Experimental Studies Of Mass Transfer Performance Of CO₂ Absorption Into DEEA-based Compound Absorbent In DX Structured Packing

Greenhouse effect is mainly caused by the emission of carbon dioxide?CO₂?,and fossil fuel combustion of coal-fired power plants has been considered to be the main contributor of greenhouse gas emissions.Therefore,it is urgent to find the CO₂capture method and technology to control the CO₂ emissions from flue gas of coal-fired power plant.Currently,alkanolamines based chemical absorption have been widely applied to remove carbon dioxide from flue gas.However,the key problem in the application of individual amine absorbents is the contradiction between low energy consumption for solvent regeneration and high CO₂ absorption rates.There has been a continuous research focus on the development of blended absorbents with relatively high CO₂ absorption rate and low energy demands during regeneration.Recently,N,N-diethylethanolamine?DEEA?,a novel tertiary amine,has been considered as a candidate absorbent for bulk CO₂ removal from flue gases due to its good performance.In addition,it can be synthesized from cheap and sustainable renewable sources.To solve the high energy consumption of regeneration of amine capture process,it is vital to develop new tertiary amines?such as DEEA?based absorbents,which can maintain low desorption energy consumption of tertiary amine solutions,higher absorption rate and higher cyclic capacity.The packed column was the most widely used equipment of gas-liquid mass transfer in the industry.The structured packing is particularly suitable for carbon dioxide capture in atmospheric flue gas due to its excellent separation efficiency and low tower pressure drop.Based on the effective removal of CO₂ coupled with lower energy requirement for solvent regeneration,the mass transfer performance of CO₂ absorption into DEEA-based solution was investigated in a effective structured packing column.The main contents and results of this work include:?1?The carbon dioxide?CO₂?capture potential of amine blends,formed by mixing N,N-Diethylethanolamine?DEEA?and piperazine?PZ?,were estimated using a rapid screening method.Solvent screening experimental results showed that blended DEEA/PZ solution with molar ratio of 2.5:0.5 exhibited the higher CO₂ absorption rate and desorption rate,thereby yielding the highest cyclic CO₂ capacity of0.8667?mol CO₂/L.Also,the mass transfer performance of CO₂ absorption into the best 2.50?M DEEA+0.5?M PZ solution was investigated in a absorber packed with Sulzer DX structured packing.The effects of liquid flow rate,lean CO₂ loading,inert gas flow rate and CO₂ partial pressure on the mass transfer performance were evaluated in terms of overall mass transfer coefficient?K_Ga _V?.?2?The mass transfer performance of CO₂ absorption into blended DEEA/MEA solutions was investigated in a lab-scale absorber packed with Sulzer DX structured packing using a standard orthogonal array with an L₂₅?5⁶?matrix.The results show that these key operating parameters have significant effects on K_Ga _V.Also,based on orthogonal analysis,it was clear that the order of importance for the contribution to K_Ga _V of the six investigated factors was as follows:CO₂ lean loading>CO₂ partial pressure>Liquid feed temperature>Amine concentration>Liquid flow rate>Inert gas flow rate and the optimization of the experimental combination was B₁C₁D₂A₃E₃F₂.The result has important implications for the design of the experimental scheme for CO₂ absorption in packed column.