Feeding polymerization additives to polymerization processes

#Disclosed herein are systems and processes for feeding polymerization additives to polymerization processes, such as a gas-phase olefin polymerization process. Disclosed herein are processes for viscosifying liquid slurry polymerization additives to facilitate more efficient feed of the polymerization additives to polymerization processes, and polymerization processes using the viscosified liquid slurry polymerization additive.

#Sheeting and chunking has been a problem in commercial polyolefin production reactors for many years. In gas phase reactors, the problem is generally characterized by the formation of solid masses of polymer on the walls or dome of the reactor. These solid masses of polymer (e.g., the sheets) eventually become dislodged and fall into the reaction section, where they may interfere with fluidization, block the product discharge port, plug the distributor plate, and force a reactor shut-down for cleaning, any one of which can be termed a “discontinuity event,” which in general is a disruption in the continuous operation of a polymerization reactor. The terms “sheeting, chunking and/or fouling,” while used synonymously herein, may describe different manifestations of similar problems, in each case which can lead to a reactor discontinuity event.

#There are at least two distinct forms of sheeting that occur in gas phase reactors. The two forms (or types) of sheeting are described as wall sheets or dome sheets, depending on where they are formed in the reactor. Wall sheets are formed on the walls (generally vertical sections) of the reaction section. Dome sheets are formed much higher in the reactor, on the conical section of the dome, or on the hemi-spherical head on the top of the reactor.

#Disclosed herein is a process for preparing a viscosified liquid slurry polymerization additive and a process for the polymerization of olefins using at least one viscosified liquid slurry polymerization additive. It has been found that the settling rate of polymerization additives in liquid slurry polymerization additives may be impacted by the amount of shear that the liquid slurry polymerization additives encounter during upstream processing, i.e., before placement in a feed vessel for supplying to a polymerization reactor. By controlling the extent of shearing of the liquid slurry polymerization additives during upstream processing, the settling rate of the polymerization additives out of the liquid may be decreased or settling may be eliminated. A decreased settling rate or the elimination of settling may, for example, minimize or eliminate the need for an agitated vessel or mixing skid and reduce the costs and improve the efficiency of the transportation and use of liquid slurry polymerization additives.

#Polymerization Additive

#As used herein, a polymerization additive includes a substance characterized by an ability to prevent or reduce fouling or sheeting, or impact the static levels in a polymerization reactor system, when the polymerization additive is introduced to the reactor system in an effective amount. The polymerization additive promotes a continuous reaction process by preventing or mitigating discontinuity events such as sheeting or chunking or impacting static levels in the reactor in a way that prevents or mitigates these events. Various polymerization additives are described in, for example, U.S. 2011/0184124, U.S. 2011/0077370, U.S. 2010/0289482, U.S. 2011/0256632, U.S. 2008/0319583, and U.S. 2007/0244271, among others.