JP4247191B2 - Gas supply device and operation method for gas engine - Google Patents

Description

  The present invention is particularly suitable for a gas engine using low-calorie gas (gas having a low calorific value) as a fuel, includes an exhaust turbocharger, mixes fuel gas and air supplied through a fuel gas passage, The present invention relates to a gas supply device for a gas engine that supplies this air-fuel mixture into a cylinder to cause ignition and combustion.

In a lean combustion gas engine, fuel gas and air are mixed while controlling to a required air-fuel ratio, and this mixed gas is supplied to the combustion chamber of the engine through a supply pipe equipped with a mixed gas flow rate adjusting means such as a throttle valve. is doing.
Among such lean combustion gas engines, in a gas engine equipped with an exhaust turbocharger (hereinafter referred to as a supercharger), the following two types of fuel gas supply methods are used.
(1) The fuel gas pressurized to a pressure higher than the supercharging air pressure by the gas compressor is injected into the supply branch pipe of each cylinder immediately before each cylinder.
(2) The fuel gas is mixed with the supercharger inlet air and the air-fuel mixture is supplied to the supercharger. The air-fuel mixture is compressed by the supercharger and supplied to the engine.

Further, as a technique combining the means (1) and the means (2), a technique disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2001-132550) is provided.
In this technique, the fuel gas pressurized by the gas compressor is supplied to the cylinder inlet or the cylinder of the supply passage, and the fuel gas before being pressurized by the gas compressor is supplied to the air passage upstream of the supercharger. The fuel gas supply to the cylinder side and the fuel gas supply to the turbocharger upstream side can be switched.

JP 2001-132550 A

However, the prior art provided in Patent Document 1 has the following problems.
That is, in the conventional technology, in the fuel gas supply system that supplies the fuel gas pressurized by the gas compressor to the cylinder inlet of the supply passage or into the cylinder, the fuel gas is compressed to a pressure higher than the supercharging air pressure. It is necessary, but when using low calorie gas (low calorific value gas) such as coal mine methane gas as a fuel gas, a large and large capacity gas compressor is required to compress a gas with a low pressure and a large flow rate. .
On the other hand, in the fuel gas supply system that supplies the fuel gas before being pressurized by the gas compressor to the air passage on the upstream side of the supercharger, the combustible fuel gas is pressurized to high temperature and high pressure by the supercharger. There is a risk of fuel gas explosion at the outlet of the feeder.

Therefore, in view of the problems of the prior art, the present invention mixes the fuel gas with the supercharger inlet air and supplies the air-fuel mixture to the supercharger and the fuel gas in the air supply passage on the cylinder side. In a gas engine with a fuel gas supply system to be supplied, there is no possibility of explosion of fuel gas at the supercharger outlet, and even when using low calorie gas (gas with low calorific value) fuel, An object of the present invention is to provide a gas supply device for a gas engine that can reduce the power of a gas compressor for compressing a fuel gas into a cylinder-side air supply passage to reduce the size and capacity of the gas compressor.

The present invention achieves such an object, and is a gas engine that includes an exhaust turbocharger, mixes fuel gas and air supplied through a fuel gas passage, and supplies the mixture into a cylinder for ignition and combustion. And a gas compressor for compressing the fuel gas connected to the air supply passage for each cylinder is interposed between the fuel gas passage and the supercharger side gas supply passage connected to the air inlet of the supercharger. The fuel gas which branches into the cylinder side gas supply passage and flows through the supercharger side gas supply passage is mixed with the supercharger inlet air to supply this mixture to the supercharger, and the cylinder side gas supply The fuel gas flowing through the passage is mixed with the supply air in the supply passage for each cylinder, and this mixture is supplied to each cylinder of the engine. Supply side gas supply A turbocharger side gas amount adjusting valve for adjusting the gas flow rate of the passage is provided, and a cylinder side gas amount adjusting valve for adjusting the gas flow rate of each cylinder side gas supply passage is provided for each cylinder in the cylinder side gas supply passage, Further, by controlling the opening degree of the supercharger-side gas amount adjusting valve, the fuel gas concentration in the air-fuel mixture for supplying the fuel gas amount to the supercharger-side gas supply passage to the supercharger is set. In addition, a gas amount controller is provided that adjusts the gas so as to be kept below the flammable lower limit gas concentration.
The gas engine operation method is a gas engine operation method in which fuel gas and air supplied through a fuel gas passage are mixed, and the mixture is supplied into a cylinder and ignited and combusted. A part of the gas is mixed with the supercharger inlet air through a supercharger side gas supply passage connected to the air inlet of the supercharger, and this mixture is supplied to the supercharger. A cylinder-side gas supply passage connected to an air supply passage for each cylinder and provided with a gas compressor for compressing the fuel gas is mixed with the air supply in the air supply passage for each cylinder, and this mixture is supplied to each cylinder of the engine. Supply and control the opening degree of the supercharger side gas amount adjusting valve provided in the supercharger side gas supply passage, and the amount of fuel gas to the supercharger side gas supply passage is supplied to the supercharger. Fuel in the mixture Scan concentration and adjusting so as to maintain below flammable lower limit gas concentration.

