DE102018209203B4 - Low pressure steam turbine plant and operating method for a low pressure steam turbine plant - Google Patents

Abstract

Low-pressure steam turbine system (10) comprising a flash evaporator (12) for evaporating liquid heat transfer medium (14) so that vaporous fluid is obtained, the pressure in the flash evaporator (12) being below the ambient pressure, - a steam turbine (18), - one Supply line (16), which fluidically connects the flash evaporator (12) to the steam turbine (18), - a generator (20), which is coupled to the steam turbine (18), - a condenser (26) for condensing the in operation of the vapor turbine (18) leaving vaporous fluid, so that liquid heat transfer medium (14) is obtained, the pressure in the condenser (26) being below the ambient pressure, - a discharge line (28) which fluidly connects the steam turbine (18) with the condenser ( 26), characterized in that the low-pressure steam turbine system (10) further comprises: - power electronics (22) for connecting the generator (20) to a consumer and / or an S power supply, - a vacuum breaker (38) which is arranged downstream of a turbine wheel (50) of the steam turbine (18), and - a control unit (24) which is set up to control the electrical load on the generator (20) from the power electronics (22 ) and to open the vacuum breaker (38), and that the generator (20) is arranged upstream of the steam turbine (18) within the feed line (16).

Description

The invention relates to a low-pressure steam turbine system and an operating method for a low-pressure steam turbine system.

A low pressure steam turbine plant according to the preamble of claim 1 is from DE 10 2012 024 526 A1 known. Also disclosed DE 10 2012 024 526 A1 an operating method for such a low-pressure steam turbine plant, wherein a line system is evacuated so that the pressure in the line system is everywhere below the ambient pressure and so that heat transfer medium evaporates in a flash evaporator.

Steam turbine systems are used to convert thermal energy into electrical energy. For this purpose, steam flows through a steam turbine. The steam turbine converts the thermal energy of the steam into mechanical energy. The steam turbine drives a generator. The generator converts mechanical energy from the steam turbine into electrical energy.

Large steam turbine plants with outputs of some ten to one hundred megawatts work in the overpressure range. I.e. the steam has a high pressure of about 200 to 300 bar when it enters the turbine. Large-scale combustion plants are used to generate steam.

Constant fresh steam parameters are aimed for. In terms of control technology, pressure and temperature fluctuations are kept to a minimum in order to protect thick-walled components such as valve boxes and turbine housings. For this purpose, the steam turbine is often operated in the so-called pre-pressure control. The mass flow rate through the steam turbine is varied via at least one control valve in such a way that the fresh steam pressure upstream of the turbine corresponds to a constant setpoint.

This mode of operation keeps the isentropic enthalpy gradient between live steam and exhaust steam largely constant. At least one control valve is either located in front of the turbine or is integrated into it. The control intervention of the at least one valve inevitably results in throttling losses which have a negative effect on the efficiency. Large power plant turbo sets are operated at a constant speed. As a result, the efficiency of the turbine drops quickly at part load.

The publication "Gearless steam turbine", VGB PowerTech 4/2008, pp. 75-80, describes a control concept for a so-called steam turbine with an output of around 500 kW. The steam turbine was driven by superheated live steam at a pressure of 16.8 to 17.6 bar at 210 ° C to 235 ° C. A pressure of 1.5 to 4.5 bar prevailed on the exhaust side. The machine speed was decoupled from the electrical network by means of a frequency converter. Theoretical and experimental investigations were carried out at which speed the turbine and the overall system achieve their highest efficiency if the power is specified.

DE 25 50 059 A1 describes a safety system for a steam turbine plant in which at least one shut-off device is provided upstream of the turbine and at least one vacuum breaker valve is provided downstream of the turbine, both of which are controlled by a control and safety device, the former, for example, on the basis of a speed controller signal, the latter, for example, on the basis of an overspeed Guardian -S ignals.

From the DE 10 2012 024 526 A1 a solar thermal heat storage power plant has become known. In solar collectors, the solar radiation heats a medium of a primary circuit, from where it reaches heat storage. The heat transfer medium of the secondary circuit is supplied to steam generators via a secondary circuit. At least one of the steam generators is designed as a flash evaporator with an absolute pressure of less than 1 bar. A vacuum pump is provided on a condenser to extract non-condensable gases.

Object of the invention

The invention has for its object to provide a steam turbine system that is simple in construction and that can be operated safely over a wide range of operating parameters. The invention is also based on the object of specifying a method for the safe operation of a steam turbine system with different operating parameters.

Brief description of the invention

This object is achieved by a low-pressure steam turbine plant according to claim 1 and an operating method according to claim 11. The subclaims indicate advantageous embodiments.

Low-pressure steam turbine systems according to the invention

According to the invention, a low-pressure steam turbine plant is provided. In the context of the present invention, a low-pressure steam turbine system is understood to mean a steam turbine system in which a steam-side system pressure in operation is below the ambient pressure, ie below 1 bar. The low-pressure steam turbine system according to the invention has a flash evaporator. The flash evaporator is used to evaporate liquid heat transfer medium, so that vaporous fluid is obtained, the pressure in the flash evaporator being below the ambient pressure. When the low-pressure steam turbine system is operating, the pressure in the flash evaporator is below the ambient pressure, ie below 1 bar. By lowering the pressure, liquid heat transfer medium, for example water, can be evaporated at a lower temperature than at ambient pressure. This opens up an area of application for comparatively low heating outputs, for example in the field of solar thermal energy or the use of waste heat from industrial processes. The liquid heat transfer medium is the same substance as the vaporous fluid; this substance is present as a heat transfer medium in the liquid state and as a fluid in vapor form, ie in the gaseous state.

The low-pressure steam turbine system also has a steam turbine. A supply line to the low-pressure steam turbine system fluidly connects the flash evaporator to the steam turbine. The vaporous fluid generated in the flash evaporator can be supplied to the steam turbine via the feed line. The steam turbine converts thermal energy of the steam (vaporous fluid) into mechanical energy. The low-pressure steam turbine system also has a generator which is coupled to the steam turbine. The generator converts mechanical energy provided by the steam turbine into electrical energy. The low-pressure steam turbine system also has power electronics. The power electronics are used to connect the generator to a consumer and / or a power network.

The low-pressure steam turbine system also has a condenser. The condenser serves to condense the vaporous fluid emerging from the steam turbine during operation, so that liquid heat transfer medium is obtained, the pressure in the condenser being below the ambient pressure. The fluid expanded in the steam turbine is condensed during operation of the low-pressure steam turbine system at a pressure which is still below the pressure in the flash evaporator. A derivative of the low-pressure steam turbine system fluidly connects the steam turbine to the condenser.

The low-pressure steam turbine system has a vacuum breaker, which is arranged downstream of a turbine wheel of the steam turbine. The vacuum breaker can be arranged on the condenser or on the discharge line or on the steam turbine downstream of the turbine wheel. When the vacuum breaker is open, ambient air can flow into the low-pressure steam turbine system downstream of the turbine wheel. As a result, the steam turbine can be braked or stopped.

