US3398722A - Heat exchanger apparatus - Google Patents

Description

HEAT EXCHANGER APPARATUS Filed June 8, 1966 2 Sheets-Sheet 1 INVBNTORJ ROBERT C. .SMYKAL dR. JAMES E MMAHON JR.

MW ATT RNEYS Aug. 27, 1968 c. sMYKAL, JR. 3,398,722

HEAT EXCHANGER APPARATUS 2 Sheets-Sheet 2 Filed June 8, 1966 FIGZ lNVEA/TORS ROBERT C. S'MYKAL (JR. "JAMES F. M MAHoN JR.

ATTO NEYS United States Patent "ice 3,398,722 HEAT EXCHANGER APPARATUS Robert C. Smykal, Jr., 15186 Drake Road, Strongsville, Ohio 44136, and James F. McMahon, Jr., Gates Mills, Ohio; said McMahon assignor to said Smykal Filed June 8, 1966, Ser. No. 556,141 6 Claims. (Cl. 122250) ABSTRACT OF THE DISCLOSURE Disclosed herein is a steam generator system having an economizer coil connected at one end to a reservoir and at the other end to a main coil of a steam generator. A tube is mounted in the economizer coil in a coaxial relationship therewith. One end of the tube is connected to a separator means where steam is separated into water and gas. The separator water is circulated through the tube to heat the water from the reservoir by cooling the water from the separator means.

The present invention relates to improvements in apparatus for use in systems for varying the temperature of one fluid with another fluid, and more particularly to a steam generator system wherein water is heated to produce steam.

In closed steam generating systems, the water to be heated into steam is maintained in a reservoir and is pumped therefrom and flowed through coils of a steam generator. The water is heated as it is circulated through the coils and is discharged therefrom as steam. One of the coils of the steam generator is an economizer coil which is positioned so that exhaust gases removed from the generator heat the water flowing therethrough. The steam is directed from the generator into a separator which separates the gaseous portion of the steam from the liquid portion thereof. The gaseous steam is then directed from the separator to equipment which is to utilize the steam, such as a radiator where heating is to be provided by the steam. The liquid portion of the steam collects in the separator and is returned to the reservoir for subsequent recirculation through the system. Also the gaseous portion of the steam which is directed, for example, to a radiator is likewise returned to the reservoir after being condensed to water as a result of heat transfer through the radiating equipment.

The liquid portion of the steam in the separator has a high temperature and is unsuitable for subsequent recirculation in the system without being cooled prior to be returned to the reservoir. If the liquid is returned to the reservoir without being cooled, it heats the water in the reservoir. Enumerable problems are created thereby, and it is not uncommon for the water temperature in the reservoir to reach the boiling point and steam is generated therein. When this water and steam mixture enters the pump, it can produce detrimental eflects on the pump requiring, for example, replacement of parts or the entire pump.

Heretofore, the cooling of the returning water has been accomplished by providing a separate heat exchanger in the return conduit through which the liquid is returned from the separator to the reservoir. The heat exchanger in many cases included a housing through which the water which is to be heated into steam is circulated before entering the coils of the steam generator, and the fluid return conduit carrying the fluid to be cooled has a section formed into a coil which is disposed in the housing of the heat exchanger so that the water to be heated in the housing absorbs heat from the water to be cooled as it passes to the reservoir. Silt and other forms of debris settle out of the water to be heated and collect in the Patented Aug. 27, 1968 housing of the heat exchanger due to the relatively slow rate of circulation of the water therethrough. As the debris accumulates, the housing volume is reduced resulting in a decrease in the efficiency of the heat exchanger. The decrease in efliciency is caused in part by the silt collecting about the coil insulating the coils from the cooling etfect of the circulating water to be heated. The increased circulation rate of water in the housing and the insulation of the coils reduces the amount of heat removed from the returning water. Consequently, the heat exchangers required frequent maintenance and replacement and which increased the down time of the steam generator system.

It is accordingly an important object of the present invention to provide a new and improved steam generator system which requires a minimum of maintenance and operates with high efliciency and with a minimum of shutdowns.

Another object of the present invention is to provide a new and improved closed steam generating system in which the water to be heated into steam cools the water returning to the reservoir without substantial reduction in the rate of flow of the water to be heated.

