JP7654580B2 - 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.

Some multi-burner systems do not have a shutoff valve for each burner, but are instead controlled collectively by a main valve. To control this type of combustion system, a master device that controls the main valve, a slave device that controls the ignition device and flame detector for each burner, and a safety control device that is higher up on these are used (see Patent Document 1).

In this system, the master device and slave device perform ignition upon receiving an ignition signal, and the slave device notifies the master device whether ignition was successful or not. Therefore, if ignition is unsuccessful, the master device can close the shutoff valve, allowing safe control. Conventionally, in this system, the master device and slave device are connected by a communication bus, and this communication bus is used to realize the mutual exchange of information described above.

JP 2017-180863 A

However, the above-mentioned technology requires communication between the master device and slave device to send and receive ignition signals and ignition status signals, which can lead to problems such as delays in communication and erroneous notifications due to noise.

The present invention was made to solve the above problems, and aims to make it possible to control combustion without problems caused by communication delays or noise.

The combustion control system according to the present invention includes a shutoff valve control device that receives a combustion control start command or a combustion control stop command to control the opening and closing of a common safety shutoff valve that collectively switches the supply and shutoff of fuel to multiple burners; multiple burner control devices provided corresponding to each of the multiple burners, which receive 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 if a flame failure during combustion control is detected; a contact input provided in the shutoff valve control device; and multiple contact outputs provided in each of the multiple burner control devices, with the multiple contact outputs connected in a daisy chain loop from one end of the contact input to the other end, and each of the multiple burner control devices opens its own contact output when it detects either a misfire during ignition control of the corresponding burner or a flame failure during combustion control after ignition, and the shutoff valve control device detects the opening of the contact input and closes the safety shutoff valve.

In one example configuration of the above combustion control system, the shutoff valve control device detects a short circuit in the contact input and opens the safety shutoff valve.

In one example configuration of the above combustion control system, the shutoff valve control device detects whether the contact input is open or shorted based on the presence or absence of voltage or current.

In one example configuration of the above combustion control system, a main control device is provided that notifies the shutoff valve control device and multiple burner control devices of a combustion control start command and a combustion control stop command.

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, when the contact input provided on the shutoff valve control device, which is connected in a loop to multiple contact outputs provided on each of multiple burner control devices in a daisy chain, is opened, the safety shutoff valve is closed, so combustion can be controlled without problems caused by communication delays or noise.

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

The combustion control system according to an embodiment of the present invention will be described below with reference to FIG. 1. This combustion control system includes a shutoff valve control device 101 and multiple burner control devices 102a, 102b, 102c, and 102d. In this example, the system includes four burner control devices 102a, 102b, 102c, and 102d, but is not limited to this.

The shutoff valve control device 101 receives a combustion control start command or a combustion control stop command and controls the opening and closing of a common safety shutoff valve 103 that simultaneously switches the supply and cutoff of fuel to multiple burners.

Multiple burner control devices 102a, 102b, 102c, and 102d are provided corresponding to each of the multiple burners, and upon receiving a combustion control start command or a combustion control stop command, control the ignition of the corresponding burner, monitor the flame state of the corresponding burner after ignition, and stop the combustion control of the corresponding burner if a flame failure is detected during combustion control.

As shown in FIG. 2, the system also includes a main control device 106 that issues combustion control start and stop commands to the shutoff valve control device 101 and multiple burner control devices 102a, 102b, 102c, and 102d.

Each of the burner control devices 102a, 102b, 102c, and 102d controls the ignition of burners 121a, 121b, 121c, and 121d arranged inside the combustion chamber 120. Ignition devices 122a, 122b, 122c, and 122d are provided corresponding to each of the burners 121a, 121b, 121c, and 121d. Flame detectors 123a, 123b, 123c, and 123d are also provided corresponding to each of the burners 121a, 121b, 121c, and 121d. The combustion chamber 120 is also provided with devices necessary for combustion control, such as temperature sensors.

Each of the burner control devices 102a, 102b, 102c, 102d determines the presence or absence of a flame in the corresponding burner 121a, 121b, 121c, 121d based on the presence or absence of a flame detected by the flame detector 123a, 123b, 123c, 123d connected to the device itself.

