JP7644036B2 - Control System - Google Patents

Description

The present invention relates to a control system that controls combustion in a combustion furnace.

2. Description of the Related Art Combustion equipment such as a combustion furnace or a boiler includes an ignition device and a burner controller as a combustion control system for controlling combustion in the furnace.
The ignition device ignites the burner by generating a high voltage of, for example, several kV to several tens of kV in the rod. The burner controller controls the ignition of the burner via the ignition device, monitors the combustion of the burner, and controls the fuel cutoff valve. When igniting the burner, the burner controller controls the fuel cutoff valve, which starts and stops the supply of fuel to the burner, to supply fuel to the burner, and when stopping combustion by the burner, controls the fuel cutoff valve to stop the supply of fuel to the burner.

When the burner controller receives a start-up request, it first checks whether the relay inside the burner controller, which drives the fuel cutoff valve and ignition device, has welded, and after confirming that the relay is not welded, it starts combustion control. This check is performed to prevent unintended activation of the fuel cutoff valve due to a welded relay, which would cause fuel to leak, and this process is called the start check process.

In addition, the relays are multiplexed so that fuel leakage will not occur due to a single failure (see Patent Document 1). For example, in the technology disclosed in Patent Document 1, a duplicate relay is provided.
However, simply providing two relays is not enough to deal with the situation when an abnormality occurs in both relays. Therefore, the technology disclosed in Patent Document 2 provides three relays to prevent abnormalities such as fuel leakage.

The technology disclosed in Patent Document 2 will be described below with reference to Figures 5 and 6. Figure 5 is a block diagram showing the configuration of a relay circuit section of a burner controller, and Figure 6 is a flowchart explaining the operation of the burner controller.
The relay circuit section of the burner controller 1 is provided with relays 12-1, 12-2 inserted in series into one of the two connection lines 10, 11 connecting the power source 2 and the load 3, and a relay 12-3 inserted in series into the other connection line 11.

The load 3 may be, for example, a fuel cutoff valve or an ignition device. Each of the relays 12-1 to 12-3 is provided with a detection circuit (not shown) that detects its operation, and feedback information FB1 to FB3 indicating the detection result is output.
The process of stop → start check → combustion start → combustion stop is performed in the following order.

(I) The burner controller 1 initiates a start check, for example, when a start-up request is received from the operator (YES in step S100 in FIG. 6).

(II) At the beginning of the start check, the burner controller 1 checks that the contacts of the first relay 12-1 and the third relay 12-3 are not welded based on the feedback information FB1 and FB3 (step S101 in Figure 6).

(III) If the burner controller 1 confirms that the contacts of the first relay 12-1 and the third relay 12-3 are not welded (YES in step S101), it excites the third relay 12-3 to turn on the contacts (step S102 in FIG. 6). The burner controller 1 confirms based on the feedback information FB1 and FB3 that the contacts of the first relay 12-1 are not welded, that the contacts of the third relay 12-3 are in the on state, and that there is no failure (step S103 in FIG. 6).

(IV) When the burner controller 1 confirms that the contacts of the first relay 12-1 are not welded and that the third relay 12-3 is not broken (YES in step S103), it turns off the contacts of all relays 12-1 to 12-3 (step S104 in FIG. 6). The burner controller 1 confirms that the contacts of the first relay 12-1 and the third relay 12-3 are not welded based on the feedback information FB1 and FB3 (step S105 in FIG. 6). Note that a check similar to that in step S101 is performed, but the main purpose of step S105 is to prevent fuel leakage in the case where the second relay 12-2 is welded by turning on the first relay 12-1 before confirming that the third relay 12-3 is off.

(V) If the burner controller 1 confirms that the contacts of the first relay 12-1 and the third relay 12-3 are not welded (YES in step S105), it excites the first relay 12-1 to turn on the contacts (step S106 in FIG. 6). The burner controller 1 confirms based on the feedback information FB2 and FB1 that the contacts of the second relay 12-2 are not welded, that the contacts of the first relay 12-1 are in the on state, and that there is no failure (step S107 in FIG. 6).

(VI) If the burner controller 1 can confirm that the contacts of the second relay 12-2 are not welded and that the first relay 12-1 is not faulty (YES in step S107), it completes the start check. After completing the start check, the burner controller 1 starts combustion. Specifically, the burner controller 1 excites the first relay 12-1 and the third relay 12-3 to turn on their respective contacts (step S108 in FIG. 6).

