US2423307A - Steam jet refrigeration apparatus - Google Patents

Description

July l, 1947. w. G. FRASER, 1mi-m. 2,423,307

STEAM JET REFRIGERATION APPARATUS Filed Jan. 16, 1945 IMWZNOZOU E w w S ma S w M .6.

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Pat'ented `Yuly 1, 1947 UNITED STATES 4Pii'l'lzrn o'FFicE,

- STEAM JET REFRIGERATION APPARATUS `Walter G. Fraser, Jr., Prospect Park, and George C. Taylor, Bala-Cynwyd, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application January 16, 1945, Serial No. 573,025

(Cl. (i2- 152) 12 Claims. 1

Our invention relates to a combined liquid distillation and vsteam jet refrigeration system and it-haszfor an object to provide a system wherebygreater economy of operation is effected.

It is an'oi.1"ler. .ob,iectl of our invention to provide a combined*liquidrdistillation and steam jet refrigeration syster'mwherein the number of pieces of apparatus required is reduced. I

It is still another object of our invention to provide a combinedfliquid distillation and steam jet refrigeration system` wherein the required boiler steam and the pumping power are reduced.

In certaini. industrial processes, there is a demand for relatively cold distilled water. To satisfy these demands, it is the usual practice to distill the,l required water using a conventional distillation or evaporator system, which vaporizes raw water and then condenses the purified vapor in a condenser of the evaporator system. The condensate or distillate is cooled to its processing temperature by using a conventional refrigeration system either of the lrriechanical or steam jet type, or byusing cooling water, if an adequate supply is available. Y

In using the conventional steam jet refrigeration system, it is the practice to either cool the distillate directly in the chilled water tank of the refrigeration unit, or to supply chilled water from the refrigeration unit to cool the distillate in a separate heat exchanger. In either case, it is the practice to operate the distillation unit and the refrigeration unit as separate systems, whereby the cost oi final cooled and purified liquid is high because of a large expenditure of boiler motive steam and pumping power as well as the requirement for additional equipment, such as pumps and heat exchange apparatus.

In accordance with our invention, we propose to intimately relate the distillation and refrigeration units as a combined system, in that the steam or vapor necessary to operate the refrigeration unit is supplied by the distillation or evaporator unit and the vapor generator in the evaporator is condensed and cooled by the refrigerationA unit. After passing through the refrigeration unit, the cooled distilled water is delivered to the required point of use inthe industrial process.

The distillation evaporator may be of the multiple ystage or effect type in which only the first stage is motivated by boiler steam. All additional stages are motivated by the evaporated vapor generated in therst or previous stage.

The steam jetrefrigeration unit may be of any suitable design which comprises a flash tank, an

ejector and a condenser. The ejector withdraws vapor from the flash tank, to cool the liquid therein, and it is motivated by steam or vapor generated in the evaporator. The condenser not only condenses the vapor discharged from the ejector but all excess steam or vapor generated by the evaporator unit not consumed by the ejector. Also, all of the condensate collecting in the condenser is pumped to the flash tank for cooling and then delivered to the point where it is required in the industrial process.

Thus, it can be seen that the evaporator condenser as used in the conventional vsystem is eliminated, and the condensate pump .of the condenser is utilized to pump the combined condensate from the condenser to the flash or chilled water tank, thereby eliminating an additional pump. Also, since the ejector is motivated by steam coming from the evaporator, boiler steam at this point is no longer necessary, as used in the conventional two separate unit system.

These and other objects are effected by our invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which the single ligure is a diagrammatic View showing our combined distillation and refrigeration system.

Referring now tothe drawing, the principal elements of` our combined liquid distillation and steam jet refrigeration system includes an evaporator Il), which, in the embodiment shown, comprisesa multiple stage or effect evaporator unit having a first stage II and a second stage I2 in which raw water is evaporated, and a steam jet refrigeration unit I3 which comprises a flash tank I4, means, such as an ejector I5, for evacuating the iiash tank, a condenser IG for condensing vapor discharged from the ejector, and a pump I'I for pumping condensate from the condenser to the flash tank.

Boiler steam at, for example, approximately 35 lb. per sq. in, absolute, 259 F., is supplied to the first stage I I of the multiple eiect evaporator I0 by a pipe I8 to a heat exchange coil I9 which is preferably immersed in raw make-up water or liquid supplied to the rst stage evaporator by a pipe 20. As the boiler steam passes through the heat exchange .coil I9, releasing its heat to the raw make-up water, it is condensed and the condensate passes through a condensate drain 2| and is returned to theboiler by means of a pipe 22.