Finally, the low-pressure steam turbine system has a control unit which is set up to change the electrical load on the generator by the power electronics and to open the vacuum breaker. The power electronics preferably comprise a feed converter, i.e. a combination of rectifier and inverter. Changing the load on the generator allows the low-pressure steam turbine system to be adapted to different operating states. In particular, the control unit can be set up to set the load in such a way that the speed of the steam turbine assumes a target value for the present operating state. In this way, the range of operating conditions within which the low pressure steam turbine plant is efficient, i.e. in particular can be operated with a high efficiency of the steam turbine. The operating state can in particular comprise one or more of the variables pressure in the supply line, pressure in the supply line, temperature of the vaporous fluid in the supply line and / or in the flash evaporator, temperature of the vaporous fluid in the discharge line and / or in the condenser. Alternatively or additionally, the operating state may include the enthalpy of the fluid in the feed line and / or enthalpy of the fluid in the discharge line.

Since the steam-side system pressure is always below the ambient pressure, the low-pressure steam turbine system according to the invention is inherently safe. An escape of vaporous fluid is not possible due to the negative pressure relative to the environment. Therefore, the use of safety devices in front of or on the steam turbine can be completely dispensed with. In addition, the control device allows operation in a so-called heat-guided sliding pressure mode, ie the pressure upstream of the turbine wheel of the steam turbine is variable. Due to the variable load on the generator in connection with the variable speed of the steam turbine, there is no need for regulating elements in front of or on the steam turbine. The low-pressure steam turbine system preferably has no organs upstream of the turbine wheel for influencing a volume flow or mass flow of the steam. As a result, the low-pressure steam turbine system can be constructed in a particularly simple manner. In particular, the low-pressure steam turbine system has no quick-closing flaps or quick-closing valves and no regulating flaps or regulating valves. Pressure losses in front of the steam turbine are avoided by not using safety and control elements reduced to a minimum, which has a positive effect on the system efficiency.

According to the invention it is provided that the generator is arranged upstream of the steam turbine within the feed line. The generator is then automatically cooled by the steam driving the steam turbine and without additional devices.

The low-pressure steam turbine system according to the invention is preferably operated using an operating method according to the invention described below. The control unit is preferably designed to carry out the corresponding method steps and / or to control the operating method accordingly.

The turbine wheel of the steam turbine and a rotor of the generator are preferably arranged on a common shaft. This allows a compact and simple construction of the low-pressure steam turbine system. The low-pressure steam turbine system can have a first bearing point for the shaft between the rotor and the turbine wheel and a second bearing point for the shaft beyond the rotor. Preferably no further storage location is provided. The turbine wheel is therefore overhung.

The low-pressure steam turbine system can furthermore have an evacuation device. By means of the evacuation device, a pressure in the flash evaporator, the steam turbine, the condenser, the supply line and the discharge line can be reduced below the ambient pressure. In particular, the pressure in the flash evaporator can be reduced below the boiling pressure of the liquid heat transfer medium. This enables the low-pressure steam turbine system to be started up. The evacuation device preferably has a vacuum pump. The evacuation device is particularly preferably arranged on the condenser.

The low-pressure steam turbine system preferably also has a braking resistor. The control unit is typically set up to convert electrical energy from the generator in the braking resistor into heat when an operating state of the low-pressure steam turbine system is outside an allowable range. The control unit can in particular be set up to conduct electrical energy from the generator into the braking resistor in the event of an emergency shutdown or when the maximum permissible system output has been reached. The heat generated in this way is preferably introduced back into a heat store.

The low-pressure steam turbine system can furthermore have a feed pump in order to convey liquid heat transfer medium into the flash evaporator, the control unit being designed to change a delivery capacity of the feed pump. The thermal energy that is available to the steam turbine or the power that can be converted in the steam turbine can be changed by varying the delivery rate. The speed of the steam turbine can also be changed in this way. The feed pump can be switched off to switch off the low-pressure steam turbine system. The delivery rate can be a volume flow.

It is particularly preferably provided that a map is stored in the control unit, which maps an operating state of the low-pressure steam turbine system to a setpoint value of a speed of the steam turbine. The operating state can comprise one or more of the variables pressure in the supply line, pressure in the supply line, temperature of the vaporous fluid in the supply line and / or in the flash evaporator, temperature of the vaporous fluid in the discharge line and / or in the condenser. Alternatively or additionally, the operating state may include the enthalpy of the fluid in the feed line and / or enthalpy of the fluid in the discharge line. The control unit is typically set up to regulate the speed of the steam turbine to the desired value. For this purpose, the control unit can vary the load on the generator, conduct electrical energy into a braking resistor and / or temporarily open the vacuum breaker. As a result of the setpoints stored in the map, the greatest possible efficiency of the low-pressure steam turbine system, in particular the steam turbine, can be achieved for a wide range of operating states.

The low-pressure steam turbine system can furthermore have a feedback device in order to return liquid heat transfer medium from the condenser to the flash evaporator. This enables a cycle to be set up. The feedback device typically has a condensate pump which pumps the condensed heat transfer medium into a heat store and / or a heating device, e.g. promotes a solar thermal heat generator. From there, the heat transfer medium is conveyed back into the flash evaporator, for example by means of a flow pump.

A stator of the generator is preferably arranged in an inner housing. The inner housing is preferably arranged within the feed line. The inner housing surrounds the stator in the circumferential direction, in particular in a ring shape. The inner housing is preferably supported on the feed line. Typically, the rotor is also arranged within the inner housing, in particular inside the stator. The inner housing can have cooling fins on the outside. As a result, improved heat transfer to the flowing fluid and stronger cooling of the generator can be achieved.

The low-pressure steam turbine system preferably furthermore has a heat store and / or a solar thermal heat generator. This enables the provision of preheated heat transfer medium. As a result, the thermal energy of the evaporated heat transfer medium, i.e. of the vaporous fluid increased.

Operating method according to the invention

• - einen Entspannungsverdampfer,
• - eine Dampfturbine,
• - einen Kondensator,
• - einen Generator, der von der Dampfturbine angetrieben wird,
• - ein Leitungssystem, das den Entspannungsverdampfer über eine Zuleitung, die Dampfturbine und eine Ableitung mit dem Kondensator verbindet, und
• - einen Vakuumbrecher, der stromabwärts eines Turbinenrades der Dampfturbine angeordnet ist.

According to the invention, an operating method for a low-pressure steam turbine plant is provided. The low pressure steam turbine system has the following:

• - a flash evaporator,
• - a steam turbine,
• - a capacitor,
• a generator which is driven by the steam turbine,
• a line system which connects the flash evaporator via a feed line, the steam turbine and a discharge line to the condenser, and
• - A vacuum breaker, which is arranged downstream of a turbine wheel of the steam turbine.

1. a) Evakuieren des Leitungssystems, sodass der Druck in dem Leitungssystem überall unter dem Umgebungsdruck liegt und sodass Wärmeträgermedium in dem Entspannungsverdampfer verdampft,
2. b) Verändern der elektrischen Belastung des Generators,
3. c) Öffnen des Vakuumbrechers.

