JP2019086281A - boiler - Google Patents

Abstract

To provide a boiler capable of suitably setting an ignition operation possible time without pre-purging, according to an amount of valve-over leakage.SOLUTION: A boiler 1 comprises: a burner 15; a fuel supply line 50 for supplying fuel gas to the burner 15; a first cutoff valve 51 and a second cutoff valve 52 arranged in the fuel supply line 50; a pressure detection unit 53 arranged between the first cutoff valve 51 and the second cutoff valve 52; and a combustion control unit 81 configured to, when the pressure detection unit 53 detects predetermined pressure drop in a state where the first cutoff valve 51 and the second cutoff valve 52 are closed, calculate a standby time of starting combustion without pre-purging, based on a time after the first cutoff valve 51 and the second cutoff valve 52 are closed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a boiler.

  Conventionally, in a boiler that burns fuel gas to generate steam, a double shut-off valve is disposed in a fuel supply line that supplies fuel gas, and is shut off during combustion stoppage of the boiler (for example, after post-purge) It is performed to determine the presence or absence of the leak over the valve of the fuel gas from the cutoff valve by determining the presence or absence of the pressure drop between the cutoff valves (see, for example, Patent Document 1).

JP, 2016-6357, A

In the boiler proposed in Patent Document 1, the first set flow rate and the second set flow rate smaller than the first set flow rate are set as the leak amount of the over-valve leak, and when the leak exceeding the first set flow rate is detected Transition to the ignition operation without performing pre-purge during the first safety standby time, when the transition to the subsequent ignition operation is disabled, and a leak equal to or less than the first set flow rate and exceeding the second set flow rate is detected. To allow. Further, when a leak exceeding the second set flow rate is not detected, transition to the ignition operation is permitted without performing pre-purge for a second safety standby time longer than the first safety standby time.
Thus, the ignition operation without pre-purge is realized while securing the safety, and the load followability of the boiler is improved.

  According to the technique proposed in Patent Document 1, the pre-purge during the first safety standby time preset according to the leak amount and the pre-purge during the second safety standby time can be omitted, but more according to the leak amount The load followability of the boiler can be further improved by setting the ignition operation possible time without a suitable pre-purge.

  Therefore, an object of the present invention is to provide a boiler capable of setting an ignition operation possible time without a suitable pre-purge according to the leak amount of the over-valve leak.

  The present invention relates to a burner, a fuel supply line for supplying a fuel gas to the burner, a first shutoff valve disposed on the fuel supply line, a second shutoff valve, and the first shutoff valve and the second shutoff valve. And the first shutoff valve is detected by the pressure detection unit in a state in which the first shutoff valve and the second shutoff valve are closed. The present invention relates to a boiler including a combustion control unit that calculates a standby time for starting combustion without performing pre-purge based on the time after the valve and the second shutoff valve are closed.

  Further, it is preferable that, when the pressure detection unit detects a predetermined pressure drop, the combustion control unit performs an ignition operation after performing a pre-purge when an ignition request is issued after the elapse of the standby time.

  In the case where the time from when the combustion control unit closes the first shutoff valve and the second shutoff valve to when the pressure detection unit detects a predetermined pressure drop is equal to or less than a first set time Preferably, the transition to the ignition operation is disabled.

  Moreover, it is preferable that the said pressure detection part is comprised with the pressure switch which operate | moves when it becomes less than setting pressure, and is further provided with the operation confirmation part which confirms operation | movement of the said pressure switch.

  Further, the boiler further includes a gas release line connected between the first shutoff valve and the second shutoff valve in the fuel supply line, and a gas relief valve disposed in the gas escape line, The first shutoff valve includes a first close confirmation switch for confirming the closed state of the first shutoff valve, and the second shutoff valve is a second close confirmation switch for confirming the closed state of the second shutoff valve. Preferably,

  In the boiler, an operation confirmation unit that confirms operations of the first close confirmation switch and the second close confirmation switch, and the first close when the first shutoff valve and the second shutoff valve are closed. A gas leak has occurred when the closing duration time of the confirmation switch and the second closing confirmation switch is counted, and the counting of the closing duration time of the first closing confirmation switch or the second closing confirmation switch is stopped. It is preferable to further include a gas leak judgment unit to judge.

