The silicon carbide smelting process produces several harmful gases, mainly including carbon monoxide (CO) derived from basic chemical reactions in smelting furnaces, sulfur dioxide (SO2) produced by wood chips and coke, hydrogen sulfide (H2S), and methyl mercaptan (CH3SH).
Carbon monoxide is a colorless, odorless, odorless and toxic gas. When the content of carbon monoxide in the air is 0.16%~0.2%, people will be poisoned and died after 1~1.5h. When the concentration increases to more than 0.5%, people will die after 15min.
Sulfur dioxide is an odorous, suffocating colorless gas. When the concentration is 0.000006~0.000012, it can cause nasal and pharyngeal irritative reactions. At high concentrations, it can cause bronchitis and even death.
Hydrogen sulfide and methyl mercaptan are damaging substances. The odor threshold of hydrogen sulfide is 0.0047×10-6, which has a rotten egg flavor. The olfactory threshold of methyl mercaptan is 0.0021 x 10-6 with a pungent sulphur taste. Therefore, even if they enter the environment in a small amount, they will make people feel uncomfortable, and have symptoms such as headache, nausea, loss of appetite and lack of concentration. Hydrogen sulfide can also cause conjunctivitis of the eye and be absorbed by the gastrointestinal tract. When it enters the blood, it partially combines with hemoglobin to form non-reducible sulphur hemoglobin, which can cause symptoms of poisoning.
Ministry of Health, State Construction Commission, State Planning Commission, State Economic Commission, State Labor Administration issued on September 30, 1979, "Industrial Enterprise Design Hygiene Standards" (TJ36-79), implemented on November 1, 1979, for the concentration of harmful substances The regulations (Table 2-11-1 and Table 2-11-2).
Table 2-11-1 Maximum allowable concentration of harmful substances in the air of the workshop (Excerpt)
Toxic substance carbon monoxide carbon dioxide hydrogen sulfide maximum allowable concentration (mg/m3) 30 15 10
Table 2-11-2 Maximum allowable concentration of atmospheric harmful substances in residential areas Material name carbon monoxide sulfur dioxide hydrogen sulfide Maximum allowable concentration (mg/m3) Once 3.00 0.50 0.01
Daily average 0.5 0.15
There is no standard for the maximum allowable concentration of methyl mercaptan in Japan, and the Japanese standard is 0.002×10-6.
The maximum allowable concentration in Table 2-11-2 refers to the maximum allowable value of any one measurement result. Daily average maximum allowable concentration refers to the maximum allowable value of the average concentration of any day. The inspection method shall be carried out in accordance with the current “Atmospheric Monitoring and Inspection Method†approved by the Ministry of Health.
The State Planning Commission, the State Construction Commission, and the “Trial of Industrial “Three Wastes†Emission Standards (GBJ4-73) approved by the Ministry of Health of the People's Republic of China stipulate the discharge of 13 types of hazardous substances, and the relevant parts are recorded in Table 2-11-3. .
The carbon monoxide gas escaping from the silicon carbide furnace is dispersed in the smelting room after being burned on the surface of the furnace, and is continuously dissipated outward. The concentration of carbon monoxide and sulfur dioxide in the smelting room for natural ventilation of the fixed furnace was measured. The results are shown in Table 2-11-4. It can be seen from the table that the concentration of carbon monoxide exceeds the requirements of Table 2-11-1, and the sulfur dioxide is below the standard.
Table 2-11-3 Emission standards for 13 hazardous substances (excerpt)
Hazardous Substance Name Hazardous Substance Enterprise 1 Emission Standard Exhaust Cylinder Height (m) Emissions (kg/h) 2
Sulfur dioxide power station 30456080100120150 82170310650120017002400
Metallurgy 30456080100120 52911423450670
Chemical 30456080100 3466110190280
Hydrogen sulfide chemical industry, light industry 20406080100120 1.33.87.6131927
Carbon monoxide chemical, metallurgy 3060100 1606201700
Note: 1 indicates that the unlisted enterprises can refer to similar enterprises in this table for their emissions of harmful substances.
2 The data listed in the table is connected to the plain area, the atmosphere is neutral, and the point source is continuously discharged. For intermittent emitters, if they are discharged several times a day, their emissions are as specified in the table; if they are discharged once a day and less than 1 hour, the emissions of sulfur dioxide, carbon monoxide and other seven substances can be three times the amount specified in the table.
