Abstract: Method for switching between steady-state and non-steady-state operations of a process for the production of a polymer by polymerization of a monomer in the presence of a comonomer and/or hydrogen. The process includes (a1) at non-steady-state controlling the process based on the ratio of comonomer to monomer in the reactor, and (b1) at steady-state controlling the process based on the flow ratio of comonomer to monomer to the reactor, and/or (a2) at non-steady-state controlling the process based on the ratio of hydrogen to monomer in the reactor, and (b2) at steady-state controlling the process based on the flow ratio of hydrogen to monomer to the reactor.

Abstract: Process for the polymerization of olefins in a gas phase fluidized bed reactor, by i) passing a fluidizing gas to the reactor to fluidize a bed of polymer particles therein, ii) withdrawing the fluidizing gas from the reactor, iii) cooling all or a portion of the fluidizing gas withdrawn from the reactor to a temperature at which a portion of the components of the fluidizing gas condense to form condensed liquid, and iv) passing condensed liquid and non-condensed components of the fluidizing gas back to the reactor. A reservoir of condensed liquid downstream of the cooling step is provided, and variations in the inventory of the condensed liquid are made in order to control the temperature in the reactor.

Abstract: The present invention relates to a method for switching between steady-state and non-steady-state operations of a process for the production of a polymer by polymerisation of a monomer in the presence of a comonomer and/or hydrogen which process comprises: a1. At non-steady-state controlling the process based on the ratio of comonomer to monomer in the reactor, and b1. At steady-state controlling the process based on the flow ratio of comonomer to monomer to the reactor, and/or a2. At non-steady-state controlling the process based on the ratio of hydrogen to monomer in the reactor, and b1. At steady-state controlling the process based on the flow ratio of hydrogen to monomer to the reactor.

Abstract: The present invention relates to a process for the polymerisation of olefins in a gas phase fluidised bed reactor, and in particular provides a polymerisation process comprising: i) passing a fluidising gas to the reactor to fluidise a bed of polymer particles therein, ii) withdrawing the fluidising gas from the reactor, iii) cooling all or a portion of the fluidising gas withdrawn from the reactor to a temperature at which a portion of the components of the fluidising gas condense to form condensed liquid, and iv) passing condensed liquid and non-condensed components of the fluidising gas back to the reactor, wherein there is provided a reservoir of condensed liquid downstream of the cooling step, and variations in the inventory of the condensed liquid are made in order to control the temperature in the reactor.