EPA-650/2-75-032-C
April 1975
Environmental Protection Technology Series
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EPA-650/2-75-032-C
ENERGY CONSUMPTION:
PAPER, STONE/CLAY/GLASS/CONCRETE,
AND FOOD INDUSTRIES
by
John T. Reding and Burchard P. Shepherd
Dow Chemical, U. S . A.
Texas Division
Freeport, Texas 77541
Contract No. 68-02-1329, Task 5
Program Element No. 1AB013
ROAP No. 21ADE-010
EPA Project Officer: Irvin A. Jefcoat
Control Systems Laboratory
National Environmental Research Center
Research Triangle Park, North Carolina 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
WASHINGTON, D. C. 20460
April 1975
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EPA REVIEW NOTICE
This report has been reviewed by the National Environmental Research
Center - Research Triangle Park, Office of Research and Development,
EPA, and approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the Environmental
Protection Agency, nor does mention of trade names or commercial
products constitute endorsement or recommendation for use.
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environ-
mental Protection Agency, have been grouped into series. These broad
categories were established to facilitate further development and applica-
tion of environmental technology. Elimination of traditional grouping was
consciously planned to foster technology transfer and maximum interface
in related fields. These series are:
1. ENVIRONMENTAL HEALTH EFFECTS RESEARCH
2. ENVIRONMENTAL PROTECTION TECHNOLOGY
3. ECOLOGICAL RESEARCH
4. ENVIRONMENTAL MONITORING
5. SOCIOECONOMIC ENVIRONMENTAL STUDIES
6. SCIENTIFIC AND TECHNICAL ASSESSMENT REPORTS
9. MISCELLANEOUS
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to
develop and demonstrate instrumentation, equipment and methodology
to repair or prevent environmental degradation from point and non-
point sources of pollution. This work provides the new or improved
technology required for the control and treatment of pollution sources
to meet environmental quality standards.
This document is available to the public for sale through the National
Technical Information Service, Springfield, Virginia 22161.
Publication No. EPA-650/2-75-032-C
11
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CONTENTS
Page
EPA Review Notice ii
List of Figures iv
List of Tables vi
Sections
I Conclusions 1
II Recommendations 2
III Introduction 3
IV Energy Consumption within the Paper, Stone- 5
Clay -Glass -Concrete and Food Industries
A. Paper by the Sulfate or Kraft Process 5
B. Cement by the Wet Process 15
C. Glass Manufacture 20
D. Food Processes 20
E. Summay of Energy Losses and Recommended ^3
Conservation Approaches
V Bibliography 49
VI Glossary of Abbreviations 52
VII Appendix 53
ill
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FIGURES
No. Page
1 Paper Energy Consumption Diagram 7
2 Paper Energy Intensive Equipment Diagram- 9
Digester, Blow Tank and Washer
3 Paper Energy Intensive Equipment Diagram- 11
Multi-effect Evaporation
4 Paper Energy Intensive Equipment Diagram- 12
Direct Heat Evaporation and Recovery Furnace
5 Paper Energy Intensive Equipment Diagram- 13
Calcining
6 Paper Energy Intensive Equipment Diagram- 14
Dryer
7 Cement (Wet Process) Energy Consumption 18
Diagram
8 Cement (Wet Process) Energy Intensive Equip- 19
ment Diagram-Cement Kiln
9 Glass Energy Consumption Diagram 22
10 Glass Energy Intensive Equipment Diagram- 23
Melting Furnace
11 Meatpacking (Beef Slaughter) Energy Con- 26
sumption Diagram
12 Meat (Pork) Processing Energy Consumption 27
Diagram
13 Fluid Milk Energy Consumption Diagram 29
14 Canned Fruits and Vegetables Energy Con- 32
sumption Diagram
15 Frozen Foods (Vegetables) Energy Consump- 31*
tion Diagram
16 Animal Feeds (Formula Feed) Energy Con- 37
sumption Diagram
iv
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FIGURES Ccontinued) Page
17 Animal Feeds (Dehydrated Alfalfa) Energy 38
Consumption Diagram
18 Bread and Rolls Energy Consumption Diagram ^0
19 Beet Sugar Energy Consumption Diagram 42
20 Malt Beverage Energy Consumption Diagram 45
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TABLES
No. Page
1 Paper Energy Conservation Approaches 16
2 Cement Energy Conservation Approaches 21
3 Glass Energy Conservation Approaches 24
4 Beef Slaughter and Pork Processing Energy 28
Conservation Approaches
5 Fluid Milk Energy Conservation Approaches 31
6 Canned Products Energy Conservation Approaches 33
7 Frozen Foods (Vegetables) Energy Conservation 35
Approaches
8 Animal Feeds (Formula Feed and Dehydrated 39
Alfalfa) Energy Conservation Approaches
9 Bread and Rolls Energy Conservation Approaches 41
10 Beet Sugar Energy Conservation Approaches 44
11 Malt Beverage Energy Conservation Approaches 46
12 Summary of Energy Losses and Recommended Con- 4?
servation Approaches
vi
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SECTION I
CONCLUSIONS
Energy consumption within the paper industry is concentrated
in wood digestion (cooking), evaporation, furnace combustion,
drying and kiln operations. The kiln operation is the prima-
ry energy consumer in the cementmaking process, while glass
melting dominates energy consumption in the glassmaking pro-
cess. The food industry consumes major amounts of energy
in cooking, refrigeration, and drying operations. Losses in
all of these operations can be decreased by employing con-
servation techniques. These techniques include:
• Design modifications to increase waste heat recovery
from furnaces and kilns.
• Proper maintenance practices, especially with regard
to insulation to limit heat losses.
• Greater use of insulation to limit heat losses.
• Research and development to improve press drying of
paper, to increase yields of products and to de-
velop submerged combustion for heating glass.
• Waste utilization by the recycle of paper and by the
use of process wastes to fuel furnaces in the paper
process.
• Process integration to optimize co-production of
electricity and steam in the paper process and food
processes.
• Process integration by increased combination of pulp
and paper-making in one plant to eliminate pulp drying
in pulp mills.
• Process modification such as substituting the dry
process for the wet process in cementmaking, enrich-
ing of combustion air with oxygen in the glass melt-
ing operation and using agglomerated feed in the
glassmaking process.
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SECTION II
RECOMMENDATIONS
Energy conservation approaches suggested in this report
could be further defined and specified in more detail.
Unanswered questions which should be considered include
• The economic feasibility of the conservation
approaches.
• The difficulty of implementing the approaches.
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SECTION III
INTRODUCTION
Purpose
The purpose of the total task Is to provide a breakdown
of energy consumption within the six primary industrial
categories - primary metals, chemicals, petroleum, food,
paper, and stone, clay, glass, concrete. The purpose
of this portion of the total task covered by this report
is to provide a breakdown of energy consumption within
the paper, food, and stone, clay, glass, concrete indust-
ries only. This breakdown can give direction to subsequent
conservation efforts.
Scope
This report analyzes high energy consumption operations
within the paper (SIC 26) and the stone, clay, glass,
concrete (SIC 32) industries. The principal pieces of
energy intensive equipment used in these operations are
identified. The causes of energy losses in these oper-
ations, the approximate magnitude of the losses, and pos-
sible approaches to decrease these losses are indicated.
The analysis of the food (SIC 20) industry is more qual-
itative and does not Include quantitative estimates of
energy losses.
General Background
The National Academy of Engineering has been commissioned
by the Environmental Protection Agency to conduct a com-
prehensive assessment of the current status and future
prospects of sulfur oxides control methods and strategies.
The agreement between the Environmental Protection Agency
and the National Academy of Engineering states explicitly
that special data collection projects may be required to
provide the National Academy of Engineering panel with
the background necessary for viewing all aspects of the
problem in perspective. This report is one segment of
the data collection project associated with the National
Academy of Engineering assessment.