The operating procedure has the following steps:

1. a) evacuating the line system so that the pressure in the line system is everywhere below the ambient pressure and so that the heat transfer medium evaporates in the flash evaporator,
2. b) changing the electrical load on the generator,
3. c) Open the vacuum breaker.

With the help of step a), the low-pressure steam turbine system can be put into operation. To start up the low-pressure steam turbine system, the internal system pressure is lowered below the ambient pressure, preferably via an evacuation device. In this way, non-condensable substances, such as gases (air), are removed from the system. The system pressure is reduced until the heat transfer medium reaches the vapor pressure according to its temperature, begins to boil and saturated steam is generated in the flash evaporator.

Steps b) and c) can be used to control and / or terminate the operation of the low-pressure steam turbine system.

In step b), the speed of the steam turbine and the generator coupled to it can be adapted to the available isentropic enthalpy gradient. The speed is adjusted by loading or unloading the generator via the power electronics, which is connected downstream of the generator. As a result, the speed can be subject to variable boundary conditions (operating states) such as by a drop in temperature in a heat accumulator, caused by the daily sunlight and / or by a change in pressure in the condenser.

The vacuum breaker is typically the only mechanical safety device in the low-pressure steam turbine system. If the load on the generator cannot be increased further, for example because the control range of power electronics has been exhausted and the speed continues to increase or a maximum permissible system output has been reached, the vacuum breaker is opened in step c). As a result, ambient air flows into the line system of the low-pressure steam turbine system. The air that flows in cannot be condensed in the condenser. This increases the pressure downstream of the turbine wheel and the isentropic enthalpy gradient available to the steam turbine becomes smaller. As a result, the speed of the steam turbine and the generator coupled to it decrease until the entire process comes to a standstill. The isentropic enthalpy gradient can be reduced in a dosed manner by briefly opening the vacuum breaker, so that the speed of the steam turbine is reduced, but the process does not come to a standstill, but continues to run with reduced power.

According to the invention, it is provided that the vacuum breaker is opened at the same time, a volume flow of liquid heat transfer medium flowing into the expansion evaporator is reduced, in particular reduced to zero, and electrical energy from the generator is converted into heat in a braking resistor of the low-pressure steam turbine system. As a result, the low-pressure steam turbine system can be switched off particularly quickly. This operating method corresponds to a quick shutdown or emergency shutdown of the low-pressure steam turbine system.

The operating method according to the invention is preferably carried out on a low-pressure steam turbine system according to the invention described above.

• d) Verändern einer Verdampfungsrate in dem Entspannungsverdampfer. Dadurch kann auf die thermische Energie und/oder den Massenstrom des verdampften Wärmeträgermediums/Fluids eingewirkt werden. Dies erlaubt es, die Leistung der Dampfturbine zu beeinflussen. Zum Verändern der Verdampfungsrate kann eine Förderleistung einer Vorlaufpumpe, die flüssiges Wärmeträgermedium in den Entspannungsverdampfer fördert, verändert werden. Der Schritt d) kann gleichzeitig mit den Schritten b) und c) durchgeführt werden. Die Schritte b), c) und/oder d) können wiederholt durchgeführt werden.

The operating method can have the further step d):

• d) changing an evaporation rate in the flash evaporator. This allows the thermal energy and / or the mass flow of the evaporated heat transfer medium / fluid to be influenced. This allows the performance of the steam turbine to be influenced. To change the evaporation rate, a delivery rate of a flow pump, which conveys liquid heat transfer medium into the flash evaporator, can be changed. The step d ) can be done simultaneously with the steps b ) and c ) be performed. The steps b ), c ) and or d ) can be repeated.

The speed of the steam turbine is preferably changed as part of the operating method. The steps are for this b ), c ) and possibly d ).

Further advantages of the invention result from the description and the drawing. The embodiments shown and described are not to be understood as an exhaustive list, but rather have an exemplary character for the description of the invention.

Figure list

• 1 eine Niederdruckdampfturbinenanlage mit einem Entspannungsverdampfer, einer Dampfturbine, einem Generator und einem Kondensator, in einer symbolischen Darstellung;
• 2 eine Niederdruckdampfturbinenanlage wie in 1, weiterhin aufweisend einen solarthermischen Wärmeerzeuger, in einer symbolischen Darstellung;
• 3 eine Niederdruckdampfturbinenanlage wie in 1, weiterhin aufweisend einen Wärmespeicher, in einer symbolischen Darstellung;
• 4 eine Niederdruckdampfturbinenanlage wie in 3, weiterhin aufweisend einen solarthermischen Wärmeerzeuger, in einer symbolischen Darstellung;
• 5 eine Dampfturbine und einen Generator für eine Niederdruckdampfturbinenanlage, wobei der Generator stromaufwärts eines Turbinenrades der Dampfturbine in einer Zuleitung angeordnet ist, in einem schematischen Längsschnitt;
• 6 einen Ablaufplan eines Betriebsverfahrens für den Normalbetrieb einer Niederdruckdampfturbinenanlage;
• 7 einen Ablaufplan eines Betriebsverfahrens für eine Schnellabschaltung einer Niederdruckdampfturbinenanlage.

The invention is illustrated in the drawing and is explained in more detail using exemplary embodiments. Show it:

• 1 a low-pressure steam turbine system with a flash evaporator, a steam turbine, a generator and a condenser, in a symbolic representation;
• 2nd a low pressure steam turbine plant as in 1 , still showing a solar thermal heat generator, in a symbolic representation;
• 3rd a low pressure steam turbine plant as in 1 , further comprising a heat store, in a symbolic representation;
• 4th a low pressure steam turbine plant as in 3rd , still showing a solar thermal heat generator, in a symbolic representation;
• 5 a steam turbine and a generator for a low-pressure steam turbine system, the generator being arranged upstream of a turbine wheel of the steam turbine in a feed line, in a schematic longitudinal section;
• 6 a flowchart of an operating method for the normal operation of a low pressure steam turbine plant;
• 7 a flow chart of an operating method for a quick shutdown of a low pressure steam turbine system.

1 shows a low pressure steam turbine plant 10th in a symbolic representation.

The low pressure steam turbine plant 10th has a flash evaporator 12 on. In the flash evaporator 12 is in operation of the low pressure steam turbine plant 10th liquid heat transfer medium 14 , here water, evaporates at a pressure below the ambient pressure. Through the evaporation of the liquid heat transfer medium 14 vaporous fluid is obtained.

The vaporous fluid is through a feed line 16 the low pressure steam turbine plant 10th to a steam turbine 18th the low pressure steam turbine plant 10th headed. The supply line 16 connects the flash evaporator 12 fluidic with the steam turbine 18th . The steam turbine 18th is mechanical with a generator 20th coupled. The generator 20th is from the steam turbine 18th driven. The generator can have a nominal output of at least 50 kW. The generator typically has a nominal output of at most 500 kW, preferably at most 300 kW, particularly preferably at most 200 kW, very particularly preferably at most 100 kW. The generator 20th can within the supply line 16 upstream of the steam turbine 18th be arranged, cf. 5 . The fluid then flows first on the generator 20th over and is then through the steam turbine 18th headed. As it flows past the generator 20th the fluid can cool it.

