JP2940267B2 - Cogeneration system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact and high-performance cogeneration system capable of effectively utilizing surplus power.

[0002]

2. Description of the Related Art In recent years, cogeneration systems (cogeneration systems) use electric power (generation output R) generated by a generator at stores and homes, as well as heat sources for cooling water and exhaust gas associated with driving of an engine and a generator. It is becoming popular as a relatively small hot water supply system that makes effective use of water. As shown in FIG. 5, the cogeneration system includes a generator 5 driven by the engine 4, a power control device 50 for controlling the power output by the generator 5, and an electric power control device 50. Utility 53 electrically connected
And The power control device 50 has a central processing unit (CPU) 51 and an engine control circuit 52.

Further, the cogeneration system includes an engine cooling water circulation circuit 7 for circulating cooling water of the engine 4 by a cooling water pump 73, and a hot water heat exchanger 7 provided in this circuit.
1 and an exhaust gas heat exchanger 74. The cogeneration system has a hot water storage tank 91 for storing the hot water heated by the hot water heat exchanger 71, and a hot water circulation circuit 8 provided between the hot water storage tank 91 and the hot water heat exchanger 71. .

The hot water storage tank 91 has a water pressure reducing valve 92. The hot water circulation circuit 8 is
A hot water circulation pump 81, the hot water heat exchanger 71, a mixing valve 82, a solenoid valve 83 for switching a hot water circuit, and a faucet 84.
, A hot water flow switch 85 and a hot water sensor 86. In the above cogeneration system, as shown in FIGS. 5 and 6, a generator 5 driven by an engine 4 generates electricity. Then, about 30% of the primary energy generated from the fuel used for the engine 4 is used as the power generation output R in the electric utilities 53 such as factories, homes, stores and the like.

[0005] The cooling water, which has been heated by cooling the engine 4, is used to heat the hot water by a hot water heat exchanger 71 provided in the engine cooling water circulation circuit 7 as shown in FIG. 6. . For this, about 40% of the primary energy is used. FIG.
As shown in FIG. 5, about 20% of the primary energy amount is effectively used as a heat source for hot water supply by the heat of the exhaust gas 630 generated from the engine 4. About 10% of the primary energy is radiated as unused energy.

The generator 5 has a four-pole motor, and its rotation speed is about 1500 to 1800 rpm (rotations /
) Is controlled by the engine control circuit 52 in the power control device 50. As a result, 50
Alternatively, a current having a frequency of 60 Hz is generated, and is used as a lighting or power source for the electric utility 53 in factories, stores, homes, and the like. The heat of the exhaust gas 630 is recovered by the exhaust gas heat exchanger 74 and is effectively used for hot water supply. However, hot water is not required, and the hot water heat exchanger 71 is not required.
In the case where the cooling of the engine cooling water is insufficient, the three-way valve 72 is operated, and the cooling water and the exhaust gas 63 of the engine 4 are operated.
Heat supplied by the engine cooling water circulation circuit 7
, The heat is radiated to the outside by the radiator 61 and the blower 62 or the exhaust gas treatment device 63 (see FIGS. 5 and 6).

On the other hand, the hot water is stored in the hot water storage tank 9.
Stored in one. The temperature T of the hot water in the hot water storage tank 91 is detected by the hot water sensor 86. When the hot water is below the set temperature T _w is hot water as the arrow by the hot water circulating pump 81, the hot water circulation circuit 8
It is circulated inside. Then, it is heated by the hot water heat exchanger 71. Next, the heated hot water is stored in the hot water storage tank 91 again. Also, the hot water is thermometry by the hot water sensor 86, when it reaches to a set temperature T _w,
The hot water circulation pump 81 stops.

By the way, when using hot water, the water pressure reducing valve 92 is operated. As a result, the circuit from the water pressure reducing valve 92 to the faucet 84 is maintained at an appropriate pressure (for example, about 0.9 kg / cm). In this state, by opening the faucet 84 can be used hot water of a predetermined temperature T _w.