A further object of the present invention is to provide a new and improved apparatus for generating steam which eliminates the heretofore required separate heat exchanger which cooled the Water returning to the reservoir.

A still further object of the present invention is to provide a new and improved apparatus for the generation of steam and in which the hot water returning to the reservoir and the water to be heated into steam are circulated through the same coil in the steam generator so that the returning water transfers its heat to the water to be heated and which is accomplished without a reduction in the velocity of flow of the water to be heated so that suflicient heat is removed from the returning water so that it is discharged into the reservoir at an appropriate temperature.

Another object of the present invention is to provide a new and improved economizer coil for use in an apparatus in which the temperature of one fluid is varied by the temperature of another fluid and which coil includes a tube within a tube construction and water at a high temperature and to be cooled is circulated through a smaller inner tube and water at a lower temperature and to be heated is circulated through the larger tube thereby providing for cooling of the water in the inner tube.

A still further object of the present invention is the provision of a new and improved economizer coil as in the preceding object wherein spacers are provided to support the inner tube centrally of the outer tube so that the heat is transferred uniformly to the fluid in the outer tube and eliminates hot spots and tube wear caused by the inner tube engaging the outer tubes and rubbing thereon.

These and other objects will become apparent from the following description of the preferred embodiment of the invention taken in conjunction with the accompanying drawings and in which:

FIG. 1 is a diagrammatic representation of an apparatus for generating steam according to the present invention;

FIG. 2 is a plan view of an economizer coil used in the apparatus of FIG. 1;

FIG. 3 is a sectional view taken substantially along line 3-3 of FIG. 2; and

FIG. 4 is a sectional plan view taken substantially along line 44 of FIG. 2.

The present invention provides an improved apparatus for use in systems for varying the temperature of one fluid by another fluid. The invention is applicable to numerous different systems wherein one fluid is heated by another but will be described hereinbelow with reference to a steam generating system for use on trains for various purposes including heating of the railroad cars.

As representing the preferred embodiment of the present invention, FIG. 1 illustrates a steam generator system 10. The steam generator system is used for heating a liquid preferably water to provide steam to heat the railroad cars. The steam generator system 10 is a closed system and includes a tank 12 which functions as a reservoir for the water to be used in the system. The reservoir 12 receives the return water and also make up water which is periodically added to the system. The water in the reservoir or tank 12 is pumped to a steam generator 14 by a pump 16. The pump 16 pumps the water from the reservoir through a conduit 18 connected at one end to the bottom of the tank 12 and at the other end to the inlet of pump 16. The pump 16 is of conventional construction and will not be described herein in detail. Suffice it to say that it is driven by suitable power means and is effective to pump the water in tank 12 through conduit 18, through the pump 16 and out through a conduit 20 to the boiler 14. The pump 16 provides the motive force for moving the water through the closed system. A suitable filter may be disposed in conduit 18 to remove foreign particles from the water prior to water entering the pump so that sludge is maintained at a minimum throughout the system.

The steam generator 10 in the preferred embodiment is a water heater or boiler of generally conventional construction and includes a central heating chamber 22 which receives heat generated by combustion of a suitable fuel. The fuel is introduced into the heater or boiler by a fuel line 24 which directs the fuel under an appropriate temperature and pressure into a combustion chamber 26 located above the heating chamber 22. The fuel entering the combustion chamber ignites and the heat from the combustion enters heating chamber 22 and is discharged into a flue 28. Coil means indicated generally as 30 are disposed about the heating chamber 22 and through which the water from the reservoir is circulated and heated into steam by the heat in the heating chamber 22. The coil means 30 comprises an economizer coil 32 which is connected to the Water inlet conduit 20 and initially receives and circulates the water in the boiler. The economizer coil as shown in FIG. 1, is positioned in the boiler so that it is exposed to the exhaust gases in flue 28. This arrangement utilizes the heat contained in the exhaust gases to initially heat the water entering the boiler preparatory to entering main coil 34 disposed in the heating chamber proper.

