JP4783308B2 - Power generation system - Google Patents

Description

  The present invention relates to a power generation system configured to operate a generator by the output of a gas engine.

  In a power generation system configured to operate a gas engine using two types of fuel, a main fuel gas such as city gas and a secondary fuel gas such as biogas, and operate the generator by the output of the gas engine, The system method is adopted. For example, according to the calorific value of the auxiliary fuel gas, the supply flow rate of the mixture of the main fuel gas and combustion air is adjusted to mix and burn two types of fuel, the main fuel gas and the auxiliary fuel There is a system that uses a fuel mixed with gas and performs combustion while controlling the air ratio of combustion air.

  For example, Patent Document 1 discloses a dual fuel diesel engine configured to operate by supplying light oil as a main fuel and a mixed gas of air and biogas to a diesel engine. In this diesel engine, the opening of a flow rate control valve that sets the biogas supply flow rate is fixed, and the light oil supply flow rate is controlled so that the rotational speed of the diesel engine is constant.

  Further, for example, in Patent Document 2, a gas configured to supply a gas engine with a mixture of an auxiliary fuel gas such as biogas and combustion air and a main fuel gas such as city gas to perform operation. An engine is disclosed. In this gas engine, by utilizing the negative pressure generated when combustion air passes through the mixer, the auxiliary fuel gas is sucked into the mixer to generate these air-fuel mixtures. Further, the air ratio is controlled by adjusting the opening of a valve for adjusting the supply flow rate of the main fuel gas based on the output fluctuation of the oxygen sensor or NOx sensor provided in the exhaust system of the gas engine. In the mixer, after the mixture of combustion air and auxiliary fuel gas and the main fuel gas are mixed, the supply flow rate of the two fuel mixture to the gas engine is adjusted by the throttle valve, and the gas is The engine speed or load is controlled.

  However, in patent document 1, the supply flow rate of the biogas by the flow control valve is fixed, and the biogas is pushed into the air flow and mixed. Therefore, the ratio of the biogas supply flow rate to the total supply flow rate of light oil and biogas to the diesel engine cannot be kept below the predetermined predetermined ratio. Therefore, in cited document 1, even when the load of the generator is low, an excessive amount of biogas, which is the same amount as when the load is almost 100%, is supplied to the diesel engine, and the control of the diesel engine becomes unstable. There is a risk. In Cited Document 1, since the biogas supply flow rate to the diesel engine is greatly influenced by the original pressure of the supply source (tank or the like), the control of the diesel engine may become more unstable.

  Further, in Patent Document 2, a valve for adjusting the supply flow rate of the main fuel gas and a throttle valve are mixed, and these controls may affect the control of the gas engine, which may become unstable. Further, in the cited document 2, a valve for adjusting the supply flow rate of the main fuel gas is required in addition to the throttle valve, so that the throttle valve and the control means for controlling the valve become complicated.

JP 2002-309997 A JP 2005-30302 A

  The present invention has been made in view of such conventional problems, and the ratio of the amount of heat supplied to the gas engine of the auxiliary fuel gas is kept below a predetermined ratio at which stable operation can always be performed without performing special control. It is intended to provide a power generation system that can.

A first invention is a gas engine having a plurality of cylinders;
A generator operated by the output of the gas engine;
An auxiliary fuel pipe to which an auxiliary fuel gas such as biogas is supplied;
A pressure regulator provided in the auxiliary fuel pipe;
An air pipe to which combustion air is supplied;
In response to the suction force generated when the combustion air flowing in from the air pipe passes through the venturi, the auxiliary fuel gas after the pressure is set by the pressure regulator flows in from the auxiliary fuel pipe. A first mixer that mixes the secondary fuel gas with air to produce a first air-fuel mixture;
A main fuel pipe to which main fuel gas is supplied;
A throttle valve provided in the main fuel pipe;
A second mixer that mixes the first fuel mixture flowing in from the first mixer with the main fuel gas after flow adjustment by the throttle valve from the main fuel pipe to create a second gas mixture;
Using the exhaust gas from the gas engine, compressing the second gas mixture flowing in from the second mixer, and creating a compressed gas mixture;
An intake manifold that supplies the compressed air-fuel mixture flowing from the supercharger in a branched manner to the plurality of cylinders;
Control means for adjusting the opening of the throttle valve so that the power generation output of the generator becomes a target output,
By adjusting the opening degree of the throttle valve in accordance with the target output of the generator by the control means, the amount of heat required to produce the target output that is insufficient with only the auxiliary fuel gas is determined by the main fuel gas. In addition, the ratio of the supply flow rate of the sub fuel gas to the total supply flow rate of the main fuel gas and the sub fuel gas to the gas engine is configured to be kept below the initially set ratio ,
The control means increases the opening of the throttle valve so that the power generation output of the generator becomes a target output when the amount of heat of the auxiliary fuel gas decreases, and the main fuel gas to the gas engine is increased. On the other hand, when the amount of heat of the auxiliary fuel gas is increased, the opening of the throttle valve is decreased so that the power generation output of the generator becomes the target output, and the gas engine is supplied to the gas engine. The power generation system is configured to reduce the supply flow rate of the main fuel gas .

The power generation system of the present invention can keep the ratio of the amount of heat supplied from the auxiliary fuel gas to the gas engine below a predetermined ratio at which stable operation can always be performed without performing special control.
Specifically, in the power generation system of the present invention, the amount of inflow of the auxiliary fuel gas to the first mixer is adjusted by a pressure regulator provided in the auxiliary fuel pipe, and the main fuel gas and the auxiliary fuel to the gas engine are adjusted. The ratio of the supply flow rate of the auxiliary fuel gas to the total supply flow rate with gas is initially set within a range that does not exceed a predetermined ratio at which stable operation can be performed in the gas engine.

When this initial setting is performed, assuming that the amount of heat of the auxiliary fuel gas is maximized, the ratio of the amount of heat supplied to the auxiliary fuel gas to the total amount of heat supplied to the gas engine and the amount of auxiliary fuel gas is the gas engine. The ratio of the supply flow rate of the auxiliary fuel gas is set within a range not exceeding a predetermined ratio at which stable operation is possible.
When performing the initial setting, the flow rate can be finely adjusted by adjusting the set pressure with a pressure regulator and adjusting the opening of a manual valve or the like provided in the auxiliary fuel pipe.

