JP2011185510A - Combustion control method and device for boiler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out safe combustion control by adding a state of a temperature of a boiler body to conditions in addition to conventional control of a boiler combustion amount by a steam pressure. <P>SOLUTION: In the combustion control device for a boiler, a steam pressure sensor 4 is provided on an upper header 3 of a water tube 1, the steam pressure sensor 4 and a control panel 5 are connected, an air damper 8 of a duct 7 of a blower 6, a fuel flow control valve 10, and a control motor 11 are connected, and the control motor 11 and the control panel 5 are connected. In a water tube membrane part 12 connecting a water tube and a water tube of the boiler, in a height position of an upper part than half of a water tube length, a temperature sensor 13 is provided, and the temperature sensor 13 and the control panel 5 are connected. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a safe combustion control method and apparatus for a boiler.

  Normally, the combustion control of the boiler is performed by the unit control panel calculating from the steam header pressure state and issuing instructions to each boiler when the pressure state of the boiler itself or when multiple boilers are installed. Each boiler is intermittently controlled such as HI-LOW-OFF or continuously controlled in combustion amount. Conventionally, combustion is only controlled by steam pressure.

On the other hand, the temperature of the boiler body shows various values depending on the combustion state of the boiler and the pressure of the boiler. Moreover, if scales or the like adhere to the boiler, the heat transfer performance is hindered and the main body temperature rises, or the main body temperature rises even when the combustion amount becomes excessive.
As these protection measures, conventionally, boilers are equipped with a device for detecting overheating of the main body. However, its function only shuts off combustion or issues an alarm when temperature is detected, and is not related to combustion control.

JP-A-11-193922

  The problem to be solved is that the combustion control of the boiler cannot be performed safely and continuously.

  In the present invention, by combining the temperature state of the boiler body and the combustion control of the boiler, it is possible to continue combustion in a state before the boiler is in a dangerous state, and to enable early risk prediction. The most important feature.

  In the present invention, in addition to normal boiler combustion control, a temperature sensor is provided in the main body of the boiler (a membrane part that connects the water pipe and the water pipe, that is, a gas seal part of the combustion gas), and the measured value of the sensor is set in advance. When the temperature rises, (1) If the combustion control is step control, shift to a lower combustion amount by one step and fix the combustion amount to the maximum combustion amount. (2) Constant for combustion control continuous control The amount of combustion is reduced at a rate of 5%, and the amount of combustion is set to the maximum amount of combustion, or control is added to set the amount of combustion reaching a preset temperature to the upper limit. Further, when the control in which the control is added to the maximum value of the combustion amount is started as described above, an alarm for notifying this is issued.

  The boiler combustion control method according to the present invention is characterized in that in addition to controlling the combustion amount of the boiler by steam pressure, the combustion state is controlled by adding the temperature state of the boiler body to the conditions. In this method, the temperature of the boiler body is detected at a height above the half of the length of the water pipe in the membrane part that joins the water pipe and the water pipe.

  In these methods, when the temperature of the boiler body reaches a set value, the combustion control is limited. As a limitation of the combustion control, when the combustion control is a step control, the combustion amount is shifted to a lower combustion amount and the combustion amount is fixed to the maximum combustion amount.

  In addition, when the combustion control is continuous control, the combustion control is limited to a method of reducing the combustion amount at a certain rate and fixing the combustion amount to the maximum combustion amount, and the boiler body temperature to a certain set value. One of the methods is to limit the combustion amount when it reaches the upper limit so that the combustion amount does not increase any more. When the above-mentioned combustion control is restricted, an alarm is issued to notify the outside of this. Further, when the temperature of the boiler body reaches the set value again during the restriction of the combustion control, the above operation is performed again.

  The boiler combustion control apparatus of the present invention is provided with a steam sensor in the boiler body, connects the steam sensor and the control panel, connects an air damper and a fuel metering valve of the duct of the blower, and a control motor. In the combustion control device for a boiler in which a motor and the control panel are connected, a temperature sensor is provided at a height above the half of the length of the water pipe at the membrane part that connects the water pipe and the water pipe of the boiler. And the control panel are connected. In this case, the height position above the half of the water pipe length is set to be within 150 mm from the lower surface of the upper header.

  Since the method and apparatus of the present invention combine the temperature state of the boiler body and the combustion control of the boiler by the steam pressure, it is possible to stably continue combustion in a state before the boiler becomes dangerous. There is an advantage that early danger prediction is possible.

FIG. 1 shows an example of a combustion control device for a boiler according to the present invention, and is a configuration explanatory diagram in the case of continuous combustion control. 2 is an enlarged cross-sectional view taken along line AA in FIG. FIG. 3 is a diagram showing the relationship between the main body temperature and the boiler load combustion amount. FIG. 4 is an explanatory diagram of a main part in the case of multistage combustion control (Hi-Low combustion control).

  The objective of continuously and stably controlling the combustion of the boiler was realized by adding control based on the temperature of the boiler body to the combustion control of the boiler using steam pressure.

  FIG. 1 is an explanatory view of the configuration of an embodiment of a boiler combustion control apparatus according to the present invention, and shows a case of continuous combustion control. FIG. 2 shows a cross section taken along line AA in FIG.