One method of limiting the amount of SOX emissions arising
from energy conversion is simply to decrease fuel use
through energy conservation. In the year 1968, it has
been reported that 41.2 percent of the total energy con-
sumption in the United States was in the industrial sector.
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More specifically, 28 percent of the national energy con-
sumption was in the six industrial categories encompassed
by this total task. Conservation efforts directed toward
industries in these six categories should obtain the great-
est impact.
General Approach
The major processes for producing paper, cement and glass
were reviewed. Energy consumption block diagrams were
drawn for each process. These diagrams indicate the op-
erations within the processes where large amounts of energy
are used. The approximate magnitudes and types of energy
used are shown. Schematic diagrams show the physical and
operational appearance of energy intensive equipment. Causes
of energy losses in the energy intensive operations, the
approximate magnitude of the losses, and possible conserva-
tion approaches are suggested.
Ten processes for producing products in the food industry
have also been analyzed. The analyses are similar to those
described above, except that the schematic diagrams of energy
intensive equipment and quantitative estimates of energy
consumption by operation have been deleted.
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SECTION IV
ENERGY CONSUMPTION
WITHIN THE PAPER, STONE-CLAY-GLASS-CONCRETE
AND FOOD INDUSTRIES
Several observations need to be made concerning the analyses
of energy consumption included in this report:
• The type of energy used in each energy intensive op-
eration is included on the process block diagrams.
Different types of energy are not equivalent. Ap-
proximately 3 kJ's of fuel energy are required to
generate 1 kJ of electrical energy. Approximately
1.1 to 1.3 kJ's of fuel energy are required to gen-
erate 1 kJ of steam energy.
• Energy values for all processes are expressed in
terms of energy per unit weight of product.
• The tables showing energy conservation approaches
give estimates of losses in each operation of the
process and in the overall process. The losses
listed in each operation are additive. The losses
listed in the overall process often overlap and are
not additive.
• The values for energy input and losses are derived
from a variety of sources as listed in the biblio-
graphy. The values are representative of published
technology. New plants may already use conservation
approaches recommended in this report and thereby,
use less energy than indicated in the figures. [An
exception to this is the paper process, in which the
estimated energy usage is believed to represent very
modern technology.]
• Energy conservation approaches are listed in the tables.
In many cases a more specific explanation of the recom-
mended energy conservation approach is listed along
with the approach. An explanation of the conservation
approaches is included in the appendix for those in-
stances where the meaning of the term may be vague.
A. Paper by the Sulfate or Kraft Process
The paper industrial category (SIC 26) consumed approximately
67000 MW (2000 x 1012 BTU)* of energy in 1973. Pulp mills
(SIC 2611), paper mills (SIC 2621), and paperboard mills
*Purchased electricity is counted as 3600 kJ/kwh (3^13 BtuAwh).
5
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(SIC 2631) accounted for approximately 90 percent of this
energy usage. Paperboard mills are similar to paper mills.
Therefore, this report analyzes energy consumption in SIC
26 by analyzing energy consumption in the pulp and paper-
making processes.
Figure 1 shows the primary steps in the manufacture of un-
bleached paper or paperboard using the sulfate or Kraft
process. Pulp and paper mill energy consumption is highly
dependent on the product mix. The process in Figure 1 is
a low energy process because bleaching and coating opera-
tions are not included. Furthermore, the energy inputs
are representative of modern, well-operated plants.
Approximately 70 percent of the paper and paperboard man-
ufactured in the United States is made using the sulfate
process. The primary energy consumption operations are
digestion (cooking) of wood chips, evaporation of water
from the cooking liquor, calcining of wet CaC03 to lime,
and drying of paper. These highly energy intensive heating
operations account for more than 70 percent of the energy
input into the sulfate process shown in Figure 1.
The major energy sources for the energy intensive heating .
operations are process wastes, natural gas and fuel oil.
Most of this fuel produces high pressure steam, which is
then used to produce electricity and lower pressure steam
for the process operations. The electricity is used in a
number of operations, including barking, chipping, pumping,
screening, draining, pressing, drying and calendering (dry
pressing).
Figure 2 shows digestion (cooking) of wood chips, partial
separation of pulp from water in a blow tank, and pulp wash-
ing. The digestion operation occurs at a temperature of 4
(350°F) and at a pressure of 1150 kN/m2 (165 psia). Pre-
steamed wood chips and cooking liquor (approximately 7 per-
cent sodium hydroxide, 3 percent sodium sulfide and 2 percent
sodium carbonate) are fed to the top of the digester. Pie-
circulating cooking liquor passes through steam heaters to
provide heat for this operation. As the wood chips pass
down through the digester, the organic lignins which hold
the cellulose fibers of the wood together, are dissolved
into the cooking liquor. The resulting black liquor is re-
moved at an intermediate point in the column. Wash water is
fed to the bottom of the column to further the separation of
the delignified wood chips from the black liquor. Wash water
plus delignified wood chips are then fed to a blow tank at
atmospheric pressure. The rapid drop in pressure breaks up
or defiberizes the cellulose chips and reduces them to pulp.
The pressure drop also allows steam to be flashed from the
blow tank. Next the pulp plus water mixture is fed to a
6
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Figure 1. Paper energy consumption diagram
[1973 USA production: 56.2 x 109 kg (123.8 x 109 lb)]
[1973 energy consumption (process wastes, natural gas, fuel oil,
electricity): 67,000 MW (2000 x 1012 Btu)]
Energy input
Reclaimed energy
Heat rejection
1
Logs
2900 kJ/kg
(1250 Btu/lb)
steam
-j Debarking, chipping |
Hot wash
water
Wood
White liquor
Ifrom causticlzlng
01
a)
in t,
as
a
60
Digester and
blow tank
o
rH
^
4J
DQ
CB
o\ a)
4->
n
I
230 kJ/kg
(100 Btu/Tt)
. Wash
1 water
h
to
J
Lt exchange
leated
rash water
Pulp and
wash water
Washer
,,
1
Terpenes
to processing
' 230 kJ/kfL
(100 Btu/lb
395°K(250°F
185 kJ/kg
Dilute 355<>K (l80°F
,fac water vapor
iliquor
2120 kJ/kg
(915 Btu/lb )
steam
bO
o
0
CO
o
CM
•^••••J
f
""" (9000 Btu/lb) i
black liquor as fuel
,1
J
Evaporatl
Pulp and
r water
Screening
beating,
draining,
pressing
W
P
•
fWater
et
aper
35 5^ K (loO^F]
black water vapor
liquor
^^1 170 kJ/kg
°" i (75 Btu/lb™
Water
vaoor
1 ' H 2320 kJ/kK
(1000 Btu/lb)
330°K (130°F)
Foul
condensate
160 kJ/kg ^
(200 Btu/lb)
330°K (135°F)
580 kJ/kg _
(250 Btu/lb)
Soap resins 330°K (135°F)
to
processing
185 kJ/kg _
(80QBtu/lbo)
(continued on next page)
-------
Figure 1. (Continued)
kJ/kg
(1900 Btu/lb)
steam
ffl
o
o o
oo o
• o
o o\
fM ^
b
o
3
cr
•H
Dry
paper
I I
I Calendering I i
^••^— • ' L
Exhaust air
and water
vapor
Warm
water
O rH
n)
1-H 3
Paper product
Heat exchange
hO
\
1-1
X
O
o
o\
Direct heat evaporation
and recovery furnace
AHreac = 1950 kJ/kg
(850 Btu/lb)
Endothermic
3
±>
03
O E
rn n)
rH Q)
ir\ 4J
^ in
CaO
1970 kJ/ke
Smelt
Air
Water
230 kJ/kg _
(100 Btu/l?J
radiation
t170 kJ/kg
(1800 Btu/lb)
365°K (200°F)
230 kJ/kg _
Stack
gas
(100 Btu/lb)
radiation
6050 kJ/kg ^
Wash
Iwater
(2600 Btu/lb)
(300°F)
Causticizing
operations
IWhite
fliquor
to
digester
(850 Btu/lb)
natural gas or
fuel oil
€-*•
CaC03
mud
Lime kiln
aHreac = 580 kJ/kg
(250 Btu/lb)
Endothermic
280 kJ/kg ^
(120 Btu/lb)
radiation
C02 and
other exiting
gases
1020 kJ/ks
CaO
Btu/lbJ^
H80°K C400°F)
100 kJ/kg
(tO Btu/lb)
615°K (650°F)
Storage
CaO
1390 kJ/kg
(600 Btu/lb)
unaccounted
for
-------
Figure 2. Paper energy intensive equipment diagram - digester, blow tank,
and washer
[Rejected heat: Radiation - 230 kJ/kg (100 Btu/lb)
Terpenes stream - 230 kJ/kg (100 Btu/lb) at 395°K (250°P)
Water vapor off washer - 185 kJ/kg (80 Btu/lb) at 355°K (l80°F)]
Terpenes,
steam
Flash
steam
Chips
Heater
Cooking liquor
White liquor
from causticizing
Presteaming vessel
Steam
Condensate
Flash steam
Wash water plus chips
Wash
water
Kamyr
continuous
digester
To multi-
effect
evaporators
Liquid cyclone knotter
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knotter (or prebreaker-knot breaker) where knots are se-
parated from the pulp. Additional washing of the pulp
removes cooking chemicals from the pulp. The wet pulp
leaves the washer at a temperature of 350°K (l80°F).
