Condensing steam turbine plant, and methods for operating such a condensing steam turbine plant

Abstract

The invention relates to a condensing steam turbine plant (1) comprising at least one steam turbine (2), a water-cooled condenser (3) which can be connected to the exhaust steam of the steam turbine (2), and a further heat condenser (4) which can be connected to the exhaust steam of the steam turbine (2). The heat condenser (4) is arranged on the steam side parallel to the water-cooled condenser (3), wherein the water-cooled condenser (3) has an accumulation control means (5) for the condensate, by which the available heat exchanger surface area (6) of the water-cooled condenser (3) can be adapted via the water level of the condensate in the water-cooled condenser (3). Furthermore, the invention relates to methods for operating a condensing steam turbine plant (1) of this type.

Description

[0001] Description

[0002] Condensation steam turbine plant and method for operating such a steam turbine plant

[0003] The invention relates to a condensing steam turbine plant, hereinafter also referred to as steam turbine plant for the sake of simplicity, according to the preamble of independent patent claim 1, and to methods for operating such a steam turbine plant according to independent patent claims 3 and 4.

[0004] To increase the overall efficiency of a steam turbine plant, steam turbine plants often have, in addition to the water-cooled condenser for condensing the exhaust steam, one (or more) heating condensers, through which the waste heat from the steam can be used for heating purposes. A typical application is the feed of heat into a district heating / heating network. The steam turbine plant should be able to meet the flexible demand of the district heating / heating network year-round and / or alternatively, divert the exhaust steam to the water-cooled condenser.

[0005] In general, two variants for heat generation using a heating condenser have become established on the market:

[0006] If an existing plant is designed for pure condensation, the waste heat from the exhaust steam cannot generally be utilized and is released into the environment via the cooling water. The heating condensers are supplied with steam via intermediate steam extraction at the turbine, and the energy is transferred to the district heating network.

[0007] If an existing system is designed as a backpressure system, the waste heat can only be used if the district heating network can absorb the heat. If no other heat consumers are integrated, the system must be shut down and electricity production is therefore also eliminated. In order to achieve greater flexibility, isolated solutions with parallel operation of the condenser and heating condenser were implemented in the past, but as an "EITHER-OR" solution. Many operators decided to switch from pure condensation operation to pure heating condensation operation once a certain requirement of the heating network was reached. However, this assumes that the heat-consuming system (e.g. district heating network) can also absorb the heat. Furthermore, the steam turbine must be shut down and then started up again after the switchover process.

[0008] Another possible, partially flexible solution is to throttle the exhaust steam mass flow to the water-cooled condenser using a control device (control flap or control valve). The disadvantages of this solution are the increased space requirement and the use of additional, cost-intensive fittings, which are often limited in flexibility by the controllable range (e.g., minimum opening angle for flaps, etc.). In pure condensation operation, the system efficiency is reduced due to the increased pressure loss in the exhaust steam section.

[0009] An object of the present invention is therefore to provide a steam turbine plant in which waste heat can be dissipated flexibly and continuously either to the water-cooled condenser (cooling medium: cooling water) or to the heating condenser (cooling medium: heating water).

[0010] A further object of the invention is to provide methods for operating such a steam turbine plant .

[0011] The problem is solved with regard to the steam turbine system by the features of independent patent claim 1 and with regard to the methods by the features of independent patent claims 3 and 4.

[0012] Further advantages and embodiments of the invention, which can be used individually or in combination with one another, are the subject of the dependent claims. The condensing steam turbine plant according to the invention comprising at least one steam turbine, a water-cooled condenser which can be connected to the exhaust steam of the steam turbine and a further heating condenser which can be connected to the exhaust steam of the steam turbine, is characterized in that the heating condenser is arranged on the steam side parallel to the water-cooled condenser and the water-cooled condenser has a build-up control for the condensate, by means of which the available heat exchanger surface of the water-cooled condenser can be adapted via the water level of the condensate in the water-cooled condenser.

[0013] The exhaust steam from the steam turbine is connected to both the water-cooled condenser and the heating condenser via an exhaust steam duct and / or piping into a common pressure chamber (without shutoff). By accumulating the condensate in the water-cooled condenser, the heating surface of the water-cooled condenser can be reduced, thus increasing the exhaust steam pressure. This allows the amount of exhaust steam flowing to the heating condenser to be flexibly and continuously controlled.

[0014] The heat exchangers must be designed / constructed for this type of "accumulation control" or, in the case of existing systems, may need to be adapted. The variable weight (condenser + accumulating condensate) caused by the accumulating pressure must also be taken into account in the installation concept and the static and dynamic calculations. The basic prerequisite for such a concept is that the turbine can cover the required exhaust steam pressure ranges. This may require a modification of the turbine end blading.

[0015] One embodiment of the invention provides that the heating condenser interacts with a district heating network and can transfer heat from the exhaust steam to the district heating network. This enables the steam turbine plant to meet the flexible needs of a district heating network all year round, resulting in a particularly high overall utilization rate of the steam turbine plant. A method according to the invention for operating a steam turbine plant according to claim 1 or 2 is characterized in that the amount of heat supplied to the heating condenser is regulated via the accumulation control by increasing the water level in the water-cooled condenser by accumulating the condensate, whereby the heat exchanger surface of the water-cooled condenser is reduced, which leads to an increased exhaust steam pressure and thus increases the amount of exhaust steam to the heating condenser. This makes it possible, for example, to accommodate an increased heat demand of a connected district heating network.

