17.12 Energy Balances for Reactions


Equilibrium constants and adiabatic reactor calculations with Excel (uakron.edu, 6 min) We previously discussed adiabatic reactor calculations in Section 3.6 with application to the dimethyl ether process. At that time, we accepted the expression for equilibrium constant as given. In Chapter 17, we must recognize how to compute the equilibrium constant for ourselves. This presentation illustrates the calculations for Example 17.9. These kinds of calculations often occur in the context of an overall process, rather than in isolation. Therefore, the presentation shows how to apply Eqn 3.5b with pathway 2.6c to characterize the enthalpies of process streams and solve for the extent of reaction and adiabatic outlet temperature simultaneously.

Comprehension Questions:

1. Suppose the reactor inlet feed was: kmol/hr of 110 N2, 300 H2, 15NH3 and 16 CH4. Solve for the adiabatic reactor temperature and extent of reaction in that case.
2. Suppose the actual conversion was only 80% of the equilibrium conversion and the inlet feed was the same as given in part 1. Solve for the adiabatic reactor temperature and extent of reaction in that case.
3. Compute the stream attributes for this entire process assuming 85% of the equilibrium conversion and a feed (kmol/h) of 105 N2, 300 H2, 20 CH4 at 10bars and 200C. The distillation column operates at 10 bars with a partial condenser and splits of 99.99% on N2 and 2% on NH3. The recycle ratio is 19:1. Assume the compressors are 100% efficient and the reactor operates adiabatically with an inlet temperature of 400K and a pressure of 100bars. Report the molar flow rates of all outlet stream components.

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