• TABLE OF CONTENTS
HIDE
 Chapter
 Front Cover
 Introduction
 Outputs
 Selection of raw materials
 General observation on plant...
 Discussion of the flow diagram
 Conclusion and additional...
 Back Cover






Group Title: Florida Cooperative Extension Service circular 482
Title: Producing ethanol by a community distillery for use as a fuel
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00049268/00001
 Material Information
Title: Producing ethanol by a community distillery for use as a fuel
Series Title: Circular Florida Cooperative Extension Service
Physical Description: 11 p. : ill. ; 28 cm.
Language: English
Creator: Le Grand, Ferdinand
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville
Publication Date: 1980
 Subjects
Subject: Alcohol as fuel   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: Ferdinand leGrand.
General Note: Cover title.
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00049268
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: oclc - 08851496

Table of Contents
    Chapter
        Unnumbered ( 1 )
    Front Cover
        Page 1
    Introduction
        Page 2
    Outputs
        Page 2
    Selection of raw materials
        Page 3
    General observation on plant design
        Page 3
    Discussion of the flow diagram
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
    Conclusion and additional observations
        Page 9
        Page 10
        Page 11
    Back Cover
        Page 12
Full Text





HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida







Circular 482
May, 1980


*


i


I 1/1o"


it-
*^
v^"


F. leGrand









Producing Ethanol by a Community Distillery
For Use as a Fuel

F. leGrand*


Introduction
The term "synfuel" refers to substitutes for
petroleum products which are derived from organic
compounds other than crude oil. They include liquid
fuels produced from organic compounds in biomass,
such as grains, potatoes, wood and other wastes
mostly fibrous in nature. Biomass is abundant and
renewable; its full potential as a future energy
source for the United States is still unknown at pre-
sent.
Recently, alcohol production has received par-
ticular attention for its relatively simple conversion
of carbohydrates into a usable fuel. The processing
technique to convert simple sugars or sucrose into
ethanol is uncomplicated:
After extraction of the juice containing these
types of sugars, the liquid is heated to be sterilized
and subsequently is cooled before the introduction
of a selected yeast strain. During fermentation, the
sugars present in water-soluble form are converted
into ethanol of a low concentration and CO2 gas. The
resulting fermentation mash is distilled in a strip-
ping column to yield a clear solution containing 40
percent to 60 percent alcohol. This liquid is further
concentrated in a rectifying column to 190 proof (95
percent) alcohol, or to a 99 percent or higher concen-
tration when using azeotropic distillation with the
addition of a third liquid as an entrainer.
Alcohol can also be produced from larger car-
bohydrate molecules such as starch in grains or
tubers. These polysaccharides must first be con-
verted into simple sugars before the solution can
serve as a feedstock for fermentation and subse-
quent distillation. After grinding the grain is
steeped in hot water to gelatinize, and the mash is
then heated to about 350F. momentarily.
This simple cooking process makes the starch in
the grain particles suitable for easy conversion into
simple sugars. Conversion is achieved by adding a
selected enzyme or by hydrolyzing with a strong
acid. In the latter case, the pH of the resultant solu-
tion must be readjusted with the addition of a base
such as calcium hydrozide.
Cooling of intermediate products in processing to
prescribed temperatures is mandatory before
adding enzymes to avoid the deactivation of the en-
zymes. Likewise, certain ranges for temperature and
pH must be maintained during the fermentation

*Associate professor, Department of Agronomy,


cycle to optimize alcohol formation in the solution.
Nutrient levels must also be kept at predetermined
levels.

Outputs
Alcohol with a concentration of 90 percent to 93
percent can be produced when using a stripping and
a rectifying column for distillation. Such a mixture
could be used directly to power a tractor or other
farm vehicle, providing that certain modifications
are made to the carburetor. Consequently, these
modified engines can only be fueled by a mixture of
highly concentrated alcohol. Some engines, not nor-
mally placed in tractors and road vehicles, are
specifically designed with a differentiation in com-
pression ratio so that they can be fueled with a con-
centration of alcohol for 60 percent of higher.
When cars or tractors are fueled with gasoholl" a
mixture of 9:1 of lead-free gasoline and anhydrous
alcohol, an exemption of 4 cents per gallon of
gasohol is received in federal road tax. Therefore,
anhydrous ethanol is worth 40 cents per gallon in
tax exemption alone, and consequently the direct
utilization of ethanol as fuel for road vehicles or
tractors must be regarded as monetarily disadvan-
tageous at present.
Anhydrous ethanol has a lower caloric value per
unit of volume than gasoline, and therefore a unit of
gasohol appears to produce less power than the
same unit of gasoline. In reality, gasohol delivers
about the same mileage per gallon as gasoline, since
the high octane rating of alcohol elevates the octane
rating of gasohol and also reduces the air intake
needed for the combustion of anhydrous alcohol.
A mixture of alcohol and gasoline may separate in
the presence of 2 percent or more water. For this
reason anhydrous alcohol (measuring 99 percent or
higher in ethanol concentration) is used for mixing
with lead-free gasoline into gasohol. The problem of
separation in the fuel tank of an automobile or in the
tank at the filling station can become critical, as
lead-free gasoline alone may contain a fair amount of
water. The production of anhydrous alcohol requires
an additional processing step beyond rectification.
For safety, care should be exercised when opening a
fuel tank filled with gasohol, as the vapor pressure
of this commodity is greater than the vapor
pressure of straight gasoline.


