WO2013061769A1

WO2013061769A1 - Gas engine, and gas heat pump device and cogeneration device that use gas engine

Info

Publication number: WO2013061769A1
Application number: PCT/JP2012/076121
Authority: WO
Inventors: 中園　徹; 大坪　弘幸; 宏年鬼原
Original assignee: ヤンマー株式会社
Priority date: 2011-10-25
Filing date: 2012-10-09
Publication date: 2013-05-02
Also published as: JP2013092083A

Abstract

Provided are: a gas engine a gas engine that is capable of smoothly switching between a stoichiometric operation and a lean operation; a gas heat pump device and a cogeneration device that use the gas engine; and a method for controlling the gas engine. The gas engine (1) carries out the stoichiometric operation during high loads, and the lean operation during low to medium loads, and a valve (21), which supplies a mixture of air and fuel gas to the engine (1), has a stoichiometric operating area (a) with a small opening, a lean operating area (b) with a large opening, and a switching operating area (c) therebetween, which are formed on a single proportional control valve, in such a manner as to enable the stoichiometric operation, switching from the stoichiometric operation to the lean operation, the lean operation, and switching from the lean operation to the stoichiometric operation.

Description

Gas engine and gas heat pump device and cogeneration device using gas engine

The present invention relates to a gas engine and a gas heat pump device and a cogeneration device using the gas engine.

Gas engines are known as driving sources for gas heat pump devices and cogeneration devices.

Conventionally, as such a gas engine, one that switches between stoichiometric operation and lean operation has been disclosed (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 2000-24465

However, when switching between stoichiometric operation and lean operation as in the conventional gas engine, the air to be controlled in lean operation with respect to the excess air ratio (λ = 1) of the theoretical air-fuel ratio to be controlled in stoichiometric operation. The excess ratio (λ = 1.4 to 1.6) has a wide control range, and the control accuracy of the two is greatly different, so the air-fuel ratio control valve for lean operation was able to shift from lean operation to stoichiometric operation. Even in the stoichiometric operation, the excess air ratio (λ = 1) of the stoichiometric air-fuel ratio cannot be controlled.

For this reason, it is conceivable to use an air-fuel ratio control valve set for stoichiometric operation, but in this case, since the control accuracy is set for stoichiometric operation, the excess air ratio cannot be increased to the region of lean operation. There wasn't.

In addition, it is conceivable to cover both operations by switching between an air-fuel ratio control valve for stoichiometric operation and an air-fuel ratio control valve for lean operation, but the control accuracy of both valves is greatly different, so in the switching process, Smooth transition is not possible. Especially in the case of the gas engine, in the course of transition to lean operation from stoichiometric operation, because of the region of the excess air ratio generation amount increases of the NO _X in the exhaust gas (λ = 1 ~ 1.3), and stoichiometric operation if it is a smooth transition between the lean operation temporarily or NO _X in the exhaust gas becomes high, and thus cause inconvenience rotational speed of the fluctuation of the gas engine or higher.

The present invention provides a gas engine capable of smoothly switching between stoichiometric operation and lean operation, and a gas heat pump device and a cogeneration device using the gas engine.

The gas engine of the present invention for solving the above problems is a gas engine that performs stoichiometric operation when the engine is high load and lean operation when the engine is low and medium, and supplies a mixture of air and fuel gas to the gas engine The valve has a certain opening area that realizes the excess air ratio in stoichiometric operation, and when switching from stoichiometric operation to lean operation, the opening area is uniform over time until the switching operation ends. The excess air ratio decreases and the excess air ratio of lean operation increases, a certain opening area is secured to realize the lean air excess ratio, and when switching from lean operation to stoichiometric operation, time elapses until the switching operation ends At the same time, the opening area is controlled so that the opening area increases uniformly and the excess air ratio decreases.

In the gas engine, the valve is composed of one proportional control valve in which three different proportional control regions in which the valve opening and the valve opening area are proportional to each other at a constant value. A large stoichiometric operation region, a lean operation region with a small opening degree, and an intermediate switching operation region may be used.

Based on the relationship between the operating time of the switching operation and the accompanying engine speed fluctuation range, the operating time of the switching operation can be set so that the engine speed fluctuation range is not more than a predetermined threshold. Also good.

