EPA-600/2-76-099
April 1976
Environmental Protection Technology Series
LARRY-CAR-FREE CHARGING OF
COKE OVENS
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are.
1. Environmental Health Effects "Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
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.
EPA RE VIEW NOTICE
This report has been reviewed by the U.S. Environmental
Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect the
views and policy of the Agency, nor does mention of trade
names or commercial products constitute endorsement or
recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield. Virginia 22161.
-------
EPA-600/2-76-099
April 1976
LARRY-CAR-FREE
CHARGING
OF COKE OVENS
by
John Varga, Jr.
Battelle-Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
Contract No. 68-02-1323, Task 39
ROAPNo. 21AQR-042
Program Element No. 1AB015
EPA Task Officer: Robert C. McCrillis
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
-------
SUMMARY
The advantages of preheating coal before charging it into coke ovens are
discussed as an introduction to the use of charging systems that do not
use larry cars. Two larry-car-free systems are discussed. A third
system which does use a larry car for charging preheated coal is in-
cluded to provide a more complete coverage of the charging of preheated
coal. The two larry-car-free-charging systems offer good possibilities
for eliminating emissions generated during the usual method of charging
coke ovens with larry cars.
"This report was prepared in response to Item AM-2-2 of
the Protocol of the First Working Meeting of the USA/USSR
Task Force on Abatement of Air Pollution from the Iron and
Steel Industry. "
PJi&EPAT
npewMymecTBa npejjBapHTejiBHoro Harpesa IIIHXTH
aarpysKOw ee B KOKCosyio nem>, c uejitio oaHaKOMJieHHH
c MeTOflOM npMMeHCHMH aarpyaouHHx cncTew 6ea aarpyao^Hbix
BaroHOB. PaccNiaTpwBaioTCH ase CMCTeMbi, ne npHweHHiomHe aa-
rpyaouHbix BaroHOB. Taioce paccwaTpHBaeTCH 3-n CMCTeua, npn~
sarpyacxiHbiM BaroH JI.JIH sasajiKH noflorpeToro yrnn,
nojiHoe npencTaBjieHne o npouecce sarpyaKw noflo-
rpeToro yrjia. flse paccwaTpHBaeMbix CMCTeMbi 6es sarpysouHbix
BaroHOB nepcneKTHBHbi B OTHoiiieHMH npeflOTBpameHHH BpejiHbix
BbiSpocoB B aTMoc$epy, MMeioinwx MSCTO npw odbmnoM weTose aa-
KOKCOBBIX neueM npM HOMOIUM aarpyao^Hbix BaronoB.
3TOT oTqeT npeflCTaBJien B corjiacwH c nyHKTow AM-2-2
npOTOKOJia nepsoro padouero coBemaHHH Tpynnw C1IIA/CGCP
no (5opBde c sarpHSHeHHew aTwoc$epbi
KOM npOMHIIIJieHHOCTfcK).
Ill
-------
TABLE OF CONTENTS
Page
I. INTRODUCTION 1
II. THE UNITED STATES COKE INDUSTRY 3
III. COKE-OVEN CHARGING EMISSIONS 7
IV. PREHEATING OF COKING COAL 13
V. LARRY-CAR-FREE CHARGING OF COKE OVENS ... 17
The Coaltek System 17
Preheater 17
Pipeline Charging System 19
Utility Consumption . 22
Coaltek Installations 22
Retrofit Capability 22
The Precarbon System 24
Operation of the Precarbon System 25
Precarbon System Installations 29
Retrofit Capability 29
The Simcar System . . . . , 29
Preheater 30
Simcar Charging 30
Simcar System Installations 30
Retrofit Capability 31
Larry-Car-Free Charging Air-Pollution-
Control Potential 31
VI. REFERENCES 33
LIST OF FIGURES
Figure 1. Distribution of coke plants in the United States ... 4
Figure 2. Blast-furnace pig iron produced, coke consumed,
and coke rate in the U. S. integrated iron and
steel industry 5
-------
LIST OF FIGURES
(Continued)
Page
Figure 3. Size distribution of particulates collected during
charging 15. 0 tonnes (16.5 net tons) of coal
with the AISI/EPA larry car 10
Figure 4. Possible increase in coke-oven productivity by
preheating coal 14
Figure 5. Profile of wet, dried, and preheated coal, top
charged to a 10-tonne (11-net ton) coke oven
with a conventional larry car 15
Figure 6. Profile of preheated coal charged to a 13. 8-tonne
(15.2-net ton) coke oven 16
Figure 7. Preheating system for the Coaltek pipeline charging
process for coke ovens 18
Figure 8. Coaltek pipeline-charging preheating system . . 20
Figure 9. Coaltek system pipeline manifold for charging
of coke ovens 21
Figure 10. Section and top view of a steam jet in the Coaltek
system pipeline 21
Figure 11. Location of pipeline for existing coke ovens ... 23
Figure 12. Flow diagram for the Precarbon process .... 25
LIST OF TABLES
Table 1. By-Product Coke Plants 4
Table 2. Volumes of Gases Emitted During Charging of
15. 0 Tonnes (16. 5 Net Tons) of Coal 8
VI
-------
LIST OF FIGURES
(Continued)
Page
Table 3. Measured Constituent Concentrations in Gases
Emitted During the Charging of 15.0 Tonnes
(16. 5 Net Tons) Coal
Table 4. Coaltek System Installations 24
Table 5. Precarbon System Installations 29
Table 6. Simcar System Installations 30
VI1
-------
I. INTRODUCTION
Coke is the principal fuel used in the manufacture of steelmaking pig
iron. As a result, it accounts for the greatest amount of fuel used
in the production of steel products. During the manufacture of coke,
emissions are released to the atmosphere. Control of coke-plant
emissions has been a continuing problem to coke-plant operators.
Emissions are generated during charging of coal to the coke ovens,
during the coking cycle, when pushing incandescent coke from the
ovens, and during quenching of the coke. This report is concerned
with the control of emissions during the charging of coal to the ovens.