University of Florida, Gainesville, Florida 32611.









Producing Ethanol by a Community Distillery
For Use as a Fuel

F. leGrand*


Introduction
The term "synfuel" refers to substitutes for
petroleum products which are derived from organic
compounds other than crude oil. They include liquid
fuels produced from organic compounds in biomass,
such as grains, potatoes, wood and other wastes
mostly fibrous in nature. Biomass is abundant and
renewable; its full potential as a future energy
source for the United States is still unknown at pre-
sent.
Recently, alcohol production has received par-
ticular attention for its relatively simple conversion
of carbohydrates into a usable fuel. The processing
technique to convert simple sugars or sucrose into
ethanol is uncomplicated:
After extraction of the juice containing these
types of sugars, the liquid is heated to be sterilized
and subsequently is cooled before the introduction
of a selected yeast strain. During fermentation, the
sugars present in water-soluble form are converted
into ethanol of a low concentration and CO2 gas. The
resulting fermentation mash is distilled in a strip-
ping column to yield a clear solution containing 40
percent to 60 percent alcohol. This liquid is further
concentrated in a rectifying column to 190 proof (95
percent) alcohol, or to a 99 percent or higher concen-
tration when using azeotropic distillation with the
addition of a third liquid as an entrainer.
Alcohol can also be produced from larger car-
bohydrate molecules such as starch in grains or
tubers. These polysaccharides must first be con-
verted into simple sugars before the solution can
serve as a feedstock for fermentation and subse-
quent distillation. After grinding the grain is
steeped in hot water to gelatinize, and the mash is
then heated to about 350F. momentarily.
This simple cooking process makes the starch in
the grain particles suitable for easy conversion into
simple sugars. Conversion is achieved by adding a
selected enzyme or by hydrolyzing with a strong
acid. In the latter case, the pH of the resultant solu-
tion must be readjusted with the addition of a base
such as calcium hydrozide.
Cooling of intermediate products in processing to
prescribed temperatures is mandatory before
adding enzymes to avoid the deactivation of the en-
zymes. Likewise, certain ranges for temperature and
pH must be maintained during the fermentation

*Associate professor, Department of Agronomy,


cycle to optimize alcohol formation in the solution.
Nutrient levels must also be kept at predetermined
levels.

Outputs
Alcohol with a concentration of 90 percent to 93
percent can be produced when using a stripping and
a rectifying column for distillation. Such a mixture
could be used directly to power a tractor or other
farm vehicle, providing that certain modifications
are made to the carburetor. Consequently, these
modified engines can only be fueled by a mixture of
highly concentrated alcohol. Some engines, not nor-
mally placed in tractors and road vehicles, are
specifically designed with a differentiation in com-
pression ratio so that they can be fueled with a con-
centration of alcohol for 60 percent of higher.
When cars or tractors are fueled with gasoholl" a
mixture of 9:1 of lead-free gasoline and anhydrous
alcohol, an exemption of 4 cents per gallon of
gasohol is received in federal road tax. Therefore,
anhydrous ethanol is worth 40 cents per gallon in
tax exemption alone, and consequently the direct
utilization of ethanol as fuel for road vehicles or
tractors must be regarded as monetarily disadvan-
tageous at present.
Anhydrous ethanol has a lower caloric value per
unit of volume than gasoline, and therefore a unit of
gasohol appears to produce less power than the
same unit of gasoline. In reality, gasohol delivers
about the same mileage per gallon as gasoline, since
the high octane rating of alcohol elevates the octane
rating of gasohol and also reduces the air intake
needed for the combustion of anhydrous alcohol.
A mixture of alcohol and gasoline may separate in
the presence of 2 percent or more water. For this
reason anhydrous alcohol (measuring 99 percent or
higher in ethanol concentration) is used for mixing
with lead-free gasoline into gasohol. The problem of
separation in the fuel tank of an automobile or in the
tank at the filling station can become critical, as
lead-free gasoline alone may contain a fair amount of
water. The production of anhydrous alcohol requires
an additional processing step beyond rectification.
For safety, care should be exercised when opening a
fuel tank filled with gasohol, as the vapor pressure
of this commodity is greater than the vapor
pressure of straight gasoline.


University of Florida, Gainesville, Florida 32611.