  Further, it is preferable that the pressure detection unit is configured by a differential pressure switch that operates when a predetermined differential pressure is generated between the primary side and the secondary side of the first shutoff valve.

  Further, the boiler opens the second shutoff valve in a state in which the first shutoff valve is closed, when there is a combustion start request in a state in which the first shutoff valve and the second shutoff valve are closed. It is preferable to further include a gas leak determination unit that determines that the first shutoff valve is leaking when the operation of the differential pressure switch is not detected for a predetermined time after the second shutoff valve is opened. .

  Further, the first shutoff valve comprises a first close confirmation switch for confirming the closed state of the first shutoff valve, and the gas leak judgment unit is in the closed state of the first close confirmation switch, and It is preferable to determine that the first shutoff valve is leaking when the differential pressure switch does not operate.

  According to the boiler of the present invention, it is possible to set the ignition operation possible time without the suitable pre-purge according to the leak amount of the over-valve leak.

It is a figure showing typically the boiler concerning a 1st embodiment of the present invention. It is a block diagram showing composition of a control part of a 1st embodiment. It is a figure showing typically the boiler concerning a 2nd embodiment of the present invention. It is a block diagram showing composition of a control part of a 2nd embodiment. It is a figure showing typically the boiler concerning a 3rd embodiment of the present invention. It is a block diagram which shows the structure of the control part of 3rd Embodiment.

Hereinafter, preferred embodiments of the boiler of the present invention will be described with reference to the drawings. The boiler 1 of the present embodiment is a steam boiler that heats water to generate steam, and supplies the steam to a load device (not shown).
The boiler 1 according to the present embodiment includes a can 10, a blower 20 for feeding combustion air to the can 10, an air supply duct 30 for connecting the can 10 and the blower 20 and circulating the combustion air, and a can An exhaust pipe 80 through which the combustion gas (exhaust gas) discharged from 10 flows, a fuel supply line 50 for supplying a fuel gas to the can 10, a water supply line 60 for supplying water to the can 10, a fuel gas and combustion And a control device 70 for controlling the supply amount of air and the like.

  The can 10 includes a boiler housing 11, a plurality of water tubes 12, a lower header 13, an upper header 14, and a burner 15.

  The boiler housing 11 constitutes the outer shape of the can 10. An air supply port 16 is formed on one side surface of the boiler housing 11, and an exhaust port 17 is formed on a side surface facing the side surface on which the air supply port 16 is formed.

  The plurality of water tubes 12 extend in the vertical direction inside the boiler housing 11 and are arranged at predetermined intervals in the longitudinal direction and width direction of the boiler housing 11.

  The lower header 13 is disposed below the boiler housing 11. Lower ends of the plurality of water tubes 12 are connected to the lower header 13. The upper header 14 is disposed on the top of the boiler housing 11. Upper ends of the plurality of water tubes 12 are connected to the upper header 14.

  The burner 15 is disposed at the air supply port 16. The mixture of the fuel gas and the combustion air is burned by the burner 15, and the water in the water pipe 12 is heated to generate steam.

  The blower 20 includes a blower main body 21 having a fan and a motor for rotating the fan, and an inverter 22 for increasing and decreasing the rotational speed of the fan (motor). The blower 20 feeds combustion air to the can 10 by the fan rotating at a predetermined rotational speed according to the frequency input to the inverter 22.

  In the present embodiment, the flow rate of the combustion air is set according to the required load required from the load device (not shown). The blower 20 is controlled by the control device 70 via the inverter 22 so as to be the set flow rate of fuel air.

The air supply duct 30 supplies the can 10 with combustion air to be mixed with the fuel gas. The upstream end of the air supply duct 30 is connected to the blower 20, and the downstream end is connected to the air supply port 16. The air supply duct 30 supplies combustion air fed from the blower 20 to the can 10.
A damper 31 is disposed in the air supply duct 30.

