Life Cycle Assessment On Industrial Sludge Drying And Co-combustion With Coal

With the principle of “reduction, harmlessness, recycling and stabilization” was come up with, the problem that disposing industrial wastewater efficiently and harmlessly was an important project. This thesis analyzed industrial sludge drying-co-combustion cost, energy consumption and environmental impact by using life cycle assessment and co-combustion(paper sludge and Indonesian bituminous coal) experiments, in order that provided theoretical guidance for power generation enterprises to disposing industrial wastewater environmentally and economically.This paper adopted twenty-three kinds of schemes, consisted of direct-drying-co-co-mbustion, indirect-drying-co-combustion, direct-drying-landfill, indirect-drying-landfill and non-drying-co-combustion. Through analysis of life cycle cost(LCC), following conclusions were formed: When the initial moisture content exceeds W(60%) and other drying conditions were the same, LCC was ranked below: indirect-drying-co-combustion< direct-drying-co-combustion. When the initial moisture of sludge below 65%, LCC of non-drying-co-combustion was the lowest than other drying-co-combustion schemes. LCC of drying-landfill was about a half of drying-co-combustion.This paper studied co-combustion characteristics of sludge and coal in diverse burning temperature and different maxing ratios. Thermogravimetric experiment indicated following discoveries: DTG of Indonesian bituminous coal existed one wave crest and the average burning rate is relatively high; While DTG of paper sludge existed two apparent wave crests, each wave crest came from volatiles burning and fixed carbon burning, respectively; From the co-combustion rule of DG and DTG, it is drawn a conclusion that the blend possesses relative linear superposition, but the kindling point is in advance, the burnout temperature increases, combustion time is longer, all combustibility parameters decrease. Blend of paper sludge and Indonesian bituminous coal is more suitable for CFB burning. Flue gas analysis experiment showed that Indonesian bituminous coal tended to generated NO/NOX more easily under medium temperature at approximately 900℃, the amount of organic sulfur in volatile is greater than that in solid particle, higher burning temperature is appropriate for generating more SO2; Under the co-combustion temperature of 1100℃, NO/NOX emission curve existed one wave crest, SO2 emission curve existed two wave crests; As the proportion of sludge in blend increased, NO/NOX emission decreased, but SO2 emission and generation speed increased; Ca O could lower down SO2 emission, but could not restrain NO/NOX emission; With the mixing amount of Ca O linear increasing, the inhibitory effect weakened. Co-combustion confirmed that the emission of N and S would not mak a difference on desulfurization and denitration.The entire life of industrial sludge drying and co-combustion with coal was evaluated to identify and quantify the energy requirements and environmental impact loading in this paper. The life-cycle assessment(LCA) consisted of wet sludge transportation stage, the drying-co-combustion operation stage and equipment reconstruction stage. Analytical results revealed that the drying-co-combustion operation stage consumed the most primary energy and discharged the most pollutants; Energy consumption come from coal and electric power, which depend on the amount of drying moisture. Coal is the main body of resource consumption, and the weighted resource consumption is still coal. The total environmental impact potential of two drying-co-combustion schemes were 8.357 PET2010 and 4.98 PET2010(person equivalents, targeted, in 2010), and the effect of photochemical ozone formation(PO) and solid waste(SW) were the most serious among all calculated category impacts.