JP3608775B2 - Gas engine air supply method and air supply device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air supply method for a gas engine having a precombustion chamber in addition to a main combustion chamber, and an air supply device for the gas engine that implements the air supply method.
[0002]
[Prior art]
Gas engines shown in FIGS. 8 and 9 are known (Japanese Patent Laid-Open No. 10-110635). The gas engine E has a plurality of cylinders 1 in which a main combustion chamber 1a and a precombustion chamber 1b are formed. A fuel gas main pipe 3 is connected to each main combustion chamber 1 a via a balancing valve 4, and an air supply pipe 6 is connected via a branch pipe 7. The main combustion chamber 1a and the precombustion chamber 1b communicate with each other.
[0003]
The fuel gas main pipe 3 has gas pressure control valves 9 and 10 and is connected to a fuel gas supply source 11. The gas pressure control valve 9 is controlled by a governor 12. The bypass pipe 14 communicating between the front and rear of the gas pressure control valve 10 is provided with a needle valve 15 as pressure adjustment means.
[0004]
A pilot gas main pipe 17 is connected to each precombustion chamber 1b. The pilot gas main pipe 17 is connected to an intermediate portion of the fuel gas main pipe 3 via a pilot unit (adjustment unit) 21 having three pressure regulators 18, 19, and 20.
[0005]
Reference numeral 23 is a blower which is operated by an exhaust turbine 24 to send air into the supply pipe 6. Reference numeral 25 denotes a generator operated by the gas engine E.
[0006]
The gas engine E is generally called a pre-combustion chamber type lean combustion gas engine, and the pre-combustion chamber 1b has a role of providing ignition energy for burning the lean air-fuel mixture in the main combustion chamber 1a, and has low NOx. At the same time, increase power generation efficiency.
[0007]
[Problems to be solved by the invention]
However, the gas engine E having the above-described configuration has a problem to be solved in that the mixed state in the pre-combustion chamber becomes excessive due to sudden load application or load operation (hereinafter simply referred to as load application), and misfire is likely to occur.
[0008]
FIG. 10 is a diagram showing the excess air ratio between the main combustion chamber 1a and the precombustion chamber 1b when a load is applied to a pre-combustion chamber type lean combustion gas engine rated at 835 kw / 1000 rpm. In normal ascending tests marked with ○, x, and △ in the figure, it took 166 seconds, 55 seconds, and 58 seconds, respectively, and from normal no-load (load factor 0%) to constant load (load factor) without misfiring 100%), but in the rapid load operation (● and ▲) in which the load application operation was attempted earlier than these, it was found that misfire engine stalls occurred at a load factor of around 40%.
[0009]
The above fuel excess occurs for the following reasons.
That is, when the load is applied, the engine speed decreases. The governor 12 detects this decrease in the rotational speed, and moves the gas pressure control valve 9 to increase the amount of fuel gas introduced into the main combustion chamber 1a. This operation is performed in several tens of μs.
[0010]
On the other hand, the combustion air is sucked into a blower 23 that is operated by an exhaust turbine 24 that uses exhaust gas energy from the combustion chambers 1a and 1b as a power source, and is compressed by a compressor impeller 50 (see FIG. 11). To be pumped. The time constant of the exhaust turbine 24 is approximately several tens of seconds depending on the capacity of the turbine, but is much longer than the time during which the governor 12 operates the gas pressure control valve 9 to feed the fuel gas.
The shortage of combustion air due to such a difference in control time constant is the reason for the excess fuel.
[0011]
For this reason, the conventional gas engine is limited in the instantaneous load input amount and the load operation speed from no load to the rated load. This limit value is lower than that of a theoretical mixed gas combustion gas engine that does not have a pre-combustion chamber (generally a type with a small engine having a cylinder diameter of less than 200 mm), and takes advantage of the characteristics of a pre-combustion chamber type lean combustion gas engine. I can't.