  According to this invention, the fuel gas passage is divided into two fuel gases, that is, the supercharger side gas supply passage connected to the supercharger inlet air passage and the cylinder side gas supply passage connected to the air supply passage for each cylinder. The fuel gas branched into the supply system and flowing through the supercharger side gas supply passage is mixed with the supercharger inlet air, and this mixture is supplied to the supercharger, while the cylinder side gas supply passage is passed through. The fuel gas that flows is mixed with the supply air in the supply passage for each cylinder, and this mixture is supplied to each cylinder of the engine. The fuel gas flow rate on the gas supply passage side is controlled, and the fuel gas flow rate supplied to each cylinder after being compressed by the gas compressor by the cylinder side gas amount adjusting valve is mixed with the supercharger inlet air. Supply air-fuel mixture to turbocharger Fuel gas amount and is mixed with supply air in the supply passage for each cylinder the air-fuel mixture can be freely controlled the ratio of the amount of the fuel gas supplied to each cylinder of the engine that.

As a result, the amount of fuel gas supplied to the supercharger is set to the limit of the amount of fuel gas that can avoid explosion after being compressed to high temperature and high pressure by the supercharger, and supplied to the supercharger. The fuel gas amount can be set to the maximum fuel gas amount that can avoid the explosion, and the explosion can be eliminated while maintaining the maximum fuel gas amount.
Further, the flow rate of the fuel gas on the cylinder side gas supply passage side that is compressed by the gas compressor and supplied to each cylinder can be reduced by an amount corresponding to the amount of fuel gas supplied to the supercharger side, so that the fuel gas to the cylinder side is compressed. The power of the gas compressor can be reduced, and the gas compressor can be reduced in size and capacity.
In particular, when using low calorie gas such as coal mine methane gas (gas with low calorific value), a large amount of fuel gas is required to obtain the required engine output. By setting the maximum fuel gas flow rate to the limit that can avoid explosion after compression to high temperature and high pressure by the supercharger, the fuel gas flow rate compressed by the gas compressor and supplied to each cylinder is set to the supercharger. By being able to reduce the fuel gas flow rate to the side, the power reduction effect of the gas compressor is further increased.

In this invention, preferably, an air supply pressure sensor for detecting an air supply pressure of the engine, an air supply temperature sensor for detecting an air supply temperature of the engine, and a fuel gas flowing through the supercharger side gas supply passage A fuel gas flow meter for detecting the flow rate of the fuel gas, and the gas amount controller includes a supply air pressure detection value from the supply air pressure sensor, a supply air temperature detection value from the supply air temperature sensor, and the fuel gas Calculate the fuel gas concentration in the air-fuel mixture supplied to the supercharger based on the detected value of the fuel gas flow rate from the flow meter, and compare the calculated value of the fuel gas concentration with the set value of the combustible lower limit gas concentration And calculating the opening degree of the supercharger side gas amount adjustment valve so that the fuel gas concentration is not more than the set value of the lower flammability limit gas concentration, and setting the supercharger side gas amount adjustment valve to the opening degree. Control.
In the case where the fuel gas is composed of coal mine methane gas, the gas amount controller controls the supercharger side so as to maintain the methane gas concentration in the air-fuel mixture at 5% or less, which is the flammable lower limit gas concentration. It is good to comprise so that the opening degree of a gas quantity adjustment valve may be controlled.

  According to this invention, in the gas amount controller, the actual fuel gas concentration is calculated using the detected values of the engine air supply pressure, the air supply temperature, and the fuel gas flow rate, and the actual fuel gas concentration and the combustible lower limit are calculated. Compared with the set value of gas concentration (concentration of 5% or less for coal mine methane gas), the supercharger side gas so that the amount of fuel gas to the supercharger side gas supply passage is kept below the combustible lower limit gas concentration. Since the opening of the volume control valve is controlled, the amount of fuel gas to the gas supply passage on the turbocharger is always accurately adjusted to the limit of the amount of fuel gas that can avoid explosion after being compressed to high temperature and high pressure by the turbocharger. Can hold.

