JP2006009701A - Operation method of gas engine, and gas engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operation method of a gas engine and the gas engine, capable of suppressing a detrimental effect due to exhaust gas at starting, and shortening the starting time. <P>SOLUTION: Each cylinder 2 of the gas engine 1 is provided with a main combustion chamber 3 formed between a cylinder liner 21 and a piston 22 and a pre-combustion chamber 4 formed adjacent to the main combustion chamber 3. An ignition plug 31 for igniting mixture gas F of fuel gas and air is arranged in the main combustion chamber 3. A liquid fuel injection nozzle 42 for injecting liquid fuel P and a glow plug 41 for heating and self-igniting liqued fuel are arranged in a pre-combustion chamber 4. At starting the gas engine 1, the ignition plug 31 and a glow plug 41 are used together to make combustion operation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gas engine operating method and a gas engine configured to perform a combustion operation using a fuel gas such as natural gas.

  A pilot ignition type gas engine that is operated by combustion using a gaseous fuel such as natural gas (fuel gas) is a main combustion chamber that is supplied with a lean gas mixture of gaseous fuel and air. In order to assist, a precombustion chamber into which self-ignitable liquid fuel such as light oil and heavy oil is injected is formed adjacently. In the pre-combustion chamber, liquid fuel is burned to generate a pre-combustion flame. The pre-combustion flame enters the main combustion chamber, and the lean gas mixture is combusted in the main combustion chamber.

By the way, pilot ignition type gas engines are classified into a spark plug type and a glow plug type depending on the ignition method at the time of starting the gas engine.
That is, in the spark plug system, a spark plug capable of spark discharge is arranged in the main combustion chamber toward the main combustion chamber. When the gas engine is started, the air ratio of the gas mixture supplied to the main combustion chamber is reduced (the gas mixture is made gas rich), and the gas rich gas mixture is ignited by the spark plug. .

When the rotational speed of the gas engine rises and the temperature in the main combustion chamber and the precombustion chamber rises, the air ratio of the gas mixture is made steady and lean, and the liquid fuel is injected into the precombustion chamber. To do. As a result, the pre-combustion flame enters from the pre-combustion chamber toward the main combustion chamber, and the lean gas mixture in the main combustion chamber is combusted.
An example of such a spark plug type gas engine is disclosed in Patent Document 1.

On the other hand, in the glow plug system, a glow plug capable of generating heat is disposed in the pre-combustion chamber. At the time of starting the gas engine, the liquid fuel is injected toward the heated glow plug, so that the liquid fuel can be self-ignited even when the temperature in the precombustion chamber is low. Further, at the time of starting, in order to promote the self-ignition of the liquid fuel, the injection amount of the liquid fuel is increased and the injection start timing of the liquid fuel is advanced.
Examples of such glow plug type gas engines include those disclosed in Patent Documents 2 and 3.

However, the spark plug method and the glow plug method both have advantages but disadvantages.
That is, in the spark plug system, when the gas engine is started, liquid fuel is not used and combustion is performed only in the main combustion chamber, so that the temperature in the precombustion chamber is difficult to rise, and the operating state of the gas engine shifts to a steady state. It will take longer to do.

Further, when the gas engine is started, it is necessary to reduce the air ratio of the gas mixture, and the gas mixture in a gas-rich state is burned in the main combustion chamber. Therefore, the combustion temperature in each combustion chamber becomes high, the injection nozzle for injecting liquid fuel into the precombustion chamber is heated, coking or the like occurs, and there is a possibility of clogging the injection nozzle.
In addition, since the temperature of the exhaust gas after combustion is high, there is a possibility that durability of an exhaust pipe or the like through which the exhaust gas passes is lowered.

  On the other hand, in the glow plug system, it is necessary to increase the injection amount of the liquid fuel when starting the gas engine, and there is a possibility that part of the liquid fuel is exhausted in an unburned state. Furthermore, the mechanism of the injection device for adjusting the injection amount of the liquid fuel becomes complicated, and it becomes necessary to perform complicated control such as an early start timing of the injection of liquid fuel. Furthermore, there are cases where ignition is not possible reliably when the temperature of the gas engine is low.

