Title of Invention	A SYSTEM FOR IMPROVED COAL BLEND PREPARATION WITH ADDITION OF A WATER-OIL EMULSION AND METHOD OF ITS IMPLEMENTATION
Abstract	A system for preparing coal blend with a water-oil emulsion comprising oil tank (1) and water tank (2) being pumped to an emulsion tank(5) for preparing water-oil emulsion, supplying emulsion from the emulsion tank to coal transfer hopper(8) having emulsion sprayers in the top region having a coal feeding conveyor(9) in the vicinity thereof, to obtain 0.03 wt.% oil and 0.18 wt.% water in form of emulsion in coal blend preferably following a method using said system, discharging the emulsion blended coal from the said hopper to a primary crusher(6) for effectively crushing the coal blend to finer coal, transporting the crushed blend to a pneumatic classifier(10), discharging fines from the pneumatic classifier as product and feeding the coarse grain from the pneumatic classifier to a second crusher(7) for crushing the coarse coat blend water-oil emulsion leaving the classifier into a finer grains, and for recycling the fine discharge therein.

Title of Invention

A SYSTEM FOR IMPROVED COAL BLEND PREPARATION WITH ADDITION OF A WATER-OIL EMULSION AND METHOD OF ITS IMPLEMENTATION

Abstract

A system for preparing coal blend with a water-oil emulsion comprising oil tank (1) and water tank (2) being pumped to an emulsion tank(5) for preparing water-oil emulsion, supplying emulsion from the emulsion tank to coal transfer hopper(8) having emulsion sprayers in the top region having a coal feeding conveyor(9) in the vicinity thereof, to obtain 0.03 wt.% oil and 0.18 wt.% water in form of emulsion in coal blend preferably following a method using said system, discharging the emulsion blended coal from the said hopper to a primary crusher(6) for effectively crushing the coal blend to finer coal, transporting the crushed blend to a pneumatic classifier(10), discharging fines from the pneumatic classifier as product and feeding the coarse grain from the pneumatic classifier to a second crusher(7) for crushing the coarse coat blend water-oil emulsion leaving the classifier into a finer grains, and for recycling the fine discharge therein.

