Optimization of heat removal in a gas-phase fluidized-bed process

A process for preparation of polyethylene from feed ethylene in which the impurity acetylene is catalytically hydrogenated to ethylene, impurity ethylene is partially converted to ethane, and the remaining ethylene is polymerized to polyethylene in the gas phase in a fluidized bed reactor is new. A process for preparation of polyethylene from feed ethylene including (a) a hydrogenation stage (a) in which the feed ethylene containing impurities and secondary components such as acetylene and ethane, with removal of the acetylene by catalytic hydrogenation with hydrogen to ethylene, and partial conversion of the ethylene to ethane, and a polymerization stage (b) in which the ethylene remaining in stage (a) is converted to polyethylene in the gas phase in a fluidized bed (FB) reactor, with feeding in of the FB gas so that on entry into the reactor the ethene and 20-70 vol.% of the ethane relative to the total volume of fluidized bed gas and also other components are included, and in (a) in addition to the ethane present in the feed-ethylene the ethylene is so far converted to ethane that in stage (b) the established concentration can be maintained. An Independent claim is also included for: (1) A FB reactor setup including: (a) a hydrogenation reactor (1) with an ethylene feed pipe (2) and a hydrogen feed pipe (3), and (b) a fluidized bed reactor (10),a catalyst feed (11), a polyethylene outlet (3), separators (14) and (7), and gas line (22).