Industrial application of swirl regenerating micro-channel separation (SRMS) for fine catalysts removal from methanol-to-olefin quench water

Abstract

Methanol to olefin (MTO) process is a chemical technology for producing low-carbon olefins from coal-based or natural gas-based methanol, which has changed the pattern of low-carbon olefins relying on petroleum cracking. However, a large amount of fine catalyst powders circulating in the water system of the MTO plant threats the sustainability of the process severely. Previously, a pilot-scale study about swirl regenerating micro-channel separation (SRMS) technology to remove the fine waste catalyst powders from MTO quench water was reported. In this study, the SRMS equipment was scaled up to an industrial level with a processing capacity of 400 m3/h based on the results of pilot-scale experiments, and the performance of the industrial unit was monitored for over 6 months. The results obtained directly from the industrial site showed that the SRMS unit based on deep-bed filtration and swirling flow enhanced washing and desorption could effectively remove the fine catalyst particles in the quench water, and the effluent particle concentration was maintained below 20 mg/L. Furthermore, the total oil content in the quench water reduced from 43.2 mg/L to 22.8 mg/L after being processed by the SRMS unit, which demonstrates that the SRMS unit also has an appreciable ability for oil pollutants removal. After the long-term operation of the SRMS unit, the equilibrium concentration of particulate matter in the quench water was reduced to under 50 mg/L, which significantly improved the performance of the quench water heat exchanger and effectively reduced the cleaning frequency of the heat exchanger, air cooler, and other equipment in the water system. Through the industrial-scale technical comparison, this technology outperforms the other common quench water treatment methods in equipment investment, maintaining cost, freshwater supplement, and energy consumption.