US1387476A - System for evaporating water - Google Patents

Description

UNITED STATES PATENT OFFICE.

WILLIAM 13. DE BAUFRE, OF ANNAPOLIS MARYLAND.

SYSTEM FOR EVAPORATING WATER.

Application filed January 23, 1917. Serial No. 143,970.

To all whom it may concern:

Be it known that I, WILLIAM L. DE BAU- rnn, a citizen of the United States, residing at Anna olis, in the county of Anne Arundel and tate of Maryland, have invented a certain new and useful System for Evaporating Water, of which the following is a specification.

My invention relates to the production of fresh water, especially for boiler feed purposes, and has for its object a reduction in the'expense of producing such make-up feed water by improving the heat efliciency of the system. A further object of my invention is to render the operation of the system readily controlled, largely automatic and reasonably safe.

With the foregoing and other objects in view, my invention consists of the novel construction, combination and arrangement of parts as hereinafter specifically described and illustrated in the accompanying drawings, wherein is shown the preferred embodiment of my invention, but it isunderstood 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, Figures 1 and 2 are diagrammatic views of my system for evaporating water, showing an evaporator with its preheater and feed pump in relation to a steam boiler with its feed pump,

feed tank and feed heaters. In Fig. 1 the two feedheaters are of the closed type, the steam being condensed in a compartment separate from that in which the boiler feed water flows; in Fig. 2, one of the feed heaters is represented as of the open type, the heating steam being condensed 1n direct contact with the water. Similar numerals refer to similar parts throughout the two figures.

plied through steam main 2 to evaporator 3,

to evaporator feed'pump 4, to boiler feed pump 5, and to such other apparatus as it may be desired to operate. The exhaust steam from these pumps, augmented by that from other auxiliaries not shown, is discharged'by exhaust main 6 through valve 7 to evaporator 3, through valve .9, to boilerfeed heater 8, throu h valve 11, to boiler feed heater 10, and t rough valve 12 to the atmosphere or preferably to a condenser (not shown) in order to conserve the fresh water. In Fig. 2, the valve 12 is shown in a pipe leading from the'open feed heater 8, rather than directly from the exhaust main 6 as indicated in Fig. 1.

The evaporator feed pump 4 draws the water to be purified by evaporation from some source 13 and discharges it through preheater 14 into evaporator 3. When this impure water becomes too concentrated to carry the evaporation further, it isdischarged through' valve .15 to waste at '16. The pure water vapor produced by the evaporation of the impure water in evaporator 3, is conveyed by vapor main 21 to the preheater 14 and through valve 22 to feed heater 8.

The fresh water resulting from the condensation of steamor water vapor in evaporator 3, in preheater 14, in feed heater 10, I

and in feed heater 8 (Fig. 1 only), is dis charged by traps 17 and drain main 18 into the proper fresh water receiver. This receiver may be the feed tank 19 of Fig. 1 or the open feed heater 8 of Fig. 2. Through pipe 20 is returned freshwater from other apparatus operated by steam from the boiler shown. If desired, the discharge from one or more of the traps 17 may be reserved for some other than boiler feed purpose; for example, the fresh water from the preheater may be usedfor drinking.

In Fig. 1', boiler feed pump 5 is connected to draw its supply water from feed tank 19 and force it through the two closed feed heaters 8 and 10 in series to boiler 1. In Fig. 2, the supply is taken from open feed heater 8 by feed pump 5 and forced into =boiler 1 through closed feed heater 10. ''In either case, after being heated in feed heater 8, the feed water is further heated in feed heater 10 before reaching boiler 1..

The exhaust steam supplied evaporator 3 through valve 7 is augmented when desired by live steam through valves 24 and 25. .The provision of an ejector 28- enables the live steam to entrain vapor drawn from evaporatorfi through valve 26 (if open) and to compress it to a higher pressure and correspondingly higher temperature, so that this compressed vapor may be condensed by the impure water undergoing evaporation in evzporator 3. 4 v

ome of the various'valves shown may be automatic in action as will now be explainedi Valve 25 may be a check valve which will automatically allow steam (or vapor) to pass from ejector 23 to the steam space within evaporator 3 but will prevent the return of exhaust steam when the ejector is not in operation. Valve 26 may be of a similar type to allow vapor to pass from evaporator 3 to ejector 23 but prevent its return. Valve 7 may be arranged to automatically allow exhaust steam from main 6 to flow into evaporator 3 when the pressure therein falls below a predetermined value. A more useful functioning, however, would be obtained by arranging it to automatically open when the exhaust pressure exceeds a set value and remain closed below that set value. Valve 7 might also be designed to open when a given difference in pressure occurs.

Valve 9 may also be of the automatic type to offer further relief to the exhaust steam when a somewhat higher pressure is reached than that for which valve 7 is set. In Fig. 2, complete relief of the exhaust steam must be afforded by valve 9 (in addition to valve 7), and valve 12 should be made automatic to relieve the pressure in open feed heater 8 at some chosen pressure therein. In Fig. 1, however, further relief for the exhaust steam is afforded by valve 12 set to open at a still higher pressure than valve 9. In Fig. 1 is also shown the relief valve 27 to automatically discharge vapor from the evaporator 3 when the preheater 14: and feed heater 8 are unable to when automatically operated provision must be made for manual control of valve 7 in order to shut down the evaporator when desired.

