CA1163627A - Bayonet tube heat exchanger - Google Patents
Bayonet tube heat exchangerInfo
- Publication number
- CA1163627A CA1163627A CA000402013A CA402013A CA1163627A CA 1163627 A CA1163627 A CA 1163627A CA 000402013 A CA000402013 A CA 000402013A CA 402013 A CA402013 A CA 402013A CA 1163627 A CA1163627 A CA 1163627A
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- CA
- Canada
- Prior art keywords
- bayonet
- tube
- sheath
- heat exchanger
- shell
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A bayonet tube heat exchanger and the method of use of the heat exchanger, the exchanger having a bayonet tube positioned within a sheath, the bayonet tube being under a vacuum. The bayonet tube removes non-condensible gases from a vapor condensing within the sheath. An alternate embodiment uses a plastic bayonet tube as an inlet for fluids into an annular passage between the bayonet tube and its sheath.
Multiple sheaths and bayonet tubes are disclosed.
A bayonet tube heat exchanger and the method of use of the heat exchanger, the exchanger having a bayonet tube positioned within a sheath, the bayonet tube being under a vacuum. The bayonet tube removes non-condensible gases from a vapor condensing within the sheath. An alternate embodiment uses a plastic bayonet tube as an inlet for fluids into an annular passage between the bayonet tube and its sheath.
Multiple sheaths and bayonet tubes are disclosed.
Description
~l 1163S~
~ I BACKGROUND OF THE INVENTION
¦l Field of the Invention ! I The present invention relates to the structure of a ¦I b,ayonet tube heat exchanger and the method of use of such I~ structure.
¦ Description of the Prior Art The structure of the so-called bayonet tube heat exchanger ¦¦ has been found to have many uses in addition to merely exchanging heat between two fluids having a heat differential.
~0 ¦ For example, the structure of the bayonet tube heat exchanger has been found useful in the condensing of fluids, purifying of fluids, and recovery of ~aluable chemicals from a fluid.
Some problems, however, ha~e de~eloped in the use of the conventional structure of the bayonet tube heat exchanger both in the traditional sense of pure heat exchange and in more sophisticated uses. For example, in'the traditional exchange o$ heat, non-condensible gases entrained in one of the fluids in~ol~ed tend to accumulate in the exchanger and to lower heat exchange efficiency.
20 jAnother problem is the tendency of the cooling fluid to il be reheated in its progress through the exchanger, thus lll reducing the efficiency of the exchanger. It is foreseen ; ', that the bayonet tube heat exchanger will find many new uses j, if the problem of reheat can be satisfactorily resol~ed.
~ I BACKGROUND OF THE INVENTION
¦l Field of the Invention ! I The present invention relates to the structure of a ¦I b,ayonet tube heat exchanger and the method of use of such I~ structure.
¦ Description of the Prior Art The structure of the so-called bayonet tube heat exchanger ¦¦ has been found to have many uses in addition to merely exchanging heat between two fluids having a heat differential.
~0 ¦ For example, the structure of the bayonet tube heat exchanger has been found useful in the condensing of fluids, purifying of fluids, and recovery of ~aluable chemicals from a fluid.
Some problems, however, ha~e de~eloped in the use of the conventional structure of the bayonet tube heat exchanger both in the traditional sense of pure heat exchange and in more sophisticated uses. For example, in'the traditional exchange o$ heat, non-condensible gases entrained in one of the fluids in~ol~ed tend to accumulate in the exchanger and to lower heat exchange efficiency.
20 jAnother problem is the tendency of the cooling fluid to il be reheated in its progress through the exchanger, thus lll reducing the efficiency of the exchanger. It is foreseen ; ', that the bayonet tube heat exchanger will find many new uses j, if the problem of reheat can be satisfactorily resol~ed.
2~ ¦l One attempt at the solution of the problem of-reheating in the bayonet tube heat exchanger-is disclosed in U.S.
~,¦ Patent No. 3,861,461. In this structure a complex double ,1l wall construction is utilized which materially increases the cost of manu~acture of the exchanger.
. .. . .
.` 2 ~
` 11~3B27 SUMMARY OF THE INVENTION
It is, therefore, a principal object of this invention to improve the efficiency of the structure of bayonet tube heat exchangers.
It is another object of the invention to automatically remove non-condensible gases from a bayonet tube heat exchanger during a heat exchange operation.
It is a still further object of the invention to provide a structure for a bayonet tube heat exchanger which minimizes reheating of a fluid which i~ being cooled.
It is an ancillary object of the invention to improve the apparatus for guiding a plurality of bayonet tubes into multiple sheaths in forming or servicing bayonet tube heat exchangers.
In accordance with an aspect of the invention there is provided a bayonet tube heat exchanger comprising:
(a) a substantially horizontal outer shell having an elongated center section, an inner end having a first tube sheet closure and a closed distal end; (b) at least one thin gauge tubular sheath having a closed end adjacent but spaced from said closed distal end of said shell and an open end facing said first tube sheet closure of said shell; (c) means for forming a first fluid flow zone between the outer surface of said sheath and said shell wherein a first fluid is boiled; ~d) a bayonet tube concentrically positioned in at least one of said sheaths, said bayonet tube piercing said first tube sheet closure, and having an outer portion extending at least through said first tube sheet closure and an inner portion terminating in an open end spaced from the closed end of said sheath; and (e) means for forming a second fluid flow zone between said bayonet tube and the inner surface of said sheath wherein a second fluid is condensed.
" 1163627 Preferably the means for forming the first fluid flow zone includes a second tube sheet closure joining the outer surfaces of the open ends of the sheaths and the inner surface of the outer shell and an inlet and outlet into the first fluid flow zone. The means for forming a second fluid flow zone preferably includes a plenum between the second tube sheet closure, the first tube sheet closure and the outer shell provided with at least one inlet and one outlet for this zone.
The bayonet tube heat exchanger of this invention in one preferred embodiment includes means for applying a vacuum source to the outer portions of the bayonet tubes, either directly to the end portions of the bayonet tubes or by use of a vacuum chamber adjacent the first tube sheet closure which is in fluid communication with a vacuum source and with the open ends of the bayonet tubes.
In accordance with one aspect of the invention, the means for forming a first fluid flow zone includes an inlet and an outlet through the shell and the means for 2Q forming the second fluid flow zone includes an inlet through each bayonet tube and an outlet through the shell.
In accordance with an aspect of the invention there is provided a method for operating a bayonet tube heat exchanger comprising: (a) forming a first fluid flow zone between the inner surface of a shell having a closed end and the outer surface of a tubular thin gauge sheath having a closed end, the closed end of the sheath being spaced from the closed end of the shell; ~b) forming a second fluid flow zone between the inner surface of the sheath and the outer surface of a bayonet tube concentrically inserted into said sheath, the inner end of said bayonet tube being open and spaced from the closed end of said -4 ~
~163627 sheath, and the outer end of said bayonet tube extending outside said second fluid flow zone; (c) causing a first ~Eluid to flow through said first fluid flow zone wherein said first fluid is boiled; (d) causing a second fluid to flow through said second fluid flow zone wherein said second fluid is condensed; and (e) applying a vacuum to the outer end of said bayonet tube for removing non-condensible gases entrained in said second fluid and accelerating fluid flow through said second fluid flow zone.
.~_ -4a-i~ 63627 ~`
l i i! A bay~net tube heat exchanger having multiple tubes ¦ may be assembled by the use of a circular plate for positioning bayonet tubes in sheaths. The circular plate has a diameter I substantially equal to the inner diameter of the shell and !1 a plurality of holes corresponding in number to the number Il of sheaths and located in the plate in corresponding relation- !
ship to the sheaths. The holes in the positioning plate have a diameter slightly larger than the bayonet tubes an~
I¦ en~ageable for sliding the open end of the bayonet tubes lQ ¦¦ through the holes and into the sheaths.
¦ The present invention overcomes the problems of conven-tional bayonet tube heat exchangers which have low heat ~ transfer efficiency and are of expensive construction. The ¦l present invention increases heat transfer rates and is a 15 ¦I si~ple and relatively inexpensive construction. In one embodiment, by using an air lance or bayonet tube to remove non-condensible gases from vapor condensing in a sheath between the bayonet tube and an outer shell, it significantly increases the efficiency of heat exchange. In another ` 20 l¦ embodiment, the invention increases heat transfer rates by using a plastic bayonet tube to prevent reheat of the cooling fluid. In this embodiment, the bayonet tube and sheath are sized to allow only a small annulus between the bayonet tube , and the sheath which creates more turbulent fluid flow, thus 1 providing higher heat transfer rates.
The invention described herein, as one of its applications, can be used in a distiller/concentrator system which is energy-efficient, reliable and which provides an effluent which can be recirculated. In addition, it may be used to recover high purity water for rinsing and valuable chemicals , for reuse. Other applications include use of the bayonet ! !
I; !
, tube heat exchanger in distillation systems, as a condenser,.
a flash e~aporator or with a freon heat pump as the heat exchanger portion of the system.
,1. BRIEF DESCRIPTION OF THE DRAWINGS
5 'I FIG. 1, is a side view, partially in section, of a single tube bayonet heat exchanger with an air lance in ` accordance with the invention;
,¦ FIG. 2 is a longitudinal cross-sectional view of a `I multiple tube embodiment of the bayonet tube heat exchanger of the invention, each tube having an air lance, FIG. 3 is a schematic drawing of a vapor rPcompression ~1 evaporator in which the bayonet tube heat exchanger of ,1 either ~IG. '. or FIG. 2 can be utilized:
,I FIG. 4 is a longitudinal cross-sectional view of a ¦ single tube bayonet tube heat exchanger having a heavy walled plastic bayonet tube;
~ F~G. 5 is an enlarged sectional view of the inner end l~ of a multiple tube embodiment of the bayonet tube heat ,I exchanger of FIG. 4 ~ith a single pass arrangement;
i FIG. 6 is an enlaxged sectional view of the inner end .~ of a multiple tube embodiment of the bayonet tube heat exchanger of FI~. 4 with a two pass water box arrangement;
FIG. 7 is a general arrangement schematic of a domestic hot water system utilizing the bayonet tube heat exchanger , of FIG. 4;
FIG. 8 is an exploded view of a guidance plate for a multiple bayonet tube heat exchanger with 2 set of bayonet tubes partially inserted into the plate.
- 11636~7 i 'i DESC~IPTION OF PREFERRED EMBODIMENTS
~' Reference will now be made in detail to the present preferred embodiments of the apparatus and methods of the ji in~ention, examples of which axe illustrated in the accom-pænying drawings.
In accordance with the invention, the bayonet tube heat ;! `
exchanger as shown in FIG. 1 includes an outer shell 10 with j an elongated center se~tion A, a tubular sheath 11 within I' the shell and a bayonet tube or air lance 12 within the 1I sheath. Shell 10 is substantially horizontal and m~y be of tubular shape. The shell has a distal end closed by an end I, cap or, as shown in FIG. 1, by a permanently closed end portion ¦1 and i~ sealed at its inner end by a first tu~e sheet closure 20.