Further, a gas heat pump device of the present invention for solving the above-described problems has the above gas engine.

Furthermore, the cogeneration apparatus of the present invention for solving the above-described problems has the gas engine.

Furthermore, a gas engine control method according to the present invention for solving the above-mentioned problems is a gas engine that performs stoichiometric operation when the engine is high load and lean operation when the engine is low and medium load, and is a mixture of air and fuel gas in the gas engine. When the stoichiometric operation is performed, the valve that secures a certain opening area that realizes the excess air ratio of the stoichiometric operation, and when switching from the stoichiometric operation to the lean operation, the switching operation is completed. As the time passes, the opening area is reduced uniformly to increase the excess air ratio, and during lean operation, a certain opening area is ensured to achieve the excess air ratio of the lean operation. When switching to operation, until the switching operation ends, increase the opening area uniformly over time and decrease the excess air ratio. And it performs mouth area control.

Above As mentioned, according to the present invention, temporarily or NO _X in the exhaust gas becomes high, it is possible to prevent or higher rotational speed fluctuation of the gas engine.

In addition, stoichiometric operation can be performed when high load is required, and lean operation can be performed at medium and low load, so the range of load that can be handled is expanded, so various equipment devices such as gas heat pump devices and cogeneration devices When this gas engine is used, it is possible to use an optimal gas engine even with a small displacement, thereby reducing costs and saving energy.

Furthermore, since the stoichiometric operation, lean operation, and switching operation can be performed with one valve without using a plurality of valves, the engine can be designed compactly.

Therefore, the gas heat pump device using such a gas engine can improve the energy consumption efficiency (APF) throughout the year, and the overall energy efficiency of the cogeneration device can also be improved.

It is a block diagram which shows the outline of the whole structure of the gas engine which concerns on this invention. It is the schematic which shows the valve | bulb provided in the gas engine which concerns on this invention. 4 is a graph showing a relationship between a valve opening and a valve opening area and a relationship between a valve opening and an excess air ratio when the gas engine according to the present invention shifts from lean operation to stoichiometric operation. It is a graph which shows the relationship between the control time at the time of shifting to the stoichiometric operation from the lean operation of the gas engine which concerns on this invention, and a valve opening degree. It is a graph which shows the relationship between the transition time at the time of shifting to the stoichiometric operation from the lean operation of the gas engine which concerns on this invention, and rotation speed fluctuation | variation.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an outline of the overall configuration of the gas engine 1, FIG. 2 shows a proportional control valve 21 of the gas engine 1, and FIG. 3 shows between the lean operation and the stoichiometric operation by the gas engine 1. 4 shows the relationship between the valve opening area and the valve opening when switching, and FIG. 4 shows the relationship between the valve opening and time when switching between lean operation and stoichiometric operation by the gas engine 1.

This gas engine 1 is a gas engine 1 that performs stoichiometric operation at high loads and leans at medium and low loads, and has three proportional control areas with different stoichiometric operation areas a, lean operation areas b, and switching operation areas c. One valve 21 is provided.

The valve 21 is connected between the regulator 22 and the mixer 23 to constitute the fuel supply device 2.

In the valve 21, three different proportional control areas in which the valve opening and the valve opening area are proportional to each other at a constant value are formed as one proportional control valve. Each proportional control region includes a stoichiometric operation region a having a large opening, a lean operation region b having a small opening, and a switching operation region c in the middle. The control motor 20 controls the valve opening. It is configured.

The stoichiometric operation region a is designed so that the opening area through which the fuel gas passes can be adjusted in accordance with the valve opening in order to control the excess air ratio (λ = 1) at which the stoichiometric air-fuel ratio is achieved, in a pinpoint manner. . That is, as shown in FIG. 3, the stoichiometric operation region a is within the range of the opening 80-100 of the opening 0-100% of the valve 21, more preferably within the range of 70-100. A region in which the opening area of the valve 21 is proportional to a constant value is formed in accordance with the opening degree of the valve 21. The stoichiometric operation region a is not particularly limited as long as it has a flow rate characteristic capable of controlling the excess air ratio (λ = 1) that becomes the stoichiometric air-fuel ratio within the above-described valve opening range. Since it is necessary to cope with changes in the ambient temperature of the gas engine 1 and the operating speed range of the gas engine 1, the excess air ratio (λ = 1) that controls the theoretical air-fuel ratio is controlled following these changes. What formed the proportional control area | region so that it may have the flow characteristic which can be used is used.

