Treating Methanol-to-Olefin Quench Water by Minihydrocyclone Clarification and Steam Stripper Purification

Separation performance of hydrocyclone oil removal device influenced by oil droplet trajectory and oil drop characteristics

Cyclone separation is an effective method for the treatment of oily wastewater from offshore oil production platforms. There is a lack of research on the impact of dispersion on the separation efficiency of current liquid-liquid separation hydrocyclones. A numerical simulation method was used to study the effect of the oil droplet characteristic parameters on the separation efficiency of a hydrocyclone oil removal device. An analysis of the trajectory of oil droplets revealed the oil removal mechanism of the hydrocyclone oil removal device: under the guidance of tangential velocity, the oil-water mixed fluid in the equipment generates different centrifugal forces due to the density difference, so oil and water adopt different flow paths to flow out. The effects of the particle diameter, velocity, and concentration of the inlet oil droplet on the separation efficiency were investigated. The droplet size had a positive effect on the separation efficiency, the oil concentration had a negative effect on the separation efficiency, and the speed of the oil drop was directly proportional to the separation efficiency within a certain range. These studies improved the basis for the efficient application of hydrocyclone oil removal devices.

Cooperative physical separation of oil and suspended solids from methanol-to-olefin wastewater: A pilot study

Methanol-to-olefin (MTO) is an important non-petroleum chemical process for the preparation of light olefins. However, the MTO process consumes copious amounts of water and produces large amounts of untreated effluent. Therefore, the realization of efficient wastewater treatment and recycling is key to the green low-carbon development of MTO. Here, a cooperative process combining swirl regenerating micro-channel separation (SRMS) and combined fibrous coalescence (CFC) technologies was proposed to separate high contents of oil and suspended matter in MTO wastewater. Using a pilot device with a treatment capacity of 1 m3/h, the average oil content in MTO wastewater decreased from 750 mg/L to <30 mg/L, while the average content of suspended matter decreased from 108 mg/L to <15 mg/L. Compared with a commercial MTO wastewater treatment process (olefin production capacity of 0.6 million tons per annum), the proposed method could reduce wastewater discharges and costs by 57% and US$ 0.23 million per annum respectively. Equipment costs and operational energy consumption were also reduced by 30% and >95% respectively. The combined process may provide the basis for the green and sustainable treatment of MTO wastewater and its recycling.

Numerical Simulation of Flow Field Characteristics and Separation Performance Test of Multi-Product Hydrocyclone

A traditional hydrocyclone can only generate two products with different size fractions after one classification, which does not meet the fine classification requirements for narrow size fractions. In order to achieve the fine classification, a multi-product hydrocyclone with double-overflow-pipe structure was designed in this study. In this work, numerical simulation and experimental test methods were used to study the internal flow field characteristics and distribution characteristics of the product size fraction. The simulation results showed that in contrast with the traditional single overflow pipe, there were two turns in the internal axial velocity direction of the hydrocyclone with the double-overflow-pipe structure. Meanwhile, the influence rule of the diameter of the underflow outlet on the flow field characteristics was obtained through numerical simulation. From the test, five products with different size fractions were obtained after one classification and the influence rule of the diameter of the underflow outlet on the size fraction distribution of multi-products was also obtained. This work provides a feasible research idea for obtaining the fine classification of multiple products.