EP1828569A2

EP1828569A2 - Method for the operation of a pressure accumulator system, and pressure accumulator system

Info

Publication number: EP1828569A2
Application number: EP05813528A
Authority: EP
Inventors: Rolf Althaus; Markus GRÜNENFELDER; Christian Henssler; Patrik Alfons Meier; Hans-Jürgen PETERS; Urs Zinniker
Original assignee: Alstom Technology AG
Current assignee: General Electric Technology GmbH
Priority date: 2004-12-23
Filing date: 2005-11-23
Publication date: 2007-09-05
Also published as: CA2592456A1; WO2006069862A3; CA2592456C; US7900455B2; US20080000233A1; WO2006069862A2

Abstract

Disclosed is a recuperative air storage system comprising a gas turbo group (11) and a heat exchanger (42) in which exhaust gas heat of the gas turbo group can be transferred to a compressed storage fluid that flows from a storage volume (30) to a relief machine (21). A flow divider (41) encompassing an exhaust gas flap that can be operated in several positions is disposed in the exhaust gas path of the gas turbo group upstream from the heat exchanger such that the exhaust gas mass flow (m0) of the gas turbo group can be variably distributed to a flue (43) and the heat exchanger (42). This allows the gas turbo group to be operated quickly at great power in the electricity supply network independently of the heat exchanger and the relief machine while the thermal load of the air storage part is slowly increased by gradually augmenting the exhaust gas proportion (m1) that flows to the heat exchanger.

Description

description

Method for operating a pressure accumulator system, and accumulator system Technical field

The invention relates to a method for Betheb a

Pressure accumulator according to the preamble of claim 1. It further relates to a pressure accumulator, which is suitable for carrying out the inventive method. Furthermore, a control unit is provided, which is suitably and configured to cause a pressure accumulator system for carrying out a method according to the invention, a digital code which is suitable to configure the control unit accordingly, as well as a data carrier on which the code in executable form and / or stored as source code.

State of the art

Pressure accumulator systems have become known in the prior art, in which a pressurized storage fluid, in particular air, stored in a storage volume and, if necessary, relaxed under power in a relaxation machine. From US 5,537,822 a pressure accumulator system has become known in which the storage fluid is heated prior to the relaxation in a heat exchanger. The heat exchanger is flowed through in a disclosed embodiment there on the heat-emitting side of the exhaust gas of a gas turbine group. Such a recuperative embodiment of a pressure accumulator system uses the waste heat of the gas turbine group very efficiently. Due to the indirect heating of the storage fluid this is not contaminated with aggressive flue gas components. Therefore, as a relaxation machine in a highly economical manner, for example, find only a slightly modified derivative of a standard steam turbine use. In stationary operation of the pressure accumulator system such a machine is well adapted to the thermal conditions. At a start the plant however are those in a steam turbine realizable temperature gradient limits, which must be taken into account in the start-up phase. Accordingly, in the case of an arrangement as disclosed in US Pat. No. 5,537,822, for example, the gas turbo group must be operated for a relatively long period of time according to an operating regime specified by the expansion machine and can therefore only be charged very slowly, in contradistinction to the operating regime of a gas turbine group. and it is only with great delay free to respond to the power requirements of the electricity grid to ensure that the ability to use waste heat in the expansion machine with the provided by the gas turbine group Abwärmeangebot can keep up and the storage fluid expansion machine not by a too fast start and Straining takes damage.

Presentation of the invention

There is now a method of the type mentioned, which is suitable for starting a pressure accumulator and in particular a recuperative pressure accumulator, as described above, specified, which according to one aspect of many of the present invention, the disadvantages of the prior art avoids. More specifically, it should allow the process to introduce the pressure accumulator as quickly as possible and with the greatest possible power gradient in an electricity grid, without overstraining the quick start capability of the expansion machine, which could drastically shorten their life. At the same time according to a further aspect of the invention during the start-up phase, the storage fluid possibly necessary for ensuring the operation of the heat exchanger should be used as efficiently as possible.

The method described in claim 1 and in the independent

Device claimed claimed accumulator are, among other benefits, meet these requirements. According to the disclosed method, therefore, the temperature of the storage fluid provided for the expansion machine is suitably controlled independently of the power output of the gas turbine group. By decoupling the temperature of the storage fluid and the power output of the gas turbine group, the gas turbo group can be loaded with its normal power gradient. In this case, a gas turbine group can be loaded after synchronization within, for example, 20 to 30 minutes to maximum power; Machines intended for peak load coverage achieve much shorter load times, which can also be in the range of only 5 to 10 minutes.