Further, the present invention provides a supercharger side gas supply passage connected to the fuel gas passage to a supercharger inlet air passage to an air inlet of the supercharger, an air outlet of the supercharger, and each of the engine Fuel that is connected to a cylinder-side gas supply passage that is connected to an air supply passage for each cylinder between the cylinder and that is provided with a gas compressor that compresses the fuel gas, and flows through the supercharger-side gas supply passage The gas is mixed with the supercharger inlet air and this mixture is supplied to the supercharger, and the fuel gas flowing through the cylinder side gas supply passage is branched for each cylinder to supply the gas in the supply passage for each cylinder. The supercharger side gas is configured to be mixed with air and supplied to each cylinder of the engine, and in the supercharger side gas supply passage, a gas flow rate in the supercharger side gas supply passage is adjusted. An amount adjustment valve is provided, and the cylinder side gas supply The road provided cylinder-side gas amount adjusting valve for adjusting the gas flow rates of the cylinder-side gas supply passage for each cylinder,
The opening degree of the supercharger-side gas amount adjusting valve was controlled, and the fuel gas concentration in the air-fuel mixture for supplying the fuel gas amount to the supercharger-side gas supply passage to the supercharger was set. In addition to the above invention with a gas amount controller that adjusts to keep below the lower flammable gas concentration,
An exhaust bypass passage that bypasses the exhaust turbine of the exhaust turbocharger and is connected to an exhaust outlet pipe, an exhaust bypass valve that opens and closes the exhaust bypass passage, and an air-fuel mixture amount to the engine An air-fuel ratio controller for controlling the opening degree of the exhaust bypass valve so as to be an amount is provided.

According to this invention, as described above, the amount of fuel gas to the supercharger-side gas supply passage is always accurately adjusted to the limit of the amount of fuel gas that can avoid explosion after being compressed to high temperature and high pressure by the supercharger. The fuel gas flow rate that is held and compressed by the gas compressor and supplied to each cylinder is accurately maintained at a flow rate that is reduced by an amount corresponding to the fuel gas flow rate to the turbocharger, so that the turbocharger can be heated to high temperature and high pressure. In addition to suppressing the power of the gas compressor while avoiding an explosion after compression, the required engine output can be obtained.
Even if the intake air temperature of the turbocharger changes due to seasonal changes, etc., and the amount of air sucked into the turbocharger changes and the air-fuel mixture changes, the air-fuel ratio controller opens the exhaust bypass valve. By controlling the degree, it is possible to operate the engine while maintaining the air excess ratio of the air-fuel mixture supplied to each cylinder of the engine substantially constant.

According to the present invention, the fuel gas passage is divided into two fuel gases: a supercharger side gas supply passage connected to the supercharger inlet air passage and a cylinder side gas supply passage connected to the air supply passage for each cylinder. Branches to the supply system, controls the fuel gas flow rate on the turbocharger side gas supply passage side by the supercharger side gas amount adjustment valve, and supplies it to each cylinder after being compressed by the gas compressor by the cylinder side gas amount adjustment valve By controlling the fuel gas flow rate, the mixture is mixed with the supercharger inlet air and the mixture is mixed with the amount of fuel gas supplied to the supercharger and the supply air in the supply passage for each cylinder. The ratio of the fuel gas supplied to each cylinder of the engine can be freely controlled, and the maximum amount of fuel gas that can avoid explosion after compression of the fuel gas supplied to the supercharger by the supercharger By setting the amount Possible to completely eliminate the explosion holds mow maximum amount of the fuel gas.
In addition, the fuel gas flow rate on the cylinder side gas supply passage side that is compressed by the gas compressor and supplied to each cylinder can be reduced by the amount corresponding to the amount of fuel gas supplied to the turbocharger side, so the fuel gas to the cylinder side is compressed. The power of the gas compressor can be reduced, and the gas compressor can be reduced in size and capacity.

  Further, according to the present invention, in addition to the above-described effects, the intake air temperature of the exhaust turbocharger changes due to a change in season, etc., whereby the amount of air sucked into the turbocharger changes and the air-fuel mixture amount to the engine Even when the air-fuel ratio changes, it is possible to keep the excess air ratio of the air-fuel mixture supplied to each cylinder of the engine almost constant by operating the engine by controlling the opening of the exhaust bypass valve with the air-fuel ratio controller A synergistic effect is obtained.

  Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this example are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.

