WO2022181382A1

WO2022181382A1 - Boiler

Info

Publication number: WO2022181382A1
Application number: PCT/JP2022/005820
Authority: WO
Inventors: 公亮中村
Original assignee: 三浦工業株式会社
Priority date: 2021-02-24
Filing date: 2022-02-15
Publication date: 2022-09-01

Abstract

Provided is a boiler comprising: a ventilator that sends air into a boiler body via a ventilation path; a first communication path that allows communication at a first position in the ventilation path; a second communication path that allows communication at a second position in the ventilation path, the second position being located further downstream than the first position; a flow rate adjustment unit that adjusts the flow rate of fuel being supplied to the boiler body in accordance with a difference in pressure between the first communication path and the second communication path; and a pressure-difference-increasing control means that performs a pressure-difference-increasing control for increasing the difference in pressure between the first communication path and the second communication path during a transition from a first state to a second state in which the combustion amount is greater than in the first state.

Description

boiler

This application claims priority based on Japanese Patent Application No. 2021-027755 filed in Japan on February 24, 2021, the contents of which are incorporated herein.
The present invention relates to boilers.

　In recent years, interest in the environment has increased, and there is a need to prevent air pollution (low NOx) by regulating the concentration and amount of emissions of air pollutants such as nitrogen oxides (NOx). As one of the methods for realizing low NOx, it is conceivable to increase the oxygen concentration during combustion by increasing the ratio of combustion air to fuel. On the other hand, it is desirable to temporarily lower the oxygen concentration in order to improve stability and the like at the time of ignition or transition of the combustion state. In response to this background, in order to prevent the oxygen concentration from becoming excessive when the burner ignites, a bypass line is installed on the route of the fuel supply line. There is a boiler that performs control to increase the amount of fuel supplied compared to normal combustion by opening a bypass valve and allowing fuel to flow also from a bypass line (see, for example, Patent Document 1).

WO2016/157925

However, with conventional boilers, it is necessary to install a large-scale facility called a bypass line on the route of the fuel supply line, which increases costs. In addition, since it is necessary to provide a bypass orifice (pressure loss) in the fuel supply line, there is a risk of adverse effects, for example, when the fuel supply pressure is low.

The present invention has been devised in view of such circumstances, and its object is to provide a boiler that can be applied even when the fuel supply pressure is low while suppressing costs and appropriately adjusting the oxygen concentration at the time of ignition. It is to be.

In order to achieve the above object, a boiler according to one aspect of the present invention comprises: a blower for sending air into a boiler body through a blowing passage; a first communication passage communicating at a first position of the blowing passage; A second communication passage that communicates at a second position downstream of the first position of the passage, and supply to the boiler main body according to the differential pressure between the first communication passage and the second communication passage. and a flow rate adjusting portion that adjusts the flow rate of fuel; and differential pressure increase control means for performing differential pressure increase control to increase the differential pressure between.

According to the above configuration, by increasing the differential pressure between the first communication passage and the second communication passage when the first state is changed to the second state where the combustion amount is large, the fuel supply amount is can be increased. As a result, it is possible to appropriately adjust the oxygen concentration at the time of transition to the second state while suppressing costs. It can also be applied when the fuel supply pressure is low.

Preferably, an open valve is provided for releasing the pressure in the second communication passage to the outside, and the differential pressure increase control is performed by opening the open valve so as to open the first communication passage and the second communication passage. This control is to increase the differential pressure with the inside of the communication passage.

According to the above configuration, it is possible to increase the differential pressure with a simple structure and operation of providing an open valve and opening it.

Preferably, a pressure reducing section is provided on the downstream side of the open valve.

According to the above configuration, since the decompression unit is provided, it is possible to prevent the differential pressure from being excessively increased.

Preferably, the differential pressure increase control means starts the differential pressure increase control at a predetermined timing until transition processing for shifting to the second state is started.

According to the above configuration, the transition process can be started with the oxygen concentration adjusted.

Preferably, the first state is an ignition waiting state before starting combustion, and the second state is a state at the time of starting combustion.

According to the above configuration, stable ignition can be performed.

Preferably, the first state is a state of combustion with a smaller amount of combustion than the second state.

According to the above configuration, it is possible to shift to the second state in which the combustion amount is large while maintaining a stable state.

