US1440723A - Evaporator - Google Patents

Description

Jan. 2, 1923.

C. w. DYSON ET AL.

EVAPORATOR.

HLEDMAR.26,1920.

2 SHEETS-SHEET l.

w X R 352%? Girona Jan. 2, 1923.

C. W. DYSON ET AL.

EVAPORATOR.

FILED MAR.26, 1920.

2 SHEETS-SHEET 2.

Patented Jan. 2, 1923.

l UNITED I STATE-'S l 1,140,723 PATENT OFFICE.

CHARLES W. DYSON, OF THE UNITED -STATES NAVY, .AND MILTON C. STUART, OF ANNAPOLIS, MARYLAND, ASSIGNORS TO ANDALE ENGINEERING COMPANY, 0F PHILADELPHIA, PENNSYLVANIA, A CORPORATION 0F PENNSYLVANIA nvaronnron.

Application mea March 26, 1920. serial no. 369,114.

rr ar admiral United States Navy, and MIL- TON C. STUART, both citizens of the United States, respectively residing at VVashing'- ton, District of Columbia, and Annapolis, county of Anne Arundel, State of Maryland, have invented certain new and useful Improvements in Evaporators; and we' do hereby declare the'following to be a full, clear, and exact description of the invention, such as will enable others skilledin the art to which it appertains to make and use the same. i

This invention relates to evaporators, especially adapted for use -aboard ship, and has for its object to provide a process which will be easily carried out and more eiicient in action than those heretofore proposed. lith these and other objects'in view the invent-ion consists in the novel steps and combinations of steps constituting the` process as will be more fully hereinafter disclosed and particularly pointed out in the claims.

Referring to the accompanyingo drawings forming a part of this specification, in*l which like numerals designate liket parts in all the views Figure l is a diagrammatic elevational view partly in section of a` first effect evaporator'joined'to a second effect evaporator made in accordance with thisv invention;

Figure 2 is asectional planview of the second effect evaporator shown in Figure l;

Figure 3 is a side elevational view partly in section of the second effect evaporator; shown in Figure 2;

Figure 4 is a detail sectional view illustrating one of the coiled tubes in position;

Figure 5 is a plan view of the parts shown in Figure 4;

Figure 6`is an enlarged 'sectional detail view of one of the drain plugs;

Figure 7 is asectional v'iew of a micrometer valv'e employed in this invention; and- Figure 8' is a sectional view taken on the l-ine 8-8 of Figure 7, looking inthe direction of the arrows. l

Referring particularly to Figure `1, the numeral 1 indicates the outer shell of a first effect evaporator, 2 a high pressure steam pipe, leading directly from the boilers, not shown, 3 a micrometer valve illustrated inV detail in Figures 7 and 8, 4 a drain pipe provided with a micrometer valve 5, and 6, f7, 8, h 9, 10, 11 and 12 indicate partitions between the outer wall 13 and lthe innerfwall 14 of the door like members 15 with which the first'efl'ect evaporator 1, as

well as the second effect evaporator- 54 are provided. One of vthese said door like members 15 is conveniently secured to the shell 54 `as at 16, and the other is secured in a similar manner. not shown, to the first effect shell 1. Y f

, On the interior of each of the shells 1 and 54 of the levaporators, there are provided a plurality of steam conveying coiled tubes. These tubes may be as numerous as desired, and are preferably arranged` in horizontal rows. Three of the top rowsof these tubes are numbered 17, 18 and 19, and are best'shownr` in Figures 2 and 3. The open ends of each of the tubes communicate with channels that are formed in the doors 15 by the passages numbered 6 to 12. The top channels in the evaporators land 54 are numbered 20, the next lower channelsl and, agiven coil or tube has its upper end 23 openlng into an upper channel such as 20 above a partition such` asf6, and the lower en d 24 of said tube opens `into a lower channel such as 21 below said partition 6. But, as above stated, itis preferred to providefor each of the channels' to 12 a plurality of coilsas best indicated Ain Figure 2, and in such fcase, all their upper open ends 23 will be joined in parallel with an upper channel` while all their lower l'ends willi be joinedin parallel with a lower channe -On the other hand, said channels or steam `coil elements 6 to 12 havev no communication with each other except through drain orifices andsaid coiled tubes.

