US1387475A - Evaporator control - Google Patents

Description

w, L. DE mm. EVAPORATOR CQNTRQL. APPLICATION FILED SEPT. 6, 1916- Patented Aug. 1 6,192i.

2 SHEETS-SHEET W/TNESSESN -i V QR; f M W r f A TTORNEY' INVENTOR ATTO Y w. L. DE BAU FRE. EVAPORATOR CONTROL.

' APPLICATION FILED SEPT- 6119's. 1,3 7,475, Patented Aug. 16, 1921.

. '2 SHEETS- SHEET 2.

on w .QPW M m I 5 u N hm J m\ w WILLIAM L. DE BAUFRE, 0F ANNAIOLIS, MARYLAND.

EVAPORATOR CONTROL.

.Speciflcation of Letters Patent. Patented Aug. 16, 1921.

Application filed September 6, 1916. Serial No. 118,726.

To all whom it may concern.

Be it known that I, WILLIAM L. DE BAU- FRE, a citizen of the United States, residing at Annapolis, in the county of Anne Arundel, in the State of Maryland, have invented a certain new and useful Evaporator Control, of which the following is a specification. My invention relates to improvements in evaporator controls-and has for its object the elimination of constant attention during operation of evaporators, by providing means of automatically controlling the supply of the primary vapor, the rate of feed of the solution to be evaporated and the rate of discharge of the concentrated solution.

A furtherv object of my invention is the utilization of the heat in the concentrated solution discharged from evaporators.

A further object of my invention is the improving of the economy and durability of evaporators.

And a further object of my invention is the providing of means to insure the safety of evaporators.

With the foregoing and other objects in view, my invention consists of the novel construction, combination and arrangement of parts as hereinafterspecifically described and illustrated in the accompanying drawings, wherein is shown the preferred embodiment of my invention, but it is understood that changes, variations and modifications can be resorted to which come within the scope of the claims hereunto appended.

In the drawings of the herein described embodiment of my invention Figure 1 is a diagrammatic view of an evaporator system, showing an evaporator in its relation to the source of primary vapor, to the source of solution feed, to the utilization of the various discharges by preheaters, feed heaters, etc, and to automatlc means of controlling the relations involved; and Fig. 2 is a similar view with modified forms of apparatus. Similar numerals refer to similar parts throughout the several views.

The source of primary vapor 1 may be an ordinary coal or oil fired boiler as shownin Fig. 1, or an electrically heated boiler as indicated in F ig.- 2. From boiler 1, the primary vapor is supplied through vapor main'2 to evaporator 3. When evaporator feed pump 4 and-boiler feed pump, 5 are vapor operated as represented in Fig. 1, the operating vapor vmay also be supplied from installation on shipboard).

-may be discharged through exhaust main 8 and, if desired, through pipe 9 into the evaporator as shown in Fig. 1. Evaporator feed suction pipe 10 from some source (such as the sea when installed on shipboard), and delivers it through pipe 11 and evaporator preheater 12 and pipe 13 to the solution space of evaporator 3.

The discharge of concentrated solution from evaporator 3 is controlled by weir box 14 and trap 15. The concentrated solution is drawn through a pipe from the placeof its greatest density (generally near the bottom of the solution s ace), and is discharged through the coil in t e boiler feed heater 16 on its way to waste (to the sea in case of In Fig. 2 a closed feed heater is depicted, while in Fig.1 the feed heater 16 consists merely of a coil immersed in the feed tank 17. The weir box 14 whether it be located outside of the evaporator shell or within the same must be connected to the upper part of the solution space of evaporator 3 by a pressure equalizing pipe 18, in order to maintain the same pressure within weir box 14 as within the evaporator shell 3. In Fig. 1 theweir box 14 is shown within the evaporator shell; in Fig. 2 it is shown located outside of the evaporator shell and within the shell of the boiler feed heater 16. Vapor from evaporator 3 passes through pipe 19 to the coil in preheater 12 where it is condensed, the condensed vapor being drained from this coil by trap 20 and discharged into tank 21 provided for it.

pump 4 gets its supply-of solution through The vapor condensed in the coil within evaporator 3 is drained by trap 22 and dis charged into feed tank 17,.or storage tank 23 ,as desired.