In operation of the low pressure steam turbine plant 10th converts the steam turbine 18th thermal energy of the fluid into mechanical energy. From the steam turbine 18th Mechanical energy provided by the generator 20th converted into electrical energy. The low pressure steam turbine plant 10th has power electronics 22 on over which the generator 20th can be connected to a consumer and / or a power grid. The power electronics 22 typically includes a feed converter with a rectifier and an inverter. The inverter converts that from the generator 20th generated, typically high-frequency, alternating current, to direct current. The direct current can flow in an intermediate circuit of the feed converter. The inverter uses the direct current to generate alternating current for feeding into a power grid or for supplying a consumer. The alternating current generated by the inverter always shows that at the place of use Low-pressure steam turbine system with the usual frequency and voltage, for example 50 Hz and 230 V in Europe.

A control unit 24th the low pressure steam turbine plant 10th is set up to load the generator 20th through the power electronics 22 to change. The one in the steam turbine 18th converted power is essentially determined by the pressure of the vaporous fluid upstream and downstream of the steam turbine 18th and determines the mass flow of the vaporous fluid. The one from the steam turbine 18th The mechanical energy is provided by the generator 20th converted into electrical energy and heat. If that's from the generator 20th Electric power output from the steam turbine 18th mechanical power output minus a conversion loss in the generator 20th corresponds, the speed of the steam turbine remains 18th constant. If the generator 20th electrical power output is smaller than that of the steam turbine 18th mechanical power output minus a conversion loss in the generator 20th , the speed of the steam turbine increases 18th on. If the generator 20th (briefly) more electrical power is required than that of the steam turbine 18th mechanical power output minus a conversion loss in the generator 20th corresponds to providing the power difference, kinetic energy of the rotation of a rotor (comprising, for example, a turbine wheel, a shaft and a rotor) of a steam turbine 18th and generator 20th converted into electrical energy. This reduces the speed of the steam turbine 18th . In this way, the control unit 24th by means of the power electronics 22 about the power output of the generator 20th the speed of the steam turbine 18th influence.

The low pressure steam turbine plant 10th has a capacitor 26 on. The condenser 26 is about a derivative 28 the low pressure steam turbine plant 10th fluidic with the steam turbine 18th connected. After the vaporous fluid in the steam turbine 18th has been relaxed while releasing energy, it will be discharged 28 in the capacitor 26 headed. In the condenser 26 the vaporous fluid is condensed by heat dissipation, so that liquid heat transfer medium 14 is obtained. The pressure in the condenser 26 is in the operation of the low pressure steam turbine plant 10th below ambient pressure. A coolant pump 30th supplies the capacitor 26 with cooling medium, for example water. The cooling medium has when entering the condenser 26 typically a temperature of 10 ° C to 20 ° C. The cooling medium causes heat to be removed from the fluid. Condensed heat transfer medium is through a condensate pump 31 from the capacitor 26 deducted. The condensed heat transfer medium exits the condenser 26 typically a temperature of 32 ° C to 60 ° C.

The supply line 16 and the derivative 28 are components of a pipe system that the flash evaporator 12 via the steam turbine 18th with the capacitor 26 connects. To the pressure in the flash evaporator 12 and the capacitor 26 The low-pressure steam turbine system shows how to lower it below ambient pressure 10th an evacuation facility 32 , here comprising a vacuum pump. The evacuation facility 32 is here on the capacitor 26 arranged. To the low pressure steam turbine plant 10th to be put into operation by means of the evacuation device 32 Gases are sucked out of the pipe system until the pressure is below the boiling pressure of the liquid heat transfer medium 14 in the flash evaporator 12 lies. Typically the evacuation device 32 operated such that the pressure in the flash evaporator 12 is 0.3 to 0.7 bar. The pressure in the condenser 26 is then typically after the expansion of the fluid in the steam turbine at 0.05 to 0.2 bar.

Warm heat transfer medium 14 is by a flow pump 34 in the flash evaporator 12 promoted. A temperature of water as a heat transfer medium in the flow is typically 95 ° C to 105 ° C. For example, waste heat from a process can be used to heat the heat transfer medium. In the flash evaporator 12 Standing water as a heat transfer medium typically has a temperature of 70 ° C to 90 ° C. At these temperatures, water boils at the aforementioned pressures of 0.3 to 0.7 bar. The control unit 24th is designed to increase the flow rate of the feed pump 34 to change. An evaporation rate of the heat transfer medium can thereby be influenced. This in turn affects those in the steam turbine 18th actionable performance. By evaporation of the heat transfer medium 14 in the flash evaporator 12 cools the heat transfer medium 14 from. It is therefore via a return pump 36 from the flash evaporator 12 deducted.

Downstream of a turbine wheel of the steam turbine 18th shows the low pressure steam turbine plant 10th a vacuum breaker 38 on. The vacuum breaker 38 is here on the capacitor 26 arranged. The control unit 24th is set up the vacuum breaker 38 to open. Due to the low pressure in the condenser 26 When the vacuum breaker is open, air flows from the environment into the condenser 26 and from this into the derivative 28 . This increases the pressure downstream of the steam turbine 18th . This lowers that of the steam turbine 18th available isentropic enthalpy gradient, so the performance of the steam turbine 18th sinks. At constant load on the generator 20th this reduces the speed of the steam turbine 18th and the generator coupled to it 20th . If there is a sufficient amount of ambient air in the low pressure steam turbine system 10th has flowed in, comes the operation of the low-pressure steam turbine system 10th finally to a halt. The vacuum breaker 38 in this way acts as a safety device through which the low pressure steam turbine plant 10th can be switched off. In the supply line 16 and on the steam turbine 18th In contrast, there are no safety devices such as quick-closing valves or quick-closing flaps and no control devices such as control valves or control flaps.

The low pressure steam turbine plant 10th still has a braking resistor here 40 on. The braking resistor 40 is electrical with the power electronics 22 connected. The control unit 24th is set up about power electronics 22 electrical energy in the braking resistor 40 to convert into heat. This can put an additional load on the generator 20th be reached when a limit of the power output into the power grid or to the consumer is reached. By introducing electrical current from the generator 20th in the braking resistor 40 can with otherwise constant operating parameters of the low-pressure steam turbine system 10th the speed of the steam turbine 18th be lowered.