A boiler according to another aspect of the present invention comprises: a blower for sending air into a boiler body through an air passage; a first communication passage communicating at a first position of the air passage; A flow rate for adjusting the flow rate of the fuel supplied to the boiler body according to the pressure difference between the first communication path and the second communication path, which communicates at a second position on the downstream side and an adjusting unit for reducing the differential pressure between the first communication passage and the second communication passage when shifting from a second state in which the amount of combustion is greater than that of the first state to the first state. and differential pressure reduction control means for performing differential pressure reduction control.

According to the above configuration, when the second state is changed to the first state in which the combustion amount is small, the differential pressure between the first communication passage and the second communication passage is reduced, thereby reducing the amount of fuel supplied. can be reduced. As a result, it is possible to appropriately adjust the oxygen concentration at the time of transition to the first state while suppressing costs. It can also be applied when the fuel supply pressure is low.

It is a figure which shows typically a schematic structure of a boiler. It is a flow chart which shows an example of transfer processing of a boiler. (a) is a flowchart for explaining an example of a main try transition process, and (b) is a flowchart for explaining an example of a high combustion transition process. It is a figure which shows typically a schematic structure of a boiler.

The boiler according to the present disclosure will be explained with reference to the drawings. The present invention is not limited to these examples, but is indicated by the scope of the claims, and is intended to include all modifications within the meaning and scope of equivalents to the scope of the claims. be.

[First embodiment]
<Overview of configuration>
A first embodiment of the present invention will be described below with reference to the drawings. First, referring to FIG. 1, a schematic configuration of a boiler according to the present embodiment will be described.

The boiler 1, as shown in FIG. , a fuel supply line 5 for supplying fuel to the boiler body 2 , a water supply line (not shown) for supplying water to the boiler body 2 , and a control section 6 for controlling the operation and operation of the boiler 1 . In addition, although an example in which the fuel is gas will be described, the fuel is not limited to gas such as gas, and may be liquid such as oil.

The fuel supply line 5 is connected to the air supply path 30. Fuel supplied from the fuel supply line 5 is mixed with air blown from the blower 3 in the air supply path 30 and supplied to the burner 20 in the boiler main body 2 .

Air supplied from the blower 3 is supplied as combustion air to the burner 20 in the boiler body 2 via the air supply path 30 . The flow rate of the combustion air is adjusted by providing a damper 7 in the air supply path 30 and adjusting the position (opening degree) of the damper 7, or alternatively or in addition to this, by adjusting the speed of the blower 3 using an inverter. This is done by changing the rotation speed of the fan.

The fuel supply line 5 is provided with an on-off valve 11 (solenoid valve) for opening and closing the passage, and a fuel supply amount adjustment valve 12 . The fuel supply amount adjustment valve 12 functions as a fuel supply amount adjustment valve (also referred to as a flow rate adjustment section) capable of adjusting the flow rate of the fuel supplied to the boiler main body 2, and also has a cutoff function. The fuel supply amount adjustment valve 12 is arranged downstream of the on-off valve 11 . In this embodiment, the fuel supply amount control valve 12 is a governor.

In the present embodiment, the air supply path 30 is provided with a combustion air pressure reducing member 8 such as a punching metal downstream of the damper 7 . The air supply passage 30 communicates with the fuel supply amount control valve 12 provided on the fuel supply line 5 via the first communication passage 14 upstream of the combustion air pressure reducing member 8 . Further, the air supply passage 30 communicates with the fuel supply amount adjustment valve 12 provided on the fuel supply line 5 through the second communication passage 15 downstream of the combustion air pressure reducing member 8 .

The governor (fuel supply amount adjusting valve) 12 adjusts the pressure difference between the first communication passage 14 and the second communication passage 15 (basically, the pressure difference before and after the combustion air pressure reducing member 8 in the air supply passage 30). is the same as ). The governor is a pressure equalizing valve whose opening degree is mechanically adjusted so that the differential pressure to be introduced and the pressure of the fuel to be supplied (pressure on the secondary side) are equalized. A branch path 13 is provided from the downstream flow path of the governor. The governor adjusts the degree of opening so that the pressure on the secondary side obtained from the branch passage 13 corresponds to the differential pressure across the combustion air pressure reducing member 8 in the air supply passage 30 to which it is introduced. can be done. As a result, if the differential pressure across the combustion air pressure reducing member 8 increases, the flow rate of the fuel supplied to the boiler body 2 increases, and if the differential pressure across the combustion air pressure reducing member 8 decreases, the boiler body 2 is reduced.

