Process and system for preventing pressure tap fouling in tandem polymerization reactors

A process for producing a bimodal ethylene polymer blend comprising the steps of:

• contacting in a first gas phase, fluidized bed reaction zone under polymerization conditions a gaseous monomeric composition comprising a major portion of ethylene and, optionally, hydrogen to provide a molar ratio of hydrogen to ethylene of less than about 0.3, with a Ziegler-Natta catalyst comprising a transition metal compound as a primary catalyst component and an organometallic compound or metal hydride as reducing cocatalyst to produce a first zone product which is a high molecular weight (HMW) polymer associated with catalyst particles and has a flow index (FI) of about 0.1 to 1.0;
• transferring the first zone product to a second gas phase, fluidized bed reaction zone into which is also fed hydrogen and a gaseous monomeric composition comprising a major proportion of ethylene, but no additional transition metal component of said catalyst to produce a polymer deposited on and within the voids of the HMW polymer/catalyst particles
• wherein a molar ratio of hydrogen to ethylene in the
• second gas phase fluidized bed reaction zone ranges
• from about 0.9 to 5.0;
• and
• adding a relatively small amount of water directly to a plurality of pressure taps of the first reaction zone to eliminate fouling of said pressure taps, wherein the amount of added water is insufficient to reduce or eliminate the positive static in the first reaction zone wherein the relatively small amount of water is from about 0.1 to about 0.6 ppmv based on total ethylene feed.