[0012]
By the way, if a pre-combustion chamber type lean combustion gas engine is used as a system for cogeneration during normal times and a machine for disaster prevention in an emergency, equipment costs are reduced.
However, due to the above restrictions, the initial input load factor (about 20 to 30% with respect to the rating) is low for disaster prevention, and there is a brake on the realization of the dual-purpose machine.
[0013]
An object of the present invention is to provide an air supply method and an air supply device for a gas engine that enable rapid load application.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, the main combustion chamber is connected to the fuel gas main pipe and the air supply pipe which is fed with air by a blower operated by an exhaust turbine. In the gas engine to which the pilot gas main pipe is communicated, in addition to the combustion air supplied from the supply pipe to the main combustion chamber when the load is applied to the gas engine, both the main combustion chamber and the pre-combustion chamber or The supplementary air is supplied to either one, and the supply of the supplementary air is stopped when the gas engine reaches a predetermined rotational speed.
[0015]
In this means, excess fuel is prevented by the supplementary air supplied from the time-limited air supplement source, and the mixing ratio of the fuel gas and the air is maintained appropriately.
[0016]
According to a second aspect of the present invention, in the gas engine in which the fuel gas main pipe and the air supply pipe are respectively connected to the main combustion chamber and the pilot gas main pipe is connected to the pre-combustion chamber, a time-limited air replenishment source is electromagnetically connected to the pilot gas main pipe. It was set as the structure connected by the replenishment pipe | tube opened and closed by a valve.
[0017]
In this means, the solenoid valve is opened at the same time as when the load is turned on, and the compressed air of the timed air replenishment source is caused to flow into the pilot gas main pipe, and is sent together with the pilot gas (pilot fuel gas) through the pilot gas main pipe. Excessive fuel in the precombustion chamber and the main combustion chamber communicating with the precombustion chamber is prevented by the supplementary air sent from the timed air replenishment source to the precombustion chamber, and the mixing ratio of the fuel gas and air is maintained appropriately.
The pilot gas main pipe is preferably provided with a mixer for mixing the pilot gas and the supplementary air from the time-limited air supplement source. The replenishment pipe is usually provided with a pressure regulator.
[0018]
In the gas engine air supply device according to claim 2, the replenishment pipe can be connected to the pilot gas main pipe via the pilot unit (claim 3).
Also in this configuration, the supplementary air from the time-limited air supplement source is sent to the precombustion chamber through the pilot unit and the pilot gas main pipe to prevent excessive fuel due to air shortage. In this configuration, the degree of freedom on the piping of the supplementary pipe is increased.
[0019]
Gas invention of claim 4, in the main combustion chamber, where the fuel gas main pipe, and a supply pipe fed air are contacted respectively by a blower that is actuated by the exhaust turbine, the pilot gas main pipe is contacted precombustion chamber In the engine, the time supply air replenishment source is connected to the air supply pipe by a replenishment pipe that is opened and closed by a solenoid valve.
[0020]
In this means, the solenoid valve is opened at the same time as when the load is applied, and the replenishing air of the timed air replenishment source is caused to flow through the air supply pipe, and is sent into the main combustion chamber together with the air flowing through the air supply pipe. Also in this case, the supplementary air sent from the time-limited air supplement source to the main combustion chamber prevents excessive fuel in the main combustion chamber and the precombustion chamber communicated therewith, and the mixing ratio is maintained appropriately. The replenishment pipe is usually provided with a pressure regulator.
[0021]
According to a fourth aspect of the present invention, there is provided an air supply device for a gas engine, wherein the replenishment pipe can be connected to the air supply pipe via a blower operated by an exhaust turbine.
In this configuration, the replenishing air from the timed air replenishment source is sent to the main combustion chamber through the blower and the air supply pipe to prevent excessive fuel. In this case, in an engine equipped with an exhaust turbine with a jet assist function (FIG. 11), supplementary air is sent into a space communicating with the jet assist insert hole, and air is blown to the compressor impeller through the jet assist insert hole. Thus, the responsiveness of the exhaust turbine can be improved and the amount of air fed into the main combustion chamber can be increased. Also in this structure, the freedom degree on the piping of a supplementary pipe becomes wide.
