CLIAMS:We Claim:
1. A process for energy efficient production of stable coal cake from coals of different granulometry and moisture level comprising,

selectively involving coal/ coal blend samples of crushing level of even less than 90% content of -3.2 mm and moisture content of even < 10 %; and

applying controlled compaction force based on the granulometry and moisture level of the coal/ coal blend samples.

2. A process as claimed in claim 1 wherein said step of applying controlled compaction force comprises applying pressure on coal blend charge in a mould for each layer in relation to coal cake density to be achieved by controlled application of pressure through a hydraulic press based on said granulometry and total moisture content to achieve the desired coal cake density.

3. A process as claimed in anyone of claims 1 or 2, wherein said controlled compaction force comprises application of pressure on coal blend charge in mould in relation to coal cake density to be achieved based on predetermined relationship between pressure and coal cake obtained of: y= 0.064ln(x)+0.832, where x is the applied pressure in kg/cm2 and y is the coal cake density in g/cm3.

4. A process as claimed in anyone of claims 1 to 3, wherein stable coal cake is produced even on use of crushing level of even 85 % content of 3.2 mm and total moisture content of even 8% at compaction force of 98 tons.

5. A process as claimed in anyone of claims 1 to 4, wherein process of making coal cake is divided preferably in four installments/layers for increasing stability of coal cake.

6. A process as claimed in anyone of claims 1 to 5, wherein carbonization of said coal cake with required density corresponding to a compaction force of 98 ton, confirms suitability of coke obtained thereof by observed values of M10 values in the range of 7.3% to 11.9% and M40 values in the range of 76.3% to 79.1%.

7. A process as claimed in anyone of claims 1 to 6 which is carried out involving a system of hydraulically operated press for compaction of a pulverized coal for making a coal cake and transferring said coal cake to a pilot coke oven, said system comprising:

a press cylinder,

a top die attached to the said cylinder,

said cylinder attached to the top pressure plate whereby movement of the said cylinder causes corresponding movement of the top die attached to the cylinder rod for applying pressure on the pulverized coal charge filled in a mould box;

a guide arrangement comprising of guide rods attached to top die and passing through bushes in top pressure plate for ensuring a straight line motion of said press cylinder during pressing the pulverized coal charge in said mould box;

an ejector cylinder with a bottom die, the said ejector cylinder attached to the bottom pressure plate for ejecting said coal cake formed from the said mould box after compaction of said pulverized coal charge;

a guide arrangement for ensuring a straight line motion of said ejector cylinder during ejecting a compacted coal cake from said mould to said mould box;

a pusher cylinder with a pusher plate attached to pusher cylinder rod and mounted on a bracket attached to the said bottom pressure plate for pushing said compacted coal cake from said bottom die to a transfer trolley;

a guide arrangement for ensuring a straight line motion of said pusher cylinder during extension and retraction of said pusher cylinder;
wherein said transfer trolley comprises portable caster wheel(s), mechanism for height adjustment, extendable and retractable table having guide arrangement and lock arrangement for proper receiving said compacted coal cake and transporting said compacted coal cake to said pilot / experimental coke oven;

a hydraulic power pack for providing required flow and pressure for motion of said press cylinder, said ejector cylinder and said pusher cylinder during pressing, ejecting and pushing of said pulverized coal cake during compaction.

8. A process as claimed in claim 7 comprising using limit switch(s) provided with said pressing cylinder, for said ejecting cylinder and said pusher cylinder for stopping said cylinder (s) at the end of stroke as well as retracted position during pressing, ejecting and pushing.

Dated this the 1st day of April, 2014
Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)

,TagSPECI:FIELD OF THE INVENTION
The present invention relates to a process of producing stable coal cake for carbonization in pilot coke oven for testing of coal/coal-blend samples. More particularly, the present invention is directed to providing a process for compaction of pulverized coal of different granulometry and moisture levels to make adequately stable coal cake applying different pressures by involving suitably designed hydraulic press. The coal cake so produced can be charged in a slot type pilot coke oven for coke making. The stability of coal cake thus produced is considered adequate when its shape remain same without any breakage during ejection from mould box, its transfer from stamping station on to coal cake transfer-trolley and then its transfer to pilot coke oven. This invention provides a process, describing determination of requirements of pressure, crushing level, and moisture content and steps to be followed to ensure making a stable coal cake during its handling and transfer into pilot coke oven without any breakage.

