JP4004499B2 - Overspeed avoidance device for regenerative gas turbine - Google Patents

Description

  The present invention recovers the rotational speed to the rated speed and releases the thermal energy accumulated in the regenerator when an overspeed in which the turbine rotational speed increases due to a sudden decrease or interruption of the load occurs. The present invention relates to an overspeed avoidance device.

  For example, in a marine gas turbine, when an overspeed occurs due to a sudden decrease or interruption of the load, it is preferable to completely shut off the fuel supply and stop the operation because it hinders the operation of the vessel. Therefore, the speed increase is controlled by reducing the fuel supply amount as much as possible to the limit value just before the blowout (misfire) occurs in the combustor, and the overspeed is designed to quickly recover to the rated speed. An avoidance device is provided. As such an overspeed avoidance device, one shown in FIG. 16 is known (see Patent Document 1). In this case, when an overspeed is generated due to a sudden decrease in load, the occurrence of the overspeed is detected by the speed detector 50 to open the inlet guide vane 51 to increase the resistance of the compressor 52 and to discharge the compressor 52. The control valve 55 provided on the pipeline 54 connecting the discharge portion of the turbine 53 to the engine is opened, and the compressed air is discharged from the control valve 55, whereby the turbine speed is reduced to the rated speed. It tries to avoid overspeed without stopping.

JP-A-8-165934

  In the function generator 56 for controlling the valve opening degree of the control valve 55, a schedule indicating the relationship between the rotational speed of the overspeed region and the valve opening degree of the control valve 55 is set in advance. The control valve 55 controls the valve opening based on a control signal output from the function generator 56 and corresponding to the detected rotational speed of the speed detector 50. Therefore, when this overspeed avoidance device is applied to a simple cycle gas turbine as shown in FIG. 16 without a regenerator, an effect of avoiding overspeed can be expected.

  However, when the overspeed avoidance device is used in a regenerative gas turbine equipped with a regenerator that recovers thermal energy of exhaust gas, even if it can avoid a large overspeed that occurs immediately after a sudden decrease in load, Thereafter, the rotational speed cannot be maintained in a steady state in response to the action of the rotational speed increasing again as the heat energy accumulated in the regenerator is recovered.

  That is, since the regenerator generally has a large heat capacity, a large amount of heat energy is accumulated during load operation, and when the load is suddenly reduced, the large amount of heat energy is recovered to increase the rotational speed. Works. Therefore, in the regenerative gas turbine, even if the fuel supply amount is blown down to the limit when the load is suddenly reduced, a large overspeed may occur depending on the amount of heat energy accumulated in the regenerator. In addition, the heat energy stored in the regenerator requires a longer time to discharge as the heat capacity of the regenerator increases. Therefore, when the overspeed avoidance device is used for a regenerative gas turbine, the overspeed due to a sudden decrease in load is temporarily avoided by reducing the fuel supply amount and releasing the compressed air by opening the control valve 55, and then rotating. In order to maintain the number in a steady state, it is necessary to perform a control operation in which the control valve 55 in FIG. 16 is kept open to release the heat energy accumulated in the regenerator.

  However, the function generator 56 of the overspeed avoidance device outputs a valve opening degree control signal in which the relationship between the rotational speed of the overspeed area and the valve opening degree of the control valve 55 is uniquely set in advance. The valve opening control signal is set to correspond to a simple cycle gas turbine that does not have a regenerator, and therefore does not consider the state of heat energy recovered from the regenerator. In other words, the valve opening control signal operates to close the control valve 55 as the rotational speed returns to the rated value by avoiding an overspeed condition by opening the control valve 55, and enters the regenerator from the compressor 52. As a result of the increase in the amount of high-pressure air, a large amount of heat energy of the regenerator is recovered and enters the turbine 53, so that the turbine rotational speed is increased again. As described above, once the overspeed is avoided, the heat energy recovered by the regenerator cannot be quickly released, so that the rotation speed cannot be maintained at the rated value. This situation will be described in detail with reference to FIG.

  17 (a) to 17 (f) show simulations of the states of the respective parts when a sudden decrease in load occurs when the overspeed avoidance device is used in a regenerative two-shaft gas turbine. In the figure, when the load suddenly decreases at time t, the valve opening of the fuel control valve 57 (FIG. 16) is reduced to reduce the fuel supply amount to the blow-off limit (FIG. 17 (b)), and the control valve 55 is turned on. It opens and discharges compressed air (FIG. 17C). As a result, the rotational speed of the gas generator turbine that drives the compressor 52 is greatly reduced (FIG. 17 (e)) and the exhaust gas temperature is also lowered (FIG. 17 (f)), but the rotational speed of the power turbine that drives the load is reduced. Since the value higher than the target value Rr within the variation allowable range Ra shown in FIG. 17D is maintained for a relatively long time, the overspeed state continues for a long time.

  This is because the opening of the control valve 50 shown in FIG. 17 (c) decreases as the load rotational speed decreases toward the target value Rr, so that the heat energy recovered from the regenerator increases, This is because the rotational speed rises again and changes in the direction in which the control valve 55 is opened, and keeps opening until the large amount of heat energy accumulated in the regenerator is reduced to a predetermined value.

  In addition, when overspeed is avoided by extracting compressed air as in the overspeed avoidance device, a control valve 55 having a relatively large capacity is required to flow a large volume of gas. The operation speed of the continuous control valve 55 whose degree is continuously controlled generally decreases as the capacity increases. Therefore, in a large gas turbine with a large operating flow rate, when the load suddenly decreases or instantaneous interruption occurs, it is difficult to avoid overspeed effectively because the continuous control valve with low responsiveness cannot keep up with the operation. .

  The present invention has been made in view of the above-described conventional problems. After avoiding an overspeed immediately after a sudden decrease in load, while maintaining the rotational speed at the rated value or maintaining the temperature of the exhaust gas within the limit range. An object of the present invention is to provide an overspeed avoidance device for a regenerative gas turbine that can effectively release the thermal energy accumulated in the regenerator and quickly avoid the overspeed.

  In order to achieve the above object, an overspeed avoidance device for a regenerative gas turbine according to the present invention includes a compressor that generates high-pressure air, a combustor that supplies and burns fuel to the high-pressure air, and the combustor A turbine that is driven by a combustion gas from the turbine and drives a load; a regenerator that heats the high-pressure air by exhaust gas discharged from the turbine; and a part of a working fluid comprising the high-pressure air, combustion gas, or exhaust gas And a valve control means for adjusting the opening of the discharge valve by feedback control based on the rotational speed of the turbine, the temperature of exhaust gas from the turbine, or both the rotational speed and exhaust gas temperature. I have.

