The energy requirement of for rice processing at commercial level is discussed. There are two types of mills engaged in rice processing i.e. conventional and modern rice mills. Conventional rice mills: Conventional rice mills are the units, in which the paddy processing is carried out by using steel hullers, an age old technology which is inefficient. Different activities like paddy cleaner, grading, polishing etc. are carried out manually. Modern rice mills: Modern rice mills are the units, in which the paddy processing is carried out by using rubber roll shellers, a modern technology which is more efficient. Majority of the activities are carried out using machineries like driers, aspirators, graders, polishers etc. Different stages of paddy processing in commercial rice mills are followed viz., parboiling process, drying of parboiled paddy and finally milling operation to get finished product.
Rice milling industry is the largest agro-based industry in India. In 2009, India had approximately 1,74,296 rice milling units. The number of hullers was 95,808, shellers 6,724 huller-cum-shellers 10,540 and modern/modernized rice mill 36,088, respectively (MoFPI 2010). Information related energy used pattern in rice mills is vital for developing work plan to acquire better control over processing operations and to properly appraise energy consumption in production, planning and marketing. The important utilities in a rice mill are water, air, steam, electricity and labour. In a rice mill some of the operations are done manually namely, feeding paddy to the bucket elevators, cleaning, sun drying, weighing and bagging. So, the man-hours should to be included in this energy accounting study. Water is used for soaking and steam generation.
This study was carried out at the Rice Research Institute of Iran (RRII) to investigate the effect of rollers differential peripheral speed of commercial rubber roller husker and paddy moisture content on the husking index and percentage of broken rice. The experiment was conducted at six levels of rollers differential speed (1.5, 2.2, 2.9, 3.6, 4.3 and 5 m s -1) and three levels of paddy moisture content (8-9, 10-11 and 12-13% w.b.). Two common paddy varieties, namely Binam and Khazer, were selected for this study. Results revealed that the effect of rollers differential speed and moisture content significantly (P<0.01) affected percentage of broken brown rice and paddy husking index. Average broken kernel percentage increased from 13 to 14.61% while husking index decreased from 71.64 to 61.81%, as paddy moisture content increased from 8-9 to 12-13%.