status of environemtal pollution and its control in the coke oven

ENVIRONMENTAL MANAGEMENT IN THE BEE- HIVE
COKE OVEN PLANTS IN ASSAM AND MEGHALAYA: AN
OVERVIEW OF ISSUES AND MANAGEMENT PRACTICES
CENTRAL POLLUTION CONTROL BOARD
(MINISTRY OF ENVIRONMENT & FORESTS)
1.0
Introduction
Coke is a solid carbonaceous material produced by destructive distillation of low-ash
and preferably low-sulfur bituminous coal.
Coal is baked or distilled in ovens at
controlled temperature of about 12000C and coke is produced as a combustible residue
consisting of residual ash and fixed carbon and in the process, the impurities present in
coal, such as volatile matters (tars, oil and grease, etc), are driven off. It is considered
that levels of 26-29 % of volatile matter (VM) in the coal are good for coking purposes.
The process of distillation or baking at controlled temperature does not allow burning of
Carbon present in coal.
Coke derived from coal is generally grey, hard and porous. Coke, also known as Low
Ash Metallurgical Coke (LAMC), is used in Blast Furnace for steel manufacturing
industries. Coke acts both as reducing agent as well as a source of fuel to melt the iron
ores. Coke is also used in the ferro alloy, graphite and carbon black industries.
The caking behavior of coal is critical to coke making. Caking behavior is a unique
property of coal and is an essential property for coal used for coking. As a caking coal is
heated, it passes through a region where it becomes very plastic, softens, swells and
then re solidifies. The re-solidified residue is a cellular coke mass. Non caking coals, on
baking or distillation, do not form any cake but simply form a non coherent or weakly
coherent char.
Bituminous coals of high grade (low ash content and high caking index) are produced in
the coalfields of Assam (Makum Coalfield) and Meghalaya (Coalfields in Jaintia, Garo
and Khasi Hills). As there is good demand of the LAMC in India, in the past few years,
a large number of bee-hive coke oven plants have been set up in the states of Assam
and Meghalaya.
This study has been carried out to assess the status of environmental management in
the bee- hive coke oven plants in Assam and Meghalaya. The study overviews the
environmental issues of bee-hive coke oven plants and also recommend various
measures for better environmental management in the beehive coke oven plants.
1
2.0
Industry description
In the coke-making process, bituminous coal is fed into a series of ovens, which are
sealed and subsequently burnt at high temperature of about 12000C in an Oxygen (O2)
deficit atmosphere, typically in a cycle lasting for 24 to 36 hours. There are primarily
two (2) types of coke oven plants, viz., recovery type coke oven plants and bee-hive
coke oven plants (non recovery type). The characteristics of both the types of coke oven
plants are briefly discussed in the following sections.
2.1
Recovery type coke oven plants
In recovery type coke oven plants, low ash metallurgical coke (LAMC) as well as coke
oven gas is produced from suitable grades of coal by involving the pyrolysis process
(heating in absence of air). Coke breeze is also produced as a by-product in a coke
oven plant.
Coke oven gases, which are produced during the coking process, contain various
volatile compounds and these gases are further processed to recover combustible
gases and other bye-products like tar, ammonium sulfate, phenol, naphthalene, light oil,
sulfur, etc., and the gas is subsequently reused as fuel for heating the ovens.
Cooling of flue gases from coke oven plants is required to derive the bye-products.
Cooling of coke oven gases results in the formation of flushing liquor, which contains
tar. This flushing liquor and liquor from primary coolers are sent to a tar decanter.
Generally, with an electrostatic precipitator or suitable gas liquid separators, tar is
removed from coke oven gas. Ammonia liquor is also separated from the tar decanter
and sent to wastewater treatment after ammonia recovery.
Coke oven gas, after removal of tar, is further cooled in a final cooler and Naphthalene
is removed in the separator on the final cooler. Light oil is then removed from the coke
oven gas and is fractionated to recover Benzene, Toluene, and Xylene. A tar distillation
unit is generally installed in a non recovery type coke oven plant. The Claus process is
normally used to recover sulfur from coke oven gas.
2
During the coke quenching, handling, and screening operation, coke breeze is
produced. It is either reused on site (e.g., in the sinter plant) or sold off site as a byproduct.
2.2
Non-recovery type bee-hive coke oven plants
In non-recovery type coke oven plants, there is no provision for recovery of various
valuable products from the coke oven gases. All the coke oven gases are emitted as
flue gas. Low ash metallurgical coke (LAMC) is the main target product for this type of
non recovery coke oven plants. Coke breeze is the only bye-product in the non-recovery
type plant. Majority of coke oven plants operating in India are of non recovery type. All
the coke oven plants operating in Assam and Meghalaya are of non recovery type coke
oven plants. These plats are also known as bee-hive coke oven plants, owing to the
bee-hive structure of the ovens in a coke battery.
2.2.1
Manufacturing process in bee-hive Coke Oven Plants
A beehive coke oven plant consists of a number of coke ovens placed in series
(Photograph 1 & 2). Each oven has the capacity to feed 5-10 MT of bituminous coal
depending on the size of the oven. Coal is fed from the top of each oven with the help
of trolleys, which are mounted on rails placed all along the top of the oven-mouths.
Various processes involved in production of coke in beehive coke oven plant is
summarized in Table 1.
3.0
Characteristics of Coal of North Eastern India
The Coke oven plants in Assam and Meghalaya use coal available in Meghalaya and
Assam as raw material. While Carbon, a tetravalent element, is the main composition of
coal, other elements like Hydrogen, Oxygen, Sulphur and Nitrogen are also
predominantly available in coal in an appreciable quantity (Bhattacharya, 1996). As the
emission load from the coke oven plants are dependent on the quality of coal being
used for coking, the characteristics of the coal produced in the North Eastern Region
are briefly described in the following section.
3
Photo 1: Inside view of a Coke Oven
Photo 2: A beehive coke oven plant with number of
ovens in series forming a coke battery.
The tertiary coal deposits of northeastern region of India range in age from Paleocene
to Oligocene. Coals found in Meghalaya, are of Eocene Age while coals available in
Assam, Nagaland and Arunachal Pradesh are of Oligocene Age. The Oligocene coal
deposits of northeastern India occur along a narrow and linear belt of over-thrust known
as ‘belt of Schuppen’, which is more than 300 km long and extends over the states of
Nagaland through Assam to Arunachal Pradesh (Misra and Ghosh, 1996).
The
chemical characteristics of Eocene and Oligocene coals available in the North Eastern
India can be broadly summarized in Table 2.
