Control device for engine power generation system

Abstract

To provide a control device for an engine power generation system which can suppress the discharge of harmful substances contained in exhaust to the outside by the early activation of an exhaust purification catalyst and the early warmup of an engine, in the power generation system constituted by an engine which can be supplied with RE fuel and hydrocarbon-based fuel and allows mixed combustion.SOLUTION: A hydrocarbon-based fuel supply quantity or a hydrogen supply quantity to an engine is controlled on the basis of a catalyst activation state which is detected by a catalyst activation state detection part and an engine warmup state detection part.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The present invention relates to a control device for an engine power generation system compatible with mixed combustion of renewable energy-derived fuels, such as hydrogen, and hydrocarbon fuels, such as gasoline and natural gas. [Background technology]

[0002] As renewable energy expands toward the decarbonization of energy, the importance of balancing power generation systems that use renewable energy-derived fuels (hereinafter referred to as RE fuels) such as hydrogen is increasing in order to respond to the resulting power fluctuations.

[0003] While large-scale gas-fired power plants can be used as adjustable power, their output adjustment range is limited to 30% to 100% of rated operation, which does not provide sufficient adjustment power. In addition, since the installation location of the facilities is fixed, it is necessary to reinforce the power lines, which increases the facility costs. Furthermore, since the procurement range of fuel to be used is limited for large-scale thermal power plants, it is difficult to effectively utilize RE fuels that are ubiquitous in the region.

[0004] Distributed power generation systems that use engine generators compatible with RE fuel are promising as systems that can respond to fluctuations in renewable energy while utilizing RE fuel, which is ubiquitous in the region. In particular, by utilizing mass-produced engines such as existing automobile engines and industrial engines and using them as stationary power generation systems, it is possible to minimize initial equipment costs. In addition, by using engines that can mix and burn RE fuels such as hydrogen with hydrocarbon fuels such as gasoline and natural gas (hereinafter referred to as mixed combustion), it becomes possible to operate the power generation system according to the amount of RE fuel produced or procured, thereby increasing the operating rate.

[0005] A control device for such an engine power generation system is known from Patent Document 1. Patent Document 1 discloses a "fuel supply device for an internal combustion engine that is configured to be able to supply hydrogen fuel and hydrocarbon-based fuel independently to a combustion chamber of an internal combustion engine, and that has a first combustion control mode in which the hydrocarbon-based fuel is supplied to a radial center portion of the combustion chamber or to a peripheral portion of an ignition plug provided for the combustion chamber, and the hydrogen fuel is supplied to a space in the combustion chamber surrounding the space to which the hydrocarbon-based fuel is supplied." [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5772958 Summary of the Invention [Problem to be solved by the invention]

[0007] Engine exhaust contains carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), etc., which are harmful to humans, animals, and plants, so it is necessary to suppress the emission of these harmful substances to the outside. For this purpose, it is effective to provide an exhaust purification catalyst in the exhaust path of the engine to purify harmful substances (NOx, THC, CO, etc.) and to reduce harmful substances directly emitted from the engine. First, for purification by catalyst, the challenge is to activate the catalyst early. This is because harmful substances can be effectively purified by raising the temperature of the catalyst and making it active. Next, for reducing harmful substances directly emitted from the engine, lean combustion, in which the minimum amount of air required for complete combustion is burned in a leaner state (hereinafter referred to as lean) than the theoretical air-fuel ratio, which is the ratio of fuel, is effective. This is because lean combustion reduces the combustion gas temperature, which significantly suppresses the amount of NOx generated by combustion. In addition, since lean combustion contains oxygen in the exhaust, both THC and CO can be purified by a three-way catalyst. On the other hand, since lean combustion reduces combustion stability, it is important to quickly achieve a warm-up state in the engine that allows stable combustion (hereinafter referred to as early engine warm-up). In addition, in a multi-fuel engine that can supply multiple fuels independently, it is necessary to solve the above problem by taking into account the properties of each fuel.

[0008] In this regard, in the conventional technology described in Patent Document 1, a mixture of hydrocarbon fuel and hydrogen is burned when the catalyst is heated, so the time required to activate the catalyst increases compared to when only hydrocarbon fuel is burned. This is because the temperature of the exhaust gas generated by the combustion of hydrogen is lower than the temperature of the exhaust gas generated by the combustion of hydrocarbon fuel. Furthermore, the conventional technology described in Patent Document 1 is limited to a configuration that includes a means capable of controlling the spatial distribution of fuel in the combustion chamber, and for example, in a configuration in which the hydrocarbon fuel and hydrogen are supplied from the middle of the intake pipe, the hydrocarbon fuel and hydrogen are supplied to the combustion chamber in a well-mixed state, making it difficult to apply.

[0009] The present invention has been made in consideration of the above circumstances, and has an object to provide a control device for an engine power generation system that is capable of quickly activating an exhaust purification catalyst and quickly warming up the engine in a power generation system including an engine that can supply RE fuel and hydrocarbon-based fuel and can perform mixed combustion. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides an engine power generation system that generates power using an engine in which hydrocarbon fuel and hydrogen are supplied to enable mixed combustion and which has an engine warm-up state detection unit that detects whether the engine is in a warm-up state, the engine power generation system control device comprising a catalyst that is provided in an exhaust passage of the engine to purify exhaust gas, and a catalyst activation state detection unit that detects whether the catalyst is in an active state, the engine power generation system control device controlling the amount of hydrocarbon fuel or hydrogen supplied to the engine based on the catalyst activation state detected by the catalyst activation state detection unit and the warm-up state of the engine detected by the engine warm-up state detection unit. Effect of the Invention

[0011] According to the present invention, it is possible to control the supply amounts of hydrocarbon fuel and hydrogen depending on the activation state of the catalyst and the warm-up state of the engine, thereby enabling early activation of the catalyst and early warm-up of the engine, thereby making it possible to suppress the emission of harmful substances contained in the exhaust to the outside.

[0012] Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic configuration diagram showing an example in which a power generation system control device according to a first embodiment of the present invention is applied to a power generation system including an engine generator fueled by hydrogen and natural gas. [Diagram 2]FIG. 2 is a block diagram showing an example of a hardware configuration of the power generation system control device according to the first embodiment of the present invention. [Diagram 3] FIG. 1 is a diagram showing an example of an engine configuration according to a first embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing another example of the engine configuration according to the first embodiment of the present invention. [Diagram 5] FIG. 2 is a graph showing heat generation histories under natural gas mono-combustion conditions and hydrogen-mixed combustion conditions according to the first embodiment of the present invention. [Figure 6] FIG. 4 is a graph showing the history of average gas temperatures in the cylinder under natural gas mono-fuel combustion conditions and hydrogen-mixed combustion conditions according to the first embodiment of the present invention. [Figure 7] FIG. 2 is a diagram showing the amount of heat transfer from the gas in the cylinder to the engine cylinder according to the first embodiment of the present invention. [Figure 8] FIG. 2 is a diagram showing lean limits under natural gas mono-combustion conditions and hydrogen-mixed combustion conditions according to the first embodiment of the present invention. [Figure 9] FIG. 4 is a diagram showing an indicated thermal efficiency at a lean limit according to the first embodiment of the present invention. [Figure 10] FIG. 4 is a diagram showing the amount of NOx generated at the lean limit according to the first embodiment of the present invention. [Figure 11] FIG. 2 is a diagram showing an operation mode according to the first embodiment of the present invention. [Figure 12] FIG. 2 is a diagram showing an example of a flowchart of engine generator control according to the first embodiment of the present invention. [Figure 13] 4 is a time chart of a scene in which the catalyst according to the first embodiment of the present invention is inactive and the engine is started from a cold condition. [Figure 14] FIG. 11 is a schematic configuration diagram showing an example in which a power generation system control device according to a second embodiment of the present invention is applied to a power generation system including a plurality of engine generators fueled by hydrogen and natural gas. [Figure 15] FIG. 11 is a block diagram showing an example of a hardware configuration of a power generation system control device according to a second embodiment of the present invention. [Figure 16] FIG. 11 is a diagram showing the indicated thermal efficiency under a natural gas mono-combustion condition and a hydrogen co-combustion condition according to Example 2 of the present invention. [Figure 17] FIG. 6 is a diagram showing an operation mode according to a second embodiment of the present invention. [Figure 18]FIG. 11 is a diagram showing an example of a flowchart of engine generator control according to a second embodiment of the present invention. [Figure 19] 10 is a time chart showing a scene in which the total required output increases from a state in which engine A is operating at a rated output, and engine B is newly started according to the second embodiment of the present invention. [Figure 20] FIG. 11 is a diagram showing the tendency of CO, HC, and NOx generation with respect to the air-fuel ratio in premixed combustion in a spark ignition engine according to a third embodiment of the present invention. [Figure 21] FIG. 11 is a diagram showing an example of a flowchart of engine generator control according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the present invention, at least one fuel is hydrogen and the other fuel is a hydrocarbon fuel. In the embodiment, natural gas is exemplified as the hydrocarbon fuel, but diesel or gasoline may also be used. This combination of fuels can be selected as appropriate.

