by 4 & Oct. 10, 1972 E. R. WEAVER 3,697,383 FEEDWATER HEATER AND STRAINER ARRANGEMENT FOR EARLE R. WEAVER,

Transcription

1 Oct. 10, 1972 E. R. WEAVER 3,697,383 FEEDWATER HEATER AND STRAINER ARRANGEMENT FOR MULTIPLE-EFFECT THIN FILM DESALINATION PLANT Filed Dec. 14, Sheets-Sheet l 6-CONDENSATE OOP INVENTOR: EARLE R. WEAVER, by 4 & HS AT TORNEY.

2 Oct. 10, 1972 E. R. WEAVER 3,697,383 FEEDWATER HEATER AND STRAINER ARRANGEMENT FOR MULTIPLE-EFFECT THIN FILM DESALINATION PLANT Filed Dec. 14, l970 2 Sheets-Sheet 2 LQUID al 22 s Y N Others s. saws are systewart Orsaxena vote as we 4. 6 w Y7 Z7 Z2 s al Navy BLOWDOWN VALVE NyNTOR: EARLE R. WEAVER BY 4. ( C2-/64 HIS AT TORNEY.

3 United States Patent Office 3,697,383 Patented Oct. 10, ,697,383 FEEDWATER HEATER AND STRAINER AR RANGEMENT FOR MULTIPLE-EFFECT THEN FILM DESALINATION PLANT Earle R. Weaver, Topsfield, Mass., assignor to General Electric Company Filed Dec. 14, 1970, Ser. No. 97,729 Int, C. B01d 1/26, 3/00, 3/02, 3/08, 3/28, 21/24 U.S. C Claims ABSTRACT OF THE DISCLOSURE A vertical double fluted tube evaporator for Water de salination has multiple closely-coupled effects with indi vidual feedwater heaters in each effect. Feedwater mani folds in each effect supply feedwater to double fluted tubes through individual porcelain spray nozzles providing thin films on the tubes. The feedwater heaters are fed in series through each effect, while parallel branch lines supply the manifolds via in-line strainers with provisions for blow-down during normal operation if strainer blockage OCCS, If it is desired to include strainers or filters in the feed water line to prevent plugging of the feed nozzles, it is very desirable to having some means to clean the strainers in the event that they become clogged or plugged. It would further be desirable to have a means for cleaning the strainers without the necessity for shutting down the desalination plant. Accordingly, one object of the present invention is to provide an improved feedwater heating and strainer ar rangement for a multiple effect thin film distillation plant with improved means for heating and cleaning the feed Water. Another object of the invention is to provide a strainer arrangement in such a plant which allows blow-down or cleaning of separate effects during operation of the plant. DRAWING The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of practice, together with further objects and advantages thereof, may best be understood by reference to the following de Scription taken in connection with the accompanying draw BACKGROUND OF THE INVENTION 2 ing, in which: This invention relates generally to multiple-effect thin FIG. 1 is an end view, showing one effect partly in film desalination plants and more particularly to a feed Section, of a vertical tube thin film desalination plant, water heating and strainer arrangement for such plants. FIG. 2 is a horizontal elevation, partly in section, of the desalination plant, Multiple-effect thin film desalination or water distilla 30 tion plants are known, wherein each effect utilizes vertical FIG. 3 is a top view of the desalination plant, tubes adapted to evaporate feedwater on one surface of FIG. 4 is an enlarged detail view of the feedwater the tubes and to condense steam on the other surface of manifold, spray nozzle and fluted tube, and FIG. is an enlarged horizontal view in cross section the tubes, both in thin films. One such apparatus wherein the several stages or effects are arranged in vertical fashion of the preferred in-line strainer used in practicing the 3 invention. may be seen by reference to U.S. Pat. 3,481,83 issued to T. C. Carnavos on Dec. 2, Enhanced heat exchange SUMMARY OF THE INVENTION characteristics may be further obtained by use of double Briefly stated, the invention is practiced by providing a fluted heat exchange surfaces as disclosed in U.S. Pat. plurality of feedwater heater loops disposed in the condens 3,291,704 issued to G. E. Diedrich and C. W. Lotz, while 40 distillation apparatus arrangements incorporating such ing chambers of successive vertical tube evaporator effects and connected in series flow relationship. A plurality of surfaces are disclosed in U.S. Pat. 3,244,601 to G. E. Died feedwater Supply lines are connected between successive rich. All of the foregoing patents are assigned to the present assignee and are incorporated by reference herein, feedwater heaters and lead to the respective feedwater The above Carnavos patent disclosed supplying raw manifolds via in-line strainers equipped with blow-down 4 valves. feedwater serially through feedwater heaters in each suc DESCRIPTION OF THE PREFERRED ceeding effect, while branch lines from