4
Table 1: Brief description of various processes employed in a Beehive Coke Oven Plant.
Sl No
1
Process
Washing of coal
2
Crushing
3
Feeding and charging
4
Carbonization
5
Discharge and
quenching
6
Coke Crushing and
sizing
7
Coke Breeze
Brief description
Coal received from various coal mining
areas is washed to remove impurities or
foreign material.
The washed coal/unwashed coal is
crushed in crushing mill, generally known
as hammer mill. Coal is crushed to a size
of about 6 mm.
Trolleys, mounted on rails, are used to
feed coal into the coke ovens. Each
Trolley can support up to a weight of 9.0
to 10.0 MT. After opening the hopper of
the Trolley, coal is fed into each oven
from the top.
Coal is carbonized through destructive
distillation at about 1200-15000C. During
this process, all the volatile matters that
are present in the coal escape into the
air.
After carbonization of coal, hot cake of
coke is formed in the oven bed
(Photograph 3). The entire hot coke is
then dragged out of the oven by
mechanical pulling followed by immediate
quenching by spraying water on the top
mass of the hot cake to obtain Low Ash
Metallurgical Coke.
Coke Lumps formed during the process
of quenching are fed into a Jaw crusher,
where coke is crushed and then
screened into different sizes.
The smallest coke particles that formed
during handling and crushing of coke are
segregated and packed as Coke Breeze,
which is a valuable by-product.
5
Photograph 3: Formation of hot cake of inside an oven
3.0
Characteristics of Coal of North Eastern India
Coal available in Assam and Meghalaya are used as raw material in the Coke oven
plants in Assam and Meghalaya use coal available in Meghalaya and Assam as raw
material. While Carbon, a tetravalent element, is the main composition of coal, other
elements like Hydrogen, Oxygen, Sulphur and Nitrogen are also predominantly
available in coal in an appreciable quantity (Bhattacharya, 1996). As the emission load
from the coke oven plants are dependent on the quality of coal being used for coking,
the characteristics of the coal produced in the North Eastern Region are briefly
described in the following section.
The tertiary coal deposits of northeastern region of India range in age from Paleocene to
Oligocene. Coals found in Meghalaya, are of Eocene Age while coals available in Assam,
Nagaland and Arunachal Pradesh are of Oligocene Age. The Oligocene coal deposits of
northeastern India occur along a narrow and linear belt of over-thrust
known as ‘belt of
Schuppen’, which is more than 300 km long and extends over the states of Nagaland through
Assam to Arunachal Pradesh (Misra and Ghosh, 1996).
The chemical characteristics of
Eocene and Oligocene coals available in the North Eastern India can be broadly summarized
in Table 2. There are a number of small coalfields in the North Eastern States, especially in
Meghalaya, Assam and Arunachal Pradesh. A few detail studies on chemical characteristics of
6
coal found in north eastern India had been done in nineties (CMPDIL 1991; Mishra and Gosh,
1996). Data available from these studies for the major coalfields of the North Eastern India are
shown in Table 3.
Table 2: Chemical Characteristics of Eocene and Oligocene Coals of NE India
Parameters
Eocene
Oligocene
Coals
Coals
Air-Dried Basis
Moisture (%)
1-12
1-6
Ash (%)
3-34
2-29
Total Sulphur (%)
2-7
1-10
Dry, mineral-matter free basis
Volatile matter (%)
38-57
41-52
Carbon (%)
68-83
74-85
Hydrogen (%)
4-9
5-7
Calorific
Value 6500-8500
6255-8650
(kcal/kg)
(Source: CMPDI 1991; Mishra and Gosh , 1996)
Table 3: Chemical Characteristics of Eocene and Oligocene Coals of NE India
Name of Coalfield
Moisture
(%)
Ash
(%)
Eocene Coals of Meghalaya (Garo Hills)
Karaibari
11.5
6.6
Rongrenggiri
10.1
17.4
Siju
6.8
5.4
Darranggiri
8.4
2.7
Balphakram
3.5-4.5
3.8-18.3
Eocene Coals of Meghalaya (Khasi Hills)
Langrin
6.5-6.9
3.3-3.8
Shella
1.9
1.9
Laitryngew
1.0-1.5
7.7-31.3
Eocene Coals of Meghalaya (Jaintia Hills)
Jarain-Tkentalang
1.7-3.1
7.2-14.2
Bapung
2.9-5.4
6.0-23.4
Khliehriat
0.9
8.7
Sutnga
1.1-1.7
7.5-34.1
Mawla-Musiang
1.0-1.5
6.7-15.6
Lumare
Lumshnong
1.1-1.5
24.7-28.1
Olegocene Coals of Assam
Makum Coalfield
1.0-2.3
1.7-27.2
Dilli-Jeypore
4.8
1.9
Oligocene Coals of Arunachal Pradesh
Namchik-Namphuk 2.2-4.1
1.8-8.8
Volatile
Matters
(%)
Total
Sulphur
(%)
C
(%)
H
(%)
46.7
43.6
37.9
41.3
41.9-47.6
3.0
4.7
3.5
2.3
4.2-4.4
67.5-70.2
75.4
77.7-79.6
72.6-79.5
79.4-80.6
4.0-4.9
6.7
6.2-8.8
5.6-7.3
6.3-6.7
40.1-44.8
9.2-20.9
30.3-43.7
2.3
3.9-4.7
4.0-4.2
78.0-81.2
76.0-81.7
78.7-83.2
6.0-6.6
5.2-6.3
5.8-6.5
40.5-46.9
37.7-43.1
44.6
29.7-39.2
35.6-37.3
5.5-6.7
3.7-6.0
6.9
4.8-5.9
4.6-4.7
80.0
79.9-83.1
5.7
5.6-6.4
75.9-82.3
77.3
5.2-6.0
4.8
28.2-29.9
3.9-4.2
80.8-84.2
5.1-5.8
32.4-43.7
44.7
1.9-6.5
1.3-9.8
79.1-85.3
73.7-79.9
5.3-6.6
5.4-6.7
40.3-44.1
1.8-4.9
79.5-82.8
5.8-6.6
(Source: CMPDI 1991, Mishra and Gosh, 1996)
7
It is observed that the sulphur contents of coal available in the NE States are
comparatively very high in contrast to the coal deposits available in the other parts of
the country. The average characteristics of coal available in major coalfields in North
Eastern India
and major coalfields in other parts of India (Singareni, Kushmanda,
Singrauli, Jharia, Neyvelli, etc) are summarized in Table 4 and Table 5 respectively.