[0015] [Example 1] First Embodiment FIG. 1 is a schematic configuration diagram showing an example in which a power generation system control device according to a first embodiment of the present invention is applied to a power generation system including an engine generator fueled by hydrogen and natural gas.

[0016] The power generation system 100 includes a power generation module GM that is composed of an engine 11, a generator 12, and a power converter 13, and the engine 11 includes an electronic control unit (ECU) 15 for controlling the engine 11. The engine 11 is connected to a hydrogen generator 2 via a hydrogen supply device 14, and is capable of being supplied with hydrogen fuel. The engine 11 is also connected to a fuel tank (not shown) and is capable of being supplied with natural gas, thereby enabling combustion with hydrogen fuel, natural gas, or a mixed fuel of hydrogen and natural gas. The output of this power generation module GM is electrically connected to a load side device 3.

[0017] The minimum configuration of the power generation module GM applicable to the present invention is that it is necessary to include an engine 11 and a generator 12, and depending on whether the load is an AC load or a DC load, an appropriate power converter 13 may be included. Also, the generator 12 may be either an AC generator or a DC generator.

[0018] Furthermore, a three-way catalyst 20 as an exhaust purification catalyst for purifying the exhaust gas, a catalyst upstream temperature sensor 18 for measuring the temperature of the gas flowing into the three-way catalyst 20 (catalyst inlet gas temperature), an air-fuel ratio sensor 17 which is one form of an air-fuel ratio detector and detects the air-fuel ratio of the exhaust gas upstream of the three-way catalyst 20, and an oxygen concentration sensor 19 which detects the oxygen concentration of the exhaust gas downstream of the three-way catalyst 20 are provided at appropriate positions in the exhaust passage 16 of the engine 11.

[0019] The three-way catalyst 20 oxidizes the hydrocarbons and carbon monoxide in the exhaust gas and reduces the nitrogen oxides at the same time, converting the harmful gas components in the exhaust gas into carbon dioxide, water vapor, and nitrogen. In order to maximize the conversion efficiency of the three-way catalyst 20, the ratio of the reactive components (HC, NOx, CO, H2) must be stoichiometrically ideal. The range of the air-fuel ratio of the mixture that realizes this state is called a window, and in a typical spark-ignition engine, the mass ratio of air to fuel is a very narrow range near the theoretical air-fuel ratio (stoichiometric), which is the minimum ratio of air to fuel required for complete combustion.

[0020] The power generation system control device 1 is mounted on the power generation system 100. The power generation system control device 1 calculates the required load of the power generation system 100 based on the required load Sg1 from the load side device 3. Furthermore, the power generation system control device 1 receives supplyable hydrogen amount information Sg2 from the hydrogen generator 2. Furthermore, the power generation system control device 1 receives information (engine state) Sg3 of the sensors and actuators of the engine 11 from the engine 11. Furthermore, the power generation system control device 1 receives the air-fuel ratio Sg4, the catalyst inflow gas temperature (also referred to as catalyst upstream temperature) Sg5, and the oxygen concentration Sg6 as information related to the control of the three-way catalyst 20 from the air-fuel ratio sensor 17, the catalyst upstream temperature sensor 18, and the oxygen concentration sensor 19. Based on this information (Sg1), the power generation system control device 1 sends the engine required output and a command for whether or not to drive (hereinafter simply referred to as required output) Sd1 to the ECU 15 of the engine 11, and controls the hydrogen supply device 14 to realize a desired hydrogen supply amount (hydrogen supply target amount) Sd2.

[0021] The ECU 15 controls the output of the engine 11 based on the required output Sd1 from the power generation system control device 1. Specifically, the ECU 15 controls a natural gas fuel injection unit, an ignition unit, a throttle valve, and a starter. The engine 11 is, for example, a four-cylinder engine that uses spark ignition combustion, and is an example of an internal combustion engine. The generator 12 generates power using the driving force of the engine 11 to achieve a desired power load. The power converter 13 adjusts the voltage and phase of the power generated by the generator 12, and supplies the adjusted power to the load side device 3.

[0022] Next, a description will be given of an internal configuration example of the power generation system control device 1 according to the first embodiment. Fig. 2 is a block diagram showing a hardware configuration example of the power generation system control device 1. The power generation system control device 1 is configured using a computer device.

[0023] In Fig. 2, the required load Sg1, the supplyable hydrogen amount Sg2, and the engine state Sg3 output from the load side device 3, the hydrogen generator 2, and the ECU 15, respectively, are input to the input circuit 1a of the power generation system control device 1. However, the input signals are not limited to these. Each signal input to the input circuit 1a is sent to an input port (not shown) in the input / output port 1b. The values ​​sent to the input port are stored in the RAM (1c) and processed by the CPU (1e). A control program describing the contents of the processing is written in advance in the ROM (1d).

[0024] Values ​​indicating the operating amounts of the controlled objects (engine 11, hydrogen supply device 14, etc.) calculated according to the control program are stored in RAM (1c) and then sent to an output port (not shown) in input / output port 1b, and sent to each device (ECU 15, hydrogen supply device 14) via each output section (engine torque control output section 1f, hydrogen supply amount control output section 1g) as a required output Sd1 and a desired hydrogen supply amount (target hydrogen supply amount) Sd2. Note that in FIG. 2, an engine control device (ECU 15) is provided separately from the power generation system control device 1, but this is not limited to the embodiment, and functional sections corresponding to the control devices of each device may be provided within the power generation system control device 1.

[0025] FIG. 3 is a diagram showing an example of the configuration of the engine 11 according to the first embodiment. The engine 11 is modified so as to be capable of supplying hydrogen to a four-cylinder engine for an automobile that performs spark ignition combustion. An air flow sensor 21 for measuring the amount of intake air and an electronically controlled throttle 26 for adjusting the intake pipe pressure are provided at appropriate positions in each intake pipe 27. In addition, the engine 11 is provided with a spark plug 29 for each cylinder for supplying ignition energy into a combustion chamber 28 of each cylinder, and a cooling water temperature sensor 24 for measuring the temperature of the cooling water of the engine 11 is provided at an appropriate position in a cylinder head 30. The exhaust pipe 25 is connected to the exhaust passage 16.

[0026] A natural gas injection device 22 for injecting natural gas as fuel is provided inside the combustion chamber 28. The natural gas injection device 22 is connected to a fuel tank (not shown) by a fuel pipe. Furthermore, a hydrogen supply passage 23 for supplying hydrogen into the intake pipe 27 is provided, and the hydrogen supply passage 23 is connected to a hydrogen supply device 14 that controls the amount of hydrogen supplied. The hydrogen supply device 14 is connected to the hydrogen generation device 2 by a hydrogen pipe.

