The best way for chemical processes to deal with solids is to turn them into liquids. This is not always possible, so solids materials handling must consider important factors for success. Solids will hang up, plug and rat hole. Solids will segregate. Solids have the unique property that they can de-mix if they are over mixed. Solid particles will break down and they will also agglomerate. Attrition of engineered particles contributes to increased pressure drop in systems where they are used as catalysts and sorbents. Product delivery to consumers can be affected by over dusting due to the breakdown of the particle structure. When suspending solids in slurries for liquid phase transport, solid particles will settle in and plug slurry lines. Dust will have to be controlled. The small particle emissions from systems have been identified with many repository aliments and have become a focus area for control.
Pumping slurries and keeping slurries agitated in tanks are two of the most difficult transport operations in chemical engineering. Provisions must be made in the design to keep all slurries moving so as to not have them plug lines or plug the bottoms of agitated tanks.
Many times engineers designing system do not take into consideration all the transient and failure modes that may effect the slurry handling systems design. For example, slurry tanks should have provisions to allow the re-start of the agitator in a tank bottom where the solids have settled into a cake in around the impeller. System design methods could include high torque agitator drives, shafts and couplings, back up electrical power, or decoupling and mechanical torque multipliers to assist in the restart. Methods to get the slurry moving in the bottom of a settled tank could include installing access for air lances to be placed into the caked up tank to begin to move the material using air then allowing the agitator start up to finish the re-suspension of material.
To insure that the production of the needed sales specification material is achieved 100% of the time, a Statistical Process Control methodology will be used to determine the needed production targets.