  As shown in FIGS. 1 and 2, the apparatus of this example is provided with a steam pressure sensor 4 in the boiler body, for example, the inlet pipe of the steam separator 20, and this steam pressure sensor 4 and the control panel 5 are connected. In the conventional boiler combustion control apparatus in which the air damper 8 and the fuel metering valve 10 of the duct 7 of the blower 6 and the fuel metering valve 10 are connected to the control motor 11 and the control motor 11 and the control panel 5 are connected to each other, A temperature sensor 13 is provided at a height position above the half of the length of the water pipe in the water pipe membrane portion 12 that connects 1 and the water pipe, and the temperature sensor 13 and the control panel 5 are connected. 14 is a furnace, 15 is a lower header, 16 is a membrane, 17 is a fuel supply pipe, 18 is a burner, and 20 is a steam separator. Steam is taken out from the steam separator 20.

In the apparatus configured as described above, the temperature sensor 13 is attached within 150 mm (below) from the lower surface of the upper header 3.
Since the upper part of the water pipe has a large proportion of steam occupying the pipe, the scale component that becomes an obstacle to heat transfer is likely to adhere to the upper part of the water pipe, and overheating of the main body due to insufficient water supply occurs faster than the lower part. In particular, within 150 mm from the lower surface of the upper header 3, there is an advantage that overheating of the main body can be detected quickly.

  In the apparatus configured as described above, in addition to controlling the combustion amount of the boiler by the steam pressure detected by the pressure sensor 4, the combustion state is controlled by adding the temperature state of the boiler body by the temperature sensor 13 to the condition. As described above, the temperature of the boiler body is detected by the temperature sensor 13 at a height above the half of the length of the water pipe in the water pipe membrane portion 12 that connects the water pipe 1 and the water pipe. When the temperature of the boiler body reaches a set value, the combustion control is limited.

  As the restriction of the combustion control, when the combustion control is continuous control, the combustion amount is reduced at a certain rate and the combustion amount is fixed to the maximum combustion amount, or as shown in FIG. The upper limit is the amount of combustion when the temperature reaches a certain set value, and a limit is given so that the amount of combustion does not increase any further.

  When the above-mentioned combustion control is restricted, an alarm is issued to notify the outside of this. Further, when the temperature of the temperature sensor 13 of the boiler body reaches the set value again during the restriction of the combustion control, the above operation is performed again.

  FIG. 4 is an explanatory diagram of another embodiment of the apparatus of the present invention, and shows a case of multistage combustion control (Hi-Low combustion control). 21 is a fuel flow control valve, and 22 is an orifice. As a restriction of the combustion control in the stage control of this example, the combustion amount is shifted to one step lower and the combustion amount is fixed to the maximum combustion amount. Other configurations and operations are the same as those in FIGS. 1 and 2.

  While boiler combustion control can be continued stably, the early danger prediction of a boiler is attained and the safety | security of boiler combustion control can be improved.

DESCRIPTION OF SYMBOLS 1 Water pipe 3 Upper header 4 Steam pressure sensor 5 Control panel 6 Blower 7 Duct 8 Air damper 10 Fuel metering valve 11 Control motor 12 Water pipe membrane part 13 Temperature sensor 14 Furnace 15 Lower header 16 Membrane 17 Fuel supply pipe 18 Burner 20 Air water Separator 21 Fuel flow control valve 22 Orifice

Claims (9)

  A combustion control method for a boiler, characterized by controlling combustion by adding the state of the temperature of the boiler body to a condition in addition to controlling the combustion amount of the boiler by steam pressure.   The boiler combustion control method according to claim 1, wherein the temperature of the boiler body is detected at a height position above a half of the length of the water pipe in the membrane portion that joins the water pipe and the water pipe.   The boiler combustion control method according to claim 1, wherein when the temperature of the boiler body reaches a set value, the combustion control is limited.   4. The boiler combustion control method according to claim 3, wherein when the combustion control is stage control, the combustion control is shifted to a lower combustion amount and the combustion amount is fixed to the maximum combustion amount.   As a limitation of combustion control, when the combustion control is continuous control, the combustion amount is reduced at a certain rate and the combustion amount is fixed to the maximum combustion amount, and the boiler body temperature reaches a certain set value. 4. The boiler combustion control method according to claim 3, wherein the combustion amount control method is any one of a method for limiting an amount of combustion at the upper limit and preventing a combustion amount from increasing further.   The boiler combustion control method according to any one of claims 3, 4 and 5, wherein when a restriction is imposed on the combustion control, an alarm is issued in order to notify the outside.   A boiler combustion control method for performing the operation according to claim 2 or 3 again when the temperature of the boiler body reaches a set value again during the restriction of the combustion control.   A steam pressure sensor is installed in the boiler body, this steam pressure sensor and the control panel are connected, the air damper of the blower duct and the fuel metering valve are connected to the control motor, and this control motor is connected to the control panel. In the boiler combustion control device, the membrane part that connects the water pipe and the water pipe of the boiler is provided with a temperature sensor at a height higher than half the length of the water pipe, and the temperature sensor and the control panel are connected. A boiler combustion control apparatus characterized by the above.   The boiler combustion control apparatus according to claim 8, wherein a height position above half of the water pipe length is within 150 mm from a lower surface of the upper header.

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