Combustion control system

Abstract

To improve economic performance by maintaining a simple configuration without a flowmeter, and save manpower through automation of various types of regulation, such as a flow rate.SOLUTION: A combustion control system includes: a main fuel flow rate control mechanism 100 serving as a flow rate control mechanism that controls a flow rate of main fuel gas G1 as control target gas flowing through main fuel piping H1 communicating and connecting with a burner BNa as site piping; an auxiliary flow rate control mechanism 500 serving as a flow rate control mechanism that controls a flow rate of auxiliary fuel gas G2 as control target gas flowing through auxiliary fuel piping H3 communicating and connecting with the burner BNa as site piping; and a combustion gas flow rate control mechanism RVa serving as a flow rate control mechanism that controls a flow rate of combustion gas A as a control target gas flowing through combustion gas piping H2 communicating and connecting with the burner as site piping.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a combustion control system using a flow rate control mechanism equipped with a control unit that controls the flow rate of a gas to be controlled, which is either a fuel gas that is a main fuel gas or a secondary fuel gas, or a combustion gas that serves as an oxidizer for the fuel gas. [Background technology]

[0002] Conventionally, a pressure equalizing valve type combustion control system has been known as a combustion control system used in industrial furnaces and the like (see Patent Document 1). This pressure equalizing valve type combustion control system includes, for example, a fuel pipe connected to a burner and carrying fuel gas such as city gas 13A, a combustion gas pipe similarly connected to the burner and carrying combustion air, a temperature controller that controls the burner output based on the temperature of the industrial furnace, a control motor that controls the flow rate of air flowing through the combustion gas pipe based on a signal from the temperature controller and a control valve connected by a linkage to the motor and controlled to open and close, a pressure equalizing valve that controls the opening of the fuel pipe in accordance with the air pressure on the secondary side of the control valve of the combustion gas pipe, and a blower that pressure-feeds combustion air to the combustion gas pipe. In this pressure equalizing valve type combustion control system, the linkage between the control motor and the control valve is manually adjusted by an expert, and the adjustment is one-point adjustment, so changing the air ratio, etc., requires another manual adjustment by an expert. This is also the case with double linkage type combustion control systems. Another known configuration is an electronic linkage type combustion control system, which includes, for example, a fuel pipe connected to a burner and carrying fuel gas such as city gas 13A, a combustion gas pipe similarly connected to the burner and carrying combustion air, a temperature controller that controls the burner output based on the temperature of the industrial furnace, a control unit that receives a signal from the temperature controller, a flow meter that measures the fuel gas flow rate through the fuel pipe and the air flow rate through the combustion gas pipe and sends the results to the control unit, a fuel flow control valve that controls the flow rate of fuel gas through the fuel pipe based on a signal from the control unit, and an air flow control valve that controls the flow rate of air through the combustion gas pipe based on a signal from the control unit. In this electronic linkage system, the flow rate of fuel gas and combustion air is monitored by a flow meter, and the air ratio based on this is monitored, and the air ratio can be changed by setting the control unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-47654 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned pressure equalizing valve type combustion control system, it is not possible to monitor the flow rate and air ratio of the fuel gas and combustion air, and even if these deviate from the target values ​​for some reason, the user will not be aware of this, and there is a risk that the furnace temperature will not be able to be maintained at the set value. Furthermore, adjustments to the output and air ratio require manual adjustment by an experienced technician, making it difficult to improve efficiency by reducing the number of people required. On the other hand, although the electronic linkage system enables automatic monitoring and automatic adjustment of the flow rate and air ratio of fuel gas and combustion air, it requires the installation of a relatively expensive flow meter, which is problematic from an economic standpoint. In particular, with regard to combustion control for multi-fuel burners that burn multiple fuels, one possible technology is to use carbon-free hydrogen or ammonia as a secondary fuel gas to reduce CO2 emissions. However, for example, in a configuration where hydrogen is mixed, there is no hydrogen sensor on the market that can measure the amount of hydrogen required for the 600kW-class combustion furnaces that are commonly used on the market, and the development of new technology was desired.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a combustion control system that improves economy by maintaining a simple configuration without a flow meter, and that can reduce manpower by automating various adjustments such as flow rate, while also being able to effectively adjust the proportion of secondary fuel gas in the fuel and adjust the air ratio to a desired value when secondary fuel gas such as hydrogen or ammonia is mixed and burned. [Means for solving the problem]

[0006] The combustion control system for achieving the above object comprises: A combustion control system using a flow rate control mechanism equipped with a control unit that controls the flow rate of a control target gas, which is either a fuel gas that is a main fuel gas or a secondary fuel gas, or a combustion gas that serves as an oxidizer for the fuel gas, and its characteristic configuration is as follows: The flow rate control mechanism includes: a flow control valve that is provided in an on-site piping through which the gas to be controlled flows, and whose opening is controlled by a control command from the control unit; a secondary-side pressure adjusting unit that is provided on the secondary side of the flow control valve in the on-site piping and that is capable of adjusting the pressure of the secondary-side outlet based on a measurement result of a second pressure gauge that is provided at a secondary-side outlet of the flow control valve; a primary-side pressure adjusting unit that is provided on the primary side of the flow control valve in the on-site piping and that is capable of adjusting the pressure of the primary-side inlet based on a measurement result of a first pressure gauge that is provided at the primary-side inlet of the flow control valve; In a test facility comprising the flow control valve, the secondary pressure adjustment unit, and the primary pressure adjustment unit in a test pipe having the same diameter as the on-site pipe, and a flow meter for measuring a flow rate of the test pipe, the control unit causes the controlled gas to flow through the test pipe, and sets the pressure of the secondary outlet to a predetermined initial set secondary pressure with the secondary pressure adjustment unit while maintaining the flow control valve at a predetermined initial set opening, and then comprises a memory unit that stores an opening / flow rate relationship between the opening of the flow control valve and the flow rate measured by the flow meter while maintaining the pressure of the primary inlet at a predetermined flow control pressure with the primary pressure adjustment unit, In the on-site facility provided with the flow control valve, the secondary-side pressure adjustment unit, and the primary-side pressure adjustment unit in the on-site piping, the control unit causes the gas to be controlled to flow through the on-site piping, and sets the pressure of the secondary-side outlet to the initially set secondary pressure using the secondary-side pressure adjustment unit while maintaining the flow control valve at the initially set opening, and then, while maintaining the pressure of the primary-side inlet at the flow control pressure using the primary-side pressure adjustment unit, controls the opening of the flow control valve based on the opening-flow rate relationship stored in the memory unit to control the flow rate of the gas to be controlled to a target flow rate, a main fuel flow rate control mechanism serving as the flow rate control mechanism for controlling a flow rate of the main fuel gas serving as the gas to be controlled that flows through a main fuel pipe connected in communication with a burner serving as the on-site pipe; a secondary fuel flow rate control mechanism serving as the flow rate control mechanism for controlling the flow rate of the secondary fuel gas as the gas to be controlled that flows through a secondary fuel pipe that is connected in communication with the burner as the on-site pipe; a combustion gas flow rate control mechanism as the flow rate control mechanism for controlling the flow rate of the combustion gas as the control target gas flowing through a combustion gas pipe connected in communication with the burner as the on-site pipe, The control unit controls the flow rate of the main fuel gas to the target flow rate using the main fuel flow rate control mechanism, controls the flow rate of the secondary fuel gas to the target flow rate using the secondary fuel flow rate control mechanism, and controls the flow rate of the combustion gas to the target flow rate using the combustion gas flow rate control mechanism.

