The present invention relates to a method to prevent the fluidization of a catalytic fixed bed present in a tubular reactor operated in upward-flow configuration by estimating a pressure drop margin remaining before fluidization of the catalytic bed and adjusting the reactant gas flow in response. It relates also to a method to operate safely a furnace suitable for performing endothermic reactions containing a plurality of catalytic fixed bed reactors operated in upward-flow configuration, and to a method to debottleneck safely a catalytic fixed bed reactor involving a gas flowing in up flow direction.

A method of monitoring a solid component of a reactor feed stream in a polymer production system, comprising (a) measuring a turbidity of the reactor feed stream, wherein the reactor feed stream comprises a solid component of a polymerization catalyst system, and (b) translating the turbidity of the reactor feed stream into a concentration of the solid component in the reactor feed stream. A method of monitoring a solid component of a reactor feed stream in a polymer production system, comprising (a) measuring a turbidity of a precontactor feed stream, wherein the precontactor feed stream comprises a solid component of a polymerization catalyst system, and (b) translating the turbidity of the precontactor feed stream into a concentration of the solid component in a precontactor effluent stream, wherein the precontactor effluent stream comprises the reactor feed stream.

A method of determining multimodal polyethylene quality comprising the steps of (a) providing a multimodal polyethylene resin sample; (b) determining, in any sequence, the following: that the multimodal polyethylene resin sample has a melt index within 30% of a target melt index; that the multimodal polyethylene resin sample has a density within 2.5% of a target density; that the multimodal polyethylene resin sample has a dynamic viscosity deviation (% MVD) from a target dynamic viscosity of less than about 100%; that the multimodal polyethylene resin sample has a weight average molecular weight (M.sub.w) deviation (% M.sub.wD) from a target M.sub.w of less than about 20%; and that the multimodal polyethylene resin sample has a gel permeation chromatography (GPC) curve profile deviation (% GPCD) from a target GPC curve profile of less than about 15%; and (c) responsive to step (b), designating the multimodal polyethylene resin sample as a high quality resin.

A method of determining multimodal polyethylene quality comprising the steps of (a) providing a multimodal polyethylene resin sample; (b) determining, in any sequence, the following: that the multimodal polyethylene resin sample has a melt index within 30% of a target melt index; that the multimodal polyethylene resin sample has a density within 2.5% of a target density; that the multimodal polyethylene resin sample has a dynamic viscosity deviation (% MVD) from a target dynamic viscosity of less than about 100%; that the multimodal polyethylene resin sample has a weight average molecular weight (M.sub.w) deviation (% M.sub.wD) from a target M.sub.w of less than about 20%; and that the multimodal polyethylene resin sample has a gel permeation chromatography (GPC) curve profile deviation (% GPCD) from a target GPC curve profile of less than about 15%; and (c) responsive to step (b), designating the multimodal polyethylene resin sample as a high quality resin.

A method of monitoring a solid component of a reactor feed stream in a polymer production system, comprising (a) measuring a turbidity of the reactor feed stream, wherein the reactor feed stream comprises a solid component of a polymerization catalyst system, and (b) translating the turbidity of the reactor feed stream into a concentration of the solid component in the reactor feed stream. A method of monitoring a solid component of a reactor feed stream in a polymer production system, comprising (a) measuring a turbidity of a precontactor feed stream, wherein the precontactor feed stream comprises a solid component of a polymerization catalyst system, and (b) translating the turbidity of the precontactor feed stream into a concentration of the solid component in a precontactor effluent stream, wherein the precontactor effluent stream comprises the reactor feed stream.

A method of monitoring a solid component of a reactor feed stream in a polymer production system, comprising (a) measuring a turbidity of the reactor feed stream, wherein the reactor feed stream comprises a solid component of a polymerization catalyst system, and (b) translating the turbidity of the reactor feed stream into a concentration of the solid component in the reactor feed stream. A method of monitoring a solid component of a reactor feed stream in a polymer production system, comprising (a) measuring a turbidity of a precontactor feed stream, wherein the precontactor feed stream comprises a solid component of a polymerization catalyst system, and (b) translating the turbidity of the precontactor feed stream into a concentration of the solid component in a precontactor effluent stream, wherein the precontactor effluent stream comprises the reactor feed stream.

A gas flow metrology system for a substrate processing system includes N primary valves selectively flowing gas from N gas sources, respectively, where N is an integer. N mass flow controllers are connected to the N primary valves, respectively, to flow N gases from the N gas sources, respectively. N secondary valves selectively flow gas from the N mass flow controllers, respectively. A gas flow path connects the N secondary valves to a flow metrology system located remote from the N secondary valves, wherein the gas flow path includes a plurality of gas lines. A controller is configured to perform a hybrid flow metrology by selectively using a first flow metrology and a second flow metrology that is different from the first flow metrology to determine an actual flow rate for a selected gas at a desired flow rate from one of the N mass flow controllers.

Devices and methods for controlling the properties of chemical species during time-dependent processes. A device includes a reactor for containing one or more chemical species of a time-dependent process, an extraction pump for automatically and continuously extracting an amount of the one or more chemical species from the reactor, one or more detectors for measuring property changes of the one or more extracted chemical species and generating a continuous stream of data related to the one or more property changes to the one or more chemical species during a time interval, and a process controller configured to fit the continuous stream of data to a mathematical function to predict one or more properties of the one or more chemical species at a future time point and make one or more process decisions based on the prediction of one or more properties at the future time point.

A method of monitoring a solid component of a reactor feed stream in a polymer production system, comprising (a) measuring a turbidity of the reactor feed stream, wherein the reactor feed stream comprises a solid component of a polymerization catalyst system, and (b) translating the turbidity of the reactor feed stream into a concentration of the solid component in the reactor feed stream. A method of monitoring a solid component of a reactor feed stream in a polymer production system, comprising (a) measuring a turbidity of a precontactor feed stream, wherein the precontactor feed stream comprises a solid component of a polymerization catalyst system, and (b) translating the turbidity of the precontactor feed stream into a concentration of the solid component in a precontactor effluent stream, wherein the precontactor effluent stream comprises the reactor feed stream.

A test system comprising a reactor having a fluid circuit and a test zone for an item under test. A plurality of control zones are included in the fluid circuit for controlling parameters of the fluid in accordance with control information. A control system receives input data specifying test values for the fluid parameters, predicts the behaviour of the fluid using the input data and a mathematical model of the reactor, calculates control information based on the predicted fluid behaviour, and communicates the control information to the control zones. The system can simulate transient test conditions by selective use of fluid evacuation and dilution, and by use of temperature and flow bypass circuits.