Selection of Raw Materials
Grains have the advantage of easy storage for
processing into ethanol year-round. For Florida,
grain may not be the feedstock of choice, but it was
selected to illustrate the process. Cellulose, for ex-
ample, may be the cheapest feedstock for conversion
into glucose; however, appropriate technology for
using this feedstock is not now available. After dry-
ing, the grain size of corn, sorghum, rice or wheat
must be reduced with a roller or hammermill to
crush the epidermis and expose the starch-
containing tissue for subsequent conversion into
simple sugars. A hammermill may be preferred for
this purpose as this type of equipment can process
all types of grains, although a multiple roller mill
specifically suited for some types of grain will
reduce required energy input and maintenance
costs.
Grain residues left after distilling contain
valuable minerals and protein for use in animal feed
rations. These materials in a concentrated wet form
can be directly utilized by a feed lot adjacent to the
distillery, or can be dried for sale as distillers grains
or distillers solids.
Parts of herbaceous plants which are high in starch,
such as tubers from Irish potatoes, sweet potatoes,
and cassave, and parts which are high in simpler
sugars, such as sugar beets or carrots, may also be
used as suitable materials for alcohol production.
These crops have to be pre-treated in a different
manner than that described for grains to recover the
starch or sugars in suitable form for ultimate
fermentation and distillation.
Sweet sorghum or sugar cane are desirable
feedstocks; however, a milling tandem which is ex-
pensive must be added. On the other hand, the
fibrous residue can be used as a fuel for distillation
and drying of by-product. A suitable manner for the
pre-treatment of these commodities will be in-
vestigated for publication in the future.
One of the main problems with feedstock derived
from herbaceous plants is that these commodities
are harvested seasonally. Thus, it is necessary to
store the carbohydrates in a durable form for
retrieval as a fermentable feedstock year-round.
Residues obtained after fermentation have only a
very limited value as animal feed.


General Observation on Plant Design
The community distillery was designed as a
thermally efficient facility. Nearly all applied heat is
recycled during processing, with the exception of
the cooling water, which rejects only a low energy
rate per unit used.
The distillery should be located at the center of
the community to make the hauling of raw materials


as short as possible. Moreover, the distillery should
be located near a small pond, of about 3 acres. The
pond will supply cooling water that should be re-
cycled in a closed system to avoid thermal pollution.
The design included here provides an output of 25
gallons of 190 proof ethanol per hour. This small-
sized plant may be useful as a cooperative commu-
nity distillery where participating members could
process a part of their grain crop into alcohol and
feed. Such an arrangement would permit the
distiller's grain to be fed in wet form locally, thus
saving much fuel needed for drying the residue. A
community distillery may permit each grower
greater flexibility for the use or sale of grain crops in
Florida. Also, the grower can find a market for grain
of inferior quality, or even grain which is affected by
aflatoxin; however, the residue from the latter can-
not be used as a feed. Hence, a distillery may cut
financial losses from grain production in some
years.
The flow-diagram allows for a yearly production
of 120,000 gallons of 190 proof ethanol, assuming a
production during 20 hours per day, 5 days per week
and 48 weeks per year. The total input required is
about 50,000 bushels of grain annually, which after
processing will supply about 425 tons of dry
distillers grain per year. The flow-diagram has been
over-designed, meaning that the calculated pipe
sizes and capacity of equipment should allow about
25 percent increase in production capacity over the
stated rate.
The chosen and reported method for processing is
the conversion of starch into simple sugars with the
use of enzymes, instead of hydrolyzing the starch
with a strong acid and then neutralizing it with
calcium. The latter approach could increase the
sulphur and calcium content of the resulting feed
by-product significantly. The needed enzymes are
purchased from specialized chemical companies as
on-site production of malts from barley and the like
will not be economically feasible for the suggested
small distillery plant.
Recovery of 140 pounds of CO, per hour emitted
by the distillery probably is not feasible for a small
plant.
A boiler of 55 to 60 H.P. rating on the plate,
delivering 200 pounds per inch2 pressure, must sup-
ply the needed energy for ethanol processing. The
needed energy of about 1 million B.T.U. per hour is
supplied from burning wood chips, which contain
about 4,000 B.T.U. per pound when wet. Hence, the
boiler will require a supply of about 250 pounds of
chips per working hour.
Starch which is transformed into a feedstock for
fermentation is likely to be deficient in nitrogen and
certain minerals when fed into the fermenters.
Normally, nitrogen is added in the form of am-
monium sulphate. For a small community distillery