In the control unit 24th the low pressure steam turbine plant 10th a map is stored. The map links an operating state of the low-pressure steam turbine system 10th with a setpoint of the speed of the steam turbine 18th . To define the operating state, one or more of the variables pressure in the feed line, pressure in the discharge line, temperature of the vaporous fluid in the feed line and / or in the flash evaporator, temperature of the vaporous fluid in the discharge line and / or in the condenser, enthalpy of the Fluids can be used in the supply line and / or in the discharge line. For a combination of numerical values of these parameters, the characteristic diagram contains a respectively assigned nominal value of the speed. An interpolation to neighboring values can be carried out for numerical values not stored. The control unit 24th is set up the speed of the steam turbine 18th to adjust to the setpoint of the current operating state. This can be done by a control algorithm in the control unit 24th be deposited. In other words, the map and the control algorithm record the thermodynamic variables that influence the isentropic enthalpy gradient and process them for control purposes. The control unit can control the speed 24th preferably the load on the generator as described above 20th about power electronics 22 and the flow rate of the feed pump 34 change. The control unit can in particular if these measures are not sufficient to remain within a permissible range of an operating parameter 24th in addition or as an alternative to these measures, the vacuum breaker 38 open and / or electrical energy in the braking resistor 40 conduct.

The control unit 24th is also set up to the return pump 36 , the condensate pump 31 , the coolant pump 30th and the evacuation device 32 to control and in particular to change their respective delivery or suction power. For the sake of clarity, in 1 corresponding control lines are not shown.

The low-pressure steam turbine system can be designed in several stages in an embodiment, not shown. For this purpose, the return of the flash evaporator, which works at the highest temperature, is connected to the feed (flow) of another flash evaporator, which works at a lower pressure level in accordance with its (lower) feed temperature. In this way, several flash evaporators can be connected in series. The vaporous fluid from the several flash evaporators can be fed to a common steam turbine. Alternatively, several steam turbines can each be supplied with fluid from one or more of the several flash evaporators.

2nd shows a low pressure steam turbine plant 10th with the components of the low pressure steam turbine system 10th according to 1 and still having a solar thermal heat generator 42 . Structure and function of the low-pressure steam turbine system 10th from 2nd correspond - from the solar thermal heat generator 42 apart from the low pressure steam turbine system 10th from 1 . For the components adopted and their function, reference is made to the above description. The power electronics 22 , the control unit 24th and the braking resistor 40 are in 2nd not shown; however, these components are present and designed in exactly the same way as in the low-pressure steam turbine system 10th from 1 .

Through the solar thermal heat generator 42 becomes the low pressure steam turbine plant 10th expanded to a solar thermal power plant. In the solar thermal heat generator 42 becomes a liquid heat transfer medium 14 , here water, warmed by solar radiation, cf. Arrows diagonally from above. The feed pump 34 promotes the warm heat transfer medium 14 from the solar thermal heat generator 42 in the flash evaporator 12 . In the flash evaporator 12 becomes the heat transfer medium 14 evaporated under vacuum so that vaporous fluid is obtained. The vapor turbine drives the steam turbine 18th on.

The evaporation cools it in the flash evaporator 12 standing, liquid heat transfer medium 14 from. This heat transfer medium 14 is through the return pump 36 back to the solar thermal heat generator 42 promoted. There is the heat transfer medium 14 warmed again by solar radiation and then in the flash evaporator 12 initiated. In this way, a first cycle (cycle process) is set up.

After passing through the steam turbine 18th becomes the vaporous fluid in the condenser 26 condensed under negative pressure, so that again liquid heat transfer medium 14 is obtained. The liquid heat transfer medium 14 is through the condensate pump 31 in the solar thermal heat generator 42 promoted. There is the heat transfer medium 14 warmed again by solar radiation and then in the flash evaporator 12 initiated. In this way, a second cycle (cycle process) is established. The condensate pump 31 , the solar thermal heat generator 42 and the feed pump 34 form a return device to liquid heat transfer medium from the condenser 26 in the flash evaporator 12 attributed.

3rd shows a low pressure steam turbine plant 10th with the components of the low pressure steam turbine system 10th according to 1 and further comprising a heat accumulator 44 . Structure and function of the low-pressure steam turbine system 10th from 3rd correspond - from the heat storage 44 apart from the low pressure steam turbine system 10th from 1 . For the components adopted and their function, reference is made to the above description. The power electronics 22 , the control unit 24th and the braking resistor 40 are in 3rd not shown; however, these components are present and designed in exactly the same way as in the low-pressure steam turbine system 10th from 1 .

In the heat storage 44 becomes a warm, liquid heat transfer medium 14 , here water, stored. Warm heat transfer medium 14 becomes the heat accumulator 44 supplied from a heater, not shown, see. left, upper arrow in the heat accumulator 44 inside. When storing in the heat store 44 cools the heat transfer medium 14 from. It is therefore re-heated in the heating device, cf. left, lower arrow from the heat accumulator 44 out.

The feed pump 34 promotes the warm heat transfer medium 14 from the heat storage 44 in the flash evaporator 12 . In the flash evaporator 12 becomes the heat transfer medium 14 evaporated under vacuum so that vaporous fluid is obtained. The vapor turbine drives the steam turbine 18th on.

The evaporation cools it in the flash evaporator 12 standing, liquid heat transfer medium 14 from. This heat transfer medium 14 is through the return pump 36 back to the heat accumulator 44 promoted. In this way, a first cycle (cycle process) is set up.

From the heat storage 44 becomes the heat transfer medium 14 fed back to the heating device and heated there. Then the heated heat transfer medium is again in the heat storage 44 initiated. In this way, a second cycle (cycle process) is established. From the heat storage 44 the heated heat transfer medium is again in the flash evaporator 12 promoted, and so on.

After passing through the steam turbine 18th becomes the vaporous fluid in the condenser 26 condensed under negative pressure, so that again liquid heat transfer medium 14 is obtained. The liquid heat transfer medium 14 is through the condensate pump 31 in the heat accumulator 44 promoted. In this way, a third cycle (cycle process) is established. From the heat storage 44 becomes the heat transfer medium 14 conveyed again into the heating device and warmed there. Then the heat transfer medium 14 again in the flash evaporator 12 initiated. The condensate pump 31 , the heat accumulator 44 and the feed pump 34 form a return device to liquid heat transfer medium from the condenser 26 in the flash evaporator 12 attributed.

4th shows a low pressure steam turbine plant 10th with the components of the low pressure steam turbine system 10th according to 3rd and still having a solar thermal heat generator 42 . The solar thermal heat generator 42 acts as a heating device for the liquid heat transfer medium described above 14 . In this way, a solar thermal storage power plant is obtained.

Structure and function of the low-pressure steam turbine system 10th from 4th correspond - from the solar thermal heat generator 42 apart from the low pressure steam turbine system 10th from 3rd . For the components adopted and their function, reference is made to the above description. The power electronics 22 , the control unit 24th and the braking resistor 40 are in 4th not shown; however, these components are present and designed in exactly the same way as in the low-pressure steam turbine system 10th from 1 .

