JP3917842B2 - How to treat CFCs - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fluorocarbon detoxification method.
[0002]
[Prior art]
Fluorocarbon is a substance mainly composed of carbon, fluorine, and chlorine, and is generally used as a foaming material for heat insulating materials typified by refrigerator refrigerant and urethane foam.
[0003]
Various methods for treating chlorofluorocarbon have been reported so far. In particular, the incineration method is common. In the rotary kiln method, it is recommended to decompose at about 900 ° C. in 2 seconds, and to rapidly cool the gas at 850 ° C. to 70 ° C. in order to avoid resynthesis of dioxins. ing.
Also in the patent gazette, for example, Japanese Patent Laid-Open No. 11-6612 discloses a method for detoxifying chlorofluorocarbons by using the industrial waste treatment facility as a chlorofluorocarbon decomposition system by the same decomposition and cooling principle as described above. Has been.
[0004]
[Problems to be solved by the invention]
The present invention provides a method for detoxifying chlorofluorocarbons using a converter, and by using this detoxification method, the operation cost of the converter operation itself can be reduced and the life of the refractory can be extended. It provides about the effect of.
[0005]
[Means for Solving the Problems]
The gist of the present invention is as follows.
(1) In a converter steelmaking method having wet dust collection , supplying flon as a cooling gas for the converter into the converter to decompose the flon and collect wet dust. Method.
(2) In the converter steelmaking method with wet dust collection, the flon is decomposed and wet dust is collected by supplying flon into the converter as a gas for cooling the bottom blowing tuyeres of the converter. And chlorofluorocarbon processing method.
(3) In converter steelmaking with wet dust collection, dissociating the flon and collecting wet dust by supplying flon into the converter as a cooling gas for the secondary combustion zone in the converter A method for treating chlorofluorocarbon.
(4) In the converter steelmaking process with wet dust collection , by supplying chlorofluorocarbon into the converter as a refractory protection gas in the vicinity of the molten iron discharge port of the converter, the chlorofluorocarbon is decomposed and wet dust collection is performed. A method for treating CFCs.
(5) In converter steelmaking with wet dust collection , by supplying chlorofluorocarbon into the converter as a reforming gas for recovering the sensible heat of the exhaust gas generated from the converter , the chlorofluorocarbon is decomposed and wet collection is performed. A method for treating CFCs, characterized by dusting .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The chlorofluorocarbon in the present invention is chlorofluorocarbon gas that is generally said to destroy the ozone layer, specifically, chlorofluorocarbon 11 (CCl ₃ F), chlorofluorocarbon 12 (CCl ₂ F ₂ ), and chlorofluorocarbon 113 (C ₂ Cl). ₃ F ₃ ), CFC 22 (CHClF ₂ ) and the like, but not limited thereto. In this way, chlorofluorocarbons are substances mainly composed of carbon, fluorine, and chlorine, and are generally used as refrigerants (refrigerant chlorofluorocarbons) in refrigerators and foaming materials (heat-insulating chlorofluorocarbons) for heat insulation typified by foamed urethane. These are also within the scope of the present invention.
[0007]
An outline of a normal converter is shown in FIG. A bottom blowing nozzle 1 is installed, and gas for stirring or refining purposes such as oxygen and carbon dioxide gas is blown from the nozzle. In particular, when oxygen is blown, expensive LPG is generally used as a cooling gas. In the converter 2, pure oxygen is sprayed from the main lance 3 onto the surface of the molten iron and decarburization refining is performed. The gas generated at this time is collected together with dust by the OG type wet dust collector 4.
[0008]
Secondary combustion occurs in the furnace, and if this degree is large, the refractories in the converter, particularly the bricks in the inclined part, are worn out. Moreover, the refractory material at the discharge port (outlet port) 5 for molten iron is also easily worn.
[0009]
The exhaust gas generated from the converter exceeds 1000 ° C., and the sensible heat of the exhaust gas is a drawback in terms of thermal efficiency as well as the heat load of the OG equipment.
[0010]
A process flow showing an example of the embodiment of the present invention is shown in FIGS.
[0011]
The inventors of the present application conducted an experiment using chlorofluorocarbon using the converter shown in FIG. 1 above, and the converter furnace was at a high temperature exceeding 1000 ° C. and was a wet dust collection system. It was found that chlorofluorocarbons were reliably decomposed and dioxins were not produced.
[0012]
This chlorofluorocarbon can be used as an alternative to the bottom blower tuyerium cooling gas of the converter, and its heat of decomposition is 3.5 times larger than that of LPG that is normally used. The cost of purchasing expensive LPG can be reduced.
[0013]
In addition, if chlorofluorocarbon is supplied to the sublance 6 and the furnace port as a cooling gas for the in-furnace secondary combustion zone of the converter, the secondary combustion in the furnace is caused by the heat absorbed by the reaction between the decomposition heat and CO ₂ + C = 2CO. The belt ambient temperature could be reduced. This endothermic action contributes to the extension of the refractory life in the furnace near the furnace port.
[0014]
