Experimental Research On The Characteristics Of Waste Incineration On The Grate And Analysis On The Low-NO_x Combustion Technology

With the development of society, the amount of MSW(Municipal Solid Waste) generated is increasing every year. Landfill is a traditional way to dispose waste. While in large city land resource is limited, waste incineration as an alternative technique has a very promising future. Waste incineration started late in China and grate incineration as a main disposal combustion way is mainly introduced from foreign countries in China. But due to the difference between foreign and domestic waste composition and calorific value, the introduction of technology for the treatment of waste does not work well. This paper based on grate furnace technology, did research on the bed combustion characteristics and NOx emission characteristics, and analyzed the advanced low NOx technology and discussed its adaptability to deal with the waste in China.In order to study the combustion characteristics of waste on the grate and the layer combustion system was built. Wood and cardboard were choosen as the simulated waste and the layer combustion temperature distribution, mass lost and gas compostion above the bed were studied. Studies showed that the samples in the process of combustion can be divided into two stages: the propagation of ignition front stage and the char burnout stage.In a certain range, improving the air flowrates can improve the propagation speed of ignition front and weight loss rate, etc., while reduce the gas concentration(such as CO, CH4, etc.). The characteristics of mixture of wood and cardboard in combustion are between wood and cardboard combustion alone.In order to study the emission characteristics of waste incineration, the multi-function low NOx combustion system was used. This article studied at a fixed Secondary air how the primary air flowrates influenced the NOx emission characteristics of wood and cardboard, and compared the differences between one-component and mixure. Results show that, under the operating conditions selected in this article, NOx emission of wood increased with the air flowrates and then reached a peak, while the NOx formation of cardboard first decreased with the air flowrates and then increased to a stable value. Mixture combustion promoted the formation of NOx.In order to study the combustion characteristic of real life waste, mixture of 10% polyethylene, 50% cardboard and 40% dehydrated cabbage were used to simulate the composition of waste. Studies showed that the simulated waste in the process of combustion can be divided into two stages: the propagation of ignition front stage and the char burnout stage. NOx emission of the simulated waste increased with the air flowrates and then reached a stable value.Based on the conclusions of this article, the traditional waste incineration technology and the advanced low NOx incineration technology, such as VLN technology, CUT-NOx technology and JFE technology were analysed. Analysis showed that although low NOx incineration technology used different means, but all these technologies reduced the excess air coefficient of main combustion zone, at the same time ensuring a stable combustion and burntout of ash. VLN and JFE technology had a good adaptability to deal with the waste in China.