Distillation is one of mankind’s oldest industrial processes, and it still remains today one of the most pervasive. It touches almost everything we eat, drink, wear or use at some point in the supply chain. It is also a voracious consumer of energy. Industrial distillation and evaporation processes account for some 5% of all the energy used in the United States.
There is a well-known technique that could be used to significantly reduce this figure. Known as multiple-effect distillation (MED), it applies heat at high temperature to an initial distillation stage – then re-uses the same heat repeatedly at progressively lower temperature and pressure. MED is already in widespread use in many industries, but cannot be applied to fluids that are sensitive to the high temperature of the first stage of distillation. Some fluids in this category, such as fermentation broth, tend to bake on and foul hot heat exchange surfaces. Others, such as food products, lose flavour and/or other important characteristics through thermal degradation.
For some of these fluids, even simple single-effect distillation involves temperatures high enough to cause problems. In these cases, distillation may be carried out at lower temperatures, if it is helped by refrigeration equipment. Unfortunately, this solution is expensive. Many processes that could benefit from low operating temperatures, cannot afford the extra cost of operating a chiller.
Clearly, the many industries that depend upon industrial evaporation and distillation will benefit from a process that can accomplish the same separation at low temperature, while providing the energy-saving benefits of MED at the same time.
We encourage a broader discussion of its basic principles under the non-commercial heading “Pass-through distillation” (PTD). We recommend that you visit the website www.passthroughdistillation.com to gain an understanding of how it works.