[0007] According to the above characteristic configuration, a secondary pressure adjustment unit is provided that is provided on the secondary side of the flow control valve in the on-site piping and is capable of adjusting the pressure of the secondary outlet based on the measurement results of the second pressure gauge provided at the secondary outlet of the flow control valve, so that by appropriately setting the secondary pressure adjustment unit of the flow control valve in the on-site piping, it is possible to adjust the pressure loss on the secondary side of the flow control valve to a constant value regardless of the site. In this configuration, the flow rate Q of the controlled gas flowing through the on-site piping can be derived from the relational expression Q=K√P2 using the pressure P2 at the secondary outlet of the flow control valve. Furthermore, by providing a primary side pressure adjustment unit that is provided on the primary side of the flow control valve in the test piping and that can adjust the pressure at the primary side inlet based on the measurement results of the first pressure gauge provided at the primary side inlet of the flow control valve, the pressure at the primary side inlet of the flow control valve is maintained at a predetermined flow control pressure by the primary side pressure adjustment unit, and the resulting opening / flow rate relationship between the opening of the flow control valve and the flow rate flowing through the test piping can be used as is in field equipment that has field piping of the same diameter as the test piping. In other words, the opening / flow rate relationship obtained in the test facility can be commonly used in various field facilities with different pressure losses on the secondary side of the flow control valve, so that in the field facility, the flow rate of the controlled gas flowing through the field piping can be controlled to a desired flow rate by controlling the opening of the flow control valve based on the known opening / flow rate relationship without installing a relatively expensive flow meter.

[0008] Furthermore, the combustion control system includes a main fuel flow rate control mechanism as a flow rate control mechanism that controls the flow rate of main fuel gas as a gas to be controlled that flows through a main fuel pipe that is connected in communication with the burner as on-site piping, a secondary fuel flow rate control mechanism as a flow rate control mechanism that controls the flow rate of secondary fuel gas as a gas to be controlled that flows through a secondary fuel pipe that is connected in communication with the burner as on-site piping, and a combustion gas flow rate control mechanism as a flow rate control mechanism that controls the flow rate of combustion gas as a gas to be controlled that flows through a combustion gas pipe that is connected in communication with the burner as on-site piping, and the control unit controls the flow rate of the main fuel gas to a target flow rate using the main fuel flow rate control mechanism, controls the flow rate of the secondary fuel gas to the target flow rate using the secondary fuel flow rate control mechanism, and controls the flow rate of the combustion gas to the target flow rate using the combustion gas flow rate control mechanism, thereby realizing a combustion control system that can properly adjust the proportion of the secondary fuel gas in the fuel and also adjust the air ratio to a desired value even in a configuration in which a secondary fuel gas such as hydrogen or ammonia is mixed and burned with the main fuel.

[0009] As a result, the object of the present invention is to provide a combustion control system that maintains a simple configuration without a flow meter, thereby improving economy, and that can reduce manpower by automating various adjustments such as flow rate adjustment, while also being able to properly adjust the proportion of secondary fuel gas in the fuel and adjust the air ratio to a desired value even when secondary fuel gas such as hydrogen or ammonia is mixed and burned. Furthermore, this control does not require manual adjustment by an expert, which also reduces manpower and improves efficiency.

[0010] In the above characteristic configuration, the secondary side pressure adjustment unit is intended to adjust the pressure loss on the secondary side of the flow control valve, which may differ from site to site, to a predetermined value. Therefore, after the initial secondary pressure is set, the pressure on the secondary side outlet will not be readjusted even if the opening of the flow control valve changes and the pressure on the secondary side outlet fluctuates.

[0011] Further characteristic configurations of the combustion control system include: The flow rate control mechanism includes: In the test facility further including the second pressure gauge in the test piping, the memory unit of the control unit causes the controlled gas to flow through the test piping, and sets the pressure of the secondary side outlet to the initially set secondary pressure using the secondary side pressure adjustment unit while maintaining the flow rate control valve at the initially set opening, and then stores an opening-pressure relationship between the opening of the flow rate control valve and the secondary side pressure measured by the second pressure gauge while maintaining the pressure of the primary side inlet at the flow rate control pressure using the primary side pressure adjustment unit, In the on-site equipment further provided with the second pressure gauge in the on-site piping, the control unit causes the controlled gas to flow through the on-site piping, and sets the pressure of the secondary-side outlet to the initially set secondary pressure by the secondary-side pressure adjustment unit while maintaining the flow control valve at the initially set opening, and then, while maintaining the pressure of the primary-side inlet at the flow control pressure by the primary-side pressure adjustment unit, executes secondary-side pressure adjustment determination control to determine whether or not adjustment of the secondary-side pressure is necessary by comparing the secondary-side pressure measured by the second pressure gauge with a derived pressure derived from the opening of the flow control valve at the time of pressure measurement by the second pressure gauge and the opening-pressure relationship, and when it is determined in the secondary-side pressure adjustment determination control that adjustment of the secondary-side pressure is necessary, executes secondary-side pressure adjustment control by the secondary-side pressure adjustment unit to correct the secondary-side pressure based on the derived pressure derived from the opening of the flow control valve at the time of determination in the secondary-side pressure adjustment determination control and the opening-pressure relationship. The control unit is capable of executing the secondary-side pressure adjustment determination control and the secondary-side pressure adjustment control for the main fuel flow control mechanism, is capable of executing the secondary-side pressure adjustment determination control and the secondary-side pressure adjustment control for the secondary fuel flow control mechanism, and is capable of executing the secondary-side pressure adjustment determination control and the secondary-side pressure adjustment control for the combustion gas flow control mechanism.

[0012] In the control described so far, for example, when applied to a waste heat recovery burner, if the air head pressure changes between cold and warm conditions, or if the secondary side of the flow control valve becomes clogged with dust or other particles after long-term use, it may become difficult to adjust the flow rate appropriately.

[0013] Therefore, in the above characteristic configuration, in order to determine whether a situation has arisen in which appropriate flow rate adjustment is difficult, the secondary pressure adjustment determination control compares the secondary pressure measured by the second pressure gauge with the opening of the flow control valve when the pressure is measured by the second pressure gauge and the derived pressure derived from the opening-pressure relationship, and determines whether adjustment of the secondary pressure is necessary. When the situation described above has arisen, the pressure derived from the previously acquired opening-pressure relationship and the current opening of the flow rate adjustment valve will deviate from the secondary pressure currently measured by the second pressure gauge, and therefore it can be determined whether adjustment of the secondary pressure is necessary based on the presence or absence of this deviation. Furthermore, when the control unit determines in the secondary-side pressure adjustment determination control that adjustment of the secondary-side pressure is necessary, the secondary-side pressure adjustment unit executes secondary-side pressure adjustment control to correct the secondary-side pressure based on the derived pressure derived from the opening of the flow control valve at the time of determination in the secondary-side pressure adjustment determination control and the opening-pressure relationship.Therefore, by correcting the opening-pressure relationship to the opening-pressure relationship at the time of initial setting when the secondary-side pressure is set to the initially set secondary pressure in the on-site piping, the opening-flow rate relationship can also be adjusted to the opening-flow rate relationship at the time of initial setting. In this way, even if a situation arises in which it is difficult to adjust the flow rate appropriately in each burner, secondary pressure adjustment control can be performed to adjust the mixture ratio of the secondary fuel gas and the main fuel gas to the desired one while controlling the air ratio to the desired value, thereby realizing a combustion control system that can perform good combustion.

