JPH0476259A - Heat and electricity parallel supply device - Google Patents

Abstract

PURPOSE:To prevent reduction of the supply due to load fluctuations on heat load side by making it possible to switch the operation modes of electric load follow-up operation and heat load follow-up operation by switching operation of a switch device, and giving preference to load on high load side when variation in steam load and hot-water load is corrected at the time of heat load follow-up operation. CONSTITUTION:In a heat and electricity supply device in which an exhaust heat heat exchanger and an exhaust gas heat exchanger are installed to an internal combustion engine for driving an electricity generator, a detection value of a fuel flow detector 4 is compared to a set electric power of the generator to determine a deviation, and add values of detection values of respective hot-water flow detectors 26, 28 are compared to a detection value of a steam flow detector 24 to select a high value by a high value preferred circuit 34 and to adjust the opening of a fuel flow adjusting valve 3 by a switching device 42 when heat load is followed up. A signal obtained by adding detection values of the hot-water flow detectors 26, 28 is outputted as a bias signal to an adder-subtractor 57, and a limit value check of a variation obtained by calculating signals of a detection value of the temperature in a steam accumulator and a detection value of the hot-water temperature at the outlet of the exhaust heat heat exchanger, is performed by a limiter 52 to adjust the opening of a hot-water flow adjusting valve 21 when the variation is within the limit value.

Description

Detailed Description of the Invention Object of the Invention (Industrial Field of Application) The present invention relates to a combined heat and power system that supplies electric power, steam, and hot water, and particularly relates to a combined heat and power system that supplies electric power, steam, and hot water, and particularly relates to a combined heat and power system that supplies electric power, steam, and hot water. In order to eliminate load fluctuations with respect to the load requirements of the hot water load of the heat exchanger and the steam load of the steam regenerator that generates and stores steam using the exhaust gas of the internal combustion engine, the hot water load and steam are combined as preceding elements. The present invention relates to a combined heat and power supply system that controls the fuel flow rate of an internal combustion engine in accordance with the amount of load and prevents load fluctuations due to secondary delays in hot water temperature control.

(Prior art) A combined heat and power system generally cools an internal combustion engine that drives a generator with cold water from an exhaust heat exchanger, uses the exhaust heat to convert the cold water into hot water, and then transfers this hot water to the exhaust gas heat exchanger. The hot water and steam are then stored in a hot water tank and a heat storage tank, respectively, and supplied to a hot water load or steam load by a heat load device. .

The heat storage control method of this combined heat and power system is based on the detected steam pressure on the outlet side of the exhaust gas heat exchanger, so that the pressure of the steam stored in the heat storage tank is constant. Controls the flow rate of hot water supplied to the side inlet. In addition, as a hot water load control method, hot water is transferred from the waste heat heat exchanger to the hot water heat exchanger and the exhaust gas heat exchanger so that the temperature of the hot water supplied from the hot water heat exchanger and the hot water storage tank to the hot water load is constant. The flow rate of cold water supplied to the heat receiving side (secondary side) inlet of the waste heat heat exchanger is controlled to match the set value based on the detected temperature value in the hot water header distributed to the exhaust heat exchanger. Further, the flow rate of hot water supplied to the hot water load is controlled by each water supply valve and hot water valve so that the exhaust heat is constant based on the detected temperature value in the hot water storage tank.

(Problems to be Solved by the Invention) In the conventional combined heat and power system configured as described above, when the load of the internal combustion engine fluctuates, the exhaust gas flow rate of the secondary system fluctuates, and the exhaust gas heat exchanger outlet By controlling the opening degree of the hot water flow rate adjustment based on the steam pressure, the heat exchange efficiency of the exhaust heat exchanger decreases, and the load fluctuation increases with respect to the required steam load and hot water load. In addition, the amount of exhaust heat from the internal combustion engine is insufficient in response to load fluctuations in the hot water load and steam load, and this essentially results in load fluctuations in the supply amount of the hot water load and steam load.