It thereforefollows that if we count, fromV the top row down, the said coils or tubes are joined in series, as will be evident when we note that the steam entering the endsv 23 of the coil 17 f, r example, in the Vcha/nucl 20, will be discharged from the ends 24 of said coils 17, into the next lower channel 21, whence the said. steam immediately enters the upperends of the coils 18, and discharges from the lower ends of said coils `into the succeeding lower channel 22 and so on down to the last channel in the first.

' doors 15 by the tie rods 28 as illustrated.

So firmly do said braces and tie rods hold the coils that the rear portions of the latter are not moved to any substantial extent upon changes in temperature, and therefore, movements due to expansions and contraction are taken up by the convolution of the coils, as will presently appear. As above stated, the steam passes through the coils in each channel in multiple, and passes through said coils, when considered in vertical rows in series, but as the steam flows through the successive coils, part of it is condensed in each coil, due to the loss of heat tothe water being evaporated, in thev spaces 29 of each evaporator 1 and 54. In order to drain off this condensed steam there is provided in each channel 6 to 12 the drain plug 30, as best shown in Figures 1 and 6. Each plug is provided with a hole 31, so small that no appreciable amount of live steam can escape therethrough, while at the same time the condensed steam or water can be vforced through said hole by the pressure of the live steam in the coils; said plugs 30 are preferably located in depressions 32 provided in the channels', so that a'water seal33 formed by said condensed steam will usually overlie each hole 31. A plug 34 for cleaning and inspection purposes may be provided over each plug 30 as illustrated.

1t will be clear that the condensed steam through each plug 30 will drain into the channel next below, until it reaches the drain pipe 4. These depressions 32 and plugs 30 constitute an important feature in raising the efliciency of the apparatus. and in keeping it at a high standard over compara tively long periods, for they coact to keep the coils drained of water and therefore to cause only dry steam to fill said coils and to contact with the Walls thereof. Not only may high pressure steam be utilized in the first effect evaporator 1,'-through pipe 2, but

exhaust steam from any convenient sourcel or sources may be led in through pipe 37 provided with the micrometer valve 38 when y movement, vor change, in curvature of said In either case, the steam supply to the evap-j orator may be so regulated by adjusting the` it is not desired to use high pressure steam.

micrometer valves 3 and 5, (as will be presentl explained), that it is substantially all con ensed in the coils, an'd therefore, only condensed steam passes out the drainpipe 4, or if any live steam should pass into the pipe 4, the micrometer valve 5 may beso adjusted as to prevent it, as will likewise be explained below.

The construction of the micrometer valves 3, and 38, as Well as others which will be mentioned hereinafter, will beA clear from Figures 7 and 8, .wherein 39 represents a steam passage to lie-controlled, 40l a disk movable Aacross said passage, and provided with the expanding curved crescent shaped slot or opening 41 adapted to adjiistably throttle said passage. Said opening 41 is curved in cross section onv the left, as seen in Figure 7, and is flat or provided with the rather sharp edges on the right as seen in said figure. rlhe purpose of this construction is to increase the velocity of the steam passing through the coils, thus insuring a bettercontact with the walls ofthe latter, and a more eflicient heat exchange. 42 represents a stem on which said disk is mounted, 43 a graduated disk, 44 a pointer, coacting with the graduations on the disk 43, and 45 means for moving said pointer over said disk 43. It is evident that by properly adjusting the pointer 44, any desired proportion of the area of the passage 39 can be cut off and therefore, the steam may be throttled with certainty to any dcsired degree. The peculiar curvature of `thil tubes or coils, such as 17, 18, and 19 iii both the first and second "effect evaporators constitutes an important feature of this invention in that said curvature causes a more eflicient scaling action than ldoes other forms of curvature and thus maintains the coils more free from scale. This latter fact aids ,in maintaining a high efficiency of the heat exchange over relatively long periods of time. That is to say, said coils being 1immersed i'n sea Water the well known scale,VA

