Values of enthalpy constants for approximate equations are not tabulated here but are also computed for each stage based on the initial temperature distribution.
In the inner-loop calculation sequence, component flow rates are computed from the MESH equations by the tridiagonal matrix method. The resulting bottoms-product flow rate deviates somewhat from the specified value of 50 lb-mol/h. However, by modifying the component stripping factors with a base stripping factor, S&, in (13-109) of 1.1863, the error in the bottoms flow rate is reduced to 0.73 percent.
The initial inside-loop error from the solution of the normalized energy-balance equations, is found to be only 0.04624. This is reduced to 0.000401 after two iterations through the inner loop.
At this point in the inside-out method, the revised column profiles of temperature and phase compositions are used in the outer loop with the complex SRK thermodynamic models to compute updates of the approximate K and H constants. Then only one inner-loop iteration is required to obtain satisfactory convergence of the energy equations. The K and H constants are again updated in the outer loop. After one inner-loop iteration, the approximate K and H constants are found to be sufficiently close to the SRK values that overall convergence is achieved. Thus, a total of only 3 outer-loop iterations and 4 inner-loop iterations are required.
To illustrate the efficiency of the inside-out method to converge this example, the results from each of the three outer-loop iterations are summarized in the following tables:
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