Specialized metallurgical processes – compositions for use therei – Processes – Electrothermic processes
Patent
1982-01-11
1983-06-21
Andrews, M. J.
Specialized metallurgical processes, compositions for use therei
Processes
Electrothermic processes
266182, 266 47, C21B 500
Patent
active
043892442
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to ferrous metallurgy, and more particularly, to a method of supplying a pulverized fuel mixture to blast furnace tuyeres.
The invention is useful in melting pig iron within the blast furnace utilizing injection of coal-dust fuel into the hearth.
BACKGROUND ART
Coking coals are in short supply, that is why one of the most urgent problems of blast furnace production is to replace the coke by fuel mixtures based on noncoking coals, e.g. by coal-dust fuel whose resources are sufficiently large. With utilization of such fuel mixtures, it is especially important to provide for the uniformity of their supply to blast-furnace tuyeres.
Known in the art is a method of supplying coal-dust fuel to blast furnace tuyeres (see N. E. Dunayev et al., Vduvaniye pylevidnykh materialov v domennye pechi, Moscow, "Metallurgiya," 1977, p.p. 96-97), comprising transportation of the above fuel to conical dividers, dividing the fuel flow therewithin into a plurality of flows, the latter being directed along outgoing pipelines to the blast furnace tuyeres.
In the given case fuel is distributed to the tuyeres in a non-uniform manner because the values of hydraulic resistances of drain pipelines are different.
Also known in the art is a method of supplying pulverized fuel mixture, disclosed in the description of operation of the apparatus according to U.S. Pat. No. 3,204,942 and comprising batch loading a discharging chamber with a pulverized fuel mixture and subsequent continuous transportation thereof by means of carrier gas through calibrated openings of a distributor dividing the fuel flow into a plurality of flows, following which said mixture is supplied along outgoing pipelines to blast furnace tuyeres.
It is obvious that utilization of calibrated openings in the given method provides for equalization of the values of hydraulic pressures within the pipelines thereby improving uniformity of fuel distribution to the tuyeres. However, with oscillations of pressure at the blast furnace tuyeres and with wearing or stopping up at least one of the outgoing pipelines, the uniformity of fuel distribution to the tuyeres is upset. The above fact results in formation of conduits within the blast furnace shaft, in deterioration of descent of charge materials, i.e. in upsetting the optimum processing condition of the melting process.
DISCLOSURE OF THE INVENTION
What is required is a method of supplying a pulverized fuel mixture wherein hydrodynamic characteristics of outgoing pipelines are equalized to ensure uniform distribution of fuel to blast furnace tuyeres.
The invention provides a method of supplying a pulverized fuel mixture to blast furnace tuyeres, comprising batch loading the pulverized fuel mixture into a discharging chamber being under gauge pressure, continuous discharging the above mixture from the discharging chamber and transporting it to the blast furnace tuyeres, supplying gas to pipelines, transporting the above fuel mixture along the pipelines by means of said gas, introducing supplementary gas into each pipeline following the discharge of the pulverized fuel mixture from the discharging chamber, the total flow rate of the supplementary gas exceeding that of the main gas 3 to 10 times, the product of the total flow rate of gas in each pipeline by the concentration of the pulverized fuel mixture contained therewithin being maintained constant for all the tuyeres.
The above fact makes it possible to equalize hydrodynamic characteristics of the pipelines, namely to increase hydraulic resistance of each pipeline thereby lowering the effect of changes in counterpressure at the blast furnace tuyeres, and consequently to improving uniformity of fuel distribution to the tuyeres.
The supplementary carrier gas is preferably introduced into the pipeline in the form of a stream directed toward the above fuel mixture leaving the discharging chamber, the speed of the stream of the supplementary gas being maintained within 0.25 to 1.5 times the critical speed of its outflow.
It will also al
REFERENCES:
patent: 3167421 (1965-01-01), Pfeiffer et al.
patent: 3689045 (1972-09-01), Coulter et al.
Bannikov Jury G.
Bat Jury I.
Danilin Evgeny A.
Kamardin Alexei M.
Lukyanchenko Leonid F.
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