US3885620A

US3885620A - Heat-exchange installation for cooling of a heat-exchange liquid

Info

Publication number: US3885620A
Application number: US448520A
Authority: US
Inventors: Cleve Hans-Henning Von
Original assignee: GEA Luftkuehler GmbH
Current assignee: GEA Luftkuehler GmbH; GEA Luftkuehlergesellschaft Happel GmbH and Co KG
Priority date: 1973-11-13
Filing date: 1974-03-06
Publication date: 1975-05-27
Anticipated expiration: 1992-05-27
Also published as: ZA741155B; DE2356505A1

Abstract

A plurality of heat-exchange elements are provided through which heat-exchange liquid can circulate to be cooled therein. A reservoir is adapted to contain the heat-exchange liquid when any of the heat-exchange elements are not in use. Conduits connect the heat-exchange elements with a user to supply and receive heat-exchange liquid from the same, and also with the reservoir. A source of gaseous pressure fluid can be connected with the reservoir at will, in order to thereby rapidly expel heatexchange liquid contained in the reservoir via the conduits and into the heat-exchange elements.

Description

United States Patent 91 Von Cleve HEAT-EXCHANGE INSTALLATION FOR COOLING OF A HEAT-EXCHANGE LIQUID [75] inventor: Hans-Henning Von Cleve, Bochum,

Germany [73] Assignee: Gea Luftkuhlergesellschaft Happel GmbH & Co. KG, Bochum. Germany [22] Filed: Mar. 6, 1974 [21] App]. No.1 448,520

[30] Foreign Application Priority Data Nov. I3, 1973 Germany 2356505 [52] US. Cl. 161/32; 165/50; l65/7l [51] Int. Cl. G0ld 23/00 [58] Field of Search 165/32, 50, 70, 71, 110, 165/111 [56] References Cited UNITED STATES PATENTS 3,828,843 8/1974 Asfura l65/l ll [451 May 27, 1975 Primary Examiner-Charles Sukalo Attorney, Agent, or Firm-Michael S. Striker [57] ABSTRACT A plurality of heat-exchange elements are provided through which heat-exchange liquid can circulate to be cooled therein. A reservoir is adapted to contain the heat-exchange liquid when any of the heatexchange elements are not in use. Conduits connect the heat-exchange elements with a user to supply and receive heat-exchange liquid from the same, and also with the reservoir. A source of gaseous pressure fluid can be connected with the reservoir at will, in order to thereby rapidly expel heat-exchange liquid contained in the reservoir via the conduits and into the heatexchange elements.

12 Claims, 4 Drawing Figures 31 L.. 25p I {MED HAY 2 7 9. 5

SHEET PAT MED HAYZY 1975 SHEET HEAT-EXCHANGE INSTALLATION FOR COOLING OF A HEAT-EXCHANGE LIQUID BACKGROUND OF THE INVENTION The present invention relates generally to a heatexchange installation, and more particularly to a heatexchange installation for cooling of a heat-exchange liquid which is heated in a user.

Installations of this general type here in question are needed for cooling heat-exchange liquid, for instance water, which has been heated up during passage through a user. This could for instance be a turbine or the like, and the heat exchange elements in such installations are usually air-cooled surface condensers or mixed-type condensers through which the heated heatexchange liquid is circulated in order to be cooled therein before it is returned to the user. For instance, if such an installation is used in conjunction with turbines in a power generating station, the steam leaving the turbines is caused to condense by passing it through condensers which are cooled by cooling water. The cooling water in turn is circulated through heatexchange elements when it is cooled by air cooling. The heat-exchange elements can be cooled by natural draft or by forced draft, for instance produced by fans or the like. Installations of this type are known to have heatexchange capacities of up to about 300 GCAL/h.

