Title of Invention	A NEW METHOD FOR IMPROVING COKE STRENGTH BY WATER QUENCHING AND THE PROCESS THEREOF
Abstract	A method of improving coke strength by water at 1000°C in coke oven battery; - quenching the carbonised coke in a quenching car with a facility to quench pushed coke with help of water from top and side and facility of draining out water from bottom which comprises a first top quenching for at least 15-20sec; - thereafter 15-20 second for side quenching; - keeping 20-25 second gap between side quenching and second top quenching; - a second top quenching for at least 40-45 sec; - the quenched coke samples were collected and a screening analysis on 100mm, 50mm, 40mm, 30mm, 20mm and 10mm size screens were carried out; - a plus 50mm size coke of 50Kg lots were selected for carrying out CSR & CRI, M40, M10 test; comparing test results of quenched coke from parameters coke strength after reaction (CSR). Coke reactivity index (CRI), M40, M10, micro-fissure and moisture content of coke to find out metallurgical grade coke on cooling carbonised high temperature coal blend.

Title of Invention

A NEW METHOD FOR IMPROVING COKE STRENGTH BY WATER QUENCHING AND THE PROCESS THEREOF

Abstract

A method of improving coke strength by water at 1000°C in coke oven battery; - quenching the carbonised coke in a quenching car with a facility to quench pushed coke with help of water from top and side and facility of draining out water from bottom which comprises a first top quenching for at least 15-20sec; - thereafter 15-20 second for side quenching; - keeping 20-25 second gap between side quenching and second top quenching; - a second top quenching for at least 40-45 sec; - the quenched coke samples were collected and a screening analysis on 100mm, 50mm, 40mm, 30mm, 20mm and 10mm size screens were carried out; - a plus 50mm size coke of 50Kg lots were selected for carrying out CSR & CRI, M40, M10 test; comparing test results of quenched coke from parameters coke strength after reaction (CSR). Coke reactivity index (CRI), M40, M10, micro-fissure and moisture content of coke to find out metallurgical grade coke on cooling carbonised high temperature coal blend.

