SU854991A1 - Method of reagent supply to blast furnace tuyere - Google Patents

Description

(54) METHOD FOR SUPPLYING REAGENTS IN A DIFFERENT FURNACE

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The invention relates to ferrous metallurgy, in particular to the production of pig iron in blast furnaces.

A known method of supplying the reactants to the tuyeres of blast furnaces allows the various hydrocarbon additives to be blown into the furnace gas of the tuyere zone together with the oxygen enriched blast 1.

The known method of supplying reagents to the tuyeres does not allow for complete dispersion and mixing with the blast of the injected fuel. As a result, black carbon and excess hydrogen are produced in the top gas, which are removed from the furnace, which reduces the rate of coke replacement by gaseous or liquid fuel.

The closest to the proposed technical essence and the achieved result is the method of supplying reagents to the tuyeres of the blast furnace, including blowing through the cavity and introducing a separate jet into the fuel blast through a gas supply tube bent to the cavity axis of the tuyere ,

However, in this method, the total degree of conversion of, for example, natural gas (calculated from the methane residue in the furnace gas) does not exceed 90%, and ensuring the homogeneity of the composition of the furnace gas in hydrogen by changing the design of the input of natural gas is almost impossible. This is due to the fact that natural gas introduced into the blast is distributed mainly in the upper part of the tuyere from the inlet side, while unburned fuel undergoes pyrolysis and black carbon appears in the furnace gas flow, hydrogen concentration increases, which reduces the powerful savings of coke in blast-furnace smelting when using gaseous or liquid fuels.

The purpose of the invention is to reduce the coke consumption by increasing the degree of fuel reaction and the uniform distribution of hydrogen in the gas stream.

The goal has been achieved by supplying process oxygen together with a jet of fuel, and the fuel is introduced in the form of an oxygen jet shell 20 at a ratio of their expenses (4-6): 1.

Claims (2)

The drawing shows a device (longitudinal section), carrying out the proposed method. The device consists of a housing 1 with nozzles 2., intended to introduce natural gas and oxygen. The coaxially mounted nozzles 2 contain at the ends of the nozzle 3, which are led through the wall of the housing into the cavity at an angle A to the central axis 4. The method is carried out as follows. A blast is fed through the lance cavity and fuel is simultaneously introduced into this blast along with oxygen, with the fuel acting as a protective envelope of a stream of oxygen. Together, the outflow of oxygen and fuel from coaxially mounted nozzles on the nozzles provides thermal screening of the oxygen jet all the way in the lance cavity beyond the end. The residence time in the cavity of the tuyere, when the two-component jet exits the nozzles, is shorter than the incubation period of ignition, therefore, the fuel burns behind the tuyere end, in the furnace space. As a result, jets of oxygen and fuel only, once in the circulation zone of the foci of burning, begin to burn intensively. The high degree of destruction and combustion of the jet of fuel, with such an intake of oxygen, provides greater homogeneity of the gorny gas in the hydrogen content. In addition, the combustion of the fuel introduced into the blast flows in the area of the furnace where the heat released does not reach the water-cooled tuyere case. The principal difference of the proposed ratio from the known one is that the burning of such mixtures (in ratios 4-6: 1) significantly increases the level of reaction, bringing it closer to explosive nature, and ensures complete mixing of the components of combustion with horn gas. At the same time, increasing the ratio of more than 6 parts of fuel to 1 part of oxygen causes soot formation due to an excess of hydrocarbons in the local volume, and when the ratio decreases to less than 4 parts of fuel to 1 part of oxygen, the effect of thermal shielding of the jet of oxygen from its passage through the cavity decreases . Example. Through the air form of 2G180 mm, injection of natural gas with oxygen is supplied to the blast. Natural gas is supplied in an amount of 1000 s, with oxygen in an amount of 250, which is a ratio of 4: 1. The products of combustion enter the chamber simulating the tuyere zone. The introduced two-component jet ignites with a destruction of 120 mm from the end of the tuyere. Gas samples from the peripheral and central zones of the imitation chamber show the identity of the chemical composition, contain 11% of hydrogen and 38.9% of carbon monoxide. To check the selected ratio of 6: 1, a two-component stream of natural gas in the amount of 1000 and oxygen in the amount of 167 is fed into the chamber simulating the tuyere zone. The gas jet ignites at a distance of 200 mm from the end of the tuyere. Combustion products are intensively mixed and their analysis showed a high degree of homogeneity (hydrogen content up to 12% and carbon monoxide up to 39%). The greater homogeneity of the chemical composition of the combustion products increases the efficiency of the combined blowing, reduces coke consumption. At a ratio of 7: 1 or 1000 of natural gas and 140 of oxygen, which is more than 6: 1, methane is detected in the combustion products in the amount of 2.5%, hydrogen - 12%, carbon monoxide - 37.5%, nitrogen - 49 , 0%. The presence of methane indicates a reduction in the mixing effect of the jets, which is not acceptable, since it adversely affects the consumption of coke. When the ratio is 3: 1 or 1000 of natural gas and 330 oxygen, which is less than 4: 1, the two-component jet ignites in the tuyere cavity and the flame plugs contact with the end face, which causes an increase in temperature of outgoing water from the cavity by 3-4 ° C . The shielding effect of the natural gas jet in this case is not observed, which is not acceptable, since the heat released during the combustion of the two-component jet is irretrievably lost, adversely affecting coke consumption. The use of the proposed method provides, in comparison with the known, homogeneity of the furnace gas with respect to the hydrogen content, the reduction of irretrievable heat loss with cooling water, eliminates the thermal effect on the material of the tuyere body and the formation of black carbon. In addition, a high degree of utilization of the reducing ability of hydrogen, a decrease in heat loss with cooling water, and an increase in the longevity of the tuyere increase the possible savings in coke when using a combined blast in blast furnace smelting, especially with high enrichment with oxygen blowing. Claims of the method of reagents in the tuyere of the blast furnace, including blowing through the cavity and introducing fuel into this blast with a separate jet, characterized in that, in order to reduce the consumption of coke due to the increased degree of fuel reaction and homogeneity of the hearth gas, together with the blast fuel stream oxygen is supplied, and the fuel is introduced in the form of a shell of a stream of oxygen at a ratio of (4-6): 1. Sources of information taken into account during the examination 1. USSR author's certificate No. 370237, cl. From 21 to 7/16, 1969. 2. USSR author's certificate number 370257, cl. From 21 to 7/16, 1970.