Rice Drying-76



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Project Leader and Principal UC Investigators

Glenn Nader, livestock farm advisor, UC Cooperative Extension Butte/Sutter/Yuba Counties


The recent increased costs of fuel from nonrenewable resources have created urgent interest in evaluating the energy performance of rice-drying systems.

Recent rice-drying research has focused on improved efficiency of deep-bed dryers and on ways and means of improving the capacity of existing columnar dryers. UCD engineers studied field hulling of rice and methods of drying the dehulled product, but found this system unpromising. Extension engineers, in 1973-74, conducted field investigations to determine the physical requirements for efficient drying of smooth-hull rice varieties. The information gained was incorporated in a publication, revised in December 1975, entitled "Deep Bed Grain Drying" (UC Leaflet 2103, by S. M. Henderson and R. A. Parsons). Recent column drying experiments by UCD and the USDA have not yet provided any conclusive ideas on ways of reducing energy costs for drying.

A three-year study was begun in 1975-76 to search for ways of improving the energy efficiency of rice drying.

The study focuses on three specific objectives:

  1. To increase the energy efficiency of rice dryers by: a) partial re-use of exit air b) use of other dryer configurations concurrent flow, countercurrent flow, etc.
  2. To determine the optimum time in terms of moisture content of rice when it is most economical to transfer rice from a columnar dryer to a deep-bed dryer.
  3. To develop computer-aided simulations of rice drying for evaluating dryer performance in terms of energy efficiency, rice quality, and increased capacity.

To study these objectives, an experimental rice dryer was designed, constructed, and installed at UCD in 1976.

Consisting of three modules with provision to recycle air during drying, the dryer will permit controlled studies to measure the amount of energy used in drying rice. A mini-computer is used to assist in rapid data analysis, thus saving time during the short rice-harvest season. It is anticipated that computer-aided studies, similar to those recently conducted in the Midwest for corn drying, may help in modifying existing dryers to achieve higher energy efficiencies and larger capacity while maintaining head quality.

Private manufacturing interest was shown in modified-atmosphere storage of rice. This type of low-oxygen storage, if successful, could have substantial impact on rice drying and storage technology in California and rice-growing areas around the world.

Insect control could be significantly improved in stored rice. Rice with high insect infestations is stored under varied conditions at UCD, with periodic measurements conducted to obtain data on the prospects of modified-atmosphere storage.


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