[0014] Further characteristic configurations of the combustion control system include: a mixing section that mixes the main fuel gas and the secondary fuel gas, with one of the main fuel gas and the secondary fuel gas serving as a drawing fluid and the other serving as a drawn fluid that is drawn in by the drawing fluid, the mixing section has a drawing fluid inlet which is an inlet for the drawing fluid and a drawn fluid inlet which is an inlet for the drawn fluid, a flow path switching mechanism that can switch between a first connection state in which the main fuel pipe is connected to the drawing fluid inlet and the secondary fuel pipe is connected to the drawn fluid inlet, and a second connection state in which the secondary fuel pipe is connected to the drawing fluid inlet and the main fuel pipe is connected to the drawn fluid inlet, The control unit executes the secondary-side pressure adjustment determination control for the main fuel flow rate control mechanism and the secondary fuel flow rate control mechanism when the flow path switching mechanism switches between the first connection state and the second connection state, and executes the secondary-side pressure adjustment control if it determines in the secondary-side pressure adjustment determination control that adjustment of the secondary-side pressure is necessary.

[0015] In a Venturi mixer serving as a mixing section, the flow of the drawn fluid is generated by negative pressure, which draws in the drawn fluid, thereby mixing the drawn fluid and the drawn fluid. Normally, the flow rate (flow velocity) of the main fuel gas is greater than the flow rate (flow velocity) of the secondary fuel gas, so the main fuel gas is the drawn fluid and the secondary fuel gas is the drawn fluid, but if the flow rates (flow velocity) of the main fuel gas and the secondary fuel gas are reversed, it may be preferable to use the main fuel gas as the drawn fluid and the secondary fuel gas as the drawn fluid. Therefore, according to the above characteristic configuration, a flow path switching mechanism is provided that can switch between a first connection state in which the main fuel pipe is connected to the inlet fluid inlet and the secondary fuel pipe is connected to the inlet fluid to be drawn in, and a second connection state in which the secondary fuel pipe is connected to the inlet fluid inlet and the main fuel pipe is connected to the inlet fluid to be drawn in.

[0016] However, when the flow path is switched by the flow path switching mechanism, the pressure loss state on the secondary side of the secondary pressure adjusting section changes, which may make it impossible to properly adjust the flow rate based on the opening-flow rate relationship. Therefore, when the flow path switching mechanism switches between the first connection state and the second connection state, the control unit executes secondary-side pressure adjustment determination control for the main fuel flow control mechanism and the secondary fuel flow control mechanism, and executes secondary-side pressure adjustment control if the secondary-side pressure adjustment determination control determines that adjustment of the secondary-side pressure is necessary.This allows the secondary-side pressure adjustment unit to absorb changes in the secondary-side pressure loss state of the secondary-side pressure adjustment unit that occur when the first connection state and the second connection state are switched, and therefore flow control by the flow adjustment valve based on the opening-flow rate relationship can be executed well in a form that controls to the desired flow rate.

[0017] Further characteristic configurations of the combustion control system include: The control unit controls the flow rate of the control-target gas using the same opening / flow rate relationship for different types of burners.

[0018] According to the above characteristic configuration, even when different types of burners (e.g., different pressure losses) are used in on-site equipment, the influence of different pressure losses of different burners can be eliminated by controlling the pressure at the secondary outlet of the flow control valve to the initial secondary pressure during initial setup using the secondary pressure adjustment unit, and a common opening / flow rate relationship can be used for different types of burners.

[0019] Further characteristic configurations of the combustion control system include: The control unit executes the secondary-side pressure regulation determination control and the secondary-side pressure regulation control using the opening-pressure relationship that is common to different types of burners.

[0020] According to the above characteristic configuration, even when different types of burners (for example, different pressure losses) are used in on-site equipment, a common opening / flow rate relationship can be used for the different types of burners, and secondary-side pressure adjustment determination control, or secondary-side pressure adjustment control in addition to secondary-side pressure adjustment determination control, can be performed, thereby realizing a combustion control system that exhibits the various effects described above.

[0021] Further characteristic configurations of the combustion control system include: An alarm notification unit is provided to notify an alarm to the outside, When it is determined in the secondary-side pressure adjustment determination control that adjustment of the secondary-side pressure is necessary, the control unit executes notification control to issue the alarm in the alarm notification unit.

[0022] According to the above characteristic configuration, when the control unit determines in the secondary side pressure adjustment determination control that adjustment of the secondary side pressure is necessary, it executes notification control to issue an alarm in the alarm notification unit. Therefore, for example, the user can be notified early on that there is a possibility that dust has become clogged on the secondary side of the flow control valve due to long-term use, and burner maintenance can be carried out with ample time, taking into account the usage conditions of the burner. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic configuration diagram of a combustion control system according to an embodiment. [Figure 2] FIG. 1 is a schematic configuration diagram showing a test facility according to an embodiment. [Figure 3] FIG. 10 is a graph showing the relationship between opening degree and flow rate for combustion air. [Figure 4] FIG. 4 is a graph showing the relationship between the head pressure and the flow rate of the burner. [Figure 5] FIG. 10 is a graph showing the relationship between opening degree and flow rate for fuel gas. [Figure 6] FIG. 10 is a graph showing an example of the relationship between opening degree and flow rate of a gas to be controlled. [Figure 7] FIG. 10 is a graph showing an example of the relationship between opening degree and pressure of a gas to be controlled. [Figure 8] FIG. 3 is a circuit diagram showing a first connection state of a mixer and a flow path switching mechanism according to the embodiment. [Figure 9] FIG. 10 is a circuit diagram showing a second connection state of the mixer and the flow path switching mechanism according to the embodiment. [Figure 10] FIG. 10 is a circuit diagram showing a first connection state of a mixing section and a flow path switching mechanism according to another embodiment. [Figure 11] FIG. 10 is a circuit diagram showing a second connection state of the mixer and the flow path switching mechanism according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] The combustion control system 300 according to an embodiment of the present invention maintains a simple configuration without a flow meter, thereby improving economy, and also reduces manpower by automating various adjustments such as flow rate adjustment. However, even when a secondary fuel gas such as hydrogen or ammonia is mixed and burned, the ratio of the secondary fuel gas in the fuel can be suitably adjusted, and the air ratio can also be adjusted to a desired value. A combustion control system 300 according to this embodiment will be described below with reference to FIGS.

[0025] As shown in FIG. 1, the combustion control system 300 according to this embodiment is configured to include a main fuel flow control mechanism 100 for a main fuel gas G1 (e.g., city gas 13A: an example of a gas to be controlled) as a fuel gas, a secondary fuel flow control mechanism 500 for a secondary fuel gas G2 (e.g., hydrogen or ammonia: an example of a gas to be controlled) as a fuel gas, a flow control mechanism 200 for combustion air (an example of a combustion gas and a gas to be controlled) as an oxidizer for the fuel gas, a control device S realized in a form in which hardware and software work together, and a burner BNa, and is configured to heat the inside of an industrial furnace R to a predetermined temperature. Furthermore, the combustion control system 300 according to this embodiment is a system that can control the flow rate of combustion air to a desired value without using a flow meter, even in exhaust heat recovery burners (burners in which combustion gas is preheated by combustion exhaust gas), such as recuperator burners and regenerative burners, in which the pressure loss of the combustion air flowing through the burner changes significantly between warm and cold states.