(VII) Next, the burner controller 1 excites the second relay 12-2 to turn on the contacts (step S109 in FIG. 6). This causes power to be supplied from the power source 2 to the load 3, and the burner installed in the combustion furnace is ignited.

If the burner controller 1 detects a problem in at least one of the checks in steps S101, S103, S105, and S107, it will stop all processing without proceeding to the next step.

(VIII) When combustion is continuing, for example, when an instruction to stop is received from the operator (YES in step S111 in FIG. 6), the burner controller 1 turns off the contact of the second relay 12-2 (step S112 in FIG. 6). This stops the power supply from the power source 2 to the load 3, and the combustion in the combustion furnace stops (step S113 in FIG. 6).

(IX) The burner controller 1 turns off the contacts of the first relay 12-1 and the third relay 12-3 (step S114 in FIG. 6). In this way, all relays 12-1 to 12-3 are turned off.

As described above, by providing three relays, the problems of the technique disclosed in Patent Document 1 can be solved.
However, the technology disclosed in Patent Document 2 has a problem in that the start check at the start of combustion takes a long time, so the start of combustion is delayed from the timing at which combustion is actually desired to start, which may affect temperature control. In equipment that starts and stops frequently (for example, every few tens of seconds), the time between stopping and restarting may be as short as about one second, and if the time required for the start check is long, the start of combustion will be delayed from the timing at which combustion is actually desired to start.

JP 2009-168404 A JP 2011-208922 A

The present invention has been made to solve the above problems, and aims to provide a control system that can shorten the time required for a start check when control begins.

The control system of the present invention includes a first relay inserted in series in a first connection line of two connection lines connecting a power source and a load, a second relay inserted for each load between the first relay and the load, a third relay inserted in series in a second connection line of the two connection lines, a control unit configured to control the load by opening and closing the first, second, and third relays, and a check execution unit configured to execute a first check sequence for confirming that the first, second, and third relays are not welded before a series of control sequences are started by the control unit in response to a startup request from the outside, and a second check sequence for confirming that the first, second, and third relays are not welded before receiving a next startup request after the control sequence has stopped, and the check execution unit executes the first and second check sequences in response to a first startup request, and executes only the second check sequence in response to a second or subsequent startup request.

In addition, in one configuration example of the control system of the present invention, the check execution unit is characterized in that if a predetermined time has passed between the stop of the most recent control sequence and the receipt of a new start-up request, or if a predetermined time has passed between the stop of the initial control sequence and the receipt of a new start-up request, the check execution unit regards the new start-up request as an initial start-up request and executes the first check sequence.
In one configuration example of the control system of the present invention, the first check sequence includes a first step of confirming that the first and third relays are not welded, a second step of the check execution unit turning on the third relay when it has been confirmed that the first and third relays are not welded and confirming that the first relay is not welded and that the third relay is not malfunctioning, a third step of the check execution unit turning off all relays when it has been confirmed that the first relay is not welded and that the third relay is not malfunctioning and confirming that the first and third relays are not welded, and a third step of the check execution unit turning off all relays when it has been confirmed that the first and third relays are not welded and confirming that the first and third relays are not welded. and a fourth step in which the check execution unit turns the first relay to an on state to confirm that the second relay is not welded and that the first relay is not malfunctioning, and the second check sequence includes a fifth step in which, after the control unit turns the second relay to an off state and stops the control sequence when the first, second, and third relays are in an on state, the check execution unit turns the third relay to an off state to confirm that the second relay is not welded, and a sixth step in which, when it has been confirmed that the second relay is not welded, the check execution unit turns the first relay to an off state to confirm that the first and third relays are not welded.

According to the present invention, the first and second check sequences are executed for the first startup request, and only the second check sequence is executed for the second and subsequent startup requests, thereby reducing the time required for the start check when control begins.

FIG. 1 is a block diagram showing the configuration of a combustion control system according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of a burner controller according to an embodiment of the present invention. FIG. 3 is a flow chart illustrating the operation of the burner controller according to the embodiment of the present invention. FIG. 4 is a block diagram showing an example of the configuration of a computer that realizes a burner controller according to an embodiment of the present invention. FIG. 5 is a block diagram showing the configuration of a relay circuit section of a conventional burner controller. FIG. 6 is a flow chart for explaining the operation of a conventional burner controller.

Figure 1 is a block diagram showing the configuration of a combustion control system according to this embodiment. The combustion control system includes a burner controller 1a, an ignition device 6 that ignites a burner 5 in a combustion furnace 4, a fuel shutoff valve 7 that starts and stops the supply of fuel to the burner 5, and a flame detector 8 that detects the presence of a flame in the combustion furnace 4.