Table 2-11-4 Measured concentration of harmful gases in silicon carbide smelting workshop CO concentration in air (mg/m3) SO2 concentration in air Furnace over the furnace, crane cab 93~112 5.41~5.86
Crane beam 61~72.3 4.19~4.72
On the crane track, the downwind side 117~190 13.66~11.87
On the furnace, 2m high 67~81 2.85~3.12
The furnace wall is empty, 2m above the furnace wall 45~402.4 2.218~9.358
Carbon monoxide is a colorless, odorless, odorless and toxic gas. When the content of carbon monoxide in the air is 0.16%~0.2%, people will be poisoned and died after 1~1.5h. When the concentration increases to more than 0.5%, people will die after 15min.
Sulfur dioxide is an odorous, suffocating colorless gas. When the concentration is 0.000006~0.000012, it can cause nasal and pharyngeal irritative reactions. At high concentrations, it can cause bronchitis and even death.
Hydrogen sulfide and methyl mercaptan are damaging substances. The odor threshold of hydrogen sulfide is 0.0047×10-6, which has a rotten egg flavor. The olfactory threshold of methyl mercaptan is 0.0021 x 10-6 with a pungent sulphur taste. Therefore, even if they enter the environment in a small amount, they will make people feel uncomfortable, and have symptoms such as headache, nausea, loss of appetite and lack of concentration. Hydrogen sulfide can also cause conjunctivitis of the eye and be absorbed by the gastrointestinal tract. When it enters the blood, it partially combines with hemoglobin to form non-reducible sulphur hemoglobin, which can cause symptoms of poisoning.
Ministry of Health, State Construction Commission, State Planning Commission, State Economic Commission, State Labor Administration issued on September 30, 1979, "Industrial Enterprise Design Hygiene Standards" (TJ36-79), implemented on November 1, 1979, for the concentration of harmful substances The regulations (Table 2-11-1 and Table 2-11-2).
Table 2-11-1 Maximum allowable concentration of harmful substances in the air of the workshop (Excerpt)
Toxic substance carbon monoxide carbon dioxide hydrogen sulfide maximum allowable concentration (mg/m3) 30 15 10
Table 2-11-2 Maximum allowable concentration of atmospheric harmful substances in residential areas Material name carbon monoxide sulfur dioxide hydrogen sulfide Maximum allowable concentration (mg/m3) Once 3.00 0.50 0.01
Daily average 0.5 0.15
There is no standard for the maximum allowable concentration of methyl mercaptan in Japan, and the Japanese standard is 0.002×10-6.
The maximum allowable concentration in Table 2-11-2 refers to the maximum allowable value of any one measurement result. Daily average maximum allowable concentration refers to the maximum allowable value of the average concentration of any day. The inspection method shall be carried out in accordance with the current “Atmospheric Monitoring and Inspection Method†approved by the Ministry of Health.
The State Planning Commission, the State Construction Commission, and the “Trial of Industrial “Three Wastes†Emission Standards (GBJ4-73) approved by the Ministry of Health of the People's Republic of China stipulate the discharge of 13 types of hazardous substances, and the relevant parts are recorded in Table 2-11-3. .
The carbon monoxide gas escaping from the silicon carbide furnace is dispersed in the smelting room after being burned on the surface of the furnace, and is continuously dissipated outward. The concentration of carbon monoxide and sulfur dioxide in the smelting room for natural ventilation of the fixed furnace was measured. The results are shown in Table 2-11-4. It can be seen from the table that the concentration of carbon monoxide exceeds the requirements of Table 2-11-1, and the sulfur dioxide is below the standard.
Table 2-11-3 Emission standards for 13 hazardous substances (excerpt)
Hazardous Substance Name Hazardous Substance Enterprise 1 Emission Standard Exhaust Cylinder Height (m) Emissions (kg/h) 2
Sulfur dioxide power station 30456080100120150 82170310650120017002400
Metallurgy 30456080100120 52911423450670
Chemical 30456080100 3466110190280
Hydrogen sulfide chemical industry, light industry 20406080100120 1.33.87.6131927
Carbon monoxide chemical, metallurgy 3060100 1606201700
Note: 1 indicates that the unlisted enterprises can refer to similar enterprises in this table for their emissions of harmful substances.
2 The data listed in the table is connected to the plain area, the atmosphere is neutral, and the point source is continuously discharged. For intermittent emitters, if they are discharged several times a day, their emissions are as specified in the table; if they are discharged once a day and less than 1 hour, the emissions of sulfur dioxide, carbon monoxide and other seven substances can be three times the amount specified in the table.
Table 2-11-4 Measured concentration of harmful gases in silicon carbide smelting workshop CO concentration in air (mg/m3) SO2 concentration in air Furnace over the furnace, crane cab 93~112 5.41~5.86
Crane beam 61~72.3 4.19~4.72
On the crane track, the downwind side 117~190 13.66~11.87
On the furnace, 2m high 67~81 2.85~3.12
The furnace wall is empty, 2m above the furnace wall 45~402.4 2.218~9.358
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