Apparatuses and processes that produce multimodal polyolefins, and in particular, polyethylene resins, are disclosed herein. This is accomplished by using two reactors in series, where one of the reactors is a multi-zone circulating reactor that can circulate polyolefin particles through two polymerization zones optionally having two different flow regimes so that the final multimodal polyolefin has improved product properties and improved product homogeneity.

Apparatuses and processes that produce multimodal polyolefins, and in particular, polyethylene resins, are disclosed herein. This is accomplished by using two reactors in series, where one of the reactors is a multi-zone circulating reactor that can circulate polyolefin particles through two polymerization zones optionally having two different flow regimes so that the final multimodal polyolefin has improved product properties and improved product homogeneity.

Apparatuses and processes that produce multimodal polyolefins, and in particular, polyethylene resins, are disclosed herein. This is accomplished by using two reactors in series, where one of the reactors is a multi-zone circulating reactor that can circulate polyolefin particles through two polymerization zones optionally having two different flow regimes so that the final multimodal polyolefin has improved product properties and improved product homogeneity.

Apparatuses and processes that produce multimodal polyolefins, and in particular, polyethylene resins, are disclosed herein. This is accomplished by using two reactors in series, where one of the reactors is a multi-zone circulating reactor that can circulate polyolefin particles through two polymerization zones optionally having two different flow regimes so that the final multimodal polyolefin has improved product properties and improved product homogeneity.

Apparatuses and processes that produce multimodal polyolefins, and in particular, polyethylene resins, are disclosed herein. This is accomplished by using two reactors in series, where one of the reactors is a multi-zone circulating reactor that can circulate polyolefin particles through two polymerization zones optionally having two different flow regimes so that the final multimodal polyolefin has improved product properties and improved product homogeneity.

Apparatuses and processes that produce multimodal polyolefins, and in particular, polyethylene resins, are disclosed herein. This is accomplished by using two reactors in series, where one of the reactors is a multi-zone circulating reactor that can circulate polyolefin particles through two polymerization zones optionally having two different flow regimes so that the final multimodal polyolefin has improved product properties and improved product homogeneity.

The present invention relates to a process for the continuous preparation of a polyolefin in a reactor from one or more -olefin monomers of which at least one is ethylene or propylene, wherein the reactor comprises a fluidized bed, an expanded section located at or near the top of the reactor, a distribution plate located at the lower part of the reactor and an inlet for a recycle stream located under the distribution plate, wherein the process comprisesfeeding a polymerization catalyst to the fluidized bed in the area above the distribution platefeeding the one or more -olefin monomers to the reactorwithdrawing the polyolefin from the reactorcirculating fluids from the top of the reactor to the bottom of the reactor, wherein the circulating fluids are cooled using a heat exchanger, resulting in a cooled recycle stream comprising liquid, and wherein the cooled recycle stream is introduced into the reactor using the inlet for the recycle stream wherein a stream comprising a thermal run away reducing agent (TRRA-containing stream) is introduced into the expanded section during at least part of the polymerization process, wherein said TRRA-containing stream is brought into contact with at least part of the interior surface of the expanded section.

A method for processing a chemical stream includes contacting a feed stream with a catalyst in an upstream reactor section of a reactor having the upstream reactor section and a downstream reactor section, passing an intermediate product stream to the downstream reactor section, and introducing a riser quench fluid into the downstream reactor section, upstream reactor section, or transition section and into contact with the intermediate product stream and the catalyst to slow or stop the reaction. The method includes separating at least a portion of the catalyst from the product stream, passing the product stream to a product processing section, cooling the product stream, and separating a portion of the riser quench fluid from the product stream. The riser quench fluid separated from the product stream may be recycled back to the downstream reactor section, upstream reactor section, or transition section as the riser quench fluid.

A system and method for preparing a high-purity vanadium electrolyte, comprising preparing a low-valence vanadium oxide with vanadium oxytrichloride by ammonium salt precipitation and fluidization reduction, and preparing the high-purity vanadium electrolyte at a low temperature by adding a sulfuric acid solution and clean water under the conditions of ultrasound-assisted dissolution and activation. Efficient utilization of heat is achieved through heat exchange between the ammonium salt and the reduction tail gas and heat exchange between the reduction product and fluidized nitrogen gas. Ammonia gas in the reduction tail gas is recovered for precipitation of vanadium to achieve the recycling of ammonia gas. An internal member is arranged in the reduction fluidized bed to realize the precise regulation of the valence state of the reduction product. Furthermore, ultrasound-assisted dissolution and activation are employed to prepare the vanadium electrolyte at a low temperature, thereby improving the activity of the electrolyte.

A subject of the invention is a fluidized-bed reactor for producing granular polycrystalline silicon. The fluidized-bed reactor comprises a segmented reactor tube, which is disposed between a reactor top and a reactor bottom, a heating facility, at least one nozzle for supplying fluidizing gas, at least one nozzle for supplying reaction gas, a facility for supplying silicon seed particles, a product removal line, and an offgas removal line. The segmented reactor tube comprises a base segment and at least one spacer segment, there being disposed, between base segment and spacer segment, a flat seal made from a carbon-containing material, the spacer segment consisting of a material which, within a temperature range from 100 to 950 C., has a thermal conductivity of <2 W/mK.