Performance and applications of flow-guided sieve trays for distillation of highly viscous mixtures

Abstract

With a particular focus on the distillation of highly viscous or self-polymerized mixtures, this study reports the hydrodynamic and mass transfer performance of two flow-guided sieve trays, including their pressure drop, entrainment, weeping and tray efficiency, obtained experimentally with an air-water/oxygen system in a Φ600 mm plexiglass column. The results show that the 8 mm hole flow-guided sieve tray tested shows better characteristics than the 7 mm flow-guided hole tray in terms of pressure drop and mass transfer. Then we present practical industrial examples of applications of the flow guided trays for distillation of viscous mixtures, i.e., the separation of vinyl acetate (VAC) from a polyvinyl acetate (PVAC) polymer solution with dynamic viscosity μ=50,000 mPas, the separation of highly unsaturated C5 mixtures by extractive distillation, and the distillation of thick, condensed and highly viscous fermentation mixtures made from fermented mash. It is demonstrated that flow-guided sieve trays with relatively large holes are an excellent candidate for distillation of mixtures with suspended solids, or concentrated/self-polymerized polymer solutions.

State‐of‐the‐Art of Advanced Distillation Technologies in China

“…The Beijing University of Chemical Technology focuses on the research and application of new sieve towers. The flow‐guided sieve trays (FGSTs) 52 have advantages of low pressure drop, high efficiency, throughput capacity, and simplified configuration. Such trays are suitable for low‐pressure rectification and separation on large‐scale equipment and have been used successfully in industry.…”

A distillation tray with high efficiency and excellent operating flexibility for viscous mixture separation

“…Additionally, on the lip of each valve, five sieve pores and one flow-guided pore are installed. In order to compare the performance, the two types of FGS-VTs were manufactured with similar structure parameter to FGST [8,11], except there are valves on the FGS-VTs. With the increasing of the gas velocity, the valves open gradually, and the opening area increases little by little to fit the varying operating conditions.…”

“…Mahiout and Vogelpohl [4][5][6] have studied the impact of viscosity on the performance of sieve tray in air-glycerol-water and cyclohexanol-air-glycerol-water systems. Experiments and applications have proven that the flow-guided sieve tray (FGST) has been successfully employed to separate the mixtures containing viscous components, suspended solids, or self-polymerization polymers [8][9][10][11]. Böcker and Ronge [7] have investigated the qualitative dependence between the viscosity and the separation performance of a distillation column, and they came to the same conclusion as Mahiout and Vogelpohl.…”

“…The results indicated that the increase in viscosity deteriorated the mass transfer performance of the tray. In the revamp, the problem was solved by replacing the sieve trays with FGST [11]. The distillation of highly viscous mixtures is still a difficult-to-solve problem, and there is little theoretical knowledge and few practical applications about this field.…”

Computational fluid dynamic simulation of MVG tray hydraulics

“…Investigations and modeling work aimed at improving the performance of various distillation columns have been carried out by many researchers for many years [2][3][4].…”