US2086808A - Fractionator control device - Google Patents

Description

July 13, 1937. F. l.. KALLAM 2,086,808

FRACTIONATOR CONTROL DEVICE l Filed kDec. 22, 1935 .'5 Sheets-Sheet l :QJ ze 27 N lll 54 v INVENToR.

FLOYD L KAL/.AM

ATTORNEY July 13, 1937. F. KALLAM FRACTIONATOR CONTROL DEVICE Y Filed Dec. 22, 1935 5 sheets-sheet 2 INVENToR.

l :j y y BY FLOYD LKML/uv ATTORNEY 4July 13, 1937. F. L. KALLAM FRACTIONATOR CONTROL DEVCE 3 Shets-Sheet 5 Filed Dec. 22, 1933 nl I M, a/w www IN VEN TOR.

N, na/m L MN L Rv Ayn KMT L A D/W/ Y O Patented July 13,` 1.937

UNITED STATES PATENT OFFICE 2,086,808 v l s FRATIONATOR CONTROL DEVICE Floyd L. Kallam,` Huntington Park, Calif. Application'llecember 22, 1933, Serial No. 703,574

'I'he invention relates to a method and means for stabilizing a product of a continuously operating distilling fractionator to have a constant volatility, and the. present lapplication comprises a 5 continuation in part of my copending, application for United States Letters Patent o'n a Control devvice for fractionators and the like, Serial Number 412,646, led Dec; 9, 1929, now U. S. Patent 1,940,802. A l A general object of the invention, is to provide,

in association with a fractionating apparatus, improved means to so controla rened liquid product thereof that said product will be of constant volatility.

l Another object of the invention is to directly and continuouslyindicate and/or record the volatility ef a liquid in the apparatus, for use in effecting a control of the apparatus for the specified purpose. v

mx A further and more specific object is to automatically eifect the stated control of a product-in terms' of the volatility of the liquid being treated showing one application of a control unit of the present invention in a fractionating apparatus, certain elements of the apparatus being shown in sectional elevation. l

' Figures 2 'and 3 are enlarged fragmentary and sectional views of diiferent portions of the control unit.l

Figure 4 is a generallyiagrammatic elevation showing still another, application of the present control unit to the aforesaid apparatus.

Figui-e5 is an enlarged sectional view of a portion of a volatility-testing unit which is used in the arrangement of Figure 4.

Figure 6 is a generallyl diagrammatic showing of another embodiment of the i vention.-

Figure 'I is a fragmentary an partly sectional 5U view o1' a recording meter of the apparatus of As particularly illustrated, the device of present invention is associated with fractionating apparav tus in which the controlled product comprises a 55 mixture of the less volatile fractionsof hydro'- carbon liquids such as fuel oils and gasolines 'and alcohols, etc. The apparatus shown comprises a conventional bubble-tray tower 6 having provided in the upper and major portion thereof a plurality of superimposed bubble trays'l of suitable structure. 'Ihe lower tower portion is seen to provide a kettle portion 8 in which to heat the liquid being treated. A duct 9vsupplies the raw liquor to the bubble trays at a constant rate; as shown, the valve I0 is provided for controlling the' 10 flow of liquor through the duct 9 and a heatexchanger I Il isoperativlyinterposed in said duct whereby to preheat said liquor. I

The liquid in the kettle 8 may be heated to the desired temperature by means of a heating coil 15 I2 interposed in a pipe I3 through which a heated iiuid is continuously passed; in practice, the heating `fluid is usually steam and the liquid in thev kettle is heated to boiling therewith. A valve I4 controls the iluid flow. through the pipe I3 and coil I2 whereby, with the other operative factors of the apparatus held constant, the rate of heat discharge from the coil may be adjusted to a desired degree.

The unevaporated liquid is arranged to constantly escape at the bottom of the kettle through a duct I5. As particularly disclosed, the heatexchanger I I is interposed in the duct I5 whereby the inilowing liquor to the fractionator is preheated and the liquid discharging through the duct I5 is partially cooled therein. A secondheat-exchanger I5 is interposed in' the duct I5 at the delivery side of the heatexchanger I2 for completing the cooling of theA discharged liquid.