The steam pressure generated by the exhaust gas heat exchanger is stored in the heat storage tank, but depending on the increase or decrease in the steam load, the internal pressure of the heat storage tank decreases due to the effects of heat radiation from the heat storage tank, etc. When the steam load decreases or when the hot water load increases, the amount of exhaust heat from the internal combustion engine must be increased. Furthermore, there is a problem in that a secondary delay occurs due to fluctuations in the hot water load requirement.

In addition, the temperature of the hot water header to which hot water is supplied from the heat receiving side (secondary side) outlet of the waste heat heat exchanger fluctuates relative to the set value,
Moreover, as the hot water fluctuates in the exhaust heat flow rate of the primary system, the amount of heat exchanged also substantially decreases due to the secondary lag cause of the exhaust heat exchanger, and the fluctuation range of the hot water temperature at the outlet of the exhaust gas heat exchanger. There was a problem that the value became larger than the set value. In addition, during thermal load following operation, fluctuations in the amount of heat exchange due to secondary delay causes of exhaust heat heat exchanger exhaust heat and exhaust gas heat exchanger,
There was a problem that the steam load and hot water load fluctuations were larger than the set values.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a combined heat and power generation device that can prevent a drop in steam pressure and hot water temperature during changes in internal combustion engine load, steam load, and hot water load. It is something.

[Configuration of the Invention (Means for Solving the Problems) The combined heat and power generation device of the present invention includes an internal combustion engine that drives a generator;
A fuel flow rate detector and a fuel flow rate adjustment valve that detect and adjust the flow rate of fuel supplied to the internal combustion engine; and an exhaust heat exchanger that heats cold water using exhaust heat from the internal combustion engine to generate hot water. ; a hot water temperature detector for detecting the outlet temperature of hot water supplied to the heat receiving side of the waste heat heat exchanger; and a cold water flow rate adjustment valve for adjusting the cold water supply flow rate; hot water from the heat receiving side of the waste heat heat exchanger; a steam regenerator for storing heat of steam generated by further heating with the exhaust gas from the internal combustion engine in the exhaust gas heat exchanger; a first for adjusting the supply flow rate of hot water supplied to the exhaust heat heat exchanger; a hot water flow rate adjustment valve that detects the hot water temperature inside the steam heat storage device and adjusts the supply flow rate to the hot water header; a second hot water flow rate regulating valve that adjusts the flow rate of hot water supplied to the hot water load; 2 hot water flow rate detector: a steam flow rate detector that detects the supply flow rate of steam supplied from the steam regenerator to the steam load; an internal pressure detector that detects the internal pressure of the steam regenerator; a comparator that compares a detection value detected by the fuel flow rate detector with a power setting value of the generator and outputs a deviation; and the first and second hot water flow rate detectors. The added value of the hot water flow rate detection value detected by the steam flow rate detector is compared with the steam flow rate detection value detected by the steam flow rate detector mentioned above, and the fuel flow rate is determined by the output signal of the high value priority circuit which outputs the higher value. a controller that adjusts the opening degree of the regulating valve and provides a control signal to the fuel flow regulating valve; and a controller that calculates the detected value of the hot water supply flow rate detected by the first and second hot water flow rate detectors using an addition/subtraction calculation circuit, respectively. , a temperature detection value inside the steam regenerator as a bias signal;
A limit value check of the deviation value calculated by the addition/subtraction calculator is performed on the signal of the detected temperature value of the hot water at the outlet of the waste heat heat exchanger, and if it is within the limit value, the deviation signal is used as a bias signal to control the waste heat heat exchanger. Compare the detected temperature value at the outlet of the chamber with the temperature set value, add or subtract the difference signal between them to the signal given to the controller, adjust the flow rate of cold water supply to the heat receiving side of the waste heat heat exchanger, The hot water supply temperature detection values detected by the first and second hot water supply temperature detectors are compared with the temperature set value, and their deviation signals are provided to the controller to apply the bias signal in advance, and the bias signal is applied in advance to the controller. A preceding control device is provided to the first and second hot water flow rate adjustment valves and the cold water flow rate adjustment valve to adjust the valve opening degrees.