A branch path is provided in the middle of the second communication path 15 . An open valve (solenoid valve) 16 is provided in the branch path. By opening the release valve 16, the second communication path 15 is opened to the atmosphere, and air escapes from the second communication path 15. Therefore, the pressure in the second communication path 15 decreases, and the first The differential pressure between the communication passage 14 and the second communication passage 15 increases more than the actual differential pressure across the combustion air pressure reducing member 8 in the air supply passage 30 . A pressure reducing section (orifice) 17 is provided downstream of the open valve 16 . The decompression part 17 prevents the air from being released excessively when the release valve 16 is opened.

When shifting from the first state to the second state in which the amount of combustion is greater than that of the first state, the amount of fuel supply is gradually increased in accordance with the differential pressure across the combustion air pressure reducing member 8. Therefore, the amount of combustion air increases with respect to the actual amount of fuel supplied, and the oxygen concentration tends to be high and excessive. On the other hand, in the present embodiment, when the first state is changed to the second state in which the amount of combustion is larger than that of the first state, the open valve 16 is opened so that and the pressure difference between the inside of the second communication passage. Thus, the differential pressure can be increased by a simple structure and operation of providing the open valve 16 in the second communication passage 15 and opening it. As the differential pressure increases, the degree of opening of the fuel supply amount control valve 12 increases, the amount of fuel supplied increases, and the oxygen concentration of the combustion air can be relatively reduced.

In the present embodiment, as an example of shifting from the first state to the second state in which the amount of combustion is greater than that of the first state, (1) the first state is an ignition waiting state before the start of combustion; , an example in which the second state is the state at the start of combustion (for example, main try, low combustion state, etc.) (hereinafter also referred to as "at the start of combustion"), and (2) the first state is the second state An example of a state in which the combustion amount is smaller than the state (hereinafter also referred to as "high combustion transition time"), that is, an example in which the first state is a low combustion state and the second state is a high combustion state and

At the start of combustion when the release valve 16 is not provided, as described above, the oxygen concentration tends to be high and excessive, which is likely to cause multi-stage ignition and ignition noise. Therefore, at the start of combustion in the present embodiment, by opening the open valve 16 and increasing the differential pressure between the first communication passage and the second communication passage, the amount of fuel supplied is increased for combustion. Stable ignition can be achieved by relatively lowering the oxygen concentration of the operating air. After the ignition is completed, the open valve 16 is closed, and fuel is supplied according to the actual differential pressure across the combustion air pressure reducing member 8 in the air supply passage 30. As a result, the oxygen concentration of the combustion air becomes high during combustion.

Also, even during combustion, if the high combustion transition is performed while the oxygen concentration is relatively high, poor combustion is likely to occur because the flow rate of air increases before the fuel. Therefore, at the time of transition to high combustion, by opening the release valve 16 and increasing the differential pressure between the first and second communication passages, the fuel supply amount is increased and the combustion air is supplied. By relatively lowering the oxygen concentration, it is possible to achieve a stable high combustion transition. After the high combustion transition is completed, the open valve 16 is closed, and fuel is supplied according to the actual differential pressure across the combustion air pressure reducing member 8 in the air supply passage 30. , the oxygen concentration of the combustion air becomes high.

The timing of starting the differential pressure increase control, that is, the timing of switching the open valve 16 to the open state, is set to a predetermined timing until the transition processing for shifting to the second state is started. For example, the timing of switching the open valve 16 to the open state at the start of combustion may be the timing until the ignition processing of the burner 20 is started. The timing may be a predetermined time before starting the ignition process, the timing during the purge, or the timing when the purge is completed. The timing of switching the open valve 16 to the open state at the time of transition to the high combustion state may be the timing until the transition processing to the high combustion state is started. The timing may be a predetermined time before the state transition processing is started. It should be noted that the predetermined time may be longer than the time required from the start of the control for switching the open valve 16 to the open state until it is completely opened.