For maintaining aconstant liquid level in the kettle, a valve Il is provided in the duct I5 at the discharge side o f the heat-exchanger I5. The valve I'I is preferably arranged for automatic operation; as shown, this valve, is of the diaphragm-motor type and is connected by means of 40 an air duct I0 with a float-controlled valve I9 which is operated by the liquid level in the kettle.

A duct 2| supplies the operating air to the valve I9 from a compressed-air main 22 connected with a suitable source (not shown) of compressed air.' 45 It is to be understood, however, that the valve Il might -be arranged for mechanical, rather than pneumatic, operation by means of a suitable oatactuated mechanism.

. Afcooling liquid fromvany suitable source is arranged to flow to and from the heat-exchanger IB through ducts 23 and 24 respectively, and a ow control valve25 is provided in a said duct. Both generally, and for a speciiic purpose to be hereinafter brought out, it is desirable that the liquid product be ydelivered through theV duct l5 at a substantially fixed and predetermined temperature, and control of said temperature is c onveniently arranged to be effected through an automatic or manual adjustment of the Valve 25.

The gaseous products resulting from the heating, and other treatments of the liquor in the tower 6 are arranged to ow from the top of the tower through a, duct 26 and to a condenser 21 wherein a portion of the gases are condensed to form a, distillation product whichis known in the art as a reux liquid. The desired cooling in the condenser 21 is arranged to be effected by means of a cooling coil 28, a valve V29 controlling the fluid iiow' rate through the coil. The uncondensed gases from the condenser 21 are ar- -ranged to escape, as to waste or for use as fuel,

through a duct 3| having a suitable back-pressure valve therein.

Part of the condensate, or reux, in the condenser 21 is arranged to be delivered back to the tower 6 through a duct 32, a motor driven pump 33 being interposed in the said duct for the purpose. A valve A34 is also interposed in said duct at the dis- 'charge side of the pump 33. Excess reflux is disa bottom, or low-volatility fraction which is discharged through the duct I5 as a liquid product, an intermediate, or top, condensed fraction which is discharged through the duct 35 as a liquid top product, and the lighter, or high volatility, fraction which does not condense at ordinary temperatures and is discharged through Athe duct 3| in gaseous form. With the various control valvesv set, an operative balance of thepressure and temperatures in the apparatus is `created and the aforesaid products are each produced under fixed conditions of pressure and temperature. If the raw liquor is of costant composition, the said products will all be of constant composition, and continuous operation of the apparatus would continuously produce uniform results.

As a. matter of fact, raw liquors for fractionation, lsuch as crude oils and natural gasolines from wells, are very seldom of an unvarying composition, henoe fractions thereof which are separated in a refining apparatus without regulation to meet variations in their compositions are neither of constant composition or volatility. No

regulation of fractionating apparatus is generally possible for the production of products which are of both constant composition and volatility, and

adjustment must therefore be made for either one or the other of said qualities rather than for both.

Generally, though not exclusively, in the art of refining natural liquid hydro-carbons to produce fuels, lubricants, etc., the production of a product of definite volatility is of major importance, and it is to the `provision of means for insuring the continuous production of a product of constant volatilitythat the present invention particularly relates.

In the apparatus shown, the aforesaid operating conditions are seen to be chiefly controlled by the supply valve I0, the heating-coil valve I4,

sample through the coil 46 and cup 42. controlled valve 49 in the cup 42 operates to mainproducts'should change, an appropriate adjust-- ment of one or more of said valves is required to bring the volatility of said product back to its desired value.

For effecting the aforesaid regulation of a fractionator apparatus, a control unit 4I is provided, said unit arrangedv to have a continuous liquid sample from some part of the apparatus ow therethrough, and to measure and/or utilize the vapor pressure of the sample as a basis and/or means for appropriately setting a control valve of theapparatus to maintain a desired degree of Volatility for a product. Essentially, and as is i particularly brought out in the detail views of IFigures 2 and 3, the control unit 4l comprises a closed evaporation cup 42 through which a sample stream is arranged to continuously flow at a constant rate while it is maintained at a constant temperature, and indicating and control means operated by the vapor pressure in the cup.