Selection of Raw Materials
Grains have the advantage of easy storage for
processing into ethanol year-round. For Florida,
grain may not be the feedstock of choice, but it was
selected to illustrate the process. Cellulose, for ex-
ample, may be the cheapest feedstock for conversion
into glucose; however, appropriate technology for
using this feedstock is not now available. After dry-
ing, the grain size of corn, sorghum, rice or wheat
must be reduced with a roller or hammermill to
crush the epidermis and expose the starch-
containing tissue for subsequent conversion into
simple sugars. A hammermill may be preferred for
this purpose as this type of equipment can process
all types of grains, although a multiple roller mill
specifically suited for some types of grain will
reduce required energy input and maintenance
costs.
Grain residues left after distilling contain
valuable minerals and protein for use in animal feed
rations. These materials in a concentrated wet form
can be directly utilized by a feed lot adjacent to the
distillery, or can be dried for sale as distillers grains
or distillers solids.
Parts of herbaceous plants which are high in starch,
such as tubers from Irish potatoes, sweet potatoes,
and cassave, and parts which are high in simpler
sugars, such as sugar beets or carrots, may also be
used as suitable materials for alcohol production.
These crops have to be pre-treated in a different
manner than that described for grains to recover the
starch or sugars in suitable form for ultimate
fermentation and distillation.
Sweet sorghum or sugar cane are desirable
feedstocks; however, a milling tandem which is ex-
pensive must be added. On the other hand, the
fibrous residue can be used as a fuel for distillation
and drying of by-product. A suitable manner for the
pre-treatment of these commodities will be in-
vestigated for publication in the future.
One of the main problems with feedstock derived
from herbaceous plants is that these commodities
are harvested seasonally. Thus, it is necessary to
store the carbohydrates in a durable form for
retrieval as a fermentable feedstock year-round.
Residues obtained after fermentation have only a
very limited value as animal feed.


General Observation on Plant Design
The community distillery was designed as a
thermally efficient facility. Nearly all applied heat is
recycled during processing, with the exception of
the cooling water, which rejects only a low energy
rate per unit used.
The distillery should be located at the center of
the community to make the hauling of raw materials


as short as possible. Moreover, the distillery should
be located near a small pond, of about 3 acres. The
pond will supply cooling water that should be re-
cycled in a closed system to avoid thermal pollution.
The design included here provides an output of 25
gallons of 190 proof ethanol per hour. This small-
sized plant may be useful as a cooperative commu-
nity distillery where participating members could
process a part of their grain crop into alcohol and
feed. Such an arrangement would permit the
distiller's grain to be fed in wet form locally, thus
saving much fuel needed for drying the residue. A
community distillery may permit each grower
greater flexibility for the use or sale of grain crops in
Florida. Also, the grower can find a market for grain
of inferior quality, or even grain which is affected by
aflatoxin; however, the residue from the latter can-
not be used as a feed. Hence, a distillery may cut
financial losses from grain production in some
years.
The flow-diagram allows for a yearly production
of 120,000 gallons of 190 proof ethanol, assuming a
production during 20 hours per day, 5 days per week
and 48 weeks per year. The total input required is
about 50,000 bushels of grain annually, which after
processing will supply about 425 tons of dry
distillers grain per year. The flow-diagram has been
over-designed, meaning that the calculated pipe
sizes and capacity of equipment should allow about
25 percent increase in production capacity over the
stated rate.
The chosen and reported method for processing is
the conversion of starch into simple sugars with the
use of enzymes, instead of hydrolyzing the starch
with a strong acid and then neutralizing it with
calcium. The latter approach could increase the
sulphur and calcium content of the resulting feed
by-product significantly. The needed enzymes are
purchased from specialized chemical companies as
on-site production of malts from barley and the like
will not be economically feasible for the suggested
small distillery plant.
Recovery of 140 pounds of CO, per hour emitted
by the distillery probably is not feasible for a small
plant.
A boiler of 55 to 60 H.P. rating on the plate,
delivering 200 pounds per inch2 pressure, must sup-
ply the needed energy for ethanol processing. The
needed energy of about 1 million B.T.U. per hour is
supplied from burning wood chips, which contain
about 4,000 B.T.U. per pound when wet. Hence, the
boiler will require a supply of about 250 pounds of
chips per working hour.
Starch which is transformed into a feedstock for
fermentation is likely to be deficient in nitrogen and
certain minerals when fed into the fermenters.
Normally, nitrogen is added in the form of am-
monium sulphate. For a small community distillery








it is suggested to add chicken manure to the
feedstock. The manure is ideal since chickens are fed
a perfectly balanced diet. The manure slurry can be
prepared and roughly filtered. This filtrate must be
sterilized by admitting steam at 225 F. (equivalent
to pressure of 5 lbs/inch2) from a perforated pipe into
a small, closed vessel. After cooling, the filtrate is
admitted to the feedstock stream with a small ad-
justable feeder pump. The described arrangement is
omitted from the flow diagram for reason of
simplicity.
The suggested flow diagram shows a continuous
process, as this type is more easy to manage with a
limited labor force than a batch process. Also, the
small vessels needed in a continuous process, reduce
initial capital costs and avoid radiation heat losses
from vessels and pipes during processing. An ad-
vantage of batch type fermentation is that con-
tamination by foreign bacteria can easily be con-
trolled.
A beamed steel building with four floors is recom-
mended for the suggested flow design. This design
will permit gravity flow and reduce the need for
pumping of intermediate materials. The high-
viscosity mash is pumped once to the top of the
building from where it descends through different
processing steps by gravity to the ground floor. A
special slab outside the main building should house
the small boiler and the supply of wood chips for
fuel.
Most of the equipment is simple in design. Tanks
which need alteration may be handled at any small-
town machine shop. Power for the community
distillery must be purchased from the local utility
company.


