大连石化污水场二期技术特点和运行效果

Techniques Used in Phase Ⅱ of Sewage Treatment Project of PetroChina Dalian Petrochemical Company and Their Performance

大连石化污水场二期整体引进美国地球工程公司的工艺包,核心工艺单元设备选型全部采用进口,设计污水处理量为1000m3/h,总投资1.3亿元。预处理单元采用的是API隔油池和DAF气浮池,油含量平均去除率为27.94%,悬浮物平均去除率为61.73%,COD平均去除率为32.67%;生化处理单元包括A/O池和二沉池,油含量平均去除率为71.6%,硫化物平均去除率为91.52%,挥发酚平均去除率为99.82%,COD平均去除率为78.83%,氨氮平均去除率为94.15%,碱度平均去除率为54.67%;深度处理单元三级澄清池采用溶气气浮工艺,出水油含量为0.63mg/L,平均去除率为85.94%,悬浮物含量为4.98mg/L,平均去除率为85.13%,COD为44.48mg/L,平均去除率为42.88%,出水水质达到排放标准。对于工艺设计存在的问题,大部分已采取解决方法,尚未解决的也在进一步调整中。

In order to reduce the emission of SO2 in flue gas,CNOOC Ningbo Daxie Petrochemical Co.,Ltd.introduced the magnesia wet desulfurization technology to desulfurize the flue gas from the three industrial heating furnaces of its 225×104t/a asphalt unit.This technology uses magnesia as the desulfurizing agent and can effectively prevent settlement and clogging.In this technology,flue gas will be in converse contact with the circularly sprayed grout in the desulfurizing and absorption column,flue gas is cooled to some 60℃ and the sour gases in the flue gas such as SO2 and SO3 are absorbed by the grout;the purified flue gas is emitted after fine droplets in it are removed by a defroster;wastewater from the absorption column will be discharged into the sea after flocculating settling and solid deposits will be made into mud cakes after being dehydrated,which will be shipped off site for disposal.Since it was put into operation,the desulfurizing system has been working very well.The concentration of SO2 in purified flue gas is lower than 2mg/m3,more than 90% of sulfur is removed and the wastewater produced meets emission requirements.This article suggests the company improve the structure of the defroster,take anti-corrosion measures for the absorption column and the chimney to reduce the corrosion by the droplets in the flue gas and add flue gas dedusting devices before the absorption column to reduce workload for the downstream wastewater treatment system.