JP2020118358A - Hydrogen combustion boiler device - Google Patents

Abstract

To provide a hydrogen combustion boiler device capable of obtaining stable low NOx performance in a wide combustion region.SOLUTION: A hydrogen combustion boiler device 1 comprises: an exhaust recirculation path 50 that circulates a part of exhaust gas flowing through an exhaust path 20 to an air blower 40; a damper 51 provided in the exhaust recirculation path 50 as an exhaust recirculation flow rate adjustment unit that adjusts an exhaust recirculation flow rate; and a control unit 100 capable of controlling the damper 51. The control unit 100 controls the damper 51 so that an EGR rate becomes higher as a combustion rate becomes lower.SELECTED DRAWING: Figure 1

Description

The present invention relates to a hydrogen combustion boiler device that uses hydrogen gas as a fuel gas.

Conventionally, in a boiler device, there is a NOx reduction method that suppresses the generation of NOx by recirculating a part of exhaust gas to the air supply side and mixing it with combustion air. In this case, since the NOx concentration contained in the exhaust gas is high in the high combustion state, the exhaust gas recirculation rate in the high combustion state (hereinafter, referred to as “EGR rate”) is the EGR in the low combustion state. More than the rate is done. In other words, the EGR rate in the low combustion state is set lower than the EGR rate in the high combustion state. The EGR rate is a value obtained by dividing the flow rate of exhaust gas (exhaust gas recirculation flow rate) by the flow rate of outside air (air flow rate).
For example, Patent Document 1 discloses that when the combustion amount is increased, the NOx emission concentration is increased and the self-exhaust gas recirculation amount is increased, whereby low NOx performance can be secured.

JP, 2008-145069, A

Therefore, the present inventor also performed control to increase the EGR rate in the high combustion state even in the hydrogen combustion boiler device (small once-through boiler), and the NOx concentration becomes a sufficiently low value in the low combustion state. It was confirmed that it did not happen.
That is, it has been found that, in the hydrogen combustion boiler device, in order to obtain stable low NOx performance in a wide combustion range from a low combustion state to a high combustion state, it is necessary to control the EGR rate suitable for the hydrogen combustion boiler. ..

The present invention has been made in view of the above problems, and an object of the present invention is to provide a hydrogen combustion boiler device capable of obtaining stable low NOx performance in a wide combustion region.

The present invention relates to a boiler main body that burns hydrogen gas as a fuel gas to heat feed water, a fuel gas supply line that supplies the hydrogen gas to the boiler main body, and a combustion gas that supplies combustion air to the boiler main body. An air supply line, a blower that is connected to the upstream side of the combustion air supply line and sends combustion air to the combustion air supply line, and an exhaust path that discharges exhaust gas generated by combustion of fuel in the boiler body. An exhaust gas recirculation path for circulating a part of the exhaust gas flowing through the exhaust path to the blower, an exhaust gas recirculation flow rate adjusting unit for adjusting the exhaust gas recirculation flow rate, which is provided in the exhaust gas recirculation path, and a combustion rate The lower the value is, the higher the EGR rate is, and the exhaust gas recirculation flow rate control unit that controls the exhaust gas recirculation flow rate adjustment unit is controlled.

Further, the hydrogen combustion boiler device is a continuous control boiler device capable of combustion control so that the combustion rate continuously changes in a range from a low combustion state to a high combustion state, and the exhaust gas recirculation flow rate control unit is It is preferable to continuously control the exhaust gas recirculation flow rate control unit so that the EGR rate becomes higher as the combustion rate becomes lower.

Further, the hydrogen combustion boiler device, in the range of low combustion state to high combustion state, is a stage value control boiler device capable of combustion control at a plurality of stepwise combustion rates, the exhaust gas recirculation flow rate control unit, It is preferable to control the exhaust gas recirculation flow rate adjusting unit according to the multistage combustion state such that the EGR rate becomes higher as the combustion rate becomes lower.

Further, it is preferable that the exhaust gas recirculation flow rate control unit controls the exhaust gas recirculation flow rate adjustment unit so that the correspondence relationship between the combustion rate and the exhaust gas recirculation flow rate is a linear function.

Further, the hydrogen combustion boiler device includes a combustion air flow rate detection unit that detects a flow rate of combustion air flowing through the combustion air supply line, and the exhaust gas recirculation flow rate control unit includes a combustion air flow rate detection unit. It is preferable to control the exhaust gas recirculation flow rate adjusting unit based on a signal corresponding to the detected combustion air flow rate.

Further, the hydrogen combustion boiler device, a combustion air flow rate adjusting unit for adjusting the combustion air flow rate flowing through the combustion air supply line, and a combustion air flow rate control unit for controlling the combustion air flow rate adjusting unit. And the combustion air flow rate control unit adjusts the combustion air flow rate such that the correspondence relationship with the combustion rate is a linear function relationship, and the air ratio increases as the combustion rate decreases. It is preferable to control the parts.

Moreover, it is preferable that the hydrogen combustion boiler apparatus further includes an averaging processing unit that performs averaging processing of signals of the combustion air flow rate detection unit.

Further, the hydrogen combustion boiler device is arranged in the fuel gas supply line and corresponds to a fuel gas flow rate adjusting unit capable of adjusting a fuel gas flow rate and the combustion air flow rate detected by the combustion air flow rate detecting unit. It is preferable that the fuel gas flow rate controller controls the fuel gas flow rate adjuster based on the signal.

Further, the hydrogen combustion boiler device comprises a signal branching unit for branching a signal of the combustion air flow rate detection unit to the fuel gas flow rate control unit and the exhaust gas recirculation flow rate control unit, and the exhaust gas recirculation flow rate control unit is It is preferable that the opening degree of the exhaust gas recirculation flow rate adjusting unit is adjusted by a signal from the combustion air flow rate detecting unit.

Further, the fuel gas flow rate control unit converts a signal from the combustion air flow rate detection unit into an opening degree signal of the fuel gas flow rate adjusting section, and adjusts the opening degree of the fuel gas flow rate adjusting section based on the opening degree signal. At the same time, the opening degree signal is transmitted to the exhaust gas recirculation flow rate control unit, and the exhaust gas recirculation flow rate control unit may adjust the opening degree of the exhaust gas recirculation flow rate adjustment unit based on the opening degree signal. preferable.

According to the present invention, it is possible to provide a hydrogen combustion boiler device capable of obtaining stable low NOx performance in a wide combustion region.

It is a figure which shows the hydrogen combustion boiler apparatus which concerns on 1st Embodiment of this invention. It is a figure which shows the relationship between a combustion rate and NOx, when an EGR rate is fixed to 0%. It is a figure which shows the relationship between a combustion rate and NOx concentration and EGR rate. It is a figure which shows the relationship between a combustion rate and exhaust gas recirculation flow rate/EGR rate. It is a flowchart explaining the process which changes an EGR rate according to the content of a combustion rate. It is a figure which shows the hydrogen combustion boiler apparatus which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the structure of a control part. It is a flow chart explaining the processing which changes the opening of a fuel gas flow control valve and a damper according to the flow rate of combustion air. It is a figure which shows the correspondence of a combustion rate and the flow rate of combustion air. It is a figure which shows the correspondence of combustion air flow rate, exhaust gas recirculation flow rate, and EGR rate. It is a block diagram which shows the other structure of a control part.