On the other hand, the timing at which the differential pressure increase control is terminated, that is, the timing at which the open valve 16 is switched to the closed state is the predetermined timing during the transition processing, the timing at which the transition processing is completed, or the like, when the combustion in the second state is stabilized. Any timing is acceptable. For example, the timing at which the open valve 16 is switched to the closed state at the start of combustion may be the timing at which it is determined that the burner 20 is ignited, or the timing at which the main try ends. Further, the timing of switching the open valve 16 to the closed state at the time of transition to the high combustion state is, for example, the timing when a predetermined time has passed since the transition processing to the high combustion state was started, or the timing when the transition processing to the high combustion state has been completed. It may be timing or the like.

By controlling the open valve 16 to the closed state, the second communication path 15 is not open to the atmosphere, and air will not escape from the second communication path 15 . Therefore, the differential pressure between the first communication passage and the second communication passage becomes the differential pressure (original differential pressure) across the combustion air pressure reducing member 8 in the air supply passage 30 . As a result, the opening degree of the fuel supply amount adjusting valve 12 is controlled to decrease according to the differential pressure across the combustion air pressure reducing member 8 in the air supply passage 30, the amount of fuel supplied decreases, and the combustion air relative increase in oxygen concentration (for example, it becomes the oxygen concentration designed according to the combustion state).

The control unit 6 controls the blower 3 and the damper 7, which are the air supply units, so that the flow rate of the supplied combustion air becomes the flow rate corresponding to the set combustion amount, thereby adjusting the supply flow rate of the combustion air. adjust. Further, the control unit 6 controls the open valve 16 according to the state of the boiler 1 (for example, combustion state). Further, the control unit 6 can function as differential pressure increase control means for performing differential pressure increase control and differential pressure decrease control means for performing differential pressure decrease control.

<About migration process>
FIG. 2 is a flow chart showing an example of a boiler transfer process. These transition processes are executed by the control unit 6 . FIG. 2(a) is a flowchart for explaining an example of a main try transition process at the start of combustion.

　In step S01, it is determined whether or not the purge performed before the start of combustion has been completed. If it is determined that the purge has been completed, the process proceeds to step S02, and if it is determined that the purge has not been completed, the process returns to step S01.

In step S02, the open valve 16 is controlled to open, and the process proceeds to step S03. As a result, the pressure in the second communication passage 15 decreases, and the differential pressure between the first and second communication passages becomes equal to the original differential pressure in the air supply passage 30 before and after the combustion air pressure reducing member 8 . increases more than As the differential pressure increases, the opening degree of the fuel supply amount control valve 12 is controlled to increase, the amount of fuel supplied increases, and the oxygen concentration of the combustion air relatively decreases.

In step S03, transition processing is performed to transition from the ignition waiting state to the main try. In the transition processing for transitioning to the main try, processing for setting the flow rate of the combustion air to the flow rate for the main try, processing for igniting the burner 20, processing for determining whether or not the ignition has occurred, and the like are performed. will be

In step S04, it is determined whether or not the ignition of the burner 20 has been completed and the main try has ended. If it is determined that the main try has ended, the process proceeds to step S05, and if it is determined that the main try has not ended, the process returns to step S04.

In step S05, the open valve 16 is controlled to be closed, and the main try transition processing ends. As a result, the differential pressure between the first communication passage and the second communication passage becomes the differential pressure (original differential pressure) across the combustion air pressure reducing member 8 in the air supply passage 30 . As a result, compared to when the open valve 16 is open, control is performed so that the degree of opening of the fuel supply amount adjusting valve 12 becomes smaller according to the differential pressure across the combustion air pressure reducing member 8 in the air supply passage 30. As a result, the amount of fuel supplied decreases, and the oxygen concentration of the combustion air relatively increases (for example, the oxygen concentration is designed according to the combustion state).

FIG. 2(b) is a flow chart for explaining an example of transition processing during transition to high combustion. In step S11, it is determined whether or not it is time to transition to high combustion. If it is determined that it is time to transition to high combustion, the process proceeds to step S12, and if it is determined that it is not time to transition to high combustion, the process returns to step S11.

