WO2014178409A1

WO2014178409A1 - Boiler

Info

Publication number: WO2014178409A1
Application number: PCT/JP2014/062012
Authority: WO
Inventors: 航伊東; 浩二三浦; 裕明池内
Original assignee: 三浦工業株式会社
Priority date: 2013-05-01
Filing date: 2014-04-30
Publication date: 2014-11-06
Also published as: JP6003792B2; JP2014219120A

Abstract

The purpose of the present invention is to provide a boiler capable of inhibiting deviation between the combustion-air supply amount and the fuel supply amount, while stabilizing control of the fuel supply amount, during changes in the combustion-air supply amount. Accordingly, a boiler (1), which changes a fuel supply amount in accordance with a combustion-air supply amount, is provided with a controller (71) which controls the fuel supply amount using weighted moving average values obtained by imparting, to the combustion-air supply amount within a prescribed time period, weights commensurate with proximity to the present. It is preferable that the controller (71) change the weights imparted to the combustion-air supply amount, in accordance with changes in the combustion-air supply amount.

Description

boiler

The present invention relates to a boiler. More specifically, the present invention relates to a boiler that can suppress the occurrence of deviation between the supply amount of combustion air and the fuel supply amount. This application claims priority based on Japanese Patent Application No. 2013-096666 filed in Japan on May 1, 2013, the contents of which are incorporated herein by reference.

Conventionally, in a boiler that includes a burner that burns fuel, a fuel supply device that supplies fuel to the burner, and a blower that supplies combustion air to the burner and is burned in a plurality of combustion states (combustion rates) The amount of air required for combustion differs depending on the combustion rate. Therefore, the blower includes a fan, a motor that rotates the fan, and an inverter that varies the drive (rotation speed) of the motor, and increases or decreases the rotation speed of the motor (fan) according to the combustion rate. Thus, a technique for supplying an appropriate amount of combustion air to the burner is used.

In such a boiler, a technique for controlling the amount of fuel supplied to the burner according to the amount of combustion air supplied to the burner is used (for example, refer to Patent Document 1). Specifically, as the amount of combustion air supplied to the burner, the air pressure in the air supply duct connected from the blower to the burner is detected by a sensor, and the fuel supply amount to the burner is controlled according to the detection result Is done. However, when the wind pressure or the like in the air supply duct is detected by a sensor, the detected value tends to vary and is not stable.

Therefore, by using the moving average value of the value detected by the sensor for the control, it becomes possible to control the fuel supply amount to the burner with a stable value with little variation.

JP-A-8-178271

However, as described above, when the moving average value of the value detected by the sensor is used for the control of the fuel supply amount, the change in the fuel supply amount with respect to the large change in the amount of combustion air supplied to the burner. Is delayed. That is, when the amount of combustion air supplied to the burner changes significantly due to fluctuations in the target load of the vapor pressure, etc., the fuel supply amount to the burner is the past of the period during which the moving average value is calculated. Delay is caused by the value. In this case, a deviation occurs in the ratio (air-fuel ratio) between the amount of combustion air supplied to the burner and the fuel supply amount.

Therefore, the present invention provides a boiler capable of suppressing the occurrence of a deviation between the supply amount of combustion air and the fuel supply amount while stabilizing the control of the fuel supply amount against changes in the supply amount of combustion air. The purpose is to provide.

The present invention is a boiler that changes the supply amount of fuel in accordance with the supply amount of combustion air, and is obtained by assigning a greater weight to the supply amount of combustion air within a predetermined period as it is closer to the present time. It is related with a boiler provided with the control part which controls the supply_amount | feed_rate of the said fuel by the weighted moving average value to be performed.

Further, it is preferable that the control unit changes a weight given to the supply amount of the combustion air according to a change in the supply amount of the combustion air.

Further, it is preferable that the control unit changes the length of the predetermined period for obtaining the weighted average value according to a change in the supply amount of the combustion air.