¦I The sheath 11 has a closed distal end adjacent, but spaced 1~ from, the closed distal end of the shell 10 and an open end facing the first tube sheet 20. ~nder the in~ention, means are provided fox forming a first fluid flow zone within the Il shell surrounding the sheath. As embodied herein, such means - ! includ~ a second tube sheet 16 joining the outer surface of 1 sheath 11 and the inner surface of shell 10 to form a fluid Il chamber 22 with an inlet 13 and an outlet 14 through the shell at substantially opposite ends and opposite sides of the center section A. The second tube sheet 16 forms a fluid-tight seal between sheath 11 and the shell 10 such that fluid entering chamber 22 through inlet 13 will flow around the sheath 11 and exit through outlet 14.
The bayonet tube 12 is positioned concentrically within the sheath 11. The tube 12 pierces the first tube sheet 20 and an inner portion of the bayonet tube extends substantially the entire length of the sheath 11, terminating in an open .~, ,, .~, . , ;! 1 163627 end spaced from the closed distal end of the sheath. The l bayonet tube 12 has an outer portion which extends at least `I through the first tube sheet 20.
l In accordance with the invention, means are provided 1,! for forming a second fluid flow zone within the sheath of iil FIG. 1. As embodied herein, such means include the second ¦I tube sheet 16, first tube sheet 20, a portion of the outer shell 10 between the first and second tube sheets and the area i~ between the sheath 11 and the bayonet tube 12. This arrange-1 ment forms a fluid chamber 23 such that fluid entering inlet 15 through the portion of the shell 10 between the first and ¦ second tube sheets flows into the area between the bayonet il tube and the sheath and, as described below, may exit either ¦I through an outlet 17 through the shell 10 or the bayonet 15 1 I tube 12, or through both.
When chamber 23,-the second fluid flow zone, has a fluid, such ~s vapor or steam, introduced through inlet 15 ¦ and a first Eluid, such as a cooling liquid circulating in the first f~uid flow zone, i.e., chamber 22, the vapor in 1 chamber 23 will condense on the interior walls of chamber 23, especially within sheath 11 where there is maximum ¦¦ opportunity for heat transfer from the steam to the circulating fluid in chamber 22. The condensed vapor collects within ~' sheath 11 and would interfere with heat transfer if not ~, removed.
In a preferred embodLment, the bayonet tube 12 of the heat exchanger is operated under a vacuum. ~a~~uum increases the infiltration of air into the heat exchanger system. Air, howe~er, is a non-condensible gas under the operating conditions 3Q of these systems and tends to build up within sheath 11, l~ creating a condition detrimental to transfer of heat through the walls of the sheath.
1~l 1 163627 ~, In order to make this system more efficient, the sheath tube 11 is inclined downward toward the second tube sheet 16. The condensate collecting within sheath 11 drains into i! the portion of chamber 23 adjacent drain outlet 17 from 5 il which the condensate exi.s .he heat ex~hanger.
Additionally, the bayonet tube or air lance 12 is of considerably smaller diameter than the sheath 11 and is ! I connected to a vacuum source such as eductor 19 The air ~1 lance or bayonet tube 12 under vacuum removes the non-¦I condensible gases which tend to concentrate at the distal ¦l end of the sheath 11 and thus inhibit heat transfer. The ¦¦ air lance 12, in addition, provides a positive fluid flow drawing the steam, for example, into cham,ber 23 enabling ¦l hi~h~r flow rat~s of steam to be introduced into the exchanger.
~¦ In single tube heat exchangers, as depicted in Figure 1, the ;¦ bayonet or air lance 12, after piercing the first tube sheet I 20, may be connected directly to the eductor as shown.
i Heat is transferred, for example, from high volume l st~am condensing within the sheath 11 to circulating water 2a - I in chamber ~2. A small diameter bayonet tube, less than one-quarter the diameter of the sheath, is used to remove the relatively small volume of non-condensible gases and entrapped condensate. The small surface area of the bayonet I tube in relation to the sheath tube surfaoe area, i.e., less than about one-sixteenth, minimizes reheat losses and more importantly, provides complete evacuation of the non-condensible gases in the condensing vapor.
_~_ ~I 1163627 The condensate draining into outlet 17 can be evacuated by a loop seal drain line 18 to a "T" connection 21 with the li ~acuum line to the bayonet tube 12, as shown in Figure 1.
Il In order to provide for high heat transfer, relatively " low cost and high corrosion resistance, the sheath 11 may be constructed of a thin gauge corrosion-resistant metal such as Il titanium or some known types of aluminum alloys. The second - ,! tube sheet 16 between the sheath 11 and the shell 10 can be i l! made of the same material. When this device is used in the 1I distillation of sea water or other corrosi~e media, use of ¦l corrosion-resistant metal is extremely important. The thin ~¦~ bayonet tube or air lance 12 can be constructed of pla-~tic, copper or stainless steel since it contacts only pure steam Il or condensate and is not subject to the same corrosive 15 1ll environment as the exterior of the sheath.
¦I The first tube she-et 20 for sealing the inner end of i the shell 10 can be of plastic or carbon steel. If plastic ¦¦ is chosen, ~or the first tube sheet 20 or the bayonet tube !¦ 12, poly~inylchloride (PVC), fiberglass reinforced PV~ or chloropolyvinylchloride (CPVC) are examples of suitable materials depending upon the operating temperature of the ¦ unit. Operational temperatures must be between approximately 30 F. and 180~. for use of PVC and CPVC. The operating temperatures for a bayonet tube heat exchanger using metal ., .
.! bayonet tubes and sheaths can be considerably higher.
The bayonet tube heat exchanger of the embodiment of FTG.
l 1 of this invention is preferably operated under a vacuum, as i stated above, and is designed to prevent formation of scale which would precipitate at atmospheric boiling temperatures.
~ikewise it can pxevent the breakdown of heat sensitive chemicals by operating at lower than atmospheric boiling , ~ --10--' temperatures. In one application of this invention, a heat il exchanger is operated under a vacuum to distill sea water.
The sea water flows into chamber 22 and is ~eated by steam I flowing in chamber 23. The s~eam has a velocity of 60-100 ' feet per second tft/sec) as measured at the annulus area between 11 and 12. Using this volume of steam and operating under a vacuum of approximately 100 mm ~g absolute, the j pressure differentials between chamber 22 and 23 are very !! small and an extremely light gauge titanium sheath can be I'j used. In this application, it is also essential to remove ¦ the non-condensible gases because of their detrimental effect on heat transfer rates. This application has demonstrated ~¦ heat transfer rates of over 650 BTU/ft3/~. with a delta T
'il of only lO~F. compared to heat transfer rates of about 400 'l 3TU/ft3/~. for standard shell-and-tube type heat exchangers.
I ~IG. 2 depicts a multiple tube arrangement of the bayonet tube heat exchanger of the type described in relation il to FIG. 1. Common numerals have been used in ~IG. 2 to I' designate corresponding elemPnts in FIG~ 1. The central 'i section of the outer shell is preferably constructed of two parts 31 and 32. Each of these parts has a flange, respectively designated as 33 and 34, for providing mating surfaces which can be secured together to form a fluid tight seal as for example by bolts (not shown) about the circumference of thè
flanges. The distal end of the exchanger is preferably closed by an end head 30 which may contain a sight window for observation of the interior of the exchanger. The inner end of the exchanger is closed by another end head 35 which may be secured to part 32 of the shell by screw threads on the exterior end portion of the shell and on the interior surface of the head which mate to form fluid tight seals.
`il '` 116362`~ i A similar structure may be used for securing the e~.d head 30 ito the shell part 30.
'i In the multiple tube embodiment of FIG. ~, a plurality of `sheaths are secured to each other and to the inner wall of the shell by a second tube sheet 16a. This tube sheet may be of the Isame material as the sheaths as described above and the edges of ,¦the tube sheet secured between flanges 33 and 34. The means for ~forming the first fluid flow zone in the embodiment of FIG. 2 com-'prise the end head 30, shell part 31 and second tube sheet 16a to Iform a chamber 22a fed by an inlet 13 on one side of shell part 31 and outlet 14 preferably on the other side of this shell part. A
con~entional tube support plate or preferably a lattice grid 9 is used to ~provide even spacing of the bayonet sheaths at the distal i end~ as required by TEMA (T~bular Exchanger Manufacturexs Associa- !
1~ 1 tion). Means for forming the second fluid flow zone in the embod-¦
iment of FIG. 2, such as chamber 23a, comprise first tube sheet l'20a, second tube sheet 16a and shell part 32 with an inlet 15 .,j . .
and an outlet 17 through the shell part 32.
! I In the operation of the multiple tube embodiment, the bayo-~ `Inet t~b~s extending into each sheath pass through the first tubesheet 20a. However, rather than having indi~idual connections to ,la vacuum source, means are included for applying a vàcuum source to the outer portion of the plurality of vacuum tubes. As embod-ied herein this means, as illustrated, includes a vacuum chamber 24 formed by the first tube sheet 20a, end head 35, and the por-tion of shell 32 between .he tube sheet and the end head, the chamber having an outlet 25 adaptable for fluid communication with a vacuum source. In this arrangement the vacuum chamber 24 provides a vacuum to `the multiple bayonet tubes, each of which
~,¦ Patent No. 3,861,461. In this structure a complex double ,1l wall construction is utilized which materially increases the cost of manu~acture of the exchanger.
. .. . .
.` 2 ~
` 11~3B27 SUMMARY OF THE INVENTION
It is, therefore, a principal object of this invention to improve the efficiency of the structure of bayonet tube heat exchangers.
It is another object of the invention to automatically remove non-condensible gases from a bayonet tube heat exchanger during a heat exchange operation.
It is a still further object of the invention to provide a structure for a bayonet tube heat exchanger which minimizes reheating of a fluid which i~ being cooled.
It is an ancillary object of the invention to improve the apparatus for guiding a plurality of bayonet tubes into multiple sheaths in forming or servicing bayonet tube heat exchangers.
In accordance with an aspect of the invention there is provided a bayonet tube heat exchanger comprising:
(a) a substantially horizontal outer shell having an elongated center section, an inner end having a first tube sheet closure and a closed distal end; (b) at least one thin gauge tubular sheath having a closed end adjacent but spaced from said closed distal end of said shell and an open end facing said first tube sheet closure of said shell; (c) means for forming a first fluid flow zone between the outer surface of said sheath and said shell wherein a first fluid is boiled; ~d) a bayonet tube concentrically positioned in at least one of said sheaths, said bayonet tube piercing said first tube sheet closure, and having an outer portion extending at least through said first tube sheet closure and an inner portion terminating in an open end spaced from the closed end of said sheath; and (e) means for forming a second fluid flow zone between said bayonet tube and the inner surface of said sheath wherein a second fluid is condensed.
" 1163627 Preferably the means for forming the first fluid flow zone includes a second tube sheet closure joining the outer surfaces of the open ends of the sheaths and the inner surface of the outer shell and an inlet and outlet into the first fluid flow zone. The means for forming a second fluid flow zone preferably includes a plenum between the second tube sheet closure, the first tube sheet closure and the outer shell provided with at least one inlet and one outlet for this zone.
The bayonet tube heat exchanger of this invention in one preferred embodiment includes means for applying a vacuum source to the outer portions of the bayonet tubes, either directly to the end portions of the bayonet tubes or by use of a vacuum chamber adjacent the first tube sheet closure which is in fluid communication with a vacuum source and with the open ends of the bayonet tubes.
In accordance with one aspect of the invention, the means for forming a first fluid flow zone includes an inlet and an outlet through the shell and the means for 2Q forming the second fluid flow zone includes an inlet through each bayonet tube and an outlet through the shell.
