JP2012017931A - Combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure combustion performance and allow earlier start of combustion in response to a combustion request.SOLUTION: A combustion device includes a blower 2 supplying air for combustion, a damper 3 regulating a supply amount of the air for combustion, and a fuel supply amount regulation device 7 regulating a fuel supply amount. When receiving a standby request during combustion, the combustion device performs post purge and then stops operation into a combustion standby state. When receiving a combustion request during combustion standby or during the post purge, the combustion device performs pre-purge and then starts combustion into a combustion state. In the combustion device, when starting the pre-purge from the combustion standby state and when starting the post purge from the combustion state, limit check of the damper is performed, and when receiving a combustion request during the post purge, the limit check of the damper performed during the post purge is taken over as the limit check during the pre-purge, so that a time required for the limit check during the pre-purge is shortened.

Description

  The present invention relates to a combustion apparatus that performs pre-purge before the start of combustion and performs post-purge after the end of combustion.

  As disclosed in Japanese Utility Model Publication No. 3-18839, in a combustion apparatus that performs combustion while supplying fuel and combustion air into the furnace, in order to prevent accidents caused by unburned gas remaining in the furnace, combustion starts. Pre-purge is performed immediately before, and post-purge is performed immediately after the end of combustion. By performing pre-purge and post-purge for supplying only air into the furnace, and ventilating so that unburned gas does not remain in the furnace, safety at the time of ignition or after stopping combustion can be improved.

  However, in this case, there is a problem that the start of combustion is delayed because combustion cannot be started until the pre-purge is completed even if there is a combustion request. In particular, when there is a combustion request during the post purge, if the pre purge is started after the completion of the post purge, the time until the start of the combustion becomes very long. Therefore, in Japanese Utility Model Publication No. 3-18839, when there is a combustion request during post-purge, it is proposed to reduce the pre-purge time by excluding the time during which post-purge was performed from the pre-purge setting time. It has been broken. Both the post-purge and the pre-purge are those in which air is sent into the furnace to ventilate the furnace, so that the time until the start of combustion can be shortened by incorporating the post-purge execution time into the pre-purge time.

Also, if a damper is installed in the combustion air supply channel and the supply amount of combustion air is adjusted by the damper, the fuel supply amount and air The balance of supply is lost and normal combustion is not possible. Therefore, it was considered to perform a limit check to check the position of the damper by operating the damper before the start of combustion.
Since the damper limit check must be performed before the start of combustion, the limit check is performed during pre-purge. Combustion cannot be started until the limit check is completed, but since the time required for the limit check is shorter than the time required for the pre-purge, the start of combustion is not normally delayed by the limit check. However, if the pre-purge time is shortened and the time required for the pre-purge becomes shorter than the time required for the limit check, the start of combustion may be delayed because it is necessary to wait for the end of the limit check. It was.

Japanese Utility Model Publication No. 3-18839

  The problem to be solved by the present invention is to ensure combustion performance by performing a limit check of a damper before the start of combustion in a combustion apparatus in which pre-purge is performed before the start of combustion and post-purge is performed after the end of combustion. At the same time, it is to be able to start combustion earlier in response to the combustion request.

  It has a blower that supplies combustion air, a damper that adjusts the supply amount of combustion air, and a fuel supply amount adjustment device that adjusts the fuel supply amount, and adjusts the combustion amount by adjusting the combustion air supply amount and the fuel supply amount. When a standby request is received during combustion, post-purge is performed and then the operation is stopped to enter a combustion standby state.When a combustion request is received during combustion standby or during post-purge, pre-purge is performed. In a combustion apparatus that starts combustion after being performed and enters a combustion state, when pre-purge is started from the combustion standby state and when post-purge is started from the combustion state, a limit check of the damper is performed, When a combustion request is received during post-purge, the damper limit check that was performed during post-purge is pulled as the limit check during pre-purge. In Gukoto, to shorten the time required to limit check at the time of the pre-purge.

  If there is a combustion request during post-purge, the pre-purge time can be shortened by setting the post-purge execution time as the pre-purge time, but the time required for the pre-purge is shorter than the time required for the limit check by reducing the pre-purge time. When it became shorter, the start of combustion was delayed by the amount of time waiting for the end of the limit check. However, if a limit check is performed during post-purge, and there is a combustion request during post-purge and switching to pre-purge, it is not necessary to perform the limit check that was performed so far by taking over the limit check. Since only the remaining limit check needs to be performed, the time required for the limit check is shortened. While confirming that the ratio of fuel to air at the time of combustion is appropriate, the time until the start of combustion can be shortened and the followability to the load can be made high.

