JP2008039215A - Combustion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a blower motor from being overheated when the operation of the blower motor is repeatedly started in a short time, in a combustion device 4 supplying the air for combustion by a blower 5. <P>SOLUTION: In the combustion device 4 where the blower 5 is stopped after a prescribed delay time from the stop of fuel supply, when the combustion is stopped, a time from the start of the operation of the blower is measured as a blower operation time, so that the blower 5 is stopped after operating the blower for a short delay time set by a comparatively short time after the stop of the fuel supply when the stop of combustion command is received after the blower operation time is over a prescribed time T, and the blower 5 is stopped after the blower is operated for a long delay time set by a comparatively long time, when the stop of the combustion command is received before the blower operation time is over the prescribed time T. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a combustion apparatus that supplies combustion air using a blower. More specifically, the present invention relates to the prevention of adverse effects on a blower motor due to a decrease in the interval at which a blower starts operation. It is related with the combustion apparatus which can be performed.

  There is a combustion apparatus in which a blower is provided and combustion is performed while air for combustion is fed into the combustion chamber. In this combustion apparatus, in order to prevent unburned fuel from remaining in the combustion chamber after the combustion is stopped, the blower continues to operate for a predetermined delay time after the fuel supply is stopped, Ventilation (post-purge) is performed. Also, when combustion is started, ventilation (pre-purge) is performed in the combustion chamber by operating the blower for a predetermined time before starting fuel supply. In the combustion apparatus, when a combustion command is received, combustion is started after the combustion preparation process is performed. When the combustion command is interrupted, the fuel supply is stopped to stop the combustion, and when the post purge to be continued is finished, the blower The operation is stopped and the combustion standby state is entered.

  As for the delay time of the blower stop (post-purge execution time), a predetermined time is generally set in advance, but as in the invention described in JP-A-7-260142, the combustion state The post purge time may be changed depending on the situation. In the invention described in Japanese Patent Laid-Open No. 7-260142, there is described a configuration in which a time measuring means for measuring the combustion continuation time is provided, and the post purge time is set longer as the combustion continuation time is longer. This is because, as the combustion duration is longer, the amount of leaked combustion gas increases, so when the combustion duration is long, the post-purging is executed for a long time, thereby accurately discharging the leaking combustion gas. It is.

By the way, in a blower motor, a large amount of current flows at the start of operation. In the case of direct injection start-up, a current exceeding about 6 times the rated current and exceeding twice the rated current flows even if the star delta start is performed. The start of the blower is started by the start of the combustion command. Is repeatedly issued in a short time, the start and stop of the blower is repeated in a short time. In this case, the average current value of the blower motor is increased by a large amount of current supplied every time the blower is started, and the motor is overheated when the cooling capacity of the motor is exceeded. When the motor is overheated, there is a problem that the grease of the motor bearing portion is deteriorated by heat, and further, the blower motor is burned out. When the temperature of the blower motor when the control of actually operating the blower for 10 seconds and stopping for 20 seconds was repeated for 30 minutes was measured, it was about 40 ° C. higher than when the blower was continuously operated.
JP-A-7-260142

  The problem to be solved by the present invention is that, in a combustion apparatus in which combustion air is supplied by a blower, the blower motor is overheated by repeatedly starting the operation of the blower motor in a short time. An object of the present invention is to provide a combustion apparatus that can prevent the above.

  According to the first aspect of the present invention, there is provided a control device for controlling the air supply by the blower and the fuel supply by the fuel supply control device, and the air from the blower and the fuel from the fuel supply control device are mixed and burned in the combustion chamber. The control device receives the combustion command, starts combustion by the combustion device, stops the combustion in response to the stop of the combustion command, and stops the fuel supply when stopping the combustion In the combustion apparatus that is designed to stop the blower after a predetermined delay time, the control device measures the time from the start of the blower operation as the blower operation time, and the blower operation time exceeds the predetermined time T If the combustion command is subsequently stopped, the blower is stopped after operating the blower for a short delay that is set to a relatively short time after the fuel supply is stopped. When receiving a stop combustion command before exceeding the time T, and performs a control to stop the air blower after running long delay component blower is set to a relatively long period of time.