BACKGROUND OF THE INVENTION
It is well known that hard coke is required for reduction of iron ore in blast furnace. For this, coke having requisite hardness and required size is charged along with iron ore in blast furnace. The properties of coking coals, used in blast furnace coke making, vary widely depending upon its origin and type. Moreover, different types of coal are blended to optimize coke cost and properties required for BF. Coal/coal blend samples are regularly tested by carbonization in slot type pilot coke oven for optimization studies. Technology of coal compaction provides means of improving coke properties even with use of inferior coking coals in blend. The carbonization tests under stamp charging require preparation of coal cake of required density and stability by compaction of coal/ coal blend of specified granulometry and moisture content. The coal cake density and stability to be achieved after compacting is dependent on factors like the granulometry and moisture content of prepared coal/ coal blend, and system of compaction under pressure.

The conventional system which was being followed in the Coal Carbonization Laboratory of R&D Centre of Iron & Steel (RDCIS) was entirely manual. The coal charge was being filled in a trolley mounted mould box by charging pulverized coal in batches and was manually pressed from top using repeated impacting motion of a weight by a person. After completion of formation of coal cake, the mould box bolts were opened and vertical side plates of the mould box were removed. The dummy back-plate was held in position manually. The top plate of the trolley carrying the coal cake was then extended into the pilot coke oven with the help of rack and pinion arrangement. The back plate was then supported by a pair of rods. The plate supporting the coal cake was then retracted with the help of rack and pinion and the coal cake remained inside the oven due to the dummy back-plate providing the reaction force. There was no system for controlling force for compaction and maintaining uniformity in density of cake. Also there was no means for controlling the pressure applied for compaction commensurate with granulometry and moisture level of prepared coal/ coal blend sample to produce coal cake of desired density and stability.

Therefore, there is a need in the art for developing a system and method of producing stable coal cake for carbonization in pilot coke oven for testing of coal/coal blend samples involving mechanized means for making compacted coal cake by pressing the pulverized and sized coal in a mould box with desired bulk density, which would control the pressure applied depending on granulometry and moisture level of coal/ coal blend sample as also maintain stability for ejection of coal cake from the mould, pushing of coal cake on to the transfer trolley, smooth transfer of the coal cake from trolley to smooth transfer of coal cake inside the pilot/experimental coke oven without any breakage.

In order to implement such a method, the present invention makes use of a system as disclosed in the co-pending patent application no. 226/KOL/2014 dated 21.02.2014 by the same applicants for making coal cake from coal/coal blend sample for carbonization testing in pilot coke oven involving hydraulic power pack, transfer trolley, associated pipings and tubings, associated main electrical panel and operator console, and cabling for operation of the hydraulic press.

OBJECTS OF THE INVENTION

The basic object of the present invention is thus directed to provide a process for producing coal cake of desired stability and density from coal/ coal blend samples for carbonization test in slot type pilot coke oven.

A further object of the present invention is directed to provide an improved Pulverized Coal Compaction Process using hydraulically operated stamping unit for making coal cakes from pulverized coal for study of coking behaviour of coal/ coal blend samples in a pilot coke oven.

A still further object of the present invention is directed to provide a process for producing coal cake of desired stability and density from coal/ coal blend samples having different granulometry and moisture content.

A still further object of the present invention is directed to provide a process to prepare stable coal cake from coal/ coal blend samples of crushing level of even less than 90% content of -3.2 mm and moisture content of even <10%.

Yet another object of the present invention is directed to providing a process for producing coal cake of desired stability and density from coal/ coal blend samples wherein controlled pressure would be applied on sample in mould for achieving desired density and stability of coal cake depending on granulometry and/or moisture level of coal sample.

