JP4939871B2 - Combustion device - Google Patents

Description

  The present invention relates to a combustion apparatus in which an air supply amount is changed in accordance with a process such as a high combustion process, a low combustion process, an ignition process, a high combustion process, a middle combustion process, or a low combustion process. The present invention relates to a combustion apparatus capable of preventing combustion from becoming unstable due to the air supply amount deviating from an appropriate value when adjusting the air supply amount.

  As described in Japanese Utility Model Publication No. 6-12348, in a combustion apparatus such as a boiler, combustion air is widely supplied by a blower. For combustion devices that require different amounts of air for each process, such as the high combustion process, low combustion process, and ignition process, install a damper device in the middle of the air passage connecting the burner section and the blower, and change the opening of the damper To adjust the air supply to the burner. In addition, when combustion is not performed, the damper may be set to a fully closed position to reduce heat dissipation from the boiler. In this case, the opening of the damper is set to the fully closed position, ignition position, low combustion position.・ The high combustion position is 4 positions.

  A limit switch is used to detect the damper position. FIG. 11 describes examples of limit detection positions and damper movement. In the case of FIG. 11, the limit detection positions are a fully closed position, an ignition position, a low combustion position, and a high combustion position in order from the state where the damper is closed. In the limit switch, when the damper reaches the position where the position is detected, it changes from on to off, or from off to on, and the damper is in the specified position by the change of the limit signal. Is detected and the movement of the damper is stopped. However, the limit switch that detects the position of the damper has a position that detects the limit signal while moving the damper in the closing direction, and a position that detects the limit signal while moving the damper in the opening direction. There was a problem that a shift occurred.

  In the case of FIG. 11, the movement of the damper is indicated by an arrow and a solid line. The low combustion position is detected at the time of transition from the ignition process to the low combustion process and at the time of transition from the high combustion process to the low combustion process. During the transition from the ignition process to the low combustion process, it is determined that the damper is in the low combustion position when it is detected that the damper has opened from the low combustion position. When it is detected that the valve is closed from the low combustion position, it is determined that the damper is in the low combustion position. At this time, it is inevitable that there is a difference between the position where the damper is opened from the low combustion position and the position where the damper is closed from the low combustion position.

  FIG. 10 is a time chart showing changes in the combustion process and the damper opening, and will be described based on the time chart. In this figure, pre-purge and post-purge for ventilating the combustion chamber before and after combustion are performed. In the figure, since the process starts from the stop step, the first damper opening degree is the fully closed position, and the operation of the blower is stopped. When starting combustion, a pre-purge process is performed before ignition. In the pre-purge process, the operation of the blower is started and the damper position is set to the high combustion position so that air is supplied to the combustion chamber to ventilate the combustion chamber.

When pre-purge is completed, ignition is performed. In the ignition process, the air blows off when the air amount is large. Therefore, the air supply amount is reduced by setting the damper position to the ignition position, and ignition is performed. Thereafter, the combustion apparatus adjusts the combustion amount to low combustion or high combustion based on the combustion command of the boiler. The air supply amount is adjusted by setting the damper position to the low combustion position in the low combustion process and setting the damper position to the high combustion position in the high combustion process. At the end of combustion, post-purge is performed and then the operation of the blower is stopped, and the combustion is stopped with the damper in the fully closed position. In this case, the damper opening degree is different between when the ignition position is changed from the ignition position to the low combustion position and when the damper opening degree is changed from the high combustion position to the low combustion position. In this figure, the position stopped based on the detection of the limit signal when moving from the high combustion position to the low combustion position is the correct low combustion position, and the limit signal is displayed when moving from the ignition position to the low combustion position. The position stopped based on the detection is shifted to the high combustion position side from the correct low combustion position. If the damper position is misaligned, the air supply will deviate from the appropriate value, causing combustion to become unstable, increasing the amount of CO, NOx, soot, etc., and blowing out the flame. Will occur.
Japanese Utility Model Publication No. 6-12348

  The problem to be solved by the present invention is that the air supply amount is adjusted by the damper device, and in the combustion device in which the damper position is detected by the limit switch, the damper opening is deviated from the set position, thereby supplying the air. The purpose is to prevent the amount from deviating from the proper value and unstable combustion.

