Regeneration of Fixed Catalyst Bed with Special Reference to Petroleum Refining
Fixed catalyst beds are normally composed of a carrier and a catalyst pellet e.g. alundum balls and platinum cylinders. Examples of this type are reforming units such as Platformers, Ultraformers, etc. Hydrodesulphurization reactors may employ cobalt molybdenum on alumina or bauxite carriers used for removal of sulphur by partial hydrogenation of sulphur-containing molecules. Catalyst disintegration, scale formation and carrier breakage cause increased reactor pressure drop and periodic regeneration is required.
METHOD AND RESULTS
Continuous processing techniques and high cost of shutdown in petroleum refining require quick turnabout. Most frequently the reactor gravity feeds a triple deck Kason Separator equipped with screens having openings of 0.375", 0.202" and 0.108". These screen sizes are most frequently selected but a wide variety are available to meet individual catalyst specification. Top screen (0.375") discharges whole alundum balls, center screen (0.202") broken balls and scale to waste, bottom screen (0.108") clean catalyst pellets, and the dust passing this screen is valuable catalyst collected for return to the maker for credit. Four deck units are also used where it is necessary to segregate carrier balls to size. Capacity will depend upon the carrier and catalyst used but, for example, most reformer beds are screened at the rate of 7 tons per hour.
Similar fixed bed catalyst cleanup jobs exist in the chemical industry and many installations have been made.
1. Reactor maintenance is only carried out when necessary and the time interval may be a couple of years. Screening is done on site and portability is an important factor. The Kason designed for this service only weighs 850 pounds and can easily be held in maintenance stores on a portable dolly ready for immediate service when required. Complete absence of transmitted vibration eliminates the necessity of any supporting substructure and it is only necessary to move the completely unitized assembly into place.
2. The Kason is equipped with a metal cover and by attaching flexible connections to the discharge spouts the entire screening operation can be made dust-tight. This is particularly important when platinum catalyst is handled, and since losses are virtually eliminated, some refinery operators have reported that the equipment has been amortized on first use when compared to other laborious methods of classification.
3. The Kason's high capacity at maximum efficiency insures shortest possible' down time which is normally very important on this application.
- Triple or four deck Kasons, as required.
- Epoxy coated carbon steel construction with stainless steel screen cloths.
- Metal cover with 8" inlet to accept feed directly from reactor.
- Explosion-proof motor and wiring to meet requirements of Class 1 Group D and Class 2 Groups F and G applications.
Kason Application Data No: 11