Chapter 4, Problem 4.32P

Gas streams containing hydrogen and nitrogen in different proportions arc produced on request by blending gases from two feed tanks: Tank A (hydrogen mole fraction = jea) and Tank B (hydrogen mole fraction = jeb )• The requests specify the desired hydrogen mole fraction, je_p, and mass flow rate of the product stream, zh_P(kg/h).

1. Suppose the feed tank compositions are xa = 0.10 mol Hi/mol and xb = 0.50 mol H?/mol, and the desired blend-stream mole fraction and mass flow rate are x_p = 0.20 mol H₂/mol and ihp = lOOkg/h. Draw and label a flowchart and calculate the required molar flow rates of the feed mixtures, «A(kmol/h) and /iB(kmol/h).
2. Derive a series of formulas for n_A and zi_B *n terms of x_A, x_B. x_p, and m_P. Test them using the values in Part (a).
3. Write a spreadsheet that has column headings XA,XB.x_P,zzz_p,ziA.andziB. The spreadsheet should calculate entries in the last two columns corresponding to data in the first four. In the first six data rows of the spreadsheet, do the calculations for je_a = 0.10, je_b = 0.50, and je_p = 0.10. 0.20. 0.30, 0.40. 0.50, and 0.60, all forzzz_P = lOOkg/h. Then in the next six rows repeat the calculations for the same values of je_a, x_b, and x_P for zzz_P = 250 kg/h. Explain any of your results that appear strange or impossible.
4. Enter the formulas of Part (b) into an equation-solving program. Run the program to determine zza and h_Bfor the 12 sets of input variable values given in Part (c) and explain any physically impossible results.