Experiment And Simulation Study On Separating Carbon Dioxide In Synthesis Gas In Coal-to-Methanol By Modified Amine

In coal-to-methanol process,large amounts of CO₂ and small amounts of H2 S,COS in the gas should be removed before sent into methanol synthesis reaction process.Rectisol is applied in this process,whose operating temperature is below-50?,while temperature of upstream and downstream are both above 200?.Thus a large amount of cold source is consumed to meet the condition.PPA recovering CO₂ is the most widely method;however traditional amine absorber,such as MDEA,also has shortages,such as small absorption capacity and large renewable energy.Aiming to discover more energy-efficient process instead of Rectisol,experiments and simulation were designed in this paper,and main work is done as followed:1.The single amines and mixed amine-ether alcohol amine solution absorption and regeneration performance was operated in 1 atm,of which the results show that the absorption capacity of different ratio of ethylene glycol ether to amine is different,absorption capacity is ranged from big to small ordered by 9:1>10:0>8:2>7:3>6:4.Absorbing capacity of NMTG is smaller than MTG,and the increasing number of ether is more favorable for CO₂ dissolved,while increasing hydroxyl is not conducive to absorb CO₂.A small amount of ethylene glycol ether could increase the solubility of CO₂,but enlarges balance time than single solute chemical absorption process.2.Pressure affection of the mixed solution is more extended than amine solution,thus MDEA-MTG solution under the ratio of 9:1 has a lower CO₂ equilibrium pressure than the MDEA solution,which has a 109.1% absorption capacity than the latter at 4 Mpa.Amine decarburization process is designed and sensitivity analysis is conducted by Aspen Hysys under designing target of fluegas 17574kmol/L?CO₂ concentration 0.32?CO₂ recovery 0.945,then the initial and advanced processes are compared under the optimal design condition.MDEA-MTG mixture volumetric flow rate is 7.27% smaller than that in MDEA solution,the amount of heat and cold power required reduces 11481.4kW and 9220 kW respectively,we can conclude that new solution will both save equipment investment and reduce the operation cost.The difference between experimental result and simulation result is 0.57%,which is in line with the actual.3.NHD is a polymer of MTG polymerization degree 3⁸,having a huge solubility of CO₂ and H2 S.Selexol decarbonization process is designed to meet the target above and optimize the parameter to find the minimum heat exchanger load.Operating parameters of the optimal operating point are as follows: the poor fluid flow 14270 kmol/h,CO₂ load 0.001,barren solution temperature-2?,flue temperature to absorber 16?,REGE flow 90kmol/h,regenerator pressure of 0.035 MPa.Under this operating condition,the absorber cooling energy consumption is 11654.68 kW,accounted for 64.5% of the total energy consumption.The modified process reduces energy load by 1886.86 k W.The Selexol process saves cooling capacity of 6582.74 kW than Rectisol process,which is under a much more simple flow.