Analysis of the performance of a sintered stainless steel wire mesh filter for cryogenic liquid purification

As a traditional and mature solid-liquid separating technique, filtration has been adopted in cryogenic liquid purification system owing to its low energy cost, simplified system, long lifetime and high purifying efficiency. Whereas, few data or result of filtration performance at low temperature is put forward in literatures, most of which are related to room and high temperatures applications. Furthermore, as an excellent cryogenic material, stainless steel medium is suitable for cryogenic liquid filtration, which is also seldom reported. In this paper, we propose a filtration system for purifying CO₂ particles from liquid nitrogen using a sintered stainless steel wire mesh filter with a nominal filtration degree of 0.5 μm, and characterize the separation behavior of this kind of filter medium at cryogenic temperature. Experimental results show that the whole filtration process can be divided into three stages with sufficient particle concentration in the feed slurry according to the evolution of pressure drop. Differences between surface filtration and depth filtration are demonstrated, and the influence of growth of filter cake is characterized. Pressure drop increases with increasing feed slurry flow and CO₂ concentration, and evolution tendency of filtration efficiency is affected by its calculation method. By comparison with the filtration at room and high temperatures, the effects of temperature on the fluid and media are emphasized.