Due to high Sulphur concentration in the NE coal, which is the only raw material for the
Beehive Coke Oven Plants in Assam and Meghalaya, the emission from these plants in
terms of Oxides of Sulphur (SOX) are obviously very high and is, therefore, detrimental
to the surrounding environment.
3.1 Coal washery plant for coal beneficiation
A coal washery plant helps in improving the quality of raw coal by removing impurities
like ash content, which in turn helps in reducing air pollutants like particulate matters
(PM).
Thus a coal washery should be an essential unit in a coke oven plant for
reducing the ash content in the raw coal and thereby controlling the size and quality of
the feed.
A few bee-hive coke oven units in Assam, namely M/s K.D. Coke, M/s S.M. Coke and
M/s Pride Coke have installed their captive coal washeries. However, most of the coke
oven plants of Assam and Meghalaya are not having any coal washery and as such
coal available in the region are used for coking without any beneficiation of the mineral.
Quality of the raw coal improves after washing in terms of reduction in ash content and
increase in carbon content. A general qualitative characteristic of raw coal and washed
coal is shown in Table 6.
8
Table 4: Total Sulphur and Sulphur Forms of Coals in the NE Region (in %)
Name of
Coalfield
Total Sulphur
Pyritic
Sulphur
Sulphate
Sulphur
Organic
Sulphur
Eocene Coals of Meghalaya (Garo Hills)
Karaibari
1.36-6.01
0.07-1.90
0.15-1.68
0.61-2.42
Rongrenggiri
3.19-5.57
0.30-2.06
0.13-1.03
2.39-3.61
Siju
0.80-7.58
0.21-5.53
0.02-0.96
0.66-7.16
Darranggiri
1.21-3.68
Nil-0.96
0.01-0.51
1.07-2.33
Balphakram
4.24
1.73
0.21
2.30
Eocene Coals of Meghalaya (Khasi Hills)
Langrin
2.3
0.08
0.06-0.08
2.10-2.19
Shella
1.3-4.0
Nil-0.88
0.05-0.18
1.28-3.40
2.31-4.27
0.64-3.60
0.08-0.25
1.57-2.63
Laitryngew
Eocene Coals of Meghalaya (Jaintia Hills)
JarainTkentalang
Bapung
5.9
2.21
0.07
3.66
4.8-6.9
2.11-5.05
0.10-0.25
1.79-3.11
Sutnga
4.8-4.9
2.63-3.76
0.05-0.11
1.01-2.12
Mawla-Musiang
Lumare
Lumshnong
4.6
1.01
0.15
3.39
3.9
1.63
0.14
2.14
Olegocene
Coals of Assam
Makum Coalfield
1.9-5.90
0.16-1.42
0.05-0.43
1.25-4.73
Dilli-Jeypore
1.3-9.8
0.05-4.30
0.02-1.47
0.51-3.78
Oligocene Coals of Arunachal Pradesh
NamchikNamphuk
1.8-4.9
0.17-3.24
0.07-1.35
1.0-2.7
(Source: Mishra and Gosh, 1996)
9
Table 5: Characteristics (Proximate Analysis) of Coal Available in major coalfields in India
Coal Mines
Singareni
Kushmanda
Singrauli
Jharia
Neyvelli
Total
average
value
9.6
23.3
32.9
34.0
0.363
4133.3
10.0
23.0
25.0
40.5
0.28
5590.0
12.0
20.1
27.9
40.0
0.31
3641.6
13.0
17.51
28.22
36.08
0.41
3300.0
42.52
24.5
19.5
07.5
0.63
2850.0
17.42
21.68
26.70
31.61
0.39
3902.98
Characteristics
Moisture (%)
Volatile Matters (%)
Fixed Carbon (%)
Ash (%)
Sulphur (%)
Cal. Value
(K.cal/kg)
Table 6: Quality of pre-washed (Raw Coal) and washed Coal
Method of analysis
Ultimate Analysis
(Air Dried Basis)
Proximate Analysis
( Air Dried basis)
Coal Elements
(in %)
Carbon (C)
Raw Coal
Washed Coal
58.99
71.78
Hydrogen (H)
4.52
5.12
Nitrogen (N)
0.64
0.71
Sulphur (S)
5.60
4.70
Moisture
1.7
1.7
Ash
17.4
8.1
Volatile Matter (VM)
36.0
41.0
(Source: Report of Central Fuel Research Institute for M/s K.D. Cokes, Assam as analysed for coal from
Bapung coalfield, Meghalaya)
4.0
Waste characteristics from bee-hive coke oven plants
The coking process emits various air pollutants like particulate matters (PM); volatile
organic compounds (VOCs); poly-nuclear aromatic hydrocarbons (PAHs); methane,
carbon monoxide, hydrogen sulfide, ammonia, etc., besides oxides of sulphur (SOx)
and nitrogen (NOx). In non-recovery types of coke oven plants like the bee-hive coke
oven plants in Assam and Meghalaya, all the above mentioned pollutants are released
into the environment directly. These coke oven plants are considered to be major air
polluting industries. Both stack and fugitive emissions from coke oven plants contribute
significantly towards air pollution.
10
A World Bank study revealed that the non recovery type coke oven plants emit various
pollutants like methane, ammonia, carbon monoxide, hydrogen sulphide, SOX, NOX,
particulate matters, VOC at very high levels as shown in the Table 6 below.
Table 6: Pollutants released from non-recovery type coke oven plants
Name of the Pollutants Release of pollutants per MT of Coke produced
Methane
0.1 kg
Ammonia
0.050–0.080 kg
Carbon Monoxide
0.050–0.080 kg
Hydrogen Sulphide
0.050–0.080 kg
SOX
2.9 kg *
NOX
1.4 kg
Particulate Matters
VOC
0.7-7.4 kg
3.0 kg **
* Release about 30% of sulfur in the feed ** Includes about 2 kg of benzene
(Source: Pollution Prevention and Abatement Handbook, World Bank Group, 1998)
4.1
Emissions from bee-hive coke oven pants in Assam and Meghalaya
4.1.1 Stack Emission
There are about forty (40) beehive coke oven plants in Assam while two (2) similar coke
oven plants are being operated in Meghalaya. During the present study, detail emission
monitoring was carried out in 16 coke oven plants, including 2 such units in Meghalaya.
Plants operating in full capacities were selected for the study. The salient features of all
the coke oven plants selected for this Study are shown in Table 7.
The findings of the study in terms of emission characteristics of major pollutants
released from the coke oven plants in Assam and Meghalaya are shown in the Table
8.0.
