Fabrication of Industrial-Scale Porous Stainless Steel Membrane Tubes and Their Applications
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https://doi.org/10.1007/s11837-020-04392-1 2020 The Minerals, Metals & Materials Society
SURFACE ENGINEERING: APPLICATIONS FOR ADVANCED MANUFACTURING
Fabrication of Industrial-Scale Porous Stainless Steel Membrane Tubes and Their Applications K. YANG,1 J. WANG,1 B.J. YANG,1 and H.P. TANG
1,2
1.—State Key Laboratory of Porous Metal Materials, Northwest Institute for Nonferrous Metal Research, Xi’an 710016, China. 2.—e-mail: [email protected]
A series of industrial-scale 316L stainless steel membrane tubes (U60 mm 9 1000 mm) was fabricated by wet spray coating three membrane powders (20 lm; 12 lm; 4 lm) onto a pre-sintered 316L stainless steel support tube, followed by sintering. The influence of the membrane powder size and spray coating times or number of spray coating layers on the structure and permeability of the as-sintered membrane tubes was analyzed in detail. A permeability model has been formulated according to the resistance-in-series model based on Darcy’s law. It is shown that the model can reasonably describe the permeability of as-sintered stainless steel membranes. A good balance between the filtration accuracy and the permeability can be achieved by fabricating an ultra-thin metallic membrane structure on the surface of a presintered stainless steel support tube. The gas separation efficiency of the asfabricated 316L stainless steel membrane reached 99.8% for the 0.3-lm dust particles. The as-sintered porous 316L membrane (U60 mm 9 1000 mm) was used to filter hot gas mixtures of CO and C4NiO4 in continuous industrial operations for 4 months and demonstrated outstanding performance.
INTRODUCTION The membrane process is a highly efficient and low-cost technique for separation and purification.1 As an important part and derivative of membranes, porous metallic membranes exhibit excellent thermal shock resistance, weldability, and mechanical properties.2,3 Microfiltration (MF) is a separation technique for removing micron-sized particles, such as bacteria, yeast cells, colloids and smoke particles, from suspensions or gases.4 Most emerging applications of metallic MF membranes are concerned with the filtration accuracy, permeability and cost. In the current state of the art, the study of metallic membranes is centered on the filtration accuracy, so that most MF membranes are designed to consist of several layers with a gradual decrease in pore size towards the feed side of the membrane. For example, Li et al.2 prepared a ceramic-metallic composite membrane with two intermediate layers on macroporous stainless steel substrates to inhibit
(Received July 28, 2020; accepted September 14, 2020)
the top layer infiltration. The interlayer can be used to improve the surface roughness of the porous support for the top layer deposition and to suppress the cracking of the microporous layer during the sintering process, but it may result in a significant decline in permeability due to the increased resistance.5–7 Recently, researchers have explored the preparation of a porous MF membrane onto the macroporous
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