A still further object of the present invention is directed to providing a process for producing coal cake of desired stability and density from coal samples wherein mechanized means are used to apply controlled pressure to form coal cake and smooth transfer of the coal cake taking out from mould to place in the pilot coke oven without breakage.

A still further object of the present invention is directed to providing a process for producing coal cake of desired stability and density from coal/ coal blend samples which would favour reducing energy consumption and shortening the carbonization time.

SUMMARY OF THE INVENTION

Thus according to the basic aspect of the present invention, there is provided a process for energy efficient production of stable coal cake from coals of different granulometry and moisture level comprising,

selectively involving coal/ coal blend samples of crushing level of even less than 90% content of -3.2 mm and moisture content of even < 10 %; and

applying controlled compaction force based on the granulometry and moisture level of the coal/ coal blend samples.

A further aspect of the present invention is directed to said process wherein said step of applying controlled compaction force comprises applying pressure on coal/ coal blend samples in a mould for each layer in relation to coal cake density to be achieved by controlled application of pressure through a hydraulic press based on said granulometry and total moisture content to achieve the desired coal cake density.

A still further aspect of the present invention is directed to said process wherein said controlled compaction force comprises application of pressure on coal/ coal blend sample in mould in relation to coal cake density to be achieved based on pre-determined relationship between pressure and coal cake obtained of: y= 0.064ln(x)+0.832, where x is the applied pressure in kg/cm2 and y is the coal cake density in g/cm3.

A still further aspect of the present invention is directed to said process, wherein stable coal cake is produced on use of crushing level of even 85 % content of 3.2 mm and total moisture content of even 8% at compaction force of 98 tons.

A still further aspect of the present invention is directed to said process wherein process of making coal cake is divided preferably in four installments/layers for increasing stability of coal cake.

A still further aspect of the present invention is directed to said process wherein carbonization of said coal cake with required density corresponding to a compaction force of 98 ton, confirms suitability of coke obtained thereof by observed values of M10 values in the range of 7.3% to 11.9% and M40 values in the range of 76.3% to 79.1%.

Yet another aspect of the present invention is directed to said process which is carried out involving a system of hydraulically operated press for compaction of a pulverized coal/ coal blend sample for making a coal cake and transferring said coal cake to a pilot coke oven, said system comprising:

a press cylinder,
a top die attached to the said cylinder,
said cylinder attached to the top pressure plate whereby movement of the said cylinder causes corresponding movement of the top die attached to the cylinder rod for applying pressure on the pulverized coal charge filled in a mould box;
a guide arrangement comprising of guide rods attached to top die and passing through bushes in top pressure plate for ensuring a straight line motion of said press cylinder during pressing the pulverized coal charge in said mould box;
an ejector cylinder with a bottom die, the said ejector cylinder attached to the bottom pressure plate for ejecting said coal cake formed from the said mould box after compaction of said pulverized coal charge;
a guide arrangement for ensuring a straight line motion of said ejector cylinder during ejecting a compacted coal cake from said mould to said mould box;
a pusher cylinder with a pusher plate attached to pusher cylinder rod and mounted on a bracket attached to the said bottom pressure plate for pushing said compacted coal cake from said bottom die to a transfer trolley;
a guide arrangement for ensuring a straight line motion of said pusher cylinder during extension and retraction of said pusher cylinder;
wherein said transfer trolley comprises portable caster wheel(s), mechanism for height adjustment, extendable and retractable table having guide arrangement and lock arrangement for proper receiving said compacted coal cake and transporting said compacted coal cake to said pilot / experimental coke oven;
a hydraulic power pack for providing required flow and pressure for motion of said press cylinder, said ejector cylinder and said pusher cylinder during pressing, ejecting and pushing of said pulverized coal cake during compaction.