Pollution Loads in terms of particulate matters (PM), carbon monoxide (CO), oxides of
sulphur (SOX) and oxides of nitrogen (NOX) released per day by the Coke Oven Plants
have been assessed and shown in Table 9.0. The ranges of emission of PM, CO, SOX
and NOX have been found to be 9.351-246.80 kg/day, 0.03-100.95 kg/day, 0.15-13.19
kg/day and 8.13-455.90 kg/day respectively.
11
Table 7:
Salient features of the coke oven plants monitored for the study
Sl No
Name of the Industry
State
Year of
No of Ovens
Commissioning
Stack Height
Coal
Coke (LAMC)
APC Devices
(m)
Consumption
Production
Installed to
(MT/Day)
MT/day
control Stack
Emission
1
Balaji Coke
Assam
2005
38
33.5
328.00
176.66
None
2
G L Coke
Assam
2003
24
36.0
165.00
90.00
Wet Scrubber
3
Global Coke
Assam
2005
18
44.0
216.67
120.00
None
4
GM Coke
Assam
2005
32
32.0
220.00
120.00
None
5
J.D.B. Coke
Assam
2004
40
36.5
340
187.00
None
6
K.D. Coke
Assam
2005
68
38.0
345.00
190.00
None
7
Kamrup Coke Industries
2003
40
33.0
250.00
125.44
None
8
Mortex Coke Industry
Assam
2005
36
35.0
185.00
100.00
None
9
Pride Coke
Assam
2004
44
39.0
350.00
175.00
None
10
R.P. Associates
Assam
2005
36
38.0
290.5
154.00
None
11
RPG Coke
Assam
2004
32
30.0
135.00
70.00
None
12
S.K. J. Coke Industries
Assam
2003
60
33.0
290.00
160.00
None
13
Shyam Carbon Company
Assam
2005
16
35.42
150
86.66
None
14
SM Coke
Assam
2001
20
41.1
233.33
128.00
None
15
Abhi Coke Industry
Meghalaya
2007
18
30.0
98.50
54.17
Wet Scrubber
16
Jaintia Coke Industry
Meghalaya
2007
32
30.0
93.66
42.85
Wet Scrubber
Assam
12
Table 8: Flue Gas Characteristics in the Coke Oven Plants in Assam and Meghalaya
Flue Gas
Name of the Industry
Flue Gas
Quantity
Temperature
3
( C)
(Nm /sec)
0
PM
O2 (%)
CO2 (%)
NOx
CO
3
Concentration
SO2
3
(mg/ Nm )
(mg/Nm )
3
(mg/ Nm )
3
(mg/Nm )
Corrected to 6
% CO2
Balaji Coke
2.463
747.3
NA
12.8
5.8
31.84
14.90
790.34
G L Coke, Changsari
5.886
407.3
96.03
16.7
2.9
1.75
20.58
541.98
Global Coke
2.977
528
93.29
13.4
4.9
267.49
20.09
804.34
GM Coke
3.512
730
NA
13.4
4.9
21.69
16.64
942.43
J.D.B. Coke
11.068
711
NA
17.7
2.7
4.85
8.78
609.02
K.D. Coke
9.114
688
NA
17
4.3
6.20
16.75
510.72
Kamrup Coke
2.217
552
523.84
18.9
1.5
0.36
8.31
424.42
Mortex Coke Industry
0.269
835.3
NA
19.5
1.3
1.08
4.57
180.69
Pride Coke
19.794
666
NA
14.8
4.1
59.03
NA
87.27
R.P. Associates
11.403
447
250.537
18.9
1.6
7.86
7.86
462.73
RPG Coke
1.797
544
NA
15.8
3.2
296.91
14.23
254.59
S.K. J. Coke Industries
1.919
791.4
NA
NA
4.6
6.72
11.76
513.18
Shyam Carbon
0.402
468.9
NA
20
1.2
31.33
4.42
234.17
SM Coke
4.570
387
237.69
16.3
3.4
117.85
19.42
810.92
Abhi Coke Industry
1.938
280.6
89
18.2
NA
397.80
13.46
494.15
Jaintia Coke Industry
0.790
433.7
136.91
17.3
2.2
370.66
3.80
315.84
Industries
Company
NA: Could not be analyzed due to very high temperature of Flue Gas
13
Table 9: Pollution Load from the coke oven plants in Assam and Meghalaya
Name of the Industry
Balaji Coke
G L Coke
Global Coke
GM Coke
J.D.B. Coke
K.D. Coke
Kamrup Coke
Industries
Pride Coke
R.P. Associates
RPG Coke
S.K. J. Coke
Industries
Shyam Carbon
Company
SM Coke
Abhi Coke Industry
Jaintia Coke Industry
PM
(kg/day)
NA
56.641
23.997
NA
NA
NA
100.334
CO
(kg/day)
6.77
55.27
23.11
6.58
4.63
0.54
0.03
NOX
(kg/day)
3.17
10.84
5.17
5.05
8.40
13.19
1.59
SOX
(kg/day)
168.19
80.88
206.90
285.98
582.39
402.18
81.29
NA
246.840
100.95
0.68
NA
7.75
149.25
455.90
NA
NA
46.10
0.58
2.21
1.67
39.53
85.07
NA
1.09
0.15
8.13
93.861
14.906
9.351
10.18
34.37
32.02
7.67
1.16
0.26
320.22
82.76
21.57
NA: Data Could not be generated due to very high temperature of flue gas
Emission of particulate matters (PM), carbon monoxide (CO), oxides of sulphur (SOX)
and oxides of nitrogen (NOX) per MT of coke production in the coke oven plants under
the study have been calculated and shown in the Table 10. The ranges of emission of
PM, CO, SOX and NOX have been found to be 0.20-1.60 kg/MT, 0.001-1.230 kg/MT,
0.002-0.120 kg/MT and 0.094-3.173 kg/MT respectively.
It has been observed that most of the coke oven plants are being operated without any
air pollution control (APC) devices. Only four (4) Units, viz., M/s Maa Kamakhya Coke
Industry (Assam), M/s G.L. Coke (Assam), M/s Jaintia Coke (Meghalaya) and M/s Abhi
Coke Pvt Ltd (Meghalaya) have installed wet scrubber to treat the flue gases before
releasing into the environment
through stacks of adequate heights. Wet scrubber
installed by M/s Jaintia Coke in Meghalaya is shown in the Photograph No 4.
