Specialized metallurgical processes – compositions for use therei – Processes – Process control responsive to sensed condition
Reexamination Certificate
1998-08-20
2001-05-08
King, Roy V. (Department: 1742)
Specialized metallurgical processes, compositions for use therei
Processes
Process control responsive to sensed condition
C075S379000, C075S445000, C075S550000, C075S556000, C266S086000, C266S092000, C266S223000
Reexamination Certificate
active
06228142
ABSTRACT:
This application is a national stage of PCT/KR97/00273, filed Dec. 19, 1997.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for keeping an optimal penetration depth formed at the front end of an oxygen tuyere and a method for keeping the same when producing molten pig iron utilizing non-coking coal, and more particularly to an apparatus for keeping an optimal penetration depth formed at the front end of an oxygen tuyere and a method for keeping the same using a sensor for measuring distance which is installed at the inside of oxygen tuyere when producing molten pig iron utilizing non-coking coal.
2. Description of the Prior Art
Generally, a blast furnace method, which forms the majority of the producing facilities of molten pig iron, requires raw material having a strength above a certain degree because of the characteristic of a reactor. As a carbon source used as a fuel and a reducing agent, coke obtained by processing a coking coal, is used. Accordingly, the producing facilities of the coke should be necessarily accompanied. In addition, the exhaustion of the raw coal of the coke and the regulation of various environment contaminating materials generated during the production of the coke has rapidly decreased the competitive power of the blast furnace method.
To cope with the above-mentioned circumstance, world nations have accelerate the development of production method of molten pig iron, which utilize the non-coking coal as the fuel and the reducing agent. U.S. Pat. No. 4,978,387 discloses the conventional production facilities of the molten pig iron using the non-coking coal.
According to U.S. Pat. No. 4,978,387, energy required for various processes is supplied through the combustion of a coal bed while injecting oxygen through a plurality of tuyeres, formed at the outer wall of the compacting layer with a constant distance in a circular shape, into the inner lower portion of the coal packed bed formed at a melter gasifier with a predetermined height. At this time, since the volumetric flow rate and the pressure of the oxygen injected through the tuyere are quite large and intensive, a space formed toward the inner portion of the coal packed bed (i.e. a penetration depth) is inevitably formed in front of the tuyere. The penetration depth largely affects the utilizing efficiency of the combustion energy, which is the supply source of the required energy in the production facilities of the molten pig iron utilizing the noncoking coal. Therefore, too short or too long penetration depth forms the gas as an excessive circumferential flow or an excessive central flow in the coal packed bed to deteriorate the effective use of the combustion energy.
Accordingly, an optimal keeping of the penetration depth is very important in the operation of the production facilities of the molten pig iron utilizing the non-coking coal. The optimal penetration depth is kept by keeping the oxygen blowing velocity at the tuyere constant by controlling the pressure applied in the melter gasifier according to the volume of the oxygen blown through the tuyere, for the present.
However, the penetration depth formed in the coal packed bed is under the influence of the structure, the particle size and the density of the coal which forms the coal packed bed, as well as the oxygen blowing velocity at the tuyere. Hence, even though the oxygen blowing velocity is kept constant, the optimal keeping of the penetration depth according to the change of various conditions of the raw material, is difficult.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to improve the problems contained in the conventional method and to provide an apparatus for optimally keeping the penetration depth formed at the front end of the oxygen tuyere and a method for optimally keeping the same, which can actively cope with the change on the injection amount of the oxygen and the change on the constituting material in the coal packed bed according to the change of various conditions of the raw material and the operation.
To accomplish the object, there is provided in the present invention an apparatus for keeping an optimal penetration depth formed at a front end of an oxygen tuyere including a melter-gasifier for producing molten pig iron, a plurality of oxygen tuyeres formed around the outer lower portion of the melter gasifier for blowing oxygen into the melter gasifier, a cyclone for receiving an exhausted gas from the melter gasifier and for separating powder from the exhausted gas, a pre-reducing furnace for receiving the exhausted gas passed through the cyclone and for pre-reducing iron ores and a scrubber having a cone for controlling pressure in the melter gasifier, the apparatus comprising:
a sensor for measuring distance using a laser installed at an optional one of the oxygen tuyeres for continuously measuring the penetration depth;
a process computer for continuously receiving the measured penetration depth from the sensor for measuring distance using a laser and comparing the received penetration depth with a predetermined optimal penetration depth to obtain a difference between the actual penetration depth with the optimal penetration depth, and for obtaining a changing amount of pressure in the melter gasifier through a mutual relation between a predetermined changing amount of pressure in the melter gasifier with a changing amount of the penetration depth using the difference between the actual penetration depth and the optimal penetration depth; and
a scrubber cone controlling device for receiving the changing amount of the pressure in the melter gasifier from the process computer and for changing an opening degree of a scrubber cone to change the pressure in the melter gasifier.
Another object of the present invention can be accomplished by a method for keeping an optimal penetration depth formed at a front end of an oxygen tuyere in a method for producing molten pig iron utilizing a producing apparatus of the molten pig iron utilizing non-coking coal, the apparatus including a melter gasifier for producing molten pig iron, a plurality of oxygen tuyeres formed around the outer lower portion of the melter gasifier for blowing oxygen into the melter gasifier, a cyclone for receiving an exhausted gas from the melter gasifier and for separating powder from the exhausted gas, a pre-reducing furnace for receiving the exhausted gas passed through the cyclone and for pre-reducing iron ores and a scrubber having a cone for controlling pressure in the melter gasifier, the method comprising the steps of:
establishing the optimal penetration depth according to a pressure in the melter gasifier under a constant amount of oxygen blowing;
obtaining a mutual relation between a changing amount of a pressure in the melter gasifier under a constant amount of oxygen blowing and a changing amount of the penetration depth;
continuously measuring the penetration depth by a sensor for measuring distance using a laser installed at optional one of the oxygen tuyeres;
continuously obtaining a difference between the measured actual penetration depth and the optimal penetration depth;
obtaining a changing amount of the pressure in the melter gasifier by the mutual relation between the changing amount of the pressure in the melter gasifier and the changing amount of the penetration depth utilizing the difference between the measured actual penetration depth and the optimal penetration depth;
controlling the pressure in the melter gasifier as much as the changing amount of the obtained pressure by controlling an opening degree of the scrubber cone; and
repeating the steps until the actual penetration depth and the optimal penetration depth become the same.
REFERENCES:
patent: 361624 (1887-04-01), Gordon
patent: 3551140 (1967-10-01), Nilles et al.
patent: 3720404 (1973-03-01), Carlson et al.
patent: 4042378 (1977-08-01), Ramelot
patent: 4530102 (1985-07-01), Baker et al.
patent: 4978387 (1990-12-01), Kepplinger
patent: 5584910 (1996-12-01), Kepplinger et al.
p
Park Yoon Chul
Shin Myoung Kyun
King Roy V.
McGuthry-Banks Tima
Pohang Iron & Steel Co. Ltd.
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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