The configuration of the ignition device 6 is disclosed in, for example, Japanese Patent Application Laid-Open No. 2016-121845, and therefore detailed description thereof will be omitted.
The flame detector 8 detects the presence of a flame by detecting light emitted from the flame inside the combustion furnace 4. However, detection by light is only one example, and flame detection may be performed by other methods.

Figure 2 is a block diagram showing the configuration of the burner controller 1a. The burner controller 1a includes a first relay 12-1 inserted in series in one of two connection lines 10, 11 connecting the power source 2 and the load 3, second relays 12-2-1, 12-2-2 inserted between the first relay 12-1 and the load 3 for each load, a third relay 12-3 inserted in series in the other connection line 11, a feedback information acquisition unit 13 that acquires feedback information from the relays 12-1 to 12-3, a flame signal acquisition unit 14 that acquires a flame signal from the flame detector 8, a feedback information storage unit 15 that stores the feedback information, a check execution unit 16 that executes checks on the relays 12-1 to 12-3 based on the feedback information, and a combustion control unit 17 that drives the relays 12-1 to 12-3 to ignite the burner 5 and control the opening and closing of the fuel cutoff valve 7.

In this embodiment, the load 3 is an ignition device 6 and a fuel cutoff valve 7. In this case, the second relay 12-2 is provided for each load, such as relay 12-2-1 having one contact terminal connected to the first relay 12-1 and the other contact terminal connected to the ignition device 6, and relay 12-2-2 having one contact terminal connected to the first relay 12-1 and the other contact terminal connected to the fuel cutoff valve 7.

The relays 12-1, 12-2-1, 12-2-2, and 12-3 are provided with detection circuits (not shown) for detecting their respective operations, and feedback information FB1, FB2-1, FB2-2, and FB3 indicating the detection results are output.
The process of stop → start check → combustion start → combustion stop is performed in the following order.

[First run]
(I) In the stopped state before the start of combustion, the combustion control section 17 of the burner controller 1a keeps the contacts of all the relays 12-1, 12-2-1, 12-2-2, and 12-3 in the OFF state.
The feedback information acquisition unit 13 of the burner controller 1a acquires feedback information FB1, FB2-1, FB2-2, and FB3 from the relays 12-1, 12-2-1, 12-2-2, and 12-3. The acquired feedback information FB1, FB2-1, FB2-2, and FB3 are stored in a feedback information storage unit 15.

(I) The check execution unit 16 of the burner controller 1a starts the check sequence, for example, when a start-up request is received from the operator (YES in step S200 in FIG. 3).

(II) At the start of the start check, the check execution unit 16 checks that the contacts of the first relay 12-1 and the third relay 12-3 are not welded based on the feedback information FB1 and FB3 (step S201 in Figure 3).

(III) If the check execution unit 16 is able to confirm that the contacts of the first relay 12-1 and the third relay 12-3 are not welded (YES in step S201), it excites the third relay 12-3 to turn on the contacts (step S202 in FIG. 3). Based on the latest feedback information FB1 and FB3, the check execution unit 16 confirms that the contacts of the first relay 12-1 are not welded, that the contacts of the third relay 12-3 are in the on state, and that there is no failure (step S203 in FIG. 3).

(IV) If the check execution unit 16 confirms that the contacts of the first relay 12-1 are not welded and that the third relay 12-3 is not faulty (YES in step S203), it turns off the contacts of all relays 12-1, 12-2-1, 12-2-2, and 12-3 (step S204 in FIG. 3). The check execution unit 16 confirms that the contacts of the first relay 12-1 and the third relay 12-3 are not welded based on the latest feedback information FB1 and FB3 (step S205 in FIG. 3).

(V) If the check execution unit 16 is able to confirm that the contacts of the first relay 12-1 and the third relay 12-3 are not welded (YES in step S205), it excites the first relay 12-1 to turn on the contacts (step S206 in FIG. 3). Based on the latest feedback information FB2-1, FB2-2, and FB1, the check execution unit 16 confirms that the contacts of the second relays 12-2-1 and 12-2-2 are not welded, that the contacts of the first relay 12-1 are in the on state, and that there is no failure (step S207 in FIG. 3).

(VI) If the check execution unit 16 confirms that the contacts of the second relays 12-2-1 and 12-2-2 are not welded and that the first relay 12-1 is not faulty (YES in step S207), it completes the first check sequence (steps S202 to S207).