[0027] With the above configuration, it is possible to switch between engine operation using natural gas (natural gas only), engine operation using hydrogen (hydrogen only), and engine operation using both hydrogen and natural gas at the same time (natural gas-hydrogen mixed combustion).

[0028] FIG. 4 is a diagram showing another example of the configuration of the engine 11 according to the first embodiment. The engine 11 is modified so as to be capable of supplying hydrogen to a four-cylinder engine for an automobile that performs spark ignition combustion. An air flow sensor 21 for measuring the amount of intake air and an electronically controlled throttle 26 for adjusting the intake pipe pressure are provided at appropriate positions in each intake pipe 27. In addition, the engine 11 is provided with a spark plug 29 for each cylinder for supplying ignition energy into a combustion chamber 28 of each cylinder, and a cooling water temperature sensor 24 for measuring the temperature of the cooling water of the engine 11 is provided at an appropriate position in a cylinder head 30. The exhaust pipe 25 is connected to the exhaust passage 16.

[0029] A natural gas injection device 22 for injecting natural gas as fuel is provided inside the intake pipe 27. The natural gas injection device 22 is connected to a fuel tank (not shown) by a fuel pipe. Furthermore, a hydrogen supply passage 23 for supplying hydrogen into the combustion chamber 28 is provided, and the hydrogen supply passage 23 is connected to a hydrogen supply device 14 that controls the amount of hydrogen supplied. The hydrogen supply device 14 is connected to the hydrogen generation device 2 by a hydrogen pipe.

[0030] With the above configuration, it is possible to switch between engine operation using natural gas (natural gas only), engine operation using hydrogen (hydrogen only), and engine operation using both hydrogen and natural gas at the same time (natural gas-hydrogen mixed combustion).

[0031] The embodiment of the present invention will be described in detail below. First, the key points of control in the embodiment will be described, and then the specific processing of the embodiment will be described.

[0032] First, we will explain the key points in control from the viewpoint of early activation of the catalyst and early warm-up of the engine. The conditions shown in Figures 5 to 7 are for mono-fuel natural gas combustion and for mixed-fuel natural gas and hydrogen combustion, and are the same for each, with the engine speed and indicated mean effective pressure constant, the air-fuel ratio being the stoichiometric air-fuel ratio, and the ignition timing being the optimal ignition timing.

[0033] Figure 5 shows the heat release history under conditions of natural gas mono-combustion and hydrogen co-firing. The horizontal axis is crank angle, and the vertical axis is heat release rate. Figure 5 shows the heat release history near the compression top dead center during the compression-expansion stroke. Figure 5 shows that hydrogen co-firing makes heat release steeper. The main reason for this is that the laminar burning speed of hydrogen is significantly higher than that of natural gas, which is mainly composed of methane.

[0034] The in-cylinder average gas temperature history under natural gas mono-combustion and hydrogen co-firing conditions is shown in Figure 6. As can be seen from Figure 6, as a result of the steeper heat generation with hydrogen co-firing, the time when the in-cylinder average gas temperature reaches its maximum is earlier, and after 30 degATDC, the in-cylinder average gas temperature is lower than under natural gas mono-combustion.

[0035] Figure 7 shows the amount of heat transfer from the gas inside the cylinder to the engine cylinder (hereafter referred to as cylinder heat transfer). Hydrogen co-firing increases the amount of heat transfer in the cylinder. This is thought to be due to the fact that hydrogen combustion has a much faster burning speed than natural gas, and this is caused by the large gas flow generated by flame propagation, and the fact that the flame front reaches the combustion chamber wall quickly, resulting in large gas convection near the wall.

[0036] From the above, from the perspective of early catalyst activation, it is effective to use only natural gas in order to increase the exhaust temperature, while from the perspective of early engine warm-up, it is effective to increase the hydrogen mixture ratio in order to increase the amount of heat transferred to the cylinder.

[0037] Next, the control points under the conditions after the catalyst is activated and the engine is warmed up will be described.

[0038] Figure 8 shows the lean limit for natural gas mono-combustion and hydrogen co-firing conditions. Here, the lean limit refers to the air-fuel ratio at which the engine's combustion stability reaches its allowable limit. Figure 8 shows that the lean limit is wider under hydrogen co-firing conditions compared to natural gas mono-combustion. This is because the laminar burning velocity of hydrogen is significantly higher than that of natural gas.

[0039] Figure 9 shows the indicated thermal efficiency at the lean limit. It can be seen from Figure 9 that the indicated thermal efficiency at the lean limit is higher under hydrogen co-firing conditions compared to natural gas mono-firing conditions. This is mainly because the increased degree of leanness reduces the combustion gas temperature, which in turn reduces the cooling loss.

[0040] Figure 10 shows the amount of NOx generated at the lean limit. It can be seen from Figure 10 that the amount of NOx generated at the lean limit is significantly lower under hydrogen co-firing conditions compared to natural gas mono-firing conditions. The main reason for this is that the lower combustion gas temperature suppresses the generation of thermal NOx, which is generated by the reaction of nitrogen and oxygen at high temperatures.

[0041] From the above, under conditions after the catalyst has been activated and the engine has warmed up, it is effective to use hydrogen co-fuel and lean combustion.

[0042] Considering the above key points of control, in this embodiment, the amount of hydrocarbon fuel or hydrogen supplied to the engine is controlled based on the activation state of the catalyst and the warm-up state of the engine. Specifically, as shown in FIG. 11, three operation modes with different hydrogen mixing ratios and air-fuel ratios are provided, and control is performed to switch the operation mode depending on the activation state of the catalyst and the warm-up state of the engine. Here, the hydrogen mixing ratio is the ratio of the amount of hydrogen to the total amount of fuel (natural gas and hydrogen) supplied to the engine. The ratio may be a calorific value ratio, a volume ratio, a mass ratio, or the like, and may be selected appropriately. Details of each operation mode are shown below.

[0043] Mode 1 Under conditions where the catalyst is inactive, only hydrocarbon fuel is supplied to the engine, and the engine is exclusively combusted with hydrocarbon fuel. This increases the exhaust temperature, and the catalyst can be activated earlier. In addition, ignition retard control may also be performed. This increases the exhaust temperature, and the catalyst can be activated earlier. In addition, the air-fuel ratio of the engine is controlled so that the oxygen concentration of the exhaust flowing into the catalyst is equal to or lower than a predetermined value C1. The predetermined value C1 is the oxygen concentration of the exhaust when the engine is operated at a theoretical air-fuel ratio (stoichiometric). Note that the air-fuel ratio of the engine is not required to be strictly stoichiometric as long as it is controlled within the window range of the catalyst where the ratio of reaction components (HC, NOx, CO, H2) is stoichiometrically ideal. This allows the catalyst to purify harmful gas components (HC, CO, NOx) in the exhaust.

[0044] Mode 2 Under conditions where the catalyst is active and the engine is cold, the engine is supplied with hydrocarbon fuel and hydrogen to perform hydrogen co-firing. This increases the amount of heat transfer in the cylinder, allowing the engine to warm up quickly. The air-fuel ratio of the engine is controlled so that the oxygen concentration of the exhaust gas flowing into the catalyst is equal to or lower than a predetermined value C1. The predetermined value C1 is the oxygen concentration of the exhaust gas when the engine is operated at a theoretical air-fuel ratio (stoichiometric). The air-fuel ratio does not need to be strictly stoichiometric as long as it is controlled within the window of the catalyst. In particular, under hydrogen co-firing conditions, the combustion temperature increases and the amount of NOx generated increases, and the amount of H2 generated increases with an increase in the amount of hydrogen supplied, while the amount of CO and THC generated decreases with a decrease in the amount of hydrocarbon fuel supplied. Therefore, the relationship between the air-fuel ratio and the exhaust composition under hydrogen co-firing conditions may be obtained in advance, and the air-fuel ratio may be controlled so that the ratio of the reaction components (HC, NOx, CO, H2) is stoichiometrically ideal. This allows the catalyst to purify harmful gas components (HC, CO, NOx) in the exhaust gas.