Particularly in the type of heat-exchange system wherein the heat-exchange elements are cooled by natural draft, the only real way in which the cooling capacity can be regulated is to cover the exposed surfaces of the heat-exchange elements to a greater or lesser degree against access of air, for instance by using shutters or other elements which can block the access of air to a greater or lesser degree depending upon the manner in which they are adjusted. This presents certain problems. In the event that there is danger of frost, the heatexchange elements must either be all evacuated of cooling water, or at least groups of them must be so evacuated, if a drop in cooling capacity requirements occurs, for instance if less steam arrives from the turbines. On the other hand, it is important to be able to rapidly fill the heat-exchange elements if, as may occur quite frequently, there is a rapid increase in the requirement for cooling capacity and additional ones of the heat-exchange elements must be put into service.

Evacuating the heat-exchange elements is usually not connected with any difficulties. Such heat-exchange elements are usually located at some considerable distance above ground, in order to make use of the available natural draft, or to be able to direct a forced draft at them more efficiently. This means that if appropriate valves are opened, the cooling water can be allowed to run out from the heat-exchange elements under the influence of gravity. Of course, there are usually very large quantities of water involved and prudent management practices dictate that this water should be stored, rather than be discharged to be replenished later with new water. Another consideration is of course that new water could probably not be supplied rapidly enough when the heat-exchange elements have to be refilled, since it is not available in a body as will be the previously used water if it has been saved in a reservoir. For this reason, such installations use reservoirs which are located at or below ground level and into which the heat-exchange elements discharge when they are emptied to take them out of service.

The situation is quite different when the emptied heat-exchange elements must subsequently be refilled with water. The volumetric capacity of such heatexchange elements is very large, and may be on the order of a thousand or even more cubic meters of water. The requirements of systems of the type in question often necessitate that this amount of water be recharged into the empty heat-exchange elements in an extremely short period of time, which may be as short as approximately 20 seconds and only as long as approximately 60 seconds. The problem can be handled by using, as does the prior art, very large and powerful pumps; however, these of course have correspondingly high energy requirements and need to be regularly maintained. This of course is not only labor-intensive but also capital-intensive, since large investments are required for these pumps at the time the installation is erected.

Other prior-art suggestions have also been studied but none of them have been found to be fully satisfactory, for various reasons which again include the complexity of installation and the capital-intensive nature of the equipment required.

Moreover, there are now being plant installations having a heat-exchange capacity of 2000 GCAL/h or even higher, and this would require such tremendous increases in the capacity of the prior-art pumps and associated equipment, in their maintenance and in the initial purchasing cost, as to render the operation of such installations economically impractical.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to overcome the disadvantages of the prior art.

More particularly, it is an object of the invention to provide an improved heat-exchange installation for cooling of a heat-exchange liquid which is heated in a user, which installation is not possessed of the aforementioned disadvantages.

An additional object of the invention is to provide such an improved heat-exchange installation wherein the re-charging of empty heat'exchange elements can be carried out in a simple, rapid and reliable manner.

Another object of the invention is to provide such an installation wherein the re-charging of the heatexchange elements can be carried out at economically reasible cost.

In keeping with the above objects, and with others which will become apparent hereafter, one feature of the invention resides in a heat-exchange installation for cooling ofa heat-exchange liquid which is heated in a user. The installation comprises a plurality of heatexchange elements through which heat-exchange liquid can circulate to be cooled therein. A reservoir is adapted to contain the heat-exchange liquid when any of the heat-exchange elements are not in use. Conduit means connects the heat-exchange elements with a user to supply and receive heat-exchange liquid from the same, and it also connects them with the reservoir. A source of gaseous pressure fluid is provided, and connecting means connects the reservoir with the source so as to admit pressure fluid from the latter into the reservoir and to expel the heat-exchange liquid contained therein via the conduit means into the heat-exchange elements, to thereby provide for rapid charging of the heat-exchange elements with the heat-exchange liquid.