the feedwater heat EMBODIMENT ing line supplied the manifolds for each effect in parallel fashion, Referring to FIG. 1 of the drawing, an end view of The Carnavos patent offered some improvements over 0 the desalination plant is shown, partially in section, so the serial-flow prior art arrangements which were de as to indicate details typical of one effect or stage of a ficient in that the foreign matter in the feedwater was multiple effect plant. The various effects are longitudinal cumulative as it was pumped serially from one effect to ly spaced along a cylindrical pressure vessel 1 which is the next. Typical of the prior art are multiple-effect divided into a condensing chamber 2 in the upper half distillation plants, in which each effect is a vertical cylinder and a separation chamber 3 in the lower half. Steam con separately mounted and piped with a complex series of denses on the outer fluted surface of vertical tubes 4 and piping and pumps. Usually, the brine emerging from the is conducted by means such as inclined plate to the side Sump of each effect is pumped as feedwater to the succeed where it is removed through condensate removal pipes 6. ing effect. This results in pluggage of feed nozzles in suc Feedwater is heated in the pipes of a two pass feed ceeding effects because of scale, rust flakes, sediment and 60 water heater 7 and a controlled flow of feedwater is sup plied through a branch line 8 and through an in-line so forth. strainer 9 to the top of a feedwater manifold 10. Feed

4 3 water in the manifold is supplied through individual spray nozzles 11 (see also FIG. 4) in a thin film along the inner fluted surface of tubes 4 where it evaporates and the re sulting steam passes into the lower separation chamber 3. Unevaporated brine falls into the bottom of the pres sure vesssel 1 and is passed to the succeeding effect by brine loops 12. Referring now... to FIG. 2 of the drawing, a number of successively higher temperature effects or stages are indicated by reference numerals 14, 1, 16 and 17. It will be understood that any number of such effects may be employed which are economically practicable and that the stages are substantially identical in internal construction with the possible exception of sizes and proportions which are adjusted as necessary for varying flow rates. Referring to the internal details of effects 1 which is shown in cross section, it will be seen that the effects are thermally closely coupled to improved efficiency and reduce costs. This is done by means of simple vertical partition walls 18 separating the effects. Openings. 18a. permit the passage of vapor from each higher pressure effect to a lower pressure effect, from left to right. The brine loops 12 similarly conduct unevaporated brine to ward the right around partition wall 18 while providing a pressure seal. Caps 12a deflect liquid downward and improve the efficiency of flashing steam. A downwardly extending baffle plate 19 is spaced from divider wall 18 to form a passage leading toward open ing 18A. A moisture separator element, in the passage removes any liquid from the steam as it passes into the next lower pressure effect. Referring now to FIG. 3 of the drawing, the top view shows the feedwater heater and strainer arrangement for Supplying the feedwater manifolds 10 of successive ef fects Feedwater enters from the right through inlet pipe 21, having been previously treated and deaerated in a manner which will be known to those skilled in the art of desalination plants. Pipe 21 is connected to the inlet of a two-pass feedwater heater 22 located in effect. 14. A pipe 23 connects the outlet offeedwater heater 22 to the inlet of feedwater heater 24. In like manner, a pipe 2 leads to the inlet of feeder 26 in effect 16 and a pipe 27 leads from the outlet of heater 26 to heater 28 in effect 17, etc. Thus the feedwater heaters 22, 24, 26, 28 are connected in series flow relationship. In order to supply feedwater at successively higher temperatures to the feedwater manifolds 10, branch lines 30, 31, 32 are T'd to respective pipes 23, 2, 27 and lead to in-line strainers 33, 34, 3 respectively. Orifice plates (see also FIG. ) are placed in the flange connections designated 36 to indicate the flow rate, while valves 37 are used to adjust the flow rate. Reference to FIG. 4 shows the details of supplying feedwater to the individual vertical fluted tubes from feedwater manifold 10. One tube 4 is shown with its end engaged in a tube sheet 38, the remainder of such tubes being identical. Tube sheet 38 and an upward curved wall 39 are sealingly engaged to provide a feedwater chamber 40. Disposed in the upper end of each tube 4 is a porcelain