Use of domestic polypropylene mesh materials for spray traps in sulfuric acid production

Abstract

Knitted mesh spray traps have been widely used in sulfuric acid production since the 1980's. To ensure high chemical stability in service under severe conditions, the meshes are made from corrosion-resistant steel, polypropylene, or fluoroplastic.When operating in an ascending stream, the filtration rate is usually 3-4.5 m/sec with hydraulic resistance 200-400 Pa. The collection efficiency for droplets larger than 5 ~tm is -0.9.Complex spray traps are also of great interest today. Judging from the patent literature, authors are working on the structure of the mesh, changing the strand diameter, the shape and dimensions of the mesh, and the porosity of the stacks.In Russia, sulfuric acid installations are used at the outlet of which are set polypropylene mesh spray traps in the form of cylinders of diameter 40 mm and height 200 ram. The throughput of a single element is about 3.8 m3/h, and the total number of elements in an apparatus can be as high as 2500.With the goal of replacing imported material used in mesh spray traps with domestic material, we conducted comparative tests on three samples of polypropylene mesh: two domestic and one from the Thopse company (Denmark).The tests were conducted on a standard experimental apparatus The tests were conducted at a filtration rate of 3.2 m/sec and initial mist droplet concentration 4.5-5.05 mg/m 3, the hydraulic resistance of the samples ranged from 190 to 240 Pa, the droplet collection efficiency ranged from 0.45 to 0.5.We calculated the mist droplet collection efficiency from the formulas given in [2], for d m = 0.82 ~tm; lg~p = 0.72; Ap = 215 Pa, which gave a theoretical value for the droplet collection efficiency equal to 0.45, i.e., comparable with practical data.A recalculation using the same formulas for the values d m = 5 ~tm and lgtSp = 0.3 (parameters for the droplet size distribution typical for spray traps) for Ap = 215 Pa showed that the spray collection efficiency in this case is increased up to 0.97.Thus the tests confirm that it is possible to effectively use domestic propylene mesh materials for spray traps in sulfuric acid production.