Full Text	Introduction to the Field of Invention: Improvements in or relating to the method of processing blend coal suited for coke oven use. This invention relates to improvements in or relating to the method of processing blend coal suited for coke oven use and a system therefore. Prior Art and Drawbacks: It is well known to process coal, taken from the bunker, before feeding to the coke oven to crush to 0-3 mm size without producing more fines (-0.25 mm). In general, fine coals with > 8% moisture content become sticky mass and do not allow free flow in transfer chutes. It affects size separation systems. High moisture content also reduces bulk density of fine coals. As a result, productivity of coal preparation plant and quality of coal prepared are affected. The problem has been solved to a certain extent by the addition of oil to the extent of 0.1 to 0.5 wt.% to the coal. This has to a limited extent solved or improved the How problem and to improved bulk density of moist fine coals. But there is a drawback due to high combustibility of oil used with combustible coal and extra fire safety measure is needed till oiled coal is consumed. Besides, oil is a costly material. For this reason only oil addition system on fine coal is rarely used in the industry. Moreover, the amount of oil used adds up to the cost and affects the economy of the process. Objects of the Invention; It is therefore an object of this invention to propose an improved method for the processing of coal economically before feeding to the coke oven. It is another object to propose a method, which will enable fluidization of fine coal preferably from the coarse fraction in the pneumatic classifier even with moisture more than 8 wt.%. It is a further object of this invention to propose such a method, which will ensure processed coal having substantially lower fine fractions (-0.25 mm) coal suited for coke oven. Another object of the invention is to propose such a processing of coal, which will consume minimum oil compared to the amount of oil consumed in the known art. Yet another object is to propose such a process, which will be free of blockage of processing units and ensure free flow of coal at different units during processing. A still further object of this invention is to propose such a process, which can use any waste oil (hydro carbon) having low viscosity and will thus improve the economy of the process. A further object of this invention is to propose such a process, which will increase the bulk density of processed coal enabling increased oven throughput. Yet another object of this invention is to propose a novel system for processing coal before making it suitable for coke oven operation. These and other objects of the invention will be clear from the following paragraphs. Brief Statement of the Invention: According to one aspect of the present invention is directed to a system for improved coal blend preparation with addition of a water-oil emulsion to improve flowability and bulk density of coal blend by reducing friction in between the coal particles, for feeding to coke oven comprising: an oil storage tank operatively connected to a pump for supply of oil to a emulsion tank; a water storage tank operatively connected to a pump for supply of water to said emulsion tank; pump with flame proof motor means for supplying emulsion from the emulsion tank to coal transfer hopper at desired rate; said coal transfer hopper is fed through chutes having emulsion sprayers in the top region with coal feeding conveyor in the vicinity thereof; said coal transfer hopper having a discharge spout at its lower end adopted to discharge the emulsion blended coal to a primary crusher for effectively crushing the coal-emulsion blend to finer coal and a transport unit provided below the discharge end of the primary crusher; a pneumatic classifier provided at the discharge end of the said transport unit for receiving the coal- emulsion blend from the primary crusher ; said pneumatic classifier having a coarse grain discharge means and fine grains product discharge means; the pneumatic classifier being operatively connected through a second blend transport hopper to a secondary crusher for crushing the coarse coal blended with water-oil emulsion leaving the classifier into a finer grains; said secondary crusher having a fine grain discharge means and transport means for recycling the finer discharge from the secondary crusher to the said pneumatic classifier, wherefrom the final coal-emulsion blend charge is taken out as stream through the outlet. The means for supplying water and oil from their respective sources are pump means and the emulsion tank is provided with a pump for feeding the emulsion to the sprayers in the coal transfer hopper. The coal feeding conveyor is a conveyor belt arranged to transfer coal from the blending bunker and the conveyor is arranged preferably at a level higher than the emulsion sprayer. A coal transfer hopper has a discharge spout at its lower end for the discharge of coal water- oil emulsion mixture, has preferably a cylindrical cross-section at the top and a conical cross section to the bottom and wherein the water-oil emulsion sprayers and the coal conveyors are disposed at the upper cylindrical section. Preferably the coal transfer hopper is positioned at the highest level in the system so as to allow gravity flow of the coal water oil emulsion mixture into the primary crusher and the primary crusher is positioned vertically provided below the coal transfer hopper. The discharge spout of the primary crusher is at its lower end and positioned above a transport belt. The pneumatic classifier of the present system preferably mounted in a position so that its top end is located above the discharge end of the primary crusher and separate conveyor belts are arranged to operatively transport the crushed coal output of the primary and secondary crusher from the respective discharge spout at lower end of each said crusher to the upper end of the pneumatic classifier, for recycling the products obtained from the crushers to the pneumatic classifier. Said pneumatic classifier has an outlet for fine grained coal btended with oil-water emulsion at preferred elevation from the bottom end of the classifier and a discharge spout at the lower end for the discharge of coarse grain water-oil coal blend on to a transport conveyor transporting the same to the secondary transport hopper. The secondary transport hopper is provided with a feeder for water-oil emulsion from the emulsion tank and is arranged preferably vertically below the secondary transport hopper and is identical in construction and function to the primary crusher and converts the coarse grain water-oil blend discharged by the pneumatic classifier into a finer grains. The secondary crusher has a discharge spout at its lower end and operatively connected by transport means to the top of the pneumatic classifier for recycling the product of the secondary crusher to the pneumatic classifier. According to another aspect of the present invention directed to a method for preparing coal, blended with a water-oil emulsion using the system of the invention comprising providing an oil storage tank and a water storage tank, an emulsion tank for preparing water-oil emulsion, supplying water and oil at desired rate, from their respective storage tanks to the emulsion tank, subjecting to emulsification, preferably to obtain 0.03 wt.% oil and 0.18 wt.