Msw Direct Gasification And Melting Incineration Technology Pilot Study

With the increasing development of urbanization, our cities are under threat of being surrounded by municipal solid waste (MSW) . In China, the annual output of MSW has already reached to 15 million tons, and still increased yearly at the rate of 7-10%. So it is extremely important for MSW treatment to limit the quantity, reduce the volume and lower the toxicity. This paper integrated and expanded the present conditions and technologies of MSW treatment that were introduced in a great deal of references at home and abroad. On the above basis, we presented the technology of direct gasification and melting MSW incineration, then discussed the properties of MSW, the process of direct gasification and melting incineration, the basic principles of regeneration and recovery of melting slag and the developmental trend of MSW treatment.Firstly, we surveyed and analyzed on municipal solid waste from Kunming City. The results showed that: (1) the annual output of MSW in the city is about 752.8 thousand tons, and the annual average rate of increasing is 9.4%, which approached to the national level. (2) MSW had a high water content of 40%, and the moisture varied with climate, seasons and areas. (3) the organic matter represented for combustible substance in MSW was above 60%, and the low thermal value approached 4500kJ/kg.Secondly, it was studied on the melting experiments on the mixture of incineration slag and coal, and direct gasification and melting incineration of MSW, respectively. The results showed that the technology of direct gasification and melting incineration was a more advanced incineration technology of MSW, which can realize the goal of limiting the quantity, reducing the volume and lowering the toxicity to the extent. In the process of direct gasification and melting incineration, the temperature at the top and bottom of furnace chamber was 1196 癈 and 1328 癈, respectively. And the effective utilization ratio of thermal energy was about 40.9%. For certain direct gasification and melting incineration furnace, we could improve the treatment capacity of the furnace as well as decrease the quantity of auxiliary fuels. In addition, the low thermal value of MSW should be not less than 5000 kJ/kg in order to stabilize the process of direct gasification and melting incineration. As to the melting temperature, it depended on slag composition. The slag was mainly composed of the four-component system of SiO2-Al2O3-CaO-Fe2O3. Through the process of direct gasification and melting incineration, the rate thermal decay remaining melting slag was close to zero, and heavy metals could not be lixiviated from the slag. The content of dioxins was only 0.0049ngTEQ/g, and the decomposition rate reached 99.93%, so a harmless IItreatment on MSW was realized through our technology. Since the temperature in the process of direct gasification and melting incineration was above 1300C and the resistance time of the fume was more than 2s, so the dioxins in the fume was decomposed completely. At the same time, the discharge rate of harmful matter from incineration furnace was deceased.At last, it was studied that the melting slag of municipal solid waste was used as the main raw materials of cement pavement brick. The prepared pavement brick was characteristic of good physical and mechanic properties, which totally meet to the request of Concrete Pavement Brick (JC446-91). By this means, the melting slag could be recovered as useful recourses.In conclusion, direct gasification and melting MSW incineration is one zero-discharge technology of MSW treatment, and it could promote the development of MSW treatment technologies.