spray nozzle of the tangential swirl type. The spray noz zles are submerged in liquid. Tangentially skewed inlet holes such as 11a meter entering feedwater and provide a swirl. The liquid is thrown outward on the depending nozzle lip 11b to be distributed on the inner wall of tube 4 in a thin film. Tube 4 is provided with inside and outside longitudinal protuberances 4a functioning in the manner described in the aforementioned Diedrich and Lotz, Pat. 3,291,704 and Diedrich Pat. 3,244,601. Reference now to FIG. of the drawing shows the arrangement of the in-line strainer used in practicing the present invention. The strainer which is an enlarged de tailed view of the strainer 9 shown in FIG. 1 is supplied with feedwater from a branch line 8 through a bolted flange connection having an orifice plate 38 interposed therein. The body of strainer 9 comprises a cylindrical 3,697,383 O pipe section 39 forming two coaxial legs 39a and 39B with a T having a base connection 40 leading to the feed water manifold 10. An end closure plate 41 closes off the end of the strainer and is provided with a blow-down valve 42. The blow-down valve is purposely located at the bottom edge of the strainer where the major portion of sediment collects. A cylindrical perforated strainer ele ment 43 is coaxially spaced within pipe 39 by means of a spacer ring 43a clamped between a flange 44 and the closure plate 41 with suitable gasket. Coaxial alignment of strainer element 43 is maintained at the other end by means of a spacer washer 4 attached to the element. The element is longitudinally compressed against a sealing ring 46 attached to the inside of the pipe 39 to maintain a tight seal. OPERATION From an overall thermodynamic cycle standpoint, the operation of the multiple-effect desalination plant shown is substantially the same as that shown in the aforemen tioned Carnavos Pat. 3,481,83. However there are sev eral important differences material to the present inven tion. First, the illustrated embodiment concerns a hor izontal arrangement of effects, rather than a vertical ar rangement of effects, wherein gravity-head is not a factor in assisting or impeding liquid flows. Both brine, and the steam generated in each effect inside the fluted tubes are successively passed toward the right or lower temperature effects, the steam through the divider wall openings and the brine through the pressure-sealing brine loops 12. Sec ondly, with respect to the feedwater heating and strainer arrangement of the present invention, feedwater enters at pipe 21 and is successively heated in feedwater heaters 22, 24, 26, 28 as it passes to the left in series-flow rela tionship between heaters. At each effect, a metered flow of feedwater is passed through branch lines 30, 31, 32 to strainers 33,34, 3. As will be seen in the enlarged view of FIG. for a typical strainer, the feedwater flow is metered by orifice 38 and flows into the interior of the perforated cylindrical element 43 where any impurities such as sludge, rust par ticles, etc. are retained. The filtered feedwater flows through T connection 40 into the top of feedwater mani fold 10, and since it is clean, there is no tendency to plug the feed nozzles 11. One of the primary advantages of the invention lies in the in-line arrangement of the strainer leading to the blow down valve 42. It will be seen that by opening the valve 42, a straight-through passage is afforded so that the cylin drical element 43 can be cleared of any trapped foreign matter through the valve. As will be seen later in the de scription, this operation can be carried out without inter ference to the operation of the desalination plant. Reference to FIG. 4 shows that the feedwater entering header 10 flows through the small ports 11a of the nozzles 11 and, since foreign matter has been moved by strainer element 43, there is less likelihood of the small nozzle ports 11a becoming plugged, and hence affecting operation of the plant. Since the feedwater branch lines are connected in paral lel to the feedwater heater line, it will be appreciated that any one of the branch lines may be blown down through valve 42 without materially affecting the operation of the plant. This offers a substantial advantage in desalination plants where the effects of corrosion products, rust, sedi ment and other deleterious substances are well known in the art. While there has been described herein what is considred to be the preferred embodiment of the invention, it is of course understood that various other modifications may be made therein, and it is intended to cover in the ap pended claims all such modifications as fall within the true spirit and scope of the invention.

