JP7654581B2 - Combustion Control System - Google Patents

Description

The present invention relates to a combustion control system that controls the supply of fuel to multiple burners.

In combustion furnaces such as steel furnaces, heating furnaces, and deodorizing furnaces, the combustion state of the burners installed in the combustion furnace, the temperature inside the furnace, the pressure of the combustion air, and the pressure of the fuel supplied to the burners are monitored and controlled by a combustion control system. One example of a combustion control system is a multi-burner system that controls the combustion of multiple burners installed in a common combustion chamber.

In combustion furnaces used in industrial furnaces, it is necessary to have duplicated shutoff valves installed in the fuel flow path that supplies fuel to the burner. This is so that even if one of the duplicated shutoff valves fails, the other can reliably shut off the fuel supply to prevent gas leaks, etc. This type of shutoff valve is equipped with a proof of closure (POC) switch that outputs a contact when the shutoff valve is completely closed and when it is not completely closed (see Patent Document 1).

JP 2003-130347 A

However, a problem with multi-burner systems is the cost involved in duplicating all the shutoff valves. To solve this problem, it is possible to provide one shutoff valve on the upstream side, branch off the pipes that transport fuel for each burner downstream of this shutoff valve, and provide a downstream shutoff valve for each branched pipe, thereby doubling the shutoff valves overall. In such a configuration, the multiple downstream shutoff valves can be controlled by a burner control device that controls the corresponding burners, but a separate control device is required to control the opening and closing of the upstream shutoff valves. Even with this configuration, if any of the multiple downstream shutoff valves fails and cannot be closed, it is necessary to close the upstream shutoff valve.

The present invention was made to solve the above problems, and aims to enable the upstream shutoff valve to be closed in the event of a failure of any of the multiple downstream shutoff valves in a configuration in which downstream shutoff valves are provided for each pipe branching off for each burner, downstream of a single shutoff valve provided upstream.

The combustion control system according to the present invention includes a main pipe that transfers fuel to be supplied to a plurality of burners, a plurality of branch pipes that branch off from the main pipe and supply fuel to each of the plurality of burners, a first shutoff valve provided in the main pipe, a plurality of second shutoff valves provided in each of the plurality of branch pipes, a plurality of valve closure confirmation switches provided in each of the plurality of second shutoff valves that detect the open state of the valve and output an open detection signal, a shutoff valve control device that controls the opening and closing of the first shutoff valve, and a plurality of burner control devices provided corresponding to each of the plurality of burners and perform combustion control of the corresponding burner and opening and closing control of the second shutoff valve provided for each corresponding burner, and the shutoff valve control device controls the first shutoff valve to a closed state in response to the output of an open detection signal by any of the plurality of valve closure confirmation switches.

In one example configuration of the above combustion control system, a plurality of safety relays are connected to each of the plurality of valve closure confirmation switches, and the contacts are opened upon receiving an open detection signal output. The shutoff valve control device detects the opening of the contacts of any of the plurality of safety relays and controls the first shutoff valve to a closed state.

In one configuration example of the above combustion control system, each of the burner control devices has a plurality of contacts that open upon receiving an open detection signal output from the valve closure confirmation switch of the corresponding second shutoff valve, and the shutoff valve control device detects the opening of the contacts and controls the first shutoff valve to a closed state.

In one example configuration of the above combustion control system, the shutoff valve control device receives a combustion control start command or a combustion control stop command to control the opening and closing of the first shutoff valve, and each of the multiple burner control devices receives a combustion control start command or a combustion control stop command to control the ignition of the corresponding burner and monitor the flame state of the corresponding burner after ignition, and stop the combustion control of the corresponding burner when either a misfire during ignition control of the corresponding burner or a flame failure during combustion control is detected.

In one example configuration of the above combustion control system, each of the multiple burner control devices is connected to a flame detector that detects the presence or absence of a flame in the corresponding burner, and each of the multiple burner control devices determines the presence or absence of a flame in the corresponding burner based on the presence or absence of a flame detected by the flame detector connected to the device itself.