In the actual installation of the system herein described it will be necessary to supply well known devices for indicating the pressures in boiler 1 and evaporator 3; the water levels in boiler 1, evaporator 3, feed tank 19 of Fig. 1 and open heater 8 of Fi 2; and for determining the density of salinity or some other property of the concentrated impure water or solution in evaporator 3. These well known devices have not, been shown in order to drawings. I w

The operation of my system for operating water is as follows:

The whole. plant being in operation with simplify the mamas the exception of evaporator 3, its preheater 14; and its feed pump d, valves 7, 15, 22, 245, 25, 26 and 27, will be closed. Exhaust steam from boiler feed pump 5 and other auxiliaries about the plant will be flowing through exhaust main 6 to feed heater 10 through valve 11 which should be open, probably to feed heater 8 through valve 9, and possibly to a condenser not shown through relief valve 12all depending upon the quantity of exhaust steam available.

Now assume the level in feed tank 19 of Fig. 1 or feed heater 8 of Fig. 2 to become low, and the only source of make-up feed to be the fresh water produced by evaporator 3. The evaporator feed pump d is first started and evaporator 3 filled to the proper working level with impure water from source 13. Valve 7 is now open (if sufficient exhaust steam be available) and this impure water heated until vapor is given off at the proper pressure when valve 22 is opened, manually or automatically, depending upon the type installed. The proper water level is maintained in evaporator 3 during normal operation by control ling the speed of feed pump 4. Apart of the vapor produced in evaporator 3 will be condensed in preheater 1%, thus raising the temperature oi the impure water fed to the evaporator, and the remainder of the vapor will be condensed in feed heater 8 provided there is a suflicient flow of boiler feed water to beheated and the heater is properly designed. If the flow of feed water through feed heater 8 should slacken for any reason, the rate of condensation of the vapor therein will he reduced and the vapor pressure in feed heater 8, preheater 14: and evaporator 33 will rise, thus reducing the temperature difference in the evaporator and consequently the rate of evaporation, assuming the exhaust steam pressure to remain constant. This will continue until either the rate of evaporation is reduced to equal the rate of condensation, or until the relief valve 27 in Fig. 1 or 12 in Fig. 2 opens to discharge the excess vapor.

During normal operation there will be produced nearly one pound of vapor to be condensed in preheater 1 1 and feed heater 8 for every pound of exhaust steam condensed in evaporator 8. The quantity of exhaust steam condensed and the quantity of fresh water produced corresponding to a given quantity of feed water will also depend upon the liberality of design of evaporator 3, preheater 14, and feed heater 8, and likenot suflicient to produce the quantity of make-up feed water'required. Then valves 25 and 24 must be opened to augment the exhaust steam from the auxiliaries with live steam from main 2. With an ejector 23 installed and valve 26 opened, there is obtained not only nearly one pound of fresh Water from preheater 14 and feed heater 8 from each pound of live steam supplied, but also the additional fresh water condensed in the steam space of evaporator 3 from the vapor entrained in each pound of live steam passing through the ejector.

Feed heater 10 operating with exhaust steam of a higher pressure than that of the vapor supplied feed heater 8, will give a higher temperature of the boiler feed water than would be possible with feed heater 8 only.

The concentration of the impure water in evaporator 3 should be observed from time to time sothat it may be blown down through valve 15 when the limiting concentration is reached, and the evaporator again filled to the proper working level with raw Water.

It should be noted that the system proposed may be operated with exhaust steam alone, with live steam only (supplied through ejector 23), or with exhaust steam and live steam containing entrained vapor commingled in the evaporator steam space.

The use of exhaust steam in an evaporator to produce fresh water is not new, being now practised in the U. S. Navy. It is believedto be novel, however, to condense all or part of the vapor produced by an evaporator using exhaust steam in a boiler feed water heater, whereby the heat in the exhaust steam is returned to the system with the exception of the heat radiated and that discharged in the concentrated impure water blown out from the evaporator. The use of two feed water heaters as described herein is also considered new, a higher temperature of the feed water and greater heat conservation resulting than if one feed heater only were employed. Also, the combination with such an exhaust steam evaporative system of an ejector to produce a regenerative working of the evaporator when live steam must supplement the exhaust steam, completes a system for evaporating water or" greater economy than were the ejector omitted. Finally, there are employed well known automatic valves in ways that are considered novel.

Having thus described my invention, I claim and desire to secure by Letters Patent, the following:

In a system for evaporating water, a boiler, two feed heaters in series, an evaporator, apparatus operated by steam from said boiler, an ejector for withdrawing vapor from said evaporator, means for heating the solution contained in said evaporator by the commingled steam and compressed vapor from the said ejector, means for heating the boiler feed water in the first of the said feed heaters by vapor from the said evaporator, and means for further heating the boiler feed water in the second of the said feed heaters by exhaust steam from the said apparatus.

WILLIAM L. DE BAUFRE. Witnesses:

A. J. G. BABEL, G. A. LAUX.

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