[0026] As shown in FIG. 1 , the main fuel flow rate control mechanism 100 (an example of a flow rate control mechanism) for the main fuel gas G1 is provided in a main fuel pipe H1 (an example of an on-site pipe) through which the main fuel gas G1 flows, and includes a main fuel flow rate control valve RVg1 whose opening is controlled by a control command from a control unit S1 provided in the control device S, and a secondary fuel pressure gauge P2g1 provided on the secondary side of the main fuel flow rate control valve RVg1 in the main fuel pipe H1, which is capable of adjusting the pressure of the secondary outlet based on the measurement result of a second main fuel pressure gauge P2g1 provided at the secondary outlet of the main fuel flow rate control valve RVg1. The control device S includes a main fuel pressure adjusting unit PVg1 (an example of a secondary-side pressure adjusting unit), a main governor GA1 as a primary-side pressure adjusting unit that is provided on the primary side of the main fuel flow rate control valve RVg1 in the main fuel pipe H1 and that can adjust the pressure of the primary-side inlet based on the measurement result of a first main fuel pressure gauge P1g1 provided at the primary-side inlet of the main fuel flow rate control valve RVg1, and a memory unit S3 that stores an opening-main fuel flow rate relationship (illustrated in FIG. 5 ) between the opening of the main fuel flow rate control valve RVg1 and the flow rate of fuel flowing through the main fuel pipe H1, the details of which will be described later. The memory unit S3 is provided integrally with the control device S. More specifically, the main fuel pipe H1 is provided with, from the upstream side, a second safety solenoid valve SV2, a first safety solenoid valve SV1, a main governor GA1, a first main fuel pressure gauge P1g1, a main fuel flow control valve RVg1, a second main fuel pressure gauge P2g1, a secondary side main fuel pressure adjustment unit PVg1, and a burner BNa (e.g., an exhaust heat recovery burner), in the order listed. With this configuration, in a main fuel field facility 100a provided with a main fuel piping H1 and including a main fuel flow rate control valve RVg1, a secondary-side main fuel pressure adjustment unit PVg1, and a main governor GA1 as a primary-side pressure adjustment unit, the main fuel flow rate control mechanism 100 sets the pressure of the secondary-side outlet to a predetermined initially set secondary pressure (for example, 4 kPaG) by the secondary-side main fuel pressure adjustment unit PVg1 while maintaining the main fuel flow rate control valve RVg1 at a predetermined initially set aperture (for example, 100% aperture) in a state where the main fuel gas G1 is flowing through the main fuel piping H1, and then, while maintaining the pressure of the primary-side inlet at a predetermined flow rate control pressure (for example, 8 kPaG) by the main governor GA1, the main fuel flow rate control valve RVg1 controls the aperture of the main fuel flow rate control valve RVg1 based on the aperture-main fuel flow rate relationship stored in a memory unit S3 (illustrated in FIG. 5: an example of the aperture-flow rate relationship), to control the flow rate of the main fuel gas G1 to a target flow rate.

[0027] Here, as the secondary-side main fuel pressure adjustment unit PVg1, an electromagnetic pressure adjustment valve that adjusts the secondary-side pressure of the main fuel flow rate control valve RVg1 of the main fuel pipe H1 by varying the opening degree of a valve element provided in the main fuel pipe H1 is preferably used.

[0028] As shown in FIG. 1, the secondary fuel flow rate control mechanism 500 (an example of a flow rate control mechanism) for the secondary fuel gas G2 is provided in a secondary fuel pipe H3 (an example of an on-site pipe) through which the secondary fuel gas G2 flows, and includes a secondary fuel flow rate control valve RVg2 whose opening is controlled by a control command from a control unit S1 provided in the control device S, and a secondary fuel pressure gauge P2g2 provided on the secondary side of the secondary fuel flow rate control valve RVg2 in the secondary fuel pipe H3, which is capable of adjusting the pressure of the secondary outlet based on the measurement result of a second secondary fuel pressure gauge P2g2 provided at the secondary outlet of the secondary fuel flow rate control valve RVg2. The control device S includes a secondary fuel pressure adjusting unit PVg2 (an example of a secondary pressure adjusting unit), a secondary governor GA2 as a primary pressure adjusting unit that is provided on the primary side of the secondary fuel flow rate control valve RVg2 in the secondary fuel pipe H3 and that can adjust the pressure of the primary inlet based on the measurement result of a first secondary fuel pressure gauge P1g2 provided at the primary inlet of the secondary fuel flow rate control valve RVg2, and a memory unit S3 that stores an opening-secondary fuel flow rate relationship (illustrated in FIG. 5) between the opening of the secondary fuel flow rate control valve RVg2 and the flow rate of fuel flowing through the secondary fuel pipe H3, as will be described in detail later. Note that the memory unit S3 is provided integrally with the control device S. More specifically, the secondary fuel pipe H3 is provided with, from the upstream side, a fourth safety solenoid valve SV4, a third safety solenoid valve SV3, a secondary governor GA2, a first secondary fuel pressure gauge P1g2, a secondary fuel flow control valve RVg2, a second secondary fuel pressure gauge P2g2, a secondary side secondary fuel pressure adjustment unit PVg2, and a burner BNa (e.g., an exhaust heat recovery burner), in the order listed. With this configuration, in a secondary fuel field facility 500a provided with a secondary fuel piping H3 and including a secondary fuel flow control valve RVg2, a secondary-side secondary fuel pressure adjustment unit PVg2, and a secondary governor GA2 as a primary-side pressure adjustment unit, the secondary fuel flow control mechanism 500, while the secondary fuel gas G2 is flowing through the secondary fuel piping H3, sets the pressure of the secondary-side outlet to a predetermined initial setting secondary pressure (e.g., 4 kPaG) by the secondary-side secondary fuel pressure adjustment unit PVg2 with the secondary fuel flow control valve RVg2 maintained at a predetermined initial setting (e.g., 100% opening), and then, while the pressure of the primary-side inlet is maintained at a predetermined flow control pressure (e.g., 8 kPaG) by the secondary governor GA2, controls the aperture of the secondary fuel flow control valve RVg2 based on the aperture-secondary fuel flow rate relationship stored in a memory unit S3 (illustrated in FIG. 5: one example of the aperture-flow rate relationship), to control the flow rate of the secondary fuel gas G2 to a target flow rate.

[0029] Here, as the secondary side secondary fuel pressure adjustment section PVg2, an electromagnetic pressure adjustment valve that adjusts the secondary side pressure of the secondary fuel flow control valve RVg2 of the secondary fuel pipe H3 by varying the opening degree of a valve body provided in the secondary fuel pipe H3 is preferably used.

[0030] As shown in FIG. 1, the air flow control mechanism 200 (an example of a flow control mechanism, a combustion gas flow control mechanism) for combustion air is provided in a combustion gas pipe H2 (an example of an on-site pipe) through which combustion air flows, and includes an air flow control valve RVa whose opening is controlled by a control command from a control unit S1 provided in the control device S, and a second air pressure gauge P2a provided on the secondary side of the air flow control valve RVa in the combustion gas pipe H2, which is capable of adjusting the pressure of the secondary outlet based on the measurement result of the second air pressure gauge P2a provided at the secondary outlet of the air flow control valve RVa. the combustion gas pipe H2 includes a secondary air pressure adjusting unit PVa (an example of a secondary pressure adjusting unit), an inverter-type blower B as a primary pressure adjusting unit that is provided on the primary side of the air flow control valve RVa in the combustion gas pipe H2 and that can adjust the pressure of the primary inlet based on the measurement result of a first air pressure gauge P1a provided at the primary inlet of the air flow control valve RVa, and a memory unit S3 that stores the aperture-air flow rate relationship (shown in FIG. 3) between the aperture of the air flow control valve RVa and the flow rate of air flowing through the combustion gas pipe H2, as will be described in detail later. The memory unit S3 is provided integrally with the control device S. More specifically, the combustion gas pipe H2 is provided with, in order from the upstream side, a blower B, a first air pressure gauge P1a, an air flow control valve RVa, a second air pressure gauge P2a, a secondary air pressure adjustment unit PVa, a third air pressure gauge P3a, and a burner BNa (e.g., an exhaust heat recovery burner). Here, the third air pressure gauge P3a measures the head pressure of the burner BN at the primary inlet of the burner BNa in the combustion gas pipe H2, and is configured to be able to check whether the relationship between the head pressure and the flow rate for each of the burners 1 to 3 is consistent with a known value, as shown in Fig. 4. In addition, as the secondary air pressure adjustment unit PVa, an electromagnetic pressure adjustment valve is preferably used which adjusts the secondary pressure of the air flow control valve RVa in the combustion gas pipe H2 by varying the opening of a valve element provided in the combustion gas pipe H2.

