Discussion on the use of gas generator to treat light-burning magnesia kiln soot. Director of Magnesium Resource Protection Office of Liaoning Provincial People's Government. Fully Table 1 Distribution of Magnesia Furnace and Kiln in Our Province Light Burning Kiln (number of units) Reburning Kiln (number of computers > electricity) Magnesium furnace (number of units) Haicheng 44823275 Dashiqiao City 220147217 Xiuyan County 4312860 Other areas 7724146 total 1176431498 Because the light-burning sand kiln uses coal as fuel, heats MgCO, generates magnesium oxide, and emits a large amount of smoke and smoke, and the smoke is black. Adding a large number of units, especially polluting the environment, is the crux of the pollution of the magnesium industry.
The proven reserves of magnesite resources in our province have reached 2.5 billion tons, accounting for 85% of the country's total reserves, accounting for about 20% of the world's total reserves. The molecular formula of magnesite is MgC03, which is calcined by helium to form magnesium oxide. The equation is MgC03:Mg0 C02. Because MgO has good temperature resistance, corrosion resistance and low thermal expansion coefficient, it can be made into many varieties of refractory materials, which are widely used in metallurgy, chemical, glass, cement and other industries. Secondly, it is also used in agriculture, animal husbandry, medicine and other industries. In the past two decades, the magnesite industry has achieved considerable development. The company has grown to nearly 400 households. The annual mining ore has reached 14 million tons, and the annual production capacity of various magnesia and manufactured products is around 8 million tons. The output value, profits and taxes of the magnesium industry such as Dashiqiao have accounted for about 1/3 of the city's total. The annual export earnings of the whole industry is around 300 million US dollars, which has become a new growth point for the province's economy.
With the development of the magnesium industry, the problem of environmental damage has become increasingly serious. Dust and smoke emitted from the production process have seriously polluted cities and counties such as Dashiqiao, Haicheng and Xiuyan. According to the data, Dashiqiao City has formed a pollution zone of 28 Fengfang kilometers. When the monthly dustfall is the highest per square kilometer, it will reach 120 tons, endangering the nearby 5 towns, more than 40,000 households, and alkaline dust to make nearby cultivated land. 1.15 million mu, 1100 mu of soil orchard in the orchard. Governments at all levels have taken many measures against the pollution of magnesia enterprises. However, due to technical and financial reasons, the pollution situation has not been resolved, seriously affecting and restricting the development of the local economy. In this regard, through years of theoretical study and work practice in the magnesium industry, the author carried out theoretical calculations and experimental research on the treatment methods of light burnt magnesium kiln dust in our province, proposed a treatment plan, and operated through more than 50 pilot kiln. The verification is as follows: 1. Distribution of pollution in the magnesium industry The pollution in the magnesium industry is mainly from the production of light-burning kiln, re-burning kiln, fused magnesium furnace and raw material crushing, screening, mixing control and pressing. . Among them, the dust emission of furnace and kiln accounts for more than 70% of the total pollution. The distribution of existing furnaces and kiln in our province is shown in Table 1.
Second, light calcined magnesia production process and roasting principle Magnesite calcined to 575 ft or more magnesite began to decompose, as far as 11001C decomposition, complete the formation of loose, chemically active light burnt magnesia (MgO).
3. The thermal efficiency of the light-burning kiln and the placement of the flue gas row are calculated. The chemical structure of the magnesite is MgC3, but the content of MgC03 in the actual ore usually contains 100%.
In actual production, the light burning process is usually carried out in a shaft kiln with a specification of 4.0x3. 5M. Its production capacity is 13 tons/day, and its hourly output is 1 ton of light burnt magnesia. The theoretical consumption of MgC03 ore is calculated. : The molecular weight of magnesium, oxygen and carbon, respectively.
Considering the loss of coarse ore in the production process, the loss coefficient is 5%, so the actual amount of magnesite ore is: 2.1 tons xl.05% = 2.2 tons.
