Unit Operations of Chemical Engineering 5th. Edition by Warren L. McCabe, Julian C. Smith, Peter Harriott | 9780070448445 | 0070448442 | Holooly

Intro to Chemical Engineering

Unit Operations of Chemical Engineering

110 SOLVED PROBLEMS

Question: 29.2

A batch grinding mill is charged with material of the composition shown in Table 29.2. The grinding-rate function Su is assumed to be 0.001 s^- 1 for the 4/6-mesh particles. Breakage function Bu is given by Eq. (29.13) with β = 1.3. Both Su and Bu are assumed to be independent of time. (a) How long ...

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(a) For the 4/6-mesh material there is no input fr...

Question: 30.5

Ultrafiltration tests with a 1.5-cm tubular membrane at NRe = 25,000 gave a permeate flux of 40 L/m²-h and 75 percent rejection for a 5 percent polymer solution. The polymer has an average molecular weight of 30,000, and the estimated diffusivity is 5 × 10^- 7 cm²/s. (a) Neglecting the effect of ...

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(a) Base case:

\begin{aligned}v & =40 \...

Question: 30.4

A tubular membrane with a diameter of 2 cm and a water permeability of 250 L/m² -h-atm is being used for UF of cheese whey. The whey proteins have an average diffusivity of 4 x 10^- 7 cm²/s, and the osmotic pressure in atmospheres is given by Jonsson’s equation^23: ...

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(a) Assume the bulk solutions have the same densit...

Question: 28.1

The screen analysis shown in Table 28.2 applies to a sample of crushed quartz. The density of the particles is 2650 kg/m³ (0.00265 g/mm³), and the shape factors are a = 2 and Φs= 0.571. For the material between 4-mesh and 200-mesh in particle size, calculate (a) Aw in square millimeters per gram ...

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To find

A_w \text { and } N_{w}

, Eq...

Question: 29.1

What is the power required to crush 100 ton/h of limestone if 80 percent of the feed passes a 2-in. screen and 80 percent of the product 1/8-in. screen? ...

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From Table 29.1, the work index for limestone is 1...

Question: 28.2

A silty soil containing 14 percent moisture was mixed in a large muller mixer with 10.00 weight percent of a tracer consisting of dextrose and picric acid. After 3 min of mixing, 12 random samples were taken from the mix and analyzed colorimetrically for tracer material. The measured ...

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For this test

\mu=0.10 \text { and } N=12 ;...

Question: 27.6

In the crystallizer of Example 27.5, a growth rate G of 0.0018 ft/h (0.00055 m/h) is anticipated, and a predominant crystal size of 20 mesh is desired. How large must the magma volume in the crystallizer be; what nucleation rate B° is necessary; and what is the screen analysis of the product, ...

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The screen opening of a 20-mesh standard screen is...

Question: 27.5

A continuous vacuum crystallizer is fed with a 31 percent MgSO4 solution. The equilibrium temperature of the magma in the crystallizer is 86°F (30°C), and the boiling-point elevation of the solution is 2°F (1.11°C). A product magma containing 5 tons (4536 kg) of MgSO4 ⋅ 7H2O per hour is obtained. ...

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Figure 27.13 shows the graphical solution of the p...

Question: 27.4

What would. be the size of a nucleus in equilibrium with a supersaturation of 0.029, under the conditions of Example 27.3? ...

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This is solved from the Kelvin equation. Here α = ...

Question: 27.3

Assuming that the rate of heterogeneous nucleation of potassium chloride is consistent with an apparent interfacial tension of 2.5 ergs/cm², determine the nucleation rate as a function of s at a temperature of 80°F (300 K). ...

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Use Eq. (27.11). The molecular weight of KCI is 74...

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