The present invention relates to a process for the continuous preparation of a polyolefm in a reactor from one or more -olefm 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 -olefm monomers to the reactorwith-drawing the polyolefm 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.

Provided herein are processes for carrying out a chemical reaction of a substrate in a diluted reaction mixture. The processes include conducting the reaction mixture having reaction product and solvent to a filtration membrane which is permeable to the solvent but impermeable to the reaction product. Solvent which permeates the filtration membrane for dilution of the substrate feed is recycled.

A process to safely shutdown a Fischer Tropsch reactor is provided. The process can be used for a routine shutdown but is specifically designed for emergency shutdowns such as during a thermal excursion or power failure or equipment failure.

The present invention relates to a process for the continuous preparation of a polyolefin from one or more -olefin monomers in a reactor system, the process for the continuous preparation of polyolefin comprising the steps of: feeding a polymerization catalyst to a fluidized bed through an inlet for a polymerization catalyst; feeding the one or more monomers to the reactor, polymerizing the one or more monomers in the fluidized bed to prepare the polyolefin; withdrawing polyolefin formed from the reactor through an outlet for polyolefin; withdrawing fluids from the reactor through an outlet for fluids and transporting the fluids through first connection means, an heat exchanger to cool the fluids to produce a cooled recycle stream, and through second connection means back into the reactor via an inlet for the recycle stream; wherein a thermal run away reducing agent (TRRA) is added to the reactor in a discontinuous way.

This disclosure relates to systems and processes for cooling polymer product mixtures manufactured at high pressure. The processes of the invention involve cooling and then subsequently reducing the pressure of the product mixture from the reactor. In the systems of the invention, a product cooler is located downstream of the high pressure reactor and upstream of a high pressure let down valve.

Systems and methods are disclosed for detecting temperature excursion in a chemical plant or petrochemical plant or refinery. Aspects of the disclosure provide an enhanced control system for a reactor, such as in hydroprocessing. The enhanced control system may provide early warnings of impending undesirable events, directly or indirectly manipulate certain process variables to reduce undesirable outcomes, and/or directly or indirectly manipulate of certain process variables so as to place a reactor unit in a safe park state. This may avoid a high temperature trip, depressuration, associated operating risks, allow for faster recovery from temperature excursions, and/or avoid unplanned emergency shutdowns of the reactor, chemical process, plant, or refinery.

In a method for monitoring a chemical reaction in a continuously operated reactor with at least one tube section, wherein the reactor has an intake, an outlet and a main flow direction running between the intake and the outlet, substances are supplied to the reactor via the intake and a product mixture made up of these substances and the solidified products thereof is created in the reactor. The reaction is monitored and measures are taken to prevent an uncontrolled reaction process, wherein these measures comprise at least the following steps: interruption of the intake and outlet, active pressure relief of the reactor and flushing of the reactor with an inert substance. This facilitates a safe and efficient interruption of the chemical reaction.

Controlling the shutdown of a polyethylene reactor system that includes a secondary compressor, a reactor, a high pressure let down valve (HPLDV), a high-pressure separator, and a high-pressure recycle gas system is provided. After a partial or complete shutdown of secondary compressor, HPLDV opens to a pre-set open position until the reactor pressure reduces to either a pre-set reduced pressure limit or a until the slope of the reactor gas density to reactor pressure exceeds 0.15. The HPLDV controls the pressure to a pressure set point.

Systems and processes for rapidly depressurizing a reactor system are disclosed. The systems and processes are particularly useful in the high pressure polymerization of ethylene.

The system according to the present invention disclosure includes a model generation module to generate a digital twin model including a replication model of a physical component of the ammonia cracking plant; an input module to input dynamic energy requirement and output information of an ammonia cracking apparatus included in the ammonia cracking plant into the digital twin model; an emergency condition imposition module to impose, for a preset emergency scenario, an emergency condition on the replication model of the physical component; a data collection and comparison module to collect data from the digital twin model under the imposed emergency condition, and compare first data when the emergency condition is imposed and second data when the emergency condition is not imposed; and a scenario generation module to generate a control scenario for the preset emergency scenario based on comparison results of the first data and the second data.