Device for the condensation of turbine steams in power stations

© Beginning of patent period: January 15, 1974 Longest possible duration:

© Issued on: 25.September 1974 © Inventor: Dipl.Ing. Georgy Sergejevits Agejev, Dipl.Ing. Ivan Alexeyevits

Alekszejev in Moscow, Dipl.Ing.Dr. Laszlo Heller,

Dipl.Ing.Dr. Laszlo Forgo and Dipl.Ing. Janos Bödas in Budapest © Dependence:

© Pamphlets considered to delineate the prior art:

OE 317 944

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The invention relates to a condensation device for steam turbines of power plants.

As is known, the lower the condensation temperature of the turbine, the higher the efficiency of a turbine

Turbine evaporation is. For cooling of capacitors, water or air is widely used. Water is taken from natural sources. The cooling water is either discharged after flowing through surface condensers of steam turbines or used repeatedly in circulation systems. In the latter case, the water is cooled in evaporative coolers (in cooling towers, trickling plants or in cooling ponds).

In the evaporative cooling means, a part of the cooled water is evaporated, while another part of it is entrained in the form of drops by the air flow. In addition, a portion of the water is usually drained, so that an excessive concentration of dissolved in the circulating water

Salt is avoided. To replace these losses, water from natural sources must be supplied to the cooling system.

In recent years, so-called air-condensation plants, in which the cooling liquid is recooled by ambient air, gained more and more ground. Systems of this type contain a mixed condenser into which the condensate is injected, which has previously been cooled in air in surface heat exchangers. The surface heat exchangers are installed in cooling towers with natural draft or with fans (fans). The cost of air-condensing systems is higher than the cost of a water-cooled system. This also means that at high ambient temperatures no suitable efficiencies of the turbines can be secured. The fact that they are still being used more and more is due to the lack of water in many parts of the world.

However, it should also be mentioned that at low air temperatures the air condensation plants produce extremely high turbine efficiencies.

Lack of water occurs in certain years and in certain seasons with little precipitation and can become critical, with annual or seasonal fluctuations in running water volumes being determinative of the lack of water.

For example, the amount of water observed in rivers at medium latitudes in winter skyrockets in the spring and maintains a fairly high level during the summer. The reservoirs are thus filled in the spring and during the summer and usually taken little use. In the hot seasons, the rivers carry water that came from the snow in the high mountains. In northern areas, numerous rivers freeze completely in winter, with the most powerful rivers providing a minimum amount of water, whereas in summer they are extremely swollen. In such cases, it is economically advantageous to recool the condensate in the winter by air, where the cold air makes it possible to maintain a high turbine efficiency, while in the summer the available water is used for cooling the condensers in addition to the air. In the low water years, where the available amount of water is particularly low, it seems to be economically advantageous, a small

To permit decrease of the turbine efficiency and to make use of the water only in those hours in which the power plant has to deliver maximum power and the temperature of the air is high.

Condensation systems are known in which an air-condensation plant and a water circulation system with a cooling tower are combined with one another.

For example, an arrangement is known in which a part of the steam escaping from the turbines is supplied via pipelines to surface heat exchangers which are cooled by air. Another part of the exhaust steam passes into surface condensers below the turbines. In the tubes of the surface condensers water is circulated, which is cooled by a trickle system by contact air. The surface condensers for cooling the steam and the trickling unit for cooling the circulating water are arranged among each other in the air supply port of a natural draft cooling tower.

It is also known to use a combined condenser which operates partly with injected condensate but is also equipped with tubes in which circulated cooling water flows. The condensate is cooled in surface heat exchangers and the recirculated water in contact steam generators superimposed in the air supply port of a natural draft cooling tower as in the embodiment just described.

Finally, an arrangement is known in which a surface condenser is associated with a cooling tower, in the air supply opening surface heat exchanger and Kontaktrieselkühlanlagen are arranged one above the other. The water circulated through the surface condenser is first passed through the surface heat exchangers and then through the open trickle coolers.

The combined systems cited require the use of surface capacitors, which must be made of costly corrosion resistant materials because of the circulation in them

Water contains various salts and oxygen. There is also the risk that the condensate over

Sealing points in the adjustments between pipes and connections is contaminated, which can have serious consequences. This also means that the space requirement of surface capacitors is very large, which then also the dimensions of the engine room in the power plant are correspondingly larger.

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Of the four combined systems described above, at least four pipelines must be installed between the condenser and the cooling tower for the first two. Two of them are used for supplying and discharging the cooling water. The other two are destined to carry the steam or the condensate. The pipes for supplying the steam into the heat exchangers are very large, the pressure in them being lower than the atmospheric pressure, so that the risk of contamination of the condensate also increases considerably.

The feed ports of the combined cooling tower are equipped with cumbersome facilities that regulate the amounts of air flowing to the cooling tower via the surface heat exchangers and the contact pellet cooling systems.

The dimensions of natural draft cooling towers or the performance of fans mounted in cooling towers (fans) must be significantly greater than conventional evaporative cooling towers because very large volumes of air are required for convective cooling of the surface heat exchangers, except for the amounts of air therefor serve to extract the heat by convection and evaporation from the Kontaktrieselkühlanlage.

The invention aims to eliminate these shortcomings, wherein in a conventional manner also provided a mixing condenser for the turbine and the condensate is cooled by means of air-cooled surface heat exchanger. Contrary to the known air-condensation plants but after the air-driven cooler for the condensate or in parallel a water-operated condensate cooler is installed, which consists of a surface heat exchanger, in whose pipes the cooling water flows, while out of the pipes, the condensate to be cooled is performed. The water-operated condensate cooler can be arranged, for example, inside a cooling tower with natural draft.