[0022]
According to a sixth aspect of the present invention, in the gas engine in which the fuel gas main pipe and the air supply pipe are respectively connected to the main combustion chamber and the pilot gas main pipe is connected to the pre-combustion chamber, the branch pipe in which the air supply pipe is connected to the main combustion chamber. The replenishing air supply valve that is operated by the pilot air distributed by the pilot distributing valve and is opened is connected to the replenishing air supply valve, and the timed air replenishing source is connected to the replenishing pipe that is opened and closed by a solenoid valve. The configuration was as follows.
[0023]
In this means, when the electromagnetic valve is opened simultaneously with the loading of the load, the pilot air is sent to the supplementary air supply valve at the timing determined by the pilot distribution valve to open it. Therefore, the replenishing air from the timed air replenishing source is fed into the main combustion chamber together with the air flowing through the branch pipe, and the fuel ratio in the main combustion chamber and the precombustion chamber is prevented from being excessive and the mixing ratio is maintained appropriately. The pilot distribution valve is usually provided on the camshaft in the same manner as the supply cam, exhaust cam or fuel cam.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows a first embodiment of a gas engine air supply device according to the present invention. In this figure, reference numeral 31 denotes a mixer, which is provided on the upstream side (fuel gas supply source 11 side) of the pilot unit 21 of the pilot gas main pipe 17.
[0025]
A timed air replenishment source 32 such as an air tank is connected to the mixer 31 via a replenishment pipe 33, and the compressed replenishment air in the timed air replenishment source 32 is mixed with fuel gas in the mixer 31 and pre-combusted through the pilot gas main pipe 17. It can supply to the chamber 1b. The replenishment pipe 33 includes an electromagnetic valve 35 that opens and closes the replenishment pipe 33, a pressure regulator 36 that adjusts the pressure of the replenishment air flowing through the replenishment pipe 33 to a predetermined pressure, and a replenishment air that flows from the timed air replenishment source 32 toward the mixer 31. A check valve 37 that frees the flow and prevents the reverse flow is provided, and on the upstream side of the mixer 31 in the pilot gas main pipe 17, fuel gas (pilot gas) from the fuel gas supply source 11 toward the mixer 31. Is provided with a check valve 38 that frees the flow and prevents the reverse flow. The check valves 37 and 38 have a check pressure set depending on the structure of the mixer 31 and the required air amount, but may be omitted.
[0026]
1 is the same as that of the conventional gas engine E of FIGS. 8 and 9, and therefore, the same members and the like are denoted by the same reference numerals and the description thereof is omitted. Is omitted.
[0027]
In the gas engine air supply device of FIG. 1, a command is output simultaneously with the loading of the gas engine E, the electromagnetic valve 35 is opened, and the replenishing air of the timed air replenishing source 32 is adjusted by the pressure regulator 36 (and the flow rate). To the mixer 31 and supplied to each precombustion chamber 1b through the pilot gas main pipe 17 together with the fuel gas. For this reason, the time constant of the exhaust turbine 24 (see FIG. 9) is the same as the conventional one in several tens of seconds, and even if the supply of air from the blower 23 is delayed, the supply of supplementary air from the timed air supply source 32 is instantaneous. The fuel gas does not become excessive, and the misfire engine stall due to this is prevented. In this way, when the rotational speed per unit time of the gas engine E rises to a predetermined rotational speed, the electromagnetic valve 35 is closed to stop the supply of supplementary air, and a normal operation is started. A part of the supplementary air supplied to the precombustion chamber 1b enters the main combustion chamber 1a and burns the fuel gas.
[0028]
FIG. 2 (a) shows the conventional rotational speed change when the load is applied, and (b) shows the rotational speed change when the present invention is implemented. As is clear from the comparison between (A) and (B), the amount of rotation decrease so far that caused a misfire engine stall is reduced by the implementation of the present invention and does not lead to a misfire engine stall. Good results were obtained.
