System for producing polyolefin and process for recovering polymerization product from gas phase reactor

Abstract

The invention relates to a system for producing polyolefin. The system comprises a gas phase reactor () for polymerizing an olefin to obtain polymerization product. The gas phase reactor () comprises a gas distribution plate () arranged inside the gas phase reactor (); a first outlet () for continuously withdrawing polymerization product from the gas phase reactor () as a first product stream, the first outlet () being arranged above the gas distribution plate (); and a second outlet () for continuously withdrawing polymerization product from the gas phase reactor () as a second product stream, the second outlet () being arranged above the gas distribution plate (). The system further comprises a first outlet tank () in fluid communication with the first outlet () via a first passage (), wherein the first passage () comprises a first valve means () for controlling the flow of the first product stream in the first passage () and wherein the first outlet tank () is arranged to receive the first product stream and to concentrate the first product stream; a product receiver tank () in fluid communication with the second outlet () via a second passage (), wherein the second passage () comprises a second valve means () for controlling the flow of the second product stream in the second passage (), and wherein the product receiver tank () is arranged to receive the second product stream; and a control means in communication with the first valve means () and the second valve means () and arranged to control the operation of the first valve means () and the second valve means () so that flow in only one of the first passage () and the second passage () is allowed at a time. The invention relates also to a process for recovering polymerization product from a gas phase reactor (). The gas phase reactor () is suitable for polymerizing an olefin to obtain polymerization product and comprises a gas distribution plate () arranged inside the gas phase reactor (); a first outlet () for continuously withdrawing polymerization product from the gas phase reactor (), the first outlet () being arranged above the gas distribution plate (); and a second outlet () for continuously withdrawing polymerization product from the gas phase reactor (), the second outlet () being arranged above the gas distribution plate (). The process comprises selectively withdrawing polymerization product from the gas phase reactor () via the first outlet () as a first product stream, feeding the first product stream to a first outlet tank (), and concentrating the first product stream in the first outlet tank (); or withdrawing polymerization product from the gas phase reactor () via the second outlet () as a second product stream, and feeding the second product stream to a product receiver tank ().