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Premium
Process Equipment |
Ethanol Industry prepares for the Energy Bill
The congress
is near sending the Energy Bill to the President of the USA for signing.
Included in the current version are significant incentives for the ethanol
fuel industry. It is expected that most of the planned grass roots plants
will begin construction sometime after the bill is signed. The current
technology used for fuel ethanol production is traditional distillation.
This process is energy intensive and profits are directly related to the
efficient use, and recovery, of heat. Proper heat exchanger selection
provides both the required duty and reliability to run the plant effectively.
PPE has a portfolio of products that are incorporated into many parts
of a common fuel ethanol plant. Most ethanol in the USA is produced from corn, although many sugary starches can be used. The corn starch is transformed into sugars and then fermented into an alcohol. The alcohol is contained in a beer and is separated by distillation. The fermentation mash is held at the optimum temperature by circulation through an external heat exchanger. As this mash is a slurry of water, alcohol, fibers, and corn bits, a Spiral Heat Exchanger or a Wide Gap Pressure Plate, type unit is often the equipment of choose. The large channel spacing, and ability to handle particulates is very important. Preheating the distillation feed requires the same types of equipment, especially if heated with distillation bottoms. Cleaning these heat exchangers is accomplished through large door-like heads allowing complete access to the heat transfer surface. The Whole Stillage and Thin Stillage used in producing the feed supplement byproduct, distillers dried grains, are both very challenging flows for heat exchangers. Both the Wide Gap Pressure Plate and the Spiral Plate heat exchangers are options for these duties. The ability of these two types of heat exchangers to handle the particle laden fluids, and be cleanable is unique. The distillate is condensed, and normally this is the end of the first of several stages required to get the purity and efficiency needed. The condensate is very clean, but fuel ethanol is produced in huge volumes, and the condensing surfaces are very large. PPE recommends the Plate-Shell heat exchanger for this application as very large surfaces are placed in a compact shell; the welded construction makes it ideal for condensing at vacuum conditions. Vacuum condensing lowers the evaporation temperature of the distillate, reducing the energy requirement. Vacuum condensing requires the condenser to be of welded construction, as gaskets are notorious for leaks under vacuum. The Plate-Shell is also the most cost effective device for vacuum condensing. PPE has several types of welded plate heat exchangers; all of them are applicable to some part of the modern ethanol plant. Applications: Mash heater/cooler
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