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Natural gas: There are mainly three types of natural gas resources: reservoir gas, associated gas, and condensate gas. Atmospheric gas is natural gas extracted from gas reservoirs ； Associated gas is the natural gas that is produced alongside crude oil during its extraction from oil reservoirs ； The gas in condensate gas reservoirs refers to gas that is stored in the reservoir under its original geological conditions; however, during extraction, as pressure decreases, some of the heavier hydrocarbons in the natural gas condense into a liquid state. Some of this liquid remains underground, while another portion is brought to the surface along with the natural gas. At present, most of the natural gas used around the world is reservoir gas; for example, gas fields in Sichuan and Changqing in China primarily produce reservoir gas. The Dagang oil field produces a significant amount of condensate gas, while the natural gas from other oil fields is mostly associated gas. It can be seen that natural gas obtained from the wellhead or from the oil and gas separator in the field contains varying amounts of heavier hydrocarbons, as well as non-hydrocarbon gases such as water vapor, sulfides (such as hydrogen sulfide), carbon dioxide, nitrogen, and helium; this is what we refer to as crude natural gas or wet gas. This type of natural gas is generally not suitable for direct use by most consumers; it needs to be specially processed to remove hydrogen sulfide, water vapor, condensed hydrocarbons, etc., before it can be supplied to users as commercial natural gas. Reasons for natural gas purification: Crude natural gas contains varying amounts of heavier hydrocarbons, as well as non-hydrocarbon gases such as water vapor, sulfides (such as hydrogen sulfide), carbon dioxide, nitrogen, and helium. Natural gas is transported through pipelines, and it usually contains saturated water vapor. When the temperature of the medium surrounding the pipeline is lower than that of the gas, the water vapor will condense into a liquid, or even freeze or form hydrates, which can severely block valves or pipelines. As for the acidic gases contained in natural gas, such as CO2 and H2S, they are even more harmful; the presence of water turns these gases into acids, thereby accelerating corrosion of the pipe walls and reducing the service life of the pipelines. When natural gas is used as fuel, it can endanger people's lives. When used as chemical raw materials, these acidic gases can also poison the catalysts, reducing their catalytic efficiency or even rendering them ineffective, which affects the quality of the products. Therefore, crude natural gas needs to undergo purification processes to meet the requirements for domestic and industrial use. Even after natural gas has been dehydrated and desulfurized, it still cannot be used directly as fuel gas or a raw material for chemical industries. It is necessary to remove thiols and heavier hydrocarbons from the natural gas in accordance with certain standards and requirements, primarily by liquefying and recovering hydrocarbons with a carbon count of C3 or higher. In this way, it not only avoids the many issues related to instability that can arise from the formation of condensate during natural gas transportation, but also purifies the natural gas, eliminating numerous hazards for users during its use. At the same time, separating the components above C3 significantly increases the calorific value of natural gas. Moreover, these components above C3 can be converted into high-quality liquefied gas and light oils, thereby yielding good economic benefits. Natural gas purification process: The process flow for natural gas treatment can vary in many ways, but the basic steps remain the same, namely natural gas purification, compression, cooling, and distillation. Cooling is further divided into expansion cooling or refrigerant cooling; currently, most natural gas processing units in China are of the shallow cooling type. Typically, after natural gas enters the centralized treatment plant, it is first passed through a separator to remove the carried condensate, water, and solid impurities. It is then compressed by a compressor to the desired pressure, and after cooling and separation, it is sent to desulfurization and dehydration towers so that the dew point of the dehydrated gas meets the requirements for low-temperature processing. Then, it passes through the rich-poor gas heat exchanger, propane refrigerator, and plate-fin heat exchanger in sequence to bring the temperature of the feed gas to the required level; finally, a qualified natural gas is obtained through distillation in a fractionation tower, while by-products such as liquefied gas and light oils are produced. Natural gas purification involves addressing the components present in natural gas obtained from oil and gas fields; through analysis and research, it is necessary to employ technical measures to remove acidic gases from the natural gas, such as carbon dioxide, hydrogen sulfide, sulfur dioxide, etc., in order to prevent further corrosion. The moisture in natural gas is treated by using absorption or adsorption methods to remove the large amount