  According to this configuration, when the load suddenly decreases, the rotation speed increases, and the increase in the rotation speed opens the air discharge valve to release a part of the working fluid to the outside of the gas turbine. An attempt to increase the rotational speed with the decrease is suppressed. Immediately after the sudden decrease in the load, a large amount of heat energy accumulated in the regenerator during the load operation is recovered and put into the turbine to increase the rotational speed and the exhaust gas temperature. In effect, the valve control means feedback-controls the opening degree of the discharge valve based on the rotational speed to be increased, the exhaust gas temperature, or both. As a result, the air discharge valve is controlled to an opening degree that always maintains the rotational speed or the exhaust gas temperature at, for example, a target value, and this opening degree control is continued until the thermal energy accumulated in the regenerator has been released. The

  Therefore, unlike the conventional device, which does not control the opening of the control valve based on a preset schedule by uniquely associating the rotation speed of the overspeed region with the opening of the control valve, this overspeed In the avoidance device, the opening degree of the discharge valve is always appropriately controlled according to the state of the thermal energy accumulated in the regenerator, so after avoiding overspeed due to a sudden decrease in load, the rotation speed is set to the rated value. Therefore, the heat energy stored in the regenerator can be released while maintaining the exhaust gas temperature within the limit range, and the overspeed can be effectively and quickly avoided. The opening degree corresponds to the amount of working fluid released by the air discharge valve.

  In the case where the valve control means performs feedback control based on the exhaust gas temperature, it is preferable that the target exhaust gas temperature is gradually decreased after the start of control during feedback control. According to this configuration, if the target exhaust gas temperature remains at a constant value after recovering from the overspeed state immediately after the sudden decrease in load and the rotational speed returns to the rated value, the opening degree of the discharge valve is Since the temperature is fed back so as to reach the target exhaust gas temperature, the discharge valve continues to open despite the decrease in the thermal energy accumulated in the regenerator. By lowering, the opening degree of the discharge valve can be gradually reduced toward the fully closed state.

  In the present invention, the valve control means may select the lower one of the two feedback control signals based on the rotational speed of the turbine and the exhaust gas temperature and output the selected one as a signal for adjusting the discharge valve. preferable. According to this configuration, by using the two feedback control signals based on the rotational speed and the exhaust gas temperature in combination to control the opening degree of the discharge valve, by selecting the lower one of the two control signals The opening degree of the air discharge valve can be controlled more appropriately for the following reason.

  That is, with only the feedback control system based on the rotational speed, for example, high-pressure air from a compressor that is a working fluid may be released excessively, and the combustion temperature and the exhaust gas temperature may be excessively increased. In the feedback control system based only on this, when the heat energy accumulated in the regenerator decreases and the exhaust gas temperature falls below the target exhaust gas temperature, the vent valve is further opened so that the exhaust gas temperature becomes the target value. Special control means for gradually decreasing the exhaust gas temperature value is required. On the other hand, if the lower one of the two control signals is selected, when the vent valve is opened too much by feedback control based on the rotational speed, the control is switched to feedback control based on the exhaust gas temperature, and the exhaust gas temperature is switched. Is a complicated control means that gradually lowers the target exhaust gas temperature value by switching to the feedback control based on the rotation speed when the thermal energy accumulated in the regenerator is reduced. The air release valve can be gradually closed without using.

Delete. The effect of the fuel control means was put at the end of [0026].

  Moreover, it is preferable that the air discharge valve has a configuration in which an opening / closing valve in which the opening degree changes in two stages of full opening and full closing and an adjustment valve in which the opening degree can change continuously. According to this configuration, when the load is an electric device for power generation or the like, there is a possibility that the load may be instantaneously interrupted, so that the enormous energy used for the operation of the generator is instantaneously generated. In this case, the on-off valve, which has a high operating speed, is fully opened immediately when the load is interrupted. It is possible to reliably suppress the occurrence of a large overspeed accompanying the interruption. Once the overspeed is avoided, the heat energy accumulated in the regenerator can be gradually released at an appropriate speed by continuously controlling the regulating valve instead of the on-off valve.

  The air discharge valve may be provided in a flow path of high-pressure air between the compressor and the regenerator or between the regenerator and the combustor. According to this configuration, by opening the discharge valve and releasing a part of the high-pressure air supplied from the compressor to the regenerator or a part of the high-pressure air supplied from the regenerator to the combustor, The turbine output is reduced, and overspeed can be avoided.

  Moreover, you may provide the said ventilating valve in the flow path of the waste gas between the exit of the said turbine, and a regenerator. According to this configuration, by releasing a part of the exhaust gas supplied from the turbine to the regenerator out of the system, it is possible to reduce the thermal energy due to the exhaust gas recovered by the regenerator. Thereby, the output of a turbine falls and an overspeed can be avoided.

  According to the overspeed avoidance device for a regenerative gas turbine of the present invention, after avoiding an overspeed immediately after a sudden decrease in load, the opening degree of the discharge valve for releasing a part of the working fluid to the outside of the system is set. By performing feedback control based on at least one of the rotational speed and exhaust gas temperature, the thermal energy accumulated in the regenerator is gradually released while maintaining the rotational speed at the rated value or keeping the exhaust gas temperature within the limit range. Thus, it is possible to avoid overspeed effectively and quickly.

  FIG. 1 is a system diagram showing a regenerative two-shaft free gas turbine to which an overspeed avoidance device according to a first embodiment of the present invention is applied. The gas turbine supplies high-pressure air A1 generated by compressing air by the compressor 1 to the combustor 3 via the regenerator 2, and the combustor 3 supplies fuel to the high-pressure air A2 supplied from the regenerator 2. Are mixed and burned, and the gas generator turbine 4 and the power turbine 7 are operated by the energy of the high-temperature and high-pressure combustion gas G generated by the combustion. The gas generator turbine 4 drives the compressor 1 via the gas generator shaft 8 that is the first shaft, and the power turbine 7 for taking out the output receives the load L1 via the power turbine shaft 9 that is the second shaft. To drive. The load L1 here is a mechanical device such as a marine propeller or an electrical device such as a generator. The exhaust gas E discharged from the power turbine 7 is supplied to the regenerator 2, and the regenerator 2 recovers the heat energy of the exhaust gas E by exchanging heat between the exhaust gas E and the high-pressure air A 1 from the compressor 1. The high-pressure air A1 is heated to generate high-temperature high-pressure air A2, which is supplied to the turbines 4 and 7.