In accordance with an aspect of the invention there is provided a method for operating a bayonet tube heat exchanger comprising: (a) forming a first fluid flow zone between the inner surface of a shell having a closed end and the outer surface of a tubular thin gauge sheath having a closed end, the closed end of the sheath being spaced from the closed end of the shell; ~b) forming a second fluid flow zone between the inner surface of the sheath and the outer surface of a bayonet tube concentrically inserted into said sheath, the inner end of said bayonet tube being open and spaced from the closed end of said -4 ~
~163627 sheath, and the outer end of said bayonet tube extending outside said second fluid flow zone; (c) causing a first ~Eluid to flow through said first fluid flow zone wherein said first fluid is boiled; (d) causing a second fluid to flow through said second fluid flow zone wherein said second fluid is condensed; and (e) applying a vacuum to the outer end of said bayonet tube for removing non-condensible gases entrained in said second fluid and accelerating fluid flow through said second fluid flow zone.
.~_ -4a-i~ 63627 ~`
l i i! A bay~net tube heat exchanger having multiple tubes ¦ may be assembled by the use of a circular plate for positioning bayonet tubes in sheaths. The circular plate has a diameter I substantially equal to the inner diameter of the shell and !1 a plurality of holes corresponding in number to the number Il of sheaths and located in the plate in corresponding relation- !
ship to the sheaths. The holes in the positioning plate have a diameter slightly larger than the bayonet tubes an~
I¦ en~ageable for sliding the open end of the bayonet tubes lQ ¦¦ through the holes and into the sheaths.
¦ The present invention overcomes the problems of conven-tional bayonet tube heat exchangers which have low heat ~ transfer efficiency and are of expensive construction. The ¦l present invention increases heat transfer rates and is a 15 ¦I si~ple and relatively inexpensive construction. In one embodiment, by using an air lance or bayonet tube to remove non-condensible gases from vapor condensing in a sheath between the bayonet tube and an outer shell, it significantly increases the efficiency of heat exchange. In another ` 20 l¦ embodiment, the invention increases heat transfer rates by using a plastic bayonet tube to prevent reheat of the cooling fluid. In this embodiment, the bayonet tube and sheath are sized to allow only a small annulus between the bayonet tube , and the sheath which creates more turbulent fluid flow, thus 1 providing higher heat transfer rates.
The invention described herein, as one of its applications, can be used in a distiller/concentrator system which is energy-efficient, reliable and which provides an effluent which can be recirculated. In addition, it may be used to recover high purity water for rinsing and valuable chemicals , for reuse. Other applications include use of the bayonet ! !
I; !
, tube heat exchanger in distillation systems, as a condenser,.
a flash e~aporator or with a freon heat pump as the heat exchanger portion of the system.
,1. BRIEF DESCRIPTION OF THE DRAWINGS
5 'I FIG. 1, is a side view, partially in section, of a single tube bayonet heat exchanger with an air lance in ` accordance with the invention;
,¦ FIG. 2 is a longitudinal cross-sectional view of a `I multiple tube embodiment of the bayonet tube heat exchanger of the invention, each tube having an air lance, FIG. 3 is a schematic drawing of a vapor rPcompression ~1 evaporator in which the bayonet tube heat exchanger of ,1 either ~IG. '. or FIG. 2 can be utilized:
,I FIG. 4 is a longitudinal cross-sectional view of a ¦ single tube bayonet tube heat exchanger having a heavy walled plastic bayonet tube;
~ F~G. 5 is an enlarged sectional view of the inner end l~ of a multiple tube embodiment of the bayonet tube heat ,I exchanger of FIG. 4 ~ith a single pass arrangement;
i FIG. 6 is an enlaxged sectional view of the inner end .~ of a multiple tube embodiment of the bayonet tube heat exchanger of FI~. 4 with a two pass water box arrangement;
FIG. 7 is a general arrangement schematic of a domestic hot water system utilizing the bayonet tube heat exchanger , of FIG. 4;
FIG. 8 is an exploded view of a guidance plate for a multiple bayonet tube heat exchanger with 2 set of bayonet tubes partially inserted into the plate.
- 11636~7 i 'i DESC~IPTION OF PREFERRED EMBODIMENTS
~' Reference will now be made in detail to the present preferred embodiments of the apparatus and methods of the ji in~ention, examples of which axe illustrated in the accom-pænying drawings.
In accordance with the invention, the bayonet tube heat ;! `
exchanger as shown in FIG. 1 includes an outer shell 10 with j an elongated center se~tion A, a tubular sheath 11 within I' the shell and a bayonet tube or air lance 12 within the 1I sheath. Shell 10 is substantially horizontal and m~y be of tubular shape. The shell has a distal end closed by an end I, cap or, as shown in FIG. 1, by a permanently closed end portion ¦1 and i~ sealed at its inner end by a first tu~e sheet closure 20.
¦I The sheath 11 has a closed distal end adjacent, but spaced 1~ from, the closed distal end of the shell 10 and an open end facing the first tube sheet 20. ~nder the in~ention, means are provided fox forming a first fluid flow zone within the Il shell surrounding the sheath. As embodied herein, such means - ! includ~ a second tube sheet 16 joining the outer surface of 1 sheath 11 and the inner surface of shell 10 to form a fluid Il chamber 22 with an inlet 13 and an outlet 14 through the shell at substantially opposite ends and opposite sides of the center section A. The second tube sheet 16 forms a fluid-tight seal between sheath 11 and the shell 10 such that fluid entering chamber 22 through inlet 13 will flow around the sheath 11 and exit through outlet 14.
The bayonet tube 12 is positioned concentrically within the sheath 11. The tube 12 pierces the first tube sheet 20 and an inner portion of the bayonet tube extends substantially the entire length of the sheath 11, terminating in an open .~, ,, .~, . , ;! 1 163627 end spaced from the closed distal end of the sheath. The l bayonet tube 12 has an outer portion which extends at least `I through the first tube sheet 20.
l In accordance with the invention, means are provided 1,! for forming a second fluid flow zone within the sheath of iil FIG. 1. As embodied herein, such means include the second ¦I tube sheet 16, first tube sheet 20, a portion of the outer shell 10 between the first and second tube sheets and the area i~ between the sheath 11 and the bayonet tube 12. This arrange-1 ment forms a fluid chamber 23 such that fluid entering inlet 15 through the portion of the shell 10 between the first and ¦ second tube sheets flows into the area between the bayonet il tube and the sheath and, as described below, may exit either ¦I through an outlet 17 through the shell 10 or the bayonet 15 1 I tube 12, or through both.
When chamber 23,-the second fluid flow zone, has a fluid, such ~s vapor or steam, introduced through inlet 15 ¦ and a first Eluid, such as a cooling liquid circulating in the first f~uid flow zone, i.e., chamber 22, the vapor in 1 chamber 23 will condense on the interior walls of chamber 23, especially within sheath 11 where there is maximum ¦¦ opportunity for heat transfer from the steam to the circulating fluid in chamber 22. The condensed vapor collects within ~' sheath 11 and would interfere with heat transfer if not ~, removed.
In a preferred embodLment, the bayonet tube 12 of the heat exchanger is operated under a vacuum. ~a~~uum increases the infiltration of air into the heat exchanger system. Air, howe~er, is a non-condensible gas under the operating conditions 3Q of these systems and tends to build up within sheath 11, l~ creating a condition detrimental to transfer of heat through the walls of the sheath.
1~l 1 163627 ~, In order to make this system more efficient, the sheath tube 11 is inclined downward toward the second tube sheet 16. The condensate collecting within sheath 11 drains into i! the portion of chamber 23 adjacent drain outlet 17 from 5 il which the condensate exi.s .he heat ex~hanger.
Additionally, the bayonet tube or air lance 12 is of considerably smaller diameter than the sheath 11 and is ! I connected to a vacuum source such as eductor 19 The air ~1 lance or bayonet tube 12 under vacuum removes the non-¦I condensible gases which tend to concentrate at the distal ¦l end of the sheath 11 and thus inhibit heat transfer. The ¦¦ air lance 12, in addition, provides a positive fluid flow drawing the steam, for example, into cham,ber 23 enabling ¦l hi~h~r flow rat~s of steam to be introduced into the exchanger.
~¦ In single tube heat exchangers, as depicted in Figure 1, the ;¦ bayonet or air lance 12, after piercing the first tube sheet I 20, may be connected directly to the eductor as shown.
i Heat is transferred, for example, from high volume l st~am condensing within the sheath 11 to circulating water 2a - I in chamber ~2. A small diameter bayonet tube, less than one-quarter the diameter of the sheath, is used to remove the relatively small volume of non-condensible gases and entrapped condensate. The small surface area of the bayonet I tube in relation to the sheath tube surfaoe area, i.e., less than about one-sixteenth, minimizes reheat losses and more importantly, provides complete evacuation of the non-condensible gases in the condensing vapor.
_~_ ~I 1163627 The condensate draining into outlet 17 can be evacuated by a loop seal drain line 18 to a "T" connection 21 with the li ~acuum line to the bayonet tube 12, as shown in Figure 1.
Il In order to provide for high heat transfer, relatively " low cost and high corrosion resistance, the sheath 11 may be constructed of a thin gauge corrosion-resistant metal such as Il titanium or some known types of aluminum alloys. The second - ,! tube sheet 16 between the sheath 11 and the shell 10 can be i l! made of the same material. When this device is used in the 1I distillation of sea water or other corrosi~e media, use of ¦l corrosion-resistant metal is extremely important. The thin ~¦~ bayonet tube or air lance 12 can be constructed of pla-~tic, copper or stainless steel since it contacts only pure steam Il or condensate and is not subject to the same corrosive 15 1ll environment as the exterior of the sheath.
¦I The first tube she-et 20 for sealing the inner end of i the shell 10 can be of plastic or carbon steel. If plastic ¦¦ is chosen, ~or the first tube sheet 20 or the bayonet tube !¦ 12, poly~inylchloride (PVC), fiberglass reinforced PV~ or chloropolyvinylchloride (CPVC) are examples of suitable materials depending upon the operating temperature of the ¦ unit. Operational temperatures must be between approximately 30 F. and 180~. for use of PVC and CPVC. The operating temperatures for a bayonet tube heat exchanger using metal ., .
.! bayonet tubes and sheaths can be considerably higher.
The bayonet tube heat exchanger of the embodiment of FTG.
l 1 of this invention is preferably operated under a vacuum, as i stated above, and is designed to prevent formation of scale which would precipitate at atmospheric boiling temperatures.
~ikewise it can pxevent the breakdown of heat sensitive chemicals by operating at lower than atmospheric boiling , ~ --10--' temperatures. In one application of this invention, a heat il exchanger is operated under a vacuum to distill sea water.
The sea water flows into chamber 22 and is ~eated by steam I flowing in chamber 23. The s~eam has a velocity of 60-100 ' feet per second tft/sec) as measured at the annulus area between 11 and 12. Using this volume of steam and operating under a vacuum of approximately 100 mm ~g absolute, the j pressure differentials between chamber 22 and 23 are very !! small and an extremely light gauge titanium sheath can be I'j used. In this application, it is also essential to remove ¦ the non-condensible gases because of their detrimental effect on heat transfer rates. This application has demonstrated ~¦ heat transfer rates of over 650 BTU/ft3/~. with a delta T
'il of only lO~F. compared to heat transfer rates of about 400 'l 3TU/ft3/~. for standard shell-and-tube type heat exchangers.