As described above, according to the present invention, the first shutoff valve is closed when an open detection signal is output from one of the valve closure confirmation switches provided in each of the second shutoff valves provided for each of the multiple burners. Therefore, in a configuration in which downstream shutoff valves are provided for each pipe branching off for each burner downstream of one shutoff valve provided upstream, the upstream shutoff valve can be closed in the event of a failure in any of the multiple downstream shutoff valves.

FIG. 1 is a configuration diagram showing the configuration of a combustion control system according to a first embodiment of the present invention. FIG. 2 is a configuration diagram showing the configuration of a combustion control system according to a second embodiment of the present invention. FIG. 3 is a flowchart for explaining an example of the operation of the combustion control system according to the second embodiment of the present invention.

The following describes a combustion control system according to an embodiment of the present invention.

[First embodiment]
First, a combustion control system according to a first embodiment of the present invention will be described with reference to Fig. 1. This combustion control system includes a main pipe 101 that transfers fuel to be supplied to a plurality of burners 111a, 111b, and 111c, and a plurality of branch pipes 102a, 102b, and 102c that branch off from the main pipe 101 and supply fuel to each of the plurality of burners 111a, 111b, and 111c. This combustion control system also includes a first shutoff valve 103 provided in the main pipe 101, and a plurality of second shutoff valves 104a, 104b, and 104c provided in each of the plurality of branch pipes 102a, 102b, and 102c.

The combustion control system also includes a plurality of valve closure confirmation switches (POC) 105a, 105b, 105c that are provided on each of the plurality of second shutoff valves 104a, 104b, 104c and detect the open state of the valve and output an open detection signal. If the second shutoff valves 104a, 104b, 104c cannot be closed due to a malfunction or the like, the second shutoff valves 104a, 104b, 104c will be in an open state, and the POCs 105a, 105b, 105c will detect this state and output an open detection signal.

The combustion control system also includes a shutoff valve control device 106 that controls the opening and closing of the first shutoff valve 103, and multiple burner control devices 107a, 107b, and 107c. The shutoff valve control device 106 receives a combustion control start command or a combustion control stop command from a higher-level control device (not shown) and controls the opening and closing of the first shutoff valve 103.

Burner control devices 107a, 107b, 107c are provided corresponding to each of the burners 111a, 111b, 111c, and perform combustion control of the corresponding burners 111a, 111b, 111c, and opening/closing control of the second shutoff valves 104a, 104b, 104c provided for each of the corresponding burners 111a, 111b, 111c.

In addition, each of the multiple burner control devices 107a, 107b, 107c receives a combustion control start command or a combustion control stop command from a higher-level control device (not shown) to control the ignition of the corresponding burner 111a, 111b, 111c, and stops the combustion control of the corresponding burner 111a, 111b, 111c when it detects either a misfire during ignition control of the corresponding burner 111a, 111b, 111c or a flame failure during combustion control after ignition.

For example, each of the burner control devices 107a, 107b, 107c is connected to a flame detector (not shown) that detects the presence or absence of a flame in the corresponding burner 111a, 111b, 111c, and each of the burner control devices 107a, 107b, 107c determines the presence or absence of a flame in the corresponding burner 111a, 111b, 111c based on the presence or absence of a flame detected by the flame detector connected to the device itself.

In addition, the shutoff valve control device 106 of the combustion control system controls the first shutoff valve 103 to a closed state when an open detection signal is output by any of the multiple POCs 105a, 105b, and 105c.

The combustion control system according to the first embodiment includes a plurality of safety relays 108a, 108b, and 108c that are connected to the plurality of POCs 105a, 105b, and 105c, respectively, and open their contacts upon receiving an open detection signal. The shutoff valve control device 106 detects the opening of the contacts of any of the plurality of safety relays 108a, 108b, and 108c, and controls the first shutoff valve 103 to a closed state.

According to the combustion control system of the first embodiment described above, when an open detection signal is output from any of the valve closure confirmation switches, the shutoff valve control device closes the first shutoff valve, so that if any of the multiple downstream second shutoff valves malfunctions and cannot be closed, the first shutoff valve is immediately closed. Note that, although the above description has been given using a multi-burner system with three burners as an example, this is not limiting, and the same applies to a multi-burner system with four or more burners, for example.

