Polymerisation control process

摘要

Process for maintaining a continuous gas-phase (co-) polymerization of olefins in a large fluidized bed reactor in a homogeneous mode while operating at high space time yield and condensation rate in the presence of a polymerization catalyst.

主权项

1. Process for the continuous gas-phase (co-) polymerisation of olefins in a vertical fluidised bed reactor having a first volume of at least 250 m3, wherein D and V are respectively the diameter and the volume of the first volume of the reactor, and H is the height of the first volume of the reactor, being the distance between a fluidization grid at the bottom of the fluidized bed and the top of the first volume of the reactor, wherein the diameter D is at least 4 meters and the ratio H/D is higher than 3.75, said process being operated with a condensation rate higher than 15 wt %, in the presence of a polymerisation catalyst and with a space time yield equal or higher than 120 kg/(m3×h), and wherein the operations are controlled in order to maintain the parameter DT below 2.5, whereinDT=(1-0.016*Z*X)*K*S⁢⁢T⁢⁢Y*H*Heat⁢⁢Polym3600*Vf*Rho⁢⁢PE*Cp⁢⁢PE where: Z is the condensation rate expressed in wt %, X is the weight ratio between the liquid introduced directly in the fluidised bed above the fluidisation grid and the total liquid introduced into the reactor, K is a dimensionless calibration factor equal to 1.46, STY is the Space Time Yield expressed in [kg/(m3×h)], H is the distance between the bottom of the fluidised bed and the top of the first volume of the reactor (expressed in meter), Heat Polym is the heat of polymerisation expressed in Kcal/kg Polymer Vf is the fluidization velocity of the fluidising gas (expressed in m/s), Rho PE is the polymer powder density expressed in Kg/m3, and Cp PE is the heat capacity of the solid polymer expressed in Kcal/kg·C.