When the first check sequence is completed, the combustion control unit 17 of the burner controller 1a starts the combustion (control sequence). Specifically, the combustion control unit 17 excites the first relay 12-1 and the third relay 12-3 to turn on their respective contacts (step S208 in FIG. 3).

(VII) Next, the combustion control unit 17 excites the second relays 12-2-1 and 12-2-2 to turn their contacts on (step S209 in FIG. 3). This causes power to be supplied from the power source 2 to the load 3. By turning on the contacts of the second relay 12-2-2 to supply power to the fuel cutoff valve 7, the fuel cutoff valve 7 opens and starts supplying fuel to the burner 5, and by turning on the contacts of the second relay 12-2-1 to supply power to the ignition device 6, the ignition device 6 generates a spark in an ignition electrode rod (not shown) to ignite the burner 5 (step S210 in FIG. 3).
The second relays 12-2-1 and 12-2-2 may be turned on simultaneously with the turning on of the first relay 12-1 and the third relay 12-3 in step S208.

If the check execution unit 16 detects a problem in at least one of the checks in steps S201, S203, S205, and S207 and the result is NO, the check execution unit 16 stops all processing without proceeding to the next step. In step S201, if at least one of the contacts of the first relay 12-1 and the third relay 12-3 is welded, the result is NO. In step S203, if at least one of the contacts of the first relay 12-1 is welded or the contact of the third relay 12-3 is not in the ON state, the result is NO. In step S205, if at least one of the contacts of the first relay 12-1 and the third relay 12-3 is welded, the result is NO. In step S207, if at least one of the contacts of the second relays 12-2-1 and 12-2-2 is welded or the contact of the first relay 12-1 is not in the ON state, the result is NO.
Furthermore, the first check sequence is not limited to the procedure described in steps S201 to S207, and may be executed according to another procedure.

The combustion control unit 17 confirms that the contacts of all relays 12-1, 12-2-1, 12-2-2, and 12-3 are in the ON state and are not malfunctioning based on the latest feedback information FB1, FB2-1, FB2-2, and FB3, and maintains the open operation of the fuel cutoff valve 7 if it confirms the presence of a flame in the combustion furnace 4 based on the flame signal acquired from the flame detector 8. In addition, the combustion control unit 17 turns off the contacts of the second relay 12-2-1 after a predetermined time has elapsed, stopping the generation of sparks by the ignition device 6.

(VIII) When combustion is continuing, for example, when an instruction to stop is received from the operator (YES in step S211 in FIG. 3), the combustion control unit 17 turns off the contact of the second relay 12-2-2 (step S212 in FIG. 3). This stops the power supply from the power source 2 to the fuel cutoff valve 7, closes the fuel cutoff valve 7, stops the fuel supply to the burner 5, and stops combustion in the combustion furnace 4 (step S213 in FIG. 3).

(IX) When the control sequence by the combustion control unit 17 is stopped, the check execution unit 16 starts a second check sequence. Specifically, the check execution unit 16 turns off the contact of the third relay 12-3 (step S214 in FIG. 3). The check execution unit 16 checks that the contacts of the second relays 12-2-1 and 12-2-2 are not welded based on the latest feedback information FB2-1 and FB2-2 (step S215 in FIG. 3).
The third relay 12-3 may be turned off simultaneously with the second relay 12-2-2 being turned off in step S212.

(X) If the check execution unit 16 confirms that the contacts of the second relays 12-2-1 and 12-2-2 are not welded (YES in step S215), it turns off the contacts of the first relay 12-1 (step S216 in FIG. 3). In this way, all relays 12-1, 12-2-1, 12-2-2, and 12-3 are turned off. The check execution unit 16 confirms that the contacts of the first relay 12-1 and the third relay 12-3 are not welded based on the latest feedback information FB1 and FB3 (step S217 in FIG. 3).

If the check execution unit 16 confirms that the contacts of the first relay 12-1 and the third relay 12-3 are not welded (YES in step S217), it completes the second check sequence (steps S214 to S217). When the second check sequence is completed, the combustion control unit 17 goes into a standby state to wait for the next start request.

If the check execution unit 16 detects a problem in at least one of the checks in steps S215 and S217 and the result is NO, it stops all processing without proceeding to the subsequent steps. In step S215, if the contacts of at least one of the second relays 12-2-1 and 12-2-2 are welded, the result is NO. In step S217, if the contacts of at least one of the first relay 12-1 and the third relay 12-3 are welded, the result is NO.