The water circulating in the economizer coil is discharged from the economizer coil through a conduit 36. The conduit 36 directs the preheated water into the main coil 34 where it circulates through the main coil and is heated by the heat in the heating chamber 22 to produce steam. The steam in the main coil 34 is discharged from the boiler into a conduit 38. The steam in conduit 38 is directed into the upper end of a separator 40. The separator 40 is a conventional steam separator and functions to sparate the gaseous portions of the incoming steam from the liquid portion thereof to prevent the liquid portion of the steam from entering the radiator or other equipment which is to utilize the produced steam. The separator includes an inlet passage 42 at the upper end thereof which is connected to conduit 38 and through which the steam enters the upper portion of a separator chamber 44. A gas discharge outlet conduit 46 is provided in the upper portion of the separator 40 as viewed in the drawings, and through which the gaseous portion of the steam flows. The lower end of conduit 46 extends below the inlet passageway 42 and the entering steam must flow downwardly upon entering the chamber 44. The gaseous part of the steam raises and enters the flared end of conduit 46 which directs the steam to the radiators in the railroad cars.

The liquid portion of the steam entering the inlet 42 flows downward in chamber 44 by gravity and collects'in the bottom of the chamber 44 and is subsequently returned to the tank 12. Disposed adjacent to the lower end of the separating chamber 44 is a liquid outlet conduit 50 through which the liquid collected in the chamber 44 flows in the course of returning to the reservoir or tank 12. During the operation of the heater, the gaseous portion of the steam entering chamber 44 accumulates therein and exerts a pressure on the collected liquid portion of the steam which forces the liquid out conduit 50. Consequently, there is a mixture of the liquid and gas portion of the steam and the liquid discharged through outlet con duit 50 may contain steam which must be eliminated from the system prior to its return to the reservoir 12. A suitable conventional steam trap 52 is provided in communication with the conduit 50 and operates to trap any steam in the returning liquid.

The separated liquid is returned to the tank 12 and has a relatively high temperature and must be cooled before entering the tank 12. The cooling will prevent the water in the tank 12 from being heated therein and/or reheated into steam in the tank which steam would harm the pumping means 16. The present invention provides an improved means for cooling the returning liquid and insures that suflicient heat is removed therefrom before returning to the tank 12, The returning water is cooled by flowing it through the economizer coil 32 counter to the flow of water to be heated which also is flowing through the economizer coil 32. The counterflow of returning water to be cooled gives up heat to the incoming fluid to be heated in the economizer coil 32 functioning to heat the incoming water while at the same time cooling the returning fluid so that it is at an acceptable temperature when entering the tank 12.

The economizer coil 32, best illustrated in FIGS. 2 and 3, includes a continuous coil which in the preferred embodiment is wound to form side-by-side convolutions of tubing. The coil includes an outer tube 32a through which the water entering the boiler is initially circulated. The outer tube 32a is constructed from suitable material such as steel having good heat transfer properties and is resistant to the corrosive effects of the exhaust gases in the flue of the boiler. Disposed co-axially within the outer tube 32a is an inner tube 32b through which the returning fluid is circulated through the economizer coil 32. The inner tube 32b has a thin wall and is preferably made of copper which has good heat transfer properties so that the heat in the returning water is effectively transferred to the water flowing through the outer tube 32a.

The inner tube 32b is supported centrally within the outer tube 32a by a plurality of spacers 54. The spacers are triangular in cross-sectional configuration and are of such size that the inner tube 32b is nestled in engagement with the inner sides of the legs of the spacer 54 and are suitably connected thereto as by brazing, The corners or apices of spacers 54 engage the interior wall of the outer tube 32a. The spacers support the inner tube 32b so that it is disposed in the central portion of the stream of the fluid to -be heated flowing through the outer tube 32a. This supporting arrangement does not permit the inner tube to sag and engage the inner wall of the outer tube 32a which sagging restricts flow thereabout creating hot spots which cause the tubes to expand and rub producing wear of the coils. Sagging also creates nonuniform heat transfer to the water flowing through the outer tube 32a.

