JPH05222906A - Controller for power plant utilizing exhaust heat - Google Patents

Abstract

PURPOSE:To carry out a stable control in relation to a load change by controlling a hot water flow rate, a medium flow rate, a medium by-pass flow rate and a cooling water flow rate based on a temperature deviation between the inlet and the exit of the evaporator of a hot water, a temperature deviation between the inlet and the exit of the preheater of a medium, the temperature deviation of a medium exhaust gas and the temperature deviation of a cooling water and the like. CONSTITUTION:A hot water is pumped up by a hot water pump 1 so as to pass in an evaporator 5 and preheaters 7, 8. A medium is circulated in the preheaters 7, 8, the evaporator 5, a medium turbine 20, a condenser 23, and a hot well tank 11. A hot water temperature is detected by a hot water temperature detector 3 and temperature detectors 6, 9 and a medium temperature is detected by temperature detectors 14, 22, 24. A cooling water temperature is detected by temperature detectors 27, 30. Further, a medium pressure is detected by pressure detectors 15, 19. A stable control is carried out in relation to an electric power load by controlling a hot water flow rate, a medium flow rate, a medium by-pass flow rate and a cooling water flow rate after inputting these detected signals into the controller of a power plant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an exhaust heat utilization power plant using high temperature hot water and a low boiling point medium.

[0002]

2. Description of the Related Art Generally, a waste heat power generation plant uses hot water in a subterranean hot water layer to exchange heat with a medium, evaporate the low boiling point medium in an evaporator, and reduce the vapor pressure of the medium turbine. To generate electricity. As the control in this case, the power generation output is controlled according to the load setting of the generator. That is, the medium flow rate is controlled with respect to the hot water temperature fluctuation, and the inlet pressure of the medium turbine is controlled by the pressure adjusting valve of the medium turbine bypass piping system.

Next, the flow rate of the cooling water is controlled by the condenser so that the exhaust gas spent for driving the medium turbine generator is controlled by the condenser. Further, the power load control of the waste heat utilization power plant is basically the maximum power operation. And
The output of the medium turbine generator fluctuates due to fluctuations in the hot water flow rate and hot water temperature, or fluctuations in the evaporation pressure of the medium in the evaporator.

[0004]

However, in such a conventional control device for an exhaust heat utilization power generation plant, the output of the generator fluctuates due to the hot water flow rate and temperature fluctuations of the primary system during power load control. This fluctuation largely depends on the heat exchange performance of the preheater and the performance of the evaporator. The level of the evaporation amount of the medium in the evaporator fluctuates with respect to the transient hot water flow rate and temperature fluctuations, and the evaporative gas pressure of the medium also fluctuates significantly accordingly. Therefore, the inlet flow rate and pressure of the medium turbine fluctuate, and the output of the medium turbine generator fluctuates significantly.

Further, as the load of the medium turbine generator fluctuates, the flow rate of exhaust gas spent for driving the medium turbine also fluctuates, and the amount of cooling water to the condenser also transiently fluctuates in the flow rate and temperature of the condenser and the secondary of the condenser. The cooling temperature of the medium also changes due to the delay.

As described above, the amount of heat exchange when preheating or evaporating the medium during the heat exchange in the evaporator, the preheater, and the medium system is controlled by the power load set power, but it is transient. There is a problem that the flow rate of the medium flow rate to the heat exchange fluctuates with the fluctuation of the hot water temperature, which causes the secondary delay of the heat exchanger of the preheater and the evaporator, and the output of the generator fluctuates and the control system becomes unstable. There is a point.

Therefore, an object of the present invention is to set the power load of the turbine generator, and to change the secondary temperature of the heat exchanger due to the fluctuations of the hot water temperature and flow rate of the hot water system and the medium temperature and flow rate of the medium system. By reducing the delay and reducing the secondary heat of the condenser when exchanging heat with the exhaust heat of the medium turbine and the cooling water supplied to the condenser, it is possible to prevent fluctuations in the output of the medium turbine generator. It is to provide a control device for a heat utilization power plant.