  The damper 31 rotates 90 degrees from the closed state in which the flow path of the combustion air in the air supply duct 30 is closed and the closed state, and the damper 31 opens the flow path of the combustion air in the air supply duct 30. It is rotatably arranged between the states.

  The exhaust pipe 80 has a proximal end side connected to the exhaust port 17 and is formed in a tubular shape. The combustion gas (exhaust gas) generated in the can 10 is discharged to the outside of the can 10 through the exhaust stack 80.

The fuel supply line 50 is connected on the upstream side to a fuel supply source (not shown) and connected on the downstream side to the air supply duct 30. The downstream end of the fuel supply line 50 is connected downstream of the position where the damper 31 in the air supply duct 30 is disposed.
In the fuel supply line 50, a first shutoff valve 51, a second shutoff valve 52, a pressure switch 53 as a pressure detection unit, an orifice 54, and a nozzle 55 are disposed.

  The first shutoff valve 51 is configured by an on-off valve such as a solenoid valve. The first shutoff valve 51 opens or closes the fuel supply line 50 to supply and stop the fuel gas.

  The second shutoff valve 52 is disposed downstream of the first shutoff valve 51. The second shutoff valve 52 opens and closes the fuel supply line 50 to supply and stop the fuel gas, and also functions as a governor that adjusts the pressure (flow rate) of the fuel gas flowing through the fuel supply line 50.

  The pressure switch 53 is disposed between the first shutoff valve 51 and the second shutoff valve 52 and detects the pressure of the fuel gas flowing through the fuel supply line 50. In the present embodiment, the pressure switch 53 is turned off when the pressure of the fuel gas between the first shutoff valve 51 and the second shutoff valve 52 in the fuel supply line 50 falls below the pressure set in advance. It consists of switches.

  The orifice 54 functions as a fuel gas depressurizing member that depressurizes the fuel gas flowing through the fuel supply line 50. The orifice 54 is disposed downstream of the second shutoff valve 52 in the fuel supply line 50.

  The nozzle 55 is disposed at the downstream end of the fuel supply line 50 and ejects the fuel gas to the air supply duct 30. The fuel gas ejected from the nozzle 55 is mixed with the combustion air sent by the blower 20, and the mixed mixture is burned by the burner 15.

  The water supply line 60 supplies water to the can 10. The upstream side of the water supply line 60 is connected to a water supply source (not shown), and the downstream side is connected to the lower header 13. A water supply valve 61 is disposed in the water supply line 60.

Next, the control device 70 will be described. The control device 70 includes a control unit 71 that controls the combustion state of the boiler 1 and a storage unit 72 in which various types of information are stored.
The control device 70 is electrically connected to each of the above-described sensors, and controls the first shut-off valve 51, the second shut-off valve 52, the blower 20, etc. based on the signals from these sensors and the required load from the load device. And control the combustion state of the boiler 1. Further, the control device 70 adjusts the opening / closing or opening degree of the water supply valve 61 according to the combustion state of the boiler 1 to control the water level of the water pipe 12.

Further, the control device 70 determines whether or not the pressure between the first shut-off valve 51 and the second shut-off valve 52 is shut down while the boiler 1 is in the combustion stop (for example, after the post-purge). Also, over-valve leak determination is performed to determine the presence or absence of over-valve leak of fuel gas from the shutoff valve.
Here, in the present embodiment, when a drop in a predetermined amount of pressure between the first shut-off valve 51 and the second shut-off valve 52 is detected in the over-valve leak determination, the drop of the pressure is detected. The load followability of the boiler 1 is further improved by setting the ignition operation possible time without pre-purge at the start of the subsequent combustion based on the elapsed time.

  The control unit 71 includes a combustion control unit 81 and an operation check unit 82 in order to realize such a valve over leak determination function.