As stated heretofore, the returning water to be cooled and the relatively cool water to be heated flow through the economizer coil in counter or opposite directions. A pair of connector means 56 and 58 are connected to the ends of the economizer coil and direct the fluids through the tubes to provide the counterflow. The connector means 56 is connected to the inlet end of the outer tube 32a and the outlet end of the inner tube 32b. The connector means 56 is also connected to conduit 20 and to an outlet conduit 60 through which the cooled water is returned to the tank 12. The connector means 56 directs the water to be heated in conduit 20 into the inlet end of the outer tube 32a and directs water to be cooled from the outlet end of the inner tube 3212 into outlet conduit 60. The connector means 58 is connected to the outlet end of the outer coil 32a and the inlet end of the inner tube 32b. The connector 58 is also connected to conduit 36 and to a conduit 62 through which the fluid to be cooled flows from the steam trap 52 to the economizer coil. The connector means 58 directs the water to be heated from the outlet end of the outer tube 32a into conduit 36 which directs it to coil 34, and the water to be cooled from conduit 62 into the inlet end of the inner tube 32b.

The connector means 56 and 58 are identical in construction and only connector means 56 will be described in detail. The connect-or means 56 comprises a body 64. The body 64 has formed therein a first passageway 66 and a second passageway 68 connected by restricted passageway 70. The passageway 66 provides for the flow of the water to be heated from the conduit 20 into the inlet end of the outer coil 32a. Passageway 66 is generally L-shaped in configuration and includes tapered, internally threaded portions 66a and 66b at the ends thereof. The threaded passageway portion 66a receives the tapered, threaded end 20a of the conduit 20. The threaded end portion 66b of the passageway 66 receives the tapered, threaded inlet end of the outer tube 32a. The inner tube 32b extends axially beyond the inlet end of the outer tube 32a and extends through one leg of passageway 66 and through the intermediate passageway 70 and has its discharge end opening into the passageway 68.

An externally threaded bushing 72 is mounted on the outlet end of the inner tube 32b and is threaded into suitable threads provided by the portion of the body 64 defining intermediate passageway 70. The bushing 72 when secured into the body 64 functions to connect the discharge end of inner tube 32b to the housing 64 and also seals the passageway 68 from the passageway 66 so that the water in the respective passageways are maintained separated. The right-hand end of the bushing 72, as viewed in FIG. 4, may be split axially so that by threading a nut 73 on the split end, the bushing is clamped to the tube 32b. The end of passageway 68 is provided with tapered, internal threads 68a. The threads 68a receive the exteriorly threaded tapered end 60a of the conduit 60 through which the cooled returning fluid is directed to the tank 12.

It should be apparent from the foregoing description of the connector means 56 that the incoming water to be heated is directed from the outlet end 20a of conduit 20 into passageway 66 where it enters the inlet end of the outer tube 32a of the economizer coil 32. This flow has been indicated by the arrows designated as 74 in FIG. 4. The fluid circulates through the outer tube 32a which is being heated by the exhaust gases in the flue 28 and also by the returning water flowing through the inner tube 32b. The water to be heated is discharged from the outlet end of the outer tube 32a into the connector means 58 where it is directed through a passageway similar to passageway 66 shown in FIG. 4 into conduit 36 which directs the fluid into the main heating coil 34 where it will subsequently be heated to produce steam. The returning fluid which is to be cooled in the economizer coil is directed to the coil through conduit 62 into the connector means 58 where it enters a passageway similar to passageway 68 shown in FIG. 4. The fluid in this passageway enters the inlet end of the inner tube 32b and flows through the inner tube counter to the flow of the water to be heated and is discharged into the passageway 68 shown in FIG. 4. This flow through the outlet end of the inner tube 32b is depicted by an arrow designated 76 in FIG. 4. The fluid which has been cooled enters passageway 68 and into the end 60a of conduit 60 which directs the fluid to the tank 12 where it is stored and subsequently returned to the boiler by the pump 16.

From the foregoing it should be apparent that the present invention provides a new and improved apparatus for heating one fluid by another and which provides for cooling of the return fluid by transferring heat to the incoming Water to the boiler which is to be heated to produce steam. The heating and cooling of the respective fluids are accomplished in the economizer coil which functions as a heat exchanger. The economizer coil thus functions to initially heat the incoming fluid which is to be subsequently generated into steam while simultaneously cooling the fluid returning from the separator to the tank. This heat exchange is accomplished without reducing the flow velocity of the incoming water to be heated, and minimizes maintenance probablerns and increases the efficiency of a steam generation system in which it is utilized and which requires minimum shutdowns for repair.