  When the power generation system according to the present invention is operated, a first mixture of combustion air and auxiliary fuel gas is created in the first mixer, and the first mixture and main fuel gas are mixed in the second mixer. A second mixture is created. Next, in the supercharger, the second air-fuel mixture is compressed to produce a compressed air-fuel mixture, and this compressed air-fuel mixture is supplied to a plurality of cylinders in the gas engine via the intake manifold. Then, the generator can be operated at the target output by adjusting the opening of the throttle valve by the control means and adjusting the supply flow rate of the main fuel gas to the gas engine.

Further, in the power generation system of the present invention, when the output of the gas engine is increased, the opening of the throttle valve is increased by a command from the control means, and the supply flow rate of the main fuel gas to the gas engine is increased. At this time, the rotational speed of the supercharger increases as the temperature of the exhaust gas from the gas engine increases. Thereby, the inflow amount of the second air-fuel mixture to the supercharger, the inflow amount of the first air-fuel mixture to the second mixer, and the inflow amount of the combustion air to the first mixer are increased, respectively, and the venturi of the first mixer is increased. As the suction force increases, the amount of inflow of the auxiliary fuel gas to the first mixer increases.
Thus, when the supply flow rate of the main fuel gas to the gas engine increases, the supply flow rates of the combustion air and the auxiliary fuel gas to the gas engine can also be increased.

On the other hand, when the output of the gas engine is reduced, the opening of the throttle valve is reduced by a command from the control means, and the supply flow rate of the main fuel gas to the gas engine is reduced. At this time, the rotational speed of the supercharger decreases due to a decrease in the temperature of the exhaust gas from the gas engine. As a result, the inflow amount of the second air-fuel mixture to the supercharger, the inflow amount of the first air-fuel mixture to the second mixer, and the inflow amount of combustion air to the first mixer are reduced, respectively. By reducing the suction force at, the amount of inflow of the auxiliary fuel gas to the first mixer decreases.
Thus, when the supply flow rate of the main fuel gas to the gas engine decreases, the supply flow rates of the combustion air and the auxiliary fuel gas to the gas engine can also be reduced.

  And in the electric power generation system of this invention, when the calorie | heat amount of sub fuel gas fluctuates, this fluctuation | variation can be supplemented with the supply flow rate of main fuel gas. Specifically, when the amount of heat of the auxiliary fuel gas decreases, the control means increases the throttle valve opening so that the power generation output of the generator becomes the target output, and supplies the main fuel gas to the gas engine. The flow rate can be increased. On the other hand, when the amount of heat of the auxiliary fuel gas increases, the control means decreases the opening of the throttle valve and decreases the supply flow rate of the main fuel gas to the gas engine so that the power generation output of the generator becomes the target output. Can be made. As a result, in the present invention, it is possible to compensate for fluctuations in the calorific value of the auxiliary fuel gas and to constantly supply the fuel gas having the calorific value necessary for the generator to output the target output to the gas engine.

  Further, since the pressure of the auxiliary fuel gas supplied from the auxiliary fuel pipe to the first mixer is set to a predetermined value by the pressure regulator, even if the original pressure in the tank of the auxiliary fuel gas fluctuates, The inflow amount of the auxiliary fuel gas to the first mixer can be stably changed according to the inflow amount of the combustion air to the 1 mixer. Further, the inflow amount of the auxiliary fuel gas to the first mixer is always determined by the inflow amount of combustion air to the first mixer and the set pressure by the pressure regulator, and the change in the supply flow rate of the main fuel gas to the gas engine Accordingly, the supply flow rate of the auxiliary fuel gas to the gas engine can be changed stably.

Thereby, the ratio of the supply flow rate of the auxiliary fuel gas to the gas engine with respect to the total supply flow rate of the main fuel gas and the auxiliary fuel gas to the gas engine is the initially set rate, that is, the predetermined rate at which the gas engine can be stably operated. Can not be exceeded.
Even when the heat amount of the auxiliary fuel gas fluctuates or when the load on the generator fluctuates and the output of the gas engine fluctuates, the sub fuel gas with respect to the total supply heat amount of the main fuel gas and the auxiliary fuel gas to the gas engine changes. It is possible to prevent the ratio of the supply heat amount of the fuel gas from exceeding a predetermined ratio at which stable operation can be performed in the gas engine. Therefore, it is possible to prevent the operation of the gas engine from becoming unstable.

  Therefore, according to the power generation system of the present invention, the ratio of the calorific value of the auxiliary fuel gas supplied to the gas engine is always stable without using any valve other than the throttle valve for controlling the opening degree and without performing any special control. It can be kept below a predetermined ratio at which driving is possible.

A second invention is a gas engine having a plurality of cylinders;
A generator operated by the output of the gas engine;
An air pipe to which combustion air is supplied;
A main fuel pipe to which main fuel gas is supplied;
A throttle valve provided in the main fuel pipe;
A first mixer for mixing the combustion air flowing in from the air pipe with the main fuel gas after flow adjustment by the throttle valve from the main fuel pipe to create a first air-fuel mixture;
An auxiliary fuel pipe to which an auxiliary fuel gas such as biogas is supplied;
A pressure regulator provided in the auxiliary fuel pipe;
According to the suction force generated when the first air-fuel mixture flowing in from the first mixer passes through the venturi, the auxiliary fuel gas after pressure setting by the pressure regulator flows from the auxiliary fuel pipe, A second mixer for mixing the auxiliary fuel gas with the first mixture to create a second mixture;
Using the exhaust gas from the gas engine, compressing the second gas mixture flowing in from the second mixer, and creating a compressed gas mixture;
An intake manifold that supplies the compressed air-fuel mixture flowing from the supercharger in a branched manner to the plurality of cylinders;
Control means for adjusting the opening of the throttle valve so that the power generation output of the generator becomes a target output,
By adjusting the opening degree of the throttle valve in accordance with the target output of the generator by the control means, the amount of heat required to produce the target output that is insufficient with only the auxiliary fuel gas is determined by the main fuel gas. In addition, the ratio of the supply flow rate of the sub fuel gas to the total supply flow rate of the main fuel gas and the sub fuel gas to the gas engine is configured to be kept below the initially set ratio ,
The control means increases the opening of the throttle valve so that the power generation output of the generator becomes a target output when the amount of heat of the auxiliary fuel gas decreases, and the main fuel gas to the gas engine is increased. On the other hand, when the amount of heat of the auxiliary fuel gas is increased, the opening of the throttle valve is decreased so that the power generation output of the generator becomes the target output, and the gas engine is supplied to the gas engine. The power generation system is configured to reduce the supply flow rate of the main fuel gas (claim 3).