[0009]

However, as shown in FIG. 6, in the above cogeneration system, the thermoelectric ratio (Q / R), which is the ratio between the power generation output R and the hot water supply output Q, is constant (60/3).
0). On the other hand, the generated electric power constantly fluctuates due to the demand in the electric utility 53. Therefore, when the amount of electric power for hot water supply becomes small, the hot water supply output Q
Of the hot water supply will be reduced accordingly. That is, when the amount of electric power is reduced, the output of the engine 4 is reduced, so that the temperature of the engine coolant decreases. Therefore, the amount of heat supplied to the hot water heat exchanger 71 decreases. Therefore, when the power generation output R is large, it is necessary to increase the hot water supply output Q as much as possible to obtain a large amount of hot water. Therefore, a relatively large hot water storage tank 91 must be prepared and hot water must be stored therein. Therefore, in this method, the cogeneration system must necessarily be increased in size, and a large installation space is required.

Therefore, in order to solve the above problem, it has been proposed to arrange a booster heater device downstream of the hot water circulation circuit for the purpose of supplementing the shortage of the power generation output R (see, for example, Japanese Unexamined Patent Publication No. Hei. -29642). However, in the above proposal, the booster heater device is constituted by a nonconductive cylinder made of a ceramic material or a plastic material.

[0011] Therefore, the above-mentioned booster heater device must inevitably consume a large amount of heat, and must use a high-voltage (400 to 3000 Volt) power supply as shown in the above-mentioned publication. Therefore, in the above cogeneration system, a normal voltage (for example, 100 to 200 Volts) is used.
Power cannot be used. Therefore, for home use,
The above-mentioned conventional technology cannot be applied to a relatively small cogeneration system used for business use. Therefore, the above prior art is not practical. Further, no control of the thermoelectric ratio for solving the shortage of hot water supply is performed. The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide a compact and high-performance cogeneration system that can effectively use surplus power.

[0012]

The present invention comprises a generator driven by an engine, a power control device for controlling power output by the generator, and an electric utility connected to the power control device. An engine coolant circulation circuit for cooling the engine coolant, a hot water heat exchanger provided in the engine coolant circulation circuit, a hot water storage tank, and a hot water storage tank and a hot water heat exchanger. In the cogeneration system comprising the hot water circulating circuit provided in the above, an electric heater is interposed in the hot water circulating circuit, and the electric power control device has an electric power for detecting surplus electric power between the electric power utility and the electric utility. A heater output controller for supplying a surplus power detected by the power detector to the electric heater is provided between the electric heater and the detector. In cogeneration apparatus characterized and.

The most remarkable point in the present invention is that an electric heater is interposed in the hot water circulation circuit, a power detector is provided between the electric power control device and the electric utility, and a power detector is provided between the electric power utility and the electric heater. Is provided with a heater output controller in order to effectively use the surplus electric power P to heat the hot water. As the hot water heat exchanger, for example, a double-pipe or multi-plate heat exchanger is used.

The power detector is for constantly detecting a power value (power output R) generated by the generator and detecting surplus power P not used in the electric utility.

The heater output controller is for supplying surplus power P detected by the power detector to the electric heater. In addition, as the electric heater,
For example, there are an electric heater with a built-in hot water circuit, a tube surface contact type electric heater, and the like.

In the electric heater, the heater output controller calculates a heater output value H based on a power consumption value W detected by the power detector and a value of a water temperature T detected by a water temperature sensor, for example. The heater is controlled. The power control device has a power detector so as to always detect the electric utility power and the surplus power P in an engine control circuit, for example. The surplus power P
Is surplus power not consumed by the electric utility (see FIG. 3). Others are the same as the conventional one.

[0017]

In the present invention, a power detector for detecting surplus power P is provided between the power control device and the electric utility. Therefore, the output power R output by the generator can always be detected.
Here, the power consumption value W is calculated from the detected output power R. Further, a heater output controller for heating hot water is provided between the power detector and the electric heater. Therefore, the surplus power P detected by the power detector is
It can be supplied to an electric heater.