Discussion of the Flow Diagram
1. This discussion assumes that grains rather than
herbaceous plants will be used. Either ground grains
are obtained from a local feed mill, or a hammermill
must be installed at the community distillery. The
installation of the hammermill is excluded from the
flow diagram. The reduced grain (the degree of
fineness is not critical for further processing) is ad-
mitted by a cyclone and airveyor to a U-shaped mix-
ing tank. Two tanks are used for mixing. This is the
only batch operation in the flow diagram, as a con-
tinuous operation would require sophisticated in-
strumentation which is not justified for a small-
sized community distillery.
2. The tank is filled to a pre-determined level with
water, the stillage (once-fermented and distilled
mash) is added to a second pre-determined level, and
finally cracked grain is added to a third level,
finishing the particular batch in the tank with 10
bushels of grain. Each vessel holds enough mash for


one hour of processing time; the two vessels are used
alternatively for filling and discharging.
3. Water and stillage are applied at a combined
rate of 20 gallons of liquid per bushel of grain. Con-
densed water from processing at 1400F. is piped
from the calandria of the third vessel of the vacuum
evaporator effect for mixing the grain. About 20
percent of the stillage is recirculated for mixing with
the grain. The stillage is also piped from the third
vessel of the evaporator, but not from the vapor
space. This stillage contains a large quantity of
perished yeast cells, which contain protein that is
beneficial to the fermentation cycle later on. At the
same time, this stillage has a pH of about 4.2,
therefore adjusting the fresh batch of mash to a pH
of 5.3-5.4. This is the optimum pH range for the en-
zymatic conversion of starch into a fermentable
feedstock and for the fermentation of this stock.
4. About 10 percent of the total quality of en-
zymes needed in processing may be added to the
mash in the mixing tank, to aid with fluidizing the li-
quid. The temperature must not exceed 1400F.
because the amylase enzyme will become inac-
tivated. A fast reacting commercial enzyme should
be used. The mixing tanks are also provided with
steam sparges (at a pressure of 5 lbs/inch2) to in-
crease the temperature if needed. The tanks are
equipped with stirrers for 30 to 35 r.p.m.
5. A valve with rotameter is placed in the outlet of
the mixing tank to calibrate the average flow of the
mash at 5.25 gallons per minute, the intended pro-
cessing rate for 10 bushels of grain per hour. This
calibration will place the rest of the distilling plant
at the same hourly processing rate.
The mash is pumped to the cooker vessel by a
triple plunger pump or any other type of pump
which is capable of delivering a pressure of 200
lbs/inch2. A trap with a screen should be placed in
the outlet of the mixing tank to prevent the entry of
foreign objects which could damage the pump. An
airchamber is placed near the outlet of the pump to
equalize the pressure of the mash entering the
cooker. In addition, a safety valve with 4 11/" line is
placed between the suction and delivery lines of the
pump to prevent accidents due to the rather high
pressure involved.
6. The pumped mash enters the cooker vessel
through a jet heater, which maintains a pressure of
185 lbs/inch2 within the vessel. Simultaneously with
the mash stream, saturated steam under 185
lbs/inch2 pressure is admitted from a steam header.
The mash is instantaneously heated to 380F. (the
equivalent temperature to 185 lbs/inch2 of saturated
steam). The cooker vessel is small (about 10 gallons),
allowing for only 2 minutes of retention time at the
elevated temperature. By this time, the mash has







the proper consistency for starch present to be con-
verted into a fermentable feedstock by selected en-
zymes.
The heated mash leaves the small cooker vessel by
means of an anticoking valve which has a ventury
type throat throttled by a tapered plug. With proper
instrumentation, this valve also maintains a con-
stant level in the cooker vessel. Temperature,
pressure and level of mash are thus automatically
controlled in the cooker. The vessel is also equipped
with gauges for temperature and pressure, a safety
valve and wash-out lines which are not shown on the
diagram.

7. After leaving the cooker vessel, the mash is
flashed into the first flash cooler, where the pressure
is instantaneously reduced from 185 lbs/inch2. The
temperature of the mash drops correspondingly,
from 380F. to 2250F., resulting in 250 pounds of
saturated steam being released per hour at 5
lbs/inch2 pressure. This steam is then reutilized by
open injection into the rectifying column.
The mash can be blown into the first flash vessel
through a series of horizontal pipes which have a
number of properly sized holes in the bottom. The
pipes are closed at the end. An automatic level valve
should regulate and maintain a constant level of
mash in the flash tank.
8. The dimensions of the flash tank are not critical.
The diameter should be at least one foot, and the
distance between the maintained level of the mash
and the outlet for the flashed steam should be at
least 6 feet. At the steam outlet a baffle arrange-
ment, similar to the one shown for the detail of the
evaporator, should be installed to prevent the en-
trainment of mash particles. The baffle arrangement
is not on the flow diagram.