Burners 121a, 121b, 121c, and 121d are devices that heat the inside of combustion chamber 120. Note that burners 121a, 121b, 121c, and 121d are, as an example, direct ignition burners that do not have a pilot burner and directly ignite the main burner. Burners 121a, 121b, 121c, and 121d are ignited by ignition devices 122a, 122b, 122c, and 122d that are provided corresponding to each burner.

Each of the ignition devices 122a, 122b, 122c, and 122d includes, for example, an ignition transformer and an ignition electrode rod (spark rod) connected to the secondary wiring of the ignition transformer. Each of the ignition devices 122a, 122b, 122c, and 122d ignites the corresponding burner 121a, 121b, 121c, and 121d by generating a high voltage of, for example, several kV to several tens of kV in the spark rod in response to a control signal from the burner control device 102a, 102b, 102c, and 102d.

Flame detectors 123a, 123b, 123c, and 123d are provided for each burner 121a, 121b, 121c, and 121d, and are devices that detect the presence or absence of a flame in the corresponding burner. Each of flame detectors 123a, 123b, 123c, and 123d outputs a flame detection signal that indicates the presence or absence of a flame.

The main fuel flow path 131 and the branch fuel flow paths 132 are flow paths for supplying fuel to the burners 121a, 121b, 121c, and 121d. Fuel is supplied from the outside to the main fuel flow path 131, and fuel is supplied to each of the burners 121a, 121b, 121c, and 121d through the branch fuel flow paths 132 that branch off from the main fuel flow path 131. A safety shutoff valve 103 is installed in the main fuel flow path 131, and the branch fuel flow paths 132 are connected to each of the burners 121a, 121b, 121c, and 121d. Here, the fuel can be, for example, gas (gas) or oil (liquid). There is no particular limitation on the type of fuel.

The safety shutoff valve 103 switches between supplying and cutting off fuel to the burners 121a, 121b, 121c, and 121d all at once. When the safety shutoff valve 103 is open, fuel is sent from the main fuel flow path 131 to the branch fuel flow path 132, and fuel is supplied to each of the burners 121a, 121b, 121c, and 121d. When the safety shutoff valve 103 is closed, the flow of fuel from the main fuel flow path 131 to the branch fuel flow path 132 is cut off, and fuel is not supplied to the burners 121a, 121b, 121c, and 121d. The safety shutoff valve 103 has a configuration in which two shutoff valves are combined to perform double shutoff, for example, and is arranged in one location in the main fuel flow path 131.

Although not shown, an air flow path is provided in addition to the branch fuel flow path 132 to supply air to each of the burners 121a, 121b, 121c, and 121d, and the air discharged from the blower is supplied to each of the burners 121a, 121b, 121c, and 121d through the air flow path.

For safe operation of the shutoff valve control device 101 and burner control devices 102a, 102b, 102c, 102d, the main control device 106 outputs instructions to the shutoff valve control device 101 and burner control devices 102a, 102b, 102c, 102d to permit or prohibit operation of 121a, 121b, 121c, 121d in the combustion chamber 120 based on the combustion state of the burners 121a, 121b, 121c, 121d, the state of each limit interlock (not shown), and burner combustion and shutoff requests from higher-level equipment, and controls the operation of each burner 121a, 121b, 121c, 121d via the shutoff valve control device 101 and burner control devices 102a, 102b, 102c, 102d.

Alternatively, the shutoff valve control device 101 monitors the combustion state of burners 121a, 121b, 121c, and 121d, the state of each limit interlock (not shown), etc., and opens the safety shutoff valve 103 only when it is confirmed that these are in a normal state.

Examples of the main control device 106 include a limit interlock module for monitoring limit interlocks manufactured based on safety standards for industrial combustion furnaces (e.g., JIS B 8415, General Safety Rules for Industrial Combustion Furnaces), and a programmable logic controller (a so-called safety PLC) configured with dedicated software that complies with the above-mentioned safety rules.