[0045] Mode 3 When the catalyst is active and the engine is warmed up, the engine is supplied with hydrocarbon fuel and hydrogen for hydrogen co-firing. This allows the lean limit to be expanded. In addition, the engine air-fuel ratio is controlled so that the oxygen concentration of the exhaust gas flowing into the catalyst is equal to or higher than a predetermined value C2. The predetermined value C2 is the oxygen concentration of the exhaust gas under lean conditions where the engine air-fuel ratio can suppress the amount of NOx produced by the engine to a value that sufficiently meets the exhaust gas regulation value without using an aftertreatment device (in other words, when the engine is operated at an air-fuel ratio where the amount of nitrogen oxides directly emitted from the engine is equal to or lower than a predetermined value). This allows the NOx emitted from the engine to be reduced, and the catalyst to purify CO and HC with high efficiency.

[0046] Next, a specific process of this embodiment will be described.

[0047] An example of a flow chart of the engine generator control according to this embodiment is shown in Fig. 12. Each step will be described in detail below.

[0048] <Step S1> In step S1, the power generation system control device 1 first reads information (required load) Sg1 from the connected load side device 3. The information (required load) Sg1 from the load side device 3 is, for example, the current power consumption (voltage and current) of the device on the load side or a future predicted value. Also, when the output of the power generation system 100 is connected to a power grid, the information is the current or future power request value from the grid side.

[0049] <Step S2> In step S2, the power generation system control device 1 reads information (engine state) Sg3 of the engine 11 from the ECU 15 and the engine 11. The information (engine state) Sg3 from the ECU 15 and the engine 11 is, for example, the engine state such as the current engine speed, torque, and engine temperature (cooling water temperature, intake air temperature, etc.) and engine specifications (displacement, compression ratio, fuel supply position, etc.).

[0050] <Step S3> In step S3, the power generation system control device 1 reads hydrogen generation information (supplyable hydrogen amount) Sg2 from the hydrogen generation device 2. Here, the hydrogen generation device 2 is, for example, a water electrolytic cell that generates hydrogen from renewable energy, and information such as the power that can be input to the water electrolytic cell and output efficiency is read into the power generation system control device 1.

[0051] <Step S4> In step S4, the power generation system control device 1 reads information related to catalyst control from the air-fuel ratio sensor 17, the catalyst upstream temperature sensor 18, and the oxygen concentration sensor 19. The information related to catalyst control is the air-fuel ratio Sg4, the catalyst inflow gas temperature (catalyst upstream temperature) Sg5, and the oxygen concentration Sg6.

[0052] <Step S5> In step S5, the power generation system control device 1 calculates a total required output required for the power generation system 100 based on information (required load) Sg1 from the load side device 3. Here, the total required output for the engine is calculated taking into account losses of the power converter 13 and the generator 12, etc.

[0053] <Step S6> In step S6, the power generation system control device 1 judges the activation state of the catalyst based on the catalyst inflow gas temperature Sg5. Here, if the catalyst inflow gas temperature Tc is equal to or higher than a predetermined temperature Tc0, the catalyst is judged to be in an activated state, and if the catalyst inflow gas temperature Tc is lower than the predetermined temperature Tc0, the catalyst is judged to be in an inactivated state. In this way, the activation state of the catalyst can be judged with high accuracy by judging based on a value obtained by directly detecting the temperature of the gas in the vicinity of the catalyst. That is, in this embodiment, the power generation system control device 1 has a catalyst activation state detection unit that detects whether the catalyst is in an activated state. The catalyst activation state detection unit detects the temperature of the gas flowing into the catalyst (catalyst inflow gas temperature) (from the catalyst inflow gas temperature measured by the catalyst upstream temperature sensor 18), and judges that the catalyst is in an activated state when the catalyst inflow gas temperature is equal to or higher than a predetermined value. However, the means for detecting whether the catalyst is in an activated state is not limited to this.

[0054] <Step S7> In step S7, the power generation system control device 1 judges the warm-up state of the engine based on information (engine state) Sg3 from the ECU 15 and the engine 11. Here, if the engine coolant temperature Tw is equal to or higher than a predetermined temperature Tw1, it is judged that the engine is warmed up, and if the engine coolant temperature Tw is lower than the predetermined temperature Tw1, it is judged that the engine is cold. In this way, since the judgment is based on a directly detected value of the engine coolant temperature, the warm-up state of the engine can be judged with high accuracy. That is, in this embodiment, the power generation system control device 1 has an engine warm-up state detection unit that detects whether the engine is in a warm-up state. The engine warm-up state detection unit detects the engine coolant temperature (from the coolant temperature measured by the coolant temperature sensor 24), and judges that the engine is in a warm-up state when the engine coolant temperature is equal to or higher than a predetermined value. However, the means for detecting whether the engine is in a warm-up state is not limited to this.

[0055] <Step S8> In step S8, the power generation system control device 1 calculates the engine operation mode based on the catalyst activation state and the engine warm-up state determined in steps S6 and S7. Here, the corresponding operation mode is set among the operation modes shown in FIG. 11. When the catalyst is inactive (in other words, when the catalyst activation state detection unit detects that the catalyst is inactive), mode 1 (only hydrocarbon fuel is supplied to the engine and the engine is exclusively burned with hydrocarbon fuel) is set. This increases the exhaust temperature and enables the catalyst to be activated early. When the catalyst is active and the engine is cold (in other words, when the catalyst activation state detection unit detects that the catalyst is active and the engine warm-up state detection unit detects that the engine is cold), mode 2 (hydrocarbon fuel and hydrogen are supplied to the engine and the engine is mixed and burned with hydrogen) is set. This increases the amount of heat transfer in the cylinder and enables the engine to be warmed up early. When the catalyst is active and the engine is warm (in other words, when the catalyst activation state detection unit detects that the catalyst is active and the engine warm state detection unit detects that the engine is warm), mode 3 (supplying hydrocarbon fuel and hydrogen to the engine for hydrogen co-combustion) is set. This reduces NOx emitted from the engine and enables the catalyst to purify CO and HC with high efficiency.

[0056] <Step S9> In step S9, the power generation system control device 1 calculates the hydrogen mixing ratio based on the operation mode calculated in step S8. At this time, the hydrogen required by the power generation system 100 is set to be equal to or not exceed the hydrogen generation capacity obtained from the hydrogen generation device 2. For example, the hydrogen mixing ratio is calculated by setting in advance the hydrogen mixing ratio for the hydrogen generation capacity obtained from the hydrogen generation device 2 for each operation mode and storing the ratio in the ROM of the power generation system control device 1. For example, by setting the hydrogen mixing ratio to increase with an increase in the hydrogen generation capacity, engine warm-up can be promoted in mode 2 under conditions where the hydrogen generation capacity is large, and the engine can be operated under leaner conditions in mode 3 under conditions where the hydrogen generation capacity is large, resulting in highly efficient operation.

[0057] In addition, in mode 2, the hydrogen mixing ratio is set so that the lower the engine coolant temperature, the higher the hydrogen mixing ratio. In other words, in mode 2 (when the engine warm-up state detection unit detects that the engine is cold), the amount of hydrocarbon fuel or hydrogen supplied to the engine is set (controlled) so that the percentage of hydrogen in the total fuel supply amount decreases as the engine coolant temperature increases. As a result, the lower the engine coolant temperature, the higher the hydrogen mixing ratio becomes, and the amount of heat transfer in the cylinder increases, thereby facilitating engine warm-up.

[0058] <Step S10> In step S10, the power generation system control device 1 sends the total required output calculated in step S5 to the ECU 15 as an engine torque command value (required output) Sd1, and executes the torque command.

[0059] <Step S11> In step S11, the power generation system control device 1 executes hydrogen supply amount control so as to realize the hydrogen mixed combustion ratio of the engine calculated in step S9, sends a hydrogen supply amount command value (hydrogen supply target amount) Sd2 to the hydrogen supply device 14, and ends the series of controls.