The power generation system of the present invention can also keep the ratio of the amount of heat supplied from the auxiliary fuel gas to the gas engine at or below a predetermined ratio at which stable operation is possible without special control.
Specifically, in the power generation system of the present invention, the inflow amount of the auxiliary fuel gas to the second mixer is adjusted by a pressure regulator provided in the auxiliary fuel pipe, and the main fuel gas and the auxiliary fuel to the gas engine are adjusted. The ratio of the supply flow rate of the auxiliary fuel gas to the total supply flow rate with gas is initially set within a range that does not exceed a predetermined ratio at which stable operation can be performed in the gas engine.

When this initial setting is performed, assuming that the amount of heat of the auxiliary fuel gas is maximized, the ratio of the amount of heat supplied to the auxiliary fuel gas to the total amount of heat supplied to the gas engine and the amount of auxiliary fuel gas is the gas engine. The ratio of the supply flow rate of the auxiliary fuel gas is set within a range not exceeding a predetermined ratio at which stable operation is possible.
When performing the initial setting, the flow rate can be finely adjusted by adjusting the set pressure with a pressure regulator and adjusting the opening of a manual valve or the like provided in the auxiliary fuel pipe.

  When the power generation system of the present invention is operated, a first mixture of combustion air and main fuel gas is created in the first mixer, and the first mixture and auxiliary fuel gas are mixed in the second mixer. A second mixture is created. Next, in the supercharger, the second air-fuel mixture is compressed to produce a compressed air-fuel mixture, and this compressed air-fuel mixture is supplied to a plurality of cylinders in the gas engine via the intake manifold. Then, the generator can be operated at the target output by adjusting the opening of the throttle valve by the control means and adjusting the supply flow rate of the main fuel gas to the gas engine.

In the power generation system of the present invention, when the output of the gas engine is increased, the opening of the throttle valve is increased by a command from the control means, and the supply flow rate of the main fuel gas to the gas engine is increased. At this time, the rotational speed of the supercharger increases as the temperature of the exhaust gas from the gas engine increases. As a result, the inflow amount of the second air-fuel mixture to the supercharger, the inflow amount of the first air-fuel mixture to the second mixer, and the inflow amount of combustion air to the first mixer increase, respectively, and the venturi of the second mixer As the suction force increases, the amount of inflow of the auxiliary fuel gas to the second mixer increases.
Thus, when the supply flow rate of the main fuel gas to the gas engine increases, the supply flow rates of the combustion air and the auxiliary fuel gas to the gas engine can also be increased.

On the other hand, when the output of the gas engine is reduced, the opening of the throttle valve is reduced by a command from the control means, and the supply flow rate of the main fuel gas to the gas engine is reduced. At this time, the rotational speed of the supercharger decreases due to a decrease in the temperature of the exhaust gas from the gas engine. As a result, the inflow amount of the second air-fuel mixture to the supercharger, the inflow amount of the first air-fuel mixture to the second mixer, and the inflow amount of combustion air to the first mixer are reduced, respectively, and the venturi of the second mixer is reduced. By reducing the suction force at, the inflow amount of the auxiliary fuel gas to the second mixer is reduced.
Thus, when the supply flow rate of the main fuel gas to the gas engine decreases, the supply flow rates of the combustion air and the auxiliary fuel gas to the gas engine can also be reduced.

Also in the power generation system of the present invention, as in the first aspect of the invention, the main fuel gas compensates for the variation in the calorific value of the auxiliary fuel gas, and the fuel gas having the calorific value necessary for the generator to produce the target output, It can always be supplied to the gas engine.
Further, since the pressure of the auxiliary fuel gas supplied from the auxiliary fuel pipe to the second mixer is set to a predetermined value by the pressure regulator, even if the original pressure in the tank of the auxiliary fuel gas fluctuates, The inflow amount of the auxiliary fuel gas to the second mixer can be stably changed according to the inflow amount of the first air-fuel mixture to the two mixers. The inflow amount of the auxiliary fuel gas to the second mixer is always determined by the inflow amount of the first air-fuel mixture to the second mixer and the set pressure by the pressure regulator, and the main fuel gas supply flow rate to the gas engine is According to the change, the supply flow rate of the auxiliary fuel gas to the gas engine can be changed stably.

Thereby, the ratio of the supply flow rate of the auxiliary fuel gas to the gas engine with respect to the total supply flow rate of the main fuel gas and the auxiliary fuel gas to the gas engine is the initially set rate, that is, the predetermined rate at which the gas engine can be stably operated. Can not be exceeded.
Even when the heat amount of the auxiliary fuel gas fluctuates or when the load on the generator fluctuates and the output of the gas engine fluctuates, the sub fuel gas with respect to the total supply heat amount of the main fuel gas and the auxiliary fuel gas to the gas engine changes. It is possible to prevent the ratio of the supply heat amount of the fuel gas from exceeding a predetermined ratio at which stable operation can be performed in the gas engine. Therefore, it is possible to prevent the operation of the gas engine from becoming unstable.

  Therefore, even with the power generation system of the present invention, the ratio of the amount of heat supplied to the sub-fuel gas to the gas engine is always stably operated without using any valve other than the throttle valve for controlling the opening degree and without performing any special control. Can be kept below a predetermined ratio.