[0029]
FIG. 3 shows a second embodiment of the present invention. The replenishment pipe 33 is directly connected in a branched state to the downstream side of the pilot unit 21 of the pilot gas main pipe 17. Other configurations are the same as those of the gas engine air supply device of FIG.
[0030]
In the case of this gas engine air supply device, the supplementary air from the timed air replenishment source 32 is not forcibly mixed with the pilot gas by the mixer 31 (FIG. 1). There is no change in being supplied to the combustion chamber 1b.
Therefore, the same effect as the gas engine air supply device of FIG. 1 can be expected in this gas engine air supply device.
[0031]
3 may be connected to the pilot gas main pipe 17 through a mixer as in FIG. Also, the mixer 31 of FIG. 1 can be omitted.
The replenishment pipe 33 can be connected to the intermediate part of the pilot gas main pipe 17 in the pilot unit 21 directly or via a mixer to obtain the same effects as described above.
[0032]
FIG. 4 shows a third embodiment of the present invention. The refilling pipe 33 is connected to the suction side of the blower 23 in a branched state. In the case of an engine equipped with an exhaust turbine with a jet assist function (FIG. 11), by blowing air to the compressor impeller 50 through the jet assist insert hole 51, the responsiveness of the exhaust turbine is improved and the intake air amount is increased. It can also be made. Other configurations are the same as those of the gas engine air supply device shown in FIGS.
[0033]
In this air supply device, the replenishment air from the time-limited air replenishment source 32 enters the blower 23, and directly or by utilizing the jet assist function in the exhaust turbine with the jet assist function, passes through the air supply pipe 6 to each main combustion chamber. 1a is sent into the precombustion chamber 1b to burn the fuel gas. Therefore, in this case as well, the mixing ratio of the fuel gas and air immediately after the loading of the load is maintained appropriately, and misfire engine stall due to excessive fuel is prevented.
[0034]
FIG. 5 shows a fourth embodiment of the present invention, and the replenishment pipe 33 is connected to an intermediate portion of the air supply pipe 6. Other configurations are the same as those of the gas engine air supply device shown in FIGS.
[0035]
In the case of this air supply device, the replenishment air of the time-limited air replenishment source 32 is sent from each main combustion chamber 1a to the precombustion chamber 1b together with the air sent from the blower 23 to burn the fuel gas. Therefore, also in this air supply device, the mixing ratio of the fuel gas and air is kept appropriate, and the misfire engine is prevented.
[0036]
FIGS. 6 and 7 show a fifth embodiment of the present invention. The refilling pipe 33 is connected to each main combustion chamber 1a via a refilling air supply valve 41 and a branch pipe 7 of the air supply pipe 6. FIG. ing. The replenishing air supply valve 41 is provided in the air supply manifold of the gas engine E in communication with each branch pipe 7. When the pilot air flows through the pilot pipe 42, the valve body 41a resists the elasticity of the return spring 41b. 7 is moved to the right in FIG. 7 so as to be opened away from the valve seat 41c.
[0037]
The pilot pipe 42 is connected to a pilot distribution valve 44 that is operated by a camshaft 43, and receives the compressed air of the time-limited air replenishment source 32 at a predetermined timing by the pilot distribution valve 44 to open the replenishment air supply valve 41. As is well known, the cam shaft 43 is provided with a fuel cam 46, an exhaust cam 47, and an air supply cam 48. Other configurations such as the solenoid valve 35 and the pressure regulator 36 are the same as those of the gas engine air supply device of FIGS.
[0038]
6 and 7, each supplementary air supply valve 41 is instantaneously opened at the timing set in the pilot distribution valve 44, and the supplementary air from the time-limited air supplement source 32 is combined with the combustion air of the blower 23. To the main combustion chambers 1a through the branch pipes 7.
Therefore, in this case as well, the gas engine E is prevented from misfire due to excessive fuel, and rises to a predetermined rotational speed quickly and reliably.