9. The mash from the first flash cooler is blown in-
to a second flash cooling vessel. The liquid cools in-
stantly there, from 2250F. to 145F., due to a drop
in pressure from 5 lbs/inch2 to about 23 inches of
vacuum. The vacuum in the second flash vessel is
maintained by a barometric condenser, which is
detailed in the flow diagram. The vapor flashed from
this second vessel is of low energy value, and is
necessarily lost with the cooling water ejected by
the condenser. The mash must be pumped from the
second vessel due to the vacuum. Pump action is
controlled by a float valve to keep the level constant
in the second flash cooling tank.
Two small tanks with valves at the inlet and
outlet may be used as an alternative to pumping
mash kept under a vacuum. The inlet valve is open
and the outlet valve closed during -filling, while the
reverse takes place during emptying of the tank
with compressed air. The tanks are used alternately;


the additional air admitted for the pumping action
will certainly decrease the degree of vacuum which
can be maintained in the vessel and hence, will place
an added load on the barometric condenser. When
installing a pump, the vessel should be placed suffi-
ciently high in the building to cause a flow of the
mash by gravity to the pump inlet, which is placed
on the ground floor.
Enzymes may be admitted with a small ad-
justable feeder pump at the suction line of the pump
to secure thorough mixing throughout the mash.
The temperature of the pumped mash is
automatically maintained at 140F. to 1450F., by
virtue of the vacuum in the flash vessel. This
temperature is ideally suited for the optimum effec-
tiveness of most commercial enzymes.
The steam and vapor flashed by the first and se-
cond cooling vessels will increase the sugar concen-
tration of the mash to more than 12 percent, the
maximum concentration for optimal production of
alcohol during the fermentation process. Hence, this
concentration is reduced with the addition of .7
gallons of water per minute. The water is obtained
as condensate from the third calandria of the triple
evaporation. It is sterile and has a temperature of
1400F. to 1450F. The exact quantity of water is not
critical, and can be supplied from a pipe with a cons-
tant pressure head and an orifice calibrated at 0.7

gallons per minute for the chosen pressure head.

10. Fermentation optimally takes place below
85F. Therefore, the mash, with starch now con-
verted into suitable single sugars, must be addi-
tionally cooled. Cooling can take place in a simple
shell and tube cooler using ambient water; about 20
square feet of cooling surface should suffice for the
hourly capacity specified in the flow diagram. The
pump from the second flash cooler moves the mash
through the shell and tube cooler for entry into the
first fermenting vessel, allowing sufficient retention
time for the added enzyme to react.

11. The time from the initial mixing of the grain
with water and stillage until the passing of the mash
through the tube and shell cooler is estimated at five
to eight minutes.

12. The cooled mash, in which starch has been con-
verted into single sugars, is now entering the first
fermenter to be retained in that vessel for four
hours. The first fermenter has an automatic
overflow pipe for the mash to enter the second
fermenter vessel. Both vessels may be made from
fiberglass.
The continuous fermentation process requires
about eight hours, with four hours of retention time
in each fermenter. The fermentation process is
anaerobic, thus requiring that the escaping CO,











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Design by F. le Grand
Drawing by B. Chandler







passes through a liquid trap (not shown in the flow
diagram). The mash should exit from the second
fermenting vessel with an ethanol concentration of
about 12 percent and with about 98 percent of the
available sugars fermented into alcohol.
13. Optimum alcohol formation in a continuous
process can be achieved only when a cell count of
100 million per milliliter is maintained in the mash
at all times. Although some yeast is formed in the
mash under anaerobic conditions during fermenta-
tion, this count may fall below this required op-
timum. Hence, additional yeast cells are multiplied
aerobically with a small system (Vogelbusch in the
detailed diagram) and added to the first fermenter
vessel. Yeast cells also should be added at the start
of every run after a prolonged shut-down of the
facility, for instance, after the weekend. Also,
sterilized sludge from chicken manure is added to
the fermenter at the rate of one pound of nitrogen
per 40 bushels of grain processed. Yeast cells and
nutrients can be added to the fermenter with a small
adjustable feeder pump at rates to be established
experimentally. The fermentation tanks are cooled
from the outside with water to dissipate the heat
generated during the fermentation process, and to
maintain the temperature of the fermenting mash
below 850F.
14. The fermented mash leaving the second vessel
is passed through the condenser of the rectifying
column where this liquid serves as a cooling
medium, thus being heated itself in the process. The
heated mash now enters the triple vacuum
evaporator effect.
15.The triple effect vessels have a dual function:
they act as a stripping still, and simultaneoulsy con-
centrate the residue (distiller's solids) to 600 to 650
Brix*. Normally a stripping still is heated through
open sparges with steam at 5 lb/inch2 pressure, and
yields an ethanol solution of about 50 percent after
condensing. With open sparges this alcohol strip-
ping will dilute the distiller's solids, leaving the
residues with as high as 90 percent moisture. This
moist material is unsuited for direct feeding to beef
animals. Therefore, the diluted distiller's solids
must be concentrated to about 60 percent to 65 per-
cent dry matter before the product can be
economically transported and utilized as an animal
feed. By using a triple vacuum evaporator effect in-
stead of a stripping still, a possible 25 percent in-
crease in fuel economy may be achieved.
16. Steam at 5 lbs/inch2 pressure enters the calan-
dria of the first vessel, while the heated mash enters
the evaporating space of the same first vessel. The
low pressure steam admitted is condensed in. the
calandria space, and is reutilized as boiler feedwater.
While condensing, this steam will release heat which
is conducted through the pipes of the calandria.

