IL31023A - Condenser tube - Google Patents

Description

Condenser tube SALINE WATER CONVERSION CORPORATION C. 29217 This invention relates to vapor condensation, and more particularly it concerns novel surface condenser structures useful in the condensation of steam and the like.

Surface condensers are widely used in connection with steam power 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 constructional configuration of a surface condenser unit involves an enclosure or outer elongated covering which is closed at each end by means of a tube sheet. A plurality of circular condenser tubes extend along the interior of the enclosure and pass through the tube sheets at each end thereof. A cooling fluid is caused to pass through the circular 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; when it contacts the cooler surface of the condenser tubes, it condenses thereon into liquid form and drips down into a collection trough located below the tubes.

In order to obtain maximum efficiency in condenser units, it has been the practice to utilize a very large number of circular condenser tubes, each usually extending along the interior of the condenser enclosure and passing through the tube sheets at each end thereof. ^ Typical prior art condenser units have anywhere from 22 One of the chief commercial drawbacks of a conventional surface condenser unit is its construction cost. The cost of each of the large number of condenser tubes used in the unit accounts for a major portion of the expense. In addition, the joining of each of the condenser tubes with the tube sheets is extremely expensive and time consuming since each Joint must be skillfully sealed and examined for leaks. Moreover, structural problems result from the use of a large number of condenser tubes, since very little of the tube sheet remains at each end of the condenser to provide support for the condenser tubes. As a result, costly reinforcing structures are often provided".

The present invention provides a novel surface condenser tube which substantially increases the overall efficiency of the surface condenser unit. Since the overall efficiency of such units is increased substantially., fewer condenser tubes are necessary than we:re used in prior units of comparable capacity. Accordingly, the present invention provides a surface condenser unit which is less complex and much more economical to construct than prior systems of comparable capacity.

I have found that the use of" ordinary circular condenser tubes in surface condenser unlfcs involves certain inherent disadvantages. Thus, I have found that as the vapors condense into fluid oh the surface of each ,of the circular condenser tube3 and flow down and around the tubes before finally dripping off, the bottom of the tubes are coated with a thick fluid film in the area where fluid droplets form. In some instances, th.Is area may range from 10 to 12 of the total surface area of each tube. The fluid film formed on this surface resists heat transfer that is necessary to carry out the desired condensation. Accordingly, ^ the accumulation of this film on the surface of the condenser tubes reduces their overall effective or working surface.

According to the present invention there is provided a condenser comprising means defining a chamber, means for directing vapors to said chamber to be condensed therein, a plurality of condenser tubes passing through said chamber and arranged therein with their axes in vertical disalignment so that no condenser tube extends directly above another tube whereby the condensate which forms at any location along each of said tubes drops directly from said looatioh and avoids further contact with said tubes, means for passing coolant through said condenser tubes to cool said vapors passing thereby whereby condensate is formed on the surfaces of said tubes, and means for collecting the condensate; characterized in that at least part of the surface of each of said condenser tubes is streamlined in the direction of condensate flow to provide lengthwise a substantially sharp edge whereby the accumulation of a film of condensate oh the surface of the condenser tubes is substantially reduced.

Each of the condenser tubes is conveniently serrated lengthwise alon the apex of its sharp edge.

The sharp edge of the condenser tubes may be in the form of a fin depending in the direction of condensate flow, the tubes being conveniently of circular cross-section and the fins being of straight ribbon forn The tubes conveniently include internal' heat-conducting fins.

There has thus been outlined rather broadly the more important features of the invention In order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject of the claims appended hereto. Those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures for carrying out the several purposes of the invention. It is important, therefore, that the claims be regarded as including such equivalent constructions as do not depart from the spirit and scope of the invention.

Certain specific applications of the invention have been chosen for purposes of illustration and description, but the invention should not be limited thereto since the surface condenser tubes disclosed herein have uses in all surface condenser units. These specific applications are shown in the . accompanying drawings and are described in the following portions of the specification.

In the drawings: Fig. 1 is a fragmentary sectional view of a condenser system embodying novel condenser tube structures according to the present invention; Fig. 2 is a side view, partially broken away, illustrating the condenser system of Fig. 1; Fig. 3 is a cross-sectional view of the condenser tubes in the system of Fig. 1; Fig. 4 shows an alternative embodiment of a surface condenser tube in accordance with the present invention; Fig. 5 shows another alternate embodiment of a surface condenser in accordance with ithe present invention; .

Fig. 7 shows a condenser .tube similar to that of Pig. but having internal heat conducting fins; Fig. 8 shows a lengthwise perspective of a further condenser tube in accordance with 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. 2t they also extend from the front to the rear of the device.

Each condenser region 22 is lined with a waterproof liner 2k and is provided with 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 elements 26 and the top of the condenser regions 22, there is a canopy-like upper baffle 28 which- extends over, the separator elements 2β to prevent any liquid droplets from falling directly down into the U-shaped separator element. This baffle 28, as well as the remaining baffles hereinafter described, may take alternative shapes. For example, the baffle may consist of an inclined flat metal sheet which deflects the liquid droplets to one side of condenser region 22.

