US3501382A

US3501382A - Distillation-condenser with vertically disaligned tubes

Info

Publication number: US3501382A
Application number: US617642A
Authority: US
Inventors: Ralph C Roe
Original assignee: Saline Water Conversion Corp USA
Current assignee: Saline Water Conversion Corp USA
Priority date: 1967-02-21
Filing date: 1967-02-21
Publication date: 1970-03-17
Anticipated expiration: 1987-03-17
Also published as: GB1212252A; FR1556000A; NL6802385A; ES350692A1; IL29503A; DE1601116A1

Description

Marh 17, 1970 Y R. c. ROE 3,501,382

DISTILLATION-CONDENSER WITH VERTICALLY DISALIGNED TUBES Filed Feb. 21, 1967 6 Sheets-Sheet I IN VENTOR.

i 2. FHA/0H6. A705 BY R. c. ROE

' March 17, 1970 DISTILLATIQN-CONDENSER WITH VERTICALLY DISALIGNED TUBES Filed Feb. 21, 1967 6 Sheets-Sheet 3 C C C TC W1 N N R. C. ROE

March 17, 1970 DISTILLATION-CONDENSER WITH VERTICALLY DISALIGNED TUBES Filed Feb. 21, 1967 6 Sheets-Sheet 4 E R. 0 E M BY %%wm/ March 17, 1970 I R. c. ROE 3,501,382

DISTILLATION-CONDENSER WITH VERTICALLY DISALIGNED TUBES Filed Feb. 21, 1967 6 Sheets-Sheet 5 677' PA/E) March 17; 1970 R. c. ROE 3,501,382

DISTILLATIOEI-CONDENSER WITH VERTIGALLY DISALIGNED TUBES Filed Feb. 21, 19s? a Sheets-Sheet e L W W Fig.7.

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INVENTOR.

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United States Patent 3,501,382 DISTILLATION-CONDENSER WITH VERTICALLY DISALIGNED TUBES Ralph C. Roe, Tenatly, N.J., assignor, by mesne assignments, to Saline Water Conversion Corporation, Oradell, N.J., a corporation of New York Filed Feb. 21, 1967, Ser. No. 617,642 Int. Cl. B01d 3/28; F28b 9/10 US. Cl. 202185 6 Claims ABSTRACT OF THE DISCLOSURE Surface condensers with coolant tubes arranged in vertical disalignment and occupying only small percentage of condenser volume. Surface condensers integrated in multistage controlled flash evaporation system.

This invention relates to vapor condensation and more particularly it concerns novel surface condenser arrangements useful in recovering fresh water from steam.

Surface condensers are widely used in connection with steampower plants in order to reduce the volume and therefore the back pressure of exhausted steam so that a greater measure of power may be obtained from the system. Surface condensers have also been used in evaporation-condensation systems for the recovery of fresh water from saline or otherwise contaminated solutions.

The basic structural configuration of a surface condenser involves an enclosure or outer elongated covering which is closed at each end by means of a tube sheet. A plurality of condenser tubes extend along the interior of the enclosure and pass throguh the tube sheets at each end thereof. A cooling fluid is caused to pass through the condenser tubes and serves to maintain their surfaces at a low temperature. Steam or other vapor to be condensed is then admitted into the enclosure; and when it contacts the cooler surface of the condenser tubes it condenses thereon into liquid form and drips down into a fresh water collection trough located below the tubes.

In order to obtain maximum cooling it has been the practice to increase the condenser tube surface area to the greatest extent possible and to distribute this area throughout as much of the condenser interior as possible. Accordingly, conventional condenser construction involves the use of a very large number of condenser tubes nested within the interior of the condenser. Typical prior art condensers have anywhere from 22 to 45% of the area of their tube sheets occupied by the condensing tubes.

The large number of condensing tubes used in prior condensers accounts for a major portion of the expense of these devices. In addition, structural problems result from the use of a large number of condensing tubes, since very little of the tube sheet remains at each end of the condenser to provide support for these condenser tubes. As a result, special reinforcing structures have to be provided. This also contributes greatly to the cost of the condenser.

