Study On The Silica Scale Control Technology Of The Thermal Recovery Boiler Of Heavy Oil Sewage Reuse

In order to reduce the difficulty of heavy oil exploitation, Steam assisted gravitydrainage technology has been promoted and applied gradually with the major oil fieldshave entered the heavy oil stage. The heavy oil sewage quantity is increasing during thesteam assisted gravity drainage processing. After the heavy oil sewage deoiling itcontains a large capacity of water resources that can be recycling, but it must beprocessed with the standard before they recycle to the hot steam injection boiler. Atpresent there is no economic and feasible method to process the high silicon content inheavy oil sewage. This article is focused on silica removal of the heavy oil sewage andexplore the mechanism of action.This article prepared simulated heavy oil sewage samples according to the waterquality, which was taken to study the effect of different agents to removal silica fromsimulated samples and the stability mechanism of heavy oil recovery sewage. On thisbasis, silicon-modified complex reagent AM was applied to process heavy oil sewage,and generating precipitates were analyzed by infrared spectroscopy (FTIR), X-raydiffraction (XRD) and X-ray photoelectron spectroscopy (XPS) and the scalingsimulation software OLI ScaleChem to explore AM processing conditions and reactionmechanisms. Main results for this study are as follows:(1) Silicon-modified complex reagent AM has good treatment effect on heavy oilsewage. When the initial total silicon content of400mg/L, the treated water samplessimulated total silicon content100mg/L or less. The process conditions was: AMdosage200mg/L (as Al), pH9, rapid mixing intensity150rpm, rapid mixing time1min, slow mixing intensity50rpm, slow mixing time9min, slow mixing time settlingtime30min, temperature90℃.(2) For heavy sewage water, the optimized processing conditions: In addition to eAM dosage was100mg/L (as Al), no complex organic polymer agent, reactionwithout adjusting pH, the treated water samples total silicon content]was100mg/L orless. Compared to the conventional method of lime addition to silica removal, siliconcompound in addition to AM desilication has better result.(3) The field pilot study was carried out with remove silicon integrationequipment.The stable operation was120h, the cumulative water flow was89.4m3.After continuous sampling detection, the outlet water content of total silica was150mg/L or less, and other water quality indicators had reached the standards. Treatment effect is good, the device is operating normally, verify the feasibility of the treatment process,to achieve the purpose of the pilot experiment.(4) Using infrared spectroscopy, X-ray photoelectron spectroscopy and X-raydiffraction analysis, combined with AM adsorption tests and scaling softwaresimulation results, compound medicament AM effect of silica removal is remarkableto the actual heavy oil sewage, silicon scale tendency reinjection to hot steam boilergenerates significantly reduced, and concluded that AM mechanism for silica removalis adsorption charge neutralization.