, As particularly illustrated, the cup 42 is dis-' posed centrally in a liquid bath 43 provided in a cylindric heat-insulated vessel 44 hving a cover 45. stant temperature whileI supplying any heat of vaporization needed in the cup or absorbing any heat of condensation emanating therefrom on account of a volatility change in the control sample.

The bath 43 must be kept at a con-l A further function of the bath 43 is to provide the sample to the cup at a constant temperature, and to this end the incoming sample is caused to flow through a coil 46 immersed in the bath and coaxially surrounding and discharging into the cup. The cup and coil are preferably formed of heatconducting material for facilitating any heat transfers required 'for maintaining a constant temperature of the sample portion in the cu`p.

Thecontrol sample enters the coil 46 from a duct 41 extending into the vessel 44 and having a now-control valve therein; as illustrated, the valve 48 is of a differential diaphragm motor type and is controlled from an orifice plate 48 whereby to automatically insure a fixed fiow rate of the A iioattain a xed liquid level in the cup, and discharges into a duct 5l for conveying the tested sample where desired. A recording thermometer 52 has its bulb immersed in the sample in the cup whereby the temperature conditions therein are both indicated and recorded for reference in adjusting the control unit.

Means are provided for automatically controlling thetemperature of the bath 43 asA may be required, said means comprising an electric i heater 53, a motor driven stirrer 54, and a circuit closing thermostat 55, all operatively immersed in the bath. The heater A53 is arranged to derive power from a suitable source through a suitable relay switch 56 which is controlled by the thermostat 55 in such a manner that the heater is energized when, and only when, the bath tem--V lperature is below a certain predetermined value.

'Ihe stirrer is constantly operated by an electric motor 51. As shown, the motor 51 is mounted on lthe cover 45, andthe heater 53 and stirrer 54 and control thermostat 55 all depend from said cover into the bath.

It will be noted that the bath v43 may be of water or oil or some other liquid, and will be suitably maintained at a properV depth in the vessel 44. Since it is a general practice in the art to test volatility at a temperature of 100 degrees Fahrenheit, the various control factors for the bath 43- are preferably so adjusted that the sample portion in the cup is automatically maintained at the aforesaid temperature; at' such a temperature either water or an oil will be found satisfactory as a bath liquid for present purposes.

As is'previously indicated, the vapor pressure generated and produced in the cup 42 is utilized for control purposes, and to this end the top of the cupcavityisconnected through a duct 6I with an expansion, or diaphragm, chamber 62 forming part of the structure of a pressure ,recording meter 63. As is usual in such meters, a movable wall 64- of the chamber 62 is arranged to control the disposal of a push rod 65, which rod in turn is arranged to constantly engage the Wall 64 with a degree/of pressure which varies with the degree of displacement ofl the wall 64 as the chamber 62 is expanded and, through suitable connecting mechanism, controls the positioning of the meter hand 66 with respect to a rotary record dial 61.

'I'he rod. 65 is also operative as a valve stem in va suitably formed fluid passage 68 which it travferses, said passagev being interposed between ducts 69'and 1I of a fluid pressure line` which in the present instance is arranged to carry air.

A valve plug 12 is adjustably vcarried on the rod,

portion within 4said passage, and is operative in the passage to vary the permitted air flow therethrough as the rod is displaced. As particularly illustrated in Figure 3, the effective passage between the ducts 69 and 1I is arranged to be decreased as the meter -indications are increased with an increased pressure in the cup whereby this valve is reverse-acting with respect to th meter.

Inthe described valve and meter combination,

thel same being'known generally in the art as a recorder-controller, ift will be noted that the pase sage 68 and the connections 'for the vducts 69 and 1I are provided in a member 13 whichV is threadedly and replaceably engaged with and between .atubular meter body portion 14 and a housing y 15 for 'the expansion chamber 62. It only a. re-