The liquid to be vaporized in boiler 1 is drawn by boiler feed pum 5 from feed tank 17 and is delivered by t is pump into the boiler either directly as indicated in Fig. l, or through the coil in closed feed heater 16 as represented in Fig. 2. In order to regulate the rate of solution feed to evaporator l 3, an automatic control valve 24. is provided, having a connection 25 to the evaporator.

In Fig. 1 this control valve is in the vapor line to the evaporator feed pump 4, and it controls the rate of feed by governing the speed of the pump; in Fig. 2 this control valve is in the delivery pipe 11 and throttles the feed directly. Control valve 24 is shown on a by-pass connection to facilitate the repair of the valve Without interrupting the operation of the evaporator.

As the vapor above the liquid in evaporator 3 is in the saturated state, there is for each pressure a definite value of its temperature and of its density to correspond. Consequently, the temperature or the density of the vapor may serve to operate control valve 24 according to the vapor pressure. Also, connections 25 may be made below the liquid level since the properties of the liquid vary with those of the vapor above.

In this description and in the drawings Fig. 1 and Fig. 2, the feed of solution is controlled by the pressure within the evaporator 3 and'the discharge of solution is controlled by the solution level therein. However, the same results may be accomplished with the controls reversed, that is, the feed controlled by the height of the liquid and the discharge controlled by the pressure.

An orifice of fixed and predetermined dimensions is provided in the pipe between vapor main 2 and the coil in evaporator 3 to supply the proper quantity of vapor for the working capacity of the evaporator. In Fig. 1 this orifice 27 is a part of the nozzles in ejector 26, in Fig. 2 it is in a diaphragm in the pipe. A safety valve 28 having a capacity corresponding to that of the fixed and predetermined orifice, is mounted on the solution chamber of evaporator 3. Evaporator stop valve 29 is mounted in the pipe between primary vapor main 2 and the fixed orifice 27 A water level gage 30 and a pressure gage 31 are provided on evaporator 3 to aid in its operation as described later.

The operation of my invention is as fol- I lows Assume the apparatus to be arranged substantially as represented either in Fig. 1 or Fig. 2, with the proper vapor pressure attained in boiler 1 and vapor main 2, but the evaporator 3 not yet in operation. Start evaporator feed pump 4 and fill the evaporator to its working level as seen in level gage 30. The by-pass of control valve 24 must be temporarily opened since the control valve will not open until its set working pressure has been attained in the evaporator to which the means of control are connected. Referring to Fig. 1, the valves on exhaust main 8 should be open and the valve on pipe 9 should be closed while starting the vapor driven pump 4. They may be reversed later if desired. The whole evaporation system is now automatically put into operation by opening wide the evaporator stop valve 29,

which of course should be opened slowly to prevent hammer in the pipes. All functions are cared for automatically during operation, provided the vapor pressure available at evaporator stop valve 29 is within the working limits required. Thus, the solution feed control valve 24 automatically regulates the rate of solution feed to the evaporator according to the pressure therein as indicated on pressure gage 31 and the weir box 14 and trap 15 automatically regulate the rate of discharge of concentrated solution by maintaining a nearly constant solution level as may be seen in level gage 30.

In the system of evaporation here described, a constant flow of the solution is maintained through the evaporator, this flow being necessary to carry off the latent heat of the primary vapor condensed therein. With a certain quantity of primary vapor available, as determined by the vapor pressure at valve 29 and the fixed size of orifice 27, the rate of solution flow will be a function of the temperature of the source of the solution and the temperature within the evaporator (or the pressure within the evaporator, since the pressure. must correspond to the temperature). A higher rate of flow than this relation gives would reduce. the pressure in the evaporator, and a lower rate would increase the pressure. Hence the proper rate of flow will be obtained by regulating it according to the pressure. he coils within evaporator 3 and preheater 12 are automatically drained by traps. The heating of the liquid fed to boiler 1 automatically takes place in feed heater 16, thus returning to the system heat which would otherwise be discharged to waste. The latent heat of the primary vapor being carried off by the concentrated solution discharged from the evaporator, the solution within the evaporator attains a maximum concentration much lower than that attained under the usual method of operation. Consequently less difficulty will be experienced with scale and the durability otthe materials employed in the construction of the evaporator Will be increased.

