A method for controlling the arch top temperature of a basic oxygen furnace melting gas making furnace

Abstract

The application discloses a method for controlling the dome temperature of a smelting gas producer of a cupola furnace, wherein the control range of the dome temperature is 1060-1090 DEG C, the content of CO2 in the cold coal gas is controlled to be between 6% and 9%, the control method adjusts the oxygen flow of a dust burner or an oxygen-coal burner, the temperature is adjusted to rise or fall, the content of CO2 is adjusted to fall or rise, the oxygen flow is adjusted to fall or rise by 100-400 Nm 3 / h, the minimum dome temperature required for cracking volatile components is maintained to be >950 DEG C, the oxygen amount of the dust burner is controlled to be 3500-4000 Nm 3 / h in a normal production state, the oxygen amount of the oxygen-coal burner is controlled to be 7400-7600 Nm 3 / h, and the oxygen flow of the dust burner and the oxygen-coal burner is adjusted by 100-400 m 3 / h every time, and the interval of each adjustment is greater than 1 minute.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for controlling the dome temperature of a smelting gasifier of an EAF. BACKGROUND

[0002] The EAF non-blast furnace ironmaking process is a two-furnace process, consisting of a top reduction shaft furnace and a bottom smelting gasifier. The dome of the smelting gasifier of the EAF is a dome-shaped top, and the center of the dome is a coal distributor. Coal, coke and auxiliary materials, mainly dolomite and silica, are distributed onto the semi-coke bed on the dome of the smelting gasifier through the two-stage coal screw of the coal distributor. Around the coal distributor are eight DRI flap holes. The reduced ore, coke and auxiliary materials in the shaft furnace are twisted into the DRI downcomer by the eight DRI screws, and are distributed to the semi-coke bed of the smelting gasifier by the flap distributor. There are four gas generation pipes and one safety gas pipe outside. The high-temperature generated gas at the dome is output through the gas generation pipe, and the temperature is the dome temperature of 1050-1080℃. After being cooled to 835℃, part of the gas enters the shaft furnace, and part of the gas goes through the excess gas line to control the pressure of the plant.

[0003] The process flow of the EAF gas system is as follows: the pure oxygen burned after being introduced into the tuyere of the smelting gasifier generates gas that rises and undergoes direct reduction and indirect reduction with the charge in the semi-coke bed to reach the dome area for temporary retention. The dome area has four dust burners and four oxygen-coal burners that introduce oxygen to burn above the semi-coke bed in the dome area of the smelting gasifier to increase the dome temperature. The adjustment of the dome temperature can be controlled by increasing or decreasing the oxygen amount of the dust burners and the oxygen-coal burners. At the same time, the dust burners spray the dust collected by the dust return line, mainly ore powder and coal powder, to burn again to reduce the dust content in the entire dome area.

[0004] If the dome temperature is too high, it is easy to cause the liquefaction of ferrous oxide and the condensation of a large amount of dust that can be bonded together to cause the sticking of the gas generation pipe. At the same time, the coal added from the coal distributor is rapidly heated to cause cracking, resulting in the generation of tar and aggravating the sticking of the gas generation pipe. The high temperature also damages the refractory material of the dome and the coal distributor and the DRI flap distributor in the dome. The maximum dome temperature should not exceed 1180℃, otherwise the plant will trip after 8 minutes. SUMMARY

[0005] In order to solve the technical problem of the high dome temperature of the smelting gasifier of the EAF, the present application provides a method for controlling the dome temperature of the smelting gasifier of the EAF, which can control the dome temperature at 1060±30℃ and CH4<4%.

[0006] A method for controlling the dome temperature of the smelting gasifier of the EAF, the specific steps are as follows:

[0007] 1) The control range of the dome temperature is 1060-1090℃, the content of CO2 in the cold coal gas is controlled between 6%-9%, the control method adjusts the oxygen flow of the dust burner or the oxygen coal burner, the temperature is raised or lowered, the content of CO2 is lowered or raised, the oxygen flow is adjusted by 100-400Nm 3 / h;

[0008] 2) The minimum dome temperature required for maintaining the cracking volatile components is >950°C;

[0009] 3) The oxygen flow of the dust burner or the oxygen coal burner is adjusted to control the content of CO2 in the cold coal gas, and the solid carbon powder amount in the dome area is controlled to be sufficient, whether the solid carbon powder amount is sufficient is determined according to the corresponding relationship between the dome temperature and the content of CO2, the dust burner is adjusted according to the change trend of the dome temperature and the content of CO2 in the cold coal gas, the oxygen amount of the dome burner is adjusted according to the change trend of the content of CO2 and the dome temperature, the principle of "opposite adjustment, same direction non-adjustment" is operated, the specific content of CO2 in the cold coal gas and the dome temperature are negatively correlated in general, that is, when the content of CO2 decreases, the dome temperature will rise after a period of lag; when the content of CO2 rises, the dome temperature will also decrease after a period of lag;