JP 2000-64838 A JP-A-9-72269 JP-A-7-158448

  The present invention has been made in view of such conventional problems, and is intended to provide a gas engine operating method and a gas engine that can suppress the adverse effects of exhaust gas at the time of starting and can shorten the starting time. It is what.

According to a first aspect of the present invention, there is provided a main combustion chamber formed between a cylinder liner and a piston, to which a gas mixture of fuel gas and air is supplied, and a liquid fuel connected to the main combustion chamber and capable of self-ignition. In a method for operating a gas engine having a plurality of cylinders having a pre-combustion chamber to be supplied,
The main combustion chamber is provided with a spark plug for sparking the gas mixture supplied to the main combustion chamber and igniting the gas mixture, while the pre-combustion chamber has a spark plug. Is provided with a liquid fuel injection nozzle for injecting the liquid fuel, and a glow plug for heating and self-igniting the liquid fuel injected from the liquid fuel injection nozzle,
In the gas engine operation method, the ignition plug and the glow plug are used together at the time of starting the gas engine.

In the operation method of the gas engine of the present invention, pre-combustion is performed using a self-ignitable liquid fuel such as light oil or heavy oil. It blows out and burns.
And this invention can have both advantages by providing the spark plug which can ignite the said gas mixture, and the glow plug which accelerates | stimulates the self-ignition of the said liquid fuel.

That is, when the gas engine is started, the gas mixture flows into the precombustion chamber from the main combustion chamber. Then, the glow plug generates heat, and liquid fuel is injected from the liquid fuel injection nozzle toward the generated glow plug. The injected liquid fuel is self-ignited and combusted with the gas mixture in the precombustion chamber.
Thus, pre-combustion is performed in the pre-combustion chamber, and the pre-combustion flame resulting from this pre-combustion enters the main combustion chamber from the pre-combustion chamber.

On the other hand, when the gas engine is started, in the main combustion chamber, spark discharge is performed from the spark plug, and the gas mixture supplied into the main combustion chamber is ignited.
In the main combustion chamber, the gas mixture is burned by the ignition by the spark plug and the precombustion flame entering from the precombustion chamber, and main combustion is performed.
Thus, at the time of starting the gas engine, by using both the spark plug and the glow plug, both the gas mixture in the main combustion chamber and the liquid fuel in the precombustion chamber can be directly ignited and combusted. .

Therefore, when the gas engine is started, the gas mixture can be reliably ignited in the main combustion chamber even if the precombustion flame entering from the precombustion chamber is reduced.
Further, in the pre-combustion chamber, the liquid fuel can be burned by receiving heat from the combustion in the main combustion chamber. This eliminates the need to increase the amount of liquid fuel injected from the liquid fuel injection nozzle when starting the gas engine.

  Therefore, the injection amount of the liquid fuel at the time of starting can be made almost the same as the injection amount of the liquid fuel at the normal time when the gas engine is sufficiently heated. Therefore, at the time of starting the gas engine, it is possible to prevent a part of the liquid fuel from being exhausted in an unburned state, and the mechanism and control of the liquid fuel injection device including the liquid fuel injection nozzle can be simplified. Can be.

Further, the pre-combustion in the pre-combustion chamber can quickly raise the temperature in the pre-combustion chamber and the main combustion chamber, and shortens the period during which the gas mixture is ignited using the spark plug at the start of the gas engine. be able to.
Therefore, it is possible to shorten the period during which the excess air ratio of the gas mixture is reduced in order to ignite the gas mixture by the spark plug, and to suppress the rise in the temperature of the exhaust gas after combustion and to allow the exhaust gas to pass through The durability of the pipe and the like can be improved. Moreover, it is possible to suppress clogging of the liquid fuel injection nozzle or the like due to a high combustion temperature due to a small excess air ratio.

Furthermore, by using both the spark plug and the glow plug, the time until the operating state of the gas engine shifts to the steady state can be shortened.
Therefore, according to the operation method of the gas engine of the present invention, it is possible to suppress an adverse effect due to the exhaust gas at the time of starting, and to shorten the starting time of the gas engine.