Emissions from coke ovens during the charging of moist coal from
larry cars may constitute as much as 70 percent of the total emissions
from the operation of a coke plant. The emissions associated with
the charging operation include (1) particulates and gases emitted with
the steam formed when the moist coal contacts the incandescent walls
of the ovens, (2) particulates and gases emitted from the ovens before
the charging-hole lids can be replaced and sealed on the charging
holes, (3) coal dust spilled during the charging operation, and (4)
particulates, smoke, and gases emitted during the coal-leveling
operation.
This Protocol Report discusses the use of a new technology that elim-
inates the use of larry cars for charging coal to coke ovens. Two
new processes reportedly eliminate or minimize emissions during the
charging operations.
-------
II. THE UNITED STATES COKE INDUSTRY
Coke produced in by-product coke ovens is consumed by the integrated
iron and steel industry, the gray iron foundry industry, and to a lesser
extent by a few other industries. By-product plants associated with
the integrated iron and steel industry produce blast-furnace coke and
are generally located at the steel-plant sites. Coke plants producing
coke for sale to the gray iron foundry industry, steel industry, and
other industries are called "merchant coke producers" and their
product is called "merchant coke". Most coke plants are located in
the northeastern United States (north of the Ohio River and east of
the Mississippi River) and in Alabama. The distribution of by-product
coke plants throughout the United States is shown in Figure 1.
Table 1 lists the number of companies and plants making blast-furnace
and merchant coke. Production of blast-furnace pig iron, the coke
consumed to make the pig iron, and the coke rate are shown in
Figure 2 for the years I960 through 1974.) ' The decrease in coke
rate (tonne coke/tonne pig iron or net ton coke/net ton pig iron), re-
sulting from the application of improved blast-furnace smelting
technology, permitted the production of an increasing amount of blast-
furnace pig iron in the period 1960-1974 with little increase in coke-
plant capacity.
-------
Figure 1. Distribution of coke plants in the United States
TABLE 1. BY-PRODUCT COKE PLANTS
Type of Coke
Produced
Companies Plants Batteries Coke Ovens
Blast-furnace coke
Merchant coke
Total
20
13
33
44
18
62
169
38
207
10, 733
2, 015
12, 748
-------
in
I 10
105
100
95
90
85
80
75
70
65
60
55
50
45
PIG IRON PRODUCED
I I I I I I I I I I I
I960
1965
1970
1975
YEAR
Figure 2. Blast-furnace pig iron produced, coke consumed, and
coke rate in the U. S. integrated iron and steel industry
-------
III. COKE-OVEN CHARGING EMISSIONS
Emissions generated during the charging of coke ovens are caused by
the following factors'2':
(1) Coal entering an oven rapidly occupies about 90 per-
cent of the space in the oven, displacing the air (or
other atmosphere) present in the empty oven. Much
of the displaced air may rush out through open
charging ports, carrying with it particulate and
other matter.
(2) Conventional blends of coals for coking contain about
8 percent moisture. Some of the moisture in the
newly charged coal immediately comes into contact
with the incandescent walls and floor of the oven,
and is flash vaporized. For each 0. 1 percent of
moisture vaporized from the coal, the volume of
steam produced at 260 C (500 F) is about 1. 7 times
the volume of the coal. This steam exiting through
the charging ports carries particulate matter into
the atmosphere.
(3) The coal itself is susceptible to thermochemical
breakdown as soon as it has become heated to over
260 C (500 F). Smoke, tar vapors, and gases formed
by these pyrolysis reactions can be emitted to the
atmosphere.
Characterization of emissions generated during the charging of coal
to coke ovens is difficult, primarily because of the problems asso-
ciated with collecting samples during the charging operation. Reports
have been published pertaining to the characterization of emissions
found on the top of coke batteries, along the coke-battery benches,
f^ — "7\
and on the ground near coke batteries.^0 '' Only one published re-
port has been located pertaining to the sampling and analysis of
-------
emissions during charging of a coke oven. (8) It was a result of work
sponsored by the U. S. Environmental Protection Agency and conducted
at an operating steel-plant coke battery. It supplemented research
work sponsored jointly by the U. S. Environmental Protection Agency
and the American Iron and Steel Institute on the development of a new
larry car and an improved coal-charging procedure for coke batteries
having only one gas-collecting main. (9) The new device is often
called the AISI/EPA larry car. The coke battery used in the research
had 79 ovens, each capable of coking 15.0 tonnes (16. 5 net tons) of
coal.
Gaseous and particulate emissions were collected during the research
work on the AISI/EPA larry car. The emissions were collected by
means of a special shroud around each drop-sleeve and charging hole.
The major gaseous emissions measured were: total hydrocarbons,
carbon monoxide, carbon dioxide, nitrogen oxides, sulfur dioxide,
hydrogen sulfide, methane, ammonia, phenol, and cyanide. The size
distribution of the particulates was determined and they were analyzed
for tar content. The reported average volumes of some of the gases
emitted during charging are listed in Table 2.*"' Analyses of the
TABLE 2. VOLUMES OF GASES EMITTED DURING CHARGING OF
15. 0 TONNES (16. 5 NET TONS) OF COAL
Standard Larry Car AISI/EPA Larry Car
Constituent
Total hydrocarbons
Carbon monoxide
Carbon dioxide
Nitrous oxide
Other nitrogen oxides
std cu m
0.96
0. 50
0. 83
0.002
0.003
std cu ft
33.8
17.5
29.4
0.08
0. 11
std cu m
0. 83
0.26
0. 13
0.0002
0.001
std cu ft
29. 1
9.0
4.7
0.006
0.05
gaseous constituents measured are given in Table 3.''' The size dis-
tribution of particulates collected during the various tests is shown in
Figure 3.^°' It was not possible to determine the unit weight of emis-
sions, i.e., grains per tonne (pounds per net ton) generated during
-------
TABLE 3. MEASURED CONSTITUENT CONCENTRATIONS IN GASES EMITTED DURING
THE CHARGING OF 15.0 TONNES (16.5 NET TONS) COAL
Standard Larry Car'
Constituent
Ammonia
Carbon dioxide
Carbon monoxide
Cyanide
Hydrogen sulfide
Nitrous oxide
Other nitrogen
oxides
Phenol
Pyridine
Sulfur dioxide
Total hydrocarbons
Unit
ppm
percent
percent
ppm
ppm
ppm
ppm
ppm
ppm
ppm
percent
Maximum
130.6
8.1
3.76
16.5
42.5
336
484
31.1
BDL
232.5
13.98
Minimum Average
BDL* . **
0.0 0.5
0.0 0.69
BDL **
BDL **
0.0 15.6
0/0 38.9
BDL **
BDL **
BDL **
0.0 1.6
AISI/EPA Larry Car
Maximum
BDL*
1.5
2.2
BDL
BDL
20.3
70.2
BDL
BDL
25.4
11.4
Minimum
BDL"
0.0
0.0
BDL
BDL
0.0
0.0
BDL
BDL
BDL
0.0
Average
**
0.11
0.21
##
**
0'. 13
9,6
«
"
#*
0.59
* BDL - Below detectable limits.