<First Embodiment>
Hereinafter, the hydrogen combustion boiler device 1 according to the first embodiment of the present invention will be described with reference to FIGS. The hydrogen combustion boiler device 1 of the present embodiment is a steam boiler (through-flow boiler) that heats water to generate steam, and supplies steam to a load device (not shown). Further, the hydrogen combustion boiler device 1 of the present embodiment is an exhaust gas recirculation type hydrogen combustion boiler device 1 in which a part of exhaust gas is circulated to the air supply side and used as combustion air. In addition, the "line" in this specification is a general term for a line such as a flow path, a route, or a pipe line through which a fluid can flow.

As shown in FIG. 1, the hydrogen combustion boiler device 1 of the present embodiment includes a boiler body 10, an exhaust passage 20, an air supply passage 30 as a combustion air supply line, a blower 40, and an exhaust gas recirculation passage 50. The water supply line 70, the water supply heater 80, the fuel gas supply line 90, and the controller 100.

The boiler body 10 burns fuel to heat feed water to generate steam. The boiler body 10 includes a can body 11 that is a cylindrical round can body that forms an outer shape, and a burner 12 that is disposed on the top of the can body 11. The can body 11 includes a plurality of water pipes, a lower header, an upper header, and a combustion chamber (none of which is shown). The burner 12 is a premixing burner, and after the combustion air supplied from the air supply passage 30 and the hydrogen gas as the fuel gas supplied from the fuel gas supply line 90 are mixed in the premixing burner. Burned.

The exhaust passage 20 discharges the exhaust gas generated by burning the fuel in the boiler body 10 to the outside. The base end side of the exhaust passage 20 is connected to the peripheral surface of the can body 11. The tip side of the exhaust passage 20 extends upward.

The air supply passage 30 supplies combustion air to the boiler body 10. The tip side of the air supply passage 30 is connected to the upper portion of the boiler body 10. The base end side of the air supply passage 30 extends downward.

The blower 40 is arranged in a lower portion of a side portion of the boiler body 10. The blower 40 is connected to the base end side of the air supply passage 30 and sends the combustion air into the air supply passage 30. The blower 40 includes a fan and a motor that rotates the fan, and the frequency of the motor is controlled by an inverter 41 so that the rotation speed of the motor can be adjusted.

The exhaust gas recirculation path 50 connects the exhaust path 20 to the inlet side of the blower 40, and circulates a part of the exhaust gas flowing through the exhaust path 20 to the blower 40 side. That is, in the present embodiment, the blower 40 sucks the outside air and the exhaust gas supplied from the exhaust gas recirculation passage 50, and sends the mixture of the outside air (air) and the exhaust gas to the air supply passage 30 as combustion air.
A damper 51 as an exhaust gas recirculation flow rate adjusting unit is arranged in the exhaust gas recirculation path 50. The damper 51 adjusts the flow rate of the exhaust gas that flows through the exhaust gas recirculation path 50 and is circulated in the blower 40 by changing the opening degree.

The water supply line 70 has a base end side connected to a water supply source (not shown) and a front end side connected to the boiler body 10 (lower header). The water supply line 70 supplies water for generating steam to the boiler body 10.

The feed water heater 80 is arranged on the upstream side (downward) of the connection portion of the exhaust passage 20 with the exhaust gas recirculation passage 50. The feed water heater 80 heats the feed water by exchanging heat between the exhaust gas discharged from the boiler body 10 and flowing through the exhaust passage 20 and the feed water flowing through the water supply line 70.

The fuel gas supply line 90 supplies hydrogen gas as fuel gas to the boiler body 10. The fuel gas supply line 90 is provided with a fuel gas flow rate adjusting valve 91 as a fuel gas flow rate adjusting unit and a shutoff valve 92.
The shutoff valve 92 is a valve for shutting off the fuel gas supply line 90 when the fuel gas is not supplied, and is controlled by the control unit 100.

The control unit 100 controls the combustion state of hydrogen gas (combustion state of the hydrogen combustion boiler device 1) and the damper 51 as an exhaust gas recirculation flow rate adjustment unit. More specifically, the control unit 100 controls the rotation speed of the motor of the blower 40, the opening degree of the damper 51, the opening degree of the fuel gas flow rate adjusting valve 91, and the like in accordance with the combustion state command signal that indicates the combustion state. .. Here, the control unit 100 in the present embodiment has a function of controlling the opening degree of the damper 51, and also has a function as an exhaust gas recirculation flow rate control unit of the present invention.

Next, the operation of the hydrogen combustion boiler device 1 of the present embodiment will be described.
In the hydrogen combustion boiler device 1, combustion air is supplied from the air supply passage 30 to the inside of the boiler body 10, and fuel gas is supplied from the fuel gas supply line 90 to burn the fuel gas. Further, water is supplied from a water supply line 70 to a plurality of water pipes arranged inside the can body 11, and the heat generated by burning the fuel gas heats the water supply to generate steam.

The combustion gas generated by the combustion of the fuel gas heats the water in the water pipe and then flows through the exhaust passage 20 as exhaust gas. The exhaust gas flowing from the lower part to the upper part of the exhaust passage 20 heats the feed water in the feed water heater 80. Part of the exhaust gas whose temperature has dropped due to heat exchange in the feed water heater 80 flows through the exhaust gas recirculation path 50, and the rest is discharged to the outside.

The exhaust gas flowing through the exhaust gas recirculation path 50 is supplied to the blower 40 and is sent to the air supply path 30 together with the outside air.
As a result, the exhaust gas circulated to the air supply side of the blower and the outside air are mixed at a predetermined ratio, and the mixed gas is used as combustion air to combust the fuel gas.

Here, the control unit 100 responds to the combustion state command signal that indicates the combustion state (combustion rate or combustion position of the hydrogen combustion boiler device 1), the rotation speed of the motor of the blower 40, the opening degree of the damper 51, the fuel gas. The opening degree of the flow rate adjusting valve 91 is controlled. Specifically, the control unit 100 receives a combustion state command signal as an external command signal for instructing the combustion state, and the flow rate of the combustion air sent to the air supply passage 30 is appropriate according to the combustion state command signal. The motor speed of the blower 40 is controlled via the inverter 41 so that the flow rate will be constant. Then, in order to control the NOx concentration in the exhaust gas, the damper 51 as an exhaust gas recirculation flow rate adjusting unit is controlled so that the exhaust gas recirculation flow rate corresponds to the combustion state command signal. Further, the opening of the fuel gas flow rate adjusting valve 91 is controlled in order to supply the fuel gas corresponding to the combustion state command signal. The control unit 100 performs control such that the higher the command value of the combustion state command signal, the higher the combustion state, and the lower the command value of the combustion state command signal, the lower the combustion state. In the case of performing exhaust gas recirculation, the combustion air is a mixture of the outside air (air) and the exhaust gas from the exhaust gas recirculation passage 50.