further multiplied by securing the coils firmly against bodily movement by means of I the ,braces and rods 27 and 28, as above explained. In other words, owing to the peculiar curvature of these said coils they can be made very milch longer than' heretofore, and a relatively slight change in tein-` perature willV produce a rrelatively"large Y The vapor ,from the salt Water iii the first effect evaporater linay pass off through the pipe 45, having the micrometer valve 46, to

isc

the distiller, not`shown. Or, all, or a portion of said vapor may pass through the From the separator 50, the pipe 51 conveys effect evaporator. and therefore duplicatef` evaporator whence their condensate may bev said distilled vapor through the micrometer' valve 52, to the chamber or channel 20 of -the said .second effect evaporator 54. Said second effector lower pressure evaporator 54 is constructed substantially like the 'first parts in each evaporator are designated, by similar numerals. n.

The operation of said seco'nd effect evaporator is similar to said firsteffect apparatus, the main differences being the provision of the partition 53 which separates the vapor delivered through the pipe 51 from that rdelivered through pipe 55, as will presently appear. The' vapors from the sea Water contained in the space 29 of said second effect evaporator may be carried off by any suitable means similar to the pipe 45',

in the first effect evaporator, but is not illus-- trated.

' It is evident however, that vapors coming through the pipe 51 into the second effect evaporator may be so controlled by the micrometer valve 52 that they will all be substantiallyA condensed by the time they reach the channel 57, in said second effect drained .0E through the micrometer valve 58 and pipe 59 to the distillers. It thus results that whether the evaporated sea water is led directly to the distillers through the pipe 45,

or is. further carried through the second effect evaporator to rob it of its heat, it is not contaminated by condensed steam, nor is there any lossof said evaporated water in the procedure. y

The condensate from the first effect apparatus 1 is carried by the pipe 4` to` the lowest coils 60 of the second effect 54, which coils may be joined in series as shown, and said condensate is then drained off through the micrometer valveV 61 and pipe 62, to the fresh water tanks.

66 represents a micrometer valve and 63- a drain to a trap, not shown, but which may be maintained at atmospheric pressure. 64

' indicates a micrometer valve and 65 a pipe vconveying high pressure steam to the pipe '55. The operation of this evaporlat-ing system will be clear from the foregoing but. may be briefly summarized as follows Sea water being, placed inthe first effect evaporator 1, and in the low pressure evaporator 54, high pressure Steam, may be c onveyed through the pipe 2 or auxiliary /ex-.

haust steam from donkey engines, or other auxiliary power plants may be conveyed into said first eect evaporator through pipe 37. In either case, the micrometer valves 3 or 38 may be so adjusted that all the steam entering said evaporator 1 and passing through its coils 1T, 18, 19, etc., will be condensed by the time it reaches the drain pipe 4; and further, the micrometer valve 5, in said pipe 4, may be so adjusted that any heat it may possess. F romthe coils 60 saidv condensate is drained off through the valve 61, and pipe'62, to the fresh water tanks. At no time is any fresh water condensate lost, nor is it ever contaminated with salt water vapor nor is a trap necessary for its recovery. In the meantime, it is evident that a maximum of heat is extracted from the originalv steam. In order to still further increase vthe efficiency of the system. all, or a portion of 'the vapor from thesalt water in the firsteffect evaporator may be conducted through the pipe 48, the steam separator 50, the micrometer valve 52, and'coils 17, 18, 19, etc., of the second effect evaporator to and through the valve 58. This said vapor thus evaporates an additional quantity of salt water in the lowv pressureapparatus 54, and at the same time all the salt water condensate is saved. as above pointed out., by passing it through the pipe 59 to the distillers.