Full Text	FIELD OF INVENTION The present invention relates to a method for improving coke strength. More particularly it relates to a method for improving metallurgical coke strength by water quenching after carbonization in coke oven battery adaptable to blast furnace use. BACKGROUND OF THE INVENTION It has been established that upon quenching the coke undergoes the same physico-mechanical changes as any solid. Depending on the rate of cooling, the stress in coke pieces of various sizes and shapes act in different ways. When these stresses exceed their threshold limits, it leads to weakening of coke due to formation of cracks and micro fissures. The hot red coke is pushed out from the oven; its appearance is characterized by a network of fissures extending throughout the coke mass, with a large central crack running through the height of the oven. During the subsequent quenching, handling and screening operations, breakage tends to occur along these fissures. It is a fact that coke is heterogeneous with respect to its physical properties, in that it contains fissures, cracks and other weaknesses and hence, the strength of the coke is determined by the degree of fissuring and other weaknesses in the coke. These flaws in the structure of coke, which determine its behaviour in use, stem from the composition, preparation of the charge to the oven and on the condition of carbonization. The prior art investigations carried out by different authors have shown that the electric resistivity, the heat of wetting, reactivity, volume changes and other physico-mechanical and physico-chemical properties reflect changes in the structure of coke at different energy levels. In high temperature range, where the structure is denser and more strongly stressed, at the coke pushing temperature (1000 to 850°C) the quenching rate must be minimal as possible. When the final temperature from 850-650°C is maintained the coke structure is still quite stressed and the temperature gradient between the surface of the coke and center being rather high, the quenching rate can be increased slightly. When the final temperature range from 650-200°C is maintained the rate of quenching may be increased to such an extent as to prevent the generation of stress exceeding the ultimate strength of the coke. It has not yet been established conclusively to what extent residual fissures influence the mechanical strength of cokes. In part, the difficulty in assessing their role lies in the lack of comprehensive methods of characterization, which enable fissuring to be quantified and compared. It is quite evident from the analysis of coke made through various quenching methods described above that the strength characteristics of coke depends not only on the selection of coal and preparation of coal blends for coking, but also on the method of quenching of coke after it is pushed from coke oven chamber. The present invention is aimed to solve the difficulties of prior arts as narrated above to solve the long standing and extent problem in coke quenching to fond out appropriate cooling method. OBJECTS OF THE INVENTION It is therefore, an object of the present invention to propose a method of improving coke strength by water quenching which eliminates the disadvantage of existing state of Arts. Another object of the present invention is to propose a method of improving coke strength by water quenching which decreases residual fissures in coke. A further object of the present invention is to propose a method of improving coke strength by water quenching which is eco-friendly. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Fig 1 relates to effect of top quenching on M40 and M10 Fig 2 shows effect of top quenching on CSR and CRI Fig 3 represents effect of top quenching on micro-fissures and moisture of coke Fig 4- shows effect of side quenching on M40 and M10 Fig 5- shows effect of side quenching on CSR and CRI Fig 6- shows effect of side quenching on moisture and micro fissures Fig 7- relates to effect of quenching gap on M40 and M10 Fig 8- shows effect of quenching gap on CSR and CRI Fig 9- represents effect of quenching gap on micro-fissures and moisture DETAILS DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION The present invention comprises of a quenching tower to cool hot coke. A quenching tower is a reinforced concrete frame with brick line structure. The water used for quenching is recycled after settling in the breeze pond and pumped up to the overhead tanks of the quenching tower. Near coke oven battery a semi flood quench system is employed, which means the water sprayed on the quenching car is not allowed to drain away and creates a pool of water in the quenching car. The coke floats in the car, levels itself and gets quenched more uniformly and instantly. A quenching method was developed to study the effect of coke quenching under different condition in coke oven battery under existing condition of quenching system (See Table 1) The coke samples after quenching were collected from wharf for each trial. Each sample was subjected to screen analysis on 100mm, 80mm, 50mm, 40mm, 30mm, 20mm and 10mm size screens. The plus 50mm size coke (50Kg lot) was stabilized and M40, M10, CSR & CRI were determined. The fissure analysis was done in Quantimet 550 Image analyzer using Leica software. The coke was sliced to 25mm X25 X 15mm and subjected to image analyzer and total area was measured. Area of each micro fissures present in total area was measured in manual mode then area