% water in form of emulsion in coal blend, supplying emulsion from the emulsion tank to coal transfer hopper, having emulsion sprayers in the top region with coal feeding conveyor in the vicinity thereof, discharging the emulsion blended coal from the said hopper to a primary crusher for effectively crushing the coal water-oil emulsion blend to finer coal, transporting the crusher blend from the primary crusher to a pneumatic classifier, discharging fines from the pneumatic classifier as product and feeding the coarse grain blend from the pneumatic classifier through a second transport hopper to a second crusher for crushing the coarse coal blend water-oil emulsion leaving the classifier into a finer grains, and for recycling the fine discharge from the secondary crusher to the said pneumatic classifier such that the favored improved bulk density in final blend is obtained at final outlet from the pneumatic classifier. In this method the following features are preferred for successfully carrying out the method: a. the emulsion tank is provided with a pump for feeding the emulsion to the sprayers in the coal transfer hopper, b. coal transfer hopper has a discharge spout at its lower end for the discharge of coal water-oil emulsion mixture and the coal transfer hopper has preferably a cylindrical cross-section at the top and a conical cross section at the bottom and wherein the water-oil emulsion sprayers and the coal conveyors are disposed at the upper cylindrical section. c. the coal transfer hopper is positioned at the highest level in the system so as to allow gravity flow of the coal water oil emulsion mixture into the primary crusher, d. the primary crusher is positioned vertically provided below the coal transfer hopper and the discharge spout of the primary crusher is at its lower end and positioned above a transport belt, e. the pneumatic classifier is preferably mounted such that its top end is above the discharge end of the primary crusher and the said transport belt is arranged belt, the lower end of the coal transport hopper and the upper end of the pneumatic classifier and it has an outlet for fine grained coal water-oil emulsion blend at a level slightly higher than the lower end or at any location as desired. f. the pneumatic classifier has a discharge spout at its lower end for the discharge of the coarse grain water-oil blend on to a transport conveyor connecting the secondary transport hopper, g. the secondary transport hopper is provided with a feeder for water-oil emulsion from the emulsion tank, h. the secondary crusher is arranged preferably vertically below the secondary transport hopper and is identical in construction and function to the primary crusher and converts the coarse grain water-oil blend discharged by the pneumatic classifier into a finer grains and It has a discharge spout at its lower end and operatively connected by transport means to the top of the pneumatic classifier for recycling the product of the secondary crusher to the pneumatic classifier. Additional Details of the Invention with Reference to the Accompanying Drawing: The novel processing step is explained with reference to the accompanying drawing, wherein: Figure 1 illustrates, schematically, the various units of the system and the various steps of the process. Thus, from the accompanying drawings, it will be seen that the system for processing coal comprises: 1-Oil storage tank; 2-Water tank; 3-Pump; 4-Pump with flame proof motor; 5-Emuision tank; 6-Primary crusher; 7-Secondary crusher; 8-Chutes; 9-Conveyor belt from blending bunker; 10-Pneumatic classifier; 11-Final coal charge. These units are interconnected as shown in the drawings. In operation, the processing steps are as follows: Oil and water are drawn respectively from the underground oil tank (1) and the water reservoir (2) through pumps (3 & 4) to emulsion tank (5). A pump with flame proof motor (4) keeps oil and water in emulsion form. Emulsion is, sprayed on coal fed from the conveyor (0) inside the transfer chutes (8), which feed the primary crusher (6). The discharge from the primary crusher is fed into a pneumatic classifier (10). The coarse grains from this unit (10) is then fed through another transfer chute (8) into the secondary crusher (7). The discharge from this crusher (7) is also fed into the classifier (10). As a result, water-oil emulsion is well mixed with fine coals and become free flowing. It helps efficient separation of fines from coarse coal particles in air fluidized pneumatic classifier (10). The product is taken out as stream (11). The addition of oil can be added on coal blend on conveyor belt effectively with due care to avoid direct exposure to empty conveyor belt surface, We have found surprisingly that the bulk density of moist fine coal increases by 1 to 3% with addition of water-oil emulsion, based on usage level of the emulsion, oil-water ratio, original moisture content and fineness of the coal. In an actual study, the bulk density of coal charge (3 mm content 82%, and moisture 8.4%) increased from 799 kg/m3 to 819 kg/m3 with addition of 0.03% oil and 0.18% water in form of emulsion. We have studied the use of different oils, which can suit our requirements. We have found after several exploratory studies that oil may be any waste oil having low viscosity, like waste machine oil, waste transformer oil or fresh light naphtha, diesel oil, kerosene oil etc. Lighter oils are more effective than the heavier or viscous oils. This new process/technique of addition of oil in the form of water-oil emulsion solved flow problem and increases bulk density of coal fines with high moisture. In this process, 0.01-0.05% of oil with 2-7 times water is sufficient to solve these problems with very little additional fire hazard. Further Exploratory Details of Performance Characteristic: Table 1 shows the performance of pneumatic classifier used in a study without and with emulsion addition during monsoon period of 1999 and 2000. Finer fractions ( significantly from the coarse fraction with use of water-oil emulsion. Table 2 shows comparative performance of coke oven during two consecutive monsoon period when coal Wend become highly moist (>8%). During 2Q00 monsoon, 0.02-0.05% of diesel oil with 3 to 7 times water was used in the coal charge. During 1999, no emulsion was added. There was no chute jamming, no stopping of crusher and bypassing of pneumatic separator. Production of prepared coal charge was normal and there was no prepared coal shortage to affect oven charging. Table 1: Comparative performance of pneumatic classifier with and without water-oil emulsion addition in coal charge (Fine contents in coarse fraction). Size content Year 1999 (No water-oil emulsion added) Year 2000 (Water-oil emulsion added) mm July Aug. Sept. Average July Aug. Sept. Average % % % % % % % % -3.2 71.9 72.2 80.6 74.9 63.7 44.7 43.1 50.5 -1.0 51.3 50.0 59.3 53.5 41.2 25.3 24.0 30.2 -0.5 37.4 36.8 44.1 39.4 27.4 18.5 17.1 21.0 -0.25 23.2 23.2 26.9 24.5 15.8 12.7 11,8 13.4 Use of water-oil emulsion in coal charge at laboratory study indicated improvement in bulk density shown in Table-Ill. Addition of more than 0.05% oil with 8 times water does not improve bulk density significantly. Table 2: Comparative performance of coke ovens in the monsoon periods. Parameters Year 1999 (No water-oil emulsion added) Year 2000 (Water-oil emulsion added) July Aug. Sept. July Aug. Sept. Crushing index, -3.2 mm, % 82.5 83.9 85.7 85.8 86.7 86.0 Oven pushed per day 254 258 249 269 271 268 By-passing of classifier due jamming problem. 18 shifts in one and 10 shifts streams stream in both No by-passing of pneumatic classifier Oven pushing drop due to shortage of prepared coal charge per month. 100 100 146 Nil Nil Nil Table 3: improvement In bulk density due to addition of oil-water emulsion. % or oil used Buik aensity, Kg/m Diesel oil Diesel oil Waste machine oil % Moisture 8.2 9.2 9.2 Crushing index, -3.2 mm, % 82.1 81.3 81.3 Oil: Water ratio 1:5 1:6 1:5 0.00 786.2 791.5 791.5 0.02 803.2 812.2 0.03 812.2 815.7 822.6 0.05 815.7 - - 0.10 820.8 819.1 829.5 The new process has following advantages compared to use of oil only. • It reduces fire hazard significantly. When water-oil emulsion is used, only extra safety measure is needed up to preparation of emulsion, compared to total coal stream after addition of oil only. • Consumption of oil reduced by 1/10th as only 0.01-0.05% is used in this system against 0.1 to 0.5% when only oil is used. • It prevents chute jamming and improves performance of separation system such as pneumatic classifier even up to 10% moisture content. • The process improves bulk density of coal charge and hence, coke oven throughput by 1-3.5%. We Claim: 1. A system for improved coal blend preparation with addition of a water-oil emulsion to improve flowability and bulk density of coal blend by reducing friction in between the coal particles, for feeding to coke oven comprising: an oil storage tank (1) operatively connected to a pump with flame proof motor for supply of oil to a emulsion tank; a water storage tank (2) operatively connected to a pump for supply of water to said emulsion tank; pump with flame proof motor (4) means for supplying emulsion from the emulsion tank to coal transfer hopper (8) at desired rate; said coal transfer hopper is fed through chutes (8) having emulsion sprayers in the top region with coal feeding conveyor (9) in the vicinity thereof; said coal transfer hopper having a discharge spout at its lower end adopted to discharge the emulsion blended coal to a primary crusher(6) for effectively crushing the coal-emulsion blend to finer coal and a transport unit provided below the discharge end of the primary crusher (6); a pneumatic classifier (10) provided at the discharge end of the said transport unit for receiving the coal-emulsion blend from the primary crusher (6); said pneumatic classified 10) having a coarse grain discharge means and fine grains product discharge means; the pneumatic classified 10) being operatively connected through a second blend transport hopper to a secondary crusher(7) for crushing tiie coarse coal blended with water-oil emulsion leaving the classifier into a finer grains; said secondary crusher(7) having a fine grain discharge means and transport means for recycling the finer discharge from the secondary crusher(7) to the said pneumatic classified 10), wherefrom the final coal-emulsion blend charge is taken out as stream through the outlet(ll). 