According to a second aspect of the present invention, there is provided a main combustion chamber formed between a cylinder liner and a piston, to which a gas mixture of fuel gas and air is supplied, and a liquid fuel connected to the main combustion chamber and capable of self-ignition. In a gas engine having a plurality of cylinders with a pre-combustion chamber to be supplied,
The main combustion chamber is provided with a spark plug for spark discharge of the gas mixture supplied into the main combustion chamber and igniting the gas mixture,
The pre-combustion chamber is provided with a liquid fuel injection nozzle for injecting the liquid fuel and a glow plug for heating and self-igniting the liquid fuel injected from the liquid fuel injection nozzle. (Claim 6).

The gas engine of the present invention performs pre-combustion using a self-ignitable liquid fuel such as light oil or heavy oil, and the pre-combustion flame by this pre-combustion is injected into a gas mixture with a fuel gas such as natural gas. This is a pilot ignition type gas engine that performs combustion.
Therefore, similarly to the above-described invention, even with the gas engine of the present invention, adverse effects due to the exhaust gas at the start can be suppressed, and the start time of the gas engine can be shortened.

A preferred embodiment of the present invention described above will be described.
In the first and second inventions, the fuel gas may be various gaseous fuels such as city gas mainly composed of natural gas and LPG.
The liquid fuel may be various self-ignitable liquid fuels such as light oil and heavy oil.
The time when the gas engine is started refers to a stage (period) until the rotational speed of the gas engine reaches a target steady rotational speed.

  In the first aspect of the invention, at the time of starting the gas engine, until the output state of the gas engine or the load state on the gas engine reaches a predetermined rising state before reaching the steady state, Combustion operation is performed using both the spark plug and the glow plug. When the output state of the gas engine or the load state to the gas engine reaches the rising state, the combustion operation is performed using only the glow plug. (Claim 2).

  In the second aspect of the invention, the gas engine has a control device that controls a combustion operation thereof, and the control device is configured so that an output state of the gas engine or a load state to the gas engine is Until a predetermined rising state is reached before reaching a steady state, the plug combined combustion stage in which the combustion operation is performed by using the spark plug and the glow plug together, the output state of the gas engine or the state to the gas engine When the load state reaches the rising state, it is preferable that the plug single combustion stage in which the combustion operation is performed using only the glow plug is sequentially performed.

  In these cases, the ignition plug and the glow plug are used together to start the gas engine, and the stage of using the ignition plug is made shorter than the stage of using the glow plug. Therefore, by using both plugs together, the temperature of the main combustion chamber and the precombustion chamber can be quickly increased until the output state of the gas engine or the load state on the gas engine reaches the rising state.

  Further, when the output state of the gas engine or the load state on the gas engine reaches the rising state, the gas engine can be stably operated only by using the glow plug. At this time, by using only the glow plug, it is possible to shorten the stage of reducing the excess air ratio of the gas mixture in order to use the spark plug.

The said steady state means the state which drives various loads stably with a gas engine.
Further, the output state of the gas engine can be observed by, for example, the rotational speed of the gas engine. The steady state can be, for example, when the rotational speed of the gas engine is a steady rotational speed, and the rising state is, for example, when the rotational speed of the gas engine is a predetermined idle rotational speed. be able to. Further, the steady rotation speed can be set to 810 to 990 rpm, for example. Further, the idle rotation speed can be set to 40 to 60% of the steady rotation speed, for example, 360 to 540 rpm.

  Moreover, the load state to the said gas engine can be observed by the output state of the load which operate | moves using a gas engine, for example. And as a load which operates using a gas engine, there is a dynamo, for example. Further, the steady state can be, for example, when the output of the generator is a rated output value, and the rising state is, for example, a predetermined output value in which the output of the generator is smaller than the rated output value. It can be when.

In the first invention, after the output state of the gas engine or the load state to the gas engine becomes the steady state, the combustion operation is performed without using the spark plug and the glow plug. (Claim 3).
In the second aspect of the invention, the control device does not use the spark plug and the glow plug after the output state of the gas engine or the load state to the gas engine becomes the steady state. It is preferable that the stationary combustion stage in which the combustion operation is performed is performed.

After the output state of the gas engine or the load state on the gas engine reaches the steady state, the temperature in the pre-combustion chamber and the main combustion chamber has risen sufficiently. Pre-combustion can be performed without using it. After the steady state is reached, stable combustion can be performed without using both plugs in the main combustion chamber and the pre-combustion chamber.
The gas engine can be operated using a glow plug for a while after the output state of the gas engine or the load state on the gas engine becomes a steady state.