  The power turbine shaft 9 is provided with a rotation sensor 10 that detects the rotational speed of the power turbine 7. The fuel controller 11 as fuel control means sets the rotational speed of the power turbine 7 to a predetermined value by performing feed hack control on the opening degree of the fuel control valve 12 based on the rotational speed of the power turbine 7 detected by the rotation sensor 10. The fuel supply amount is variably adjusted so that In addition, an air discharge valve 13 for discharging a part of the high-pressure air A1 to the outside of the gas turbine system is connected to the flow path of the high-pressure air A1 between the compressor 1 and the regenerator 2. The air discharge valve 13 has an opening that can be continuously changed.

  The valve controller 14, which is a valve control means for adjusting the opening degree of the discharge valve 13, includes a memory 17 in which a rotation speed target value set in advance near a rated rotation speed of the power turbine 7 is stored, and the rotation A subtractor 18 for calculating a difference value between the numerical target value and the rotational speed of the power turbine 7 detected by the rotation sensor 10, a controller 19 for calculating a control signal based on the deviation calculated by the subtractor 18, and An inverter 20 that inverts the sign of the control signal output from the controller 19 and outputs a feedback control signal FS 1, and an open / close like a switch interposed in a connection line between the inverter 20 and the discharge valve 13. Means 21, and opening / closing control means 22 for controlling opening / closing of the opening / closing means 21 based on the rotation speed detection value from the rotation sensor 10 and the opening degree detection value of the ventilating valve 13 are provided. The valve controller 14 adjusts the opening degree of the air discharge valve 13 by feedback control based on the rotational speed of the power turbine 7.

  Next, the operation for avoiding the overspeed in the overspeed avoidance device of the embodiment will be described with reference to the simulation results of FIG. When the load L1 shown in FIG. 1 suddenly decreases at time t1 as shown in FIG. 2A, the fuel controller 11 in FIG. 1 indicates that the load L1 is suddenly reduced due to an increase in the rotation speed detection value from the rotation sensor 10. It discriminate | determines and performs control which throttles the fuel control valve 12 shown in FIG.2 (b) to the opening degree corresponding to the fuel supply amount of a blow-off limit. As a result, the rotational speed of the gas generator turbine 4 in FIG. 2 (e) is greatly reduced, and the rotational speed of the power turbine 7 shown in FIG. 2 (d) is prevented from suddenly increasing as the load L1 decreases rapidly. Thus, an overspeed state immediately after the sudden decrease in the load L1 is quickly avoided. Here, the ventilating valve 13 whose opening degree can be continuously changed has a relatively poor responsiveness, and thus may not function to immediately suppress the occurrence of overspeed. 11 is capable of controlling the fuel supply amount to be blown down to the limit when the load suddenly decreases, so that the overspeed associated with the sudden decrease in load can be quickly suppressed immediately after this occurs. Can do.

  After the overspeed state is once avoided in this way, a large amount of heat energy accumulated in the regenerator 2 starts to be recovered during the operation of the load L1, and acts to increase the rotational speed of the power turbine 7. Thus, even if the fuel supply amount is reduced to the blow-off limit as described above, the rotational speed of the power turbine 7 does not return to the rotational speed target value Rr shown in FIG. Therefore, in the valve controller 14 of FIG. 1, the opening / closing control means 22 detects the overspeed state based on the rotation speed detection value of the rotation sensor 10 and closes the opening / closing means 21 to set the feedback control to be possible. . In this state, the controller 19 calculates a control signal based on the deviation from the subtracter 18, and a negative signal as a result of the calculation is converted into a positive signal by the inverter 20 to obtain a feedback control signal FS1. It is done. With this feedback control signal FS1, after opening the air discharge valve 13 at time t2 in FIG. 2C, the opening degree of the air discharge valve 13 is feedback controlled based on the rotational speed of the power turbine 7. The feedback control signal FS1 is positive in the direction in which the opening degree of the discharge valve 13 is increased.

  When the discharge valve 13 is opened, a part of the high-pressure air A1 that is a working fluid that passes through the gas turbine is released to the outside through the discharge valve 13, and the flow rate of the high-pressure air A1 that passes through the regenerator 2 decreases. . In this way, by opening the vent valve 13 and releasing a part of the high-pressure air A1 supplied from the compressor 1 to the regenerator 2 to the outside, the output of the power turbine 7 is reduced to avoid overspeed. be able to.

  In the conventional apparatus of FIG. 16, the control valve 55 provided in the discharge part of the compressor 52 is controlled to a valve opening uniquely set with respect to the rotational speed in the overspeed region, and this is applied to the regenerative gas turbine. In this case, it was not possible to set the opening according to the state of thermal energy of the regenerator. On the other hand, in the overspeed avoidance device, the opening degree of the ventilating valve 13 can be set according to the state of thermal energy recovered from the regenerator. While the heat energy accumulated in the regenerator 2 remains, if the air discharge valve 13 is operated in the direction of closing, the rotational speed of the power turbine 7 tends to increase due to the heat energy recovered from the regenerator 2. The valve controller 14 performs control so that the air discharge valve 13 is held open.

  After that, when the heat energy accumulated in the regenerator 2 is gradually released and the energy to rotate the power turbine 7 decreases, the rotational speed of the power turbine 7 reaches the rotational speed target value Rr at time t3. At this time, the valve controller 14 feedback-controls the discharge valve 13 in the closing direction as shown in FIG. 2C by the feedback control signal FS1, so that the rotational speed of the power turbine 7 is The rotation speed target value Rr is maintained. As a result, the power turbine 7 is reliably held within the variation allowable range Ra shown in FIG. 2D even in a situation where a relatively large overspeed is likely to occur due to a sudden decrease in the load L1.

  The valve controller 14 controls the air release valve 13 to be gradually closed as the heat energy accumulated in the regenerator 2 is gradually released. As a result, while the rotational speed of the power turbine 7 is maintained at the rotational speed target value Rr, the air discharge valve 13 is finally controlled to be fully closed. The opening / closing control means 22 turns off the opening / closing means 21 when it detects the fully closed state of the discharge valve 13 and returns to the normal operating state.