The invention according to claim 1 is a combustion device in which air is supplied to the burner unit by a blower, and the amount of air supply is changed according to the operation process, and a blower path connecting the blower and the burner unit The amount of air supply is adjusted by changing the opening degree of the damper device provided in the middle of the combustion chamber, and the limit switch is used to detect the damper position. The limit switch opens the damper. When the damper is closed, the limit signal is output when the damper is opened or closed by detecting that the damper is switched from ON to OFF. The position where the limit switch is switched from OFF to ON is set to the side where the damper is opened rather than the position where the limit switch is switched from ON to OFF. A position in which bets signal is turned on from off, and provided out a position from ON to OFF, to reduce the air supply flow rate, when being moved in a direction to close the opening of the damper, the air after the change When the damper is stopped based on the detection that the limit signal of the limit switch corresponding to the supply amount position has been turned off from on, and the air supply amount is increased, it is changed when the damper opening is moved in the opening direction. After the change direction of the damper is reversed based on the detection that the limit signal of the limit switch corresponding to the later air supply amount position is turned on from OFF, the limit signal of the limit switch corresponding to the changed air supply amount position is turned on. The control is performed to stop the damper based on the detection that it has been turned off .

  According to a second aspect of the present invention, when the opening degree of the damper is changed in the combustion apparatus, the air supply amount position after the change is reversed once after passing through the high combustion process, the low combustion process, and the ignition. When the air supply amount is set in three or more stages, such as in the high combustion process, middle combustion process, and low combustion process, the intermediate position other than the largest air supply amount and the smallest air supply amount. It is characterized in that it is performed only when shifting to the air supply amount.

  By carrying out the present invention, the air supply amount can always be kept appropriate, so that the combustion state can be stabilized, and the increase in the generation amount of CO, NOx, and soot, and the occurrence of flame blow-off can be prevented. be able to.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a boiler embodying the present invention, FIG. 2 is a time chart in an embodiment of the present invention, FIG. 3 is an explanatory diagram of a limit signal detection position of a damper position, and FIGS. It is explanatory drawing which showed the flow of the electric current in a circuit diagram. FIG. 9 is an explanatory diagram of the limit signal detection position of the damper position in another embodiment.

  First, FIG. 1 will be described. In FIG. 1, the combustion apparatus is provided in the upper part of the boiler main-body part 2, and it burns by supplying fuel and air to the burner part 1 of a combustion apparatus. The combustion air is supplied to the combustion device by operating the blower 3, and the burner unit 1 and the blower 3 are connected by a blower passage 6. A damper device 4 for changing the flow passage area in the air passage 6 is provided in the middle of the air passage 6, and the combustion air supply amount is adjusted by changing the opening degree of the damper device 4. The fuel supply amount is adjusted by the fuel supply amount control device 5 provided in the fuel supply path. An operation control device 7 connected to the blower 3, the damper device 4, and the fuel supply amount control device 5 is provided, and the operation control of each part is performed by the operation control device 7.

  The combustion device controls combustion at three positions of high combustion, low combustion, and stop. In the case of high combustion, the amount of fuel supplied is increased and the amount of combustion air is increased to increase the combustion amount. In this case, the combustion amount is reduced by reducing the fuel supply amount and the combustion air amount. As shown in FIG. 3, the damper device 4 sets a fully closed position and an ignition position in addition to the high combustion position and the low combustion position. The fully closed position is a position where the blades of the damper are perpendicular to the air flow direction in the air passage 6 so that the air supply amount increases in the order of the fully closed position, the ignition position, the low combustion position, and the high combustion position. Set. The damper device 4 has a configuration in which blades provided in the air passage 6 are rotated by DCM (damper control motor). A plurality of cams are provided on the damper shaft so that the position of the damper can be detected by the movement of the cam and the limit switch.

