| 摘要 |
A hydrocarbon stream is cracked in Plant A to produce a hot gaseous stream which is separated in a fractionator B. A gaseous stream containing hydrogen and C1-C4 hydrocarbons is taken from the fractionator B, is raised in pressure in compressor C and is cooled in a heat exchanger D. The cooled gaseous stream is separated in a demethaniser E, and an off-gas comprising hydrogen and C1 to C3 hydrocarbons is withdrawn from the demethaniser E. The off-gas is subjected to separation by pressure swing adsorption or temperature swing adsorption at an adsorption temperature of about 0 to about 250 DEG C in a bed of adsorbent which selectively adsorbs ethylene and propylene, thereby adsorbing substantially all of the ethylene and propylene from the gas stream. The ethylene and/or propylene is recovered upon bed regeneration. <IMAGE> |