[Second or subsequent operation]
(XI) After the second check sequence is completed, the combustion control unit 17 starts the combustion (control sequence) when, for example, there is a start request from the operator (YES in step S218 in FIG. 3). Specifically, the combustion control unit 17 excites the first relay 12-1 and the third relay 12-3 to turn on the contacts of each relay (step S219 in FIG. 3).

(XII) Next, the combustion control unit 17 excites the second relays 12-2-1 and 12-2-2 to turn on the contacts (step S220 in FIG. 3). This causes the fuel cutoff valve 7 to open and start supplying fuel to the burner 5, and the ignition device 6 generates a spark in the ignition electrode rod to ignite the burner 5 (step S210 in FIG. 3). Subsequent processing is as described above.

As described above, in this embodiment, when the first operation is stopped, the time required for the second check sequence of steps S214 to S217 is longer, but in the second and subsequent operations, the first check sequence of steps S202 to S207 can be omitted. As a result, in this embodiment, the delay from the start request to the start of combustion in the second and subsequent operations can be made shorter than in the past.

Note that if a predetermined time (e.g., 24 hours) has elapsed between the time when the most recent control sequence was stopped and when a new start request was received, or if a predetermined time has elapsed between the time when the initial control sequence was stopped and when a new start request was received, the check execution unit 16 and the combustion control unit 17 must take into consideration failures and welding of relays 12-1, 12-2-1, 12-2-2, and 12-3 (JIS B8415-3 F.2), and therefore they regard the new start request as an initial start request and begin processing from step S202.

The feedback information acquisition unit 13, flame signal acquisition unit 14, feedback information storage unit 15, check execution unit 16, and combustion control unit 17 of the burner controller 1a described in this embodiment can be realized by a computer equipped with a CPU (Central Processing Unit), a storage device, and an interface, and a program that controls these hardware resources. An example of the configuration of this computer is shown in Figure 4.

The computer includes a CPU 200, a storage device 201, and an interface device (I/F) 202. Relays 12-1, 12-2-1, 12-2-2, and 12-3, a flame detector 8, and the like are connected to the I/F 202. A program for implementing the control method of the present invention is stored in the storage device 201. The CPU 200 executes the processing described in this embodiment in accordance with the program stored in the storage device 201.

The present invention can be applied to facilities that include combustion furnaces.

1a... burner controller, 2... power source, 3... load, 4... combustion furnace, 5... burner, 6... ignition device, 7... fuel shutoff valve, 8... flame detector, 10, 11... connection lines, 12-1, 12-2, 12-2-1, 12-2-2, 12-3... relays, 13... feedback information acquisition unit, 14... flame signal acquisition unit, 15... feedback information storage unit, 16... check execution unit, 17... combustion control unit.

Claims (3)

a first relay inserted in series into a first connection line of two connection lines connecting a power source and a load;
a second relay inserted for each load between the first relay and the load;
a third relay inserted in series with the second connection line of the two connection lines;
a control unit configured to control the load by opening and closing the first, second, and third relays;
a check execution unit configured to execute a first check sequence for confirming that the first, second, and third relays are not welded before a series of control sequences is started by the control unit in response to an external startup request, and a second check sequence for confirming that the first, second, and third relays are not welded after the control sequence is stopped and before a next startup request is received,
A control system characterized in that the check execution unit executes the first and second check sequences in response to an initial startup request, and executes only the second check sequence in response to a second or subsequent startup request. 2. The control system of claim 1,
The control system is characterized in that the check execution unit, when a predetermined time has passed between the stop of the most recent control sequence and the receipt of a new start-up request, or when a predetermined time has passed between the stop of the initial control sequence and the receipt of a new start-up request, regards the new start-up request as an initial start-up request and executes the first check sequence. 3. The control system according to claim 1,
The first check sequence comprises:
a first step of confirming that the first and third relays are not welded;
a second step in which, when it is confirmed that the first and third relays are not welded, the check execution unit turns on the third relay to confirm that the first relay is not welded and that the third relay is not at fault;
a third step in which, when it is confirmed that the first relay is not welded and the third relay is not broken, the check execution unit turns off all relays and confirms that the first and third relays are not welded;
and a fourth step of the check execution unit turning on the first relay when it has been confirmed that the first and third relays are not welded, thereby confirming that the second relay is not welded and that the first relay is not at fault,
The second check sequence includes:
a fifth step of, when the first, second and third relays are in an on state, the control unit turns the second relay to an off state to stop the control sequence, and then the check execution unit turns the third relay to an off state to confirm that the second relay is not welded;
and a sixth step in which, when it is confirmed that the second relay is not welded, the check execution unit turns off the first relay and confirms that the first and third relays are not welded.

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