气田高含硫污水负压气提脱硫及尾气无害化处理技术研究

Research on the technology of vacuum extraction desulfurization and harmless treatment of gas field high-sulfur wastewater

关键词:  高含硫污水  负压气提脱硫  尾气处理  离子液体

Key words:  high-sulfur wastewater  vacuum extraction desulfurization  tail gas treatment  ionic liquid

摘要:

针对目前普光气田高含硫污水气提脱硫率低的问题,通过采用“曝气+负压气提+尾气催化氧化”工艺技术,设计正交实验,优选出最优负压气提脱硫操作条件为:污水pH值4.0、温度20 ℃、气提真空度-0.02 MPa、空气曝气气液体积比20∶1,污水负压气提脱硫率高达94%。各操作条件对脱硫率的影响由强到弱顺序为:空气曝气气液比、污水pH值、气提真空度和污水温度。实验优选出铁基离子液体作为尾气脱硫催化剂。结果 表明,铁基离子液体中Fe³⁺对H₂S氧化速率很快,净化后尾气中H₂S质量浓度为0 mg/m³,氧化产物为单质S,同时离子液体可通过空气将Fe²⁺氧化成Fe³⁺,实现低成本循环利用,解决了含硫尾气燃烧的SO₂排放问题。 

Abstract:

Aiming at the low desulfurization rate of high-sulfur wastewater in Puguang gas field, the technology of “aeration + vacuum extraction + catalytic oxidation of tail gas” was adopted and orthogonal experiment optimization was designed. The optimized operating conditions are shown as follows:sewage pH value of 4.0, temperature of 20 ℃, gas stripping vacuum degree of -0.02 MPa, aeration gas-liquid ratio of 20∶1, and sewage desulfurization ratio is as high as 94%. The influence of vacuum desulfurization operation conditions on the desulfurization rate from strong to weak in the order is air aeration gas-liquid ratio, sewage pH value, gas extraction vacuum degree and sewage temperature. Iron-base ionic liquids was optimized as exhaust gas desulfurization catalyst in the test. The results show that Fe³⁺ oxidized H₂S at a very fast rate in iron-based ionic liquids, the concentration of H₂S in tail gas is 0 mg/m³, and the oxidation products is elemental sulfur. Meanwhile, Fe²⁺ in ionic liquids can be oxidized to Fe³⁺ by air. The application of iron-based ionic liquids not only realizes the low cost reuse of the desulfurization liquid, but also completely eliminates the SO₂ emission problem caused by the combustion of the tail gas containing sulfur.