** Average could not be computed.
-------
800
600
400
200
§ 100
| 80
cc
HI
H
O
h-
DC
60
40
20
I
0.8
0.6
0.5
1 1 1 I 1 1 1 I
LOWER LIMIT
UPPER LIMIT
i i
i
J_
I
J_
0.01 0.2 2 10 20 40 60 80 95 99 99.9 99.99
PERCENT OF SAMPLE GREATER THAN INDICATED SIZE
Figure 3. Size distribution of particulates collected during
charging 15.0 tonnes (16.5 net tons) of coal with
the AISI/EPA larry car
10
-------
charging because of the intermittent time intervals used for collecting
samples.
One investigator used microscopic techniques to identify and charac-
terize emissions generated by a coke plant.''*' Identification of high-,
medium-, and low-volatile coals which comprised the coals charged
into the coke ovens was possible without difficulty. A particulate
attributed specifically to the charging of coal into the ovens was
designated as "coke balls". Coke balls were oval in shape and had
an unusual network-like internal structure. The formation of coke
balls was attributed to the thermal conditions encountered by coal
particles as they are carried through the hot zone of an oven and out
the adjacent open charging holes.
11
-------
IV. PREHEATING OF COKING COAL
Larry-car-free charging of coke ovens did not originate as a method
for controlling emissions during the charging operation. It was
originated as a method for charging preheated coal into the ovens.
The use of preheated coal in the production of coke has an important
advantage to the coke-plant operator — an increase in production.
The general amount of increase in productivity by preheating is illus-
trated in Figure 4.(10~29) The increase in coke-oven productivity is
affected by the bulk density of the coal and the preheat temperature
at the time the coal is charged to the oven. In addition to the increase
in productivity, the use of preheated coal has other advantages: (1)
lower quality metallurgical coals can be used in the coal blend, (2)
the amount of energy required to make coke is lowered, and (3) pre-
heated coal is so fluid that it does not require leveling of the coal
charge in the oven.
Many coals and coal blends have been evaluated for their response to
preheating. \* 1-36) jn almost all cases the coke produced from pre-
heated coals had properties equal to or better than the coke made
from similar wet-coal blends. The use of lower quality metallurgical
coals has been quite thoroughly evaluated.^ > ^ > ^' The use of such
a coal in a coking-coal blend was one of the factors in the decision
of a midwest United States steel company (Inland Steel) to install a
coke battery that would use a preheated coal charge. (^9)
There has been much discussion pertaining to the total amount of
energy needed to produce 1 ton of coke by the use of preheated coal,
as compared with conventional coking using wet coal. No reports
have been made of full-scale tests on commercial coke batteries to
determine the total energy consumed in each method of making coke.
However, estimates have been made comparing the energy require-
ments of the two methods. The preheating of coal charges was re-
ported to provide a potential energy saving of 116 to 349 E+06 joules
per tonne (27, 800 to 83, 300 kilogram-calories tonne, 100, 000 to
300, 000 Btu per net ton) of coke produced. (37)
13
-------
65
60
55
50
COKE-OVEN VOLUME, cubic feet
500 1000
1500
8 45
ID
>
0 40
cc
LU
I35
o
§30
i
25
20
I 5
I 0
1 i i ii | r
PREHEATED COAL
10 15 20 25 30 35 40
COKE-OVEN VOLUME, cubic meters
- 15
45
Figure 4. Possible increase in coke-oven productivity
by preheating coal
14
-------
The fluid characteristics of preheated coal permit it to achieve a
uniform profile in the oven. Profiles for wet coal, dry coal, and
preheated coal are illustrated in Figure 5. (38) -phe coai was charged
to a 10-tonne (11-net ton) coke oven, using a larry car. The wet coal
had moisture contents between 9. 1 and 10.4 percent, the dried coal
had moisture contents between 2.0 and 2. 8 percent, and the preheated
coals were charged to the oven at temperatures between 180 and 200 C
(356 and 392 F). (
3.7 METERS (12 FEET)
WET COAL - LEVELED
3.7 METERS (12 FEET)
DRY COAL - NOT LEVELED
3.7 METERS (12 FEET)
PREHEATED COAL - NOT LEVELED
Figure 5. Profile of wet, dried, and preheated coal, top
charged to a 10-tonne (11-net ton) coke oven
with a conventional larry car
Another report concerning the self-leveling properties of preheated
coal, indicated a profile in a 4.2-meter (13.8-foot) coke oven, capable
of coking 13.8 tonnes (15.2 net tons) of coal, as shown in Figure 6.' '
The preheated coal was charged with a conveyor system through the
two charging ports indicated.
This self-leveling property of preheated coal eliminates the require-
ment for a leveling bar and thus the need for a leveling-bar door,
which is a continued source of emissions during the leveling operation
for conventional charging of wet coal.