In the hot water circulation circuit, an electric heater is interposed between the hot water heat exchanger and the hot water storage tank. Therefore, the electric heater can effectively use the surplus power P supplied by the heater output controller, and improve the capability of the hot water supply output Q. That is, the heater output value H that is effectively used for the electric heater is determined from the required maximum generated power G output by the generator and the power consumption value W detected by the power detector. The power output value H is the surplus power P.

Therefore, the thermoelectric ratio (Q / R), which is the ratio between the power generation output R and the hot water supply output Q, can always be controlled to an optimum value. That is, the thermoelectric ratio is controlled and determined by constantly detecting the surplus power P and the fluctuating power consumption value W. In addition, the power consumption value W and the heater output value H constantly fluctuating in the electric utility are controlled and determined, and the maximum power generation amount G required by the power generator is controlled and determined all the time.
The value of the power generated by the generator is determined. Thereby, the required maximum power generation amount G (G ≧ W + H) can be output by the generator.

Therefore, in the combined heat and power supply apparatus of the present invention, the heater output value H is set so as to always obtain a large hot water supply capacity.
Can be determined. Therefore, the present cogeneration system can always exhibit the maximum hot water supply capacity (thermoelectric ratio). On the other hand, due to the effect of improving the hot water supply capacity, the hot water storage tank can be made smaller and higher in performance than the conventional capacity of the hot water storage tank.

Further, in the present cogeneration system, a normal voltage (100 V to 20 V) is used instead of the conventional booster heater device which must use a high voltage as an auxiliary heat source.
0V) can be used. Therefore, a relatively small heat and power supply device can be obtained. As described above, according to the present invention, it is possible to provide a compact and high-performance cogeneration system that can effectively use surplus power.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cogeneration system according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the cogeneration system of the present embodiment includes a generator 5 driven by an engine 4, a power control device 50 for controlling the power output by the generator 5, and a power control device 50. And an electric utility 53. As shown in the figure, the cogeneration system includes an engine cooling water circulation circuit 7 for circulating cooling water of the engine 4, a hot water heat exchanger 71 provided in the engine cooling water circulation circuit 7, and a hot water storage device. It comprises a tank 91 and a hot water circulation circuit 8 provided between the hot water storage tank 91 and the hot water heat exchanger 71.

As shown in FIG. 1, the electric heater 1 is interposed in the hot water circulation circuit 8, and the electric utility 53 and the CPU 5 are installed in the power control device 50.
1 and a power detector 2 for detecting surplus power P. As shown in the figure, a heater output controller 3 for supplying surplus power P detected by the power detector 2 to the electric heater 1 is provided between the electric heater 1 and the power detector 2. It is provided. The electric heater 1 includes:
An electric heater with a built-in hot water circuit is used. Further, the electric heater 1 has a power consumption value W detected by the power detector 2.
And the value of the water temperature T detected by the water temperature sensor 86,
The heater is controlled by the calculated heater output value H. That is, the electric heater 1 is controlled by the heater output value H to determine whether or not the warm water should always be heated.

The power detector 2 is for constantly detecting the power (power generation output R) generated by the generator 5 and detecting the surplus power P. In addition, power detector 2
A current / voltage detection type RMS wattmeter is used.
The heater output controller 3 supplies the surplus power P detected by the power detector 2 to the electric heater 1,
It is for control. In addition, the heater output controller 3
Is electrically connected to the CPU 51, and the CPU 51
Is controlled by As the hot water heat exchanger 71, a heat exchanger for exchanging heat of the cooling water of the engine 4 is used.

The power control device 50 has the power detector 2 so as to constantly detect the power consumption value W for the electric utility 53 and the surplus power P.
As the electric utility 53, for example, home use,
There are lighting fixtures, home appliances, and office appliances used in general homes, stores, and the like for business use. As the hot water storage tank 91, a relatively small-sized hot water tank having a smaller capacity than the hot water storage tank 9 in the conventional cogeneration system is used. Thus, the entire cogeneration system can be made compact, the installation area of the hot water storage tank 91 can be reduced (space saving), and the arrangement (installation) can be improved.

As shown in FIG. 3, the surplus power P is also a value (GW) obtained by subtracting the power consumption value W consumed by the electric utility 53 from the maximum power generation amount G generated from the generator 5. . Thus, the electric heater 1 uses the surplus electric power P, which constantly fluctuates, to the maximum effective use to heat the hot water. The electric heater 1 is always controlled by the heater output controller 3 for hot water supply. Others are the same as the conventional one.