Figure 3 shows the concentrating of the dilute black liquor
(a,15_20 percent solids) leaving the digester. Water is
evaporated from the liquor in a multi-effect evaporation
system until the solids concentration is approximately 50
percent. This step is necessary to allow later recovery of
caustic and sulfide contained in the liquor and to allow the
use of organics in the black liquor as fuel. In addition,
as shown in the figure, soaps that are used to make tall oil
are obtained in this processing step. Steam at a pressure
of 240-550 kN/m2 (35-80 psia) is used to provide heat for
this operation.
Figure 4 shows additional concentrating of the black liquor
to approximately 65 percent in a direct heat evaporator;
combustion of the black liquor in a furnace; and reclaiming
of caustic and sulfide in a dissolving tank. The burning
of the oragnics in the black liquor supplies heat which is
used to make high pressure steam. This steam is then used
to produce electricity and process steam. Flue gases from
the furnace are used to supply heat to the direct heat evap-
orator. Flue gases from the direct heat evaporator leave
at 420°K (300°F). Approximately 10 percent of the heat pro-
duced in the furnace is used to reduce makeup sodium sulfate
to sulfide in the bottom of the furnace.
Figure 5 shows a rotary kiln which is commonly used to pro-
duce lime from CaC03 mud. This mud is obtained when lime is
added to the sodium sulfide, sodium carbonate solution from
the recovery furnace. The kiln is operated at approximately
1370°K (2000°F). The lime kiln is shown with Warner-type,
kiln mounted integral tube coolers. The coolers cool the
product lime to 590-640°K (600-700°F) and preheat combustion
air which is used to burn natural gas. Combustion gases
leave the kiln at approximately 480°K (400°F).
Figure 6 shows a possible dryer scheme. Many different ar-
rangements of dryers can be used. The dryer section con-
sists of a number of hollow iron or steel cylinders over
which the paper web passes in a serpentine fashion. The
cylinders are rotated in synchronization. Heat is supplied
by steam condensing inside the cylinders and usually the
sheet is pressed tightly against the dryers by a heavy dryer
felt. The prime purpose of the felt is to bring the sheet
as close as possible to the dryer surface. The air film
between sheet and dryer is reduced to a reasonable minimum
so that maximum practical heat transfer to the sheet is
10
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Figure 3- Paper energy Intensive equipment diagram - multi-effect
evaporation
[Rejected heat: Radiation - 170 kJ/kg (75 Btu/lb)
Water vapor - 2320 kJ/kg (1000 Btu/lb) at 330°K (130°F)
Foul condensate - H60 kJ/kg (200 Btu/lb) at 330°K (135°F)
Soap resins - 185 kJ/kg (80 Btu/lb) at 355°K (180°F)]
LL Li.
Water
vapor
Concentrated
black
liquor
Hot
black
liquor
*-*
Condensate
to boiler
Soap to
tall oil
plant
Dilute
black
liquor
Settling
tank
Combined foul
condensate to
sewer
Sextuple-effect evaporation system
11
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Figure 4. Paper energy intensive equipment diagram - direct heat
evaporation and recovery furnace
[Rejected heat: Radiation - 230 kJ/kg (100 Btu/lb)
Stack gas - 6050 kJ/kg (2600 Btu/lb) at U20°K (300°F)]
Recirculated i 1
liquor 1
Black
from n
effect
evapoi
systei
liquor
lulti-
'ator
" 1.
H 1
y
*• Flue gas to stack Steam
Make-uo . ^ , rW
Na2SO,/ Preaheated
1 | air »•
, | f , Black *"
liquor ^ J
fj Rec
L. fui
LJ I
Cyclone MixinE °£
evaporator M^
Smelt
dissolving
tank
•Feed wate
f Comb us
^T\
W
V
.overy
'nace
Smelt to
lusticizing
r
tion
gases
Combustion gases
from recovery furnace
12
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Figure 5. Paper energy Intensive equipment diagram - calcining
[Rejected heat: Radiation - 280 kJ/kg (120 Btu/lb)
Combustion gases - 1020 kJ/kg ( 40 Btu/lb) at 480°K C*00°F)
Hot product - 100 kJ/kg (HO Btu/lb) at 6l5°K (650°F)]
Discharge end with Warner
type integral cooler
Natural gas
and air
Combustion
gases
CaC03 mud
Secondary air
Burner
Lime kiln
13
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Figure 6. Paper energy intensive equipment diagram - dryer
[Rejected heat: Radiation - 230 kJ/kg (100 Btu/lb)
Exhaust air plus water vapor - 4170 kJ/kg (1800 Btu/lb) at
365°K (200°?)]
Air to water
heat exchange
Warm water
Warm air to operating
floor or to dryer
area
Insulated hood
\
Paper
from press
section >
Exhaust stack
Water
Air to air heat exchanger
Air intake from room
Hood air exaust duct
\
To
calender
if stack
Paper
dryer
Kraft dryer section
14
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obtained. A reasonably large portion of the dryer is wrap-
ped by the sheet, thus resulting in fairly good heat transfer
while adequate ventilation is possible through fairly
generous clear spaces throughout the dryer section. ' The
paper entering the dryer can contain 1 to 3 kg water per
kg paper.
Table 1 shows the causes of energy losses in the pulp and
papermaking process. It also gives estimates of the size
of the losses and some possible energy conservation approaches.
B. Cement by the Wet Process
The stone, clay, glass and concrete industrial category
(SIC 32) consumed approximately 45000 MW (1350 x 10rz Btu)
of energy in 1971. Processes for manufacturing cement and
glass accounted for over 55 percent of this total. Because
of their dominance of this category, processes for man-
ufacturing these two materials are analyzed in this report.
Portland cement is the dominant product of industrial
category 3241. In 1972 the energy consumption of this
category was approximately 16000 MW (480 x 1012Btu).*
Energy consumed in portland cement manufacture accounted
for over 95 percent of this quantity. Figure 7 shows the
primary steps in the portland cement manufacturing process
using the "wet process". In 1972 approximately 59 percent
of the cement production in the United States came from
this process. It consists of blending a calcareous (lime-
bearing) material, an argillaceous (clayish) material and
an iron containing material (iron ore) with water and grind-
ing. The water content in the slurry is then reduced from
50 percent to 20-30 percent by letting the solids settle in
a tank. The thickened slurry is then charged into a rotary
kiln. As the slurry moves through the kiln, water is evap-
orated and then the endothermic reaction which releases C02
from the limestone occurs at 925°K (1200°F). Finally, at
1480°K (2200°F) complex silicates form in an exothermic reaction
which raises the cement temperature to 1750-l8lO°K (2700-2800°F).