(Function) In the device of the present invention configured as described above, when performing electric load following operation of the combined heat and power generation device, when the electric load following operation mode is selected as the operation mode of the switch, the fuel supplied to the internal combustion engine is The opening degree of the fuel flow control valve that adjusts the supply amount of the fuel is adjusted so that the deviation between the detector of the fuel flow detector that detects the fuel supply flow rate and the power set value is zero, and the electric power that corresponds to the electric load request is adjusted. Load following operation is performed.

On the other hand, when performing thermal load following operation of the combined heat and power generation device,
When the operating mode of the switch is selected as thermal load following operation Moto, the opening degree of the fuel flow rate adjustment valve that controls the flow rate of fuel supplied to the internal combustion engine is controlled to follow fluctuations in the steam load and hot water load. Ru.

That is, the opening degree of the fuel flow rate control valve is adjusted by adjusting the steam load and the signal of the hot water flow rate detection value that detects the first and second hot water supply flow rates, and the signal obtained by calculating the hot water load amount using the addition/subtraction calculation circuit. Based on the signal from the high value priority circuit that gives priority to the high value, the opening degree of the fuel flow N regulating valve is controlled to give priority to the supply amount of the steam load and the hot water load, and the electric power load is operated to follow the heat load.

If the hot water load is insufficient, check the control value of the temperature inside the steam regenerator described above, the hot water temperature at the outlet of the exhaust heat heat exchanger of the internal combustion engine, and the deviation signal, and if it is within the limit value, the signal is As a bias signal, the opening degree of the cold water flow rate regulating valve is adjusted and operated in response to hot water load fluctuations. Furthermore, adding and subtracting the signals of each of the first and second hot water flow rate detectors,
The signal is applied as a bias signal to the first and second hot water flow rate regulating valves, and the opening degrees of these valves are adjusted.

(Example) The present invention will now be described in detail with reference to the drawings.

FIG. 2 is a system diagram showing the overall configuration of an embodiment of the device of the present invention, in which the supply flow rate of fuel supplied to the internal combustion engine 2 that drives the synchronous generator 1 is controlled by a fuel flow rate regulating valve 3;
It is detected by the fuel flow rate detector 4.

The internal combustion engine 2 is cooled by an exhaust heat exchanger 5 such as a water jacket, and its exhaust gas is discharged through the heating side body of the exhaust gas heat exchanger 6.

A cold water inlet on the heat receiving side (secondary side) of the waste heat heat exchanger 5 is connected to a heating side outlet of the hot water storage tank 7 via a cold water pipe 5a. This cold water pipe includes, from the upstream side to the downstream side, a hot water tank three-way valve (second hot water flow rate adjustment valve) 8, a cold water header 9 connected to a cold water source (not shown), a cold water pump 10,
Cold water flow rate adjustment valves 11 are installed in sequence, and are configured to supply cold water to the heat receiving side inlet of the waste heat exchanger 5.

A hot water header 9b is connected to the heat receiving side outlet of the waste heat exchanger 5 via a hot water pipe 13 equipped with a hot water temperature detector 12 for detecting hot water temperature. In addition, the hot water header 9b is
It is connected to the heating side inlet of the hot water heat exchanger 14, and is also connected to the steam heat storage device 15 via the hot water pipe 15a.

The other outlet end of the hot water header 9b is connected to the heating side inlet of the exhaust gas heat exchanger 6 via a pipe 6a. A hot water pump 16 and a flow rate regulating valve 17 are inserted in the middle of the piping 6a from the upstream side to the downstream side, and the hot water pump 16 supplies hot water to the exhaust gas heat exchanger 6 from the internal combustion engine 2. It is heated by exhaust gas to generate steam. A heat receiving side outlet of the exhaust gas heat exchanger 6 is connected to a steam load (not shown) side via a steam pipe 6b. A steam regenerator 15 is inserted in the middle of the steam pipe 6b, and a steam pressure detector 18 and a steam flow rate detector 24 are connected before and after the steam regenerator 15.