[0060] 13 shows a time chart of a scene in which the catalyst is inactive and the engine is started when it is cold in this embodiment. The vertical axis indicates, from the top, the total required output, the catalyst activation state, the engine warm-up state, the operation mode, the hydrogen mixture ratio, the catalyst upstream gas air-fuel ratio, the engine power generation amount, and the cumulative amount of harmful substance emissions, while the horizontal axis indicates time. The solid line indicates this embodiment, and the dashed line indicates the prior art.

[0061] In FIG. 13, at time t0, information is received from the load side device and the total required output is calculated. At this time, the catalyst is inactive and the engine is in a cold state, so in this embodiment, the operation mode is set to mode 1, the hydrogen mixture ratio is set to 0, and the air-fuel ratio is set to stoichiometric. After that, at time t1, the catalyst is activated and the engine is in a cold state, so in this embodiment, the operation mode is set to mode 2, the hydrogen mixture ratio is set to a predetermined value, and the air-fuel ratio is set to stoichiometric. As the catalyst is activated, harmful substances are purified, and the cumulative amount of harmful substance emissions becomes almost constant thereafter. In addition, the colder the engine is (not shown, but the lower the engine coolant temperature), the higher the hydrogen mixture ratio is set, so that the warm-up of the engine is promoted. After that, at time t2, the catalyst is activated and the engine is in a warm-up state, so in this embodiment, the operation mode is set to mode 3, the hydrogen mixture ratio is set to a predetermined value, and the air-fuel ratio is set to lean. On the other hand, in the conventional technology, hydrogen mixed combustion is performed regardless of the activation state of the catalyst, so the exhaust temperature drops and the activation of the catalyst is delayed. Accordingly, harmful substances are discharged without being purified until the catalyst is activated, and as a result, the cumulative amount of harmful substance discharged increases.

[0062] In this embodiment, the method of starting the engine is not described, but the air-fuel ratio may be enriched to stabilize the combustion during the period from engine cranking to when the combustion is stabilized. Also, by using hydrogen mixed combustion or hydrogen only combustion at the time of starting, it is possible to achieve stable combustion compared to the case of using only hydrocarbon fuel, and it is also possible to reduce the emission of unburned substances such as CO and THC.

[0063] In addition, in this embodiment, the activity state of the catalyst is directly detected by the catalyst upstream temperature sensor 18, but the activity state of the catalyst can also be estimated based on the engine operating conditions (e.g., intake air volume, fuel supply volume, ignition timing, engine speed, etc.).

[0064] Furthermore, in this embodiment, the air-fuel ratio of the engine is obtained from the output value of the air-fuel ratio sensor 17, but it may be calculated based on the intake air amount detected by the airflow sensor 21 and the fuel injection amount.

[0065] As is clear from the above description, this embodiment is an engine power generation system (power generation system 100) that generates power using an engine that is supplied with hydrocarbon fuel and hydrogen to enable co-combustion and has an engine warm-up detection unit that detects whether the engine is in a warm-up state, and a control device (power generation system control device 1) for the engine power generation system that includes a catalyst that is provided in the exhaust passage of the engine to purify exhaust gas and a catalyst activation state detection unit that detects whether the catalyst is in an activated state, and that controls the amount of hydrocarbon fuel or hydrogen supplied to the engine (more specifically, the ratio of the amount of hydrocarbon fuel and hydrogen supplied to the engine) based on the catalyst activation state detected by the catalyst activation state detection unit and the warm-up state of the engine detected by the engine warm-up state detection unit. This enables early activation of the catalyst and early warm-up of the engine, and as a result, the amount of harmful substances emitted from the power generation system 100 can be suppressed.

[0066] [Example 2] A second embodiment of the present invention will be described. In this embodiment, a method of applying a power generation system control device according to the present invention to a power generation system consisting of multiple engine generators that use hydrogen and natural gas as fuel will be described. Note that in the second embodiment described below, the configuration described in the first embodiment is applied except for the differences from the first embodiment.

[0067] Second Embodiment FIG. 14 is a schematic configuration diagram showing an example in which a power generation system control device according to a second embodiment of the present invention is applied to a power generation system including a plurality of engine generators fueled by hydrogen and natural gas.

[0068] The power generation system 100 is configured by connecting multiple power generation modules GM (GM1 to GMn) in parallel, each of which is made up of an engine 11, a generator 12, and a power converter 13. The engines 11 are equipped with an electronic control unit (ECU) 15 for controlling each engine 11. The engines 11 are connected to a hydrogen generator 2 via a hydrogen supply device 14, and are capable of being supplied with hydrogen fuel. The engines 11 are also connected to a fuel tank (not shown) and are capable of being supplied with natural gas, thereby making it possible to burn hydrogen or natural gas, or a mixed fuel of hydrogen and natural gas. The outputs of these power generation modules GM (GM1 to GMn) are electrically connected to a load side device 3.

[0069] The minimum configuration of the power generation module GM applicable to the present invention is that it is necessary to include an engine 11 and a generator 12, and depending on whether the load is an AC load or a DC load, an appropriate power converter 13 may be included. Also, the generator 12 may be either an AC generator or a DC generator.

[0070] The exhaust pipes of the engines 11 are joined together in an exhaust passage 16. In addition, a three-way catalyst 20 as an exhaust purification catalyst for purifying the exhaust gas, a catalyst upstream temperature sensor 18 for measuring the temperature of gas flowing into the three-way catalyst 20 (catalyst inflow gas temperature), an air-fuel ratio sensor 17 which is one form of an air-fuel ratio detector and detects the air-fuel ratio of the exhaust gas upstream of the three-way catalyst 20, and an oxygen concentration sensor 19 which detects the oxygen concentration of the exhaust gas downstream of the three-way catalyst 20 are provided at appropriate positions in the exhaust passage 16 after the exhaust pipes of the engines 11 are joined together.

[0071] The power generation system control device 1 is mounted on the power generation system 100. The power generation system control device 1 calculates the required load of the power generation system 100 based on the required load Sg1 from the load side device 3. Furthermore, the power generation system control device 1 receives supplyable hydrogen amount information Sg2 from the hydrogen generator 2. Furthermore, the power generation system control device 1 receives information (engine state) Sg3 (Sg31 to Sg3n) of the sensors and actuators of each engine 11 from the engine 11. Furthermore, the power generation system control device 1 receives the air-fuel ratio Sg4, catalyst inflow gas temperature (catalyst upstream temperature) Sg5, and oxygen concentration Sg6 from the air-fuel ratio sensor 17, catalyst upstream temperature sensor 18, and oxygen concentration sensor 19 as information related to the control of the three-way catalyst 20. Based on this information (Sg1, Sg2, Sg3), the power generation system control device 1 sends the engine required output and commands regarding whether to drive (hereinafter simply referred to as required output) Sd1 (Sd11 to Sd1n) to the ECU 15 of each engine 11, and controls each hydrogen supply device 14 to achieve the desired hydrogen supply amount (hydrogen supply target amount) Sd2 (Sd21 to Sd2n).

[0072] The ECU 15 controls the output of the engine 11 based on the required output Sd1 from the power generation system control device 1. Specifically, the ECU 15 controls a natural gas fuel injection unit, an ignition unit, a throttle valve, and a starter. The engine 11 is, for example, a four-cylinder engine that uses spark ignition combustion, and is an example of an internal combustion engine. The generator 12 generates power using the driving force of the engine 11 to achieve a desired power load. The power converter 13 adjusts the voltage and phase of the power generated by the generator 12, and supplies the adjusted power to the load side device 3.

[0073] Next, a description will be given of an internal configuration example of the power generation system control device 1 according to the second embodiment. Fig. 15 is a block diagram showing a hardware configuration example of the power generation system control device 1. The power generation system control device 1 is configured using a computer device.