A still further aspect of the present invention is directed to said process comprising using limit switch(s) provided with said pressing cylinder, for said ejecting cylinder and said pusher cylinder for stopping said cylinder (s) at the end of stroke as well as retracted position during pressing, ejecting and pushing.
The objects and advantages of the invention are described hereunder in greater details with reference to the following non limiting illustrative examples.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

Figure 1: shows graphically the correlation between coal cake density with applied pressure for laboratory scale cake preparation.

Figure 2: shows the photograph of newly designed, developed and installed hydraulically operated coal compaction system for implementing the method according to the present invention.

Figure 3: shows the photograph of the stable coal cake produced according to the process of the invention, after ejection and transfer from mould box on to the coal cake transfer tolley.

Figure 4: shows graphically the effect of coal charge compaction to produce stable coal cake on M10 and M40 values of coke produced thereof.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING FIGURES

The present invention is thus directed to provide a process for producing coal cake of desired stability and density from coal samples for carbonization test in slot type pilot coke oven.

The present invention thus provides an improved Pulverized Coal Compaction Process using newly designed hydraulically operated stamping unit involving a system as disclosed in the co-pending patent application no. 226/KOL/2014 for making coal cakes from pulverized coal for study of coking behaviour of coals and coal blends in a pilot coke oven

This invention is also aimed to prepare stable coal cake from coals of crushing level of even less than 90% content of -3.2 mm and moisture content of even <10%. This is in contrary to the existing process of stamp charging where crushing level is >90% - 3.2 mm content and moisture content is about 10%. This will help in reducing energy consumption.

The process according to the present invention involves developing of relationship between pressure and coal cake density in laboratory scale by experimental study. The first set of experiments for preparation of coal cake of density up to 1.05 g/cm3 was carried out using a 2 ton capacity hydraulically operated Universal Testing Machine and a mould of internal diameter of 40.24 mm. Experiments were carried out at loads of 40 kg, 50 kg, 80 kg, 120 kg, 160 kg, 190 kg, 290 kg and 300 kg. The prepared coal blend used was having crushing level of 90% -3.2 mm content and moisture content of 10%. To carry out tests at higher coal cake density, another set of experiments was carried out using 60 ton capacity Compression Testing Machine and mould of internal diameter 40 mm. Prepared coal blend properties were same as first set of experiments. Experiments were carried out at loads of 20 tons, 30 tons and 40 tons. At 40 tons load coal cake got crumbled. Cake density was 1.26 g/cm3 at 20 tons load and 1.28 g/cm3 at 30 tons load. The correlation between coal cake density and applied pressure for laboratory scale cake preparation is illustrated in accompanying Figure 1. The relationship between pressure and coal cake density obtained is y= 0.064ln(x)+0.832, where x is the applied pressure in kg/cm2 and y is the coal cake density in g/cm3. Estimation of requirement of force for preparation of coal cake of different densities for pilot coke oven, considering coal cake of length 90 cm and width 35.5 cm (area 3195 cm2) as obtained through experiments are given in following Table 1.

Table-1:
Force, ton Pressure, kg/cm2 Density, g/cm3
10 3.15 0.91
13 3.93 0.93
20 6.29 0.94
30 9.44 0.98
40 12.59 0.99
48 14.95 0.99
73 22.81 1.04
75 23.60 1.05
5088 1592.00 1.26
7631 2389.00 1.28

Results show that if density of coal cake is to be more than 1.05 the hydraulic system need to be designed of capacity of more than 75 tons. Considering the requirement of coal cake desity and other infrastructure constraints, the capacity of hydraulic press was set at 100 tons.

The hydraulic press of 100 tons capacity and coal cake transfer trolley were designed based on above mentioned results, system was fabricated and installed at applicants testing facility at RDCIS, Ranchi. Pilot oven carbonization tests were carried out to evaluate the stability of coal cake required for transfer from hydraulic press to cake transfer trolley and then for its transfer into coke oven.