Table 10: Emission of Pollutants in the Coke Oven Plants per MT of coke production
Name of the Industry
Balaji Coke
G L Coke
Global Coke
GM Coke
J.D.B. Coke
K.D. Coke
Kamrup Coke
Industries
Pride Coke
R.P. Associates
PM
(kg/MT)
CO
(kg/MT)
NOx
(kg/MT)
SOX
(kg/MT)
NA
0.629
0.20
NA
NA
NA
0.799
0.038
0.014
0.573
0.055
0.025
0.026
0.001
0.018
0.120
0.043
0.042
0.045
0.069
0.013
0.952
0.899
1.724
2.383
3.114
2.117
0.648
NA
1.602
0.577
0.050
*
0.050
0.853
2.960
RPG Coke
NA
0.659
0.032
0.565
S.K. J. Coke
NA
0.007
0.012
0.532
Industries
Shyam Carbon
NA
0.013
0.002
0.094
Company
SM Coke
0.733
0.364
0.060
2.502
Abhi Coke Industry
0.275
1.230
0.042
1.528
Jaintia Coke Industry
0.218
0.591
0.006
0.503
NA: Data Could not be analyzed due to very high temperature of Flue Gas
* Data Could not be analyzed due to Sensor error during monitoring
The wet scrubbing of flue gases is showing satisfactory result, in terms of reduction in
the gaseous pollutants, as shown in Table 11 (a) and Table 11 (b).
Photograph 4: Wet Scrubbing system of M/s Jaintia Coke, Meghalaya
15
Table 11 (a): Flue Gas characteristics of a coke oven plant with scrubber as well as scrubber
bypassed condition (M/s Jaintia Coke Industry)
Operating
Condition
Parameters Monitored (M/s Jaintia Coke Industry, Meghalaya)
Flue Gas
Temp
(0C)
SOX
(mg/Nm3)
NOX
(mg/Nm3)
CO
(mg/Nm3)
CO2 (%)
O2 (%)
PM
(mg/ Nm3)
With
Scrubber
431.9
317.45
3.81
372.55
2.2
17.2
136.91
With
scrubber
bypassed
479.4
679.84
7.51
510.57
2.1
16.8
NA
Table 11 (b): Flue Gas characteristics of a coke oven plant with scrubber as well as scrubber
bypassed condition (M/s G.L. Coke, Assam)
Operating
Condition
With
Scrubber
With
scrubber
bypassed
Parameters Monitored
Flue Gas
Temp
(0C)
294.4
SOX
(mg/Nm3)
NOX
(mg/Nm3)
CO2 (%)
O2 (%)
PM
(mg/ Nm3)
126.05
*
1.7
17.60
88.27
407.7
541.98
*
2.8
16.70
96.03
* Could not be analyzed due to Sensor Error in Flue Gas Analyzer, NA: Not Analyzed
4.1.2 Fugitive emissions from coke oven plants
Though stack emissions (Photograph 5) are considered to be the major sources of air
pollution from the coke oven plants, fugitive emissions from various processes involved
in coke manufacturing contribute significantly towards environmental pollution. Coal
handling operations like coal crushing, coal charging and coke handling operations like
coke pushing, quenching and crushing are the major sources of fugitive emissions in
coke oven plants. Fugitive emissions, in large scale, were seen in most of the coke
oven plant during the study. Large scale fugitive emissions occur during charging of
coal into the oven and also during coal pushing and quenching operations (Photograph
6 and 7). Moreover, high level of fugitive emission are released from the ‘secondary
holes’ provided in both sides at the bottom of the main flue tunnel in the coke oven
plants (Photograph 7) during the initial hours of charging of coal.
16
Photograph 5:
Stack Emissions from Coke
Oven Pants
Photograph 6:
Fugitive Emissions in coke
oven pants during charging of
coal
Photograph 7:
Fugitive emissions occur
during pushing and
quenching of coke
Photograph 8:
Fugitive emissions from
‘Secondary Holes’ provided
in ‘flue tunnel’ during initial
hours of charging of coal
17
In M/s S.M. Coke, Byrnihat, provisions have been made to collect fugitive emission,
generated during charging of coal into the ovens, from the top of the ovens through a
common duct (Photograph 9). Long duct and ID fan have been installed for the purpose
to collect the fugitive emission and pass the same into a water chamber for retaining
and recovering the dust.
Photograph 9:
Ducts with openings provided
over the ovens to control fugitive
emissions (SM Coke, Byrnihat)
4.1.2.1 Assessment of fugitive emissions from coke oven plants
To assess the level of fugitive emission inside coke oven plants, concentration of
various pollutants, viz., PM, SOx and NOx was measured near the source of fugitive
emission using low volume sampler (Make: Envirotech, Model: Handy sampler APM
881). Fugitive mission monitoring was carried out at two industries (M/s Pride Coke and
M/s K.D. Coke industry) after selecting suitable locations considering the source of
emission during coal feeding, quenching and coke crushing operations. The result of
monitoring is shown in the Table 12.
From fugitive emission monitoring, level of suspended particulate matter (SPM) is
observed in the range of 666 – 14666 (µg/m3) near the coke ovens and coke crushing
areas. The levels of SOx and NOx are observed in the range of 0.25-216.88 µg/m3 and
22.65-36.88 µg/m3 respectively and these concentrations are alarmingly high looking
into the ambient air quality standards in India
18
Table 12: Level of fugitive emission in Coke Oven Plants
Name of the Unit
Source of Sampling
Pride Coke
(Date of monitoring :
20.07.2010)
K D Coke
(Date of monitoring :
06.08.2010)
4.1.3
Concentration of pollutants
Oven floor level (during quenching
operations in an oven)
Oven mouth level ( during Coal
charging)
Coke crushing yard (during
crushing )
Near ovens floor level (during
quenching operations in an oven)
SPM
3
(µg/m )
SO2
(µg/m3)
NOX
(µg/m3)
14666
0.55
22.65
666
216.88
23.85
5556
4.58
36.88
13333
0.25
36
Ambient Air Quality in Coke Oven Plants
The ambient air quality inside the premises of a few coke oven plants, as monitored by
recognized laboratories, is shown in Table 12.