Further, it is preferable that the control unit controls the fuel supply amount using a weighted moving average value as the weighted moving average value.

Further, it is preferable that the control unit controls the fuel supply amount using an exponential moving average value as the weighted moving average value.

According to the boiler of the present invention, it is possible to suppress the occurrence of a deviation between the supply amount of the combustion air and the fuel supply amount while stabilizing the control of the fuel supply amount with respect to the change in the supply amount of the combustion air. .

It is a figure showing typically one embodiment of the boiler of the present invention. FIG. 6 is a schematic diagram showing a comparison of the response of the vapor pressure to the fluctuation of the target load when the fuel gas supply amount is controlled using various moving average values of the wind pressure in the air supply duct 30.

Hereinafter, a preferred embodiment of a 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 generates steam by heating water. As shown in FIG. 1, the boiler 1 includes a can body 10, a blower 20 that sends combustion air to the can body 10, and an air supply duct 30 that connects the can body 10 and the blower 20 and through which combustion air flows. A damper 40 disposed in the air supply duct 30, a fuel supply device 50 that supplies fuel gas to the air supply duct 30, an exhaust pipe 60 through which the combustion gas discharged from the can body 10 circulates, and the can body 10 A water supply path (not shown) for supplying water to the boiler, a control device 70 for controlling the combustion state of the boiler 1, a vapor pressure sensor 80 for detecting the vapor pressure in the upper header 14, and a damper in the supply duct 30 40, a wind pressure sensor 90 for detecting the wind pressure at the downstream position.

As shown in FIG. 1, the can 10 includes a boiler housing 11, a plurality of water pipes 12, a lower header 13, an upper header 14, and a burner 15.
The boiler housing | casing 11 comprises the external shape of the can 10, and is formed in the rectangular parallelepiped shape of planar view. An air supply port 16 is formed in the first side surface 11a located on one end side in the longitudinal direction of the boiler casing 11, and a second side surface 11b located on the other end side in the longitudinal direction of the boiler casing 11 is An exhaust port 17 is formed.

The plurality of water pipes 12 are disposed so as to extend in the vertical direction inside the boiler housing 11 and are disposed at predetermined intervals in the longitudinal direction and the width direction of the boiler housing 11.
The lower header 13 is disposed at the lower part of the boiler casing 11. The lower header 13 is connected to the lower ends of the plurality of water pipes 12.

The upper header 14 is disposed on the upper portion of the boiler casing 11. The upper header 14 is connected to the upper ends of the plurality of water pipes 12.
The burner 15 is disposed in the air supply port 16.

The blower 20 includes a blower body 21 having a fan and a motor that rotates the fan, and an inverter 22 that increases or decreases the number of rotations of the fan (motor). The blower 20 feeds combustion air into the can body 10 when the fan rotates at a predetermined rotation speed in accordance with the frequency input to the inverter 22.

The air supply duct 30 has an upstream end connected to the blower 20 and a downstream end connected to the air supply port 18. The air supply duct 30 supplies the combustion air sent from the blower 20 to the can body 10.
The damper 40 is in a closed state in which the combustion air flow path inside the air supply duct 30 is closed and rotated 90 degrees from this closed state to open the combustion air flow path in the air supply duct 30. It is arranged to be rotatable between states.

The fuel supply device 50 includes a gas supply line 51, and an adjustment valve 52 and a nozzle 53 provided in the gas supply line.
The gas supply line 51 is connected to the downstream side of the air supply duct 30 from the position where the damper 40 is disposed, and supplies the fuel gas to the air supply duct 30.
The adjustment valve 52 adjusts the flow rate of the fuel gas supplied to the air supply duct 30.
The nozzle 53 is disposed at the tip of the gas supply line 51 and ejects fuel gas into the air supply duct 30.