15
-------
CHARGING PORTS USED FOR CHARGING
PREHEATED COAL
0
45678
COKE-OVEN LENGTH, meters
I
11
12
Figure 6. Profile of preheated coal charged to a
13. 8-tonne (15. 2-net ton) coke oven
16
-------
V. LARRY-CAR-FREE CHARGING OF COKE OVENS
The high-fluidity characteristics of preheated coal and the necessity
of minimizing the loss of heat during transport from the heating units
to the ovens have resulted in the development of two systems that are
used to charge coke ovens without the use of larry cars. One system
was developed in the United States and the other in West Germany.
The process developed in the United States is called the "Coaltek
system"'-^"', and the process developed in West Germany is called
the "Precarbon process"'^^). A third system which uses a covered
larry car to charge preheated coal was developed by Simon-Carves,
Ltd., England, A prototype is installed at the British Coke Research
Association experimental coke plant. (26) This is known as the
"Simcar system" and is included to provide a complete picture of the
systems available for charging preheated coal.
THE COALTEK SYSTEM
The Coaltek system, which employs pipelines to convey the preheated
coal from the preheaters to the coke ovens, was developed by the
Semet-Solvay Division, Allied Chemical Company. The process is
marketed today by Coaltek Associates.
Preheater
Research work started in the 1950's resulted in 10 patents for the
Coaltek process. (42) The first, U. S. Patent No. 3, 047, 473 filed in
September 1956, and granted in July 1962, was concerned with the
preheating of coal and the basic concepts of pipeline charging. '^3)
The preheating system used in the Coaltek process was developed by
the Research Center for the French coal industry and is known as the
"Cerchar" preheater.' > ^' A flow diagram of the Cerchar
17
-------
preheating system used with the Coaltek process is shown in Figure
7=(46) This figure shows duplicate preheating systems feeding one
distribution system (at the center of the figure).
DDIVERTER
HARGE / \/ VALVESTO
BINS
Figure 7. Preheating system for the Coaltek pipeline charging
process for coke ovens
Ahead of the preheating system for the Ironton installation shown in
Figure 7, wet coal is withdrawn from the coal bunkers by screw con-
veyors and is discharged onto a belt conveyor. A magnet located
over the conveyor belt is used to remove any tramp iron. The coal
is then screened to 2.5 cm (1 inch), and the oversize crushed to less
than 2.5 cm (1 inch), which is then recombined with the undersize
from the screen and discharged to the preheater feed hopper.
18
-------
Coal from the feed hopper is fed into the preheaters by variable-speed
screws. The wet coal, fed into the flash-drying entrainment section,
conies into contact with a stream of hot low-oxygen gas, where it is
partially dried and carried by the gas up to a dilute-phase fluidized
bed. A rotating swinghammer crusher located in the lower part of
the fluidized-bed chamber breaks the larger pieces of coal so that
the largest size is about 6 mm (1/4 inch), with 90 percent passing
3 mm (1/8 inch). The rotating swinghammer also provides rapid
dispersion and agitation of the coal particles in the gas stream. All
preheated coal is transported upward by the gas stream and is re-
covered in conventional cyclone separators. About 90 percent of the
coal is recovered in the primary cyclone and the remainder in four
secondary cyclones arranged in parallel. ^ -^ Figure 8 is an illus-
tration of the external appearance of such a preheating system,
Pipeline Charging System
Hot coal from the bottom of the cyclones is conveyed to a hot-coal
receiving bin from where it is conveyed intermittently, as needed, to
a higher measuring bin before being transported to the ovens. The
coal is conveyed through a pipeline to the ovens whenever an oven is
ready for charging. The pipeline manifold, illustrated in Figure
contains individual valves for each oven, in a battery. Coal is trans-
ported through the pipeline by means of steam jets spaced along the
pipeline. A steam jet is illustrated in Figure 10.' ' The oven
operator activates the charging sequence from a control panel located
at the end of the battery. When the predetermined amount of coal has
been charged, the valve at the outlet of the measuring bin is automati-
cally closed and the feeder is stopped. After a short time interval to
provide for clearing of the pipelines and discharging the remaining
coal into the oven, the flow of steam for conveying the coal through
the pipeline is lowered to a standby rate.* '
The gas from the outlet of the secondary cyclones is divided into two
streams. The excess gas passes through a wet scrubber and is ex-
hausted to the atmosphere. The recycle gas is increased in pressure
by a recycle blower and returned to the combustion chamber where
it is used to temper and add to the flow of combustion gases passing
up through the preheater. Automatic controls are used to adjust the
flow of recycle gas to that required to maintain the desired flow of
gases through the preheating column. (^5, 28)
19
-------
Figure 8. Coaltek pipeline-charging preheating system
20
-------
MAIN CHARGING PIPE-
STEAM LINES
-INDIVIDUAL OVEN PIPES
Figure 9. Coaltek system pipeline manifold for charging
of coke ovens
W/////////////////X
COAL FLOW
Y////////////7///,
Y////////////////,
Figure 10. Section and top view of a steam jet in the
Coaltek system pipeline
21
-------
Utility Consumption
Gas consumption for preheating and carbonizing coal blends contain-
ing 8 percent moisture has averaged about 90 percent of that required
for carbonizing wet coal in a conventionally charged coke oven.
Total steam requirements are reported to vary from 25 to 32 kilo-
grams per tonne (50 to 65 pounds per net ton) of preheated coal. The
steam is used primarily for heating pipes in various parts of the
system, pressurizing the metering (charging) bin, conveying the coal
through the pipelines, and purging the coke-oven entry pipes. Coal
is pipelined to the ovens at a ratio of 100 kilograms of coal per kilo-
gram of steam (100 pounds of coal per pound of steam). (", 28)
Preheater electrical-energy consumption varies with the operating
rate, which is controlled primarily by the requirements of the recycle
blowers. At Ironton the electrical-energy requirements of the re-
cycle blowers vary from 6. 8 kilowatts per tonne at 18. 1 tonnes per
hour to 3.2 kilowatts per tonne at 36.3 tonnes per hour (6.2 kilowatts
per net ton at 20 net tons per hour to 2. 9 kilowatts per net ton at 40
net tons per hour). All other electric energy, including requirements
for the pipeline system, amounts to 6.6 kilowatts per tonne (6.0 kilo-
watts per net
Clean-water consumption is about 9500 liters (2500 gallons) per day.
