The extracted natural gas contains a certain amount of acidic gas CO2, which can cause problems such as decreased calorific value and pipeline corrosion. Therefore, decarbonization treatment is required before pipeline transportation and use.
According to the natural gas calorific value formula in the national standard (GB/T 11062-2014), it can be calculated that 10mol% CO2 will cause a decrease of about 9.80% in methane calorific value per cubic meter. When CO2 coexists with water vapor and has a partial pressure greater than 207kPa, it will cause serious corrosion to equipment and pipelines, and additional anti-corrosion measures need to be taken. Therefore, natural gas must undergo strict CO2 removal before being transported to commercial pipelines.
MDEA process is used to remove CO2 from natural gas.
MDEA Physicochemical properties and decarburization principle
MDEA, scientific name N -methyldiethanolamine, is a colorless or slightly yellow viscous liquid.
Molecular formula: CH3N(CH2CH2OH)2 ,
Boiling point： 246~249 ℃ /760mmhg ; specific gravity： 1.0425g/ml ( 20 ℃);
Freezing point： -21 ℃ (purity 99% ); viscosity： 101Cp ( 20 ℃);
It can be easily miscible with water, ethanol, ether, etc.; weakly alkaline in water; chemical reaction will occur in acid carbon dioxide and hydrogen sulfide gas, and at higher pressure, carbon dioxide and hydrogen sulfide gas have higher So the whole absorption process is the physical and chemical absorption process.
The MDEA rich liquid after absorbing hydrogen sulfide and carbon dioxide enters the flash tank for vacuum flash evaporation, and then is sent to the regeneration tower. The rich liquid is heated and decomposed at the tower bottom to completely release carbon dioxide and hydrogen sulfide. At the same time, the gas at the tower bottom rises to form a secondary stripping effect on the rich liquid at the tower top.; so the whole regeneration process also is the physical and chemical regeneration process. The specific chemical reaction is as follows:
R2R’N + H2S R2R’NH +HS (instant reaction)
R2R’N+CO2+ H2O R2R’NH +HCO3 (slow reaction)
Rongteng specialize in gas field wellhead treatment, natural gas purification, LPG recovery, LNG plant and natural gas generator set.
Contact:
Sichuan Rongteng Automation Equipment Co., Ltd.
Phone/WhatsApp/Wechat : +86 177 8117 4421 +86 138 8076 0589
Website: www.rtgastreat.com Email: info@rtgastreat.com
Address:No. 8, Section 2 of Tengfei Road, Shigao Subdistrict,Tianfu New Area, Meishan city, Sichuan China 620564
Post time: Dec-03-2023