The relationship between the combustion state, EGR rate, and NOx concentration will be described below.
Conventionally, in a boiler device, it is known that the NOx concentration contained in the exhaust gas becomes high in a high combustion state. Therefore, the EGR rate in the high combustion state is usually higher than the EGR rate in the low combustion state. In other words, the EGR rate in the low combustion state is set lower than the EGR rate in the high combustion state. Therefore, the present inventor has confirmed that even in the hydrogen combustion boiler device, when the device is controlled by setting such an EGR rate, the NOx concentration does not become a sufficiently low value in the low combustion state.
That is, it has been found that, in the hydrogen combustion boiler device, in order to obtain stable low NOx performance in a wide combustion range, it is necessary to control the EGR rate suitable for the hydrogen combustion boiler.

Therefore, the present inventor measured the NOx concentration contained in the exhaust gas by fixing the EGR rate to 0% and changing the combustion state command signal as an external command for instructing the combustion state.
FIG. 2 shows a combustion state in a hydrogen combustion boiler apparatus having a round can body (through-flow boiler) and a premixing burner (burner for diffusion combustion) and performing continuous control when the EGR rate is fixed to 0%. It is a graph which shows the relationship between the combustion rate based on a command signal, and NOx concentration. Since the NOx concentration varies depending on the O2 concentration of the sampled gas sample, the NOx concentration of the O2 (0%) conversion value is shown in this embodiment.

As shown in FIG. 2, in the hydrogen combustion boiler device, it was confirmed that the NOx concentration becomes lower as the burning rate becomes higher in the range from the low combustion state to the high combustion state. In other words, the inventor has discovered the fact that the lower the combustion rate, the higher the NOx concentration.
This phenomenon that occurs in the boiler device that burns hydrogen gas is, for example, when the combustion rate is high, the jetting speed of the combustion air and hydrogen gas as the fuel gas becomes faster, and the flame extends and burns in a wide range. On the other hand, when the combustion rate is low, the jetting speed of the combustion air and the hydrogen gas becomes slow, and there is a possibility that the combustion is in a narrow range. As a result, it is presumed that when the combustion rate is low, a local high-temperature part is easily formed and the NOx concentration becomes high.
Hydrogen gas has properties that are significantly different from other gases, such as a wider flammable range, a faster burning rate, and a higher flame temperature than other gases such as methane (combustion characteristics of hydrogen, Yoshihiro Ogisu) , Fuel Association Magazine, Vol. 54, No. 583 (1975)). In the hydrogen combustion boiler apparatus using such hydrogen gas, the above phenomenon is not confirmed near the low combustion state, but is strong in the low combustion state and weakens as the combustion becomes higher, as shown in FIG. ing.

FIG. 3 is provided with a hydrogen combustion boiler device 1 (a round can body (through-flow boiler) and a premixing burner (a burner that performs diffusion combustion)) of the present embodiment, which was devised based on such knowledge, and the continuous control is performed. 6 is a graph showing a relationship between a combustion rate, a NOx concentration, and an EGR rate in the case of burning (performing).
In the present embodiment, the control unit 100 performs control such that the higher the combustion rate based on the command value of the combustion state command signal, the lower the EGR rate. In other words, the damper 51 as the exhaust gas recirculation flow rate adjusting unit is controlled so that the EGR rate becomes higher as the combustion rate based on the command value of the combustion state command signal becomes lower. By performing such control, the actual measurement value of the EGR rate changes as shown by the solid curve in FIG. 3, and the NOx concentration becomes substantially constant as shown by the dotted line.

For example, along the horizontal axis of FIG. 3, when combustion control can be performed so that the combustion rate continuously changes, or in a range from a low combustion state to a high combustion state, combustion is performed at a plurality of stepwise combustion rates. In the controllable case, the damper 51 as the exhaust gas recirculation flow rate adjusting unit is controlled so that the EGR rate becomes higher as the combustion rate based on the command value of the combustion state command signal becomes lower.
For example, as shown by the solid line in the graph of FIG. 3, the EGR rate is about 5.2% when the combustion rate is 100%, and the EGR rate is 7.5% and the combustion rate is 25% when the combustion rate is 55%. When it is %, the damper 51 is controlled so that the EGR rate becomes about 11%. When the combustion rate is an intermediate value between these values, the EGR rate also uses the intermediate value on the curve. For example, when the combustion rate is 80%, the damper 51 is controlled so that the EGR rate becomes about 6%.
The line indicating the value of the EGR rate to be set is not limited to this, and may be a curve connecting a plurality of points or a straight line.

This makes it possible to sufficiently reduce the NOx concentration contained in the exhaust gas in the range from the low combustion state to the high combustion state. That is, also in the hydrogen combustion boiler device, a remarkable effect that stable low NOx performance can be obtained in a wide combustion region can be obtained. Further, when the combustion rate is high, the control is performed in the direction of lowering the EGR rate, so the load of the blower due to exhaust gas recirculation can be reduced in the high combustion state region where the combustion air flow rate increases, and the power consumption of the blower can be reduced. Besides, it is possible to reduce the size of the blower used.

FIG. 4 shows another example showing the relationship between the combustion rate and the EGR rate. FIG. 4 also shows the relationship between the combustion rate and the exhaust gas recirculation flow rate.
As shown in FIG. 4, the control unit 100 controls the combustion rate based on the command value of the combustion state command signal such that the higher the combustion rate based on the command value of the combustion state command signal, the lower the EGR rate. The damper 51 as the exhaust gas recirculation flow rate adjusting unit is controlled so that the correspondence relationship between the exhaust gas recirculation flow rate and the exhaust gas recirculation flow rate is a linear function. For example, when the combustion rate is 20%, the exhaust gas recirculation flow rate is a', when the combustion rate is 60%, the exhaust gas recirculation flow rate is b', and when the combustion rate is 100%, The damper 51 is adjusted so that the exhaust gas recirculation flow rate is c'.
As described above, if the correspondence relationship between the combustion rate and the exhaust gas recirculation flow rate is a linear function, the calculation of the exhaust gas recirculation flow rate corresponding to the instructed combustion rate and the subsequent control of the damper 51 can be easily performed. You can Even in this case, as shown in FIG. 4, the relationship between the combustion rate and the exhaust gas recirculation flow rate is set so that the relationship that the EGR rate becomes lower as the combustion rate becomes higher is maintained. ..
In addition, when the correspondence between the combustion rate and the exhaust gas recirculation flow rate is a linear function, the variation of the oxygen concentration and/or the NOx concentration in the exhaust gas is substantially within the allowable range. Including the case that can be approximated by a linear function.

In addition, it is preferable that the control unit 100 execute the control for changing the EGR rate in a timely manner according to the content of the input combustion state command signal.
FIG. 5 is a flow chart for explaining the process of changing the EGR rate in the hydrogen combustion boiler device 1 of the present embodiment in accordance with the content of the combustion state command signal for instructing the combustion state.

In step S1, it is determined whether or not a low combustion state command signal, which is a command signal for lowering the combustion state, is input as the combustion state command signal.
When it is determined that the low combustion state command signal has been input (YES in step S1), control for increasing the EGR rate is performed in step S2.

