Commercial production of ethanol in the San Luis Valley, Colorado. Final Report Page: 72 of 222
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are all good sources of water supplying 32,100 kilograms/hour (70,700 pounds/hour),
38,900 kilograms/hour (85,600 pounds/hour), and 1000 kilograms/hour (2300 pounds/hour)
respectively of recyclable water.
This results in 72,000 kilograms/hour (158,600 pounds/hour) of water that
can be treated and re-used within the plant. Since total plant make-up water demand is
only 25,000 kilograms/hour (55,000 pounds/hour), a substantial surplus quantity of water
is available when the plant is operating on potatoes.
188.8.131.52 Plant Water Consumption-Grain Feedstock
When the alcohol plant is operating with a grain feedstock, such as barley,
corn or wheat, the plant consumes more water than is available for recovery. This
result is caused primarily by the lower water content of the input feedstock.
Makeup water requirements include 49,500 kilograms/hour (108,900
pounds/hour) of water required- for grain slurry make-up and 5000 kilograms/hour
(11,100 pounds/hour) of geothermal steam input directly into the process stream in the
jet cookers. These two flow streams taken together account for 99 percent of the plant
water requirement when the plant is operating on grain feedstocks. The remaining
1 percent of water demand includes water added during pH adjustment of the slurry and
makeup water required by the CO2 gas scrubber and the fusel oil washer. The total
plant water demand is 55,000 kilograms/hour (121,200 pounds/hour).
Water is lost from the process stream primarily from the by-project
dryers where 10,600 .kilograms/hour (23,400 pounds/hour) is vented to the atmosphere.
Smaller sources of loss include the 90 kilograms/hour (200 pounds/hour) vented from the
CO2 gas scrubber and 860 kilograms/hour (1900 pounds/hour) that leaves the plant in
the form of moisture retained within the by-product, distillers dried grains (DDG).
These streams of lost water are not recoverable at the present time due to technical
and economic barriers that prevent such recovery..
Significant sources of recoverable process water include; 42,500 kilo-
grams/hour (93,400 pounds/hour) discharged to the facility waste water treatment plant
during by-product processing, 1200 kilograms/hour (2700 pounds/hour) discharged from
the flash cooling tanks, and 1000 kilograms/hour (2300 pounds/hour) recoverable from
the hydrocarbon stripping column bottoms.
This results in a total quantity of water available for reuse of 44,700
kilograms/hour (98,400 pounds/hour) or 81 percent of the total plant water demand of
55,000 kilograms/hour (121,200 pounds/hour). The remaining 19 percent of the total
water demand will have to be obtained from sources outside the plant when the plant is
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Hewlett, E.M.; Erickson, M.V.; Ferguson, C.D.; Sherwood, P.B.; Boswell, B.S.; Walter, K.M. et al. Commercial production of ethanol in the San Luis Valley, Colorado. Final Report, report, July 1, 1983; United States. (digital.library.unt.edu/ark:/67531/metadc874948/m1/72/: accessed May 27, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.