In the first aspect of the invention, when the spark plug is used, the excess air ratio of the gas mixture supplied to the main combustion chamber is set to be higher than the steady air excess ratio during steady operation of the gas engine. It is preferable to make it smaller (claim 4).
In the second aspect of the invention, in the plug combined combustion stage, the control device uses the excess air ratio of the gas mixture supplied to the main combustion chamber as the steady air during steady operation of the gas engine. It is preferable to make it smaller than the excess rate (Claim 9). In these cases, the gas mixture can be easily ignited by the spark plug.

Also, the excess air ratio of the gas mixture when spark is discharged from the spark plug (the air ratio, that is, the value obtained by dividing the actual amount of air actually supplied by the amount of air required to completely burn the fuel gas) Can be about 1.0. Moreover, the said steady air excess rate can be 1.8-2.0.
The term “steady operation of the gas engine” means that the output state of the gas engine or the load state on the gas engine is in a steady state.

In the first aspect of the invention, the injection set amount of the liquid fuel to be injected from the liquid fuel injection nozzle is determined by the output state of the gas engine or the load state to the gas engine after the gas engine is started. It is preferable not to change until the steady state is reached (Claim 5).
In the second aspect of the invention, the control device sets an injection set amount of the liquid fuel to be injected from the liquid fuel injection nozzle, an output state of the gas engine after starting the gas engine, or the gas engine. It is preferable that the load state is not changed until the steady state is reached (claim 10).

  In these cases, the injection control of the liquid fuel injection nozzle by the control device can be made extremely easy at the start and steady state of the gas engine. Further, it is not necessary to adjust the injection amount of the liquid fuel, and the structure of the injection device including the liquid fuel injection nozzle can be simplified.

Embodiments of the gas engine and the operating method thereof according to the present invention will be described below with reference to the drawings.
As shown in FIGS. 1 and 2, the gas engine 1 of this example performs pre-combustion using a liquid fuel P that can be self-ignited such as light oil or heavy oil, and the pre-combustion flame H by this pre-combustion is converted into natural gas or the like. This is a pilot ignition type gas engine that performs main combustion using an ignition source of the gas mixture F by the fuel gas.

The gas engine 1 includes a plurality of cylinders 2 each having an intake valve 32 that sucks the gas mixture F into the main combustion chamber 3 and an exhaust valve 33 that exhausts the exhaust gas G after combustion from the main combustion chamber 3. This is a multi-cylinder gas engine. Each cylinder 2 includes a main combustion chamber 3 formed between the cylinder liner 21 and the piston 22, and a precombustion chamber 4 formed adjacent to the main combustion chamber 3.
The main combustion chamber 3 is configured to be supplied with a gas mixture F of fuel gas and air. The main combustion chamber 3 is sparked by the gas mixture F supplied into the main combustion chamber 3. A spark plug 31 is disposed for discharging and igniting the gas mixture F.

The pre-combustion chamber 4 is configured to be supplied with self-ignitable liquid fuel P. The pre-combustion chamber 4 is injected with a liquid fuel injection nozzle 42 for injecting the liquid fuel P, and the liquid fuel injection nozzle. A glow plug 41 for heating and self-igniting the liquid fuel P injected from 42 is disposed.
As shown in FIGS. 3 and 4, when the gas engine 1 is started in the combustion operation, the ignition operation is performed using the spark plug 31 and the glow plug 41 together.
This will be described in detail below.

The gas engine 1 of this example has a control device (not shown) for controlling the combustion operation. The control device is configured to perform an ignition operation of the spark plug 31, a heat generation operation of the glow plug 41, an adjustment of the air ratio (excess air ratio) of the gas mixture F, an injection operation of the liquid fuel injection nozzle 42, and the like. .
Further, the gas engine 1 is provided with a rotational speed detection means (not shown) for detecting the rotational speed, and the control device determines the rotational speed of the gas engine 1 detected by the rotational speed detection means. It is configured to receive.

