Slurry tanks, mixed

Topics that acquire special importance on the industrial scale are the quality of mixing in tanks and the residence time distribution in vessels where plug flow may be the goal. The information about agitation in tanks described for gas/liquid and slurry reactions is largely apphcable here. The relation between heat transfer and agitation also is discussed elsewhere in this Handbook. Residence time distribution is covered at length under Reactor Efficiency. A special case is that of laminar and related flow distributions characteristic of non-Newtonian fluids, which often occiu s in polymerization reactors. 

Every year millions of cubic meters of ready-mixed concrete are returned for disposal in dump sites. There are now increasing environmental concerns and restrictions regulating the disposal of returned plastic concrete. In the last decade, environmental protection agencies in Europe and North America have classified both returned plastic concrete and truck wash water as hazardous waste. Consequently, the conventional methods of disposal in slurry tanks and landfill sites have become redundant, and disposal of plastic concrete is now a major problem for the ready-mixed concrete industry [102]. 

Capital equipment rentals include equipment trailer, slurry mixer and pump, mixing pumps, tanks, hoses, fracturing lance, wellhead assembly, notching pump and accessories, uplift survey equipment, scale, and miscellaneous tools and hardware. 

The slurry tank, when well mixed, can be considered a continuous-stirred tank reactor for both the gas phase and the liquid phase. When the solid is retained in the reaction vessel, it behaves in a batch mode however, catalyst can be removed and regenerated easily in a slurry tank, so activity can be maintained. 

Gum Slurry The gum slurry tank is usually adjacent to the main mix tank and contains about 0.1 of the volume of the main mix tank. Gums are dispersed in a portion of the formula vegetable oil with a lightening mixer or similar type agitator. 

Hie RDX cake washed from the filter cloth is continuously evacuated into a slurrying tank where it is mixed with water and transferred by means of water injector to another building. Reactors are cooled with Freon 12. 

Despite the experience with batch reactors it may be worthwhile to operate continuous reactors also for fine chemicals. Continuously operated reactors only demand for one start-up and one shut-down during the production series for one product. This increases the operating time efficiency and prevents the deactivation of dry catalysts this implies that the reactor volume can be much smaller than for batch reactors. As to the reactor type for three phase systems an agitated slurry tank reactor [5,6] is not advisable, because of the good mixing characteristics. Specially for consecutive reaction systems the yields to desired products and selectivities will be considerably lower than in plug flow type reactor. The cocurrent down flow trickle flow reactor... 

The slurry falls from the scrubber to a mixing/hold tank, where ... 

The Costeam process (Appell et al., 1969 Vera and Bell, 1978 Nowacki, 1980) is designed to convert low-rank coals (such as lignite and subbituminous coals) to a low-sulfur product by the noncatalytic reaction of a coal/oil slurry with either carbon monoxide or synthetic gas (carbon monoxide/hydrogen). In the process (Figure 19.9), pulverized coal is introduced into a slurrying tank where it is mixed with process solvent (a process-derived liquid) after which the slurry is fed (with the gas choice) into... 

A commercial design based on semicontinuous operation was developed for manufacture of silicate powders (27). A slurry, prepared containing the feed materials and water, is fed to the reactor tank and heated by circulating a heat-exchange fluid in channels located on the outside vessel wall. A six-bladed stirrer is operated at about 100 rpm in order to keep reagents well mixed. Once the slurry reaches the operating temperature, the vessel heat is maintained until reaction is complete. For most fine-particle products, this time is less than 1 hr. 

---