Subtopic: Drying and milling of cereals, pulses and oilseeds
Question Statement:
M kg of wheat at 9.8% moisture content (wet basis) is conditioned for 6 hours in 75 kg of water. A sample of 25 g conditioned wheat is crushed and dried in hot air oven at 130°C for 1 hour that yields 20.5 g of bone dried material. The value of M is _______.
Official Answer Key:
749 to 751
Step-by-Step Solution & Explanation
Moisture content of the conditioned wheat sample (wet basis), from the oven test:
MC_final = (25 − 20.5)/25 = 4.5/25 = 0.18 = 18%.
Mass balance on M kg of wheat initially at 9.8% MC(wb), to which 75 kg of water is added (conditioning), all retained:
Dry matter (unchanged) = M(1−0.098) = 0.902M.
Total water after conditioning = 0.098M + 75.
Total mass after conditioning = M + 75.
MC_final = (0.098M + 75)/(M + 75) = 0.18
0.098M + 75 = 0.18M + 13.5
75 − 13.5 = 0.18M − 0.098M = 0.082M
61.5 = 0.082M ⇒ M = 750.0 kg, matching the accepted range exactly.
Size Reduction and Material Handling
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