Study On The Catalytic Low-temperature Pyrolysis Of Sludge

The problem of the sewage sludge in domestic city is pressing to the healthy development of the city.Every country in the world is seeking for perfect approach of treatment about sludge.In the past,the sewage sludge is regarded as waste and the people only consider how to dispose it innocuously,but now people discovered that sewage sludge is a kind of resource and consider how to use it reasonably.So the new treatment of the sludge has far-reaching significances.Through the pyrolysis properties and the low-temperature pyrolysis experiments of the sewage sludge which is treated by the Ma Lan He Sewerage Plant,the oil rate under different conditions is obtained and the proper technics conditions for the low-temperature pyrolysis are confirmed.The article introduces the origin,characteristic,harm, sort and the instances of treatment and the disposal overseas at first,and analyzed these technologies of treatment and disposal about sludge.It is concluded that the low-temperature pyrolysis sludge is a developmental potential new technology.The proximate analysis of the sludge indicates that the sludge for the experiments is a kind of resource which has high contents of water,medium contents of volatile and low contents of ash.Through the calculation,it can be concluded that the quantity of heat is 15124.76kJ/kg. The temperature range of the pyrolysis is 150～360℃.The experiments are done to study the influences of different reaction conditions to the oil rate. The conclusions are that:(1)When the reaction temperature is below 270℃,the oil rate increases conspicuously along with the increase of the temperature;when the reaction temperature is above 270℃,the oil rate increases unconspicuously along with the increase of the temperature.Through the analysis,the best reaction temperature is confirmed which is 270℃.(2)There is a time milestone of the reaction balance and the oil rate is the maximal only when the time is around this milestone.The oil rate increases at first and then decreases along with the increase of the time.When the reaction time is 75min,the reaction reachs the balance and the oil rate is the maximal.So it can be concluded that the best reaction time is 75min.(3)The catalyzer of the experiment is Na₂CO₃.In the large dosage range,the influence of the dosage of the catalyzer to the oil rate is studied.With regard to the oil rate and the economic performance,the best dosage of the catalyzer is confirmed which is 4g(per 100g sludge).