As shown in Fig. 1, there is provided an upper set of condenser tubes 30a, 30b and 30c, within the condenser region 22 . There is also 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 between the front and back tube sheets of the device (not shown) and are supplied \;ith 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 direc'tly 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. This baffle 3 may take alternative shapes in the same manner as baffle 28, discussed above.

In the preferred embodiment, condenser tubes 30a-c and 31a-c are each of like configuration. As shown in Figs. 1, 3 and 6, the surface of each tube is streamlined in the direction of condensate flow so as to provide a rather* sharp edge, indicated generally at 42, on the bottom area by fusing or mechanically adding a drip extension or fin 44 to a circular condenser tube, or the tubes may be formed, in the configuration Illustrated. Alternatively, as shown in Pigs. 4 and 7, a teardrop shaped tube may be used to provide the desired edge- like surface; or, as shown in Fig. 5, a straight ribbon fin mechanically added or fused to an otherwise ordinary circular condenser tube may provide the desired configuration. As an alternative to the edge- like structure provided by each of the embodiments discussed hereinabove, the condenser tube 48 illustrated in Fig. 8 may be used.

This tube provides a series of points 50 on the bottom of the tube 48. The tube may be constructed by serrating a condenser tube of substantially the s e configuration as Fig. 3 lengthwise along the apex of its streamlined configuration. This construction additionally streamlines a tube of the configuration of Fig. 3 in the longitudinal direction and thus further reduces the area on which water film can accumulate. Additionally, the condenser tube configuration of Fig. 5 may also be lengthwise serrated in the same manner.

As shown in Figs. 6 and 7, further heat transfer, an 3 thus greater overall efficiency, may be obtained by providing internal heat conducting fins 52 in each of the condenser tube embodiments previously mentioned.

The system described above operates in the following manner: The saline water 12 located above the upper surface 14 is maintained in a saturation condition. The saturated saline water flows gradually down through the evaporation channels 20 in the channel members 18 toward the condenser regions 22. During this downward flow, the water experiences a gradual pressure drop which results in a controlled flash- type evaporation whereby a portion of the saline water is vaporized. The vapors generated are impelled at a rapid rate downwardly through the channel 20 and are accompanied by a smoothly distributed pressure gradient along the channel which results in a gradual evaporation along the channel. This evaporation is similar to the controlled flash achieved according to U.S. Patent No. 3,214, 350 . Any unevaporated liquid follows, for the most part, the walls of the condenser region 22 down to a saline water collection trough 36 at the bottom of the condenser region 22 . Baffle 28 prevents drippage from the unevaporated saline water from entering the interior of the U-shaped separator element 26 .

The generated vapors fill the greater portion of condenser region 22, and directly contact the outer surfaces of the streamlined condenser tubes 30a-c and 31a-c whereby condensate is formed on the surfaces thereof. The condensate formed on each of the surfaces flows around and down the streamlined surface toward the edge or apex 42. The condensate accumulates on the edge 42 and finally drips off to be collected in the fresh water trough, shown generally at 40 .

Ao fully explained in my aforementioned -oop It will also be noted from; the above that by arranging the condenser tubes in eoooipdanoe with the -fe-each^ ■ofil-y are t&e—benefits disclosed therein do-rive-d, but -e-i-so—¾- more compact condenser unit may be built. Since the streamlined condenser tubes have a rather s¾arp edge, these structures aid in channeling the condensate directly to the collection trough in such a manner that the condenser tubes may be more closely arranged with eac!a other in both the horizontal and vertical directions while still being vertically disaligned so that the drippings of one tube do not touch another tube.

It will be appreciated from fc:he above that the present invention increases the efficiency of otherwise known surface condensers. Thus, by providing condenser tubes having a fin depending in the . direction of condensate . flow to provide a lengthwise edge, a very efficient condenser

Claims (8)

1. OIAIMS 1.

2. A condenser comprising means defining a chamber, means for directing vapors to said chamber to be condensed therein, a pluralit of condenser tubes passing through said chamber and arranged therein tilth their axes in vertical disalignment so that no condenser tube extends directly above another tube whereby the condensate which forms at any location along each of said tubes drops directly from said location and avoids further contact with said tubes, means for passin coolant through said condenser tubes to cool said vapors passing thereby, whereby condensate is formed on the surfaces of said tubes, and means for collecting the condensate; characterized in tha at least part of the surface of each of said condense tubes is streamlined in the direction of condensate flow to provide lengthwise a substantially sharp edge whereby the accumulation of a film of condensate on the surface of the condenser tubes is substantially reduced. ,i A condenser as in Claim 1 wherein each of said condenser tubes is serrated lengthwise along the apex of its said edge.

3. A condenser as in either pf Claims 1 and 2 wherein the said edge of said condenser tubes is a fin depending in the direction of condensate flow.

4. · A condenser as in Claim 1 wherein each of said condenser tubes comprises a circular condenser tube having a straight ribbon fin,

5. A condenser as in any of Claims 1 to 4 wherein each of said condenser tubes includes internal heat conducting fins. 31023/2

6. A condenser as in Claim 1 wherein each of said ' condenser tubes is cross-sectionally teardrop shaped.

7. · A condenser as in any of Claims 1 to 6 wherein each of said condenser tubes extends horizontally through said chamber* 8. A condenser substantially as described with reference to the accompanying drawings. For DR. TNER

8. S IS:CB