As already mentioned, the solar thermal heat generator takes over 42 at the low pressure steam turbine plant 10th from 4th the function of the heater. To the liquid heat transfer medium 14 from the heat storage 44 To promote in the solar thermal heat generator is a heating circuit pump 46 intended. By introducing the heat transfer medium 14 from the heat storage 44 in the solar thermal heat generator 42 is in the solar thermal heat generator 42 heat transfer medium heated by solar radiation (see arrows from diagonally above) 14 displaced and in the heat storage 44 pressed. The condensate pump 31 , the heat accumulator 44 , the heating circuit pump 46 , the solar thermal heat generator 42 and the feed pump 34 form a return device to liquid heat transfer medium from the condenser 26 in the flash evaporator 12 attributed.

The control unit 24th is set up for the heating circuit pump 46 head for. In particular, the control unit 24th a delivery rate, for example a volume flow, of the heating circuit pump 46 to adjust.

5 shows a turbo set 48 having a steam turbine 18th and a generator 20th for a low pressure steam turbine plant 10th , such as in the 1 to 4th is shown in a schematic longitudinal section. The generator 20th is upstream of a turbine wheel 50 the steam turbine 18th in a supply line 16 arranged.

The steam turbine 18th is designed as an axial turbine. The steam turbine 18th points the turbine wheel 50 and a stator 52 on. The idler 52 is upstream of the turbine wheel 50 arranged, here between the turbine wheel 50 and the generator 20th . The turbine wheel 50 is by means of a wave 54 rotatably mounted. The turbine wheel points radially outside 50 a barrel blading 56 on. The blading 56 can from the turbine wheel 50 include separate blades attached to the turbine wheel 50 are attached. Alternatively, the turbine wheel 50 be formed in one piece, ie the blading 56 can be an integral part of the turbine wheel 50 be. The blading 56 the steam turbine 18th can be implemented in impulse or reaction design. The idler 52 is not rotatable on an outer housing 58 of the turbo set 48 held. The outer case 58 forms upstream of the steam turbine 18th the supply line 16 with out. Downstream of the steam turbine 18th forms the outer housing 58 a derivative 28 with out. About the supply line 16 becomes the steam turbine 18th Fluid supplied. About the derivative 28 becomes relaxed fluid after passing through the steam turbine 18th dissipated.

Within the supply line 16 is the generator 20th arranged. The generator 20th is therefore upstream of the steam turbine 18th . A direction of flow through the turbo set 48 is in 5 indicated by arrows. The flow of the fluid here runs in a straight line through the feed line 16 on the generator 20th over and to the steam turbine 18th there.

The generator 20th has a rotor 60 and a stator 62 on. The rotor 60 is on the same wave 54 like the turbine wheel 50 arranged. So that's the rotor 60 together with the turbine wheel 50 around a common longitudinal axis 64 rotatable. The wave 54 , the rotor 60 and the turbine wheel 50 form a rotor of the turbo set 48 . The longitudinal axis 64 can be used to operate the turbo set 48 horizontal, vertical or inclined.

The wave 54 is in a first depository 66 and a second depository 68 stored. The first depository 66 is between the rotor 60 and the turbine wheel 50 . The second depository 68 is from the turbine wheel 50 seen from beyond, ie upstream, of the rotor 60 . The bearings 66 , 68 can be carried out in a manner known per se as a fixed / floating bearing arrangement, floating support bearing or employed support bearing. Bearings of the bearing arrangements 66 , 68 can be designed as roller bearings, plain bearings and / or magnetic bearings. The steam turbine 18th can be stored oil-free. Should be used as a heat transfer medium 14 Water is used, and that in the condenser 26 If the resulting condensate is processed as drinking or process water, contamination of the condensate can be avoided.

The stator 62 of the generator 20th is in an inner case 70 arranged. The inner case 70 is inside the supply line 16 arranged. The inner case 70 can on the outer housing via unspecified supports 58 support. The bearings 66 , 68 support the shaft 54 in a manner not shown on the inner housing 70 from.

Between the inner case 70 and the supply line 16 of the outer case 58 is an annular gap 72 educated. In operation of the low pressure steam turbine plant 10th with the turbo set 48 the fluid flows through the annular gap 72 on the generator 20th past. On the outside, the inner casing 70 Cooling fins 74 on. The cooling fins 74 protrude in to the longitudinal axis 64 radial direction in the annular gap 72 inside. The cooling fins are in operation 74 thus swept over by the flowing fluid, so that the generator 20th is cooled. The stator can be used to improve heat dissipation 62 in a manner not shown, but known per se, heat-conducting with the cooling fins 74 be connected.

6 shows a flow chart for an operating method for normal operation 100 a low pressure steam turbine plant 10th , such as in the 1 to 4th is shown. In one step 102 becomes a line system for the low-pressure steam turbine plant 10th evacuated. The pressure in the line system drops everywhere to a value below the ambient pressure of 1 bar. The pressure in the pipe system is reduced during the evacuation 102 lowered so far that in a flash evaporator 12 the low pressure steam turbine plant 10th liquid heat transfer medium 14 evaporates. By evaporating the heat transfer medium 14 vaporous fluid is obtained. The vaporous fluid drives a steam turbine 18th the low pressure steam turbine plant 10th on. The steam turbine 18th in turn drives a generator 20th the low pressure steam turbine plant 10th on. The generator 20th converts mechanical energy to it from the steam turbine 18th is provided in electrical energy.

In one step 104 becomes the electrical load on the generator 20th changed. A control unit 24th the low pressure steam turbine plant 10th acts on a power electronics 22 one over which the generator 20th is connected to a consumer and / or a power grid. By changing the electrical load on the generator 20th the speed of the steam turbine changes 18th .

In one step 106 becomes an evaporation rate in the flash evaporator 12 changed. The step 104 can be with or before or after the step 104 be performed. Typically, the steps 104 and 106 performed repeatedly. To change the evaporation rate, the control unit changes 24th a delivery rate of a feed pump 34 who have favourited Warm Heat Transfer Medium 14 in the flash evaporator 12 promotes. By changing the evaporation rate in the flash evaporator 12 becomes the performance of the steam turbine 18th influenced, so that - with otherwise constant operating parameters - the speed of the steam turbine 18th is changed.

The steps 104 and 106 are carried out in such a way that the speed of the steam turbine 18th depending on an operating state of the low-pressure steam turbine system 10th is regulated to a setpoint. This is in the control unit 24th stored a map that links the operating state with the setpoint. The operating state comprises one or more of the variables pressure in a supply line 16 , Pressure in a derivative 28 , Temperature of the vaporous fluid in the feed line 16 and / or in the flash evaporator 12 , Temperature of the vaporous fluid in the discharge 28 and / or in a capacitor 26 , Enthalpy of the fluid in the supply line 16 and / or in the derivation 28 .

When the operation of the low pressure steam turbine plant 10th is to be ended in one step 108 a vacuum breaker 38 downstream of a turbine wheel 50 the steam turbine 18th open. As a result, ambient air flows into the pipe system and increases downstream of the turbine wheel 50 the pressure in the pipe system. This lowers that on the steam turbine 18th adjacent isentropic enthalpy gradient until finally the steam turbine 18th comes to a standstill.