[0010] 4) The oxygen amount of the dust burner is controlled at 3500-4000Nm 3 / h in the normal production state, and the oxygen amount of the oxygen coal burner is controlled at 7400-7600Nm 3 / h;

[0011] 5) When the dome temperature is too high, the oxygen amount of the oxygen coal burner is first reduced, then the oxygen amount of the dust burner is reduced, and the nitrogen of the coal distributor is opened in time;

[0012] 6) The oxygen flow of the dust burner and the oxygen coal burner is adjusted by 100-400m 3 / h each time, and the interval of each adjustment is greater than 1 minute.

[0013] The beneficial effects of the present application are:

[0014] The oxygen amount of the dome burner is adjusted according to the change trend of the dome temperature and the content of CO2 in the cold coal gas, the content of CO2 in the coal gas can be stabilized in an ideal interval as the control basis of the dome temperature, the dome temperature is reasonably controlled at 1060-1090℃, and the content of CO2 in the cold coal gas is controlled between 6%-9%. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 Process flow diagram of the present application;

[0016] Wherein, 1, smelting gas furnace; 2, tuyere (28 groups of uniform distribution); 3, dome area; 4, dust burner (4 groups of uniform distribution); 5, oxygen coal burner (4 groups of uniform distribution); 6, coal distributor; 7, DRI flap distributor; 8, shaft furnace; 9, DRI downpipe; 10, four gas generating pipes (4 groups of uniform distribution); 11, cold coal gas; 12, dome thermocouple; 13, hot cyclone thermocouple. Embodiment

[0017] In order to make the personnel in the technical field better understand the present application scheme, the technical scheme in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the scope of protection of the present application.

[0018] In combination Figure 1 As shown in the figure, the present application provides a method for controlling the dome temperature of the smelting gas furnace of the European smelting furnace. The coal gas generated after the pure oxygen combustion from the tuyere 2 of the smelting gas furnace 1 rises, and after the direct reduction and indirect reduction with the furnace charge in the semi-coke bed, reaches the dome area 3 domain for temporary stay. The dome area has 4 dust burners 4, 4 oxygen coal burners, and the oxygen coal burners 5 are connected to the oxygen coal burners 5. The combustion in the smelting gas furnace dome area above the semi-coke bed is used to improve the dome temperature. The adjustment of the dome temperature can be controlled by increasing or reducing the oxygen content of the dust burner and the oxygen coal burner. At the same time, the dust burner sprays the dust collected by the dust back blowing line, mainly the mineral powder and the coal powder, for re-combustion, thereby reducing the dust content in the whole dome area.

[0019] The smelting gas furnace dome of the European smelting furnace is a dome-shaped top. The center of the dome is the coal distributor 6. The coal, coke and auxiliary materials, mainly dolomite and silica, are distributed to the semi-coke bed on the smelting gas furnace dome through the two-stage coal screw 7 and the coal distributor 6. Around the coal distributor 6 are 8 DRI flap distributors 7. The reduced ore, coke and auxiliary materials in the shaft furnace 8 are twisted into the DRI downpipe 9 by the 8 DRI screws, and are distributed to the semi-coke bed of the smelting gas furnace through the flap distributor 7. There are four gas generating pipes 10 on the periphery. The gas generating pipe outputs the high-heat-value generated gas from the dome, and the temperature is the dome temperature of 1050-1080℃. After being cooled to 835℃ by the cold coal gas 11, part of it enters the shaft furnace to reduce the shaft furnace charge, and part of it goes through the excess gas line to control the plant pressure.

[0020] The key to adjust the dome temperature is to determine when to increase the oxygen content and when to decrease the oxygen content. The action direction should not be wrong, otherwise it may cause the dome temperature to fluctuate greatly. The action amplitude should also be determined according to the deviation of the dome temperature, and the amplitude can be confirmed again after one adjustment. In order to make the adjustment accurate and prevent the directional error of the adjustment, the following embodiments are proposed: Embodiment

[0021] The adjustment of the dome temperature should take the trend of the cold gas addition as an important reference. The method is as follows: if the cold gas addition increases as a whole, it indicates that the dome temperature rises, so the oxygen content of the burner should be appropriately reduced even if the dome temperature does not change; on the contrary, if the cold gas addition decreases as a whole, the oxygen content of the burner should be appropriately increased.

[0022] Because the insertion depth of the dome thermocouple 12 is not as deep as that of the hot cyclone thermocouple 13, and the dome thermocouple 12 is beside the coal distributor and concentrates in the central area of the dome, the feedback speed of the actual dome thermocouple 12 to the temperature change is greatly slower than that of the hot cyclone thermocouple 13. Therefore, it is more accurate and timely to take the trend of the cold gas addition as an important reference for adjusting the dome temperature.

