Question 8.5.1: Production of Hydrochloric Acid Hydrochloric acid is produce......

It is advisable to determine the molar amounts or flow rates of the components of all feed and product solutions before drawing and labeling the flowchart. In this case

The enthalpy table for the process is shown below. As usual, physical property data valid at P = 1 atm are used and the effects on enthalpy of any pressure differences that may occur in the process are neglected.

Note that the value of \dot{n} for the product solution is the molar flow rate of the solute (HCl) rather than the solution, since the enthalpy will be determined in kJ/mol solute.

Calculate \hat{H}_{1} and \hat{H}_{2} :        HCl(g, 25°C) → HCl(g, 100°C)

\hat{H}_{1} = \Delta \hat{H} = \int_{25°C}^{100°C}{C_{p}  dT} \\ \left. \Large{\Downarrow} \right. C_{p}  for  HCl(g)  from  Table  B.2 \\ \hat{H}_{1} = 2.178  kJ/mol

For the product solution,

The heat capacities of aqueous hydrochloric acid solutions are listed on p. 2-183 of Perry’s Chemical Engineers’ Handbook (see Footnote 5) as a function of the mole fraction of HCl in the solution, which in our problem is

Energy Balance:

Heat must be transferred out of the absorber at a rate of 335,000 kJ/h to keep the product temperature from rising above 40°C.