For example, when the hydrogen combustion boiler device 1 is a continuous control boiler device (proportional control boiler device) capable of performing combustion control so that the combustion rate continuously changes in the range from the low combustion state to the high combustion state, The unit 100 controls the damper 51 so that the EGR rate becomes higher as the combustion rate becomes lower. More specifically, when the low combustion state command signal (the combustion state command signal lower than the predetermined combustion rate) is input, the control unit 100 is set so as to increase as the combustion rate decreases. The opening degree of the damper 51 is controlled so as to obtain the ratio. At this time, it is preferable to control the EGR rate and the opening degree of the damper 51 so as to continuously change like the combustion rate. It should be noted that the EGR rate and the opening degree of the damper 51 may be controlled to be changed stepwise according to the combustion rate region divided into three or more.

On the other hand, the hydrogen combustion boiler device 1 has a plurality of stepwise combustion rates, for example, four stages of combustion stop state, low combustion state, medium combustion state and high combustion state (in the range from the low combustion state to the high combustion state, When it is determined that the medium combustion state command signal is input during the high combustion state in the case of the stage value control boiler device (4 position control boiler device) that burns at the combustion position of 3 stages), the control unit 100 The opening degree of the damper 51 is controlled so that the EGR rate is higher than the preset EGR rate in the high combustion state. Further, when it is determined that the low combustion state command signal is input during the medium combustion state, the control unit 100 causes the damper 51 to have a preset EGR rate higher than the EGR rate in the medium combustion state. Control the opening. In this way, in the range from the low combustion state to the high combustion state, for example, in the case of a stage value control boiler device capable of combustion control with at least three or more stages of combustion rate, the control unit 100 is The opening degree of the damper 51 is controlled so that the EGR rate becomes high. At this time, it is preferable to control the EGR rate and the opening degree of the damper 51 so as to change stepwise in accordance with the stage of the combustion rate.

When it is determined that the low combustion state command signal has not been input (NO in step S1), the process proceeds to step S3.

In step S3, it is determined whether or not a high combustion state command signal, which is a command signal for raising the combustion state, is input as the combustion state command signal.
When it is determined that the high combustion state command signal has been input (YES in step S3), control is performed to reduce the EGR rate in step S4.

For example, in the case where the hydrogen combustion boiler device 1 is the above-described continuous control boiler device, when the high combustion state command signal (the combustion state command signal higher than the predetermined combustion rate) is input, the control unit 100 The opening degree of the damper 51 is controlled so that the EGR rate is set to decrease as the combustion rate increases.

On the other hand, in the case where the hydrogen combustion boiler device 1 is the above-described step value control boiler, when it is determined that the medium combustion state command signal is input at the low combustion position, the control unit 100 sets the preset low value. The opening degree of the damper 51 is controlled so that the EGR rate is lower than the EGR rate in the combustion state. Further, when it is determined that the high combustion state command signal is input at the medium combustion position, the control unit 100 causes the damper 51 to have a preset EGR rate lower than the preset EGR rate in the medium combustion state. Control the opening.

Thus, when the low combustion state command signal which is a command signal for lowering the combustion state is input as the combustion state command signal, the control unit 100 sets the EGR rate to be lower as the input combustion rate is lower. Control to raise.
As a result, the control for appropriately increasing the EGR rate is performed according to the control in the direction in which the combustion state decreases, so that the generation of NOx can be suppressed.

Even when the EGR rate is 10% or more, the control unit 100 increases the EGR rate when a low combustion state command signal that is a command signal for lowering the combustion state is input as the combustion state command signal. Control. In other words, in the present invention, in the low combustion state, the hydrogen combustion boiler device 1 is operated at an EGR rate exceeding 10%.
That is, even when the EGR rate is as high as 10% or more, the control for further increasing the exhaust EGR rate is performed at the timing when the control in the direction of decreasing the combustion state is performed. Thereby, NOx generation can be suppressed.

Further, when a high combustion state command signal, which is a command signal for increasing the combustion state, is input as the combustion state command signal, the control unit 100 controls the EGR rate to decrease as the input combustion rate increases. To do.
Thereby, according to the control in the direction of increasing the combustion state, the control for appropriately lowering the EGR rate is performed, so that the load of the blower due to the exhaust gas recirculation can be reduced in the region of the high combustion state in which the combustion air flow rate increases. In addition to reducing the power consumption of the blower, it is possible to prevent the blower used from increasing in size.

According to the hydrogen combustion boiler device 1 of the present embodiment described above, the following effects are achieved.

(1) The hydrogen combustion boiler device 1 of the present embodiment includes a boiler body 10 that burns hydrogen gas as a fuel gas to heat feed water, a fuel gas supply line 90 that supplies hydrogen gas to the boiler body 10, and a boiler. The air supply passage 30 that supplies combustion air to the main body 10, the blower 40 that is connected to the upstream side of the air supply passage 30 and sends the combustion air to the air supply passage 30, and the fuel is burned and generated in the boiler body 10. An exhaust passage 20 for discharging exhaust gas, an exhaust gas recirculation passage 50 for circulating a part of the exhaust gas flowing through the exhaust passage 20 to the blower 40, and an exhaust gas provided in the exhaust gas recirculation passage 50 for adjusting the exhaust gas recirculation flow rate. It includes a damper 51 as a recirculation flow rate adjusting unit, and a control unit 100 that controls the damper 51 so that the EGR rate becomes higher as the combustion rate becomes lower.
As a result, the NOx concentration contained in the exhaust gas can be sufficiently reduced in the range from the low combustion state to the high combustion state, and stable low NOx performance can be obtained in a wide combustion range even in the hydrogen combustion boiler device.
Further, when the combustion rate is high, the control is performed in the direction of lowering the EGR rate, so the load on the blower due to exhaust gas recirculation can be reduced, the power consumption of the blower can be reduced, and the blower to be used can be prevented from increasing in size. be able to.

(2) The hydrogen combustion boiler device 1 of the present embodiment is a continuous control boiler device capable of performing combustion control so that the combustion rate continuously changes in the range from the low combustion state to the high combustion state. The damper 51 is continuously controlled so that the EGR rate becomes higher as the combustion rate becomes lower.
As a result, continuously stable low NOx performance can be obtained in the range from the low combustion state to the high combustion state.

(3) The hydrogen combustion boiler device 1 of the present embodiment is a stage value control boiler device capable of combustion control with a plurality of stepwise combustion rates in the range from the low combustion state to the high combustion state. The damper 51 is controlled according to the multistage combustion state so that the EGR rate becomes higher as the combustion rate becomes lower.
As a result, stable low NOx performance can be obtained in any combustion state in the range from the low combustion state to the high combustion state.

