Methods and devices for polymerization

A method for the polymerization of an alpha-olefins in a fluidized bed reactor in the presence of a catalyst that may cause sheeting during the polymerization, by maintaining a static electric charge in the reactor at the site of possible sheet formation below static voltage levels which would otherwise cause sheet formation by introducing a chromium-containing compound into the fluidized bed reactor in such manner as to contact the surfaces of the reactor, the chromium in the chromium-containing compound being present in a valence state from 2 to 3, oxidizing the chromium, and forming a high molecular weight polymer on a bed section wall of the fluidized bed reactor,

• wherein the oxidizing step is completed in less than 2 hours,
• wherein the high molecular weight polymer coating is formed by reacting the oxidized chromium with ethylene, and
• wherein the chromium-containing compound is introduced into the fluidized bed reactor through a plurality of injection devices located inside the fluidized bed reactor and in proximity to a lower section of a bed section wall of the fluidized bed reactor.

A device for treating a fluidized bed reactor comprising a plurality of injection devices located inside a fluidized bed reactor, wherein the injection devices are placed in proximity to a lower section of a bed section wall of the fluidized bed reactor, and the injection devices are oriented to contact a treatment fluid with the bed section wall,

• wherein the plurality of injection devices are oriented at an angle of 40 to 50 degrees up from a horizontal plane, and the plurality of injection devices are oriented in the horizontal plane at an angle of 40 to 50 degrees inward from the tangent to the bed section wall.