JP2009068774A - Method for controlling combustion of fuel gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling combustion of a fuel gas suitably applied when a by-product gas recovered from a coke oven, a blast furnace, a converter and the like and including moisture, is burned. <P>SOLUTION: The substantial amount of fuel gas is obtained by subtracting the moisture as the amount of saturated water vapor at a gas temperature of the fuel gas, from the amount of fuel gas, preferably, the by-product gas, and a theoretical amount of air is determined to the substantial amount of fuel gas. Preferably, the moisture in the fuel gas is the amount of saturated water vapor determined on the basis of an atmospheric air temperature around a combustion furnace. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a fuel gas combustion control method, and more particularly to a fuel gas combustion control method suitable for burning a by-product gas containing moisture from a coke oven, a blast furnace, a converter, or the like.

When fuel gas such as LPG and LNG is burned, the air-fuel ratio (ratio of air and fuel) is set so that optimum combustion is obtained. When the fuel gas 1Nm ³ is completely burned, the ratio of the theoretical air amount TNm ³ obtained by further converting the theoretical oxygen amount into air is the air ratio 1 (theoretical air ratio). Combustion is performed at a ratio of 1.1 to 1.2.

  In combustion control, the air ratio, which is the ratio of the theoretical air volume and the supply air volume that is the theoretical air volume plus the excess air volume, is set appropriately, and complete combustion is performed, but in this case, the moisture contained in the fuel gas is also Including the air ratio is set. LPG, LNG, and the like have little influence because the moisture contained in the fuel gas is extremely low.

  However, when using by-product gas generated from steelworks or waste treatment plants as fuel gas, the amount of moisture contained in the gas is high, and the actual amount of fuel gas is small relative to the apparent flow rate. If the combustion control is performed based on the flow rate, excess air combustion occurs and the combustion efficiency decreases.

  In order to remove moisture from the fuel gas, a cooling and reheating process is required. For large-scale factories such as steelworks, the equipment load is large and moisture removal is not performed. There are many.

Patent Document 1 relates to moisture correction in combustion control, and is optimal by performing moisture correction in which the wet oxygen concentration of oxygen, which is an auxiliary combustion gas having the same function as air, is set to dry oxygen concentration in combustion control of an industrial furnace such as a boiler. Achieving combustion is described.
Japanese Patent Laid-Open No. 3-87513

  By the way, in the steelworks, it is assumed that the amount of fuel used is reduced in the summertime because there is little radiated heat and the sensible heat of the fuel, air, and heated object is small. There are many combustion facilities such as heating furnaces, and it is desired to reduce the amount of fuel gas used by appropriate combustion control corresponding to the summer.

  FIG. 3 shows the amount of fuel used throughout the year for the heating furnace at the steel works. The amount of fuel used in the summer from July to October is higher than the amount of fuel used in the winter from November to March. It should be noted that the amount of heat treatment per month throughout the year is almost constant, and it is recognized that the combustion efficiency in summer is decreasing. FIG. 4 shows the result of arranging the fuel consumption in the same heating furnace at the atmospheric temperature (° C.).

  Therefore, an object of the present invention is to provide a combustion control method for burning by-product gas used in steelworks and the like with good combustion efficiency throughout the year.

The object of the present invention can be achieved by the following means.
1. A method for controlling the combustion of fuel gas in a combustion furnace, wherein the amount of fuel gas is obtained by subtracting the moisture that becomes the amount of saturated water vapor at the gas temperature of the fuel gas to obtain the amount of actual fuel gas, and obtained from the amount of actual fuel gas. A combustion control method for fuel gas, wherein combustion control is performed using the theoretical air amount.
2.1. The fuel gas combustion control method according to 2.1, wherein the moisture content in the fuel gas is a saturated water vapor amount obtained by using the atmospheric temperature around the combustion furnace.
3. 3. The fuel gas combustion control method according to 1 or 2, wherein the fuel gas is a by-product gas.

  ADVANTAGE OF THE INVENTION According to this invention, in the combustion control of the steel furnace industrial furnace which uses by-product gas as fuel gas, appropriate combustion control is attained throughout the year, and it is prevented that the amount of fuel gas used in summer is higher than that in winter. It is extremely useful in industry.

  In the present invention, in combustion control of a combustion furnace that uses a gas containing moisture such as a by-product gas as a fuel gas, the moisture is subtracted from the fuel gas amount to obtain a real fuel gas amount, and an air amount relative to the real fuel gas amount. It is characterized by setting.

  In the combustion furnace, the combustion load is automatically adjusted to reach the target temperature, and the flow rate of air is proportionally calculated with respect to the flow rate of fuel gas.

  Hereinafter, the present invention will be described with reference to examples. FIG. 2 shows an example of a combustion control flow of the heating furnace 1. The furnace temperature of the heating furnace 1 is measured by the furnace thermometer T1 and input to the temperature controller (TIC1) 3, which is necessary for achieving the target furnace temperature. The target fuel gas amount is controlled by a fuel gas flow rate controller (FIC2) 4.

