VACUUM DISTILLATION OFFERS A LOW
TEMPERATURE SOLUTION FOR SOLVENT
RECOVERY OF NMP
 
A white paper by Wastech Controls & Engineering, Inc.

Vacuum Distillation Wastewater Treatment System

Distillation is simply the act of separating water from contaminants. Water reaches its boiling point and is evaporated away, leaving the non-vaporizable substances behind. Distillation, the process of separating a liquid into different parts by evaporation and condensation, is an age-old process that may have began as early as 2000 BC. Some say that the first use of distillation occurred in China, Egypt, or Mesopotamia for medicinal purposes as well as to create balms, essences, and perfumes.

Wastech Controls and Engineering Inc.’s line of vacuum distillation systems evaporate liquids in a vacuum that reduces the boiling temperature to below 100ºF. Any materials, including water soluble solvents, can be separated from the mother liquid. Wastech Controls and Engineering Inc.’s capability to precisely control the temperature and pressure of vaporization enable the SIGMA series to recover a very broad range of reusable components in a waste stream.

Vacuum Distillation has been widely used in the refinery and energy industries for 50+ years. The technology has now become simple, robust and affordable enough to be utilized by companies that would like to recycle process materials, recover valuable solvents, and attain zero discharge. Vacuum Distillation is sometimes called Vacuum Evaporation or Cold Vaporization.

Advantages of distillation at low temperature include:

• Use of durable and economical materials.
• Ability to use low cost / low grade heat available through cogeneration schemes, thereby minimizing the energy cost component.
• No tube scaling -- which is the largest issue with high temperature distillers and atmospheric evaporators.
• Recovery of materials between 95 and 99%. This is made possible by high quality of the distillate (pharmaceutical grade) and low temperature operation. Temperature-sensitive materials are preserved in the separation process, allowing reuse of materials after recycling is completed.
• Little or no sensitivity to variation in influent quality. Consistency and robustness of vacuum distillation translates into minimal need for intake pretreatment systems.
• Minimal cleaning and maintenance. Wastech Control and Engineering Inc.’s systems only require cleaning of an hour or two per week. Cleaning involves recirculation a wash solution through the system, which the distiller then disposes of in its usual manner.

Some of the typical applications of vacuum distillation include:

• Zero-liquid-discharge wastewater, recycle/reuse and elimination of a liquid discharges.
• High value solvent recovery including typical GPC solvents such as HFIP, m-creosol, trichlorobenzene, Tetrahydrofuran (THF), dichloromethane, chloroform, xylene, and n-methyl pyrrolidone (NMP).
• BOD removal and subsequent recovery of sugars, proteins, starches and yeast as a salable products.
• Recycling of valuable chemical resources (electroplating solutions, acids, alkaline cleaners and coolants.
• Concentrating process solutions for cost-effective reclamation of precious metals, e.g. gold, silver, platinum.
• Direct replacement of atmospheric and high temperature evaporators.
• Augmentation of your primary resource recovery equipment such as ion exchange and reverse osmosis /nanofiltration systems to a zero liquid-discharge solution.
• Recovery of Water Base Inks, spent Photochemistry and Phosphates.

The SIGMA VDT Wastewater Treatment system is a "set and forget" process. It begins (1) with a fill of the vacuum chamber to a preset process level, (2) a preheat of the process fluid to the operating temperature that is preset by the operator (around 100°F), (3) Normal operation which reduces the pressure in the chamber to boil off the process fluid and inducing new process liquid as required to match the rate of evaporation, (4) collection of the distillate, and (5) periodic discharge of the process fluid at a timed interval that takes into account the required concentration of the remaining component(s). This completely automated system is PLC controlled and monitored in a closed system with a local HMI touch-screen, and can be remotely monitored using SCADA software. Alarm conditions can be communicated 24/7 to a beeper, cell phone or central control room, and historical data is maintained with data logging conforming to 21CFR Part 11.

For more information on Vacuum Distillation, visit www.wastechengineering.com/products/vacuum_distillation_systems.html