The -charge leaves the kiln in the form of "clinker", marble size
particles produced by melting of portions of the charge. The
clinker is aircooled by preheating combustion air, combined with
gypsum (2-3 percent gypsum) and ground to a fine powder. Approx-
imately 85-90 percent of the total energy required for this pro-
cess is used in the kiln operation*. Natural gas, coal or oil
can be used as the fuel.
Figure 8 shows the kiln operation. The energy usage in a
cement kiln is dependent on a number of factors and can range
*Purchased electricity is counted as 3600 kJ/kwh (3413 Btu/kwh).
15
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Table 1. PAPER ENERGY CONSERVATION APPROACHES
Causes of
energy losses
Approximate
magnitude
of losses
Energy conservation
approaches
1. Digestion of wood
chips
a. Radiation &
convection
b. Heat in ter-
penes stream
c. Vaporization of
water in washer
2. Multi-effect evapora-
tion
a. Radiation &
convection
b. Heat in foul
condensate
c. Heat in water
vapor leaving
last evaporator
d. Heat in soap
resins
3. Direct heat evapora-
tion & recovery
furnace
a. Radiation &
convection
b. Heat in flue
gas
4. Calcination
a. Radiation &
convection
b. Heat in exiting
combustion gases
Heat in exiting
product
230 kJ/kg
(100 Btu/lb)
230 kJ/kg
CLOO Btu/lb)
185 kJ/kg
(80 Btu/lb)
170 kJ/kg
(75 Btu/lb)
460 kJ/kg
(200 Btu/lb)
2320 kJ/kg
(1000 Btu/lb)
185 kJ/kg
(80 Btu/lb)
230 kJ/kg
(100 Btu/lb)
6050 kJ/kg
(2600 Btu/lb)
280 kJ/kg
(120 Btu/lb)
1020 kJ/kg
(440 Btu/lb)
100 kJ/kg
(40 Btu/lb)
Insulation
Maintenance
Design modification
(waste heat recovery)
Insulation
Maintenance
Design modification
(waste heat recovery)
Design modification
(consider additional
effect)
Insulation
Maintenance
Design modification
(waste heat recovery)
Insulation
Design modification
housing of kiln)
Design modification
(waste heat recovery)
(reduce water content
in kiln feed)
Design modification
(waste heat recovery)
16
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Table 1. (continued)
Causes of
energy losses
Approximate
magnitude
of losses
Energy conservation
approaches
Paper drying
a. Radiation &
conduction
through hood
b. Heat in hood
exhaust gas
Overall process
230 kJ/kg
(100 Btu/lb)
kJ/kg
(1800 Btu/lb)
a.
S<
Drying of pulp in
some pulp mills
Unnecessary bleach-
ing of pulp in some
cases
High degree of 4400 kJ/kg
wetness of paper (1900 Btu/lb)
leaving presses
Low yield of paper
from wood
Overdrying of
paper
Lack of paper
recycling
Inefficient
evaporation of
water in direct
heat evaporator
10,000 kJ/kg
(4000 Btu/lb)
460 kJ/kg
(200 Btu/lb)
Insulation
Design modification
(waste heat recovery)
Process integration
(integrate pulp &
paper production)
Market modification
Research & development
(improve drying ef-
ficiency of presses)
Research & development
Operation modifica-
tion
Waste utilization
Design modification
(replace direct heat
evaporator with ad-
ditional effect in
multi-effect evapora-
tion system)
17
-------
Figure 7. Cement (wet process) energy consumption diagram
[1972 USA production: 73 x 109 kg (160 x 109 lb)]
[1972 USA energy consumption (natural gas, coal, oil,
electricity): 16,000 MW (480 x 1012 Btu)]
Energy input
Heat rejection
Limestone
Crushing
Iron
C1»
Water
Blending
I
Slurry
Grinding, blending |
I
Separator
5800 kJ/kg
Kiln
Slurryf_
Water
(2500 Btu/lb)
natural gas
= 17^0 kJ/kg
(750 Btu/lb)
1560 kJ/kg
(670 Btu/lb)
radiation
Gypsu
1
Clinker^ 2320 kJ/kg _
t
Storage
ml
Clinker
p
Grinding
(1000 Btu/lb)
590°K (600°P
185 kJ/ke ^
(80 Btu/lb)
480°K OOO°F)
\
Cement product
18
-------
Figure 8. Cement (wet process) energy intensive equipment diagram - cement
kiln
[Rejected heat: Radiation - 1560 kJ/kg (670 Btu/lb)
Exit gases - 2320 kJ/kg (1000 Btu/lb) at 590°K (600°P)
Clinker - 185 kJ/kg (80 Btu/lb) at 180°K (100°P)]
Combustion
products to
stack
-*-
Slurry _j
feed
Chains to help transmit heat
CJas fuel,
air
Air U-T—'
r
Clinker
Cement kiln
Clinker cooler
19
-------
from 3250 to 11600 kJ/kg (1*100 to 5000 Btu/lb). The value
chosen for this report is an intermediate one of 5800 kJ/kg
(2500 Btu/lb}. Feed preheaters which use the heat available
in exiting combustion gases are used on recently built ce-
ment kilns to decrease energy consumption.
Table 2 shows the causes of energy losses in the cement man-
ufacturing process. It also gives estimates of the size of
the losses and some possible energy conservation approaches.
C. Glass Manufacture
Three major glass industrial categories (3211 or flat glass,
3221 or glass containers, 3229 or pressed and blown glass and
glassware) are large consumers of energy because each cat-
egory includes glass melting as a part of the process. These
three groups consumed 9200 MW (275 x 1012 Btu)* in 1971.
Natural gas was the primary energy source.
Figure 9 shows the major steps in the glassmaking process.
The primary energy consumption step whether the final pro-
duct is a container, flat glass, or blown glass is the melt-
ing of the raw materials. Approximately 70-80 percent of the
total energy consumed in the glass manufacturing process is
expended in this operation.
Figure 10 shows a melting operation in a continuous glass
tank. Usually these tanks are rectangular and are divided
into two compartments, a large melting compartment and a
smaller cooling or refining compartment. A crown above the
tank walls provides a space for combustion. Regenerators
economize fuel by recovering heat from the flue gas before
it passes to the stack. The temperature in the melting com-
partment of the glass tank is 1770°K (2730°F).
Table 3 shows the causes of energy losses in the glass melt-
ing operation. It also lists the approximate magnitude of the
losses and possible energy conservation approaches.
D. Food Processes
The analysis of energy consumption within the food industrial
category (SIC 20) is not as quantitative as the analyses of
the other industrial categories. One reason for this is the
difficulty in covering such a diverse industry in a short time.
Equally important is the lack of information on energy con-
sumption by operation. This lack is probably due to the minor
importance of energy costs in most food processes.