[0074] In FIG. 15, the required load Sg1, the supplyable hydrogen amount Sg2, and the engine state Sg3 (Sg31 to Sg3n) output from the load side device 3, the hydrogen generator 2, and the ECU 15 are input to the input circuit 1a of the power generation system control device 1. However, the input signals are not limited to these. Each signal input to the input circuit 1a is sent to an input port (not shown) in the input / output port 1b. The value sent to the input port is stored in the RAM (1c) and is processed by the CPU (1e). A control program describing the contents of the processing is written in advance in the ROM (1d).

[0075] Values ​​indicating the operating amounts of the controlled objects (engine 11, hydrogen supply device 14, etc.) calculated according to the control program are stored in RAM (1c) and then sent to an output port (not shown) in input / output port 1b, and sent to each device (ECU 15, hydrogen supply device 14) via each output section (engine torque control output section 1f, hydrogen supply amount control output section 1g) as required output Sd1 (Sd11-Sd1n) and desired hydrogen supply amount (hydrogen supply target amount) Sd2 (Sd21-Sd2n). Note that in FIG. 15, the control devices (ECU 15) for each engine are provided separately from the power generation system control device 1, but this is not limited to the above, and functional sections corresponding to the control devices of each device may be provided within the power generation system control device 1.

[0076] In a configuration with multiple engine generators, the number of operating power generation modules GM can be adjusted according to the total required load from the load side equipment. For example, assume that i power generation modules are operating at rated power at a certain total required output Pr1, and that all engines with active catalysts and in operation are in a warmed-up state, operating in mode 3 (hydrogen mixed combustion (lean)) in the first embodiment. In this situation, assume that the total required output from the load side equipment increases to Pr2 at a certain timing. At this time, if the increase in the total required output cannot be accommodated by adjusting the output of the modules in operation, the total required output Pr2 is realized by newly operating k modules. Here, since the newly started k engines are cold, they are operated in mode 2 (hydrogen mixed combustion (stoichiometric)) in the first embodiment in order to warm up the engines early. At this time, in order to maximize the purification ability of the catalyst, the air-fuel ratio of the i engines that have already been operating must also be stoichiometric. In this embodiment, the control is performed under such conditions that a warmed-up engine and a cold engine operate at the same time.

[0077] Figure 16 shows the indicated thermal efficiency under conditions of mono-natural gas combustion and hydrogen co-firing. The conditions are the same for both mono-natural gas combustion and natural gas-hydrogen co-firing, with constant engine speed and indicated mean effective pressure, a stoichiometric air-fuel ratio, and optimal ignition timing. Under hydrogen co-firing conditions, the indicated thermal efficiency is lower than under mono-natural gas combustion. The main reason for this is that the amount of heat transfer in the cylinder increases, as shown in Figure 7, resulting in increased cooling losses.

[0078] From the above, from the viewpoint of the indicated thermal efficiency under theoretical air-fuel ratio conditions, it is effective to exclusively use natural gas.

[0079] Therefore, in this embodiment, the amount of hydrocarbon fuel or hydrogen supplied to each engine is controlled based on the activation state of the catalyst and the warm-up state of each engine. Specifically, as shown in Fig. 17, four operation modes with different hydrogen mixing ratios and air-fuel ratios are provided, and control is performed to switch the operation mode depending on the activation state of the catalyst and the warm-up state of each engine. Modes 1 and 2 are similar to modes 1 and 2 in embodiment 1, so a description thereof will be omitted. Details of modes 3 and 4 are shown below.

[0080] Mode 3 When the catalyst is active, the engine is warmed up, and the cold engine is not running at the same time, a hydrocarbon fuel and hydrogen are supplied to the warm engine to perform hydrogen co-firing. This allows the lean limit to be expanded. Also, the air-fuel ratio of each engine is controlled so that the oxygen concentration of the exhaust gas flowing into the catalyst is equal to or higher than a predetermined value C2. The predetermined value C2 is the oxygen concentration of the exhaust gas under the engine air-fuel ratio (lean) condition that can suppress the amount of NOx generated from the engine to a value that can sufficiently achieve the exhaust gas regulation value without using an aftertreatment device (in other words, when the engine is operated at an air-fuel ratio that makes the amount of nitrogen oxides directly emitted from the engine equal to or lower than a predetermined value). This allows the NOx emitted from the engine to be reduced when the cold engine is not running at the same time, and the catalyst can purify CO and HC with high efficiency.

[0081] Mode 4 When the catalyst is active, the engine is warmed up, and a cold engine is running at the same time, only hydrocarbon fuel is supplied to the warm engine, and the engine burns only hydrocarbon fuel. This allows the warm engine to operate under highly efficient conditions. The air-fuel ratio of each engine is controlled so that the oxygen concentration of the exhaust gas flowing into the catalyst is equal to or lower than a predetermined value C1. The predetermined value C1 is the oxygen concentration of the exhaust gas when the engine is running at a theoretical air-fuel ratio (stoichiometric). Note that the air-fuel ratio of the engine needs only to be controlled within the catalyst window in which the ratio of reaction components (HC, NOx, CO, H2) is stoichiometrically ideal, and does not need to be strictly stoichiometric. This allows the catalyst to purify harmful gas components (HC, CO, NOx) in the exhaust gas when a cold engine is running at the same time.

[0082] Next, a specific process of this embodiment will be described.

[0083] An example of a flow chart of the engine generator control according to this embodiment is shown in Fig. 18. Each step will be described in detail below.

[0084] <Step S12> Step S12 is the same process as step S1 in the first embodiment, so a description thereof will be omitted.

[0085] <Step S13> In step S13, the power generation system control device 1 reads information (engine state) Sg3 (Sg31 to Sg3n) of each engine 11 from each ECU 15 and the engine 11. The information (engine state) Sg3 from the ECU 15 and the engine 11 is, for example, engine states such as the current engine speed, torque, and engine temperature (cooling water temperature, intake temperature, etc.) and engine specifications (displacement, compression ratio, fuel supply position, etc.).

[0086] <Steps S14 to S16> Steps S14 to S16 are similar to steps S3 to S5 in the first embodiment, so their explanation will be omitted.

[0087] <Step S17> In step S17, the power generation system control device 1 distributes the total required output Sd1 calculated in step S16 to each engine power generation module to obtain individual required outputs Sd11, Sd12, ... Sd1n (processing step S5). For example, the number of engine power generation modules required to be driven is calculated from the total required output Sd1 and the rated output of each engine power generation module, and the total required output Sd1 is evenly distributed among the driven engine power generation modules.

[0088] <Step S18> Step S18 is the same process as step S6 in the first embodiment, so a description thereof will be omitted.

[0089] <Step S19> In step S19, the power generation system control device 1 judges the warm-up state of each engine based on the information (engine state) Sg3 (Sg31 to Sg3n) from each ECU 15 and the engine 11. Here, if the engine coolant temperature Tw is equal to or higher than a predetermined temperature Tw1, it is judged that the engine is warmed up, and if the engine coolant temperature Tw is lower than the predetermined temperature Tw1, it is judged that the engine is cold. In this way, since the judgment is based on a directly detected value of the engine coolant temperature, the warm-up state of the engine can be judged with high accuracy.