2. A system as claimed in claim 1, wherein, said means for supplying water and oil from their respective sources/storages are pump means. 3. A system as claimed in claims 1 and 2, wherein, the emulsion tank is provided with a pump driven by flame proof motor for feeding the emulsion to the sprayers in the coal transfer hopper. 4. A system as claimed in claims 1 to 3, wherein, the coal feeding conveyor is a conveyor belt arranged to transfer coal from the blending bunker. 5. A system as claimed in claim 4, wherein, the conveyor is arranged preferably at a level higher than the emulsion sprayer. 6. A system as claimed in claims 1 to 5, wherein, the said coal transfer hopper has a discharge spout at its lower end for the discharge of coal water-oil emulsion mixture. 7. A system as claimed in claim, 6, wherein, the coal transfer hopper has preferably a cylindrical cross-section at the top and a conical cross section to the bottom and wherein the water-oil emulsion sprayers and the coal conveyors are disposed at the upper cylindrical section. 8. A system as claimed in claims 1 to 7, wherein, the coal transfer hopper is positioned at the highest level in the system to allow gravity assisted flow of the coal water oil emulsion mixture into the primary crusher. 9. A system as claimed in claim 8, wherein, the primary crusher is positioned vertically provided below the coal transfer hopper. 10. A system as claimed in claim 9, wherein, the discharge spout of the primary crusher is at its lower end and positioned above a transport belt. 11. A system as claimed in claim 10, wherein, the pneumatic classifiers preferably mounted in a position so that its top end is located above the discharge end of the primary crusher and separate conveyor belts are arranged to operatively transport the crushed coal output of the primary and secondary crusher from the respective discharge spout at lower end of each said crusher to the upper end of the pneumatic classifier, for recycling the products obtained from the crushers to the pneumatic classifier. 12. A system as claimed in claim 11, wherein, said pneumatic classifier has an outlet for fine grained coal water-oil emulsion blend at a level slightly higher than the lower end or at any location as desired. 13. A system as claimed in claim 12, wherein, the pneumatic classifier has a discharge spout at its lower end for the discharge of the coarse grain water-oil blend on to a transport conveyor connecting the secondary transport hopper. 14. A system as claimed in claim 13, wherein, the secondary transport hopper is provided with a feeder for water-oil emulsion from the emulsion tank. 15. A system as claimed in claim 14, wherein, the secondary crusher is arranged preferably vertically below the secondary transport hopper and is identical in construction and function to the primary crusher and converts the coarse grain water-oil blend discharged by the pneumatic classifier into finer grains. 16. A system as claimed in claim 15, wherein, the secondary crusher has a discharge spout at its lower end and operatively connected by transport means to the top of the pneumatic classifier for recycling the product of the secondary crusher to the pneumatic classifier. 17. A method for preparing coal, blended with a water-oil emulsion using the system as claimed in anyone of claims 1 to 16 comprising providing an oil storage tank and a water storage tank, an emulsion tank for preparing water-oil emulsion, supplying water and oil at desired rate, from their respective storage tanks to the emulsion tank, subjecting to emulsification, preferably to obtain 0.03 wt.% oil and 0.18 wt.% water in form of emulsion in coal blend, supplying emulsion from the emulsion tank to coal transfer hopper, having emulsion sprayers in the top region with coal feeding conveyor in the vicinity thereof, discharging the emulsion blended coal from the said hopper to a primary crusher for effectively crushing the coal water-oil emulsion blend to finer coal, transporting the crusher blend from the primary crusher to a pneumatic classifier, discharging fines from the pneumatic classifier as product and feeding the coarse grain from the pneumatic classifier through a second blend transport hopper to a second crusher for crushing the coarse coal blend water-oil emulsion leaving the classifier into a finer grains, and for recycling the fine discharge from the secondary crusher to the said pneumatic classifier such that the favored improved bulk density in final blend is obtained at final outlet from the pneumatic classifier. 18. A method as claimed in claim 17, wherein, the emulsion tank is provided with a pump for feeding the emulsion to the sprayers in the coal transfer hopper. 19. A method as claimed in claim 18, wherein, the said coal transfer hopper has a discharge spout at its lower end for the discharge of coal water-oil emulsion mixture. 20. A method as claimed in claim 19, wherein, the coal transfer hopper has preferably a cylindrical cross-section at the top and a conical cross section at the bottom and wherein the water-oil emulsion sprayers and the coal conveyors are disposed at the upper cylindrical section. 21. A method as claimed in claims 17 to 20, wherein, the coal transfer hopper is positioned at the highest level in the system so as to allow gravity flow of the coal water oil emulsion mixture into the primary crusher. 22. A method as claimed in claim 21, wherein, the primary crusher is positioned vertically provided below the coa! transfer hopper. 23. A method as claimed in daim 22, wherein, the discharge spout of the primary crusher is at its lower end and positioned above a transport belt. 24. A method as claimed in claim 23, wherein, the pneumatic classifiers preferably arranged such that its top end is above the discharge end of the primary crusher and the said transport belt is an arranged belt, connecting the lower end of the coal transport hopper and the upper end of the pneumatic classifier. 25. A method as claimed in claim 24, wherein, said pneumatic classifier has an outlet for fine grained coal water-oil emulsion blend at a level slightly higher than the lower end or at any location as desired. 26. A method as claimed in claim 25, wherein, the pneumatic classifier has a discharge spout at its lower end for the discharge of the coarse grain water-oil blend on to a transport conveyor connecting the secondary transport hopper. 27. A method as claimed in claim 26, wherein, the secondary transport hopper is provided with a feeder for water-oil emulsion from the emulsion tank. 28. A method as daimed in daim 27, wherein, the secondary crusher is arranged preferably vertically below the secondary transport hopper and is identical in construction and function to the primary crusher and converts the coarse grain water-oil blend discharged by the pneumatic classifier into a finer grains. 29. A method as daimed in claim 28, wherein, the secondary crusher has a discharge spout at its lower end and operatively connected by transport means to the top of the pneumatic dassifier for recycling the product of the secondary crusher to the pneumatic classifier. 30. A system for preparing coal blend with water-oil emulsion and a method to carry out such system, substantially as herein described with reference to the accompanying drawings. Dated this 30th day of January, 2002. A system for preparing coal blend with a water-oil emulsion comprising oil tank (1) and water tank (2) being pumped to an emulsion tank(5) for preparing water-oil emulsion, supplying emulsion from the emulsion tank to coal transfer hopper(8) having emulsion sprayers in the top region having a coal feeding conveyor(9) in the vicinity thereof, to obtain 0.03 wt.% oil and 0.18 wt.% water in form of emulsion in coal blend preferably following a method using said system, discharging the emulsion blended coal from the said hopper to a primary crusher(6) for effectively crushing the coal blend to finer coal, transporting the crushed blend to a pneumatic classifier(10), discharging fines from the pneumatic classifier as product and feeding the coarse grain from the pneumatic classifier to a second crusher(7) for crushing the coarse coat blend water-oil emulsion leaving the classifier into a finer grains, and for recycling the fine discharge therein.