The gas engine 1 of this example is a stationary four-cycle reciprocating engine, and performs a combustion operation by repeating the steps of intake, compression, combustion, and exhaust.
As shown in FIGS. 1 and 2, the pre-combustion chamber 4 in each cylinder 2 of the present example is formed in a pre-combustion connection portion 25 disposed above the cylinder liner 21, and this pre-combustion is performed. A liquid fuel pipe 251 for guiding the liquid fuel P to the precombustion chamber 4 is disposed in the connecting portion 25. A liquid fuel injection nozzle 42 is formed at the tip of the liquid fuel pipe 251, and the liquid fuel injection nozzle 42 is configured to inject liquid fuel P in response to a command from the control device.

  In addition, a communication port 43 that connects the precombustion chamber 4 and the main combustion chamber 3 is formed at the lower end of the precombustion chamber 4. Further, the precombustion chamber 4 of the present example is formed at a substantially central portion above the cylinder liner 21. Further, the glow plug 41 of this example is disposed at a position facing the liquid fuel injection nozzle 42, and the ignition plug 31 of this example is disposed in the vicinity of the outer peripheral side end of the main combustion chamber 3. Yes.

  Each cylinder 2 of the gas engine 1 is connected to an intake manifold (not shown) via an intake pipe 23, and a mixer (not shown) that mixes fuel gas and air in front of the intake manifold. Is connected. The mixer is configured to adjust the mixing ratio of the fuel gas and air in response to a command from the control device.

Next, the operation method of the gas engine 1 that performs the combustion operation using the control device and the operation effect thereof will be described in detail.
As shown in FIGS. 3 and 4, the control device performs combustion control of the gas engine 1 by sequentially performing the following plug combined combustion stage, plug single body combustion stage, and steady combustion stage.
That is, when the start control of the gas engine 1 is performed, the control device adjusts the mixture ratio of the fuel gas and air in the mixer, thereby adjusting the excess air ratio of the gas mixture F sucked into the main combustion chamber 3. Is set to be smaller than the steady excess air ratio A2 during steady operation of the gas engine 1 (step S101 in FIG. 3). In this example, the excess air ratio A1 when starting the gas engine 1 is about 1.0, and the steady air excess ratio A2 during steady operation of the gas engine 1 is 1.8 to 2.0.

  Further, the control device sets the injection setting amount of the liquid fuel P to be injected from the liquid fuel injection nozzle 42 to a predetermined value (S102). Then, the control device starts the gas engine 1 until the rotational speed (output state) of the gas engine 1 reaches the steady rotational speed (steady state) N2, and the piston 22 in each cylinder 2 approaches the top dead center. The injection set amount of the liquid fuel P to be injected at the time is always maintained at a predetermined value.

  Next, when the gas engine 1 is started, the control device starts the combustion operation using the spark plug 31 and the glow plug 41 in each cylinder 2 together as the plug combined combustion stage (S103). The control device starts the heat generation of the glow plug 41 when the gas engine 1 is started.

  Then, in the plug combined combustion stage, as shown in FIG. 2, when the piston 22 goes to the bottom dead center, each intake valve 32 is opened in the main combustion chamber 3 in each cylinder 2 as an intake process of the gas engine 1. A gas mixture F of fuel gas and air is sucked from each intake pipe 23.

Next, as shown in FIG. 1, when the piston 22 goes to top dead center, the gas mixture F in the main combustion chamber 3 is compressed as a compression process of the gas engine 1, and the gas mixture F in the main combustion chamber 3 is compressed. Part of the gas further flows into the precombustion chamber 4. When the piston 22 approaches top dead center, as a combustion process of the gas engine 1, the liquid fuel P is injected from the liquid fuel injection nozzle 42 toward the glow plug 41 that has generated heat. At this time, the liquid fuel P injected into the precombustion chamber 4 is self-ignited and combusted with the gas mixture F in the precombustion chamber 4.
Thus, pre-combustion is performed in the pre-combustion chamber 4, and the pre-combustion flame H resulting from this pre-combustion enters the main combustion chamber 3 from the pre-combustion chamber 4 through the communication port 43.

  On the other hand, the excess air ratio of the gas mixture F sucked into the main combustion chamber 3 is a starting excess air ratio A1 smaller than the steady excess air ratio A2, and each cylinder 2 has gas richness from the intake manifold. In this state, the gas mixture F is sucked. When the piston 22 approaches the top dead center, the gas mixture F in the main combustion chamber 3 is compressed, and the control device generates a spark discharge from the spark plug 31. At this time, the compressed gas mixture F is ignited, and in the main combustion chamber 3, the gas mixture F is burned by the ignition by the spark plug 31 and the precombustion flame H entering from the precombustion chamber 4. The main combustion takes place.