Inside the steam regenerator 15, an internal temperature detector 19 and an internal pressure detector 20 are installed.

Further, a hot water flow rate adjustment valve 21 and a hot water flow rate detector 22 are installed in the middle of the hot water pipe 15a.

A hot water heat exchanger three-way valve (first hot water flow rate regulating valve) 23 is inserted in the middle of the heating side communication pipe 23a of the hot water heat exchanger 14.

A cold water supply pipe 25a is connected to the heat receiving side of the hot water heat exchanger 14, and an outlet of the heat receiving side is connected to a hot water load (not shown) via a first hot water supply pipe 25b.

A first hot water temperature detector 25 and a first hot water flow rate detector 26 are installed in the middle of the first hot water supply pipe 25b.

On the other hand, the body of the heat receiving part of the hot water storage tank 7 is connected to the second hot water supply pipe 2.
7a to the hot water load side, and a second hot water temperature detector 27 and a second hot water flow rate detector 28 are installed in the middle of the second hot water supply pipe 27a.

One end of the hot water tank three-way valve 8 is connected to the heating side communication pipe 23a of the hot water heat exchanger 14.

The control device 29 has a fuel flow rate adjustment valve 3, a fuel flow rate detector 4, a cold water flow rate adjustment valve 11, a hot water temperature detector 12, a hot water supply flow rate adjustment valve 17, a steam pressure detector 18, An internal temperature detector 19 and an internal pressure detector 20 of the steam regenerator 15, a hot water flow rate adjustment valve 21, a hot water flow rate detector 22, a hot water heat exchanger three-way valve (first hot water flow rate adjustment valve) 23
, first hot water temperature detector 25, first hot water flow rate detector 2
6. The hot water tank three-way valve 8, the second hot water temperature detector 27, and the second hot water flow rate detector 28 are electrically connected, and the opening degrees of the various regulating valves are adjusted based on the detected values from each detector. Control.

The control device 29 is configured as shown in FIG.

That is, the fuel supply flow rate signal supplied to the internal combustion engine 2 detected by the fuel flow rate detector 4 is linearized by the square root calculator 30a, compared with a setting signal proportional to electric power by the power setting device 41, and the deviation thereof is When following electrical load, the signal is
The signal flows through the switch 42 to a 7 b, and becomes a control signal at the PID controller 43. This control signal is turned into an air signal by an electro-pneumatic converter 44 that converts an electric signal into an air signal, and the opening degree of the fuel flow rate regulating valve 3 is adjusted so that the output of the generator 1 is controlled to be constant.

On the other hand, during thermal load tracking, the signal from the steam flow rate detector 24 is smoothed by the square root calculator 30b, and then smoothed by the high value priority circuit 30b.
4 is input. In addition, the first hot water flow rate detector 26 and the second
The detection signals of the hot water flow rate detector 28 are respectively output by the square root calculator 3.
After being smoothed by signals 0c and 30d and added by an addition/subtraction calculator 33, the signal is led to a high value priority circuit 34 and compared with the signal from the square root calculator 30b, and the signal with the highest value is led to a switch 42 and then added to the PID The controller 34 converts the signal into a control signal, which is converted into an air signal by the electro-pneumatic converter 44 to control the opening degree of the fuel flow rate regulating valve 3.

The pressure of steam generated by heat exchange with the exhaust gas of the internal combustion engine 2 in the exhaust gas heat exchanger 6 is detected by the steam pressure detector 18, and compared with a pressure setting value by the pressure setting device 35 to generate a deviation signal. Further, the pressure signal from the steam pressure detector 18 and the pressure signal from the internal pressure detector 20 of the steam regenerator 15 are added and subtracted by an addition/subtraction calculator 36, and a bias signal is added to the obtained signal by a biaser 37. After that, it is led to the addition/subtraction calculator 38 together with the deviation signal from the pressure setting device 35, and is subjected to addition/subtraction calculations. The output signal of the addition/subtraction calculator 38 is P
The signal is converted into a control signal by the ID controller 39 and converted into an air signal by the electro-pneumatic converter 45 to adjust the opening degree of the hot water flow rate regulating valve 17 and control the steam pressure.

The hot water temperature at the outlet of the waste heat heat exchanger 5 is determined by the hot water temperature detector 12.
After being detected by the temperature converter 46 and converted into a current signal, it is compared with the temperature setting value in the temperature setting device 47, and is converted into a calculation signal and guided to the PID controller 48, and then converted into an air signal by the electro-pneumatic converter 49. After being converted into cold water flow regulating valve 1
1 is adjusted to control the temperature of cold water supplied to the hot water header 9b.

The detected value of the internal temperature detector of the steam regenerator 15 is converted into a current signal by the temperature converter 50, and is led to the addition/subtraction calculator 51 together with the current signal from the temperature converter 46 for addition/subtraction calculation. The output of the addition/subtraction calculator 51 is checked for upper and lower limits by a limiter 52, and if it is within the limit value, it is input to a biaser 53. Further, the current signal from the temperature converter 50 is compared with the temperature setting value in the temperature setting device 54, and the deviation signal is
It is input to the D controller 55.

On the other hand, the signal obtained by the addition/subtraction calculator 33 is sent to the bias unit 5.
This bias signal, the signal from the bias device 53, and the control signal from the PID controller 55 are added and subtracted by an addition/subtraction calculator 57, and the output is converted to a bias signal by an electro-pneumatic converter. At step 58, the signal is converted into an air signal, and the opening degree of the hot water flow rate regulating valve 21 is adjusted to control the temperature of the hot water header 9b.

The temperature of the hot water supplied to the secondary side of the hot water heat converter 14 is detected by the first hot water temperature detector 25, this detected value is converted into a current signal by the temperature converter 60, and the temperature is set by the temperature setting device 61. It is compared with the set value, the deviation signal is led to the PID controller 62 as a control signal, this signal and the bias signal from the bias device 56 are added and subtracted by the adder/subtractor 63, and the obtained signal is electro-pneumatically The converter 64 converts it into an air signal, and adjusts the opening degree of the hot water heat exchanger three-way valve (first hot water flow rate regulating valve) 23 to control the first hot water supply temperature.

Furthermore, after the detection signal of the second hot water temperature detector 27 is converted into a current signal by the temperature converter 65, it is compared with the temperature setting value by the temperature setting device 66, and the deviation signal is guided to the PID controller 67 for control. This control signal and the bias signal from the bias device 56 are added and subtracted by an addition/subtraction calculator 68, and the obtained signal is converted into an air signal by an electro-pneumatic converter 69.
The second hot water supply temperature is controlled by adjusting the opening degree of the hot water flow rate adjustment valve (hot water tank three-way valve) 8.

With the above configuration, load fluctuations in the hot water supply flow rate supplied from the hot water storage tank 7 and the hot water heat exchanger 14 and the steam heat storage 15
The higher value priority circuit selects the higher value of the steam load flow rate supplied from the generator and the steam load flow rate supplied from the generator to increase the generator output during thermal load tracking, thereby preventing a drop in load supply due to thermal load fluctuation factors.

Furthermore, even if the hot water load increases instantaneously, it is possible to effectively utilize the hot water in the steam regenerator to prevent a drop in the supply load due to fluctuations in the heat load.

[Effects of the Invention] As explained above, the present invention is capable of switching the operation mode between electrical load following operation and thermal load following operation by switching the switching device, and moreover, it is possible to switch the operation mode between the electric load following operation and the thermal load following operation, and moreover, the operation mode can be switched between the steam load and hot water load during the thermal load following operation. A high load priority circuit prioritizes the load on the high load side and increases or decreases the load on the internal combustion engine that drives the generator, thereby reducing supply due to load fluctuations on the thermal load side. can be prevented.

Furthermore, when the hot water load increases relative to the steam load amount, the heat utilization rate can be improved by using the hot water in the steam heat storage device to prevent fluctuations in the hot water load.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing essential parts of an embodiment of a control device in a combined heat and power generation device according to the present invention, and FIG. 2 is a block diagram illustrating the overall configuration of the combined heat and power generation device. 1...Synchronous generator 2...Internal combustion engine 3.8, 11.17, 21.23...Adjusting valve 4.22
, 24, 26.28...Flow rate detector 5.6...Exhaust heat exchanger 7...Hot water storage tank 9a...Cold water header 9b... ......Hot water header 10...Cooling pump 12.19.25.27...Temperature detector 13...
...Hot water system 14...Hot water heat exchanger 15...Steam heat storage 16...Hot water supply pump 18.20・・・
・Pressure detector 29...Control device 30a to 30d...Square root calculator 33.35, 36, 38, 51, 57.63°6 8.
...... Addition/subtraction calculator 34... High value priority circuit 35.41, 47, 54, 61.66... Setting device 37.56... Bias device 39. 43.48.55, 62.67... PID controller 42... Switcher 44.45.49, 58, 64.69... Electro-pneumatic converter

Claims (1)

[Claims] an internal combustion engine that drives a generator; a fuel flow detector and a fuel flow adjustment valve that detect and adjust the flow rate of fuel supplied to the internal combustion engine; and hot water by heating cold water using exhaust heat from the internal combustion engine. an exhaust heat heat exchanger that generates; a hot water temperature detector that detects the outlet temperature of hot water supplied to the heat receiving side of the exhaust heat heat exchanger; and a cold water flow rate adjustment valve that adjusts the cold water supply flow rate; a steam regenerator for storing heat of steam generated by further heating hot water from the heat receiving side of the heat exchanger with exhaust gas from the internal combustion engine in an exhaust gas heat exchanger; a first hot water flow rate adjustment valve that adjusts the flow rate of hot water supplied to the hot water header; a hot water flow rate adjustment valve that detects the temperature of hot water in the steam heat storage device and adjusts the flow rate of hot water supplied to the hot water header; A second controller that adjusts the flow rate of hot water supplied from the heating side of the heat exchanger to the heating side of the hot water storage tank.
a hot water flow rate regulating valve; first and second hot water flow rate detectors for detecting the hot water supply flow rates respectively supplied to the hot water load from the respective heat receiving sides of the hot water heat exchanger and the hot water storage tank; In a combined heat and power system having: a steam flow rate detector that detects the supply flow rate of steam supplied to a steam load; and an internal pressure detector that detects the internal pressure of the steam regenerator; a comparator that compares the detected value and the power setting value of the generator and outputs a deviation; an added value of the hot water flow rate detection values detected by the first and second hot water flow rate detectors; The fuel flow rate is adjusted by comparing the detected steam flow rate values detected by the steam flow rate detector and adjusting the opening degree of the fuel flow rate adjustment valve using the heat load follow-up switching device based on the output signal of the high value priority circuit that outputs the high value. a controller that provides a control signal to the valve; a hot water supply flow rate detection value detected by the first and second hot water flow rate detectors is calculated by an addition/subtraction calculation circuit; The temperature detection value and the signal of the hot water temperature detection value at the outlet of the exhaust heat heat exchanger are checked for the limit value of the deviation value calculated by the adder/subtraction calculator, and if it is within the limit value, the deviation signal is used as the bias signal. The detected temperature value at the outlet of the exhaust heat heat exchanger is compared with the temperature set value, and the difference signal is added or subtracted to the signal given to the controller, and the chilled water is supplied to the heat receiving side of the exhaust heat heat exchanger. Adjust the flow rate and
and compares the hot water supply temperature detection value detected by the second hot water supply temperature detector with the temperature set value, provides their deviation signal to the controller to apply the bias signal in advance, and and a preceding control device that is applied to the second hot water flow rate adjustment valve and the cold water flow rate adjustment valve to adjust the valve opening degree.