Next, the function and effect will be described. First, the basic flow of the cogeneration system according to this example is shown in FIG.
This will be described with reference to the flowchart of FIG. First, the hot water set temperature _Tw (for example, 65 ° C.) is set by the hot water supply user. In the figure, in step S101, the heater output controller 3 operates (starts) simultaneously with the start of driving of the generator 5. Next, in S102, the power detector 2 reads the power consumption value W.

Next, at S103, the heater output value H is
It is calculated as a value (GW) obtained by subtracting the power consumption value W from the required maximum power generation amount G of the generator 5.
If the heater output value H is larger than (GW) (No), the process proceeds to S104. Then, in S104, the electric heater 1 heats the hot water by effectively utilizing the surplus electric power P. Then, in S104, when the heater output value is H = GW, the process proceeds to the next S106.

On the other hand, if the heater output value H is smaller than (GW) (Yes) in S104, the process proceeds to S10.
The process proceeds from S3 to S106. In addition, the surplus power P is controlled and determined according to the power consumption value W, and the warm water is heated by effectively utilizing the surplus power P. Then, in S106, the water temperature T is read by the water temperature sensor 86. In S107, when the water temperature T of the hot water is higher than the maximum value T _WH (for example, 67 ° C.) of the set temperature T _W (when Yes), the process proceeds to S108. next,
In S108, the heater output value H is reduced by the control unit h by the heater output controller 3, and the process returns to S106.

On the other hand, in the S107, the maximum value T _WH of the water temperature T is the set temperature T _w (e.g., 67 ° C.) (when No) is lower than, the process proceeds to S109. And S10
In 9, when the minimum value of the hot water set temperature T _W is lower than T _WL, the process proceeds to S110. In S110, the process returns to S106 in which the heater output H is increased by the control unit h. When the state of T _WL <T <T _WH continues, the above S
Return to 102. Then, the hot water is heated again by the electric heater 1.

The above flow will be described below with reference to FIGS.
This will be specifically described with reference to FIG. In this example, a central processing unit (CP) electrically connected to the power control device 50 is used.
A power detector 2 for detecting the surplus power P is provided between the U) 51 and the electric utility 53. Therefore, the power generation output R output by the generator 5 can always be detected. A heater output controller 3 is provided between the electric heater 1 and the power detector 2.

Therefore, the surplus power P detected by the power detector 2 can be supplied to the electric heater 1.
Further, the temperature T detected by the power detector 2 power consumption value W and the water temperature sensor 86 is detected by whether or not to warm to the set temperature T _w is controlled determined. That is, as shown in FIG. 3, when the power consumption value W is detected by the power detector 2, the heater output controller 3 controls the electric heater 1 so that the heater output value H is calculated.
Is controlled by the heater. Here, the heater control refers to control for judging whether or not the hot water should be heated by the electric heater 1 by effectively utilizing the surplus power P.

FIG. 3 shows the relationship between the heater output value H (vertical axis) and the power consumption value W (horizontal axis). Here, when the power consumption value W is detected by the power detector 2, it is determined whether or not the electric heater 1 should heat the hot water to the set temperature T _W. Next, the heater output value H
Is determined. On the other hand, the set temperature T _W is a value determined by the hot water user according to the purpose of use. For example, when using hot water for the tub, T _W are set to 65 ° C.. Temporarily requires a large amount of hot water supply amount, it may not be controlled to the set temperature T _W. In this case, the mixing valve 82 operates as follows. That is, as shown in FIG. 1, the mixing valve 82 disposed between the hot water heat exchanger 71 and the faucet 84 operates in the following two modes.

Here, first, when the temperature of the hot water is lower than the set temperature T _W , the wax thermostat provided in the mixing valve 82 operates. Thus, the hot water issued from the faucet 84 to the outside, are mixed hot water in the hot water storage tank 91, control is performed so as to be constantly set temperature T _W. The above-described series of controls is performed by detecting the opening and closing of the faucet 84 by the flow detection sensor 85. As described above, the control of the electric heater 1 by the heater output controller 3 is such that the set temperature T _{W of the} hot water is maintained at all times.
The electric heater 1 and the heater output controller 3 operate.