percentages of micro fissures were calculated. In this analysis differentiation was made between pores and fissures. In pores, length was considered equal to width whereas, in fissures, it was assumed that length was not equal to width and the basic parameters recorded were area, perimeter, breadth and length. Figures 1 to 9 shown the parameters in the ordinates in coke quality parameter with respect of top quenching condition, side quenching and gap between two quenching cooling method, herein denoted in the abscissae as quenching conditions. The parameters used are coke strength after reaction (CSR), coke reactivity index (CRI), Micum Indices (M40 and M10), micro-fissures and coke moisture. The starting material utilized in the process may be derived from any coal source which is suitable for metallurgical coke making and coke quality parameter can be determined by standard practice. For evaluation of quality of coke on cooling the said parameters are compared with the 10,15 and 20 seconds of quenching with water the carbonized coke from 1000°C. Good quality coke is assessed for room temperature strength which is important at the time of charging and in stock zone of blast furnace. It was observed that from the graph in Figure 1, 4 and 7 that slow cooling improves M40 and M10 decreases due to which performance of coke in stack zone of blast furnaces improves. Fig 3, 6 and 9 showed that micro-fissures and coke moisture is lower with compared to higher cooling rate. Considering all the aspects from above test results it is recommended that methods of 15 seconds top quenching, 15 seconds of side quenching and keeping 20 seconds gap between side quenching and second top quenching of 40 seconds most suitable fro carbonized coke cooling. But the present invention qualify an improved process guides to produce metallurgical grade of coke applicable to all the above three quenching conditions on precise process control to be maintained with slow cooling rate when quenched in water from higher temperature. The proposed invention has developed methods of cooling of carbonized coke at high temperature (1000°C) of different combinations of quenching conditions through characterize evaluation from test results to maintain compatible coke strength after carbonization to produce metallurgical grade coke. The invention as narrated hereinabove and illustrated with an exemplary embodiment of the invention should not be read and construed in a restrictive manner as various modifications of the apparatus, adaptations and alterations of the constructive parts of the apparatus and method steps, coke sizes and process control steps are possible within the scope and limit of the invention as defined in the encompassed appended claims. TABLE: 1 PROPOSED QUENCHING METHOD FOR EXPERIMENTATION P - positioning; T1-1st Top quenching; G- Gap; S- Side quenching T2 - 2nd Top quenching WE CLAIM 1. A method of improving coke strength by water quenching comprises:- - carbonisation of coal at 1000°C in coke oven battery; - quenching the carbonised coke in a quenching car with a facility to quench pushed coke with help of water from top and side and facility of draining out water from bottom which comprises a first top quenching for at least 15-20sec; - thereafter 15-20 second for side quenching; - keeping 20-25 second gap between side quenching and second top quenching; - a second top quenching for at least 40-45 sec; - the quenched coke samples were collected and a screening analysis on 100mm, 50mm, 40mm, 30mm, 20mm and 10mm size screens were carried out; - a plus 50mm size coke of 50Kg lots were selected for carrying out CSR & CRI, M40, M10 test; - comparing test results of quenched coke from parameters coke strength after reaction (CSR). Coke reactivity index (CRI), M40, M10, micro-fissure and moisture content of coke to find out metallurgical grade coke on cooling carbonised high temperature coal blend. 2. The method as claimed in claim 1 wherein the fissure analysis was carried out in Quantimet 550 image analyzer using lica software. 3. The method as claimed in claim 2 wherein coke was sliced to 25mm X 25mm x 15mm and was subjected to image analyzer and total area were measured. 4. The method as claimed in claim 3 wherein area of each micro fissures present in total area was measured in manual mode then area percentages of micro-fissures were calculated. 5. The method as claimed in claim 1 wherein CSR and CRI were carried out in a conventional testing procedure. A method of improving coke strength by water quenching comprises:- - carbonisation of coal at 1000°C in coke oven battery; - quenching the carbonised coke in a quenching car with a facility to quench pushed coke with help of water from top and side and facility of draining out water from bottom which comprises a first top quenching for at least 15-20sec; - thereafter 15-20 second for side quenching; - keeping 20-25 second gap between side quenching and second top quenching; - a second top quenching for at least 40-45 sec; - the quenched coke samples were collected and a screening analysis on 100mm, 50mm, 40mm, 30mm, 20mm and 10mm size screens were carried out; - a plus 50mm size coke of 50Kg lots were selected for carrying out CSR & CRI, M40, M10 test; comparing test results of quenched coke from parameters coke strength after reaction (CSR). Coke reactivity index (CRI), M40, M10, micro-fissure and moisture content of coke to find out metallurgical grade coke on cooling carbonised high temperature coal blend.