In a further development of the method, the expansion machine for the first time receives a storage fluid mass flow supplied when the storage fluid temperature has reached a minimum value at the exit from the heat exchanger. This criterion is especially important when first the heat exchanger must reach an operating temperature from a cold state. In one embodiment, the minimum value of the storage fluid temperature is determined depending on an average temperature of the rotor of the expansion machine. This avoids, among other things, a sudden entry of cold air into the expansion machine and associated thermal shocks. In a further development, this is the case as soon as possible after the synchronization of the gas turbo group, for example immediately after the synchronization of the gas turbo group. By early admission of the expansion machine with storage fluid this is of course as quickly as possible put into a state ready for loading. Important parameters for a steam turbine used as a relaxation machine, for example, the temperature of the rotor, the uniformity of the heating of the rotor and the temperature distribution in the rotor, and / or the heating rate at the inlet flange of the machine, and, during the start-up process at low speeds, the temperature at the outlet from the turbine. The Controlling the temperature of the storage fluid provided for the expansion machine makes it possible in principle to conduct storage fluid into the expansion machine at a very early stage. An embodiment of the method provides for controlling the temperature of the storage fluid provided for the expansion machine such that the temperature and / or the temperature gradient of the expanded storage fluid and / or the temperature gradient of the rotor temperature and / or the housing temperature at the outlet of the expansion machine remain below a limit value or exceed the limit. This comes into play at low speeds and at low powers of the expansion machine and in particular an air turbine. At low speeds of a turbine, that is, in particular during startup and acceleration, the mass flow-specific enthalpy of the working fluid is low for reasons of step kinematics, which is why the temperature difference between the inlet and outlet of the turbine is low. That is, the fluid temperature at the outlet is comparatively close to the fluid temperature at the inlet, which is why, for example, a thermal overload of the designed for low temperatures outlet region is possible without suitable measures. That is, the temperature of the working fluid at the machine entrance can be increased only slowly when accelerating with the speed of the machine, which delays the acceleration process. A refinement of the method explained below therefore provides, during the startup and acceleration of the expansion machine, to operate the generator coupled to the expansion machine at least temporarily by an electric motor and thus to support the acceleration process. Compared to the usual in the prior art accelerating an air turbine, in which this is accelerated purely by the flowing working fluid, thus a much faster acceleration of the expansion machine and thus a faster increase in temperature of the incoming working fluid and thus ultimately an earlier power output of Relaxation machine in the electricity grid allows. At low power operated as a relaxation machine air turbine, a similar problem. From the low mass flow results in a low pressure ratio and thus a comparatively low enthalpy and temperature reduction, which is why even at rated speed, but low power of an air turbine, the temperature at the turbine outlet compared to the full load operation is close to the inlet temperature. Even at rated speed and idling or low power so there is a potential danger of overheating at the turbine outlet. It is therefore advantageous if the temperature of the storage fluid flowing in the expansion machine is controlled during acceleration of an air turbine at rated speed and during loading at powers below the full load power and in particular below 10% or 25% to 50% of the full load power such that specific temperatures and / or or temperature gradient at the outlet of the expansion machine can not be exceeded. In this case, on the one hand, the temperature at the outlet as a function of the temperature at the inlet or the temperature at the inlet can be determined as a function of the temperature at the outlet and further as a function of the pressure ratio via the expansion machine and / or the power and / or the speed of the expansion machine. In the execution of the method, it proves to be expedient, but not mandatory, to further accelerate the starting process and the power output of the entire power plant by supporting the starting of the expansion machine by the motor operation of a generator associated with the expansion machine. Because the power of the electric machine is available in addition to the speed increase of the expansion machine, its speed can be increased faster, whereby the temperature of the storage fluid at the entrance to the expansion machine can be increased faster without allowable temperatures and / or temperature gradients at the exit of the Passing relaxation machine. This is due to the fact that, as described above, at a higher speed, a higher mass flow specific enthalpy degradation takes place, such that the temperature drop of the storage fluid as it flows through the expansion machine increases with increasing speed more and more. This makes it possible to accelerate and synchronize the expansion machine faster to synchronous speed, and the expansion machine can be warmed up faster and placed in a ready-to-power state. Furthermore, the higher speed of the expansion machine also increases its absorption capacity, and a higher mass flow of warmed up storage fluid can be absorbed and utilized by the expansion machine. Overall, the lugging of the expansion machine by means of the motor-driven generator contributes to a fast and energy-efficient, yet gentle and life-prolonging start of the accumulator. In one embodiment of the method, the temperature of the storage fluid is already controlled at the exit from the heat exchanger. This can of course be done by the heat flux flowing through the storage fluid mass flow is adjusted accordingly. If the expansion machine is unable to enforce this mass flow in its current operating state, according to one embodiment of the method described here, a partial mass flow exceeding the mass flow that can be utilized by the expansion machine is blown off, or recooled and recompressed into the storage volume. For this purpose, branches off from the flow path, which leads from the heat exchanger to the expansion machine, a branch line whose flow cross-section varies by means of an actuating and / or obturator and / or shut off and released. However, a partial mass flow of the storage fluid is discarded unused. A further development of the method therefore envisages varying the heat input into the heat exchanger for controlling the temperature of the storage fluid at the exit from the heat exchanger. In a further development, this is done by the heat exchanger, a variable proportion of the exhaust gas mass flow of the gas turbine group is supplied. To realize this, an exemplary pressure accumulator system, which is suitable for carrying out the method, comprising a arranged downstream of the gas turbine group and upstream of the heat exchanger flow branch with an adjustable flap arranged therein for flow diversion and variable flow distribution, which is arranged such that variable portions of Exhaust gas mass flow of the gas turbine group to the heat exchanger and to a second branch of the branch are conductive. In a specific embodiment of the pressure accumulator, the flap is designed such that it has a first stationary operating position, in which the entire exhaust gas mass flow is conducted into the heat exchanger; In addition, the flap has a second stationary operating position, in which the entire exhaust gas mass flow is conducted into the second branch. For carrying out the method, the flap further has at least one third stationary operating position, in which a first partial flow of the exhaust gas to the heat exchanger and a second partial flow of the exhaust gas is conducted to the second branch of the flow branch. In this case, a steady-state operating position is to be fallen below by positions, which usual exhaust gas bypass valves, which only one

Flow switching function, during the switching between these two positions may take a short time. If the possibility of the temperature of the storage fluid already at

Accordingly, one embodiment of the method provides for adjusting the temperature of the storage fluid prior to entering the storage fluid outlet, and / or, if this is not desirable for other reasons. To reduce relaxation machine. This is done, for example, by the unheated storage fluid and / or a liquid mass flow downstream of the heat exchanger and upstream of the expansion machine from the heated storage fluid flowing out of the heat exchanger, in particular, a water mass flow is added. The admixture of a liquid has the advantage that due to the heat of evaporation, a particularly efficient cooling is achieved, and that no consuming compacted storage fluid must be expended for the cooling. In contrast, the use of non-heated storage fluid has the advantage that no liquid needs to be stored or introduced. In order to carry out this variant of the method, the pressure accumulator system comprises a means for lowering the temperature of the heated storage fluid arranged in the flow path from the heat-receiving side of the heat exchanger to the expansion machine, which means comprises for example a means for introducing non-warmed storage fluid and / or a means for introducing liquid into the heated storage fluid ; You could imagine a cooler here, but this means a considerable amount of equipment.

