RU1770370C - Method of stoves heating - Google Patents

Abstract

Essence: when using low-calorie fuel, heating is carried out in two stages. At the same time, within 0.75-0.87 from the beginning of the heating period, part of the fuel is burned in the lower zone of the combustion chamber with an air flow coefficient of 1.05-1; 1, in the remaining time, one-stage heating is carried out by burning fuel in the lower zone of the combustion chamber at a flow rate air 1.05-1.1.

Description

The invention relates to metallurgy, in particular to a method for heating air heaters of blast furnaces, and can be applied in the industries of the national economy to improve the environmental parameters of flue gases.

A known method of heating a high-temperature air heater, where, in order to increase the heating efficiency of the blow and the resistance of the combustion chamber in the lower part of the combustion chamber, low-calorie and high-calorific fuel is burned with an air flow coefficient of 0.6-0.85 and the combustion temperature is maintained at 1000-1150 ° C, and the upper part burns the gas and maintain the temperature of the furnace under the dome 1450-1500 ° С 1.

The closest in technical essence is the method of burning gas in the air heaters of blast furnaces, including the supply of high-calorie and low-calorific fuel and air 2. To increase heating, blow and increase

resistance of the combustion chamber in the main burner burn low-calorie fuel with a flow coefficient of 1.6-2.2 and high-calorific fuel in the amount of 2-40% is fed into the second zone through an additional burner installed above the hot-blow nozzle. The disadvantage is that. that the task of improving the operation of this device was considered without taking into account the formation of such harmful substances as nitrogen oxides, the release of which into the atmosphere seriously complicates the environmental situation. Moreover, this solution is complicated by the supply of two gas pipelines, low-calorie and high-calorie.

An object of the invention is to reduce the concentration of nitrogen oxides.

The goal is achieved. that in the method of heating air heaters of blast furnaces with hydrocarbon-containing gaseous fuel, including supplying air and fuel to the lower zone of the combustion chamber, when heating the air heater (L

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l low-calorific fuel within 0.75-0.87 from the beginning of the heating period, carry out two-stage heating, while in the lower zone of the combustion chamber part of the fuel is burned with an air flow coefficient of 1.4-1.6, the rest of the fuel is burned in the upper zone with an air flow coefficient of 1.05-1.1, in the remaining time, one-stage heating is carried out by burning fuel in the lower zone of the combustion chamber with an air flow coefficient of 1.05-1.1.

During two-stage heating in an air heater, the entire combustion air is fed through the main burner to the lower zone of the combustion chamber to maintain an airflow coefficient of 1.4–1.6, and during the initial heating period of 0.75–0.87, 65–75% of the total fuel consumption, and to the upper zone through an additional burner located above the hot blow nozzle, all remaining fuel is supplied until it is completely burned with an air flow coefficient of 1.05-1.1.

For normal operation of air heaters, when switching from blowing mode to heating mode, when in the lower zone of the chamber the torch must be ignited from a masonry having a temperature not lower than 800 ° C, during 0.13-0.25 the final heating period takes place one-step heating to raise the temperature of the masonry to 910-920 ° C with cooling during the period to blow to 840-850 ° C.

When switching to single-stage heating, the fuel supplied to the upper zone enters the lower zone, where, together with the previously supplied part of the fuel, it burns out with an air flow coefficient of 1.05-1 1.

In two-stage combustion, the maximum temperature decreases

zone of the plume, which helps to reduce the rate of reaction of the formation of nitrogen oxides. In this case, in the upper zone, when the fuel is burned, the temperature will increase slightly. However, some of the nitrogen oxides formed in the lower zone will interact with the newly supplied fuel and will be reduced (2NO + + 2H2 2H20 + No.).

In the upper zone, the most complete combustion of the fuel takes place, as a result of which not only nitrogen oxides are reduced, but also carbon oxides, which is associated with an effect similar to the recirculation method when combustion products are fed to the flare.

This heating method leads to a decrease in the concentration of nitrogen oxides in comparison with the existing heating method on existing blast furnace air heaters by 12-14 times.

Claims (1)

The claims A method of heating blast furnace air heaters, comprising supplying air and hydrocarbon-containing gaseous fuel to the upper and lower zones of the combustion chamber and burning and heating thereof, characterized in that that, in order to reduce the concentration of nitrogen oxides when using low-calorie fuel, heating is carried out in two stages, while in the first stage, with a relative duration of 0.75-0.87 of the total and in the lower zone of the combustion chamber, part of the fuel is burned with an air flow rate of 1 , 4-1.6, and in the upper zone part of the fuel is burned with an air flow coefficient of 1.05-1.1. and in the second stage, the remaining fuel is completely burned.