[0023] This adjustment method is particularly effective when the dome thermocouple fails or is not sensitive. When the probe of the dome thermocouple is powdered after a long time of use, the sensitivity decreases, and the reaction lags behind according to the dome temperature operation. Large oxygen content reduction and oxygen content increase cannot control the dome temperature in the range of 1050-1080, resulting in a large fluctuation of the dome temperature. The gas amount can be used as a backup reference to effectively stabilize the dome temperature, improve the furnace condition, and reduce the workload of the operator. Embodiment

[0024] The dust burner is adjusted according to the trend of the dome temperature and the CO2 content in the cold gas. According to the principle of "opposite adjustment and same direction non-adjustment", the oxygen content of the dome burner is operated. This method is simple and practical, can accurately judge the change of the chemical reaction trend in the dome area at each time, and can stabilize the CO2 content in the gas in an ideal interval.

[0025] Specifically, the CO2 composition in the cold gas and the dome temperature are negatively correlated in general, that is, when the CO2 decreases, the dome temperature will rise after a period of lag; when the CO2 rises, the dome temperature will also decrease after a period of lag. Theoretically, the following two reaction formulas can explain this phenomenon. When the CO2 composition rises, it proceeds in the direction of reaction formula ①, and this is an endothermic reaction. After the heat is absorbed, the dome temperature will decrease after a period of time. When the CO2 composition decreases, it proceeds in the direction of reaction formula ②, which is an exothermic reaction. With the heat released, the dome temperature will subsequently rise.

[0026] ① CO2+C=2CO endothermic

[0027] ② 2CO=CO2+C exothermic

[0028] CO2 component is the leading indicator of the dome temperature changes, and with the dome temperature to a certain extent, a negative correlation between. Embodiment

[0029] According to the trend of CO2 content increases and decreases the oxygen content of the burner. Cold gas CO2 content is high, the theoretical basis for the CO2 content is high because of the dome temperature drop caused by the dome temperature drop to promote the chemical reaction CO + O2 = CO2 + exothermic reaction, to the exothermic direction, at this time to increase the oxygen content of the burner; otherwise, to reduce the oxygen content.

[0030] According to the trend of CO2 component to adjust the oxygen content of the burner, you can well control the dome temperature, when the CO2 component is significantly reduced, reduce the oxygen content of the burner; when the CO2 component is significantly increased, increase the oxygen content of the burner; when the CO2 component narrow amplitude fluctuations, the oxygen content of the burner remains unchanged. Such operation is equivalent to the dome temperature has directionality of the pre-adjustment, effectively control the dome temperature fluctuation range.

Claims

1. A method for controlling the dome temperature of a molten gasifier in a metallurgical furnace, characterized in that... The specific steps are as follows: 1) The temperature control range of the dome is 1060-1090℃, and the CO2 content in the cold gas is controlled between 6% and 9%. The control method is to adjust the oxygen flow rate of the dust burner or oxy-fuel burner, and adjust the oxygen flow rate by increasing or decreasing the temperature, decreasing or increasing the CO2 content, and decreasing or increasing the oxygen flow rate by 100-400 Nm³. 3 / h amplitude adjustment; 2) The minimum dome temperature required to maintain the pyrolysis volatiles is ≥950°C; 3) Adjust the oxygen flow rate of the dust burner or oxy-fuel burner to control the CO2 content in the cold coal gas, while simultaneously controlling the amount of solid carbon powder in the dome area to ensure it is sufficient. Whether the amount of solid carbon powder is sufficient is determined based on the correlation between the dome temperature and the CO2 content. Adjust the dust burner according to the trend of dome temperature change and the CO2 content in the cold coal gas. The principle of "adjusting in opposite directions and not adjusting in the same direction" applies to the CO2 content and dome temperature trends. Specifically, the CO2 composition of the cold coal gas and the dome temperature are generally negatively correlated. That is, when CO2 decreases, the dome temperature will rise after a period of lag; when CO2 increases, the dome temperature will also decrease after a period of lag. 4) Under normal production conditions, the oxygen content of the dust burner should be controlled at 3500-4000 Nm³. 3 / h, the oxygen content of the oxy-fuel burner is controlled at 7400-7600 Nm³ / h. 3 / h; 5) When the temperature at the top of the coal arch is too high, first reduce the oxygen content of the coal burner, then reduce the oxygen content of the dust burner, and turn on the nitrogen gas of the coal feeder in a timely manner. 6) Adjust the oxygen flow rate of the dust burner and the oxy-fuel burner by 100-400 m³ / min per step. 3 / h, with an adjustment interval of more than 1 minute each time.

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