As the boiler steam releases its heat in the heat exchange coil I9, the raw make-up water is Vaporized and steam at, for example, approxi- 3 mately 28 1b. per sq. in. absolute, 246 F., passes out of the first stage or eHect evaporator II through a conduit 24 to the second stage I2 of the multiple-stage evaporator. The second stage I2 is similar in design to the first stage II however, in this case, the steam leaving the first stage II is utilized to evaporate raw make-up water in the second stage of the multiple-effect evaporator i0. Thus, conduit 24 is connected and supplies steam or vapor to a heat exchange coil 25 which is also preferably immersed in raw make-up water. The second-stage evaporator I2 is supplied with raw water or liquid through a pipe 26 which is connected to the raw water supply pipe 20.

The vapor passing through the heat exchange coil 25v releases its heat to the raW make-up water and is condensed, after which it flows as pure water through a condensate drain 21 and a conduit 28 to the condenser I8. The condensate flowing from the conduit 28 into the condenser I 6 will thus be cooled to the temperature therein.

The raw make-up water in the second stage I2 of the evaporator unit is vaporized by the first stage steam and steam at, for example, approximately 21 lb. per sq. in. absolute, 230 F., leaves the second stage through a conduit 29. The rate of flow, in lbs. per hour, is somewhat less than the iiow of steam from the first stage evaporator. Due to the fact that this steam or vapor has a sufficiently high pressure, the conduit 29 is connected to and supplies motivating steam for operating the ejector I which is associated with and removes vapor from the flash tank I4.

The ejector I5, which is designed to operate, for example, at approximately 21 lb. per sq. in. absolute, is of conventional design having its suction end connected to the flash tank I4 to reduce the pressure therein to, for example, approximately .2 lb. per sq. in. absolute and its discharge end communicating with the interior of the condenser I6 operating at approximately 28.5 inches of mercury. The discharge end of the ejector I5 delivers its compressed vapor to the condenser I6, wherein the vapors are condensed, and the condensate collects in a hot well 31 located at the bottom of the condenser |69 This hot well is connected by a pipe 38 to the pump I1 which delivers the purified Water or distillate through a conduit or spray pipe 32 to the flash tank I4 for cooling. The flash tank I4 is also of conventional design and the purified water to be cooled is admitted into the tank I4 through the spray pipe 32, having spray openings 33 therein, and is cooled to approximately 54 F. The cooled water collecting in the bottom of the flash tank chamber 3| flows through a pipe 34 to a pump 35 which pumps the purified and refrigerated water through a pipe 36 to the point where it is required in the industrial process.

Due to the fact that the second stage or effect evaporator I2 generates more steam or vapor than the ejector I5 can utilize, We provide a bypass conduit 4I to by-pass steam or vapor around the ejector, under control of a pressure-reducing or relief valve 42. In the example given, ap# proximately 5300 lb. of steam per hour is utilized by the ejector I5 and approximately 12,200 lb. of steam per hour will flow through the by-pass conduit 4I. Thus, slightly less than one-third of the steam generated in the second-stage evaporator is utilized by the ejector I 5, the remainder being by-passed. However, the quantity of steam by-passed depends upon various design conditions. The pressure-reducing valve is adjusted to the operating pressure of the ejector I5 so that the steam generated by the second-stage evaporator I2 exceeding the consumption limit of the ejector I5 increases the pressure therein to a predetermined value, and causes the' pressurereducing valve 42 to operate to by-pass the excess steam or vapor directly to the condenser I6 without performing work on the system. Also it might' be desirable, under certain conditions, to actuate or adjust the by-pass valve 42 manually.

'I'hen condenser I6 if of a conventional design, having the usual cooling water inlet 44 and outlet 45 for supplying cooling water to condense the steam or vapor discharged into the interior thereof, and also having a pump or ejector 46 for removing air and noncondensable vapors. However, the condenser I6 is provided with three inlets to the steam condensing chamber, an inlet 41 to receive steam from the ejector I5, an inlet 48 to receive steam from the by-pass conduit 4I, and an inlet 49 which communicates with the condensatel conduit 28 leading to the heat exchange coil 25 in the second evaporator stage I2. The condensate or purified water collected therein and delivered to the flash tank is a mixture of distillate coming from both the first and second evaporator stages and the ejector I5.

All the pieces of apparatus used in this combined distillation and refrigeration system may be of any suitable standard design.