  By the way, when the load L <b> 1 is input before the discharge valve 13 is fully closed, the opening / closing control means 22 determines the rotational speed of the power turbine 7 based on the rotational speed detection value of the rotational sensor 10. By detecting a sudden drop and turning off the opening / closing means 21, the discharge valve 13 is immediately controlled to be fully closed, so that it can be immediately returned to the normal operating state. As a result, it is possible to prevent the rotational speed of the per turbine 7 from greatly decreasing due to the air release valve 13 being held open with the load L1 being applied.

  In the overspeed avoidance device, a fuel feedback control system in which the fuel controller 11 adjusts the fuel control valve 12 based on the rotational speed of the power turbine 7, and an opening degree of the air discharge valve 13 based on the rotational speed. The two feedback control systems both control the rotational speed of the power turbine 7, but these two feedback control systems interfere with each other's control operations. Accordingly, the control operation does not become unstable. That is, since the fuel controller 11 is generally adjusted so as to increase the sensitivity of the control operation, the fuel controller 11 can quickly follow the fluctuation of the load L1. On the other hand, the air discharge valve 13 that opens and closes the flow path of the working fluid whose flow rate is larger than that of the fuel is large as described above, and the operation speed is relatively slow. In order to cope with the response of the wind valve 13, the sensitivity of the control operation cannot be made very high. Therefore, the opening degree control of the air discharge valve 13 must be less sensitive to the control operation than the fuel flow rate control, and as a result, both control operations can be easily adjusted so as not to cause interference.

  The regenerative two-shaft free gas turbine to which the overspeed avoidance device of the first embodiment is applied is a gas turbine in which a relatively large overspeed is likely to occur when the load L1 is suddenly reduced. That is, in a single-shaft gas turbine, the compressor, the turbine, and the load are coupled on the same axis as the output shaft, and the compressor has a certain resistance against increasing the rotational speed of the turbine when the load suddenly decreases. And acts in a direction to prevent overspeed. On the other hand, in the two-shaft free turbine, the compressor 1 is not coupled to the power turbine shaft 9 that drives the load L1, so that when the load L1 suddenly decreases, some mechanical loss such as frictional resistance is caused. Except for the fact that there is no resistance element, an overspeed is likely to occur. When this is a regenerative type, the thermal energy recovered from the regenerator 2 is also added, so that the regenerative two-shaft free turbine is likely to generate a relatively large overspeed when the load L1 is suddenly reduced. On the other hand, the overspeed avoidance device can reliably avoid the occurrence of such a large overspeed as described above, and is applied to any type of regenerative gas turbine other than the two-shaft free turbine. In some cases, overspeed can be reliably avoided, and this is the same in any of the following embodiments.

  FIG. 3 is a system diagram showing a regenerative two-shaft free gas turbine to which the overspeed avoidance device according to the second embodiment of the present invention is applied. This overspeed avoidance device differs from that of the first embodiment in that, in the first embodiment, the opening degree of the discharge valve 13 is adjusted by feed hack control based on the rotational speed of the power turbine 7, whereas In the overspeed avoidance device, only the opening degree of the discharge valve 13 is adjusted by feedback control based on the temperature of the exhaust gas E discharged from the power turbine 7, and therefore a valve controller for feedback control of the discharge valve 13 is provided. The configuration of 14A is different from that of the first embodiment.

  That is, the valve controller 14A has a temperature table 24 and a subtracter 28. In the temperature table 24, a target exhaust gas temperature value of the exhaust gas E that decreases with time from the initial value is set in advance. The subtractor 28 calculates a difference value between the target exhaust gas temperature value from the temperature table 24 and the temperature of the exhaust gas E detected by the temperature sensor 27. This exhaust gas temperature is the temperature of the exhaust gas E between the power turbine 7 and the regenerator 2. The valve controller 14A further includes a controller 29 that calculates a feedback control signal FS2 based on the deviation calculated by the subtractor 28, and an opening / closing means 21 interposed in a connection line between the controller 29 and the air discharge valve 13. The opening / closing control means 22 for controlling opening / closing of the opening / closing means 21 based on the rotation speed detection value from the rotation sensor 10 and the opening detection value of the air discharge valve 13, and the rotation speed detection value from the rotation sensor 10 and the air discharge valve 13. Table control means 30 is provided for issuing a change command and a reset command for the target exhaust gas temperature of the temperature table 24 based on the detected opening value.

  Next, the operation of avoiding overspeed in the overspeed avoidance device of the second embodiment will be described with reference to the simulation results of FIG. When the load L1 shown in FIG. 3 suddenly decreases at time t11 as shown in FIG. 4 (a), the fuel controller 11 opens the fuel control valve 12 corresponding to the fuel supply amount at the blow-off limit, as in the first embodiment. Therefore, the overspeed state immediately after the sudden decrease in the load L1 is quickly avoided. After that, the heat energy accumulated in the regenerator 2 is recovered and acts in the direction of increasing the rotational speed of the power turbine 7, so that the rotational speed of the power turbine 7 does not immediately return to the rotational speed target value Rr. Further, when the load L1 is suddenly decreased, the opening / closing control means 22 detects an overspeed state based on the rotation speed detection value and closes the opening / closing means 21, whereby the valve controller 14A enters the feedback control state.

  In the temperature table 24 of the valve controller 14A, a value slightly lower than the limit temperature allowed during load operation is set as the target exhaust gas temperature value Tr shown in FIG. This is to give a certain margin to the temperature limit. That is, when the discharge valve 13 of FIG. 3 is opened, the flow rate of the high-pressure air A2 entering the combustor 3 from the regenerator 2 decreases and the temperature of the exhaust gas E rises, so that the exhaust gas temperature limit value Tr is reached. This is to give a margin that allows the air release valve 13 to be closed.

  Then, at the time t11 when the sudden change of the load L1 occurs, the temperature of the exhaust gas E is greatly reduced from the target exhaust gas temperature Tr as the fuel is blown off to the limit as described above. A large difference value is output, and the controller 29 adjusts the ventilating valve 13 so that it opens to a large opening. As a result, a relatively large amount of high-pressure air A1 is discharged to the outside through the air discharge valve 13, so that the combustion temperature rises as the flow rate of the high-pressure air A1 passing through the regenerator 2 decreases, and FIG. As shown in f), the temperature of the exhaust gas E similarly rises. At this time, the valve controller 14A performs feedback control based on the temperature of the raised exhaust gas E to adjust the discharge valve 13 to an appropriate opening degree, and releases the exhaust gas E in a direction to reach the target exhaust gas temperature value Tr. Control of the opening degree of the wind valve 13 is continued.