(4) In the present embodiment, the control unit 100 controls the damper 51 so that the correspondence relationship between the combustion rate and the exhaust gas recirculation flow rate becomes a linear function relationship.
As described above, if the correspondence relationship between the combustion rate and the exhaust gas recirculation flow rate is a linear function, the calculation of the exhaust gas recirculation flow rate corresponding to the instructed combustion rate and the subsequent control of the damper 51 can be easily performed. You can

(5) In the present embodiment, the control unit 100 performs control to increase the EGR rate according to the low combustion state command signal that is a command signal for lowering the combustion state.
As a result, the control for appropriately increasing the EGR rate is performed at the timing when the control for decreasing the combustion state is performed, so that the NOx concentration in the exhaust gas does not increase.

(6) In the present embodiment, the control unit 100 increases the EGR rate according to the low combustion state command signal which is a command signal for lowering the combustion state even when the EGR rate is 10% or more. Take control.
As a result, the control for appropriately increasing the EGR rate is performed at the timing when the control for decreasing the combustion state is performed, so that the NOx concentration in the exhaust gas does not increase.

(7) In the present embodiment, the control unit 100 performs control to reduce the EGR rate according to the high combustion state command signal that is a command signal for increasing the combustion state.
As a result, the control for appropriately lowering the EGR rate is performed at the timing when the control in the direction of increasing the combustion state is performed, so that the load of the blower due to exhaust gas recirculation can be reduced, and the power consumption of the blower can be reduced. It is possible to prevent the blower from increasing in size.

<Second Embodiment>
Next, a second embodiment will be described with reference to FIGS. Note that the description of the same configuration as the first embodiment will be omitted.
The hydrogen combustion boiler device 1 of the first embodiment controls the damper 51 as the exhaust gas recirculation flow rate adjusting unit according to the content of the input combustion state command signal. The hydrogen combustion boiler device 1 of the second embodiment includes an air differential pressure sensor 31 as a combustion air flow rate detection unit that detects the flow rate of combustion air flowing through the air supply passage 30, and the control unit 200 includes an air differential pressure sensor. Based on the signal corresponding to the flow rate of combustion air detected by 31, the damper 51 as an exhaust gas recirculation flow rate adjusting unit is controlled.

FIG. 6 is a diagram showing a hydrogen combustion boiler device 1 according to a second embodiment of the present invention.
As shown in FIG. 6, an air differential pressure sensor 31 as a combustion air flow rate detection unit that detects the flow rate of combustion air flowing through the air supply passage 30 is arranged in the air supply passage 30 of the present embodiment. The air differential pressure sensor 31 has a fixed pressure loss portion 32 formed by punching metal, an orifice, or the like. By measuring the pressure difference between the pressure on the upstream side and the pressure on the downstream side of the fixed pressure loss portion 32, it is possible to obtain a signal corresponding to the flow rate of combustion air. As the combustion air flow rate detection unit, a sensor other than the air differential pressure sensor 31, for example, a wind pressure sensor, an air flow sensor (such as a hot wire type), may be used to obtain a signal corresponding to the combustion air flow rate.

The control unit 200 acquires the detection signal of the air differential pressure sensor 31. Further, the control unit 200 controls the rotation speed of the motor of the blower 40, the opening degree of the damper 51, the opening degree of the fuel gas flow rate adjusting valve 91, and the like.
FIG. 7 is a block diagram showing the configuration of the control unit 200. As shown in FIG. 7, the control unit 200 includes a combustion air flow rate control unit 202, a combustion air flow rate signal acquisition unit 203, an averaging processing unit 204, a signal branching unit 205, and a fuel gas flow rate control unit 206. An exhaust gas recirculation flow rate control unit 207 and a storage unit 208.
Although the control unit 200 is composed of a plurality of functional blocks as described above, each block does not necessarily have to be physically separated, and the functions of a plurality of blocks can be realized by one CPU. You may comprise. Further, the control unit 200 may be divided into two or more in consideration of the arrangement and wiring of the control target device.

FIG. 8 shows a fuel gas flow rate adjusting valve 91 and a fuel gas flow rate adjusting valve 91 as a fuel gas flow rate adjusting unit based on a signal corresponding to the combustion air flow rate detected by the air differential pressure sensor 31 in the hydrogen combustion boiler device 1 of the present embodiment. It is a flow chart for explaining processing which controls damper 51 as an exhaust gas recirculation flow rate adjustment part.

In step S11, the combustion rate (combustion amount, load rate) is set according to the amount of steam consumed by a load device (not shown) to which the steam from the hydrogen combustion boiler device 1 is supplied. Specifically, the combustion rate is set based on, for example, the pressure of the steam header of the hydrogen combustion boiler device 1.

In step S12, control for supplying the combustion air flow rate corresponding to the set combustion rate is performed. Specifically, the combustion air flow rate control unit 202 controls the frequency of the inverter 41 according to the value of the combustion air flow rate corresponding to the set combustion rate. Thereby, the rotation speed of the motor of the blower 40 is adjusted, and the combustion air having a flow rate according to the rotation speed of the motor is supplied to the air supply passage 30. Here, the inverter 41 and the motor of the blower 40 constitute the combustion air flow rate adjusting unit in the present embodiment. A damper may be provided on the downstream side of the blower 40 and used as a combustion air flow rate adjusting unit.
The correspondence between the combustion rate and the flow rate of combustion air will be described later with reference to FIG.

Here, the amount of air blown by the blower 40 does not immediately reach a target value due to the problem of rising response. For example, when changing the setting of the combustion rate, the combustion air flow rate gradually changes toward the flow rate value corresponding to the set combustion rate. Further, the combustion air flow rate may change due to fluctuations in the furnace pressure of the boiler.
In this way, considering that there is a situation where the combustion air flows at a flow rate different from the target flow rate value, the fuel gas flow rate is adjusted and supplied to a flow rate corresponding to the actual combustion air flow rate. It is preferable. Also, the exhaust gas recirculation flow rate is preferably adjusted to an exhaust gas recirculation flow rate corresponding to the actual combustion air flow rate (including the exhaust gas recirculation flow rate). As a result, the exhaust gas recirculation flow rate can be controlled to the target value even if the combustion air flow rate fluctuates, and a good combustion state can be maintained.

Therefore, in the present embodiment, the air differential pressure sensor 31 detects a signal corresponding to the actual flow rate of combustion air, and various controls are performed using a control value based on the detected signal.
In step S<b>13, the combustion air flow rate signal acquisition unit 203 acquires a signal corresponding to the combustion air flow rate detected by the air differential pressure sensor 31.

In step S14, the averaging processing unit 204 performs averaging processing of the signal corresponding to the combustion air flow rate. Specifically, the averaging processing unit 204 receives from the combustion air flow rate signal acquisition unit 203 a signal corresponding to the combustion air flow rate within a predetermined period in the past (for example, in the past several seconds), and a moving average of the received signals. Calculate the value.
The combustion air flow rate signal is unstable, and detection noise is present. Therefore, by performing the averaging process, the subsequent process based on the signal corresponding to the combustion air flow rate can be made stable. Here, as the moving average value, a simple moving average value may be used, or a weighted moving average value obtained by giving a larger weight to a current value may be used.

In step S15, the signal branching unit 205 branches the signal received from the averaging processing unit 204 and transmits the signal to the fuel gas flow rate control unit 206 and the exhaust gas recirculation flow rate control unit 207. As described above, since the signal after the averaging process is branched and transmitted to the plurality of control units, the same stable signal can be transmitted to each control unit. Therefore, the control thereafter is stable.