*Purchased electricity is counted as 3&"00 kJ/kwh (3^13 Btu/kwh),
20
-------
Table 2. CEMENT ENERGY CONSERVATION APPROACHES
Causes of energy
losses
Approximate
magnitude of
losses
Energy conservation
approaches
1. Kiln
a. Radiation &
convection
b. Heat in exiting
gases
c. Heat in exiting
product
1560 kJ/kg
(670 Btu/lb)
2320 kJ/kg
(1000 Btu/lb)
185 kJ/kg
(80 Btu/lb
Maintenance
Insulation
Design modification
(Increase use of
feed preheaters)
Design modification
(waste heat recovery)
2. Overall Process
Evaporation of
water in kiln
1160 kJ/kg
(500 Btu/lb)
Process modification
(substitute dry
process for wet)
21
-------
Figure 9. Glass energy consumption diagram
[1971 USA production: 16 x 10s kg (3^ x 109 lb)]
[1971 USA energy consumption (primarily natural gas, electricity):
9200 HW (275 x 1012 Btu)]
Energy input
Heat rejection
Silica
Sodium
Lime- carbonate
stone
Crushed waste glass
stone I
I £
tilt
Mixing
7900 kJ/kg
(3^00 Btu/lb)
natural gas
i
Melting
= 185 kJ/kg
(80 Btu/lb)
Molten
glass
Forming
3950 ItJ/kg
(1700 Btu/lb
radiation
,,J3taclc gases 1600 kJ/kg
r
(700 Btu/lb)
8lO°K (1000°F)
Crushing
Annealing
I
Inspection
Glass products
2320 kJ/kg ^
(1000 Btu/lb)
Heat to atmosphere
during cooling of glass
22
-------
Figure 10. Glass energy intensive equipment diagram - melting furnace
[Rejected heat: Radiation - 3950 kJ/kg (1700 Btu/lb)
Stack gases - 1600 kJ/kg (700 Btu/lb) at 8lO°K (1000°P)]
Crown
23
-------
Table 3- GLASS ENERGY CONSERVATION APPROACHES
Causes of energy
losses
Approximate
magnitude of
losses
Energy conservation
approaches
1. Glass melting
a. Radiation &
convection
b. Heat in stack
gases
3950 kJ/kg
(1700 Btu/lb)
1600 kJ/kg
(700 Btu/lb)
Maintenance
Insulation
Research & develop-
ment (submerged
combustion)
Design modification
(waste heat recovery)
2. Overall Process
a. Sensible heat in
inerts (Na) con-
tained in combus
tion air
b. Difficulty in
melting raw
materials
c. Cooling of glass
with no heat
recovery
690 kJ/kg
(300 Btu/lb)
920 kJ/kg
(400 Btu/lb)
2320 kJ/kg
(1000 Btu/lb)
Process modification
(oxygen enrichment
of combustion air)
Process modification
(use agglomerated
feed)
-------
In 1971 the approximate energy consumption for the food
category was 30,000 MW (900 x 10 lz Btu)*. This report covers
processes which account for approximately 50 percent of this
total,
The meatpacking industrial category (SIC 2011) is the largest
energy consumer within the food category. The total energy
usage by this category in 1971 was approximately 2800 MW
(85 x 1012 Btu)*. The primary sources of energy were natural
gas and electricity. The energy usage can be conveniently
split into three major groups:
• beef slaughter - approximately 8HO MW (25 x 1012Btu)*
• other slaughter - approximately 1000 MW (30 x 1012Btu)*
• meat processing- approximately 1000 MW (30 x 1012Btu)*
Figure 11 shows the major steps in a beef slaughter process.
This process is not especially energy intensive and energy
requirements vary widely depending on the extent of the by-
product processing. The primary energy consumption steps in
the process shown are refrigeration of products and render-
ing (converting into fats, oils, and proteinaceous solids) of
by-products.
Figure 12 shows the major steps in pork processing. The total
energy consumption shown for 1971 includes both pork processed
under the 2011 industrial category (meatpacking) and the 2013
industrial category (sausages and other prepared meat products).
The energy intensive steps include cooking/smoking and refrig-
eration of the products.
Table 4 lists causes of energy losses in beef slaughtering
and pork processing. It also lists possible energy conser-
vation approaches for these processes.
The fluid milk industrial category (SIC 2026) includes bulk
fluid products, packaged fluid milk, cottage cheese, butter-
milk, flavored milk drinks and a number of other minor products.
The total energy usage by this category in 1971 was approximate-
ly 1900 MW (58 x 10r2Btu)». Bulk and packaged fluid milk
comprise by far the largest volume of production although the
process for producing them is not energy intensive.
Figure 13 shows the major steps in the fluid milk process.
This process accounts for approximately 20 percent of the
total energy consumption in this industrial category. Milk
and cream are usually separated in a centrifugal clarifier,
pasteurized at a temperature of 336-345°K (145-162°F) [past-
eurization at 345°K for 16 seconds is more efficient than at
*Purchased electricity is counted as 3600 kJ/kwh (3^13 Btu/kwh).
25
-------
Figure 11. Meat packing (beef slaughter) energy consumption diagram
[1971 USA production (beef): 8.2 x 109 kg (18.1 x 109 lb)]
[1971 energy (primarily natural gas,* electricity): 8^0 MW
(25 x 1012Btu)]
Energy Input
1 1 Cattle
Slaughter
i
1 Blood to orocessing
r
Hide removal
T Hides to processing
Eviscerating
1 Edible
1 offal
Steam /•
Ine
i i
dibles
v ^^^^Inedlble |
• renderine I
Trimming, cutting,
deboning
^Meat for
processing
Steam f
<
t Scraps
* *§ Edible rendering |
> Meat products
Ling
1
* Natural gas is used for steam generation.
26
-------
Figure 12. Meat (pork) processing energy consumption diagram
[1971 USA production: 1.9 x 109 kg d.l x 109 lb)]
[1971 energy consumption (primarily natural gas, electricity);
1100 MW (33 x 1012 Btu)]
Energy input
Hams and pork bellies
(from slaughter process
Skinning, trimming
boning
Pickle
SolutionL
Curing
Natural gas
i
Cooking/smoking
Electricity
i
J
Cooling
i
J
Aging
Forming, slicing
i
Packaging
Bacon and ham products
27
-------
Table i|. BEEF SLAUGHTER AND PORK PROCESSING
ENERGY CONSERVATION APPROACHES
Causes of energy
losses
Energy conservation
approaches
Cooling
Conduction
and convection
Rendering (cooking)
Radiation and
convection
Insulation
Maintenance
Insulation
Maintenance
3. Cooking/smoking
a. Heat in exhaust
gases
b. Radiation &
convection
Design modification
(waste heat recovery)
Maintenance
Insulation
Overall Process
Unnecessary purchase of
electricity from utilities
Process integration
(consider co-production
of electricity and steam)
28
-------
Figure 13. Fluid milk energy consumption diagram
[1971 USA production: 23 x 109 kg (51 x 109 lb)]
[1971 energy consumption (primarily natural gas,* electricity)
400 I1W (12 x 10li Btu)]
Energy input
Unprocessed milk
Separation
Cream to processing
Steam
t
Pasteurization
J
Homogenization
Vitamin D
Milk for by-products
Fortification
Electricity
Cooling
I
1
Packaging
Natural gas is used for steam generation.
29
-------
336°K for 30 minutes], and homogenized by pumping through
a small orifice at high pressure (14,000 to 17,000 kN/m*
or 2000-2500 psi). The milk is then fortified by the addition
of vitamin D, cooled and packaged. The primary energy con-
sumption steps are refrigeration after processing and heating
for pasteurization.
Table 5 lists the causes of energy losses in the fluid milk
process. It also lists possible energy conservation approaches.
The canned fruits and vegetables industrial category (SIC
2033) includes plants primarily engaged in the canning of
fruits, vegetables, fruit juices and vegetable juices. It
also includes manufacturers of catsup, other tomato sauces,
preserves, jams and jellies. The total energy usage by this
category in 1971 was approximately 18,000 MW (53 x 1012 Btu)*.
Figure 14 shows the major steps in a generalized canning- pro-
cess. All products do not go through all of the operations
shown. Green vegetables generally go through the blanching
operation where air is expelled when the vegetables are im-
mersed in hot water or steam. Tomato products generally re-
quire cooking. Exhausting of carbon dioxide and oxygen from
the cans is accomplished by passing the open cans through a
hot water or steam bath. Sterilizing is usually done with
steam under pressure at a temperature of 375-390°K (212-240°F).