In the lean operation region b, the opening area through which the fuel gas passes can be adjusted in accordance with the opening degree of the valve 21 in order to control the range (λ = 1.4 to 1.6) of the excess air ratio that causes lean combustion. Designed to be That is, as shown in FIG. 3, the lean operation region b is within the range of the opening 0-30 of the opening 0-100% of the valve 21, more preferably within the range of the opening 0-40. A region in which the opening area of the valve 21 is proportional to a constant value is formed in accordance with the opening degree of the valve 21. The lean operation region b is particularly limited as long as it has a flow rate characteristic capable of controlling the range of excess air ratio (λ = 1.4 to 1.6) that causes lean combustion within the above-described valve opening range. However, since it is necessary to cope with changes in the environmental atmospheric temperature in which the gas engine 1 is used and the operating rotational speed range of the gas engine 1, the range of the excess air ratio (λ = 1.4 to 1.6) in which a proportional control region is formed so as to have a flow characteristic that can be controlled.

The switching operation region c is for controlling switching from the excess air ratio (λ = 1) at the stoichiometric air-fuel ratio to the range of excess air ratio at the lean combustion (λ = 1.4 to 1.6). In addition, the opening area through which the fuel gas passes can be adjusted according to the opening degree of the valve 21. That is, as shown in FIG. 3, the switching operation region c is a range of the opening 70 to 30 between the stoichiometric operation region a and the lean operation region b out of the opening 0-100% of the valve 21. Preferably, an area in which the opening area of the valve 21 is proportional to the opening degree of the valve 21 is formed in a range of opening degrees 60 to 40 in accordance with the opening degree of the valve 21. The switching operation region c is a range of the air excess ratio (λ = 1) at which the stoichiometric air-fuel ratio is achieved, and the range of air excess ratio at which lean combustion is performed (λ = 1.4 to 1.6) within the above-described valve opening range. Although it is not particularly limited as long as it has a flow characteristic that can control switching to, it is necessary to cope with changes in the environmental atmosphere temperature in which the gas engine 1 is used and the rotation speed range in which the gas engine 1 is used. Following these changes, the flow rate that can control switching from the excess air ratio (λ = 1) at the stoichiometric air-fuel ratio to the range of excess air ratio (λ = 1.4 to 1.6) at which lean combustion occurs What formed the proportional control area | region so that it may have a characteristic is used.

The regulator 22 controls the pressure of the fuel gas so that the fuel gas can be always supplied at a constant pressure.

The mixer 23 is configured by a Venturi tube that mixes fuel gas and air. The mixer 23 is configured to mix fuel gas and air by the venturi effect of the air sucked according to the opening degree of the throttle valve 24 provided on the downstream side.

The fuel supply device 2 configured as described above is connected to the intake port 11 of the cylinder head 10 of the gas engine 1. The gas engine 1 is provided with a sensor (not shown) for measuring the oxygen concentration in the exhaust gas in the exhaust passage or the like, and measures the excess air ratio based on the measurement detection result. . The gas engine 1 can smoothly switch between the stoichiometric operation and the lean operation by controlling the fuel supply device 2 and the like by the control unit 3 based on the measurement detection result by the sensor and the like. Further, in the stoichiometric operation, although concentration of NO _X in the exhaust gas becomes high, is the reduction treatment by providing a three-way catalyst in an exhaust passage.

Next, control of the gas engine 1 by the control unit 3 will be described.

First, stoichiometric operation is performed in an operating environment that requires high output. This stoichiometric operation is performed by controlling the opening degree of the valve 21 in the stoichiometric operation region a so that the excess air ratio (λ = 1) of the stoichiometric air-fuel ratio is obtained. When the opening of the valve 21 is increased, the opening area is increased and the fuel gas concentration is increased. That is, the excess air ratio is decreased. When the opening is decreased, the opening area is decreased and the fuel gas concentration is decreased. The rate goes up. At this time, in the stoichiometric operation region a of the valve 21, the opening area of the valve 21 is proportional to the opening degree of the valve 21 so as to easily control the excess air ratio (λ = 1) of the theoretical air-fuel ratio. Since the region is formed, the excess air ratio (λ = 1) of the stoichiometric air-fuel ratio can be easily controlled.

