Application of optimized microchannel separator to maximize the reuse efficiency of purified water in the petrochemical industry

Abstract

In the petrochemical industry, water is purified through a steam stripping system. However, the generated water contains approximately 5–10 mg/L of suspended solids (SS), which does not meet the high-pressure air-cooled water standard (SS ≤0.2 mg/L) proposed by the American Petroleum Institute (API). Therefore, additional efforts are needed to reduce the content of SS and facilitate the recycling of water resources, in addition to saving energy and reducing emissions. This study proposed a physical separation method based on microchannel technology, after which a laboratory-scale experimental study was conducted to assess the influence of important parameters such as bed height, filler type, and particle size on the separation performance of the microchannel separator. Next, a 1 m3/h pilot-plant was established to comprehensively evaluate the removal efficiency and operational stability of SS in the purified water. Our study found that in weakly alkaline purified water, when the filler bed height was greater than 1500 mm, and using 0.105–0.125 mm glass beads, the effluent SS could reach 0.2 mg/L and purified water could be stably obtained with a 95% recovery rate. Therefore, it was estimated that a 100 m³ /h industrial-scale installation could save approximately $1100,000 in salt water and effluent treatment alone, in addition to reducing the annual CO2 emissions by approximately 15,000 t. This is a low-cost method that does not require any additional chemicals while delivering high-efficiency separation, which reduces the demand for fresh water by petrochemical companies, increases corporate benefits, and meets the requirements of emission reduction and environmental protection.