The flash or chilled water tank I4 is often 'referred to as an evaporator, but we have re- Summary of operation The operation of our combined liquid distillation and steam .let refrigeration system may be summarized as follows:

Boiler steam is delivered to the coil I9 in the first stage I I of the multiple stage or effect evaporator unit II) and returned as condensate to the boiler. Steam or vapor generated in the rst stage passes to the heat exchange coil 25 in the second stage, wherein it is condensed and passes to the condenser I6.

The steam or vapor generated in the second stage I2 of the evaporator motivates the ejector I5, The ejector operates to remove vapor` from the iiash tank I4 to reduce the pressure therein,

thereby removing heat from the liquid therein by partial evaporation. The vapor removed from the fiash tank I4 is compressed in the ejector I5 and delivered to the condenser I6 wherein it is condensed. All excess steam not required by the ejector I5 is by-passed through conduit 4I and the pressure-reducing valve 42 directly to the condenser I6 wherein it is also condensed. The combined condensate collecting in the hot well 31 is delivered to the flash tank I4 wherein it is sprayed and whereby it is cooled. As the cooled distillate collects in the bottom of the flash tank I4, it is conducted to the required point of use in the industrial process.

Thus it can be seen that we have provided a combined distillation and steam jet refrigeration system which, compared to the usual two separate evaporator and refrigeration systems, requiresI fewer individual pieces of apparatus and is therefore a more compact system, Also it requires a reduced expenditure of boiler motive steam and pumping power.

It is to be noted further that more or less than tw@ Stages of evaporator may be used for vamore than two stages are used in the system,

steam from the last stage, or a portion of an intermediate stage, will be utilized to operate the ejector, depending upon the design condil tions.

It is to be understood that the steam pressures, temperatures, and fiowconditions given` at various parts of the system are only approximate and are for a particular design and given 1g Only by Way 0f an example. The steam pressures, temperatures and proportionate rates oi ilow will vary with each unit depending upon the cooled water requirements and upon the quality and quantity of boiler steam available; and may be gg readily determined by one skilled in the art.

While we have shown our invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible or various changes and modiiications without g5 departing from the spirit thereof.

What we claim is:

l. In a distillation and steam jet refrigeration system, the combination oi an evaporator for vaporizing liquid, means for supplying heat to 3 said evaporator to vaporize the liquid therein, a flash tank adapted to contain liquid to be cooled, means for removing vapor from said ilash tank to effect cooling of the liquid therein, said vapor removal means being motivated by vapor generated in said evaporator, a condenser for conthe liquid therein,

ejector with vapor generated in said evaporator,

therein to vaporize the water, means for supplying steam to said tube and `for removing the condensate therefrom, a `flash tank adapted to contain liquid to be cooled, an ejector for removing vapor from said flash tank to effect cooling of means for motivating the a condenser for condensing vapor discharged by said ejector,lmeans for conveying the condensate from said tube to the condensing space in said condenser, and means for supplying condensate from said condenser to the ilash tank to be cooled f therein.

6. In a distillation and steam -jet refrigeration system, the combination o! an evaporator for vaporizing liquid, means for supplying heat to said evaporator to vaporize said liquid, a flash tank adapted to contain liquid to be cooled, an ejector for removing vapor from said ilash tank to eiect cooling of the liquid therein, means for motivating the ejector with vapor generated in said evaporator, a condenser for condensing vapor discharged by said ejector, a conduit and a valve therein for conducting vapor from the evaporator directly to the condenser and by-passing l said ejector, Aand means for supplying the condensate from said condenser to the ilash tank to be cooled therein. n

