Study Of The Process Of Flue Gas Carbon Dioxide Capture Based On Liquid Gas Jet Technology

Petroleum processing is a high energy consumption industry.About 6.5%of the crude oil is consumed by processing,resulting in a large amount of CO₂ emission.In China,energy consumption of the crude oil processing was equal to 35 million tons of crude oil with crude processing volume at 539 million tons in 2016 under the standard of the hydrogen carbon atom ratio in crude oil is calculated by about 1.9,which would produce carbon dioxide about110.9 million tons.Therefore,it is imminent to implement carbon capture in refineries.However,most of the CO₂ in refinery is discharged by flue gas,with high temperature（about150℃）,low pressure（normal pressure）and low carbon content（dry base about 12%）,and the emission source is usually located at the top of the chimney of dozens of meters high,so the recovery is difficult and the energy consumption is high.In this paper,a new process of pre-absorption and regeneration of CO₂ by using the jet pump of flue gas compression with lean solution and strong turbulence characteristics for pre-abosorption is proposed then mechanism modeling and optimization design carried out.In the new process,the flue gas is directly inhaled by the jet pump with high pressure lean solution and pressed into the absorption tower,leaving out high energy consumption of compressor.Meanwhile,strong turbulence in the jet pump throat makes the mixture of CO₂and lean solution close to molecular level achieving high efficient CO₂ pre-absorption.In order to simulate physical and chemical process in the jet pump,CFD is used while UDF is embedded to describe models of gas and liquid contact,mass transfer and chemical reaction.With the aid of the model,effects of operating parameters and structural parameters on CO₂ absorption performance are explored.On the other hand,the original absorption and regeneration process is simulated by Aspen.Sensitivity analysis of parameters on the energy consumption and material are performed deciding absorber pressure and recycle rate as main optimization characters in new process.Finally,a new design method with absorption ratio iterative correction as core idea is put forward to optimize overall process with Fluent and Aspen converge simultaneously.An expmple of CO₂ capture of 40×10⁴t/a FCCU flue gas is shown.Compared with the traditional process,with the help of jet pump,pressure of the absorber can be increased from0.076MPa to 0.09MPa so that energy consumption decreases from 5.55GJ/tCO₂ to4.56GJ/tCO₂,in an extent of 17.8%,which can save 3.892 million yuan yearly.