The gaseous fluid may be a gas or it may be steam, and its use has the advantage that the requirement for employing pumps of any kind is completely avoided. Thus, the investments required in the erection of such an installation are significantly reduced since all that it necessary is to supply a conduit which connects the reservoir with a source of compressed gas or steam. Especially if the installation is a part of a power plant, it is a very simple manner to supply steam from the power plant to the reservoir. However, if the use of gas is necessary or preferred, this also does not involve significant economic expenditures, because it is not necessary to provide equipment for compressing gas since it is entirely possible to use mobile containers of pressur ized gas which can be readily obtained. Moreover, by resorting to the present invention it is very readily possible to meet the very brief time requirement for refilling the heat-exchange elements, that is within a period of for instance 20-60 seconds, depending only upon the capacity of the steam or gas conduit.

Moreover, the filling capacity of the heat-exchange elements can be increased by resorting to the present invention, without at the same time having to significantly increase economic expenditures. This is of great importance in view of the projected increases in the heat-exchange capacity of such installations, up to 2000 GCAL/h or higher. In particular, it is no longer necessary to subdivide the total available cooling surface area of the heat-exchange elements into several sectors each having a correspondingly smaller volumetric capacity. This eliminates the heretofore necessary valve arrangements which had to be precisely controlled by automatic equipment.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic illustration, showing one embodiment of the invention wherein a surface condenser is employed;

FIG. 2 is a view similar to FIG. I, but showing a mixed condenser;

FIG. 3 is a view similar to FIG. 1, but showing a further surface condenser arrangement; and

FIG. 4 shows the embodiment of FIG. 3 but using a mixed condenser.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now firstly to FIG. I in the drawing, it will be seen that reference numeral 1 identifies a turbine of which more than one can of course be present and which may be installed in a power plant. The turbine 1 is coupled with a generator 2, and again there may be more than one of these generators provided. Waste steam derived from the turbine passes via a conduit 3 to a surface condenser 4 in which it becomes precipitated, that is in which it condenses. The condensation of the steam is obtained with the aid of cooling water which is circulated through the surface condenser 4 which thus constitutes a user being supplied via a conduit 5 and leaving the surface condenser 4 via a conduit 7 through which it is pumped by a pump 6. Of course, at this time the cooling water is heated because of its heat exchange with the steam. It is now returned to the cooling elements 8 to cool it down again.

The drawing shows several of the cooling elements 8 which have not been shown in detail, because they are well known to those skilled in the art and their detailed construction forms no part of the invention. These cooling elements may be part ofa cooling arrangement that may be located in a natural-draft cooling tar or in a forced-draft cooling tar. In the event that there is a danger of frost, and cooling capacity requirements vary, for instance because there is less steam than must be cooled, it is important that it be possible to take some or even all of the cooling or heat-exchange elements 8 out of service. This is done by emptying them of cooling water. For this purpose there is provided a branch conduit 9 in which a valve 10 is interposed. A branch conduit II is connected with the conduit 7 and communicates at its other end with a reservoir l2; a valve 13 is interposed in the conduit II.

The reservoir 12 itself is so constructed that it can accommodate the cooling water of all of the cooling elements 8. In other words, its volumetric capacity equals to the combined volumetric capacity of the cooling elements 8. The reservoir 12 is either placed on ground beneath the level of the cooling elements 8, or it is embedded in the ground. The important factor here is that the cooling water must be able to flow out of the cool ing elements 8 under the influence of gravity.

When the installation is to be filled and started up, the various conduits including the reservoir 12 and at least the conduits are advantageously underground are first filled with cooling water. Thereupon, the valve 13 in the conduit 11, the valve 14 in the conduit 7 and the valve 15 in the conduit 5 are closed. The valve 16 in the conduit 17 intermediate the reservoir 12 and the conduit 7, the valve 10 in the conduit 9, the valve 18 between the conduit 7 and the conduit 5, the valve 20 which is located above the cooling elements 8 and the water level indicator 19, and the venting valve 21 connected with the conduit 5 are all open. The valve 22 in the branch 23 of a steam conduit 24, the valve 25 in a further branch 26 of the steam conduit 24, and the valve 27 in the conduit 28 connecting the condenser 4 and the steam conduit 24 remain closed for the time being. It should be noted that the branch 23 communicates with the reservoir 12 above the level of liquid in the same, whereas the branch 26 communicates with the reservoir 12 below the level of cooling water therein. Now, the valve 22 is opened, permitting steam to enter into the reservoir 12 and to force water from the same via the conduit 17 and the valve 16 into the cooling water circuit, that is into the conduit 7, and this part of the conduit is vented of air via the valve 21. Even ifinitially no steam is available at the time the installation is started up, the circuit can be filled out of the reservoir 12 by the pump 29, if the valve 16 has been closed before hand. After switching on one of the circulating pumps, for instance the pump 6, a circulation of water will take place via the valve 10 and the surface condenser 4.

