SU1502623A1 - Air tuyere for blast-furnace - Google Patents

Abstract

The invention relates to ferrous metallurgy and can be used in blast furnace production. The purpose of the invention is to reduce the consumption of coke-is achieved by improving the mixing of carbon-containing additives with the blowing stream. For this, a lug (0.10-0.20) D _f in length (1-5) H located at a distance (1-5) H from the edge of the nozzle the supply of carbon-containing additives, where D _f - the inner diameter of the tuyere, the H-height of the protrusion. Fuel economy is 5-7 kg of coke per ton of pig iron. 4 ill., 2 tab.

Description

The invention relates to ferrous and metallurgy and can be used in blast-furnace production for the supply of hot blowing and carbon-containing additives to the forge.

The purpose of the invention is to reduce coke consumption for smelting iron by improving the mixing of carbon-containing additives with the blowing stream.

The protrusion on the inner glass of the tuyere causes turbulence in the flow to blow, i.e. blowing itself mixes up hydrocarbons. If the protrusion is positioned in front of the addition point (viewed from the nozzle), a discharge is formed behind the protrusion. At the same time the stream of additives will penetrate into more

deep areas of the flow and better mixed with it. The size of the protrusion and the distance of its base to the point of entry should be optimal and replaced depending on the consumption of natural gas. To determine the above parameters, studies were conducted on a gas-dynamic model of an air tuyere in compliance with the basic laws of modeling. Studies have shown (Pl. O that the height of the protrusion h should be 0.10-0.20 diameter, if h is less than 0.10 (for example, 0.05) d, then the turbulent motion will cover only the surface layer and the mixing will not be complete .

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With an excessively large protrusion (0.25 d), the blast flow is too much resistance, which leads to a decrease in the productivity of the blast furnace. In blast furnaces, gas consumption varies widely from 70 to 160 m / t of pig iron. The greater the flow rate of natural gas, the more necessary it is to create a higher flow turbulence for the hydrocarbons to fully interact with the oxidizing agent and then distribute the combustion products evenly in the tuyere hearth. Therefore, for blast furnaces with low natural gas consumption, the protrusion size is minimal (0.1 djj) .C by increasing the consumption of natural gas, respectively, increase the size of the protrusion. With a consumption of natural gas of 160 m / t of cast iron, 20 d ,. The length of the protrusion 1 is determined, in addition to ensuring optimal turbulence of the blower, and the need to ensure reliable cooling of it with water.

The greater the water pressure, the less 1 is required and vice versa. The coolant pressure on the tuyeres varies in blast furnaces from 2.5 to 5.0 atm. With a water pressure of 2.5 atm 1, it is 5 h, and at 5.0 at air pressure 1 h. To ensure sufficient turbulence of the blast flow, it is sufficient to have 1 equal to 1 h, t, and the choice of this size of the protrusion is determined mainly by the pressure of the cooling water,

Conventionally, it was assumed that satisfactory mixing occurs at, 5, where d (p is the internal diameter of the gas-dynamic model.

Significant influence on the nature of the interaction of the flow of blowing and natural gas jets has a distance from the edge of the protrusion to the point of its introduction (S). Model tests showed that the best mixing is achieved when S is in the range of 1-5 h. If the distance is less than 1 h, then the outgoing natural gas stream destroys the turbulent vortices formed behind the protrusion, which reduces the overall turbulence of the flow to blow. If S is exceeded 5 h, the mixing of the natural gas with the blast also decreases as the turbulent vortices shift from the moment of formation to the tuyere axis and already

do not involve in mixing the entire volume of the injected gas. The choice of the optimal S is based on the flow rate of natural gas. The higher it is, the greater the distance from the protrusion should be the supply and vice versa. The need for increasing S with increasing natural gas consumption is evidenced by the fact that as the gas flow increases, the angle of jet opening is greater and therefore the probability of turbulent eddy destruction is greater.

Fig, I shows the air lance, general view; in fig. 2-4 - section aa in fig. 1.

The air lance contains a water-cooled body 1, a rile part 2, a branch pipe 3 for supplying natural gas, a water-cooled protrusion 4.

Several embodiments of the protrusion have been proposed: I - a rectangular protrusion is located along the entire circumference of the inner glass of the air tuyere (Fig 2); II - a rectangular protrusion occupies 1/2 of the circumference of the inner cup (Fig. 3); III - a rectangular protrusion occupies 1/4 of the circumference of the inner cup immediately before the supply of natural gas (Fig. 4),

The choice of one of the three proposed options should be made from the conditions of the presence of the reserve power of the blower means to the blast furnace, since the protrusion has a certain resistance to the passage of gas. If there is a reserve for the power of the blower means, then any of the three options can be applied. The first option is most appropriate in this case, since the mixing of additives and blowing is maximum. If the power margin is small, then the second option should be applied. In the third option, the pressure loss is practically absent. It should be noted that even in the third embodiment, the mixing remains high.

Data on gas head loss in the gas-dynamic model for options I, II and III are presented in c. Table 2

In order to ensure reliable operation of the protrusion, a constant inflow of cooling water to it is necessary. To do this, a hole is made in the pressure tube (the tube brings water to the lance)

diameter 1 / 3-1 / 4 of the output diameter of the pressure tube. Thus, part of the fresh water goes directly

rennie diameter of tuyeres, h - protrusion height.

Table 1

WATER

gazi

fie. one

Aa

A a

Fi9. I

Fish.W

Aa

fis. four

Claims (2)

Claim An air tuyere of a blast furnace containing a water-cooled casing with 15 flanges, a snout and a nozzle for supplying carbon-containing additives with an inlet, characterized in that, in order to reduce the coke consumption for smelting pig iron 20 by improving the mixing of carbon-containing additives with the blast flow, a protrusion of a height of (O, 10-0.20) * d <p, length (1-5) выполнен, and it is located from the edge of the supply at a distance of (l-5) < h, where d ^ is the inner diameter tuyere meter, h is the height of the protrusion. Table 1 The lance model parameter value 1 degree I mix 1 cm Protrusion height h 0.05 0.82 for l = h 0.10  0.40 0.15 0.35 0.20 0.33 0.25 0.32 Protrusion length 1 at h = 0.20 dg, 0.5 0.70 1,0 0.35 s oh 0.35 5,0 0.34 6.0 0.34 Distance to supply S at h = 20 d ™ 0.5 0.75 1,0 0.30 3.0 0.40 5,0 0.50 6.0 0.82 Table 2 Option Gas velocity, m / s Loss of pressure, Pa I 1,0 60 1,6 80 II 1,0 35 1,6 fifty III 1,0 20 1,6 thirty L-4 Λ “Λ A -A F “* 2 fi 9.3 fie. to