SI21762A - Device for capturing, processing and exhausting of gases around arc furnace - Google Patents

Abstract

A device for capturing and exhausting gases from around an arc furnace is carried out of a housing (1) with openings (5) through which electrodes (6) are standing, and of an opening (11) to which an exhaust channel (12) is attached, leading on the opposite side - outside of the place where the furnace is standing - to a dust filter (13) with a suction fan (14) on its rear side. A ring gap (7) is carried out between the respective electrode (6) and the opening (6) through which the former is standing, while the striking of the housing (1) to the furnace cover (2) is carried out with spacers (8) due to which the lower edge of the housing (1) is shifted from the cover (2) to create gaps (10) between them.

Description

Prislan Srečko

A device for the capture, processing and extraction of gases

AT THE ARC FURNACE

The subject of the invention

The object of the invention is a device for capturing gases in an arc furnace, processing gases into an environmentally friendly state, and discharging them into the environment.

A technical problem

The technical problem solved by the godfather is how to design such a device for the capture, processing and extraction of gases in an arc furnace that will be simple, without special additional attachments and devices that would have to be designed specifically for that environment and precisely in order to withstand in such a thermally and mechanically demanding environment that their inactivity may not cause the electric arc furnace to be interrupted or reduced, the device according to the invention also being able to process toxic gases emanating from the arc furnace into gases that are less environmentally friendly. load-bearing pipelines to the mechanical filter, and at the same time the device should also create improved conditions for the operation of arc furnace electrodes to extend their service life and thereby reduce the amount of carbon in the steel that occurs due to combustion of the electrodes into the melt, that the device should also be energy efficient and therefore reasonably priced.

31086.dOC / yy-04 / D33-Vr

The prior art

Known devices for gas capture and discharge in an electric arc furnace are made of a housing that covers the furnace cover and which captures gases emitted through the slots adjacent to the electrodes in the surrounding area. Because the electrodes are higher than the housing, there are openings for the output of the electrodes.

Due to the high temperature of the furnace cover, heat is also transferred to the housing of the gas collection device. Therefore, the sealing rings next to the electrodes are designed in a particularly challenging way. The ventilation fans at the appliance must withstand high temperatures because the gases are very hot when exiting the furnace. A particular problem is the design of the gas exhaust ducts, which must be flexible in order to follow the opening of the furnace cover and gas collection device. All this contributes to the intricate construction of the gas capture and discharge device. Due to the hot exhaust gases, both the housing of the device and the drainage pipe are very hot, which raises the unfavorable level of the working environment in Man.

However, there is a need for a simpler installation of this kind, which will be less burdened with possible failures, not least its lower cost should contribute to lower steel production costs. Due to increasing concern for the environment, the quality of the gases being discharged into the surrounding atmosphere is also subject to more stringent requirements.

The solution to a technical problem

The described technical problem is solved with a new device for the capture and extraction of gases from the arc furnace, the essential feature of which is that the housing covers the furnace cover at a distance such that a narrow gap is made between them. Also, the openings for the electrodes are larger with a circular gap between them and the housing. The discharge of gases through the exhaust duct is only done by the pressure produced by the intake vents behind the filter located away from the space in which the

31086.doc / yy-04 / D33-Vr located furnace. The amount of suction air is several times the estimated amount of gases emitted from the furnace. This ensures the suction of ambient air through the slots between the appliance and the furnace cover and through the slots next to the electrodes. The pressure in the device ensures that no gas escapes from the device into the surrounding area except through the discharge duct. The extra oxygen in the device, which is supplied by the intake air, causes the gases emanating from the arc furnace to burn in the device itself so that they become significantly less burdensome to the environment.

The relatively high temperature in the plant (about 700-900 ° C) additionally warms the furnace due to the combustion of gases emitted from the furnace and the ambient air. At the same time, the ambient air entering the device ensures that the electrodes do not overheat above 700-900 ° C, so they are not yet annealed and thus the graphite electrode combustion rate is significantly lower due to oxidation upon contact with the surrounding air. Based on this fact, the thickness of the new electrodes may be smaller by the same actual electric current intended for melting in the furnace.

It has also been shown that, due to the strong suction of gases from the device and the cooling of the electrodes, the described device of the invention permits additional forced air or oxygen supply directly to the furnace in order to accelerate the melting of the contents without damaging the electrodes. This increases the capacity of the stove.

