Design And Research On A Small-sized Continuous Pyrolysis Furnace Of Oily Sludge

Oily sludge in oil field is a kind of dangerous solid waste which is complex and difficult to treat,which causes great harm to the local soil,water system,vegetation and people's health.The pyrolysis method can completely decompose organic matter and solidify heavy metals without secondary pollution,and it has high energy utilization ratio,which realizes harmless treatment of oily sludge.At present,the fluidized bed pyrolysis furnace system is huge and the operation is complex.The sludge in the rotary kiln is easy to bond and hinders the movement of the material.They are not suitable for heat treatment of oily sludge in oil field.In view of the dispersion characteristics of oily sludge in oil field,a small-sized continuous pyrolysis furnace for oily sludge has been developed and optimized.By pyrolysis experiment and thermogravimetric analysis of oily sludge,the pyrolysis temperature is determined at 550?,and the dry sludge reaction heat is 235.26kJ/kg.According to the thermal calculation,a new type pyrolytic furnace is designed.The stress distribution of the key components is calculated,the reliability is analyzed,and the design of transmission and heat preservation are carried out.The new type of pyrolysis furnace has two stage multi return heating structure and realizes countercurrent heat exchange.The spiral thruster is used in the heating section.The self circulating combustion chamber,self sealing import and export structure and water cooled shaft end seal have been designed.The pyrolysis furnace realizes miniaturization,containerization,skid-mounted package,and high heat utilization rate,it achieves continuous harmless treatment of oily sludge in boundary oil areas.According to the basic structure,the convection heat transfer model of the whole pyrolysis furance has been established to simulate the heat transfer process between the flue gas and the sludge through the wall.The structure of the pyrolysis furnace has been optimized.The study shows that there are many heat transfer dead zones after the bow baffle in flue,which causes fluid retention and low heat transfer efficiency.The spiral baffle almost eliminates the recirculation zone,so its heat transfer efficiency is better than the bow baffle.Moreover,under the condition that the pressure drop meets the requirements,the smaller pitch can bring better heat transfer effect.Under the condition that the handling capacity is constant,the larger spiral shaft diameter can bring more uniform sludge temperature.Under the condition that the average flue gas flow rate is no more than 15m/s,the smaller flue diameter can bring more uniform sludge temperature and higher heat transfer efficiency.Based on the amount of flue gas and the length of the thermal insulation section,the length of the heating flue is optimized,and the diameter of the spiral shaft is reduced properly,the heat preservation time of the sludge is increased.The energy efficiency analysis on the optimum furance shows that,if the waste heat of pyrolysis solid slag is not taken into consideration,the amount of flue gas heated at 1099?is 102.6kg/h,so the natural gas consumption is 5.59Nm~3/h,the thermal efficiency of the pyrolysis furnace is 57.6%.After energy efficiency analysis,the optimized structure can effectively improve the thermal efficiency.And the self circulating combustion of the pyrolysis gas can save the recovery system and the external fuel to a certain extent.The research productions of this paper have some guiding significance for the development and design of small-sized continuous oily sludge pyrolysis furnace.