WO2005040581A1

WO2005040581A1 - Power station unit

Info

Publication number: WO2005040581A1
Application number: PCT/EP2004/052574
Authority: WO
Inventors: Rolf Althaus
Original assignee: Alstom Technology Ltd
Priority date: 2003-10-23
Filing date: 2004-10-19
Publication date: 2005-05-06
Also published as: DE112004002066A5

Abstract

A CAES unit comprises an atmospheric burner (11), arranged downstream of the expansion machine (2). The flue gas thus generated flows through a heat exchanger (9). The storage medium, flowing from the reservoir (1) into the heat exchanger is heated by heat exchange. In said unit, the storage medium is directly used for the combustion of a fuel without the need to expose the expansion machine to corrosive flue gases.

Description

Power plant

Technical field

The present invention relates to a power plant according to the preamble of claim 1 and a preferred operating method.

State of the art

So-called CAES power plants are well known in the prior art, for example from US 5,537,822. In these power plants, a storage volume is filled with a tense storage fluid, in particular air. In times of high electricity demand, the stored fluid is expanded while working in an engine that drives a generator. For a given pressure ratio across the engine, the higher the temperature of the storage fluid at the inlet to the engine, the higher the utilization of the storage fluid.

No. 5,537,822 proposes to carry out the expansion of the storage fluid in several steps and to heat the fluid before each expansion step. This requires a lot of equipment, since several engines and several heat exchangers have to be arranged in series in terms of flow. alternative proposes US 5,537,822 to heat the storage fluid prior to expansion in the engine by means of the waste heat from a gas turbine group. This requires the arrangement and operation of a gas turbine group.

Presentation of the invention

The invention seeks to remedy this. The invention characterized in the claims is based on the object

Power plant of the type mentioned, which can avoid the disadvantages of the prior art. In particular, the invention is intended to specify a CAES power plant in which the storage fluid can be brought to the highest possible temperature beforehand, without the need for expensive auxiliary units. The arrangement of additional fireplaces should also be avoided, since their number is often strictly limited within the scope of the building and operating permits.

According to the invention, this object is achieved using the entirety of the features of claim 1.

The essence of the invention is therefore to design the power plant in such a way that the storage fluid in the engine itself is completely expanded, that is to say essentially to atmospheric pressure, and then flows through an atmospheric combustion chamber, a fuel being burned in the expanded storage fluid, and the flue gas produced during combustion flows through the primary side of a heat transfer apparatus, it being cooled in the heat exchange with the storage fluid flowing to the engine. The cooled flue gas then flows off as exhaust gas. The storage fluid removed from the storage volume is heated beforehand to relax in the engine, as a result of which it is available via the engine standing mass-specific enthalpy gradient increases. This means that a lower storage fluid mass flow is necessary to generate a certain useful output, or vice versa, with a given storage pressure and volume, more electrical energy can be generated. Air is particularly suitable as the storage fluid, since it is available in practically unlimited quantities and can be used without difficulty to burn a fuel in the atmospheric combustion chamber.

The arrangement according to the invention is distinguished by a whole series of advantages: on the one hand, the storage fluid is used directly for the combustion of the fuel. On the one hand, this has the advantage that complex devices for conveying combustion air are eliminated, since the relaxed storage fluid has to flow through an outflow tract of the engine anyway. In addition, there is no need for a further chimney to be arranged next to an exhaust chimney. On the other hand, the combustion only takes place downstream of the engine, and the storage fluid flowing to the engine is heated in indirect heat exchange. This means that the engine is traversed by storage fluid, generally air, instead of aggressive smoke gases. Protective measures against aggressive flue gases can therefore be dispensed with. It is therefore possible to use much less expensive engines than would be the case if smoke gases were applied. In particular, steam turbines with minor modifications can be used as expansion engines for the storage fluid; it is advantageous if the inlet temperature of the storage fluid is limited in order to remain compatible with the permissible inlet temperatures of the turbine, for example around 500 ° C. to 600 ° C. or even 650 ° C., without using high-temperature materials. A turbine which is intended for the expansion of a non-aggressive storage fluid and therefore does not require any special measures against aggressive and corrosive media is hereinafter referred to collectively as an air turbine. The power plant system according to the invention can be implemented very advantageously and with little effort with exactly one single expansion engine. In an advantageous embodiment, the secondary-side flow path of the heat transfer apparatus through which the tensioned storage fluid flows is essentially immediate

