Research On The Deep Decarbonization Process Of Natural Gas

Natural gas has been attracting attention as a clean energy source.Especially in the case of depletion of petroleum resources,natural gas mining,purification,transportation,liquefaction and other project projects are not uncommon.Before natural gas enters liquefaction,it prevents H₂S,organic sulfur and mercury from corroding equipment to prevent water and CO₂ from freezing and blocking pipes and equipment valves in low temperature environment.Deep removal of CO₂,H₂S,organic sulftur,mercury,water and other impurities in natural gas is required.Compared to shallow desorption?requirement for pipeline transportation purification?,the energy required for the deep removal of these impurities is much higher.It is important to study the purification process to reduce energy consumption.This paper investigates the research status of natural gas purification treatment at home and abroad.In the LNG pretreatment,in view of the improvement of other impurity removal technologies,most of them are mainly based on COZ removal.This paper decided to focus on the deep decarbonization process of natural gas.After investigating the literature on deep decarbonization of natural gas,the research contents were determined,and the performance comparison of different alkanolamines in deep decarburization was studied.The evaluation and analysis of the current natural gas deep decarburization process were proposed,and the current process optimization measures were proposed.With the characteristics of high process energy consumption,the focus is on reducing the energy consumption,researching three new processes,including the variation of characteristic parameters,analysis of energy-saving reasons,comparison of energy-saving effects,and promoting the practical use of the three processes;The adaptability of three new processes to different CO₂ content changes was analyzed,and whether the energy saving effects of the three processes were changed.For the actual project,through the simulation and actual operation data of the factory,analyze the practicability of the new process,optimize the current process of the plant,and promote the application of new processes.By comparing the performance of the solvent absorption in the deep decarburization process of natural gas,the mixed solvent and the activated amine are mostly used as the absorption solvent.If a mixed amine is used,the content of MEA or DEA should be 10%?15%?wt?,which is higher than that of shallow?MEA or DEA content is 5%?.If the thermal stability salt corrosion can be effectively controlled,MDEA+MEA is preferred as the preferred mixed amine solution.If the corrosion is difficult to control,MDEA+DEA can be selected as a mixed solvent.When the raw material gas does not contain H₂S or the content is small,MDEA+PZ is preferably recommended as the absorption solvent.At present,deep decarbonization of natural gas is widely applied to conventional processes.When the feed gas contains H₂S,the energy consumption will increase.If the H₂S content is too high,the selectivity of MDEA can be utilized to preferentially remove most of the H₂S.A small amount of heat-stable salt is often present in the amine liquid system.Although it is beneficial to the absorption of H₂S,it is easy to cause foaming and loss of the amine liquid.In engineering,the heat-stable salt is generally controlled within 1%.For different natural gas containing CO₂,the conventional process is highly adaptable,and the purification index can be achieved for different CO₂ feedstock gases.The semi-lean solution is applied to the deep decarburization process of natural gas,and the energy-saving effect of the process increases with the increase of the content of CO₂ in the feed gas.This paper focuses on three new processes:split desorption,heat pump rectification-split desorption and steam recompression.The former two are high-temperature streams obtained by split heat transfer to increase the temperature of the entire regeneration tower and further enhance the regeneration tower.Regeneration effect for energy saving purposes.The latter uses the lean liquid throttling phase change to generate steam as the regeneration tower gas lift,which also plays an obvious energy-saving effect.The energy-saving effect of the split desorption process and the steam recompression process is about 10%?20%.Compared with other processes,the heat pump rectification-distribution desorption process has obvious energy-saving effect,and the energy saving is about 30%.Compared with the on-site data of Zhuhai LNG pretreatment,the process still has significant energy-saving effect and is a new process worthy of popularization and application.