I ~IG. 2 depicts a multiple tube arrangement of the bayonet tube heat exchanger of the type described in relation il to FIG. 1. Common numerals have been used in ~IG. 2 to I' designate corresponding elemPnts in FIG~ 1. The central 'i section of the outer shell is preferably constructed of two parts 31 and 32. Each of these parts has a flange, respectively designated as 33 and 34, for providing mating surfaces which can be secured together to form a fluid tight seal as for example by bolts (not shown) about the circumference of thè
flanges. The distal end of the exchanger is preferably closed by an end head 30 which may contain a sight window for observation of the interior of the exchanger. The inner end of the exchanger is closed by another end head 35 which may be secured to part 32 of the shell by screw threads on the exterior end portion of the shell and on the interior surface of the head which mate to form fluid tight seals.
`il '` 116362`~ i A similar structure may be used for securing the e~.d head 30 ito the shell part 30.
'i In the multiple tube embodiment of FIG. ~, a plurality of `sheaths are secured to each other and to the inner wall of the shell by a second tube sheet 16a. This tube sheet may be of the Isame material as the sheaths as described above and the edges of ,¦the tube sheet secured between flanges 33 and 34. The means for ~forming the first fluid flow zone in the embodiment of FIG. 2 com-'prise the end head 30, shell part 31 and second tube sheet 16a to Iform a chamber 22a fed by an inlet 13 on one side of shell part 31 and outlet 14 preferably on the other side of this shell part. A
con~entional tube support plate or preferably a lattice grid 9 is used to ~provide even spacing of the bayonet sheaths at the distal i end~ as required by TEMA (T~bular Exchanger Manufacturexs Associa- !
1~ 1 tion). Means for forming the second fluid flow zone in the embod-¦
iment of FIG. 2, such as chamber 23a, comprise first tube sheet l'20a, second tube sheet 16a and shell part 32 with an inlet 15 .,j . .
and an outlet 17 through the shell part 32.
! I In the operation of the multiple tube embodiment, the bayo-~ `Inet t~b~s extending into each sheath pass through the first tubesheet 20a. However, rather than having indi~idual connections to ,la vacuum source, means are included for applying a vàcuum source to the outer portion of the plurality of vacuum tubes. As embod-ied herein this means, as illustrated, includes a vacuum chamber 24 formed by the first tube sheet 20a, end head 35, and the por-tion of shell 32 between .he tube sheet and the end head, the chamber having an outlet 25 adaptable for fluid communication with a vacuum source. In this arrangement the vacuum chamber 24 provides a vacuum to `the multiple bayonet tubes, each of which
3~ passes through the first tube sheet 20a and opens into the ~ ~ vacuum ch~mber.
I :
- FIG. 3 depicts an application of the bayonet tube heat exchanger o~ FIG~ 2 in a vapor recompression evaporator designed or high vacuum operation. This arrangement prevènts the forma-tion of scale which is precipitated at atmospheric boiling temp-eratures and is also useful in preventing t~e breakdown of heat ; sensitive chemicals. In this applic~tion, ~he bayonet tube heat exchanger 40 is fed from feed tank 41 through fluid line 42 and l inlet 13 into the heat exchanger. (The same reference numerals i, as used in FIGS. 1 and 2 are used in F~G. 3 where appropriàte.) I` After flowing through the first fluid flow zone, i.e., chamber 22, surrounding the sheaths, tube, the fluid feed exits the heat exchanger 40 in a heated condition via outlets 14 and is l,l conducted by wet vapor uptakes 43 into vapor separator 44. The ¦1 ~a~or separator has a series of mesh demistors 45 to entrain liquid droplets which drain to the bottom of the separator 44 and are returned to the feed tank 41 via fluid communication line 46 11 and pump 47 or taken of as concentrate via fluid communication ! ¦ line 48. The vapor separator is connected by outlet 49 at its upper end to suction vapor delivery line 50 and then to a vapor i compressor 51. This vapor compressor 51 pressurizes the ~apor ~0 , and the pressurized vapor, exiting the compressor at its lower end, is delivered to inlet 15 of the heat exchanger 40 via.pipe l, 52. The pressurized vapor flows into the second fluid flow zone ; I! i.e., chamber 23a of the embodiment of the heat exchanger, as de-picted in FIG. 2. The flow rate of Yapor is from about 60-100 ft/sec, as measured at the area of the combined annuli. The v por condenses in sheaths 11 as heat is transferred through the sheath walls to the cooler feed fluid flowing through chamber 23a The vapor sweeps non-condensible gases (e.g., air) to the distal end of the sheaths 11 where the bayonet tubes 12, connected via vacuum chamber 24 and outlet 25 to a vacuum line, continuously ., ~.. ~........ ...
`i ' 1 163627 ` i siphon the non-condensible gases off. As the vapor condenses ,~, in sheaths 11, the condensate drains individually from each sheath by the pitch of the sheaths toward the first tube sheet 20a. Thus, the condensate does not drop down and l, build up on the lower tube banks to form films of condensate ,, which would blanket the tubes and decrease the heat transfer . .
efficiency.
The condensate drains from the heat exchanger through , drain line 18 which joins the vacuum line exiting from the , vacuum chamber 24 at a "T" junction 21. The condensate is then pumped to the distillate tank 53 through fluid line 54 il running from the eductor 19 to the dis~illate tank.
The vapor compression e~aporator, as described above, ,~ can operate under low temperature and high ~acuum conditions.
'I This permits the use of CPVC for piping, evaporator and ,i condensor shells. In addition to reducing construction costs, CPV~ is immune to the corrosive effects of salt water and other mediums such as chromic acid solutions formed in ', electroplating wastes.
20 ',' Another embodiment of the in~ention, as depicted FIG. 4, has a thi~k walled insulating bayonet tube within a thin walled sheath. This embodiment permits the transfer of heat from boiling fluids to circulating hot water or from condensing steam to circulating cooling water with high ~5 efficiency. The bayonet tube heat exchanger 60 of FIG. 4 has an outer shell 61 with an elongated center section A, a tubular sheath 6~ within the shell and a bayonet tube 66 within the sheath. Shell 60 is substantially horizontal and as depicted, is of tubular shape. The shell has a distal end 61 which may be closed by an end head as described abo~e in relation to FIG.
,` :
I' 1163S27 il 2 or by a permanently closed end portion as shown in FIG. 4.
The shell is sealed at its inner end by first tube sheet 68. Sheath 65 has a closed dlstal end adjacent, but spaced ¦ from, the closed distal end of shell 61 and an open end !11 facing first tube sheet 68. In accordance with the in~ention, means are pro~ided for forming a first fluid flow zone within the shell surrounding the sheath. Such means, as ¦' embodied herein, include a tube sheet 78 joining the outer Ij surface of sheath 65 to the inner surface of shell 60 to 1I form a fluid chamber 64 with at least one inlet 62 through Il the shell and at least one outlet 63 through the shell, both ¦I being between the tube sheet 78 and the distal end of the I shell. The tube sheet 78 forms a fluid tight seal at the ¦ inner end of chamber 64 such that fluid entering inlet 62 15 ¦I flows around sheath 65 and exits through outlet 63.
The bayonet tube 66 is positioned concentrically within ', the sheath 65. The bayone~ tube 66 pierces the tube sheet 68 and an inner portion of the bayonet tube extends substan-¦ tially the entire length of the sheath 65, terminating in an 20 -¦ open end spaced from the closed distal end of thr sheath. `, The bayonet tube 65 has an outer portion which extends ¦I through first tube sheet 68. In the single tube embodiment shown in FIG. 4, the bayonet tube is threaded into the Il interior portion of a double tapped bushing 67 which extends I through tube sheet 68 and which is suitable for fluid tight connection to a fluid source at its exterior portion.
In accordance with the in~ention, means are also provided for forming a second fluid flow zone within the sheath 65.
Such means, as embodied herein, include second tube sheet 78, first tube sheet 68 and a portion of the outer shell 60 . ~.~ ,, ,.. ~.. . .
~ -15-, -between the first and second tube sheets, as well as the ~ area between the sheath 65 and the bayonet tube 66. These 'i elements define a fluid chamber 71 such that fluid entering i through bayonet tube 66 flows along the length of the bayonet I tube to the distal end of sheath 65 and flows through the I annulus between the bayonet tube and the sheath and exits at ,1 outlet 72 located in shell 61 between tube sheet 78 and tube `¦ sheet 68.
~, In order to minimize reheat of the fluid in the second , fluid flow zone, the bayonet tube in this embodimet is '¦ constructed of an insulating material such as plastic. Both ,¦ PVC and CPVC have been ~ound to be suitable materials due to ,I their low cost and the ease with which they may be worked.
tl The sheath 65 and the tube sheet 78 may be made of '¦ light gauge titanium or other corrosion resistant metal as described in relation to FIGS. 1 and 2.
In order to position the bayonet 66 within the sheath 65, the invention, means are pro~ided such that a relatively ~ uniform annular passage surrounds the bayonet. It is preferred 20 I to affix metal wires or pins 90 extending radially from the~ i ~¦ bayonet ~ube at equal distance spacings (about 120 àpart~around ¦ the circumference of the bayonet tube. These pins 90 extend from at least the outer surface of the bayonet tube for a ' dîstance as necessary to contact the inner surface of the , sheath 65. Pins 90 may be spaced at one or more locations along bayonet tube 65 depending upon the length of the , bayonet tube.
In order to reduce entrance drag at the end of the bayonet tube 66 where the fluid flows from the bayonet tubes into the small annular passage between the bayonet tube 66 and .
the sheath 65, it is preferred to bevel the outer surface of - the end of the bayonet tube as best shown in FIG. 4.
` `` 1 163627 , The plastic bayonet tube of the invention effectively pre~ents reheating by its insulating quality. The optimum , parameters found for this embodiment of the in~ention uses a I one-inch OD (outer diameter) tube of 0.035 wall thickness , for the sheath and a 1/2 inch ips (iron pipe size) (0.84 inch OD) Schedule 80 (0.147 inch) PVC or CPVC tube for the ~, bayonet tube. The preferred inside cross-sectional area of I the sheath is 0.679 square inches and the outside cross-sectional , area of the bayonet is 0.554 square inches lea~ing an annular j passage surrounding the bayonet of 0.125 square inches in ,I cross-section or about 18 percent of the total area inside of the sheath. A flow rate through each such bayonet tube ,~-of two ~allons of liquid per minute provides a velocity of ¦ 5.1 feet per second through the annular passage surrounding I the bayonet. This smali annular passage and the relatively l high flow velocity creates a high turbulence in the fluid in ¦ the annular passage which promotes overall heat transfer 'I rates of 600-800 Btu/cf/F. at the high vacuums at which I these h~at exchanges are operated. The sheath preferably may I range in OD from 75" to 1.5" and the bayonet tube from 0.5~
to 1.25~" The wall thicknesses of the sheath and the bayonet tube can be determined by the intended application but it is preferred that an annular passage with an area of about 18 ; percent of the total area within the sheath be maintained for the most effective heat transfer rates.
In a multiple tube heat exchanger as shown in FIG. 5, the plastic bayonet tubes 66 may be adhered to plastic tube sheet 69 while a metal tube sheet 78 is used to seal the sheath tubes 65 to each other and to the outer shell. In 3n this embodiment, the tube sheet 78 is sealed between flanges 11 75 and 76 of outer shell sections 73 and 74 respectively.