[0008]

The control device for an exhaust heat utilization power plant of the present invention is an evaporator for pumping high-temperature hot water from an underground hot water layer to evaporate a medium having a low boiling point and a preheater for preheating the medium. A hot water system that supplies heat to the medium and returns it to the reduction well, and supplies the medium from the medium tank to the preheater and the evaporator to exchange heat with the high-temperature hot water to supply the evaporated gas of the medium generated to the medium turbine. The exhaust gas that has generated power and has finished generating electricity is guided to a condenser, and a medium system that collects the medium that has been cooled to a low temperature with cooling water in a medium tank, and a cooling system that supplies cooling water that exchanges heat with the exhaust gas of the medium turbine from the cooling tower from the cooling tower. In a control device for an exhaust heat utilization power plant consisting of and, power generation is performed in consideration of the deviation between the inlet hot water temperature of the evaporator and the outlet hot water temperature and the deviation between the inlet medium temperature and the outlet medium temperature of the preheater. Output in advance The difference between the hot water temperature at the inlet of the evaporator and the hot water temperature at the outlet of the evaporator, and the difference between the inlet medium temperature of the preheater and the outlet medium temperature Evaporator outlet pressure control means for controlling the medium flow rate so that the outlet pressure of the evaporator becomes a predetermined outlet pressure set value, and the inlet hot water temperature and the outlet hot water temperature of the evaporator , The turbine inlet pressure control means for controlling the medium bypass flow rate so that the inlet pressure of the medium turbine becomes a predetermined inlet pressure set value, and the exhaust gas temperature at the medium turbine outlet and the condenser side Cooling water temperature control that controls the cooling water flow rate so that the cooling water temperature reaches its set value, taking into account the deviation from the medium tank temperature and the deviation between the cooling system cooling tower internal temperature and the condenser outlet cooling water temperature Having means and And butterflies.

[0009]

As a result, the temperature variation of the hot water flow rate for the power load follow-up control of the medium turbine generator, the pressure variation of the evaporative gas of the medium evaporator, and the heat exchange of a plurality of preheaters are used.
Second-order lag compensation, second-order lag compensation when exhaust gas driven by a medium turbine generator is heat-exchanged with cooling water in a condenser,
Following the temperature change of the cooling water, the load fluctuation of the medium turbine generator is prevented, the pressure fluctuation of the evaporative gas of the evaporator is prevented, the secondary delay is eliminated by the heat exchange of the preheater and the condenser, and the condenser The secondary delay of the condenser due to the fluctuation of the cooling water temperature can be eliminated.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a system diagram showing the construction of an exhaust heat utilization power plant to which the present invention is applied. The hot water is pumped up from the underground hot water layer by the hot water pump 1 and guided to the evaporator 5 through the hot water system 2. The evaporator 5 exchanges heat with the medium, and the first preheater 7 and the second preheater 8 exchange heat with the medium, and then return to the underground.

The flow rate adjusting valve 4 adjusts the flow rate of hot water at the inlet of the evaporator 5. That is, the power set value of the generator 21 of the medium turbine 20 and the second preheater 8
The opening degree of the inlet hot water flow rate adjusting valve 4 of the evaporator 5 is controlled based on the detection value of the hot water outlet flow rate detector 10 that detects the hot water flow rate at the outlet of the. Here, the hot water temperature from the hot water pump 1 is detected by the hot water temperature detector 3, the outlet hot water temperature of the evaporator 5 of the hot water system 2 is the temperature detector 6, and the second preheater 8 The outlet hot water temperatures of are detected by the temperature detectors 9, respectively.

Next, the medium is transferred to the second position by the medium pump 12.
Is supplied to the preheater 8 and further passes through the first preheater 7 to exchange heat with hot water. Then, it is heat-exchanged with hot water in the evaporator 5, becomes saturated steam, flows into the medium evaporation system, and is supplied to the medium turbine 20 under a specified pressure to generate electric power.
Drive to generate electricity. Further, the medium evaporation pressure supplied to the medium turbine 20 is adjusted by the bypass pressure adjusting valve 18. That is, based on the detection value of the inlet pressure detector 19 of the medium turbine 20, the bypass pressure control valve 1 of the bypass system 17
8 to control the inlet pressure of the media turbine 20.
The exhaust gas of the medium turbine 20 flows into the condenser 23 and exchanges heat with the cooling water. Then, it is collected in the hot well tank 11 and circulated. The outlet medium pressure of the evaporator 5 is controlled by the medium flow rate adjusting valve 13. That is, the medium flow rate adjusting valve 13 on the discharge side of the medium pump 12 is adjusted so that the outlet medium pressure of the evaporator 5 detected by the pressure detector 15 becomes a specified value.