A preferred embodiment in the first and second inventions described above will be described.
In the first and second inventions, city gas (such as 13A) containing methane or the like can be used as the main fuel gas. The secondary fuel gas includes biogas produced by fermenting organic waste (livestock manure, raw garbage, organic residue, sewage sludge, etc.), wood waste (factory scrap, building waste, etc.) A fuel gas such as a biogas generated by pyrolyzing and by-product gas generated in a factory or the like can be used. In addition, a general gas fuel different from the main fuel gas may be used as the auxiliary fuel gas.

In the first invention, when the pressure of the combustion air in the air pipe decreases because the pilot regulator for adjusting the set pressure is connected to the air pipe, the pressure regulator It is preferable that the set pressure is corrected to be low as the pressure decreases (claim 2).
According to a second aspect of the present invention, the pilot regulator for adjusting the set pressure is connected to an intake pipe connecting the first mixer and the second mixer, so that the intake pipe When the pressure of the first air-fuel mixture is reduced, the set pressure is preferably corrected to be low according to the pressure drop.
In these cases, even when the pressure of the combustion air in the air pipe slightly varies, it is possible to prevent the supply flow rate of the auxiliary fuel gas to the gas engine from fluctuating due to the influence of the variation.

In the first invention, the set pressure of the auxiliary fuel gas by the pressure regulator can be set to be substantially the same as the pressure of the combustion air in the air pipe. Thereby, in 1st invention, according to the inflow amount of the combustion air to a 1st mixer, the inflow amount of the sub fuel gas to a 1st mixer can be changed more stably.
In the second aspect of the invention, the set pressure of the auxiliary fuel gas by the pressure regulator can be set to be substantially the same as the pressure of the first air-fuel mixture at the inlet of the second mixer. Thereby, the inflow amount of the auxiliary fuel gas to the second mixer can be changed more stably according to the inflow amount of the first air-fuel mixture to the second mixer.

The auxiliary fuel pipe is preferably provided with an electromagnetic valve capable of opening and closing the auxiliary fuel pipe.
In this case, when the auxiliary fuel pipe is closed by the electromagnetic valve, the power generation system can be operated using only the main fuel gas.

Hereinafter, embodiments of the power generation system of the present invention will be described with reference to the drawings.
Example 1
As shown in FIG. 1, the power generation system 1 of this example is configured to operate the generator 11 by the output of the gas engine 2 having a plurality of cylinders 21. The power generation system 1 includes a main fuel supply system that supplies a main fuel gas F1 such as city gas to the gas engine 2, and a sub fuel supply system that supplies a sub fuel gas F2 such as biogas to the gas engine 2. The gas engine 2 is operated by co-firing the main fuel gas F1 and the auxiliary fuel gas F2.

  As shown in the figure, the auxiliary fuel supply system of this example includes an auxiliary fuel pipe 6 to which an auxiliary fuel gas F2 such as biogas is supplied, a pressure regulator 61 provided in the auxiliary fuel pipe 6, and combustion air A. The air pipe 4 to be supplied and the first mixer 7A for producing the first air-fuel mixture M1 by mixing the combustion air A flowing in from the air pipe 4 with the auxiliary fuel gas F2 flowing in from the auxiliary fuel pipe 6 ing. The first mixer 7A sucks the auxiliary fuel gas F2 after the pressure is set by the pressure regulator 61 from the auxiliary fuel pipe 6 according to the suction force generated when the combustion air A flowing in from the air pipe 4 passes through the venturi 71. It is configured to be.

As shown in FIG. 1, the main fuel supply system of this example includes a main fuel pipe 5 to which a main fuel gas F1 is supplied, a throttle valve 51 provided in the main fuel pipe 5, and a first mixer 7A that flows in from the first mixer 7A. The air-fuel mixture M1 has a second mixer 7B that mixes the main fuel gas F1 whose flow rate is adjusted by the throttle valve 51 from the main fuel pipe 5 to produce the second air-fuel mixture M2.
Further, on the downstream side of the second mixer 7B, a supercharger 3 that uses the exhaust gas G from the gas engine 2 to compress the second air-fuel mixture M2 flowing from the second mixer 7B to produce a compressed air-fuel mixture M3, An intake manifold 22 for connecting the compressed mixture M3 flowing from the supercharger 3 to the plurality of cylinders 21 is connected. The power generation system 1 can be controlled by the control means 8 such as an electronic control unit, and the opening degree of the throttle valve 51 is controlled by the control means 8 so that the power generation output of the generator 11 becomes the target output.

  When operating the power generation system 1, the opening of the throttle valve 51 is adjusted by the control means 8 in accordance with the target output of the generator 11, and the amount of main fuel gas F1 flowing into the second mixer 7B is determined. In addition, the rotational speed of the supercharger 3 changes according to the output of the gas engine 2, and the inflow amount of the combustion air A to the first mixer 7A is determined according to the rotational speed of the supercharger 3, and The inflow amount of the auxiliary fuel gas F2 to the first mixer 7A is determined according to the inflow amount of the combustion air A.

  In the power generation system 1, the control means 8 adjusts the opening degree of the throttle valve 51 in accordance with the target output of the generator 11, so that the amount of heat necessary for producing a target output that is insufficient only with the auxiliary fuel gas F2. Is supplemented by the main fuel gas F1, and the ratio of the supply flow rate of the auxiliary fuel gas F2 to the total supply flow rate of the main fuel gas F1 and the auxiliary fuel gas F2 to the gas engine 2 is kept below the initially set ratio. It is.

Hereinafter, the power generation system 1 of this example will be described in detail with reference to FIGS.
The power generation system 1 of this example is of a grid connection type that operates the generator 11 by connection with a commercial power source, and rotates the generator 11 in accordance with the frequency (50 Hz or 60 Hz) of the commercial power source. The generator 11 of this example performs power generation by rotating the rotor at a constant rotational speed determined by the frequency of the commercial power source.

  The control means 8 of this example is configured to measure the power generation output of the generator 11 with a wattmeter 81, adjust the opening of the throttle valve 51 so that this power generation output becomes the target output, and perform feedback control. is there. The control means 8 can also adjust the opening degree of the throttle valve 51 so that the rotational speed of the gas engine 2 becomes the target rotational speed.