FIG. 1 is an overall configuration diagram of a gas supply apparatus for a gas engine according to an embodiment of the present invention. In FIG. 1, 1 is an engine (gas engine), 4 is a cylinder head of the engine 1, 13 is a generator directly connected to the engine 1, 14 is a flywheel, 7 is an exhaust turbine 7a and compressor 7b. It is a feeder. 3 is an air supply branch pipe connected to the air supply inlet of each cylinder head 4, 2 is an air supply pipe connecting the air supply outlet of the compressor 7 b and each air supply branch pipe 3, and 9 is the air supply pipe 2. It is a supply air cooler which cools the supply air which flows through.
5 is an exhaust pipe connected to the exhaust outlet of each cylinder head, 6 is an exhaust collecting pipe connected to each exhaust pipe 5, and 110 is for exhausting exhaust gas from the exhaust gas outlet of the exhaust turbine 3a. An exhaust outlet pipe.

An exhaust bypass pipe 11 is branched from the exhaust turbine 7a inlet side of the exhaust collecting pipe 6 to bypass the exhaust turbine 7a and is connected to an exhaust outlet pipe 110 on the outlet side of the exhaust turbine 7a. An exhaust bypass valve 12 changes the passage area of the exhaust bypass pipe 11.
10a is a supercharger inlet air passage for introducing air from the outside to the compressor 7b of the supercharger 7, and 10 is a mixer installed in the supercharger inlet air passage 10a. Reference numeral 21 denotes a gas supply pipe into which fuel gas is introduced from a fuel gas tank (not shown) that contains fuel gas, and a supercharger side gas supply pipe 211 and a cylinder side gas supply pipe 212 are branched from the gas supply pipe 21. ing.
The supercharger side gas supply pipe 211 is connected to the mixer 10 installed in the supercharger inlet air passage 10a. Further, the cylinder side gas supply pipe 212 is branched for each cylinder in the middle and becomes a gas supply branch pipe 213 and is connected to each of the air supply branch pipes 3.

  A gas compressor 18 is installed in the cylinder side gas supply pipe 212 and compresses the fuel gas flowing through the cylinder side gas supply pipe 212. 19 is a supercharger-side gas amount adjusting valve that is installed in the supercharger-side gas supply pipe 211 and controls the passage area of the supercharger-side gas supply pipe 211, that is, the fuel gas flow rate, and 20 is each gas supply branch. It is a cylinder side gas amount adjusting valve that is installed in the pipe 213 and controls the passage area of each gas supply branch pipe 213, that is, the fuel gas flow rate.

15 is a rotation speed sensor for detecting the engine rotation speed, 013 is a load detector for detecting the load of the generator 13, that is, an engine load, 17 is a supply pressure sensor for detecting the supply pressure in the supply pipe 2, and 16 is It is a supply air temperature sensor for detecting a supply air temperature in the supply pipe 2. Reference numeral 021 denotes a fuel gas flow meter for detecting the flow rate of the fuel gas flowing through the supercharger side gas supply pipe 211.
Reference numeral 24 denotes a rotational speed controller, 23 denotes an air-fuel ratio controller, 22 denotes a gas amount controller, and the detected value of the engine rotational speed from the rotational speed sensor 15 is sent to the rotational speed controller 24, the air-fuel ratio controller 23, and the gas amount controller 22. The detected value of the engine load from the load detector 013 is input to the air-fuel ratio controller 23, and the detected value of the supply air pressure from the supply air pressure sensor 17 is input to the air-fuel ratio controller 23 and the gas amount controller 22. The detected value of the supply air temperature from the supply air temperature sensor 16 is input to the air-fuel ratio controller 23 and the gas amount controller 22, and the detected value of the fuel gas flow rate from the fuel gas flow meter 021 is input to the gas amount controller 22. Entered.

The rotational speed controller 24 is a normal electronic governor and controls the opening degree of each cylinder-side gas amount adjusting valve 20 so that the target rotational speed is set based on the detected value of the engine rotational speed from the rotational speed sensor 15. Control.
The air-fuel ratio controller 23 detects the detected value of the engine speed from the engine speed sensor 15, the detected value of the engine load from the load detector 013, the detected value of the supply air pressure from the supply air pressure sensor 17, and the supply air Based on the detected value of the supply air temperature from the temperature sensor 16, the opening degree of the exhaust bypass valve 12 is controlled by means described later. The gas amount controller 22 converts the detected value of the engine speed from the engine speed sensor 15, the detected value of the supplied air pressure from the supplied air pressure sensor 17, and the detected value of the supplied air temperature from the supplied air temperature sensor 16. Based on this, the opening degree of the supercharger side gas amount adjusting valve 19 is controlled by means to be described later.