In step S12, the open valve 16 is controlled to open, and the process proceeds to step S13. As a result, the pressure in the second communication passage 15 decreases, and the differential pressure between the first and second communication passages becomes equal to the original differential pressure in the air supply passage 30 before and after the combustion air pressure reducing member 8 . increases more than As the differential pressure increases, the opening degree of the fuel supply amount control valve 12 is controlled to increase, the amount of fuel supplied increases, and the oxygen concentration of the combustion air relatively decreases.

In step S13, transition processing for transitioning from the low combustion state to the high combustion state is performed. In the transition processing for transitioning to the high combustion state, processing for adjusting the flow rate of the combustion air to the flow rate for the high combustion state is performed.

In step S14, it is determined whether or not the transition to the high combustion state has ended. If it is determined that the transition to the high combustion state has ended, the process proceeds to step S15, and if it is determined that the transition to the high combustion state has not ended, the process returns to step S14.

In step S15, the open valve 16 is controlled to be closed, and the transition processing to the high combustion state ends. As a result, the differential pressure between the first communication passage and the second communication passage becomes the differential pressure (original differential pressure) across the combustion air pressure reducing member 8 in the air supply passage 30 . As a result, compared to when the open valve 16 is open, control is performed so that the degree of opening of the fuel supply amount adjusting valve 12 becomes smaller according to the differential pressure across the combustion air pressure reducing member 8 in the air supply passage 30. As a result, the amount of fuel supplied decreases, and the oxygen concentration of the combustion air relatively increases (for example, the oxygen concentration is designed according to the combustion state).

In the above embodiment, as shown in steps S01 to S05 in FIG. 2A and steps S11 to S15 in FIG. When shifting to state 2, differential pressure increase control is performed to increase the differential pressure between the first communication passage 14 and the second communication passage 15 . Therefore, when shifting from the first state to the second state in which the amount of combustion is large, the amount of fuel supplied can be increased by increasing the differential pressure between the first communication passage and the second communication passage. can be done. As a result, it is possible to appropriately adjust the oxygen concentration at the time of transition to the second state while suppressing costs. It can also be applied when the fuel supply pressure is low.

In addition, since the branch passage provided in the middle of the second communication passage 15 is provided with the open valve 16, the differential pressure can be increased by a simple structure and operation of opening the open valve 16 by providing the open valve 16. Further, since the orifice 17 is provided as a pressure reducing portion downstream of the open valve 16, it is possible to prevent the differential pressure from being excessively increased.

Further, the control for switching the open valve 16 to the open state is performed by the time the main try transition process and the high combustion transition process are started, respectively, as shown in step S02 of FIG. 2(a) and step S12 of FIG. 2(b). be started. Therefore, the transition process can be started with the oxygen concentration adjusted.

Also, as shown in FIG. 2(a), stable ignition can be achieved when combustion is started from an ignition waiting state before combustion is started. Furthermore, as shown in FIG. 2(b), when the low combustion state transitions to the high combustion state, it is possible to shift to the high combustion state in which the combustion amount is large while maintaining a stable state.

[Second embodiment]
A second embodiment of the present invention will now be described with reference to FIG. A description of the contents common to the first embodiment of the present invention will be omitted, and different points will be described. In the boiler according to the first embodiment, when shifting from the first state to the second state in which the amount of combustion is greater than that of the first state, the inside of the first communication passage and the inside of the second communication passage Although an example of performing differential pressure increase control to increase the differential pressure has been shown, in the boiler according to the second embodiment, the second state in which the combustion amount is larger than the first state is shifted to the first state. A different example is shown in that differential pressure reduction control is performed to reduce the differential pressure between the first communication passage and the second communication passage.

In the boiler according to the first embodiment, as shown in FIG. 1, the branch path was provided in the middle of the second communication path 15, but in the boiler according to the second embodiment, as shown in FIG. , a branch path is provided in the middle of the first communication path 14 . An open valve (solenoid valve) 18 is provided in the branch path. By opening the open valve 18, the first communication path 14 is opened to the atmosphere, and air is released from the first communication path 14. Therefore, the pressure in the first communication path 15 decreases, and the air is supplied. The differential pressure across the combustion air pressure reducing member 8 in passage 30 is reduced. A pressure reducing section (orifice) 19 is provided downstream of the open valve 18 . The decompression unit 19 prevents excessive air leakage when the release valve 18 is opened.