  According to a second aspect of the present invention, in the combustion apparatus, the long time delay is determined based on a value obtained by subtracting a measured blower operating time from a predetermined time T. It is characterized by that. Further, in the invention according to claim 3, in the combustion apparatus, the value of the long time delay obtained by subtracting the blower operating time from the predetermined time T is shorter than the value of the short time delay. In such a case, control is performed to stop the blower after operating the blower for at least a short delay.

  When the combustion command is received during the blower stop delay time after the combustion stop in the combustion apparatus according to claim 4, the blower stop delay process is terminated and the pre-purge is started. When pre-purge is started while the blower is operating, control is performed to shorten the pre-purge time than usual. The invention according to claim 5 is characterized in that, in the combustion apparatus, the predetermined time T is set based on a blower operation start interval necessary to prevent the blower motor from being overheated. And

  According to a sixth aspect of the present invention, in the above combustion apparatus, a damper device that blocks the flow of air is provided between the blower and the combustion chamber, and when the air from the blower is sent to the combustion chamber, the damper device is opened to open the air Since the combustion command was stopped before the blower operating time exceeded the predetermined time T, the control to operate the blower for a long delay set to a relatively long time after the combustion stopped was performed. When performing, the control which closes the said damper is performed during the air blower operation | movement after the combustion stop after the short delay part progresses, It is characterized by the above-mentioned. The invention according to claim 7 is characterized in that, in the combustion apparatus provided with the damper device, the damper is opened at a minimum opening degree even during operation of the blower after the combustion is stopped.

  By implementing the present invention, even if the start and stop of the combustion command are repeated at short intervals, the interval at which the blower operation is started does not become shorter than the predetermined time, so a large amount of current at the start of the blower operation This prevents the blower motor from overheating. If the delay time for stopping the blower is lengthened, there will be a problem that the amount of electricity consumed and the amount of heat dissipation will increase, but the blower will only stop if there is a need to increase the fan start time because the blower operation time is short. The delay time is increased, and when the blower operating time is longer than the set time T, the delay is short, so that it is possible to prevent an unnecessary increase in electric consumption and heat dissipation. Further, the long delay is necessary for opening the blower operation start interval, and a certain interval time (predetermined time T) is required, but it is not necessary to extend the required time beyond that. Therefore, if the long-time delay is obtained by subtracting the measured blower operating time from the predetermined time T, the long-time delay can be set to a necessary and sufficient time without becoming too long.

  Even if the blower re-operation prohibition time is set without increasing the delay time until the blower stops, the operation start interval of the blower motor can be extended. However, in this case, since the blower cannot be operated until the blower re-operation prohibition time ends, the start of combustion is delayed. With respect to this point as well, in the present invention, the operating time of the blower is extended, and pre-purge at the start of combustion can be started in the middle of the delay time, so that the problem of the start of combustion being delayed does not occur. Burnout can be prevented.

  In addition, when the pre-purge is started in the blower operating state, the air can be supplied from the beginning of the pre-purge time, so that the pre-purge time can be shortened than usual. The pre-purge is performed based on a standard that air of 50% or more of the maximum combustion amount air volume is supplied at least four times the combustion gas side space volume. The amount of air from the blower is 0 at the start of the blower operation and increases thereafter. Therefore, when setting the pre-purge time from the start of the blower operation, the fixed time from the start of the blower operation is invalidated, and the pre-purge time Needs to be set longer. However, if the blower is already operating normally at the start of pre-purge, the required amount of air can be supplied at the start of pre-purge, so the pre-purge time can be shortened. By shortening the pre-purge time, the time required for preparation until the start of combustion can be shortened, and the followability of combustion can be improved.

  When a damper device is provided between the blower and the combustion chamber, when the blower is operated for a long time after the combustion is stopped, the flow of air sent to the combustion chamber is controlled by closing the damper device. Therefore, the amount of heat released from the combustion chamber can be reduced, and the efficiency can be increased in the case of equipment that uses heat, such as a boiler. Conversely, when the blower is operated for a long time after the combustion is stopped, if the damper device is opened, the temperature of the blower can be kept lower, and the grease of the blower bearing portion deteriorates. The occurrence of adverse effects can be suppressed. When opening the damper device, the damper opening is set to the minimum opening (low combustion opening) so that the cooling of the blower motor is not hindered and the amount of air sent to the combustion chamber is reduced. An increase in the amount of heat dissipation can be prevented.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a boiler system when the combustion apparatus of the present invention is installed in a boiler, FIG. 2 is a flowchart of a blower stop delay time setting program in one embodiment, and FIG. 3 is a blower when the present invention is implemented. FIG. 4 is a time chart showing an operating condition of a blower in a conventional example for comparison.

