Abstract: A method for manufacturing polyester polymer containing waste polyester in a continuous polymerization unit that includes: a) providing an intermediate prepolymer stream from the continuous polymerization unit and diverting a portion of the intermediate polymer stream to a centrifugal mixer; b) adding waste polyester to said centrifugal mixer to obtain a homogenous melt stream, and c) combining the homogenous melt stream with the remaining portion of the intermediate polymer stream forming an outlet stream, wherein the method is characterized in that the waste polyester in step b) is not heated or melted.

Abstract: Methods of on-line control of molecular weight in continuous solid state polymerization processes. The solid state polymerization process can be a polyester process or to a polyamide process, and more specifically a poly(ethylene terephthalate) (PET) or a poly(butylene terephthalate) (PBT) or a nylon 6,6 continuous solid-state polymerization (SSP) process. An in-line viscometer melts and measures the molecular weight of the SSP resin and adjusts one or more of the process variables, i.e. reactor time, inert gas purity and inert gas temperature to maintain a constant resin molecular weight.

Abstract: The invention relates to the on-line control of the molecular weight in continuous solid state polymerization processes. In particular it is directed to a polyester process or to a polyamide process, and more specifically to a poly(ethylene terephthalate) (PET) or a poly(butylene terephthalate) (PBT) or a nylon 6,6 continuous solid-state polymerization (SSP) process. An in-line viscometer melts and measures the molecular weight of the SSP resin and adjusts one or more of the process variables, i.e. reactor time, inert gas purity and inert gas temperature to maintain a constant resin molecular weight.

Abstract: A method and apparatus for quenching and scrubbing a hot gas using a liquid in a single packed column while controlling mist formation. Hot gas is introduced at the bottom of the column and drawn upward countercurrent to the scrubbing liquid. The column has three stages, each packed and fed liquid from above. The first stage is a quench region wherein the gas flow rate, liquid flow rate and liquid temperature are controlled such that the quench rate does not exceed 5.4° C./ft2 of packing to prevent formation of an aerosol mist. The second and third stages for scrubbing employ packed regions separately supplied with increasingly cooler and purer liquid.