Slurries pneumatic conveying

Pipelines to transport soHds are called freight pipelines, of which three different types exist pneumatic pipelines, the use of which is known as pneumotransport or pneumatic conveying slurry pipelines, which may also be called hydrotransport or hydrauHc conveying and capsule pipelines. When air or inert gas is used to move the soHds in the pipeline, the system is called a pneumatic pipeline and often involves a wheeled vehicle inside the pipeline, propelled by air moving through the pipe (25). Slurry pipelines involve the transport of soHd particles suspended in water or another inert Hquid. HydrauHc capsule pipelines transport soHd material within cylindrical containers, using water flow through the pipeline for propulsion. 

Suspended Particle Techniques. In these methods of size enlargement, granular soHds are produced direcdy from a Hquid or semiliquid phase by dispersion in a gas to allow solidification through heat and/or mass transfer. The feed Hquid, which may be a solution, gel, paste, emulsion, slurry, or melt, must be pumpable and dispersible. Equipment used includes spray dryers, prilling towers, spouted and fluidized beds, and pneumatic conveying dryers, all of which are amenable to continuous, automated, large-scale operation. Because attrition and fines carryover are common problems with this technique, provision must be made for recovery and recycling. 

Handling and processing operations (e.g., slurry flow, fluidization, pneumatic conveying)... 

Pneumatic conveying. Direct type, continuous operation See comments under Slurries Can be used only if product is recirculated to make feed suitable for handling Usually requires recirculation of dry product to make suitable feed. Well suited to high capacities. Disintegration usually required Suitable for materials that are easily suspended in a gas stream and lose moisture readily. Well suited to high capacities Suitable for materials that are easily suspended in a gas streatm. Well suited to high capacities. Product may suffer physical degradation Not applicable Not applicable Not applicable... 

Particle-fluid flow has been in existence in industrial processes since the nineteenth century. Applications include pneumatic conveying, which deals with pipe flow of solid material transported by a gas, slurry transport and processing of solids in a fluid. The necessity of predicting blower or pumping power for a given amount of material to be conveyed led to measurements of pressure drops and attempts in the correlation of physical parameters. That anomaly exists in the correlation in terms of simple parameter is one of the motivations for the exploration into the details of distributions in density and velocity and the present state of development of instrumentation. 

A slurry mixture is essentially a mixture of a carrying fluid and solid particles held in suspension. The most commonly used fluid is water, but over the years, attempts have been made to use crude oils with milled coal, and even air in pneumatic conveying. 

Suitable feeds to a spray dryer are solutions or pumpable pastes and slurries. Such a material is atomized in a nozzle or spray wheel, contacted with heated air or flue gas and conveyed out of the equipment with a pneumatic or mechanical type of conveyor. Collection of fines with a cyclone separator or filter is a major aspect of spray dryer operation. Typical equipment arrangements and flow patterns are shown in Figure 9.14. 

Principles of ECT and the latest developments in the technology are highlighted with emphasis on the volume ECT (ECVT) for 3D imaging. The significance of ECT technique in process engineering is presented in the framework of industrial application. Fluidized beds, pneumatic solids conveying, and slurry bubble columns are examples of ECT s capability to provide quantitative and qualitative understanding of the internal process dynamics. 

From this point, the process becomes continuous. The bead/water slurry is centrifuged (3) where most of the "mother liquor" is removed. The beads are conveyed to a pneumatic dryer (4) where the remaining moisture is removed. 

Some of the more obvious areas definitely requiring test work are filtration, sedimentation, spray, or fluidized bed or any other kind of solids drying, extrusion pelleting, pneumatic and slurry conveying, adsorption, and others. Even in such thoroughly researched areas as vapor-liquid and liquid-liquid separations, rates, equilibria, and efficiencies may need to be tested, particularly of complex mixtures. A great deal can be found out, for instance, by a batch distillation of a complex mixture. 

Slurries, mining slurries, liquids with large amounts of suspended soUds, systems that convey sohds pneumatically, food service... 

---