The exhaust tube 60 is connected to the exhaust port 17. The exhaust cylinder 60 discharges the combustion gas generated by the combustion of the fuel gas inside the can 10.
The control device 70 controls the combustion state (combustion rate) of the boiler 1 by adjusting the supply amount of combustion air and the supply amount of fuel gas to the can body 10 and adjusts the amount of steam generated by the boiler 1. To do.
The vapor pressure sensor 80 detects the vapor pressure in the upper header 14 and outputs the detection result to the control device 70.
The wind pressure sensor 90 detects the wind pressure at the downstream position of the damper 40 in the air supply duct 30 and outputs the detection result to the control device 70.

According to the boiler 1 described above, the combustion air fed into the air supply duct 30 by the blower 20 is mixed with the fuel gas supplied from the gas supply line 51, and the mixed gas of the fuel gas and the combustion air is burned. 15 is injected into the inside of the can 10 and burned. And the water supplied with the combustion of the mixed gas by the burner 15 heats the water supplied from the lower header 13 to the inside of the plurality of water pipes 12, and generates steam. The steam generated in the plurality of water pipes 12 is collected in the upper header 14 and then led to the outside through a steam outlet pipe (not shown). Further, the combustion gas generated by the combustion of the mixed gas is discharged from the exhaust cylinder 60 to the outside.

Next, details of control of the combustion state of the boiler 1 by the control device 70 will be described.
In this embodiment, the boiler 1 is comprised by the proportional control boiler which can change a combustion rate continuously. The proportional control boiler is a boiler in which the combustion rate can be continuously controlled at least in the range from the minimum combustion state (for example, the combustion state at a combustion rate of 20% of the maximum combustion amount) to the maximum combustion state. .

In this embodiment, the change of the combustion rate between the combustion stop state of the boiler 1 and the minimum combustion state is controlled by turning on / off the combustion of the boiler 1 (burner). In the range from the minimum combustion state to the maximum combustion state, the combustion rate can be controlled continuously.
In the following, control of the combustion state in the boiler 1 in which the combustion rate can be continuously changed in the range of 20% to 100% will be described.

The controller 70 changes the combustion rate of the boiler 1 and adjusts the amount of steam generated according to the amount of steam consumed by the load equipment to which the boiler 1 supplies steam. The control device 70 includes a control unit 71 and a storage unit 72.

The control unit 71 increases or decreases the rotational speed of the fan of the blower 20 by increasing or decreasing the frequency input to the inverter 22, and controls the amount of combustion air fed into the air supply duct 30. In addition, the control unit 71 controls the amount of combustion air flowing through the air supply duct 30 toward the burner 15 by controlling the opening degree of the damper 40. Further, the control unit 71 controls the amount of fuel gas supplied to the burner 15 by controlling the opening of the adjustment valve 52.

The storage unit 72 opens the damper 40 according to the content of the instruction given to the boiler 1 under the control of the control unit 71, information such as the combustion state of the boiler 1, and the combustion state (combustion rate) of the boiler 1. The setting of the wind pressure value detected by the wind pressure sensor 90 in the past predetermined period, the weighted moving average value calculated from the wind pressure value in the past predetermined period, the frequency input to the inverter, and the opening of the adjustment valve 52 Store information and so on.

Here, in the proportional control boiler, in order to continuously change the combustion rate while maintaining a stable combustion state in the range from the minimum combustion state to the maximum combustion state, the supply amount of combustion air and the amount of fuel gas It is also necessary to continuously change the supply amount.
Regarding the supply of combustion air, the control unit 71 determines the supply amount of combustion air based on the vapor pressure in the upper header 14 detected by the vapor pressure sensor 80.