Fluid connection with the high pressure side of the expansion engine, such that the heated storage fluid flows to the expansion machine without flowing through further apparatus. It is also advantageous in this sense to establish an essentially direct fluid connection from the low-pressure side of the expansion engine to the atmospheric one

Combustion chamber manufactured. Another advantage can be seen in the informal compatibility of the fluid mass flows flowing through the heat transfer apparatus on the primary and secondary sides, on the basis of which the temperature conditions at the inlet and outlet from the heat exchanger apparatus are essentially only a function of its dimensioning.

A flue gas cleaning catalytic converter is arranged with the greatest advantage downstream of the atmospheric combustion chamber. Because of the temperature window required for the catalytic converter to function, it is advantageously arranged within the heat transfer apparatus, specifically at a point at which the flue gases emerging from the atmospheric combustion chamber have already cooled down sufficiently in the heat exchange with the tensioned storage fluid to damage the catalytic converter to avoid, but still have a temperature at which a sufficient catalytic effect is ensured. This means that the catalyst is arranged within the primary-side flow path of the heat transfer apparatus downstream of a first and upstream of a second part of the primary-side flow path.

In a further embodiment of the invention is further downstream of the flow path of the heat transfer apparatus and a high-pressure combustion chamber is arranged upstream of the expansion machine. This enables a further increase in the mass flow-specific power output, but, as indicated above, in return requires corresponding measures on the expansion machine, because aggressive smoke gases then flow through it and the components are exposed to higher temperatures. In this case, the turbine part of a gas turbine group can preferably be used as an expansion engine. In this embodiment, the temperature at the inlet of the expansion machine is preferably determined directly or indirectly, and the fuel mass flow, in a suitable manner known per se

High-pressure combustion chamber is controlled by adjusting a fuel mass flow actuator to keep this temperature at a setpoint or to limit this temperature to an allowable maximum value.

In one mode of operation of the power plant according to the invention, the

Useful power of the expansion engine regulated by preferably intervening in the storage fluid mass flow. This requires suitable means for determining the useful power, preferably as the power of a generator driven by the expansion engine. A power controller, which intervenes as a manipulated variable on a storage fluid mass flow control element, is preferably connected to the power determined in this way as a controlled variable.

In a further mode of operation, the storage fluid temperature at the inlet to the expansion machine is determined in a suitable manner, either directly or indirectly, and is regulated by interventions in a fuel mass flow control element of the atmospheric combustion chamber.

In a further advantageous mode of operation, the temperature of a flue gas cleaning catalytic converter arranged in the flue gas path downstream of the atmospheric combustion chamber, and / or the temperature of the flue gas flowing into it, is measured and regulated Limit control can be understood. A continuous controller as well as a discontinuous controller, for example a two-point controller, can also be used. Such a regulation ensures that the catalytic converter is not permanently damaged due to overheating. Furthermore, the temperature can be regulated in a temperature window that is conducive to catalytic flue gas cleaning.

In yet another advantageous embodiment, the temperature of the flue gas is determined downstream of the primary-side flow path of the heat transfer apparatus or at its outlet, and is regulated to a setpoint value or to the compliance with an allowable minimum value. On the one hand, this can ensure that the dew point of corrosive flue gas components is not undershot. In this regard, the lower limit temperature can also vary depending on the fuel, and may be higher, for example, with oil firing than with natural gas firing. In one mode of operation, the flue gas temperature can be regulated to the lowest possible value above this dew point, as a result of which the exhaust gas heat losses are minimized and the fuel utilization is thus improved.

Further advantageous embodiments of the power plant according to the invention and advantageous modes of operation are evident from the subclaims and in the light of the exemplary embodiments.

