JP2006348063A - Method for controlling combustion of coke oven - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling combustion of a coke oven in which an excess ratio to a theoretical amount of air can be reduced to the utmost while preventing incomplete combustion in a combustion chamber even in the coke oven controlled so that the amounts of a combustion gas and a combustion air fed into the combustion chamber become a definite ratio. <P>SOLUTION: In the combustion control method in the coke oven controlled so that the amount of the combustion gas and the amount of the combustion air fed into the combustion chamber become a definite ratio, a mixed ratio of a plurality of kinds of fuel gases mixed is controlled so that A<SB>0</SB>/γ<SP>1/2</SP>(wherein A<SB>0</SB>: theoretical air amount of the combustion gas; γ: specific gravity of the combustion gas) becomes constant. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a combustion control method for a coke oven, which comprises carbonizing carbon to make coke.

  In a coke oven in which coal is carbonized into coke, combustion chambers and carbonization chambers are alternately arranged, and the combustion chambers and the carbonization chamber are partitioned by a refractory brick partition wall (furnace wall brick). The charcoal chamber is charged with coal loaded on the hopper of the charging vehicle from above. The coal charged into the carbonization chamber is dry-distilled with the combustion heat of the combustion gas in the combustion chambers arranged on both sides of the carbonization chamber to be coke. The carbonized coke is pushed from the side by the extrusion ram of the extruder and discharged from the carbonization chamber.

  Here, as the combustion gas supplied into the combustion chamber, for example, a mixed gas in which blast furnace gas (BFG) and coke oven gas (COG) are mixed is used because it is easily available in an iron factory. There are many cases. The blast furnace gas and coke oven gas are not always constant in calorific value depending on the operating state of the blast furnace or coke oven, and even when the blast furnace gas and coke oven gas are mixed and supplied at a certain ratio, The calorific value of the mixed gas varies.

  For this reason, when control is performed so that combustion air is supplied at a constant ratio to the amount of mixed gas supplied into the combustion chamber, the combustion air is insufficient due to fluctuations in the amount of heat generated in the mixed gas. Incomplete combustion may occur, and as a result, black smoke may be generated. In addition, the amount of combustion air to be supplied is increased by 20 to 50% with respect to the theoretical amount of air so that black smoke is generated due to incomplete combustion of the mixed gas, which is a combustion gas. Was also done. In this case, the amount of exhaust gas discharged from the combustion chamber has increased, and a reduction in thermal efficiency due to exhaust gas loss has been a problem.

  In response to such a problem, for example, in Patent Document 1 (Japanese Patent Laid-Open No. 2002-267157), a heat generation amount of the fuel is detected in the middle of the fuel supply pipe, and the fuel is burned using the heat generation amount. A combustion control method for correcting and controlling the amount of combustion air at the time of combustion is described.

Further, for example, in Patent Document 2 (Japanese Patent No. 2701617), in a combustion control method of a combustion furnace in which two or more kinds of fuel gases are mixed to form a combustion gas, the ratio of carbon and hydrogen in the combustion gas composition is set. Accordingly, there is described a mixed gas combustion control method for changing the excess ratio of the fuel gas to the theoretical air amount and supplying combustion air having an air ratio other than the smoke generation region.
JP 2002-267157 A Japanese Patent No. 2701617

  However, the method described in Patent Document 1 corrects and controls the combustion air amount on the assumption that the calorific value of fuel and the theoretical air amount are proportional to each other. The theoretical air volume also changes. Therefore, even when controlling by the method described in Patent Document 1, there is a problem that the excess ratio of the combustion air must be increased to some extent from the viewpoint of preventing incomplete combustion. Furthermore, in a coke oven in which the amount of combustion gas and combustion air supplied to the combustion chamber is controlled to a constant ratio, only the amount of combustion air is independently determined based on the heat value of the fuel. Therefore, it is difficult to perform correction control.