The large amount of fresh air in the device, in addition to causing the combustion of gases into environmentally friendly gases, also significantly reduces their temperature to around 300 ° C when leaving the device. Therefore, the device needs to be substantially less water cooled than is the case with a known tonnage device so that its outdoor surface temperature is tolerable to personnel. The temperature of the gases in the filter and fan area is reduced to about 80 ° C. The large amount of ambient air relative to the gases emitted from the furnace introduced into the apparatus according to the invention further ensures that the amount of particulate matter per unit exhaust gas is small. So don't

31086.doc / yy-04 / D33-Vr increases the specific gravity of a mixture of gases and particles, thereby maintaining a high flow rate through channels. Dust particles do not fall in large quantities to the bottom of the ducts, especially at curves, but reach the filter where they separate from the gases. This ensures a long operating time of the device without the necessary cleaning of the channels.

Due to the high temperature of the gases in the filter, no condensate can be formed in it, leaving the particulate matter in the filter dry and not adhering to a paste which would otherwise require the filter to be cleaned too quickly if the oven is interrupted.

Since the device according to the invention prevents the escape of gases from the furnace into the surroundings, the amount of ambient air required to mix the furnace gases and the two together is sucked in and mechanically filtered at least 5 times less than the amount of furnace air and gases in known embodiments and for the same end effect , the suction and filtering devices required are significantly smaller, cheaper and also more energy efficient.

When loading the kiln with the raw material, the device according to the invention is mounted together with the lid of the kiln. The flexible part of the duct allows the housing to rotate. In the same way, the housing is rotated by the furnace lid when the furnace is rotated when the melt is poured out of it.

The essence of the invention is explained in more detail by the following description of an embodiment and the accompanying drawing, in which FIG. 1 is a schematic view of a arc furnace with a gas capture, processing and exhaust device according to the invention.

The device for the capture, processing and extraction of gases in the arc furnace is made of a housing 1, which is installed only in the sense of fitting on the lid 2 of the arc furnace 3. The housing 1 is two-sided and is intended for cooling with coolant via

31086.doc / yy-04 / D33-Vr Terminals 4. Furthermore, openings 5 are provided in the housing through which the electrodes 6 flow, so that a circular gap 7 is formed between the electrodes 6 and the opening 5. the furnace is made with spacers 8, which cause the lower edge of the housing 1 to be moved away from the cover 2 so that the slots 10 are between them. The cover 1 has an opening 11 to which the drainage channel 12, which is on the opposite end, is connected, as a rule outside the enclosure of the furnace, introduced into the dust filter 13, behind which a suction fan 14 is installed. In duct 12, a branch 15 is made for the auxiliary duct 16, which catches beneath the ceiling of the space preferably above the furnace the gases leaking from the furnace at pouring melt. In channel 12, a flexible bellows 17 is provided between the housing 1 and the branch 15, which allows the furnace to be tilted and the furnace lid opened with the housing installed and a drainage duct connected to it.

The shape and size of slots 7, and in particular slots 10, are arbitrary and can be adapted to individual requirements. Preferably, the total cross-section of the slots 10 is equal to the channel cross-section

12.

The cooling of the housing may also be performed in any manner other than that described. The cooling water outlet can be led to a heat exchanger 18 and then transferred to any medium in a known manner.

There are also special devices for the capture and extraction of gases from the furnace upon the pouring of the melt, the installation of which does not affect the device according to the invention. The ducts, filter and fan can also be modified and adapted to individual conditions without affecting the content of the present invention.

One of skill in the art may, in the knowledge of the description of the invention, conceive other embodiments without circumventing the essence of the invention as defined in the following claims.

Claims (6)

Patent claims A device for the capture, processing and extraction of gases in an arc furnace (3), which is made of a housing (1) in which the openings (5) through which the electrodes (6) flow and the opening (11) are made, to which is connected a drainage duct (12) at the opposite end, as a rule, outside the space in which the arc furnace is introduced, introduced into a dust filter (13), behind which a suction fan (14) is mounted, characterized in that between the electrode (6) and the opening (5) through which the annular slot (7) flows and the slots (10) for entering ambient air into the device are provided in the housing (1) on the furnace lid (2). according to the invention. Apparatus according to claim 1, characterized in that the slots (10) are arranged at the edge of the housing (1) so that spacers (8) are provided between the furnace cover (2) and the housing (1). Device according to claims 1 and 2, respectively; in that the total cross-section of the slots (10) is preferably equal to the cross-section of the channel (12). Apparatus according to Claims 1 to 3, characterized in that a trapping duct (16) is provided below the ceiling above the stove for gases emanating from the furnace upon pouring the melt from the furnace, and which is preferably connected to the branch (15) in channel (12). Device according to claims 1 to 4, characterized in that the ratio of air drawn by the fan (14) from the furnace surroundings through the slots (7 and 10) and the gases emitted from the furnace and covered by the device is about 20 : 1. Device according to claims 1 to 5, characterized in that the housing (1) is forced-cooled, preferably with water.