The dimensions of the air-cooled condensate cooler or the heat exchanger and the air feed systems are suitably chosen so that at maximum load of the power plant in winter suitable low condensation temperatures are ensured without having to perform cooling water to the water-cooled radiator of the condensate. Since at air temperatures below freezing point very large differences between the temperatures of the condensate and the air can be allowed without the efficiency of the turbine would decrease (the difference can be in the range of 35 to 45 ° C), are the appropriate dimensions of the air-driven Condensate cooler significantly lower than in the known air condensation systems, which are usually measured at the annual mean temperature of the air.

Cooling water is only supplied to the water-operated condensate cooler when the air temperature is so high that the air-driven condensate cooler is unable to ensure a suitably low temperature for condensing the exhaust steam escaping from the turbine. Water does not have to be used for cooling even if at air temperatures above freezing the power plant is not operated at full load, such as during the night or on days off.

The flowing amount of the cooling water is automatically controlled depending on the temperature of the condensate or the pressure prevailing in the condenser of the turbine pressure.

In this way, the condensation device according to the invention allows to maintain a high efficiency of the turbine constantly while consuming only a minimum amount of cooling water, in which the supply of the cooling water is regulated depending on the weather conditions and the load of the power plant.

Cooling water can be taken from external sources such as rivers, ponds and canals. If these sources are not able to supply suitable amounts of cooling water even in summer, an evaporation water cooling device (cooling tower, trickle bed or cooling pond) is provided according to the invention. In this case, the supply of cooling water in the water-cooled condenser of the condensate is also controlled according to the condensation temperature of the steam, depending on the weather conditions and the load of the power plant, with the aim of avoiding water losses in the evaporative cooling system and to ensure suitably high efficiencies of the turbine ,

The contact steam generator or evaporator water cooler and the surface heat exchanger of the condensate air cooler are installed in a natural draft cooling tower, reducing both cost and space requirements. When arranging the heat exchangers for cooling the condensate and the trickle of Kontaktrieselanlage or the evaporative cooler in a row, the water capacity of the air is fully utilized and reduced air consumption, so that the dimensions of the cooling tower with natural draft or the performance of chandeliers (fans) are smaller.

Further details of the invention will be explained with reference to the drawings, whose Fig.l to 5 represent the circuit diagrams of various embodiments of the condensation device according to the invention.

In the drawings, like reference numerals indicate similar details.

Fig.l represents an embodiment of the condensation device according to the invention, in which the

Cooling water is taken from an external source -8-, wherein the air and water-powered radiator of

Condensate are connected in series. The steam passes from a turbine -1- into a mixing condenser - 4 -

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--2--. To condense the exhaust steam of the turbine, cooled condensate is injected into the mixing condenser -2. The heated condensate is conveyed by a pump - 3 in the heat exchangers -4-, which are cooled by air, as indicated by curved arrows. From the heat exchangers -4- the condensate enters the heat exchanger -6-, which is provided by means of a pump -7- from the external source -8- with cooling water. The flow rate is controlled by a closure member -10-. The cooled condensate returns from the heat exchangers -6- via a condensate line -9- back into the mixing condenser -2-.

2 shows an embodiment of the condensation device according to the invention, in which the luftbzw. water-cooled condenser of the condensate are arranged in parallel. Here, a portion of the condensate from the mixing condenser -2- flows through the heat exchanger -4-, which is cooled by air. The other part of the condensate flows through the water-cooled heat exchanger -6-. The distribution of the various coolers inflowing condensate is effected by control elements, not shown.

FIG. 3 shows an exemplary embodiment of the condensation device according to the invention, in which the cooling water for the water-operated heat exchanger -6- in a cooling tower -12- is recooled. The cooled in the cooling tower -12- water is fed by the circulation pump -7- in the water-driven surface heat exchanger -6-, from which the cooling water in the direction of the arrows to the cooling tower -12- returns.

The loss of water arising in the cooling tower as a result of evaporation and entrainment of water particles through the air, as well as by draining the water to prevent an undue increase in the concentration of dissolved salt in the water, is replaced by an external source of water, not shown.

In the illustrated embodiment, a cooling tower -12- has been shown with natural draft. However, it is easy to see that even cooling towers with fans (fans), trickle water tanks or cooling ponds could be used.

The embodiment of Figure 4 differs from the previous one in that the Kontaktrieselanlage -13- the water-driven heat exchanger -6- together with the air-driven

Heat exchanger -4 - for the condensate in the air inlet opening of the cooling tower - 5 - with natural

Train is attached, wherein the air-driven heat exchanger -4- above the Rieselanlage -13- is arranged. The distribution of the air flow between the heat exchangers -4, 6- and the Rieselanlagen -13- by means of control valves -11,

If the amount of water supplied to the trickle plant increases, the amount of air flowing through the trickle bed is also increased, while the flow of air is also interrupted when adjusting the supply of water to the trickle bed.

The example embodiment of the condensation device according to the invention according to Figure 5 shows how the Kontaktrieselanlage -13- of the water-driven heat exchanger -6- with evaporation in

Direction of air flow behind the air-driven heat exchanger -4 - can be attached to the condensate. In such an embodiment, a control of the amount of air can be omitted.