Dryer system

Fig. 13. Spray-dryer system designed for production of agglomerated food powders with instant properties (82) A, Hquid-feed system B, spray-dryer chamber C, drying air heater D, cyclones for fines recovery E, vibrofluidizer as afterdryer F, vibrofluidizer as aftercooler and G, fines return to drying...

System includes finned air heaters, transition piece, dryer, drive, product collector, duct, and fan. Prices are for carhon steel construction and include entire dryer system (Novemher, 1994). 

Figure 16-49 [Engineering Data Book, 10th ed., Gas Processors Slippers Association, Tulsa, 1988, Sec. 20, p. 22] depicts the flow scheme for a typical two-bed TSA dryer system showing the auxiliary equipment associated with regeneration. Some of the diy product gas is externally heated and used couutercurreutly to heat and desorb water from the adsorber not currently drying feed. The wet, spent regeneration gas is cooled the water is condensed out and the gas is recycled to feed for recovery.

Municipal and industrial incinerators Pathological incinerators Industrial waste Odors, hydrocarbons, HCl, dioxins, furans Particulates, smoke, and combustion contaminants Proper charging, acid gas scrubber, baghouse Modified fuel feed, auxiliary fuel and dryer systems, cyclones, scrubbers... 

Figure 9.7 Crystallizer-centrifuge-dryer system optimization Rossiter, 1986)...

Becker, H. A. P. L. Douglas and S. Ilias. Development of Optimization Strategies for Industrial Grain Dryer Systems. Can J Chem Engy 62 738-745 (1984). 

Airborne hazards, such as tritium (present in radiated water vapour), can be reduced by running the station s dryer system. The dryer system catches the radiated vapour and dries it out of the air. 

Atmospheric air at the rate of 6.1 million SCFD is compressed to 160 psig in a two-stage compressor JJ-1 that is provided with an intercooler and a knockout drum. Then it proceeds to a packed tower T-l where it is scrubbed with recirculating caustic soda solution. Overhead from T-l is cooled to 14°F in a refrigerated exchanger. After removal of the condensate, this stream proceeds to a dryer system that consists principally of two vessels F-l and F-2 packed with solid desiccant. 

Ethylene, hydrogen, co-monomer and a super-high activity catalyst are fed into the reactors (1). Polymerization reaction occurs under a slurry state. The automatic polymer property control system plays a very effective role in product-quality control. Slurry from the reactors is pumped to the separation system (2). The wetcake is dried into powder in the dryer system (3). As much as 90% of the solvent is separated from the slurry and is directly recycled to the reactors without any treatment. The dry powder is pelletized in the pelletizing system (4) along with required stabilizers. 

In the process, homopolymer and random copolymer polymerization occurs in the loop-type reactor (or vessel-type reactor) (1). For impact copolymer production, copolymerization is performed in a gas-phase reactor (2) after homopolymerization. The polymer is discharged from a gas-phase reactor and transferred to the separator (3). Unreacted gas accompanying the polymer is removed by the separator and recycled to the reactor system. The polymer powder is then transferred to the dryer system (4) where remaining propylene is removed and recovered. The dry powder is pelletized by the pelletizing system (5) along with required stabilizers. 

FIGURE 16.8 Schematic diagram of a hot IPA dryer system (from Ref. 31). 

The purge gas is water scrubbed at 135 -145 bar, reducing the ammonia concentration to less than 200 ppm. The scrubbed purge gas is heated to 35 °C and sent directly to the Prism separators. Trace concentrations of ammonia and water vapor in the gas stream pose no problem to the membrane. Therefore, a dryer system is not required. 

As shown in the flowsheet (Figure 3), the washed product from the second-stage centrifuge is repulped in an appropriate vehicle preparatory to the final purification stage. This vehicle might be methanol, if a molding grade type of polymer is desired as the end product, water if over-all plant economics dictate a final thermal dryer system suitable for the evaporation of water rather than flammable solvent, or aqueous hydrochloric acid, if the end use of the polymer is for fiber and film production. 

Two of the dryer system options incorporate a rotary cascade dryer (Figure 2). The performance is modelled using a straightforward mass-energy balance, where biomass inlet and target outlet moisture are input values, along with biomass flow rate. For a given gas inlet composition, the model then calculates the necessary gas inlet temperature for a specified flow rate. Gas outlet temperature has to be specified. 

Rossiter, A. P., and Douglas, J. M., Design and optimization of solids processes. Part 2. Optimization of crystallizer, centrifuge and dryer systems. Chem. Eng. Res. Des. 64, 184 (1986b). 

Decide on the envelope for the mass and energy balance. Some dryer systems have hot-air recycle loops and/or combustion or steam heating systems. It is not always necessary to include these to understand the dryer operation. 

Start-up and shutdown Start-up and shutdown situations must be carefully considered when designing a dryer system. These situations can create higher than normal dust and solvent concentrations. This coupled with elevated temperatures can create a hazard well beyond normal continuous operation. 

Common Control Schemes Two relatively simple, but common control schemes in many dryer systems (Fig. 12-110) are as follows ... 

Interlocks Interlocks are another important feature of a well-designed control and instrumentation system. Interlocks are intended to prevent damage to the dryer system or to personnel, especially during the critical periods of start-up and shutdown. The following are a few key interlocks to consider in a typical dryer system. 

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