  Based on the output from (TIC1) 3 so as to achieve the target furnace temperature, the output of the fuel gas flow rate controller (FIC2) 4 is adjusted so that the fuel gas flow rate detected by the fuel gas flow rate sensor 9 matches the target fuel gas flow rate. Based on this, the fuel gas flow control valve 6 is adjusted. The combustion control method according to the present invention is characterized in that the air amount is set by correcting the moisture in the fuel gas.

  The air amount is set by the arithmetic controller 5 as follows. First, the fuel gas temperature is regarded as the atmospheric temperature T2 around the furnace, the saturated water vapor amount at the atmospheric temperature T2 is set as the moisture amount, and the moisture amount is subtracted from the fuel gas amount detected by the fuel gas flow rate sensor 9 to obtain a substantial fuel gas. The theoretical air amount is obtained with respect to the actual fuel gas amount.

  An air ratio, which is the ratio of the theoretical air amount obtained by the arithmetic controller 5 and the supplied air amount obtained by adding the excess air amount to the theoretical air amount, is set to a desired value by the ratio setter (R1) 11, and the air The air flow rate adjustment valve 7 is adjusted by the supply air flow rate controller (FIC3) 10 so that the supply air amount detected by the flow rate sensor 8 becomes the supply air amount that satisfies the set air ratio.

  FIG. 1 is a diagram for explaining the structure of a by-product gas used as a fuel gas. A by-product gas (fuel gas) G having a certain measurement flow rate includes a real fuel gas (actual gas G ′), moisture (water vapor), and The sum of expansion due to temperature correction is used, and moisture (water vapor) is the amount of saturated water vapor at the gas temperature of the by-product gas.

  However, when the by-product gas is heated, such as in summer, when the by-product gas is fed from the coke oven or the like of the source to the combustion furnace 1 through a steel gas pipe laid on the ground surface, Even when the temperature is high, moisture is not replenished in the gas pipe, so that moisture in the by-product gas may not be saturated.

  FIG. 5 shows the relationship between the amount of moisture in the gas (saturated water vapor amount) and the gas temperature. When the gas temperature becomes high, the amount of moisture in the gas (saturated water vapor amount) also increases. In the summer, when the by-product gas sent by the steel gas pipe laid on the ground surface is burned in the combustion furnace, the by-product gas is heated by the solar heat in the steel gas pipe and becomes hotter than the production time, Moisture is not replenished in the steel gas pipe.

  In such a case, if the moisture in the by-product gas is the amount of saturated water vapor at the temperature of the by-product gas in the steel gas pipe, the value is greater than the actual value.

  For example, when a by-product gas generated at 20 ° C. is heated to 40 ° C. in a steel gas pipe, the amount of saturated water vapor is apparently increased by 5.3%. In practice, since water is not replenished, the amount of saturated water vapor in the byproduct gas heated to 40 ° C. remains at the value at 20 ° C.

  Therefore, when the amount of real fuel gas in the by-product gas is calculated by subtracting the saturated water vapor amount from the measured flow rate of the by-product gas in summer, saturation at the temperature when the by-product gas is generated, for example, the atmospheric temperature around the combustion furnace Use of the water vapor amount is preferable because more appropriate combustion control is possible. Examples of by-product gas include blast furnace gas, coke oven gas, converter gas, mixed gas thereof, and gas generated from a waste incinerator.

  In the above description, the fuel gas has been described as a by-product gas. However, the present invention can provide an effect as long as the fuel gas contains moisture, and the fuel gas is not limited to the by-product gas.

The figure which shows one structure of byproduct gas (fuel gas). The combustion control flowchart of the heating furnace in this invention. The figure which shows the change of an annual fuel consumption. The figure which shows the influence of the atmospheric temperature on fuel consumption. The figure which shows the relationship between saturated water vapor amount and atmospheric temperature.

Explanation of symbols

1 Heating furnace 3 Temperature controller (TIC1)
4 Fuel gas flow controller (FIC2)
5 Arithmetic Controller 6 Fuel Gas Flow Control Valve 7 Air Flow Control Valve 8 Air Flow Sensor 9 Fuel Gas Flow Sensor 10 Supply Air Flow Controller 11 Air Ratio Ratio Setter (R1)
T1 Furnace thermometer T2 Atmospheric temperature

Claims (3)

  A method for controlling the combustion of fuel gas in a combustion furnace, wherein the amount of fuel gas is obtained by subtracting the moisture that becomes the amount of saturated water vapor at the gas temperature of the fuel gas to obtain the amount of actual fuel gas, and obtained from the amount of actual fuel gas. A combustion control method for fuel gas, wherein combustion control is performed using the theoretical air amount.   2. The fuel gas combustion control method according to claim 1, wherein a moisture content in the fuel gas is set to a saturated water vapor amount obtained by using an atmospheric temperature around the combustion furnace.   3. The fuel gas combustion control method according to claim 1, wherein the fuel gas is a by-product gas.

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