As already indicated above, a target temperature of the storage fluid flowing to the expansion machine is determined in a variant of the method depending on the thermal state of the expansion machine.

Further developments of the inventive method and the accumulator arise from the dependent claims and the embodiments illustrated below.

The control of the pressure accumulator system for carrying out a

Method according to the method claims, for example, by means of a control unit, which has at least one signal output and preferably a plurality of signal outputs and signal inputs, wherein at least one signal output directs a control signal to an actuator of the pressure accumulator, whereby the pressure accumulator is made to carry out a method described above. For this purpose, the control unit generates, for example, a sequence of control signals, or control signals are generated according to a time schedule. If the controller is operated within a closed loop, then the control unit forms the control signals in response to at least one input signal applied to a signal input. To accomplish these tasks, the control unit must be configured accordingly. The configuration of the control unit, for example to define a functional relationship for the formation of control variables from input variables, takes place, for example, via a processor in which a digital program is loaded, which is suitable for configuring the control unit such that it has an accumulator for carrying out an above caused procedure described. In this respect, the invention also includes a control unit which is configured to cause a pressure accumulator system for carrying out a method described above, a digital code which is suitable for configuring a control unit such that it causes the pressure accumulator system to carry out the method, and a data carrier on which such a digital code is stored as an executable instruction sequence or as source code. In addition to non-volatile memory modules, a data carrier should be understood as well as magnetic or optical data carriers to be named by way of example. This also includes memory modules or appropriately configured programmable logic modules, which are installed directly in the control unit. Of course, the list of data carriers is not conclusive.

Short description of the drawing

The invention will be explained in more detail with reference to embodiments illustrated in the drawings. Show in detail

Figure 1 shows a first example of a pressure accumulator system;

Figure 2 shows the schematic course of some operating parameters of the accumulator during a startup; and

Figure 3 shows a second example of a pressure accumulator.

Details that are not essential to understanding the invention have been omitted, but are implicit to those skilled in the art with revealed. The exemplary embodiments are purely instructive and should not be used to limit the invention characterized in the claims.