Brief description of the drawing

The invention is explained in more detail below on the basis of exemplary embodiments illustrated in the drawing. In detail: FIG. 1 shows a first preferred embodiment of the invention; Figure 2 shows another preferred embodiment of the invention. Elements which are not immediately necessary for understanding the invention are omitted. The exemplary embodiments are to be understood purely as instructions and should not be used to restrict the invention characterized in the claims.

Way of carrying out the invention

The power plant system shown in FIG. 1 basically comprises a storage volume 1 for storing a compressed gas, in particular air, and a turbine 2 for relieving pressure on the storage fluid, a generator 3 being driven which generates a useful power PAct. The relaxed storage fluid is through a

Exhaust chimney 4 released into the atmosphere. To charge the accumulator 1, a compressor unit 5 is arranged, the specific configuration of which is not relevant to the invention; a turbocompressor 6 with a drive motor 7 and a cooler 8 are shown by way of example. In times of low electricity demand and correspondingly low electricity prices, the

Compressor unit operated to charge the memory 1 with compressed air. As mentioned in the introduction and easy to understand, the specific enthalpy gradient across the turbine is very small when air flows in and is released from the accumulator at approximately ambient temperature of the turbine 2. This means that a lot of storage fluid is required to generate a certain electrical energy, in other words, the electrical power that can be generated with a stored volume at a given storage pressure is thereby limited. According to the invention, a heat transfer device 9 and a combustion chamber 11 are therefore arranged. The combustion chamber 11 is arranged downstream of the turbine 2. Apart from the dynamic pressure of the flowing fluid and pressure losses in the further flow path, the pressure of the storage fluid in the combustion chamber corresponds 11 the ambient pressure. It is therefore justified to speak of an atmospheric combustion chamber. The heat transfer device 9 is arranged such that the primary-side flow path, through which a heat-emitting fluid flows, is arranged in the flow path of the relaxed storage fluid downstream of the atmospheric combustion chamber 11. The flow path on the secondary side, through which the heat-absorbing fluid flows, is arranged in the flow path of the storage fluid between the storage 1 and the turbine 2. In other words, the same fluid flow flows through the primary side of the heat transfer device 9 and the secondary side of the heat transfer device 9. The relaxed working fluid is supplied with fuel in the atmospheric combustion chamber 11 and burned. The resulting hot flue gas is fed to the heat transfer device 9 and cooled when flowing through the heat exchange with the storage fluid flowing from the storage volume 1 to the turbine 2. At the same time, the fluid flowing on the secondary side from the accumulator to the turbine is heated in the heat exchange. The fluid flows on the primary side and the secondary side flow in counterflow in the interest of the best heat exchanger effect. Due to the heating of the storage fluid before entering the expansion engine 2, a larger mass-specific enthalpy gradient is available.

Accordingly, at a certain pressure ratio, a lower mass flow is required to generate a certain useful power, and more electrical energy can be generated with the storage fluid stored in a given storage volume. With regard to the power yield, it is of course the more favorable the higher the temperature of the storage fluid at the inlet into the storage fluid expansion machine 2. On the other hand, the materials used and other boundary conditions set limits for a maximum permissible temperature. It is therefore extremely advantageous to use suitable means to determine the temperature at the inlet of the relaxation machine 2 and to limit it to a maximum value or to as close as possible to it Set maximum value lying setpoint. A possible implementation of this regulation is explained in more detail below.

The invention thus makes it possible to heat the storage fluid before entering the expansion engine without the engine being subjected to a flue gas flow; only fluid, in particular air, flows through the engine. In the embodiment shown, the components of the expansion machine are not subjected to aggressive flue gas components, as a result of which the expansion machine can be implemented more easily and more cheaply. Nevertheless, essentially only a single media stream and only one chimney are required because the storage fluid is used to burn the fuel at the same time. Furthermore, no specific devices for treating and conveying combustion air from an external furnace have to be provided. The combustion of a fuel creates pollutant components such as nitrogen oxides. Although the pollutant values can be greatly reduced by suitable measures during combustion, the strictest emission regulations require the use of