1163627 ``
Il ~n inlet fluid plenum 70 is formed by a portion of outer i! shell section 74 between tube sheet 69 and an end head 77.
Fluid enters the plenum 70 through inlet 79 positioned in Il the wall of shell section 74 between tube sheet 69 and end i head 77. A similar inlet plenum is unnecessary in the il single tube embodiment of FIG. 4 since the bayonet tube 66 ¦ extends into a bushing 67 through tube sheet 68 providing a ¦¦ direct connection to a fluid supply line.
The embodiment of FIG. 5 of a bayonet tube heat exchanger ¦ of the invention in addition to providing high heat transfer rates, cost effectiveness in construction and operation and compact arrangement performs functions which would be impossible `
or quit,e expensive in standard heat exch~nger constructions.
I For example, a "U" tube design would not be able to use the 1 light gauge corrosion resistant metals found in this invention ¦¦ since such materials are al st impossible to bend to a l short radius. Further, sm~ller tube diameters ha~e to be ! used in conventional construction to provide necessary tube l ~elocities for good heat transfer rates. The use of 0.5~ to i 1.25" OD bayonet tubes and 0.75" to 1.5" OD sheaths in this ¦l invention, in addition to being economical tube sizes, also l! pro~ides optimum water flow velocities without use of much smaller tubes and attendant increase in the number of dri holes and construction costs.
25 ,l A further preferred embodiment of a multiple bayonet tube heat exchanger is depicted in Fig. 6. This embodiment has a two-pass water box -rrangement wherein one or more bayonet tubes 83 and one or more bayonet tubes 87 rather than connecting to a single plenum 71 as in FIG. 5, connect , to two plenums 80 and 31. Thus, the second fluid flow zone .: .~ .~.. . .
!` ( ' 1163627 `
has fluid entering plenum 80 through inlet 82 through a tube sheel 91 from which it enters at least one bayonet tube 83 which is in fluid com~unication with plenum 80. This fluid travels ,l the length of the ~ayonet tube 83 and returns through annular 5 li passage 84 between the bayonet tube and its sheath 89 into 1'1 chamber 85. Fluid entering chamber 85 r which is formed by li tube sheet 78a, tube sheet 69a and shell section 74a, then travels into annular passage 86 surrounding bayonet tube 87 Il and exits down at least one bayonet tube 87 which is in ll fluid communication with plenum 81 and exits through outlet ~¦ 88. This arrangement increases the water velocities through the heat exchanger. Such velocities may be further increased ¦ by adding additional passes.
¦¦ FIG. 7 pro~ides an illustration of one application of 1¦ the embodiment of the bayonet tube heat exchanger described in relation to FIG. 4. The heat exchanger can be coupled with a domestic hot-water heater to produce low cost potable water from contaminated well water. Water from the hot I water ~ank 100, e., a first fluid, is supplied via fluid I line 114 to the inlet 62 feeding the first fluid flow zone of bayonet tube heat exchanger 101 to be further heated. 1, i! Additional water from tank 100 is supplied via ~luid line ' ~l 115 and pump 116 to inlet 67 feeding the second fluid flow ~l~ zone of bayonet tube heat exchanger 102. A second fluid ~' in~roduced through inlet 67 feeding the second fluid flow zone of heat exchanger 101 is heated by an auxiliary electric heater 104 in heater loop 103 serviced by pump 117. The heated fluid entering inlet 67 from loop 103 exits the heat 1 exchanger 101 at outlet 72 and recirculates thro~gh the , heater loop after giving up its heat to the water in the first fluid flow zone.
` `` 1163627 The heated water and water Yapor from the first fluid ~lo~ zone exits from outlet 63 and flows through pipe 105 to ~apor separator 106. The liquid water in the separator 106, ' which contains concentrated pollutants, drains through .5 outlet 107 to drain line 108 and is pumped away by pump 118.
The vapor at about 165~. from the upper end of separator 106 is introduced via fluid line 119 into the inlet 62 feeding the first fluid flow zone of bayonet tube heat exchanger ' 102. The water entering heat exchanger 102 from tank 100 , through inlet 67 feeding the second fluid flow zone of exchanger j 'll 102 causes the ~apor in the first fluid flow zone to condense~
i Distilled water is taken off through outlet 109 which communi- i1 cates with the first fluid flow zone. The distillate is pumped 11 via fluid line 110 connected to a wet vacuum pump 111.
1l The water exiting heat exchanger 102 through outlet 72 Il is at a t~mperature of 120-140F. and returns via fluid line - l, 112 to a valve 113 which directs it through the household hot water system or returns it to the hot water tank 100. With ', this system, using single tube bayonet tube heat exchangers of 2~ . the type depicted in FIG. 4, for every twelve gallons of , water raised 80F~, one gallon of distilled water can be ,~ produced for less than 1/8 of a KW for pumping costs. This application can also be used for a small electroplating set up to concentrate and recover plating wastes. The ganged pumping system used is described in U.S. Patent No. 3,358,609.
In order to assemble the multiple tube bayonet tube heat exchangers, as depicted in FIG. 2, especially when there are dozens or hundreds of bayonet tubes involved, a guidance means is provided to permit the bayonet tubes to be aligned with their corresponding sheath tubes. As depicted in FIG. 8, a circùlar plate 120 is provided with holes 121. The number of holes at least equals the number of bayonet tubes used in the heat exchanger in which such guidance plate is employed. The plate may be of plastic or metal depending upon the operating temperature range of the heat exchanger in which it is used. The holes 121 are positioned to correspond with the openings of the sheaths in the second tube sheet 16a. As depicted in FIG. 2, the plate 1~0 is dimensioned to fit within the outer shell of the heat exchanger and is held a distance away from tube sheet 16a by positioning rods 122. The holes in plate 120 are slightly larger than the diameter of the bayonets in order to enable the bayonets to slide freely through the positioning holes and into the sheath tubes.
In operation, the free ends of the bayonet tubes are inserted into holes 121 in plate 120 and the plate is aligned with the sheath tubes 11. Then, by pushing the bayonet tube sheet, the bayonet tubes slide through the plate 120 and along the length of sheath tubes 11 until the positioning rods 122 contact the sheath tube sheet 16a.
This plate enables the proper positioning of the bayonets upon insertion and maintains them in proper spaced relationship upon removal of the bayonet tubes from the heat exchanger.
Other applications and modifications of this invention will be obvious to one skilled in the art of heat exchangers. Such applications may include the use of the bayonet tube heat exchanger with a climbing film evaporator in conjuction with a Freon (trade mark) heat pump with secondary heat transfer loops using distilled water to prevent transfer of radioactivity from the concentration of radioactive wastes. Reference to 1 16362~
Williamson U.S. Patent Nos. 3,248,305; 3,399,118; 3,420,747 will furnish further details as to applications particularly as they would apply of a freon pump.
The freon condenser of the heat pump can employ the bayonet tube heat exchanger ~sing enhanced tubing for the sheath. Finned or twisted tubes similar to those described in U.S. Patent No. 3,533,267 can be used to condense the freon vapors on the outside of the sheath and transfer heat to distilled water, or other liquid to be heated~ in the annulus between the sheath and the insulating bayonet.
The bayonet tube heat exchanger may be used with a long tube flash evaporator of the type depicted in Williamson U.S. Patent No. 3,186,924 and would be particularly advantageous. The bayonet tube heat exchanger could replace the condenser portion identified as 22 in the 3,186,924 patent and would reduce the length of the heat recovery condenser in half and eliminate any problem with expansion stresses. For example, a long tube flash evaporator requiring 1/2" O~ tubes in order to acquire optimum tube velocity could use 1" OD bayonet sheaths and insulating bayonet t~bes providing the small annuli area which would require half the length heat transfer tube in order to acquire the same square feet of heat transfer surfaces with the same tube velocities. The number of tube holes to be drilled would be greatly reduced and save in tubing and fabrication costs. The division plates 45 in the patent 3,186,924 can be part of the new removable bayonet tube bundle and would eliminate the need for flanging sections 41.
It is intended that modifications and variations of the above embodiments can be made within the scope of this invention as defined by the appended claims and their equivalents.
~.,
I :
- FIG. 3 depicts an application of the bayonet tube heat exchanger o~ FIG~ 2 in a vapor recompression evaporator designed or high vacuum operation. This arrangement prevènts the forma-tion of scale which is precipitated at atmospheric boiling temp-eratures and is also useful in preventing t~e breakdown of heat ; sensitive chemicals. In this applic~tion, ~he bayonet tube heat exchanger 40 is fed from feed tank 41 through fluid line 42 and l inlet 13 into the heat exchanger. (The same reference numerals i, as used in FIGS. 1 and 2 are used in F~G. 3 where appropriàte.) I` After flowing through the first fluid flow zone, i.e., chamber 22, surrounding the sheaths, tube, the fluid feed exits the heat exchanger 40 in a heated condition via outlets 14 and is l,l conducted by wet vapor uptakes 43 into vapor separator 44. The ¦1 ~a~or separator has a series of mesh demistors 45 to entrain liquid droplets which drain to the bottom of the separator 44 and are returned to the feed tank 41 via fluid communication line 46 11 and pump 47 or taken of as concentrate via fluid communication ! ¦ line 48. The vapor separator is connected by outlet 49 at its upper end to suction vapor delivery line 50 and then to a vapor i compressor 51. This vapor compressor 51 pressurizes the ~apor ~0 , and the pressurized vapor, exiting the compressor at its lower end, is delivered to inlet 15 of the heat exchanger 40 via.pipe l, 52. The pressurized vapor flows into the second fluid flow zone ; I! i.e., chamber 23a of the embodiment of the heat exchanger, as de-picted in FIG. 2. The flow rate of Yapor is from about 60-100 ft/sec, as measured at the area of the combined annuli. The v por condenses in sheaths 11 as heat is transferred through the sheath walls to the cooler feed fluid flowing through chamber 23a The vapor sweeps non-condensible gases (e.g., air) to the distal end of the sheaths 11 where the bayonet tubes 12, connected via vacuum chamber 24 and outlet 25 to a vacuum line, continuously ., ~.. ~........ ...
`i ' 1 163627 ` i siphon the non-condensible gases off. As the vapor condenses ,~, in sheaths 11, the condensate drains individually from each sheath by the pitch of the sheaths toward the first tube sheet 20a. Thus, the condensate does not drop down and l, build up on the lower tube banks to form films of condensate ,, which would blanket the tubes and decrease the heat transfer . .
efficiency.
The condensate drains from the heat exchanger through , drain line 18 which joins the vacuum line exiting from the , vacuum chamber 24 at a "T" junction 21. The condensate is then pumped to the distillate tank 53 through fluid line 54 il running from the eductor 19 to the dis~illate tank.
The vapor compression e~aporator, as described above, ,~ can operate under low temperature and high ~acuum conditions.
'I This permits the use of CPVC for piping, evaporator and ,i condensor shells. In addition to reducing construction costs, CPV~ is immune to the corrosive effects of salt water and other mediums such as chromic acid solutions formed in ', electroplating wastes.