  First, the configuration of the device will be described with reference to FIG. FIG. 1 relates to a boiler system having a combustion apparatus according to the present invention, in which three boilers that generate steam are installed. Each boiler 1 is provided with a combustion device 4. The combustion device 4 supplies combustion air by a blower 5, and the fuel supply control device 6 controls fuel supply. A damper device 8 that adjusts the amount of air supplied from the blower 5 is provided in the middle of the air passage through which the air from the blower 5 passes. The operation of the blower 5, the operation of the fuel supply control device 6, and the opening setting of the damper device 8 are automatically controlled by the control device 7 provided in each boiler. The combustion device controls combustion at three positions of stop, low combustion, and high combustion, and adjusts the amount of fuel supplied from the fuel supply control device 6 according to the amount of combustion. The damper device 8 is also controlled at three positions: an opening for operation stop (fully closed), an opening for low combustion (LO), and an opening for high combustion (HI). Adjust the air volume.

  Each boiler 1 is connected to a common steam header 2, and the steam generated in each boiler is collected in the steam header 2, and the steam is supplied from the steam header 2 to the steam using device. The operation of each boiler is controlled by a number control device 3 that determines the number of boilers to be burned based on the steam pressure in the steam header 2. The number control device 3 is connected to the control device of each boiler 1 and outputs a combustion command to the required number of boilers 1. The number control device 3 outputs a combustion command to many boilers as the steam pressure in the steam header 2 is low, and the combustion amount of the boiler is also changed from low combustion to high combustion. Increase steam generation. In addition, when the steam pressure increases, the number of boilers that output a combustion command is reduced, and the combustion amount of the boiler is changed from high combustion to low combustion, thereby reducing the amount of steam generated in the entire boiler. The control device 7 that has received the combustion command from the number control device 3 starts combustion of the boiler 1, and stops the combustion of the boiler 1 when the combustion command is stopped.

  When the boiler 1 receives the output of the combustion command from the number control device 3, it starts the combustion preparation process. In the combustion preparation step, the damper device 8 is opened and only the blower 5 is operated to perform pre-purge to ventilate the combustion chamber. When the pre-purge for a predetermined time is completed, the operation of the blower 5 is continued, the ignition device (not shown) is operated, and the fuel supply control device 6 starts supplying fuel to perform combustion. When the steam pressure in the steam header 2 rises to a predetermined value, the number control device 3 reduces the number of boilers that output a combustion command. When the combustion command from the unit control device 3 is interrupted while combustion is being performed, the boiler 1 stops combustion. When stopping the combustion, the fuel supply control device 6 stops the fuel supply to stop the combustion, and even if the combustion is stopped, the operation of the blower 5 is continued, and the operation stop of the blower is performed for a predetermined time. Delay. After the combustion is stopped, the operation of the blower is continued, and air is sent into the combustion chamber to perform post-purge to ventilate the combustion chamber.

  The blower stop delay time and the pre-purge time that are performed after the combustion is stopped are set based on the blower operating time. The setting method will be described based on FIG. 2 showing a flowchart of a program for setting the blower stop delay time and the pre-purge time. In this embodiment, in order to prevent overheating of the blower motor, the interval for starting the blower operation must be longer than 45 seconds. Further, when the combustion is performed in the combustion chamber, a post purge for 4 seconds is required. In this program, the set time T for determining the blower stop delay time is also set to 45 seconds. The long delay and the set time T are determined from the time of the blower operation start interval necessary to prevent the blower motor from being adversely affected, and the short delay is the post purge required when combustion is performed in the combustion chamber. Determine from time. Since the short delay is the post purge time, it is fixed at 4 seconds, and the long delay is a value obtained by subtracting the blower operating time from the set time T of 45 seconds. However, if the blower operating time is between 41 seconds and 45 seconds, and the value obtained by subtracting the blower operating time from the set time of 45 seconds is smaller than 4 seconds, the delay time is set to 4 seconds. When setting the pre-purge time from the start of the blower operation, it is necessary to set the pre-purge time longer by the time from the start of the blower operation until the predetermined amount of air blows. However, if the blower is already operating normally at the start of the pre-purge, the required amount of air can be supplied from the start of the pre-purge, so the pre-purge time can be shortened. Therefore, the pre-purge time has two stages, a long-time pre-purge and a short-time pre-purge, and the long-time pre-purge and the short-time pre-purge are set according to the blower operation status at the start of the pre-purge. The short time pre-purge is set to a set value of 10 seconds.

