Preparation Of Slurry Fuel Based On Municipal Sewage Sludge And Coal

Municipal sludge is the solid waste produced in the process of municipal domestic sewage treatment.The coal-sludge slurry are prepared from municipal sludge and coal,which is an important way to realize the utilization of municipal sludge for clean fuel or raw material for gasification.The characteristics,reaction performance and slurry-ability of municipal sludge conditioned by semi-coke(SS)is studied,and a new method of preparation of coal-sludge slurry from municipal sludge and coal is created in this paper.The main contents and conclusions were as follow:In order to reveal the effect of semi-coke addition on the combustion characteristics of the mixtures from semi-coke and municipal sludge has been investigated by thermo-gravimetric analysis.The results indicated that the combustion performance of the mixtures from semi-coke and municipal sludge become batter with the increase of the ratio of semi-coke,which shows that semi-coke can improve the combustion performance of municipal sludge.When the ratio of semi-coke greater than 40%,the combustion fingerprint(DTG)curve of the mixture display a single peak,which indicates that have better combustion performance.The reaction performance of the mixtures from SS and coal has been investigated by thermo-gravimetric analysis.The results indicate that the F of coal could be viewed as a key effect factor for the combustion performance of the blend by SS and coal,with the decreasing fuel ratio of coal,the combustion performance of the blend became better.When the F of coal is less than 2.53%,the combustion fingerprint curve of the blend display a single peak,which indicates that have better combustion performance.The slurry-ability of municipal sludge conditioned by semi-coke was investigated by slurry performance experiment.The results show that the ratio of semi-coke could be viewed as a key effect factor for the slurry-ability of conditioned sludge and the slurry-ability of conditioned sludge improves with increasing ratio of semi-coke.When the ratio of semi-coke was greater than 80%,the slurry concentration of conditioned sludge was still merely 33.88%,which suggests the quality of the slurry is not satisfactory.It is necessary to prepare the coal-sludge slurry with better performance by blended with SS and the coal with fine slurry-ability.The coal-sludge slurry could meet the three state quality standards of coal water slurry.A new method of preparation of coal-sludge slurry from municipal sludge and coal was established,which was based on the characteristics of municipal sludge conditioned by semi-coke.First,the municipal sludge is conditioned by semi-coke.Then,the municipal sludge is concentrated dewatering by using Gravity concentration dehydration.Finally,the municipal sludge conditioned by semi-coke was obtained,which can directly blend with coal to prepare coal-sludge slurry.The characteristic of the new method not only make municipal sludge dispense with mechanical dewatering and drying but also simplify the preparation process of coal-sludge slurry,which would dropped the cost of the preparation.The new method has a great significance to save resources and protect environment.The coal-sludge slurry is prepared to reach the three state quality standards of coal water slurry that must be have some technical conditions as follow:(1)The coal should have good slurry-ability and the inherent moisture of coal should be less than 5.32%;(2)The particles size is less than 74 ? m should be accounted for 75% in the size composition of the materials;(3)The naphthalene NF is used as additive of coal-sludge slurry,and the addition of it is 1% on the total weigh of slurry;(4)The weight fraction of conditioned sludge should be less than 7.72% of the total weigh of coal and conditioned sludge.