Reduction of fouling in high pressure reactors
AssigneeNOVA Chemicals (International) S.A.
InventorsWilliam Joseph Tchir, Eric Cheluget
Life of this patent
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Abstract
The Application of equations of state to experimental and literature data permits the formation of a model and phase diagram(s) that show under what conditions polyethylene is likely to precipitate out of a high pressure solution of polyethylene in supercritical ethylene. This then permits a better definition to run a high pressure reactor to reduce the likelihood of phase separation, loss of cooling and potentially decomposition of the reactor contents.
Claims17
A method to determine the curve of the liquid liquid equilibrium boundary as a function of molecular weight distribution (MWD) for a multitude of different products comprising from about 80 to about 100 wt. % of ethylene and about 0 up to about 20 weight % of one or more C3-8 alpha olefins having a molecular weight from about 8,000 to about 500,000 produced in super critical ethylene in a high pressure reactor at temperatures from about 80° C. to about 350° C. and pressures from about 100 MPa to about 350 MPa comprising:
- a) modeling experimental or literature data for the liquid liquid equilibrium using an equation of state model to describe the effects of the molecular weight and the polydispersity of the polyethylene on the liquid liquid equilibrium curve
- b) determining the composition-specific parameters of the model from a);
- and,
- c) applying the resultant equation of state model to the temperature, pressure and composition conditions of the reaction to generate the liquid liquid equilibrium boundary and optionally the critical polymer concentration.
A method of operating a polymerization of a mixture of not less than about 80 wt % ethylene and up to about 20 wt % of one or more C3-8 alpha olefin monomers at a pressure from about 100 to about 350 MPa and a conversion wherein during the initial conversion of up to about 10 wt % of polymer wherein the temperature is maintained above about 125° C. [to about 135° C.].
Dependencies are inferred from the claim text.