  In the method described in Patent Document 2, the composition of the combustion gas mixture is obtained from each combustion gas composition and the mixing ratio of each gas, and the ratio of carbon and hydrogen in the combustion gas mixture composition is compared with the theoretical air amount. The excess rate is calculated and the air amount is adjusted. However, for example, the gas mixture of blast furnace gas and coke oven gas is not proportional to the ratio of carbon and hydrogen and the theoretical air volume like heavy hydrocarbons. Since the accuracy of gas flow rate measurement is inferior because of the large difference, the excess air amount must be increased to some extent for safety. Further, as described above, in a general coke oven in which the amount of combustion gas and combustion air supplied into the combustion chamber is controlled to a constant ratio, carbon and hydrogen in the combustion gas composition are controlled. It is difficult to independently control only the excess rate with respect to the theoretical air amount by the ratio.

  Therefore, the present invention prevents incomplete combustion in the combustion chamber even in a coke oven in which the amount of combustion gas and combustion air supplied into the combustion chamber is controlled to a constant ratio. It is another object of the present invention to provide a coke oven combustion control method capable of reducing the excess ratio with respect to the theoretical air amount as much as possible.

In order to solve the above problems, the present invention has the following features.
[1] A combustion control method in a coke oven in which the amount of combustion gas supplied to the combustion chamber of the coke oven and the amount of combustion air are controlled to have a constant ratio,
Regarding the combustion gas produced by mixing a plurality of types of fuel gas,
A ₀ / γ ^1/2 (where A _{0 is} the theoretical air amount of the combustion gas, γ is the gas specific gravity of the combustion gas)
The combustion control method for a coke oven is characterized in that the mixing ratio of a plurality of types of fuel gas to be mixed is adjusted so as to be constant.
[2] The combustion control method for a coke oven according to [1], wherein at least combustion air is supplied into the combustion chamber by natural ventilation.

  According to the present invention, incomplete combustion in a combustion chamber is prevented even in a coke oven in which the amount of combustion gas and combustion air supplied into the combustion chamber is controlled to a constant ratio. A combustion control method for a coke oven that can reduce the excess ratio with respect to the theoretical air amount as much as possible is provided.

  Hereinafter, an example of the best mode for carrying out the present invention will be described.

  FIG. 1 is a schematic configuration diagram illustrating an example of a facility configuration in a coke oven to which a coke oven combustion control method according to the present invention is applied. FIG. 1 shows a case where a mixed gas in which blast furnace gas (BFG) and coke oven gas (COG) are mixed is used as the combustion gas, but the types of fuel gas to be mixed are limited to these. In addition, for example, converter gas (LDG), liquefied petroleum gas (LPG), or the like can be used. Further, the fuel gas to be mixed is not limited to two types, and three or more types of gas may be mixed.

  Hereinafter, the case where the mixed gas which mixed blast furnace gas (BFG) and coke oven gas (COG) is used as combustion gas is demonstrated.

  In the middle of the supply pipe 1a for supplying blast furnace gas (BFG), there are an analysis means 2a for analyzing the gas components of the supplied blast furnace gas, and a flow rate control means 3a for controlling the flow rate of the supplied blast furnace gas. And are provided. Further, in the middle of the supply pipe 1b for supplying the coke oven gas (COG), similarly, an analysis means 2b for analyzing the gas component of the supplied coke oven gas and the flow rate of the supplied coke oven gas are controlled. And a flow rate control means 3b. The blast furnace gas and the coke oven gas are mixed after the flow rate is controlled by the flow rate control means 3a and 3b, respectively, and the mixed gas is mixed into the combustion chamber 5 through the mixed gas supply pipe 1c. Supplied. Here, a flow rate control means 4 is provided in the middle of the mixed gas supply pipe 1 c to control the flow rate supplied into the combustion chamber 5.

  In addition, as said analysis means 2a, 2b, a gas chromatograph analyzer etc. can be used, for example. Further, as the flow rate control means 3a, 3b, 4, a flow rate adjusting valve or the like can be used.