*A measure of density equivalent to specific gravity.


Subsequently the mash in the space above will con-
centrate, and vapor will exit at the top of the vessel
for condensation in the calandria of the second
vessel. The condensate is a clear liquid containing
about 25 percent ethanol. The vapor generated in
the calandra of the second vessel is in turn con-
densed in the calandria of the third vessel; this con-
densate may contain about 1 percent ethanol. The
vapor generated in the third vessel is removed by
the vacuum exerted from the barometric condenser.
The vapor is then condensated by cooling water ap-
plied to the condenser. The condensate received in
the calandria of the second vessel is collected by
pump. This liquid, containing about 25 percent
ethanol, is sent to the rectifying column for further
concentration into 95 percent (190 proof) alcohol.
The condensate from the calandria of the third
vessel, still containing about one percent of ethanol,
is returned to processing for the mixing of grain.
Mash is entering the first vessel of the triple effect
in a continuous stream and exiting from the third
vessel after having been stripped of alcohol and a
large portion of its water. The distiller's solids are
recovered from the liquid space of the third vessel at
60 percent to 65 percent dry matter.
17. As previously mentioned, the condensate
which exits from the calandria of the third vessel
contains about 1 percent ethanol, and this product is
returned to processing for mixing with grain. This
alcohol will escape with the flashed steam from the
first flash cooler. The flashed steam and the dilute
alcohol is directly injected through open sparges in-
to the rectifying column, where the alcohol is
recovered. Therefore, the closed system for utilizing
all available energy is apparent.
18. Calcium and magnesium will deposit inside the
calandria tubes in the triple effect. Scaling needs to
be removed at regular intervals by boiling with a
concentrated solution of sodium hydroxide and then
washing with a dilute solution of sulphuric acid.
Cleaning is necessary in order to retain the heat ex-
change capacity and subsequent evaporation rate
per square foot of heating surface. The ar-
rangements needed for boiling with the cleaning
chemical are not shown on the flow diagram.
19. A detail for the vessel of the triple effect is sup-
plied. The calandria contains 39 copper tubes, with a
total of 78 square feet in heating surface. The tube
plates should be V2 inch thick to accommodate for the
proper rolling-in of the tubes. Proper spacing above
the tube plate is critical to avoid an entrainment of
the mash into the calandria of the next vessel.
Preferably the vessels should be made from mild
steel with sufficient thickness to withstand a
vacuum of 26 inches per square inch. The mash
space should have a fairly large manhole to facilitate
the scraping of the tube's inside surfaces with a rod







and wire brush, if scraping is required to remove
durable scaling. Also, one or two sightglasses
should be provided for each vessel.
The diameter of the vessel and the length of the
tubing is not critical. The calandria may have a
larger diameter with shorter tubes, as long as a
heating surface of 75 square feet is provided for each
vessel. The arrangement for the barometric con-
denser which supplies the needed vacuum for the
triple effect and the second flash cooling vessel is
provided in the flow diagram. The triple evaporator
effect must be placed at least 10 feet above ground
level, and preferably higher to faciliate the removal
of hot condensate from the calandrias of the vessels
without causing a vapor lock at the centrifugal
pumps.
20. The condensate from the second calandria,
which contains about 25 percent ethanol, is directly
pumped to the rectifying column. The use of a bub-
blecap column is preferred over a so-called packed-
column. The latter is often difficult to manage and
often "leakage" occurs inside the packing of the
column. The bubblecap column can be made from
steel as the feed has almost a neutral pH, consisting
of condensed liquids which are unlikely to form any
incrustations inside the column. The bubblecap
plates should be positioned 10 to 12 inches apart to
avoid possible liquid entrainment. The height of the
entire column is about 24 feet. The diameter of the
column should be about 16 inches to achieve the in-
tended rectifying capacity for 25 gallons of 190 pro-
of ethanol per hour. Four bubblecaps, each meas-
uring three inches in diameter, per tray should suf-
fice to obtain satisfactory rectifying results. The
rectifying column is energized by two sources of
steam: The flashed vapor from the first flash cooling
vessel, which is admitted through the open sparges,
plus additional steam at 5 lbs/inch, pressure, which
is supplied to a closed system of a calandria or a coil.
Condensate from the latter is recirculated as boiler-
feed water.
21. The rectified alcohol vapor is tapped from the
fourth tray from the top of the column. This vapor is
condensed, then is sent through a spiral cooler till it
reaches about ambient temperature. Water is the
cooling medium for the coil. The vapor will first pro-
ceed through the dephlegmator or reflux condenser,
which uses low strength alcohol from the triple ef-
fect as the cooling medium. Then the vapor enters
the condenser where it is cooled with mash. A tap
with a U-shaped leg from the first condenser pro-
vides for refluxing of a part of the condensate to the
rectifying column. The condensate enters the recti-
fying column below the fourth tray from the top. A
valve in the return line regulates the amount of li-
quid refluxed and the amount passed on to the se-
cond condenser. The degree of regulation by the
valve will determine the strength of proof. Proof of


