In the gas treatment process, the impurities contained in the raw gas, such as liquid free water, solid particles, H₂O, acid gas (CO₂, H₂S), etc., not only accelerate the corrosion of the equipment and clogging of the pipeline, but also may affect the stability of the subsequent process and the quality of the product, so it is necessary to strictly control the impurity indicators. Pre-treatment adopts a step-by-step purification strategy, firstly, the use of alcohol and amine method to efficiently remove the acidic gas, and then with the help of molecular sieve adsorption technology, to further remove water, heavy hydrocarbons, mercury and other impurities, in order to lay the foundation for the subsequent treatment.
There are many different technologies for acid gas removal, including molecular sieve adsorption method, alcohol-amine method, modified hot potassium method, sulfone-amine method and so on. The selection of solvents and process design for different technologies requires comprehensive consideration of the composition of the raw gas, pressure conditions, product quality standards, and overall costs and operating expenses. With rich experience in the industry, customized deacidification plants based on the ethanolamine method are designed to ensure efficient acid gas removal according to the characteristics of the gas components and the working conditions at the site.
Natural gas dehydration mainly adopts absorption and adsorption methods. For small-scale projects, the molecular sieve adsorption method has the advantage of efficient dewatering even under low partial pressure of water vapour due to its strong adsorption performance, while further removing residual acid gas. In addition, the device is easy to operate, compact and occupies a small space, which is highly suitable for small-scale projects. It is worth mentioning that the regas of the molecular sieve system comes from the BOG after recovering the cooling capacity of the re-liquefaction unit, so as to achieve the recycling of energy.
In order to ensure that the gas quality meets the stringent standards, the purification equipment adopts targeted technology to deal with trace pollutants. Specialised sulphur-impregnated coal-based activated carbon is used to effectively adsorb and remove possible trace amounts of mercury, while special adsorbents are used for in-depth purification of aromatic hydrocarbons. Through these precise treatment measures, trace impurities in the gas are efficiently removed, and the gas purification effect is guaranteed in all aspects.
Q1: Why is pre-treatment necessary in gas processing?
Pre-treatment is essential to remove impurities like liquid free water, solid particles, H₂O, and acid gases. Left untreated, these impurities can accelerate equipment corrosion, clog pipelines, and compromise the stability and quality of the final product.
Q2: What technologies are commonly used for acid gas removal?
Common technologies include the molecular sieve adsorption method, alcohol-amine method, modified hot potassium method, and sulfone-amine method. The choice depends on gas composition, pressure, quality standards, and budget.
Q3: What makes molecular sieve adsorption suitable for small-scale dewatering?
Molecular sieve adsorption is highly efficient even under low water vapour partial pressure. Additionally, the equipment is compact, easy to operate, and has a small footprint, making it ideal for smaller project layouts.
Q4: How does the dewatering process achieve energy recycling?
The system utilizes Boil-Off Gas (BOG) after recovering the cooling capacity of the re-liquefaction unit as the regeneration gas (regas) for the molecular sieve system, successfully recycling energy.
Q5: How are trace mercury and aromatic hydrocarbons removed?
Trace mercury is captured using specialized sulphur-impregnated coal-based activated carbon, while aromatic hydrocarbons are deeply purified using targeted, custom adsorbents to ensure absolute gas purity.
Q6: What is the main benefit of the step-by-step purification strategy?
A step-by-step purification strategy ensures that different types of impurities—ranging from acidic gases to trace mercury—are targeted systematically using the most appropriate physical and chemical methods. This minimizes operational risks and maximizes product gas purity.
Hongke Qingneng
