A new application for Maratek has now been installed and successfully started in a medical facility in South Carolina. The F-25 fractional distillation column has been designed to separate a mixture of ethanol, methanol, ethyl acetate and water.
The purpose is to reproof the ethanol content while maintaining a methanol concentration high enough to keep denatured alcohol status.
The customer originally approached Maratek to develop a replacement system for their current alcohol reproofing still. The existing still was close to reaching the end of its scheduled life and a replacement was needed.
A design of 25 gallons of their infeed waste material was the standard to reach, with the products measuring 20 gallons of purified ethanol and methanol and 5 gallons of wastewater to be sent to their on-site wastewater plant.
This is a key factor when making a choice of reproofing solutions. Wastewater is always generated when distilling ethanol to a higher proof and must be treated in some way as there is elevated ethanol content in this waste stream. Sending this to a municipal waste treatment plant is generally not possible, as the organic compounds from the ethanol are usually at too high of a concentration for a municipal facility to accept.
Finding a toll processor or constructing an on-site treatment plant becomes necessary and needs to be considered when a decision on reproofing is taken.
As the customer possessed this treatment facility, it made the most sense to construct a new tower at their facility as a direct replacement. With the performance parameters set, the other design parameters needed to be considered. This included spacing, height, ease of use and maintenance accessibility. These are important metrics of design and were carefully considered during implementation of the system, ensuring there is sufficient room for operators, maintenance personnel and inspections.
How the column was designed
The direct performance and design of the column was modelled in Aspen-HYSIS, a chemical engineering design software that allows for detailed tracking of process flows through the system, exact physical analysis as separation occurs in the column, and detailed design of the column size, tray placement and number, and physical requirements for flow rate and other similar parameters.
After the equipment design was completed in Aspen-HYSIS, a piping and instrumentation diagram was constructed and updated as necessary to show all the process equipment that needs to be placed and how the process piping will flow and be connected. This diagram is used by the mechanical engineering team to design a 3D buildable model in Solidworks with all of the necessary dimensions for the production team to create the base, pipe spools, wiring harnesses, and pneumatic lines.
This process resulted in a system that is approximately 60 feet tall, with a 20 foot by 20 foot base. The two major vessels, the reboiler drum and reflux drum, have volumes of 200 gallons and 300 gallons respectively to manage the flows of products and inputs.
The distillation tower has two sections within it, one with structured packing and one with regular trays to facilitate separation. This was modelled and determined to be the best concept for improving the separation of water and ethanol to produce the final product. A liquid ring vacuum system controls and maintains the vacuum level of the column to assist with distillation thermodynamics. Using vacuum-assisted distillation, it is possible to increase the efficiency of water-ethanol separation.
This project has resulted in a successful replacement column for the customer, running at a higher flow rate with equivalent purity for their recycled ethanol. The increased number of sensors and controls, compared to the still that was replaced, allow for much more independent operation of the system and increased confidence for the operators on the performance of the still.
Want to learn more about Maratek’s innovative engineering services? Contact us today. Our team of experts would love to answer any questions that you may have.