These four heating operations are the primary energy consum-
ing steps in the canning industry. Natural gas is the main
source of energy to generate steam for these operations.
Table 6 lists the causes of energy losses in the canned fruits
and vegetables process. It also lists possible energy conser-
vation approaches.
The frozen fruits and vegetables industry (SIC 2037) includes
plants primarily engaged in the freezing of fruits, fruit
juices, vegetables and specialties. The total energy usage
by this category in 1971 was approximately 1300 MW (39x101?Btu?.
Figure 15 shows the major steps in a frozen vegetable process.
Vegetables accounted for over 40 percent of the production in
this category in 1971 but only 15-20 percent of the energy con-
sumption. The primary energy consumption operations are the
freezing plus cold storage of the product along with the blanch-
ing of the raw vegetables. Natural gas and electricity are the
primary energy sources.
Table 7 lists the causes of energy losses in the frozen vege-
table process. It also lists energy conservation approaches.
"Purchased electricity is counted as 3600 kJ/kwh (3413 Btu/kwh),
30
-------
Table 5. FLUID MILK ENERGY CONSERVATION APPROACHES
Causes of
energy losses
Energy conservation
approaches
1. Pasteurization
Conduction &
convection
Cooling
Conduction &
convection
Design modification
(continue replacement of old
type vat pasteurization
equipment with high temperature-
short time pasteurization
equipment)
Maintenance, Insulation
Insulation
Maintenance
Overall process
Unnecessary purchase of
electricity from utilities
Process integration
(consider co-production of
electricity and steam)
31
-------
Figure I1*. Canned fruits and vegetables energy consumption diagram
[1971 USA production: 13-5 x 109 kg (30 x 109 lb)]»
[1971 energy consumption (primarily natural gas*»): 1800 MW
(53
Energy Imput
Fruits, vegetables
Cleaning, raw
product preparation
P-
Steam J f
S*l
1 ' Green vegetables
Blanching • |
Tomatoes f _
Steam J |
SI
Cooking |
1
V Ir *
Can filling
i r
Steam ^B
I
Steam |
T
Exhausting, 1
can sealing^^^^l
i •
Sterilization 1
Cooling
W
Canned fruits and
vegetables
* This includes juices, preserves, jams, and jellies.
** Natural gas is used for steam generation.
32
-------
Table 6. CANNED PRODUCTS ENERGY CONSERVATION APPROACHES
Causes of
energy losses
Energy conservation
approaches
1, Blanching, cooking
exhausting, steril-
ization
a. Conduction &
convection
b. Heat required to
heat vessels
c. Overdoing operations
Maintenance
Insulation
Design modification
(replace batch operations
with continuous operations)
Operation modification^
(closer control of temperatures
and times of heating)
2. Overall Process
Purchase of electricity
from utilities
Process integration
(consider co-production
of steam and electricity)
33
-------
Figure 15. Frozen foods (vegetables) energy consumption diagram
[1971 USA production: 2.2 x 10* kg (4.8 x 109 lb)]
[1971 energy consumption (primarily natural gas*, electricity)
2300 NW (7x 1012 Btu)]
Energy inout
\
i
Vegetables
Raw product
cleaning
1
Trimming, grading
transporting
i
i
Steam
Blanching
J
Cooling, washing,
slicing, deaerating
Filling
1
Electricity
i
Freezing and
cold storage
J
Frozen products
* Natural gas is used for steam generation.
34
-------
Table 7. FROZEN FOODS (VEGETABLES) ENERGY CONSERVATION
APPROACHES
Causes of
energy losses
Energy conservation
approaches
1. Blanching
Conduction &
convection
Insulation
Maintenance
2. Freezing
a. Conduction &
convection
b. Excess lowering
of temperature
Maintenance
Insulation
Operation modification
(closer temperature control)
3. Overall Process
Purchase of electricity
from utilities
Process integration
(consider co-production
of steam and electricity)
35
-------
The animal feeds category (SIC 20^2) includes plants pri-
marily engaged in manufacturing feeds for animals and fowls.
The total energy consumption in 1971 for this category was
approximately 2070 MW (62 x 1012 Btu)*. The energy usage can
be conveniently split into three major groups:
formula feeds - approximately 1030 MW (31 x 1012Btu)«
dehydrated feeds - approximately 670 MW (20 x ltf2Btu)*
other - approximately 370 MW (11 x 1012 Btu)*
Figure 16 shows the major steps in a typical formula feed
process. The process is not excessively energy intensive.
Approximately 60 percent of the total energy consumption is
used to agglomerate or pelletize the feed, even though only
50 percent of the prepared formula feeds are pelletized.
Natural gas is the primary energy source for this process.
Figure 17 shows the major steps in the dehydrated alfalfa
process. The process is energy intensive due to the de-
hydrating operation.
Table 8 shows the causes of energy losses in the formula
feed and dehydrated alfalfa processes. It also lists pos-
sible energy conservation approaches.
The bread, cake and related products industrial category
(SIC 2051) consists of plants primarily engaged in man-
ufacturing bread, cakes and other "perishable" baking pro-
ducts. This group's energy usage in 1971 was 1870 MW (56 x
1012 Btu)*.
The largest volume of output in this category is bread and
bread rolls. Figure 18 shows the major steps in the bread-
making process using a continuous-mix process. The primary
energy consumption operations are baking, space heating/
ventilation and distribution of the products.
Table 9 shows the causes of energy losses in the breadmaking
industry. It also lists possible energy conservation approaches.
The beet sugar industrial category's (SIC 2063) energy con-
sumption in 1971 was 2700 MW (80 x 1012Btu). Nearly all of
this was fuel energy with the primary energy source being
natural gas.
Figure 19 shows the major steps in the beet sugar process.
The primary energy consumption occurs in the multi-effect
evaporation of water from the sucrose solution and in the
drying of beet pulp in a rotary dryer.
*Purchased electricity is counted as 3600 kJ/kwh (3*113 Btu/kwh).
36
-------
Figure 16. Animal feeds (formula feed) energy consumption diagram
[1971 USA production: 65 x 109 kg (142 x 109 lb)]
[1971 energy consumption (primarily natural gasB, electricity)
1030 MW (31 x 1012 Btu)]
Energy input
i
Grain
Grinding, rolling,
or flaking
Protein
+
Minerals
Mixing
325 kJ/kg
Btu/lb)
Pelleting
steam
I
Packaging
Prepared animal feed
* Natural gas is used for steam generation.
