US2891773A

US2891773A - Apparatus for filling and emptying air-cooled condensers

Info

Publication number: US2891773A
Application number: US554803A
Authority: US
Inventors: Heller Laszlo
Original assignee: Licencia Talalmanyokat Ertekesito Vallalat
Current assignee: Licencia Talalmanyokat Ertekesito Vallalat
Priority date: 1954-12-22
Filing date: 1955-12-22
Publication date: 1959-06-23
Anticipated expiration: 1976-06-23

Description

APPARATUS FOR FILLING AND EMPTYING AIR-COOLED CONDENSERS Filed Dec. 22, 1955 L. HELLER June 23, 1959 4 Sheets-Sheet 1 INVENTOR LASZLO HELLER ATTORNEYS June 23, 1959 HELLER 2,891,773

APPARATUSFOR FILLING AND EMPTYING AIR-000L120 CONDENSERS Filed Dec. 22, 1955 4 Sheets-Sheet 2 INVENTOR LASZLO HELL Elk ATTORNEYS June 23, 1959 4.. HELLER 2,891,773

APPARATUS FOR FILLING AND EMPTYING AIR-COOLED CONDENSERS Filed Dec. 22, 1955 4Shets-Sheet a INVENTOR. LASZLO HELLER BY (QM MEL/m ATTORNEYS June 23, 1959 1 HELLER 2,891,773

APPARATUS FOR FILLING AND EMPTYING AIR-COOLED CONDENSERS Filed Dec. 22, 1955 4 Sheets-Shae 4 INVENTOR. LASZLQ HELLER An ormeys United States Patent F APPARATUS FOR FILLING AND EMP'I'YING AIR-COOLED CONDENSERS Lfiszl Heller, Budapest, Hungary, assignor to Licencia Talalmanyokat Ertekesito Vallalat, Budapest, Hungary, :1 firm It is known in steam power plants to use mixing condensers in which the steam is precipitated by means of the condensate serving as cooling Water and to cool again the condensate, which has thereby been heated, in a closed system by means of the atmospheric air. With this object in view use is made as a rule of a closed cooling system consisting of thin-Walled tubes provided with cooling ribs in which tubes the cooling water is circulated, whereby cooling air flows between the tubes and the ribs sweeping the surfaces of the system to be cooled.

Since in such air condensers, comparatively very large amounts of heat have to be transmitted at a very small temperature difference and small ventilator work of the atmospheric air, this means heat exchange surfaces be tween the cooling water and the air which are of very large dimensions. In order to reduce these dimensions it is necessary to use heat exchangers of high specific capacity. The plant provided with air-cooled condensers of the kind referred to is often mounted at a place where the temperature of the atmospheric air sinks temporarily below zero during the year so that in the case of the said heat exchangers of great specific capacity there is a danger that the condensate will freeze. This danger is especially great if at the same time as the temperature of the outer air is low, owing to a disturbance, such as the removal of the turbine load or for other reasons, the heat supplied to the cooling surface is reduced and sinks below a predetermined value.

The flow of the condensation heat of the plant towards the heat exchangers may, due to some of the reasons above given, sink suddenly to a great extent or stop altogether, in which caseeven in spite of the stopping of the air ventilator or owing to the great specific capacity of the heat exchange surfaces-the cooling water may freeze in a very short time. In order to avoid this, the air condensation device must be so constructed, that all those parts thereof which are exposed to the danger of freezing as above explained may be emptied easily and quickly, preferably automatically in the case of large plants.

The conditions are similar if the plant, or a part thereof, has to be set into operation when the outer temperature is below freezing point. As long as the turbines do not run with a sufficient amount of steam no heat will flow to the heat exchange surface which would be suflicient to prevent freezing of the cooling water. On the other hand, it is not possible to produce the vacuum necessary for the starting of the turbine without a sufficient circulation of cooling water. Therefore suitably constructed apparatus for starting are necessary which will overcome the said difficulties.

The invention relates to an air condensating apparatus in which the exchange surfaces carrying the cooling water inside and being swept on the outside by the atmospheric air are prevented from freezing in the case of an outer temperature below the freezing point, when the amount of steam flowing through the steam turbines is reduced,

2,891,773 Patented June 23, 1959 or ceases altogether and also when the turbines are started.

The object of the invention is to prevent or reduce the freezing danger of the cooling Water by means of an arrangement which enables a rapid emptying of the water from all parts of the apparatus which is exposed to freezing.

With this object in view, according to the invention, the cooling apparatus of the air-cooled condenser, constituted by heat exchange elements, is provided with at least two vertical groups of tubes and with valves associated therewith, which enable two settings to be effected, in one of which, corresponding to the valve setting for the filling of the apparatus with cooling water, the latter, driving the air, flows in the same direction upwards in both groups of tubes, and in the other one corresponding to the valve setting for normal operation, the cooling water flows in opposite directions, that is to say, in the one group upwards and in the other group downwards.