  After that, when the piston 22 again goes to the bottom dead center by this main combustion and then goes to the top dead center again, as an exhaust process, the exhaust valves 33 in the cylinders 2 are opened and the exhaust pipes 24 are connected. Exhaust gas G after combustion is exhausted from the main combustion chamber 3. Thereafter, the combustion operation of the gas engine 1 is performed by repeating the intake, compression, combustion, and exhaust processes.

Thus, in the plug combined combustion stage at the start of the gas engine 1, by using the spark plug 31 and the glow plug 41 in combination, either the gas mixture F in the main combustion chamber 3 or the liquid fuel P in the precombustion chamber 4 is selected. Can be directly ignited and burned.
Therefore, when the gas engine 1 is started, the gas mixture F can be reliably ignited in the main combustion chamber 3 even if the precombustion flame H entering from the precombustion chamber 4 is reduced.
Further, in the precombustion chamber 4, the liquid fuel P can be burned by receiving heat from the combustion in the main combustion chamber 3. This eliminates the need to increase the amount of liquid fuel P injected from the liquid fuel injection nozzle 42 when the gas engine 1 is started.

  Therefore, the injection amount of the liquid fuel P when the gas engine 1 is started can be made almost the same as the injection amount of the liquid fuel P during the steady operation when the gas engine 1 is sufficiently heated. Therefore, when the gas engine 1 is started, it is possible to prevent a part of the liquid fuel P from being exhausted in an unburned state, and the mechanism of the liquid fuel P injection device including the liquid fuel injection nozzle 42. And control can be simplified.

Next, the control device maintains the rotational speed of the gas engine 1 at the idle rotational speed N1 for a predetermined time (S104 in FIG. 3). When the rotational speed of the gas engine 1 is shifted to the steady rotational speed N2, the control device stops using the spark plug 31 (S105), adjusts the gas supply amount of the mixer, and mixes the gas mixture. The target value of the excess air ratio of F is changed from the excess air ratio A1 to the steady excess air ratio A2 (S106).
Thus, after that, in the plug single combustion stage, the combustion operation is performed using only the glow plug 41 without using the spark plug 31 (S107).

  In the plug single combustion stage, the combustion of the liquid fuel P and the gas mixture F in the precombustion chamber 4 using the glow plug 41 is the same as in the plug combined combustion stage. The difference from the plug combined combustion stage is that only the pre-combustion flame H formed by the pre-combustion in the pre-combustion chamber 4 is used for the gas mixture F sucked into the main combustion chamber 3 in the plug single-combustion stage. And burn it.

Further, the combustion operation of the gas engine 1 is performed after the plug combined combustion stage, that is, the ignition plug 31 and the glow plug 41 are used together, and the temperatures in the pre-combustion chamber 4 and the main combustion chamber 3 are rapidly increased. To rise. Thereby, the rotation speed of the gas engine 1 can be raised rapidly.
Then, after the rotational speed of the gas engine 1 exceeds the idle rotational speed N1, the use of the spark plug 31 is stopped, and the target value of the excess air ratio of the gas mixture F is changed from the starting excess air ratio A1 to the steady excess air. Change to rate A2. Thereafter, a lean gas mixture F can be supplied into the main combustion chamber 3.

As a result, the period during which the excess air ratio of the gas mixture F is reduced can be shortened, and the exhaust gas G exhausted from the exhaust valve 33 of each cylinder 2 as an exhaust process of the gas engine 1 after combustion is performed. Temperature rise can be suppressed. As a result, the durability of the exhaust pipe 24 through which the exhaust gas G passes can be improved.
Moreover, since the period during which the excess air ratio of the gas mixture F is reduced can be shortened, the occurrence of coking and the like can be suppressed, and clogging of the liquid fuel injection nozzle 42 and the like can be suppressed.

  Further, in the plug single combustion stage, since the temperatures in the main combustion chamber 3 and the precombustion chamber 4 have already increased, even if the injection amount of the liquid fuel P is kept small, The gas mixture F in the main combustion chamber 3 can be easily burned by the precombustion flame H formed by the precombustion.