In step S16, the fuel gas flow rate control unit 206 controls the opening degree of the fuel gas flow rate adjustment valve 91 based on the signal corresponding to the branched combustion air flow rate. Further, the exhaust gas recirculation flow rate control unit 207 controls the opening degree of the damper 51 based on the signal corresponding to the branched combustion air flow rate. Here, the opening degree of the damper 51 is set based on the exhaust gas recirculation flow rate corresponding to the combustion air flow rate. The correspondence between the combustion air flow rate and the exhaust gas recirculation flow rate will be described later with reference to FIG.

By performing such control, the exhaust gas recirculation flow rate can be controlled to the target value according to the combustion air amount even when there is a situation in which the combustion air flows at a flow rate different from the target flow rate value. (It can be controlled to a target EGR rate corresponding to the combustion amount), and a good combustion state can be maintained.
In particular, in the present embodiment, a suitable exhaust gas recirculation flow rate is set according to the actual combustion air flow rate, and an appropriate amount of exhaust gas can be circulated to the blower, so stable exhaust gas recirculation combustion is realized. In addition, low NOx performance can be realized.
Further, by controlling the opening amounts of the fuel gas flow rate adjusting valve 91 and the damper 51 so that the fuel gas flow rate and the exhaust gas recirculation flow rate correspond to the actual combustion air flow rate, the air-fuel ratio and the EGR rate are appropriately adjusted. Can be controlled.

Further, this control is suitable for the continuous control boiler device capable of performing combustion control so that the combustion rate continuously changes in the range from the low combustion state to the high combustion state as described in the first embodiment. Applicable. At this time, the exhaust gas recirculation flow rate and the opening degree of the damper 51 can be controlled so as to continuously change according to the control value based on the signal corresponding to the combustion air flow rate detected by the air differential pressure sensor 31. preferable. In addition, for example, the exhaust gas recirculation flow rate and the opening degree of the damper 51 may be controlled to be changed stepwise according to the region of the combustion air flow rate divided into three or more.

Further, a stage value control boiler device capable of controlling combustion at a plurality of stepwise combustion rates, for example, four stages (combustion stopped state, low combustion state, medium combustion state, high combustion state (range from low combustion state to high combustion state) (3) can be applied to a stage value control boiler device that burns at three stages of combustion positions. At this time, the exhaust gas recirculation flow rate and the opening degree of the damper 51 can be controlled so as to continuously change according to the control value based on the signal corresponding to the combustion air flow rate detected by the air differential pressure sensor 31. preferable. It should be noted that the exhaust gas recirculation flow rate and the opening degree of the damper 51 may also be controlled to change stepwise in accordance with the stepwise combustion air flow rate region corresponding to the stepwise combustion position.

FIG. 9 is a diagram showing a correspondence relationship between a combustion rate and a combustion air flow rate. In step S12, the target combustion air flow rate is set on the basis of the combustion rate set in step S11 and the correspondence shown in FIG. 9, and the inverter 41 of the inverter 41 is set so that this combustion air flow rate flows. The frequency is controlled. For example, when the set combustion rate is 60%, the frequency of the inverter 41 is controlled so that the combustion air flow rate of the target value b flows.
The correspondence between the combustion rate and the flow rate of combustion air is preferably a linear function. If the combustion rate is a linear function, the relationship between the combustion rate and the frequency input to the inverter 41 that controls the rotation speed of the motor of the blower 40 is also a linear function, and thus the control of the inverter 41 corresponding to the set combustion rate is performed. Can be done easily.

FIG. 10 is a diagram showing a correspondence relationship between the combustion air flow rate and the exhaust gas recirculation flow rate/EGR rate. The EGR rate can be uniquely calculated by the exhaust gas recirculation flow rate with respect to the combustion air amount shown in FIG. In step S16, a target exhaust gas recirculation flow rate is set based on the combustion air flow rate detected in steps S13 to S14 and the correspondence shown in FIG. , The damper 51 is controlled. For example, when the value of the detected combustion air flow rate is b, the exhaust gas recirculation flow rate is controlled by the damper 51 so that the exhaust gas recirculation flow rate becomes b′.
The correspondence relationship between the combustion air flow rate and the exhaust gas recirculation flow rate is preferably a linear function. If it is a linear function, the exhaust gas recirculation flow rate corresponding to the detected combustion air flow rate and the subsequent control of the damper 51 can be easily performed.
Here, the correspondence relationship between the combustion rate and the combustion air flow rate is a linear function as shown in FIG. 9, and the correspondence relationship between the combustion air flow rate and the exhaust gas recirculation flow rate is also shown in FIG. When the above is a linear function, the correspondence between the combustion rate and the exhaust gas recirculation flow rate is also a linear function.
In addition, when the correspondence between the combustion rate and the exhaust gas recirculation flow rate is a linear function, the variation of the oxygen concentration and/or the NOx concentration in the exhaust gas is substantially within the allowable range. Including the case that can be approximated by a linear function.

As shown in FIG. 10, the correspondence relationship between the combustion air flow rate and the EGR rate is such that the lower the combustion air flow rate, the higher the EGR rate. Here, as for the relationship between the combustion rate and the combustion air flow rate, as shown in FIG. 9, the higher the combustion rate, the higher the combustion air flow rate. Therefore, the correspondence relationship shown in FIG. It can be said that the lower the combustion rate, the higher the EGR rate.

Correspondences as shown in FIGS. 9 and 10, that is, the correspondences among the combustion rate, the combustion air flow rate, the exhaust gas recirculation flow rate, and the EGR rate are stored in the storage unit 208. These correspondences may be stored in a table or as a calculation formula.
For example, when these correspondences are stored in a table, for a predetermined combustion rate (for example, 20%, 60%, 100%), a predetermined combustion air flow rate (for example, when the combustion rate is 20%) is stored. Flow rate a, flow rate b at a burning rate of 60%, flow rate c at a burning rate of 100%), predetermined combustion air flow rate (for example, flow rate a at a burning rate of 20%, and burning rate at a burning rate of 60%) For a flow rate b and a flow rate c at a combustion rate of 100%, a predetermined exhaust gas recirculation flow rate (for example, an exhaust gas recirculation flow rate a′ at a combustion rate of 20%, an exhaust gas recirculation at a combustion rate of 60%). A table in which the flow rate b′ and the exhaust gas recirculation flow rate c′ when the combustion rate is 100% are set may be used. The EGR rate may be calculated from the combustion air flow rate and the exhaust gas recirculation flow rate. In such a case, the exhaust gas recirculation flow rate control unit 207 controls the inverter 41 and the damper 51 according to the correspondence between the combustion rate and the combustion air flow rate, and the combustion air flow rate and the exhaust gas recirculation flow rate, which are predetermined in the table. To do.

Table 1 shows an example in which the relationship between the combustion rate and the combustion air flow rate and the relationship between the combustion air flow rate and the exhaust gas recirculation flow rate are defined in one table. In this table, the combustion air flow rate and the exhaust gas recirculation flow rate are defined so that the EGR rate becomes higher as the combustion rate becomes lower.
By using such a table, the target combustion air flow rate is set according to the set combustion rate, and the target exhaust gas recirculation flow rate is set according to the detected combustion air flow rate. It becomes possible to do.

