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.

A method for determining polymer concentration can include synthesizing a polymer in a reactor under a set of parameters, wherein the reactor comprises a solution mixture having a refractive index, and wherein the solution mixture comprises a solvent, a polymer, and optionally a monomer, wherein the solution mixture has a polymer concentration; measuring the refractive index of the solution mixture; comparing the refractive index of the solution mixture with a calibration curve; and identifying the polymer concentration in the solution mixture. A system for determining polymer concentration can include a reactor containing a solution mixture comprising a solvent, a polymer, and optionally a monomer; a flash vessel fluidly coupled to the reactor to receive the solution mixture from the reactor; and a first refractometer fluidly coupled to the reactor, placed between the reactor and the flash vessel, and configured to measure a refractive index of the solution mixture.

Provided are integrated processes for the conversion of beta propiolactone to acrylic acid. Systems for the production of acrylic acid are also provided.

The present invention discloses methods for removing volatile components from an ethylene polymer effluent stream from a polymerization reactor, and related polyethylene recovery and volatile removal systems. In these methods and systems, the polymer solids temperature is increased significantly prior to introduction of the polymer solids into a purge column for the final stripping of volatile components from the polymer solids.

Reactor systems, reactor coolant systems, and associated processes for polymerizing polyolefins are described. The reactor systems generally include a reactor pipe and a coolant system, in which the coolant system includes a jacket pipe surrounding at least a portion of the reactor pipe to form an annulus therebetween, at least one spacer coupling the jacket to the reactor pipe, and a coolant which flows through the annulus to remove heat from the reactor pipe. At least one of the external surface of the reactor pipe, the internal surface of the jacket, and at least one spacer, are independently modified, for example by polishing, coating, or reshaping, to reduce the fluid resistance of the coolant flow through the annulus.

The invention relates to a process and system for the continuous polymerization of one or more -olefin monomers comprising the steps of: a) introducing catalyst and/or polymer from at least one loop reactor to at least one second reactor b) withdrawing fluids from the at least one second reactor c) cooling fluids comprising the withdrawn fluids with a cooling unit d) introducing the cooled fluids to a separator to separate at least part of the liquid from these fluids to form a liquid phase and a gas/liquid phase e) introducing the gas/liquid phase below to the reactor below a distribution plate f) introducing the liquid phase to a settling tank to separate liquid from fines that settle down in the settling tank g) introducing liquid from the settling tank upstream of the cooling unit, h) introducing the slurry comprising solid polymer particles from the settling tank to the at least one loop reactor.

Systems and methods for improved degassing of polymer flake are provided herein. These systems include a polymerization reactor configured to polymerize one or more olefin monomers and produce a product stream comprising solid polymer flake entrained in a fluid; a flash chamber configured to separate the solid polymer flake from the fluid and to produce a fluid stream and a concentrated stream; and a first degassing chamber configured to separate the concentrated stream by contacting the concentrated stream with a purge fluid comprising one or more light hydrocarbons to produce a partially degassed polymer flake stream and a purge fluid stream.

Methods of controlling olefin polymerization reactor systems are provided herein. In some aspects, the methods include a) selecting n input variables, each input variable corresponding to a process condition for an olefin polymerization process; b) identifying m response variables, each response variable corresponding to a measurable polymer property; c) adjusting one of more of the n input variables in a plurality of polymerization reactions using the olefin polymerization reactor system, to provide a plurality of olefin polymers and measuring each of the m response variables as a function of the input variables for each olefin polymer; d) analyzing the change in each of the response variables as a function of the input variables to determine the coefficients; e) calculating a Response Surface Model (RSM) using general equations for each response variable determined in step d) to correlate any combination of the n input variables with one or more of m response variables; f) applying n selected input variables to the calculated Response Surface Model (RSM) to predict one or more of m target response variables, each target response variable corresponding to a measurable polymer property; and g) using the n selected input variables I.sup.s1 to I.sup.sn to operate the olefin polymerization reactor system and provide a polyolefin product.

Loop-Loop-gas-phase reactor polypropylene plant and process for producing polypropylene and polypropylene copolymers.