Next, in the plug single combustion stage, the control device determines whether or not the rotational speed of the gas engine 1 has reached a predetermined steady rotational speed N2 (S108 in FIG. 3).
Then, the plug single combustion stage is continued for a predetermined period after the rotational speed of the gas engine 1 reaches the predetermined steady rotational speed N2.
Thereafter, the control device stops the use of the glow plug 41 as a steady combustion stage (S109) and performs the combustion operation of the gas engine 1 without using the spark plug 31 and the glow plug 41 (S110).

As described above, the control device maintains the injection set amount of the liquid fuel P to be injected from the liquid fuel injection nozzle 42 from the start of the gas engine 1 until the steady rotation speed is reached.
Therefore, the control device does not need to perform the adjustment control of the injection amount of the liquid fuel P injected from the liquid fuel injection nozzle 42, and the injection control of the liquid fuel P can be performed very easily. Further, since it is not necessary to adjust the injection amount of the liquid fuel P, the configuration of the control device for injecting the liquid fuel P from the liquid fuel injection nozzle 42 can be greatly simplified.

In addition, since the gas engine 1 and its operating method of this example are started using the spark plug 31 and the glow plug 41 in combination, the time until the operating state shifts to the steady state can be shortened. .
Therefore, according to the gas engine 1 and its operating method of the present example, the adverse effect of the exhaust gas G due to combustion at the start on each part can be suppressed, and the start time of the gas engine 1 can be shortened.

(Performance confirmation)
In this example, the excellent performance by the gas engine 1 and its operation method was confirmed. For comparison, the performance of a conventional spark plug type gas engine and a glow plug type gas engine was also confirmed.
That is, FIG. 4 schematically shows the combustion operation of the gas engine 1, FIG. 5 schematically shows the combustion operation of a spark plug type gas engine, and FIG. 6 shows the combustion operation of a glow plug type gas engine. In each figure, the horizontal axis represents the elapsed time since the start of the gas engine, and the vertical axis represents the rotation speed of the gas engine, the excess air ratio of the gas mixture, and the liquid fuel injection amount. It is a graph which shows the change of the driving | running state of.

  As shown in FIG. 4, in the gas engine 1 of this example, the operation of the gas engine 1 is performed using the spark plug 31 and the glow plug 41 as a plug combined combustion stage until the rotational speed reaches the idle rotational speed N1. I do. Further, even when the rotational speed of the gas engine 1 is maintained at the idle rotational speed N1, the operation of the gas engine 1 is performed using both plugs 31 and 41 together. In the plug combined combustion stage, the excess air ratio of the gas mixture F is set to the excess start air ratio A1.

Next, when the rotational speed of the gas engine 1 is shifted to the steady rotational speed N2, the target value of the excess air ratio of the gas mixture F is changed to the steady excess air ratio A2 and only the glow plug 41 is used as a single plug combustion stage. The gas engine 1 is operated using Further, the glow plug 41 is used for a while after the rotational speed of the gas engine 1 reaches the steady rotational speed N2.
Thereafter, the gas engine 1 is operated without using the plugs 31 and 41 as a steady combustion stage.

  On the other hand, as shown in FIG. 5, in a spark plug type gas engine, the gas engine is started using only the spark plug. Therefore, it can be seen that the time for maintaining the excess air ratio at the excess start air ratio A1 is long, and that the time required for the rotation speed of the gas engine to reach the steady rotation speed N2 is also long.

  As shown in FIG. 6, in the glow plug type gas engine, the gas engine is started using only the glow plug. Therefore, at the time of start-up, it is necessary to set the liquid fuel injection set amount to a large value, and it is understood that the time required for the rotation speed of the gas engine to reach the steady rotation speed N2 is long.

  Compared to these conventional gas engines, the gas engine 1 of the present example can shorten the time for maintaining the excess air ratio at the excess start air ratio A1, and the rotation speed of the gas engine 1 can be reduced to the steady rotation speed N2. It can be seen that the time required to reach can be shortened. Further, it was confirmed that the gas engine 1 can be stably operated without changing the injection set amount of the liquid fuel P.