The present invention provides a surface condenser arrangement which is less complex and therefore is more economical to construct than prior condensers of comparable capacity. Moreover, such condenser does not suffer from the structural difiiculties encountered by prior art condenser arrangements.

According to one aspect of the present invention, there is provided a surface condenser unit within which a plurality of condenser tubes extend horizontally and are arranged such as to be in vertical disalignment so that no condenser tube extends directly above another tube. With this arrangement, the condensate which forms at any location along any of the tubes, drops directly down from that location and avoids all further contact with the tubes. As a result the condenser tubes are kept nearly completely free of condensate film and therefore are maintained at maximum heat transfer effectiveness.

The present invention, in another aspect, utilizes only about 2 to 5% of the tube sheet area to be occupied by the condenser tubes. While this involves a considerable reduction in area of the condensing surfaces, it has been found that such reduction is more than compensated for by the increased availability and increased heat transfer per square foot of tube surface of the condenser surfaces to the incoming vapors to be condensed. In the past, where steam had to be forced through a congested nest of condenser tubes, it was not possible to utilize each tube to its fullest capacity since the incoming steam would initially contact the forwardmost tubes and be condensed prior to contacting the rearward tubes. Further the rearward tubes were contacted by steam to be condensed only after it has been forced through the entire tube nest; and the rearward tubes would become effective to condense the steam only after the forward tubes were rendered less effective by the buildup thereon of a film of condensate. Furthermore, in the conventional condenser there is a substantial pressure drop through the tube bank which is eliminated in this arrangement.

The present invention involves the use of relatively few condenser tubes so that the incoming vapors to be condensed are not forced over one tube prior to contacting the tube upon which they are condensed, but instead they are caused to be condensed directly upon the first tube they contact.

The present invention in a still further aspect involves the integration of the novel condensing concepts mentioned above into a controlled flash evaporation system to provide a self-contained structure for the recovery of fresh water from salt water or other contaminated solutions. According to this aspect of the invention there art pro vided controlled flash evaporation channels down through which water to be evaporated passes from a higher to a lower pressure. In the lower pressure region there are provided condenser tubes and baffle arrangements along with a fresh water collection trough and an unevaporated collection trough for separating and distributing the unevaporated solution and the recovered fresh water. This arrangement lends itself particularly well to multistaging in an economically constructed unit.

Specific embodiments of the invention have been chosen for purposes of illustration and description, and are shown in the accompanying drawings, forming a part of the specification, wherein:

FIG. 1 is a fragmentary section view of an evaporator system embodying novel condenser means according to the present invention;

FIG. 2 is a side view, partially broken away illustrating the fresh Water recovery system of FIG. 1;

FIG. 3 is a section view, taken in elevation illustrating a second embodiment of the present invention;

FIG. 4 is a perspective view, partially broken away, illustrating a condenser arrangement according to the present invention;

FIG. 5 is a section view taken in elevation illustrating a portion of a multistage controlled flash evaporator type fresh water recovery system having integrated therein novel condenser means according to the present invention;

FIG. 6 is a partial side view of the system of FIG. 5; and

FIG. 7 is a section view taken in elevation showingone stage of a still further fresh water recovery system according to the present invention.

As shown in FIGS. 1 and 2 there is provided a fresh water recovery unit illustrated generally at 10. At the top of this unit there is provided a reservoir of saline water 12 from which fresh water is to be recovered. The body of saline water 12 rests upon an upper surface 14 formed by a plurality of elongated structural members 16. These elongated structural members are interrupted periodically by downwardly extending channel members 18. The channel members 18, as illustrated in FIG. 2, extend horizontally along with the structural members 16 from the front to the back of the unit 10. The channel members 18 each define a narrow evaporation channel 20 which opens to and extends vertically between the reservoir of saline water 12 and an associated condenser region 22. The condenser regions 22 are of considerably greater width than their associated evaporation channels 20'; and, as illustrated in FIG. 2, they also extend from the front to the rear of the device.

Each condenser region 22 is lined with a waterproof liner 24. Inside the condenser regions 22 there is provided a U-shaped separator element 26 which extends from the front to the back of the device.