The wet scrubbers use about 330 liters (87 gallons) per minute.
Coaltek Installations
Coaltek system installations throughout the world are listed in
Table 4. (25, 28, 29)
Retrofit Capability
As with any new process or system, when there is a possibility for
increasing production and/or providing improved control of emissions,
the possibilities of retrofitting the process or system to existing facil-
ities becomes an important factor to the steel-plant operator. Such
is the case with pipeline charging of coke ovens.
22
-------
RELATIVE POSITION OF FIRST CROSSOVER IN A
MODERN BECKER 6-METER AND HIGHER OVEN
COALTEK PIPELINE
RELATIVE POSITION OF FIRST CROSSOVER
IN OLDER BECKER FLUE OVENS
/777777/7 / 777 / 77 7777
Figure 11. Location of pipeline for existing coke ovens
23
-------
TABLE 4. COALTEK SYSTEM INSTALLATIONS
Coal Capacity
Ovens, Startup per Oven Preheaters, Capacity per Preheater
Company and Location number Year tonnes net tons number tonnes/hr net tons/hr
Alabama Byproducts Corp. 78 1974 24.9 27.5 2 72.'5 80
Tarrant, Alabama
Inland Steel Company 56 1974 29.7 32.7 2 90.7 100
East Chicago, Indiana 69 1977 33.4 36.8
Jones & Laughlin Steel Corp. 56 1976 29.7 32.7 2 90.7 100
Aliquippa, Pennsylvania
Semet Solvay Division,
Allied Chemical Corp.
Detroit, Michigan 70 1973 24.9 27.5 2 72.5 80
Ironton, Ohio 24 1970 12.7 14.0 1 36.3 40
British Steel Corp.
Teeside, England 66 1976 24.9 27.4 3 79.8 88
66 1977 24.9 27.4 2 79.8 88
Scunthorpe, England 75 1976 26.1 28.8 3 90.7 !00
Norbottens Jarnverk Aktiebolag 54 1976 35.7 39.4 3 72.5 80
Lulea, Sweden
SACILOR 12 1974 11.7 13.9 1 13.0 14.
Carling, France
Exploratory engineering studies have been made on the possibilities of
installing the Coaltek system on existing coke batteries. The major prob-
lem has been the angle of the pipeline entering the oven. On a new battery
designed and constructed for pipeline charging, the angle of the downward-
sloping pipe can be 10 to 60 degrees from horizontal. On existing coke
batteries, the location of the first crossover flue presents a problem in
the location of the entry pipeline. Research work has shown that the coal-
entry pipeline can be positioned at 60 degrees from horizontal as shown
in Figure 11.
THE PRECARBON SYSTEM
The Precarbon system uses an enclosed Precarbon chain conveyor to
charge preheated coal into conventional coke ovens. It was developed
jointly by Didier Engineering GmbH and Bergbau-Forschung GmbH,
both of Essen, West Germany. (47) The preheater is known as a "Pre-
carbon Preheater".
24
-------
Installation of the Precarbon plant began in 1970 and the preheating
system was placed into operation in 1971. (40) A flow diagram for the
Precarbon process is shown in Figure 12. (48)
Al
i
WATER INLET
Figure 12. Flow diagram for the Precarbon process
Operation of the Precarbon System(48)
The Precarbon system is characterized by the combination of a vertically
arranged 2-stage flash-drying system for the thermal pretreatment of
coking coal with a special chain conveyor arranged above the batteries
for charging the ovens.
The basic arrangement of the system is shown in the process diagram.
The data used for illustration in the following discussion are based on
25
-------
a coal with. 10 percent moisture content which has been preheated to
200 C (392 F). These figures will vary in relation to the moisture con-
tent and the desired preheating temperature.
The wet coal is conveyed to the feed bunker by means of a conveying
system, is measured by metering equipment, and is fed to the first
flash leg (the drying stage) by means of a centrifugal feeder. The coal
is dried to 2 percent moisture and heated to about 80 C (176 F) by hot
carrier gases which have been cooled down in the second stage to about
280 C (536 F). At the top end of the drier leg, the predried coal is
separated in a cyclone and delivered by gravity to the bottom of the
second flash leg (the preheating stage) into which it is fed by a centrif-
ugal feeder. The predried coal is treated with heated carrier gas at
550 C (1022 F) generated in a combustion chamber and an addition of
recycled hot gases, so that the coal is completely dry at the upper end
of the preheating leg at a temperature of about 200 C (392 F).
After separation in a cyclone, the thermally treated coal can be treated
with a Precarbon additive in order to reduce carryover when "on-the-
main" charging is used and also to achieve the desired bulk density. The
coal is then stored in an intermediate bunker system from where it is
conveyed to a subsequent measuring bin having the capacity of one oven
charge.
The hot carrier gas is generated in a combustion chamber by burning
gaseous fuels such as blast-furnace gas, coke-oven gas, and natural
gas. Recycled off-gases are added to the gas to reduce its temperature
to about 550 C (1022 F). In order to benefit from the counterflow prin-
ciple (i.e. , to utilize relatively low temperatures in the second stage),
the hot flue gas is first introduced to the second stage (preheating stage)
to thermally treat the predried coal. Since the hot carrier gas contains
fine dust after passing through the first-stage cyclone, it is cleaned in
a double cyclone. The coal-carrier gas mixture is then fed to the
second stage. After passing the main blower, which circulates the car-
rier gas, a part of the gas is recycled to the combustion chamber and
the remaining part is thoroughly cleaned in a heavy-duty dust collector
and released to the atmosphere.