On the other hand, regarding the supply of the fuel gas, the control unit 71 determines the supply amount of the fuel gas based on the wind pressure in the air supply duct 30 detected by the wind pressure sensor 90. At this time, the value of the wind pressure in the air supply duct 30 detected by the wind pressure sensor 90 tends to be unstable and unstable. Therefore, it is possible to calculate the moving average value of the wind pressure value within the past predetermined period (for example, the past several seconds) by the control unit 71, and to determine the supply amount of the fuel gas based on this moving average value. However, if the simple moving average value is used as the moving average value of the wind pressure value within a predetermined period in the past, the moving average value when the supply amount of combustion air changes greatly due to fluctuations in the target load of the vapor pressure, etc. Because of the influence of the past value of the predetermined period for calculating the fuel gas, there is a delay until the fuel gas supply amount changes corresponding to the change.

Therefore, in this embodiment, as a moving average value of wind pressure values within a predetermined period in the past (for example, the past several seconds), a weighted moving average obtained by assigning a larger weight closer to the present time than a simple moving average value. A value is calculated, and the supply amount of the fuel gas is controlled based on the weighted moving average value.

Specifically, the control unit 71 acquires the vapor pressure in the upper header 14 detected by the vapor pressure sensor 80, and calculates the amount of combustion air necessary to control this vapor pressure to the target load. . Further, the controller 71 increases or decreases the rotation speed of the fan of the blower 20 or controls the opening degree of the damper 40 by increasing or decreasing the frequency input to the inverter 22 based on the calculated amount of combustion air. Thus, the amount of combustion air fed into the air supply duct 30 is controlled.

Further, the control unit 71 acquires the value of the wind pressure in the air supply duct 30 detected by the wind pressure sensor 90, and calculates the weighted moving average value of the wind pressure value within the past predetermined period (for example, the past several seconds). . In the present embodiment, as the weighted moving average value, a weighted moving average value obtained by assigning a larger weight as it is closer to the present time is used. For example, as the weighted moving average value, it is possible to use a weighted moving average value that gives a linearly larger weight to the wind pressure value in the past predetermined period to obtain a moving average value as it gets closer to the present.

In addition, as the weighted moving average value, an exponential moving average value that gives a moving average value by assigning an exponentially larger weight to the wind pressure value in the past predetermined period can be used. When an exponential moving average value is used as the weighted moving average value, the supply amount of the fuel gas can be changed with a smaller delay with respect to the change in the target load of the vapor pressure.
Further, the control unit 71 controls the supply amount of the fuel gas to the burner 15 by controlling the opening degree of the adjustment valve 52 based on the weighted moving average value of the wind pressure values in the past predetermined period.

Thereby, when the supply amount of fuel gas is controlled based on the detected value of the wind pressure in the air supply duct 30 by the wind pressure sensor 90, the moving average value (specifically, the weighted moving average value) of the detected value is used. Therefore, control can be performed based on a stable value with little variation. In addition, when the detected value of the wind pressure in the air supply duct 30 by the wind pressure sensor 90 is greatly changed (that is, when the supply amount of combustion air is greatly changed), it is obtained by assigning a larger weight to the current value. By using the weighted moving average value, it is possible to change the supply amount of the fuel gas more quickly in response to the change.

FIG. 2 is a schematic diagram showing a comparison of the response of the vapor pressure to the change in the target load when the supply amount of the fuel gas is controlled using various moving average values of the wind pressure in the air supply duct 30.
In FIG. 2, the solid line is the target load, the broken line is the vapor pressure when using the simple moving average value, the dashed line is the vapor pressure when using the weighted moving average value, and the two-dot chain line is the exponential moving average value. It shows the vapor pressure when

As shown in FIG. 2, in the boiler 1 of the present embodiment, the detected value of the wind pressure in the air supply duct 30 detected within the past predetermined period (within the moving average period indicated by the double arrow in FIG. 2). Thus, the weighted moving average value is calculated, and the fuel gas supply amount is controlled based on the weighted moving average value.
In FIG. 2, the target load does not fluctuate before time T0. In this case, the supply amount of the combustion gas is the same regardless of whether the simple moving average value, the weighted moving average value, or the exponential moving average value is used. Be controlled.