Although the present invention has been described in considerable detail, it is intended to cover all modifications, adaptations and uses thereof which come within the scope of the appended claims.

We claim:

1. In an apparatus for heating a fluid, a heat exchanger having coil means adapted to receive a fluid to be heated and a fluid to be cooled so that heat is transferred from the fluid to be cooled to the fluid to be heated, said coil means comprising a first tubular coil having inlet and outlet means and adapted to receive and circulate said fluid to be heated, a second tubular coil having a diameter smaller than the diameter of said first tubular coil and disposed within said first coil, said second coil further having inlet and outlet ends, first connector means connected to said coil for introducing said fluid to be heated into said inlet end of said first coil and directing the fluid to be cooled from said outlet end of said second coil, and second connector means connected to said coils for introducing said fluid to be cooled into said inlet end of said second coil and for directing the fluid to be heated from said outlet end of said first coil whereby said fluids circulate through said coil in opposite directions to effect said heat transfer, said first and second connector means each including a body having separated lfirst and second passageways, said first passageway of said first connector means directing the fluid to be heated to said inlet end of said first coil and said second passageway of said first connector means directing the fluid from said outlet end of said second coil, said first passageway of said second connector means directing the fluid to be cooled into said inlet end of said second coil and said second passageway of said second connector means directing the water to be heated from said outlet end of said first coil.

2. The apparatus defined in claim 1 further including a heat chamber within which hot gasses are adapted to circulate, an exhaust flue which is adapted to receive hot gasses from said heat chamber, and a main coil exposed to said hot gasses in said heat chamber and connected in fluid communication with said first tubular coil at said second connector mean-s, said coil means being supported in said exhaust flue and exposed to exhaust gasses therein to thereby heat fluid flowing through said first tubular coil.

3. The apparatus defined in claim 1 further including spacer means for supporting said second coil centrally in said [first coil, said spacer means comprising a plurality of triangular shaped spacer members, said spacer members surrounding spaced portions of the periphery of said second coil.

4. The apparatus defined in claim 1 wherein said first and second connector means each including a body having separated first and second passageways, said first passageway of said first connector means directing the fluid to be heated to said inlet end of said first coil and said second passageway of said first coil directing the fluid from said outlet end of said second coil, said first passageway of said second connector means directing the fluid to be cooled into said inlet end of said second coil and said second passageway of said second connector means directing the water to be heated from said outlet end of said first coil.

5. The apparatus defined in claim 4 wherein each body includes a bushing supporting an end of said second coil and separating said rfirst and second passageways to prevent mixing of said fluids.

6. In an apparatus for generating steam, a reservoir adapted to store Water to be heated, a steam generator having a main coil and an economizer coil connected in series and extending around a heating chamber, pump means for pumping water from said reservoir through said economizer coil where the water is initially heated and then through said main coil where the water is further heated, means for heating the water to convert the Water to steam as it is circulated through said coils, separator means connected to said main coil for separating the steam generated in said coils into gas and water, a tube mounted within said economizer coil, first conduit means directing water from said separator means into said tube at a first end of said economizer coil which is opposite to a second end of said economizer coil through which water from said reservoir enters said economizer coil, and second conduit means connected to said tube at said second end of said economizer coil for conducting water from said tube to said reservoir, said tube being mounted in said economizer coil in a coaxial relationship with said economizer coil to enable heat to flow from said heating chamber into water from said reservoir circulating through said economizer coil and to enable heat to flow from said separator water circulating through said tube into the water from said reservoir to thereby contemperaneously heat the Water from said reservoir and cool the water from said separator means.

References Cited UNITED STATES PATENTS 1,800,306 4/1931 Lofiler 122483 1,908,265 5/1933 Luche 122-235 XR 2,020,860 11/1935 Touborg 165154 XR 2,442,281 5/1948 Arant 122406 XR 2,527,539 10/1950 Frisch 122479 XR 3,105,468 10/1963 Gardam 122-451 KENNETH W. SPRAGUE, Primary Examiner.

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