The process of producing coal cake with required stability and density for carbonization test requires a system involving Hydraulic Press with mould box, press cylinder and top die, press cylinder guide arrangement, top and bottom pressure plates, ejection cylinder and bottom die, mould box, pusher cylinder and pusher plate and guide arrangement, hydraulic power pack, and wheel mounted height adjustable extendable/retractable and height adjustable coal cake transfer trolley along with its alignment and locking mechanism, electrical panel and operator control panel, and control logic for proper operation of the press. The arrangement of hydraulic power pack provides the necessary oil flow and pressure for operating the hydraulic cylinders for press, ejection and pushing and providing requisite forces as desired.

The method of the present invention is implemented by involving the above system for compression of pulverized coal charges of specific crushing level and with a predetermined moisture percentage either in batches and successive compression strokes or one complete charge of up to maximum possible level of the mould and then compression strokes as required.

To implement the process according to the present invention for producing coal cake of desired stability, the present invention makes use of the system as disclosed in the co-pending patent application no. 226/KOL/2014 with an arrangement of Hydraulic Cylinders viz. Press Cylinder, Ejector Cylinder, Pusher Cylinder. All cylinders are completely guided along their strokes. Two guide rods and corresponding guide bushes in the top pressure plate have been provided for the press cylinder and additionally it is guided by the mould box in the later part of the stroke. The ejection cylinder is guided by the mould box. The pusher cylinder is guided by the sleeves attached to the frame and rods attached to the pusher plate.

Accompanying Figure 2 shows the photograph of newly designed, developed and installed hydraulically operated coal compaction system for implementing the method according to the present invention.

Accompanying Figure 3 shows the photograph of the stable coal cake produced according to the process of the invention, after ejection and transfer from mould box on to the coal cake transfer tolley.

For coal cake preparation with required stability from various coal blend samples of specified granulometry and total moisture content for carbonization test according to the process of the present invention using the above mentioned system, all three cylinders are moved back to their respective home positions. The coal charge is manually filled in the mould box and the press cylinder is operated to apply the set force on the coal charge. The force is set by adjusting the pressure relief of the hydraulic system. The compaction can be done in successive batches, preferably in four layers, which are the equal installments of the total coal charge till the final size of the coal cake is achieved after the compaction of last batch. However, a single charge of coal filled in the mould box up to the maximum possible level can also be compressed to achieve a compacted coal cake. Then the press cylinder is moved back to its home position. The transfer trolley is positioned at the press on the alignment tracks and locked with the press structure. The top portion is also latched with the press. Its height wise alignment is done with the help of hydraulic jack & pump, and the top table is then extended to flush it with the mould box top to receive the cake smoothly. There are a set of rollers provided in the press for support to the extended top table of the transfer trolley. The ejector cylinder is operated and coal cake is ejected from the mould box. After ejection the pusher cylinder is operated while the ejector cylinder and bottom die cum ejector plate are still holding the cake in its extended position above the mould box. The coal cake is pushed on to the transfer trolley top table. The top table is then retracted to its home position by rack and pinion. The table height is then reduced by releasing the jack, the locks are opened and then the trolley is pushed and aligned with pilot coke oven on the alignment tracks. The trolley level is adjusted with the hydraulic jack and pump to align the top table with respect to the pilot coke oven floor. The trolley is then locked with the pilot coke oven. The top table is extended by the rack and pinion arrangement in the trolley and coal cake along with top table enters the coke oven chamber. The back plate is then positioned and locked with the trolley to keep the coal cake in position when the top plate of the trolley is moved backwards. The rack and pinion is then operated to pull the top plate back and the coal cake is positioned inside the pilot coke oven.

The above system thus provides facility for control of pressure/force on prepared coal/ coal blend samples in mould by hydraulic press depending on crushing level/granulometry and total moisture level, to achieve desired coal cake density.