Table 12: Ambient air quality in the premises of coke oven plants
Name of the Unit
Source of Sampling
Jal Coke Company
Between office and Coke
Crusher unit
Between office and Coke
Crusher unit
Main Gate
Global Coke Products
Coal Yard near ovens
(Sample 1)
Coal Yard near ovens
(Sample 2)
Main Gate
Concentration of pollutants
RSPM
(µg/m3)
85.80
SPM
(µg/m3)
293.72
SO2
(µg/m3)
27.00
NOX
(µg/m3)
32.32
265.49
699.96
30.50
17.94
71.88
341.83
34.50
24.90
96.28
364.87
35.67
23.48
285.29
775.39
35.00
20.58
88.71
256.22
28.17
21.54
S.M Cokes Ltd
Between Coke Crusher and
106.21
322.18
40.17
20.58
Coke Ovens-I
Between Coke Crusher and
315.76
575.72
49.33
21.80
Coke Ovens-II
Source: Jal Coke Company, Global Coke Products, S.M Cokes Ltd as analyzed by Eco Care, Asansol, Dist. Burdwan,
West Bengal
19
4.2
Existing emission standards available for beehive hard coke oven,
effluent standards recovery type coke oven plants and coal washeries in
India
4.2.1 Environmental standard for beehive hard coke oven
Pollutant
Emission Limit
New Unit
Particulate Matter
(corrected to 6 % CO2)
150 mg/Nm3
Existing Unit
Particulate Matter
(corrected to 6 % CO2)
350 mg/Nm3
Note: For control of emissions and proper dispersion of pollutants, the following
guidelines shall be followed
•
Units set up after April 2, 1996 shall be treated as new units
•
A minimum stack height of 20 m shall be provided by each unit.
•
Emission from coke ovens shall be channelised through a tunnel and finally
emitted through a stack. Dumper adjustment techniques shall be used to have
optimum heat utilization and also to control the emission of un-burnt carbon
particles and combustible flue gases.
•
Wet scrubbing system or waste heat utilization for power generation or byproduct
recovery system should be installed properly to achieve the prescribed standards.
•
After April 01, 2000, all the existing coke units shall comply with the standards
prescribed for the new units.
Source: EPA Notification [ GSR 176 (E) April 2, 1996]
20
4.2.2 Coke ovens : Wastewater discharge standards
Concentration in the effluent when
discharged into inland surface
water not to exceed, mg/l (except
for pH)
5.5 to 9.0
Parameters
pH
Biochemical
(270C, 3 days)
oxygen
demand
30
Suspended solids
100
Phenolic compounds (As C6H5OH)
5
Cyanides (As CN)
0.2
Oil & grease
10
Ammonical nitrogen (As N)
50
Source : EPA Notification [S.O. 64(E), dt.
18th Jan., 1988]
4.2.3 Environmental standards for coal washeries
A. Fugitive emission standards
The difference in the value of suspended particulate matter, delta (Δ), measured
between 25 to 30 metre from the enclosure of coal crushing plant in the downward and
leeward wind direction shall not exceed 150 microgram per cubic meter. Method of
measurement shall be High Volume Sampling and Average flow rate, not less than 1.1
m3 per minute, using upwind downwind method of measurement.
B. Effluent discharge standards
The coal washeries shall maintain the close circuit operation with zero effluent
discharge.
If in case due to some genuine problems like periodic cleaning of the system, heavy
rainfall etc. it become necessary to discharge the effluent to sewer/land/stream then the
effluent shall conform to the following standards at the final outlet of the coal washery.
21
Sr. No.
Parameter
Limits
1
pH
5.5-9.0
2
Total suspended solids
100 mg/l
3
Oil & Grease
10 mg/l
4
B.O.D. (3 days 27 deg C)
30 mg/l
5
COD
250 mg/l
6
Phenolics
1.0 mg/l
C. Noise level standards
Operational/Working zone — not to exceed 85 dB (A) Leq for 8 hours exposure.
The ambient air quality standards in respect of noise as notified under Environmental
(Protection) Rules, 1986 shall be followed at the boundary line of the coal washery.
D. Code of practice for Coal Washery.
Water or Water mixed chemical shall be sprayed at all strategic coal transfer points
such as conveyors, loading/unloading points etc. As far as practically possible
conveyors, transfer points etc. shall be provided with enclosures.
•
The crushers/pulverizers for the coal washeries shall be provided with enclosures,
fitted with suitable air pollution control measures and finally emitted through a stack
of minimum height of 30 m, conforming particulate matter emission standard of 150
mg/Nm3 or provided with adequate water sprinkling arrangement.
•
Water sprinkling by using fine atomizer nozzles arrangement shall be provided on
the coal heaps and on land around the crushers/pulveriser.
•
Area, in and around the coal washery shall be pucca either asphalted or concreted.
•
Water consumption in the coal washery shall not exceed 1.5 cubic meter per MT of
coal.
•
The efficiency of the setting ponds of the wastewater treatment system of the coal
washery shall not be less than 90%.
22
•
Green belt shall be developed along the road side, coal handling plants, residential
complex, office building an all around the boundary line of the coal washery.
•
Storage bunkers, hoppers, rubber decks in chutes and centrifugal chutes shall be
provided with proper rubber linings.
•
Vehicles movement in the coal washery area shall be regulated effectively to avoid
traffic congestion. High pressure horn shall be prohibited. Smoke emission from
heavy duty vehicle operating in the coal washeries should conform the standards
prescribed under Motor Vehicle Rules 1989.
(Source: G.S.R. 7 dated 22nd December, 1998)
4.3 Emission factor for hazardous air pollutants (HAPs)
In non recovery type bee-hive coke oven plants, by-products are not recovered and as
such the hazardous air pollutants like benzene, toluene, isomers of xylene, cyanide
compounds, naphthalene, phenol, and polycyclic organic matter are contained in the
coke oven gas and are emitted to the atmosphere through stack emission as well as
fugitive emission.
There are no emission standards for these HAPs. Moreover, no quantitative emission
data suitable for use in development of air pollutant parameters in respect of benzene,
toluene, isomers of xylene, cyanide compounds, naphthalene, phenol, and polycyclic
organic matter are available for any of these HAPs. However, an emission factor for the
HAPs may be calculated as described in the following section.
4.3.1. A sample calculation for emission factor
HAPs like benzene and other class of compounds termed as Polycyclic Organic Matter
(POM) are the known carcinogens and therefore, are of serious health concern. POM
condense as fine particulate at ambient temperature. There are thousands of POM
reported as Benzene Soluble Organics (BSO) or Benzene (a) Pyrene. The emission
factor for the BSOs can be calculated as shown in the following example.
23
Let, a particular bee-hive coke oven has 40 ovens with 20 percent of doors leaking at an
average rate of 200 gm of BSO per hour per leaking door (1 door in each oven). Let,
each oven is charged with 5 Ton of coal in 24 hours cycle in a day and the coke oven is
operated 300 days per year.
i)
ii)
Number of leaking doors
=
40 ovens x 1 door/oven x 0 .2 (fraction leaking)
=
8 doors
Benzene soluble organics =
8 doors x 0.2 kg hour/door x 7200 hr/yr
(BSO) emitted per year
iii)
=
8 x 1440 kg/year
=
11520 kg/year
Total coal uses in the Coke =
5 tons of coal/oven x 40 ovens/24 hr x 7200 hr/yr
oven plant per year (for 5 =
60000 Tons/year
MT of coal per oven and
24 hr cyclic time, 300 days
in a year),
iv)
5.0
Emission factor for BSO
=
( 11520 kg/ year)/ 60000 MT/year
=
0.192 kg of BSO /Ton of coal usage
=
192 gm of BSO /Ton of coal usage
Power generation from waste heat of Flue Gases in bee-hive
coke oven plants.