Examples of construction of the apparatus according to the invention are illustrated in the accompanying drawings, in which- Figure l is a cross-section of an air-cooled condenser (cooling tower) according to the invention;

Figure 2 is a diagram of connections of a part of the heat exchanger of the condenser shown in Figure 1;

Figure 3 is a modification of the diagram of connections of the heat exchanger; and I Figure 4 is an apparatus for accelerating the removal of the air when the condenser is filled with cooling water.

The same references are shown in all the figures with respect to the same components.

It will be seen from the vertical section of the cooling tower shown in Figure 1', that the same consists of a base 1 on which rests the actual, preferably prismatic or cylindrical, cooler consisting of heat exchangers 2 built up of ribbed tubes. A column 3 is mounted in the centre to support a ventilator 4, which sucks the cooling air from the outside between the individual heat exchangers 2 in the direction of the arrows 5, pressing it in the direction of the arrows 6 into a difiusor 7. The heat exchangers 2 constitute the vertical outer walls of the cooling tower.

Figure 2 shows the diagram of connections of the condenser tubes. The same are so arranged that in case of need, that is to say when the outer temperature is below 0 C. and when the steam consumption of the turbine is too small, the tubular system can be rapidly emptied. Moreover, care has to be taken that the plant or a part thereof, can be put into operationsufiiciently quickly also when the outer temperature is too low, that is to say, that it can be filled with Water if the cooling plant has been previously emptied. Without circulation of the cooling water the required vacuum cannot be produced in order to start the turbines, so that also in this case certain difficulties have to be overcome to avoid the freezing of the cooling water.

The exhaust steam leaves the turbine through the exhaust pipe connector 8 and reaches into the mixing condenser 9, into which cooling water is sprayed through one or more nozzles 10. The precipitated condensate leaves the mixing condenser 9 through the pipe 11, whereupon a portion thereof is supplied through the pump 12,

and the pipe 24 to the steam boiler (not shown in the drawing) and the other part through the pipe 25 and pump 26 to a lower collecting chamber 27. In the above example of construction two pipe lines 28 ascend from the lower'right-hand side of the collecting chamber 27 to an upper collecting chamber 29. With the pump 26: running, the valve 14 being open and the

valves

16 and 17 being closed, the cooling water flows upwards in Q both pipe lines 28 forming a group, and it returns through pipe lines 36 forming a second group to the second collecting chamber 31 lying below, then flowing through the open valve 13 and the pipe 34 to the spraying nozzle of the mixing condenser 9.

If the plant is empty and has to be filled with water, this cannot take place in the manner that is usual for instance in central heating installations, in which the water circulates in a completely closed pipe system, whereby it is possible to fill the same from below, the air escaping at one or more very high points. In the apparatus according to the invention the pipe system, which is otherwise completely closed, is interrupted by the mixing condenser, so that a filling up is possible only through the pipe 25, namely by means of the pump 26. In the case of such filling, however, the cooling water may drag along with it the air that has collected in the collecting chamber 29, so that it reaches the pipe lines Where it disturbs the water circulation which, in normal operation, is directed downwards, causing the water to freeze in some of the pipes. it is therefore necessary to provide such a connection of the pipe lines that when the filling takes place the cooling water flows in all

pipe lines

28 and 30 upwards. Moreover, care has to be taken, that after the completion of the filling the connection of the pipe lines can be switched again to the normal operation, whereby the cooling water will again flow in the pipes 23 only upwards and in the pipes 343 only downwards. For this purpose, the valves 13 to 17 are provided which enable, in case of need, the mixing condenser 9 to be disconnected from the circulation of the cooling water.

For the filling of the system, which is efifected by means of the pump 26, the

valves

13, 15 and 17 are closed and the

valves

14, 16 and 18 are opened. By closing the

valves

13 and 17, the path of the cooling water from the pipe system to the mixing condenser 9 is closed, and likewise by closing the valve 15, the flow to the collecting vessel 21, which is used when the pipe system is being emptied, is interrupted. By opening the

valves

14 and 16 the flow from the pump 26 to all the pipe lines 28 and 311 is opened from below, and by opening the valve 18 the path for the removal of the air from the pipe system is freed. Thus, the cooling water ascends in all the pipe lines simultaneously upwards and presses the air in front of it through the valve 18 into the open. After the removal of the air, the valve 13 has to be opened and the

valves

16 and 18 have to be closed (the valve 14 remaining open and the

valves

15 and 17 remaining closed), whereby the normal working condition is attained. The cooling water flows in the pipe lines 28 upwards and in the pipe lines 30 downwards.

