An automated sample divider for farmers stock peanuts

Authors: Butts, Christopher - Chris; Sheppard, Harry - Hank; Lamb, Marshall

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2016
Publication Date: 4/25/2017
Citation: Butts, C.L., Sheppard, H.T., Lamb, M.C. 2017. An automated sample divider for farmers stock peanuts. Applied Engineering in Agriculture. doi:10.13031/aea.11798.

Interpretive Summary: Farmers harvest peanuts after partially drying in the windrow, then are loaded into drying trailers, and delivered to a peanut buying point. At the buying point, they are dried to a moisture content safe for long term storage, sampled, graded, then unloaded into bulk storage. These drying trailers are various sizes with capacities that range from five to twenty-five tons of dry farmers stock peanuts. Each conveyance is sampled using a pneumatic probe that is inserted into the load multiple times in a semi-random pattern. Approximately 10-15 lb of peanut material is extracted from the load each time it is probed and the number of times a load is probed depends on the size of the trailer. The total amount of peanuts extracted for grading ranges from approximately 50 to 250 lb. That sample is subsampled using a rotating sample divider to obtain 7 to 15 lb of farmers stock peanuts, and then manually divided over a riffle divider to obtain an official grade sample and a check sample. The preferred grade sample size is 4.0 ± 0.6 lb. An instrumentation and control system consisting of an ultrasonic bin level sensor, an electric motor brake, and a Programmable Logic Controller (PLC), was installed and calibrated to control a rotating sample divider. The PLC calculates the delay interval for rotating the divider through the stream of peanuts flowing out of the sample bin based on the bin level sensor output. The PLC then releases the bin gate, controls the rotating divider to achieve the desired 3.6-kg sample. Commercial prototypes were developed, calibrated, and tested in the laboratory then installed and operated at a commercial peanut buying. Due to variations in sampling bin construction, the commercial prototype required site specific calibration to consistently provide the desired sample size.

Technical Abstract: In-shell peanuts are harvested, loaded into drying trailers, and delivered to a central facility where they are dried to a moisture content safe for long term storage, sampled, graded, then unloaded into bulk storage. Drying trailers have capacities ranging from five to twenty-five tons of dry farmers stock peanuts. Each conveyance is sampled using a pneumatic probe that is inserted into the load multiple times in a semi-random pattern. The total amount of peanuts extracted for sampling is proportional to the size of conveyance and may range from approximately 22 to 115 kg. That sample is subsampled using a rotating sample divider to obtain 3.0 to 6.0 kg of farmers stock peanuts, and then manually divided over a riffle divider to obtain an official grade sample and a check sample. The preferred grade sample size is 1800 ± 300 g. An instrumentation and control system consisting of an ultrasonic bin level sensor, an electric motor brake, and a PLC, was installed and calibrated to control a rotating sample divider. The PLC calculates the delay interval for rotating the divider through the stream of peanuts flowing out of the sample bin based on the bin level sensor output. The PLC then releases the bin gate, controls the rotating divider to achieve the desired 3.6-kg sample. Commercial prototypes were developed, calibrated, and tested in the laboratory then installed and operated at a commercial peanut buying. Due to variations in sampling bin construction, the commercial prototype required site specific calibration to consistently provide the desired sample size.