  Further, combustion air is supplied into the combustion chamber 5 through a combustion air supply port 6. Here, the combustion air supplied through the combustion air supply port 6 is supplied at a constant ratio with the flow rate of the mixed gas supplied from the mixed gas supply pipe 1c. As described above, as a method of supplying the combustion air so as to have a constant ratio with the flow rate of the mixed gas supplied into the combustion chamber 5, the mixed gas flow rate and the combustion air flow rate are controlled using the differential pressure. This can be done by using

  That is, at least the combustion air is introduced into the combustion chamber 5 by natural ventilation due to the negative pressure generated by the flow of the high-temperature combustion gas generated by the combustion in the combustion chamber 5, so that the flow rate of the mixed gas is constant. The combustion air flow rate is controlled so that the ratio is as follows. Here, the mixing ratio of the mixed gas and the combustion air is adjusted by adjusting the flow rate in the flow rate control means 4 provided in the middle of the mixed gas supply pipe 1c and the damper 7 provided in the combustion air supply port 6. And the opening degree of the damper 9 provided in the middle of the discharge pipe 8 for discharging the combustion exhaust gas from the combustion chamber 5 can be adjusted. In addition, the combustion exhaust gas discharged | emitted by the discharge piping 8 is discharge | released from the chimney 10 to air | atmosphere.

In such an apparatus configuration, the present invention relates to a combustion gas that is a mixed gas produced by mixing blast furnace gas (BFG) and coke oven gas (COG).
A ₀ / γ ^1/2
Is adjusted so that the mixing ratio of the blast furnace gas (BFG) and the coke oven gas (COG) to be mixed is adjusted.
Here, _{A 0:} stoichiometric air per combustion gases ^{1Nm 3 (Nm 3), γ} : represents the gas density of the combustion gas (kg / Nm ^3).

When the flow rate Qg (Nm ³ / hour) of the combustion gas supplied into the combustion chamber 5 is controlled by a differential pressure type flow meter such as an orifice, the differential pressure is ΔP (Pa), and K is a constant, It is represented by the following formula (1).

Qg = K · ΔP ^1/2 / γ ^1/2 (1)
The theoretical air amount necessary for combustion is the product of the theoretical air amount (Nm ³ ) per combustion gas 1Nm ³ determined by the combustion gas component and the flow rate of the combustion gas, so the theoretical air amount required for combustion is Is represented by the following equation (2).

Qg · A ₀ = K · ΔP ^1/2 / γ ^1/2 · A ₀ = K · A ₀ / γ ^1/2 · ΔP ^1/2 (2)
Here, if A ₀ / γ ^1/2 is controlled to be constant in the above equation (2), the theoretical air amount necessary for combustion is proportional to ΔP ^1/2 , that is, proportional to the combustion gas flow rate Qg. . In other words, when the amount of combustion gas and the amount of combustion air are controlled so as to have a constant ratio, by always controlling A ₀ / γ ^1/2 of the combustion gas to be constant, Combustion control of a coke oven in which the combustion air of the theoretical amount of air is supplied and the amount of combustion gas supplied to the combustion chamber 5 and the amount of combustion air are controlled at a constant ratio. It can be seen that is an optimal combustion control method.

  A method for setting the mixing ratio of the blast furnace gas (BFG) and the coke oven gas (COG) to be mixed will be described below.

Analyzing means 2a for analyzing the gas component of the blast furnace gas (BFG) supplied into the combustion chamber 5 and analysis for analyzing the gas component of the coke oven gas (COG) also supplied into the combustion chamber 5 The analysis result of each gas component from the means 2b is input to the computer 12. The computer 12 calculates the theoretical air amount and gas specific gravity of each gas from the analysis results of the gas components of the blast furnace gas (BFG) and the coke oven gas (COG). The results, set A _{0 /} gamma ^1/2 represented by the gas density of the combustion gases represented by A ₀ and the theoretical air amount A ₀ per combustion gases 1 Nm ³ represented by gamma gamma advance The mixing ratio of the blast furnace gas (BFG) and the coke oven gas (COG) is determined so that the obtained value is obtained.

  The mixing ratio determined by the calculator 12 is input from the calculator 12 to the ratio setting unit 11. In the ratio setting device 11, the flow rate control means 3a for controlling the flow rate of the blast furnace gas (BFG) and the coke oven gas (COG) based on the flow rate measurement signal from the flow rate control means 4 provided in the middle of the mixed gas supply pipe 1c. A signal is sent to the flow rate control means 3b for controlling the flow rate of the blast furnace gas so as to control the flow rates of the blast furnace gas and the coke oven gas to the determined mixing ratio.