[0031] With this configuration, the air flow control mechanism 200 is an air field facility 200a provided with an air flow control valve RVa, a secondary air pressure adjustment unit PVa as a secondary pressure adjustment unit, and a blower B as a primary pressure adjustment unit in a combustion gas pipe H2, in which a control unit S1 causes combustion air to flow through the combustion gas pipe H2, and while maintaining the air flow control valve RVa at a predetermined initial setting opening (for example, 100%), the secondary air pressure adjustment unit PVa sets the pressure of the secondary outlet to a predetermined initial setting secondary pressure (for example, 4 kPaG), and then, while maintaining the pressure of the primary inlet to a predetermined flow control pressure (for example, 8 kPaG) with the blower B, controls the opening of the air flow control valve RVa based on the opening-air flow rate relationship (shown in FIG. 3: an example of the opening-flow rate relationship) stored in a memory unit S3, thereby controlling the flow rate of the combustion air to a target flow rate.

[0032] Now, the test equipment 400 that acquires the opening-flow rate relationship stored in the storage unit S3 will be described with reference to FIG. The test equipment 400 is provided separately from the main fuel field equipment 100a (an example of field equipment), the secondary fuel field equipment 500a (an example of field equipment), and the air field equipment 200a (an example of field equipment) for the purpose of obtaining in advance the above-mentioned opening / main fuel flow rate relationship and opening / secondary fuel flow rate relationship (illustrated in Figure 5) and opening / air flow rate relationship (shown in Figure 3).When the fluid to be controlled is main fuel gas G1, a test pipe H having the same diameter as the main fuel pipe H1 is used; when the fluid to be controlled is secondary fuel gas G2, a test pipe H having the same diameter as the secondary fuel pipe H3 is used; and when the fluid to be controlled is combustion air, a test pipe H having the same diameter as the combustion gas pipe H2 is used. Below, we will explain configuration examples and methods for obtaining the opening / main fuel flow rate relationship for the main fuel gas G1, but configuration examples and methods for obtaining the opening / secondary fuel flow rate relationship for the secondary fuel gas G2, and configuration examples and methods for obtaining the opening / air flow rate relationship for combustion air can also be obtained using substantially the same configuration examples and methods.

[0033] 2, the test facility 400 is provided with a fuel flow control valve RV, a butterfly valve BV as a secondary pressure adjustment unit, an inverter-type blower B as a primary pressure adjustment unit, and a flow meter F that measures the flow rate of the test pipe H, on a test pipe H having the same diameter as the main fuel pipe H1. More specifically, from the upstream side, the blower B, the flow meter F, a first test pressure gauge P1 that measures the pressure at the primary inlet of the fuel flow control valve RV, the fuel flow control valve RV, a second test pressure gauge P2 that measures the pressure at the secondary outlet of the fuel flow control valve RV, the butterfly valve BV, and a test burner BN (for example, a waste heat recovery burner) are provided in this order. In the test facility 400, a control unit Ss1 provided in the control device Ss flows the main fuel gas G1 through the test piping H, and while maintaining the fuel flow control valve RV (an example of a flow control valve) at a predetermined initial setting opening (for example, 100%: the same opening as the initial setting opening in the main fuel field facility 100a), sets the pressure of the secondary side outlet to a predetermined initial setting secondary pressure (for example, 4 kPaG: the same pressure as the initial setting secondary pressure in the main fuel field facility 100a) using the butterfly valve BV, and then, while maintaining the pressure of the primary side inlet to a predetermined flow control pressure (for example, 8 kPaG: the same pressure as the flow control pressure in the main fuel field facility 100a) using the blower B, stores in a memory unit Ss3 provided in the control device Ss the opening-main fuel flow rate relationship (in the case of secondary fuel gas, the opening-secondary fuel flow rate relationship; in the case of combustion air, the opening-air flow rate relationship) between the opening of the fuel flow control valve RV and the flow rate measured by the flow meter F.

[0034] 1, in the combustion control system 300, the control unit S1 first acquires the measurement results of a thermocouple ND provided in the industrial furnace R, derives a target output and a target air ratio of the burner BNa for setting the temperature inside the furnace to a target temperature based on the measurement results, controls the flow rate of combustion air to obtain the target output and target air ratio, and controls the flow rates of the main fuel gas G1 and the secondary fuel gas G2 to obtain the target air ratio corresponding to the flow rate of combustion air. The ratio (degree of mixed combustion) of the main fuel gas G1 and the secondary fuel gas G2 is adjusted as appropriate by the control unit S1. By adopting this configuration, the openings of the main fuel flow rate control valve RVg1, the secondary fuel flow rate control valve RVg2, and the air flow rate control valve RVa can be controlled for burners with different pressure losses (burners 1 to 3 in Figures 3 to 5) based on a common opening-air flow rate relationship (relationship in Figure 3) and a common opening-main fuel flow rate relationship (opening-secondary fuel flow rate relationship) (relationship in Figure 5). It should be noted that while control is being continuously executed, the secondary pressures of the main fuel flow control valve RVg1, the auxiliary fuel flow control valve RVg2, and the air flow control valve RVa fluctuate from the initially set secondary pressure depending on the progress of control toward the target output, the target air ratio, etc., but the primary pressures of the main fuel flow control valve RVg1, the auxiliary fuel flow control valve RVg2, and the air flow control valve RVa are kept constant by the main governor GA1, the auxiliary governor GA2, and the blower B which serve as primary-side pressure control mechanisms.

[0035] According to the control method described above, the opening-flow rate relationship, which is the relationship between the opening of the flow control valve and the flow rate of the gas to be controlled as shown in Figure 6, can be obtained, and the flow rate of the gas to be controlled can be controlled using this opening-flow rate relationship without providing a flow meter. However, for example, if the burner BNa is a waste heat recovery burner or the like and the pressure loss of the combustion air as the controlled gas changes over time between when the burner BNa is cold and when it is warm, or if dust or the like clogs the passage through which the controlled gas of the burner BNa flows, causing the pressure loss of the controlled gas to change over time, the aperture-flow rate relationship will change. Specifically, if dust or the like clogs the passage through which the controlled gas of the burner BNa flows, the aperture-flow rate relationship (graph) shown in Figure 6 will have a lower flow rate at a predetermined aperture, resulting in an overall downward shift. Therefore, if the control device S controls the aperture of the flow control valve based on the aperture-flow rate relationship before the shift, the flow rate of the output controlled gas will differ from the desired flow rate.

[0036] Therefore, in addition to the configurations described above, the above-mentioned test facility 400, main fuel flow rate control mechanism 100 (main fuel field facility 100a), secondary fuel flow rate control mechanism 500 (secondary fuel field facility 500a), air flow rate control mechanism 200 (air field facility 200a), and combustion control system 300 are configured as follows. Incidentally, as described above, for the test facility 400, a configuration example and method relating to the main fuel gas G1 will be described, but the configuration example and method relating to the secondary fuel gas G2 and the configuration example and method relating to the combustion air can also be substantially the same configuration example and method.