The blower arrangement automatically creates the following pressure
distribution in the plant. Minimum pressure is maintained at the cyclone
of the drying stage. The drying stage itself creates a pressure loss of
about 300 mm (11.8 in. ) w.g. as does the preheating stage, so that a
26
-------
pressure of approximately ±0 mm w. g. exists in the combustion
chamber.
The process of thermal pretreatment is governed by three control sys-
tems and is fully automatic. In order to prevent overheating of the
system and of the coal, the flue-gas temperature at the end of the
second stage is used as a control point. For safety reasons, the addi-
tion of combustion air is controlled by this control point. In a separ-
ate control circuit, the gas addition with the specified excess air rate
is controlled. A third control circuit regulates the amount of recycled
off-gas to the combustion chamber so that at the entrance to the second
stage, the pressure is neither below or above the set value. Varia-^
tions in the moisture content of the coal charge and variations in the
throughput thus are automatically controlled so that at any time a
satisfactory operation at optimum conditions is maintained.
In case of emergency shutdown, the coal in the flash legs drops into
water seals at the bottom of the individual stages from where it can
be easily removed.
The thermally pretreated coal from the preheating plant is conveyed
by parallel operating chain conveyors to an oven for charging and is
charged "on-the-main" through a chute buggy, without atmospheric
pollution. Each chain conveyor charges coal to two charging holes
through individual pant legs. The Precarbon process requires only
two charging holes. In case wet coal is to be charged with a chain
conveyor, four charging holes are used.
The operational sequence of the Precarbon charging process is as
follows:
(1) Charging is first made through the two inside
charging holes by setting a flap in the pant leg.
The charge level in the oven is measured by
Precarbon level probes.
(2) When the desired charge level is reached below the
charging holes, which is measured by level probes,
the flap is automatically switched.
(3) Charging is continuing through the two outer charg-
ing holes.
27
-------
(4) The chain conveyors are switched off on response
from the level probes and the probes are automati-
cally retracted from the oven. Levelling of the
oven charge is eliminated with the Precarbon
process.
The coal remaining in the chain conveyor between two oven charges is
transported back to the battery charging station, by reversing mech-
anizms on the chain conveyor, and is again charged in the following
cycle. (The chain conveyor has a continuous intermediate bottom.)
Since levelling is not required by the Precarbon process, the chute
buggy and coke-pushing machine are independent of each other. For
this reason, any desired carbonization cycle may be used.
A measuring bin is available which permits batch charging of ovens,
instead of measuring the coal volume by the level probes. In the case
of batch charging, the coal quantity is weighed in the measuring bin
and discharged to the empty chain conveyors, transported to the oven,
and the entire quantity of weighed coal charged to the oven. However,
such practice requires more time.
In case of failure of the preheating plant or in reducing the coke
throughput from the ovens, the Precarbon process permits the charg-
ing of wet coal by means of the chain conveyor and the chute buggy.
It is then necessary to install a bunker system (storage and measuring
bunker) for the wet coal above the chain conveyor. While thermally
pretreated coal may, in emergency case&, be charged through one
chain conveyor, both chain conveyor systems must be used when
charging wet coal.
When charging wet coal, the two exterior charging holes are charged
first. When the desired level of coal is reached, the changeover flap
is automatically switched and the two inside charging holes are filled,
until the level probes respond and are retracted. During the subse-
quent levelling, coal is charged through one inside charging hole only
and the period is limited by a time relay (i.e., during levelling, the
chain conveyor operates for a short preset period).
On existing plants it is often necessary to modify the Precarbon pro-
cess so that only one chain conveyor in connection with a pant leg is
used. Ovens up to 12 meters long can be operated without difficulty
in this way.
28
-------
Precarbon System Installations
In addition to the prototype installation at Ruhrkohle AG, Essen, West
Germany, Precarbon systems have been installed on new coke batter-
ies listed in Table 5.(48)
TABLE 5. PRECARBON SYSTEM INSTALLATIONS
Company and
Location
U. S. Steel
Corporation,
Gary, Indiana
Ovens,
number
57
57
Startup
Year
1975
1976
Coal
Capacity
per Oven
tonnes
net tons
Systems,
number
3
3
Nippon Steel 1977 3
Corporation, 1977 3
Oita, Japan
Retrofit Capability
There have been no specific reports in regard to the retrofit capability
of the Precarbon system. However, because the prototype Precarbon
system was placed into operation in 1971 on five experimental coke
ovens constructed in 1968, capability for retrofit is obvious.
THE SIMCAR SYSTEM
Although the Simcar system does employ larry cars for charging of
preheated coal in coke ovens, it is included in this report to provide
full coverage on methods that can be used for charging preheated coal.
The Simcar system, developed by Simon-Carves Ltd., England, was
first installed at the British Coke Research Association Center at
Chesterfield, England.
29
-------
Preheater
The coal preheater used with the Simcar system is the Rosin preheater.
The preheater at the British Coke Research Association Center experi-
mental ovens was placed into operation in 1967.' '
Simcar Charging
The Simcar system employs a special larry car to transport the pre-
heated coal from the hot-coal bunkers to the coke ovens. The larry
car includes a scrubber to control emissions during charging, with
the addition of rotating seals on the tops of the coal hoppers to prevent
the emission of particles of heated coal from the hoppers and to mini-
mize heat losses.
Simcar System Installations
Coke-oven batteries using the Simcar system for the charging of pre-
heated coal are given in Table 6. (26, 37, 50)
TABLE 6. SIMCAR SYSTEM INSTALLATIONS
Company and Location
Capacity per
Pre- Preheater
Ovens, Startup Coal Capacity heaters, tonnes/ net tons/
number Year tonnes net tons number hr hr
British Coke Research Assoc.
Chesterfield, England
British Steel Corp.
Brookhouse, England
Anglo American Corp.