Full Text

Introduction to the Field of Invention:
Improvements in or relating to the method of processing blend coal suited for coke oven use.
This invention relates to improvements in or relating to the method of processing blend coal
suited for coke oven use and a system therefore.
Prior Art and Drawbacks:
It is well known to process coal, taken from the bunker, before feeding to the coke oven to
crush to 0-3 mm size without producing more fines (-0.25 mm).
In general, fine coals with > 8% moisture content become sticky mass and do not allow free
flow in transfer chutes. It affects size separation systems. High moisture content also reduces
bulk density of fine coals. As a result, productivity of coal preparation plant and quality of coal
prepared are affected.
The problem has been solved to a certain extent by the addition of oil to the extent of 0.1 to
0.5 wt.% to the coal. This has to a limited extent solved or improved the How problem and to
improved bulk density of moist fine coals.
But there is a drawback due to high combustibility of oil used with combustible coal and extra
fire safety measure is needed till oiled coal is consumed.
Besides, oil is a costly material. For this reason only oil addition system on fine coal is rarely
used in the industry.
Moreover, the amount of oil used adds up to the cost and affects the economy of the process.
Objects of the Invention;
It is therefore an object of this invention to propose an improved method for the processing of
coal economically before feeding to the coke oven.
It is another object to propose a method, which will enable fluidization of fine coal preferably
from the coarse fraction in the pneumatic classifier even with moisture more than 8 wt.%.
It is a further object of this invention to propose such a method, which will ensure processed coal having
substantially lower fine fractions (-0.25 mm) coal suited for coke oven.
Another object of the invention is to propose such a processing of coal, which will consume minimum oil
compared to the amount of oil consumed in the known art.
Yet another object is to propose such a process, which will be free of blockage of processing units and
ensure free flow of coal at different units during processing.
A still further object of this invention is to propose such a process, which can use any waste oil (hydro
carbon) having low viscosity and will thus improve the economy of the process.
A further object of this invention is to propose such a process, which will increase the bulk density of
processed coal enabling increased oven throughput.
Yet another object of this invention is to propose a novel system for processing coal before making it
suitable for coke oven operation.
These and other objects of the invention will be clear from the following paragraphs.
Brief Statement of the Invention:
According to one aspect of the present invention is directed to a system for improved coal blend
preparation with addition of a water-oil emulsion to improve flowability and bulk density of coal blend by
reducing friction in between the coal particles, for feeding to coke oven comprising:
an oil storage tank operatively connected to a pump for supply of oil to a emulsion tank;
a water storage tank operatively connected to a pump for supply of water to said emulsion tank;
pump with flame proof motor means for supplying emulsion from the emulsion tank to coal transfer
hopper at desired rate;
said coal transfer hopper is fed through chutes having emulsion sprayers in the top region with coal
feeding conveyor in the vicinity thereof;
said coal transfer hopper having a discharge spout at its lower end adopted to discharge the emulsion
blended coal to a primary crusher for effectively crushing the coal-emulsion blend to finer coal and a
transport unit provided below the discharge end of the primary crusher;
a pneumatic classifier provided at the discharge end of the said transport unit for receiving the coal-
emulsion blend from the primary crusher ;
said pneumatic classifier having a coarse grain discharge means and fine grains product discharge means;
the pneumatic classifier being operatively connected through a second blend transport hopper to a
secondary crusher for crushing the coarse coal blended with water-oil emulsion leaving the classifier into a
finer grains;
said secondary crusher having a fine grain discharge means and transport means for recycling the finer
discharge from the secondary crusher to the said pneumatic classifier, wherefrom the final coal-emulsion
blend charge is taken out as stream through the outlet.
The means for supplying water and oil from their respective sources are pump means and the
emulsion tank is provided with a pump for feeding the emulsion to the sprayers in the coal
transfer hopper.
The coal feeding conveyor is a conveyor belt arranged to transfer coal from the blending
bunker and the conveyor is arranged preferably at a level higher than the emulsion sprayer.
A coal transfer hopper has a discharge spout at its lower end for the discharge of coal water-
oil emulsion mixture, has preferably a cylindrical cross-section at the top and a conical cross
section to the bottom and wherein the water-oil emulsion sprayers and the coal conveyors are
disposed at the upper cylindrical section.
Preferably the coal transfer hopper is positioned at the highest level in the system so as to
allow gravity flow of the coal water oil emulsion mixture into the primary crusher and the
primary crusher is positioned vertically provided below the coal transfer hopper.
The discharge spout of the primary crusher is at its lower end and positioned above a
transport belt.
The pneumatic classifier of the present system preferably mounted in a position so that its top
end is located above the discharge end of the primary crusher and separate conveyor belts are
arranged to operatively transport the crushed coal output of the primary and secondary
crusher from the respective discharge spout at lower end of each said crusher to the upper
end of the pneumatic classifier, for recycling the products obtained from the crushers to the
pneumatic classifier. Said pneumatic classifier has an outlet for fine grained coal btended with
oil-water emulsion at preferred elevation from the bottom end of the classifier and a discharge
spout at the lower end for the discharge of coarse grain water-oil coal blend on to a transport
conveyor transporting the same to the secondary transport hopper.
The secondary transport hopper is provided with a feeder for water-oil emulsion from the
emulsion tank and is arranged preferably vertically below the secondary transport hopper and
is identical in construction and function to the primary crusher and converts the coarse grain
water-oil blend discharged by the pneumatic classifier into a finer grains.
The secondary crusher has a discharge spout at its lower end and operatively connected by
transport means to the top of the pneumatic classifier for recycling the product of the
secondary crusher to the pneumatic classifier.
According to another aspect of the present invention directed to a method for preparing
coal, blended with a water-oil emulsion using the system of the invention comprising
providing an oil storage tank and a water storage tank, an emulsion tank for preparing
water-oil emulsion, supplying water and oil at desired rate, from their respective storage
tanks to the emulsion tank, subjecting to emulsification, preferably to obtain 0.03 wt.% oil
and 0.18 wt.% water in form of emulsion in coal blend, supplying emulsion from the
emulsion tank to coal transfer hopper, having emulsion sprayers in the top region with
coal feeding conveyor in the vicinity thereof, discharging the emulsion blended coal from
the said hopper to a primary crusher for effectively crushing the coal water-oil emulsion
blend to finer coal, transporting the crusher blend from the primary crusher to a
pneumatic classifier, discharging fines from the pneumatic classifier as product and
feeding the coarse grain blend from the pneumatic classifier through a second transport
hopper to a second crusher for crushing the coarse coal blend water-oil emulsion leaving
the classifier into a finer grains, and for recycling the fine discharge from the secondary
crusher to the said pneumatic classifier such that the favored improved bulk density in
final blend is obtained at final outlet from the pneumatic classifier.
In this method the following features are preferred for successfully carrying out the
method:
a. the emulsion tank is provided with a pump for feeding the emulsion to the
sprayers in the coal transfer hopper,
b. coal transfer hopper has a discharge spout at its lower end for the discharge of
coal water-oil emulsion mixture and the coal transfer hopper has preferably a