As shown in FIG. 1, the supercharger 3 of this example is an exhaust gas supercharger 3 that operates using the energy of the exhaust gas G exhausted from the gas engine 2. The exhaust gas supercharger 3 is coupled to a turbine wheel 31 rotated by exhaust gas G passing through an exhaust manifold 23 in which exhaust ports of a plurality of cylinders 21 of the gas engine 2 are concentrated, and the turbine wheel 31 on the same axis. The compressor wheel 32 is configured to rotate in response to the rotation of the turbine wheel 31. Then, the second air-fuel mixture M <b> 2 sent from the second mixer 7 </ b> B to the supercharger 3 is converted into a compressed air-fuel mixture M <b> 3 by the compressor wheel 32 and supplied to the gas engine 2.
The throttle valve 51 of this example receives a command from the control means 8 and operates the valve body 511 disposed at the passage port through which the main fuel gas F1 passes through the actuator 512 to adjust the opening degree of the passage port. It is configured to

As shown in FIG. 2, the first mixer 7 </ b> A of this example is provided with a venturi 71 in the main passage 70, and a plurality of tip opening holes 721 in the sub-passage 72 on the outer periphery of the throat portion (throttle portion) 711 in the venturi 71. Is configured to open. Then, when the combustion air A passes through the venturi 71 in the main passage 70, the throat portion 711 in the venturi 71 becomes negative pressure, and the auxiliary fuel gas F2 enters the main passage 70 from the sub passage 72 by the suction force due to the negative pressure. Can be aspirated.
The second mixer 7B of this example also has the same configuration as the first mixer 7A, and is configured to mix the main fuel gas F1 with the first air-fuel mixture M1 passing through the main passage 70.

Further, as shown in FIG. 1, the first mixer 7 </ b> A, the second mixer 7 </ b> B, and the compressor wheel 32 of the supercharger 3 are connected by the intake pipe 12.
Further, the auxiliary fuel pipe 6 of this example is provided with an electromagnetic valve 62 that can open and close the auxiliary fuel pipe 6 on the downstream side of the pressure regulator 61. The electromagnetic valve 62 can be operated by other control means 8 or the like. When the gas engine 2 is operated by co-firing using the main fuel gas F1 and the auxiliary fuel gas F2, the auxiliary fuel is always used. When the gas engine 2 is operated by burning only the main fuel gas F1, the sub fuel pipe 6 is closed.

As shown in the figure, in this example, the air pipe 4 is open to the atmosphere, and the auxiliary fuel pipe 6 is connected to a tank (not shown) in which the auxiliary fuel gas F2 such as biogas is generated or stored. ing. The set pressure of the auxiliary fuel gas F2 by the pressure regulator 61 is set to be almost atmospheric pressure.
An air filter 41 for preventing foreign matter from entering the gas engine 2 is disposed at the inlet of the air pipe 4. When the power generation system 1 is operated for a long period of time, on the downstream side of the air filter 41 in the air pipe 4, the negative pressure is slightly lower than the atmospheric pressure due to clogging generated in the air filter 41.

  As shown in FIG. 1, in the pressure regulator 61 of this example, the pilot section 611 that adjusts the set pressure is downstream of the air filter 41 in the air pipe 4 by the pipe 612, and the first mixer It is connected upstream of 7A. The pressure regulator 61 is configured to correct the set pressure to be low according to the decrease in the pressure of the combustion air A downstream of the air filter 41 in the air pipe 4.

  Specifically, when the air filter 41 is clogged when the power generation system 1 is operated for a long period of time, the pressure of the combustion air A on the downstream side of the air filter 41 is slightly increased due to an increase in pressure loss in the air filter 41. Although the pressure decreases, the set pressure of the pressure regulator 61 is corrected to be slightly lower according to the slight decrease in the pressure. Thereby, it is suppressed that the set pressure of the pressure regulator 61 becomes relatively higher than the pressure of the combustion air A on the downstream side of the air filter 41, and the inflow amount of the auxiliary fuel gas F2 to the first mixer 7A. Can be suppressed from increasing slightly. Therefore, when the power generation system 1 is operated for a long period, it is possible to suppress a slight increase in the supply flow rate of the auxiliary fuel gas F2 to the gas engine 2.

In addition, before the operation of the power generation system 1, the supply pressure of the auxiliary fuel gas F2 to the first mixer 7A is determined by setting the set pressure of the pressure regulator 61 to a predetermined value. In the auxiliary fuel pipe 6, a manual valve can be disposed between the pressure regulator 61 and the electromagnetic valve 62. When the power generation system 1 is initially set, the flow rate of the auxiliary fuel gas F2 can be adjusted by operating the manual valve.
In addition, when the pressure of the auxiliary fuel gas F2 is set by the pressure regulator 61, if the auxiliary fuel gas F2 contains a gas that easily causes knocking such as hydrogen or butane, the auxiliary fuel gas F2 is used to avoid knocking. The mixing ratio can be suppressed to a predetermined ratio or less.

  Further, the amount of heat supplied to the gas engine 2 of the auxiliary fuel gas F2 can prevent the above-described knocking with respect to the total amount of supplied heat of the main fuel gas F1 supplied to the gas engine 2 and the amount of supplied heat of the auxiliary fuel gas F2. Can be determined by range. Further, the supply heat amount of the main fuel gas F1 can be determined within a range that can follow a rapid load fluctuation in the generator 11 with respect to the total supply heat amount. The gas engine 2 can be operated even if the supply heat amount of the auxiliary fuel gas F2 is larger than the supply heat amount of the main fuel gas F1. The supply heat amount of the main fuel gas F1 is considered to be at least about 10% with respect to the total supply heat amount.

The power generation system 1 of this example can keep the ratio of the amount of heat supplied from the auxiliary fuel gas F2 to the gas engine 2 below a predetermined ratio at which stable operation is possible without performing any special control.
Specifically, in the power generation system 1 of this example, the inflow amount of the auxiliary fuel gas F2 to the first mixer 7A is adjusted by the pressure regulator 61 provided in the auxiliary fuel pipe 6, and The ratio of the supply flow rate of the sub fuel gas F2 to the total supply flow rate of the main fuel gas F1 and the sub fuel gas F2 is initially set within a range that does not exceed a predetermined ratio at which the gas engine 2 can be stably operated.