When shifting from the second state in which the combustion amount is larger than that in the first state to the first state, the amount of fuel supply is reduced according to the differential pressure across the combustion air pressure reducing member 8. , the amount of combustion air is small relative to the actual amount of fuel supplied, and the oxygen concentration tends to be too low. On the other hand, in the present embodiment, the second state (high combustion state) to the first state (hereinafter also referred to as "during transition to low combustion"), the release valve 18 is opened to reduce the pressure difference between the first communication passage and the second communication passage. Decrease. In this way, the differential pressure can be reduced by the simple structure and operation of providing the open valve 18 in the first communication passage 14 and opening it. As the differential pressure decreases, the degree of opening of the fuel supply amount control valve 12 decreases, the amount of fuel supplied decreases, and the oxygen concentration of the combustion air can be relatively increased. As a result, low combustion transition can be performed while maintaining a stable state. After the low combustion transition is completed, the open valve 18 is closed, and fuel is supplied according to the actual differential pressure across the combustion air pressure reducing member 8 in the air supply passage 30. .

The timing of starting the differential pressure reduction control, that is, the timing of switching the open valve 18 to the open state, is set to a predetermined timing until the transition processing for shifting to the first state is started. For example, the timing at which the open valve 18 is switched to the open state at the time of transition to the low combustion state may be the timing until the transition processing to the low combustion state is started. The timing may be a predetermined time before the start of the transition process to the low combustion state. It should be noted that the predetermined time may be longer than the time required from the start of the control for switching the open valve 18 to the open state until it is completely opened.

On the other hand, the timing at which the differential pressure reduction control is terminated, that is, the timing at which the open valve 18 is switched to the closed state is the predetermined timing during the transition processing, the timing at which the transition processing is completed, or the like, when the combustion in the first state is stabilized. Any timing is acceptable. For example, the timing at which the open valve 18 is switched to the closed state at the time of the transition to the low combustion state is the timing after a predetermined time has elapsed since the transition processing to the low combustion state was started, the timing at which the transition processing to the low combustion state has been completed, or the like. may be

By controlling the open valve 18 to the closed state, the first communication path 14 is not open to the atmosphere, and air will not escape from the first communication path 14 . Therefore, the differential pressure between the first communication passage and the second communication passage becomes the differential pressure (original differential pressure) across the combustion air pressure reducing member 8 in the air supply passage 30 . As a result, the opening degree of the fuel supply amount adjusting valve 12 is controlled to increase according to the differential pressure across the combustion air pressure reducing member 8 in the air supply passage 30, the amount of fuel supplied increases, and the combustion air increases. The oxygen concentration of is relatively decreased (for example, it becomes the oxygen concentration designed according to the combustion state).

In the above embodiment, the differential pressure reduction control reduces the differential pressure between the first communication passage 14 and the second communication passage 15 when shifting from the second state to the first state where the combustion amount is small. I do. For this reason, when shifting from the second state to the first state in which the combustion amount is small, the amount of fuel supplied is reduced by reducing the differential pressure between the first communication passage and the second communication passage. can be done. As a result, it is possible to appropriately adjust the oxygen concentration at the time of transition to the first state while suppressing costs. It can also be applied when the fuel supply pressure is low.

The present invention is not limited to the above embodiments, and various modifications and applications are possible. Modifications of the above embodiments applicable to the present invention will be described below.

Although the above-mentioned first embodiment and second embodiment have been described separately, the differential pressure increase control described in the first embodiment and the second embodiment are not limited to this. You may make it perform both the differential pressure reduction control demonstrated by the form. That is, when shifting from the first state to the second state where the combustion amount is large, the differential pressure increase control is performed, and the second state where the combustion amount is larger than the first state is shifted to the first state. The boiler may be a boiler that performs differential pressure reduction control.

In the above embodiment, an example in which an orifice is provided downstream of the open valve 16 has been described. . Further, if the opening of the open valve 16 is small and there is no risk of excessive air leakage, the downstream pressure reduction section may not be provided.

In the above embodiment, a punching metal is used as the combustion air decompression member 8, but it is not limited to this, and any member that can decompress the air and has a proportional air flow rate and pressure loss may be used.

An example of controlling the boiler 1 in the above embodiment in two stages, a low combustion stage and a high combustion stage, has been described. However, the present invention is not limited to this, and may be controlled in three stages of a low combustion stage, an intermediate combustion stage, and a high combustion stage, or may be proportionally controlled so as to achieve an arbitrary load factor.

