2014 Morning 21. How to solve real exam questions on filtering?
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In the morning of 2014, a certain suspension was filtered using a plate and frame filter under a constant pressure difference. The filter cake was incompressible, and the resistance caused by the medium could be ignored. What is the percentage increase in processing capacity when the filtration pressure difference is increased by 50%, while the filtration time remains unchanged? Which of the following values represents this percentage? (A) 50.0 (B) 41.4 (C) 26.3 (D) 22.5 How to solve this? Please help, thanks!
This post was last edited by Xingying Suifeng on 2016-8-25 at 16:28. Equation for constant-pressure filtration: (V+Ve)² = K(θ+θe)A². Here, K = 2kΔp₁ – S; k is a constant related to the properties of the material. In constant-pressure filtration, when the resistance of the medium can be ignored, Ve = 0 and θe = 0, and the compressibility of the filter cake is zero (s = 0). Therefore, V² = 2kΔpA²θ; thus, V² ∝ Δp. Hence, ΔV/V = (√1.5 – 1) × 100% = 22.5%. The correct answer is D