• - der Vakuumbrecher 38 wird geöffnet (Schritt 112),
• - ein Volumenstrom von in den Entspannungsverdampfer 12 fließendem Wärmeträgermedium 14 wird auf null verringert (Schritt 114),
• - elektrische Energie aus dem Generator 20 wird in dem Bremswiderstand 40 in Wärme umgesetzt (Schritt 116).

Zudem kann gleichzeitig mit den Schritten 112, 114 und 116 in einem Schritt 118 die Abgabe von elektrischer Leistung aus dem Generator 20 an einen Verbraucher und/oder ein Stromnetz maximiert werden. 7 shows a flow chart of an operating method for a quick shutdown 110 a low pressure steam turbine plant 10th , such as in the 1 to 4th is shown. The low-pressure steam turbine plant is located first 10th in normal operation 100 , for example according to 6 . If the low-pressure steam turbine system is shut down quickly 10th the following steps are performed simultaneously:

• - the vacuum breaker 38 opens (step 112 ),
• - A volume flow of in the flash evaporator 12 flowing heat transfer medium 14 is reduced to zero (step 114 ),
• - electrical energy from the generator 20th is in the braking resistor 40 converted into heat (step 116 ).

It can also coincide with the steps 112 , 114 and 116 in one step 118 the delivery of electrical power from the generator 20th to a consumer and / or a power grid can be maximized.

Through the steps 112 and 114 will be in the steam turbine 18th maximum mechanical power that can be generated is reduced. Through the step 114 the evaporation process comes to a standstill and the steam mass flow decreases. Through the steps 116 and 118 becomes the power output of the generator 20th elevated. This increases the need for mechanical power for the generator 20th . If the power requirement of the generator 20th the performance of the steam turbine 18th exceeds, rotational energy from steam turbine 18th and generator 20th converted into electrical energy so that the speed of the steam turbine 18th decreases until it comes to a standstill.

Taking all the figures together, the invention relates to a low-pressure steam turbine system 10th , which is operated in a heat-guided sliding pressure mode, and whose speed is based on a map, variably controlled. The low pressure steam turbine plant 10th is characterized by a variable system pressure on the steam side and a reduced system complexity. This particularly affects the steam turbine 18th , which is designed due to the driving style without upstream control elements (control valves or flaps). Pressure losses in front of the steam turbine 18th are minimized, which has a positive effect on the system efficiency.

The steam generation within the low pressure steam turbine plant 10th relies on the effect of flash evaporation. For this purpose, the system pressure within a line system of the low-pressure steam turbine system 10th under the vapor pressure of a suitable heat transfer medium 14 lowered until saturated steam is produced. The heat transfer medium can be, for example, water, deionized water (deionized water), fresh water, brackish water or sea water.
The system temperatures occurring on the steam side are at most as high as the boiling temperature of the heat transfer medium used 14 at the prevailing ambient pressure. The system pressures on the steam side are always below the ambient pressure. An escape of hot, vaporous fluid (evaporated heat transfer medium) is therefore impossible. This significantly reduces the potential risk. Due to this system characteristic, safety devices (quick-closing valves or flaps) can be used on the steam turbine 18th or in the supply line 16 to be dispensed with.

As one of the steam turbine 18th downstream safety device is on the capacitor 26 a vacuum breaker 38 used. When it is opened, the system is flooded with ambient air and the process comes to a standstill.

• - das der Dampfturbine 18 zur Verfügung stehende isentrope Enthalpiegefälle,
• - die der Dampfturbine 18 zur Verfügung stehende Druckdifferenz,
• - die der Dampfturbine 18 zur Verfügung stehende Temperaturdifferenz, und/oder
• - ein in der Steuereinheit 24 hinterlegtes Kennfeld herangezogen werden.

The steam turbine 18th comes with a generator 20th like a turbo set 48 connected that both components always run at the same, variable speed. The steam turbine 18th and the generator 20th can be directly coupled or connected with a coupling or positioned on a common shaft. A mechanical gearbox is not used. The steam turbine 18th can be carried out in one or more stages. Adapting the in the generator 20th generated current to the prevailing grid frequency and the speed control of the turbo set 48 are carried out via a power electronics feed converter 22 . The speed setpoint is determined via a map that in a control unit 24th is deposited. The speed of the steam turbine 18th and the generator coupled to it 20th is changed by loading or unloading the generator via the feed converter. As a manipulated variable for the speed control of the steam turbine 18th and the generator coupled to it 20th can

• - that of the steam turbine 18th available isentropic enthalpy gradient,
• - that of the steam turbine 18th available pressure difference,
• - that of the steam turbine 18th available temperature difference, and / or
• - one in the control unit 24th stored map can be used.

The steam side pressure in the flash evaporator 12 , in the supply line 16 and in front of the steam turbine 18th is variable. It is a function of the temperature of the flash evaporator 12 supplied heat transfer medium 14 and the flash evaporator 12 supplied amount of heat.

The steam mass flow, that of the steam turbine 18th is fed is variable. It arises depending on the temperature of the flash evaporator 12 supplied heat transfer medium 14 and the flash evaporator 12 supplied amount of heat. On the flash evaporator 12 heat can be supplied via the flow pump 34 control influence. The electrical power of the low pressure steam turbine system 10th is from the flash evaporator 12 amount of heat supplied and the temperature of the heat transfer medium 14 dependent. By regulating the mass flow or volume flow of the heat transfer medium 14 the electrical power can be regulated.

The isentropic enthalpy gradient, that of the steam turbine 18th is available is variable. Because in the flash evaporator 12 Only saturated steam is generated, it depends on the pressure in front of the steam turbine 18th adjusts, and from the pressure in the condenser 26 prevails.

The low pressure steam turbine plant 10th stands out due to the heat-controlled sliding pressure operation and the speed-controlled steam turbine 18th through an expanded operating range compared to conventionally operated systems. In addition, the steam turbine is adapted to the isentropic enthalpy gradient 18th always operated at the optimum efficiency or close to the optimum efficiency for the respective load point, which has a positive effect on the system efficiency.

• - einen Entspannungsverdampfer (12), zum Verdampfen von flüssigem Wärmeträgermedium (14), wobei der Druck in dem Entspannungsverdampfer (12) unter dem Umgebungsdruck liegt,
• - eine Dampfturbine (18),
• - einen Generator (20), der mit der Dampfturbine (18) gekoppelt ist,
• - eine Leistungselektronik (22) zum Anschließen des Generators (20) an einen Verbraucher und/oder ein Stromnetz,
• - einen Kondensator (26), zum Kondensieren des im Betrieb aus der Dampfturbine (18) austretenden dampfförmigen Fluids, wobei der Druck in dem Kondensator (26) unter dem Umgebungsdruck liegt,
• - einen Vakuumbrecher (38), der stromabwärts eines Turbinenrades (50) der Dampfturbine (18) angeordnet ist, und
• - eine Steuereinheit (24), die dazu eingerichtet ist, die elektrische Belastung des Generators (20) durch die Leistungselektronik (22) zu verändern und den Vakuumbrecher (38) zu öffnen.