Full Text

FIELD OF INVENTION
The present invention relates to a method for improving coke strength. More
particularly it relates to a method for improving metallurgical coke strength by
water quenching after carbonization in coke oven battery adaptable to blast
furnace use.
BACKGROUND OF THE INVENTION
It has been established that upon quenching the coke undergoes the same
physico-mechanical changes as any solid. Depending on the rate of cooling, the
stress in coke pieces of various sizes and shapes act in different ways. When
these stresses exceed their threshold limits, it leads to weakening of coke due to
formation of cracks and micro fissures. The hot red coke is pushed out from the
oven; its appearance is characterized by a network of fissures extending
throughout the coke mass, with a large central crack running through the height
of the oven. During the subsequent quenching, handling and screening
operations, breakage tends to occur along these fissures. It is a fact that coke is
heterogeneous with respect to its physical properties, in that it contains fissures,
cracks and other weaknesses and hence, the strength of the coke is determined
by the degree of fissuring and other weaknesses in the coke. These flaws in the
structure of coke, which determine its behaviour in use, stem from the
composition, preparation of the charge to the oven and on the condition of
carbonization.

The prior art investigations carried out by different authors have shown that the
electric resistivity, the heat of wetting, reactivity, volume changes and other
physico-mechanical and physico-chemical properties reflect changes in the
structure of coke at different energy levels.
In high temperature range, where the structure is denser and more strongly
stressed, at the coke pushing temperature (1000 to 850°C) the quenching rate
must be minimal as possible. When the final temperature from 850-650°C is
maintained the coke structure is still quite stressed and the temperature gradient
between the surface of the coke and center being rather high, the quenching
rate can be increased slightly. When the final temperature range from 650-200°C
is maintained the rate of quenching may be increased to such an extent as to
prevent the generation of stress exceeding the ultimate strength of the coke.
It has not yet been established conclusively to what extent residual fissures
influence the mechanical strength of cokes. In part, the difficulty in assessing
their role lies in the lack of comprehensive methods of characterization, which
enable fissuring to be quantified and compared.
It is quite evident from the analysis of coke made through various quenching
methods described above that the strength characteristics of coke depends not
only on the selection of coal and preparation of coal blends for coking, but also
on the method of quenching of coke after it is pushed from coke oven chamber.
The present invention is aimed to solve the difficulties of prior arts as narrated
above to solve the long standing and extent problem in coke quenching to fond
out appropriate cooling method.

OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose a method of
improving coke strength by water quenching which eliminates the disadvantage
of existing state of Arts.
Another object of the present invention is to propose a method of improving
coke strength by water quenching which decreases residual fissures in coke.
A further object of the present invention is to propose a method of improving
coke strength by water quenching which is eco-friendly.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig 1 relates to effect of top quenching on M40 and M10
Fig 2 shows effect of top quenching on CSR and CRI
Fig 3 represents effect of top quenching on micro-fissures and moisture of
coke
Fig 4- shows effect of side quenching on M40 and M10
Fig 5- shows effect of side quenching on CSR and CRI
Fig 6- shows effect of side quenching on moisture and micro fissures
Fig 7- relates to effect of quenching gap on M40 and M10
Fig 8- shows effect of quenching gap on CSR and CRI
Fig 9- represents effect of quenching gap on micro-fissures and moisture

DETAILS DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
The present invention comprises of a quenching tower to cool hot coke. A
quenching tower is a reinforced concrete frame with brick line structure. The
water used for quenching is recycled after settling in the breeze pond and
pumped up to the overhead tanks of the quenching tower. Near coke oven
battery a semi flood quench system is employed, which means the water sprayed
on the quenching car is not allowed to drain away and creates a pool of water in
the quenching car. The coke floats in the car, levels itself and gets quenched
more uniformly and instantly. A quenching method was developed to study the
effect of coke quenching under different condition in coke oven battery under
existing condition of quenching system (See Table 1)
The coke samples after quenching were collected from wharf for each trial. Each
sample was subjected to screen analysis on 100mm, 80mm, 50mm, 40mm,
30mm, 20mm and 10mm size screens. The plus 50mm size coke (50Kg lot) was
stabilized and M40, M10, CSR & CRI were determined.
The fissure analysis was done in Quantimet 550 Image analyzer using Leica
software. The coke was sliced to 25mm X25 X 15mm and subjected to image
analyzer and total area was measured. Area of each micro fissures present in
total area was measured in manual mode then area percentages of micro
fissures were calculated. In this analysis differentiation was made between pores
and fissures. In pores, length was considered equal to width whereas, in fissures,
it was assumed that length was not equal to width and the basic parameters
recorded were area, perimeter, breadth and length.
Figures 1 to 9 shown the parameters in the ordinates in coke quality parameter
with respect of top quenching condition, side quenching and gap between two