Experiments studies were carried out to evaluate coal cake stability with variable force of compaction of different coal blend samples and the results are shown in following Table 2. Individual coal samples as mentioned in Table 2 were collected from SAIL plant (Bokaro Steel Limited) and brought to RDCIS, Ranchi. Individual coal samples were homogenized and representative samples were drawn for laboratory characterization. Blends were prepared as per specified compositions, crushed to specified granolometry and moisture was adjusted as specified in Table 2. Prepared coal blend samples were used to produce coal cake for carbonization tests. Experiments F-2 to F-5 show that the compaction force of 74 tons or more produced coal cake of enough stability which is required for its ejection from mould box, transfer from stamping station on to coal cake transfer trolley and then transfer from trolley to pilot coke oven chamber without any cake breakage. In these experiments, blend composition, granulometry and moisture content were maintained constant (within experimental variation). The coal cake density increased from 1.08 g/cm3 to 1.11 g/cm3 with increase in load from 74 tons to 103 tons. These results of coal cake density of hydraulically operated pilot coal compaction unit validate the correlation between pressure/ force and coal cake density developed based on laboratory experimental data.

Table 2:
Coal Blend Identification F-1 F-2 F-3 F-4 F-5
Coal-A (Imp. Hard) 30 30 30 30 30
Coal-B (Imp. Hard) 15 15 15 15 15
Coal-C (Imp. Soft) 10 10 10 10 10
Coal-D (Imp. Hard) 5 5 5 5 5
Coal-E (Ind. Prime) 5 5 5 5 5
Coal-F (Ind. Prime) 5 5 5 5 5
Coal-G (Ind. Medium) 15 15 15 15 15
Coal-H (Ind. Medium) 15 15 15 15 15
Total 100 100 100 100 100
Crushing Level, % of -3.2 mm 80 90 90 90 90
Total Moisture, % 6.9 9.6 10.0 10.3 9.9
Load on pilot oven coal cake, ton - 74 86 98 103
Charge Preparation Technology Top Stamp Stamp Stamp Stamp
Remarks - No cake breakage No cake breakage No cake breakage No cake breakage
M40, % 75.2 76.3 77.6 77.4 81.0
M10, % 16.9 12.4 11.6 12.3 11.1

Experiments studies were carried out to evaluate coal cake stability with variation in imported coals in blends as illustrated in following Table 3. It can be observed from the table that, when the content of imported coking coals in the blend increased from 60% to 85% and other parameters maintained constant (within experimental variation), the coal cake stability was adequate to safeguard from breakage.

Table 3:

Coal Blend Identification F-1 F-4 F-6 F-7
Coal-A (Imp. Hard) 30 30 30 30
Coal-B (Imp. Hard) 15 15 20 20
Coal-C (Imp. Soft) 10 10 30 30
Coal-D (Imp. Hard) 5 5 5 5
Coal-E (Ind. Prime) 5 5 5 5
Coal-F (Ind. Prime) 5 5 - -
Coal-G (Ind. Medium) 15 15 5 5
Coal-H (Ind. Medium) 15 15 5 5
Total 100 100 100 100
Crushing Level, % of -3.2 mm 80 90 80 90
Total Moisture, % 6.9 10.3 6.9 10.4
Load on pilot oven cake, ton - 98 - 98
Charge Preparation Top Stamp Top Stamp
Remarks - No cake breakage - No cake breakage
M40, % 75.2 77.4 82.7 78.2
M10, % 16.9 12.3 10.7 8.1

Further experimental studies were carried out to evaluate coal cake stability with variable crushing level of coal charge (granulometry) as illustrated in following Table 4. In these experiments, the granulometry of prepared coal blend samples was varied from 85% -3.2 mm content to 95% -3.2 mm content for coal cake preparation. The other parameters such as blend composition, moisture content and compaction force maintained constant (within experimental variation). Results showed that coal blend granulometry even of 85% -3.2 mm content also produced stable coal cake at moisture content of about 10% and compaction force of 98 tons. There was no adverse impact on M10 and M40 values due to change in granulimetry. Thus the production of stable coal cake even at lower crushing level will help in saving energy consumption without any adverse impact on M40 and M10 indices.
Table 4:

Coal Blend Identification F-1 F-10 F-4 F-9
Coal-A (Imp. Hard) 30 30 30 30
Coal-B (Imp. Hard) 15 15 15 15
Coal-C (Imp. Soft) 10 10 10 10
Coal-D (Imp. Hard) 5 5 5 5
Coal-E (Ind. Prime) 5 5 5 5
Coal-F (Ind. Prime) 5 5 5 5
Coal-G (Ind. Medium) 15 15 15 15
Coal-H (Ind. Medium) 15 15 15 15
Total 100 100 100 100
Crushing Level, % of -3.2 mm 80 85 90 95
Total Moisture, % 6.9 10.0 10.3 9.3
Load on pilot oven cake, ton - 98 98 98
Charge Preparation Top Stamp Stamp Stamp
Remarks - No cake breakage No cake breakage No cake breakage
M40, % 75.2 77.8 77.4 77.6
M10, % 16.9 11.3 12.3 10.9

Also additional experimental studies were carried out to evaluate coal cake stability at different total moisture content of the blends as illustrated in following Table 5. In these experiments, the moisture content of prepared coal blend samples was varied from 8.0% - to 10.8% for coal cake preparation. Experiments were carried out at imported coal usage of 85% in blends. Other parameters such as granulometry and compaction force maintained constant (within experimental variation). Results showed that stable coal cake could be produced with coal blend moisture content even at 8% with coal blend granulometry of 90% -3.2 mm content and compaction force of 98 tons. There was improvement in M10 and M40 indices of coke. Thus the production of stable coal cake even at lower moisture content will help in saving energy consumption with improvement in M10 and M40 indices of coke.

Table 5:

Coal Blend Identification F-1 F-12 F-7 F-11
Coal-A (Imp. Hard) 30 30 30 30
Coal-B (Imp. Hard) 15 20 20 20
Coal-C (Imp. Soft) 10 30 30 30
Coal-D (Imp. Hard) 5 5 5 5
Coal-E (Ind. Prime) 5 5 5 5
Coal-F (Ind. Prime) 5 0 - 0
Coal-G (Ind. Medium) 15 0 5 0
Coal-H (Ind. Medium) 15 10 5 10
Total 100 100 100 100
Crushing Level, % of -3.2 mm 80 90 90 90
Total Moisture, % 6.9 8.0 10.4 10.8
Load on pilot oven cake, ton - 98 98 98
Charge Preparation Top Stamp Stamp Stamp
Remarks - No cake breakage No cake breakage No cake breakage
M40, % 75.2 79.4 78.2 78.2
M10, % 16.9 7.3 8.1 8.0

The process according to the present invention thus help to prepare stable coal cake from coals of crushing level of even less than 90% content of -3.2 mm and moisture content of even <10%.

The stable coal cake thus produced is subjected to carbonization test in slot type pilot coke oven. Accompanying Figure 4 shows graphically the effect of coal charge compaction to produce stable coal cake on M10 and M40 values of coke produced thereof.

It is thus possible by way of the present invention to provide an improved Pulverized Coal Compaction Process using hydraulically operated stamping unit for making coal cakes from pulverized coal for study of coking behaviour of coals/ coal blends in a slot type pilot coke oven involving making coal cake at different pressure, from coal charge having different crushing level and moisture content. Also a relationship is determined experimentally between pressure and density of coal cake in laboratory hydraulic press with required control system for applying variable pressure on samples in mould. Importantly, the process is capable to prepare stable coal cake from coals of crushing level of even less than 90% content of -3.2 mm and moisture content of even <10%, which would produce coke on carbonization. Reduction in crushing level or moisture content of prepared coal/ coal blend would be helpful in saving energy consumption. Reduction in moisture content can also help in improving M10 and M40 indices of coke.

We Claim:
1. A process for energy efficient production of stable coal cake from coals of different granulometry and moisture level comprising,

selectively involving coal/ coal blend samples of crushing level of even less than 90% content of -3.2 mm and moisture content of even < 10 %; and

applying controlled compaction force based on the granulometry and moisture level of the coal/ coal blend samples.

2. A process as claimed in claim 1 wherein said step of applying controlled compaction force comprises applying pressure on coal blend charge in a mould for each layer in relation to coal cake density to be achieved by controlled application of pressure through a hydraulic press based on said granulometry and total moisture content to achieve the desired coal cake density.