  Therefore, in this overspeed avoidance device, while releasing a large amount of thermal energy accumulated in the regenerator 2, the opening degree of the discharge valve 13 is set within a range where the temperature of the exhaust gas E does not exceed the target exhaust gas temperature value Tr. Since the feedback control can be performed by restricting to the inside, the combustion temperature and the temperature of the exhaust gas E rise excessively until the temperature of the exhaust gas E exceeds the limit temperature that can be withstood by the high temperature member of the gas turbine. There is an advantage that can be surely prevented.

  Then, at time t12 in FIG. 4D, the power turbine 7 is restored from the overspeed state immediately after the sudden decrease in the load L1 and is in a settling state in which the rotational speed of the power turbine 7 returns to the target rotational speed Rr. After that, if the feedback control for setting the opening degree of the discharge valve 13 so that the temperature of the exhaust gas E becomes the target exhaust gas temperature value Tr is continued as it is, the heat energy accumulated in the regenerator 2 decreases. The temperature of the exhaust gas E does not reach the target exhaust gas temperature value Tr. In this case, since the discharge valve 13 is controlled so as to have the target exhaust gas temperature value Tr, the air discharge valve 13 operates further in the opening direction even though the heat energy of the regenerator 2 is reduced.

  Therefore, in the overspeed avoidance device, when the table control means 30 in FIG. 3 detects that the rotational speed of the power turbine 7 has been set to the rated state based on the rotational speed detection value of the rotational sensor 10, the temperature table 24 is used. A change command for the target exhaust gas temperature value Tr is given to the engine. Accordingly, the temperature table 24 is changed by means of a ramp function or the like so as to gradually decrease the target exhaust gas temperature value Tr as indicated by a two-dot chain line in FIG. Since the valve controller 14A performs feedback control for setting the opening degree of the air discharge valve 13 so that the temperature of the exhaust gas E becomes the target exhaust gas temperature value Tr, the air discharge valve 13 is gradually decreased toward the fully closed state. As the opening degree is reduced and the discharge valve 13 is held at a small opening degree, an increase in the rotational speed of the power turbine 7 is suppressed, and the thermal energy accumulated in the regenerator is gradually released.

  The table control means 30 gives a reset command to the temperature table 24 when detecting any one of overspeed, full closing of the air discharge valve 13 or turning on of the load L1, and the initial target exhaust gas (at time t11). The temperature Tr is reset. Also in the overspeed avoidance device, as in the first embodiment, when the load L1 is applied until the discharge valve 13 is fully closed, the opening / closing control means 22 causes the opening / closing means 21 to By turning it off, the discharge valve 13 is immediately fully closed and returned to the normal operation state.

  In the overspeed avoidance device, even if feedback control based on the temperature of the combustion gas G is performed instead of the temperature of the exhaust gas E, the same operation and effect as described above can be obtained. In that case, since the combustion temperature of the gas turbine is usually a high temperature of around 1200 ° C., it is necessary to use an expensive temperature sensor with excellent durability, so that the exhaust gas is relatively low as in the second embodiment. It is preferable to use the temperature of E.

FIG. 5 is a system diagram showing a regenerative two-shaft free gas turbine to which the overspeed avoidance device according to the third embodiment of the present invention is applied. In this overspeed avoidance device, the valve controller 14B includes a first feedback control system 34 having the same memory 17, subtractor 18, controller 19 and inverter 20 as provided in the first embodiment, and a preset value. the target exhaust gas temperature Tr ₀ memory 32 is stored, the subtractor 28 and the second feedback control system 37 includes a controller 29 becomes substantially the same structure as the second embodiment is a constant value, these first A signal for adjusting the opening degree of the discharge valve 13 by selecting the lower one of the two first and second feedback control signals FS1 and FS2 based on the first and second feedback control systems 34 and 37. And the same opening / closing means 21 and opening / closing control means 22 as those provided in the first and second embodiments. That is, the valve controller 14B selectively performs control of the rotational speed of the power turbine 7 by the first feedback control system and control of the temperature of the exhaust gas E by the second feed hack control system, thereby The control operation is performed so as to avoid it.

  Next, the operation for avoiding the overspeed in the overspeed avoidance device of this embodiment will be described with reference to the simulation results of FIG. In addition, about the same operation | movement as demonstrated in 1st and 2nd embodiment, the overlapping description is abbreviate | omitted. When the load L1 shown in FIG. 5 suddenly decreases at time t21 as shown in FIG. 6 (a), the supply amount of fuel is reduced to suppress the rapid rise of the power turbine 7, and immediately thereafter, the first feedback control system Although the feedback control of the rotational speed of the power turbine 7 by 34 and the feedback control of the exhaust gas temperature by the second feed hack control system 37 are started simultaneously, the low-level selector 33 outputs from both feedback control systems 34 and 37. The lower one of the two feedback control signals FS1 and FS2, that is, the smaller one of the opening command is selected to adjust the opening of the discharge valve 13.

  Immediately after the sudden decrease of the load L1, the temperature of the exhaust gas E is relatively greatly reduced by reducing the amount of fuel supplied, and the second feedback control signal FS2 based on the exhaust gas temperature detected by the temperature sensor 27 is used. Since the opening degree command is also increased, the low order selector 33 selects the first feedback control signal FS1 having a low signal level and outputs it as a signal for adjusting the opening degree of the discharge valve 13. Thus, feedback control is performed so that the rotational speed of the power turbine 7 becomes the rotational speed target value Rr stored in the memory 17.

When the heat energy accumulated in the regenerator 2 is gradually released and the energy to rotate the power turbine 7 decreases, the rotational speed of the power turbine 7 rotates at time t22 in FIG. 6 (d). It decreases in a direction below the target value Rr. At this time, the temperature of the exhaust gas E rises as a part of the high-pressure air A1 is discharged out of the system through the air discharge valve 13 and the flow rate of the working fluid passing through the gas turbine decreases. The opening degree command by the control signal FS2 is smaller than the opening degree command of the first feedback control signal FS1. Therefore, the valve controller 14B switches the first feedback control signal FS1 from the first feedback control signal FS1 to the second feedback control signal FS2 by the low-order selector 33, thereby setting the opening degree of the discharge valve 13 and the temperature of the exhaust gas E in the memory 32. Feedback control is performed so as to match the stored target exhaust gas temperature value Tr ₀ (FIG. 6F).