Here, the temperature of the medium inlet of the evaporator 5 is the temperature detector 14, the temperature of the exhaust gas of the medium turbine 20 is the temperature detector 22, and the medium temperature in the hot well tank 11 is the temperature detector 24. Are detected respectively.

Next, the cooling water for cooling the medium in the condenser 23 is adjusted by the cooling water flow rate adjusting valve 26. That is, the opening degree of the flow rate adjusting valve 26 is controlled based on the temperature of the cooling water detected by the temperature detector 27 at the outlet of the condenser 23. The cooling water in the cooling tower tank 29 is supplied to the condenser 23 by the cooling water pump 25 and is heat-exchanged. That is, the cooling water passes through the cooling system 28, is cooled by the cooling fan of the cooling tower 29, and is circulated. The temperature inside the tank unit of the cooling tower 29 is detected by the temperature detector 30.

Next, FIG. 1 shows a control device 31 of the present invention for such a waste heat power generation plant. The detection signal of the hot water outlet flow rate detector 10 is linearized by the square root calculator 32 of the control device 31, and compared with the power set value by the power setter 33. The deviation signal is added to the addition / subtraction calculator 34. On the other hand, the signals of the bias units 39 and 43 are also input to the addition / subtraction calculator 34. As the signal of the bias device 39, a signal obtained by converting the detection signal of the hot water temperature detector 3 into a current signal by the temperature converter 37 and the detection signal of the outlet hot water temperature detector 6 of the evaporator 5 by the temperature converter 40. The signal converted into the current signal is added to the addition / subtraction calculator 38, and the signal subjected to the addition / subtraction calculation is used as a bias signal by the bias device 39. On the other hand, the signal of the bias device 43 is the signal obtained by converting the detection signal of the inlet medium temperature detector 14 of the evaporator 5 into the current signal by the temperature converter 41 and the detection signal of the medium temperature detector 24 of the hot well tank 11. The signal converted into the current signal by the temperature converter 44 and the addition / subtraction calculator 4
The signal obtained by the addition / subtraction calculation in 2 is used as a bias signal in the bias device 43. In the adding / subtracting calculator 34, the PID controller 35 obtains a control signal from the arithmetic signal obtained by adding each, and the electropneumatic converter 36 converts the current signal into an air signal to open the flow rate adjusting valve 4 at the hot water inlet. Control the degree. As a result, the hot water flow rate is controlled by following the power set value of the generator 21 of the medium turbine 20.

Next, the detection signal of the outlet pressure detector 15 of the evaporator 5 of the medium system is compared with the pressure set value by the pressure setter 45, and the deviation signal is added to the addition / subtraction calculator 46. On the other hand, the signals of the bias devices 39 and 43 are also input to the addition / subtraction calculator 46. As the signal of the bias device 39, a signal obtained by converting the detection signal of the hot water temperature detector 3 into a current signal by the temperature converter 37 and the detection signal of the outlet hot water temperature detector 6 of the evaporator 5 by the temperature converter 40. The signal converted into the current signal and the addition / subtraction calculator 3
In addition to 8, the bias signal is used as a bias signal by the bias device 39. On the other hand, the signal of the bias device 43 is the signal obtained by converting the detection signal of the inlet medium temperature detector 14 of the evaporator 5 into the current signal by the temperature converter 41 and the detection signal of the medium temperature detector 24 of the hot well tank 11. The signal converted into the current signal by the temperature converter 44 and the addition / subtraction calculator 42
The signal which has been subjected to the addition / subtraction calculation in step 4 is used as a bias signal in the bias device 43. In the adder / subtractor calculator 46, a calculation signal obtained by adding each is obtained by a PID controller 47 to obtain a control signal, and an electropneumatic converter 48 converts a current signal into an air signal, and the evaporator 5
The outlet medium evaporating pressure is controlled according to the pressure set value to control the opening degree of the medium flow rate adjusting valve 13.