First, the operation of the combustion control unit 81 in the case of performing the over-valve leak determination will be described.
In a state where the first shutoff valve 51 and the second shutoff valve 52 are closed and the combustion of the boiler 1 is stopped, the combustion control unit 81 performs the first shutoff when a predetermined pressure drop is detected by the pressure switch 53. Based on the time after closing the valve 51 and the second shutoff valve 52, the standby time for starting the combustion without performing the pre-purge is calculated.

That is, when the combustion of the boiler 1 is stopped and the first shutoff valve 51 and the second shutoff valve 52 are closed, the pressure between the first shutoff valve 51 and the second shutoff valve 52 is during combustion of the boiler 1 (That is, the state in which the fuel gas is flowing through the fuel supply line 50) is higher than the pressure. And in the state where over valve leak has not occurred, the pressure is maintained.
On the other hand, when an over-valve leak occurs, the pressure between the first shutoff valve 51 and the second shutoff valve 52 gradually decreases.

  Therefore, the combustion control unit 81 is disposed between the first shut-off valve 51 and the second shut-off valve 52, and operates by the pressure switch 53 that operates when the pressure falls below the set pressure. While detecting a predetermined pressure drop during the period, and measuring the time required for the pressure drop. Then, the combustion control unit 81 performs per unit time based on the supply pressure of the fuel gas supplied to the fuel supply line 50 and the volume of the fuel supply line 50 between the first shutoff valve 51 and the second shutoff valve 52. Calculate the maximum leak amount of fuel gas.

  Furthermore, the combustion control unit 81 calculates the standby time for starting the combustion without performing the pre-purge, when the valve leakage occurs with the calculated maximum leak amount per unit time. The standby time is calculated based on the maximum leak amount per unit time, the capacity of the boiler 1 (in-furnace capacity), and the lower explosion limit (LEL) of the fuel gas. For example, the standby time is calculated as the time until the combustion gas concentration in the inside of the boiler 1 (in the furnace) reaches 1⁄4 of the LEL when the valve leakage occurs with the maximum leakage amount.

  By performing the above control, if the pressure switch 53 does not operate in the state where an arbitrary time t1 has elapsed after the combustion stop of the boiler 1, the amount of combustion gas flowing into the inside of the boiler 1 is the fuel It can be determined that the lower limit of explosion of the gas has not been reached, and when there is an ignition request for the boiler 1 after the time t1 has elapsed, combustion of the boiler 1 can be started without performing pre-purge.

  In addition, when the pressure switch 53 operates at the time when the time t2 has elapsed, it can be determined how much fuel gas leaks at that time, and the waiting time for starting the combustion without performing the pre-purge Can be calculated. Therefore, even if the pressure switch 53 is operated, the combustion of the boiler 1 can be started without performing the pre-purge if there is an ignition request in a state where the elapsed time from the combustion stop does not exceed the standby time. Therefore, the load followability of the boiler 1 can be improved without compromising the safety.

  In addition, when a predetermined pressure drop is detected by the pressure switch 53, the combustion control unit 81 starts the ignition operation after performing the pre-purge if there is an ignition request after the elapse of the standby time.

  Also, if the time from when the pressure switch 53 detects a predetermined pressure drop after closing the first shutoff valve 51 and the second shutoff valve 52 is equal to or less than the first set time, the combustion control unit 81 determines that: Disable transition to the ignition operation. That is, when the pressure switch 53 operates in a short time after the combustion of the boiler 1 is stopped, a large amount of valve leakage has occurred, and there is a high possibility that the valve has an abnormality. In such a case, by disabling the combustion of the boiler 1, the safety of the boiler 1 can be further improved. The first set time is, for example, a time when the leak amount of the fuel gas calculated at the time when the pressure switch 53 detects a drop in pressure is at least 1/4 of the lower explosion limit (LEL) inside the boiler 1 It can be set.