37
-------
Figure 17- Animal feeds (dehydrated alfalfa) energy consumption diagram
[1971 USA production: l.M x 109 kg (3.1 x 10* lb)]
[1971 energy consumption (primarily natural gas, electricity)
670 MW (20 x 1012 Btu)]
Energy input
Alfafa
14,000 kJ/kg
(6000 Btu/lb)
natural gas
Dehydrating
J
Grinding
Pelleting
Storage
I
Dried, pelleted
alfafa
38
-------
Table 8. ANIMAL FEEDS
(FORMULA FEED AND DEHYDRATED ALFALFA)
ENERGY CONSERVATION APPROACHES
Causes of
energy losses
Energy conservation
approaches
1. Pelleting (formula feed)
a. Conduction &
convection
b. Heat lost in
pellets
Maintenance
Insulation
2. Dehydrating (alfalfa)
a. Radiation, conduction
& convection
b. Heat lost in exhaust
gases
c. Heat lost in hot
product
Maintenance
Insulation
Design modification
(waste heat rpcovery)
Design modification
(waste heat recovery)
3. Overall process
(formula feed)
Purchase of electricity
from utilities
Process integration
(consider co-production
of steam & electricity)
39
-------
Figure 18. Bread and rolls energy consumption diagram
[1971 USA production: 7.1 x 109 kg (15.6 x 109 lb)]
[1971 energy consumption (primarily natural gas, petroleum,
electricity): 1600 MW (48 x 1012 Btu)]
Energy input
T
Other
ingredients
1
Yeast brew
(sugar, yeast, flour)
Blending and mixing
Extruding and cutting
Proofing
1620 kJ/kg
(700 Btu/lb)
natural gas, steam,
electricity
i
Baking
I
J
Bread
Depanning, cooling,
slicing, packaging
kJ/kg
(1100 Btu/lb)
gasoline
i
I
Distributing
J
1390 kJ/kg
(600 Btu/lb)
natural gas,
electricity
1
Space heating, ventilation
I
-------
Table 9. BREAD AND ROLLS ENERGY CONSERVATION APPROACHES
Causes of
energy losses
Energy conservation
approaches
1. Baking
a. Radiation, conduction,
& convection
b. Heat in exhausted
combustion gases
c. Heat in hot bread
product
Maintenance
Insulation
Design modification
(continue conversion from still
gas ovens to agitated ovens)
Design modification
(preheat combustion air with
bread)
2. Distribution
Low efficiency operation
of vehicles
Maintenance
Operation modification
3. Space heating
Conduction &
convection
Maintenance
Insulation
-------
Figure 19- Beet sugar energy consumption diagram
[1971 USA production: 3.0 x 109 kg (6.8 x 109 lb)]
[1971 energy consumption (primarily natural gas): 2700 MW
(80 x 1012 Btu)]
Energy input
I
Beets
Washing, slicing
Warm
water 1
Sugar extracting
Pulp
5700 kJ/kg
(2450 Btu/lb)
natural gas
Sucrose
solution
CaO
Pulp as
feed
Carbonating,
thickening,
filtering
Sulfur dioxide
Sulfonation, filtering
11.700 kJ/kg
Calcium sulfite
steam
Sulfon
cent
dr
I
Molasses
-eiiect evaporation •
i Sulfur dioxide
ation, crystallization,
rifuging, washing
ying, screening,
packing
f ' Calcium sulfit-e
Sugar
-------
Table 10 shows the causes of energy losses in the beet sugar
process. It also lists possible energy conservation approaches
The malt beverage industrial category's (SIC 2082) energy
consumption in 1971 was 1700 MW (51 x 10 Btu)*. The primary
energy sources are natural gas and electricity.
Figure 20 shows the major steps in the brewing process. Major
energy consumption occurs in the brewing, spent grain drying**,
and cooling/aging operations.
Table 11 shows the causes of energy losses in the malt bev-
erage process. It also lists possible energy conservation
approaches.
E. Summary of Energy Losses and Recommended Conservation
Approaches
Table 12 is a summary of energy losses and recommended con-
servation approaches for the paper, cement, glass and food
industrial groups.
*Purchased electricity is counted as 3600 kJ/kwh (3*113 Btu/kwh).
**0nly 40 percent of the spent grain is dried. Figure 20
shows a process in which all of the spent grain is dried.
-------
Table 10. BEET SUGAR ENERGY CONSERVATION APPROACHES
Causes of
energy losses
Energy conservation
approaches
Pulp drying
a. Radiation, conduction
and convection
b. Heat in exhaust
gases
c. Heat in dried pulp
2. Multi-effect evaporation
a. Radiation, conduction
and convection
b. Heat in water vapor out
of last effect
Maintenance
Insulation
Design modification
(waste heat recovery)
Design modificaton
(waste heat recovery)
Maintenance
Insulation
Design modification (add
additional effect to decrease
quantity of vapor)
3. Overall Process
Use of heat to dry pulp
Research and development
(develop alternate method
for water removal such as
pressing)
-------
Figure 20. Malt beverage energy consumption diagram
[1971 USA production: 16 x 109 kg (34 x 109 lb)]
[1971 energy consumption (primarily natural gas, electricity)
1700 MW (51 x 1012 Btu)]
Energy input
\
Barley, malt,
corn or rice
Steam
2780 kJ/kg
(1200 Btu/lb)
natural gas
Feedstuff
Mashing, filtering
Brewing(cooking)
^M
Wort
Spent grain
Hop leaves
Fermenting I
Electricity
Yeast to i i
yeast recovery f ^ c°2
1 Cooling
iHard
resins i
,, aging, |
rine ^^^^B
i jj
ICarbonating, filtering |
Packaging
45
-------
Table 11. MALT BEVERAGE ENERGY CONSERVATION APPROACHES
Causes of
energy losses
Energy conservation
approaches
1. Brewing
a. Conduction and
convection
b. Heat in brewing
product
Maintenance
Insulation
Design modification
(waste heat recovery)
2. Grain drying
a. Radiation, conduction
and convection
b. Heat in exhaust gases
c. Heat in dried grain
Maintenance
Insulation
Design modification
(waste heat recovery)
Design modification
(waste heat recovery)
3. Cooling, aging
a. Conduction and
convection
Maintenance
Insulation
Overall Process
a. Purchase of electricity Process integration
from utilities
(consider co-production of
steam and electricity)
Market modification
(intensify efforts to market
wet grain)
-------
Table 12. SUMMARY OF ENERGY LOSSES
AND RECOMMENDED CONSERVATION APPROACHES
High energy
consumption
operations
Paper Industry:
Digestion
Multi-effect
evaporation
Energy losses
Direct heat
evaporation
& recovery
furnace
Temperature
level
Radiation
350-400°K
(170-260°F)
Radiation
320-350°K
(115-170°F)
350-400°K
(170-260°F)
Radiation
400-450°K
(260-350°F
Calcination Radiation
450-500°K
(350-440°F)
600-650°K
(620-710°F)
Paper
drying
Overall
process
Radiation
350-400°K
(170-260°F)
Approx.
magnitude
230 kJ/kg
(100 Btu/lb)
415 kJ/kg
(180 Btu/lb)
170 kJ/kg
(75 Btu/lb)
2780 kJ/kg
(1200 Btu/lb)
185 kJ/kg
(80 Btu/lb)
230 kJ/kg
(100 Btu/lb)
6050 kJ/kg
(2600 Btu/lb)
280 kJ/kg
(120 Btu/lb)
1020 kJ/kg
(440 Btu/lb)
100 kJ/kg
(40 Btu/lb)
230 kJ/kg
(100 Btu/lb)
4170 kJ/kg
(1800 Btu/lb)
Energy
conservation
approaches
Insulation
Maintenance
Design
modification
Design
modification
Insulation
Maintenance
Design
modification
Insulation
Maintenance
Design
modification
Insulation
Maintenance
Design
modification
Insulation
Research and
development
Waste utiliza-
tion
Process
integration
Market
modification
Operation
modification
Design
modification
47
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Table 12 (continued)
High energy
consumption
operations
Cement Industry:
Kiln
Energy losses
Overall
process
Temperature
level
Radiation
450-500°K
550-600°K
Approx.
magnitude
1560 kJ/kg
(670 Btu/lb)
185 kJ/kg
(80 Btu/lb)
2320 kJ/kg
j j\j — w w w i\ c. j t.w r±u / ng>
(530-620°F) (1000 Btu/lb)
Energy
conservation
approaches
Design
modification
Insulation
Maintenance
Process
modification
Glass Industry:
Melting
tank
Radiation 3950 kJ/kg
(1700 Btu/lb)
800-850°K 1600 kJ/kg
(980-1070°P) (700 Btu/lb)
Overall
process
Research and
development
Design
modification
Insulation
Maintenance
Process
modification
Food Industry:
Process
integration
Insulation
Maintenance
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SECTION V
BIBLIOGRAPHY
Paper Industry
Chemical and Heat Recovery in the Paper Industry. In:
Steam/Its Generation and Use. New York, Babcock and Wilcox,
1972. p. 26-1 - 26-14.
Gyftopoulos, E. P., Director. Study of Effectiveness of
Industrial Fuel Utilization. Thermo Electron Corporation,
Waltham, MA. Report No. TE 5357-71-74. January 1974.
