Experiment On Oilfield Wastewater Treatment By Submerged Combustion Evaporation

Oilfield wastewater is often Polluted by colloids,suspended solids, solid particles,crude oil,organic molecules and salt ions,so it become difficult on treating and reusing.Because of high salt content,halophilic bacteria is difficult to be cultured when macromolecular organic matter in sewage is dealed with by biological,there are pretreatment requirements,cumbersome process,serious equipment corrosion and a series of problems when desalination by traditional membrane and thermal.Therefore seeking the core technology of the new method on oilfield wastewater treatment and reuse have important academic significance and engineering application.In this paper, the idea of submerged combustion evaporation (SCE) on oilfield wasterwater is proposed,and the process and device of SCE to dealing with oilfield sewage is designed.According experimental study, the factors and the variation to the stability of evaporation temperature,exhaust temperature, evaporation efficiency and thermal efficiency of SCE of is investigated.The main work and conclusions are as follows:(1) According to the experimental requirement,the SCE treatment on oilfield wastewater experimental device are designed and seted up, The the core of SCE plant designing is the burning structure and heating and evaporation of the shell body. In this paper,the diffusion combustion structure is applied,the mixture jet exit velocity to be limited to burning off the fire within the speed limit is ensured when designe it,and ensure that combustion is safe.(2) The experiment results of SCE show that boiling point of steady evaporation is between80-85°C,the temperature of exhaust is3-7°C higher,so the effect of vacuum evaporation under atmospheric pressure operation could be achieved by SCE.It is indicated that the immersion depth of high temperature flue gas vent,speed and bubbling size have little effect on the boiling point and the exhaust gas.However.the heat load of fuel gas has a big effect on the evaporation temperature.especially when the immersion depth is small.(3) The evaporation efficiency and the thermal efficiency of SCE are affected by many factors.They increases with the increasing of immersion depth,but when the immersion depth is too high.the evaporation efficiency and the thermal efficiency will decline.Besides,research is done from the point of the bubbling situation.Under the same heal load and vents aperture but with different number of discharge holes,the results show that the evaporation efficiency and thermal efficiency increase with the decreases of exit velocity of high temperature exhaust.In the same heat load and the outlet area, the exit velocity of high temperature gas is same.With different vents aperture,the results show that the evaporation efficiency and thermal efficiency increases with the decreases of vents aperture.This article also looked at the impact of gas heat load to the evaporation efficiency and thermal efficiency,the experiments show that the gas-liquid perturbation increase with heat load,resulting evaporation efficiency and thermal efficiency increase with the heat load increasing.(4) The use of orifice plates and thin-stream porous cross-pipe exhaust structure are compared.lt is indicated the thin-stream porous cross-pipe exhaust structure can strengthen the heat and mass transfer by extending the gas-liquid contact time,and also increase the gas-liquid disturbances as well as the refinement of bubbles.So the evaporation efficiency and thermal efficiency are greatly improved.(5) According to experimental study on kerosene, oil, and crude oil were added in the wastewater, the results showed that the treatment effect of SCE on kerosene oil is the most obvious, the treatment effect of crude oil, though isn't as obvious visual effect as kerosene and oil, however, there is a certain degree of degradation of crude oil and reached a certain treatment effect. In addition, when oilfield wastewater contained diffierent oil is dealed with by the SCE,there is little impact to stabilize the evaporation temperature.But there is a great influence on evaporation efficiency and thermal efficiency,the evaporation efficiency and thermal efficiency of sewage containing oil is the largest,while the efficiency of sewage containing crude oil is the least, kerosene between the two middle, and the efficiency of processing of sewage containing crude oil and sewage is the same.(6) According to analysising of heat distribution and utilization problems to the SCE, the process of evaporation combining heavy oil recovery programs and the process of combining multi-effect distillation is made.These programs can not only improve the heat utilization efficiency of the system,but also improve the economy of the processing systems.Innovation of this paper are as follows:This is the first comprehensive experimental study factors to impact the "boiling point" of stable evaporation and exhaust gas temperature.This is the first time,the SCE is used to removal the different oil of the sewage,and its effcct,stabilc evaporation temperature, exhaust temperature, evaporation efficiency,themal efficiency is studied,and certain result is achieved.On the basis of the experimental results obtained in this study, jointing exploitation background of heavy oil,the combining of exploitation of heavy oil and the SCE process is developed, at the same time,two patents are applied.