Next, the operation check unit 82 will be described.
The operation confirmation unit 82 confirms the operation of the pressure switch 53. Specifically, the operation check unit 82 periodically checks the input state (on or off) of the pressure switch 53 to check whether the pressure switch 53 is operating normally. That is, in the present embodiment, the pressure switch 53 is configured by a pressure switch which is turned off when the pressure is lower than the set pressure and turned on when the pressure is higher than the set pressure. Therefore, the operating pressure of the pressure switch 53 is lower than the pressure of the fuel gas at the time of the combustion stop (at the time of closing the first shutoff valve 51 and the second shutoff valve 52). By setting the pressure to a high pressure, the pressure switch 53 can be turned off during the combustion of the boiler 1 and can be turned on when the combustion is stopped.
Thus, for example, when the pressure switch 53 is in the on state in the combustion state of the boiler 1 or in the state where the combustion of the boiler 1 is stopped, the pressure switch 53 is in the off state. It can be determined that it is not operating normally. As described above, the operation check unit 82 can check that the pressure switch 53 is operating normally by periodically checking the input state of the pressure switch 53.

  According to the boiler 1 of the present embodiment described above, the following effects can be obtained.

  When the boiler 1 is disposed in the fuel supply line 50 and the pressure switch 53 for detecting the pressure between the first shutoff valve 51 and the second shutoff valve 52 and a predetermined pressure drop is detected by the pressure switch 53 In addition, the combustion control unit 81 is configured to calculate the standby time for starting the combustion without performing the pre-purge based on the time after the first shut-off valve 51 and the second shut-off valve 52 are closed. As a result, when over-valve leakage of the fuel gas from the shutoff valve occurs, it is possible to determine the standby time for safely ignitering without ventilating (pre-purge) the boiler 1 according to the amount of leakage of the fuel gas. Therefore, even if the fuel gas leaks over the valve, a suitable waiting time can be set, so ignition of the boiler 1 without pre-purge can be realized without compromising safety.

  Further, when the pressure drop is detected by the pressure switch 53, the combustion control unit 81 performs the pre-purge and starts the ignition operation if there is an ignition request after the calculated standby time has elapsed. As a result, the safety at the time of ignition of the boiler 1 when there is a leak over the valve can be improved without performing unnecessary purge and the like.

  Further, when the time after the first shutoff valve 51 and the second shutoff valve 52 are closed is equal to or less than the first set time, the combustion control unit 81 disables the transition to the ignition operation. As a result, the combustion of the boiler 1 can be disabled if the over-valve leakage amount is large, so the safety of the boiler 1 can be further improved.

  Moreover, the pressure switch 53 was comprised by the pressure switch which operate | moves when it becomes less than setting pressure, and the boiler 1 was comprised including the operation confirmation part 82 which confirms operation | movement of the pressure switch 53. FIG. As a result, the pressure switch 53 is turned off when the pressure of the fuel gas decreases while the boiler 1 is burning, and when the combustion is stopped, the pressure of the fuel gas is raised and turned on by closing the shutoff valve. Therefore, by confirming the operation of the pressure switch 53 periodically by the operation confirmation unit 82, it can be confirmed that the pressure switch 53 is operating normally, so the safety of the boiler 1 can be further improved.

Next, a boiler 1A according to a second embodiment of the present invention will be described with reference to FIGS. 3 and 4.
The boiler 1A of the second embodiment differs from the first embodiment mainly in that it further includes a gas release line 90, the configuration of the first shutoff valve 51A and the second shutoff valve 52B, and the configuration of the control unit 71A. In the description of the second and subsequent embodiments, the same components will be denoted by the same reference numerals, and the description thereof will be omitted or simplified.

The boiler 1A of the second embodiment further includes a gas release line 90 and a gas release valve 91 in addition to the configuration of the first embodiment.
One end of the gas release line 90 is connected between the first shutoff valve 51A and the second shutoff valve 52A in the fuel supply line 50, and the other end is opened.
The gas release valve 91 is constituted by an on-off valve such as a solenoid valve and is disposed in the gas release line 90. The gas release valve 91 opens or closes the gas release line 90.

  In the second embodiment, the first shutoff valve 51A includes a first close confirmation switch 511A for confirming the closed state of the first shutoff valve 51A. In addition, the second shutoff valve 52A includes a second close confirmation switch 521A for confirming the closed state of the second shutoff valve 52A. The first close confirmation switch 511A and the second close confirmation switch 521A are respectively first shut off. It is comprised by the mechanical contact incorporated in the valve 51A and the 2nd cutoff valve 52A.