[0016] A further method according to the invention for operating a steam turbine system according to claim 1 or 2 is characterized in that the amount of heat supplied to the heating condenser is regulated via the accumulation control by reducing the water level in the water-cooled condenser, thereby increasing the heat exchanger surface of the water-cooled condenser, which leads to a reduced exhaust steam pressure, thereby reducing the amount of exhaust steam supplied to the heating condenser. This allows the amount of heat made available to the district heating network to be reduced.

[0017] Both processes enable simple, flexible and yet stepless control of the amount of heat that is made available to the water-cooled condenser and / or the heating generator.

[0018] Further advantages of the invention are explained below using an exemplary embodiment.

[0019] Fig. 1 shows only a schematic and not to scale representation of a steam turbine plant according to the invention, in which essentially only the components necessary for explaining the invention are shown.

[0020] The steam turbine system 1 comprises a steam turbine 2, as well as a water-cooled condenser 3 and a heating condenser 4. The water-cooled condenser 3 and the heating condenser 4 are connected to the steam outlet of the steam turbine 2 via a common exhaust steam line 9, the exhaust steam line 9 forming a common pressure chamber (without shut-off devices). The water-cooled condenser 3 comprises a backup control 5 for the condensate that accumulates in the water-cooled condenser 3. By backing up the condensate, the available heat exchanger surface 6 of the water-cooled condenser 3 can be continuously varied. The accumulation control 5 comprises a drain control valve 5 ' and a level measurement 5 "' which is operatively connected to the drain control valve 5 '. The condensate which has not accumulated is pumped out by means of a pump 10 and fed back into the water-steam circuit of the steam turbine system 1.

[0021] The amount of heat supplied to the heating condenser 4 is controlled by the accumulation control 5. For this purpose, the water level in the water-cooled condenser 3 is changed by accumulating the condensate, thereby changing the heat exchanger surface 6 of the water-cooled condenser 3, which leads to a changed exhaust steam pressure, allowing the amount of exhaust steam to the heating condenser to be continuously controlled.

[0022] In the exemplary embodiment, the heating condenser 4 interacts with a district heating network 7 and can transfer thermal energy from the exhaust steam to the district heating network 7. Depending on the amount of heat required, more or less exhaust steam is fed to the heating condenser 4. If, in summer operation, only a small amount of heat is required from the district heating network 7, the accumulation control 5 is operated in such a way that the water level 8 in the water-cooled condenser 3 only reaches a low water level. If there is no heat requirement at all from the district heating network 7, the condensate can also be completely drained from the water-cooled condenser 3. In both cases, a large heat exchanger surface 6 is available within the water-cooled condenser 3, so that a large amount of exhaust steam condenses in the water-cooled condenser 3. This greatly reduces the exhaust steam pressure and no or very little water flows. only a very small amount of exhaust steam to the heating condenser.If, however, a larger amount of heat is required by the district heating network during winter operation, the water-cooled condenser 3 can be flooded with a larger amount of condensate by means of the accumulation control, thereby reducing the effective heat exchanger surface 6. This increases the exhaust steam pressure, and a correspondingly larger amount of exhaust steam is directed to the heating condenser 4.

[0023] The accumulation control 5 enables for the first time a continuous, demand-based control of the exhaust steam. It is a flexible parallel operation and / or individual operation of water-cooled

[0024] Condenser 3 and heating condenser 4 are possible without having to shut down the steam turbine plant 1.

Claims

Patent claims 1. Condensation steam turbine plant (1) comprising at least one steam turbine (2), a water-cooled condenser (3) connectable to the exhaust steam of the steam turbine (2), and a further heating condenser (4) connectable to the exhaust steam of the steam turbine (2), characterized in that the heating condenser (4) is arranged on the steam side parallel to the water-cooled condenser (3) and the water-cooled condenser (3) has a build-up control (5) for the condensate, by means of which the available heat exchanger surface (6) of the water-cooled condenser (3) can be adjusted via the water level of the condensate in the water-cooled condenser (3).

2. Condensation steam turbine plant according to claim 1, characterized in that the heating condenser (4) interacts with a district heating network (7) and can transfer heat of the exhaust steam to the district heating network (7).

3. Method for operating a condensing steam turbine plant (1) according to claim 1 or 2, characterized in that the amount of heat supplied to the heating condenser (4) is regulated by increasing the water level (8) in the water-cooled condenser (3) by accumulating the condensate, whereby the heat exchanger surface (6) of the water-cooled condenser (3) is reduced, which leads to an increased exhaust steam pressure, whereby the amount of exhaust steam to the heating condenser (4) is increased.

4. Method for operating a condensing steam turbine plant (1) according to claim 1 or 2, characterized in that the amount of heat supplied to the heating condenser (4) is regulated by the water level (8) in the water-cooled Condenser (3) is reduced, whereby the heat exchanger surface (6) of the water-cooled condenser (3) is increased, which leads to a reduced exhaust steam pressure, whereby the amount of exhaust steam to the heating condenser (4) is reduced.

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