  Limit signal detection by the limit switch is performed at four locations: a high combustion position (cm3), a low combustion position (cm5), an ignition position (cm6), and a fully closed position (cm4). A cam is set corresponding to each damper position, and each limit switch outputs ON (a contact side) when the damper is opened from the set position, and outputs OFF when it is closed. The position of the damper is detected by detecting the limit signal so that the damper can be stopped at a predetermined position. In FIG. 3, the reason why the low combustion position is doubled is that there is a difference between the position where the limit signal is turned on and the position where it is turned off at the low combustion position.

  Next, the operation state and the movement of the damper will be described with reference to FIGS. 2 and 4 to 8. In the time chart of FIG. 2, since the combustion starts from the state of combustion stop, the first damper opening is the fully closed position, and the operation of the blower is stopped. When the combustion command is output to the boiler, the boiler starts combustion. When starting combustion, a pre-purging step is performed before ignition in order to perform ignition with no fuel remaining in the combustion chamber. In the pre-purge process, the operation of the blower is started and the damper position is set to the high combustion position so that air is supplied to the combustion chamber to ventilate the combustion chamber.

  When the damper position is changed from the fully closed position to the high combustion position, the damper position is moved by passing a current through the circuit of FIG. FIG. 4 shows a circuit for opening the damper to the high combustion position, and RY1 (fully opened) is turned on. When RY1 is turned on, current flows to cm3. cm3 is turned on and off based on the limit signal of the high combustion position, and is turned off when the damper is closed from the high combustion position. Therefore, until the damper reaches the high combustion position, current flows through the DCM (damper control motor) in the opening direction (thick solid line), and the damper is driven in the opening direction. When the damper reaches the high combustion position and the limit signal of cm3 is turned on, the current to the DCM stops and the movement of the damper stops, and a signal of the high combustion position is output to the operation control device 7 (thick broken line) ).

  In the operation control device 7, ventilation of the combustion chamber is continued until the pre-purge time ends, and when the pre-purge time ends, the operation control device 7 shifts to an ignition process. In the ignition process, the air blows off when the amount of air is large. Therefore, ignition is performed with the damper position as the ignition position. FIG. 5 is a circuit for closing the damper to the ignition position, and RY2 (ignition) is turned on. When RY2 is turned on, current flows to cm6. cm6 is turned on and off based on the limit signal of the ignition position, and is turned on when the damper is opened from the ignition position. Therefore, until the damper reaches the ignition position, a current flows in the DCM in the closing direction (thick solid line), and the damper is driven in the closing direction. When the damper reaches the ignition position and the cm6 limit signal is turned off, the current to the DCM stops, so the movement of the damper stops, and the ignition position signal is output to the operation control device 7 (thick broken line). The operation control device 7 reduces the air supply amount by setting the damper to the ignition position, and starts the operation of the ignition device (not shown) and the supply of fuel to perform ignition.

  The operation control device 7 performs ignition in a state where the damper is in the ignition position, and when the ignition process is completed, the operation shifts to the low combustion process. FIG. 6 is a circuit for opening the damper to the low combustion position, and RY5 (ignition → low combustion) is turned on. When RY5 is turned on, current flows to DCM while cm5 is off. cm5 is turned on and off based on the limit signal of the low combustion position, and is turned off when the damper is closed from the low combustion position. Therefore, until the damper reaches the low combustion position, a current flows in the DCM in the open direction (thick solid line), and the damper is driven in the open direction. When the damper reaches the low combustion position and the limit signal of cm5 is turned on, the current to the DCM stops, so that the movement of the damper stops and a signal of the low combustion position is output to the operation control device 7 (thick broken line) ).

