Experimental Study On Combustion And Kinetic Characteristics Of Sludge And Its Mixture With Coal

Energy is a major guarantee of human survival and development, and also theengine and the ultimate power of the social and economic development. As thedevelopment of economy, global energy consumption rises rapidly and the competitionincreases fiercely which results in the contradiction between energy supply and demand.Energy resources are limited in our country. So energy diversification is the new trendsin the development and utilization of energy. Meanwhile, it is the most significantproblem that we need to develop new energy and utilize the resources.As the acceleration of urbanization and industrialization, the municipal andindustrial sewage emissions continue to increase and the treatment rate are improved.The increasing of the sludge production promotes the strict requirements in the modernequipment and the scale of sewage treatment. Meanwhile, it is a challenge of dealingwith the sludge especially how to dispose the large amount of sludge in order toreduction, innocuity and resource.The Jiguanshi sludge from the largest waste water treatment plant in the southeast,Banan domestic sludge and the local inferior coal were investigated in this paper. Andthe DTA （Differential Thermal Analysis） and TGA （Thermal Gravimetric Analysis）method were used to study the combustion performances and the dynamiccharacteristics among sludge, coal and their mixture. Particularly the sludge mixingratio, oxygen concentration, sludge and coal particle size and catalysts influencing onthe characteristics of mixed burning and dynamic were focused. The experimentalresults show that a huge diversity exists in the physical properties between coal andsludge or different sludge. There are two weightlessness peaks in the sludge combustionwhile there is only one in the combustion of coal. When the mixing ratio in the mixedburning between inferior coal and domestic sludge is very low, both of them promotemutually the combustion process. As the growth of mixing ratio, it reflects the relativeindependence. The oxygen concentration has a positive effect on combustion whichresults in the increase of the weightlessness, activation energy and frequency factors, etc.Particle size influences the heat diffusion and the discharge of generation. And it is easyto burn for smaller particle size. Additionally adding catalysts can reduce the activationenergy and increase the frequency factors.In addition, the combustion characteristics of sludge and coal in a fixed bed and the characteristics of the flue gas were investigated especially the influence of mixing ratioand oxygen concentration through the fixed bed system and the flue gas analyzer. Theexperimental results indicate that combustion ignition temperature drops, intensityslows down and the burning time increases with increasing of mixing ratio. Theemissions of NOx,SO₂andCO₂grow up while the amount ofN₂O decreases. Asthe oxygen concentration jumps, the combustion ignition temperature drops, burningprocess is more severe resulting in the reducing of combustion time. Meanwhile, theemissions of NOx,SO₂andCO₂drop while the amount ofN₂O increases.