[0090] <Step S20> In step S20, the power generation system control device 1 calculates the operation mode of each engine based on the activation state of the catalyst and the warm-up state of each engine determined in steps S18 and S19. Here, the corresponding operation mode is set among the operation modes shown in FIG. 17. When the catalyst is inactive (in other words, when the catalyst activation state detection unit detects that the catalyst is inactive), mode 1 (only hydrocarbon fuel is supplied to the engine and the engine is exclusively burned with hydrocarbon fuel) is set. This increases the exhaust temperature and enables the catalyst to be activated early. When the catalyst is active and the engine is cold (in other words, when the catalyst activation state detection unit detects that the catalyst is active and the engine warm-up state detection unit detects that the engine is cold), mode 2 (hydrocarbon fuel and hydrogen are supplied to the engine and the engine is mixed and burned with hydrogen) is set. This increases the amount of heat transfer in the cylinder and enables the engine to be warmed up early. When the catalyst is active, the engine is in a warm-up condition, and the cold engine is not operating at the same time (in other words, when the catalyst activation state detection unit detects that the catalyst is active, the engine warm-up state detection unit detects that the engine is warmed up, and the cold engine is not operating at the same time), mode 3 (hydrocarbon fuel and hydrogen are supplied to the warm-up engine to perform hydrogen co-combustion) is set. This enables hydrogen co-combustion (lean) when the cold engine is not operating at the same time, thereby reducing NOx emitted from the engine and enabling the catalyst to purify CO and HC with high efficiency. When the catalyst is active, the engine is in a warm-up condition, and the cold engine is operating at the same time (in other words, when the catalyst activation state detection unit detects that the catalyst is active, the engine warm-up state detection unit detects that the engine is warmed up, and the cold engine is operating at the same time), mode 4 is set, and only hydrocarbon fuel is supplied to the warm-up engine to perform hydrocarbon fuel exclusive combustion (stoichiometric). This allows the warmed engine to operate under highly efficient conditions, and the catalyst can purify HC, CO, and NOx with high efficiency.

[0091] <Step S21> In step S21, the power generation system control device 1 calculates the hydrogen mixing ratio for each engine based on the operation mode calculated in step S20. The other processing is the same as that in step S9 in the first embodiment, so detailed description will be omitted.

[0092] <Step S22> In step S22, the power generation system control device 1 sends the torque command values ​​(individual required outputs Sd11, Sd12, . . . Sd1n) for each engine calculated in step S17 to each ECU 15, and executes the torque commands.

[0093] <Step S23> In step S23, the power generation system control device 1 executes hydrogen supply amount control so as to realize the hydrogen mixed combustion ratio for each engine calculated in step S21, and sends individual hydrogen supply amount command values ​​(Sd21, Sd22, ... Sd2n) to each hydrogen supply device 14, and ends the series of controls.

[0094] 19 shows a time chart of a scene in this embodiment where the total required output increases from a state in which engine A is operating at rated power, and engine B is then started. From the top, the vertical axis indicates the total required output, catalyst activation state, warm-up state of engines A and B, operation mode, hydrogen mixture ratio, power generation amount, thermal efficiency, and catalyst upstream gas air-fuel ratio (exhaust air-fuel ratio), and the horizontal axis indicates time. The solid line indicates this embodiment, and the dashed line indicates the prior art.

[0095] In FIG. 19, at time t5, the total required output increases, and engine B is started to respond to the increase. At this time, the catalyst is active, engine A is warmed up, and engine B is cold, so in this embodiment, the operation mode for engine A is set to mode 4 (single-fuel combustion of hydrocarbon fuel), the hydrogen mixture ratio is 0, and the air-fuel ratio is stoichiometric, and the operation mode for engine B is set to mode 2 (mixed hydrogen combustion), the hydrogen mixture ratio is a predetermined value, and the air-fuel ratio is stoichiometric. On the other hand, in the conventional technology, the operation mode for both engines A and B is set to the preset mode 2 (mixed hydrogen combustion), the hydrogen mixture ratio is a predetermined value, and the air-fuel ratio is stoichiometric. In this way, while engine A in the conventional technology burns hydrogen, engine A in this embodiment burns single-fuel combustion of hydrocarbon fuel, so that the thermal efficiency of engine A can be improved compared to the conventional technology. Also, in this embodiment, the colder the engine is (not shown, but the lower the engine coolant temperature is), the higher the hydrogen mixture ratio is set, so that engine B can be warmed up earlier in this embodiment compared to the conventional technology. At time t6, in this embodiment, the catalyst becomes active and engine A and engine B become warmed up, and for both engine A and engine B, the operation mode is set to mode 3, the hydrogen mixture ratio is set to a predetermined value, and the air-fuel ratio is set to lean, enabling highly thermally efficient operation. On the other hand, in the conventional technology, the catalyst becomes active and engine A and engine B become warmed up at time t7, which is after time t6, and the period until highly thermally efficient operation is achieved is lengthened.

[0096] In this manner, in this embodiment, the amount of hydrocarbon fuel or hydrogen supplied to each engine (more specifically, the ratio of the amount of hydrocarbon fuel and hydrogen supplied to each engine) is controlled based on the catalyst activation state and the warm-up state of each engine. This enables early activation of the catalyst and early warm-up of the engine, thereby suppressing harmful substance emissions from the power generation system 100. Furthermore, when a cold engine is operating at the same time, the warm engine can be operated under conditions of high thermal efficiency, thereby reducing fuel consumption.

[0097] [Example 3] A third embodiment of the present invention will be described. In this embodiment, a method for setting the air-fuel ratio of each engine in a power generation system control device according to the present invention applied to a power generation system consisting of multiple engine generators fueled by hydrogen and natural gas, so that the ratio of reaction components (HC, NOx, CO, H2) of the gas flowing into the catalyst becomes a stoichiometrically ideal value, will be described. In the third embodiment described below, the configuration described in the second embodiment is applied except for the differences from the second embodiment.

[0098] First, a method for setting the air-fuel ratio of each engine in this embodiment will be described with reference to FIG.

[0099] Figure 20 shows the generation trends of CO, HC, and NOx versus air-fuel ratio in premixed combustion in a spark ignition engine. Premixed refers to a state in which air and fuel are mixed uniformly before ignition. Here, we will use a single hydrocarbon fuel, or a mixture of hydrocarbon fuel and hydrogen, as examples. The generation characteristics of each component are explained below.

[0100] CO and HC Since CO and HC are components of incomplete combustion, their amounts increase as the air-fuel ratio becomes smaller and the mixture becomes richer. When starting the engine, a rich mixture is necessary to stabilize combustion, which tends to generate large amounts of CO.

[0101] NOx NOx is mainly NO, which is produced in large quantities at high temperatures and in the presence of oxygen and nitrogen. The combustion gas is at its highest when the mixture is slightly richer than the stoichiometric air-fuel ratio, where oxygen is present only during combustion, but after combustion there is no oxygen, and the amount of oxygen increases in the leaner range. As a result, the amount of NO produced is at its maximum when the mixture is leaner than the stoichiometric air-fuel ratio.

[0102] The air-fuel ratio of each engine is set based on the generation characteristics of CO, HC, and NOx relative to the air-fuel ratio. For example, consider a scenario in which engine A is operating at rated power but the total required output increases, and engine B is started. When engine B starts, the air-fuel ratio of engine B is set to rich to stabilize combustion. At this time, large amounts of CO and HC are generated. Therefore, the air-fuel ratio of engine A is set to lean to increase the amounts of NOx and oxygen. This allows the ratio of reactive components in the gas flowing into the catalyst to be stoichiometrically ideal, and the catalyst can purify harmful substances with high efficiency.

[0103] Next, a specific process of this embodiment will be described.

[0104] An example of a flowchart of engine generator control according to this embodiment is shown in Fig. 21. Each step will be described in detail below.

[0105] <Steps S24 to S33> Steps S24 to S33 are similar to steps S12 to S21 in the second embodiment, and therefore a description thereof will be omitted.

[0106] <Step S34> In step S34, the power generation system control device 1 calculates the air-fuel ratio of each engine based on the information (engine state) Sg3 (Sg31 to Sg3n) from each ECU 15 and the engine 11. Here, the air-fuel ratio of the newly started engine is set to rich. Also, the air-fuel ratio of the already operating engine is set to lean or stoichiometric. At this time, the air-fuel ratio of each engine is set so that the ratio of the reactive components of the gas flowing into the catalyst is a stoichiometrically ideal value. For example, in the case where there is one newly started engine and two already operating engines, the newly started engine may be set to rich and the already operating engines may all be set to lean, or one may be set to stoichiometric. By controlling the air-fuel ratio of each engine in this way, harmful substances can be purified by the catalyst with high efficiency.

[0107] <Steps S35 and S36> Steps S35 and S36 are similar to steps S22 and S23 in the second embodiment, so their explanation will be omitted.

