Metallurgical apparatus – With control means responsive to sensed condition – With means responsive to condition of treated material
Reexamination Certificate
2000-02-07
2001-07-17
Kastler, Scott (Department: 1742)
Metallurgical apparatus
With control means responsive to sensed condition
With means responsive to condition of treated material
C266S099000, C266S199000
Reexamination Certificate
active
06261513
ABSTRACT:
The invention relates to a device for direct observation of the charging process inside a shaft furnace during its operation, in particular a blast furnace.
It is already known that the most uniform possible furnace charging is of crucial importance for optimum operation of a shaft furnace, e.g. a blast furnace. Hence in larger blast furnaces the conventional bell-type closing device has been replaced by bell-less throat closing devices with rotary chutes with angular adjustment, which allow selective build-up of the charge column in the blast furnace. To allow selective control of the build-up of the charge column in practice, the surface profile of the charge in the blast furnace is determined by special measuring equipment and the movements of the rotary chute with angular adjustment are controlled as a function of the determined surface profile.
In particular, measuring lances, which can be introduced radially into the blast furnace through a lateral opening in the shaft furnace wall above the charge column and have at least one profile probe for mechanical or contactless scanning of the charge surface, have been adopted in practice as measuring devices for determination of the surface profile of the charge. For example, a measuring lance with a plumb bob as the profile probe, which is secured to a wire rope running over a rotary drum, is already known from U.S. Pat. No. 4,326,337. The unreeled wire rope length when the plumb bob strikes the charge surface is measured. It is already known from DE-A-32 33 986 how to install an ultrasonic sensor in the plumb bob to scan the surface without contact and thus avoid penetration of the plumb bob in the charge surface. It is already known from EP-A-0291 757 how to install in the front end of the measuring lance a swivelling radar probe, which permits contactless scanning of the charge surface by radar waves.
To allow selective control of the build-up of the charge column with the aid of the determined surface profile, however, the charging characteristic (i.e. the trajectories) of the charging device for the respective charge material must be known. This charging characteristic is measured by means of tests with different charging parameters when a new charging device is commissioned and summarised in tables or mathematical models. However, this charging characteristic varies with time, e.g. due to erosion of the sliding surfaces in the charging device. Furthermore, it should be pointed out that a reliable charging characteristic is, of course, not -available for untested charge material or for varied charging parameters. The charging characteristic can, of course, be checked and/or supplemented when a furnace is shut down. During operation of the blast furnace, however, indirect conclusions concerning changes in the charging characteristic can be drawn only by comparisons of the determined surface profile with the pre-calculated surface profile. These conclusions are nevertheless extremely unreliable, because the determined surface profile is relatively inaccurate on the one hand and is staggered in time in relation to the charging process on the other. In fact reliable profile measurements can be made with the already known profile probes only in the intervals between charging and not during the charging process itself.
Hence the invention is based on the task of creating a device for direct observation of the charging process inside a shaft furnace, in particular a blast furnace, during its operation.
A device according to the invention comprises a measuring lance, which is arranged in such a way above the charge column in the shaft furnace that it is exposed during the charging process to the charge material falling from a charging device, and sensor means, which detect the position of the falling loose material in relation to the measuring lance. The measuring lance can accordingly be permanently arranged in the shaft furnace. In a preferred form of construction, however, the measuring lance—like already known measuring lances for the blast furnace—can be introduced radially into the shaft furnace through a lateral sealing device in the furnace wall above the charge column, whereby the measuring lance when introduced is exposed to the charge material falling from a charging device during the charging process. Hence with this measuring lance the trajectories of the charge material can be recorded during the charging process. Consequently changes in the charging characteristic of the charging device can be ascertained directly during furnace operation. These changes can be taken into account in the tables and/or mathematical models, which are used to control the charging device. Tables and/or mathematical models for charge material with new parameters can easily be compiled during furnace operation. This contributes significantly to optimisation of the charging of a blast furnace. Furthermore, changes detected in the charging characteristic permit conclusions to be drawn concerning wear (e.g. due to erosion of the sliding surfaces) in the charging device itself. The proposed device can be used, for example, to establish when the rotary chute in a bell-less throat closing device needs to be replaced. In this case the maintenance costs for the charging device are reduced and the furnace shutdown times for maintenance work can be shortened if necessary.
The sensor means advantageously comprise at least one impact sensor, which records the impact of pieces of charge material on the measuring lance. This impact sensor is advantageously designed as a position-resolving pressure sensor extending along the active area of the measuring lance, i.e. as a pressure sensor with which the point of impact of the charge material on the lance can be determined. It may be, for example, an interchangeable film pressure sensor, which has several separate active areas along the active area of the measuring lance. To prevent damage to the film pressure sensor by the falling material, the sensor is preferably covered by an elastomer material or enclosed in an elastomer body.
In a second embodiment the impact sensor is designed as a sound sensor. This advantageously comprises several resonance bodies arranged one behind the other in the longitudinal direction of the measuring lance and several sound conductors, a sound conductor extending inside the measuring lance from the respective resonance body to a rear end of the measuring lance outside the shaft furnace being assigned to each resonance body. At the rear end of the measuring lance a microphone, which picks up the sound generated by the resonance body and converts it into electrical signals, is assigned to each sound conductor.
In a further embodiment, the impact sensor incorporates several fluid cells arranged one behind the other in the longitudinal direction of the measuring lance, wherein each fluid cell can be supplied with a fluid via a fluid supply. Each fluid cell is accordingly a detector for detecting the change in fluid pressure in the fluid cell concerned. If a piece of charge material impacts on one of the fluid cells, a pressure shock occurs in that cell, which is detected by the detector allocated to that cell and converted into, for example, an electrical signal. The electrical signals produced by the various detectors are then evaluated in order to calculate the distribution of the impacting pieces of material on the measuring lance.
In a first, particularly simple variant of the fluid cells, each fluid cell forms an opening on the upper side of the measuring lance, through which the fluid can escape from the measuring lance, the opening of the fluid cell when impacted by a piece of charge material being capable of being closed at least partially by the piece of charge material. When a piece of charge material falls on to one of the openings, the flow of fluid through that opening is as a result briefly interrupted or at least significantly reduced. This leads to a brief rise in the static pressure in the fluid supply, which is detected by the detector. It should be noted that t
Bernard Gilbert
Bologna Aldo
Breden Emile
Lemmer Pol
Lonardi Emile
Kastler Scott
Paul Wurth S.A.
Smith Gambrell & Russell
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