gas treatment

Gas Treatment: An Overview

Introduction to Gas Treatment
Gas treatment is the process of removing impurities and harmful substances from gas streams to make them suitable for various applications, including fuel, chemical feedstock, and environmental compliance. This process is essential in the oil and gas industry, where it involves the removal of acid gases, water, and other contaminants to prevent equipment corrosion, ensure safety, and meet environmental standards.

Physical and Chemical Solvent Processes
Two primary liquid absorption procedures used in gas treatment are physical solvent processes and chemical solvent processes. Physical solvent processes utilize organic solvents, low temperatures, and high pressure to absorb acid gases. Chemical solvent processes, on the other hand, use alkaline solutions such as amines or carbonates to absorb acid gases at temperatures below 50°C (120°F). Regeneration, or desorption, can be induced using reduced pressures and/or high temperatures to remove the acid gases from the solvent.

Sour Gas Sweetening
Sour gas is defined as natural gas that contains hydrogen sulfide (H2S). The sweetening process involves the removal of H2S to meet the specifications set by gas purchasers, typically a transmission company or the end user. The H2S content limit is generally one grain per 100 scf of sales gas, with some areas setting stricter limits at 1/4 grain per 100 scf of gas. Sour gas can contain H2S concentrations ranging from several ppm to over 90%. In addition to H2S, other sulfur compounds such as mercaptans are also present in sour gas and must be removed to meet total sulfur content specifications.

Applications in Natural Gas Purification Plants
Gas treatment processes are applied in natural gas purification plants to ensure that the gas meets the required quality standards before it is transported or used. One such application is the Cansolv tail gas treatment process, which is used to control the SO2 mass concentration in discharged flue gas below 100 mg/m3, significantly lower than the 800 mg/m3 standard set by GB 39728-2020 for the natural gas mining industry. This process has been optimized to control the mass fraction of organic amine, pH valve of lean liquid, and the molar ratio of heat stable salt to organic amine, among other parameters, to achieve effective gas treatment.

Environmental Considerations and Optimization
The environmental impact of gas treatment processes is a significant consideration, especially with the growing focus on pollution control and carbon neutrality. Life Cycle Assessment (LCA) is used to evaluate the environmental performance of gas treatment processes, identifying key stages and main environmental impacts. By improving the clean production index and optimizing the production process, it is possible to reduce the environmental characterization value by 80 to 90%, generating significant environmental, technological, economic, and social benefits.

Conclusion
Gas treatment is a vital process in ensuring the safety, efficiency, and environmental compliance of gas streams in various industries. It involves the removal of harmful substances like H2S and other sulfur compounds, and its optimization is crucial for meeting environmental standards and achieving sustainable development goals. As the focus on environmental protection and carbon neutrality increases, the role of gas treatment in pollution control and carbon emission reduction will become even more significant.