Technology
Dense Loading
Dense loading is preferable to sock loading in several instances. The advantages of dense loading include increased density, capacity, run length, reactor integrity, and product quality. Sock loading, as a result of its tendency to create void spaces, may not maximize a reactor's capacity. Sock loading, on the other hand, because it is more tolerant to particulate matter in the feed and distributes catalyst in a less dense state, may be preferable to dense loading in some situations. Sock loading often comes at a lower cost. For those refiners who do not require or cannot handle the increased capacities that dense loading allows, it is a viable option.
Maximum performance for catalytic processes will require that those involved with the catalyst handling are well trained and aware of the desired results expected by the catalyst manufacturer and the refiner. It is most important that discussions are conducted with the facility operations, engineering, and maintenance departments, and with a representative of the catalyst manufacturer.
Since 1970, refiners, catalyst manufacturers, and catalyst-loading contractors have developed dense-loading devices that dramatically reduce void spaces and bridging. Dense loading can increase catalyst bed densities by as much as 17%.Moreover, unlike sock loading, dense loading does not require personnel inside the reactor to distribute the catalyst evenly from the sock. Workers inside the reactor require breathing air and weight distribution shoes to prevent crushing of the catalyst underneath their weight. Dense loading is accomplished by introducing the catalyst cylinders into the reactor in a manner that allows each cylinder to fall freely to the catalyst surface. Individual cylinders separately assume a horizontal rest position before being impinged by other cylinders. Under this regime, cylinders tend to pack horizontally, minimizing the possibility of bridging or creating void spacess.