20 ',' Another embodiment of the in~ention, as depicted FIG. 4, has a thi~k walled insulating bayonet tube within a thin walled sheath. This embodiment permits the transfer of heat from boiling fluids to circulating hot water or from condensing steam to circulating cooling water with high ~5 efficiency. The bayonet tube heat exchanger 60 of FIG. 4 has an outer shell 61 with an elongated center section A, a tubular sheath 6~ within the shell and a bayonet tube 66 within the sheath. Shell 60 is substantially horizontal and as depicted, is of tubular shape. The shell has a distal end 61 which may be closed by an end head as described abo~e in relation to FIG.
,` :
I' 1163S27 il 2 or by a permanently closed end portion as shown in FIG. 4.
The shell is sealed at its inner end by first tube sheet 68. Sheath 65 has a closed dlstal end adjacent, but spaced ¦ from, the closed distal end of shell 61 and an open end !11 facing first tube sheet 68. In accordance with the in~ention, means are pro~ided for forming a first fluid flow zone within the shell surrounding the sheath. Such means, as ¦' embodied herein, include a tube sheet 78 joining the outer Ij surface of sheath 65 to the inner surface of shell 60 to 1I form a fluid chamber 64 with at least one inlet 62 through Il the shell and at least one outlet 63 through the shell, both ¦I being between the tube sheet 78 and the distal end of the I shell. The tube sheet 78 forms a fluid tight seal at the ¦ inner end of chamber 64 such that fluid entering inlet 62 15 ¦I flows around sheath 65 and exits through outlet 63.
The bayonet tube 66 is positioned concentrically within ', the sheath 65. The bayone~ tube 66 pierces the tube sheet 68 and an inner portion of the bayonet tube extends substan-¦ tially the entire length of the sheath 65, terminating in an 20 -¦ open end spaced from the closed distal end of thr sheath. `, The bayonet tube 65 has an outer portion which extends ¦I through first tube sheet 68. In the single tube embodiment shown in FIG. 4, the bayonet tube is threaded into the Il interior portion of a double tapped bushing 67 which extends I through tube sheet 68 and which is suitable for fluid tight connection to a fluid source at its exterior portion.
In accordance with the in~ention, means are also provided for forming a second fluid flow zone within the sheath 65.
Such means, as embodied herein, include second tube sheet 78, first tube sheet 68 and a portion of the outer shell 60 . ~.~ ,, ,.. ~.. . .
~ -15-, -between the first and second tube sheets, as well as the ~ area between the sheath 65 and the bayonet tube 66. These 'i elements define a fluid chamber 71 such that fluid entering i through bayonet tube 66 flows along the length of the bayonet I tube to the distal end of sheath 65 and flows through the I annulus between the bayonet tube and the sheath and exits at ,1 outlet 72 located in shell 61 between tube sheet 78 and tube `¦ sheet 68.
~, In order to minimize reheat of the fluid in the second , fluid flow zone, the bayonet tube in this embodimet is '¦ constructed of an insulating material such as plastic. Both ,¦ PVC and CPVC have been ~ound to be suitable materials due to ,I their low cost and the ease with which they may be worked.
tl The sheath 65 and the tube sheet 78 may be made of '¦ light gauge titanium or other corrosion resistant metal as described in relation to FIGS. 1 and 2.
In order to position the bayonet 66 within the sheath 65, the invention, means are pro~ided such that a relatively ~ uniform annular passage surrounds the bayonet. It is preferred 20 I to affix metal wires or pins 90 extending radially from the~ i ~¦ bayonet ~ube at equal distance spacings (about 120 àpart~around ¦ the circumference of the bayonet tube. These pins 90 extend from at least the outer surface of the bayonet tube for a ' dîstance as necessary to contact the inner surface of the , sheath 65. Pins 90 may be spaced at one or more locations along bayonet tube 65 depending upon the length of the , bayonet tube.
In order to reduce entrance drag at the end of the bayonet tube 66 where the fluid flows from the bayonet tubes into the small annular passage between the bayonet tube 66 and .
the sheath 65, it is preferred to bevel the outer surface of - the end of the bayonet tube as best shown in FIG. 4.
` `` 1 163627 , The plastic bayonet tube of the invention effectively pre~ents reheating by its insulating quality. The optimum , parameters found for this embodiment of the in~ention uses a I one-inch OD (outer diameter) tube of 0.035 wall thickness , for the sheath and a 1/2 inch ips (iron pipe size) (0.84 inch OD) Schedule 80 (0.147 inch) PVC or CPVC tube for the ~, bayonet tube. The preferred inside cross-sectional area of I the sheath is 0.679 square inches and the outside cross-sectional , area of the bayonet is 0.554 square inches lea~ing an annular j passage surrounding the bayonet of 0.125 square inches in ,I cross-section or about 18 percent of the total area inside of the sheath. A flow rate through each such bayonet tube ,~-of two ~allons of liquid per minute provides a velocity of ¦ 5.1 feet per second through the annular passage surrounding I the bayonet. This smali annular passage and the relatively l high flow velocity creates a high turbulence in the fluid in ¦ the annular passage which promotes overall heat transfer 'I rates of 600-800 Btu/cf/F. at the high vacuums at which I these h~at exchanges are operated. The sheath preferably may I range in OD from 75" to 1.5" and the bayonet tube from 0.5~
to 1.25~" The wall thicknesses of the sheath and the bayonet tube can be determined by the intended application but it is preferred that an annular passage with an area of about 18 ; percent of the total area within the sheath be maintained for the most effective heat transfer rates.
In a multiple tube heat exchanger as shown in FIG. 5, the plastic bayonet tubes 66 may be adhered to plastic tube sheet 69 while a metal tube sheet 78 is used to seal the sheath tubes 65 to each other and to the outer shell. In 3n this embodiment, the tube sheet 78 is sealed between flanges 11 75 and 76 of outer shell sections 73 and 74 respectively.
1163627 ``
Il ~n inlet fluid plenum 70 is formed by a portion of outer i! shell section 74 between tube sheet 69 and an end head 77.
Fluid enters the plenum 70 through inlet 79 positioned in Il the wall of shell section 74 between tube sheet 69 and end i head 77. A similar inlet plenum is unnecessary in the il single tube embodiment of FIG. 4 since the bayonet tube 66 ¦ extends into a bushing 67 through tube sheet 68 providing a ¦¦ direct connection to a fluid supply line.
The embodiment of FIG. 5 of a bayonet tube heat exchanger ¦ of the invention in addition to providing high heat transfer rates, cost effectiveness in construction and operation and compact arrangement performs functions which would be impossible `
or quit,e expensive in standard heat exch~nger constructions.
I For example, a "U" tube design would not be able to use the 1 light gauge corrosion resistant metals found in this invention ¦¦ since such materials are al st impossible to bend to a l short radius. Further, sm~ller tube diameters ha~e to be ! used in conventional construction to provide necessary tube l ~elocities for good heat transfer rates. The use of 0.5~ to i 1.25" OD bayonet tubes and 0.75" to 1.5" OD sheaths in this ¦l invention, in addition to being economical tube sizes, also l! pro~ides optimum water flow velocities without use of much smaller tubes and attendant increase in the number of dri holes and construction costs.
25 ,l A further preferred embodiment of a multiple bayonet tube heat exchanger is depicted in Fig. 6. This embodiment has a two-pass water box -rrangement wherein one or more bayonet tubes 83 and one or more bayonet tubes 87 rather than connecting to a single plenum 71 as in FIG. 5, connect , to two plenums 80 and 31. Thus, the second fluid flow zone .: .~ .~.. . .
!` ( ' 1163627 `
has fluid entering plenum 80 through inlet 82 through a tube sheel 91 from which it enters at least one bayonet tube 83 which is in fluid com~unication with plenum 80. This fluid travels ,l the length of the ~ayonet tube 83 and returns through annular 5 li passage 84 between the bayonet tube and its sheath 89 into 1'1 chamber 85. Fluid entering chamber 85 r which is formed by li tube sheet 78a, tube sheet 69a and shell section 74a, then travels into annular passage 86 surrounding bayonet tube 87 Il and exits down at least one bayonet tube 87 which is in ll fluid communication with plenum 81 and exits through outlet ~¦ 88. This arrangement increases the water velocities through the heat exchanger. Such velocities may be further increased ¦ by adding additional passes.
¦¦ FIG. 7 pro~ides an illustration of one application of 1¦ the embodiment of the bayonet tube heat exchanger described in relation to FIG. 4. The heat exchanger can be coupled with a domestic hot-water heater to produce low cost potable water from contaminated well water. Water from the hot I water ~ank 100, e., a first fluid, is supplied via fluid I line 114 to the inlet 62 feeding the first fluid flow zone of bayonet tube heat exchanger 101 to be further heated. 1, i! Additional water from tank 100 is supplied via ~luid line ' ~l 115 and pump 116 to inlet 67 feeding the second fluid flow ~l~ zone of bayonet tube heat exchanger 102. A second fluid ~' in~roduced through inlet 67 feeding the second fluid flow zone of heat exchanger 101 is heated by an auxiliary electric heater 104 in heater loop 103 serviced by pump 117. The heated fluid entering inlet 67 from loop 103 exits the heat 1 exchanger 101 at outlet 72 and recirculates thro~gh the , heater loop after giving up its heat to the water in the first fluid flow zone.
` `` 1163627 The heated water and water Yapor from the first fluid ~lo~ zone exits from outlet 63 and flows through pipe 105 to ~apor separator 106. The liquid water in the separator 106, ' which contains concentrated pollutants, drains through .5 outlet 107 to drain line 108 and is pumped away by pump 118.
The vapor at about 165~. from the upper end of separator 106 is introduced via fluid line 119 into the inlet 62 feeding the first fluid flow zone of bayonet tube heat exchanger ' 102. The water entering heat exchanger 102 from tank 100 , through inlet 67 feeding the second fluid flow zone of exchanger j 'll 102 causes the ~apor in the first fluid flow zone to condense~
i Distilled water is taken off through outlet 109 which communi- i1 cates with the first fluid flow zone. The distillate is pumped 11 via fluid line 110 connected to a wet vacuum pump 111.
1l The water exiting heat exchanger 102 through outlet 72 Il is at a t~mperature of 120-140F. and returns via fluid line - l, 112 to a valve 113 which directs it through the household hot water system or returns it to the hot water tank 100. With ', this system, using single tube bayonet tube heat exchangers of 2~ . the type depicted in FIG. 4, for every twelve gallons of , water raised 80F~, one gallon of distilled water can be ,~ produced for less than 1/8 of a KW for pumping costs. This application can also be used for a small electroplating set up to concentrate and recover plating wastes. The ganged pumping system used is described in U.S. Patent No. 3,358,609.
In order to assemble the multiple tube bayonet tube heat exchangers, as depicted in FIG. 2, especially when there are dozens or hundreds of bayonet tubes involved, a guidance means is provided to permit the bayonet tubes to be aligned with their corresponding sheath tubes. As depicted in FIG. 8, a circùlar plate 120 is provided with holes 121. The number of holes at least equals the number of bayonet tubes used in the heat exchanger in which such guidance plate is employed. The plate may be of plastic or metal depending upon the operating temperature range of the heat exchanger in which it is used. The holes 121 are positioned to correspond with the openings of the sheaths in the second tube sheet 16a. As depicted in FIG. 2, the plate 1~0 is dimensioned to fit within the outer shell of the heat exchanger and is held a distance away from tube sheet 16a by positioning rods 122. The holes in plate 120 are slightly larger than the diameter of the bayonets in order to enable the bayonets to slide freely through the positioning holes and into the sheath tubes.