The purpose of having the two branch conduits from the conduit 24 communicate with the reservoir 12 above and below the level of cooling water therein, is to assure that the steam cushion which builds up above the level of liquid presses the cooling water through the conduit which communicates with the reservoir at the lowest level thereof.

Moreover, by using steam it is possible to preheat the cooling water in the reservoir l2 before it is introduced into the cooling elements 8, thus assuring that the latter can be filled without any danger to them even in conditions of deep frost. This eliminates the previous necessity to circulate the cooling water through the condenser 4 to heat it therein before it is admitted into the cooling elements 8. The preheating can be accomplished by admitting steam via the

valves

27 and 25 into the condenser 4 or into the reservoir 12. A temperature regulating device 25a of a construction known per se can be associated with the valve 25. A non-illustrated small regulating valve or the venting valve 21 may be employed to discharge excess water from the closed condenser circuit as required. The reservoir 12 is sufficiently large in its volumetric capacity to take into account any expansion of the volume of the water.

The valves 14 and are slowly opened and the water volume of the conduit 7 extending to the cooling elements 8 is slowly allowed to circulate. The warmingup of the

conduits

7 and 5 results from a slow throttling of the valve 10, keeping in mind that the pressure difference between the

conduits

7 and 5 must not be so great that the water could enter from the conduit 7 to the lowest cooling surfaces of the cooling elements 8 and where it might freeze. It is important to prevent stagnation of cold water in the riser conduits 30, for which purpose the valve I0 must be repeatedly fully opened and then throttled again.

After the entire underground system has been warmed up, the cooling elements 8 can be filled as soon as sufficient steam pressure is available. For this purpose, the

valves

14 and 15 are closed again and the valve 13, which may be a slide valve, is opened. A command unit which is well known from the art of feedback circuits and which supplies a signal of a desired value, can be connected with the pressure regulating device 31 that is in turn associated with the valve 22. it supplies a signal operating the valve 22 via the regulator 31 and with the aid of steam pressure water is now expelled from the reservoir 12 via the valve 13 and all cooling elements 8 are simultaneously filled via the conduit 7 with the prewarmed water. The water rises into the upper conduit 32 and into the water level indicator 19. The air which is present in the cooling elements 8 is expelled via the venting valve 20. Subsequently, the

valves

14 and 15 are opened and the

valves

10 and 18 closed, and the circulation of cooling water to and from the condenser 4 can now begin.

In continuous operation of the installation shown in FIG. I, the water level regulator 33 can be connected to the pump 29 or the valve 16 which could also be a different type of closure member. When the water level is too high, water is bled into the reservoir 12 via the valve 16, whereas in the event of insufficient water level the pump 29 draws water from the reservoir l2 and adds it to the circulating water.

The cooling effectiveness of the cooling elements 8 is controlled by opening or closing the shutter which are located at those surfaces of the cooling elements 8 that are exposed to the draft of air. This is not novel and therefore requires no detailed description.

in continuous operation of the installation. the pres sure cushion of the steam in the reservoir 12 is elimi= nated by terminating the supply of the control signal from the command unit to the pressure regulator 31. The steam in the reservoir 12 will then slowly condense at the surface of the water remaining in the reservoir 12, or else it is vented to the exterior via the valve 34.