Weiter betrifft die Erfindung ein Betriebsverfahren für eine Niederdruckdampfturbinenanlage (10), mit den Schritten

1. a) Evakuieren eines Leitungssystems der Niederdruckdampfturbinenanlage (10), sodass der Druck in dem Leitungssystem überall unter dem Umgebungsdruck liegt und sodass Wärmeträgermedium (14) in einem Entspannungsverdampfer (12) verdampft,
2. b) Verändern der elektrischen Belastung eines Generators(20),
3. c) Öffnen eines Vakuumbrechers (38).

After all, the invention relates to a low-pressure steam turbine plant ( 10th )

• - a flash evaporator ( 12 ), for evaporating liquid heat transfer medium ( 14 ), the pressure in the flash evaporator ( 12 ) is below the ambient pressure,
• - a steam turbine ( 18th ),
• - a generator ( 20th ) with the steam turbine ( 18th ) is coupled,
• - power electronics ( 22 ) for connecting the generator ( 20th ) to a consumer and / or a power grid,
• - a capacitor ( 26 ) to condense the steam turbine during operation ( 18th ) escaping vaporous fluid, the pressure in the condenser ( 26 ) is below the ambient pressure,
• - a vacuum breaker ( 38 ), the downstream of a turbine wheel ( 50 ) of the steam turbine ( 18th ) is arranged, and
• - a control unit ( 24th ), which is designed to reduce the electrical load on the generator ( 20th ) by the power electronics ( 22 ) and change the vacuum breaker ( 38 ) to open.

The invention further relates to an operating method for a low-pressure steam turbine plant ( 10th ) with the steps

1. a) evacuating a line system of the low-pressure steam turbine system ( 10th ), so that the pressure in the pipe system is everywhere below the ambient pressure and that heat transfer medium ( 14 ) in a flash evaporator ( 12 ) evaporates,
2. b) changing the electrical load of a generator ( 20th ),
3. c) opening a vacuum breaker ( 38 ).

Reference symbol list

10th

Low pressure steam turbine plant

12

Flash evaporator

14

liquid heat transfer medium

16

Supply

18th

Steam turbine

20th

generator

22

Power electronics

24th

Control unit

26

capacitor

28

Derivative

30th

Coolant pump

31

Condensate pump

32

Evacuation facility

34

Flow pump

36

Return pump

38

Vacuum breaker

40

Braking resistor

42

solar thermal heat generator

44

Heat storage

46

Heating circuit pump

48

Turbo set

50

Turbine wheel

52

Diffuser

54

wave

56

Barrel blading

58

Outer housing

60

rotor

62

stator

64

Longitudinal axis

66

first depository

68

second depository

70

Inner casing

72

Annular gap

74

Cooling fins

100

Normal operation

102

Evacuate

104

Change load

106

Change evaporation rate

108

Open vacuum breaker

110

Quick shutdown

112

Open vacuum breaker

114

Reduce volume flow

116

Implement energy in the braking resistor

118

Maximize power output

Claims (13)

Low-pressure steam turbine system (10) comprising - a flash evaporator (12) for evaporating liquid heat transfer medium (14) so that vaporous fluid is obtained, the pressure in the flash evaporator (12) being below the ambient pressure, - a steam turbine (18), - one Feed line (16) which fluidically connects the flash evaporator (12) to the steam turbine (18), a generator (20) which is coupled to the steam turbine (18), - a condenser (26) for condensing the vaporous fluid emerging from the steam turbine (18) during operation, so that liquid heat transfer medium (14) is obtained, the pressure in the condenser (26) is below the ambient pressure, - a discharge line (28) which fluidly connects the steam turbine (18) to the condenser (26), characterized in that the low-pressure steam turbine system (10) also has the following: - power electronics ( 22), for connecting the generator (20) to a consumer and / or a power network, - a vacuum breaker (38), which is arranged downstream of a turbine wheel (50) of the steam turbine (18), and - a control unit (24), the is set up to change the electrical load of the generator (20) by the power electronics (22) and to open the vacuum breaker (38), and that the generator (20) upstream of the steam turbine (18) within the inlet line (16) is arranged. Low pressure steam turbine system (10) after Claim 1 , characterized in that the turbine wheel (50) of the steam turbine (18) and a rotor (60) of the generator (20) are arranged on a common shaft (54). Low-pressure steam turbine system (10) according to one of the preceding claims, further comprising an evacuation device (32). Low-pressure steam turbine system (10) according to one of the preceding claims, further comprising a braking resistor (40). Low-pressure steam turbine plant (10) according to one of the preceding claims, further comprising a feed pump (34) to convey liquid heat transfer medium (14) into the flash evaporator (12), the control unit (24) being designed to deliver the delivery of the feed pump (34) to change. Low-pressure steam turbine system (10) according to one of the preceding claims, characterized in that a control map is stored in the control unit (24), which maps an operating state of the low-pressure steam turbine system (10) to a setpoint value of a speed of the steam turbine (18), in particular wherein the operating state is a or more of the sizes - pressure in the feed line (16), - pressure in the discharge line (28), - temperature of the vaporous fluid in the feed line (16) and / or in the flash evaporator (12), - temperature of the vaporous fluid in the Derivation (28) and / or in the capacitor (26) comprises. Low-pressure steam turbine system (10) according to one of the preceding claims, further comprising a return device for returning liquid heat transfer medium (14) from the condenser (26) to the flash evaporator (12). Low-pressure steam turbine system (10) according to one of the preceding claims, characterized in that a stator (62) of the generator (20) is arranged in an inner housing (70). Low-pressure steam turbine plant (10) according to one of the preceding claims, further comprising a heat accumulator (44) and / or a solar thermal heat generator (42). Operating method for a low-pressure steam turbine system (10), the low-pressure steam turbine system (10) comprising: - a flash evaporator (12), - a steam turbine (18), - a capacitor (26), - a generator (20) which is driven by the steam turbine (18), - A line system that connects the flash evaporator (12) via a feed line (16), the steam turbine (18) and a discharge line (28) to the condenser (26), and - A vacuum breaker (38), which is arranged downstream of a turbine wheel (50) of the steam turbine (18), with the steps a) evacuating (102) the line system so that the pressure in the line system is everywhere below the ambient pressure and so that heat transfer medium (14) evaporates in the flash evaporator (12), b) changing the electrical load on the generator (20), c) opening (112) the vacuum breaker (38), the vacuum breaker (38) being opened (112) at the same time, a volume flow of liquid heat transfer medium flowing into the expansion evaporator (12) being reduced (114) and electrical energy from the generator (20 ) is converted (116) into heat in a braking resistor (40) of the low-pressure steam turbine system (10). Operating procedures according to Claim 10 , with the further step d) changing an evaporation rate in the flash evaporator (12). Operating procedures according to Claim 10 or 11 , characterized in that the speed of the steam turbine (18) is changed. Operating method according to one of the Claims 10 to 12 , characterized in that the Volume flow of liquid heat transfer medium flowing into the flash evaporator (12) is reduced to zero.

Images