Estimate the 2020 cost of the condenser and the reboiler (shell and tube, floating head) for Problem 11.D1. Steam is available at 41.0 barg, but due to pressure losses, the steam is at \(230.0^{\circ} \mathrm{C}\) when it enters the reboiler. Cooling water is available at \(30.0^{\circ} \mathrm{C}\) and is returned to the cooling tower at \(45.0^{\circ} \mathrm{C}\). Latent heat of \(\mathrm{n}\)-hexane and \(\mathrm{n}\)-heptane can be estimated from (Green and Perry, 2008, 2-152):

\(\lambda_{\mathrm{C} 6}(\mathrm{~kJ} / \mathrm{kmol})=45,440\left(1-\mathrm{T} / \mathrm{T}_{\mathrm{c}}\right)^{0.39002}, \mathrm{~T}\) in \(\mathrm{K}, \mathrm{T}_{\mathrm{c}}=\) critical temp. \(=507.6 \mathrm{~K}\)

\(\lambda_{\mathrm{C} 7}(\mathrm{~kJ} / \mathrm{kmol})=50,014\left(1-\mathrm{T} / \mathrm{T}_{\mathrm{c}}\right)^{0.38795}, \mathrm{~T}\) in \(\mathrm{K}, \mathrm{T}_{\mathrm{c}}=\) critical temp. \(=540.2 \mathrm{~K}\)

Boiling points can be estimated from the DePriester charts.

Problem 11.D1.

Repeat Example \(11-1\) except at \(400.0 \mathrm{kPa} . \mathrm{F}=1000.0 \mathrm{lb} \mathrm{mol} / \mathrm{h}, \mathrm{L} / \mathrm{D}\) \(=4.0\), distillate is \(99.9 \mathrm{~mol} \% \mathrm{n}\)-hexane, and bottoms is \(0.1 \mathrm{~mol} \% \mathrm{n}\) hexane. At this pressure, \(\mathrm{E}_{\mathrm{o}}\) is determined in Problem 10.D1, the relative volatility depends on pressure, and diameter is calculated in Problem 10.D5. Hint: See answers to problems 10.D1 and 10.D5 in back of book immediately before the index.

a. Find \((\mathrm{L} / \mathrm{D})_{\min }\).

b. Find \(_{N \text { min }}\).

c. Estimate \(\mathrm{N}_{\text {equil }}\).

\section*{d. Estimate \(\mathrm{N}_{\text {actual }}\).}

e. Find cost of shells and trays using the bare module cost calculation procedure and the data in Table 11-2. Update costs to 2020.

Example 11-1

Example 11-2

Example 11-3

Table 11-2

Data From Problem 10.D1

Repeat Example 10-1 for an average column pressure of \(400.0 \mathrm{kPa}\).

Example 10-1

Data From Problem 10.D5

Repeat Example 10-2 except calculate the diameter at the bottom of the column at a pressure of \(400.0 \mathrm{kPa}\). The surface tension of pure \(\mathrm{n}-\) heptane at \(20^{\circ} \mathrm{C}\) is 20.14 dynes \(/ \mathrm{cm}(0.0214 \mathrm{~N} / \mathrm{m})\), and the temperature coefficient is \(-0.0980 \mathrm{dynes} / \mathrm{cm} / \mathrm{K}\) (www.surface-tension.de). Use the DePriester chart to estimate bottoms temperature.

Example 10-2

Example 10-1

 

Transcribed Image Text:

(kJ/kmol)=45,440 (1 - T/T)0.39002, T in K, T = critical temp. = 507.6 K (kJ/kmol) = 50,014 (1 - T/T 0.38795, T in K, T = critical temp. = 540.2 K