Agro Processing Plant Design Questions and Answers

Answer: C

Correct answer: Capacity follows from the annual tonnage

That is the false statement. Capacity follows from the peak arrival rate, because the crop cannot be held back - sizing on the annual tonnage spread over the year would leave most of it unprocessed. The other three statements are all true, and all follow from that same fact.

Answer: D

Correct answer: An increase in fixed costs

Breakeven is fixed cost over contribution, so raising the fixed cost raises the breakeven output. The other three all lower it: a higher price or a lower variable cost increases the contribution, and a smaller fixed cost reduces what has to be covered.

Answer: A

Correct answer: The rated capacity of each machine

A machine’s rating is a property of the machine, fixed when it is bought - the layout cannot change it. What the layout does govern is travel distance, handling cost and the risk of cross-contamination.

Answer: B

Correct answer: Wrong: cost scales to a power near 0.6

By the six-tenths rule the cost rises by a factor of \(2^{0.6} = 1.52\) - about half again, not double. It is not a rule for large plants only: the economy of scale applies throughout the range, which is why cost per tonne of capacity falls steadily as capacity rises.

Answer: C

Correct answer: Removing one bottleneck simply promotes the next slowest stage

That is the essential character of balancing: it is iterative. Relieve the slowest stage and the next slowest becomes the constraint, so the gain is only as far as the second bottleneck. The other statements are false - the slowest stage sets throughput, balance is precisely a question of capital efficiency, and one step is rarely enough.

Answer: D

Correct answer: Finished product routed past reception

Routing finished product back past the raw material reception is exactly what a food plant layout is designed to prevent: it creates a crossing point between the dirtiest and the cleanest parts of the process. The other three are all standard requirements.

Answer: A

Correct answer: It reflects the distance between consumers in the plant

That is the false statement. The diversity factor has nothing to do with where the consumers are; it exists because they do not all draw their maximum at the same instant. It is established from the plant’s operating pattern, and applying it reduces the utility size - both of which the other statements say correctly.

Answer: B

Correct answer: The number of employees

Headcount says nothing about whether a project is worth doing - it is an input, and a large one may be a cost rather than a merit. Viability is judged by net present value, which discounts the whole cash flow, and supported by breakeven and payback, which measure the margin of safety and the exposure.

Answer: C

Correct answer: Drainability matters more than the material

A vessel that cannot be emptied and dried will harbour organisms whatever it is made of, so drainability is the first requirement: sloped surfaces, no dead legs, no pockets that hold liquid. Stainless steel helps but guarantees nothing; threaded fasteners and horizontal ledges both trap product and are avoided in product areas.

Answer: D

Correct answer: Scale-up rarely behaves exactly as calculation predicts

A pilot plant is built to find out what calculation cannot tell you: how heat transfer, mixing, handling and fouling behave at an intermediate scale, and how the actual raw material behaves rather than a clean sample. It costs money rather than saving fixed capital, and it exists to reduce the risk of a far more expensive surprise at full size.