An explanatory diagram comparing the case where the invention is implemented and the case where the invention is not implemented Configuration diagram of a boiler implementing the present invention

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram comparing a case where the invention is implemented with a case where the invention is not implemented, and FIG. 2 is a configuration diagram of a boiler implementing the invention. The upper part of FIG. 1 shows the case where the present invention is implemented, and the lower part shows the case where the present invention is not implemented, and describes the operation process and the damper position. The figure shows a boiler 1 that performs three-position combustion control of high combustion, low combustion, and stop, and the combustion air is supplied by operating the blower 2. A damper 3 for adjusting the supply amount of combustion air and a fuel supply amount adjusting device 7 for adjusting the fuel supply amount are provided, and the combustion amount is controlled by adjusting the combustion air supply amount and the fuel supply amount. The damper 3 is provided in the air passage connecting the blower and the combustion device 4, and the flow passage area of the air passage is changed by moving the damper 3 to adjust the amount of air sent to the combustion device 4. The damper position is set to the high fuel position, low fuel position, ignition position, fully closed position, high combustion position at high combustion, low fuel position at low combustion, ignition position at ignition, fully closed at combustion standby Position. The fuel supply amount adjusting device 7 also adjusts the fuel supply amount in accordance with the combustion amount, and supplies a high combustion fuel amount during high combustion, a low combustion fuel amount during low combustion, and a fuel supply during combustion standby. Stop.

  The boiler 1 is provided with a steam pressure detection device 5 that detects the generated steam pressure value, and the boiler is operated based on the steam pressure value detected by the steam pressure detection device 5. When a single boiler is installed, the steam pressure value detected by the steam pressure detection device 5 is sent to the operation control device 6. If the steam pressure value sent from the steam pressure detection device 5 is equal to or lower than the lower limit value of the pressure adjustment range, the operation control device 6 outputs a combustion request and burns the boiler. At the time of combustion, the amount of combustion is adjusted by high combustion and low combustion according to the steam pressure value, and by performing combustion, the water pipe in the boiler is heated to supply steam. When the steam pressure value rises due to the steam supply and exceeds the upper limit value of the pressure adjustment range, the operation control device 6 outputs a standby request and stops combustion of the boiler.

  In the case of multi-can installation where a plurality of boilers are installed, a number control device (not shown) is provided, and the operation of each boiler is performed based on a command from the number control device. The steam pressure detecting device 5 is provided in a steam collecting portion that collects the steam of each boiler, and sends the steam pressure value detected by the steam pressure detecting device 5 to the unit control device. The unit control device determines the combustion amount of the boiler based on the steam pressure value, outputs a combustion request to the required number of boilers, performs combustion, and outputs a standby request to the boiler that no longer needs combustion .

  In a boiler that has requested combustion, the blower 2 starts to operate before starting combustion, performs pre-purge to ventilate the interior of the furnace by sending only air into the furnace, and performs ignition after completion of pre-purge. To start. Even when the combustion is stopped, in the boiler that has been requested to wait, the operation of the blower 2 is continued even after the fuel supply is stopped, and after the combustion is stopped, only the air is sent into the furnace to ventilate the furnace. Perform post-purge.

  Further, in a boiler in which the fuel supply amount and the combustion air supply amount are adjusted, it is necessary to supply appropriate amounts of fuel and combustion air in order to perform stable combustion. If a predetermined amount of air cannot be supplied due to a damper position shift or the like, the ratio of fuel to air collapses and the combustion state becomes worse. Therefore, when pre-purge is started from the combustion standby state and when post-purge is started from the combustion state, the damper stops at a predetermined position when the damper is moved, and it is confirmed whether the limit signal is correctly output. Perform limit check. At this time, a substrate check is also performed to confirm whether the operation control device 6 is operating correctly. Before starting combustion, a signal check including a limit check and a substrate check is performed to confirm that proper combustion can be performed with a correct air-fuel ratio. If there is a combustion request during post-purge, the limit check time during pre-purge is shortened by taking over the limit check of the damper that was performed during post-purge as the limit check during pre-purge. .