[0108] In this embodiment, when at least one engine is in operation, the air-fuel ratio of the newly started engine is controlled to be rich, and the air-fuel ratio of the engines already in operation is controlled to be lean or stoichiometric. By controlling the air-fuel ratio of each engine in this manner, the ratio of reactive components in the gas flowing into the catalyst becomes a stoichiometrically ideal value, and harmful substances can be purified by the catalyst with high efficiency. As a result, the amount of harmful substances emitted from the power generation system 100 can be suppressed.

[0109] The present invention is not limited to the above-described embodiments, and it goes without saying that various other applications and modifications are possible without departing from the gist of the present invention as set forth in the claims.

[0110] For example, the above-mentioned embodiments have described the configuration of the device and system in detail and specifically in order to explain the present invention in an easily understandable manner, and are not necessarily limited to those including all of the configurations described. In addition, it is possible to replace a part of the configuration of the embodiments described here with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

[0111] In addition, the control lines and information lines shown are those that are considered necessary for the explanation, and not all control lines and information lines in the product are necessarily shown. In reality, it can be considered that almost all components are connected to each other. [Explanation of symbols]

[0112] 1: Power generation system control device (control device for engine power generation system) 1a: Input circuit 1b: Input / Output port 1c:RAM 1d:ROM 1e:CPU 1f: Engine torque control output section 1g: Hydrogen supply amount control output section 2: Hydrogen generator 3: Load side equipment 11: Engine 12: Generator 13: Power converter 14: Hydrogen supply device 15: ECU 16: Exhaust passage 17: Air-fuel ratio sensor 18: Catalyst upstream temperature sensor 19: Oxygen concentration sensor 20: Exhaust purification catalyst (three-way catalyst) 21: Air flow sensor 22: Natural gas injection device 23: Hydrogen supply channel 24: Coolant temperature sensor 25: Exhaust pipe 26: Electronically controlled throttle 27: Intake pipe 28: Combustion chamber 29: Spark plug 30: Cylinder head

Claims

1. In an engine power generation system that performs power generation by an engine equipped with a hydrocarbon-based fuel and hydrogen supply and capable of co-combustion, and having an engine warm-up state detection unit that detects whether the engine is in a warm-up state, a catalyst provided in the exhaust passage of the engine for purifying exhaust gas, and a catalyst activity state detection unit that detects whether the catalyst is in an active state, a control device for the engine power generation system, based on the catalyst activity state detected by the catalyst activity state detection unit and the warm-up state of the engine detected by the engine warm-up state detection unit, controls the supply amount of the hydrocarbon-based fuel or hydrogen to the engine, when the catalyst activity state detection unit detects that the catalyst is active, supplies the hydrocarbon-based fuel and hydrogen to the engine for co-combustion with hydrogen, a control device for an engine power generation system characterized by this.

2. A control device for an engine power generation system according to Claim 1, characterized in that, based on the catalyst activity state detected by the catalyst activity state detection unit and the warm-up state of the engine detected by the engine warm-up state detection unit, controls the ratio of the supply amounts of the hydrocarbon-based fuel and hydrogen supplied to the engine.

3. A control device for an engine power generation system according to Claim 1, when the catalyst activity state detection unit detects that the catalyst is inactive, supplies only the hydrocarbon-based fuel to the engine for exclusive combustion of the hydrocarbon-based fuel, a control device for an engine power generation system characterized by this.

4. A control device for an engine power generation system according to Claim 1, when the engine warm-up state detection unit detects that the engine is cold, controls the air-fuel ratio of the engine so that the oxygen concentration of the exhaust gas flowing into the catalyst becomes equal to or less than a predetermined value C1, wherein the predetermined value C1 is the oxygen concentration of the exhaust gas when the engine is operated at a stoichiometric air-fuel ratio, a control device for an engine power generation system characterized by this.

5. A control device for an engine power generation system according to Claim 1, when the engine warm-up state detection unit detects that the engine is warm, controls the air-fuel ratio of the engine so that the oxygen concentration of the exhaust gas flowing into the catalyst becomes equal to or greater than a predetermined value C2, The control device for an engine power generation system, wherein the predetermined value C2 is the oxygen concentration of the exhaust gas when the engine is operated at an air-fuel ratio at which the amount of nitrogen oxides directly discharged from the engine is equal to or less than a predetermined value.

6. The control device for an engine power generation system according to claim 1, wherein the catalyst activity state detection unit detects the temperature of the gas flowing into the catalyst, i.e., the catalyst inflow gas temperature, and determines that the catalyst is in an active state when the catalyst inflow gas temperature is equal to or higher than a predetermined value, and / or the engine warm-up state detection unit detects the cooling water temperature of the engine, and determines that the engine is in a warm-up state when the cooling water temperature of the engine is equal to or higher than a predetermined value. The control device for an engine power generation system is characterized by this.

7. The control device for an engine power generation system according to claim 1, when it is detected by the engine warm-up state detection unit that the engine is cold, the hydrocarbon-based fuel supply amount or hydrogen supply amount to the engine is controlled such that the ratio of the amount of hydrogen in the total supplied fuel amount decreases as the cooling water temperature of the engine increases. The control device for an engine power generation system is characterized by this.

8. The control device for an engine power generation system according to claim 1, wherein the engine power generation system includes a plurality of the engines, an exhaust passage that aggregates the exhaust pipes of each of the plurality of engines, and the catalyst provided in the exhaust passage, and the hydrocarbon-based fuel supply amount or hydrogen supply amount to each engine is controlled based on the catalyst activity state detected by the catalyst activity state detection unit and the warm-up state of each engine detected by the engine warm-up state detection unit. The control device for an engine power generation system is characterized by this.

9. The control device for an engine power generation system according to claim 8, when it is detected by the catalyst activity state detection unit that the catalyst is active and it is detected by the engine warm-up state detection unit that the engine is cold, hydrocarbon-based fuel and hydrogen are supplied to the engine for hydrogen co-combustion. The control device for an engine power generation system is characterized by this.

10. The control device for an engine power generation system according to claim 8, When it is detected by the catalyst activity state detector that the catalyst is active, and it is detected by the engine warm-up state detector that the engine is warm, and the cold engine is not operating at the same time, hydrocarbon fuel and hydrogen are supplied to the warm engine for hydrogen co-combustion. A control device for an engine power generation system characterized by this.

11. A control device for an engine power generation system according to claim 8, When it is detected by the catalyst activity state detector that the catalyst is active, and it is detected by the engine warm-up state detector that the engine is warm, and the cold engine is operating at the same time, only hydrocarbon fuel is supplied to the warm engine for exclusive combustion of hydrocarbon fuel. A control device for an engine power generation system characterized by this.

12. A control device for an engine power generation system according to claim 11, When it is detected by the engine warm-up state detector that the cold engine is operating at the same time, the air-fuel ratio of each engine is controlled so that the oxygen concentration of the exhaust gas flowing into the catalyst becomes equal to or less than a predetermined value C1. The control device for an engine power generation system, wherein the predetermined value C1 is the oxygen concentration of the exhaust gas when the engine is operated at the stoichiometric air-fuel ratio.

13. A control device for an engine power generation system according to claim 10, When it is detected by the engine warm-up state detector that the cold engine is not operating at the same time, the air-fuel ratio of each engine is controlled so that the oxygen concentration of the exhaust gas flowing into the catalyst becomes equal to or greater than a predetermined value C2. The control device for an engine power generation system, wherein the predetermined value C2 is the oxygen concentration of the exhaust gas when the engine is operated at an air-fuel ratio at which the amount of nitrogen oxides directly discharged from the engine becomes equal to or less than a predetermined value.

14. A control device for an engine power generation system according to claim 8, When at least one or more engines are operating, the air-fuel ratio of the newly started engine is controlled to be rich, and the air-fuel ratio of the already operating engine is controlled to be lean or stoichiometric. A control device for an engine power generation system characterized by this.

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