Abstract:
A continuous gas-phase process for the polymerization of alpha-olefins, in particular ethylene, comprising passing an alpha-olefin monomer stream through an oil filter in order to reduce the amount of oil to less than 8 ppm, and polymerizing the thus purified monomer feed in gas-phase reactor; the reduction of the amount of oil improves the operability of the plant over time.
Abstract:
A continuous gas-phase process for the polymerization of alpha-olefins, in particular ethylene, comprising passing an alpha-olefin monomer stream through an oil filter in order to reduce the amount of oil to less than 8 ppm, and polymerizing the thus purified monomer feed in gas-phase reactor; the reduction of the amount of oil improves the operability of the plant over time.
Abstract:
Method for metering polar, antistatically acting process auxiliaries into a polymerization reactor in which the process auxiliaries are present in solution in a nonpolar solvent, wherein the electrical conductivity of the solution is measured and the amount of the process auxiliary metered in is determined from the electrical conductivity.
Abstract:
A polyethylene composition, in particular suitable for the preparation of films, and a process for preparing the same are described. The polyethylene composition of the invention comprises from 50 to 89% by weight of a first polyethylene component comprising at least one multimodal polyethylene including a plurality of ethylene polymer fractions having distinct molecular weights and comonomer contents, at least one of said plurality of ethylene polymer fractions being prepared by the use of a single site catalyst, and from 50 to 11% by weight of a second polyethylene component comprising a low or medium density polyethylene.
Abstract:
An apparatus for the polymerization of olefins, in particular ethylene, comprising a gas-phase fluidized-bed reactor (1), a recycle gas line (2) connected to the reactor for discharging and recirculating the recycle gas stream comprising the unpolymerized olefin and a cyclone (3) located in the recycle gas line for the reduction and precipitation of the solid particles entrained in the recycle gas from the reactor, with the cyclone comprising an upper section (3a) which has an essentially vertical central axis, whose wall extends along a rotationally symmetric body and which is provided with a cyclone inlet (4) arranged eccentrically relative to the central axis, a middle section (3b) which adjoins the upper section (3a) and whose wall extends along a rotationally symmetric body which tapers in a downward direction, a lower section (3c) for discharging the solid particles precipitated from the recycle gas which adjoins the middle section (3b) and whose wall extends along a rotationally symmetric body and a tube (5) extending essentially axially symmetrically down into the upper section and, if appropriate, the middle section for discharging the recycle gas which has been freed of the particles. According to the invention the ratio Hi of the distance hi from the lower end of the tube (5) extending downward into the cyclone to the intersection (6) of an imaginary extension of the wall of the downward-extending tube (5) with the wall of the middle section (3b) to the diameter di of the downward-extending tube (5) is from 3 to 8, in particular from 4 to 7.
Abstract translation:用于烯烃聚合的装置,特别是乙烯,包括气相流化床反应器(1),连接到反应器的再循环气体管线(2),用于排出和再循环包含未聚合烯烃的循环气流和 旋流器(3),其位于循环气体管线中,用于还原和沉淀夹带在来自反应器的再循环气体中的固体颗粒,旋风分离器包括具有基本上垂直的中心轴线的上部分(3a),其上壁延伸 沿着旋转对称体并且设置有相对于中心轴线偏心布置的旋风入口(4),邻近上部(3a)并且其壁沿旋转对称体延伸的中间部分(3b) 用于排出邻近中间部分(3b)并且其壁延伸的再循环气体沉淀的固体颗粒的下部分(3c) 旋转对称体和基本上轴向对称地延伸到上部的管(5)以及适当的中间部分用于排出已经没有颗粒的循环气体。 根据本发明,与从下游进入旋风分离器的管(5)的下端距离h i i的距离h i i的比例H i 向下延伸的管(5)的壁与中间部分(3b)的壁与向下延伸的管(5)的直径d iI i的假想延伸为3至 8,特别是4到7。
Abstract:
A continuous vapor-phase fluidized-bed process for the preparation of ethylene homopolymers and copolymers having a density of from 0.87 to 0.97 g/cm3 in which ethylene or mixtures of ethylene and C3-C8 a-monoolefins are (co)polymerized in the presence of a supported chromium catalyst in the polymerization zone of a vapor-phase fluidized-bed reactor under pressures ranging from 1 to 100 bar and at temperatures ranging from 30° to 125° C. in the vapor phase in an agitated bed of bulk material comprising particulate polymer, the resultant heat of polymerization is removed by cooling the recirculated reactor gas and the resulting (co)polymer is removed from the vapor-phase fluidized-bed reactor, wherein, for the preparation of a (co)polymer of a specific density d, the (co)polymerization is carried out at a temperature which is in a range restricted by an upper envelope defined by equation I T H = 171 + 6 d ′ 0.84 - d ′ ( I ) and a lower envelope defined by equation II T L = 173 + 7.3 d ′ 0.837 - d ′ , ( II ) in which the variables have the following meanings: TH is the highest reaction temperature in ° C.; TL is the lowest reaction temperature in ° C.; d′ is the numerical value of the density d of the (co)polymer to be synthesized.
Abstract:
In a continuous gas-phase polymerization process for preparing ethylene and propene homopolymers and copolymers, in which ethylene, propene or a mixture of ethylene or propene and C3-C8-&agr;-monoolefins is polymerized in the polymerization zone of a gas-phase polymerization reactor at from 30 to 125° C. and a pressure of from 1 to 100 bar in the gas phase in a bed of finely divided polymer in the presence of a catalyst, where the reactor gas is circulated to remove the heat of polymerization, polymer deposits in the circulating gas line are prevented by metering a catalyst poison having a boiling point above the maximum temperature within the circulating gas line into this circulating gas line in at most such an amount that it does not significantly impair the productivity of the catalyst in the reactor.