Approximately halfway between the top of the U- shaped separator element 26 and the top of the condenser regions 22 there is provided a canopy-like upper baflle 28 which extends over the separator elements 26 to prevent any liquid droplets from falling directly down into the U-shaped separator element.

As shown in cross section in FIG. 1, there is provided an upper set of

condenser tubes

30a, 30b and 300, within the condenser region 22. There is additionally provided a lower set of condensing tubes 31a, 31b and 31c just under the upper set within the condenser region. The condenser tubes extend horizontally from the front to the back of the device and are supplied with coolant liquid 32 from an external source (not shown). It will be noted that the condenser tubes in each of the sets are arranged along a triangular pattern so that no tube in any set is directly above another tube in that set. This vertical disalignment of the tubes serves to prevent drippage of condensate from any one tube down upon another tube in the set.

An intermediate baffle 34 is placed between the two sets of

tubes

30 and 31 in order to direct the condensate which falls from the upper set away from the tubes of the lower Set.

The system thus far described operates in the following manner: The saline water 12 located above the upper surface 14 is maintained at pressure and temperature conditions corresponding to saturation. That is, any increase in temperature or any decrease in pressure will cause vaporization of the water 12. The saline water flows gradually down through the evaporation channels 20 in the channel members 18 toward the condenser regions 22. During such downward flow the water experiences a gradual pressure drop which results in a controlled flashtype evaporation. In this controlled flash type evaporation, a portion of the saline water vaporizes, thereby extracting heat from the unevaporated portion. This vapor occupies a much greater volume and has much less inertia than the unevaporated liquid. Accordingly it is impelled at a rapid rate downwardly through the channel 20. This rapid movement of vapor is accompanied by a smoothly distributed pressure gradient along the channel which results in a gradual evaporation, or controlled flash along the channel. This controlled flash evaporation is similar to that achieved according to US. Patent 3,214,350. Both vapor and unevaporated saline water are discharged from the bottom of the channels 20 into the condenser region 22. The unevaporated liquid tends to adhere to the waterproof liner 24 in the condenser region and thus for the most part, follows the walls of the condenser region 22 down to a saline water collection trough 36 at the bottom of the condenser region 22. Any premature drippage of the unevaporated saline water is prevented by the upper baffle 28 from entering into the interior of the U-shaped separator element 26.

The vapors which issue from the descending saline water in the channels 20 fill the greater portion of the interior of the condenser regions 22, and proceed through spaces 38 between the upper bafile 28 and the top of the U-shaped separator element 26. These vapors enter into the interior of the U-shaped separator element 26, and in so doing, they directly contact the outer surface of the

condenser tubes

30a, 30b and 30c. These condenser tubes, as illustrated in FIG. 2, extend in a horizontal direction; and as illustrated in FIG. 1 they are arranged in vertical disalignment so that no condenser tubeis directly above another tube. As a result, the condensate which forms at any location falls directly down from that location onto the intermediate bafile 34 and from there into the bottom of the U-shaped separator element 26 where fresh water 40 is collected. Similarly, vapors which do not contact the

upper tubes

30a, 30b and 300, pass downwardly past the intermediate baflie 34 and contact the lower tubes 31a, 31b and 310 where they condense into liquid form and drip directly into the condensate pool in the bottom U-shaped element 26.

It will additionally be noted that the total volume occupied by the condenser tubes occupies only a few percent of the total condenser region volume. This, of course, reduces the complexity and construction costs of the device. However, it is to be noted that this drastic reduction in condenser surface area actually increases the overall condensing effectiveness of the device. In part, this is due to the fact that the horizontal orientation and vertical dis alignment of the tubes prevents the buildup of insulating liquid films thereon. In further part, however, this increase in condensing effectiveness is due to the fact that the condenser tubes, in occupying only a few percent of the total condenser interior, provide large spaces between the condenser tubes which permit free and unobstructed flow of incoming vapor without appreciable pressure drop through the tubes directly to the condenser surface on which each portion of the vapor becomes liquified. As a result, fullest use is made of the entire condenser surface area.

