Fundamental Study On Pyrolysis Of Oily Sludge In The Circulating Fluidized Bed

The oily sludge produced in the process of oil exploitation and refining will cause waste of resources and environmental pollution.The oil and gas resources can be recovered by the double circulation fluidized bed technology of oil sludge pyrolysis-residue combustion,the solid residue produced by pyrolysis can also be used as fuel to directly enter the combustion furnace for combustion to provide energy for the solid heat carrier,the heated solid heat carrier can return to the pyrolysis furnace to continue pyrolysis of oil sludge,which reduces the energy consumption of the whole pyrolysis system,prevents secondary pollution,and realizes the resource utilization and advanced treatment of oily sludge.Therefore,fundamental study on pyrolysis of oily sludge in circulating fluidized bed was carried out in this thesis.Firstly,the basic physical properties and pyrolysis mechanism of oily sludge were obtained by industrial analyzer and thermogravimetric analyzer.The results show that the pyrolysis of oily sludge can be divided into four stages:drying,light oil volatilization,heavy oil pyrolysis,semi-coking and mineral decomposition.Secondly,the pyrolysis behavior of oily sludge was analyzed in a fixed bed reactor,the effects of pyrolysis temperature,residence time and particle size on products distribution were obtained.when the pyrolysis temperature is 550?,the maximum yield of liquid-phase products is 18.5 wt%,when the temperature is over 550?,the yield of liquid-phase products shows a downward trend;with the increase of residence time,the yield of gas-phase products increases gradually,and the yield of liquid-phase products does not increase after the residence time exceeds 60 min;with the increase of particle size from 0.25 mm to 6 mm,the yields of products in liquid phase and gas phase decreased by 2.4 wt%and 1.9 wt%,respectively.The larger the particle size,the more significant the effect on the yield distribution of pyrolysis products.The content of volatile matter in the solid residue after pyrolysis of oily sludge decreases with the increase of pyrolysis temperature,the increase of residence time and the decrease of particle size.The viscosity of pyrolysis oil is similar to that of diesel oil,the content of C and H elements is higher,and the calorific value is higher;the total content of hydrogen,methane and other hydrocarbons and alkynes in the pyrolysis gas is high.Finally,the fluidization characteristics of binary mixtures were analyzed in fluidized bed,the mixing and segregation laws of binary mixtures with different mass fraction were obtained.The results show that initial filling modes of binary ash with different sizes will have an effect on the fluidization process of increasing velocity;the begin fluidization velocity of binary mixtures does not change much when the mass ratio of the coarse particles is lower than 60%,it will increase rapidly when the mass ratio of the coarse particles is higher than 60%,while the complete fluidization velocity changes much when the mass ratio of coarse particles is lower than 20%,and increases little when the mass ratio of coarse particles is higher than 20%.