Experimental Research And Numerical Analysis On The Low Temperature Pyrolysis Of Oily Sludge

Oily sludge is one of the main pollutants generated in the process of oilfield development and production.If not treated in time,it will become a major pollution affecting the surrounding environment and production area.Pyrolysis technology is a well modified technology with many advantages,and it is one of the main development trends of sludge treatment technology in the world.In this paper,a series of pyrolysis experiments of oily sludge from hazardous waste treatment center and Yanshan Petrochemical Company were carried out,and the composition and physicochemical properties of pyrolysis products were analyzed.The products of pyrolysis reaction were considered and their characteristics were studied.In addition,in order to meet the needs of industrial scale-up,a continuous pyrolysis process and a large-scale pyrolysis industrial equipment were designed,and related operation experiments were carried out.Then,the heat transfer analysis and simulation verification of the equipment were carried out.Thermogravimetric analysis shows that the pyrolysis of sludge has three stages of weight loss,including water evaporation,light oil volatilization and heavy oil cracking.Coats-Redfern approximation is used to calculate the reaction kinetics of sludge,and Origin is used to fit the results linearly to determine the required kinetic parameters in the pyrolysis stage.A series of pyrolysis experiments were carried out in a fixed bed pyrolysis reactor to investigate the different characteristics of gas,liquid and solid three-phase products under oxygen barrier conditions.It was found that:the gas production has high enthalpy values;The pyrolysis oil is mainly composed of linear normal paraffins with good quality;the residue has high carbon content,which can be used as an adsorbent or put into the soil to improve the carbon to nitrogen ratio.The continuous pyrolysis technology was proposed,and the design of each system was carried out according to the process route including:homogenization treatment and feeding system,combustor,sludge drying system,sludge pyrolysis system,condensation and separation system,flue gas treatment system,process inspection and control system.The related pyrolysis test was carried out on the equipment,and it was concluded that the continuous pyrolysis reactor can effectively treat oily sludge.Through the numerical calculation of the heat transfer process in the pyrolysis process of oily sludge,the "particle heat transfer model" proposed by Schlunder was applied to verify the feasibility of pyrolysis treatment of oily sludge,and the relevant thermodynamic parameters were obtained,which provided relevant data support for energy analysis.The process of pyrolysis of the sludge was reproduced by constructing a three-dimensional dynamic model of pyrolysis of the sludge in the reactor.By analyzing the concentration field of reactants and products,it was concluded that the geometric model and grid system of this paper are reasonable,and the numerical method adopted is correct,which can simulate the actual situation.