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Dew point control is primarily used in natural gas transmission, and it involves reducing the dew points of water and hydrocarbons to specified values. Common control methods include absorption, adsorption, and low-temperature separation. 1. Glycerol absorption method: The glycerol dehydration process mainly consists of two parts: glycerol absorption and regeneration. The wet natural gas has its liquid and solid impurities removed in the inlet separator before entering the absorption tower. Inside the tower, natural gas comes into countercurrent contact with lean glycol; the dehydrated natural gas becomes dry gas, while the glycol solution that has absorbed water becomes rich glycol. Glycerol is reused through a regeneration cycle. This method is only used to control the water dew point and cannot control the hydrocarbon dew point. 2. Solid adsorption method: The solid adsorption method involves using porous solid adsorbents to treat natural gas mixtures, so that one or more components contained within them are adsorbed onto the surface of the solid, thereby achieving separation. The adsorbent can be regenerated after being used for a period of time. The adsorption process can be carried out in semi-continuous or continuous modes. Semi-continuous operation employs two or three fixed-bed towers for alternating adsorption and regeneration. Continuous operation uses a fluidized bed, where natural gas and the adsorbent come into contact in opposite directions within the absorption tower, while the adsorbent is regenerated outside the tower. This method requires high investment and energy consumption, and is generally used only for high-pressure natural gas with low water content or in situations where very low dew points are required. 3. Low-temperature separation method: By using an appropriate low temperature, water and some of the heavier hydrocarbons in natural gas can be condensed and separated, thereby enabling simultaneous control of the dew points of water and hydrocarbons. Common methods for generating low temperatures include: throttling refrigeration, mechanical refrigeration, ammonia absorption refrigeration, etc. (1) Throttling refrigeration dehydration refers to the method of dehydrating by using the Joule-Thomson effect through a throttle valve for cooling ； It is suitable for situations where the gas source pressure is very high and no further compression is required after pressure reduction. Generally, a decrease of 1 atmosphere results in a temperature drop of about 0.5°C. (2) Mechanical refrigeration dehydration refers to a cooling method that uses a refrigerant in a compression-condensation-vaporization cycle. The applicable temperature ranges for various common refrigerants are: ammonia – 10 to –25°C, propane – 20 to –35°C, and liquefied petroleum gas – around 5°C. (3) The ammonia absorption refrigeration method uses an ammonia aqueous solution to achieve cooling through a heating, fractional distillation, condensation–vaporization–absorption cycle. The cooling temperature is around –10°C.