In addition to 'this salt water vapor auxiliary exhaust steam may be simultaneously. or independently used in said evaporator 54. by passing said auxiliary steam through the coils, 17, 18, 19 etc., located on the right hand side of the partition 53, as seen in Figurey /1, and locatedabove said partition 53, as seen in .Figure 2. Said auxiliary steam is\conve'niently introduced through pipe 55 and is so throttled by a micrometer, valve 56 as to cause it all to be condensed' by the time it reaches valve 66. If, however, any portion of it remains uncondensed when valve 66 is reached. said valve may be so adjusted as to throttle off the live steam,

Owing to its possible contamination with oil the condensate passing through wthe pipe 63 is, not mixed wit-h that passing through the V pipe 6,2. Should it be` desired to employ high pressureA steam in the second effect. evaporator such may be introduced through the pipe 65, and valve 64, and in such case said'second effect evaporator will. operate in so far asits coils on the right hand side of the partition 53 are concerned, in the jak same manner as does the first. effect evaporator. y

On the other hand, if it is desired to employ live steam simultaneously with the condensed vapor through pipe 51, it can also be employed that way. In other words, it will be observed that the second effect evaporator may be run independently, precisely as is the first effect evaporator7 or it may be run simultaneously with the employment of vapor from the first effect evaporator through pipe 5l.

It will now be clear that with the foregoing evaporator system', the folowing advantages contributing to its highefficiency are readily attained.

1. (lne is enabled to provide a relatively very long path of travel for the steam through the coils;

2. The vmicrometer valves afford a ready means for controlling the operation as well as the capacity of the system. In fact, the capacity' of the system may be virtually controlled by-the'valves 3 and 38.- That is to say, it is evident that as the steam passes the valve 3, which really constitutes an expansion nozzle,'it expandsinto the coil elements with a relatively low pressure and a relatively high velocit of flow. In other words, the well known aw of Napier, governs the flow of steam, which shows that a constant Weight of steam will pass per unit of time through this said nozzlevalve 3 into said coil elements until the pressure on the low pressure /side of the said valve 3 equals about 58% of the pressure ontthe high pressure side of said valve. It further results from this that as the deposits, or scale, accumulate on. the evaporator coils the rate of transmission of heat from said coils fallsofl", but the weight of steam flowing into said coil elements remains constant under said law of Napier, so the pressure builds up in theL convolutions, and the temperature therein increases. I

It therefore results that the transmission of heat through the-walls of the coils to the liquid remains practically constant. In other words, it is clear thatby this construction one is enabled to obtain a very high efficiency of operation until a certainl thickness of scale is present, after which the efficiencyv will rapidly fall 0H. But when l this thickness of scale is reached. steam will appear at the end of the final convolution before the valve 5 is reached, and the temperature of the combined drainage from the convolutions will also rapidly rise. These phenomena will indicate to the operator that the scale on the convolutions should be removed.

3. The drain plugs 30 constitute a means for draining off the condensateV from each coil as it is formedl so that only dry steam enters the coils. lVhen desired automatic Afree from scale.

charge of condensate from veach group ofl coils, so that only condensed steam may escape from the colls, thus insuring a highly efficient heat exchange.

5. The pipe 4 constitutes a mea-ns for further abstracting heat from the condensate from the high pressure steam, and thus still y further increases lthe eHiciency of the apparatus;

GI'The pipe 55 and partition 53 constitute a means for` utilizing low pressure eX- haust steam in vthe same apparatus thatI is utilizing low pressure vapor from said salt water;

7.v .The pipe 65 and partition 53 constitute a means of using high pressure steam in the same apparatus that is using low pressure vapor from salt water; I

8. Owing to the relatively long coiled tubes, the high velocity of the steam, and to the micrometer valves insuring a complete condensation of the steam, the use of traps or drain pots may be done away with.