Exhaust gas treatment measures. In the illustrated embodiment, a flue gas purification catalyst 10 is disposed in the flue gas flow path downstream of the atmospheric combustion chamber. When using a

Flue gas cleaning catalytic converter, its operating temperature window must be observed. Too high a catalyst temperature leads to irreversible damage to the catalyst. If the temperature is too low, no catalytic effect is achieved. The temperature of the flue gas at the exit from the atmospheric combustion chamber is generally too high for the catalytic converter. For best heat utilization, the flue gas is cooled in the heat transfer device 9 to a temperature which is too low for the catalytic exhaust gas purification. The catalytic converter is therefore arranged within the heat transfer device, in the primary-side flow path, downstream of a first part of the flow path and upstream of a second part of the flow path within the heat transfer device. In this way the temperature gradient advantageously divided over the heat transfer apparatus in such a way that a favorable temperature range for the catalyst is encountered in normal operation. This effect can also be achieved in an equivalent manner by dividing the heat transfer apparatus in two, the catalyst being interposed.

In the embodiment shown, a storage fluid mass flow control element 14 serves as an actuator for useful power control. The useful power is determined as the generator power PAct. This is compared with a desired value in a manner which is not shown but is readily familiar to the person skilled in the art. If the output decreases as a controlled variable, the actuator 14 is opened further and the storage fluid mass flow increases. If the power increases as a controlled variable, the actuator 14 is throttled more and the storage fluid mass flow decreases. The fuel mass flow supplied to the atmospheric combustion chamber 11, which is controlled via the fuel mass flow control element 13, is available as a further manipulated variable of the process. Three temperatures are relevant for the operation of the power plant shown. On the one hand, this is the temperature of the storage fluid at the outlet from the secondary-side flow path of the heat transfer apparatus or the temperature of the storage fluid at the inlet into the turbine 2, the exhaust gas temperature of the fluid at the outlet from the primary-side flow path of the heat transfer apparatus, as well as the catalyst temperature or the temperature of the flue gas directly upstream of the catalyst. According to one aspect of the invention, the power plant has means for determining one of these temperatures, which is used as a control variable for a control loop, while the position of the fuel mass flow control element 13 is used as a control variable for this control loop. It is now a question of process optimization, which of the three temperatures is regulated to a setpoint. If the temperature at the turbine inlet is regulated to the highest possible setpoint, this results in an operating mode with the best storage fluid utilization. Is the temperature of the flue gas downstream of the Heat transfer apparatus regulated to a setpoint, so the exhaust gas heat losses can be minimized, and the result is an efficiency-optimized operation. In the embodiment shown, the temperature of the catalyst is measured by means of a measuring point 15 and regulated to a desired value. If the measured temperature exceeds the setpoint or the upper limit of a setpoint interval, the actuator 13 is closed a bit. If the measured temperature falls below the setpoint or the lower limit of a setpoint interval, the actuator 13 is opened a little further. This results in the best possible flue gas cleaning effect of the catalytic converter. The mass flows flowing in the heat transfer apparatus on the primary and secondary sides are always identical except for the fuel mass flow. Given the dimensions of the heat transfer device, all three temperatures are therefore closely linked. This means that if one of the three temperatures is adjusted to a setpoint, they move

Fluctuations in the other two temperatures within comparatively narrow limits. In other words, the other temperatures are also controlled indirectly. It is nevertheless advantageous, in a manner not shown, but familiar to the person skilled in the art, to also monitor the temperatures which are not directly regulated in each case and to evaluate them in a safety circuit of the power plant, so that the flue gas does not fall below the dew point in the embodiment shown, and the thermal overload of the Expansion machine is avoided.

In principle, it is also possible to arrange a further combustion chamber downstream of the flow path of the heat transfer apparatus 9 on the secondary side and upstream of the turbine 2; the arrangement of an indirect firing is not sensible at this point when the power plant is designed according to the invention, although in principle it is possible. However, this arrangement of a combustion chamber upstream of the turbine 2 requires special measures so that it does not damage the turbine which is exposed to hot flue gases comes. In particular, the expansion turbine of a gas turbine group can be used in this case, which is advantageously used together with its combustion chamber. Because of the simplicity, however, according to a first aspect of the invention, the embodiment shown in FIG. 1 is considered advantageous, in which the flow path from the secondary side of the heat transfer device 9 to the expansion machine is realized essentially directly, without any intermediate devices.