7. In a distillation and steam jet refrigeration system, the combination of an evaporator for vaporizing make-up water, a heat'exchange coil in said evaporator for vaporizing make-up water and for condensing steam supplied thereto, a flash tank adapted to contain liquid to be cooled, an ejector for removing vapor from saidy ilash tank to effect cooling 'of liquid therein, means densing the vapor generated in said evaporator for motivating the ejector with vapor generated and the vapor removed from said dash tank, and in the evaporator, a condenser ior'condensing vameans for supplying all of the condensate from por,` discharged by said'ejector, a conduit for con- Slid COl'ideliSer t0 the flash tank for cOOliIig. A0 ducting vapor from the evaporator to the gon.. 2. In a distillation and steam jet refrigeration denser and by-passing said elector, valve means system, the combination of an evaporator for disposed in said conduit and responsive to a prevaporizing liquid, means for` supplying heat to determined pressure whereby excess evaporated Said evaporaim t0 VapOrZe said liquid, a flash vapor not consumed by the ejector will flow tank adapted to contain liquid to be cooled, an through the by-pass conduit and be condensed, ejector fOr remOVing VPOI frOm Said flash tank a conduit for conducting condensate in the heat to effect cooling of the liquid therein, means for exchange coil to the condenser, and means for motivating the ejector with vapOr generated in delivering the condensate collecting in the consaid evaporator, a condenser for condensing vadenser to the flash tank to be cooled therein, por discharged by Said ejector, means fOI SUP- 8. In a distillation and steamjjet refrigeration plylng all of the condensate from said condenser system, the combination of a multiple-stage evapto the flash tank for cooling, and means for'reorator comprising a first stage for vaporizing liqmoving the cooled liquid from the ilash tank. uid, means for supplying heat to vaporize the 3. Ina distillation and steam jet refrigeration liquid therein, a second stagg for vaporizing nqsystem, the combination'of an evaporator fOr uid, means for utilizing the va r generated in vaporizing raw make-up water, said evaporator the first stage to vaporize the liquid in the second having a heat exchange Coil therein to vaporize stage, a flash tank adapted to contain a liquid to theI raw water, means for supplying boiler steam be coo1e'd, an ejector for removing vapor from to said heat exchange coil and for removing the said flash tank to effect coolingl` of the liquid condensate therefrom, a flash tank adapted t0 $0 therein, means for motivating the ejector withy contain liquid to be cooled, an ejector for removvapor generated in said second stage oi the evap# ing Vapor from said iiash tank to effect cooling orator, a condenser for condensing vapor diso the liquid therein, means for motivating the charged by said ejector, and means for supplying elector with vapor generated in Said evaporator. condensate from said condenser to the ilash tank a condenser for condensing vapor discharged by u to be cooled therein, said ejector, and means for supplying condensate f 9. The combination as claimed in claim 8, infrom said condenser to the ilash tank to be cooled cluding a conduit for conducting vapor from the therein. second-stage evaporator to the condenser and 4. The combination as claimed in claim 3 ity-passing said ejector, valve means disposed in wherein all of the condensate collecting in the l'm said conduit responsive to a predetermined prescondenser is delivered to the ilash tank to be cooled therein. f

5. In a distillation and steam jet refrigeration' system, the combination of an evaporator for vaporizing water, said evaporator having a tube sure whereby the vapor generated in the second stage of the evaporator not consumed by the ejector passes through the by-pass directly to the condenser and is condensed.

10. In a distillation and steam jet refrigeration system, the combination of a multiple-stage evaporator comprising a first stage for vaporizing liquid, means for supplying heat to vaporize the liquid therein, a second stage for vaporizlng liquid, and a heat exchange coil disposed in the second stage to vaporize the liquid therein and utilizing the vapor generated in the rst stage, a ash tank for cooling liquid therein, an ejector associated with the flash tank to evacuate the chamber, means for supplying motivating vapor to said ejector from said second stage of the evaporator, a condenser for condensing vapor discharged from said ejector, means for conducting the condensate from the heat exchange coil in the second stage of the evaporator to said condenser, and means for supplying condenser condensate to the flash tank to be cooled therein.

11. In a distillation and steam jet refrigeration system, the combination of an evaporator comprising a first and a second stage for vaporizing raw make-up water, a heat exchange coil in said rst stage to vaporize the raw Water therein, means for supplying boiler steam to said heat exchange coil and for removing condensate therefrom, a heat exchange coil located in the second-stage evaporator to vaporize the raw water therein, means for conducting the steam generated by the first stage to said heat exchange coil wherein the rst stage steam is condensed, a flash tank for cooling pured water by subjecting the flash tank chamber to a low pressure, an ejector associated with the flash tank for subjecting the chamber to a low pressure, means for motivating the ejector by steam generated in the second stage of the evaporator, a. condenser for condensing steam and vapor discharged by said ejector, a conduit for conducting steam generated in the second-stage evaporator to the condenser and by-passing said ejector, a pressure-reducing valve disposed in said by-pass conduit and responsive to a predetermined pressure for by-passing steam around said ejector to the condenser wherein it is condensed, a conduit for delivering condensate from the heat exchange coil in the second stage of the evaporator to the condenser, and means for delivering condensed liquid from the condenser to the ash tank to be cooled therein.

12. In a distillation and steam jet refrigeration system, the combination set forth in claim 1l wherein the last-named means delivers all of the condensed liquid from the condenser to the flash tank to be cooled therein.

WALTER ERASER, JR, GEORGE C. TAYLOR.

REFERENCES CITED The following references le of this patent:

are of record in the Number Date Humble Dec. 15, 1936

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