Purification, Delivery, and Recycling
During the initial technology development period, adjunct innovations were co-developed to support the immersion and spray cleaning platforms. Shown in Figure 1-20, technologies include single- and multi-stage distillation systems, cold-trap refluxing stills, in-situ condenser-purifiers, and high pressure-capacity delivery systems.
A novel purification and recycling process called “isobaric distillation” is shown schematically in Figure 1-21. The isobaric distillation process continuously distills and condenses under relatively constant temperature and pressure conditions (approximately 832 psi at 70 Deg. F) using a closed-loop heat pump scheme analogous to a continuous solvent distillation system used in a conventional vapor degreaser under ambient pressure conditions .
A finned-tube distillation tower is positioned vertically and coaxially in the solvent holding tank within which contaminated liquid is vaporized using an external vapor transfer pump to separate the from the contaminants. The purification process uses (internal) phase change and a (external) vapor treatment train comprising coalescing, activated carbon, and particle filters. The evaporation process (liquidàgas) cools the internal holding tank fluid (liquid ) vis-à-vis heat exchange with the finned-tube distillation tower. During recompression of the purified vapor-phase into the holding tank, compression heat is added back into the internal tank fluid. Contaminants are concentrated at the bottom of the distillation tower and periodically released under pressure (tower blown down) and recovered in an external separator. The isobaric still, commercially referred to as IsoStill™, is particularly useful for Centrifugal immersion processes. During cleaning or extraction processes, liquid is continuously exchanged between the IsoStill and the centrifugal processing chamber while the liquid is continuously purified and recycled.
- 1-35. U.S. Patent 6,979,362, D. Jackson, Apparatus and Process for the Treatment, Delivery and Recycle of Process Fluids used in Dense Phase Carbon Dioxide Applications, December 25, 2005