The required heat for the complete decomposition of 2 tons of MgC03: 64 kilojoules of heat is equivalent to the production, the use of high-quality coal heating children is 7000Kcal / kg coal: 186) = 90Kg, the theoretical coal consumption of light burned magnesia is 90kg / ton .
Years of production practice, calcination - tons of MgC3 to generate light burned magnesia consumption of 7000Kcal / kg of coal is generally 330-350 kg, calculated 340 kg, so the actual thermal efficiency of the existing light kiln is only: every 90 kg of coal The amount of flue gas emitted during combustion is as follows: 5. The dust emission status before and after the transformation was monitored by the provincial environmental monitoring center station. The data is shown in Table 2.
Table 2 Monitoring data (a company's 8' light-burning kiln) monitoring project unit monitoring results without installation of gas generators in light kiln installation gas generators light kiln flue gas temperature X220252 ç®… ç®… dust emission concentration mg / Nm36945176 smoke black The degree of the Ringermann level 5<1 s2 emission concentration mg/m3115<80 provincial environmental monitoring center station conclusions are: light burned magnesia kiln equipped with gas generator: Table 3 does not.
Table 3 Comparison of production indexes of light-burning kiln before and after installation of gas generators. Date of installation before installation. Date of production in the second quarter of 2000 (90 days) September-November 2000 (90 days) kiln No. 235 three average 235 three sets of average magnesia Total coal children (tons) 415. According to the Rosin empirical formula, the theoretical smoke volume is obtained: 10, the amount of smoke emitted by coal combustion is: the amount of CO 2 produced when 2 tons of MgC03 is decomposed: the molecular weight of C2 is 44, so We know that the volume of C02 of 44 grams is theoretically produced by one ton of light burnt magnesia. The smoke temperature of the chimney outlet of the light burned magnesia kiln is 200T, and the smoke output after temperature correction is: actual production. The calculation of the smoke output of one ton of light-burned magnesia is 7=26.47% due to the thermal efficiency of the light-burning kiln, and the actual consumption of light-burning magnesia is 340Kg/ton, so the actual smoke output: x=16256.9NmV tons, ie light burn The kiln emits 8128m3 of smoke per hour. For the above calculations, if the treatment of such a large amount of soot is to use the headache, the dust must be removed from the 220. Use gas generator to control the light kiln pollution. Coal combustion becomes gas, instead of coal, it enters the light kiln to calcine MgC03. Coal is gasification
According to the calculation of the amount of flue gas, in order to fully burn the coal and reduce the blackness of the soot, we have repeatedly tested and rectified the structure of the gas generator, and adjusted the gas kiln mouth to make the gas supply more suitable for light burning. The production process requirements of the kiln are to achieve the effect of increasing coal production. (See Fig. 48 for the installation diagram of the light kiln and gas generator.) - 1996 (Industrial kiln air pollutant discharge standard) The minimum standard requirement (200mg/m3).
Installation of the above-mentioned gas generators investment in low gas generator production and installation costs plus labor costs, the total investment of less than 80,000 yuan / Taiwan. The equipment is simple, and the floor space is small, and the treatment effect is remarkable. These advantages can be easily promoted and implemented by using a gas generator to control the light kiln dust.
Coal saving. The statistical production data of the three light-burning kiln after the transformation, such as the calorie kiln with gas generator, is: coal price is calculated at 260 yuan / ton, the equivalent value is 18.2 yuan / ton magnesia . The thermal efficiency has been increased from 26.47% to 33. The use of gas generators has increased the yield of light burnt magnesia. Since the coal combustion is sufficient, the gas flame is uniform, the effect of MgC03 calcination is good, and the calcination cycle in the kiln is shortened, so the yield of the light burned magnesia is improved. Through production comparison, the yield increase rate of light burned magnesia is 147%, which makes the daily output of magnesia in the same type of light-burning kiln increased from 13 tons to 19.1 tons, thus achieving the effect of increasing production, and the kiln can be built less. From this rough calculation, the production of one ton of magnesia can increase the economic benefit by 10 yuan.