cordingmeter is desired, the member 13 may ,be

lomitted and the housing 15 may be directly secured to the extension 14; in this case, an appropriate shorter -rod 55 lacking a valve plug would be substituted for the rod 65 as shown in Figure '1'. particularly shown in the installations of t Figures 1, 4 and 6, ashut-o valve 1U is provided eiIective as a control means -should suclrbe de-4 in `theduct 69 for closing to render the v'alv`e in- For most dependable results with the evaporation cup 42,' it is desirable that the vapor space provided by the cup 42 and the duct 6I andthe expansion chamber 62"contain a minimum of air. Accordingly, when the unit 4I is rst cond nected in a line to`be'sampled, a valve 50 in the cup discharge line 5I is closed and the said vapor space opened as high therein as is practically possible to permit an initial illling of the space-with -the liquid sample. As particularly shown, that `portion oi' the expansion chamber housing 15' `vwhich engages lthe upper end of the duct. 6I and fmounts' the expansion chamber -62 is provided with a' passage extending radially from said space and normally closed by a screw plug 16, the removal oi' said plug permitting the aforesaid ilow ,of liquid into the vapor space to expel substantially all of the air therefrom. When the vapor ,space is lled with the sample liquid, the plug 16 is replaced, and a subsequent opening of the valve `5I! permits a lowering of the liquid to its normal level in the lcup as controlled by the oat'valve 49. Should air afterwards accumulate in the aforesaid vapor space, such air may be removed by proceeding in the manner described for rendering the device initially operative. It will be 4understood that the valve 5|! is normally open to a constant degree whereby the resistance in the line 5I may be and remain constant, said pressure being necessarily less than that in the cup 42.

As particularly shown in the assembly of Figeure 1', the control unit 4I is applied for producing the bottom, or heavier, fraction to have a constant volatility through control of a back-presvsure valve in the 4duct 36in directaccordance with the volatility `of a sample taken from the product in the duct I5. In the present arrange` ment, the supply valve Il! is of adiierential diaphragm motor type and is controlled from an orifice plate I0' in the supply duct 9 whereby to.v I

insurea constant flow rate through the valve I Ii even though the supply pressureI should vary.

The heating-coil valve I4 is a diaphragm valve,

orifice p1ate`34. in the duct 32.

Referring now to the application of the control unit to the described tractionating apparatus, `a reference to Figure 1 discloses that the unit 4Il isl thereimarranged to control the volatility of the discharged bottom product through utilizing a sample from the duct I5 as a control means for the gas vescape duct 3l. Accordingly, the duct.v

41 is connected to the duct I5 as a bypass there@- from and forreceiving a continuous sample iiowing through the sample cup 42, the valve duct 69 is-conected with the compressed air main 22, and the valve duct 1I is,connected to an air controlled diaphragm motor valve 11 which is interposedy in'the duct 3l asa back-pressure valve therein. The duct 1I is provided'with a constantly open branch 18 having a needle valve 19 operative therein; in this manner, regulationv of the actuation of the valve 11 may be effected inj adjusted proportion to the actuation of the meter control rod and the vapor pressure which actuates it. It will be understood that the valve 12 is never fully closed and that, by reason l of the back pressure created in the duct 1I by the needle valve 1.9, any `diierence in the air pressure against the diierent sides of the valve 12 is not sufcient to appreciabiy affect the movement.`

of the diaphragm 64 and the meter indications which are controlled by the rod. y

' The ductll may also have therein a-hand operated throttlevalve and a pressure gauge 8|. When the valve 11 is' controlled romthe unit 4I in the described manner, the valve Il is left open. If the valve 11 isnot tobe used, the

valve 80 would be appropriately set as a backpressure valve for the system.

It will now be noted that a vapor pressure will be set up in the constant-temperature sample in the cup 42 in direct accordance with that of the sample portion in the cup, said pressure changing if the volatility changes. Momentary changes lin the volatility of the sample will, of course, produce but a negligible effect on the cup pressure, but sustained changes in the volatility of the sample will effect the cup pressure in accordance therewith. Since the volatility of aliquid changes with the temperature thereof, the automatic maintenance of a constant sample temperature, as by the previously described operation of the unit 4I, is obviously an essential feature of the device.

The aforesaid vapor pressure in the sample cup is arranged to control the back-pressure valve 11 in such a manner that a change in the volatility of the sample will cause such a change in the tower pressure as Will bring the volatility of the sampled product back to its required value.

