Journal of Mines, Metals and Fuels, 70(8) : 449-455; 2022. DOI: 10.

18311/jmmf/2022/32362

Print ISSN : 0022-2755

Journal of Mines, Metals and Fuels

Contents available at: www.informaticsjournals.com/index.php/jmmf

Saving of Coke Oven Gas by Reduction of Smoke

Pushing of Recovery Type Coke Plant
Niranjan Mahato1*, Himanshu Agarwal1 and Jainendra Jain2
1
Department of Mechanical Engineering, Government Engineering College, Jagdalpur - 494001, Chhattisgarh, India;
niranjan166mahato@gmail.com
2
Department of Applied Mathematics, Government Engineering College, Jagdalpur - 494001, Chhattisgarh, India

Abstract
For stable oven operation and prolongation of the coke oven life, it is important to remove excess carbon formation on
the coke oven wall. It is considered that the carbon formation rate is influenced by the gas components generated during
carbonation, the gas velocity and oven wall temperature are not uniformly maintained, as a result of smoke pushing. The
smoke pushing is not favourable for the good health of the coke oven battery. In this paper, the smoke pushing can be rectified
by proper maintenance of the gas path. Energy consumption and economic growth are interwoven, and rising energy levels
always represent rising energy consumption. Coke is a reducing agent and a load-handling tool in blast furnaces. By this
rectification, the coke oven gas flow was reduced from 17600Nm3/hrs to 17300Nm3/hrs without any extra manpower cost.
The experimental set-up implementation of this modern proposal in a coke plant will make coke more extra energy efficient
with no other extra costs.

Keywords: Coke, Coke Oven Gas Flow, Coke Plant, Heating Flues, Specific Heat Consumption

1.0 Introduction coke rate, boost its output, and cut costs. Modelling and
testing in a pilot oven can be used to analyze the
Coke is produced by the proper destructive distillation of composition of current coal blends. During plant audits, a
coal in a coke plant. Especially feeding coal blends study of the current coke-making technologies is
comprising the various types of blended coals of desired conducted, and possibilities to introduce new or modified
coking parameters are heated in an oxygen-free technologies are noted. Each coke facility’s battery design,
atmosphere (coked) until the most volatile components nameplate capacity, current and historical production,
in the coal are removed. The process is carried out in a reline dates, service life, number of ovens out of
battery, which contains twenty or more tall, wide and commission and undergoing extended coking cycles,
narrow ovens arranged side by side. After charging, a number of ovens requiring end flue or through wall
coke oven is heated for twelve or more hours, during repairs, and delays are all established as part of the coke
which a variety of volatile compounds evolves from coal. supply analysis. As the raw coke oven gas is cooled, tar
The quality and quantity requirements for current and vapour condenses and forms aerosols which are carried
upcoming blast furnace operations are included in the along with the gas flow [2]. These tar particles would
coke demand analysis [1]. Receiving constant, high- contaminate and foul downstream processes and would
quality coke is necessary for the blast furnace to reduce its foul gas lines and burner nozzles if allowed to continue in

*Author for correspondence

 Saving of Coke Oven Gas by Reduction of Smoke Pushing of Recovery Type Coke Plant

