Applied Research On Deactivation Of Activated MDEA

A growing number of gas fields with high CO2 content have been discovered, the existence of CO2 in the natural gas will affect the heating value of natural gas, and may result in equipment corrosion and CO2 freeze plugging in LNG production,NGL recovery and other low-temperature conditions, even affecting the normal production. Directing at the decarbonization of high-CO2 natural gas, the in-depth research of active MDEA method can provide a reference to the selection of sorption solvents and treatment process for future high-CO2 gas field development.This paper used the MDEA aqueous solution that was blended with MEA, DEA or PZ respectively and quantificationally for CO2 removal from high-CO2 natural gas. After studying the behaviors of CO2 absorption and desorption of the actived MDEA solution in which MDEA and the activated solvent of MDEA were at different concentrations, PZ was selected as the activator of MDEA solution in desulfurization.By studying the mechanism of CO2 absorption into PZ-activated MDEA aqueous solution,thermodynamic and dynamic models in CO2-MDEA-PZ-H2O system, this paper pointed out the direction of mathematical model building and optimizing. After studying the the influences of partial pressure of CO2 and absorption temperature to the activation characteristics of the PZ, it was proved that PZ could adapt to the changes of partial pressure of CO2 in feed gas and absorption temperature, and that adding a small amount of PZ into MDEA solution can substantially increase the reaction rate between MDEA and CO2. It was suggested that the mass fraction of PZ in activated MDEA decarbonization absorption solution was 3%～5%.By adopting PZ-activated MDEA aqueous solution as absorption solvent for CO2 removal, three different desulfurization process, including 1-Stage absorption+multi-stage flash process,1-Stage absorption+(flash+stripping) process and 2-Stage absorption+ (flash+stripping) process were is simulated respectively. After analyzing the influences of critical process parameters in three different process to CO2 degree of purification and energy consumption, this paper pointed out their degree of purification, energy consumption and suitable applications. Directing at the existing problems, this paper proposed process improvement measures to improve the CO2 removal efficiency, reduce the solvent loss and comprehensive energy consumption of decarbonization apparatus.At last, through a in-depth research of a decarbonization apparatus of high-CO2 gas field, this paper pointed out the influences of the amount of natural gas to be treated, CO2 content in natural gas, temperature of reboiler and CO2 loading in in aqueous solutions of MDEA to comprehensive energy consumption, and analyzed its measures to save energy and effect. After analyzing the energy consumption, taking process improvement measures can reduce the comprehensive energy consumption by about 23.37%.