120 p.
Hall, F. K. Wood Pulp. Scientific American. 230:52-62,
April 19 71*.
Sawyer, F. G., C. T. Beals and A. W. Neubauer. Kraft Paper-
making. In: Modern Chemical Processes. New York, Reinhold
Publishing Company, 1952. 2;.255-266.
Sawyer, F. G., W. F. Holzer and L. D. McGlothlin. Kraft
Pulp Production. In: Modern Chemical Processes. New York,
Reinhold Publishing Company, 1952. 2:267-280.
A Study of Process Energy Requirements in the Paper and Pulp
Industry. New York, American Gas Association, Inc. 29 p.
Tomlinson, C. L., and F. H. Richter. The Alkali Recovery
System. In: Pulp and Paper Manufacture. ^:The Pulping of
Wood, MacDonald, R. G. (ed.). New York, McGraw-Hill Book
Company, 1969. p. 576-627.
Cement Industry
Brown, B. C. Cement. In: Minerals Yearbook 1972. Schreck,
A. E. (ed.). Washington, U. S. Government Printing Office,
1974. 1:247-257.
Gelb, B. A. Hydraulic Cement—SIC 3241. In: Energy Con-
sumption in Manufacturing, Myers, J. G. (project director).
Cambridge, MA, Ballinger Publishing Company, 1974.
p. 349-372.
Gyftopoulos, E. P., Director. Study of Effectiveness of
Industrial Fuel Utilization. Thermo Electron Corporation,
Waltham, MA. Report No. TE 5357-71-74. January 1974. 120 p.
49
-------
lammartino, N. R. Cement's Changing Scene. Chemical
Engineering. 81:102-106, June 24, 1974.
Kunnecke, M., and B. Piscaer. Choosing Insulation for
Rotary Kilns. Rock Products. 76 :138,140 ,142,148. May 1973.
Lea, F. M. The Chemistry of Cement and Concrete. London,
Edward Arnold (Publishers), Ltd., 1956. 637 p.
Peray, K. E., and J. J. Waddell. The Rotary Cement Kiln.
New York, Chemical Publishing Company, 1972. 194 p.
A Study of Process Energy Requirements in the Cement and
Lime Industry. New York, American Gas Association, Inc.
Glass Industry
Gelb, B. A. Basic Glass~SIC 3211, 3221, and 3229. In:
Energy Consumption in Manufacturing. Myers, J. G. (project
director). Cambridge, MA, Ballinger Publishing Company,
1974. p. 323-348.
Hutchins, J. R., Ill, and R. V. Harrington. Glass. In:
Kirk-Othmer Encyclopedia of Chemical Technology, 2nd ed.,
Standen, A. (ed.). New York, John Wiley and Sons, Inc.,
1966. 10:533-604.
Schwalbe, F. G. Furnaces and Fuels. In: Handbook of Glass
Manufacture, 3rd printing. Tooley, F. V. (ed.). New York,
Ogden Publishing Company, 1961. I:107-172.
Shand, E. B. Glass Engineering Handbook, 2nd ed. New York,
McGraw-Hill Book Company, Inc., 1958. 484 p.
A Study of Process Energy Requirements in the Glass Industry.
New York, American Gas Association, Inc.
Food Industry
Industrial Energy Study of Selected Food Industries.
Development Planning and Research Associates, Inc.,
Manhattan, KS. Contract No. 14-01-0001-1652. July 1974.
Levmore, S. Bread, Cake and Related Products—SIC 2051.
In: Energy Consumption in Manufacturing. Myers, J. G.
(project director). Cambridge, MA, Ballinger Publishing
Company, 1974. p. 153-158.
Levmore, S. Canned Fruits and Vegetables—SIC 2033. In:
Energy Consumption in Manufacturing. Myers, J. G. (project
director). Cambridge, MA, Ballinger Publishing Company,
1974. p. 123-129.
50
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Levmore, S. Frozen Fruits and Vegetables—SIC 2037. In:
Energy Consumption in Manufacturing. Myers, J. G. (project
director). Cambridge, MA, Ballinger Publishing Company,
1974. P. 131-136.
Preston, N. Fluid Milk—SIC 2026. In: Energy Consumption
in Manufacturing. Myers, J. G. (project director).
Cambridge, MA, Ballinger Publishing Company, 1974. p. 111-
121.
Preston, N. Meatpacking Plants—SIC 2011. In: Energy
Consumption in Manufacturing. Myers, J. G. (project
director). Cambridge, MA, Ballinger Publishing Company,
1974. P. 89-110.
Preston, N. Prepared Feeds—SIC 2042. In: Energy Consump-
tion in Manufacturing. Myers, J. G. (project director).
Cambridge, MA, Ballinger Publishing Company, 1974. p. 137-
151.
A Study of Process Energy Requirements in the Food Industry,
New York, American Gas Association, Inc.
51
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SECTION VI
GLOSSARY OF ABBREVIATIONS
Btu British thermal unit
cond condensate
CW cooling water
hr hour
kg kilogram
kJ kiloJoule
kN kiloNewton
kW kilowatt
kwh kilowatt hour
Ib pound
m meter
psia pounds per square inch absolute
MW megawatt
stm steam
yr year
52
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SECTION VII
APPENDIX
ENERGY CONSERVATION APPROACHES
Design modification - This term includes design changes in
equipment or process.
Insulation - This term implies that a review of the econdmics
of additional insulation is needed.
Maintenance - This term implies that the economics of
additional maintenance effort needs review.
Process integration - This term relates to the best use of
steam by using the same steam in more than one process
or to the optimization of the steam-electricity produc-
tion ratio. It also covers the combination of two or
more processes within one plant.
Research and development - This term relates to the improve-
ment of processes by future discoveries.
Operation modification - This term includes changes in op-
erating procedures or practices that do not require a
design change.
Market modification - This term relates to the substitution
of a low energy consumption product for a high energy
consumption product.
Process modification - This term relates to a change in a
process due to a change in process feedstock, raw
materials, or process route.
Waste utilization - This term relates to the use of fuel
value of waste process streams or to the recycling of
discarded materials.
53
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-650/2-75-032-C
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Energy Consumption:
Paper, Stone/Clay/Glass/Concrete, and Food
Industries
5. REPORT DATE
April 1975
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
John T. Reding and Burchard P. Shepherd
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Dow Chemical, U.S.A.
Texas Division
Freeport, Texas 77541
10. PROGRAM ELEMENT NO.
1AB013: ROAP 21ADE-010
11. CONTRACT/GRANT NO.
68-02-1329, Task 5
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
NERC-RTP, Control Systems Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final Task; 8/74-3/75
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT Tne report gives results of 2i study of energy consumption in the paper,
stone/clay/glass/concrete, and food industries. It analyzes energy-intensive steps
or operations for commonly used manufacturing processes. Results of the analyses
are in the form of energy consumption block diagrams, energy-intensive equipment
schematic diagrams, and tables that indicate the causes of energy losses, as well as
possible conservation approaches. (The analysis of energy consumption in the food
industry is not as quantitative as in the others.) The most common energy-intensive
operations in these industries are: (paper) -- pulp digestion (cooking), evaporation,
furnace and kiln operations, and drying; (stone/clay/glass/concrete) -- kiln and
furnace operations; and (food) -- cooking, drying, and refrigeration. Energy losses
in these operations could be reduced by: design, market, and process modification;
better insulation and maintenance; waste utilization; process integration; and
research and development.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
Energy
Consumption
Rocks
Clays
Glass
Concretes
Food Industry
Conservation
Pulping
Evaporation
Furnaces
Kilns
Paper Industry Research
8. DISTRIBUTION STATEMENT
Cookery
Refrigera-
ting
Drying
Marketing
Insulation
Wastes
06H
08G 13H.07A
07D
11B 13A, 05C
13C
I1L.
Unlimited
19 SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
60
20 SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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