∙ If the above-mentioned stoichiometric operation results in a medium to low load operating environment that does not require high output, switch from stoichiometric operation to lean operation with an excess air ratio of λ = 1.4 to 1.6.

This switching is performed by controlling the opening degree of the valve 21 in the switching operation region c. At this time, if the opening of the valve 21 is lowered, the opening area is reduced and the fuel gas concentration is decreased, that is, the excess air ratio is increased, and the stoichiometric operation excess air ratio (λ = 1) is obtained. It shifts to the range of excess air ratio (λ = 1.4 to 1.6) that causes lean combustion.

In this switching operation, it is desired to pass through the excess air ratio region (λ = 1 to 1.3) where the amount of NO _X generated in the exhaust gas increases as soon as possible. However, if it passes quickly, as shown in FIG. 5, a rotational speed fluctuation | variation will be produced and the gas engine 1 and its to-be-driven object will be damaged. In the case of the present invention, for this transition time, since the control time of the opening degree of the valve 21 can be freely set in the switching operation region c, the rotational fluctuation of the gas engine 1 is prevented so as not to damage the gas engine 1 and the like. Can be performed over a switching time when the value becomes equal to or less than a predetermined threshold A. Moreover, the switching operation region c of the valve 21 is formed with a region in which the opening area of the valve 21 is proportional to the opening of the valve 21 so as to be suitable for the switching operation. By controlling the opening, it is possible to smoothly switch the operation by passing through the excess air ratio region (λ = 1 to 1.3) where the amount of NO _X generation in the exhaust gas increases. it is possible to suppress the generation amount of of the NO _X to a minimum.

】 After switching to lean operation in this way, lean operation is performed. This lean operation is performed by controlling the opening degree of the valve 21 in the lean operation region b so that the excess air ratio of lean combustion is in the range (λ = 1.4 to 1.6). When the opening of the valve 21 is lowered, the opening area is reduced and the fuel gas concentration is decreased, that is, the excess air ratio is increased, and when the opening is increased, the opening area is increased and the fuel gas concentration is increased, that is, the air is excessive. The rate goes down. At this time, in the lean operation region b of the valve 21, the opening of the valve 21 is adjusted in accordance with the opening of the valve 21 so that the range of the excess air ratio (λ = 1.4 to 1.6) of lean combustion can be easily controlled. Since the area in which the area is proportional to the constant value is formed, the range of the excess air ratio of lean combustion (λ = 1.4 to 1.6) can be easily controlled.

When an operating environment requiring a high output is obtained after the lean operation, the lean operation with the excess air ratio λ = 1.4 to 1.6 is performed again using the switching operation region c of the valve 21 and the theoretical sky. The operation is switched to the stoichiometric operation with the excess air ratio (λ = 1) that becomes the fuel ratio.

In order to perform this switching, in the switching operation region c, the valve opening degree is controlled in the direction opposite to the above, and the excess air ratio (λ = 1) at which the stoichiometric air-fuel ratio is reached, that is, the stoichiometric operation region a. This is done by increasing the opening of the valve 21.

The relationship between the valve opening and the control time is as shown in FIG. That is, in the stoichiometric operation region a and the lean operation region b, control is performed so as to maintain a predetermined excess air ratio by a predetermined valve opening, so the control time ta and the lean operation region b in the stoichiometric operation region a are controlled. Although the valve opening does not change much with respect to the control time tb at, the control time tc in the switching operation region c changes from the stoichiometric operation to the lean operation by greatly changing the valve opening over a time period equal to or less than the above threshold A. Change to driving or vice versa.

When the gas engine 1 configured as described above is switched from the lean operation to the stoichiometric operation or vice versa, the switching operation region c formed in the valve 21 is used to generate the NO _X generation amount in the exhaust gas. Can pass smoothly through the excess air ratio region (λ = 1 to 1.3). Therefore, it is possible to suppress the generation amount of the NO _X in the exhaust gas by the driver switches to a minimum, it is possible to prevent damage to the gas engine 1 due to the fluctuation of the rotational speed.