When performing this initial setting, it is assumed that the amount of heat of the auxiliary fuel gas F2 is maximized, and the amount of heat supplied to the auxiliary fuel gas F2 with respect to the total amount of supplied heat of the main fuel gas F1 and the auxiliary fuel gas F2 to the gas engine 2 The ratio of the supply flow rate of the auxiliary fuel gas F2 is set within a range in which the ratio does not exceed a predetermined ratio at which stable operation can be performed in the gas engine 2.
When performing the initial setting, the flow rate can be finely adjusted by adjusting the set pressure by the pressure regulator 61 and adjusting the opening of the manual valve provided in the auxiliary fuel pipe 6.

  When the power generation system 1 of this example is operated, the first mixer 7A produces the first mixture M1 of the combustion air A and the auxiliary fuel gas F2, and the second mixer 7B produces the first mixture. A second mixture M2 of M1 and main fuel gas F1 is created. Next, in the supercharger 3, the second mixture M <b> 2 is compressed to produce a compressed mixture M <b> 3, and this compressed mixture M <b> 3 is supplied to the plurality of cylinders 21 in the gas engine 2 via the intake manifold 22. . The generator 11 can be operated at the target output by adjusting the opening of the throttle valve 51 by the control means 8 and adjusting the supply flow rate of the main fuel gas F1 to the gas engine 2.

In the power generation system 1 of this example, when the output of the gas engine 2 is increased, the opening degree of the throttle valve 51 is increased by a command from the control means 8, and the supply flow rate of the main fuel gas F1 to the gas engine 2 is increased. . At this time, when the temperature of the exhaust gas G from the gas engine 2 increases, the expansion work of the supercharger 3 increases, and the rotational speed of the supercharger 3 increases. Thereby, the inflow amount of the second air-fuel mixture M2 to the supercharger 3, the inflow amount of the first air-fuel mixture M1 to the second mixer 7B, and the inflow amount of the combustion air A to the first mixer 7A are increased. As the suction force in the venturi 71 of the first mixer 7A increases, the inflow amount of the auxiliary fuel gas F2 to the first mixer 7A increases.
Thus, when the supply flow rate of the main fuel gas F1 to the gas engine 2 increases, the supply flow rates of the combustion air A and the auxiliary fuel gas F2 to the gas engine 2 can also be increased.

On the other hand, when the output of the gas engine 2 is reduced, the opening degree of the throttle valve 51 is reduced by a command from the control means 8, and the supply flow rate of the main fuel gas F1 to the gas engine 2 is reduced. At this time, when the temperature of the exhaust gas G from the gas engine 2 decreases, the expansion work of the supercharger 3 decreases, and the rotational speed of the supercharger 3 decreases. Thereby, the inflow amount of the second air-fuel mixture M2 to the supercharger 3, the inflow amount of the first air-fuel mixture M1 to the second mixer 7B, and the inflow amount of the combustion air A to the first mixer 7A are reduced. As the suction force in the venturi 71 of the first mixer 7A decreases, the inflow amount of the auxiliary fuel gas F2 to the first mixer 7A decreases.
Thus, when the supply flow rate of the main fuel gas F1 to the gas engine 2 is reduced, the supply flow rates of the combustion air A and the auxiliary fuel gas F2 to the gas engine 2 can also be reduced.

  In the power generation system 1 of this example, when the composition or the like of the auxiliary fuel gas F2 changes and the amount of heat changes, the change in the amount of heat can be compensated by the supply flow rate of the main fuel gas F1. Specifically, when the amount of heat of the auxiliary fuel gas F2 decreases, the control means 8 increases the opening of the throttle valve 51 so that the power generation output of the generator 11 becomes the target output, The supply flow rate of the main fuel gas F1 can be increased. On the other hand, when the amount of heat of the auxiliary fuel gas F2 increases, the control means 8 decreases the opening of the throttle valve 51 so that the power generation output of the generator 11 becomes the target output, and the main fuel gas to the gas engine 2 is increased. The supply flow rate of F1 can be reduced. Thereby, in this example, the fuel gas of the calorie | heat amount required in order to make up the fluctuation | variation of the calorie | heat amount of the sub fuel gas F2 and the generator 11 output target output can always be supplied to the gas engine 2. FIG.

  Further, the pressure of the auxiliary fuel gas F2 supplied from the auxiliary fuel pipe 6 to the first mixer 7A is set to a predetermined value by the pressure regulator 61, so that the original pressure of the auxiliary fuel gas F2 in the tank or the like fluctuates. Even so, the inflow amount of the auxiliary fuel gas F2 to the first mixer 7A can be stably changed in accordance with the inflow amount of the combustion air A to the first mixer 7A. The inflow amount of the auxiliary fuel gas F2 to the first mixer 7A is always determined by the inflow amount of the combustion air A to the first mixer 7A and the set pressure by the pressure regulator 61, and the main fuel to the gas engine 2 is determined. The supply flow rate of the auxiliary fuel gas F2 to the gas engine 2 can be stably changed according to the change in the supply flow rate of the gas F1.

Thereby, the ratio of the supply flow rate of the auxiliary fuel gas F2 to the gas engine 2 with respect to the total supply flow rate of the main fuel gas F1 and the auxiliary fuel gas F2 to the gas engine 2 is stable in the initially set rate, that is, the gas engine 2. It is possible not to exceed a predetermined ratio at which driving is possible.
Further, when the amount of heat of the auxiliary fuel gas F2 fluctuates or when the load on the generator 11 fluctuates and the output of the gas engine 2 fluctuates, the main fuel gas F1 and the auxiliary fuel gas F2 to the gas engine 2 The ratio of the supply heat amount of the auxiliary fuel gas F2 to the total supply heat amount of the gas engine 2 can be made not to exceed a predetermined ratio at which the gas engine 2 can be stably operated. Therefore, it is possible to prevent the operation of the gas engine 2 from becoming unstable.

  Therefore, according to the power generation system 1 of this example, the ratio of the amount of heat supplied to the gas engine 2 without using the valve for controlling the opening other than the throttle valve 51 and without performing special control. Can be kept below a predetermined ratio at which stable operation is always possible.