the gas stream. The tar precipitators typically use high- by emissions produced during coal charging, coal
voltage electrodes to charge the tar particles and then carbonization, coke pushing, and coke cooling.
collect them from the gas by means of electrostatic Polynuclear aromatic hydrocarbons, which cause cancer,
attraction. The task of the unit is to remove tar droplets are present in coke oven emissions along with other
entrained in gas after the primary cooler. To remove tar hazardous materials. The authors developed a new model
mist entrained in gas, three electric tar precipitators are for reducing variation in the burning of coal to coke
provided, normally three precipitators in operation, in during the coke-making process to gain good quality and
case of one in maintenance and two in operation, tar also to properly develop the energy in the coke plant [4].
content in the gas canal so be reduced to 20mg/Nm3 is The total length of the battery is a hundred meters,
guaranteed experimental value while two electrostatic tar consisting of rectangular-shaped heating chambers of a
precipitators are in operation. Gas enters into the electric length of sixteen meters, a height is seven meters, and a
tar precipitator from its bottom, via the gas distribution width of 0.41 meters with removal door ends. The
plate gas is uniformly distributed onto the whole section, recovery-type coke-making process takes a period of
then flows through the high voltage electric field of the eighteen to twenty hours depending on the number of
honeycomb upward to leave the electric tar precipitator pushes by indirect heating with the coke oven gas or
and enters into the exhauster unit. When gas passes mixed gas. A 7-meter tall battery has sixty-eight heating
through the electric tar precipitator, solid and tar mist walls and each type of wall has thirty burning flues [5].
droplet in gas is deposited on the surface of the The total average temperature of each flue is about
honeycomb, the tar flows via the tar outlet at the bottom maintained at about 1200 to 1300 °C. Maintaining the
into the water seal pot, from which it flows into the proper uniform operating conditions is a difficult task
underground slop tank. Coke oven gas from the exhauster due to the dynamic pushing of the operation and achieving
is first it is fed to the final cooling stage at the lower part the required production target. The pulverized coking
of the hydrogen sulfide scrubber. The gas is cooled at coal that has been carbonized at a high temperature
about 22ºC by spraying with the circulating water. After produces coke (-3 mm size) [6]. To create lumpy coke,
the circulating water out of the hydrogen sulfide scrubber coal is burned to a temperature between 10,000 and
is cooled with the cooler for circulating water, the 10,000 degrees Celsius in the absence of air. It includes in
circulating water is sent back again to the final cooling terms of its impact on the functioning of the blast furnace
stage at the lower part of the hydrogen sulfide scrubber and the quality of the hot metal, coke is the most
for circulating cooling. At the upper part of the hydrogen significant raw material put into the furnace [7]. Several
sulfide scrubber, hydrogen sulfide in gas is absorbed with by-products, some of which may be solid, liquid, gaseous,
enriched ammonia water from ammonia scrubbing and or plastic in form, are produced during the coke-making
lean solution from the de-acidifier and ammonia stripping process. Many of these by-products are hazardous to the
unit. At the same time as hydrogen sulfide removal in a environment and poisonous. They need to be handled
hydrogen sulfide scrubber, also carbon die oxide, with extreme caution and restraint. Each battery used to
hydrocarbons and ammonia are absorbed. Because the make coke has a number of slot-type furnaces for
absorption process of hydrogen sulfide, CO2, carbonizing the coal [8]. To drive out the volatile stuff
hydrocarbons and ammonia is the process of an found in coal, each oven receives a sequential charge of
exothermic reaction, therefore both the upper stage and coal from the coal preparation plant and stores it in a coal
lower stage of hydrogen sulfide scrubber are provided tower. This process is known as coking. Coke is forced out
with the coolers for hydrogen sulfide circulating scrubbing of the oven, quenched and properly cooled using the wet/
solution. The primary purpose of coke ovens is to dry process, and then supplied to the blast furnace via the
transform coal into coke, which is utilized in the blast coke handling plant once the gas evolution and subsequent
furnace as a fuel and reducing agent [3]. The entire process coal carbonization are finished. Coke oven gas is saved up
of creating coke is fraught with safety risks, such as being to 300-400 Nm3/hour by using reversal cycle modification
hit by or tangled in moving machinery, getting burned, in the coke plant. The by-product factory receives evolved
starting a fire or explosion, falling and slipping, and being gases from the ovens to recover important compounds
exposed to dust, noise, heat, gas, etc. The majority of such as tar, ammonia, naphthalene, benzene, and
health risks associated with coke production are caused others [9]. The gas and preheated air are fed to the base of

