Experiment Study Of Regeneration Process Intensification From FCC Gasline Sweetening Process By Higee

A certain amount of mercaptan is contained in light oil,such as LPG and gasline. Mercaptan can cause a foul semll and reduce the stalility and quality of oils. Besides, mercaptan is corrosive itself. So,mercaptan should be removed or transformed to RSSR, which is less harmful.The current gasline standard for mercaptan sulfur is=0.001%,or passing doctor test.With the development of FCC gasline selective hydrogenation desulfurization technology at home and abroad, the caustic extraction sweetening process has been widespread used for the LCN of FCC gasline sweetening operation as associated process, can realize the reduce of the total sulfur and avoid the loss of octane number.Conventional regeneration of spend caustic is usually performed in oxidation tower. But there are problems of ineffective gas-liquid mass transfer and high energy consumption which lead to large quantity of waste caustic and high total sulfur content in treated FCC gasline.This work studied the regularity of different operational conditions(temperature, gas-liquid ratio, rotating speed, mercaptan sodium concentration, and NaOH concentration)on the conversion rate of mercaptan sodium, and the regularity of temperature, gas-liquid ratio on the removal rate of RSSR under non-catalytic system. The work also studied the regularity of temperature, gas-liquid ratio on the coupling process of reaction and separation under catalytic system and found the optimal conditions. The work found that raise the temperature and gas-liquid ratio benifiting the conversion rate of mercaptan sodium and the removal rate of RSSR. Conversion rate of mercaptan sodiume can reach 97.8% and the removal rate of RSSR can reach above 99.0% on the conditions of T=45～55℃,G/L=150-250,ω=800-1000r/min.On this basis, This work studied the multi-stage extraction experiment, the results showed that by repeated recycle, the removal rate of mercaptan maintained above 96.0%, unreacted mercaptan sodium’s content was below 50jug/g, RSSR’s content was below 20/ug/g. Experiments indicated that the Higee technology can realize high efficiency regeneration of spend caustic,solve the accumulation of sulfur in recycle caustic and prolong the phase of usage cycle.Higee technology integrates two originally independent unit operations into one by coupling reaction and separation processes. It can greatly improve the productivity and reduce equipment investment. Compared with traditional oxidation tower, the Higee technology has many advantages including higher rate of conversion, larger ratio of gas-liquid, easy to operated, more stable operation, So the Higee-regeneration technology has good prospects for industrial application.