Next, the detection signal of the inlet pressure detector 19 of the medium turbine 20 is compared with the medium turbine pressure set value by the pressure setter 49, and the deviation signal is added to the addition / subtraction calculator 50. On the other hand, the signal of the bias unit 39 is also input to the addition / subtraction calculator 50. As the signal of the bias device 39, a signal obtained by converting the detection signal of the hot water temperature detector 3 into a current signal by the temperature converter 37 and the detection signal of the outlet hot water temperature detector 6 of the evaporator 5 by the temperature converter 40. The signal converted into the current signal is added to the addition / subtraction calculator 38, and the signal subjected to the addition / subtraction calculation is used as a bias signal by the bias device 39. In the addition / subtraction calculator 50, a control signal is obtained by the PID controller 51 from these added calculation signals, and a current signal is converted into an air signal by the electropneumatic converter 52, so that the inlet pressure of the medium turbine 20 becomes a pressure set value. Following this, the opening degree of the medium turbine bypass pressure adjusting valve 18 is controlled.

Next, in order to make the medium cooling temperature of the condenser 23 constant, a signal obtained by converting the detection signal of the outlet cooling water temperature detector 27 of the condenser 23 into a current signal by the temperature converter 56 is set as a temperature setter. At 57, the temperature setting value is compared. Then, the deviation signal is added to the adjustment calculator 58. Further, the detection signal of the outlet cooling water temperature detector 27 of the condenser 23 is converted into the temperature converter 56.
The signal converted into the current signal by the controller 29 and the signal converted from the detection signal of the temperature detector 30 inside the tank of the cooler 29 into the current signal by the temperature converter 61 are subjected to the addition and subtraction operation by the addition and subtraction calculator 62, and the bias device 64 is It is added to the addition / subtraction calculator 58 via Further, the bias signal of the bias unit 54 is added to the addition / subtraction calculator 58. Then, the PID controller 59 obtains the control signals from these arithmetic signals, the electro-pneumatic converter 60 converts the current signal into an air signal, and the cooling water temperature of the condenser 23 follows the temperature set value and the condenser 23 The opening degree of the inlet flow rate adjusting valve 26 is controlled.

Therefore, by following the electric power load setting of the medium turbine, the evaporator can respond to fluctuations in the hot water flow rate and temperature, the medium flow rate and temperature, the cooling water flow rate and temperature in the hot water system.
It is possible to prevent secondary delay due to heat exchange between the preheater and the condenser and improve heat exchange efficiency.

That is, according to the present invention, the opening control signal of the first flow rate adjusting valve 4 for controlling the flow rate of hot water in the hot water system is set for the power load setting of the medium turbine generator 21.
The hot water temperature deviation at the inlet / outlet of the evaporator 5 and the medium temperature deviation at the inlet / outlet of the preheaters 7, 8 of the medium system are added in advance as bias signals, and the output of the medium turbine generator 21 sets the power. The second-order lag in heat exchange due to transient fluctuations of the evaporator 5 and the preheaters 7 and 8 is compensated so that continuous control can be stably performed.

Further, the flow rate adjusting valve 1 for controlling the medium flow rate of the medium system with respect to the vapor gas pressure setting of the medium of the evaporator 5
To the opening control signal of 3, the hot water temperature deviation at the inlet / outlet of the evaporator 5 and the medium temperature deviation at the inlet / outlet of the preheaters 7 and 8 of the medium system are added in advance as bias signals. A secondary delay in heat exchange due to transient fluctuations of the evaporator 5 and preheaters 7 and 8 is compensated so that the outlet evaporative gas pressure of 5 can be stably controlled continuously with respect to the evaporative gas pressure setting.

Next, with respect to the pressure setting of the inlet gas pressure of the medium turbine 20, the evaporator 5 is sent to the opening signal of the pressure adjusting valve 18 for controlling the pressure of the bypass system of the medium turbine 20.
The inlet / outlet hot water temperature deviation signal is added as a bias signal in advance to stably control the inlet pressure of the medium turbine, and the transition of the medium flow rate with respect to the power load setting of the medium turbine generator 21 is transient. The opening of the medium bypass pressure adjusting valve 18 is controlled in order to reduce the fluctuation of the evaporative gas pressure due to the above and to stably and continuously control the output of the medium turbine generator 21.