During operation of the gas engine, the fuel gas from the gas supply pipe 21 is branched in the middle of the gas supply pipe 21. Then, one of the branched fuel gases is introduced into the mixer 10 through the supercharger-side gas supply pipe 211, and is mixed with air from the supercharger air inlet passage 10a in the mixer 10, and this mixture is It is introduced into the compressor 7b of the supercharger 7. The air-fuel mixture pressurized to a high temperature and high pressure by the compressor 7b is cooled by the air supply cooler 9 and lowered in temperature, and flows into the air supply branch pipe 3 of each cylinder through the air supply pipe 2.
The other of the branched fuel gas enters the cylinder side gas supply pipe 212, is compressed by the gas compressor 18, passes through each gas supply branch pipe 213 of each cylinder, enters each of the supply air branch pipes 3, and then supplies the supply gas. It is mixed into the air-fuel mixture in the air branch pipe 3 and sent into each cylinder.

The exhaust gases from the cylinders of the engine 1 are merged in the exhaust collecting pipe 6 through the exhaust pipe 5 and supplied to the exhaust turbine 7a of the supercharger 7 to drive the exhaust turbine 7a, and then the exhaust outlet pipe It is discharged to the outside through 110.
Further, when the exhaust bypass valve 12 is opened by a control operation signal as will be described later from the air-fuel ratio controller 23, a part of the exhaust gas in the exhaust collecting pipe 6 bypasses the exhaust turbine 7a and becomes an exhaust outlet pipe. 110 is discharged.

Next, the operation of the combustion control apparatus for the gas engine will be described with reference to FIGS.
FIG. 2 is a control block diagram of the gas amount controller in the embodiment. In FIG. 2, the detected value of the supply pressure from the supply pressure sensor 17, the detected value of the supply air temperature from the supply air temperature sensor 16, and the detected value of the engine speed from the rotation speed sensor 15 are the gas amount controller. 22 is input to the air supply amount calculation unit 221. The supply air amount calculation unit 221 calculates the actual air amount using the detection value of the supply air pressure, the detection value of the supply air temperature, and the detection value of the engine speed, and inputs the actual air amount to the gas concentration calculation unit 222. .
In the gas concentration calculation unit 222, based on the detected value of the fuel gas flow rate from the fuel gas flow meter 021 and the calculated value of the actual air amount from the supply air amount calculation unit 221, Is calculated and input to the gas concentration deviation calculator 224.

Reference numeral 223 denotes a combustible lower limit gas concentration setting unit in which the combustible lower limit gas concentration is set for each fuel gas. That is, as shown in FIG. 4, the relationship between the gas pressure and the flammable lower limit concentration is set for each fuel gas. In FIG. 4, the lower concentration side than each lower limit line, that is, each lower limit. The left side of the line represents the gas concentration at which no gas explosion occurs as indicated by numbers 1 to 11 in the figure. The flammable lower limit gas concentration of the coal mine methane gas used in this example is set so that the methane concentration in the air-fuel mixture is less than 5%.
In the gas concentration deviation calculation unit 224, the calculated value of the fuel gas is matched with the combustible lower limit gas concentration set in the combustible lower limit gas concentration setting unit 223, and the concentration deviation is compared. From this, a correction value for the flow rate of the fuel gas supplied to the mixer 10 through the supercharger-side gas supply pipe 211 is calculated, and the concentration of the fuel gas in the mixture is less than or equal to the lower flammability limit gas concentration based on the correction value ( The degree of opening of the supercharger side gas amount adjusting valve 19 that maintains the combustible lower limit gas concentration of the coal mine methane gas is 5% or less is calculated and output to the supercharger side gas amount adjusting valve 19.
As a result, the supercharger-side gas amount adjusting valve 19 keeps the flow rate of the fuel gas fed into the mixer 10 at such a flow rate that the concentration of the fuel gas in the air-fuel mixture is kept below the flammable lower limit gas concentration.

Therefore, according to this embodiment, the gas amount controller 22 calculates the actual fuel gas concentration using the detected values of the engine supply air pressure, the supply air temperature, the engine speed, and the fuel gas flow rate. The fuel gas concentration to the supercharger side gas supply passage 211 is less than or equal to the lower flammability limit gas concentration. Since the opening degree of the supercharger-side gas amount adjusting valve 19 is controlled so as to hold the fuel gas flow rate to the supercharger-side gas supply passage 211, the explosion after compression to a high temperature and high pressure by the supercharger 7 It is possible to always accurately maintain the maximum flow rate of the fuel gas that can be avoided, and to keep the maximum amount of fuel gas and to eliminate the explosion.
At the same time, the gas supply pipe 21 branches to the cylinder side gas supply pipe 212 side and is compressed by the gas compressor 18, and passes through each gas supply branch pipe 213 and each air supply branch pipe 3 of each cylinder. The flow rate of the fuel gas fed in can be reduced by a considerable amount corresponding to the flow rate of the fuel gas to the supercharger side gas supply pipe 211, the power of the gas compressor 18 can be reduced, and the gas compressor 18 can be reduced in size and capacity. Thereby, the power of the gas compressor 18 can be reduced and the required engine output can be obtained while avoiding the explosion of the fuel gas after being compressed to a high temperature and high pressure by the supercharger 7.

