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Key NT no of plates, Mix Mixture Tj minimum batch time for the separation using lowest plate holdup (2 ) T2 minimum batch time for the separation using optimal plate holdup Ts time saved (T, - T2) x 100 7, Key NT no of plates, Mix Mixture Tj minimum batch time for the separation using lowest plate holdup (2 ) T2 minimum batch time for the separation using optimal plate holdup Ts time saved (T, - T2) x 100 7, 3.5.3.1. Effect of Plate Holdup on the Column Performance Column configurations (NT)...

Multiperiod Operation Optimisation

In batch distillation, as the overhead composition varies during operation, a number of main-cuts and off-cuts are made at the end of various distillation tasks or periods (see Chapter 3). Purities of the main-cuts are usually determined by the market or downstream process requirements but the amounts recovered must be selected based on the economic trade off between longer distillation times (hence productivity), reflux ratio levels (hence energy costs), product values, etc. Increasing the...

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ACC (annualised capital cost, hr) K 05 (N -2)0'8 + K2V0 65 (11.9) where, i mixture index, Clj product price 10 kmol, C2j raw material cost 2 kmol, K, 1500, K2 9500, K3 180 and A 8000, i, batch time, ts startup time 0.5 hr. The annualised capital cost function and parameters are taken from Logsdon etal. (1990). Note that since both the top and bottom product compositions are fixed (and so are the total amounts of distillate and bottoms for each mixture) the profit shown in Table 11.8 represents...

Unconventional Batch Distillation

Over the last few decades many alternative column configurations and operation have been suggested for batch distillation. The features and characteristics of such configurations have been briefly presented in Chapter 2 with process models of different degree of complexity in Chapter 4. The flexibility and operational issues of some of these configurations will be presented in this chapter. 11.2. Use of Continuous Columns for Batch Distillation In the mid Eighties, 99 batch processes within 74...

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Equations II.6-II.17 are iterative to estimate the right value of C and therefore to calculate xlD. Note that Sundaram and Evans (1993a,b) used FUG method of continuous distillation directly and developed time explicit model, while Diwekar (1992) developed modified FUG method as described above and time implicit model for batch distillation. Sundaram and Evans used time as an independent variable of the model while Diwekar (1992) used reboiler composition as independent variable. Both models...

10 Batch Extractive Distillation

The separation of azeotropic or close boiling mixtures is often the most difficult task in many chemical industries. Under normal operating conditions high recovery of species with high purity is not possible. The separation of these mixtures using a conventional distillation column is not an economically feasible option as a very large column or a very high reflux ratio operation would be required to separate these mixtures. Pressure swing distillation is used sometimes to break the azeotropic...

Greaves Patel Chem Eng Res Des 1985 199

Optimum Temperature Trajectories (Feedback Strategies) Albet, J., Le Lann, J.M., Joulia, X. and Koehret, B., In Proceedings Computer Oriented Process Engineering (Elsevier Science Publishers B.V., Amsterdam, 1991), 75. Balasubramhanya, L.S. and Doyle III, F.J., J. Proc. Cont. 10 (2000), 209. Basualdo, M.S. and Ruiz, C.A., Lat. Ame. Appl. Res. 25-S (1995), 29. Barbosa, D. and Doherty, M.F Chem. Eng. Sei. 43 (1988), 529. Bernot, C., Doherty, M.F. and Malone, M.F., Chem. Eng. Sei. 46...

Batch Reactive Distillation Bread

Reactive Distillation processes combine the benefits of traditional unit operations with a substantial progress in reducing capital and operating costs and environmental impact BP Review, 1997 Taylor and Krishna, 2000 . Traditionally, as in many chemical industries, reaction and separation take place separately Figure 9.1 in a batch reactor followed by a batch distillation column Charalambides et al., 1994 . Therefore, the distillation of desired species cannot influence the conversion of the...

C

inequality constraint model equations, equality constraints initial conditions, equality constraints inequality constraints where C is the conversion of the limiting reactant, xD tf is the composition of distillate at the end of the operation tf , r i is the reflux ratio as a function of time t . Solution method for such optimisation problem has been discussed earlier. Note that other types of dynamic optimisation problems such as minimum time, maximum profit, etc. could also be formulated and...

Design And Operation Optimisation

There are many papers in the literature dealing with the optimisation of the operation of batch distillation for a given column design and for a single separation duty Farhat et al. 1990 Bernot et al., 1991, 1993 Logsdon and Biegler, 1993 Mujtaba and Macchietto, 1993 . However, the design of batch columns has attracted much less attention. The main design parameters Al-Tuwaim and Luyben, 1991 are the Number of stages plates in the column Still capacity batch size Reboiler and condenser size...

Column Configurations

Conventional Column Configuration In this configuration, the available separation section tray or packed is utilised in rectifying mode, with product cuts recovered and intermediate off-cut fractions disposed of or recycled collected as condensed distillate. A final residue bottom fraction may also be a desired product. Conventional column configuration has been discussed in section 1.4 of Chapter 1. Further details are given in later chapters. 2.2. Unconventional Column Configurations...

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Where Mw is the vapour molecular weight, pv is the vapour density lb ft3 , Vm is the maximum allowable superficial velocity ft s given by where Kv empirical constant 0.3 ft s for 24-in spacing between plates pL is the liquid density lb ft3 . c. The energy consumption ', Btu hr where, Hv' is the molal heat of vaporisation of the feed Btu lb mole d. The steam flowrate W lb hr where, Hv is the heat of vaporisation of steam 915.5 Btu lb The Energy Cost Cg, hr can be calculated using e. The reboiler...

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XB1A lt 0.0, 0.0, 0.004,0.996 gt Figure 4.20. MultiBD Column - Product Amounts and Compositions 4.4. Packed Batch Distillation and Model Extensive literature survey shows that only a few considered modelling, simulation and optimal control of such column Hitch and Rousseau, 1988 Hansen and Jorgensen, 1986 . Nad and Spiegel 1987 simulated their experimental packed column using the methods developed for tray columns by estimating the number of trays representative of the packed height. The...