9. Owing to the continuously curved pipe in the coils, and the peculiar bracing and holding means preventing the bodilyniovement of said coils, the contractions and expanslons lncident to the changes 1n tem-v perature greatly aid in keeping the coils ln fact the efficiency of this apparatus has been demonstrated in practice to be very high and to be capable of being maintained for a milch longer period than with other apparatus which have been heretofore proposed. That is to say, we have shown in practicethat on opening' a micrometer valve to give a desired pressure in the coils, and upon starting to evaporate with clean coils, a certain output of condensate free from steam will be realized through a long period. coils become more orlless covered with scale the pressure in the coils automatically increases so the rate of evaporation in the shell still holds, through'a periodof time or until a certain degree of scaling up.of the coils occurs.I

Then the efficiency begins to fall and this gives an indication as to the time when a scaling of-the coils should be had.- 'In an As the actua-l test using 30 pounds of steam and" 50 feet in a coil of inch pipe we found that every particle of steam was lcondensed at the outlet4 from the pipe. In practice we prefer that each vertical element of the sections be made 65 feet in length and of .1` inch pipe, thus insuring a complete condensation of the -steam by the time it leaves the evaporator through the drain. Such a maintenance of a high efficiency vthrough a long range of time has never heretofore been attained in similar apparatus in so far as we are aware.

Owing to this high efficiency' over rela'- tively long periods of time. the capacity of a given apparatus is greatly increased so that for a given output it may be made smaller aboard ship and space thus saved. Then too. said high efficiency serving to condense all the steam the use of steam traps. steam pots. etc.. heretofore found necessary to choke back the drainage from the coils may be done away with.

It will be observed that the drain plugs 30 are omitted from the lowest row of coils in each evaporator. so that the lowest row ofV 1s concoils will conduct all the water that densed in the upper coils. i

Further. it

instead of in parallel as is illustrated in Figure l. i

This will expedite the further cooling of the condensate. In all cases. the doors 15. and their attached coils may be readily 'removed without disturbing the steam connec tions. Further. owing to the fact that the coils arel unusually long. and owing to their peculiar. curvature. the manufacturer is enabled to locate the ends of the coils in the plate 1l of each door farther apart than has been heretofore possible` .with the same capacity of apparatus` and this results 'in the important advantage that, when the end of the 011e coil is being expanded. it does notdistort or change the dimensions of the hole. for the end of another coil.

In other words. the holes in the wall 1l accurately tit the coils even after repairs which is not the case when the holes are placedv so near together that the expansion of a tube in one hole changes the dimensions of a neighboring hole.

Of course. although the coils have been shown as arranged in parallel. in each channel. yet they may be. if desirerharranged in series. or in any other connections fwhich will best suit the requirements for cooling the condensed steam to'a point where it may be discharged without the loss of vapor.

The graduations, not shown. onvthe disk 43 may be determined by a calibration made at various points with various portions of the slot() in the disk. for both water and steam. The micrometer valves in the steam pipes control the capacity of the evaporators while the said valves in the drain pipes control the pressure and temperature of the discharged condensates. -v y It will now be clear that the tube like elements 1T whether considered singly or in multiple, constitute a convolution. one endof which communicates with the chamber 20,

will be observed that the lowest row of coils may be arranged 1n series.

'while the other end communicates with the chamber 217 and that the tube like elements 18. 19. etc., constitute additional convolutions. the upper ends of which communicate with upper chambers. and the lower ends of which communicate with lower chambers.

Itwill further be clear that all of the tube like elements or convolutions are joined in series. so that they in the aggregate constitute a continuous coil, through which the steanrpasses. That is. the convolutions are joined in series b v the chambers, andthe.

`steam passes continuously through the same 'and through the chambers.

It is further evident that each convolution alternates with a chamber. and that each preceding upper .chamber is drained directly into a succeeding lower chamber.

It is further evident that through a proper manipulation of the valve mechanism shown in Figures T and 8, the steamv passing through the'convolutions and the chambers can be so controlled as to cause itl to be all substantially condensed when it leaves'the last chamber or theevaporating system.