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 Niranjan Mahato, Himanshu Agarwal and Jainendra Jain

the flues from where they move upwards under the a new type of SOP for regular maintenance of gas paths
influence of chimney drought [10]. The hot products of like distribution pipe cleaning, orifice cleaning, cylinder
combustion cross over to the adjacent flues and pass on to and horse pipe cleaning as a daily routine basis, as results
the re-generators where the checker-work absorbs most all flues like pusher side and coke side temperature will
of the sensible heat contained in the product of be gradually increased. This method is also helpful for
combustion [11]. In this paper, the cooled gases from the reducing coke oven gas flow.
re-generator move to the waste heat flues and then to the There are some difficulties to remove carbon efficiency
chimney. These two currents of heat flow, i.e. the with conventional methods of carbon removal. Sometimes
up-current and down-current are periodically reversed compressed air is also helpful for full distribution pipe
every 20 minutes to maintain uniform and state cleaning as well as horse pipe cleaning.
temperature conditions throughout the whole battery [12].
Due to the growing public awareness of environmental 2.1 Seven-Meter Tall Battery Experimental
issues in a developed country, the major modern process Description
of large-scale industries is under tremendous pressure to
The experimental set-up for a 7-meter tall coke oven
minimize the control of air emissions. In an integrated
battery required some technical processes and operation
steel factory where coke and coke oven gas are the main
parameters which are shown in Table 1. There is a
sources of energy, the production of metallic coke in the
sixty-seven heating oven, sixty-eight heating walls and
by-product of recovery-type ovens is one of the important
sixty-nine numbers of waste heated boxes for transferring
major sources of air pollution. Dust is produced at every
the waste gas tunnel to the chimney. There is three
step of the coke-making process, including improper
charging hole for feeding the coking coal into the heating
receiving, improper unloading, improper handling,
oven. Thirty-two tonnes of blended dried coal is charged
abnormal crushing, improper carbonization, and
per oven and output coke is around twenty-five tones
subsequent coke handling. Hot air plumes, dust, and
produced. There is a total thirty-two number of heating
gaseous emissions are produced during the charging,
flues out of thirty-two sixteen numbers of heating flues
pushing, and coke-quenching processes.
on the pusher side and sixteen numbers on the coke side.
The experimental brief description is given below in
2.0 Methodology of Research tabulation form in Table 1.
The carbon deposits on coke oven walls may not only
interrupt the oven operation but also cause damage to
2.2 CPD of Recovery Type of Coke Plant
the oven walls, although many studies have been made on 2.2 Represents the mathematical formula for the coking
the properties of deposited carbons and the mechanism period of a coke plant:
of their formation. There are few on the quantitative N1 × 24
emission of carbon formation in an actual coke oven. For CPD =
N
the purpose of stable oven operation and prolongation of
oven life, it is necessary to remove carbon according to
67 × 24
the amount of carbon deposited on coke oven walls. CPD =
91
In this paper, it is introduced that a quantitative emission
of carbon formation rate on the wall was developed and

Table 1. Technical parameters for experimental set-up

No. of No. of No. of Dry- No. of No. of No. of Output No. of Oven
oven heating waste charged heating heating heating flues coke per charging height in
walls heat coal in flues flues on per wall oven holes per meter
boxes tones on the the coke oven
pusher side
side
67 68 69 32 16 16 32 25 03 7

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 Saving of Coke Oven Gas by Reduction of Smoke Pushing of Recovery Type Coke Plant

