Study On Recovery Of CO₂ In Natural Gas By Improved MDEA

In order to improve crude oil production, an oil region of Shengli oilfield Chunliang plant is injected CO₂ 100 t/d. However, the crude oil dissolves partial CO₂, which makes associated gas quality not conform to the standards. Gas calorific value will be decreased and pipe wall will be quickly corroded by too much CO₂ in natural gas. At present, the station of heat has been already used coal instead of associated gas. Therefore, it is very necessary for this paper to study on amine reagent that can remove CO₂ from natural gas.In this paper, we study the decarburization reagent by MDEA and with other amine reagents, including kinds of binary compound reagents and ternary compound reagents. Binary compound reagents: MDEA+PZ, MDEA+MEA, MDEA+DEA, MDEA+DETA and MDEA+TETA. Ternary blends reagents: MDEA + MEA + DETA, MDEA + MEA + TETA, MDEA+ MEA+ PZ, MDEA+ MEA+ DEA. This paper makes MDEA decarbonization experiments as a comparable experiment. Then, we have done the ten groups of reagent decarburization experiments under the same experimental conditions successfully.According to the principle of orthogonal experiment and reagent nature, this paper designes nine absorption experiments for each reagent by an orthogonal table with four factors and three levels; the indexes are absorption and absorption rate. According to the method of controlling, this paper has done the regeneration experiments of each rich fluid; the indexes are regeneration rate, regeneration energy and regeneration velocity.We obtain order importance of factors and optimal levels for each reagent experiment by orthogonal experimental data processing method. According to the controlvariable method for regeneration experiments, we conclude optimal regeneration parameters for each reagent. This paper contrasts absorption experimental and regeneration experimental indexs between groups of reagent with the histogram. Meanwhile, this paper explains the experimental results with the reagent properties and reaction theory.From different perspective of the experimental indexes, the 10 kinds of reagentshave different priorities. However, the decarburization performance of mixed reagentsis better than that of the MDEA. The decarburization performance of MDEA+MEA is the best in the Binary compound reagents, but the regeneration energy is the highest in the 10 groups of reagents. The decarburization performance of ternary blendsreagent is on the same level, but the reagents added MEA have the fastest regeneration rate, the reagent added PZ has the highest regeneration energy.In a word, it is worthy for 25% MDEA+15% MEA to popularize and apply. The absorption performance of the reagent is best, which means absorption is 5.987 mol/L, absorption rate is 2.687×10-3 mol/s, in all groups of reagents with the conditions: 45℃, 1.5MPa, 700r/min. The optimal regeneration conditions for the reagentare 104℃, 1000 r/min. The results are regeneration velocity: 1.543×10-3mol/s, regeneration energy: 0.786 kw/mol, regeneration rate: 99.2%.