It is obvious that those skilled in the 'art may vary the details of the construction as well as the arrangement of parts without departing from the spirit of the invention. and therefore` .we do not wish to be limited to the above disclosure except as may be required by the claims.

lVhat is claimed is 1. The process of evaporating a liquid which consists inimmersing in said liquid a plurality of convolutions located one above the other and each alternating with a chamber and joinedk in series; passing steam successively v'through said convolutions and chambers: draining any condensed steam from an upper chamber in succession through the lower chambers andinto the steam exit from the system; and so controlling the flow of steam through said convolutions and chambers as to cause it to be substantially all condensed as it leaves the system. substantially as described.

2. The process of evaporating a liquid which consists in immersing in said liquid a plurality of tubes comprising convolutions located one above the other and each alternating with a chamber and joined in series; f passing steam successively 'through said con` volutions and chambers; draining the condensate of the tubes of aconvolution into' its corresponding chamber'at a plurality of points; draining any condensed steam-from an upper chamber in succession through the lower chambers and into the steam exit from the system; and so controlling the flowof steam through said convolutions and chambers as tocause it to be, substantially all condensed as it -leaves the system, substantially as described. i f

3. The process of evaporating a. liquid which consists in immersing irf said liquid a plurality of convolutions, each alternating with a chamber2 joined in series and constituting a continuous coil; :passing steam th-roughf'said coil; draining any condensate from a convolution into its corresponding chamber; draining the condensate from each preceding chamber into'a succeeding cham* ber; and so controlling the passage of steam through the coil-and chambers as to cause it .to be substantially all condensed before it leaves said coil, substantially as described.

4. The process 'of evaporating a liquid which consists in immersing in said liquid a plurality of' tube like elements alternating with. chambers and j ointediin series; passing steam successively through' said elements and chambers; draining any condensatefrom a preceding chamber directly into a succeeding chamber; and so controlling the steam passing through said elements and chambers as to cause it to be substantially condensed as it leaves the last of said chambers, substan tially as described.

5. The process of maintaining the etticiency of evaporators having'a plurality. of serially joined tube like elements immersed in liquid to be evaporated and alternatingv with chambers, which consists in expanding a substantially constant weight'o steam in J said elements and chambers per unit of time;

draining the 'condensate of each element into its corresponding chamber; draining each preceding chamber into a succeeding chamber; and so controllin steam passing 4throug said .elements and chambers as to cause it to be substantially all condensed as it leaves the last chamber y'of the series,substantially as described.

6. The process of maintaining the eciency of evaporators havinga plurality of lserially joined tube like elements immersed in the liquid .to be evaporated and alternating with chambers, whichV consists inexpanding a substantially constant Weight of steam in said elements and chambers per unit of time; draining the condensate of .each element into its lcorresponding chamber at a plurality of pints;"drain'ing each pre-v ceding chamber into a succeeding chamber;

, and so controlling the total weight of steam passing through said elements and chambers as to densed as it leaves the last cham series, substantially as described.

the total weight of 'I cause it to be substantiallyeall con-N r of the 7. The process of evaporating liquids which consists in passing steam through coil elements immersed in said liquids and located one above the other; draining any water that may condense in an upper coil element into a lower coil element to maintain the steam ina .substantially dr ystate in said elements; and so throttling said steam as to cause it to be substantially completely con-y densed as it leaves said elements, substantially asdescribed.

8. The process of evaporating liquids which consists in continuously passing steam through coil elements immersed in said liquids and located one above theother; continuously draining anv water thatmay condense inan upper coil element into a lower coil element to'ma-intain the steam in a substantially dry state in all .of said elements; and so throttling said steam as to cause it to be substantially completely condensed as it' leaves said elements, substantially as described.

9. The` process of evaporating liquids which consists in passing steam through coil elements immersed in said liquids and located `one above the other; draining any l elements immersed in said liquids and located oneA above the other; draining any water that 'may condense in an upper coil element into alower coil element to maintainW the steam in a substantially dry state in said elements; so throttling said steam as to cause it to be substantially completely condensed as it leaves said elements; collecting the vaporsof` the evaporated liquids, and

heating therewith additional quantities of. liquids to bev evaporated, substantially as described. v

`lin testimony whereof` we atx our signatures. l i

u cnanrrsw. DYSON.

. Milli/TGN (C. STUART.,

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