cylindrical cross-section at the top and a conical cross section at the bottom and
wherein the water-oil emulsion sprayers and the coal conveyors are disposed at
the upper cylindrical section.
c. the coal transfer hopper is positioned at the highest level in the system so as to
allow gravity flow of the coal water oil emulsion mixture into the primary crusher,
d. the primary crusher is positioned vertically provided below the coal transfer
hopper and the discharge spout of the primary crusher is at its lower end and
positioned above a transport belt,
e. the pneumatic classifier is preferably mounted such that its top end is above the
discharge end of the primary crusher and the said transport belt is arranged belt,
the lower end of the coal transport hopper and the upper end of the pneumatic
classifier and it has an outlet for fine grained coal water-oil emulsion blend at a
level slightly higher than the lower end or at any location as desired.
f. the pneumatic classifier has a discharge spout at its lower end for the discharge of the coarse
grain water-oil blend on to a transport conveyor connecting the secondary transport hopper,
g. the secondary transport hopper is provided with a feeder for water-oil emulsion from the
emulsion tank,
h. the secondary crusher is arranged preferably vertically below the secondary transport hopper
and is identical in construction and function to the primary crusher and converts the coarse
grain water-oil blend discharged by the pneumatic classifier into a finer grains and It has a
discharge spout at its lower end and operatively connected by transport means to the top of
the pneumatic classifier for recycling the product of the secondary crusher to the pneumatic
classifier.
Additional Details of the Invention with Reference to the Accompanying Drawing:
The novel processing step is explained with reference to the accompanying drawing, wherein:
Figure 1 illustrates, schematically, the various units of the system and the various steps of the
process.
Thus, from the accompanying drawings, it will be seen that the system for processing coal
comprises:
1-Oil storage tank;
2-Water tank;
3-Pump;
4-Pump with flame proof motor;
5-Emuision tank;
6-Primary crusher;
7-Secondary crusher;
8-Chutes;
9-Conveyor belt from blending bunker;
10-Pneumatic classifier;
11-Final coal charge.
These units are interconnected as shown in the drawings.
In operation, the processing steps are as follows:
Oil and water are drawn respectively from the underground oil tank (1) and the water reservoir (2)
through pumps (3 & 4) to emulsion tank (5). A pump with flame proof motor (4) keeps oil and
water in emulsion form. Emulsion is, sprayed on coal fed from the conveyor (0) inside the transfer
chutes (8), which feed the primary crusher (6). The discharge from the primary crusher is fed into
a pneumatic classifier (10).
The coarse grains from this unit (10) is then fed through another transfer chute (8) into the
secondary crusher (7). The discharge from this crusher (7) is also fed into the classifier (10).
As a result, water-oil emulsion is well mixed with fine coals and become free flowing. It helps
efficient separation of fines from coarse coal particles in air fluidized pneumatic classifier (10).
The product is taken out as stream (11).
The addition of oil can be added on coal blend on conveyor belt effectively with due care to avoid
direct exposure to empty conveyor belt surface,
We have found surprisingly that the bulk density of moist fine coal increases by 1 to 3% with
addition of water-oil emulsion, based on usage level of the emulsion, oil-water ratio, original
moisture content and fineness of the coal.
In an actual study, the bulk density of coal charge (3 mm content 82%, and moisture 8.4%)
increased from 799 kg/m3 to 819 kg/m3 with addition of 0.03% oil and 0.18% water in form of
emulsion.
We have studied the use of different oils, which can suit our requirements. We have found after
several exploratory studies that oil may be any waste oil having low viscosity, like waste machine
oil, waste transformer oil or fresh light naphtha, diesel oil, kerosene oil etc. Lighter oils are more
effective than the heavier or viscous oils.
This new process/technique of addition of oil in the form of water-oil emulsion solved flow
problem and increases bulk density of coal fines with high moisture. In this process, 0.01-0.05%
of oil with 2-7 times water is sufficient to solve these problems with very little additional fire
hazard.
Further Exploratory Details of Performance Characteristic:
Table 1 shows the performance of pneumatic classifier used in a study without and with emulsion
addition during monsoon period of 1999 and 2000. Finer fractions ( significantly from the coarse fraction with use of water-oil emulsion.
Table 2 shows comparative performance of coke oven during two consecutive monsoon period
when coal Wend become highly moist (>8%). During 2Q00 monsoon, 0.02-0.05% of diesel oil with
3 to 7 times water was used in the coal charge. During 1999, no emulsion was added. There was
no chute jamming, no stopping of crusher and bypassing of pneumatic separator. Production of
prepared coal charge was normal and there was no prepared coal shortage to affect oven
charging.
Table 1: Comparative performance of pneumatic classifier with and without
water-oil emulsion addition in coal charge (Fine contents in coarse fraction).
Size content Year 1999 (No water-oil emulsion added) Year 2000 (Water-oil emulsion added)
mm July Aug. Sept. Average July Aug. Sept. Average
% % % % % % % %
-3.2 71.9 72.2 80.6 74.9 63.7 44.7 43.1 50.5
-1.0 51.3 50.0 59.3 53.5 41.2 25.3 24.0 30.2
-0.5 37.4 36.8 44.1 39.4 27.4 18.5 17.1 21.0
-0.25 23.2 23.2 26.9 24.5 15.8 12.7 11,8 13.4
Use of water-oil emulsion in coal charge at laboratory study indicated improvement in bulk density
shown in Table-Ill. Addition of more than 0.05% oil with 8 times water does not improve bulk
density significantly.
Table 2: Comparative performance of coke ovens in the monsoon periods.
Parameters Year 1999 (No water-oil emulsion added) Year 2000 (Water-oil emulsion added)
July Aug. Sept. July Aug. Sept.
Crushing index, -3.2 mm, % 82.5 83.9 85.7 85.8 86.7 86.0
Oven pushed per day 254 258 249 269 271 268
By-passing of classifier due jamming problem. 18 shifts in one and 10 shifts streams stream in both No by-passing of pneumatic classifier
Oven pushing drop due to shortage of prepared coal charge per month. 100 100 146 Nil Nil Nil
Table 3: improvement In bulk density due to addition of oil-water emulsion.
% or oil used Buik aensity, Kg/m
Diesel oil Diesel oil Waste machine oil
% Moisture 8.2 9.2 9.2
Crushing index, -3.2 mm, % 82.1 81.3 81.3
Oil: Water ratio 1:5 1:6 1:5
0.00 786.2 791.5 791.5
0.02 803.2 812.2
0.03 812.2 815.7 822.6
0.05 815.7 - -
0.10 820.8 819.1 829.5
The new process has following advantages compared to use of oil only.
• It reduces fire hazard significantly. When water-oil emulsion is used, only extra safety
measure is needed up to preparation of emulsion, compared to total coal stream after
addition of oil only.
• Consumption of oil reduced by 1/10th as only 0.01-0.05% is used in this system against
0.1 to 0.5% when only oil is used.
• It prevents chute jamming and improves performance of separation system such as
pneumatic classifier even up to 10% moisture content.
• The process improves bulk density of coal charge and hence, coke oven throughput by
1-3.5%.
We Claim:
1. A system for improved coal blend preparation with addition of a water-oil emulsion
to improve flowability and bulk density of coal blend by reducing friction in
between the coal particles, for feeding to coke oven comprising:
an oil storage tank (1) operatively connected to a pump with flame proof motor
for supply of oil to a emulsion tank;
a water storage tank (2) operatively connected to a pump for supply of water to
said emulsion tank;
pump with flame proof motor (4) means for supplying emulsion from the
emulsion tank to coal transfer hopper (8) at desired rate;
said coal transfer hopper is fed through chutes (8) having emulsion sprayers in
the top region with coal feeding conveyor (9) in the vicinity thereof;
said coal transfer hopper having a discharge spout at its lower end adopted to
discharge the emulsion blended coal to a primary crusher(6) for effectively
crushing the coal-emulsion blend to finer coal and a transport unit provided below
the discharge end of the primary crusher (6);
a pneumatic classifier (10) provided at the discharge end of the said transport
unit for receiving the coal-emulsion blend from the primary crusher (6);
said pneumatic classified 10) having a coarse grain discharge means and fine
grains product discharge means;
the pneumatic classified 10) being operatively connected through a