On the other hand, the hot water heat exchanger 71 supplies the cooling water circulating in the engine cooling water circulation circuit 7 with the three-way valve 7.
It is activated when it is sent to the hot water heat exchanger 71 by the opening of 2. These controls are all performed by the CPU 51. Then, when it becomes necessary to heat the hot water, the hot water heat exchanger 71 is controlled to heat the hot water preferentially.

[0036] At this time, the three-way valve 72 senses the temperature of the hot water, when the hot water is heated to a set temperature T _W, the cooling water flows into the radiator 61 is an auxiliary heat dissipating means. This is also controlled by the CPU 51. As mentioned above,
In this example, as shown in FIG. 3, the heater output value H is determined while controlling the required maximum power generation amount G and the power consumption value W detected by the power detector 2. Thus, the power heater is controlled by the heater output controller 3 and the CPU 51 so that the thermoelectric ratio always becomes the optimum value.

For this reason, the heater output controller 3 detects the constantly fluctuating power consumption value W in the electric utility 53 while simultaneously detecting the required maximum power generation amount G.
To calculate the heater output value H. This gives
The heater output controller 3 and the CPU 51 control and determine which of the hot water heat exchanger 71 and the electric heater 1 should be operated. Therefore, as shown in FIG. 4, the heater output value H is controlled and determined with respect to the power consumption value W, and the appropriate thermoelectric ratio is controlled so as to always obtain the maximum hot water supply capacity (the upper dashed line in FIG. 4). Hot water supply capacity Q). Here, FIG. 4 is a graph showing a relationship between hot water supply capacity Q and power consumption value W.

That is, according to the present embodiment, when the power consumption value W is small, the surplus power P is effectively used and is used for hot water supply, thereby controlling the thermoelectric ratio (Q / R). The power output by the generator 5 can be effectively used to the maximum. Further, as described above, since the hot water supply capacity can be improved, a small-sized hot water storage tank having a smaller capacity than the conventional hot water storage tank 91 can be used. Therefore, the installation and workability of the hot water storage tank 91 are improved. Further, according to the present embodiment, since the electric heater 1 is used instead of the booster heater device as in the conventional example, a normal voltage can be used and a compact cogeneration system can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a cogeneration system according to an embodiment.

FIG. 2 is a flowchart of the cogeneration system according to the embodiment;

FIG. 3 is a graph showing a relationship between a heater output value H and a power consumption value W in the embodiment.

FIG. 4 is a graph showing a relationship between a hot water supply output Q and a power consumption value W in the embodiment.

FIG. 5 is a circuit diagram of a conventional cogeneration system.

FIG. 6 is an explanatory diagram showing a utilization rate of primary generated energy of fuel used for an engine in a conventional cogeneration system.

[Explanation of symbols]

 1. . . 1. electric heater, . . Power detector, 3. . . 3. heater output controller; . . Engine, 5. . . Generator, 50. . . Power control device, 53. . . 6. Electric utilities, . . Engine cooling water circulation circuit, 71. . . 7. hot water heat exchanger, . . Hot water circulation circuit, 91. . . Hot water storage tank,

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F24H 1/18 F01K 17/02 F02G 5/04 H02J 3/38

Claims (1)

(57) [Claims] A generator driven by an engine;
An electric power control device for controlling electric power output by the generator, an electric utility connected to the electric power control device, and an engine cooling water circulation circuit for cooling engine cooling water; In the combined heat and power unit comprising a hot water heat exchanger provided in an engine cooling water circulation circuit, a hot water storage tank, and a hot water circulation circuit provided between the hot water storage tank and the hot water heat exchanger, the hot water circulation circuit An electric heater is interposed therein, and the power control device is provided with a power detector for detecting surplus power between the electric utility and the electric utility, and is detected by the power detector between the electric utility and the electric heater. And a heater output controller for supplying surplus power to the electric heater.