FIG. 3 shows, in fragmentary cross section, an alternate form of evaporator-condenser arrangement. In the arrangement of FIG. 3 saline water is directed via an inlet tube into the bottom of a rectangular housing 52 so that there is maintained therein a body 54 of liquid saline water. The pressure and temperature of the water entering through inlet tube 50 are at saturation temperature slightly higher than the pressure within housing 52. Therefore in order to bring pressure and temperature within housing 52 into equilibrium, a portion of the Water entering through inlet tube 50 will flash on the surface of the water pool 54 so that vapors, illustrated schematically by the arrows 56, are emitted from the upper surface of the water. Immediately above the surface of the body 54 of saline water, there are located generally U-shaped trough like collection elements 58 which open upwardly. A triangularly arranged array of condenser tubes 60a, 60b and 60c extend lengthwise inside each collection element 58. As in the preceding embodiment, these condenser tubes convey fluid coolant 62 which maintains their outer surfaces at a temperature below the saturation conditions existing within the housing 52. As the vapors 56 proceed upwardly within the housing 52, they eventually contact the cooler surfaces of the condenser tubes 60. As a result, the vapors condense on these surfaces in liquid form.

In the embodiment of FIG. 3, as in the preceding embodiment, it will be noted that the condenser tubes 60a-c are arranged to occupy only a very small percentage of the total volume within the housing 52. Thus, all of the vapors within the housing may travel directly to the condensing surfaces on which they are to be condensed and they are not forced first to pass over other, noneffective condensing surfaces. Additionally, as in the preceding embodiment, the condenser tubes 60 are an.

ranged in vertical disalignment so that the condensate which forms on their outer surfaces will drop directly into the collection troughs 58 without building up on other condensing tubes thereby impairing their efficiency.

FIG. 4 illustrates a unique condenser arrangement utilizing the principles of the present invention in a manner which may serve to reduce to an even greater degree the costs of condenser construction. As shown in FIG. 4 there is provided a tubular outer housing 70 which may, for example, be formed of pipe or conduit. Toward the upper portion of the interior of the housing 70, there is provided a horizontally extending inlet plate 72 which extends across the interior of the housing 70 to form a chordal cross section therein. A diametrically positioned partition 74 extends downwardly from the under surface of the inlet plate 72 to a location close to the bottom of the housing 70. At that location, the partition 74 branches off into two adjoining symmetrical U-shaped configurations which merge with the sides of the housing 70 to form longitudinally extending lower collection channels 76 and 77. A plurality of condenser tubes 80 extend along inside the housing 70 in vertical disalignment on each side of the partition 74 in regions 78 and 79 just above the collection channels 76 and 77. Means (not shown) are provided for conveying coolant fluid through the coolant tubes.

Steam or other vapor to be condensed in the apparatus shown in FIG. 4 is passed along inside the housing 70 above the inlet plate 72. This steam or vapor is then admitted into the regions 78 and 79 in distributed manner via a plurality of inlet holes 82 arranged along the inlet plate 72. This steam or vapor passes from the various inlet holes 82 directly to the tubes 80 without undergoing any tortuous or turbulent movement. Each elemental portion of this when it is condensed and when it has been converted to steam is condensed directly and immediately upon the condenser surface which it strikes. It then drips directly down in liquid form into the collection channels 76 and 77 thus preventing any buildup of heat insulating liquid film on the condenser tubes.

The arrangement shown in FIG. 4 is especially useful in comparing condenser tubes having difi'erent positional arrangement and surface characteristics. For example, the tubes on the left side of the partition 74 may be made of titanium while those on the opposite side may be made of a cupro-nickel composition. So long as the openings 82 in the inlet plate 72 are equally distributed, it can be assumed that the amount of steam or vapor admitted to the tubes on opposite side of the partition 74 will be controlled by the condensing ability of the tubes 80 in areas 78 and 79 respectively on each side of the division plane. Accordingly, the amount of condensate retrieved along the tube channels 76 and 78 serve as a measure of the effectiveness of the different tube arrangements and tube surface and material characteristics in condensing the vapors.

