In washing-type plate and frame presses, the ratio of wash rate to the final filtrate rate is__________________?
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Answer: B. 1/4
Explanation
Washing-type plate and frame presses route wash liquid through the cake to displace residual mother liquor. The geometry of the internal plate drainage channels results in wash rates equaling one-quarter of final filtrate flow. This specific hydraulic ratio reflects the increased flow resistance encountered during the washing cycle stage. Plate and frame filter presses consist of alternating hollow frames and solid plates covered with filter cloth. Washing cycles remove soluble impurities from the accumulated filter cake before final discharge. Wash liquid must traverse the entire cake thickness, doubling the effective flow path compared to filtration.
Chemical and pharmaceutical industries use washing presses to produce high-purity crystalline chemical products. Optimizing wash time ensures maximum impurity removal without unnecessarily prolonging total cycle times. Understanding filtration and washing rates helps engineers size pumps and filter press capacities correctly. Option A suggests a wash rate four times higher than filtrate, which contradicts internal press flow geometry. Option C assumes wash and filtrate rates are identical, ignoring the added resistance of wash liquid flow. Option D proposes a one-half ratio, which overestimates the typical wash permeability in standard presses.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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