Should vapor pipe 19 become closed or the pressure control valve 24 fail to operate properly while stop valve 29 is open, there may be an accumulationof pressure in evaporator 3. Safety valve 28 will then auto matically open to prevent an excessive rise of pressure. The vapor generated within the evaporator will never be but very slightly greater than the quantity of primary vapor supplied through the orifice 27. Hence,

safety valve 28 will always control thepressure in the solution space within safe limits, if made with a normal capacity equal to that of the orifice at the maximum available primary vapor pressure. The shell of the evaporator may thus be safely designed for 9.

, trolled by the vapor in the solution space of pressure lower than that of the primary vapor. The primary vapor space, however, should be designed to safely withstand the maximum available boiler pressure unless a second safety valve of proper capacity is mounted thereon.

Having thus described my invention what I claim and desire to secure by Letters Patent is. v

1. In an evaporator control, an evaporator and a preheater in closed hydraulic connection embracing a feed into the preheater of a solution which is fedinto the evaporator, means in the preheater for condensing vapor from said evaporator, and an automatic control of solution feed to said evaporator consaid evaporator. 2. In an evaporator control, an evaporator containing evaporating and condensing compartments, means of supplying the said evaporating compartment 'w1th solution to be evaporated, a safety valve onthe said evaporating compartment, means for supplying a heating vapor of a definite maximum pressure to said condensing compartment and means for limiting the rate of supply of vapor to said condensing compartment to less than the capacity of said safety valve by an orifice of fixed and predetermined capacity through which the said vapor flows.

'3. In an evaporator control, an evaporator and automatic means for controlling the flow of solution through the said evaporator operated by the solution level therein in I combination with the pressure, temperature ordensity of the vapor therein. 4. In an evaporator control, an evaporator and automatic means for controlling the flow of solution through the said evaporator comprising means of maintaining a constant solution level therein in combination with j means for maintaining a constant pressure therein.

' 5. In an evaporator control, an evaporator,

an automatic control of solution feed to said evaporator controlled by the vapor in the solution space of. saidevaporator, automatic means for maintaining .a constant solution level in said evaporator, and automatic means for withdrawing the solution from a place of its greatest density.

6. In an-evaporator containing a condensing compartment and an evaporating compartment control, an evaporator, an. automatic control of solution feed to said evaporator the latent'heat of the orator controlled by the vapor in the said evaporating compartment, and automatic means for maintaining a constant solution level in said evaporator embracing a chamber with passages. extending both above and below. the solution level in said evaporating compartment.

7. In an evaporator control, a system comprising an evaporator and a preheater for heating the solution fed to said evaporator, means for condensing the vapor from said evaporator within said system, and automatic means for removing from the system in the solution discharged from sald eva said evaporator.

8.- In an evaporator control, a system comprising an evaporator and a preheater for heating the solution fed to said evaporator,

means for condensing the vapor from said evaporator within said system, and automatic means for removing from the system in the solution discharged from said evaporator the latent heat of the steam supplied said evaporator operated by the vapor and the solution'level in said evaporator.-

9. In an evaporator control, asystem comprising an evaporator and a preheater forheating the solution fed to said evaporator, means for condensing. the vaporfromsaid evaporator. within said system,'- automatic means for controllingthe rate of solution fed to saidfevaporator by the va'tporin said evaporator, and automatic means for con the solution discharged from said evaporator, and automatic means for controlling the flow of solution through said preheater, evaporator and feed heater by the vapor and the solution level in saidevaporator.

WI LIA L. DE BAUFRE.

Witnesses:

THOMAS W. KINKAID, J, S. KAUFFMAN.

steam supplied

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