Research On Two-stage Drying And Synergetic Incineration Of Municipal Sludge

Sludge treatment has been the area in the spotlight of the industry. This thesis uses Suzhou Industry Park sludge synergetic incineration project as the research subject, the fruitful outcomes have been obtained through the research and analysis on the Two-stage Sludge Drying process system designing, operation and dried sludge products recovery. The main research outcomes are drawn as follow:1. The 1999 days operation result of the Two-stage Sludge Drying process, using drying process and themol electricity plant as assistance, shows that the energy consumption for drying 1 ton of wet sludge(Moisture ratio is larger than 80%) is efficient. The consumption of vapor, electricity and cooling water is 0.63 t, 35.6 kWh and 16.4 t respectfully, which is lower by 28%, 21% and 48% comparing the original designing.2. When the temperature of 1st and 2nd phase of the Two-stage Sludge is respectfully lower than 133℃ and 105℃, the heat of sludge can be efficiently remained and the effulent concentration of COD, TOC, NH4+-N and odor pollutant can be reduced. Meanwhile the pollutant of heavy metal can be accumulated in sludge. When the mix ratio of sludge and coal is 5.8%, related index of released gas, of which dioxin concentration is merely 0.018 ng TEQ/m3, can fulfill the standard; Heavy metal pollutants, including Cu, Ge, Ni, As and etc.,are transferred to flying ashed and slag, the poison test of which shows that both of them are not included to hazardous waste.3. The sludge disposal plant shows great recovery potential during 1999 days operation.By co-combustion of dry sludge and coal in electricity plant, 12,000 tones of standard coal is saved and 9 million yuan revenue is earned from the sale of rest evaporation from electricity plant; 3 million yuan profit is made due to the sale of dry sludge; 66,960 t water is saved due to the reuse of condensated water; Investment in facilities of wastewater treatment is saved because of the internal recycle of water; the reuse of reclaimed water gains 1.2 million yuan for WWTP annually; the flying ash and slag is used as the raw material of construction material.