If the emptied plant has to be set into operation in cold weather, the whole of the amount of water that is to be supplied to the pipe system has to be correspondingly preheated before the heat exchangers are filled up and the water circulation is started. For this purpose, a separate pipe line 32 is provided in the arrangement according to Figure 2, through which steam can be supplied to the mixing condenser 9 from a suitable point through a valve 33. After the valve 33 has been opened, the pump 26 is started, the valve 17 is opened and the

valves

13 and 14 are closed. The water is drawn through the pump 26 and the pipe 11 from the mbring condenser and is pressed again into the mixing condenser through the pipe 25, valve 17, pipe 34 and nozzle 11). This circulation of the Water is continued until the water in the mixing condenser and in a storage container, which may be connected in parallel with the mixing condenser, has reached the desired temperature, whereupon the filling up of the pipe system of the cooling plant is effected in the manner described.

The emptying of the heat exchangers is effected by closing the valves 13 and 1 and opening the

valves

15, 16 and 18. The water then runs out of the pipe system of the heat exchangers through the valve 15 and the pipe 19 into the collecting container 21, whereby the air flows after it through the valve 18.

The construction shown in Figure 3 likewise shows an air condensation apparatus, which differs from the one in Figure 2 by that in all the pipe lines 35 of the heat exchangers, in normal operation, the cooling water flows in the same direction, that is to say, from below upwards. in this example of construction, a collecting chamber 37 common to all the pipe lines 35 is provided at the lower part of the heat exchanger. The upper collecting chamber 29 is connected through a pipe line 36 and the pipe line 34 with the nozzle 10 in the mixing condenser 9. in normal operation, the cooling water flows in the pipe line 36 downwards to the nozzle 10, through the open valve 13, whilst the

valves

16, 17 and 18 are closed. Moreover, for the purpose of setting for normal operation, and also for the filling up or emptying of the apparatus, the valves 13 to 18 are set as above described with reference to Figure 2.

Figure 4 shows a further form of construction in which during filling as well as during the operation, the removal of the air is accelerated or ensured.

During the filling of the apparatus, with the setting of the valves above described, the water will flow in the

pipe lines

37, 38 from below upwards and will press the air out of the apparatus through the open valve 18. Thereby, air accumulates in the upper collecting chamber 29. At the transition from filling to normal operation, the valve 13 is opened and the

valves

16 and 18 are closed, the valve 14 continuing to remain open and the

valves

15 and 17 closed. Cooling water then flows from the collecting chamber 27 in the pipe lines 37 upwards and in the pipe lines 33 downwards. The flow is maintained by the pump 26. During the operation, air may accumulate besides in the chamber 29 also in the chamber 31. Thereafter, such an apparatus has to be preferably freed of air continuously also during normal working.

These two problems, that is to say the rapid removal of air during filling and the continuous removal thereof during operation, are solved by the form of construction shown in Figure 4, by connecting, it possible, the highest points of the collecting chambers 2% and 31 with the vacuum space of the mixing condenser, through the

pipes

39, 4t and 41. Since, while filling the apparatus With cooling Water, a vacuum has already to be maintained in the mixing condenser 9, which is further increased after the starting of the turbine, the vacuum produces a flow in the

pipes

39, 4 3 and 41 from the collecting

chambers

29, 31 to the mixing condenser, whereby the air present in the said chambers is delivered into the vacuum space of the mixing condenser, from which the same is delivered into the open by the vacuum pump. After the removal of the air present in the pipe system, a continuous flow of cooling Water to the mixing condenser is started, whereby accumulation of further quantities in the collecting

chambers

29, 31 during working is prevented. in order to be able to adjust the amount of water flowing through the

pipes

39, 4t and 41 to a constant value, according to the invention, throttling

discs

42 and 43 are provided in the air discharge pipes 39 and 4.9. It is well known that such throttling discs allow a greater volume of air than of water to pass per unit of time. The water which is supplied to the mixing condenser via the pipe 41 may be used there for the condensation of the steam coming from the turbine. In this way, this amount of water constitutes only a comparatively small loss, since a portion of the amount of water that flows through the throttling disc is not as yet completely cooled.

A valve 44 is provided in the pipe 41. This valve has to be closed when the apparatus is being emptied so that no air can reach the mixing condenser which is under a vacuum.

As already mentioned above, the need may arise during operation for the pipe system to be completely or partly emptied. This may especially be the case in cold weather and when the conditions of operation are changing. If unexpectedly the apparatus fails in cold weather, then the whole of the pipe system has to be emptied as soon as possible. However, it may also be necessary to empty the pipe system only partly, for instance, in the case of full load and especially very cold weather, or in the case of partial loading and an outer temperature of only a few degrees below freezing point. In such cases the disconnection of a portion of the cooling surface prevents the dangerous cooling off of the cooling water. However, in this case one has to take care that the water is quickly discharged from the disconnected part of the pipe system.