In operation, the free ends of the bayonet tubes are inserted into holes 121 in plate 120 and the plate is aligned with the sheath tubes 11. Then, by pushing the bayonet tube sheet, the bayonet tubes slide through the plate 120 and along the length of sheath tubes 11 until the positioning rods 122 contact the sheath tube sheet 16a.
This plate enables the proper positioning of the bayonets upon insertion and maintains them in proper spaced relationship upon removal of the bayonet tubes from the heat exchanger.
Other applications and modifications of this invention will be obvious to one skilled in the art of heat exchangers. Such applications may include the use of the bayonet tube heat exchanger with a climbing film evaporator in conjuction with a Freon (trade mark) heat pump with secondary heat transfer loops using distilled water to prevent transfer of radioactivity from the concentration of radioactive wastes. Reference to 1 16362~
Williamson U.S. Patent Nos. 3,248,305; 3,399,118; 3,420,747 will furnish further details as to applications particularly as they would apply of a freon pump.
The freon condenser of the heat pump can employ the bayonet tube heat exchanger ~sing enhanced tubing for the sheath. Finned or twisted tubes similar to those described in U.S. Patent No. 3,533,267 can be used to condense the freon vapors on the outside of the sheath and transfer heat to distilled water, or other liquid to be heated~ in the annulus between the sheath and the insulating bayonet.
The bayonet tube heat exchanger may be used with a long tube flash evaporator of the type depicted in Williamson U.S. Patent No. 3,186,924 and would be particularly advantageous. The bayonet tube heat exchanger could replace the condenser portion identified as 22 in the 3,186,924 patent and would reduce the length of the heat recovery condenser in half and eliminate any problem with expansion stresses. For example, a long tube flash evaporator requiring 1/2" O~ tubes in order to acquire optimum tube velocity could use 1" OD bayonet sheaths and insulating bayonet t~bes providing the small annuli area which would require half the length heat transfer tube in order to acquire the same square feet of heat transfer surfaces with the same tube velocities. The number of tube holes to be drilled would be greatly reduced and save in tubing and fabrication costs. The division plates 45 in the patent 3,186,924 can be part of the new removable bayonet tube bundle and would eliminate the need for flanging sections 41.
It is intended that modifications and variations of the above embodiments can be made within the scope of this invention as defined by the appended claims and their equivalents.
~.,
Claims (49)
1. A bayonet tube heat exchanger comprising-(a) a-substantially horizontal outer shell having an elongated center section, an inner end having a first tube sheet closure and a closed distal end;
(b) at least one thin gauge tubular sheath having a closed end adjacent but spaced from said closed distal end of said shell and an open end facing said first tube sheet closure of said shell;
(c) means for forming a first fluid flow zone between the outer surface of said sheath and said shell wherein a first fluid is boiled;
(d) a bayonet tube concentrically positioned in at least one of said sheaths, said bayonet tube piercing said first tube sheet closure, and having an outer portion extending at least through said first tube sheet closure and an inner portion terminating in an open end spaced from the closed end of said sheath; and (e) means for forming a second fluid flow zone between said bayonet tube and the inner surface of said sheath wherein a second fluid is condensed.
(b) at least one thin gauge tubular sheath having a closed end adjacent but spaced from said closed distal end of said shell and an open end facing said first tube sheet closure of said shell;
(c) means for forming a first fluid flow zone between the outer surface of said sheath and said shell wherein a first fluid is boiled;
(d) a bayonet tube concentrically positioned in at least one of said sheaths, said bayonet tube piercing said first tube sheet closure, and having an outer portion extending at least through said first tube sheet closure and an inner portion terminating in an open end spaced from the closed end of said sheath; and (e) means for forming a second fluid flow zone between said bayonet tube and the inner surface of said sheath wherein a second fluid is condensed.
2. The bayonet tube heat exchanger according to claim 1, including a plurality of tubular sheaths each with its concentric bayonet tube and wherein said means for forming said first fluid flow zone includes a second tube sheet closure joining the outer surfaces of the open ends of said sheaths and the inner surface of said shell, and wherein said means for forming said second fluid flow zone includes a plenum between said second tube sheet closure, said first tube sheet closure and said shell.
3. The bayonet tube heat exchanger according to claim 2, wherein said means for forming said first and second fluid flow zones include at least one inlet and one outlet for each said zone, the inlet and outlet for said second zone opening into said plenum, and wherein said exchanger also includes means for applying a vacuum source to said outer portions of said bayonet tubes.
4. The bayonet tube heat exchanger according to claim 3, wherein said means for applying a vacuum source to said outer portions of said bayonet tubes comprises a vacuum chamber adjacent said first tube sheet closure and in fluid communication with a vacuum source, said outer portions of said bayonet tubes opening into said vacuum chamber.
5. The bayonet tube heat exchanger according to claim 1, 2 or 3, wherein the cross-sectional area of each bayonet tube is approximately 1/16 the cross-sectional area of its concentric sheath.
6, The bayonet tube heat exchanger according to claim 1 wherein said exchanger also includes means for applying a vacuum source to said outer portion of said bayonet tube.
7. The bayonet tube heat exchanger according to claim 6 wherein said means is a pipe for fluid communication to a vacuum source.
8. The bayonet tube heat exchanger according to claim 1 wherein said means for forming a first fluid flow zone includes at least one inlet and one outlet through said shell, and wherein said means for forming a second fluid flow zone includes an inlet through said outer portion of each said bayonet tube and at least one outlet through said shell.
9. The bayonet tube heat exchanger according to claim 2 wherein said means for forming a first fluid flow zone includes at least one inlet and one outlet through said shell, and wherein said means for forming a second fluid flow zone includes an inlet through said outer portion of`
each said bayonet tube and at least one outlet through said shell.
each said bayonet tube and at least one outlet through said shell.
10. The bayonet tube heat exchanger of claim 8 including an inlet feed chamber into which said outer portions of said bayonet tubes open.
11. The bayonet tube heat exchanger of claim 9 including an inlet feed chamber into which said outer portions of said bayonet tubes open.
12. The bayonet tube heat exchanger according to claim 2, wherein said means for forming a first fluid flow zone includes at least one inlet and one outlet through said shell, and wherein said means for forming a second fluid flow zone includes an inlet through said outer portion of at least one of said bayonet tubes and an outlet through at least one other of said bayonet tubes.
13. The bayonet tube heat exchanger according to claim 8, wherein each of said bayonet tubes is formed of insulating material for preventing reheating of fluid flowing in said second fluid flow zone.
14. The bayonet tube heat exchanger according to claim 13, wherein said insulating material is plastic.
15. The bayonet tube heat exchanger of claim 13, wherein the bayonet tube has positioning means for main-taining said tube uniformly concentric within said sheath.
16. The bayonet tube heat exchanger of claim 15, wherein said positioning means includes three spacers each projecting radially from said bayonet tube at 120° apart from each other around the circumference of said bayonet tube.
17. The bayonet tube heat exchanger according to claim 10, 11 or 12, wherein said open end of the bayonet tube is bevelled around its exterior circumference.
18. The bayonet tube heat exchanger according to claim 1, wherein each of said sheaths is formed of corrosion resistant metal.
19. The bayonet tube heat exchanger according to claim 1, 2 or 3, wherein each sheath tube is inclined downwardly toward the inner end of said shell.
20. The bayonet tube heat exchanger of claim 4, wherein the closed distal end of said shell includes a sight window.
21. The bayonet tube heat exchanger of claim 4, wherein the side of said vacuum chamber opposite the first tube sheet includes a sight window.
22. The bayonet tube heat exchanger according to claim 8, 9 or 10, wherein the bayonet tubes and the sheaths are dimensioned to provide an annular passage between the sheath and the bayonet tube having a cross-sectional area which is less than twenty-five percent of the inner cross-sectional area of the sheath.
23. A method for operating a bayonet tube heat exchanger comprising:
(a) forming a first fluid flow zone between the inner surface of a shell having a closed end and the outer surface of a tubular thin gauge sheath having a closed end, the closed end of the sheath being spaced from the closed end of the shell;
(b) forming a second fluid flow zone between the inner surface of the sheath and the outer surface of a bayonet tube concentrically inserted into said sheath, the inner end of said bayonet tube being open and spaced from the closed end of said sheath, and the outer end of said bayonet tube extending outside said second fluid flow zone;
(c) causing a first fluid to flow through said first fluid flow zone wherein said first fluid is boiled;
(d) causing a second fluid to flow through said second fluid flow zone wherein said second fluid is condensed; and (e) applying a vacuum to the outer end of said bayonet tube for removing non-condensible gases entrained in said second fluid and accelerating fluid flow through said second fluid flow zone.
(a) forming a first fluid flow zone between the inner surface of a shell having a closed end and the outer surface of a tubular thin gauge sheath having a closed end, the closed end of the sheath being spaced from the closed end of the shell;
(b) forming a second fluid flow zone between the inner surface of the sheath and the outer surface of a bayonet tube concentrically inserted into said sheath, the inner end of said bayonet tube being open and spaced from the closed end of said sheath, and the outer end of said bayonet tube extending outside said second fluid flow zone;
(c) causing a first fluid to flow through said first fluid flow zone wherein said first fluid is boiled;
(d) causing a second fluid to flow through said second fluid flow zone wherein said second fluid is condensed; and (e) applying a vacuum to the outer end of said bayonet tube for removing non-condensible gases entrained in said second fluid and accelerating fluid flow through said second fluid flow zone.
24. The bayonet tube heat exchangers of claim 1, having a circular plate for positioning bayonet tubes in sheaths, said plate having a diameter substantially equal to the inner diameter of said shell and having a plurality of holes, said holes corresponding to the sheaths in number and located in said plate in corresponding relationship to said sheaths, said holes having a diameter slightly larger than and engageable for sliding relationship with said bayonet tubes when the open ends of said bayonet tubes are inserted in said holes, and means for positioning said plate in the heat exchanger at a fixed distance from the first tube sheet.
25. The plate of claim 24, wherein the means for positioning the plate a fixed distance from the first tube sheet includes a plurality of spacer rods fixed at one end to the plate.
26. A flash evaporator comprising at least one elongated tank and a condenser, means for admitting fluid into said tank, means for causing said fluid to vaporize, causing the vapor to flow into said condenser, said condenser including (a) a substantially horizontal outer shell having an elongated center section, an inner end having a first tube sheet closure and a closed distal end;
(b) at least one thin gauge tubular sheath having a closed end adjacent but spaced from said closed distal end of said shell and an open end facing said first tube sheet closure of said shell;
(c) means for forming a first fluid flow zone between the outer surface of said sheath and said shell wherein said first fluid is condensed;
(d) a bayonet tube concentrically positioned in at least one of said sheaths, said bayonet tube piercing said first tube sheet closure, and having an outer portion extending at least through said first tube sheet closure and an inner portion terminating in an open end spaced from the closed end of said sheath; and (e) means for forming a second fluid flow zone between said bayonet tube and the inner surface of said sheath wherein said second fluid is heated in turbulent flow.