The correspondence relationship between the combustion rate and the combustion air flow rate, the correspondence relationship between the combustion air flow rate and the exhaust gas recirculation flow rate, and the like are predetermined as calculation formulas such as a linear function and are stored in the storage unit 208. Good.

In the present embodiment, the angle of the damper 51 is controlled so that the EGR rate becomes higher as the combustion rate becomes lower. In addition to this, the air ratio becomes higher as the combustion rate becomes lower. As described above, a configuration for controlling the inverter 41 may be adopted.

Table 2 shows an example of a table in which the combustion air flow rate and the re-exhaust gas circulation flow rate are specified so that the air ratio and the EGR rate become higher as the combustion rate becomes lower.
Even with such a table, the target combustion air flow rate can be set according to the set combustion rate, and the target exhaust gas recirculation flow rate can be set according to the detected combustion air flow rate. It becomes possible to do.

By the control based on such a table, the inverter 41 and the damper 51 are controlled such that the air ratio becomes higher when the combustion rate is lower, and the EGR rate becomes higher when the combustion rate is lower. Is also possible.
The correspondence between the combustion rate and the air ratio may be a linear function. In this case, the calculation of the air ratio corresponding to the instructed combustion rate and the subsequent control of the inverter 41 and the like can be easily performed. Further, the correspondence relationship between the combustion rate and the EGR rate may be a linear function.
As a result, although the EGR rate is high and the oxygen concentration in the combustion air is relatively low as the combustion rate is low, the excess air ratio is in a large state, so that the hydrogen gas is always sufficient for combustion. In such a state that various air is supplied, the combustion state can be more stabilized while suppressing the NOx generation amount in the range from the low combustion state to the high combustion state.

In the setting of the table, the correspondence relationship between the combustion rate and the combustion air flow rate is set to be a linear function relationship, and the correspondence relationship between the combustion rate and the exhaust gas recirculation flow rate is a linear function relationship. May be set as follows. In this case, the air-fuel ratio (air ratio) according to the combustion rate is appropriately adjusted and set so as to maintain this relationship.
Further, in setting the table, the correspondence between the combustion rate and the combustion air flow rate is set to be a linear function, and the correspondence between the combustion rate and the air ratio is a linear function. You may set it. In this case, the EGR rate is appropriately adjusted and set according to the combustion rate so as to maintain this relationship.
In addition, in setting the table, the correspondence between the combustion rate and the air ratio is set to be a linear function, and the correspondence between the combustion rate and the exhaust gas recirculation flow rate is a linear function. It may be set to.

The control unit 200 may be composed of functional blocks as shown in FIG. In the example shown in FIG. 11, the signal branching unit 205 does not exist. In this case, the signal corresponding to the combustion air flow rate averaged by the averaging processing unit 204 is converted into the opening signal of the fuel gas flow rate adjusting valve 91 in the fuel gas flow rate control unit 206, and this opening signal Based on the above, the opening degree of the fuel gas flow rate adjusting valve 91 is adjusted, and this opening degree signal is transmitted to the exhaust gas recirculation flow rate control unit 207. Then, the exhaust gas recirculation flow rate control unit 207 generates a control signal for controlling the opening degree of the damper 51 based on this opening degree signal, and controls the opening degree of the damper 51 based on this control signal.

According to the hydrogen combustion boiler device 1 of the present embodiment described above, the following effects are exhibited in addition to (1) to (7).

(8) The hydrogen combustion boiler device 1 of the present embodiment includes the air differential pressure sensor 31 that detects the flow rate of the combustion air flowing through the air supply passage 30, and the exhaust gas recirculation flow rate control unit 207 uses the air differential pressure sensor 31. The damper 51 is controlled based on the signal corresponding to the detected combustion air flow rate.
Thereby, an appropriate amount of exhaust gas can be circulated in the blower 40 according to the actual flow rate of combustion air. Therefore, even when the flow rate of combustion air is changing, such as when the setting of the combustion rate is changed, it is possible to circulate an appropriate amount of exhaust gas to the blower 40 according to the actual flow rate of combustion air. Therefore, it is possible to realize a stable combustion state and low NOx performance.
Further, according to such control, the exhaust gas recirculation flow rate can be appropriately controlled even in a boiler device of various control systems such as a boiler device of a continuous control system capable of continuously changing the combustion rate.

(9) In the hydrogen combustion boiler device 1 of the present embodiment, the motor of the inverter 41 and the blower 40 that adjusts the flow rate of the combustion air flowing through the air supply passage 30, and the flow rate of the combustion air that controls the motors of the inverter 41 and the blower 40. The combustion air flow rate control unit 202 includes a control unit 202, and the combustion air flow rate control unit 202 has a linear function relationship with the combustion rate, and the inverter 41 and the blower are arranged so that the air ratio becomes higher as the combustion rate becomes lower. Control 40 motors.
As a result, although the EGR rate is high and the oxygen concentration in the combustion air is relatively low as the combustion rate is low, the excess air ratio is in a large state, so that the hydrogen gas is always sufficient for combustion. In such a state that various air is supplied, the combustion state can be more stabilized while suppressing the NOx generation amount in the range from the low combustion state to the high combustion state.

(10) The hydrogen-fired boiler device 1 of the present embodiment includes a storage unit 208 that stores a correspondence relationship among a combustion rate, a combustion air flow rate, and an exhaust gas recirculation flow rate, and a combustion unit that flows through the air supply passage 30. The motor of the inverter 41 and the blower 40 that adjusts the air flow rate, and the combustion air flow rate control unit 202 that controls the motors of the inverter 41 and the blower 40 are provided, and the combustion air flow rate control unit 202 has the set combustion rate. Based on the correspondence between the combustion rate and the combustion air flow rate stored in the storage unit 208, the exhaust recirculation flow rate control unit 207 controls the motors of the inverter 41 and the blower 40. The damper 51 is controlled on the basis of the combustion air flow rate detected by, and the correspondence relationship between the combustion air flow rate and the exhaust gas recirculation flow rate stored in the storage unit 208.
Accordingly, the damper 51 can be appropriately controlled based on the correspondence relationship between each parameter such as the combustion rate, the combustion air flow rate, and the exhaust gas recirculation flow rate.

(11) The hydrogen combustion boiler device 1 of the present embodiment further includes an averaging processing unit 204 that performs averaging processing of the signal of the air differential pressure sensor 31.
By thus performing the averaging process, disturbance such as noise can be reduced and stable control can be performed.

(12) The hydrogen combustion boiler device 1 of the present embodiment is arranged in the fuel gas supply line 90, and the fuel gas flow rate adjusting valve 91 capable of adjusting the fuel gas flow rate and the combustion air detected by the air differential pressure sensor 31. And a fuel gas flow rate control unit 206 that controls the fuel gas flow rate adjustment valve 91 based on a signal corresponding to the flow rate.
As described above, by controlling the fuel gas flow rate in addition to the exhaust gas recirculation flow rate according to the actual combustion air flow rate, a more stable combustion state can be realized.