3. A process as claimed in anyone of claims 1 or 2, wherein said controlled compaction force comprises application of pressure on coal blend charge in mould in relation to coal cake density to be achieved based on predetermined relationship between pressure and coal cake obtained of: y= 0.064ln(x)+0.832, where x is the applied pressure in kg/cm2 and y is the coal cake density in g/cm3.

4. A process as claimed in anyone of claims 1 to 3, wherein stable coal cake is produced even on use of crushing level of even 85 % content of 3.2 mm and total moisture content of even 8% at compaction force of 98 tons.

5. A process as claimed in anyone of claims 1 to 4, wherein process of making coal cake is divided preferably in four installments/layers for increasing stability of coal cake.

6. A process as claimed in anyone of claims 1 to 5, wherein carbonization of said coal cake with required density corresponding to a compaction force of 98 ton, confirms suitability of coke obtained thereof by observed values of M10 values in the range of 7.3% to 11.9% and M40 values in the range of 76.3% to 79.1%.

7. A process as claimed in anyone of claims 1 to 6 which is carried out involving a system of hydraulically operated press for compaction of a pulverized coal for making a coal cake and transferring said coal cake to a pilot coke oven, said system comprising:

a press cylinder,

a top die attached to the said cylinder,

said cylinder attached to the top pressure plate whereby movement of the said cylinder causes corresponding movement of the top die attached to the cylinder rod for applying pressure on the pulverized coal charge filled in a mould box;

a guide arrangement comprising of guide rods attached to top die and passing through bushes in top pressure plate for ensuring a straight line motion of said press cylinder during pressing the pulverized coal charge in said mould box;

an ejector cylinder with a bottom die, the said ejector cylinder attached to the bottom pressure plate for ejecting said coal cake formed from the said mould box after compaction of said pulverized coal charge;

a guide arrangement for ensuring a straight line motion of said ejector cylinder during ejecting a compacted coal cake from said mould to said mould box;

a pusher cylinder with a pusher plate attached to pusher cylinder rod and mounted on a bracket attached to the said bottom pressure plate for pushing said compacted coal cake from said bottom die to a transfer trolley;

a guide arrangement for ensuring a straight line motion of said pusher cylinder during extension and retraction of said pusher cylinder;
wherein said transfer trolley comprises portable caster wheel(s), mechanism for height adjustment, extendable and retractable table having guide arrangement and lock arrangement for proper receiving said compacted coal cake and transporting said compacted coal cake to said pilot / experimental coke oven;

a hydraulic power pack for providing required flow and pressure for motion of said press cylinder, said ejector cylinder and said pusher cylinder during pressing, ejecting and pushing of said pulverized coal cake during compaction.

8. A process as claimed in claim 7 comprising using limit switch(s) provided with said pressing cylinder, for said ejecting cylinder and said pusher cylinder for stopping said cylinder (s) at the end of stroke as well as retracted position during pressing, ejecting and pushing.

Dated this the 1st day of April, 2014
Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)

ABSTRACT

TITLE: A PROCESS FOR ENERGY EFFICIENT PRODUCTION OF STABLE COAL CAKE FROM COALS OF DIFFERENT GRANULOMETRY AND MOISTURE LEVEL.

The present invention relates to a process for compaction of pulverized coal of different granulometry and moisture levels to make adequately stable coal cake applying required controlled pressure based on said granulometry and/or moisture level by involving suitably designed hydraulic press. The coal cake so produced can be charged in a slot type pilot coke oven for coke making. The stability of coal cake thus produced is considered adequate when its shape remain same without any breakage during ejection from mould box, its transfer from stamping station on to coal cake transfer-trolley and then its transfer to pilot coke oven. This invention provides a process describing determination of requirements of pressure, crushing level and moisture content, and steps to be followed to ensure making a stable coal cake during its handling and transfer to pilot coke oven without any breakage in an energy efficient manner.