When the installation is to be emptied, that is when cooling water is to be discharged from one or more of the cooling elements 8 due to the danger of frost and a reduction in heat exchange or cooling capacity requirements, the

valve

14 and 15 are first closed. Thereupon, the valce l0 and the valve 13 are opened, as well as the valve 34 and the valve 20. The

valves

22 and 25 remain closed. The cooling water in the cooling elements 8 can now run out of the same under the influence of gravity, travelling via the open valves l3 and 18 into the reservoir 12. After the elements 8 are emptied, or those which are to be taken out of service, the valve 13 in the conduit 11 is closed, as is the valve 20. it is now advantageous to evacuate the cooling elements 8, a possibility which has not been separately illustrated but which would require the use of a vacuum pump, since this reduces the amount of oxygen contained in the cooling elements 8 and thus reduces the possibility of corrosion occurring in them. If, for instance, the cooling elements are evacuated to approximately 0.0l atmosphere, the residual oxygen content in them will be decreased to approximately 0.23 percent, which provides an effective protection against corrosion.

In the event any of the cooling elements I should become damaged and a leak develop, it is of course necessary to shut down the installation and empty the cooling element or elements. The damaged cooling element or elements can now be disconnected from the circuit and plugs installed in the conduits where the elements were previously connected, whereupon the installation can be placed back into operation. it is advantageous to provide adjustable throttles in the circuit ahead of the cooling elements 8, to provide for a uniform water distribution, and of course valves can be installed which could cut off any one of the cooling elements 8 from the circuit and thus make it unnecessary to shut down the installation when one of them becomes defective.

The embodiment in FIG. 2 corresponds essentially to that of FIG. 1, and like reference numerals identify like elements. it differs from the embodiment of FIG. 1 essentially by the fact that the cooling water which is cooled in the elements 8 passes through the conduit 5 not into a surface condenser 4, but into a mixed condenser 35 where it issues from the jets 36. Due to the temperature difference between the steam arriving from the turbine and the cooling water the steam condenses, so that at the bottom of the mixed condenser there will be formed a mixture of warm liquid composed of cooling water and condensate which is then passed through the elements 8. The operation of the embodiment in FIG. 2 is the same as in FIG. 1, except that the regulation of the highest water level is effected via the valve 15. whereas the pump 29 and the valve 16 serve to regulate the water level in the condenser 35.

The emptying=out and re=fllling of the cooling ele= ments 8 is carried out in the same way as described with reference to FIG. 1.

The embodiment of FIG. 3. wherein again like refer= ence numerals identify the same elements as before. shows that it is possible to refill the emptied cooling el= ements 8 with the aid of compressed gas, rather than steam. For this purpose, a gas conduit 37 is connected with the reservoir 12 at the upper end thereof. being provided with a valve 38. The conduit 37 is connected with a source 39 of compressed gas. either in form of mobile containers of compressed gas or a compressed gas installation, for instance an air compressor or the like. The valve 38 is controlled by a pressure regulating device 40 of known construction. which controls the flow-through cross'section of the conduit 37. although this could be omitted. Filling and emptying of the elements 8 is the same as described with respect to the embodiment of FIG. 1. The circulation of cooling water in the conduits and 7 is also the same as in FIG. 1, that is the cooling water is supplied to and returned from a surface condenser 4.

Finally. FIG. 4 shows an embodiment in which all elements correspond to those shown in FIG. 3, and which therefore requires no detailed description, except to point out that the surface condenser of FIG. 3 is replaced by a mixed condenser 35.

it should be understood that l have illustrated only those components of the various embodiments which are essential for an understanding of the invention. All other components, including regulating elements and the like. which are not essential for an understanding of the invention have not been illustrated, being well within the skill of those working in this field.