The target exhaust gas temperature Tr ₀ is not a value that gradually decreases as in the second embodiment, but is a constant value stored and set in the memory 32. However, as the heat energy accumulated in the regenerator 2 is released, the temperature of the exhaust gas E decreases without reaching the target exhaust gas temperature Tr ₀ . Therefore, at the time t23, the opening degree command based on the second feedback control signal FS2 becomes larger than the opening degree command based on the first feedback control signal FS1, and the first feedback control signal FS1 is selected again by the low-order selector 33. Thus, the opening degree of the air discharge valve 13 is feedback-controlled based on the rotational speed of the power turbine 7.

  As described above, the first and second feedback control systems 34 and 37 are used together, and the lower one of the feedback control signals FS1 and FS2 is selected to open the air discharge valve 13. By feedback control of the degree, it is possible to eliminate both a problem that may occur in the first embodiment and a slight complication of the configuration of the second embodiment. This point will be described below.

  In the first embodiment shown in FIGS. 1 and 2, the opening degree of the discharge valve 13 is controlled based only on the rotational speed of the power turbine 7 without monitoring the temperature of the exhaust gas E. The amount of discharge of the high-pressure air A1 becomes too large, and the combustion temperature and the temperature of the exhaust gas E may be excessively increased. The case where such a problem occurs is illustrated in FIG. That is, at time t3 in FIG. 2B, the set opening of the discharge valve 13 is too large, and as shown in FIGS. When the rotational speed of the turbine 7 is about to fall below the rotational speed target value Rr, the amount of fuel supplied temporarily increases and the amount of high-pressure air A1 released is large, as shown in FIG. The temperature of the exhaust gas E temporarily rises excessively. On the other hand, in the third embodiment, the rotational speed of the power turbine 7 shown in FIG. 6 (d) approaches the target rotational speed Rr due to the opening degree of the vent valve 13 becoming too large. At that time, the control is switched to the control based on the second feedback control signal FS2, and the control is performed so that the temperature of the exhaust gas E does not exceed the limit value.

Further, in the second embodiment shown in FIGS. 3 and 4, when the thermal energy accumulated in the regenerator 2 is released to some extent, the rotational speed of the power turbine 7 is in a settling state that is almost settled to the rated value. In addition, the temperature table 24 and the table control means 30 need to detect the settling state and perform special control for gradually decreasing the target exhaust gas temperature value Tr. On the other hand, in the third embodiment, the temperature of the exhaust gas E is increased with the release of the energy accumulated in the regenerator 2 while the target exhaust gas temperature value Tr ₀ is simply set in the memory 32 of FIG. At time T23 in FIG. 6 (f), the control is switched again to the control based on the first feedback control signal FS1, and the discharge valve 13 is fully closed as the thermal energy accumulated in the regenerator 2 decreases. It can be controlled to close gradually toward

  FIGS. 7 and 8 are system diagrams showing the main parts of a regenerative two-shaft free gas turbine to which the overspeed avoidance devices according to the fourth and fifth embodiments of the present invention are applied, respectively. In the first to third embodiments, the vent valve 13 is provided in the air flow path between the outlet of the compressor 1 and the inlet of the regenerator 2, whereas in the fourth embodiment of FIG. The valve 13 is provided in the air flow path between the outlet of the regenerator 2 and the inlet of the combustor 3, and in the fifth embodiment of FIG. 8, the discharge valve 13 is connected to the outlet of the power turbine 7 and the inlet of the regenerator 2. It is provided in the exhaust gas flow path between.

  In the fourth embodiment shown in FIG. 7, unlike the first to third embodiments, the air flow rate passing through the regenerator 2 does not decrease, so the heat energy recovered in the regenerator 2 cannot be reduced. In this regenerator, a part of the high-pressure air A2 heated by heat energy is discharged out of the gas turbine system, so that the heat energy input to the power turbine 7 can be reduced. As a result, it is possible to obtain the same operation and effect as when a part of the high-pressure air A1 supplied to the regenerator 2 in the first to third embodiments is discharged out of the system. In addition, although illustration is abbreviate | omitted in FIG. 7, any feedback control system shown in the 1st thru | or 3rd embodiment is applicable as it is.

  Moreover, in 5th Embodiment of FIG. 8, the flow volume of the waste gas E which passes the regenerator 2 can be reduced, and, thereby, the thermal energy collect | recovered by the regenerator 2 itself can be reduced. As a result, the heat energy of the high-pressure air A2, that is, the heat energy input to the power turbine 7 can be reduced, so that the same operations and effects as those of the first to third embodiments can be obtained. In addition, although illustration is abbreviate | omitted in FIG. 8, the feedback control system based on the rotation speed shown in 1st Embodiment is applicable as it is.

  It is not preferable to apply the feedback control system of the second or third embodiment (control based on exhaust gas temperature or both exhaust gas temperature and rotational speed) to the fifth embodiment for the following reason. In the fifth embodiment of FIG. 8, the temperature characteristics of the exhaust gas E with respect to the opening / closing operation of the discharge valve 13 are different. That is, in the first to fourth embodiments, when the discharge valve 13 is opened, the flow rate of the gas passing through the combustor 3 and the turbines 4 and 7 decreases, so the temperature of the exhaust gas E tends to rise. On the other hand, in the fifth embodiment, when the air discharge valve 13 in FIG. 8 is opened, the flow rate of the exhaust gas E passing through the regenerator 2 decreases, while the flow rate of the gas passing through the combustor 3 and the turbines 4 and 7. Will not decrease. Therefore, the temperature of the exhaust gas E slightly decreases as the amount of heat recovered from the regenerator 2 decreases. As described above, in the fifth embodiment, unlike the first to fourth embodiments, the temperature of the exhaust gas E does not increase. Therefore, the method using the feedback control of the temperature of the exhaust gas E is not appropriate. A method using the rotational speed is appropriate. Note that the temperature of the exhaust gas E does not rise due to the opening of the discharge valve 13 even by feedback control based on this rotational speed. Therefore, unlike the case of releasing the high-pressure air A1, A2, the combustion temperature and There is no risk of excessively increasing the exhaust gas temperature.