Ways to carry out the invention

FIG. 1 shows a first pressure accumulator system suitable for carrying out a method as described above. The pressure accumulator system essentially comprises a gas turbine group 1 1, which is arranged with a motor / generator unit 12 and a compressor 13 on a common shaft train. The motor / generator unit 12 can be operated both by motor and by generator. The compressor 13 is used to charge a pressure storage volume 30. Therein stored working fluid can be relaxed in times of high electrical power requirement work in the storage fluid expansion machine, air turbine 21, which drives the generator 22. As an air turbine is in particular a standard, so to speak from stock, available steam turbine use, which only needs to be modified slightly. This results in a particularly economical solution. The electric machine 12 can be connected to the gas turbine group 11 and / or the compressor 13 by means of switchable clutches 14, 15. In times of high power requirements and to start the gas turbine group, the clutch 14 is closed and the clutch 15 is open. To start the gas turbine group, the electric machine 12 is operated by an electric motor and supports the acceleration of the gas turbine group to rated speed. To generate power, the electric machine 12 is operated as a generator and driven by the gas turbine group 11. In times of high availability of electrical energy and with a correspondingly low electricity price, the clutch 15 is closed and the clutch 14 is opened. The machine 12 is operated by an electric motor and drives the compressor 13 to charge the storage volume 30 with pressurized fluid, such as air, with cheap available power and the energy thus stored at times high electric power requirements and correspondingly high electricity prices in the expansion machine 21 to use again for power generation. The gas turbine group 1 1 is meanwhile usually at a standstill; but it is in principle also possible to keep the gas turbine group 1 1 available in idle mode. Furthermore, an operating state is possible in which both clutches 14 and 15 are closed; thereby driving, depending on the performance of the components, either the gas turbine group 1 1 and the electric machine 12 together the compressor, or the gas turbine group 1 1 is operated to on the one hand to drive the electric machine 12 for power generation and at the same time the compressor 13. In this case, for example, the excitation of the generator-operated machine 12 determines the distribution of the power of the gas turbine group on the compressor 13 and the machine 12. The thus provided ability to adjust by means of variable excitation of the generator and variable compressor power output and reactive power independently, is in deregulated Electricity markets also very lucrative. It is also possible to open both clutches 14 and 15 and to let the electric machine 12 rotate in the electricity grid without load and without drive as a phase shifter to provide the required reactive power components. It is also possible, in a manner not shown to those skilled in but readily familiar manner, to arrange the air turbine or expansion machine on a common shaft train with a compressor and an electric machine operable both as a generator and as an electric motor. In the same way as in the shaft train of the gas turbine group, clutches are then arranged between the expansion machine and the electric machine and between the compressor and the electric machine. The compressor is also connected to deliver storage fluid into the storage volume 30. In this case, the compressor on the shaft train of the expansion machine with the compressor on the shaft train of the gas turbine group may be connected both in parallel and in series. One like that realizing the distribution of the entire compressor capacity on two compressors enables high compressor performance without having to arrange extremely difficult to control extremely long compressor shaft strands; Although an arrangement of two compressors for the time seems more complex than the arrangement of only one compressor, the distribution of compressor power from a certain size allows the use of standard available compressors without having to make a redesign with respect to the rotor dynamics difficult to control new design. The operation of the compressor and expansion machine and the switching states of the clutches will be apparent to those skilled in the embodiments of the shaft train of the gas turbine group itself. In the loading operation of the accumulator position the obturator 34 is open, and the shut-off and / or actuator 35 is usually closed. Fluid compressed by the compressor 13 is cooled in a cooler 32 and flows through the open obturator 34 into the storage volume 30. Furthermore, in this flow path, a check member 31 is arranged, which reliably prevents a backflow of fluid into the compressor. In the power operation of the accumulator system, the gas turbine group 11, which comprises a compressor 111, a combustion chamber 112, and a turbine 113, generates an exhaust gas mass flow mo. The exhaust gas mass flow mo flows into a flow branching element 41, in which a controllable exhaust gas flap is arranged. By means of the flap arranged in the branch 41, it is possible to divide the exhaust gas mass flow mo into a first partial flow mi and a second partial flow rri2. The first partial flow flows into a heat exchanger 42, which can be flowed through from the storage volume 30 in countercurrent to the exhaust gas in a heat-absorbing part with storage fluid. In this way, the storage fluid can be heated and the waste heat of the gas turbine group can be implemented in the air turbine 21. The second partial flow flows off via a chimney 43. In the interest of a good use of energy, it is of course desirable, the second part of the flow, without Use of waste heat flows out to keep as small as possible. It is clear that one of the substreams can easily become zero. While the first partial flow of the exhaust gas of the gas turbine group flows through a heat-emitting part of the heat exchanger 42, a heat-absorbing part 51 of the heat exchanger can be acted upon by the adjusting and / or shut-off device 35, which is also referred to as "wellhead", with storage fluid from the storage volume 30 The mass flow of the storage fluid flowing to the heat receiving part 51 of the heat exchanger is m_HEx designated. The storage fluid is passed downstream of the heat exchanger via an actuator 52 to the expansion machine 21. Furthermore, a mixer 55 is arranged downstream of the heat exchanger in the flow path of the storage fluid. The mixer 55 can be supplied via a bypass line of the heat exchanger unheated storage fluid. Thus, in the mixer 55, the temperature of the recirculation machine 21 incoming storage fluid can be reduced. Furthermore, downstream of the heat-absorbing portion of the heat exchanger, a blow-off, bypass valve, 53 is arranged, via which a Abblasmassenstrom or bypass mass flow rriD of the storage fluid can be discarded after flowing through the heat-absorbing portion 51 of the heat exchanger, for example, in the case of air as storage fluid drained or is recooled and fed back into the storage volume 30 by means of a compressor. For controlling and regulating the storage system, a control unit 60 is arranged. The control unit comprises an input interface which receives a plurality of input signals 61 which characterize the operating state of different components of the storage system. The control unit 60 is configured such that it forms from the input signals 61 control signals 62, which are passed through an output interface to actuators of the storage facility. These include, for example, control variables for controlling the shut-off and / or actuators 34, 35, 52, 53 and 54 or for the exhaust valve in the flow divider 41. The configuration of the control unit 60 takes place for example via a processor, not shown, which is configured by a digital code accordingly. This digital code is stored on a data carrier 63, and is loaded into the control unit, for example, at the start of the control unit. The data carrier can, as shown, be an external storage medium; but as a data carrier, a non-volatile memory module or any other suitable storage medium can be used. In the power operation of the storage system, the heat exchanger 42 is flowed through by the hot exhaust gas mass flow of the gas turbine group whose temperature is, for example, values from 550 to 580⁰C or 600⁰C can reach, and readily deviations from these values are possible. The flow mass flow of the heat-absorbing portion 51 of the heat exchanger 42 is so dimensioned that the temperature T_ΘX does not exceed a permissible maximum value at the exit from the heat exchanger. This ensures that overheating of the heat exchanger apparatus is avoided. The controllable branch 41 makes it possible to operate the gas turbine group even when no storage fluid is available. The entire exhaust gas mass flow is then discharged, bypassing the heat exchanger via the chimney 43. By means of the shut-off and / or control element 35, also referred to as "wellhead", a constant pressure PHEX of, for example, 60 bar is set in the heat-absorbing part of the heat exchanger, of course, variable pressures can also be set such that a sliding pressure mode is realized. During operation of the expansion machine 21, the mass flow is adjusted such that the temperature of the storage fluid at the exit from the heat exchanger corresponds to a desired value, and for example 30⁰C or 50⁰C is below the temperature of the exhaust gas of the gas turbine group. This allows the best possible utilization of the storage fluid, because a maximum mass-specific enthalpy gradient is set via the expansion machine 21. In a cold start of the storage system, it is now possible that the storage