Batch distillation extractive

For mixtures with more than 3 components similar STNs may be generated to represent various operations, with additional states and distillation tasks defined as required. Other STNs can be generated when recycles of off-cuts or solvents are considered. Figure 3.8 shows the STN for a ternary batch extractive distillation with solvent recovery and recycling (Mujtaba, 1999). 

Figure 3.8. STN for Ternary Batch Extractive Distillation with Solvent Recovery and Recycle [Mujtaba, 1999]a...

Figure 10.3. Batch Extractive Distillation (BED) Process. [Mujtaba, 1999] ...

Batch Extractive Distillation with Intermediate Boiling... 

Short-cut Design of Batch Extractive Distillation using... 

An automatic design method for batch extractive distillation, one of the most important techniques for separating low relative volatility or azeotropic mixtures, is presented. Example calculations are performed to the acetone-methanol mixture using water as entrainer. The NLP and MINLP problems are solved with applying GAMS D1COPT++. 

Chapter 13 will illustrate the operations of batch distillation utilizing two previously mentioned separation methods for azeotropic mixtures extractive distillation and heterogeneous azeotropic distillation. In the first part of Chapter 13, operation of batch extractive distillation is studied for separating acetone and methanol using water as the entrainer and separating IPA and water using DMSO as the entrainer. In the latter part of that chapter, a heteroazeo-tropic batch distillation system for acetic acid dehydration will be studied. 

Batch distiUalion is commonly used in the fine chemicals industries, speeialty polymer, bioehemieal, pharmaceutieal, and food. In these types of applications, the production scale is usually small, whieh justifies rumiing the separation process in batch mode. When the mixture contains an azeotrope, the separation methods mentioned in previous chapters can also be operated in batch mode. We will start this chapter by studying the operation of batch extractive distillation for two systems. One is to separate acetone and methanol using water as the entrainer. The other system is to separate IPA and water using DMSO as the entrainer. 

BATCH EXTRACTIVE DISTILLATION (ACETONE-METHANOL WITH WATER AS THE ENTRAINER)... 

The RCMs and the equivolatility curves of this chemical system ean be seen in Figure 13.1, where the numbers in the equivolatility emwes denote the relative volatility of acetone versus methanol in the presence of water. The RCM indicates that any mixture of acetone and methanol, even premixed with water, will produce the acetone-methanol azeotrope at the top of the column. However, by continuously adding water (a heavy entrai-ner) into the column, it can be seen from the equivolatility curves that the acetone is becoming more and more volatile than the methanol in the extractive section. Acetone and methanol can then be separated in the extractive section if the number of trays in this section is sufficient. Acetone will go toward the top of the column while methanol will be carried with the water toward the column bottom. In the rectifying section, owing to the lack of methanol in this section, only the separation of acetone and water is performed. Pure acetone will preferably go to the top of the batch extractive distillation column. After the draw-off of the acetone product and a slop-cut period, where the acetone in the column is completely depleted, the methanol product can be collected at the top of the column. The heavy entrainer (water) can be collected at the column bottom. 

This chapter also demonstrates that the operation of batch extractive distillation can be improved by allowing the reflux ratio and the continuous entrainer feed rate to be varied with time. The simulation results of the IPA dehydration system demonstrate that batch time and entrainer usage can be reduced by including two temperature control loops to manipulate the reflux ratio and the entrainer feed rate. All dynamic simulations used in... 

Yao J. Y., S. Y. Lin, and I. L. Chien, Operation and control of batch extractive distillation for the separation of mixtures with minimum-boiling azeotrope, J. Chin. Inst. Chem. Eng., 38, 371 -383... 

Lang P., H. Yatim, P. Moszkowicz, and M. Otterbein, Batch extractive distillation under constant reflux ratio, Comput. Chem. Engng., 18, 1057-1069 (1994). 

Milani S. M., Optimization of Solvent feed rate for maximum recovery of high purity top product in batch extractive distillation, Chem. Eng. Res. Des., 77, 469-470 (1999). 

Operational fractions of batch extractive distillation in a middle vessel column [1]. 

There are two types of extraction processes, namely, leaching where solids are extracted and liquid-liquid extraction. The commonly used leaching equipment is the extraction battery where counter current flow is established resulting in a number of extracting stages. This can be modeled as equilibrium process. The McCabe-Thiele procedure can be used to model this process. In liquid-liquid extraction, ternary diagrams and tie lines are used to determine the extent of extraction. Batch extractive distillation is a commonly used extractive method for liquid-liquid extraction. 

---