Explanatory drawing which shows the gas engine of the state which burns in the main combustion chamber and the precombustion chamber in an Example. Explanatory drawing which shows the gas engine of the state which inhales a gas mixture into the main combustion chamber and the precombustion chamber in an Example. The flowchart which shows the combustion operation | movement of the gas engine in an Example. The graph which shows the combustion operation | movement of the gas engine in an Example. The graph which shows the combustion operation | movement of the conventional spark plug type gas engine in an Example. The graph which shows the combustion operation | movement of the conventional glow plug system gas engine in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas engine 2 Cylinder 21 Cylinder liner 22 Piston 3 Main combustion chamber 31 Spark plug 4 Precombustion chamber 41 Glow plug 42 Liquid fuel injection nozzle F Gas mixture P Liquid fuel Fp Precombustion mixture H Precombustion flame G Exhaust gas

Claims (10)

A main combustion chamber formed between a cylinder liner and a piston and supplied with a gas mixture of fuel gas and air, and a precombustion chamber connected to the main combustion chamber and supplied with a self-ignitable liquid fuel In a method of operating a gas engine having a plurality of cylinders with
The main combustion chamber is provided with a spark plug for sparking the gas mixture supplied to the main combustion chamber and igniting the gas mixture, while the pre-combustion chamber has a spark plug. Is provided with a liquid fuel injection nozzle for injecting the liquid fuel, and a glow plug for heating and self-igniting the liquid fuel injected from the liquid fuel injection nozzle,
A method for operating a gas engine, wherein the ignition plug and the glow plug are used in combination when the gas engine is started. In claim 1, at the time of starting the gas engine, until the output state of the gas engine or the load state to the gas engine reaches a predetermined rising state before reaching a steady state, the spark plug and the Combustion operation in combination with a glow plug,
A method for operating a gas engine, wherein when the output state of the gas engine or the load state on the gas engine reaches the rising state, a combustion operation is performed using only the glow plug.   3. The combustion operation according to claim 2, wherein the combustion operation is performed without using the spark plug and the glow plug after the output state of the gas engine or the load state to the gas engine becomes the steady state. How to operate the gas engine.   In Claim 2, when using the said spark plug, the excess air ratio of the said gas mixture supplied to the said main combustion chamber is made smaller than the steady excess air ratio at the time of the steady operation of the said gas engine. Gas engine operation method.   The injection set amount of the liquid fuel injected from the liquid fuel injection nozzle according to any one of claims 2 to 4, wherein an output state of the gas engine or a load on the gas engine after the gas engine is started A method for operating a gas engine, wherein the state is not changed until the state reaches the steady state. A main combustion chamber formed between a cylinder liner and a piston and supplied with a gas mixture of fuel gas and air, and a precombustion chamber connected to the main combustion chamber and supplied with a self-ignitable liquid fuel In a gas engine having a plurality of cylinders with
The main combustion chamber is provided with a spark plug for spark discharge of the gas mixture supplied into the main combustion chamber and igniting the gas mixture,
The pre-combustion chamber is provided with a liquid fuel injection nozzle for injecting the liquid fuel and a glow plug for heating and self-igniting the liquid fuel injected from the liquid fuel injection nozzle. A gas engine characterized by In Claim 6, the said gas engine has a control apparatus which controls the combustion operation,
The control device uses both the spark plug and the glow plug for combustion until the output state of the gas engine or the load state on the gas engine reaches a predetermined rising state before reaching the steady state. A plug-combustion stage of operation,
When the output state of the gas engine or the load state on the gas engine reaches the rising state, the plug single combustion stage for performing a combustion operation using only the glow plug is sequentially performed. Characteristic gas engine.   8. The control device according to claim 7, wherein the control device performs a combustion operation without using the spark plug and the glow plug after the output state of the gas engine or the load state to the gas engine becomes the steady state. A gas engine configured to perform a steady combustion stage.   8. The control device according to claim 7, wherein, in the plug combined combustion stage, the excess air ratio of the gas mixture supplied to the main combustion chamber is smaller than a steady air excess ratio during steady operation of the gas engine. A gas engine characterized by being configured to perform.   The control device according to any one of claims 6 to 9, wherein the control device sets an injection set amount of the liquid fuel to be injected from the liquid fuel injection nozzle after an output state of the gas engine or the gas engine is started. A gas engine configured not to change until a load state to the gas engine reaches the steady state.

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