` volatility than the product to be controlled. Inv Vthe arrangement of Figure 4, it is the reflux product which is to have a constant volatility,-

Thus, should the volatility of the controlled product increase to produce an increased pressure in the cup 42, the back-pressure valve 11 would be opened to lower the .tower pressure and thereby decrease the volatility of the product, the kettle temperature being held constant by the hereinbefore described automatic operation of the heating-coil valve I4.

In some arrangements of fractionating apparatus, a volatility control through a product sample may introduce an undesirable element of control lag, and in such a case it may be desirable to effect the control with .a sample of untreated liquid from the system. One such application of the unit 4| is disclosed in Figure 4 wherein a sample of raw liquor taken from the feed duct 9 is utilized to controlf the supply of heating fluid to the heating coil I2. In this instance, theA air duct 1I from the unit 4| is connected directly to the valve I4 in lieu of the thermometer I4', andthe sample supply duct 41 is connected as a bypass from the duct 9 at a point thereof ahead of the heat-exchanger II. In lieu of the valves 11 and 80, an automatic relief valve 82 is provided in the duct 3| whereby the pressure in the system may be held constant. 'I'he record and control afforded is, of course, similar to that Where a sample is taken from a product.

Since it is a product which is to be controlled, either a top or bottom product must be continuously tested for volatility, it being noted that a sample not a product might well have a different and a sample is accordingly taken from a point of the duct 35 ahead of the valve 36 and delivered to an evaporation cup 83 at a constant temperature and flow rate; as particularly4 illus- Y,

trated, a duct 84 conducts the sample to the cup through acontrolled heat-exchanger 85 and an automatic flow` control vvalve 86. The temperature of the sample leaving the heat-exchanger B5 is operative through a thermostat 81 interposed in the duct 84 to so regulate a valve 88 in the heating fluid duct 89 as to discharge the sample from the heat-exchanger at a constant temperature. The sample is arranged to flow from the cup 83 through an overflow duct 90 having a liquid trap 9| therein to prevent the escape of vapors from the cup therethrough. The

increased' kettle heat.

cup 83`is sealed except for a vapor-discharge duct 92 in which a constant degree of suction is maintained, as by means of an ejector 93 and an automatic flow control valve 94 operative in the duct. The ejector 93 may be actuated by yair derived from the air main 22 through a valved duct 95 `connected therewith.

Through the aspiration of the vapors from the sample in the cup 83, said sample will be cooled, and the difference in the temperatures of the sample in the duct 84 and cup 83 is a measure of the volatility of the sampled product. Accordingly, recording thermometers 96 and 91 are operatively installed in thel cup and duct ref spectively whereby the necessary information is available for determining the results of the control afforded by the unit 4I. In this manner, a proper control of a product may be assured through a non-product sample from the system and with an avoidance of control lag. It will be -noted that the present Volatility testing arrangement is a modification and adaptation of that disclosed in my United States Patent No.

.1,901,104, dated March 14, 1933.

With the control arrangement of Figure 4, it will be understood that if the volatility of the sample of raw liquor increases, the resulting increased pressure in the cup 42 should effect an opening of the valve |4 to increase the rate of heat supply from the coil I2 and so increase the heating in the kettle; in this manner the volatility of the tested top product may be held at the desired value through the automatic addition of further lower fractions thereto because of the Under these circumstances, the valve provided in the member 13 of the recorder-controller 63 would be reverse-acting as is 'shown in Figure 3. If, on the other hand, it is the bottom product which is to have a constant Volatility, and the volatility of the raw liquor increases, the same valve would be used at the recorder-controller, since under these circumstances the kettle heat should be increased to hold the bottom product volatility down by removing further light fractions therefrom.

In the embodiment of Figure 6, the control sample is taken from a bubble tray 1, and the control of the systeml is effected from a control and recording unit 4| at the valve I4 as in Figure 4.` I n the present arrangement, the gas discharge pipe 3| is provided with the pressure meter 8| and an automatic back-pressure Valve 82 as in Figure 4, the discharge pipe 35 for the top productI contains only the float-controlled valve 36 as in Figure 1, and the arrangement is otherwise as in Figures 1 and 4. Through the automatic control provided at the heating coil I2 in terms of a'partly fractionated' liquid in the system, the control lag is further minimized whereby this arrangement is particularly sensitive and dependable for the controlled treatment of a variable raw liquor.

