Licensed DENSICAT* Technology
Catalyst Services is a licensed contractor in DENSICAT loading of catalyst into fixed bed reactors. This technology provides a very effective way of increasing the bed density and volume of all catalyst and desiccant material in a wide variety of reactors. Our licensed technicians and equipment travel all over the world to meet the required needs of our customers.
Conventional loading methods using a sock often result in loosely packed beds with poor catalyst orientation. Dense bed loading is used to overcome these deficiencies.
Dense bed loading applies the principles of individual particle movement in free fall in a static air column. The major advantages that are desired are listed below.
Increase Bulk Density
Catalyst loading by dense bed loading results in a more dense bed than is obtained by conventional loading. More catalyst can be loaded into a given reactor and throughput can be increased.
Improve Catalyst Utilization
In two-phase (liquid and gas) systems, the liquid-catalyst contacting is improved by dense bed loading and increased efficiency is obtained in very high conversion reactions. Uniform void spaces and tendency toward horizontal particle orientation enhance efficiency.
Reduce Bed Settling
Since a near maximum density is achieved with dense bed loading at the start of the cycle, bed settling and shifting is greatly reduced. This helps eliminate damage to reactor internals, common to conventional techniques. In addition, reduced bed settling in radial flow reactors helps eliminate the severe by-passing that can occur if the bed level drops below the scallops or the center pipe.
PRINCIPLES
The DENSICAT dense bed loading method is a controlled rate loading procedure that achieves uniform high density catalyst beds using a loading device designed to distribute the catalyst over the entire surface. The increase in bed density for catalyst loaded by the DENSICAT loading method is possible because of the following principles:
- Extruded particles, when permitted to fall independently, come to rest primarily in horizontal orientation and pack closely.
- A discrete particle falling in air reaches a maximum velocity after 10-12 feet of fall. This velocity is not great enough to cause significant breakage upon impact in most cases.
Improved operations in reactors loaded by the DENSICAT loading method are the result of the following factors:
- Horizontally oriented particles tend to divert liquid or gas streamlets horizontally and cause streamlets to mix.
- Close packing reduces voids and increases initial pressure drop somewhat, but bed settling is avoided so that Delta P increase and mechanical damage due to bed settling does not occur.
The DENSICAT loading equipment is designed to control the loading rate and the radial distribution of catalyst during loading to accomplish the following:
- Obtain maximum density and horizontal particle orientation.
- Maintain level bed surface during loading.
The important physical properties associated with reactor catalyst loading are bulk density and attrition resistance. The bulk density is needed to determine the amount of catalyst to be loaded in each bed and the total reactor. The attrition resistance is needed to verify that particle breakage will be minimal.
The major items of equipment needed are the catalyst loading device, a hopper to be positioned at the top reactor entry, a transfer container used to convey the catalyst from ground level to the hopper, and a hoisting apparatus for the transfer container.
*DENSICAT is a registered mark of Compagnie De Raffinage Et De Distribution Total France.