fluid expansion machine required for the heat exchanger Mass flow with the existing temperature is not able to absorb. For example, if a derivative of a steam turbine is used as a relaxation machine 21, which has no heat shields, especially on the rotor, and no cooling possibility, it may only be warmed up slowly and / or accelerated to nominal speed, so that the allowable voltages in the rotor are not exceeded in the other case could lead to serious mechanical damage. It is known, for example, to start steam turbines under voltage control. In this case, mechanical stresses are determined in the rotor, and accelerating to rated speed takes place the slower, the greater the voltages. This is known as voltage-controlled starting. Further limiting factors in the exposure of the expansion machine with heated storage fluid, for example, be temperature gradients at the inlet flange of the housing. Another limitation results from the temperature or a temperature gradient at the outlet from the expansion machine. This range is generally intended for low temperatures, for example, below 100⁰C and lower. At low speeds, however, the temperature of the storage fluid flowing through the expansion machine falls only slightly due to the step kinematics, so that even if the temperature at the inlet of the expansion machine is within a permissible range, exceeding the allowable temperature at the outlet of the expansion machine is able to occur. Even at low power, or idling at rated speed, this effect can occur due to the low mass flow and the associated low pressure ratio of the expansion machine. It is therefore at least one temperature TAT of the expansion machine, for example, a housing temperature and / or a fluid temperature and / or a rotor temperature at the inlet and / or outlet of the expansion machine and / or another suitable temperature of the expansion machine, and the rotational speed n_Aτ of the rotor of Relaxation machine measured and evaluated in the control unit 60. The control unit generates a control variable for the actuator 52. The actuator 52 controls the mass flow rriAT the relaxation machine so that allowable temperature and / or speed gradients are not exceeded. That is, during the startup process of the expansion machine 21, only a limited waste heat output of the gas turbine group can be utilized. In general, it is possible to bring the gas turbine group only very slowly to a high power output, and in this way to increase the exhaust gas mass flow mo and the temperature of the exhaust gas only slowly. Apart from restrictions, which can bring the operating regime of the gas turbine group 1 1 in this regard, this means that the power output of the storage system can be delivered at cold start with a long delay in the network. However, the ability to quickly deliver power to the grid provides a significant competitive advantage in today's liberalized electricity markets. Another possibility is to burden the gas turbine group with its maximum power gradient, while the actuator 52 of the expansion machine 21 is controlled in accordance with the above criteria so that the expansion machine is not overloaded and with their normal, cold start significantly lower speed and power gradients is approached. However, if the heat exchanger 42 is subjected to a high exhaust gas mass flow comparatively quickly due to the rapid startup and loading of the gas turbine group, the storage fluid mass flow must also be increased very rapidly in order to avoid overheating of the heat exchanger apparatus. That is, at the exit from the heat-absorbing portion 51 of the heat exchanger both the mass flow and the temperature are increased faster than the expansion machine is able to process this. Therefore, during such a starting operation, in which the heat exchanger 42 very quickly, for example, within 20 or 30 minutes after the synchronization or after the ignition of the Gas turbine group is already acted upon with a maximum thermal power, on the one hand, the actuator 54 is opened to direct non-warmed storage fluid to the mixer 55, and thus to lower the temperature of the storage fluid at the inlet to the expansion machine to a value below the temperature of the storage fluid at the exit from the heat exchanger and to regulate to a value compatible with the operating state of the expansion machine. An exploitable from the expansion machine in compliance with the allowable speed and temperature gradients mass flow m_AτT exceeding the proportion of the total mass flow ΓTIHEX is blown off as Abblasmassenstrom rriD via the actuator 53. The actuator 53 makes it possible always, even with fully closed actuator 52, to ensure at least erfoderlichen flow of the heat-absorbing portion 51 of the heat exchanger 42. Although this method allows fast power production by means of the gas turbine group, but is economically unfavorable insofar as the Abblasorgan 53 in particular during cold start a significant mass flow must be discarded unused at previously complex compressed storage fluid. The branching device 41 is therefore provided with a flap for flow deflection, which allows a variable flow distribution to the two outflow openings of the branch, such that variable proportions of the total exhaust mass flow mo to the heat exchanger and to a second branch of the branch in this case, so led to the chimney can be. The flap of the splitter is therefore designed so that it at least a third stationary operating position in addition to a first stationary operating position in which the entire exhaust gas mass flow is passed into the heat exchanger, and a second stationary operating position in which the entire exhaust gas mass flow is directed into the chimney in which a first partial flow of the exhaust gas to the heat exchanger and a second partial flow is passed into the chimney. With such an arrangement, it is possible, the thermal performance, with which the heat exchanger is applied, better to the Adjust thermal performance, which is usable by the expansion machine. In this way, the unproductively rejected Abblasmassenstrom ΓTID can be reduced. Ideally, the flap is infinitely adjustable within the splitter 41; In practice, however, this is relatively difficult to implement, which is why branching find application in which the flap has discrete intermediate positions for stationary operation. In itself, it is also possible, albeit less energy-efficient, to dispense with the branching device 41 and / or to dispense with the intermediate positions. In this case, however, much more storage fluid must be discarded unused via the blow-off member 53, which is required for heat removal from the heat exchanger, but is not usable in the expansion machine during the start-up process. The blower is also useful when an existing exhaust flap, as shown in the figure, is inoperative to further allow operation of the storage facility where the gas turbine group can operate independently of the thermal condition of the expansion machine. Furthermore, the blow-off member is used in a possible rapid shutdown of the expansion machine to relieve the expansion machine, and makes it possible to dissipate the residual heat from the heat exchanger and / or continue to operate the gas turbine group unrestricted. In the manner already described above, if the mass flow and temperature limitation of the storage fluid is not predetermined by the conditions at the inlet of the expansion machine, the start of the expansion machine can be accelerated by the speed increase of the expansion machine is supported by the electric motor-driven generator. In this way, on the one hand, the mass flow of storage fluid which the expansion machine can utilize rises faster. This means that less energy has to be discarded in the form of storage fluid which has been rejected via the discharge element 53 and exhaust gas of the gas turbine group which has been passed unused through the chimney. This will start the boot process again more energy efficient. Furthermore, the expansion machine 21 is able to deliver faster power into the electricity grid, which also offers an economic advantage. The generator 22 of the expansion machine 21 is therefore provided on its electrical side with a starting aid. Such starting devices are known per se from the generators of gas turbine groups and the drive motors of compressors. Also, the electric machine 12 is provided with such a starting device, which is known in the art but in this context per se, and which is therefore not shown explicitly in the figure. While gas turbine groups require such a starting device, so that their compressor is brought to a speed which ensures a minimum mass flow necessary for igniting the combustion chamber, steam and air turbines are usually started by the machines are acted upon with working fluid; an external starting device is not necessary per se. The generator 22 of the expansion machine 21 is connected in a known per se via a transformer 71 and a power switch 73 to the electricity grid. For the sake of clarity, only a schematic course is shown instead of the usual three phases of the three-phase network. Between the transformer 71 and the generator 22, the current guide on two branches, which can be selected via switches 74 and 75. In the power mode of the expansion machine, the switches 73 and 75 are closed and the switch 74 is opened, and the generator 22 feeds electrical power into the network 70. When starting the expansion machine, the switches 73 and 74 are closed, and the switch 75 is open. The generator 22 is then operated by an electric motor and mains asynchronous. In this case, the frequency converter 72, for example, a so-called static frequency converter, Static Frequency Converter, SFC, the AC frequency of the network in a manner familiar to the skilled worker in such a way that it is recoverable from the