  In particular, in the case of a low calorie gas (a gas having a low calorific value) such as coal mine methane gas used in this embodiment, a large amount of fuel gas is required to obtain a required engine output. By setting the fuel gas flow rate supplied to the 7 side to the maximum fuel gas flow rate that can avoid an explosion after being compressed to a high temperature and high pressure by the supercharger 7, the cylinder is compressed by the gas compressor 18 The fuel gas flow rate to be supplied to the turbocharger 7 can be reduced by an amount corresponding to the fuel gas flow rate on the supercharger 7 side, so that the power reduction effect of the gas compressor 18 becomes greater.

  Further, according to this embodiment, the gas amount controller 22 calculates the actual fuel gas concentration using the detected values of the engine supply air pressure, supply air temperature, engine speed, and fuel gas flow rate. The fuel gas concentration of the fuel is compared with the set value of the lower flammability limit gas concentration, and the amount of fuel gas to the supercharger side gas supply pipe 211 is maintained. Since the opening of the supercharger-side gas amount adjusting valve 19 is controlled so that the fuel gas amount to the supercharger-side gas supply pipe 211 is compressed to a high temperature and high pressure by the supercharger 7, an explosion is avoided. It is possible to maintain the fuel gas flow rate as close as possible at all times accurately.

In the present embodiment, the air supply amount is calculated from the temperature sensor and the pressure sensor. However, the method for calculating the air supply amount is not limited to this, and for example, the air supply amount is calculated from the temperature sensor and the flow meter. The amount may be calculated.
In this embodiment, the detection value from the rotation speed sensor is input to the gas amount controller 22. However, in a gas engine that is always operated at the rated rotation speed, the gas volume controller 22 has a rated rotation speed setting unit. And the rated rotational speed set value may be input in advance.
Further, in the present embodiment, the input from each sensor is configured to be calculated in the gas amount controller 22, but a map corresponding to the supply air pressure / temperature and the fuel gas flow rate is prepared in advance, and this may be read out. Good.

Next, FIG. 3 is a control block diagram of the air-fuel ratio controller in the embodiment. In FIG. 3, the detected value of the supply air pressure from the supply air pressure sensor 17, the detected value of the intake air temperature from the intake air temperature sensor 16, and the detected value of the engine speed from the engine speed sensor 15 are the air-fuel ratio controller. 23 is input to the air supply amount calculation unit 221. The supply air amount calculation unit 221 calculates the actual air amount using the detection value of the supply air pressure, the detection value of the supply air temperature, and the detection value of the engine speed, and inputs the actual air amount to the mixture amount calculation unit 231. To do.
Further, the detected value of the engine load from the load detector 013 is input to the target mixture amount calculation unit 232 and the mixture amount calculation unit 231 of the air-fuel ratio controller 23. In the air-fuel mixture amount calculation unit 231, an actual air-fuel amount is calculated from the fuel gas amount corresponding to the detected value of the engine load and the actual air amount, and is input to the air-fuel mixture amount deviation calculation unit 233.

Further, the target mixture amount calculation unit 232 calculates the target value (target mixture amount) of the mixture amount based on the appropriate excess air ratio corresponding to the detected value of the engine load, and the mixture amount deviation calculation unit. Input to 233.
The mixture amount deviation calculating unit 233 calculates the mixture amount deviation between the actual mixture amount from the mixture amount calculating unit 231 and the target value (target mixture amount) of the mixture amount. Input to the air supply amount adjustment amount calculation unit 234.
In the air supply amount adjustment amount calculation unit 234, the adjustment amount of the air supply amount at the supercharger outlet is calculated based on the mixture amount deviation and is input to the exhaust bypass valve opening degree calculation unit 235.