second blend transport hopper to a secondary crusher(7) for crushing
tiie coarse coal blended with water-oil emulsion leaving the classifier into
a finer grains;
said secondary crusher(7) having a fine grain discharge means and transport
means for recycling the finer discharge from the secondary crusher(7) to the said
pneumatic classified 10), wherefrom the final coal-emulsion blend charge is taken
out as stream through the outlet(ll).
2. A system as claimed in claim 1, wherein, said means for supplying water and oil
from their respective sources/storages are pump means.
3. A system as claimed in claims 1 and 2, wherein, the emulsion tank is provided
with a pump driven by flame proof motor for feeding the emulsion to the sprayers
in the coal transfer hopper.
4. A system as claimed in claims 1 to 3, wherein, the coal feeding conveyor is a
conveyor belt arranged to transfer coal from the blending bunker.
5. A system as claimed in claim 4, wherein, the conveyor is arranged preferably at a
level higher than the emulsion sprayer.
6. A system as claimed in claims 1 to 5, wherein, the said coal transfer
hopper has a discharge spout at its lower end for the discharge of coal
water-oil emulsion mixture.
7. A system as claimed in claim, 6, wherein, the coal transfer hopper has
preferably a cylindrical cross-section at the top and a conical cross section
to the bottom and wherein the water-oil emulsion sprayers and the coal
conveyors are disposed at the upper cylindrical section.
8. A system as claimed in claims 1 to 7, wherein, the coal transfer hopper is
positioned at the highest level in the system to allow gravity assisted flow
of the coal water oil emulsion mixture into the primary crusher.
9. A system as claimed in claim 8, wherein, the primary crusher is positioned
vertically provided below the coal transfer hopper.
10. A system as claimed in claim 9, wherein, the discharge spout of the
primary crusher is at its lower end and positioned above a transport belt.
11. A system as claimed in claim 10, wherein, the pneumatic classifiers
preferably mounted in a position so that its top end is located above the
discharge end of the primary crusher and separate conveyor belts are
arranged to operatively transport the crushed coal output of the primary
and secondary crusher from the respective discharge spout at lower end
of each said crusher to the upper end of the pneumatic classifier, for
recycling the products obtained from the crushers to the pneumatic
classifier.
12. A system as claimed in claim 11, wherein, said pneumatic classifier has an
outlet for fine grained coal water-oil emulsion blend at a level slightly
higher than the lower end or at any location as desired.
13. A system as claimed in claim 12, wherein, the pneumatic classifier has a
discharge spout at its lower end for the discharge of the coarse grain
water-oil blend on to a transport conveyor connecting the secondary
transport hopper.
14. A system as claimed in claim 13, wherein, the secondary transport hopper
is provided with a feeder for water-oil emulsion from the emulsion tank.
15. A system as claimed in claim 14, wherein, the secondary crusher is
arranged preferably vertically below the secondary transport hopper and is
identical in construction and function to the primary crusher and converts
the coarse grain water-oil blend discharged by the pneumatic classifier into finer
grains.
16. A system as claimed in claim 15, wherein, the secondary crusher has a discharge
spout at its lower end and operatively connected by transport means to the top of
the pneumatic classifier for recycling the product of the secondary crusher to the
pneumatic classifier.
17. A method for preparing coal, blended with a water-oil emulsion using the system
as claimed in anyone of claims 1 to 16 comprising providing an oil storage tank
and a water storage tank, an emulsion tank for preparing water-oil emulsion,
supplying water and oil at desired rate, from their respective storage tanks to the
emulsion tank, subjecting to emulsification, preferably to obtain 0.03 wt.% oil and
0.18 wt.% water in form of emulsion in coal blend, supplying emulsion from the
emulsion tank to coal transfer hopper, having emulsion sprayers in the top region
with coal feeding conveyor in the vicinity thereof, discharging the emulsion
blended coal from the said hopper to a primary crusher for effectively crushing the
coal water-oil emulsion blend to finer coal, transporting the crusher blend from the
primary crusher to a pneumatic classifier, discharging fines from the pneumatic
classifier as product and feeding the
coarse grain from the pneumatic classifier through a second blend transport
hopper to a second crusher for crushing the coarse coal blend water-oil emulsion
leaving the classifier into a finer grains, and for recycling the fine discharge from
the secondary crusher to the said pneumatic classifier such that the favored
improved bulk density in final blend is obtained at final outlet from the pneumatic
classifier.
18. A method as claimed in claim 17, wherein, the emulsion tank is provided with a
pump for feeding the emulsion to the sprayers in the coal transfer hopper.
19. A method as claimed in claim 18, wherein, the said coal transfer hopper has a
discharge spout at its lower end for the discharge of coal water-oil emulsion
mixture.
20. A method as claimed in claim 19, wherein, the coal transfer hopper has preferably
a cylindrical cross-section at the top and a conical cross section at the bottom
and wherein the water-oil emulsion sprayers and the coal conveyors are disposed
at the upper cylindrical section.
21. A method as claimed in claims 17 to 20, wherein, the coal transfer hopper is
positioned at the highest level in the system so as to allow gravity flow of the coal
water oil emulsion mixture into the primary crusher.
22. A method as claimed in claim 21, wherein, the primary crusher is positioned
vertically provided below the coa! transfer hopper.
23. A method as claimed in daim 22, wherein, the discharge spout of the primary
crusher is at its lower end and positioned above a transport belt.
24. A method as claimed in claim 23, wherein, the pneumatic classifiers preferably
arranged such that its top end is above the discharge end of the primary crusher
and the said transport belt is an arranged belt, connecting the lower end of the
coal transport hopper and the upper end of the pneumatic classifier.
25. A method as claimed in claim 24, wherein, said pneumatic classifier has an outlet
for fine grained coal water-oil emulsion blend at a level slightly higher than the
lower end or at any location as desired.
26. A method as claimed in claim 25, wherein, the pneumatic classifier has a discharge
spout at its lower end for the discharge of the coarse grain water-oil blend on to a
transport conveyor connecting the secondary transport hopper.
27. A method as claimed in claim 26, wherein, the secondary transport hopper is
provided with a feeder for water-oil emulsion from the emulsion tank.
28. A method as daimed in daim 27, wherein, the secondary crusher is arranged
preferably vertically below the secondary transport hopper and is identical in
construction and function to the primary crusher and converts the coarse grain
water-oil blend discharged by the pneumatic classifier into a finer grains.
29. A method as daimed in claim 28, wherein, the secondary crusher has a discharge
spout at its lower end and operatively connected by transport means to the top of
the pneumatic dassifier for recycling the product of the secondary crusher to the
pneumatic classifier.
30. A system for preparing coal blend with water-oil emulsion and a method to carry
out such system, substantially as herein described with reference to the
accompanying drawings.
Dated this 30th day of January, 2002.
A system for preparing coal blend with a water-oil emulsion comprising oil tank (1)
and water tank (2) being pumped to an emulsion tank(5) for preparing water-oil
emulsion, supplying emulsion from the emulsion tank to coal transfer hopper(8)
having emulsion sprayers in the top region having a coal feeding conveyor(9) in the
vicinity thereof, to obtain 0.03 wt.% oil and 0.18 wt.% water in form of emulsion in
coal blend preferably following a method using said system, discharging the emulsion
blended coal from the said hopper to a primary crusher(6) for effectively crushing
the coal blend to finer coal, transporting the crushed blend to a pneumatic
classifier(10), discharging fines from the pneumatic classifier as product and feeding
the coarse grain from the pneumatic classifier to a second crusher(7) for crushing
the coarse coat blend water-oil emulsion leaving the classifier into a finer grains, and
for recycling the fine discharge therein.

