JP2542165B2 - Optimal temperature controller for cogeneration system - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to a optimum temperature control device for co-generation systems.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram of a conventional cogeneration system. In the figure, 1 is a generator that generates electric power, and 2 is an engine that drives the generator 1. The heat source water supplied from the pipe 16 is heated by the amount of heat generated in the engine 2. This heat source water is sent by the pipe 13 to the exhaust gas boiler 3 that uses the exhaust gas generated from the engine 2 and is heated. The heated heat source water is pump 1
1 to the hot water utilization equipment 4 that uses the heat source water to release heat, and the heat source water is cooled and flows to the radiator 6 through the pipe 15. It is the three-way valve 5 that adjusts the amount of heat used by the hot water utilization facility 4. Further, in order to release the amount of heat that cannot be absorbed by the hot water utilization facility 4 to the outside, a radiator 6 and a three-way valve 7 for adjusting the amount of heat released are provided. The heat source water cooled by the radiator 6 passes through the pipe 16 and flows into the engine 2. The valve opening of the three-way valve 7 is controlled by the controller 8. In this system, the temperature sensor 9 detects the inlet temperature of the engine 2, inputs the measured value as a feedback value to the controller 8, and calculates the temperature difference from the engine inlet temperature set value in the controller 8 by PID calculation. The valve opening degree is calculated, and the three-way valve 7 is controlled so that the inlet temperature of the engine 2 matches the set value.

[0003]

FIG. 7 shows the temperature of each part when the valve opening of the three-way valve 5 is opened to the bypass side in order to reduce the amount of heat used by the hot water utilization facility 4 when the amount of heat generated by the engine is constant. It is the figure which showed change.

As shown in the figure, the response of the valve opening of the three-way valve 7 connected to the radiator 6 is slow, the required amount of heat radiation does not increase with the temperature rise, and the engine outlet as shown by arrow B is shown. The temperature has risen. The response of the valve opening degree of the three-way valve 7 is slow because the gain of the feedback control system of the controller 8 is limited by the response of the temperature sensor 9.
Due to its structure, the temperature sensor 9 generally has a response time constant of about 180 seconds, and the feedback system cannot further increase the response of the controller 8. In this system, since the heat source water is used as engine cooling water, if the engine outlet temperature of the heat source water rises, there is a danger that a vapor phenomenon partially occurs in the engine, which causes engine failure.

The present invention has been made in view of the above circumstances, and its purpose is to control a three-way valve connected to a radiator optimally to keep the engine outlet temperature constant and improve system performance. Optimal temperature control of the generation system
To provide a device .

[0006]

In order to achieve the above object, the present invention heats heat source water flowing through a system with heat generated from an engine for driving a generator, and uses the heated heat source water. Utilization equipment, a first three-way valve for adjusting the amount of heat used by the hot water utilization equipment, a radiator for releasing the amount of heat that could not be used by the hot water utilization equipment to the outside, and the amount of heat released by the radiator a second three-way valve which, a temperature sensor for detecting an engine inlet temperature of the heat source water, corresponding to the temperature difference from the temperature difference between the set value of the detected engine inlet temperature and the engine inlet temperature by the temperature sensor An optimum temperature control device for a co-generation system comprising a controller that obtains the valve opening of the second three-way valve and adjusts the second three-way valve so that the engine inlet temperature becomes a set value, And line function that outputs the absorbed heat quantity corresponding to the valve opening degree from the serial first 3-way valve opening degree, the absorption heat output rated heat generation amount of the engine that are set in advance from the polygonal line function A line function for calculating the amount of heat to be released by the radiator from the heat amount difference and outputting the valve opening degree according to the heat amount is provided, and the valve opening value of this line function is fed forward to the output control signal of the controller. It is characterized in that the opening degree of the second three-way valve is adjusted by adding as a signal.

[0007]

By incorporating a control for feeding forward the heat quantity difference between the engine and the absorbed heat quantity in the hot water utilization equipment into the control system for feeding back the measured value of the radiator outlet temperature like the above-mentioned control device , The response speed of valve control becomes faster, the heat source water inlet temperature of the engine can be kept constant, and the engine outlet temperature can also be kept constant if the engine generated heat amount is kept constant.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. 1 is a system control block diagram of an embodiment of the present invention, in which the same reference numerals as those in FIG. 6 indicate the same components.

In the figure, the engine inlet temperature is detected by the temperature sensor 9, and the temperature difference from the engine inlet temperature set value of the controller 8 is PID-calculated to obtain the required valve opening. 3 to match the set value
The one-way valve 7 is controlled. 12 is the rated heat generation amount of the engine 2. A polygonal line function 18 representing the characteristic of the absorbed heat quantity of the heat utilization system versus the valve opening degree from the valve opening degree of the three-way valve 5 for the hot water utilization facility 4 has the characteristics shown in FIG. The amount of absorbed heat is calculated using this polygonal line function 18, and the amount of heat to be released by the radiator 6 is calculated from the difference between the rated amount of heat generated by the engine 2 and the amount of absorbed heat. Further, the polygonal line function 19 in FIG. 3 has a heat release amount-valve opening degree characteristic. Using this polygonal line function 19, the valve opening of the three-way valve 7 of the radiator 6 is determined, and this valve opening signal is added to the output signal of the controller 8 as a feedforward signal to obtain a feedback signal and a feedforward signal. The optimum valve opening of the three-way valve 7 is determined from the sum of the above.

Next, the operation of this embodiment will be described.
FIG. 4 is a diagram showing the characteristics of the control device of the present invention under the same conditions as in FIG. The system according to the present embodiment is generally connected to the system, and since the load on the engine is almost 100%, there is no output fluctuation and it can be considered that the amount of heat generated by the engine is constant. When attempting to stop the hot water utilization equipment 4 from the state where the hot water utilization equipment 4 is fully operating, the three-way valve 5 of the hot water utilization equipment 4 is closed. At this time, the hot water utilization equipment 4 does not absorb the heat quantity of the heat source water, and the surplus heat quantity generated at this time is released to the outside by the radiator 6.

First, the amount of heat released from the radiator 6 is determined,
The required valve opening is given to the three-way valve 7. For this purpose, the inlet temperature of the engine 2 is used as a feedback signal, and the temperature difference from the set value is PID-calculated inside the controller 8 to obtain the valve opening. Feed-forward control is incorporated into this feedback control to output the optimum valve opening signal of the radiator 6. As this feedforward value, the engine 2
The amount of heat generated from the heat sink is set to a constant value, and the difference in the amount of heat between this amount of heat and the amount of heat absorbed by the line function 18 representing the valve opening absorption heat amount characteristic of the hot water utilization equipment 4 is taken as the amount of heat released by the radiator 6 A value obtained by calculating the valve opening degree is used by using a polygonal line function 19 indicating the heat release amount-valve opening degree characteristic of the heat radiation system from the heat quantity. As a result, the valve opening of the radiator 6 follows the valve opening of the hot water utilization equipment 4, and the amount of heat that cannot be absorbed by the hot water utilization equipment 4 can be quickly released. Therefore, the inlet temperature of the engine 2 can be kept constant, and the outlet temperature of the engine can be kept constant as indicated by arrow A in FIG.

In the control according to this embodiment, normally, the valve opening of the three-way valve 7 is optimally determined by the feedforward control, and the engine inlet temperature is kept constant. The correction is applied by the feedback control only when the engine inlet temperature changes due to the error of the feedforward polygonal line functions 18 and 19 or the disturbance due to the change of the engine power generation amount. The valve opening of the heat radiation system is generally detected by a potentiometer, and there is no detection delay. Therefore, there is no delay in the feedforward control, and a quick response control is possible.

As described above, in this embodiment, the engine inlet temperature is controlled to be constant by setting the three-way valve 7 of the radiator 6 so as to incorporate the feedforward control,
Considering that the amount of heat generated by the engine is constant, the engine outlet temperature can also be maintained at a constant level, improving system reliability and the efficiency of hot water utilization equipment.

FIG. 5 is a system control block diagram of another embodiment of the present invention. The present embodiment is different from the above embodiment in that the arithmetic unit 17 is provided, and the other points are the same, so the same components are designated by the same reference numerals and the description thereof is omitted. The arithmetic unit 17 calculates the amount of heat generated by the engine 2 by multiplying the temperature difference detected by the temperature sensors 9 and 20 by the flow rate. In the present embodiment, the rated amount of heat generated is used as the amount of heat generated by the engine 2. However, when the load of the generator 1 changes, the engine calculated from the temperature difference between the inlet temperature and the outlet temperature of the engine 2 and the flow rate. Even if the feedforward control is performed using the amount of heat generated, the inlet temperature of the engine 2 can be constantly controlled to be constant.

In the above embodiments, the type having the exhaust gas boiler has been described, but the effect of the present invention can be similarly exerted even in a configuration in which the heat source water from the engine is directly supplied to the hot water utilization facility without the exhaust gas boiler .

[0016]

As described above, according to the present invention,
Since the feed-forward control system is incorporated in the feedback control system, the response speed becomes faster and optimum temperature control can be performed. That is, the engine inlet temperature can be controlled to be constant, and the reliability of the cogeneration system is improved.

[Brief description of drawings]

FIG. 1 Control of the co-generation system of the present invention
The block diagram of an apparatus .

FIG. 2 is a characteristic diagram of a polygonal line function 18 applied to FIG.

FIG. 3 is a characteristic diagram of a polygonal line function 19 applied to FIG.

FIG. 4 is a characteristic diagram applied to the control system of the present invention.

FIG. 5 is a configuration diagram of another embodiment of the present invention.

FIG. 6 is a block diagram of a conventional co-generation system control method.

FIG. 7 is a characteristic diagram of a conventional technique.

[Explanation of symbols]

1 ... Generator, 2 ... Engine, 3 ... Exhaust gas boiler, 4 ... Hot water utilization equipment, 5 ... 3-way valve, 6 ... Radiator, 7 ... 3-way valve, 8
... Controller, 9, 20 ... Temperature sensor, 11 ... Pump, 12 ... Heat generated from engine, 13, 14, 1
5, 16 ... Piping, 17 ... Calculation device for calculating engine heat quantity, 18 ... Line function for obtaining heat quantity from valve opening of heat radiation system, 19 ... Line function for finding valve opening degree from heat quantity.

Continued Front Page (72) Hidekazu Hayashi, 3-2 95 Chiyosaki, Nishi-ku, Osaka City, Osaka Prefecture Osaka Gas Co., Ltd.

Claims (2)

(57) [Claims] 1. A hot water utilization facility that heats heat source water flowing through a system with heat generated from an engine that drives a generator, and uses the heated heat source water; and a utilization heat quantity of the hot water utilization facility. A three-way valve of No. 1 and a radiator that releases the amount of heat that could not be used in the hot water utilization facility to the outside.
A second three-way valve that adjusts the amount of heat released by the radiator, a temperature sensor that detects the engine inlet temperature of the heat source water, and an engine inlet temperature detected by the temperature sensor and a set value of the engine inlet temperature. From the difference, the valve opening of the second three-way valve corresponding to the temperature difference is obtained, and a controller that adjusts the second three-way valve so that the engine inlet temperature becomes a set value In the optimum temperature control device, a polygonal line function that outputs the absorbed heat amount according to the valve opening amount of the first three-way valve, and a preset rated heat generation amount of the engine and the polygonal line function that outputs a polygonal line function formed, wherein the valve opening value of the polygonal line function controller is the amount of heat to be released by the radiator from the heat differential between the heat absorption was calculated, and outputs a valve opening corresponding to the amount of heat Optimal temperature control device for co-generation systems and adjusting the second three-way valve opening by adding a feed-forward signal to the output control signal. 2. The optimum temperature control device for a co-generation system according to claim 1, wherein a temperature sensor for the rated heat generation amount of the engine is provided at the engine outlet side, and the temperature detected by this temperature sensor and the engine inlet side are provided. An optimum temperature control device for a co-generation system, characterized in that the temperature difference from the temperature detected by the temperature sensor provided is multiplied by the flow rate to calculate.