FIGS. 5 and 6 show a still further embodiment of the present invention, such embodiment comprising a multistage controlled flash evaporator with integral condensation provided therein. The system shown in FIGS. 5 and 6 comprises front and rear plate assemblies 100 and 102 between which the various integrated evaporators and condensers (to be described hereinafter) extend. As shown in FIG. 5, toward the top thereof, there are provided a plurality of condenser housings 104 arranged side by side with spaces 106 remaining therebetween. The condenser housings 104, which may be of sheet metal stock, extend between the front and rear plate assemblies 100 and 102. In cross section, as illustrated in FIG. 5, the condenser housings have essentially rectangular bottom portions and slanted top portions which terminate in a top opening 108. Canopy or umbrella-like covers 110 extend over the top opening 108 of each of the condenser housings 104 and are displaced a certain distance thereabove to permit vapors from the surrounding region to enter through the top 108- of the condenser housings 104. The covers 110, however, do prevent any liquid droplets which may drop directly downwardly from above, from entering in through the opening 108.

Within each of the condenser housings 104 there are provided a plurality of condenser tubes 112. As illustrated, these condenser tubes 112 are arranged with their centers located along two slanted lines which are generally parallel with the upper portion of the condenser housings 104. It will be appreciated that the condenser tubes 112, being thusly positioned in vertical disalignment, are arranged such that any condensate which forms on the external surface of one of the tubes, will not drip directly down upon another tube, but instead will fall into the bottom of the condenser housing 104.

The condenser housings 104 are supported on cross braces 114 which in turn are hung on channel members 116. Also supported from the channel members 116 are brackets 118 which support a shallow reservoir 120. This reservoir receives the saline water which has dripped over the covers 110, onto the upper surfaces of the condenser housings 104 and has flowed down in through the spaces 106 between the condenser housings. This liquid water then drips down into the shallow reservoir 120 where it remains until gradually it flows down through evaporation passages 122. These evaporation passages extend downwardly from the bottom of the shallow reservoir 120 and are filled with packing material 124 which is supported inside the passages 122 by means of screen 126 at their lower ends. The packing material 124 divides the evaporation passages 122 into a myriad of tortuous passageways extending downwardly through the evaporator passage 122. These passageways are restricted in cross section so that as vapors are formed from the water flowing down through them these vapors will occupy the major portion of the spaces between the individual particles of the packing material 124. These vapors are induced to flow rapidly downwardly through the evaporator passages 122 by virtue of the pressure differential which exists across the passages 122. This pressure differential is converted, by the downward velocity of the vapors, into a uniformly distributed pressure gradient along the evaporation passages. As a result of this gradient there is provided a controlled flash evaporation of the saline water in a manner corresponding to the controlled flash achieved in the embodiment of FIGS. 1 and 2.

Each of the evaporator passages 122 opens directly out onto the top of one of the covers of the next lower stage of the system. Both unevaporated saline water and evaporated vapors issue from the screen 126 of the evaporator passages 122. The vapors fill the region around the condenser housings 104 While the unevaporated saline Water drips down onto lower stage covers 110', and flows down along the tops of lower stage condenser housings 104', and proceeds down through the spaces 106' to a lower stage shallow reservoir It will be seen that the several stages of this unit are of substantially identical construction and that any number of stages can be added depending upon the total pressure differential which the system may accommodate.

Also as shown in FIG. 5, in dotted outline, there are provided at spaced locations fresh water collection conduits 130 which relieve the condenser housings 104 of the buildup of fresh water which drips down from the condensing tubes 112.

As shown in FIG. 6 there is provided a coolant system comprising a coolant inlet conduit which is connected to the wall assembly 102 and which opens via a header 142 into the condenser tubes 112 in the lower stage. At the opposite end of the unit there is provided another header 143 and collection conduit 144 which receives the coolant fluid from the condenser tubes 112 and transmits it via a conduit 146 up to the next higher stage of the system. Even though the coolant fluid has absorbed a certain amount of heat in the lower stage, and its temperature is raised, nevertheless in the next higher stage a higher temperature coolant fluid will suffice to produce condensation in that stage because of the higher pressures and temperatures of the vapors and unevaporated liquid present therein.

