Analysis And Studies On The Failure Mechanism Of Desulfurization Solution Of Natutal Gas Purification Plant

This paper aimed at the failure problem of gas desulfurization solution of Erdos gas field with a systematic study.The main findings were followed:1. The major impurities in desulfurization solution are suspended solids, heat stable salts, chlorides and other types of polymeric organic compounds,which was obtained through a variety of analytical methods.And the content of DEA and MDEA in desulfurization amine solution were determined by capillary gas chromatography internal standard method.2. The influence law which was the suspended solid, heat stable salts and organic impurities impacting on the absorption and desorption of desulfurization solution were found by sbsorbing device simulation experiment as follows:(1)The main influence factors of suspended solid absorption ability and regeneration capacity to MDEA, absorption ability to H2S and CO2were FeS and Fe2(SO4)3.The effect factors order was Fe2(SO4)> FeS.(2)The thermal stability of salts and organic impurities affected on the absorption and regeneration to MDEA as follows:Fe3+、HCOO-、CH3COO-and C2O42-had great impact on the absorption capacity to MDEA.The effect size of Fe3+、CH3COO-、C2O42-and HCOO-decreased successively;Na+、 K+、F-、Cl-and SO42-had no significant effect;K+、Cl-、HCOO-、CH3COO-、C2O42-、had great impact on the regeneration process to MDEA; F-、SO42-、Fe3-、Na+followed.Fe3+、HCOO-、CH3COO-and C2O42-had a significant effect on the absorption capacity to H2S; Na+、K+、F-、Cl-and SO42-almost had no effect;Fe3+and CH3COO-were the main factors of affecting the removal to CCO2；HCOO-and C2O42-also impacted on the absorption capacity to CO2.But the impact was less than Fe3+and CH3COO-; Na+、K+、 F-、Cl-and SO42-had no influence.Piperazine substances affecting the absorption and regeneration capacity to MDEA were very significant, and glycols were little.3. The results of impurities affected the corrosion rate as follows: Cl-and SO42-had no influence.(3)Piperazine substances affecting the absorption and regeneration capacity to MDEA were very significant, and glycols were little.3.The influence of impurities to MDEA solution corrosive were got as follows:(1)Under low temperature, FeS and Fe2(SO4)3had very significant effect on corrosion and pitting corrosion rate of hanging pieces, while Fe3O4had very little effect.Under high temperature, FeS、Fe3O4and Fe2(SO4)3showed a strong influence,whose varied concentrations directly determined the level of both corrosion and pitting corrosion rate.(2)Under low temperature, Cl-、Fe3+、HCOO-、CH3COO-had very significant effect on corrosion and pitting corrosion rate of hanging pieces;Fe3+was maximum on corrosion rate; Cl-、HCOO-and CH3COO-decreased successively; The influence of Fe3+on the pitting corrosion rate was the maximum;CH3COO-followed, Cl-and HCOO-were minimum.Under high temperature, Cl-was the main factor of affecting the corrosion rate.(3)Whether the temperature was high or low, piperazine substances on the corrosion rate was more significant,while glycols had no significant effect.4.The SEM analysis of corrosion morphology and the XRD of corrosion product about hanging pieces study showed that CO2and H2S dissolved in free water wre the main reason causing the corrosion to MDEA reboiler, and pitting corrosion caused by Cl-could not be underestimated.