Improve the quality of light burnt magnesia products. After the gas generator is used, the heat generation medium is changed, and the magnesite ore is calcined by coal combustion exotherm to become secondary energy gas exothermic calcination. Reduce coal contamination of the magnesite. Therefore, the calcined magnesia produced by the light-burning kiln of the gas generator can increase the MgO content by 1% when the ore grade is unchanged. It not only improves the scope of the ore, but also estimates that the enterprise benefits are also improved. -5 yuan / ton of magnesia.
The comprehensive benefit calculation after the transformation of the light kiln in the province. There are 1,176 light-burning magnesia kiln in our province. According to statistics, there are 650 continuous production, and there are 450 with conditions for gas generator conversion. The working day of each kiln is calculated according to 290 days, and the output of kiln is calculated according to 19 tons. The annual benefit can be increased: 2 yuan / ton + 10 yuan / ton + 4 yuan / ton) = 79.84 million yuan.
80,000 yuan = 36 million yuan The above calculations have been proved by the transformation of more than 50 kiln, not only can the recovery investment costs be recovered in the same year, but also the benefits of more than 43 million yuan. After the second year, the net profit was nearly 80 million yuan. More importantly, the problem of environmental pollution has been solved, the dust emission has been reduced by more than 90%, and the blackness of the smoke has been greatly reduced. The pollution problems that cannot be solved for many years can be discharged to the standard, alleviating the soil compaction and saving a large area of ​​Liaoning Province. Farmland, orchard. Therefore, the use of a gas generator to control the pollution of light burned magnesia kiln is a technically feasible, economical and environmentally beneficial solution. Mouth Consultant: Zhu Xi 1 (former Deputy Governor of Liaoning Province) Fu Xin (Deputy Governor of Liaoning Province) Chairman: Zhong Yiquan (Director of Liaoning Provincial Development Planning Committee) Zhang Heling (Board of Liaoning Venture Group Chairman): Wang Hongtu (Director of Development Research Center of Liaoning Provincial People's Government) Zhang Liao (Deputy Director of Development Research Center of Liaoning Provincial People's Government) Li Shuxiang (Chairman and General Manager of Liaoning Property Group Corporation) Yue Caihua (Manager of Sinopec Liaoning Economic Development Company) Tie Sheng ( Secretary-General of Liaoning Economic Magazine and Editor-in-Chief: Secretary-General: Tiesheng (Director and Editor-in-Chief of Liaoning Economic Magazine) Deputy Secretary-General: Zhang Renyuan (Deputy Editor-in-Chief, Liaoning Economic Magazine) Executive Director: Liu Shua (Northeast Oil Transportation Administration) Director) Guo Zhigui (Secretary of Shenyang Electric Power Bureau): (in no particular order) Fan Zhong (General Manager of Dongfeng Chaoyang Diesel Engine Co., Ltd.) Xu Yongdi (President of China Construction Bank Liaoning Branch) Wang Min (Liaoning Business Vocational College) Long) Chen Li (President of China Construction Bank Shenyang Branch) Liu Zhongcheng (General Manager of Liaoning Key Project Development Company) Chi Yuanjie (Chinese) Li Zhengde, General Manager of Liaoning Branch of Insurance Company (Dean of Liaoning Academy of Agricultural Sciences)ç¥*(Deputy Director of Shenyang Municipal Finance Bureau) Qi Zhikang (General Manager of Shenyang Xingguang Float Glass Company) Xu Jie (Liaoning Provincial Transportation Machinery Manufacturing Co., Ltd. Chairman) Meng Xiangsuo (Director of Shenyang Wire Factory) Bai Naizhi (Head of Shenyang Branch of National Development Bank) Zhao Hengxian (Director of Shenyang Beiling Printing Factory) Liu Yuchun (General Manager of Shenyang Construction and Development Corporation of China Construction Bank) (Continued from 7 pages) ) é“™ é“™ ç ‚ 容 容 容 容 容 容 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 Slightly small gas box light burning S number name unit number
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