M/s Patkai Coal Products, Samukjan Village, Margherita, Assam has put a
commendable effort to generate electrical energy from the flue gases emitted from the
coke ovens. The unit has installed a plant to generate 500 KW of electric power from
the flue gases.
In M/s Patkai Coal Products Limited, there are 36 beehive coke ovens with an installed
hard coke production capacity of 15000 MT/year. However the workable capacity has
been reported as about 12,000 MT/year. The unit has estimated that about 1.2 lakh
m3/hr of flue gases shall be available from the plant. The unit is also of the opinion that
about 1.5 MW of electrical energy may be generated from the quantum of the flue gases
24
available. However, as a first attempt, the unit is targeting to generate about 500 KW of
electricity.
5.1 Various units installed for the power plant
The unit has already installed a Gas Collection Chamber (Capacity: 12.68 cu m) to
collect the flue gases from the flue duct (Photograph 10). Earlier the flue duct was
directly connected with a chimney of about 30 m. Now that tunnel is blocked by a
damper and the flue gas is routed through the gas collection chamber. The gas
collection chamber is then connected with a steam boiler (Photograph 11), which has
steam generation capacity of 18 MT/hr, followed by a steam super-heater and turbine
generator (500 KW capacity).
Flue gas
To Boiler
Gas Collection
Chamber
Photograph 10 : Gas Collection Chamber
25
Boiler
Photograph 11 : Steam boiler (capacity 18 MT/hr)
The installation of the power plant is almost complete. Trial run has already been made
by the unit. Though sincere efforts have been put by the unit, the power plant is not
fully successful so far.
5.2 Difficulties faced by the unit in running the power plant.
M/s Patkai Coal Products has invested about ` 1 crore in installation of the power plant,
as has been reported. However, following difficulties have been faced by the power
plant for continuous running the power plant for generation of electricity.
i)
Due to high water table in the plant site, there occur water seepage in the flue
tunnel and subsequently the flue gases get cooled and as such there is not
sufficient d temperature in the flue gas to run the boiler.
ii) There is drop in steam pressure frequently and as such there is difficulty in
running the boiler smoothly.
To overcome the problem of low heat of the flue gas, the unit has planned to use natural
gas as auxiliary fuel and also plans to generate about 1.0 MW electricity in near future.
26
6.0
•
General observations
Exit flue gas temperature was found to be more than 5000c in most of the coke
oven plants and as such particulate matters in flue gas could not be measured in
many coke oven plants because the glass fibre thimbles used for emission
monitoring can withstand a temperature of about 5000 C only.
•
Almost all the units have installed bag houses to reduce fugitive emissions from
the coke crushing operations. However, uncontrolled fugitive emissions were
observed in many coke crushing units due to poor maintenance of the bag
houses.
•
Crushing of coke in moist condition was seen practiced by a few units, where
lesser fugitive emission was observed.
•
All the units have a settling tank to store and recycle water required for coke
quenching. When water is sprayed over the hot coke for quenching, significant
amount of water is spilled over into the drains surrounding the coke –ovens. In
most of the coke oven plants, the drain surrounding the coke ovens, is seen
connected to a settling tank, where the coke fines are settled and water is further
recycled for coke quenching. The arrangement of settling tank thus allows
settling of coke fines in one hand, while serves as a measure of water
conservation on the other hand.
•
CO2 percentages (0.6 – 5.8 %) in the Flue Gases are found to be very low and
when corrected to 6 % CO2 conditions, very few units could achieve the
Standards.
•
Coal washery is useful in reducing ash content by 9.0-10.0 %.
•
Anthracite is the highest rank of coal and is characterized by low volatile matter
(always less than 10 %) and high carbon content. It is capable of burning without
smoke.
•
Though coking is done in oxygen starved condition, a portion of oven above the
coal charge in non recovery ovens (since by products are not recovered) is
27
subjected to an oxidizing atmosphere. This is because secondary air is
introduced into the oven chamber for combustion through several ports located
above the charge level in both pusher and coke side doors of the oven. This
oxidizing atmosphere in the oven assumes special significance as guiding factor
for the selection of refractors. Refractory bricks work in the non recovery type
ovens are likely to be subjected to thermal shocks and hence alumina refractory
bricks are ideally suitable as alumina bricks provide better resistance to thermal
shocks. Higher alumina bricks (with alumina 61 %) are superior to silica bricks
with respect to compressive strength, bending strength, coefficient of thermal
expansion and modulus of elasticity
•
The coke ovens plants, which have installed either the scrubber system or the
fugitive emission control system or both, do not run the air pollution control
devices regularly as those are power consuming equipments and also, it is
possible to run the plant bypassing the APC devices.
7.0
•
Suggestive measures for controlling stack emission and fugitive
emission
The industry should prevent fugitive emission from all active operations by installing
suitable pollution control devices. Fugitive emission generated during the Coal
charging processes should be collected through common ducts connected with ID
Fan as has been done by M/s S/M. Coke, Assam. Fugitive Emissions, thus
collected, should be passed through Air Pollution Control (APC) Devices like
scrubber before releasing through the Stack of Suitable Height.
• Airborne dust should be extracted to the maximum extent from various locations like
unloading of raw materials, coal and coke crusher discharge, and other material
transfer points by providing suction & duct arrangement equipped with cyclone &
bag filters.
• Dry extraction cum bag filter with adequate extraction volume should be installed in
the coke crushing house to control airborne dust generated during coke-crushing
operations.
28
• Emission from coke ovens shall be channelized through a tunnel and finally emitted
through a stack. Dumper adjustments shall be used to have optimum heat utilization
and also to control the emission of un-burnt carbon particles and combustible flue
gases.
• The vibratory screen for sizing the coke should be provided with a dust extraction
arrangement equipped with bag filter to prevent fugitive emission from that section.
• Controlled automated system for introduction of tertiary air in the common flue duct
shall be installed to ensure proper combustion of combustible particulate matters
(PM) in the flue gas.
