Drying batch system

Batch versus continuous Flowsheet input-output structure Crystallizer and recycle considerations Separation systems specification Product drying Energy systems... 

Further experiments were conducted in a large aeration tank, 15 litres batch system to study die dry weight cell density, COD, carbohydrate, dissolved oxygen and oxygen transfer modelling. Two different airflow rates, 5 and 10 litres/min, were applied. However,... 

Manifold drying has several advantages over batch tray drying. Because vessels are attached to the manifold separately, each vial or flask has a direct path to the collector. This eliminates some of the competition for molecular space created in a batch system and is most ideally realized in a cylindrical drying chamber where the distance between each product and the collector will be identical. In a tee manifold, the water molecules leaving the product in vessels farthest from the collector experience some traffic congestion as they travel past ports of other vessels. 

Solar water heating system for single stage preparation in a kier and pad-batch systems with a process cost savging is possible [28,29]. Solar heat may be utilised to the maximum extent for drying the fabric to reduce consumption of fuel. 

The ceramic industry has, for many years, examined the use of microwaves for drying purposes. Today, several uses are operating successfully. One such system, MCB Ceramics in Toronto, Canada, uses microwaves at two stages to replace a slow, hand-operated batch system with a continuous process. A 27 kW microwave oven is used to speed up the initial drying in the mold to 20 min from its previous 1 h, during which the microwaves are applied for only 2 min. The final drying used to take 24 h but now is done with microwaves in only 8 min, after which the piece is glazed and fired. The process is used to produce small bathroom accessories such as towel bar holders and soap dishes [23]. 

The product is dried under vacuum at low temperatures. Temperatures range between 35°C and 60°C. Vacuum-dried products are quite hygroscopic. Special care is needed during packing of the materials to protect against absorption of moisture. This method could be applied to batch as well as to continuous systems. In batch systems, product in trays is dried in a compartment maintained at pressures reduced below atmospheric pressure. 

Precipitation is an operation known for producing small crystals that are difficult to filter and dry. Batch precipitation is usually carried out in the form of a semibatch process, i.e., one or two reactants are continuously added to the reactor. The control of the particle size distribution in a precipitation process is very complicated because of the high level of supersaturation generated by the fast reaction. According to Mersmann [16], the important factors for sparingly soluble systems in isothermal precipitation are ... 

The synthesis of most molecular sieve zeolites is carried out in batch systems, in which a caustic aluminate solution and a caustic silicate solution are mixed together, and the temperature held at some level above ambient (60-180°C) at autogenous pressures for some period of time (hours-days). It is quite common for the original mixture to become somewhat viscous shortly after mixing, due to the formation of an amorphous phase, i. e., an amorphous alumino-sdicate gel suspended in the basic medium. The viscous amorphous gel phase normally becomes less viscous as the temperature is raised, but this is not universally true, as in the case of some NH40H-based systems which remain viscous throughout the synthesis. The amorphous gel can be filtered from the solution and dehydrated by conventional drying methods. 

The setup of a system for continuous vacuum drying is similar to the setup of batch systems. But in addition dosing devices and feed- and discharge locks are required for a continuous product flow into and out of the system (Figure 12.19). 

Three different detection modes can be utilized including fixed potential preferred in flow systems and for biosensors, step pulse potential and sweeping potential of which the last two are preferred in batch systems. Up and coming are microchip capillary electrophoresis coupled with amperometric screen-printed electrodes [25], Metal sensors are also used, but lack selectivity. They are more useful for classification applications than for evaluation of taste, like predicting sensorial descriptors of Italian red dry wines of different origins [26]. 

This type of manual control is simpler and less expensive, and less expertise is required than automatic control systems. It can be applied to small plants (mainly batch systems) and on easy-to-dry-... 

Ultrasonic waves can be excited into screens, which transfer the vibration to the food product, and the ultrasound emitter can be attached to the center of the screen, as well as to its frame. Direct transmission to the product allows sonication to be used in a large variety of food processes, throughout the complete drying process. Future equipment developments could enable ultrasound-mediated transfer not only to screens but also to trays or conveyor belts, and in this way airdrying in batch systems, as well as in continuous systems, could be assisted by ultrasonic vibrations. Even in vacuum freeze-drying, where air transmission is impossible due to the vacuum, the product can be placed on supports and treated with ultrasonic waves (Schbssler et al, 2012b). 

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