Separation Process Principles- 2n - Seader & Henley - Solutions Manual

The column feed is 142 vaporized the distillate rate

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: intercooler stage 5 Liquid out, lbmol/h 452.04 498.69 500.53 500.74 500.74 Temp., gas out, oF 144.9 133.8 137.3 138.6 138.6 Because the temperature was still significantly higher than the lower limit of 100oF, a higher intercooler heat duty of -2,000,000 Btu/h was tried at stage 5. However, the temperature of that stage dropped to 84oF. For a duty of -1,500,000 Btu/h, the temperature of stage 5 was an acceptable value of 102oF. The liquid out increased to 599.68 lbmol/h and the temperature of the gas out decreased to 127.5oF. The corresponding component absorption rates compared to those of the base case (no intercooler) were as follows: lbmol/h: Component No intercooler -1,500,000 Btu/h, stage 5 C1 13.75 21.09 C2 101.17 171.52 C3 143.59 212.32 nC 4 23.94 24.98 nC 5 5.57 5.66 Total: 288.02 435.57 Thus, the effect of the intercooler is very significant. The corresponding stage temperatures compared to those of the base case are also of interest: o Stage No intercooler -1,500,000 Btu/h - stage 5 F: 1 144.9 127.5 2 153.1 134.1 3 156.1 135.1 4 157.3 128.5 5 154.6 102.1 6 144.3 114.9 Exercise 10.39 Subject: Design of a an absorber with two absorbent oil feeds. Given: Feed gas at 90oF and 400 psia with the composition given below. Column has 8 equilibrium stages. Lean oil, assumed to be nC12, at 80oF and 400 psia at 250 lbmol/h enters the top stage. Secondary oil at 80oF and 400 psia, of the composition given below, enters stage 7 from the top. 150,000 Btu/h (-0.15 MMBtu/h) is removed by intercooling from stage 7. The feed gas enters stage 8. Assumptions: SRK for K-values and enthalpies. Find: Product rates and compositions, stage temperatures, and interstage vapor and liquid flow rates and compositions. Analysis: The calculations were made with the Tower model (Inside-out method) of Chemcad, with the following specifications: No condenser Top pressure = 400 psia Column pressure drop = 0 psi. Number of stages = 8 Lean oil (1st feed) to stage 1 Secondary oil (2nd feed) to stage 4 Intercooler (3rd feed) at stage 7 Feed gas (4th feed) to stage 8 At the top, no condenser At the bottom, no reboiler Estimated distillate rate = 450 lbmol/h Estimated reflux rate = 350 lbmol/h Estimated temperature of stage 1 = 110oF Estimated temperature of bottom stage = 100oF Estimated temperature of stage 2 = 100oF Note that the intercooler is treated as the 3rd feed with a specification as a stream of -0.15 MM Btu/h. Convergence was achieved in 4 iterations. The results are shown on the following two pages. Note that the degree of absorption was good with following results: Component C1 C2 C3 nC 4 nC 5 % in Feed gas absorbed 15.2 73.4 99.2 99.98 100.00 Exercise 10.39 (continued) Analysis: (continued) Exercise 10.39 (continued) Analysis: (continued) Exercise 10.40 Subject: Reboiled absorber for the separation of a hydrocarbon mixture. Given: Absorbent oil of nC9 at 60oF and 230 psia and 40 lbmol/h. Feed at 120oF and 230 psia with the composition given below. Column has 15 equilibrium stages plus a parti...
View Full Document

This document was uploaded on 02/24/2014 for the course CBE 2124 at NYU Poly.

Ask a homework question - tutors are online