[0037] In the test facility 400, a control unit Ss1 provided in the control device Ss flows the main fuel gas G1 through the test piping H, and while maintaining the fuel flow control valve RV at a predetermined initial setting opening (for example, 100%: the same opening as the initial setting opening in the main fuel field facility 100a), sets the pressure of the secondary side outlet to a predetermined initial setting secondary pressure (for example, 4 kPaG: the same pressure as the initial setting secondary pressure in the main fuel field facility 100a) using the butterfly valve BV, and then, while maintaining the pressure of the primary side inlet to a predetermined flow control pressure (for example, 8 kPaG: the same pressure as the flow control pressure in the main fuel field facility 100a) using the blower B, stores in a memory unit Ss3 an opening-main fuel pressure relationship (an example of an opening-pressure relationship, for example, the relationship shown in FIG. 7: in the case of secondary fuel gas, the opening-secondary fuel pressure relationship, and in the case of combustion air, the opening-air pressure relationship) between the opening of the fuel flow control valve RV and the secondary side pressure measured by the second test pressure gauge P2.

[0038] In the main fuel field facility 100a, the control unit S1, while flowing the main fuel gas G1 through the main fuel piping H1, sets the pressure of the secondary-side outlet to a predetermined initially set secondary pressure (for example, 4 kPaG) by the secondary-side main fuel pressure adjustment unit PVg1 while maintaining the main fuel flow rate control valve RVg1 at a predetermined initially set opening (for example, 100% opening), and then controls the flow rate of the main fuel gas G1 to a target flow rate while maintaining the pressure of the primary-side inlet at a predetermined flow rate control pressure (for example, 8 kPaG) by the main governor GA1, and executes secondary-side pressure adjustment determination control to determine whether adjustment of the secondary-side pressure is necessary by comparing the secondary-side pressure measured by the second main fuel pressure gauge P2g1 with the derived pressure derived from the aperture of the main fuel flow rate control valve RVg1 at the time of pressure measurement by the second main fuel pressure gauge P2g1 and the aperture-main fuel pressure relationship.

[0039] For example, in the secondary-side pressure adjustment determination control, the control unit S1 determines that adjustment of the secondary-side pressure is necessary if the absolute value of the difference between the secondary-side pressure measured by the second main fuel pressure gauge P2g1 and the derived pressure derived from the opening of the main fuel flow rate control valve RVg1 when the pressure is measured by the second main fuel pressure gauge P2g1 and the relationship between the opening and the main fuel pressure is divided by the pressure derived from the opening of the main fuel flow rate control valve RVg1 when the pressure is measured by the second main fuel pressure gauge P2g1 and the relationship between the opening and the main fuel pressure and multiplied by 100 continuously exceeds a predetermined error range (a value of approximately −20% to 20%: for example, 5%) for a predetermined error determination time or more (a value of approximately 3 seconds to 60 seconds: for example, 3 seconds).

[0040] Furthermore, when the control unit S1 determines in the secondary-side pressure adjustment determination control that adjustment of the secondary-side pressure is necessary, the control unit S1 executes secondary-side pressure adjustment control, which corrects the secondary-side pressure by the secondary-side main fuel pressure adjustment unit PVg1 based on the opening of the main fuel flow rate control valve RVg1 at the time of determination in the secondary-side pressure adjustment determination control and the derived pressure derived from the opening-main fuel pressure relationship.

[0041] For example, when executing the secondary-side pressure regulation control, the control unit S1 controls the secondary-side pressure to become the derived pressure derived from the opening of the main fuel flow rate control valve RVg1 and the opening-main fuel pressure relationship at the time of determination in the secondary-side pressure regulation determination control. More specifically, the control unit S1 corrects the secondary-side pressure by the secondary-side main fuel pressure regulation unit PVg1 so that the absolute value of the difference between the secondary-side pressure and the derived pressure falls within a predetermined error range (a value of about −1.0 kPa to 1.0 kPa: for example, 0.05 kPa) continuously for at least a predetermined stabilization time (a time of about 2 seconds to 60 seconds: for example, 2 seconds).

[0042] Incidentally, the control unit S1 also performs secondary-side pressure adjustment determination control and secondary-side pressure adjustment control for the secondary fuel flow control mechanism 500 (secondary fuel field equipment 500a) and the air flow control mechanism 200 (air field equipment 200a) using substantially the same configuration and method as for the main fuel flow control mechanism 100 (main fuel field equipment 100a), so explanations thereof will be omitted here.

[0043] Furthermore, in addition to the configuration and control described above, the combustion control system 300 can be configured to perform secondary-side pressure adjustment determination control and secondary-side pressure adjustment control for the main fuel gas G1, secondary-side pressure adjustment determination control and secondary-side pressure adjustment control for the secondary fuel gas G2, and secondary-side pressure adjustment determination control and secondary-side pressure adjustment control for the combustion air, using the main fuel flow rate control mechanism 100, the secondary fuel flow rate control mechanism 500, and the air flow rate control mechanism 200.

[0044] With the above configuration, even if the burner BNa is a waste heat recovery burner or the like and the pressure loss of the combustion air as the gas to be controlled changes over time when the burner is cold and when it is warm, or even if the flow path of the gas to be controlled in the burner BNa is clogged with dust or the like and the pressure loss of the gas to be controlled changes over time, causing the opening-flow rate relationship to change, the flow rate of the gas to be controlled can be appropriately controlled to the desired flow rate by correction.

[0045] In addition, the control unit S1 can control the flow rate of the gas to be controlled using a common opening / flow rate relationship for different types of burners BNa, and can also perform secondary pressure adjustment judgment control and secondary pressure adjustment control using a common opening / pressure relationship for different types of burners BNa.

[0046] Furthermore, the above-described flow rate control mechanisms 100, 200, 500 and combustion control system 300 are each provided with a speaker KH (an example of an alarm notification unit) that issues an alarm to the outside, and when the control unit S1 determines in the secondary-side pressure adjustment determination control that adjustment of the secondary-side pressure is necessary, it executes notification control to issue an alarm through the speaker KH. This allows the user to take measures such as quickly formulating a maintenance plan based on that fact, for example, when it is determined that adjustment of the secondary-side pressure is necessary due to clogging of the flow path of the controlled gas of the burner BNa with dust or the like.

[0047] In the combustion control system 300 described so far, depending on the mixed-fuel ratio, there are cases where the flow rate (flow velocity) of the main fuel gas G1 is greater than the flow rate (flow velocity) of the secondary fuel gas G2, and cases where the flow rate (flow velocity) of the main fuel gas G1 is smaller than the flow rate (flow velocity) of the secondary fuel gas G2. Here, if the mixing section provided at the confluence section G is a Venturi mixer that mixes the inflow fluid and the inflow fluid with the inflow fluid having a large flow rate (flow velocity), if one of the main fuel gas G1 and the secondary fuel gas G2 is fixed as the inflow fluid and the other is fixed as the inflow fluid that is drawn in by the inflow fluid, there is a risk that the main fuel gas G1 and the secondary fuel gas G2 will not be able to be mixed properly if the flow rates (flow velocities) of the main fuel gas G1 and the secondary fuel gas G2 are reversed.

