Abstract: Processes for reducing shutdown time of a sub-system/ reactor component in an LDPE process. The process includes closing one or more pairs of upstream lock-out valves, each pair of upstream lock-out valves being located in an inlet stream upstream of the reactor component and configured to cease fluid flow into the reactor component through said inlet stream when said pair of upstream lock-out valves is closed; closing one or more pairs of downstream lock-out valves, each pair of downstream lock-out valves being located in an outlet stream downstream of the reactor component and configured to cease fluid flow out of the reactor component through said outlet stream when said pair of downstream lock-out valves is closed; depressurizing the reactor component; introducing purge gas comprising N2 into the reactor component at and withdrawing the purge gas from the reactor component.

Abstract: Improved heat exchanger systems and processes for cooling recycled off-gas in high pressure low-density polyethylene production. A system for exchanging heat between a first material and a second material can include a shell for containing the first material therein, a plurality of tubes disposed within the shell for containing the second material therein, a tube sheet disposed at an end of the shell for restricting flow of the second material to the shell, and at least one collector conduit disposed exterior to the shell for receiving at least one end of the plurality of tubes, wherein at least one of the plurality of tubes extend through the tube sheet to the collector conduit. A cleaning tool can be disposed within the collector conduit for cleaning the tubes. A process for cooling a gas stream can include introducing the gas stream to the heat exchanger system provided herein.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Processes for producing high pressure polyethylene and processes for increasing the crosslinkability of high pressure polyethylene are disclosed. The processes comprise controlling particular reaction parameters that have been found to promote crosslinkability in the resulting high pressure polyethylene. High pressure polyethylenes having improved crosslinkability are also disclosed.

Abstract: Processes for producing high pressure polyethylene and processes for increasing the crosslinkability of high pressure polyethylene are disclosed. The processes comprise controlling particular reaction parameters that have been found to promote crosslinkability in the resulting high pressure polyethylene. High pressure polyethylenes having improved crosslinkability are also disclosed.