FIG. 7 shows an alternate form of condenser arrangement for use in the fresh water recovery system of FIGS. and 6. In this alternate arrangement various condenser housings 160 are provided with condenser tubes 162 arranged in horizontal banks of two layers. As shown, the tubes of the upper bank are staggered with respect to the tubes of the lower bank so that condensate which forms on the outside of any tube will drip directly downwardly to the bottom of the housing Without contaminating or increasing the film thickness of any other condenser tube. In the arrangement of FIG. 7, the covers 110 are eliminated by positioning the evaporator passages 122 in such a manner that they open directly downwardly into the spaces 106 between the various condenser housings. With the arrangement of FIG. 7, it is-possible to reduce the vertical height per stage for a given amount of pressure drop per stage.

It will be appreciated from the above that the present invention achieves improved condensation of vapors with structures which are far less costly to produce and to maintain than has heretofore been considered possible. Thus, by selectively arranging condenser tubes both with respect to the vapor inlet and by restricting the amount of condenser surface in the unit a very eflicient and low cost system is achieved.

What is claimed as new and desired to be secured by Letters Patent is:

1. A condenser comprising an enclosure forming a substantially sealed chamber, means providing an entrance for admitting both vaporized and unvaporized liquid to said chamber within a region above an hereinafter defined array of condenser tubes for condensing the vapor to a pure liquid state, a common collection means for condensate collection disposed substantially in vertical alignment with respect to said chamber entrance and having an opening facing the same, a plurality of condenser tubes forming at least one array of tubes mounted by said enclosure in a manner such that their longitudinal axes are substantially parallel and horizontal to the enclosure, at least some of the tubes of said array being positioned within said opening of said common collection means and all of said tubes in said array located in at least three parallel vertical planes with each tube in each plane being staggered to be in vertical disalignment with an adjacent tube in an adjacent plane so that liquid con densate formed on the exterior surface of each tube drops past a tube in a lower plane and directly into the common collection means thereby to avoid contact with all lower condenser tubes of said array, means to admit coolant to and withdraw coolant from said tubes in said array, deflection means mounted within said chamber between said entrance means and said opening to deflect past said opening to said common collection means the unvaporized liquid entering said chamber, and means for collecting the pure liquid condensate from said common collection means.

2. The condenser of claim 1 including a second array of condenser tubes of similar make-up to the first array,

said second array of condenser tubes mounted within said common collection means, and a baffle element within said common collection means and between said arrays thereby to deflect falling condensate past sa d second array.

3. The condenser of claim 1 wherein said common collection means includes a trough positioned directly under said condenser tubes.

4. A condenser as in claim 1 wherein said condenser tubes are arranged to permit direct contact of each thereof by vapors passing through said vapor entrance means.

5. A condenser as in claim 1 wherein the volume occupied by said condenser tubes is about 2 to 5% of the total volume of the interior of said chamber.

6. A condenser construction comprising a horizontally extending tubular housing, a partition plate extending in a generally horizontal direction across the upper interior of said housing and dividing said interior into upper and lower regions, said partition plate being perforated at several locations therealong to provide a distributed inlet for vapor from the upper to the lower region, a partition diametrically positioned to extend downwardly from under the surface of the partition plate and terminating in two adjoining symmetrical U-shaped configurations which merge with the sides of the condenser housing to form longitudinally extending lower condenser collection channels, a bank of condenser tubes extending along through said lower region and arranged therein with respect to the bottom of said housing so that condensate which forms thereon drops directly down to the bottom of said housing, the condenser tubes of said bank being arranged in vertical disalignment and in staggered array with re spect to the bottom of the housing so that no condenser tube is directly above another and that condensate which forms on higher tubes drops down and passes lower condenser tubes in the drop to the bottom of said housing thereby avoiding any contact with said lower condenser tubes.

References Cited NORMAN YUDKOFF, Primary Examiner F. E. DRUMMOND, Assistant Examiner US. Cl. X.R.

12/ 1932 Great Britain.