  Further, in the power generation system 1 of this example, the combustion air A is supplied to the gas engine 2 in accordance with the amount of heat of the fuel gas supplied to the gas engine 2. Therefore, without performing special control, the air ratio in the gas engine 2 (the excess air ratio, that is, the value obtained by dividing the actually supplied air amount by the amount of air required for completely burning the fuel gas theoretically). It can be kept almost constant. Note that the air ratio in the gas engine 2 may slightly change under the influence of the characteristics of the supercharger 3, the temperature of the combustion air A, and the like.

(Example 2)
In this example, as shown in FIG. 3, the first mixture M1 obtained by mixing the combustion air A and the main fuel gas F1 is mixed with the auxiliary fuel gas F2 to create the second mixture M2. is there.
The power generation system 1 of this example also includes a main fuel supply system that supplies a main fuel gas F1 such as city gas to the gas engine 2 and a sub fuel supply system that supplies a sub fuel gas F2 such as biogas to the gas engine 2. Have.

  As shown in the figure, the main fuel supply system of this example includes an air pipe 4 to which combustion air A is supplied, a main fuel pipe 5 to which main fuel gas F1 is supplied, and a throttle provided in the main fuel pipe 5. A valve 51 and a first mixer 7A for producing the first mixture M1 by mixing the combustion fuel A flowing in from the air pipe 4 with the main fuel gas F1 whose flow rate is adjusted by the throttle valve 51 from the main fuel pipe 5; is doing.

  The auxiliary fuel supply system of this example includes an auxiliary fuel pipe 6 to which an auxiliary fuel gas F2 such as biogas is supplied, a pressure regulator 61 provided in the auxiliary fuel pipe 6, and a first air-fuel mixture flowing from the first mixer 7A. A second mixer 7B that mixes the sub fuel gas F2 flowing from the sub fuel pipe 6 into M1 to produce the second air-fuel mixture M2. The second mixer 7B has a sub fuel gas F2 after the pressure is set by the pressure regulator 61 from the sub fuel pipe 6 according to the suction force generated when the first air-fuel mixture M1 flowing from the first mixer 7A passes through the venturi 71. Is configured to be sucked.

In the power generation system 1 of this example, the opening of the throttle valve 51 is controlled by the control means 8 in accordance with the target output of the generator 11 to determine the amount of main fuel gas F1 flowing into the first mixer 7A. At the same time, the rotational speed of the supercharger 3 changes according to the output of the gas engine 2, and the inflow amount of the combustion air A to the first mixer 7 </ b> A is determined according to the rotational speed of the supercharger 3, and combustion The inflow amount of the auxiliary fuel gas F2 to the second mixer 7B is determined according to the inflow amount of the working air A.
Further, in the pressure regulator 61 of this example, a pilot section 611 that adjusts the set pressure is connected to the intake pipe 12 that connects the first mixer 7A and the second mixer 7B by a pipe 612.

  In the power generation system 1 of this example, the inflow amount of the auxiliary fuel gas F2 to the second mixer 7B is adjusted by the pressure regulator 61 provided in the auxiliary fuel pipe 6, and the main fuel gas F1 to the gas engine 2 is adjusted. The ratio of the supply flow rate of the auxiliary fuel gas F2 to the total supply flow rate with the auxiliary fuel gas F2 is initially set within a range not exceeding a predetermined ratio at which the gas engine 2 can be stably operated.

When performing this initial setting, it is assumed that the amount of heat of the auxiliary fuel gas F2 is maximized, and the amount of heat supplied to the auxiliary fuel gas F2 with respect to the total amount of supplied heat of the main fuel gas F1 and the auxiliary fuel gas F2 to the gas engine 2 The ratio of the supply flow rate of the auxiliary fuel gas F2 is set within a range in which the ratio does not exceed a predetermined ratio at which stable operation can be performed in the gas engine 2.
When the initial setting is performed, the flow rate can be finely adjusted by adjusting the set pressure by the pressure regulator 61 and adjusting the opening of a manual valve or the like provided in the auxiliary fuel pipe 6.

  When the power generation system 1 of this example is operated, the first mixture M1 of the combustion air A and the main fuel gas F1 is produced in the first mixer 7A, and the first mixture is produced in the second mixer 7B. A second gas mixture M2 of M1 and the auxiliary fuel gas F2 is created. Next, in the supercharger 3, the second mixture M <b> 2 is compressed to produce a compressed mixture M <b> 3, and this compressed mixture M <b> 3 is supplied to the plurality of cylinders 21 in the gas engine 2 via the intake manifold 22. . The generator 11 can be operated at the target output by adjusting the opening of the throttle valve 51 by the control means 8 and adjusting the supply flow rate of the main fuel gas F1 to the gas engine 2.

In the power generation system 1 of this example as well, as in the first embodiment, the main fuel gas F1 compensates for the variation in the amount of heat of the sub fuel gas F2, and the fuel of the amount of heat necessary for the generator 11 to output the target output. Gas can be constantly supplied to the gas engine 2.
Further, the pressure of the auxiliary fuel gas F2 supplied from the auxiliary fuel pipe 6 to the second mixer 7B is set to a predetermined value by the pressure regulator 61, so that the original pressure of the auxiliary fuel gas F2 in the tank or the like fluctuates. Even so, the inflow amount of the auxiliary fuel gas F2 to the second mixer 7B can be stably changed in accordance with the inflow amount of the first mixture M1 to the second mixer 7B. The inflow amount of the auxiliary fuel gas F2 to the second mixer 7B is always determined by the inflow amount of the first air-fuel mixture M1 to the second mixer 7B and the set pressure by the pressure regulator 61. The supply flow rate of the auxiliary fuel gas F2 to the gas engine 2 can be stably changed according to the change in the supply flow rate of the fuel gas F1.

Thereby, the ratio of the supply flow rate of the auxiliary fuel gas F2 to the gas engine 2 with respect to the total supply flow rate of the main fuel gas F1 and the auxiliary fuel gas F2 to the gas engine 2 is stable in the initially set rate, that is, the gas engine 2. It is possible not to exceed a predetermined ratio at which driving is possible.
Further, when the amount of heat of the auxiliary fuel gas F2 fluctuates or when the load on the generator 11 fluctuates and the output of the gas engine 2 fluctuates, the main fuel gas F1 and the auxiliary fuel gas F2 to the gas engine 2 The ratio of the supply heat amount of the auxiliary fuel gas F2 to the total supply heat amount of the gas engine 2 can be made not to exceed a predetermined ratio at which the gas engine 2 can be stably operated. Therefore, it is possible to prevent the operation of the gas engine 2 from becoming unstable.

  Therefore, even with the power generation system 1 of the present example, the ratio of the amount of heat supplied to the gas engine 2 of the auxiliary fuel gas F2 can be set without using any valve other than the throttle valve 51 for controlling the opening degree and without performing any special control. Therefore, it can be kept below a predetermined ratio at which stable operation is always possible. Also in this example, other configurations are the same as those of the first embodiment, and the same effects as those of the first embodiment can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 3 is an explanatory diagram schematically showing a structure of a first mixer in the first embodiment. Explanatory drawing which shows the electric power generation system in Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power generation system 11 Generator 2 Gas engine 21 Cylinder 22 Intake manifold 3 Supercharger 4 Air piping 5 Main fuel piping 51 Throttle valve 6 Sub fuel piping 61 Pressure regulator 62 Electromagnetic valve 7A 1st mixer 7B 2nd mixer 71 Venturi 8 Control Means A Combustion air F1 Main fuel gas F2 Sub fuel gas M1 First mixture M2 Second mixture M3 Compressed mixture G Exhaust gas

Claims (5)

A gas engine with multiple cylinders;
A generator operated by the output of the gas engine;
An auxiliary fuel pipe to which an auxiliary fuel gas such as biogas is supplied;
A pressure regulator provided in the auxiliary fuel pipe;
An air pipe to which combustion air is supplied;
In response to the suction force generated when the combustion air flowing in from the air pipe passes through the venturi, the auxiliary fuel gas after the pressure is set by the pressure regulator flows in from the auxiliary fuel pipe. A first mixer that mixes the secondary fuel gas with air to produce a first air-fuel mixture;
A main fuel pipe to which main fuel gas is supplied;
A throttle valve provided in the main fuel pipe;
A second mixer that mixes the first fuel mixture flowing in from the first mixer with the main fuel gas after flow adjustment by the throttle valve from the main fuel pipe to create a second gas mixture;
Using the exhaust gas from the gas engine, compressing the second gas mixture flowing in from the second mixer, and creating a compressed gas mixture;
An intake manifold that supplies the compressed air-fuel mixture flowing from the supercharger in a branched manner to the plurality of cylinders;
Control means for adjusting the opening of the throttle valve so that the power generation output of the generator becomes a target output,
By adjusting the opening degree of the throttle valve in accordance with the target output of the generator by the control means, the amount of heat required to produce the target output that is insufficient with only the auxiliary fuel gas is determined by the main fuel gas. In addition, the ratio of the supply flow rate of the sub fuel gas to the total supply flow rate of the main fuel gas and the sub fuel gas to the gas engine is configured to be kept below the initially set ratio ,
The control means increases the opening of the throttle valve so that the power generation output of the generator becomes a target output when the amount of heat of the auxiliary fuel gas decreases, and the main fuel gas to the gas engine is increased. On the other hand, when the amount of heat of the auxiliary fuel gas is increased, the opening of the throttle valve is decreased so that the power generation output of the generator becomes the target output, and the gas engine is supplied to the gas engine. A power generation system configured to reduce a supply flow rate of the main fuel gas .   In claim 1, when the pressure of the combustion air in the air pipe is reduced due to the fact that the pilot section for adjusting the set pressure is connected to the air pipe, the pressure regulator reduces the pressure. Accordingly, the power generation system is configured to correct the set pressure low. A gas engine with multiple cylinders;
A generator operated by the output of the gas engine;
An air pipe to which combustion air is supplied;
A main fuel pipe to which main fuel gas is supplied;
A throttle valve provided in the main fuel pipe;
A first mixer for mixing the combustion air flowing in from the air pipe with the main fuel gas after flow adjustment by the throttle valve from the main fuel pipe to create a first air-fuel mixture;
An auxiliary fuel pipe to which an auxiliary fuel gas such as biogas is supplied;
A pressure regulator provided in the auxiliary fuel pipe;
According to the suction force generated when the first air-fuel mixture flowing in from the first mixer passes through the venturi, the auxiliary fuel gas after pressure setting by the pressure regulator flows from the auxiliary fuel pipe, A second mixer for mixing the auxiliary fuel gas with the first mixture to create a second mixture;
Using the exhaust gas from the gas engine, compressing the second gas mixture flowing in from the second mixer, and creating a compressed gas mixture;
An intake manifold that supplies the compressed air-fuel mixture flowing from the supercharger in a branched manner to the plurality of cylinders;
Control means for adjusting the opening of the throttle valve so that the power generation output of the generator becomes a target output,
By adjusting the opening degree of the throttle valve in accordance with the target output of the generator by the control means, the amount of heat required to produce the target output that is insufficient with only the auxiliary fuel gas is determined by the main fuel gas. In addition, the ratio of the supply flow rate of the sub fuel gas to the total supply flow rate of the main fuel gas and the sub fuel gas to the gas engine is configured to be kept below the initially set ratio ,
The control means increases the opening of the throttle valve so that the power generation output of the generator becomes a target output when the amount of heat of the auxiliary fuel gas decreases, and the main fuel gas to the gas engine is increased. On the other hand, when the amount of heat of the auxiliary fuel gas is increased, the opening of the throttle valve is decreased so that the power generation output of the generator becomes the target output, and the gas engine is supplied to the gas engine. A power generation system configured to reduce a supply flow rate of the main fuel gas .   The pressure regulator according to claim 3, wherein a pilot section that adjusts the set pressure is connected to an intake pipe that connects the first mixer and the second mixer, so that the first pressure in the intake pipe is set. A power generation system configured to correct the set pressure to be low in accordance with a decrease in the pressure of the air-fuel mixture.   The power generation system according to any one of claims 1 to 4, wherein the sub fuel pipe is provided with an electromagnetic valve capable of opening and closing the sub fuel pipe.

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