CATALYST BED SUPPORT
Catalyst Support Media ("inert catalyst supports") are available in
both ball and pellet shapes. They are used in fixed bed catalytic units
to "support" the heterogeneous catalyst particles away from the unit
outlet, or the support grid perforations. In addition, Raschig Rings
are used in fixed bed catalytic units as an alternative to balls and
pellets.
Some down-flow units are also designed or operated with Catalyst Bed Supports on the top of catalyst bed to aid in distribution of the feed stock. Sometimes "trash baskets" filled with Catalyst Bed Supports are also used in the top of catalytic units to help collect tramp iron, localize cracked feed polymerization, etc., before these contaminants reach the catalyst bed itself.
Catalyst Bed Supports are generally available in three materials of construction: high alumina low alumina or stoneware, and mid-alumina or cement. In those catalytic reactions where potential low-catalytic-activity acid sites are not desirable, more expensive high alumina Catalyst Bed Supports are specified.
Stoneware Catalyst Bed Supports are used routinely in the following services:
Ammonia plants
Hydrotreaters
Bender treaters
Isomerization units
Chloride absorbers
(pretreaters and reactors)
Claus units
Molecular sieve units
Diesel hydrotreaters
Naphtha treaters
Fixed bed reformers
Reformer pretreaters
Fluidized pollution control
SCOT®
units
Hydrocrackers (1st stage)
VGO
pretreaters
Hydrogen plants
MATERIALS OF CONSTRUCTION
When manufactured properly, stoneware and porcelain shapes do not contain crystalline quartz, a known carcinogen regulated by governmental uthorities.
Stoneware is inherently less dusty than its cementitious alternative.