CPD = 17.67 hrs V4 = 17622.22Nm3 /hrs

The average gas flow required the entire first to the fourth
2.3 Requirement of Coke Oven Gas Flow as week which is given below
per Schedule of Pushing/Charging V1 + V2 + V3 + V4
V=
2.3 represent the mathematical formula for calculating 4
the required gas flow:
V = 17622.22Nm3 /hrs
W × Q × N × 1000
V=
T × CV
V = 17600Nm3 /hrs (approx)
First-week average coke oven gas flow required on an
hourly basis before rectification Similarly, after rectification average coke oven gas flow
required the entire first week to the fourth week which is
610 × 91× 32 × 1000
V1 = given below
4200 × 24
V1 + V2 + V3 + V4
V=
V1 = 17622.22Nm /hrs 3 4
second-week average coke oven gas flow required on an
hourly basis before rectification V=17333.33Nm3 /hrs

610 × 91× 32 × 1000

V2 = V=17300Nm3 /hrs (approx)
4200 × 24
All mathematical calculation value is shown in the
V2 = 17622.22Nm3 /hrs tabulation form which is elaborated in Table 2.

third-week average coke oven gas flow required on an

hourly basis before rectification 3.0 Results with Discussion
610 × 91× 32 × 1000 3.1 Rectification of Smoke Pushing
V3 =
4200 × 24
In this paper, it is introduced that a quantitative emission
of carbon formation rate on the wall was developed and a
V3 = 17622.22Nm3 /hrs new type of SOP for regular maintenance of gas paths like
fourth-week average coke oven gas flow required on an distribution pipe cleaning, orifice cleaning, and cylinder
hourly basis before rectification and horse pipe cleaning as a daily routine basis, as results
all flues like pusher side and coke side temperature will
610 × 91× 32 × 1000 be gradually increased. This method is also helpful for
V4 =
4200 × 24 reducing coke oven gas flow. Firstly we have taken the

Table 2. Heating wall No. 26 pusher side flue wise temperature

Flue No. 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16
The 1080 1090 1110 1160 1180 1170 1190 1200 1200 1210 1190 1210 1200 1210 1190 1200
temperature
in °C before
rectification
The 1110 1120 1150 1180 1200 1210 1220 1230 1220 1230 1210 1220 1230 1220 1210 1220
temperature
in °C after
rectification

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 Niranjan Mahato, Himanshu Agarwal and Jainendra Jain

Table 3. Heating wall No.26 coke side flue wise temperature

Flue No. 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
The 1200 1190 1210 1200 1220 1210 1200 1200 1190 1170 1160 1140 1110 1090 1070 1060
temperature
in °C before
rectification
The 1220 1220 1230 1240 1250 1250 1230 1210 1200 1190 1180 1170 1150 1140 1130 1120
temperature
in °C after
rectification

temperature reading of particular problematic heating

wall No.26. The temperature reading is taken on the
pusher side sixteen flues and coke side also sixteen flues
before and after rectification of smoke pushing which is
shown in Tables 2 and 3 then is plotted in a graph which
is already shown in Figures 1 and 2.
Tables 2 and 3 comprise the problematic heating
wall No. 26. The temperature reading is taken on the
pusher side sixteen flues and the coke side also sixteen
flues before rectification temperature of all flues is not
uniform. The maximum temperature before rectification
is 1220°C, then after a new type of SOP is developed for Figure 1. Variation of temperature for pusher side flue
regular maintenance of gas paths like distribution pipe number.
cleaning, orifice cleaning, and cylinder and horse pipe
cleaning on a daily routine basis, as a result, all flues like
pusher side and coke side temperature will be gradually
increased. After rectification, the maximum temperature
is 1250°C, as a result, smoke pushing is controlled and
the unwanted heat losses are also controlled and the coke
oven gas flow is also saved at 300 Nm3/hrs.
Figure 1 comprises the variation of temperature with
respect to the pusher side flue number. There are sixteen
heating flues on the pusher side. Firstly temperature
reading is taken of each flue by using the digital pyrometer.
The temperature reading is given in Table 2 which can be
plotted on a graph in Figure 1. The temperature is gradually Figure 2. Variation of temperature for coke side flue
increasing with respect to the heating flue number. The number.
temperature is starting from 1080°C for heating flue
number 01, the 2nd flue increases the temperature to 1120°C and the 3rd flue temperature is around 1150°C.
1090°C and the 3rd flue temperature is around 1110°C. so that after the rectification temperature is increased by
The maximum temperature reaches 1210°C in flue 30°C of 1ist flue, 2nd flue temperature increased by 30°C
number 10 of the pusher side before rectification. The and 3rd flue temperature is increased by 40°C without
minimum temperature reaches is around 1080°C and the affecting the quality of coke. So that after rectification.
maximum temperature is 1210°C before rectification of The maximum temperature is increased from 1210°C to
smoke pushing. After the rectification of smoke pushing 1230°C in pusher side heating flues.
the temperature is starting from 1110°C of heating flue Figure 2 comprises the variation of temperature with
number 01, the 2nd flue increases the temperature to respect to the pusher side flue number. There are sixteen

