Equinox… A Balanced Perspective


Plants adopt a scientific, IT-enabled work-flow to track their solvent recovery systems. Gain better yield and/or purity and/or capacity!!

The chemical process industry has been employing various kinds of solvent recovery strategies, mostly led by distillation operation. Although the art and science of distillation is well understood, it is the complex phase behavior of solvent containing streams, which makes it difficult to optimize the distillation operation. The industry has even learnt to live with the classical trade-off between yield and purity. The significant milestone has now been achieved by combining various mathematical tools to predict the multi-phase, VLE and VLLE, behavior of multi-component systems, comprising of solvent-impurity-entrainers. The field validation of these techniques has increased the confidence of designers to opt for other separation methods, like extraction.

An analytical framework, consisting of a series of steps using different modeling tools, has been developed by the EQNX team in Pune. MAXSOL was first deployed at an API facility of a Pharmaceutical company. Based on that initial success MAXSOL was updated and applied in another API plant. Apart from these operating plants, MAXSOL was also tried for a new plant design– that plant has already been commissioned and working successfully.

While the Pharmaceutical industry may not generate a large volume of waste, as compared to the Steel and Petroleum industries, it does generate the highest amount of waste per unit of finished products.

The pharmaceutical industry in the US generated 128 million kg of water in 2006. This waste included mainly organic solvents, the top three of which are methanol, 44.8 million kg/year; dichloromethane, 22.3 million kg/year; and toluene, 12.1 million kg/year. The top 10 solvents accounted for more than 80 per cent of the waste generated (see figure above)

The industry requires different solvents at various steps of synthesis, isolation and purification. And the solvent usage could account for as much as 80-90% of the total mass in the process. Or in other words, the amount of waste generated could be as high as 25 to 100 kg per kg of final API product.

Pharmaceutical wastes typically contain multiple solvents (in both homogeneous and heterogeneous mixtures), unconverted reactants and other byproducts, requiring complex separation schemes to obtain high quality solvent for re-use.

However, once the economic criterion is superimposed, then the picture changes. This is shown in Fig. 2.0, which unequivocally throws E113 as the candidate exchanger for cleaning in this round

A large amount of knowledge base on distillation operation is already there in literature as well as in the industry. This knowledge base, no doubt useful, is also responsible for an impression in the industry that what their engineers or operators are typically doing is already the best they could. Or they have already tried “All” the options to optimize their distillation operation.

MAXSOL actually challenges and competes with this mind-set. Moving away from the simple X-Y graphs of Macabe-Thiele diagrams, it is a fundamentally different way, to approach the optimization problem.

To know more download the brochure : MAXSOL

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