  The operation status of the boiler will be described with reference to FIG. In FIG. 1, the operation process is combustion, and the damper position starts from the high combustion position. Here, combustion is performed at high combustion. When the steam pressure value rises by performing high combustion, the operation control device 6 uses the fuel supply amount and the combustion air supply amount for low combustion, and reduces the steam supply amount by reducing the combustion amount to low combustion. When the steam pressure value rises even at low combustion and the steam pressure value exceeds the upper limit of the pressure adjustment range, the operation control device 6 outputs a standby request and stops combustion.

  When the fuel supply is stopped when the combustion is stopped, the combustion of the boiler is stopped. However, when the combustion is stopped, the post-purge needs to be performed, so that the operation of the blower is continued. Since post purge is performed for furnace ventilation, it is not necessary to change the damper position in that sense, but in the present invention, the damper position is once closed to the fully closed position, the ignition position, the low fuel position, Change to a high burn position, and then change to a low burn position. The operation control device 6 performs a signal check including a damper limit check and a substrate check.

If the combustion request is not output before the post purge for a predetermined time is completed, the operation of the blower 2 is stopped and the damper position is set to the fully closed position to enter a combustion standby state.
After that, when the combustion is stopped and the steam pressure value decreases and the boiler needs to be burned, the operation control device 6 outputs a combustion request and restarts the combustion of the boiler. When there is an output of a combustion request, the operation of the blower is started and pre-purge is performed. At the time of pre-purge, a signal check consisting of a damper limit check and a substrate check is performed, and when pre-purge starts, the damper position that was in the fully closed position is changed to the ignition position, low fuel position, high fuel position, Furthermore, before starting combustion, the damper position is confirmed as the low fuel position.

  Since the time required for the signal check is shorter than the time required for the pre-purge, even if the signal check is performed here, the signal check is completed during the pre-purge, so the start of combustion is not delayed. When the pre-purge for a predetermined time is completed, combustion is started with the damper position set to the ignition position. After the start of combustion, the damper position is switched between a low fuel position and a high fuel position according to the amount of combustion. When the combustion raises the steam pressure value and reaches the upper limit of the pressure adjustment range and outputs the standby request, the combustion is stopped and the post purge is started. When post-purge is started, the signal is checked as in the previous case.

  In the previous post purge, the combustion request was not output during the post purge, so when the predetermined post purge time passed, the air supply was stopped and the machine was in a standby state. Output has been made. If a combustion request is output during post purge, post purge is switched to pre purge. Since the signal check performed before the output of the combustion request is the same as the signal check performed at the time of the pre-purge, the signal check is taken over when the post-purge is switched to the pre-purge. As a result, it is not necessary to perform the signal check that has been completed so far, and only the remaining signal check needs to be performed. Therefore, the time required for the signal check performed after the output of the combustion request is shortened.

  Further, when the post purge is switched to the pre purge, the pre purge time is shortened by setting the post purge execution time as the pre purge execution time. If the post-purge execution time is the same as or longer than the pre-purge setting time, it is possible to shift to the ignition process simultaneously with the output of the combustion request. When the post-purge execution time is shorter than the pre-purge setting time, the pre-purge execution time is set to a time obtained by subtracting the post-purge execution time from the pre-purge setting time, thereby shortening the pre-purge time after the combustion request. When the pre-purge for a predetermined time is completed, the process proceeds to the ignition process, whereby the time from the output of the combustion request to the start of combustion can be shortened.

  In addition, as described in the lower part of FIG. 1, when the present invention is not implemented, the signal check is started after the output of the combustion request is performed, and the start of the combustion is the end of the signal check. Because of the need to wait, the start of combustion was delayed by that much. However, when the present invention is implemented, the start of combustion can be accelerated, so that the followability to the load is improved.

1 boiler
2 Blower
3 Damper
4 Combustion device
5 Steam pressure detector
6 Operation control device
7 Fuel supply amount adjustment device

Claims (1)

It has a blower that supplies combustion air, a damper that adjusts the supply amount of combustion air, and a fuel supply amount adjustment device that adjusts the fuel supply amount, and adjusts the combustion amount by adjusting the combustion air supply amount and the fuel supply amount. When a standby request is received during combustion, post-purge is performed and then the operation is stopped to enter a combustion standby state.When a combustion request is received during combustion standby or during post-purge, pre-purge is performed. In a combustion apparatus that starts combustion after being performed and enters a combustion state, when pre-purge is started from the combustion standby state and when post-purge is started from the combustion state, a limit check of the damper is performed, When a combustion request is received during post-purge, the damper limit check that was performed during post-purge is pulled as the limit check during pre-purge. In Gukoto, combustion apparatus, characterized in that to shorten the time required for the limit check during pre-purge.

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