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 Saving of Coke Oven Gas by Reduction of Smoke Pushing of Recovery Type Coke Plant

heating flues on the coke side. Firstly temperature reading By using this methodology coke oven gas flow
is taken of each flue by using the digital pyrometer. The requirement is reduced from 17600 Nm3/hrs to 17300
temperature reading is given in Table 3 which can be Nm3/hrs without affecting the quality of coke. The average
plotted on the graph in Figure 2. The temperature is pushing/charging schedule remains constant before and
gradually increasing with respect to the heating flue the after rectification of smoke pushing on the recovery
number. The temperature is starting from 1200°C for type of coke oven plant.
heating flue number 17th, then18th the flue decreases Figure 4 comprises the experimental value of specific
the temperature to 1190°C and the 19th flue temperature heat consumption with respect to the number of weeks.
is around 1210°C. The maximum temperature reaches Specific heat consumption is directly proportional to the
1220°C in flue number 21st of the coke side before gas flow requirement. Firstly requirement of the coke oven
rectification. The minimum temperature reaches is
around 1060°C and the maximum temperature is 1220°C
before rectification of smoke pushing in the coke side of
heating flues. After the rectification of smoke pushing
the temperature is starting from 1220°C of heating flue
number 17th, the 18th flue increases the temperature to
1220°C and the 19th flue temperature is around 1230°C
so that after the rectification temperature is increased
by 20°C of 17th flue, 18th flue temperature increased
by 30°C and 19th flue temperature is increased by 20°C
without affecting the quality of coke after rectification.
The maximum temperature is increased from 1220°C to
1250°C on the coke side of the heating flues.
In Figures 1 and 2 excluding before rectification Figure 3. Variation of coke oven gas flow for No. of weeks.
of smoke pushing to each flue of the pusher side, the
maximum temperature is achieved as 1220°C. After
rectification, the maximum temperature is 1250°C, as
a result, smoke pushing is controlled and the unwanted
heat losses are also controlled and the coke oven gas flow
is reduced from 17600 to 17300 Nm3/hrs.
Figure 3 comprises the requirement of coke oven gas
flow requirement with respect to the number of weeks.
There are four weeks taken average reading is taken for
the requirement of coke oven gas flow. Firstly before
rectification of smoke pushing gas flow requirement is
about 17600 Nm3/hrs which is shown in graphical form
Figure 3. After the rectification of smoke pushing gas flow
requirement is about 17300 Nm3/hrs. Figure 4. Variation of specific heat consumption for the
Number of weeks.

Table 4. Experimental calculation value before and after rectification

No. of weeks Average Before After Before After rectification Average COG
average pushing / rectification rectification rectification average saving on an
experimental charging average gas average gas flow average specific heat hourly basis
data schedule flow required in required Nm3/ specific heat consumption
Nm3/hrs hrs consumption in kcal/kg
kcal/kg
04 91 17600 17300 610 600 300

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 Niranjan Mahato, Himanshu Agarwal and Jainendra Jain

gas flow is about 17600 Nm3/hrs then after rectification 6.0 References
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