  FIG. 9 is a system diagram showing a main part of a regenerative two-shaft free gas turbine to which the overspeed avoidance device according to the sixth embodiment of the present invention is applied. The sixth embodiment is particularly suitable when an electrical device such as a generator for power generation or electric propulsion is used as the load L2. This overspeed avoidance device is different from the first to third embodiments in that the opening angle is the same as that used as the discharge valve 38 in the first to third embodiments. The control valve 39 that can be changed to the above and the on-off valve 40 whose opening degree changes in two stages of fully open and fully closed are shown in the first to third embodiments as a feedback control system. Any of the above can be applied as it is.

  First, the reason why the discharge valve 38 is constituted by the adjustment valve 39 and the opening / closing valve 40 will be described. In the load L1 composed of a mechanical device such as a ship propulsion device, the output decreases with a certain time delay due to the mechanical resistance of the load L1 itself even if it is interrupted instantaneously. For the gas turbine, the output of the load L1 does not instantaneously decrease to zero. On the other hand, in the load L2 composed of an electrical device, the load is turned on or off instantaneously. Further, when an abnormality occurs in the generator or the power system, for example, the control system is opened by opening the circuit breaker. May be instantaneously disconnected from the full load state to the full load cut-off. Further, in the load L2, when the full load is interrupted instantaneously, the enormous energy used for power generation and the like is instantaneously changed to a large acceleration energy. The climbing speed of is extremely large.

  Therefore, in the overspeed avoidance device, by adding the opening / closing valve 40 as the discharge valve 38, the followability to the instantaneous load interruption is ensured and the discharge valve 38 is switched from the opening / closing valve 40 to the regulating valve 39. Thus, appropriate overspeed avoidance control can be performed for the heat energy recovered from the regenerator 2.

  Next, the operation for avoiding the overspeed in the overspeed avoidance device of the sixth embodiment will be described with reference to the simulation results of FIG. FIG. 10 illustrates a case where the opening degree of the discharge valve 38 in FIG. 9 is feedback-controlled by a feedback control system substantially equivalent to the case of using the valve controller 14B in FIG. 5 in the third embodiment. When the load L2 shown in FIG. 9 is interrupted at time t31 shown in FIG. 10 (a), the rotational speed of the power turbine 7 instantaneously increases as shown in FIG. 10 (d). At this time, as shown in FIG. 5C, the on-off valve 40 is fully opened in the discharge valve 38, and the adjustment valve 39 is set to an opening degree by feedback control based on the rotational speed of the power turbine 7. The instantaneous increase in the rotational speed of the power turbine 7 is suppressed by releasing a relatively large amount of working fluid out of the system by fully opening the on-off valve 40.

  At time t32 in FIG. 10 (d) when the rotational speed of the power turbine 7 is reduced to an appropriate value due to the full opening of the on / off valve 40, the on / off valve 40 is controlled to be fully closed, and thereafter, the first to third The opening degree of the regulating valve 39 is continuously controlled by feedback control similar to that described in any of the embodiments, and thereby the heat energy accumulated in the regenerator 2 is released.

  As described above, the overspeed avoidance device can effectively and quickly avoid the overspeed when the load L2 such as an electrical device is instantaneously interrupted, and such an effect can be obtained. As a comparative example for specifically indicating this, the state of each part when the instantaneous interruption of the load L2, which is an electrical device, occurs in the overspeed avoidance devices of the first and second embodiments is shown in FIGS. It is shown. Even in the case of FIG. 11 (first embodiment) and FIG. 12 (second embodiment), the operation speed is relatively slow in the ventilating valve 13 whose opening degree can be continuously changed. Since high-pressure air or exhaust gas E cannot be discharged instantaneously, the rotational speed of the power turbine 7 increases beyond the upper limit of the allowable fluctuation range Ra as shown in FIGS. 11 (d) and 12 (d). Or the exhaust gas temperature rises above the target exhaust gas temperature Tr occurs, and overspeed cannot be effectively avoided.

  Moreover, since the on-off valve 40 used as a part of the air discharge valve 38 of the sixth embodiment has a higher operating speed than the regulating valve 39, the on-off valve 40 alone is used to instantaneously cut off the load L2 like an electrical device. It is conceivable to avoid overspeed at the time. FIG. 13 shows the state of each part of a comparative example in which the adjustment valve 39 is excluded from the vent valve 38 in the sixth embodiment and the overspeed at the time of instantaneous interruption of the load L2 is avoided. It is. In this case, an instantaneous increase in the rotational speed of the power turbine 7 immediately after the load L2 is interrupted can be suppressed by releasing a relatively large amount of working fluid out of the system by fully opening the on-off valve 40.

  However, in the case of a regenerative gas turbine, it takes a relatively long time for the thermal energy accumulated in the regenerator 2 to be released even after avoiding the overspeed state immediately after the load L2 is shut off. If the on / off valve 40 is closed when the overspeed state immediately after the L2 is cut off is avoided, the overspeed state is resumed due to the heat energy recovered from the regenerator 2, so the on / off valve 40 must be opened again. Instead, as shown in FIG. 13 (c), the on-off valve 40 must be controlled so as to be frequently repeated alternately between full open and full close. Therefore, in the regenerative gas turbine, in addition to the on-off valve 40, it is preferable to provide a regulating valve 39 whose opening degree can be continuously changed.

  FIG. 14 and FIG. 15 are system diagrams showing a main part of a regenerative two-shaft free gas turbine to which each overspeed avoidance device according to the seventh and eighth embodiments of the present invention is applied. In the sixth embodiment of FIG. 9, an air discharge valve 38 having a regulating valve 39 and an on-off valve 40 is provided in the air flow path between the outlet of the compressor 1 and the inlet of the regenerator 3. In the seventh embodiment of FIG. 14, the vent valve 38 is provided in the air flow path between the outlet of the regenerator 2 and the inlet of the combustor 3, whereby the high pressure heated by the heat energy in the regenerator. By releasing a part of the air out of the system, the heat energy input to the power turbine 7 can be reduced. In the eighth embodiment of FIG. 15, the discharge valve 38 is provided in the exhaust gas flow path between the outlet of the power turbine 7 and the inlet of the regenerator 2, whereby the flow rate of the exhaust gas E passing through the regenerator 2. Thus, the heat energy recovered by the regenerator 2 itself can be reduced. Therefore, in any case, the same effect as described in the sixth embodiment can be obtained.

  In the seventh embodiment of FIG. 14, any feedback control (control based on the rotational speed or / and the exhaust gas temperature) shown in the first to third embodiments can be applied. In the eighth embodiment of FIG. 15, since the exhaust gas E is released, it is preferable to apply the feedback control (control based on the rotational speed) of the first embodiment as in the case of the fifth embodiment of FIG.

