GB371142A - Improvements in the purification of acetylene - Google Patents

Abstract

<PICT:0371142/IV/1> Acetylene obtained by the thermal or electrical treatment of hydrocarbon products of any kind is freed from impurities such as diacetylene, allylene, allene, butadiene, and hydrocyanic acid by cooling to a temperature below -20 DEG C. under such conditions that solidification or condensation of acetylene is avoided. The cooling may be effected in stages and under atmospheric or raised pressure. The crude acetylene may be mixed with the vapour of a solvent such as methanol, in order to avoid separation of frozen impurities. As shown, crude acetylene supplied through a pipe 6 passes through a vessel 7 containing methanol and then up a bundle of tubes 1 immersed in methanol, in which the gas is cooled, e.g. to -30 DEG C., by expanding liquid ammonia in a coil 9. The condensate comprising moisture and methanol, with or without residual solvent from the isolation of the crude acetylene, is withdrawn at 10. The gas passes through a pipe 11 up a second tube bundle 2 in which it is cooled, e.g. to -75 DEG C., by expanding liquid ethylene in a coil 13. The condensed impurities are withdrawn at 15. The ethylene used in the coil 13 may be liquefied in a coil 14 in the methanol surrounding the tubes 1. The purified acetylene passes out at 16, and may be freed from traces of impurities by means of an adsorbent such as silica gel, or used directly for the manufacture of acetaldehyde. Examples are given of the treatment of gases containing 89 and 9 per cent of acetylene respectively; in the first example, the gas is cooled to -30 DEG C. and then to -70 DEG C. under atmospheric pressure; in the second example, the gas is cooled directly to -70 DEG C. under 25 atmospheres pressure.