Abstract
Rice (Oryza sativa L.) is the staple food crop in Sri Lanka occupying 34% of the total cultivated area. Seed paddy production is one of the major economic activities in the paddy sector, which is fully mechanized only at the large-scale level. Unavailability of an affordable mechanical solution is a big barrier for entering small and medium scale producers in to the seed paddy industry. Therefore, the aim of this study was to introduce an efficient and affordable electrical motor driven small or medium scale paddy cleaning machine for seed paddy production. The main components of the machine are paddy sieving unit, blowing unit and stone separator. According to the variety of paddy, the sieve size of the sieving unit can be changed. The performance of the machine was evaluated using paddy samples with purposely added light and heavy impurities such as straw particles and different sized stones. The suitable speeds for the better operation of sieve, separator and blower were 90, 200 and 960 rpm, respectively. The separation percentages of the large, light, and same size impurities were 96%, 74%, and 86%, respectively. The effective capacity of the machine was 252 kgh-1 with 79% mechanical efficiency. Based on the overall satisfactory performance, the newly built paddy cleaning machine can be recommended to small and medium scale paddy farmers in Sri Lanka. The machine can be further developed with a magnetic separator for removing iron particles.
Highlights
Paddy, the second largest produced cereal in the world is the staple food crop in most countries
According to the per capita consumption of rice, Myanmar, Lao People’s Democratic Republic, Viet Nam, Bangladesh, Cambodia and Indonesia are considered as very high rice consuming countries (>200 kg year-1) while Thailand, Philippines, Sri Lanka, Sierra Leone, Republic of Korea, Nepal, Madagascar, China, Gambia, Malaysia, Guinea-Bissau, Guyana, Maldives, Brunei Darussalam, Suriname, Democratic People’s Republic of Korea, Côte d’Ivoire, India, Senegal, China-Macao and Costa Rica are under high rice consuming countries (100200 kg year-1) (Nguyen 2020)
Most of the available large scale paddy cleaners in Sri Lanka have more than 1000 kg h-1 capacity
Summary
The second largest produced cereal in the world is the staple food crop in most countries. There are over 144 million rice farms worldwide on a harvested area of about 158 million hectares. World Rice Production in 2017 was 508.6 million metric tons (Shahbandeh 2017). Paddy is cultivated in two seasons as Yala and Maha in Sri Lanka based on the rainfall. 870,000 ha of paddy fields are cultivated annually in Sri Lanka, as 560,000 ha in the Maha season and 310,000 ha in the Yala season engaging 1.8 million farm families. Current annual rice production of Sri Lanka is about 2.7 million tons of rough rice, and it satisfies only 95 percent of the domestic requirement (DOA 2014)
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