On the other hand, when the target load starts to increase at time T0, the actual vapor pressure is delayed with respect to the change in the target load.
At this time, in the case of using the simple moving average value, the weighted moving average value, and the exponential moving average value, the vapor pressure in the case of the simple moving average value indicated by the broken line has the largest delay with respect to the target load. .

On the other hand, the vapor pressure in the case of the weighted moving average value indicated by the one-dot chain line and the exponential moving average value indicated by the two-dot chain line has a smaller delay with respect to the target load than the vapor pressure in the case of the simple moving average value. In addition, comparing the vapor pressure in the case of the weighted moving average value and the vapor pressure in the case of the exponential moving average value, the vapor pressure in the case of the exponential moving average value is better than the vapor pressure in the case of the weighted moving average value. The delay with respect to the target load is small.

As described above, in the boiler 1 of the present embodiment, even when the supply amount of combustion air changes greatly, the delay in the change in the supply amount of fuel gas is smaller than that in the conventional technology. ing.
Accordingly, it is possible to suppress a situation in which a deviation occurs in the ratio between the combustion air and the fuel gas (air-fuel ratio).
That is, according to the boiler 1 of the present embodiment, a deviation between the supply amount of the combustion air and the fuel supply amount occurs while stabilizing the control of the fuel supply amount with respect to the change in the supply amount of the combustion air. This can be suppressed.

As mentioned above, although one preferable embodiment of the boiler of this invention was described, this invention is not restrict | limited to embodiment mentioned above, It can change suitably.
For example, in this embodiment, the weighting is fixed when calculating the weighted moving average value obtained by assigning a larger weight to the detected value of the wind pressure in the air supply duct 30 as it is closer to the present. However, it is not limited to this.
That is, the weighting in calculating the weighted moving average value may be changed with respect to the detected value of the wind pressure in the air supply duct 30. Specifically, when the fluctuation of the wind pressure in the past predetermined period is smaller than the threshold, the inclination of weighting is made smaller, and when the fluctuation of the wind pressure is larger than the threshold, the inclination of weighting is made larger. It is possible.

Further, in the present embodiment, when calculating a weighted moving average value obtained by assigning a greater weight to the detected value of the wind pressure in the air supply duct 30 as it is closer to the present, the calculation target of the weighted moving average value It is assumed that the length of the predetermined period in the past is fixed, but is not limited thereto.
That is, the length of the past predetermined period to be calculated when calculating the weighted moving average value with respect to the detected value of the wind pressure in the air supply duct 30 may be changed. Specifically, when the fluctuation of the wind pressure in the past predetermined period is smaller than the threshold, the length of the past predetermined period to be calculated is made longer, and when the fluctuation of the wind pressure is larger than the threshold It is possible to make the length of the past predetermined period to be calculated longer.

The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiments or examples are merely examples in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the scope of claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

1 Boiler 15 Burner 20 Blower 40 Damper 71 Control Unit 80 Vapor Pressure Sensor 90 Wind Pressure Sensor

Claims

A boiler that changes the supply amount of fuel according to the supply amount of combustion air,
A boiler provided with a control part which controls the amount of supply of the above-mentioned fuel by the weighted moving average value obtained by assigning a larger weight to the amount of supply of combustion air within a predetermined period as it is closer to the present.
2. The boiler according to claim 1, wherein the control unit changes a weight given to the supply amount of the combustion air according to a change in the supply amount of the combustion air.
The boiler according to claim 1 or 2, wherein the control unit changes a length of the predetermined period for obtaining the weighted average value in accordance with a change in a supply amount of the combustion air.
The boiler according to any one of claims 1 to 3, wherein the control unit controls the fuel supply amount using a weighted moving average value as the weighted moving average value.
The boiler according to any one of claims 1 to 3, wherein the control unit controls the fuel supply amount using an exponential moving average value as the weighted moving average value.