strength is measured continuously by an alcohol
hydrometer in a tester which is placed in the exit
line of the second condenser. The testing is perform-
ed before the condensate enters the alcohol cooler.
An additional valve and tap in this line may return
the already condensed liquid from the second con-
denser to the rectifying column below the fourth
tray from the top. This piping arrangement is omit-
ted from the flow diagram for clarity as most text-
books on this subject show the needed piping ar-
rangement.
For a smooth operation in rectifying, it is essen-
tial that the pressure inside this vessel remains as
constant as possible. Hence, the supply of 5
lbs/inch2 of steam provided to the calandria or coil
system should be automatically regulated according
to the desired constant pressure maintained inside
the rectifying column. With the input flow from the
triple effect being almost constant, and the pressure
inside the rectifier maintained at a constant level by
automatic instrumentation, the strength of alcohol
leaving the condenser can be regulated to obtain 190
proof by valves controlling the amount of refluxing
permitted. Also, to guarantee constant supply of in-
put, the 25 percent alcohol mixture is passed
through the dephlegamator to obtain a constant
head for the input supply to the rectifier.
Piping to conduct the vapor between the rectifier
and condensers should have a diameter of 6 inches,
while the reflux piping from the condensers to the
rectifier should be one inch. It is advisable to install
condensers with ample capacity; a pipe and shell
condenser with 75 square feet of heat exchange
capacity should be more than adequate. Only one
tap is made from the rectifier, at the fourth tray
from the top, to obtain concentrated ethanol vapor
which still contains volatile oils. No other taps are
made to recover separately these substances. The
rated capacity for the community distillery makes
such recovery hardly worthwhile.
Finally, the rejected hot water from the rectifying
column may be recovered from the inverted
U-shaped exit for additional boilerfeed water, or it
may simply be discarded.

Conclusion and Additional Observations
A small community distillery which incorporates
thermal efficiencies has been described. All pipe
sizes and flows are supplied so that a farming com-
munity may initiate an energy supply plant, utiliz-
ing local skills and farming out some phases of
design and construction.
The question of whether a community-sized
distillery is economically feasible or not is unknown.
Certain advantages are obvious: (1) the short supply
lines needed for feedstocks and fuel; (2) suitability of
distiller's solids in wet form for feed; and (3) the con-








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Details for Yeast Propagating Vessel and Calandria for Triple Effect
from Flow Diagram for Community Distillery*


*Reproduction not permitted without author's written permission.

venience of a local alcohol fuel supply. A definite
disadvantage may be the small economies of scale.
The question of converting 190 proof ethanol to
anhydrous alcohol has not been addressed. Such a
process will require the use of highly flammable en-
training materials and it is felt that such a process
should only be applied by large distilleries having a
well-trained staff and equipment to prevent possible
serious accidents. For the time being, it is suggested
that a community distillery sell its production to a
large distillery for the conversion into anhydrous
alcohol. However, such facilities are not presently
available in Florida.


Design by F. le Grand
Drawing by B. Chandler


Simple methods using dried cracked grains to pro-
duce anhydrous alcohol have been reported recently.
Pilot plant studies are now being conducted
elsewhere for possible incorporation by community-
sized distilleries in the future. Also, an additive is
already being marketed which could permit the mix-
ing of 190 proof ethanol with unleaded gasoline,
without causing separation of the liquids. Hopeful-
ly, other additives will be announced soon. Break-
throughs such as these may allow utilization of 95
percent alcohol at the local level. Alcohol of this
quality may be produced by a community distillery
as described in this publication.












































































Details for Barometric Condensor and Calandria Vessel
from Flow Diagram for Community Distillery*


*Reproduction not permitted without author's written permission.


Design by F. le Grand
Drawing by B. Chandler





AUG 919i 0 : :


This publication was promulgated at a cost of $457.75, or 15.3. cents per copy, to provide information on a method
for producing ethanol by a community distillery for use as a fuel. 5 3M 80




COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, INSTITUTE OF FOOD AND AGRICULTURAL
SCIENCES, K. R. Tefertller, director, In cooperation with the United States Department of Agriculture, publishes this infor-
mation to further the purpose of the May 8 and June 30, 1914 Acts of Congress; and is authorized to provide research, educa-
tional Information and other services only to individuals and institutions that function without regard to race, color, sex or
national origin. Single copies of Extension publications (excluding 4-H and Youth publications) are available free to Florida
residents from County Extension Offices. Information on bulk rates or copies for out-of-state purchasers is available from
C. M. Hinton, Publications Distribution Center, IFAS Building 664, University of Florida, Gainesville, Florida 32611. Before publicizing this
publication, editors should contact this address to determine availability.




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