The coiled-tube heat exchanger is a new type of heat exchanger, with a structure that differs from the shell-and-tube heat exchangers widely used in current petrochemical plants. In this design, the heat transfer tubes are spirally wound in multiple layers, with each layer separated from the one below by precisely positioned spacers to maintain consistent spacing. Notably, adjacent layers are wound in opposite directions. This innovative design allows for an extended length within the shell, enabling a more compact outer casing while simultaneously enhancing heat transfer efficiency.
  
　　Low-temperature methanol washing is a typical physical absorption process, where methanol absorbs CO₂, H₂S, and other impurities in an absorption tower under low-temperature and high-pressure conditions. The methanol solution, now enriched with these impurities, undergoes throttling to reduce pressure, causing the released CO₂ to vent through the boiler chimney at an elevated height. Meanwhile, the methanol solution is heated again, enabling the efficient desorption of H₂S from the liquid. The regenerated methanol can then be reused repeatedly.
  
　　In cryogenic process equipment, heat exchangers are crucial, and minimizing thermal losses is essential. To achieve this, heat exchangers must be compact in design yet feature a large heat-transfer area and high efficiency. Additionally, when fluids flow in counter-current mode, the temperature difference should remain as small as possible. Among the practical heat exchanger designs that meet these stringent requirements, the most commonly used are coiled-tube and plate-fin types. Both are well-suited for cryogenic applications: plate-fin exchangers operate effectively at pressures below 4 MPa, while coiled-tube exchangers can handle pressures up to 20 MPa, making them particularly ideal for high-pressure cryogenic systems. As a result, these advanced heat exchangers are increasingly being adopted across various industrial sectors, including refinery hydrogenation processes, large-scale air separation units, natural gas liquefaction facilities, and applications involving liquid oxygen, liquid nitrogen, and cryogenic methanol scrubbing systems.