[0039]
【The invention's effect】
As described above, according to the present invention, it is possible to rapidly load the gas engine. Therefore, the gas engine can be used both as a cogeneration during normal times and a machine for disaster prevention in an emergency, and the equipment costs can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first embodiment of an air supply device for a gas engine according to the present invention.
FIG. 2 is a time diagram from loading to transition to normal operation.
FIG. 3 is a diagram showing a second embodiment of a gas engine air supply device according to the present invention.
FIG. 4 is a diagram showing a third embodiment of an air supply device for a gas engine according to the present invention.
FIG. 5 is a diagram showing a fourth embodiment of an air supply device for a gas engine according to the present invention.
FIG. 6 is a diagram showing a fifth embodiment of an air supply device for a gas engine according to the present invention.
FIG. 7 is a cross-sectional view showing an example of a supplementary air supply valve.
FIG. 8 is a view of a conventional gas engine air supply device.
9 is a diagram showing a relationship between a blower and an exhaust turbine of the gas engine air supply device of FIG. 8;
10 is a diagram showing an excess air ratio between the main combustion chamber and the pre-combustion chamber when the load is applied to the pre-combustion chamber-type lean combustion gas engine of FIG. 8. FIG.
FIG. 11 is a cross-sectional view of an exhaust turbine with a jet assist function.
[Explanation of symbols]
E Gas Engine 1 Cylinder 1a Main Combustion Chamber 1b Precombustion Chamber 3 Fuel Gas Main Pipe 6 Supply Air Pipe 7 Branch Pipe 17 Pilot Gas Main Pipe 21 Pilot Unit 23 Blower 24 Exhaust Turbine 31 Mixer 32 Timed Air Replenishment Source 33 Refill Pipe 35 Electromagnetic Valve 36 Pressure Regulator 41 Supplementary air supply valve 42 Pilot pipe 43 Cam shaft 44 Pilot distribution valve

Claims (6)

In the gas engine in which the main combustion chamber is connected to the fuel gas main pipe and the air supply pipe to which air is sent by the blower operated by the exhaust turbine, and the pilot gas main pipe is connected to the pre-combustion chamber, a load is applied to the gas engine. Sometimes, in addition to the combustion air supplied from the supply pipe to the main combustion chamber, supplementary air is supplied from the timed air supplement source to the main combustion chamber and / or the pre-combustion chamber, and the gas engine has a predetermined rotational speed. The supply method of the gas engine is characterized in that the supply of supplementary air is stopped when the pressure reaches the value. In a gas engine in which a fuel gas main pipe and an air supply pipe are connected to the main combustion chamber and a pilot gas main pipe is connected to the pre-combustion chamber, the pilot gas main pipe is provided with a replenishment pipe whose timed air replenishment source is opened and closed by a solenoid valve. A gas engine air supply device characterized by being connected. 3. A gas engine air supply device according to claim 2, wherein the replenishment pipe is connected to the pilot gas main pipe via a pilot unit. In a gas engine in which a fuel gas main pipe and an air supply pipe to which air is sent by a blower operated by an exhaust turbine are connected to the main combustion chamber, and a pilot gas main pipe is connected to the pre-combustion chamber, An air supply device for a gas engine, characterized in that the time-limited air supply source is connected by a supply pipe that is opened and closed by a solenoid valve. 5. A gas engine air supply device according to claim 4, wherein the replenishment pipe is connected to the air supply pipe via a blower operated by an exhaust turbine. In a gas engine in which a fuel gas main pipe and an air supply pipe are connected to the main combustion chamber, and a pilot gas main pipe is connected to the pre-combustion chamber, the gas is distributed to the branch pipe connected to the main combustion chamber by the pilot distribution valve. A replenishing air supply valve that is opened by being operated by pilot air is connected to the replenishing air supply valve, and a gas that is connected to the replenishing air supply valve by a replenishing pipe that is opened and closed by a solenoid valve. Engine air supply device.

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