of water vapor present in it. The natural gas after such treatment meets the requirements of users, and the waste gases are recycled. At the same time, the wastewater from natural gas processing plants is treated; once it meets the required standards, it can be reinjected into the oil reservoirs to achieve water flooding effects. The amine treatment method is a representative technique for removing carbon dioxide and hydrogen sulfide from natural gas, through a chemical reaction between monoethanolamine and the acidic gases present in natural gas. Monoethanolamine has stable physical properties, which reduces the degradation of solutions; its chemical reactions are thorough, resulting in effective purification of natural gas. It is widely used in natural gas processing plants. Using the amine method to treat natural gas can easily bring the concentration of acidic gases in it to the levels required for pipeline transportation. This processing technology has a wide range of applications and strong adaptability, and the purified natural gas meets the design specifications. Low-temperature methanol washing achieves excellent removal efficiency due to the high solubility of methanol solutions under low temperature and high pressure for gases such as carbon dioxide, hydrogen sulfide, and water vapor. The low-temperature methanol washing process has a strong absorption capacity and achieves high purity in gas purification; it is an effective method for natural gas treatment, capable of removing both inorganic and organic sulfur completely. In the natural gas processing process, the commonly used method involves pretreatment via solvent absorption, followed by advanced purification using molecular sieves to meet the basic requirements for natural gas treatment. The condensation separation method recovers natural gas by means of condensation, thereby recovering the condensate generated during natural gas processing. Taking advantage of the different boiling points of the various components in natural gas, the temperature of the gas is reduced below its dew point, causing partial condensation and separation between the gas and liquid phases. This results in a condensate oil with a high content of heavy hydrocarbons; further processing of this condensate yields chemical raw materials that can be utilized in the petrochemical industry. Liquefied natural gas is obtained by liquefying natural gas; the pre-treated natural gas is compressed and condensed to temperatures below -162°C, after which it turns into liquefied natural gas. The natural gas extracted from oil and gas fields, which has been treated to remove acidic gases, is generally acidic in nature. Therefore, in natural gas processing plants, the first step in purifying this gas is to remove the acidic components from it through acid removal treatment, so as to ensure that the purified gas meets the requirements of the end-users. Although sulfides in natural gas do not have a corrosive effect, the combustion of natural gas produces sulfur dioxide, which can lead to acid rain and cause environmental pollution. The presence of carbon dioxide promotes the formation of natural gas hydrates, leading to the degradation of natural gas and affecting its purification efficiency. If natural gas contains too much moisture during dehydration treatment, its combustion efficiency will be poor, which affects the quality of the gas. Water vapor in natural gas is separated to achieve purification. The solid absorption method and solvent adsorption method are applied to remove moisture from natural gas, so that its water content meets the requirements of users. For dust removal and purification, the methyldiethanolamine method is used for desulfurization and triethylene glycol is employed for dehydration. The sulfur recovery technique makes use of low-temperature Claus cold bed absorption, which enables a high rate of sulfur recovery; this prevents waste of various raw materials during natural gas processing, **improves the efficiency of natural gas purification, and allows for the separation and treatment of different components in natural gas. The feed gas is subjected to filtration to remove condensate oil, mechanical impurities, and free water. The equipment used for this purpose are gravity separators and filter separators, which achieve separation based on differences in density. The desulfurization unit employs an absorption method, using a methyldiethanolamine solution to absorb hydrogen sulfide from natural gas; within the absorption tower, the hydrogen sulfide is removed through the counter-current interaction between gas and liquid. Then, through desorption, the absorbed hydrogen sulfide is released and reused. The dehydration process of natural gas is a physical reaction process with no chemical reactions taking place. The moisture in natural gas is absorbed into a triethylene glycol solution, and under normal temperature and pressure, the water can be evaporated for further use, which reduces production costs. This absorption process can be repeated to achieve the goal of dehydrating natural gas. By using dry gas stripping for triethylene glycol, a high-concentration triethylene glycol solution of satisfactory quality can be obtained