Although the boiler 1 in the above embodiment is controlled using a governor, the fuel supply amount adjustment valve 12 can also be electronically controlled by the control unit 6. In the case of electronic control, an air amount detection unit that detects a differential pressure across the combustion air pressure reducing member 8 and outputs differential pressure information is electrically connected to the control unit 6 to detect the air amount. The differential pressure information from the unit is input to the control unit 6 . The control unit 6 is realized by a computer including a memory, a timer, and an arithmetic processing unit inside, and operates the fuel supply amount adjustment valve 12 according to the stage of combustion based on differential pressure information input from the air amount detection unit. adjust the opening of the The control unit 6 transmits an opening degree specifying signal for specifying the opening degree to the fuel supply amount adjusting valve 12 based on the opening degree adjustment information stored in advance in the memory. As a result, the fuel supply amount adjustment valve 12 is controlled to have an opening degree corresponding to the differential pressure across the combustion air pressure reducing member 8 , thereby adjusting the flow rate of the fuel supplied to the boiler main body 2 . The opening degree adjustment information may be, for example, a table that can specify the degree of opening of the fuel supply amount adjustment valve 12 according to the pressure difference, or the opening degree of the fuel supply amount adjustment valve 12 according to the pressure difference. It may be an arithmetic expression for specifying the degree. In this case, for example, when the first state is changed to the second state where the combustion amount is large, the control unit 6 sets the differential pressure specified from the differential pressure information input from the air amount detection unit to a predetermined value. The fuel supply amount adjusting valve 12 is controlled to the degree of opening corresponding to the increased value, and when shifting from the second state in which the combustion amount is larger than the first state to the first state, the air amount detection unit The fuel supply amount adjusting valve 12 may be controlled to an opening degree corresponding to a value obtained by subtracting a predetermined value from the differential pressure specified from the input differential pressure information.

The embodiments disclosed this time should be considered illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and range of equivalents of the scope of the claims.

REFERENCE SIGNS LIST 1 boiler 2 boiler main body 3 fan 4 exhaust passage 5 fuel supply line 6 control unit 7 damper 8 combustion air pressure reducing member 11 opening/closing valve 12 fuel supply amount adjusting valve 13 branch passage 14 first communication passage 15 second communication passage 16 opening valve 17 decompression section 18 release valve 19 decompression section 20 burner 30 air supply path

Claims

an air blower for sending air into the boiler body through the air passage;
a first communication passage that communicates at a first position of the air passage;
a second communication path communicating at a second position on the downstream side of the first position of the air passage;
a flow rate adjustment unit that adjusts the flow rate of the fuel supplied to the boiler main body according to the differential pressure between the first communication path and the second communication path;
Differential pressure increase control for increasing the differential pressure between the first communication passage and the second communication passage when shifting from the first state to a second state in which the amount of combustion is greater than that of the first state. and differential pressure increase control means for performing
A release valve for releasing the pressure of the second communication passage to the outside,
2. The boiler according to claim 1, wherein said differential pressure increase control is control to increase the differential pressure between said first communication passage and said second communication passage by opening said open valve.
The boiler according to claim 2, wherein a pressure reducing section is provided on the downstream side of the open valve.
4. The differential pressure increase control means according to any one of claims 1 to 3, wherein said differential pressure increase control means starts said differential pressure increase control at a predetermined timing before starting transition processing for shifting to said second state. boiler.
The first state is an ignition waiting state before combustion starts,
The boiler according to any one of claims 1 to 4, wherein said second state is a state at the start of combustion.
The boiler according to any one of claims 1 to 4, wherein said first state is a state of combustion with a smaller combustion amount than said second state.
an air blower for sending air into the boiler body through the air passage;
a first communication passage that communicates at a first position of the air passage;
a second communication path communicating at a second position on the downstream side of the first position of the air passage;
a flow rate adjustment unit that adjusts the flow rate of the fuel supplied to the boiler main body according to the differential pressure between the first communication path and the second communication path;
Differential pressure reduction control for reducing the differential pressure between the first communication passage and the second communication passage when shifting from a second state in which the amount of combustion is greater than that of the first state to the first state. differential pressure reduction control means for performing