The arrangement of a combustion chamber upstream of the expansion machine is advantageously implemented in the manner shown in FIG. 2. The

Utilized the fact that an operating temperature window of a catalytic converter of, for example, around 300 ° C to 350 ° C, whereby these temperatures can be significantly higher, depending on the catalytic converter, is quite comparable with the compressor end temperature of a gas turbine group with a pressure ratio between 10 and 15. In the power plant shown in FIG. 2, the catalytic converter 10 is arranged at the upstream end of the primary-side flow path of the heat transfer device 9. Furthermore, the power plant comprises a combustion chamber-turbine unit 16, comprising the combustion chamber 161 and the turbine 162 of a gas turbine group, in which the compressor has been omitted. In a manner not shown, upstream of the high-pressure combustion chamber 161, a portion of the storage fluid is discharged into the cooling air system of the gas turbine group. It is also highly advantageous that this storage fluid has a temperature which is at least approximately comparable to the cooling air branched off at a compressor outlet of a gas turbine group. The compressor-side shaft end drives the generator 3 directly. The power control of the generator power PAct takes place with the position of the storage fluid mass flow control element 14 as the control variable. The temperature of the catalyst is advantageously controlled with the position of the fuel mass flow control element 13 of the atmospheric combustion chamber as a control variable. In the present embodiment, the temperature at the inlet of the turbine 162 is not measured directly, but rather in a manner known per se Calculated from other variables, for example the turbine outlet temperature and the turbine pressure ratio. The temperature determined in this way is controlled by intervening in the fuel mass flow control element 17 of the combustion chamber 161. In this way, a power plant system according to the invention can also be constructed using largely standardized components, namely the complete combustion chamber-turbine unit 16.

LIST OF REFERENCE NUMBERS

1 storage volume, compressed air storage

2 expansion engine, expansion turbine

3 generator

4 chimney, exhaust chimney

5 compressor unit

6 compressors

7 drive motor

8 coolers

9 heat transfer apparatus

10 flue gas cleaning catalytic converter

11 atmospheric combustion chamber

13 fuel mass flow control element

14 storage fluid mass flow actuator

15 temperature measuring point

16 combustion chamber turbine unit

17 Fuel mass flow control element

161 combustion chamber, high pressure combustion chamber

162 turbine

PAct net power

Claims

claims

1. power plant, comprising a pressure accumulator (1) for a gaseous storage fluid, in particular a compressed air accumulator, an expansion engine (2; 162), in particular an expansion turbine, with an engine inlet on a high pressure side and an engine outlet on a low pressure side, a heat transfer device (9), which comprises a heat-emitting primary-side and a heat-absorbing secondary-side flow path, and an atmospheric combustion chamber (11), characterized by the following arrangement of the components mentioned: an upstream end of the secondary-side flow path of the heat transfer device is connected to the pressure accumulator; a downstream end of the secondary side flow path of the heat transfer apparatus is connected to the engine inlet; the engine outlet is connected to an upstream end of the atmospheric combustion chamber; a downstream end of the atmospheric combustion chamber is connected to an upstream end of the primary side flow path of the heat transfer apparatus.

2. Power plant according to claim 1, which comprises exactly one expansion engine.

3. Power plant according to one of the preceding claims, characterized in that the secondary flow path of the heat transfer apparatus is in substantially direct fluid communication with the high pressure side of the expansion engine.

4. Power plant according to claim 3, characterized in that the expansion engine is an air turbine (2).

5. Power plant according to one of the preceding claims, characterized in that the low-pressure side of the expansion engine (2; 162) is in substantially direct fluid communication with the atmospheric combustion chamber.

6. Power plant according to one of the preceding claims, characterized in that a catalyst (10) for exhaust gas purification is arranged in the primary-side flow path of the heat transfer apparatus (9).