[0048] Therefore, the combustion control system 300 according to this embodiment is provided with a venturi mixer BM (an example of a mixing section) that mixes the main fuel gas G1 and the secondary fuel gas G2, with either the main fuel gas G1 or the secondary fuel gas G2 as an inlet and the other as a drawn fluid that is drawn in by the inlet fluid, and the venturi mixer BM has an inlet for the inlet fluid, an inlet for the drawn fluid, a drawn fluid inlet BMb, and is provided with a flow path switching mechanism RK that can be switched between a first connection state (connection state shown in FIG. 8) in which the main fuel pipe H1 is connected to the inlet for the inlet for the secondary fuel pipe H3 and the drawn fluid inlet BMb, and a second connection state (connection state shown in FIG. 9) in which the secondary fuel pipe H3 is connected to the inlet for the inlet for the secondary fuel pipe H1 and the drawn fluid inlet BMb.

[0049] Specifically, the main fuel pipe H1 includes a main fuel main pipe H1b connected to the drawing fluid inlet BMa, and a main fuel sub-pipe H1a branched from the main fuel main pipe H1b at a first branch section SZ1 and connected to the drawn fluid inlet BMb, as well as a third switching valve KV3 downstream of the first branch section SZ1 of the main fuel main pipe H1b and a fourth switching valve KV4 in the main fuel sub-pipe H1a. Furthermore, the secondary fuel pipe H3 includes a secondary fuel main pipe H3b connected to the drawn fluid inlet BMb, and a secondary fuel sub-pipe H3a branching from the secondary fuel main pipe H3b at a second branch section SZ2 and connecting to the drawn fluid inlet BMa, as well as a first switching valve KV1 downstream of the second branch section SZ2 of the secondary fuel main pipe H3b and a second switching valve KV2 in the secondary fuel sub-pipe H3a. The control unit S1 controls the flow path switching mechanism RK so that when the flow rate (flow velocity) of the main fuel gas G1 is greater than the flow rate (flow velocity) of the secondary fuel gas G2, the first switching valve KV1 and the third switching valve KV3 are in an open state and the second switching valve KV2 and the fourth switching valve KV4 are in a closed state to set the first connection state, and when the flow rate (flow velocity) of the secondary fuel gas G2 is smaller than the flow rate (flow velocity) of the main fuel gas G1, the control unit S1 controls the flow path switching mechanism RK so that the first switching valve KV1 and the third switching valve KV3 are in a closed state and the second switching valve KV2 and the fourth switching valve KV4 are in an open state to set the second connection state.

[0050] In addition, when the flow path switching mechanism RK switches between the first connection state and the second connection state, the control unit S1 executes secondary-side pressure adjustment determination control for the main fuel flow rate control mechanism 100 and the secondary fuel flow rate control mechanism 500, and executes secondary-side pressure adjustment control if the secondary-side pressure adjustment determination control determines that adjustment of the secondary-side pressure is necessary.

[0051] [Another embodiment] (1) In the above embodiment, combustion air is used as the combustion gas. However, for example, oxygen-enriched gas may be used as the combustion gas.

[0052] (2) The combustion control system 300 is not limited to heating of the industrial furnace R, but can be widely applied to burners of glass melting furnaces, metal forging facilities, and the like. Furthermore, the flow rate control mechanism 100 can be suitably incorporated into systems that control the flow rates of various gases, regardless of whether the system is a combustion device such as a burner.

[0053] (3) Although not described in detail in the above embodiment, in an environment where the temperatures in the main fuel field equipment 100a, the secondary fuel field equipment 500a, and the air field equipment 200a change significantly, the following configuration and control may be adopted. That is, in the test facility 400, the opening / flow rate relationship can be obtained for each temperature of the gas to be controlled flowing through the test pipe H, and flow rate control of the flow rate to be controlled can be performed in the main fuel field facility 100a, the secondary fuel field facility 500a, and the air field facility 200a based on the opening / flow rate relationship corresponding to the temperature of the gas to be controlled measured in the field pipes H1, H2, and H3.

[0054] (4) In the above embodiment, a configuration example in which secondary pressure regulation control is executed is shown, but the secondary pressure regulation control does not necessarily have to be executed. In this case, for example, the control device S may employ a configuration in which, when it is determined in the secondary pressure adjustment determination control that adjustment of the secondary pressure is necessary, an alarm is issued.

[0055] (5) In the above embodiment, as shown in FIGS. 8 and 9, a configuration in which one venturi mixer BM is provided as the mixing section and a corresponding flow path switching mechanism RK is provided is exemplified. As another configuration, as shown in FIGS. 10 and 11, two venturi mixers BM1 and BM2 may be provided, and a corresponding flow path switching mechanism RK may also be provided. Specifically, the system is provided with a first venturi mixer BM1 and a second venturi mixer BM2 that mix the main fuel gas G1 and the secondary fuel gas G2, with either one of the main fuel gas G1 and the secondary fuel gas G2 as an intake fluid and the other as a fluid to be drawn in by the intake fluid. The first venturi mixer BM1 has a first drawing fluid inlet BM1a, which is an inlet for the drawing fluid, and a first drawn fluid inlet BM1b, which is an inlet for the drawn fluid, and the second venturi mixer BM2 has a second drawing fluid inlet BM2a, which is an inlet for the drawing fluid, and a second drawn fluid inlet BM2b, which is an inlet for the drawn fluid. Furthermore, the flow path switching mechanism RK switches between a first connection state (connection state shown in Figure 10) in which the main fuel pipe H1 is connected to the first inlet fluid inlet BM1a and the secondary fuel pipe H3 is connected to the first inlet fluid inlet BM1b, and a second connection state (connection state shown in Figure 9) in which the secondary fuel pipe H3 is connected to the second inlet fluid inlet BM2a and the main fuel pipe H1 is connected to the second inlet fluid inlet BM2b.

[0056] Specifically, the main fuel pipe H1 includes a main fuel main pipe H1b connected to the first drawing fluid inlet BM1a, and a main fuel sub-pipe H1a branched off from the main fuel main pipe H1b via a sixth three-way valve KV6 provided at the branching point and connected to the second drawn fluid inlet BM2b. Furthermore, the secondary fuel pipe H3 is provided with a secondary fuel main pipe H3b connected to the first drawn fluid inlet BM1b, and a secondary fuel sub-pipe H3a branching off from the secondary fuel main pipe H3b via a fifth three-way valve KV5 provided at the branching point and connecting to the second drawn fluid inlet BM2a. The control unit S1 controls the flow path switching mechanism RK to switch between the first connection state and the second connection state in a manner that switches the fifth three-way valve KV5 and the sixth three-way valve KV6.

[0057] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, as long as no contradictions arise. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these, and can be modified as appropriate within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0058] The combustion control system of the present invention maintains a simple configuration without a flow meter, improving economy, and can reduce manpower by automating various adjustments such as flow rate adjustment. Even when mixing and burning secondary fuel gases such as hydrogen and ammonia, the system can effectively adjust the proportion of the secondary fuel gas in the fuel and can also adjust the air ratio to a desired value. [Explanation of symbols]

[0059] 100: Main fuel flow control mechanism 100a: Main fuel field equipment 200: Air flow control mechanism 200a: Air site equipment 300: Combustion control system 400: Testing facilities 500: Secondary fuel flow control mechanism 500a: Secondary fuel field equipment BM1: First Venturi Mixer BM1a: First intake fluid inlet BM1b: 1st drawn fluid inlet BM2: Second Venturi Mixer BM2a: Second intake fluid inlet BM2b: Second drawn fluid inlet BMa: Inlet fluid inlet BMb: Inlet for drawn fluid BN: Burner BNa: Burner G1: Main fuel gas G2: Secondary fuel gas GA1: Main governor GA2: Vice Governor H: Test piping H1: Main fuel pipe H2: Combustion gas piping H3:Auxiliary fuel pipe KH: Speaker KV1: First switching valve KV2: Second switching valve KV3: Third switching valve KV4: 4th switching valve KV5: 5th three-way valve KV6: 6th three-way valve P1: First test pressure gauge P1a: 1st air pressure gauge P1g1: 1st main fuel pressure gauge P1g2: 1st auxiliary fuel pressure gauge P2: Second test pressure gauge P2a: Second air pressure gauge P2g1: Second main fuel pressure gauge P2g2: Second auxiliary fuel pressure gauge P3a: Third air pressure gauge PVa: Secondary air pressure adjustment section PVg1: Secondary side main fuel pressure regulator PVg2: Secondary fuel pressure regulator RK: Flow path switching mechanism RV: Fuel flow control valve RVa: Air flow control valve RVg1: Main fuel flow control valve RVg2: Secondary fuel flow control valve S: Control device S1: Control unit S3: Storage section