non-synchronous electric motor operated generator. In this way, the acceleration of the expansion machine can be supported be avoided, thereby avoiding the problem of excessive increase in the temperature at the outlet of the expansion machine at low speeds and at the same time the Anfahrgradient the expansion machine is increased. In sum, the expansion machine can accelerate faster to rated speed and the generator 22 are operated in power operation on the network, as would be possible if the expansion machine would be accelerated only by the performance of the flowing storage fluid. In connection with FIG. 2, the starting process of the storage system from FIG. 1 will now be explained, in which the exhaust flap of the branching device 41 has two discrete stationary intermediate positions in addition to the positions in which the entire mass flow is conducted either to the chimney or to the heat exchanger. FIG. 2 plots the course of various mass flows and the power PGT of the gas turbine group and PAT of the relaxation machine over time. It should be noted that the representation is not to scale, but only qualitatively different gradients, in order to facilitate the understanding of the startup process. In particular, the representation in FIG. 2 serves to explain how the exhaust gas mass flow ΓTID is minimized by means of the start-up process characterized in the claims and the storage system characterized in the device claims, and at the same time the load rate is maximized. In a first phase of the starting process, which is not shown in the diagram, and which adjoins the presentation to the left, so to speak, the gas turbine group is ignited and accelerated to rated speed. The flap of the splitter 41 is set so that the entire exhaust gas mass flow of the gas turbine group is passed past the heat exchanger 42. The flap is brought into a first position at the time t1, such that a first part Ström m 1 of the exhaust gas mass flow Mθ is passed into the heat exchanger. The flow control of the heat exchanger reacts with a caused by the thermal inertia of the heat exchanger delay on the application of hot exhaust gases. The Actuator 53 is opened, and the flow through the heat-absorbing portion 51 of the heat exchanger is adjusted so that overheating of the heat exchanger is avoided. As a result, the mass flow ΓTID initially increases. As soon as possible, the mass flow rriAT (not shown) is increased in order to start the heating process of the expansion machine, and accordingly the mass flow ΓTID is lowered. At time t2, the gas turbine group is synchronized and its power is increased with a normal power gradient. A gas turbine group that is not specifically designed for peak load typically reaches its maximum power within about 20 minutes to half an hour after synchronization, with deviations from these exemplary times readily possible. In the example shown, the gas turbine group has reached its maximum power at time t4 and remains there; However, it is readily possible in the illustrated device and the method explained here to operate the gas turbine group independently of the other starting process as desired according to the power requirements of the network. With increasing power of the gas turbine group also increases their exhaust gas temperature and thus the heat to be converted in the heat exchanger thermal performance. Therefore, after the synchronization, the storage fluid mass flow rriHEx in the heat exchanger increases. Because this increasing mass flow and the rising temperature can not be processed immediately by the expansion machine, the blow-off mass flow mo also increases. In the period between t3 and t4 an adjustable Vorleitreihe the compressor of the gas turbine group is opened, which is why the exhaust gas mass flow mo and increase in the same position of the exhaust valve in the manifold 41, the mass flow mi in the heat-emitting part of the heat exchanger 42. This results in an increased increase of the storage fluid mass flow ΓTIHEX by the heat exchanger. Meanwhile, the expansion machine 21 is further warmed up and is therefore able to process a larger mass flow. At the same time, the temperature of the relaxation machine inflowing storage fluid can be lowered by the storage fluid in the mixer 55, a non-heated storage fluid mass flow is added, which is measured by the actuator 54. Therefore, the mass flow which can be utilized by the expansion machine increases, and the blow-off mass flow rriD does not completely complete the increase in the storage-mass fluid flow rriHEx, because the expansion-type machine is increasingly able to utilize larger mass flows. As has already been stated several times, the mass flow of the expansion machine can be additionally increased faster when the expansion machine is started up with the assistance of the electric motor-driven generator and accelerated to nominal speed. After reaching the maximum power of the gas turbine group, a first constant value for the entire storage fluid mass flow rri_HEx. The blow-off mass flow steadily decreases. When the bleed air flow ΓTID falls below a threshold value, the flap in the distributor 41 is set to a second intermediate position at time t5. In principle, this step can also be waited until the blow-off mass flow has returned to zero; In the interest of a fast power output, however, this step takes place in the exemplary embodiment already when the discharge mass flow has fallen below a limit value. The partial flow mi of the total exhaust gas mass flow, which flows to the heat exchanger, increases. Accordingly, the storage fluid mass flow ΓTIHEX increases, which increase is retarded by the thermal inertia of the heat exchanger. Due to the sudden increase in the thermal power to be converted, the blow-off mass flow rriD initially increases, and then decreases again as the storage-fluid expansion machine heats up. At time t7, the exhaust flap is brought in the branching in a position in which the entire exhaust gas mass flow of the gas turbine group flows through the heat exchanger. This results in a further increase of the storage fluid mass flow rriHEx and the Abblasmassenstroms ΓTID, the latter with progressive warming up of the storage facility on not shown, for the expert but traceable way goes back to zero. At time t6, the storage fluid relaxation machine is synchronized and its power P_AT increased. The storage fluid relaxation machine substantially reaches its maximum power output at about the same time the bleed air flow, rriD, has returned to zero. The operationally necessary loss of storage fluid results from the integral below the curve of the Abblasmassenstroms. Of course, this will be the smaller, the faster the storage fluid relaxation machine is able to process a high mass flow of high temperature storage fluid. Furthermore, this loss is the smaller, the more stationary intermediate positions the exhaust valve in the manifold 41, that is, the smaller the mass flow jumps are in the heat-emitting part of the heat exchanger. In the case of a continuously variable exhaust flap, these losses can be reduced to zero or at least to near zero. The storage fluid loss can be further reduced, as described above, by reducing in the mixer 55 the temperature of the storage fluid flowing to the storage fluid expansion machine and adjusting it to a temperature compatible with the operating condition of the storage fluid expansion machine. Likewise, the start-up assistance of the expansion machine by the electric motor-driven generator can further reduce this loss. FIG. 3 shows a further embodiment of the pressure accumulator system. This differs from the pressure accumulator system shown in Figure 1 in that instead of the mixer 55, an injection cooler 57 is arranged, which is metered via an actuator 56, a liquid mass flow, which is injected into the injection cooler in the storage fluid. Due to the evaporation of the liquid, there is a cooling of the storage fluid recirculation machine inflowing storage fluid. In this way it is also possible to lower the temperature so that the storage fluid expansion machine can utilize a greater proportion of the stored through the heat exchanger storage fluid. In this embodiment, it is advantageous over FIG. 1 that no additional storage fluid has to be expended for cooling the storage fluid; in return, liquid must be stored or demineralized and purified liquid provided. In a manner analogous to the statements made in connection with FIG. 1, a further compressor may also be arranged on the shaft train of the expansion machine here; detailed explanations are unnecessary in the light of the statements made there. In the light of these statements, the person skilled in the art will be presented with a large number of further embodiments within the scope of the invention. The embodiments illustrated for explanation of the invention may of course not be conclusive. As already indicated above, can be dispensed in principle to the adjustable exhaust flap, even if this requires losses during startup efficiency, because more storage fluid must be enforced during the startup of the expansion machine through the heat exchanger, not the entire masses Ström can be utilized by the expansion machine , which means that storage fluid must be discarded unused via the blow-off. In particular, a gas turbine group with sequential combustion, as has become known from EP 620 362, can continue to be used. For example, two or more gas turbine groups may act on a common heat exchanger. Furthermore, the loading compressor 13 may be arranged on a separate shaft train with a drive machine; Furthermore, several compressors connected in series are generally used here, but this is not shown because it is not essential to the invention. Beyond these examples, embodiments of the invention are of course included. LIST OF REFERENCE NUMBERS

[0022] 1 gas turbine group

12 motor-generator unit, electric machine

13 compressor

14 clutch

15 clutch

21 storage fluid expansion machine; air turbine

22 generator

30 storage volume

31 non-return member

32 cooler

34 shut-off

35 shut-off and / or actuator; "Wellhead"

41 flow branching element; Branching, with

exhaust flap

42 heat exchangers

[0036] 43 fireplace

51 heat-absorbing part of the heat exchanger

52 actuator, control valve

53 Actuator, bypass valve

54 actuator, mixing valve

55 mixers

56 actuator

57 injection cooler

60 control unit

[0045] 61 input signals of the control unit

[0046] 62 output signals of the control unit, manipulated variables

63 data carriers

[0048] 70 electricity grid

71 Mains transformer

72 frequency converter [0051] 73 power switch

[0052] 74 starting switch

75 circuit breaker

[0054] 1 1 1 Compressor of the gas turbine group

[0055] 1 12 combustion chamber

[0056] 113 turbine of the gas turbine group

[0057] DrehzahlAT rotational speed of the expansion machine

Mo exhaust gas mass flow

[0059] mi first partial flow of the exhaust gas mass flow

[0060] rri2 second partial flow of the exhaust gas mass flow

[0061] rriAT mass flow of the expansion machine

[0062] rriD blow-off mass flow, bypass mass flow

[0063] rriHEx storage fluid mass flow through the heat exchanger

PHEX pressure of the storage fluid in the heat exchanger

PGT power output of the gas turbine group

PAT power output of the expansion machine

TAT temperature of the expansion machine

Tex temperature of the storage fluid after heat exchanger

Claims

claims

A method of operating a pressure accumulator, said accumulator comprising: a gas turbine group (11), a storage volume (30) for a pressurized storage fluid, a storage fluid expansion machine (21), and a heat exchanger (42) which on a heat exiting side is passed through the gas turbine group exhaust gas and the heat receiving side (51) is arranged in a flow path from the storage volume (30) to the expansion machine (21), and which method comprises bringing the gas turbine group to an operating speed, a generator of the gas turbine group with to synchronize an electricity grid and to operate the gas turbine group for power delivery into the electricity grid, to pressurize the heat exchanger (42) with storage fluid (rriHEx) and exhaust gas of the gas turbo group (mi), and to provide heated storage fluid for the storage fluid expansion machine characterized by Temperature of the d The control unit provided storage fluid independent of the power output (PGT) to control the gas turbine group.

2. The method according to claim 1, characterized by controlling the temperature of the storage fluid provided for the expansion machine so that the temperature and / or the temperature gradient of the expanded storage fluid at the outlet from the expansion machine remains below a threshold value.

3. The method according to any one of claims 1 or 2, characterized by controlling the temperature of the storage fluid provided for the expansion machine so that the temperature gradient of the rotor temperature and / or the housing temperature at the outlet of the expansion machine remains below a limit.

4. The method according to any one of the preceding claims, characterized by accelerating the expansion machine to rated speed, and to support the acceleration of the expansion machine by a motor operation of the relaxation machine associated generator.

5. The method according to any one of the preceding claims, characterized by the expansion _machine for the first time to supply a storage _fluid mass flow when the storage _{fluid temperature} (T _ΘX ) has reached a minimum value at the exit from the heat exchanger.