quenching cooling method, herein denoted in the abscissae as quenching
conditions. The parameters used are coke strength after reaction (CSR), coke
reactivity index (CRI), Micum Indices (M40 and M10), micro-fissures and coke
moisture. The starting material utilized in the process may be derived from any
coal source which is suitable for metallurgical coke making and coke quality
parameter can be determined by standard practice.
For evaluation of quality of coke on cooling the said parameters are compared
with the 10,15 and 20 seconds of quenching with water the carbonized coke
from 1000°C. Good quality coke is assessed for room temperature strength
which is important at the time of charging and in stock zone of blast furnace. It
was observed that from the graph in Figure 1, 4 and 7 that slow cooling
improves M40 and M10 decreases due to which performance of coke in stack zone
of blast furnaces improves. Fig 3, 6 and 9 showed that micro-fissures and coke
moisture is lower with compared to higher cooling rate.
Considering all the aspects from above test results it is recommended that
methods of 15 seconds top quenching, 15 seconds of side quenching and
keeping 20 seconds gap between side quenching and second top quenching of
40 seconds most suitable fro carbonized coke cooling. But the present invention
qualify an improved process guides to produce metallurgical grade of coke
applicable to all the above three quenching conditions on precise process control
to be maintained with slow cooling rate when quenched in water from higher
temperature. The proposed invention has developed methods of cooling of
carbonized coke at high temperature (1000°C) of different combinations of
quenching conditions through characterize evaluation from test results to
maintain compatible coke strength after carbonization to produce metallurgical
grade coke.
The invention as narrated hereinabove and illustrated with an exemplary
embodiment of the invention should not be read and construed in a restrictive

manner as various modifications of the apparatus, adaptations and alterations of
the constructive parts of the apparatus and method steps, coke sizes and
process control steps are possible within the scope and limit of the invention as
defined in the encompassed appended claims.
TABLE: 1 PROPOSED QUENCHING METHOD FOR EXPERIMENTATION

P - positioning; T1-1st Top quenching; G- Gap; S- Side quenching
T2 - 2nd Top quenching

WE CLAIM
1. A method of improving coke strength by water quenching comprises:-
- carbonisation of coal at 1000°C in coke oven battery;
- quenching the carbonised coke in a quenching car with a facility to
quench pushed coke with help of water from top and side and facility of
draining out water from bottom which comprises a first top quenching for
at least 15-20sec;
- thereafter 15-20 second for side quenching;
- keeping 20-25 second gap between side quenching and second top
quenching;
- a second top quenching for at least 40-45 sec;
- the quenched coke samples were collected and a screening analysis on
100mm, 50mm, 40mm, 30mm, 20mm and 10mm size screens were
carried out;
- a plus 50mm size coke of 50Kg lots were selected for carrying out CSR &
CRI, M40, M10 test;
- comparing test results of quenched coke from parameters coke strength
after reaction (CSR). Coke reactivity index (CRI), M40, M10, micro-fissure
and moisture content of coke to find out metallurgical grade coke on
cooling carbonised high temperature coal blend.

2. The method as claimed in claim 1 wherein the fissure analysis was carried
out in Quantimet 550 image analyzer using lica software.
3. The method as claimed in claim 2 wherein coke was sliced to 25mm X
25mm x 15mm and was subjected to image analyzer and total area were
measured.

4. The method as claimed in claim 3 wherein area of each micro fissures
present in total area was measured in manual mode then area
percentages of micro-fissures were calculated.
5. The method as claimed in claim 1 wherein CSR and CRI were carried out
in a conventional testing procedure.