Here, in such an engine 1, when the opening of the exhaust bypass valve 12 is increased to increase the amount of exhaust gas bypassing the exhaust turbine 7a to reduce the output of the exhaust turbine 7a, the supply air pressure decreases, When the opening degree of the exhaust bypass valve 12 is reduced and the amount of exhaust gas bypassing the exhaust turbine 7a is decreased to increase the output of the exhaust turbine 7a, the supply air pressure increases.
Therefore, in the exhaust bypass valve opening degree calculation unit 235, the opening degree of the exhaust bypass valve 126 corresponding to the adjustment value of the supply air pressure is calculated from the relationship between the supply air pressure and the opening degree of the exhaust bypass valve 12 as described above. The exhaust bypass valve opening adjustment amount is output to an exhaust bypass valve drive device (not shown) that drives the exhaust bypass valve 12, and the opening degree of the exhaust bypass valve 12 is set to the adjustment amount. adjust.
As a result, the supply air pressure is changed so that the actual air amount of the engine becomes the required air amount, the actual air amount matches the required air amount, and the engine 1 has a constant excess air adapted to the fuel gas amount. Driven at a rate.

As in the case of the gas amount controller, in this embodiment, the air supply amount is calculated from the temperature sensor and the pressure sensor. However, the method of calculating the air supply amount is not limited to this. The air supply amount may be calculated from a sensor and a flow meter.
In this embodiment, the detection value from the rotation speed sensor is input to the air-fuel ratio controller 23. However, in the gas engine that is always operated at the rated rotation speed, the air-fuel ratio controller 23 includes a rated rotation speed setting unit. And the rated rotational speed set value may be input in advance.
Further, in this embodiment, the input from each sensor is calculated in the air-fuel ratio controller 23, but a map corresponding to the supply air pressure / temperature and the engine load may be prepared in advance and read out. .

Therefore, according to this embodiment, as described above, the amount of fuel gas to the supercharger-side gas supply pipe 211 is set to a fuel gas flow rate of a limit that can avoid an explosion after being compressed to a high temperature and high pressure by the supercharger 7. The fuel gas flow rate supplied to each cylinder after being compressed by the gas compressor 18 is accurately maintained at a flow rate reduced by an amount corresponding to the fuel gas flow rate to the supercharger. In addition to being able to suppress the power of the gas compressor 18 while avoiding an explosion after compression to a high temperature and high pressure, the required engine output can be obtained.
Even when the intake air temperature of the supercharger 7 changes due to a seasonal change or the like, and the amount of air sucked into the supercharger 7 thereby changes and the amount of air-fuel mixture into the engine 1 changes, the air-fuel ratio controller 23 By controlling the opening degree of the exhaust bypass valve 12, it is possible to operate the engine 1 while keeping the excess air ratio of the air-fuel mixture supplied to each cylinder of the engine 1 substantially constant.

  According to the present invention, the fuel gas supply system for mixing the fuel gas with the supercharger inlet air and supplying the mixture to the supercharger, and the fuel gas supply system for supplying the fuel gas into the air supply passage for each cylinder, In a gas engine equipped with a gas engine, the possibility of explosion of fuel gas at the outlet of the turbocharger can be eliminated, and even when using low calorie gas (gas with low calorific value) fuel, The power of the gas compressor for fuel gas compression can be reduced, and a gas engine in which the gas compressor is reduced in size and capacity can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram of the gas supply apparatus of the gas engine of the gas engine which concerns on the Example of this invention. It is a control block diagram of the gas amount controller in the embodiment. It is a control block diagram of the air-fuel ratio controller in the embodiment. It is explanatory drawing of the combustible lower limit gas concentration of fuel gas.

Explanation of symbols

1 Engine (gas engine)
DESCRIPTION OF SYMBOLS 2 Supply pipe 3 Supply air branch pipe 6 Exhaust collecting pipe 7 Supercharger 7a Exhaust turbine 7b Compressor 11 Exhaust bypass pipe 12 Exhaust bypass valve 10a Supercharger inlet air passage 13 Generator 013 Load detector 15 Rotation speed sensor 16 Supply air Temperature sensor 17 Supply air pressure sensor 18 Gas compressor 19 Supercharger side gas amount adjustment valve 20 Cylinder side gas amount adjustment valve 21 Gas supply pipe 22 Gas amount controller 23 Air-fuel ratio controller 24 Speed controller 021 Fuel gas flow meter 211 Supercharger Machine side gas supply pipe 212 Cylinder side gas supply pipe

Claims (7)

  In a gas supply apparatus for a gas engine, which includes an exhaust turbocharger, mixes fuel gas and air supplied through a fuel gas passage, and supplies the mixture into a cylinder for ignition and combustion. A cylinder-side gas supply that is connected to a supercharger-side gas supply passage connected to the air inlet of the supercharger and a gas compressor that is connected to a supply passage downstream of the supercharger and compresses the fuel gas. The fuel gas that branches into the passage and flows through the supercharger side gas supply passage is mixed with the supercharger inlet air, and this mixture is supplied to the supercharger and flows through the cylinder side gas supply passage. The fuel gas to be mixed is mixed with the supply air in the supply passage downstream of the supercharger, and this mixture is supplied to each cylinder of the engine. Adjusting the gas flow rate in the machine side gas supply passage A turbocharger-side gas amount adjusting valve, a cylinder-side gas amount adjusting valve for adjusting a gas flow rate in the cylinder-side gas supply passage is provided in the cylinder-side gas supply passage, and the supercharger-side gas amount adjusting valve The fuel gas concentration in the air-fuel mixture supplied to the supercharger is kept below the combustible lower limit gas concentration so that the amount of fuel gas to the supercharger side gas supply passage is controlled. A gas supply device for a gas engine, comprising a gas amount controller for adjustment.   In a gas supply apparatus for a gas engine, which includes an exhaust turbocharger, mixes fuel gas and air supplied through a fuel gas passage, and supplies the mixture into a cylinder for ignition and combustion. A supercharger-side gas supply passage connected to the air inlet of the supercharger, and a cylinder-side gas supply passage connected to an air supply passage for each cylinder and provided with a gas compressor for compressing the fuel gas. The fuel gas which branches and mixes the fuel gas flowing through the supercharger side gas supply passage with the supercharger inlet air and supplies this mixture to the supercharger and also flows through the cylinder side gas supply passage Is mixed with the supply air in the supply passage for each cylinder, and this mixture is supplied to each cylinder of the engine. The supercharger side gas supply passage is connected to the supercharger side gas supply passage. Adjust gas flow A cylinder-side gas amount adjusting valve is provided for each cylinder, and a cylinder-side gas amount adjusting valve for adjusting a gas flow rate of each cylinder-side gas supply passage is provided for each cylinder. By controlling the opening of the gas amount adjustment valve, the fuel gas amount to the supercharger-side gas supply passage is maintained so that the fuel gas concentration in the mixture supplied to the supercharger is lower than the lower flammable gas concentration A gas supply device for a gas engine, characterized in that a gas amount controller for adjusting the gas amount is provided.   A fuel pressure sensor that detects a charge pressure of the engine, a fuel temperature sensor that detects a charge temperature of the engine, and a fuel that detects a flow rate of fuel gas flowing through the supercharger-side gas supply passage A gas flow rate controller, and the gas amount controller includes a supply air pressure detection value from the supply air pressure sensor, a supply air temperature detection value from the supply air temperature sensor, and a fuel gas flow rate from the fuel gas flow meter. The fuel gas concentration in the air-fuel mixture supplied to the supercharger is calculated based on the detected value of the fuel gas, the calculated value of the fuel gas concentration is compared with the set value of the combustible lower limit gas concentration, and the fuel gas concentration Is configured to calculate the opening degree of the supercharger side gas amount adjusting valve so that the flammable lower limit gas concentration is less than the set value of the combustible lower limit gas, and to control the supercharger side gas amount adjusting valve to the opening degree. Either of claims 1 or 2 Gas supply device for a gas engine according to section.   The fuel gas is composed of coal mine methane gas, and the gas amount controller controls the supercharger-side gas amount adjustment valve so as to maintain the methane gas concentration in the mixture at 5% or less, which is a lower flammable limit gas concentration. The gas supply device for a gas engine according to any one of claims 1 and 2, wherein the opening is controlled.   An exhaust bypass passage that bypasses the exhaust turbine of the exhaust turbocharger and is connected to an exhaust outlet pipe, an exhaust bypass valve that opens and closes the exhaust bypass passage, and an air-fuel mixture amount to the engine The gas supply device for a gas engine according to claim 1 or 2, further comprising an air-fuel ratio controller that controls the opening degree of the exhaust bypass valve so as to be an amount.   A gas engine comprising the gas supply device according to any one of claims 1 to 5. In a method for operating a gas engine in which fuel gas and air supplied through a fuel gas passage are mixed and the mixture is supplied into a cylinder and ignited and combusted, a part of the fuel gas is supplied to an air inlet of a supercharger. The fuel gas is mixed with the supercharger inlet air through the connected supercharger side gas supply passage, and this mixture is supplied to the supercharger. The fuel gas is connected to the air supply passage for each cylinder and the fuel gas is supplied to the supercharger. Through a cylinder-side gas supply passage in which a gas compressor that compresses the gas is mixed with the supply air in the supply passage for each cylinder, and this mixture is supplied to each cylinder of the engine,
Mixing for controlling the opening degree of the supercharger side gas amount adjusting valve provided in the supercharger side gas supply passage to supply the fuel gas amount to the supercharger side gas supply passage to the supercharger A method for operating a gas engine, characterized in that the fuel gas concentration in the air is adjusted so as to be kept below a flammable lower limit gas concentration.

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