Further, in the second embodiment, the control unit 71A further includes a gas leak determination unit 83A in addition to the combustion control unit 81A and the operation check unit 82A.
The combustion control unit 81A performs the same combustion control as that of the first embodiment.
In addition to the operation of the first shutoff valve 51A and the second shutoff valve 52A, the operation confirmation unit 82A confirms the operation of the first close confirmation switch 511A and the second close confirmation switch 521A.

  The gas leak judgment unit 83A judges the gas leak of the first shutoff valve 51A or the second shutoff valve 52A in the combustion stop state of the boiler 1A. Specifically, in the gas leak determination unit 83A, the combustion control unit 81A issues a closing instruction of the first shutoff valve 51A and the second shutoff valve 52A, and the first shutoff valve 51A and the second shutoff valve 52A are closed. In this case, when the closing state of the first closing confirmation switch 511A and the second closing confirmation switch 521A is confirmed by the operation confirmation unit 82A, the closing state of the first closing confirmation switch 511A and the second closing confirmation switch 521A is continued. Count time Then, the gas leak determination unit 83A counts the closing state continuation time of the first closing confirmation switch 511A or the second closing confirmation switch 521A in a state where the closing instruction is output to the first shutoff valve 51A and the second shutoff valve 52A. If it stops, it is determined that a gas leak has occurred.

  When the gas leak judgment unit 83A judges that a gas leak has occurred, the control unit 71A opens the gas relief valve 91. Thus, for example, when a gas leak occurs in the first shutoff valve 51A and the second shutoff valve 52A, the fuel gas that has passed through the first shutoff valve 51A can be discharged to the outside through the gas escape line 90, so the leaked fuel Gas can be prevented from flowing into the can 10.

  According to the boiler 1A of the second embodiment described above, in addition to the same effects as the first embodiment, the following effects can be obtained.

  The boiler 1A includes a gas release line 90 connected between the first shutoff valve 51A and the second shutoff valve 52A in the fuel supply line 50, and a gas relief valve 91 arranged in the gas escape line 90. The first shutoff valve 51A is configured to include the first closing confirmation switch 511A, and the second shutoff valve 52A is configured to include the second closing confirmation switch 521A. As a result, since the closed state of the first shutoff valve 51A and the second shutoff valve 52A can be confirmed by the closing confirmation switch, the safety of the boiler 1A can be further improved.

  In addition, when the control unit 71A checks the operation of the first close confirmation switch 511A and the second close confirmation switch 521A, and the first shutoff valve 51A and the second shutoff valve 52A are closed, (1) The closed state continuation time of the closed confirmation switch 511A and the second closed confirmation switch 521A is counted, and gas leakage occurs when the counting of the closed state continuation time of the first closed confirmation switch 511A or the second closed confirmation switch 521A is stopped. Gas leakage determination unit 83A that is determined to be present. As a result, in the state where the closing instruction is output to the first shutoff valve 51A and the second shutoff valve 52A, it is possible to promptly determine the gas leak when the closing confirmation by the closing confirmation switch can not be confirmed. Therefore, the safety of the boiler 1A can be further improved.

  Next, a boiler 1B according to a third embodiment of the present invention will be described with reference to FIGS. 5 and 6. The boiler 1B of the third embodiment differs from the first embodiment mainly in the configuration of the pressure detection unit. In the third embodiment, the pressure detection unit includes a differential pressure switch 53B that operates when a predetermined differential pressure is generated between the primary side and the secondary side of the first shutoff valve 51B in the fuel supply line 50. Ru. Further, the first shutoff valve 51B is provided with a first close confirmation switch 511B for confirming the closed state of the first shutoff valve 51B.