In this instance, it is the bottom product which is to have a constant volatility, and a sample is accordingly taken from the discharge line I5 for continuous testing, For testing the bottom product, only the cup and meter portions of the previouslydescribed testing and control unit 4I are 64. The walls of the expansion chamber 62 act as a spring to resiliently resist an expansion of the chamber in such manner that the restoring force on the chamber wall 64 is proportional to the chamber-expansion displacement thereof. The present arrangement may also be that for the meter 63 of the meter and control unit 4|.

Essentially, the invention now disclosed is understood to concern devices for automatically maintaining the volatility of a mixed fraction which is continuously produced by any suitable fractionating and/or cracking apparatus, and to be generally applicable to other types of appa'- ratus than that particularly illustrated for set-` ting forth the present features of invention.

In illustrating the control operations of the various described embodiments, an increase above the desired volatility has been assumed in each case; it will be understood, however, that the disclosed control means Will operate in an appropriate manner if the volatility of a product should become less than that desired.

From the foregoing description taken in connection with the accompanying drawings, the advantages of the construction and method of operation Willv be Areadily understood'by those skilled in the art to which the invention appertains, and While I have described the principle of operation, together with forms of the device which I now consider preferred embodiments thereof, I desire to have it understood that the showings are primarily illustrative, and that such changes may be made, When desired, as fall Within the scope of the appended claims.

Having thus described my invention, I claim as new and desire to secure by Letters Patent of the United States the following:

1. In a continuously operable system for fractionating an initially liquid mixture, means acltin of the system, means continuously sampling a liquid other than a nal product in the system and including an evaporation cup, and means directly utilizing the vapor pressure generated in said cup by reason of the evaporation of the liquid sample in the cup to control said stabilizing means for providing a fractionator product of constant volatility.

2. In a continuously operable system for fractionating a liquid mixture by distillation to provide a plurality of products, control means of the system adjustable for stabilizing the operation of the system, means continuously sampling the liquid mixture and including a closed evaporation cup through which a continuous sample is arranged to flow at a constant rate, means automatically operative to maintain the temperature of the liquid in said cup at a constant value for partially evaporating the sample, and means continuously utilizing the vapor pressure generated in said cup to so regulate said control means of the system that a said product thereof will have a constant vapor pressure as it is produced by the system.

3. In a continuously operable system for fractionating a liquid mixture by distillation to provide a plurality of fraction products, control means of the system adjustable for stabilizing the operation of the system, means continuously sainpling the liquid mixture and including a closed evaporation cup through which a continuous sample is directed at a constant rate, means automatically operative to maintain the temperature of the liquid in said cup ata constant value, and means continuously utilizing the vapor pressure in said cup to so regulate said control means of the system that a said product thereof Will have a constant vapor pressure as it is produced by the system.

4. In a continuously operating fractionating system having elements cooperative to control the qualities of a product derived from a variable raw liquor, the method of controlling the product for constant volatility thereof Which comprises utilizing the vapor pressure of a continuous sample of unfractionated liquid from the system to automatically control said regulating means for the production of said product with a constant f" vapor pressure.

5.1In a continuously operating fractionating system having lelements cooperative to control the lqualities of a product derived from a variable raw liquor, the method of controlling the means for maintaining the constancy of the va por pressure of said product.

6. In a continuously operable system for fractionating an initially liquid mixture, means adjustable for stabilizing the fractionizing operation-of the system, means continuously sampling a partly treated liquid in the system and including a closed evaporation cup, and means directly utilizing the vapor pressure generated in said cup by reason of the evaporation of the liquid sample in the cup to control said stabilizing means for providing a fractionator, product of constant volatility. l

7. In a continuously operating fractionating system .having elements cooperative to control the quantities of a product derived from a variable raW liquor, the method of controlling the product for constant volatility thereof which comprises utilizing the vapor pressure ofa continuous sample of partly treated liquid from the system to automatically control said regulating means stant vapor pressure.

. FLOYD L. KALLAM.

G0 for the production of said product with a con- Y I

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