Objective In order to meet the specification requirements of the GB 39728-2020 Emission standard of pollutants for onshore oil and gas exploitation and production industry, a new tail gas treatment unit was needed for the built natural gas purification plant and production. Cansolv process has been successively applied in the natural gas purification plant to realize the low concentration SO₂ emission of tail gas and economic operation.

Methods According to the operation adjustment summary of the new Cansolv tail gas treatment unit in Zhongxian Natural Gas Purification Plant since it was put into operation, the main factors affecting the normal operation of the unit were explored. The statistical analysis includes the following contents: (1) wastewater quality and SO₂ emission in waste gas; (2) energy consumption of Cansolv tail gas treatment unit and consumption of chemical raw materials; (3) factors affecting pollutants produced by Cansolv tail gas treatment unit. The following optimization measures are implemented for Cansolv tail gas treatment unit: (1) optimize the operation parameters of Cansolv tail gas treatment unit to meet the requirements of tail gas SO₂ emission; (2) reasonably control the content of thermal stability salt in DS solution of Cansolv tail gas treatment unit to reduce the amount of waste water; (3) reasonably control the temperature of DS solution and flue gas of Cansolv tail gas treatment unit to reduce the amount of waste water; (4) improve the operation stability of wet electric mist eliminator to reduce the thermal stability salt content in the solution; (5) reasonably adjust the quality of neutralization wastewater to improve the yield of fresh water from DTRO treatment skid; (6) optimize the operation of Cansolv tail gas treatment unit during the startup and shutdown of sulfur recovery unit; (7) adjust the energy consumption of Cansolv tail gas treatment unit to reduce the energy consumption of chemical raw materials.

Results After optimizing the operation measures of Cansolv tail gas treatment unit, the low concentration SO₂ emission of tail gas was ensured while wastewater production has been effectively reduced and controlled. Meanwhile, energy saving has been greatly improved.

Conclusions Through the analysis on the influence of Cansolv tail gas treatment unit on the natural gas purification plant and the optimization of operation measures, the Cansolv tail gas treatment unit can achieve efficient, safe and stable operation, which would provide reference for new Cansolv tail gas treatment in the future.