Claims

1. A combustion control system using a flow rate control mechanism including a control unit that controls the flow rate of a control target gas, which is either a fuel gas that is a main fuel gas or a secondary fuel gas, or a combustion gas that serves as an oxidizer for the fuel gas, The flow rate control mechanism includes: a flow control valve that is provided in an on-site piping through which the gas to be controlled flows, and whose opening is controlled by a control command from the control unit; a secondary-side pressure adjusting unit that is provided on the secondary side of the flow control valve in the on-site piping and that is capable of adjusting the pressure of the secondary-side outlet based on a measurement result of a second pressure gauge that is provided at a secondary-side outlet of the flow control valve; a primary-side pressure adjusting unit that is provided on the primary side of the flow control valve in the on-site piping and that is capable of adjusting the pressure of the primary-side inlet based on a measurement result of a first pressure gauge that is provided at the primary-side inlet of the flow control valve; In a test facility comprising the flow control valve, the secondary pressure adjustment unit, and the primary pressure adjustment unit in a test pipe having the same diameter as the on-site pipe, and a flow meter for measuring a flow rate of the test pipe, the control unit causes the controlled gas to flow through the test pipe, and sets the pressure of the secondary outlet to a predetermined initial set secondary pressure with the secondary pressure adjustment unit while maintaining the flow control valve at a predetermined initial set opening, and then comprises a memory unit that stores an opening / flow rate relationship between the opening of the flow control valve and the flow rate measured by the flow meter while maintaining the pressure of the primary inlet at a predetermined flow control pressure with the primary pressure adjustment unit, In the on-site facility provided with the flow control valve, the secondary-side pressure adjustment unit, and the primary-side pressure adjustment unit in the on-site piping, the control unit causes the gas to be controlled to flow through the on-site piping, and sets the pressure of the secondary-side outlet to the initially set secondary pressure using the secondary-side pressure adjustment unit while maintaining the flow control valve at the initially set opening, and then, while maintaining the pressure of the primary-side inlet at the flow control pressure using the primary-side pressure adjustment unit, controls the opening of the flow control valve based on the opening-flow rate relationship stored in the memory unit to control the flow rate of the gas to be controlled to a target flow rate, a main fuel flow rate control mechanism serving as the flow rate control mechanism for controlling a flow rate of the main fuel gas serving as the gas to be controlled that flows through a main fuel pipe connected in communication with a burner serving as the on-site pipe; a secondary fuel flow rate control mechanism serving as the flow rate control mechanism for controlling a flow rate of the secondary fuel gas as the gas to be controlled that flows through a secondary fuel pipe that is connected in communication with the burner as the on-site pipe; a combustion gas flow rate control mechanism as the flow rate control mechanism for controlling the flow rate of the combustion gas as the control target gas flowing through a combustion gas pipe connected in communication with the burner as the on-site pipe, a combustion control system in which the control unit controls the flow rate of the main fuel gas to the target flow rate using the main fuel flow rate control mechanism, controls the flow rate of the secondary fuel gas to the target flow rate using the secondary fuel flow rate control mechanism, and controls the flow rate of the combustion gas to the target flow rate using the combustion gas flow rate control mechanism.

2. The flow rate control mechanism includes: In the test facility further including the second pressure gauge in the test piping, the memory unit of the control unit causes the controlled gas to flow through the test piping, and sets the pressure of the secondary side outlet to the initially set secondary pressure using the secondary side pressure adjustment unit while maintaining the flow rate control valve at the initially set opening, and then stores an opening-pressure relationship between the opening of the flow rate control valve and the secondary side pressure measured by the second pressure gauge while maintaining the pressure of the primary side inlet at the flow rate control pressure using the primary side pressure adjustment unit, In the on-site equipment further provided with the second pressure gauge in the on-site piping, the control unit causes the controlled gas to flow through the on-site piping, and sets the pressure of the secondary-side outlet to the initially set secondary pressure by the secondary-side pressure adjustment unit while maintaining the flow control valve at the initially set opening, and then, while maintaining the pressure of the primary-side inlet at the flow control pressure by the primary-side pressure adjustment unit, executes secondary-side pressure adjustment determination control to determine whether or not adjustment of the secondary-side pressure is necessary by comparing the secondary-side pressure measured by the second pressure gauge with a pressure derived from the opening of the flow control valve at the time of pressure measurement by the second pressure gauge and the opening-pressure relationship, and when it is determined in the secondary-side pressure adjustment determination control that adjustment of the secondary-side pressure is necessary, executes secondary-side pressure adjustment control by the secondary-side pressure adjustment unit to correct the secondary-side pressure based on the derived pressure derived from the opening of the flow control valve at the time of determination in the secondary-side pressure adjustment determination control and the opening-pressure relationship.

2. The combustion control system according to claim 1, wherein the control unit is capable of executing the secondary-side pressure adjustment determination control and the secondary-side pressure adjustment control with respect to the main fuel flow rate control mechanism, the secondary-side pressure adjustment determination control and the secondary-side pressure adjustment control with respect to the auxiliary fuel flow rate control mechanism, and the secondary-side pressure adjustment determination control and the secondary-side pressure adjustment control with respect to the combustion gas flow rate control mechanism.

3. a mixing section that mixes the main fuel gas and the secondary fuel gas, with one of the main fuel gas and the secondary fuel gas serving as a drawing fluid and the other serving as a drawn fluid that is drawn in by the drawing fluid, the mixing section has a drawing fluid inlet which is an inlet for the drawing fluid and a drawn fluid inlet which is an inlet for the drawn fluid, a flow path switching mechanism that can switch between a first connection state in which the main fuel pipe is connected to the drawing fluid inlet and the secondary fuel pipe is connected to the drawn fluid inlet, and a second connection state in which the secondary fuel pipe is connected to the drawing fluid inlet and the main fuel pipe is connected to the drawn fluid inlet, 3. The combustion control system according to claim 2, wherein the control unit executes the secondary-side pressure adjustment determination control for the main fuel flow rate control mechanism and the secondary fuel flow rate control mechanism when the flow path switching mechanism switches between the first connection state and the second connection state, and executes the secondary-side pressure adjustment control when it is determined in the secondary-side pressure adjustment determination control that adjustment of the secondary-side pressure is necessary.

4. 3. The combustion control system according to claim 1, wherein the control unit controls the flow rate of the control-target gas using the opening-flow-rate relationship that is common to different types of burners.

5. The combustion control system according to claim 2 , wherein the control unit executes the secondary pressure regulation determination control and the secondary pressure regulation control using the opening-pressure relationship that is common to different types of burners.

6. An alarm notification unit is provided to notify an alarm to the outside, 3. The combustion control system according to claim 2, wherein the control unit executes notification control in which the alarm notification unit issues the alarm when it is determined in the secondary-side pressure adjustment determination control that adjustment of the secondary-side pressure is necessary.

Images