(b) at least one thin gauge tubular sheath having a closed end adjacent but spaced from said closed distal end of said shell and an open end facing said first tube sheet closure of said shell;
(c) means for forming a first fluid flow zone between the outer surface of said sheath and said shell wherein said first fluid is condensed;
(d) a bayonet tube concentrically positioned in at least one of said sheaths, said bayonet tube piercing said first tube sheet closure, and having an outer portion extending at least through said first tube sheet closure and an inner portion terminating in an open end spaced from the closed end of said sheath; and (e) means for forming a second fluid flow zone between said bayonet tube and the inner surface of said sheath wherein said second fluid is heated in turbulent flow.
27. The bayonet tube heat exchanger according to claim 1, wherein said first and second fluids are in heat exchange relationship when in said first and second fluid flow zones.
28. The bayonet tube heat exchanger according to claim 1, further including means for removing condensate and noncondensible gases entrained in said second fluid and accelerating fluid flow through said second fluid flow zone.
29. The bayonet tube heat exchanger according to claim 2, further including means for forming a third fluid flow zone between said second tube sheet closure, said first tube sheet closure and said shell.
30. The bayonet tube heat exchanger according to claim 14, wherein each of said sheaths are provided with enhanced surfaces as a means for imparting turbulent flow to said fluids.
31. The bayonet tube heat exchanger according to claim 14, wherein each of said bayonet tubes are spirally grooved on its external surface as a means for imparting turbulent flow to said second fluid.
32. The bayonet tube heat exchanger of claim 18 wherein said corrosion resistant metal is titanium.
33. The method of claim 23 further comprising forming a third fluid flow zone in fluid communication with said first and second fluid flow zones.
34. The method of claim 33 further comprising applying a vapor compressor to said first fluid zone thereby compressing said vapor and passing said compressed vapor to said third zone wherein said vapor is condensed.
35. The method of claim 23, wherein the cross-sectional area of said bayonet tube is approximately 1/16 of the cross-sectional area of its concentric sheath.
36. A bayonet tube heat exchanger comprising:
(a) a substantially horizontal outer shell having an elongated center section, an inner end having a first tube sheet closure and a closed distal end;
(b) at least one thin gauge tubular sheath having a closed end adjacent but spaced from said closed distal end of said shell and an open end facing said first tube sheet closure of said shell;
(c) means for forming a first fluid flow zone between the outer surface of said sheath and said shell;
(d) an insulating plastic bayonet tube concentrically positioned in at least one of said sheaths, said bayonet tube piercing said first tube sheet closure, and having an outer portion extending at least through said first tube sheet closure and an inner portion terminating in an open end spaced from the closed end of said sheath; and (e) means for forming a second fluid flow zone between said bayonet tube and the inner surface of said sheath wherein means are provided for imparting turbulent flow to said second fluid.
(a) a substantially horizontal outer shell having an elongated center section, an inner end having a first tube sheet closure and a closed distal end;
(b) at least one thin gauge tubular sheath having a closed end adjacent but spaced from said closed distal end of said shell and an open end facing said first tube sheet closure of said shell;
(c) means for forming a first fluid flow zone between the outer surface of said sheath and said shell;
(d) an insulating plastic bayonet tube concentrically positioned in at least one of said sheaths, said bayonet tube piercing said first tube sheet closure, and having an outer portion extending at least through said first tube sheet closure and an inner portion terminating in an open end spaced from the closed end of said sheath; and (e) means for forming a second fluid flow zone between said bayonet tube and the inner surface of said sheath wherein means are provided for imparting turbulent flow to said second fluid.
37. The bayonet tube heat exchanger according to claim 36, further including a plurality of tubular sheaths each with its plastic concentric bayonet tube and wherein said means for forming said first fluid flow zone includes a second tube sheet closure joining the outer surfaces of the open ends of said sheath and the inner surface of said shell, and wherein said means for forming said second fluid flow zone includes a plenum between said second tube sheet closure, said first tube sheet closure and said shell.
38. The bayonet tube heat exchanger according to claim 36, wherein each of said sheaths is formed of corrosion resistant metal.
39. The bayonet tube heat exchanger according to claim 38, wherein said metal is titanium.
40. The bayonet tube heat exchanger according to claim 38, wherein said sheaths are provided within enhanced surfaces.
41. The bayonet tube heat exchanger according to claim 40, wherein said plastic bayonet tubes are spirally grooved on their external surfaces for imparting turbulent flow to said second fluid.
42. The bayonet tube heat exchanger according to claim 36, wherein each sheath tube is inclined downwardly toward the inner end of said shell.
43. The bayonet tube heat exchanger according to claim 37, wherein the bayonet tubes and sheaths are dimensioned to provide an annular passage between the sheath and the bayonet tube having a cross-sectional area which is less than 25% of the inner cross-sectional area of the sheath.
44. The bayonet tube heat exchanger according to claim 14, wherein said plastic bayonet tube is spirally grooved on its external surface for imparting turbulent flow to said second fluid.
45. The bayonet tube heat exchanger according to claim 26, wherein said bayonet tube is formed of an insulating material for preventing reheating of fluid flowing in second fluid flow zone.
46. The bayonet tube heat exchanger of claim 45, further comprising means for sealing said sheaths between condensing stages of said elongated tank connection.
47. A freon heat pump having a freon condenser including:
(a) a substantially horizontal outer shell having an elongated center section, and having a first tube sheath closure and enclosed distal ends;
(b) at least one externally finned tubular sheath member having a closed end adjacent but spaced from said closed distal end of said shell and an open end facing said first tube sheath closure of said shell;
(c) means for forming a first fluid flow zone between the outer surfaces of said finned sheath and said shell wherein said first fluid is condensed;
(d) an insulating plastic bayonet tube concentrically positioned in at least one of said sheaths, said bayonet tube piercing said first tube sheath closure, and having an outer portion extending at least through said first tube sheath closure and an inner portion terminating in an open end spaced from said closed end of said sheath; and (e) means for forming a second fluid flow zone between said bayonet tube and the inner surface of said sheath wherein said second fluid is heated in turbulent flow.
(a) a substantially horizontal outer shell having an elongated center section, and having a first tube sheath closure and enclosed distal ends;
(b) at least one externally finned tubular sheath member having a closed end adjacent but spaced from said closed distal end of said shell and an open end facing said first tube sheath closure of said shell;
(c) means for forming a first fluid flow zone between the outer surfaces of said finned sheath and said shell wherein said first fluid is condensed;
(d) an insulating plastic bayonet tube concentrically positioned in at least one of said sheaths, said bayonet tube piercing said first tube sheath closure, and having an outer portion extending at least through said first tube sheath closure and an inner portion terminating in an open end spaced from said closed end of said sheath; and (e) means for forming a second fluid flow zone between said bayonet tube and the inner surface of said sheath wherein said second fluid is heated in turbulent flow.
48. A freon heat pump comprising:
(a) a freon compressor: and (b) a freon chiller including:
i. a substantially horizontal outer shell having an elongated center section, an inner end having a first tube sheath enclosure and a closed distal end;
ii. at least one externally finned tubular sheath having a closed end adjacent but spaced from said closed distal end of said shell and an open end facing said first tube sheath closure of said shell;
iii. means for forming a first fluid zone between the outer surfaces of said finned sheath and said shell wherein first fluid is boiled;
iv. an insulating plastic bayonet tube concentrically positioned in at least one of said sheaths, said bayonet tube piercing said first tube sheath closure and an inner portion terminating in an open end space from the closed end of said sheath; and v. means for forming a second fluid zone between said bayonet tube and the inner end of said sheath.
(a) a freon compressor: and (b) a freon chiller including:
i. a substantially horizontal outer shell having an elongated center section, an inner end having a first tube sheath enclosure and a closed distal end;
ii. at least one externally finned tubular sheath having a closed end adjacent but spaced from said closed distal end of said shell and an open end facing said first tube sheath closure of said shell;
iii. means for forming a first fluid zone between the outer surfaces of said finned sheath and said shell wherein first fluid is boiled;
iv. an insulating plastic bayonet tube concentrically positioned in at least one of said sheaths, said bayonet tube piercing said first tube sheath closure and an inner portion terminating in an open end space from the closed end of said sheath; and v. means for forming a second fluid zone between said bayonet tube and the inner end of said sheath.
49. A freon heat pump comprising:
(a) a freon compressor; and (b) a freon chiller including:
i. a substantially horizontal outer shell having an elongated center section, an inner end having a first tube sheath enclosure at a closed distal end;
ii. at least one internally finned tubular sheath having a closed end adjacent but spaced from said closed distal end of said shell and an open end facing said first tube sheath closure of said shell;
iii. means for forming a first fluid zone between the outer surfaces of said sheath and said shell when said first fluid is cooled;
iv. a small diameter bayonet tube concentrically positioned in at least one of said sheaths, said bayonet tube piercing said first tube sheath closure, and having an outer portion extending at least through said first tube sheath closure and an inner portion terminating in an open end spaced from the closed end of said sheath; and v. means for forming a second fluid zone between said bayonet tube and the inner surface of said internally finned tubular sheath.
(a) a freon compressor; and (b) a freon chiller including:
i. a substantially horizontal outer shell having an elongated center section, an inner end having a first tube sheath enclosure at a closed distal end;
ii. at least one internally finned tubular sheath having a closed end adjacent but spaced from said closed distal end of said shell and an open end facing said first tube sheath closure of said shell;
iii. means for forming a first fluid zone between the outer surfaces of said sheath and said shell when said first fluid is cooled;
iv. a small diameter bayonet tube concentrically positioned in at least one of said sheaths, said bayonet tube piercing said first tube sheath closure, and having an outer portion extending at least through said first tube sheath closure and an inner portion terminating in an open end spaced from the closed end of said sheath; and v. means for forming a second fluid zone between said bayonet tube and the inner surface of said internally finned tubular sheath.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US35080482A | 1982-02-22 | 1982-02-22 | |
US350,804 | 1989-05-12 |
Publications (1)
Publication Number | Publication Date |
---|---|
CA1163627A true CA1163627A (en) | 1984-03-13 |
Family
ID=23378254
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA000402013A Expired CA1163627A (en) | 1982-02-23 | 1982-04-30 | Bayonet tube heat exchanger |
Country Status (3)
Country | Link |
---|---|
AU (1) | AU552488B2 (en) |
CA (1) | CA1163627A (en) |
EG (1) | EG15145A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5314009A (en) * | 1992-10-08 | 1994-05-24 | Gas Research Institute | Exhaust gas recuperator |
CN117419586A (en) * | 2023-12-19 | 2024-01-19 | 中国核动力研究设计院 | Unidirectional micro-channel heat exchange tube assembly and heat exchanger |
-
1982
- 1982-04-30 CA CA000402013A patent/CA1163627A/en not_active Expired
- 1982-05-04 AU AU83274/82A patent/AU552488B2/en not_active Ceased
- 1982-06-12 EG EG33382A patent/EG15145A/en active
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5314009A (en) * | 1992-10-08 | 1994-05-24 | Gas Research Institute | Exhaust gas recuperator |
CN117419586A (en) * | 2023-12-19 | 2024-01-19 | 中国核动力研究设计院 | Unidirectional micro-channel heat exchange tube assembly and heat exchanger |
CN117419586B (en) * | 2023-12-19 | 2024-02-20 | 中国核动力研究设计院 | Unidirectional micro-channel heat exchange tube assembly and heat exchanger |
Also Published As
Publication number | Publication date |
---|---|
AU8327482A (en) | 1983-09-01 |
AU552488B2 (en) | 1986-06-05 |
EG15145A (en) | 1985-12-31 |
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