  The air discharge valves 13 and 38 of the present invention operate from the compressor 1 to the regenerator 2 via the regenerator 2, the combustor 3, the gas generator turbine 4 and the power turbine 7, as can be seen from the above embodiments. It can be provided at any location of the fluid flow path (including the compressor 1 and the regenerator 2 at both ends of the flow path).

1 is a system diagram showing a regenerative gas turbine to which an overspeed avoidance device according to a first embodiment of the present invention is applied. (A)-(f) is a simulation figure which shows the state of each part at the time of sudden load reduction generation | occurrence | production in the overspeed avoidance apparatus same as the above. It is a systematic diagram showing the regenerative gas turbine to which the overspeed avoidance device according to the second embodiment of the present invention is applied. (A)-(f) is a simulation figure which shows the state of each part at the time of sudden load reduction generation | occurrence | production in the overspeed avoidance apparatus same as the above. It is a systematic diagram showing the regenerative gas turbine to which the overspeed avoidance device according to the third embodiment of the present invention is applied. (A)-(f) is a simulation figure which shows the state of each part at the time of sudden load reduction generation | occurrence | production in the overspeed avoidance apparatus same as the above. It is a systematic diagram which shows the principal part of the regenerative gas turbine to which the overspeed avoidance device according to the fourth embodiment of the present invention is applied. It is a systematic diagram which shows the principal part of the regenerative gas turbine to which the overspeed avoidance device according to the fifth embodiment of the present invention is applied. It is a systematic diagram which shows the principal part of the regenerative gas turbine to which the overspeed avoidance device according to the sixth embodiment of the present invention is applied. (A)-(f) is a simulation figure which shows the state of each part at the time of sudden load reduction generation | occurrence | production in the overspeed avoidance apparatus same as the above. (A)-(f) is a simulation figure which shows the state of each part at the time of interruption | blocking generation | occurrence | production of the load of the electric apparatus in the overspeed avoidance apparatus which concerns on 1st Embodiment. (A)-(f) is a simulation figure which shows the state of each part at the time of interruption | blocking generation | occurrence | production of the load of the electric apparatus in the overspeed avoidance apparatus which concerns on 2nd Embodiment. (A)-(f) is a simulation figure which shows the state of each part at the time of interruption | blocking generation | occurrence | production of the load of the electric apparatus of the comparative example which comprised only the on-off valve in the overspeed avoidance apparatus which concerns on 6th Embodiment. is there. It is a systematic diagram which shows the principal part of the regenerative gas turbine to which the overspeed avoidance device according to the seventh embodiment of the present invention is applied. It is a systematic diagram which shows the principal part of the regenerative gas turbine to which the overspeed avoidance device according to the eighth embodiment of the present invention is applied. It is a systematic diagram which shows the overspeed avoidance apparatus of the conventional gas turbine. (A)-(f) is a simulation figure which shows the state of each part at the time of the sudden reduction | decrease generation | occurrence | production of load in the case where the overspeed avoidance device same as the above is used for a regenerative type biaxial gas turbine.

Explanation of symbols

1 Compressor 2 Regenerator 3 Combustor 7 Power turbine (turbine)
11 Fuel controller (fuel control means)
13, 38 Ventilation valve 14, 14A, 14B Valve controller (valve control means)
39 Control valve 40 On-off valve L1, L2 Load FS1, FS2 Feedback control signal Tr, Tr ₀ Target exhaust gas temperature

Claims (9)

A compressor that generates high-pressure air;
A combustor for supplying and burning fuel to the high-pressure air;
A turbine that operates with combustion gas from the combustor to drive a load;
A regenerator for heating the high-pressure air with exhaust gas discharged from the turbine;
A vent valve for releasing a part of the working fluid comprising the high-pressure air, combustion gas or exhaust gas to the outside of the system;
An overspeed avoidance device for a regenerative gas turbine, comprising: valve control means for adjusting an opening degree of the discharge valve by feedback control based on a rotational speed of the turbine. A compressor that generates high-pressure air;
A combustor for supplying and burning fuel to the high-pressure air;
A turbine that operates with combustion gas from the combustor to drive a load;
A regenerator for heating the high-pressure air with exhaust gas discharged from the turbine;
A vent valve for releasing a part of the working fluid comprising the high-pressure air, combustion gas or exhaust gas to the outside of the system;
An overspeed avoidance device for a regenerative gas turbine, comprising: valve control means for adjusting an opening degree of the discharge valve by feedback control based on a temperature of exhaust gas from the turbine. A compressor that generates high-pressure air;
A combustor for supplying and burning fuel to the high-pressure air;
A turbine that operates with combustion gas from the combustor to drive a load;
A regenerator for heating the high-pressure air with exhaust gas discharged from the turbine;
A vent valve for releasing a part of the working fluid comprising the high-pressure air, combustion gas or exhaust gas to the outside of the system;
An overspeed avoidance device for a regenerative gas turbine, comprising: valve control means for adjusting an opening degree of the discharge valve by feedback control based on a rotational speed of the turbine and a temperature of exhaust gas.   3. The overspeed avoidance device for a regenerative gas turbine according to claim 2, wherein the valve control means gradually lowers the target exhaust gas temperature after the start of control during feedback control.   4. The valve control means according to claim 3, wherein the valve control means selects a lower one of the two feedback control signals based on the rotational speed of the turbine and the temperature of the exhaust gas and outputs the selected one as a signal for adjusting the discharge valve. Overspeed avoidance device for regenerative gas turbine.   6. The air release valve according to claim 1, wherein the air release valve includes an on-off valve in which the opening degree changes in two stages of fully open and fully closed, and an adjustment valve in which the opening degree can be continuously changed. An overspeed avoidance device for a regenerative gas turbine.   The overspeed avoidance device for a regenerative gas turbine according to any one of claims 1 to 6, wherein the discharge valve is provided in a high-pressure air flow path between the compressor and the regenerator.   The overspeed avoidance device for a regenerative gas turbine according to any one of claims 1 to 6, wherein the discharge valve is provided in a flow path of high-pressure air between the regenerator and the combustor.   The overspeed avoidance device for a regenerative gas turbine according to any one of claims 1 to 6, wherein the discharge valve is provided in an exhaust gas flow path between an outlet of the turbine and a regenerator.

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