Africa
NA 1967 10.0 11.0
NA NA 13.6 15.0
NA NA
5.5
55 60.6
55 60.6
ISCOR
Pretoria, South Africa
NA NA
88 97.0
NA = Not available.
30
-------
Retrofit Capability
The retrofit capability of the Simcar system is illustrated by the fact
that it was installed on an existing coke battery, the Brookhouse
battery in England.
LARRY-CAR-FREE CHARGING AIR-
POLLUTION CONTROL POTENTIAL
The true larry-car-free systems for charging coal to coke ovens have
the potential for eliminating emissions to the atmosphere. Since the
systems are enclosed, there should be no possibility for emissions
unless there is some type of major breakdown in the systems that
could not be corrected in a minimum amount of time. Under routine
operating conditions, emissions should be completely absent. Direct
measurements of emissions from charging operations have not been
made successfully so it is impossible to state what the specific reduc-
tion of overall coke-oven emissions would be in milligrams per tonne
of coal charged or tonne of coke pushed (grains per net ton of coal
charged or grains per net ton of coke pushed).
The larry-car-free charging systems discussed in this report all are
used to charge preheated coal to the coke ovens. Some emissions to
the atmosphere may occur because of the overloading of the scrubbers
that are used to clean off-gases from the drying units. In such cases,
there may be an intermittent emission of pollutants to the atmosphere,
which can be corrected by adjustments to the coal-drying system.
31
-------
VI. REFERENCES
(1) Annual Statistical Reports, American Iron and Steel Institute,
1960-1974.
(2) Barnes, T. M., Hoffman, A. O., and Lownie, H. W., Jr.
Final Report on Evaluation of Process Alternatives to Improve
Control of Air Pollution from Production of Coke. PB No.
189,266. Battelle's Columbus Laboratories for National Air
Pollution Control Administration, Department of Health, Educa-
tion, and Welfare, Division of Process Control Engineering,
111-14, January 31, 1970.
(3) Group of Experts on Coking, Economic Commission for Europe,
Air Pollution by Coking Plants. ST/ECE/COAL/26, United
Nations, 65, 1968.
(4) Herrick, R. A., and Benedict, L. G. A Microscopic Classi-
fication of Settled Particulates Found in the Vicinity of a Coke-
Making Operation. Journal of the Air Pollution Control Asso-
ciation. 16:325-338, May 1969.
(5) Masek, V. The Composition of Dusts From Work Sites of Coke
Ovens. Staub-Reinhaltung der Luft (In English). 30:34-37, May
1970.
(6) Smith, W. M. Evaluation of Coke Oven Emissions. Yearbook of
the American Iron and Steel Institute. 163-179, 1970.
(7) Masek, V. New Methods for Evaluation of Solid Dust Particles
in the Atmosphere of Coke Oven Plants. Hutnicke Listy. 761-765,
1973.
(8) Stoltz, J. H. Coke Charging Pollution Control Demonstration.
EPA-650/2-74-022. Office of Research and Development, U. S.
Environmental Protection Agency. 325, March 1974.
33
-------
(9) Bee, R. W., et al. Coke Oven Charging Emission Control Test
Program. EPA-650/2-74-062. Office of Research and Develop-
ment, U. S. Environmental Protection Agency. 164, July 1974.
(10) Longenecker, C. Armco Steel Corporation, Middletown Works,
Producers of Steels for Over Half a Century. Blast Furnace
and Steel Plant. 50:746-749, August 1962.
(11) Longenecker, C. Armco's Houston Works — Sheffield Division -
Both Serves the Southwest and Operates on Its Resources. Blast
Furnace and Steel Plant. 49:741-744, August 1961.
(12) Ess, T, J. A Decade of Expansion at Bethlehem's Sparrow
Point Plant. Iron and Steel Engineer. 26:B3-B5, April 1949.
(13) Crawford, C. C. CF&I Steel at Pueblo. Iron and Steel Engineer.
39:P4-P7, May 1962.
(14) Ess, T. J. Inland Steel Company. Iron and Steel Engineer.
36:17-18, September 1959.
(15) Ess, T. J. Jones & Laughlin . . . Cleveland Works. Iron and
Steel Engineer. 36:88-89, February 1959.
(16) Ess, T. J. The Story of Granite City Steel. Iron and Steel
Engineer. 45:GC6, October 1968.
(17) Lassen, E. G. The Wisconsin Steel Works of the International
Harvester Company. Blast Furnace and Steel Plant. 52:929,
October 1964.
(18) Rueckel, W. C. Modern Wilputte High Capacity Ovens. AIME
Ironmaking Proceedings. 25:25-29, 1966.
(19) Strahn, T. M. , and Wolfe, F. C. Design and Operation of
5-Meter Coke Ovens at Wisconsin Steel Works. AIME Ironmak-
ing Proceedings. 29:2-7, 1970.
(20) Fodor, R. J. New Coke-Oven Facilities at Great Lakes Steel.
Iron and Steel Engineer. 48-79-84, September 1971.
34
-------
(21) Mack, L. H. Inland's No. 10 Battery - Twenty-Foot Giant in
the Midst of Twelve Footers. AIME Ironmaking Proceedings.
30:82-91, 1971.
(22) McCord, J. C. Lackawanna's'Experience Operating No. 9 Coke
Oven Battery. AIME Ironmaking Proceedings. 30:94-101,
1971.
(23) Kashay, A. M. Armco's Middletown Works. A Blend of In-House
Knowledge and Supplier Competence. Iron and Steel Engineer.
51:M48, September 1974.
(24) Cameron, A. M. , Sagle, G. W., and Farkas, N. R. A Full-
Scale Test on Algoma's Coal — Normal vs. Preheated Coal
Charging. Iron and Steel Engineer. 48:61-62, December 1971.
(25) Marting, D. G., and Davis, R. F'. Coaltek System for Preheat-
ing and Pipeline Charging of Coal to Coke Ovens. AIME Iron-
making Proceedings. 31:174-182, 1972.