Further, in the stoichiometric operation in which pinpoint control accuracy is required at an excess air ratio (λ = 1) that is the stoichiometric air-fuel ratio, the control is performed using the stoichiometric operation region a formed in the valve 21 to perform lean combustion. In the lean operation in which the control in the range of the excess air ratio (λ = 1.4 to 1.6) is required, the control can be performed using the lean operation region b formed in the valve 21. The valve 21 makes it possible to achieve both lean operation, stoichiometric operation, and switching operation between them.

The gas engine 1 thus configured can be suitably used as a drive source for a gas heat pump device (not shown). In other words, the gas heat pump device is required to have a high load in winter and summer, but can sufficiently cope with a medium and low load in the spring and autumn seasons. Moreover, the gas engine 1 drives a plurality of compressors when a high load is required, and conversely, when the load is low, it is normal to drive a single compressor. Therefore, the gas heat pump device using the gas engine 1 can perform lean operation when the load is medium and low, and can switch to the stoichiometric operation when high load is required. The cost can be reduced by using the gas engine 1 having the displacement.

In addition, at high loads, the stoichiometric operation reduces the thermal efficiency, but driving multiple compressors increases the mechanical efficiency, so the thermal efficiency is equivalent to the lean operation at medium and low loads. Naturally, the thermal efficiency at the time of medium and low loads is excellent because the lean operation is performed. Therefore, it is possible to increase the efficiency of year-round energy consumption efficiency (APF). Furthermore, since the fuel supply device 2 that performs the stoichiometric operation to the lean operation can be configured by the single valve 21, not only the gas engine 1 itself can be reduced but also the entire gas engine 1 can be reduced in size. it can.

The gas engine 1 can also be suitably used as a drive source for a cogeneration device (not shown). That is, the cogeneration apparatus can achieve energy saving by performing a stoichiometric operation when performing a lean operation during normal operation and switching to a heat main operation with a high load.

Note that the present invention can be implemented in various other forms without departing from the spirit or main features thereof. For this reason, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

The gas engine according to the present invention is used as a drive source for various energy saving facilities.

DESCRIPTION OF SYMBOLS 1 Gas engine 2 Fuel supply device 21 Valve a Stoke operation area b Lean operation area c Switching operation area λ Excess air ratio

Claims

A gas engine that performs stoichiometric operation when the engine is under high load, and lean operation when the engine is under low or medium load,
A valve that supplies a mixture of air and fuel gas to a gas engine
A certain opening area to ensure the excess air ratio of stoichi operation is secured.
When switching from stoichiometric operation to lean operation, the opening area decreases uniformly over time until the switching operation ends, and the excess air ratio increases.
A certain opening area that realizes the excess air ratio of lean operation is secured,
When switching from lean operation to stoichiometric operation, the opening area increases uniformly over time and the excess air ratio decreases until the switching operation ends.
Thus, the opening area control is performed as described above.
The valve is composed of one proportional control valve formed with three different proportional control areas in which the valve opening degree and the valve opening area are proportional to each other at a constant value. Each proportional control area includes a stoichiometric operation area with a small opening degree. The gas engine according to claim 1, wherein a lean operation region having a large opening and a switching operation region intermediate between them are used.
3. The operation time of the switching operation can be set so that the engine rotation fluctuation range is equal to or less than a predetermined threshold based on the relationship between the operation time of the switching operation and the accompanying engine rotation fluctuation range. Gas engine.
A gas heat pump apparatus comprising the gas engine according to any one of claims 1 to 3.
A cogeneration apparatus having the gas engine according to any one of claims 1 to 3.
In a gas engine that performs stoichiometric operation at high engine load and lean operation at medium to low load,
A valve that supplies a mixture of air and fuel gas to a gas engine
During stoichiometric operation, secure a certain opening area to realize the excess air ratio of the stoichiometric operation,
When switching from stoichiometric operation to lean operation, the opening area is reduced uniformly over time until the switching operation ends, and the excess air ratio is increased.
During lean operation, ensure a certain opening area to realize the excess air ratio of the lean operation,
When switching from lean operation to stoichiometric operation, until the switching operation is completed, the opening area is uniformly increased over time to reduce the excess air ratio,
A control method of a gas engine, wherein the opening area is controlled as described above.