7. Power plant according to claim 7, characterized in that the catalyst is arranged within the heat transfer apparatus, downstream of a first part of the primary flow path and upstream of a second part of the primary flow path.

8. Power plant according to one of the preceding claims, further comprising: means for determining the useful power (PAct) of the expansion engine, a storage fluid mass flow actuator (14); a power regulator; characterized in that the power controller is connected to the useful power of the expansion engine as a control variable and to the position of the storage fluid mass flow control element as a control variable.

9. Power plant according to one of the preceding claims, comprising: a fuel mass flow control element (13) for controlling the fuel mass flow to the atmospheric combustion chamber (1 1); Means for determining the temperature at the turbine inlet; a temperature controller; characterized in that the temperature controller is connected to the temperature at the turbine inlet as the control variable and to the position of the fuel mass flow control element as the control variable.

10. Power plant according to one of claims 1 to 8, comprising: a fuel mass flow control element (13) for controlling the fuel mass flow to the atmospheric combustion chamber (1 1); Means for determining the exhaust gas temperature at the downstream end of the primary flow path of the heat transfer device; a temperature controller; characterized in that the temperature controller is connected to the exhaust gas temperature as a control variable and with the position of the fuel mass flow control element as a control variable.

11. Power plant according to one of claims 1 to 8, comprising: a fuel mass flow control element (13) for controlling the fuel mass flow to the atmospheric combustion chamber (11); Means (15) for determining the flue gas temperature at the catalyst inlet and / or the catalyst temperature; a temperature controller; characterized in that the temperature controller is connected to the flue gas temperature and / or the catalyst temperature as a control variable and with the position of the fuel mass flow control element as a control variable.

12. Power plant according to one of claims 1 to 3 or 6 to 1 1, characterized in that a high-pressure combustion chamber (161) is arranged downstream of the secondary-side flow path of the heat transfer apparatus (9) and upstream of the high-pressure side of the engine (162).

13. Power plant according to claim 12, characterized in that a flue gas cleaning catalyst (10) at the upstream end of the primary-side flow path of the heat transfer apparatus (9) is arranged.

14. Power plant according to one of claims 12 or 13, further comprising: means for determining the temperature at the engine inlet on the high pressure side of the expansion turbine; a fuel mass flow actuator (17) for controlling the fuel mass flow to the high pressure combustion chamber (161); a temperature controller; characterized in that the temperature controller is connected to the temperature at the turbine inlet as the control variable and to the position of the fuel mass flow control element as the control variable.

15. A method for operating a power plant, comprising the steps of: removing a storage fluid mass flow, in particular an air mass flow, from a storage volume (1); direct the storage fluid mass flow through the secondary-side flow path of a heat transfer apparatus (9) and thereby heat the storage fluid mass flow by indirect heat transfer; to relax the heated storage fluid mass flow in an expansion engine (2, 162); to conduct the relaxed storage fluid mass flow into an atmospheric combustion chamber (1 1); supplying and burning a fuel mass flow to the relaxed storage fluid mass flow in the atmospheric combustion chamber, thereby generating a flue gas; to lead the flue gas through a primary flow path of the heat transfer device (9) and to cool it in the heat exchange with the storage fluid flowing through the secondary flow path of the heat transfer device.

16. The method according to claim 15, comprising the further step of regulating the temperature of the storage fluid at the entry into the expansion engine or limiting it to a maximum value.

17. The method according to any one of claims 15 or 16, comprising the further step of regulating or limiting the temperature of the flue gas at the outlet from the primary-side flow path of the heat transfer apparatus to a minimum value.

18. The method according to any one of claims 15 to 17, comprising the further step of regulating the temperature of the flue gas when entering a catalytic converter or the temperature of the catalytic converter or limiting it above a minimum value and below a maximum value.

19. The method according to any one of claims 16 to 18, comprising the further step of using the fuel mass flow to the atmospheric combustion chamber as a manipulated variable for the control loop.

20. The method according to any one of claims 15 to 19, comprising the further steps: to determine the useful power of the expansion engine, and to regulate the useful power with the air mass flow as a manipulated variable.