Research On The Co-Combustion Characteristics Of Pulverized Coal And Sewage Sludge Catalyzed By Metal Salt

Sewage sludge is by-product generated from municipal wastewater treatment plant, andone of the main sources of Chinese municipal solid wastes. Co-combustion of dry sewagesludge and load-metal salts coal as a new method, which is not only effective way to settlethis problem, but achieve the value of resource utilization.With thermogravimetric apparatusand gas analyzer for the combustion of dry sludge, metal salts-loade coal.The effect metal saltspecies, the catalyst loading, sludge/coal ratio on co-combustion characteristics, pollutionemission and the reaction kinetics were analyzed.The results of the experiments of combustion loaded metal salts show that: K, Na, Ca,Mg can improve the combustibility of pulverized coal, Fe in the coal exerts a negligibleinfluence on the coal combustion. The ignition temperature and comprehensive combustionindex decrease with increasing K, Na, Ca, Mg loading. The coal catalytic combustion has theoptimum loading amount of metal salts.The results of the co-combustion of sludge combined with loaded metal salts show that:With increasing the sludge/coal ratio, improving the combustibility of samples, the ignitiontemperature decreased. When the mixing ratio of sludge is more than 40%, Ti of samples isdecreased significantly. Which the loading amount of Fe, the ignition temperature reducingthe most 157℃.The Na-loaded coal with the sludge, when the mixing ratio of sludge is 10%,20%, the optimum of comprehensive combustion index.According to the Coats-Redfern equation, the most probable kinetic function of thecombustion of samples: cylindrical symmetric of the phase boundary reaction, sphericalsymmetry the phase boundary reaction, reaction order was n=1. The apparent activationenergy and frequency factor were calculated, the apparent activation energy increased withdeepen reaction degree.The results of the contaminant emission characteristics of sample s show that: the loadingof K, Na, Fe can increase NO emission of the pulverized coal. With the loading amountincreased, get a better catalytic effect. The NO emission was inhibited, when the loading amount of Ca was 162mg/g coal, the loading amount of Mg was 74.4mg/g coal. The NOemission increased with increasing the sludge/coal ratio, broaden the peak width. The less NOemission of Mg-loaded coal with sludge, which were beneficial to the Mg can reduce NOemissions from coal.Based on the combustion and pollutant emission, the optimum conditionwas the mixing ratio of sludge is 10%, which loading Mg.