Design of hybrid drying- dedusting unit processor for rough rice processing

Law Chung Lim, Wan Ramli Wan Daud

Research output: Contribution to journalArticle

Abstract

Advanced drying technology enables drying of rough rice and dedusting of rice husks to be carried out simultaneously in the same unit processor. This paper reports the efficiency of dedusting of rice husks in a two-stage inclined cross flow fluidized bed dryer and the drying kinetics of rough rice in a batch fluidized bed dryer as well as the conceptual design of a hybrid drying - dedusting unit processor. Experimental works had been carried out using rough rice (a Group D particle according to Geldart classification of powders) in a 2.5 m height two-stage inclined fluidized bed column of cross sectional area of 0.61m x 0.15m and a 3 m high batch fluidized bed dryer. The objectives of the study was to investigate the separation efficiency of dedusting of rice husks in the two-stage cross flow fluidized bed dryer and to study the drying kinetics of rough rice drying in the batch fluidized bed dryer. The experimental results showed that the dedusting separation efficiency at low superficial gas velocity gave unsatisfactory separation of merely 40% of rice husks. At higher superficial gas velocity, separation efficiency of rice husks as high as 93% was achieved. In addition, higher distributor inclination angle gave slightly improved separation efficiency. The drying kinetics showed that the residence time that is required to reduce the moisture content of rough rice to 18% (intermediate storage moisture content for second stage drying) is 3 minutes whereas the residence time that is required to reduce the moisture content to 13% (desirable final moisture content) is approximately 10 minutes regardless of the effect of kernel cracking. It was also found that higher drying temperatures gave higher drying rate. A conceptual design has been developed based on the results obtained in the studies. In order to maximize the heat utilization and to carry out two processes viz. dedusting and drying in one unit processor, it is suggested that drying - dedusting can be carried out in a multistage mode where drying is taken place at each stage while dedusting is taking place at the upper stage. This concept can be applied to a packed bed or a fluidized bed unit processor.

Original languageEnglish
Article number8
JournalInternational Journal of Food Engineering
Volume4
Issue number6
Publication statusPublished - 29 Jul 2008

Fingerprint

rough rice
Drying
drying
fluidized beds
Processing
Fluidized beds
rice hulls
dryers
Moisture
water content
kinetics
Conceptual design
Gases
Oryza
Kinetics
gases
Powders
drying temperature
cracking
Packed beds

Keywords

  • Distributor
  • Elutriator
  • Fluidized bed
  • Particle separation
  • Rice husk

ASJC Scopus subject areas

  • Engineering (miscellaneous)
  • Food Science
  • Biotechnology

Cite this

Design of hybrid drying- dedusting unit processor for rough rice processing. / Lim, Law Chung; Wan Daud, Wan Ramli.

In: International Journal of Food Engineering, Vol. 4, No. 6, 8, 29.07.2008.

Research output: Contribution to journalArticle

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