Here, in the combustion control system according to the embodiment, the shutoff valve control device 101 has a contact input 104, and each of the multiple burner control devices 102a, 102b, 102c, and 102d has a contact output 105. In addition, the multiple contact outputs 105 are loop-connected in a daisy chain from one end of the contact input 104 to the other end of the contact input 104 by wiring 151.

Each of the burner control devices 102a, 102b, 102c, and 102d opens the contact output 105 of the device when an abnormality is detected in either misfire during combustion control of the corresponding burner or flame failure during combustion control after ignition. The shutoff valve control device 101 also detects an opening of the contact input 104 and closes the safety shutoff valve 103. The shutoff valve control device 101 detects a short circuit in the contact input 104 and opens the safety shutoff valve 103. The shutoff valve control device 101 detects an opening or short circuit in the contact input 104 based on the presence or absence of a voltage or current.

Next, an example of the operation of the combustion control system will be explained using the flowchart in Figure 3.

First, in step S101, when an ignition command is received (yes in step S101), in step S102, the burner control devices 102a, 102b, 102c, and 102d check whether the corresponding burners 121a, 121b, 121c, and 121d can be ignited. When it is confirmed that the burners 121a, 121b, 121c, and 121d can be ignited (yes in step S102), in step S103, each of the burner control devices 102a, 102b, 102c, and 102d shorts the contact output 105 and drives the ignition device.

As a result of the above, the contact input 104 is short-circuited, and this state (short-circuited contact input 104) is detected by the shutoff valve control device 101 (yes in step S104), and in step S105, the shutoff valve control device 101 opens the safety shutoff valve 103. After this, in step S106, the burners 121a, 121b, 121c, and 121d are ignited.

After that, when the burner control devices 102a, 102b, 102c, and 102d determine that any of the burners 121a, 121b, 121c, and 121d is not ignited (not ignited, flame out) through measurements by the flame detectors 123a, 123b, 123c, and 123d (no in step S107), at least one contact output 105 is opened in step S108. The shutoff valve control device 101 that detects this state closes the safety shutoff valve 103 in step S110. Alternatively, when a stop command is output from the main control device 106 (yes in step S109), the shutoff valve control device 101 closes the safety shutoff valve 103 in step S110. As a result, all of the burners 121a, 121b, 121c, and 121d are in an extinguished state.

As described above, according to the present invention, when the contact input provided on the shutoff valve control device, which is connected in a loop to the multiple contact outputs provided on each of the multiple burner control devices in a daisy chain, is opened, the safety shutoff valve is closed, making it possible to control combustion without problems caused by communication delays or noise.

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...Shut-off valve control device, 102a, 102b, 102c, 102d...Burner control device, 103...Safety shut-off valve, 104...Contact input, 105...Contact output, 151...Wiring.

Claims (5)

a shutoff valve control device that receives a combustion control start command or a combustion control stop command and controls opening and closing of a common safety shutoff valve that collectively switches between supplying and shutting off fuel to a plurality of burners;
a plurality of burner control devices provided corresponding to the plurality of burners, each of which receives the combustion control start command or the combustion control stop command to control the ignition of the corresponding burner, monitors the flame state of the corresponding burner after ignition, and stops the combustion control of the corresponding burner when a flame failure during the combustion control is detected;
A contact input provided in the shutoff valve control device;
a plurality of contact outputs provided in each of the plurality of burner control devices;
The plurality of contact outputs are connected in a loop from one end side to the other end side of the contact input,
Each of the plurality of burner control devices opens a contact output of the burner control device when it detects either a misfire during ignition control of the corresponding burner or a flame cut during combustion control after ignition,
The combustion control system according to claim 1, wherein the shutoff valve control device detects the opening of the contact input and closes the safety shutoff valve. 2. The combustion control system according to claim 1,
The combustion control system according to claim 1, wherein the shutoff valve control device detects a short circuit of the contact input and opens the safety shutoff valve. 3. The combustion control system according to claim 1,
A combustion control system characterized in that the shutoff valve control device detects an open or short circuit of the contact input based on the presence or absence of a voltage or current. The combustion control system according to any one of claims 1 to 3,
a main control device that notifies the shutoff valve control device and the plurality of burner control devices of the combustion control start command and the combustion control stop command. The combustion control system according to any one of claims 1 to 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.

Images