High-gravity systems

Energy of Centrifugal Fields-High-Gravity Systems I 301... 

Figure 8.17 (a) A schematic diagram of a high gravity system for producing BaC03... 

The apphcations of PI in the chemical process sector encompass bulk and fine chemicals and a range of unit operations. Dominant are high gravity systems (HiGee and spinning disc reactors) and micro or HEX-reactors. In many cases the examples are one-offs , but the replication is bound to increase in future years as environmental and production demands grow. 

Dry condensing equipment can be equipped with either with horizontal or vertical freeze condensers (Figures 17 and 18). Advantages of horizontal dry condensing systems are the relatively simple and compact construction of the freeze condensers. On the other hand, the mass of the refrigerant in the gravity system is typically high. 

High pressure system Gravity flow system... 

Highly viscous systems are difficult to de-gas under gravity, so degassing is best done in a thin-film device. 

Fig. 20.33 A typical water deaeration plant involving pasteurization. Equipment for producing chilled, carbonated, deaerated, pasteurized water for beer dilution after high gravity brewing. Alternative systems lead water to the spray chamber either at 15°C or at temperatures above 100°C. In these, the holding tube is omitted. The system with the highest temperature of water relies on flash action within the spray vessel which eliminates the need for vacuum. (Based on diagrams of APV Co., Crawley.)...

Answer by author Tests have not been performed with liquid transfer systems operating under unusual acceleration loads. Of course, infrared cooling applications are rarely expected to require operation for prolonged periods under high-gravity loads and residual capacity can be provided in the system to assure continued cooling during short periods of interrupted liquid flow."... 

A concurrent downward flow circulating fluidized bed, or a downer, is a new alternative flow arrangement for a high-velocity system. A downer reactor system has similar system configurations to a riser reactor system except that both the gas and the solid particles flow downward. Concurrent downward flow of particles and gas reduces the residence time of solid particles because the downward flow is in the same direction as gravity. More uniform radial gas and solids flow than those in a riser can be achieved. The downer leads to more uniform contact time between the gas and solids. With these advantages, downer reactors have been proposed for processes such as fluid catalytic cracking, which requires short contact time and uniform gas and solids residence time distributions. 

Figure 5. Images of foams produced in Low gravity (left) and High gravity (right). The systems consisted of HDD A, HEMA, Aliquat Persulfate, Aliquat 336, and water. The 1.8 g and pg images were taken from the same sample at different times during the flights.

Figure 6. Bubble behavior in liquid/liquid system under (left) high gravity and (right) low gravity.

Low Pressure Preferences—Gravity or low pressure systems should be used over high pressure systems (e.g., fuel to prime movers, day tank supplies, etc.). 

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