6. The method according to any one of the preceding claims, characterized by the expansion machine to supply a first storage fluid mass flow substantially immediately after the synchronization of the gas turbine group.

7. Method according to one of the preceding claims, characterized by controlling the temperature (T _9x ) of the storage fluid at the exit from the heat exchanger (42; 51).

8. The method according to claim 7, characterized by passing a storage fluid mass flow (ΓTIHEX) through the heat receiving side (51) of the heat exchanger (42), and adjust the storage fluid mass flow (rriHEx) so that the temperature (T _ΘX ) at the exit from the Heat exchanger reaches a target value, comprising a first of the storage fluid relaxation machine utilizable partial mass flow (rriAτ) to the expansion machine (21) to pass and a second, the first partial mass flow masses ström (ΓTID) bypassing the storage fluid expansion machine.

9. The method according to claim 8, comprising, the actuator for the first partial mass flow (52) to operate as an actuator for the control of at least one operating variable of the expansion machine, and the actuator (53) for the second partial mass flow (ΓTID) to operate as an actuator for controlling the temperature at the exit from the heat exchanger.

10. The method according to any one of the preceding claims, characterized by varying the heat input into the heat exchanger.

1 1. A method according to claim 10, characterized in that the heat exchanger to supply a variable portion (mi) of the gas from gas mass flow (mo) of the gas turbine group.

12. The method according to any one of the preceding claims, characterized by reducing the temperature of the storage fluid before entering the storage fluid expansion machine.

13. The method according to claim 12, characterized by mixing the heated storage fluid downstream of the heat exchanger and upstream of the expansion machine unheated storage fluid.

14. The method according to any one of claims 12 or 13, characterized by introducing a liquid mass flow, in particular a water mass flow, in the heated storage fluid downstream of the heat exchanger and upstream of the expansion machine.

15. The method according to any one of the preceding claims, characterized by determining a desired temperature of the storage fluid flowing to the expansion machine depending on the thermal state of the expansion machine.

16. The method according to any one of the preceding claims, comprising, when passing the gas turbine group bypassing the entire exhaust gas mass flow of the gas turbine to the heat exchanger, after reaching the rated speed of the gas turbine group to direct a first partial mass flow of the exhaust gas mass flow through the heat exchanger, a mass flow of the storage fluid to pass through the heat-absorbing portion of the heat exchanger to regulate a required storage fluid mass flow so that an allowable maximum temperature and / or a maximum allowable temperature gradient of the storage fluid is not exceeded when exiting the heat exchanger, at least a first partial flow of the storage fluid in the To direct relaxation machine, to set the first partial flow of the storage fluid so that a permissible limit of the rotor acceleration of the expansion machine and / or a permissible limit of the temperature gradient of the expansion machine is not exceeded, to blow off a second, the first partial flow exceeding partial flow of the storage fluid mass flow downstream of the heat exchanger , And to operate the gas turbine group regardless of the thermal state of the heat exchanger and the expansion machine

17. The method according to claim 16, comprising adjusting the first partial mass flow of the exhaust gas mass flow such that the required storage fluid mass flow can be absorbed as much as possible from the storage fluid expansion machine.

18. The method according to any one of claims 16 or 17, characterized by cooling the heated storage fluid prior to introduction into the expansion machine, such that allowable temperature gradients are not exceeded.

19. The method according to any one of the preceding claims, characterized by operating the controller in a closed loop.

20. Pressure accumulator, comprising a gas turbine group (1 1), a storage volume (30) for a pressurized storage fluid, a storage fluid expansion machine (21), and a heat exchanger (42) which on a heat emitting side of the gas turbine exhaust gas (mi ) is flowed through and its heat-absorbing side (51) in one Flow path is arranged from the storage volume to the expansion machine, characterized in that in the exhaust gas flow path of the gas turbine group upstream of the heat exchanger, a branch (41) is arranged with an adjustable exhaust flap arranged therein for flow diversion and variable flow distribution, such that variable proportions of the exhaust gas mass flow to the heat exchanger and can be conducted to a second branch of the branching.

21. Accumulator according to claim 20, characterized in that the flap in a first stationary operating position, in which the entire exhaust gas mass flow is passed into the heat exchanger, a second stationary operating position, in which the entire exhaust gas mass flow is passed into the second branch, and at least a third stationary Betiebsposition in which a first partial flow of the exhaust gas to the heat exchanger and a second partial flow is passed to the second branch.

22. Pressure accumulator according to one of claims 20 or 21, characterized in that in the flow path from the heat receiving side (51) of the heat exchanger to the expansion machine (21) a means (55; 57) is arranged for lowering the temperature of the heated storage fluid.

23. Pressure accumulator according to claim 22, characterized in that for lowering the temperature, a means for introducing unheated storage fluid and / or a means for introducing liquid into the heated storage fluid is arranged.

24. Pressure accumulator, comprising a gas turbine group (1 1), a storage volume (30) for a pressurized storage fluid, a storage fluid expansion machine (21), and a heat exchanger (42) which on a heat emitting side of the gas turbine exhaust gas (mi is flowed through and the heat receiving side (51) is arranged in a flow path from the storage volume to the expansion machine, characterized in that in the flow path of the Storage fluid from the heat exchanger to the expansion machine a branching element is arranged, wherein a branch of the branching element a second flow path with a shut-off and / or actuator (53) adjoins, which second flow path bypasses the expansion machine, such that via the second flow path at least a partial flow (ΓTID) of the effluent from the heat exchanger storage fluid bypassing the expansion machine can be derived.

25, control unit (60) which is configured to cause a pressure accumulator system for carrying out a method according to one of claims 1 to 19.

26. Digital code, which is suitable for configuring a control unit such that it causes a pressure accumulator system for carrying out a method according to one of claims 1 to 19.

27. Data carrier (63) on which a digital code according to claim 26 and / or its source code is stored.