Here, the preset value of the above A ₀ / γ ^1/2 is determined based on the supply status of the blast furnace gas (BFG) and coke oven gas (COG) to be mixed, such as the amount of heat, the supply capacity, etc. This value is determined by the required amount of heat of the combustion gas determined by conditions and the like. The determination of the value of A ₀ / γ ^1/2 is performed by, for example, first determining the required amount of heat (kcal / Nm ³ ) in the standard state of the combustion gas that is a mixed gas, and taking into account the properties of the gas to be mixed The determination is made by determining A ₀ / γ ^1/2 of the combustion gas as the amount of heat. Then, the flow rate of each gas to be mixed is adjusted so that the determined value of A ₀ / γ ^1/2 is obtained.

In the present invention, combustion is controlled by controlling the amount of blast furnace gas (BFG) and coke oven gas (COG) to be mixed so that A ₀ / γ ^1/2 of the combustion gas that is a mixed gas is constant. While preventing incomplete combustion in the room, it is possible to reduce the excess rate relative to the theoretical air amount as much as possible. Further, the gas components of the blast furnace gas (BFG) and the coke oven gas (COG) supplied into the combustion chamber 5 are analyzed in real time by the analyzing means 2a and 2b, and the combustion gas A ₀ / Since the mixing amount is controlled so that γ ^1/2 is constant, even when the gas components of the blast furnace gas (BFG) and the coke oven gas (COG) fluctuate, the excess rate relative to the theoretical air amount Can be reduced as much as possible.

  As a result, the amount of combustion exhaust gas can be reduced, exhaust gas loss can be reduced, flame temperature in the combustion chamber can be increased, and thermal efficiency can be improved.

The combustion control method according to the present invention in the case where a mixed gas obtained by mixing blast furnace gas (BFG) and coke oven gas (COG) is used as the combustion gas supplied into the combustion chamber of the coke oven having the configuration shown in FIG. In other words, combustion was performed using a method of controlling the mixing amount of blast furnace gas (BFG) and coke oven gas (COG) to be mixed so that A ₀ / γ ^1/2 of the supplied combustion gas is constant. The change in the excess air ratio was investigated (invention example).

  Component analysis of the supplied blast furnace gas and coke oven gas was performed by a gas chromatograph analyzer at a cycle of 1 minute, and the mixing amount was adjusted, and continuous combustion for 7 hours was performed.

  As a comparative example, in the coke oven configured as shown in FIG. 1, when the amount of heat generated by the fuel is detected in the middle of the fuel supply line described in Patent Document 1, the fuel is burned using the amount of heat generated. When the method of correcting and controlling the amount of combustion air (Comparative Example 1) is used, the excess ratio of the fuel gas to the theoretical air amount is changed according to the ratio of carbon and hydrogen in the combustion gas composition described in Patent Document 2 Then, in the case of using a method of supplying combustion air having an air ratio other than the smoke generation region (Comparative Example 2), 7 hours of continuous combustion was similarly performed.

  As a result of continuous combustion for 7 hours, the excess rate with respect to the theoretical air amount was within 1.5%, whereas in Comparative Example 1, the excess rate with respect to the theoretical air amount was within 2.5%. In Example 2, it was within 2.0%, but in the present invention example, the excess rate with respect to the theoretical air amount was within 1.5%, and it was found that the excess air rate was kept low. It was.

It is a schematic block diagram which shows an example of the equipment structure in the coke oven to which the mixing method of the combustion gas supplied in the combustion chamber of the coke oven which concerns on this invention is applied.

Explanation of symbols

1a, 1b, 1c Supply piping 2a, 2b Analysis means 3a, 3b, 4 Flow rate control means 5 Combustion chamber 6 Combustion air supply port 7, 9 Damper 8 Discharge piping 10 Chimney 11 Ratio setter 12 Calculator

Claims (2)

A combustion control method in a coke oven in which the amount of combustion gas supplied to the combustion chamber of the coke oven and the amount of combustion air are controlled to have a constant ratio,
Regarding the combustion gas produced by mixing a plurality of types of fuel gas,
A ₀ / γ ^1/2 (where A _{0 is} the theoretical air amount of the combustion gas, γ is the gas specific gravity of the combustion gas)
The combustion control method for a coke oven is characterized in that the mixing ratio of a plurality of types of fuel gas to be mixed is adjusted so as to be constant.   The combustion control method for a coke oven according to claim 1, wherein at least combustion air is supplied into the combustion chamber by natural ventilation.

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