It will be understood that each of the elements described above. or two or more together. may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a heat-exchange installation for cooling of a heat-exchange liquid, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore. such. adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. in a heat-exchange installation for cooling of a heat-exchange liquid which is heated in a user. a combination comprising a plurality of heat-exchange elements through which heat-exchange liquid can circulate to be cooled therein. a reservoir adapted to contain said heat-exchange liquid when any of said heatexchange elements are not in use; conduit means connecting said heat-exchange elements with a user to supply and receive heat-exchange liquid therefrom. and also with said reservoir; a source of gaseous pressure fluid; and connecting means for connecting said reservoir with said source so as to admit pressure fluid from the latter into said reservoir and expel heat-exchange liquid contained therein via said conduit means into said heat-exchange elements. to thereby provide for rapid charging of the heat-exchange elements with the heat-exchange liquid.

2. A combination as defined in claim I, said reservoir having a lowest region; and wherein said conduit means includes a conduit which communicates with said lowest region.

3. A combination as defined in claim 2'. and further comprising valve means in said conduit for permitting and blocking the flow of heat-exchange through the same.

4. A combination as defined in claim 1, wherein said source is a source of steam under pressure.

5. A combination as defined in claim 1, wherein said source is a source of gas under pressure.

6. A combination as defined in claim 1, wherein said source is a source of steam under pressure; and wherein said connecting means comprises a connecting conduit and pressure and temperature-regulating means interposed in said connecting conduit.

7. A combination as defined in claim 1, wherein said source is a source of steam under pressure; and wherein said connecting means comprises a connecting conduit having one branch which communicates with said reservoir above the level of heat-exchange liquid therein; and another branch which communicates with said reservoir below the level of heabexchange liquid therein.

8. A combination as defined in claim 7; further comprising temperature regulating means interposed in said connecting conduit; and valve means interposed in said other branch and controlled by said temperatureregulating means.

9. A combination as defined in claim 7; further comprising pressure-regulating means interposed in said connecting conduit; and valve means interposed in said one branch and controlled by said pressure-regulating means.

10. A combination as defined in claim 7; and further comprising means located within said reservoir and operatively associated with said other branch for transmitting heat from steam in said connecting conduit to the heat-exchange liquid in said reservoir.

11. A combination as defined in claim I, wherein said source is a source of pressurized gas; and wherein said connecting means comprises a connecting conduit. and pressure-regulating means interposed in said connecting conduit.

12. A combination as defined in claim ll. wherein said reservoir has an upper region. and said connecting conduit communicates with said upper region; and further comprising valve means interposed in said connecting conduit and controlled by said pressureregulating means.

Claims

1. In a heat-exchange installation for cooling of a heatexchange liquid which is heated in a user, a combination comprising a plurality of heat-exchange elements through which heat-exchange liquid can circulate to be cooled therein; a reservoir adapted to contain said heat-exchange liquid when any of said heat-exchange elements are not in use; conduit means connecting said heat-exchange elements with a user to supply and receive heat-exchange liquid therefrom, and also with said reservoir; a source of gaseous pressure fluid; and connecting means for connecting said reservoir with said source so as to admit pressure fluid from the latter into said reservoir and expel heat-exchange liquid contained therein via said conduit means into said heat-exchange elements, to thereby provide for rapid charging of the heat-exchange elements with the heatexchange liquid.

2. A combination as defined in claim 1, said reservoir having a lowest region; and wherein said conduit means includes a conduit which communicates with said lowest region.

3. A combination as defined in claim 2; and further comprising valve means in said conduit for permitting and blocking the flow of heat-exchange through the same.

7. A combination as defined in claim 1, wherein said source is a source of steam under pressure; and wherein said connecting means comprises a connecting conduit having one branch which communicates with said reservoir above the level of heat-exchange liquid therein; and another branch which communicates with said reservoir below the level of heat-exchange liquid therein.

8. A combination as defined in claim 7; further comprising temperature regulating means interposed in said connecting conduit; and valve means interposed in said other branch and controlled by said temperature-regulating means.

11. A combination as defined in claim 1, wherein said source is a source of pressurized gas; and wherein said connecting means comprises a connecting conduit, and pressure-regulating means interposed in said connecting conduit.

12. A combination as defined in claim 11, wherein said reservoir has an upper region, and said connecting conduit communicates with said upper region; and further comprising valve means interposed in said connecting conduit and controlled by said pressure-regulating means.