[Embodiment 2]
Next, a combustion control system according to a second embodiment of the present invention will be described with reference to Fig. 2. This combustion control system includes a main pipe 101 that transfers fuel to be supplied to a plurality of burners 111a, 111b, and 111c, and a plurality of branch pipes 102a, 102b, and 102c that branch off from the main pipe 101 and supply fuel to each of the plurality of burners 111a, 111b, and 111c. This combustion control system also includes a first shutoff valve 103 provided in the main pipe 101, and a plurality of second shutoff valves 104a, 104b, and 104c provided in each of the plurality of branch pipes 102a, 102b, and 102c.

The combustion control system also includes a plurality of valve closure confirmation switches (POC) 105a, 105b, 105c that are provided on each of the plurality of second shutoff valves 104a, 104b, 104c and detect the open state of the valve and output an open detection signal. If the second shutoff valves 104a, 104b, 104c cannot be closed due to a malfunction or the like, the second shutoff valves 104a, 104b, 104c will be in an open state, and the POCs 105a, 105b, 105c will detect this state and output an open detection signal.

The combustion control system also includes a shutoff valve control device 106 that controls the opening and closing of the first shutoff valve 103, and multiple burner control devices 107'a, 107'b, and 107'c. The shutoff valve control device 106 receives a combustion control start command or a combustion control stop command from a higher-level control device (not shown) and controls the opening and closing of the first shutoff valve 103.

Burner control devices 107'a, 107'b, 107'c are provided corresponding to each of the burners 111a, 111b, 111c, and perform combustion control of the corresponding burners 111a, 111b, 111c, and opening/closing control of the second shutoff valves 104a, 104b, 104c provided for each of the corresponding burners 111a, 111b, 111c.

In addition, each of the multiple burner control devices 107'a, 107'b, 107'c receives a combustion control start command or a combustion control stop command from a higher-level control device (not shown) to control the ignition of the corresponding burner 111a, 111b, 111c, and stops the combustion control of the corresponding burner 111a, 111b, 111c when it detects either a misfire during ignition control of the corresponding burner 111a, 111b, 111c or a flame failure during combustion control after ignition.

For example, a flame detector (not shown) that detects the presence or absence of a flame in the corresponding burner 111a, 111b, 111c is connected to each of the multiple burner control devices 107'a, 107'b, 107'c, and each of the multiple burner control devices 107'a, 107'b, 107'c determines the presence or absence of a flame in the corresponding burner 111a, 111b, 111c based on the presence or absence of a flame detected by the flame detector connected to the device itself.

In addition, the shutoff valve control device 106 of the combustion control system controls the first shutoff valve 103 to a closed state when an open detection signal is output by any of the multiple POCs 105a, 105b, and 105c.

In the combustion control system according to the second embodiment, a plurality of burner control devices 107'a, 107'b, 107'c are provided with a plurality of contacts 109a, 109b, 109c that are opened upon receiving an open detection signal output from the POCs 105a, 105b, 105c of the corresponding second shutoff valves 104a, 104b, 104c. In the second embodiment, the shutoff valve control device 106 detects the opening of the contacts 109a, 109b, 109c and controls the first shutoff valve 103 to a closed state.

Next, an example of the operation of the combustion control system according to the second embodiment will be described with reference to the flowchart in FIG. 3. In this system, when the burner control devices 107a, 107b, and 107c have not output an open command for the second shutoff valve of the corresponding burner 111a, 111b, and 111c due to receiving a stop command or the like (no in the first step S101), in step S102, the burner control devices 107a, 107b, and 107c determine whether an open detection signal has been output.

When it is determined (detected) that the open detection signal is being output (yes in step S102), the burner control devices 107a, 107b, and 107c open the contacts 109a, 109b, and 109c in step S103. As a result of this opening, the shutoff valve control device 106 controls the first shutoff valve 103 to a closed state in step S104.

According to the combustion control system of the second embodiment described above, when an open detection signal is output from any of the valve closure confirmation switches, the shutoff valve control device closes the first shutoff valve, so that if any of the multiple downstream second shutoff valves fails and cannot be closed, the first shutoff valve is immediately closed. According to the second embodiment, the first shutoff valve is closed when any of the second shutoff valves fails, without the need for additional equipment such as a safety relay. Note that, although the above description has been given using a multi-burner system with three burners as an example, this is not limiting, and the same applies to a multi-burner system with four or more burners, for example.