5 What is claimed is: 1. In a multiple-effect thin film desalination plant, each effect having a plurality of vertical tubes supplied from a feedwater manifold through nozzle means with ports subject to blockage by foreign matter in the feedwater, and wherein the feedwater manifolds are separately Sup plied from branch conduits in parallel flow relationship from a feedwater heater line, the improvement compris 1ng: an in-line strainer connected between the branch con duit and the feedwater manifold for each of said effects, said strainer also having a blow-down valve on the upstream side of the strainer and adapted for discharging foreign matter therefrom without Sub stantially shutting off the flow of feedwater to said manifold. 2. In a multiple-effect thin film desalination plant, each effect having a plurality of vertical tubes supplied from a feedwater manifold through nozzle means with ports subject to blockage by foreign matter in the feedwater, the improvement comprising: a plurality of feedwater heaters, each one disposed in adjacent proximity to the vertical tubes of the same effects, main conduit means connecting said heaters together in series flow relationship, branch conduit means connected to said main conduit means between said feedwater heaters for extracting heated feedwater for each effect in parallel flow rela tionship, strainer means connected between said branch conduit means and the feedwater manifold for each effect, said strainer means being adapted on its upstream side for discharging foreign matter therefrom without substantially shutting off the flow of feedwater to said manifold. 3. The combination according to claim 2, wherein said strainer means comprises: a T-shaped body member having a pair of coaxial legs and a base leg and having the base of the T con nected to said feedwater manifold, a perforated strainer element open at both ends dis posed within and spaced from the walls of said co axial legs, 8,697,383 O a blow-down valve connected at one end of one co axial leg of said T-section communicating with the inside of said strainer element, and means connecting the other coaxial leg of said T-sec tion to said branch conduit. 4. The combination according to claim 3, wherein said connecting means includes a flow-metering orifice disposed therein to meter the rate of flow to said feedwater mani fold.. The combination according to claim 2, wherein said effects are horizontally disposed inside a longitudinal pressure vessel, said effects being closely coupled and sep arated only by partition walls. 6. The combination according to claim, wherein vapor flows successively through said effects through open ings in said partition walls, over the exterior of said ver tical tubes and said feedwater heater of each immediately downstream effect with respect to vapor flow. 7. The combination according to claim, wherein un evaporated feed water from said vertical tubes flows suc cessively through said effects in vapor flow direction through brine loops beneath said partition walls forming pressure seals between effects. References Cited UNITED STATES PATENTS 1,843,242 2/1932 Rafton X 2,606,663 8/192 Blackman et al X 2,697,23 12/194 Bloksma X 3,099,607 7/1963 Lustenader et al ,32,12 10/1970 Cartinhour ,370,63 2/1968 Kumm A FOREIGN PATENTS 1,132,096 6/1962 Germany A NORMANYUDKOFF, Primary Examiner J. SOFER, Assistant Examiner U.S. C. X.R , Dig. 8; 2-178, 236;