  However, since there is a difference between the position where the limit signal turns from on to off and the position where the limit signal turns from off to on, the damper position at this point is shifted to the high combustion position side from the original low combustion position. . Therefore, the operation control device 7 moves the damper in the closing direction to set the damper to the original low combustion position. FIG. 7 shows a circuit for closing the damper to the low combustion position, and RY5 (ignition → low combustion) is turned off. When RY5 is turned off, the current to DCM flows in the opposite direction, that is, the current flows in the closed direction in DCM. The damper is moved in the closing direction until cm5 is turned off (thick solid line). The damper is closed until cm5 is turned off, and when the limit signal of cm5 is turned off, the current to the DCM stops, so that the movement of the damper is stopped and a signal for the low combustion position is output to the operation control device 7 ( Bold broken line). By performing an operation of reversing the damper moving direction, an air supply amount suitable for low combustion can be obtained.

  Thereafter, when a combustion command for high combustion is output to the boiler, the operation control device 7 sets the combustion amount of the combustion device to high combustion. When the combustion amount is increased from low combustion to high combustion, the damper position is changed from the low combustion position to the high combustion position. When the damper position is opened to the high combustion position, the damper is set to the high combustion position using the circuit of FIG. 4 described above. Similarly, when a low combustion combustion command is output to the boiler, the operation control device 7 sets the combustion amount of the combustion device to low combustion. When reducing the combustion amount from high combustion to low combustion, the damper position is changed from the high combustion position to the low combustion position. When closing the damper position to the low combustion position, the damper is set to the low combustion position using the circuit of FIG. 7 described above.

  When the combustion command for the boiler is finished, the operation control device 7 finishes the combustion by the combustion device. In this case, after the combustion is stopped, the operation of the blower is continued for a predetermined time, and a post purge for ventilating the combustion chamber is performed. Since the damper position in the post purge is the same as that at the time of low combustion, the damper position is not changed at the start of the post purge. When the predetermined post-purge time ends, the damper is in the fully closed position and the operation of the blower is also stopped.

  FIG. 8 is a circuit for closing the damper to the fully closed position, and RY3 (fully closed) is turned on. When RY3 is turned on, current flows to cm4. cm4 is turned on and off based on the limit signal at the fully closed position, and remains on until the damper is closed at the fully closed position. Therefore, until the damper reaches the fully closed position, a current flows in the DCM in the closing direction (thick solid line), and the damper is driven in the closing direction. When the damper reaches the fully closed position and the cm4 limit signal is turned off, the current to the DCM stops, so the movement of the damper stops, and the fully closed position signal is output to the operation control device 7 (thick broken line). ).

  By opening and closing the damper device as described above, the damper position when changing from the ignition process to the low combustion process and the damper position when changing from the high combustion process to the low combustion process can be made the same. Further, it is possible to prevent combustion from becoming unstable due to a shift in the supply amount of combustion air.

  In the present embodiment, the damper positions are four positions of a high combustion position, a low combustion position, an ignition position, and a fully closed position, but it can be similarly performed even in other cases. FIG. 9 shows the limit signal detection position of the damper and the movement of the damper in another embodiment. Here, there are five damper positions: a high combustion position, a medium combustion position, a low combustion position, an ignition position, and a fully closed position. In this case, the low combustion air supply amount and the medium combustion air supply amount, which are air supply amounts other than the largest air supply amount and the smallest air supply amount, are intermediate positions. There are two types of transition to the low combustion air supply amount, immediately after ignition and when the air supply amount is increased from the ignition position to the low combustion position and when the combustion amount is decreased from high combustion. There are two ways to shift to an air supply amount for medium combustion, when the combustion amount is increased from low combustion and when the combustion amount is decreased from high combustion. In order to keep the air supply amount constant during low combustion and medium combustion, the target position (low combustion position or medium combustion position) of the damper is set either when the air supply amount increases or when the air supply amount decreases. After passing, control to reverse the damper moving direction is performed.

  In addition, in the embodiment, the detection of the limit signal when the air supply amount is changed to the intermediate position is detected in a state in which the damper is moved in the opening direction and in a state in which the damper is moved in the closing direction. Both are possible. Therefore, for example, at the transition from the ignition process to the low combustion process, when the limit signal at the low combustion position is switched from off to on, the movement direction of the damper is reversed, and the limit signal at the low combustion position is changed from on to the previous time. It can be said that the damper is stopped when switched off. In this case, the set value of the combustion air supply amount can be reversed immediately after passing a little, and the width over which the combustion air supply amount becomes excessive can be reduced by passing the set value. it can. However, in order to be able to detect the limit signal from both, the control circuit becomes complicated. Therefore, the time from when the damper starts to move may be measured, and the moving direction may be reversed after a predetermined time since the damper starts moving.

  If the air supply amount is increased to medium combustion as in the middle combustion process, and the case where the air supply amount is decreased to intermediate combustion occurs at approximately the same rate, the air supply amount is increased. Even if it is set to reverse the direction of damper movement at the time of either time or decrease, there is no big difference. However, since the transition from the ignition process to the low combustion process is performed only once immediately after the ignition, in this case, adjusting the stop position by reversing the moving direction of the damper is a low process from the ignition process. It is assumed that the damper is opened for shifting to the combustion process. The number of times of reversal can be reduced by reversing at the low combustion position when the damper is open.

Outline diagram of boiler implementing the present invention Time chart showing damper opening and operation process in the embodiment Explanatory drawing which showed the limit signal detection position of a damper in an example, and the movement of a damper Circuit diagram showing the current flow when opening the damper toward the high combustion position Circuit diagram showing the current flow when closing the damper toward the ignition position Circuit diagram showing the current flow when opening the damper toward the low combustion position Circuit diagram showing current flow when closing damper to low combustion position Circuit diagram showing the flow of current when closing the damper toward the fully closed position Explanatory drawing which showed the limit signal detection position of the damper in another example, and the movement of a damper Time chart showing damper opening and operation process in conventional control example Explanatory drawing showing the limit signal detection position of the damper and the movement of the damper in the conventional example

Explanation of symbols

1 Combustion device
2 Boiler body
3 Blower
4 Damper device
5. Fuel supply control device
6 Air duct
7 Operation control device

Claims (2)

Air is supplied to the burner part by a blower, and the combustion apparatus changes the air supply amount according to the operation process, and opens a damper device provided in the middle of the air passage connecting the blower and the burner part. In the combustion device that adjusts the air supply amount by changing the degree and uses a limit switch to detect the damper position, the limit switch switches from off to on when the damper is open, When the damper is closed, the limit signal can be output from either when the damper is opened or when it is closed by detecting that the damper switches from on to off. The limit signal is switched from OFF to ON by setting the damper to the side where the damper is opened rather than the position where the switch is switched from OFF to ON. A position that has provided out a position from ON to OFF, to reduce the air supply flow rate, when being moved in a direction to close the opening of the damper, which corresponds air supply position after the change of the limit switch When the damper is stopped based on the detection that the limit signal has been turned off and the air supply amount is increased, when the damper opening is moved in the opening direction, it corresponds to the changed air supply amount position. After reversing the damper change direction based on the detection that the limit switch limit signal was switched from OFF to ON, the limit switch limit signal corresponding to the changed air supply amount position was switched from ON to OFF. A combustion apparatus that performs control to stop a damper based on detection . In the combustion apparatus according to claim 1, when changing the opening degree of the damper, after changing the air supply amount position once changed, it is reversed that the high combustion process, the low combustion process, the ignition process, or the high combustion process. When the air supply amount is set to three or more stages as in the process / medium combustion process / low combustion process, it shifts to the intermediate air supply amount other than the largest air supply amount and the smallest air supply amount. A combustion apparatus, which is performed only when

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