In order that this operation may be carried out without fail, the valve 33 has been provided in the pipe 32 in the form of construction shown in Figure 2, through which valve steam is added directly to the mixing condenser, whereby it is ensured that the temperature of the cooling water behind the cooling elements cannot drop below a predetermined value.

The valve 33 may be operated by hand or automatically. A thermometer 45 is preferably provided in the pipe 34-, which, when the admissible lowest temperature is reached, gives, in a known manner, an optical or acoustic signal, whereupon the valve 33 is opened by the operating personnel. However, it is possible to derive, in a known manner, a pulse from the thermometer 45 by means of which the valve 33 is automatically operated. By opening the valve 33 and by artificially maintaining the desired temperature of the cooling water connected therewith, the personnel is enabled to disconnect a suitable number of cooling elements and empty the same. In the case of larger plants, the emptying itself may also be effected automatically, in which case the pulse transmitter 45 correspondingly operates, in addition to the valve 33, the other parts which participate in the emptying of the plant.

What I claim is:

1. An apparatus for filling and emptying and for normal operation of cooling towers of air condensers, comprising in combination a pipe system; heat exchangers incorporated in said pipe system, said heat exchangers having a first and a second vertical group of pipes; a pump for circulating the cooling water in said pipe system and for supplying cooling water to said pipe system for filling; a mixing condenser, which the water cooled in said heat exchangers is supplied to; a first and second lower collecting chamber and an upper collecting chamber, which said groups of pipes of said heat exchangers open into; first pipes for connecting the mixing condenser over said pump and over the first lower collecting chamber with said first group of vertical pipes, second pipes for connecting said second group of vertical pipes over the second of said lower collecting chambers with the mixing condenser and third pipes for emptying water from the pipe system; first valves arranged in said first pipes and second pipes for permitting in their open position circulation of cooling water in normal operation through said first group of vertical pipes in upward direction and said second group of vertical pipes in downward direction and through the mixing condenser; second valves arranged in the pipe system for disconnecting the mixing condenser from said circulation and preventing discharge of cooling water in their closed position, during filling; a third valve for permitting in its open position escape of air from the pipe system at the top of the vertical pipes; said apparatus being adapted to avoid freezing of the cooling water within the apparatus by the quick flow of water.

2. An apparatus as claimed in claim 1, comprising a separate pipeline for conveying air from the heat exchangers into the mixing condenser, from which the air is removed by said pump during normal operation.

3. An apparatus as claimed in claim 2, comprising an interconnecting pipe for continuous communication between the points of the collecting chambers for the collection of air, and the vacuum space of the mixing condenser.

4. An apparatus as claimed in claim 3, comprising throttle discs provided in each pipe branch of the interconnecting pipe.

5. An apparatus as claimed in claim 1, comprising additional valve means for supplying fresh steam to the condenser in order to maintain a predetermined temperature of the cooling water which is re-cooled.

6. An apparatus as claimed in claim 2, comprising additional valve means for supplying fresh steam to the condenser in order to maintain a predetermined temperature of the cooling water which is re-cooled.

7. An apparatus as claimed in claim 1, comprising an interconnecting pipe for continuous communication between the points of the collecting chambers for the collection of air, and the vacuum space of the mixing condenser and also comprising additional valve means for supplying fresh steam to the condenser in order to maintain a predetermined temperature of the cooling water which is re-cooled.

8. An apparatus as claimed in claim 5, comprising a pulse transmitter for automatically controlling the additional valve means in dependence on the temperature of the cooling water.

9. An apparatus as claimed in claim 1, comprising a separate pipeline for conveying air from the heat exchangers into the mixing condenser, from which the air is removed by said pump during normal operation, said apparatus also comprising additional valve means for supplying fresh steam to the condenser in order to maintain a predetermined temperature of the cooling water which is re-cooled and a pulse transmitter for automatically controlling the additional valve means in dependence on the temperature of the cooling water.

10. An apparatus as claimed in claim 1, comprising a separate pipeline for conveying air from the heat exchangers into the mixing condenser, from which the air is removed by said pump during normal operation; said apparatus also comprising an interconnecting pipe for continuous communication between the points of the collecting chambers for the collection of air, and the vacuum space of the mixing condenser; additional valve means for supplying fresh steam to the condenser in order to maintain a predetermined temperature of the cooling water which is re-cooled and a pulse transmitter for antomatically controlling the additional valve means in dependence on the temperature of the cooling water.

References Cited in the file of this patent UNITED STATES PATENTS 2,335,250 Adlam Nov. 30, 1943 2,356,404 Heller Aug. 22, 1944 2,360,900 Setterwall Oct. 24, 1944 2,808,234 Rosenblad Oct. 1, 1957