Desublimation of solids from vapour-gas mixture - using seed crystals in cold inert gas to accelerate process

摘要

Method comprises mixing the flow of the vapour-gas mixt. with a cold inert gas stream and cooling the mixt. together with the inert gas to a temp. below the m.pt. of the prod, Sepn. of the solid phase of the prod. of differing dispersivity takes place accompanied by pptn. of coarsely dispersed fraction of the prod. under gravity and removal of the finely dispersed fraction through the gas stream consisting of uncondensed vapours and gases. Seeding crystals, which constitute crystallisation centres, are introduced into the inert gas stream before it is mixed with the vapour-gas mixt. to be desulbimated. Pref. the seeding crystals are introduced uniformly across the flow crossection of the cold gas. Pref. also, finely dispersed fractions of solids removal by the stream of uncondensed vapours and gases are used as seeding crystals. Used typically, for the prodn. of cyanic chloride, for use in the mfr. of synthetic dyes; for producing AlCl3 for use as catalyst; prodn. of salysilic acid and other chemical, pharmaceutical, foodstuffs and similar prods. The method is considerably more effective per unti vol. than previous systems and enables the process to be economically carried out on an industrial scale.