Further, in order to cool the temperature of the exhaust gas of the medium turbine 20 constant, the opening signal of the flow rate adjusting valve 26 for controlling the cooling water amount of the cooling water system with respect to the cooling water temperature setting at the outlet of the condenser 23. In addition, the deviation signal between the exhaust gas temperature at the outlet of the medium turbine 20 and the hot well internal temperature at the outlet of the condenser 23, the cooling tower tank internal temperature of the cooling water system, and the condenser 2
A deviation signal from the cooling temperature at the outlet of No. 3 is added as a bias signal to cope with a transient fluctuation of the exhaust gas amount of the medium turbine 20 so that the medium temperature at the outlet of the condenser 23 can be stably and continuously controlled. The cooling water flow rate is controlled so as to reach the cooling water temperature set value. Therefore, with respect to the transient disturbance of the hot water system, the medium system, and the cooling water system of the waste heat utilization power plant and the power setting load of the medium turbine generator, the evaporator 5, the preheaters 7 and 8, and the condenser 23 It is possible to compensate for the secondary delay at the time of heat exchange in order to improve the thermal efficiency and to control by following the load fluctuation.

Therefore, when a predetermined power load is set, the hot water flow rate of the hot water system becomes a function of the power load setting,
The hot water flow rate on the inlet side of the preheater is controlled by setting the opening of the flow rate adjusting valve 4 to a set value. Further, the deviation signal between the temperature detector 3 at the evaporator inlet of the hot water system and the temperature detector 9 at the outlet of the preheater, and the temperature detector 24 in the hot well tank device of the medium system and the temperature detection at the inlet of the evaporator 5 are detected. The deviation signal of the instrument 14
A bias signal is added in advance to each of the evaporators 5,
The preheaters 7 and 8 follow the set power of the medium turbine generator 21 by compensating for the secondary delay at the time of heat exchange so that the opening degree of the hot water flow rate adjusting valve 4 at the inlet of the evaporator 5 becomes a set value. Control.

When the evaporative gas pressure of the medium at the outlet of the evaporator 5 is set to a predetermined value, the medium pressure of the medium system is adjusted by controlling the opening of the pressure regulating valve 18 to the set value. To be done. Further, the deviation signal between the temperature detector 3 at the inlet of the evaporator 5 of the hot water system and the temperature detector 14 at the outlet of the preheaters 7, 8 and the temperature detector 24 and the evaporator in the hot well tank device of the medium system The deviation signal from the temperature detector 14 at the inlet of 5 is added as a bias signal in advance and added to the evaporator 5,
The preheaters 7 and 8 control the outlet evaporation gas pressure of the medium evaporator 5 so as to follow the set value by compensating for the secondary delay at the time of heat exchange so that the opening of the pressure regulating valve 18 becomes the set value.

Next, when the inlet pressure of the medium turbine 20 is set to a predetermined value, the inlet pressure of the medium turbine 20 of the medium evaporation system is the pressure detector 19 at the inlet of the medium turbine 20.
Is adjusted by controlling the opening degree of the pressure adjusting valve 18 of the medium turbine bypass line to a set value. Further, the deviation signal between the temperature detector 3 at the inlet of the evaporator 5 of the hot water system and the temperature detector 9 at the outlet of the preheaters 7 and 8 is added as a preceding bias signal for compensation, thereby compensating for the medium turbine 20. The inlet pressure follows the set value, and the opening of the pressure adjusting valve 18 of the medium turbine bypass line is controlled to reach the set value.

When the cooling water temperature of the cooling water system is set to a predetermined value, the outlet temperature of the condenser 23 of the cooling water system is
The amount of cooling water at the inlet of the condenser 23 is the cooling water flow rate adjusting valve 26.
It is controlled by controlling the opening degree of the control valve to a set value.