(26) Pater, V. J., and Webster, J. Methods of Charging Preheated
Coal. Developments in Ironmaking Practice. Iron and Steel
Institute Publication No. 152:53-62, 1973.
(27) Knoerzer, J. J.' Preheating and Pipeline Charging of High
Illinois Coal Blends for By-Product Coking. AIME Transactions
of the Society of Mining Engineer. 258:42-46, 1975.
(28) Davis, R. F. , Jr., and Cekela, V. W. Pipeline Charging Pre-
heated Coal to Coke Ovens. AIME Ironmaking Conference.
34:339-349, 1975.
(29) McMorris, C. E. Inland's Preheat-Pipeline Charged Coke Oven
Battery. AIME Ironmakmg Conference. 34:330-338, 1975.
(30) Beck, K. G., et al. A New Technique for Preheating Coking
Coal Blends for Carbonization in Slot-Type Recovery Ovens.
AIME Ironmaking Conference. 31:185-190, 1972.
(31) Smith, F. W., et al. Better Coke by Thermal Pretreatment of
Coal: Results for Illinois No. 6-, Pittsburgh-, and Mason-Bed
Coals. U. S. Bureau of Mines Report of Investigations 5418:26,
1958.
35
-------
(32) Perch, M., and Russell, C. C. Preheating Coal for Carboni-
zation. Blast Furnace and Steel Plant. 47-591-597, June 1959.
(33) Dowson, J. W., and Gadsen, W. R. The Drying and Preheating
of Coal for Coke Ovens. Blast Furnace and Steel Plant. 54:385-
390, May 1966.
(34) Jackman, H, W., and Helfinstine, R. J. Drying and Preheating
Before Coking. Blast Furnace and Steel Plant. 57:119-123,
February 1969.
(35) Alderman, L. , and Chambers, R. H. Preheating and Charging
Coal to Coke Ovens. AIME Ironmaking Proceedings. 31:193-
198, 1972.
(36) Graham, J. P. Application of Preheating to British Coals.
AIME Ironmaking Proceedings. 30:361-379, 1971.
(37) Potential for Energy Conservation in the Steel Industry. PB
244097/AS, Battelle's Columbus Laboratories for Federal
Energy Administration, V-3, May 30, 1975.
(38) Graham, J. P., Pater, W. J., and Lee, G. W. Preheating of
Coals Prior to Carbonization. Coke in Ironmaking. Iron and
Steel Institute Publication No. 127:53-62, 1970.
(39) Marting, D. G., and Blach, G. E. Coke-Oven Charging, Part 2:
Charging Preheated Coal to Coke Ovens. Coke in Ironmaking.
Iron and Steel Institute Publication No. 127:73-76, 1970.
(40) Beck, K. G. The Precarbon Process - Blast Furnace Coke
From Preheated Coal. Paper presented to the Midlands Divi-
sion of the Coke Oven Managers Association:23, April 12, 1973.
(41) Byproduct Coke Ovens Fight Off Challenges, Continue to Reign
Over Steelmaking Scene. 33 Magazine. 13:34, October 1975.
(42) Coke-Oven Controls: Complex, Costly and Controversial.
Chemical Week. 117:28-29, November 26, 1975.
(43) Schmidt, L. D. Drying, Preheating, Transferring and Carboniz-
ing Coal. U. S. Patent No. 3,047,473:13, July 31, 1962.
36
-------
(44) Foch, P. Dry Charging and Preheating of Coking Blends: Devel-
opment of the Processes. Coke in Ironmaking. Iron and Steel
Institute Publication No. 127:47-52, 1970.
(45) Marcellini, R0, and Geoffroy, J. Development of a New Pro-
cess to Preheat Coal Blends Used for Coking. AIME Ironmaking
Proceedings. 31:166-173, 1972.
(46) Marting, D. G. , Coaltek Associates „ Communication to Varga,
J., Jr. BatteLle's Columbus Laboratories. December 20, 1974.
(47) PRECARBON - Coal Preheating and Chain Conveyor Charging
System. Didier Engineering GmbH. 7, August 1974.
(48) Eismann, D. E. Kaiser Engineers, Inc. (Didier Engineering,
GmbH). Communication to Varga, J., Jr0 Battelle's Columbus
Laboratories. March 19, 1976.
(49) Alderman, L. , and Chambers, R. H. Preheating and Charging
Coal to Coke Ovens. AIME Ironmaking Proceedings. 31:193-
201, 1972.
(50) Bruce, J., McN., and Staniforth, W. Some Aspects of Experi-
ence on the Brookhouse Project. Developments in Ironmaking.
Iron and Steel Institute Publication Number 152:63-72, 1973.
37
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-7 6-099
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Larry-Car-Free Charging of Coke Ovens
5. REPORT DATE
April 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
John Varga, Jr.
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Battelle-Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
10. PROGRAM ELEMENT NO.
1AB015; ROAP 21AQR-042
11. CONTRACT/GRANT NO.
68-02-1323, Task 39
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Task Final; 10/75-2/76
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES Task officer for this rep0rt is R.C. McCrillis, Mail Drop 62,
Ext 2557.
. ABSTRACT
repOrt discusses advantages of preheating coal before charging it into
coke ovens , as an introduction to the use of charging systems that do not use larry
cars. Two larry-car-free systems are discussed. A third system, which uses a
larry car for charging preheated coal, is also discussed to provide more complete
coverage of the charging of preheated coal. The two larry-car-free charging systems
offer good possibilities for eliminating emissions generated during the usual method
of charging coke ovens with larry cars. (The report responds to Item AM-2-2 of the
Protocol of the First Working Meeting of the USA/USSR Task Force on Abatement of
Air Pollution from the Iron and Steel Industry. )
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Air Pollution
[ron and Steel Industry
oking
Coal
Heating
Air Pollution Control
Stationary Sources
Coke Oven Charging
Larry Cars
Coal Preheating
13B
11F
13H
2 ID
13A
8. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
46
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
39
------- |