GreenField Ethanol Successfully Trials Membrane Dewatering Technology; Potential for 40% Savings in Energy Costs
|The Vaperma Siftek dewatering membrane modules in the ethanol production process. Click to enlarge. Source: Vaperma|
GreenField Ethanol, Canada’s largest ethanol producer, completed a successful trial demonstration of a new membrane dewatering technology from Vaperma that can significantly improve the efficiency of the ethanol production process.
Use of the Vaperma Siftek membrane eliminates the distillation and molecular sieve units typically in place in an ethanol plant. By replacing these, GreenField could save up to 40% in energy costs.
GreenField President and CEO Robert Gallant announced the results of the demonstration at the inauguration of Vaperma Inc.’s 22,000 square-foot research and technology centre for the development and pilot testing of gas separation membranes in Saint-Romuald, Québec.
The pilot dewatering membrane process is scheduled to go into production in the fall of 2007 with a production capacity of 20 m3 per day—the equivalent of about 6% of Greenfield’s Chatham fuel ethanol plant production, according to Gallant.
A Vaperma Siftek membrane module consists of thousands of polymeric hollow fibers—extruded using a wet/dry-phase—embedded into a thermoset resin that is permanently bonded to a fixture ring seal to form a removable cartridge. The cartridge is inserted into a pressure vessel made of carbon steel, stainless steel, or ABS plastic, depending upon the application.
|The Vaperma Siftek membrane works with any water-vapor gas blend. Source: Vaperma|
The membrane works with any water-vapor gas blend. Each fiber consists of two layers with different properties: an inner, active layer where separation occurs, and an outer porous sublayer that provides mechanical support and draws the water vapor out. Both layers together are no more than 0.2mm thick.
When a wet, pressurized gas comes into contact with the membrane, water molecules readily move into the hydrophilic active layer. Water vapor diffuses across the boundary, and is drawn out of the outer layer.
In ethanol production, the ethanol-water mixture resulting after evaporation has a 40:60 ethanol to water vapor content. This blend flows into a first Siftek module, where 90% of the water vapor is removed, pumped out and condensed, and sent back for re-use in production. The remaining gas flows to a second series of modules, where the remaining water is removed, resulting in the 99+% fuel-grade ethanol.
Water vapor is carried away in the permeate stream at low pressure. The separation unit typically operates under a total pressure of 1 to 1.5 bar within the capillary tubes and a vacuum outside of the membranes.
Vaperma attributes the higher selectivity and permeance of water compared to ethanol are attributed to the unique polymer formulation and the membrane fabrication process.
GreenField Ethanol began discussions with Vaperma two years ago about installing a demonstration project at its Tiverton, Ontario ethanol plant. This project proved to be the first large-scale demonstration in North America of membrane technology for the dewatering of ethanol.
Researchers in Japan are among those who are also exploring the use of membrane technology for dewatering ethanol. (Earlier post).
GreenField Ethanol, formerly Commercial Alcohols, is Canada’s leading ethanol producer. The company produces 250 million liters (66 million gallons US) a year of corn-based fuel ethanol at its plants in Chatham and Tiverton, Ontario and Varennes, Québec. Two more plants are under construction in Hensall and Johnstown, Ontario, and will be operational in 2008. GreenField Ethanol will be one of the top producers in North America with five operating plants, producing more than 700 million liters (185 million gallons US) of ethanol per year by 2008. GreenField’s Ethanol is available at more than 1,500 gas stations across Canada.
(A hat-tip to John!)