• The natural draft shall be produced by the chimneys alone. It is caused by the
difference in weights between the column of hot gases inside the chimney and the
column of outside air of the same height and cross section. Being much lighter than
outside air, chimney flue gas tends to rise and the heavier air outside air flows in
through the ash pit to take its place. It is usually controlled by hand operated dumper
in the chimney. Here no fans or blowers are required to be used.
• The hot flue gases containing a number of pollutants, including HAPs, shall be
discharged through chimney at such a height that it will not be a nuisance to the
surrounding community in case of a non recovery coke oven plant. All hydrocarbons
shall be incinerated due to high operating temperature in the oven and also the flue
gas passage.
• A very high coking temperature of 1200oC-1500oC shall be achieved to burn and
break combustible compounds of hydrocarbons in the coke oven gas.
• Wet scrubbing shall be installed with the installation of high pressure nozzles
(minimum 7.5 kg/cm2) for control of SO2 emission.
• NOx levels should be minimized by control in oven temperature.
• Charging and pushing emissions shall be minimized by coal cake compaction and
precision on oven door openings.
• Higher alumina bricks (with alumina 61 %) are superior to silica bricks with respect
to compressive strength, bending strength, coefficient of thermal expansion and
29
modulus of elasticity and such alumina bricks shall be used for construction of coke
oven walls.
• Coal washery should be made mandatory more new bee hive coke oven plants.
Coal washery is useful in reducing ash content by 9.0-10.0 %.
•
Anthracite is the highest rank of coal and is characterized by low volatile matter
(always less than 10 %) and high carbon content. It is further capable of burning
without smoke. Such coals shall be used by the coke oven plants, if available.
• Water used for quenching and spillage thereof should be properly channeled into a
sedimentation tank, from where water should be recycled for the quenching
operations and other purposes, as a measure of water conservation..
• Water should be periodically sprayed on the stockpiles/coal yard so as to retain
some moisture in the top layer and thus to avoid wind blowing of fines. The
frequency and quantity of watering may vary from season to season and the area to
be covered, which should be decided and recorded, based on average evaporation
rate in the region. Coal should be sufficiently moistened to suppress fines by
spraying minimum quantity of water.
•
Adequate ventilation for the coke crushing and packing hall should be provided for
venting out suspended particulates thereby ensuring dust free work environment.
• Storm water around the coal yard should be isolated. sedimentation tank and
neutralization tank in series to be provided in the storm drain to avoid discharge of
coal dust laden water (wastewater with high suspended solids) into the environment
•
Water should be periodically sprayed on the stockpiles/coal yard so as to retain
some moisture in the top layer and thus to avoid wind blowing of fines. The
frequency and quantity of watering may vary from season to season and the area to
be covered, which should be decided and recorded, based on average evaporation
rate in the region. Coal should be sufficiently moistened to suppress fines by
spraying minimum quantity of water.
30
8.0
Recommended guidelines for better environmental management
in coke oven plants
•
Some of the coke oven plants are having the flue tunnel at the top of the coke
oven battery ( Upward draft ) and the chimney is placed in the middle of the coke
ovens. In some other coke oven plants, flue gases are routed through an
underground tunnel ( Downward draft) before releasing the gases through a
chimney.
In this former case, the travel path of flue gases is very less as
compared to the later. Moreover, the flue gas temperature at the chimney is very
high (upto 750-8000C) in the former while in the later case, it is under 5000C.
As the flue gases have to travel more in the underground channel, the
particulates get time for burning and settling and it is therefore observed that the
particulate matter concentration in the flue gas in less in bee hive coke oven
plant, in which the flue gases are passed through an underground tunnel before
releasing through a chimney. Therefore upward draft coke oven units should be
converted to downdraft provided with
well designed underground Tunnel of
adequate length for reducing the emission levels of particulate matter.
• Airborne dust should be extracted to the maximum extent from various locations
like unloading of raw materials, coal and coke crusher discharge, and other
material transfer points by providing suction & duct arrangement equipped with
cyclone & bag filters.
• Controlled automated system for introduction of tertiary air in the common flue
duct shall be installed to ensure proper combustion of combustible particulate
matters (PM) in the flue gas and thereby reducing the level of particulate matter
in the flue gas.
•
Wet scrubbing system should be made installed in coke oven plants as
significant reduction of gaseous pollutants were observed with wet scrubbing of
flue gases. Wet Scrubbing of gases have been found to be adequate to reduce
the Flue gas temperature less than 500 0C and also to reduce the concentration
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of gaseous pollutants, especially SOx and CO, to about 50 %. Scrubbing of flue
gases are thus essential for two basic purposes:
a)
To lower the concentration of particulate matters and also to reduce the
volume of toxic gases
b)
•
To lower the temperature of emission.
Wastewater generated from the scrubber should be treated with lime to
neutralize pH. The sludge should be properly dumped after it is removed from the
water recirculation tank.
•
Fugitive emissions are of major environmental concern in coke oven plants.
Fugitive emissions from the oven mouths during coal charging is found to be the
maximum and, therefore, should be collected through common ducts placed over
the ovens and should be passed through water chambers before letting out with
the help of ID Fans to the chimneys.
•
Utilization of waste heat for electric power generation shall be the best possible
option for reducing the gaseous pollution and also in recovering the heat from the
flue gases. This may be made mandatory for the new bee hive coke oven units.
•
All the Coke oven plants should have similar air pollution control (APC) devices.
As of now, there are only a few plants which have APC devices and are not
operated regularly. State Pollution Control Board should ensure that all the
Beehive Coke Oven plants install APC devices should ensure action against the
defaulting units.
9.0
Scope for future studies
Status of ambient air quality in the Byrnihat area, where cluster of coke oven plants
are being operated, should be studied in detail. Such study should incorporate
determination of heavy metals (HM), Poly-nuclear Aromatic Hydrocarbons (PAH) in
ambient air of Jorabat and Byrnihat, located in the Assam –Meghalaya Border.
--------------------------
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References:
CMPDIL, 1991, Compendium on coal occurrences of the North Eastern region, Vol. II AMakum Coalfield, Assam. Central Mine Planning and Design Institute Limited, 188 pp.
Coal Chemicals, CFRI Golden Jubilee Monograph, edited by R.N. Bhattacharya,
Central Fuel Research Institute, Dhanbad, 1996
Dasgupta, A. B. and Biswas, A. K., 2000, Geology of Assam. Geological Society of
India, 169 pp.
Mishra, H. K. and Ghosh, R. K, 1996, Geology, Petrology and Utilization Potential of
some Tertiary coals of the Northeastern Region of India. International Journal of Coal
Geology, 30: 65 -100.
Pollution Prevention and Abatement Handbook, World Bank Group July 1998
Wikipedia, the free encyclopedia
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