Further, in the third embodiment, the control unit 71A includes a combustion control unit 81B, an operation check unit 82B, and a gas leak determination unit 83B, as in the second embodiment.
In the third embodiment, the combustion control unit 81B detects a predetermined pressure drop between the first shutoff valve 51B and the second shutoff valve 52B by the differential pressure switch 53B (the differential pressure switch 53B is operated). Measure the time required for the pressure drop. The operation check unit 82B also checks the operation of the differential pressure switch 53B.

In the third embodiment, when the boiler 1B receives a combustion request, the gas leak determination unit 83B performs the gas leak determination of the first shutoff valve 51B before the start of the ignition operation.
In this gas leak determination, if there is a combustion request in a state in which the first shutoff valve 51B and the second shutoff valve 52B are closed, the gas leak judgment unit 83B first performs the second operation while the first shutoff valve 51B is closed. The shutoff valve 52B is opened, and it is monitored whether or not the differential pressure switch 53B is operated for a predetermined time. Then, the gas leak judgment unit 83B keeps the first close confirmation switch 511B closed (the closed state of the first shut-off valve 51B is detected) for a predetermined time after the second shut-off valve 52B is opened, and When the differential pressure switch 53B does not operate (a predetermined differential pressure does not occur), it is determined that the first shutoff valve 51B is leaking.

That is, when the second shutoff valve 52B is opened with the first shutoff valve 51B closed, the pressure on the secondary side of the first shutoff valve 51B decreases unless a gas leak occurs in the first shutoff valve 51B. Therefore, a differential pressure is generated between the primary side and the secondary side of the first shutoff valve 51B, and the differential pressure switch 53B operates. Therefore, the gas leak judgment unit 83B opens the second shutoff valve 52B in a state where the first shutoff valve 51B is closed, and does not operate the differential pressure switch 53B for a predetermined time after opening the second shutoff valve 52B. It can be determined that a gas leak has occurred in the first shutoff valve 51B.
When the gas leak determination unit 83B determines that the gas in the first shutoff valve 51B is leaked, the combustion control unit 81B starts the ignition operation after performing the pre-purge. In addition, the control unit 71B notifies that the gas leak has occurred in the first shutoff valve 51B.

  According to the boiler 1B of the third embodiment described above, in addition to the same effects as the first embodiment, the following effects can be obtained.

  The pressure detection unit is constituted by a differential pressure switch 53B that operates when a predetermined differential pressure is generated between the primary side and the secondary side of the first shutoff valve 51B, and the control unit 71B is formed by the first shutoff valve 51B. After the second shutoff valve 52B is opened and the second shutoff valve 52B is opened in a closed state, gas leakage occurs in the first shutoff valve 51B when the operation of the differential pressure switch 53B is not detected for a predetermined time. Gas leakage determination unit 83B that is determined to be present. Thereby, since the gas leak of the 1st cutoff valve 51B can be judged before starting combustion of boiler 1B, the safety of boiler 1B can be improved more.

  In addition, when the first shutoff valve 51B is configured to include the first closing confirmation switch 511B, and the first closing confirmation switch 511B is closed in the gas leak determination unit 83B, and the differential pressure switch 53B does not operate. It was determined that leakage occurred in the first shutoff valve 51B. Thus, the gas leak of the first shutoff valve 51B can be determined based on the operation of the first close confirmation switch 511B and the operation of the differential pressure switch 53B, so that the accuracy of the gas leak determination can be further improved.

As mentioned above, although each preferable embodiment of the boiler of this invention was described, this invention is not restrict | limited to the above-mentioned embodiment, It can change suitably.
For example, in the first and second embodiments, the pressure switch 53 is used as the pressure detection unit, but the present invention is not limited to this. That is, a pressure sensor may be used as the pressure detection unit.

  Moreover, in 3rd Embodiment, although the differential pressure switch 53B was used as a pressure detection part, it does not restrict to this. That is, a differential pressure sensor may be used as the pressure detection unit.

