Rice dryers

Golmohammadi, M., M. Rajabi-Hamane, and S. J. Hashemi (2011). Optimization of drying-tempering periods in a paddy rice dryer. Drying Technology 30(1) 106-113. 

Courtois, F., Abud-Archila, M., Bonazzi, C., Meot, J., Trystram, G., 2001. Modeling and control of a mixed-flow rice dryer with emphasis on breakage quality. J. Food Eng. 49(4) 303-309. 

Commercial rice dryers are nsnaUy continuous flow or multipass. The first is commonly used in large operations and consist of an upright structure into which rough... 

Orifice scrubbers are used in industrial applications including food processing and packaging (cereal, flour, rice, salt, sugar) pharmaceutical processing and packaging and the manufacture of chemicals, rubber and plastics, ceramics, and fertilizer. Processes controlled include dryers, cookers,... 

The drum dryer is also extensively used to dry and gelatinize or cook starch slurries, such as potato, rice, - wheat, " maize, com," soybean-banana, and cowpea slurries to produce pregelatinized starch for instant foods. Nonstarch, low-sugar foods, such as tomato puree, milk, skim milk, whey, beef broth, yeast," coffee, and malt extract, have also been successfully dried on a drum dryer. Heat-sensitive products such as pharmaceuticals and vitamin-containing products can be dried in a vacuum drum dryer. 

Furukawa et al. reported on a conunercial steam drying and deodorization plant to process soy sauce cakes as feedstock [27]. An agitated trough steam dryer (1.5 ton/h dry product capacity) was used. Deodorization commenced at a moisture level below 4% (dry basis) and a temperature of 135°C. The oils and fats distilling from the cake result in deodorization. Indeed, the fats and oils were used as auxiliary fuels for the process. Concurrent steam drying and deodorization of rice bran, fish meal, and pupa were also reported by Akao [28]. In these products, the odor is due to oxidation of lipids. Akao also showed that the quality of green tea and vegetables dried in steam (e.g., color, odor, etc.) was acceptable. 

In industrial rice mills, fast drying is preferred, and hence, the LSU dryer is the most popular. This vertical dryer has rows of air channels with staggered arrangement crossways alternative rows open to plenum inlets and intervening rows to exhaust outlets as shown in Figure 28.5. Moist paddy is dried and mixed when it flows from the top, passing the rows of air channel to the bottom of the dryer, and recirculates until the desired final moisture content has been reached. 

Figure 28.13 shows the conventional production process of parboiled rice that is currently operated in some factories in Thailand and some other countries. After steaming, parboiled paddy is dried to a moisture content of 39% (d.b.) (28.5% [w.b.]) by a hot-air fluidized-bed dryer, tempered (no. 5) and dried again in the fluidized-bed dryer to 21% (d.b.). Below this, an LSU dryer is used to dry the paddy to a safe-storage moisture level. 

FIGURE 28.13 Conventional parboiled rice process production. (1) Soaking tank (2) steamer (3) ambient air ventilator (4) fluidized-bed dryer (5) tempering and air ventilation unit (6) LSU dryer (7) storage bin. (From Rordprapat, W. et al., J. Royal Inst. Thailand, 30,363,2005.)... 

Rattanamechaiskul, C. Soponronnarit, S. Prachayawarakom, S. Tungtrakul, P. Optimal operating conditions to produce nutritious partially parboiled brown rice in a humidified hot air fluidized bed dryer. Drying Technology 2013, 31, 368-377. 

Rordprapat, W. Nathakaranakule, A. Tia, W. Soponronnarit, S. Development of a superheated-steam-fluidized-bed dryer for parboiled rice. The Journal of the Royal Institute of Thailand 2005, 30, 363-378. 

Roberts RL, Carlson RA, Parkas DF. Preparation of a quick-cooking brown rice product using a centrifugal fluidized bed dryer. J Food Sci 45 1080-1081, 1980. 

Deep bed/dihedral dryer cereals malt, maize, sunflower grain, rice, wheat... 

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