Each control device constituting the combustion control system according to the above-mentioned embodiment can be a computer device equipped with a CPU (Central Processing Unit), a main memory device, an external memory device, a network connection device, etc., and each of the above-mentioned functions can be realized by the CPU operating (executing the program) according to a program deployed in the main memory device. The above-mentioned program is a program for causing a computer to execute the operation of the control device shown in the above-mentioned embodiment. The network connection device connects to a network. Also, each function can be distributed among multiple computer devices.

In addition, each of the above-mentioned control devices can also be configured using a programmable logic device (PLD) such as a field-programmable gate array (FPGA).

As described above, according to the present invention, the first shutoff valve is closed when an open detection signal is output from one of the valve closure confirmation switches provided in each of the second shutoff valves provided for each of the multiple burners. Therefore, in a configuration in which downstream shutoff valves are provided for each piping branched off for each burner after one shutoff valve provided upstream, the upstream shutoff valve can be closed in the event of a failure in any of the multiple downstream shutoff valves.

The present invention is not limited to the embodiments described above, and it is clear that many modifications and combinations can be implemented by those with ordinary skill in the art within the technical concept of the present invention.

101...Main pipe, 102a, 102b, 102c...Branch pipe, 103...First shutoff valve, 104a, 104b, 104c...Second shutoff valve, 105a, 105b, 105c...Valve closure confirmation switch (POC), 106...Shutoff valve control device, 107a, 107b, 107c...Burner control device, 107'a, 107'b, 107'c...Burner control device, 108a, 108b, 108c...Safety relay, 109a, 109b, 109c...Contact points.

Claims (5)

A main pipe for transporting fuel to be supplied to the plurality of burners;
a plurality of branch pipes branching from the main pipe for supplying fuel to each of the plurality of burners;
A first shutoff valve provided in the main pipe;
A plurality of second shutoff valves provided in each of the plurality of branch pipes;
a plurality of valve closure confirmation switches provided in the plurality of second shutoff valves, each of which detects an open state of the valve and outputs an open detection signal;
A shutoff valve control device that controls opening and closing of the first shutoff valve;
a plurality of burner control devices provided corresponding to each of the plurality of burners, each of which controls the combustion of the corresponding burner and controls the opening and closing of a second shutoff valve provided for each corresponding burner;
The combustion control system according to claim 1, wherein the shutoff valve control device controls the first shutoff valve to a closed state in response to an output of an open detection signal from any one of the plurality of valve closure confirmation switches. 2. The combustion control system according to claim 1,
a plurality of safety relays connected to the plurality of valve closure confirmation switches, the plurality of safety relays each having a contact opening in response to an output of an open detection signal;
The combustion control system, wherein the shutoff valve control device detects an opening of a contact of any of the plurality of safety relays and controls the first shutoff valve to a closed state. 2. The combustion control system according to claim 1,
a plurality of contacts provided in each of the plurality of burner control devices, the contacts opening in response to an open detection signal output from a valve closure confirmation switch of a corresponding second shutoff valve;
The combustion control system, wherein the shutoff valve control device detects the opening of the contact and controls the first shutoff valve to a closed state. The combustion control system according to any one of claims 1 to 3,
The shutoff valve control device receives a combustion control start command or a combustion control stop command and controls opening and closing of the first shutoff valve,
a combustion control system characterized in that each of the plurality of burner control devices, upon receiving the combustion control start command or the combustion control stop command, controls the ignition of a corresponding burner and monitors the flame state of the corresponding burner after ignition, and stops the combustion control of the corresponding burner when either misfire during ignition control of the corresponding burner or flame failure during combustion control is detected. 5. The combustion control system according to claim 4,
Each of the plurality of burner control devices is connected to a flame detector that detects the presence or absence of a flame in the corresponding burner,
A combustion control system, wherein each of the plurality of burner control devices determines the presence or absence of a flame in a corresponding burner based on the presence or absence of a flame detected by the flame detector connected to the burner control device itself.

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