A method of improving coke strength by water quenching comprises:-
- carbonisation of coal at 1000°C in coke oven battery;
- quenching the carbonised coke in a quenching car with a facility to
quench pushed coke with help of water from top and side and facility of
draining out water from bottom which comprises a first top quenching for
at least 15-20sec;
- thereafter 15-20 second for side quenching;
- keeping 20-25 second gap between side quenching and second top
quenching;
- a second top quenching for at least 40-45 sec;
- the quenched coke samples were collected and a screening analysis on
100mm, 50mm, 40mm, 30mm, 20mm and 10mm size screens were
carried out;
- a plus 50mm size coke of 50Kg lots were selected for carrying out CSR &
CRI, M40, M10 test;
comparing test results of quenched coke from parameters coke strength
after reaction (CSR). Coke reactivity index (CRI), M40, M10, micro-fissure
and moisture content of coke to find out metallurgical grade coke on
cooling carbonised high temperature coal blend.

Documents:

01214-kol-2008-abstract.pdf

01214-kol-2008-claims.pdf

01214-kol-2008-correspondence others.pdf

01214-kol-2008-description complete.pdf

01214-kol-2008-drawings.pdf

01214-kol-2008-form 1.pdf

01214-kol-2008-form 2.pdf

01214-kol-2008-form 3.pdf

01214-kol-2008-gpa.pdf

1214-KOL-2008-(16-01-2012)-AMANDED CLAIMS.pdf

1214-KOL-2008-(16-01-2012)-CORRESPONDENCE-1.pdf

1214-KOL-2008-(16-01-2012)-CORRESPONDENCE.pdf

1214-KOL-2008-(16-01-2012)-DESCRIPTION (COMPLETE).pdf

1214-KOL-2008-(16-01-2012)-DRAWINGS.pdf

1214-KOL-2008-(16-01-2012)-FORM 1.pdf

1214-KOL-2008-(16-01-2012)-FORM 2.pdf

1214-KOL-2008-(16-01-2012)-OTHERS.pdf

1214-KOL-2008-(16-01-2012)-PETITION UNDER RULE 137.pdf

1214-KOL-2008-CANCELLED PAGES.pdf

1214-KOL-2008-CORRESPONDENCE.pdf

1214-KOL-2008-EXAMINATION REPORT.pdf

1214-kol-2008-form 18.pdf

1214-KOL-2008-FORM 3.pdf

1214-KOL-2008-GPA.pdf

1214-KOL-2008-GRANTED-CLAIMS.pdf

1214-KOL-2008-GRANTED-DESCRIPTION (COMPLETE).pdf

1214-KOL-2008-GRANTED-DRAWINGS.pdf

1214-KOL-2008-GRANTED-FORM 1.pdf

1214-KOL-2008-GRANTED-FORM 2.pdf

1214-KOL-2008-GRANTED-FORM 3.pdf

1214-KOL-2008-GRANTED-SPECIFICATION-COMPLETE.pdf

1214-KOL-2008-OTHERS.pdf

1214-KOL-2008-PETITION UNDER RULE 137.pdf

1214-KOL-2008-REPLY TO EXAMINATION REPORT.pdf

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Patent Number

258898

Indian Patent Application Number

1214/KOL/2008

PG Journal Number

07/2014

Publication Date

14-Feb-2014

Grant Date

13-Feb-2014

Date of Filing

16-Jul-2008

Name of Patentee

TATA STEEL LIMITED

Applicant Address

RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR

Inventors:

#	Inventor's Name	Inventor's Address
1	MR. RAMESHWAR SHARMA	TATA STEEL LIMITED RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR
2	MR. A K CHOUDHURY	TATA STEEL LIMITED RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR
3	MR. A KUMAR	TATA STEEL LIMITED RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR
4	MR. DHARMENDRA KUMAR	TATA STEEL LIMITED RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR

PCT International Classification Number

B65G69/18

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA