稠油热采废水回用电站锅炉补给水工艺

摘要

常规稠油热采废水处理采用除油软化工艺,出水水质较低,仅能用于直流小注汽锅炉补水.由于小注汽锅炉参数低,排污量大,能耗高,造成采油蒸汽成本高.针对该问题,开发了预处理-蒸发-生物处理-膜处理-混床工艺处理稠油热采废水,并通过实验对工艺各子系统运行性能进行研究以提高处理效果,使系统处理出水可用于电站高参数锅炉补给水,达到以热电联产机组取代小注汽锅炉,降低采油蒸汽费用的目的.研究结果表明,采用该工艺对稠油热采废水进行处理,各子系统运行稳定;废水经除硅软化预处理及蒸发后,产水TOC平均约22mg/L;曝气生物滤池产水TOC平均约6mg/L;再经超滤-反渗透处理后产水TOC含量小于0.15mg/L;继续经混床处理,最终出水电导率≤0.15μS/cm、二氧化硅≤10μg/L、TOC≤200μg/L,满足电站高参数锅炉补水水质要求,每吨水直接运行费用为8.05元.%The traditional heavy oil thermal recovery wastewater treatment process is comprised of oil eliminating and softening. The effluent quality is comparably poor which can only be used as make up water for once-through small steam injection boiler. Because the parameter of small steam injection boiler is low,both the boiler blowdown and energy consumption are high. The oil extraction steam cost is raised subsequently. Aimed at the problem,a novel heavy oil thermal recovery wastewater treatment process that comprises of pretreatment,bio-treatment,membrane,and mixed bed technology was developed. Operating performance of individual sub-system was investigated by model experiments to enhance the treatment efficiency and to make it possible to reuse the product water as high parameter power plant unit make up water. As a result,the objective to replace the small steam injection boiler by combined heat and power generation unit to reduce the oil extraction steam fee could be achieved. Results show that the operating performance of all sub-system is stable when theheavy oil thermal recovery wastewater was treated by the new process. The average TOC was about 22mg/L when the wastewater was treated by the silica removal and softening pretreatment system and the evaporator. The TOC was decreased to about 6mg/L in the BAF effluent,and it was continued to decrease to about 0.15mg/L in the UF-RO effluent. The conductivity,silica and TOC of the final product water were less than 0.15μS/cm,10μg/L and 200μg/L respectively when the UF-RO effluent was treated by mixed bed ion exchanger subsequently. This water quality could meet the demand of high parameter power plant boiler and the direct operating cost is 8.05yuan/ton of product water.