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Patent Number

222920

Indian Patent Application Number

58/CAL/2002

PG Journal Number

35/2008

Publication Date

29-Aug-2008

Grant Date

27-Aug-2008

Date of Filing

30-Jan-2002

Name of Patentee

STEEL AUTHORITY OF INDIA LIMITED

Applicant Address

RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, DORANDA, RANCHI-834002

Inventors:

#	Inventor's Name	Inventor's Address
1	BANDOPADHYAY SHYAM SUNDAR	RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, STEEL AUTHORITY OF INDIA LTD., DORANDA, RANCHI-834002
2	GHOSH NIRMAL KUMAR	RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, STEEL AUTHORITY OF INDIA LTD., DORANDA, RANCHI-834002
3	LAKSHMANAN PARTHASARTHY	RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, STEEL AUTHORITY OF INDIA LTD., DORANDA, RANCHI-834002
4	ROY NILOTPAL	DURGAPUR STEEL PLANT, STEEL AUTHORITY OF INDIA LIMITED, DURGAPUR
5	KAR SATYAJIT	DURGAPUR STEEL PLANT, STEEL AUTHORITY OF INDIA LIMITED, DURGAPUR
6	SENGUPTA MALAY SHANKAR	RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, STEEL AUTHORITY OF INDIA LTD., DORANDA, RANCHI-834002

PCT International Classification Number

C01B 53/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA