Abstract: A process for producing an olefin polymer employs a gas phase polymerization reactor in fluid communication with a vent column and a product discharge system. The discharge system can include first and second pairs of lock hoppers, where each pair includes an upstream lock hopper connected by a valve to the reactor and a downstream lock hopper connected by a valve to the upstream lock hopper and by a further valve to a product recovery system, and where a first cross-tie can be provided between the upstream lock hoppers of the first and second pairs of lock hoppers and a second cross-tie can be provided between the downstream lock hoppers of the first and second pairs of lock hoppers. Upon reaching the vent column's maximum removal capacity, additional gas can be removed from the reactor by reducing the frequency of opening the second cross-tie between the downstream lock hoppers.

Abstract: Methods and systems for performing transient processes may include: providing a path and path thresholds for an operational condition as a function of progress of a transient process based on historical data of previously performed transient processes; performing the transient process in a chemical reactor using operational parameters; measuring the operational condition of the transient process as a function of the progress of the transient process; and adjusting one or more of the operational parameters during the progress of the transient process to maintain the operational condition within the path thresholds.

Abstract: Methods for producing a polymer include contacting at least one monomer under polymerization conditions with a fluidized bed of a polymerization catalyst on a particulate support; measuring a plurality of pressures of the fluidized bed at a plurality of locations corresponding to increasing heights from a bottom of the fluidized bed; calculating a plurality of pressure drops between the plurality of locations based on the measured pressures; performing a regression analysis on the calculated plurality of pressure drops; correlating the plurality of pressure drops to corresponding heights from the bottom of the fluidized bed based on the regression analysis; determining a height of the fluidized bed based on the correlating; and controlling polymerization conditions based on the determined height of the fluidized bed. The method can also be used to detect malfunctioning pressure transducers based on deviation between measured and expected values.

Abstract: A process for producing an olefin polymer employs a gas phase polymerization reactor having a product discharge system comprising first and second pairs of lock hoppers, wherein each pair comprises an upstream lock hopper connected by valve means to the reactor and a downstream lock hopper connected by valve means to the upstream lock hopper and by further valve means to a product recovery system, and wherein a first cross-tie is provided between the upstream lock hoppers of the first and second pairs of lock hoppers and a second cross-tie is provided between the downstream lock hoppers of the first and second pairs of lock hoppers. Operation of the second cross-tie during product removal cycles is controlled in accordance with reactor pressure.

Abstract: Methods and systems for performing transient processes may include: providing a path and path thresholds for an operational condition as a function of progress of a transient process based on historical data of previously performed transient processes; performing the transient process in a chemical reactor using operational parameters; measuring the operational condition of the transient process as a function of the progress of the transient process; and adjusting one or more of the operational parameters during the progress of the transient process to maintain the operational condition within the path thresholds.

Abstract: A process for producing an olefin polymer employs a gas phase polymerization reactor having a product discharge system comprising first and second pairs of lock hoppers, wherein each pair comprises an upstream lock hopper connected by valve means to the reactor and a downstream lock hopper connected by valve means to the upstream lock hopper and by further valve means to a product recovery system, and wherein a first cross-tie is provided between the upstream lock hoppers of the first and second pairs of lock hoppers and a second cross-tie is provided between the downstream lock hoppers of the first and second pairs of lock hoppers. Operation of the second cross-tie during product removal cycles is controlled in accordance with reactor pressure.