  The program starts at terminal (1). In the next step (4), it is first determined whether or not the blower is stopped. If the blower is stopped, the blower operation time is cleared in process (12), the pre-purge time is set to a long time (25 seconds) in process (13), and the stop delay time is set to time T in process (14). (45 seconds), and move to terminal (3). The next step of the terminal (3) is the process (18). In the process (18), the previous combustion command is replaced with the current combustion command. The program then returns to terminal (1). Even if the stop delay time is set here, this program only sets the delay time, and the blower stop delay is performed when the combustion command is stopped. Is not meant to be executed.

  If the blower is operating in the decision (4), the process proceeds to the process (5). In the process (5), the blower operating time, which is the time during which the blower is operating since the start of the blower operation, is counted. Next, the process proceeds to decision (6) to confirm the combustion command. If the combustion command is on, the process branches to the terminal (2). If the combustion command is off, the process branches to the determination (7). When the combustion command is on, the terminal (2) shifts to the decision (15), and the decision (15) branches according to the previous combustion command. If the previous combustion command was on, that is, if the combustion command was on from before the previous time, go to the terminal (3) .If the previous combustion command was off, that is, the combustion command was off until just before. However, if it is now that the combustion command has been turned on, the process branches to decision (16). In decision (16), the process branches based on the operating state of the blower. In the present embodiment, the blower performs star delta startup, and if the current star operation is in progress immediately after startup, the flow proceeds to the terminal (3), and if it is in the normal operation delta operation, the flow proceeds to processing (17).

  If it is immediately after the combustion command is turned on, pre-purge is in progress and the pre-purge time is determined. In this embodiment, when the pre-purge is started in the star operation state (when the pre-purge is started simultaneously with the start of the blower operation or when the pre-purge is started in the star operation state even if the blower operation is earlier) When the pre-purge time is set to a long time and the pre-purge is started in the delta operation state, the pre-purge time is set to a short time on the assumption that the pre-purge is started in a normal operation state. If pre-purge is started while the blower is in delta operation, the pre-purge time is set to a short time (10 seconds) in process (17). If the blower is still in star operation immediately after starting operation, Do not change from the long time (25 seconds) pre-purge as set in (13). After processing in the processing (17), the terminal merged with what was transferred to the terminal (3) in the judgment (15) and judgment (16), and after the previous combustion command was replaced with the current combustion command in the processing (18), the terminal Return to (1).

  If the combustion command is ON in judgment (6) and the routine proceeds to judgment (7), the process branches based on the previous combustion command in judgment (7). In Judgment (7), if the previous combustion command was on, that is, if the combustion command was on until immediately before, but now the combustion command has been turned off, go to Judgment (8), and the previous combustion command is turned off. If this is the case, that is, if the combustion command has been turned off from before the previous time, the process proceeds to the terminal (3). Here, when the combustion command is changed to OFF, since the operation of the blower is stopped after the blower stop delay time from this time, the blower stop delay time is determined after the determination (8). In the judgment (8), the blower operating time that has been counted in the process (5) is compared with the set time T. When the blower operating time is longer than the set time T, that is, when the delay time for expanding the blower operation start interval is not required, the stop delay time is only the time required for the post purge in the process (11). Set to seconds. If the blower operating time is shorter than the set time T, that is, if a delay time is required to widen the blower start time, the time and post after subtracting the blower operating time from the set time T in decision (9) Compare 4 seconds, the time required for purging. When the time obtained by subtracting the blower operating time from the set time T in the determination (9) is shorter than 4 seconds, the process proceeds to the process (11) and the stop delay time is set to 4 seconds. If the time obtained by subtracting the fan operating time from the set time T is longer than 4 seconds, the process proceeds to the process (10), and the stop delay time is set to the time obtained by subtracting the fan operating time from the set time T. . After setting the stop delay time, the process proceeds to the process (18) through the terminal (3), and returns to the terminal (1) after the process (18).

  This will be described based on a time chart. FIG. 3 is a time chart in the embodiment of the present invention, and FIG. 4 is a time chart in the conventional control. The time charts of FIGS. 3 and 4 show the situation of the blower stop delay in two patterns when the combustion command output time is long and short. In the figure, the combustion command for 50 seconds is first output, and thereafter, the combustion command stop for 20 seconds and the combustion command output for 10 seconds are repeated, and the time when the first combustion command output is started is time 0 seconds.

  This will be described with reference to FIG. When the output of the combustion command is started at time 0 second, the boiler controls the operation of the blower and the damper opening to be HI, and starts counting the blower operation time simultaneously with the start of the blower operation. The blower always operates while the combustion command is output, and supplies more air by setting the damper opening to HI during pre-purge and high combustion. When the output of the combustion command is started, a pre-purge time is set in order to perform pre-purge. The pre-purge time is set to a short time (10 seconds) when starting with the fan already operating in delta operation, but since the fan was not operating at time 0 second, the pre-purge time here The time is set for a long time (25 seconds). When starting operation from the state where the blower is stopped, if it is star delta start, it starts operation with star operation, but since a large amount of current flows through the blower motor at the start of operation, the current value is prominent, The current value then decreases and stabilizes. When the pre-purge for the pre-purge set time is completed, the boiler starts combustion. During boiler combustion, low combustion fuel is supplied during low combustion, the damper opening is set to low combustion opening LO, high combustion fuel is supplied during high combustion, and the damper opening is high combustion. HI of the opening.

  After the output of the combustion command starts at time 0 second, the combustion command is interrupted at time 50 seconds. Therefore, at time 50 seconds, the fuel supply is stopped, combustion is terminated, and post purge is performed. The control device 7 compares the blower operating time counted when the blower is operating with the set time T (45 seconds). Since the combustion command was output from time 0 seconds to time 50 seconds, the blower operating time is 50 seconds. Since the blower operating time of 50 seconds is longer than the set time T of 45 seconds, the blower stop delay here is a short time delay. Since the short-time delay is set to be fixed at 4 seconds, post-purge is performed here by continuing the operation of the blower for 4 seconds after the combustion is stopped. In the case of post purge, the damper is kept open because it is necessary to send air into the combustion chamber. When the post-purge is finished and the operation of the blower is stopped, the damper is also closed and the combustion standby state is entered.

  Thereafter, a second combustion command is output at time 70 seconds. As soon as combustion command output starts, the blower starts to operate, and at the same time as the blower starts operating, the blower operating time starts counting. Also in the case of the combustion command output from the time of 70 seconds, the pre-purge time is set to a long time (25 seconds) because the pre-purge is started from the state where the blower is not operating. In addition, a large amount of current flows at the start of fan operation, but a sufficient interval is opened from time 0 seconds when the previous large amount of current flow, so the average current value becomes high and the fan motor burns out. That does not happen. Although the output of the combustion command started at time 70 seconds, the combustion command is interrupted at time 80 seconds, so the combustion is stopped at time 80 seconds and post purge is performed. At time 80 seconds, the pre-purge was still in progress and combustion was not started, but the operation is continued without stopping the blower immediately. The blower operating time is 10 seconds from the time 70 seconds when the combustion command is output to the time 80 seconds, and is shorter than 45 seconds of the set time T, so the blower stop delay here is delayed for a long time.

  Since the long delay starting from time 70 seconds is 35 seconds obtained by subtracting 10 seconds of the blower operating time from 45 seconds of the set time T, the operation of the blower is continued as a blower stop delay until time 115 seconds. Become. Since the pre-purge was being performed at the time of 80 seconds, the opening degree of the damper was set to HI. However, since the pre-purge is completed and the post-purge is started from the time of 80 seconds, the damper opening degree is set to LO. The damper opening LO is the minimum opening in this case. When the damper device is closed while the blower is operating, the air sent from the blower stays in front of the damper device, so the air is compressed and the temperature rises. Therefore, the temperature of the blower also rises, and when the blower temperature rises, problems such as deterioration of the grease of the bearing portion may occur. Therefore, here, the damper device is kept open even during a long delay, so that the temperature of the blower can be kept low and the maintenance frequency of the blower can be reduced. In this case, the opening degree of the damper is set to the LO opening degree which is the minimum opening degree. Increasing the damper opening increases the amount of air sent to the combustion chamber and increases the amount of heat released from the combustion chamber, so reducing the damper opening to the minimum opening reduces the amount of air supplied to the combustion chamber. Reduce heat dissipation.

  Note that the operation of the blower for a long time delay after the combustion is stopped is for ensuring the operation interval of the blower, and does not require a long post-purge time for ventilating the combustion chamber. Since the post-purge is required only for 4 seconds as described above, the damper device may be opened only for 4 seconds after the combustion is stopped, and thereafter the damper device may be closed. If control is performed to close the damper device while the blower is operating due to a long delay, the amount of air sent from the blower to the combustion chamber is reduced, so that heat release from the combustion chamber can be reduced. In the case of a device such as a boiler that should have less heat dissipation, the efficiency on the device side can be improved by closing the damper device.

  The long delay is set to 115 seconds, but the combustion command output is started again at the time 100 seconds when the long delay is being implemented. Therefore, the blower operation as the blower stop delay ends at the time of 100 seconds, and subsequently, the pre-purge which is ventilation in the combustion preparation process is started. Since the damper opening of the pre-purge is HI, the damper opening is set to HI from time 100 seconds. In this case, since the blower continues to operate, a large amount of current does not flow through the blower motor at this stage. In addition, since the pre-purge is started while the blower is operating, a predetermined amount of air can be sent from the time when the pre-purge starts. Therefore, the pre-purge here is set to a short pre-purge (10 seconds).

  The combustion command started from time 100 seconds is also stopped at time 110 seconds. The blower operating time at time 110 seconds is 40 seconds from time 70 seconds to time 110 seconds, and the blower operating time in this case is also shorter than 45 seconds of the set time T. Therefore, the blower stop delay that starts at 40 seconds is also a long delay. The long delay here is 5 seconds obtained by subtracting 40 seconds of the blower operating time from 45 seconds of the set time T, and the suspension of the blower is delayed for 5 seconds from the time 110 seconds to the time 115 seconds. In addition, when the blower operating time is between 41 seconds and 45 seconds, subtracting the blower operating time from the set time T becomes smaller than 4 seconds. In this case, by setting 4 seconds as the blower stop delay time, the post-purge required time is not lowered. Thus, when the blower operation time is short at the time of combustion command stop, by delaying the blower stop, it is possible to prevent the operation interval of the blower from becoming shorter than a predetermined interval, the blower motor is overheated when the blower is operating, The blower motor will not burn out.

  In contrast, in the case of FIG. 4, the timing at which the combustion command is started and stopped is the same as in FIG. 3, but when the blower operating time is shorter than the set time T, a long blower stop delay is performed. Therefore, the interval at which a large amount of current flows through the blower motor is shortened. In the case of FIG. 4, the operation of the blower is started in response to the output of the combustion command, and when the combustion command is interrupted, the operation of the blower is stopped by performing a normal short post purge. Therefore, the operation of the blower is started at each of the time 70 seconds and the time 100 seconds, and a large amount of current flows through the blower motor each time a combustion command is output. When a large amount of current is passed through the blower motor many times at such short intervals, the blower motor overheats. If the degree of superheat of the blower motor becomes high, the blower motor will burn out.

  By carrying out the present invention, even if the start and stop of the combustion command are repeated at short intervals, the interval at which the operation of the blower is started does not become shorter than the predetermined time. For this reason, the blower motor is not overheated when a large amount of current supply is repeated. In addition, if the blower stop delay time is lengthened, there is a problem that the amount of electric consumption and heat dissipation increases, but the blower stop delay time only when the blower operation time is short and it is necessary to open the blower operation start interval. In addition, since the stoppage of the blower is delayed for a necessary time, it is possible to prevent an unnecessary increase in the amount of electricity consumed and the amount of heat released.

  In addition, when pre-purge is started while the blower is in operation, the time required for preparation until the start of combustion can be shortened by shortening the pre-purge time, and combustion follow-up can be improved. When a damper device is provided between the blower and the combustion chamber, when the blower is operated for a long time after the combustion is stopped, the damper device is controlled to close so that the air sent to the combustion chamber is reduced. Since the flow can be blocked, the amount of heat released from the combustion chamber can be reduced, and the efficiency can be increased in the case of equipment that uses heat, such as a boiler. Conversely, when the blower is operated for a long time after the combustion is stopped, if the damper device is opened, the temperature of the blower can be kept lower, and the grease of the blower bearing portion deteriorates. The occurrence of adverse effects can be suppressed. When opening the damper device, the damper opening is set to the minimum opening (low combustion opening) so that the cooling of the blower motor is not hindered and the amount of air sent to the combustion chamber is reduced. An increase in the amount of heat dissipation can be prevented.

Configuration diagram of a boiler system when the combustion apparatus of the present invention is installed in a boiler Flow chart of blower stop delay time setting program in one embodiment Time chart showing the operating status of the blower when implementing the present invention Time chart showing the operating status of the blower when the present invention is not implemented

Explanation of symbols

1 boiler
2 Steam header
3 Number control device
4 Combustion device
5 Blower
6 Fuel supply control device
7 Control device
8 Damper device

Claims (7)

  A combustion apparatus having a control device for controlling air supply by a blower and fuel supply by a fuel supply control device, and mixing the air from the blower and the fuel from the fuel supply control device and combusting in the combustion chamber. The device receives the combustion command and starts combustion by the combustion device, and stops the combustion upon receiving the stop of the combustion command. When stopping the combustion, the blower is delayed by a predetermined delay time from the stop of the fuel supply. In the combustion device that stops the operation, the control device measures the time from the start of the blower operation as the blower operation time, and receives the stop of the combustion command after the blower operation time exceeds the predetermined time T In such a case, the blower is stopped after operating the blower for a short time set for a relatively short time after stopping the fuel supply, and before the blower operating time exceeds the predetermined time T, When receiving the stop, the combustion apparatus and performs control for stopping the blower after running long delay component blower is set to a relatively long period of time.   2. The combustion apparatus according to claim 1, wherein the long time delay is determined based on a value obtained by subtracting a measured blower operating time from a predetermined time T. 3. Combustion device.   3. The combustion apparatus according to claim 2, wherein when the value of the long time delay obtained by subtracting the blower operating time from the predetermined time T is shorter than the value of the short time delay, the short time delay. A combustion apparatus that performs control to prevent a long delay from becoming shorter than a short delay by stopping the blower after the minute blower is operated.   In the combustion apparatus according to any one of claims 1 to 3, when a combustion command is received during a blower stop delay time after combustion stop, the blower stop delay process is terminated and pre-purge is started. A combustion apparatus that performs control to shorten the pre-purge time than usual when pre-purge is started in a state where the blower is operating.   5. The combustion apparatus according to claim 1, wherein the predetermined time T is set based on a blower operation start interval necessary for preventing the blower motor from being overheated. Combustion device.   6. A combustion apparatus according to claim 1, wherein a damper device is provided between the blower and the combustion chamber to block the flow of air, and when the air from the blower is sent to the combustion chamber, the damper device is opened to open the air. Since the combustion command was stopped before the blower operating time exceeded the predetermined time T, the control to operate the blower for a long delay set to a relatively long time after the combustion stopped was performed. When performing, the combustion apparatus characterized by performing control which closes the said damper during operation of the air blower after the combustion stop after progress for a short time delay.   6. A combustion apparatus according to claim 1, wherein a damper device is provided between the blower and the combustion chamber to block the flow of air, and when the air from the blower is sent to the combustion chamber, the damper device is opened to open the air. Since the combustion command was stopped before the blower operating time exceeded the predetermined time T, the control to operate the blower for a long delay set to a relatively long time after the combustion stopped was performed. When performing, the combustion apparatus characterized by opening the said damper with the minimum opening degree while the air blower is operating after the combustion is stopped.

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