(13) The hydrogen combustion boiler device 1 of the present embodiment includes the signal branching unit 205 that branches the signal of the air differential pressure sensor 31 into the fuel gas flow rate control unit 206 and the exhaust gas recirculation flow rate control unit 207. The control unit 207 adjusts the opening degree of the damper 51 according to the signal from the air differential pressure sensor 31.
Therefore, since the same signal is branched and used, the error of the signal can be suppressed and the control of the fuel gas flow rate and the exhaust gas recirculation flow rate becomes simple.

(14) In the present embodiment, the fuel gas flow rate control unit 206 converts the signal of the air differential pressure sensor 31 into the opening signal of the fuel gas flow rate adjusting valve 91 and adjusts the fuel gas flow rate based on this opening signal. While adjusting the opening degree of the valve 91, this opening degree signal is transmitted to the exhaust gas recirculation flow rate control section 207, and the exhaust gas recirculation flow rate control section 207 adjusts the opening degree of the damper 51 based on this opening degree signal. ..
Therefore, since the fuel gas flow rate and the exhaust gas recirculation flow rate are controlled based on the same signal, the control becomes simple.

(15) In the present embodiment, the combustion air flow rate stored in the storage unit 208 is set so that the air ratio increases as the combustion rate decreases, and the exhaust gas recirculation flow rate control unit. A control unit 207 controls the damper 51 so that the EGR rate becomes higher as the combustion rate becomes lower, and the combustion air flow rate control unit 202 makes the inverter 41 higher so that the air ratio becomes higher as the combustion rate becomes lower. And controlling the damper of the blower 40.
As a result, as the combustion rate becomes lower, the combustion air in which the exhaust gas and the excess air are added in a high mixing ratio is supplied, so that the fuel gas at a flow rate that is always sufficient for hydrogen gas combustion. The air flows, and the combustion state can be further stabilized in the range from the low combustion state to the high combustion state while suppressing the generation of NOx.

Although the preferred embodiment of the hydrogen-fired boiler device 1 of the present invention has been described above, the present invention is not limited to the above-described embodiment and can be modified as appropriate.

1 Hydrogen Combustion Boiler Device 10 Boiler Main Body 20 Exhaust Channel 30 Air Supply Channel 31 Air Differential Pressure Sensor 40 Blower 41 Inverter 50 Exhaust Gas Recirculation Channel 51 Damper 90 Fuel Gas Supply Line 91 Fuel Gas Flow Rate Control Valve 100, 200 Control Unit 202 For Combustion Air flow rate control unit 203 Combustion air flow rate signal acquisition unit 204 Averaging processing unit 205 Signal branching unit 206 Fuel gas flow rate control unit 207 Exhaust gas recirculation flow rate control unit 208 Storage unit

Claims (10)

A boiler body that burns hydrogen gas as fuel gas to heat the feed water,
A fuel gas supply line for supplying the hydrogen gas to the boiler body;
A combustion air supply line for supplying combustion air to the boiler body,
A blower that is connected to the upstream side of the combustion air supply line and sends combustion air to the combustion air supply line,
An exhaust path for discharging exhaust gas generated by burning fuel in the boiler body,
An exhaust gas recirculation path for circulating a part of the exhaust gas flowing through the exhaust path to the blower,
An exhaust gas recirculation flow rate adjusting unit, which is provided in the exhaust gas recirculation path, for adjusting the exhaust gas recirculation flow rate,
An exhaust gas recirculation flow rate control unit that controls the exhaust gas recirculation flow rate adjustment unit so that the EGR rate becomes higher as the combustion rate becomes lower. The hydrogen combustion boiler device,
In the range of low combustion state to high combustion state, a continuous control boiler device capable of combustion control so that the combustion rate continuously changes,
The hydrogen combustion boiler device according to claim 1, wherein the exhaust gas recirculation flow rate control unit continuously controls the exhaust gas recirculation flow rate adjustment unit so that the EGR rate becomes higher as the combustion rate becomes lower. The hydrogen combustion boiler device,
In the range of low combustion state to high combustion state, it is a step value control boiler device capable of combustion control with a plurality of stepwise combustion rates,
The hydrogen according to claim 1, wherein the exhaust gas recirculation flow rate control unit controls the exhaust gas recirculation flow rate adjustment unit according to a multi-stage combustion state such that the EGR rate becomes higher as the combustion rate becomes lower. Combustion boiler equipment. The exhaust gas recirculation flow rate control unit,
The hydrogen combustion boiler device according to claim 2 or 3, wherein the exhaust gas recirculation flow rate adjusting unit is controlled such that the correspondence relationship between the combustion rate and the exhaust gas recirculation flow rate is a linear function relationship. The hydrogen combustion boiler device,
A combustion air flow rate detection unit that detects the flow rate of combustion air flowing through the combustion air supply line is provided.
The exhaust gas recirculation flow rate control unit controls the exhaust gas recirculation flow rate adjustment unit based on a signal corresponding to the combustion air flow rate detected by the combustion air flow rate detection unit. The hydrogen combustion boiler device according to Item 1. The hydrogen combustion boiler device,
A combustion air flow rate adjusting unit for adjusting the flow rate of combustion air flowing through the combustion air supply line,
And a combustion air flow rate control unit for controlling the combustion air flow rate adjustment unit,
The combustion air flow rate control unit controls the combustion air flow rate adjustment unit so that the correspondence relationship with the combustion rate becomes a linear function relationship, and the air ratio becomes higher as the combustion rate becomes lower. The hydrogen combustion boiler device according to any one of claims 2 to 5. The hydrogen combustion boiler device,
The boiler apparatus according to claim 5, further comprising an averaging processing unit that performs averaging processing of the signal of the combustion air flow rate detection unit. The hydrogen combustion boiler device,
A fuel gas flow rate adjusting unit arranged in the fuel gas supply line and capable of adjusting the fuel gas flow rate,
8. A fuel gas flow rate control unit that controls the fuel gas flow rate adjustment unit based on a signal corresponding to the combustion air flow rate detected by the combustion air flow rate detection unit. Boiler device described. The hydrogen combustion boiler device,
A signal branching unit for branching the signal of the combustion air flow rate detection unit to the fuel gas flow rate control unit and the exhaust gas recirculation flow rate control unit;
The boiler apparatus according to claim 8, wherein the exhaust gas recirculation flow rate control unit adjusts the opening degree of the exhaust gas recirculation flow rate adjustment unit according to a signal from the combustion air flow rate detection unit. The fuel gas flow rate control unit converts a signal from the combustion air flow rate detection unit into an opening degree signal of the fuel gas flow rate adjusting section, and adjusts the opening degree of the fuel gas flow rate adjusting section based on the opening degree signal. , The opening signal is transmitted to the exhaust gas recirculation flow rate control unit,
The boiler device according to claim 8, wherein the exhaust gas recirculation flow rate control unit adjusts the opening degree of the exhaust gas recirculation flow rate adjusting unit based on the opening degree signal.

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