Further, a deviation signal between a temperature detector 22 for detecting the exhaust gas temperature of the medium turbine 20 of the medium system and a temperature detector 24 for detecting the internal temperature of the hot well tank 11 for cooling and storing the medium, The deviation signal of the temperature detector 27 for detecting the condenser outlet temperature of the cooling water system and the temperature detector 30 for detecting the inside temperature of the cooling tower tank cooled by the cooling tower 29 is added in advance as a bias signal for compensation. By controlling the cooling medium temperature to a specified value, the cooling water temperature at the condenser outlet is adjusted to the cooling water flow rate adjusting valve 26 at the condenser inlet.
The opening degree of is controlled to the set value. Therefore, the evaporator 5, the preheater 7, and the power load setting of the medium turbine 20 are tracked.
8. The secondary delay in heat exchange of the condenser 23 can be compensated for in advance, and transient hot water, low boiling point medium, cooling water temperature / flow rate fluctuations can be controlled.

[0030]

As described above, according to the present invention, for the power setting load of the waste heat utilization system power plant,
It is possible to prevent the medium evaporation pressure fluctuation of the evaporator due to the hot water flow rate and temperature fluctuation of the hot water evaporator. Furthermore, in order to prevent fluctuations due to secondary delays during heat exchange between the hot water and the medium in the preheater and to prevent transient load fluctuations, the rate of temperature change at the evaporator inlet / outlet of the hot water system is set in advance. And the temperature change rate at the evaporator inlet and the temperature change rate at the evaporator inlet of the collected hot well tank of the medium system are added as bias signals to control the opening of the hot water flow rate adjusting valve. Control that follows power can be achieved. In addition, by improving the heat exchange rates of the condensers of the hot water system, medium system, and cooling water system so that fluctuations in the medium turbine inlet pressure are minimized, stable control of transient load fluctuations is possible. And it can operate with high efficiency.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an exhaust heat utilization power plant to which a control device of the present invention is applied.

FIG. 2 is a block diagram showing an embodiment of the present invention.

[Explanation of symbols]

1 Hot water pump 2 Hot water system 3,6,9,14,22,24,27,30 Temperature detector 4,13,26 Flow rate adjustment valve 18 Pressure adjustment valve 5 Evaporator 7,8 Preheater 10 Flow rate detector 11 hot well tank 12 medium pump 15, 19 pressure detector 16 medium system 17 bypass system 20 medium turbine 21 generator 23 condenser 25 cooling water pump 28 cooling water system 29 cooler 31 controller

Claims (1)

[Claims] 1. A hot water system that pumps high-temperature hot water from an underground hot water layer to an evaporator that evaporates a medium having a low boiling point and a preheater that preheats the medium, exchanges heat with the medium, and returns to a reduction well. , The medium is supplied from the medium tank to the preheater and the evaporator to exchange heat with the high-temperature hot water, the evaporative gas of the medium generated there is supplied to the medium turbine to generate power, and the exhaust gas that has finished power generation is transferred to the condenser. A waste heat power generation plant comprising a medium system for collecting a medium whose temperature has been lowered by cooling water into the medium tank, and a cooling system for supplying cooling water that exchanges heat with exhaust gas of the medium turbine in the condenser from a cooling tower. In the control device, the electric power whose power generation output is predetermined in consideration of the deviation between the inlet hot water temperature and the outlet hot water temperature of the evaporator and the deviation between the inlet medium temperature and the outlet medium temperature of the preheater in advance. Configuration Power load control means for controlling the flow rate of hot water so that the value becomes a value, the deviation between the inlet hot water temperature and the outlet hot water temperature of the evaporator, and the deviation between the inlet medium temperature and the outlet medium temperature of the preheater are preceded. In addition, the evaporator outlet pressure control means for controlling the medium flow rate so that the outlet pressure of the evaporator becomes a predetermined outlet pressure set value, and the inlet hot water temperature and the outlet hot water temperature of the evaporator Of the medium turbine outlet pressure control means for controlling the medium bypass flow rate so that the inlet pressure of the medium turbine reaches a predetermined inlet pressure set value by taking into account the deviation of Cooling water flow rate so that the cooling water temperature becomes its set value, taking into consideration the deviation between the temperature inside the medium tank on the condenser side and the deviation between the temperature inside the cooling tower of the cooling system and the outlet cooling water temperature of the condenser. Control the cooling Control device for waste heat utilization power plant, characterized in that a temperature control means.