  In the second embodiment, when the first shutoff valve 51A and the second shutoff valve 52A are closed by the gas leak judgment unit 83A, the closed state of the first close confirmation switch 511A and the second close confirmation switch 521A continues Although the time is counted and it is determined that the gas leakage has occurred when the counting of the closed state continuation time of the first close confirmation switch 511A or the second close confirmation switch 521A is stopped, the present invention is not limited thereto. That is, when the first shutoff valve 51A and the second shutoff valve 52A are closed, the gas leak determination unit monitors whether the closed state of the first close confirmation switch 511A or the second close confirmation switch 521A is maintained. If the first closing confirmation switch 511A or the second closing confirmation switch 521A is in the open state (that is, the mechanical contact is turned off and the shutoff valve is released from the closing state), the gas leaks. It may be determined that

1, 1A, 1B Boiler 15 burner 50 Fuel supply line 51, 51A, 51B 1st cutoff valve 511A, 511B 1st closure confirmation switch 521A 2nd closure confirmation switch 52, 52A, 52B 2nd cutoff valve 53 pressure switch (pressure detection Department)
53B Differential pressure switch (pressure detector)
71, 71A, 71B control unit 72, 72A, 72B storage unit 81, 81A, 81B combustion control unit 82, 82A, 82B operation check unit 83A, 83B gas leak determination unit 90 gas release line 91 gas release valve

Claims (9)

With the burner,
A fuel supply line for supplying a fuel gas to the burner;
A first shutoff valve disposed in the fuel supply line, a second shutoff valve, and a pressure detection unit disposed between the first shutoff valve and the second shutoff valve;
In a state in which the first shutoff valve and the second shutoff valve are closed, the first shutoff valve and the second shutoff valve are closed when a predetermined pressure drop is detected by the pressure detection unit. And a combustion control unit that calculates a standby time for starting combustion without performing pre-purge based on the time of.   The boiler according to claim 1, wherein the combustion control unit starts the ignition operation after performing pre-purge when there is an ignition request after the elapse of the standby time when the predetermined pressure decrease is detected by the pressure detection unit. .   The combustion control unit is ignited when the time from the closing of the first shutoff valve and the second shutoff valve to the detection of a predetermined pressure drop by the pressure detection unit is equal to or less than a first set time. The boiler according to claim 1 or 2, which makes the transition to operation impossible. The pressure detection unit is configured by a pressure switch that operates when the pressure falls below a set pressure.
The boiler according to any one of claims 1 to 3, further comprising an operation confirmation unit that confirms the operation of the pressure switch. A gas release line connected between the first shutoff valve and the second shutoff valve in the fuel supply line;
And a gas relief valve disposed in the gas relief line,
The first shutoff valve includes a first close confirmation switch for confirming a closed state of the first shutoff valve,
The boiler according to any one of claims 1 to 4, wherein the second shutoff valve comprises a second close confirmation switch for confirming a closed state of the second shutoff valve. An operation confirmation unit that confirms operations of the first close confirmation switch and the second close confirmation switch;
When the first shutoff valve and the second shutoff valve are closed, the closing time durations of the first close confirmation switch and the second close confirmation switch are counted, and the first close confirmation switch or the second close check switch is counted. The boiler according to claim 5, further comprising: a gas leak judging unit that judges that gas leak has occurred when counting of the closing state continuation time of the closing confirmation switch is stopped.   The pressure detection unit according to any one of claims 1 to 4, wherein the pressure detection unit includes a differential pressure switch that operates when a predetermined differential pressure is generated between the primary side and the secondary side of the first shutoff valve. Boiler. When a combustion request is made in a state where the first shutoff valve and the second shutoff valve are closed,
The second shutoff valve is opened in a state in which the first shutoff valve is closed,
The fuel cell system according to claim 7, further comprising a gas leak judging unit that judges that the first shut-off valve is leaking when the operation of the differential pressure switch is not detected for a predetermined time after opening the second shut-off valve. The boiler as described in. The first shutoff valve includes a first close confirmation switch for confirming a closed state of the first shutoff valve,
9. The gas leak judging unit according to claim 8, wherein the first shutoff valve is judged to be leaked when the first close confirmation switch is closed and the differential pressure switch is not operated. boiler.

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