Furthermore, it is also possible to use chlorofluorocarbon as a refractory protecting gas in the vicinity of the molten iron discharge port 5 of the converter. In particular, in the melting method of iron-containing cold material using a converter, the above-mentioned molten iron discharge port was greatly worn, but by introducing Freon from the outside to the inside of the furnace, the wear of this molten iron discharge port was greatly reduced. .
[0015]
It can also be used as a reforming gas from the furnace port to the flue for the purpose of recovering sensible heat of the exhaust gas generated from the converter by the same action as the cooling of the secondary combustion zone described above. The endothermic heat associated with the reaction of CFC decomposition and CO ₂ + C = 2CO reduces the sensible heat of the exhaust gas, generates CO gas, and increases the latent heat (heat generation amount) of the exhaust gas. Therefore, the value of the converter recovered gas (LDG) is improved and it contributes to the reduction of energy (for example, heavy oil) purchased at the steelworks.
[0016]
[Example 1]
110 tons of hot metal was decarburized and blown using an upper-bottom blow converter with a scale of 110 tons. Top blowing oxygen flow 19000Nm ³ / hr, bottom-blown oxygen flow rate 1000 Nm ³ / hr, a bottom-blown oxygen nozzle Freon 20 Nm ³ / hr from the periphery of the slit was supplied. The blowing time was 15 minutes, and no abnormality was found around the bottom blowing nozzle. As a result, the amount of LPG used could be reduced by 20 Nm ³ per blowing for 15 minutes. Moreover, since wet dust collection was performed, the dioxin concentration in the fuel gas was less than 0.1 ng / Nm ³ , which is no problem.
[0017]
[Example 2]
Iron-containing cold material, secondary material, carbonaceous material, and oxygen are supplied to a 200-ton-scale melting converter in which seed hot water and seed hot metal exist, and the iron-containing cold material is carburized (carburized) to melt high carbon molten iron and hot metal. In addition, a part of the high-carbon molten iron is left in the furnace at the time of tapping in the inversion furnace and used as seed water for the next iron-containing cold material carburizing and melting operation. In the melting method of the iron-containing cold material of the continuous residual hot metal residue system used as the seed hot metal for the next iron-containing cold material carburizing and melting operation, the iron dust scattering suppression hot metal, sometimes leaving a part of the hot metal in the furnace, The melting operation was carried out using 58 tonnes of scrap as the iron-containing cold material for raw fuel and 11500 kg of pulverized coal as the fuel carbon material. The seed hot water (residual hot water), the seed hot metal (residual hot metal), and the amount of discharged hot water in this operation were 84 tons, 10 tons and 55 tons, respectively. As auxiliary agents, 1070 kg of lime (CaO), 390 kg of magnesia (MgO), and 160 kg of aluminum ash briquette were supplied to adjust the hot metal composition at the completion of melting of the iron-containing cold material. Oxygen was supplied at 9350 Nm ³ .
[0018]
At this time, Freon was supplied from the outside of the molten iron discharge port of the converter into the furnace at a flow rate of 100 Nm ³ / hr.
[0019]
When the above operation was repeated and the operation method using no chlorofluorocarbon was compared with this example, the wear of the molten iron discharge port was reduced by 45%. Moreover, since wet dust collection was performed, the dioxin concentration in the fuel gas was less than 0.1 ng / Nm ³ , which is no problem.
[0020]
【The invention's effect】
The present invention not only provides a treatment for detoxifying chlorofluorocarbons, but also a method that greatly contributes to reducing iron production costs, such as replacement of expensive hydrocarbon gas, extending the life of furnace refractories, and improving the quality of recovered gas. It can be provided and has industrially superior characteristics.
[Brief description of the drawings]
FIG. 1 is a diagram showing a normal converter facility.
FIG. 2 is a process flow showing an example of an embodiment of the present invention.
FIG. 3 is a process flow showing an example of an embodiment of the present invention.
FIG. 4 is a process flow showing an example of an embodiment of the present invention.
[Figure 5]
It is a process flow which shows an example of embodiment of this invention.
[Explanation of symbols]
1 Bottom blowing nozzle 2 Converter 3 Top blowing lance 4 Wet dust collection equipment (OG)
5 Molten iron outlet 6 Sublance

Claims (5)

In the converter steelmaking method which has wet dust collection , the flon is decomposed | disassembled and wet dust collection is carried out by supplying the Freon as the cooling gas of a converter into the converter, and carrying out wet dust collection . In a converter steelmaking method having wet dust collection , flon is decomposed and wet dust collected by supplying flon into the converter as a gas for cooling the bottom blowing tuyeres of the converter. Processing method. In the converter steelmaking method having wet dust collection , the flon is decomposed and wet dust is collected by supplying chlorofluorocarbon into the converter as a cooling gas for the secondary combustion zone in the converter. How to treat chlorofluorocarbons. In converter steelmaking with wet dust collection, chlorofluorocarbon is decomposed and wet dust collected by supplying chlorofluorocarbon into the converter as a refractory protection gas in the vicinity of the molten iron discharge port of the converter. And chlorofluorocarbon processing method. In converter steelmaking with wet dust collection, dissociating flon and collecting wet dust by supplying flon into the converter as a reforming gas that recovers sensible heat of exhaust gas generated from the converter A method for treating chlorofluorocarbon.

Images