DESC:FIELD OF THE INVENTION

The present invention is directed to sinter system including pallet car/sinter bed and grate bar combination having extended width of pallet car/sinter bed adapted for uniform air flow across all grate bars for favouring uniform combustion and maintaining sinter quality and also to a method for controlling sintering involving sinter system including pallet car/sinter bed and grate bar combination having extended width of pallet car/sinter bed. Importantly, the advancement provide sinter bed configuration incorporating modified grate bars at extended width of sinter bed for uniform air flow favouring improved quality of sinter. More particularly, according to a basic aspect of the present invention the same is directed to provide a sinter bed configuration wherein the side wall of Pallet car near the dead zone/blind spot formed due to extension of width of Pallet car/sinter bed is blocked and optionally, in addition the grate bars of modified configuration incorporated near sides having more of less similar design/cross section but with a reduced width and increased number of gaps thus enables more air flow per unit area making air flow more uniform in side locations thus improving sinter productivity and quality as well as life of grate bars is enhanced.

BACKGROUND OF THE INVENTION

In applicant’s existing sinter plant, technology was provided by MECC China. In order to increase the productivity, sinter plant width was increased by 10% and increased productivity was achieved. This is a typical approach by many of the sinter plants to increase the productivity by width extension. In existing system, due to non-uniform air flow across the width of the sinter bed, selective damage of specific grate bars was observed. Detailed analysis of air flow across the Pallet car width using mathematical model indicates differential air flow at various locations. Moreover, at the extended width portion at sides, there exists a dead zone which is out of suction zone causing non uniform air flow through sinter bed.

It is known that feed mix charged on a sinter bed contains coal/coke as fuel among other constituents including iron ore fine, fluxes, secondary materials etc. Air is sucked from bottom through grate bars. Feed mix is burnt from top and ignition layer travels downwards as sintering process proceeds. Maximum temperature reaches to around 1300oC in burning zone. Outlet gas leaving grate bars is at a significantly high temperature at a high velocity. This erodes the grate bars. In existing system, due to non-uniform air flow through various grate bars, those grate bars where air flow is more, gets damaged earlier than other grate bars.

Due to width extension, a dead zone was created on the corner of Pallet car/sinter bed. Air flow is restricted due to geometry and grate bars 1-3 comes under a blind spot. Suction air thus finds its path from grate bar no 4 onwards. Hot air (generally around 400oC) leaves the grate bars. Under ideal conditions, air flow across all the grate bars should be same and they should be exposed to the similar temperature. But, in existing system, due to 1-3 grate bars falling in blind spot, air velocity and temperature are increased in 4-6 grate bars. Moving ahead to grate bars no.7 onwards, it tends to be more or less uniform. That is why grate bars no. 4-6 are having more damage. Also the sinter quality in dead zone is poor due to incomplete combustion of sinter mix leading to less productivity.

There has been thus a continuing need to provide a sinter bed configuration on Pallet car with width extension which would avoid blind spot formation at side corners to ensure uniform air flow across the width of the sinter bed and favour improved sinter quality and productivity as well as enhanced life of grate bars.

OBJECTS OF THE INVENTION

Thus according to the basic object the present advancement is directed to meet the continuing need to provide a sinter bed configuration on pallet car with width extension which would avoid blind spot formation at side corners to ensure uniform air flow across the width of the sinter bed and favour improved sinter quality and productivity as well as enhanced life of grate bars.

According to a further aspect the need to provide a sinter bed configuration on pallet car with width extension which would avoid blind spot formation at side corners to ensure uniform air flow across the width of the sinter bed and favour improved sinter quality and productivity as well as enhanced life of grate bars is addressed with or without incorporating modified grate bars at extended width of sinter bed for uniform air flow favouring improved quality of sinter.

A further object of the present invention is directed to provide a sinter bed configuration on pallet car with width extension which would avoid blind spot formation at side corners to ensure uniform air flow across the width of the sinter bed and favour improved sinter quality and productivity as well as enhanced life of grate bars is addressed with or without sinter bed configuration incorporating modified grate bars at side locations on pallet car comprising arrangements of grate bars consisting of narrower grate bars at the side followed by regular arrangement to ensure more gap at sides for improved air flow as well as avoiding blind spot/dead zone at the corner to avoid production of bad quality sinter leading to fluctuation of overall quality and loss of yield and to ensure uniform air flow across the width.

A still further object of the present invention is directed to provide sinter bed configuration incorporating modified grate bars at side locations on Pallet car which would ensure proper sintering thus improving sinter quality and productivity.

A still further object of the present invention is directed to provide sinter bed configuration incorporating modified grate bars at side locations on Pallet car which would enhance life of grate bars by ensuring uniform flow of air through sinter bed across the width.

SUMMARY OF THE INVENTION

Thus according to a basic aspect of the present invention there is provided a sinter system including pallet car/sinter bed and grate bar combination having extended width of pallet car/sinter bed adapted for uniform air flow across all grate bars for favouring uniform combustion and maintaining sinter quality comprising:

pallet car/sinter bed with extended width providing for feeding sinter input material alongwith fuel;

grate bars allowing passage of gas flow from thereunder said sinter bed wherein said extended width of said sinter bed beyond the grate bars width providing for dead zone at the side/end with insufficient supply of gas flow for effective combustion and sintering;

said dead zone at the side/end of said pallet car/sinter bed comprise blocked dead zone to avoid any inefficient combustion or sintering and enabling uniform combustion and maintaining sinter quality.

According to another aspect the sinter system as above is disclosed wherein the dimensions of said dead zone vary from 15-30mm width and 5-20mm height.

According to another aspect the sinter system as above is disclosed wherein said blocked dead zone comprise said dead zone filled with hearth material layer preferably upto a level of 50-60 cm from base hearth layer.

According to yet another aspect the sinter system as above is disclosed comprising blocking the dead zone in said pallet car/sinter bed by welding steel plate.

According to another aspect the sinter system as above is disclosed wherein said steel plate is welded covering locking plate & quarter pin.

According to another aspect the sinter system as above is disclosed wherein said blocked dead zone comprising blocking of the dead zone in said pallet car/sinter bed by fastening blank plate on the side of the pallet car including by extending locking pin in a way to accommodate the required geometry of dead zone thus blocking the dead zone.

According to another aspect the sinter system as above is disclosed wherein said blocked dead zone comprising said blocking said dead zone by blanking plate attached to the side wall.

According to another aspect the sinter system as above is disclosed comprising said grate bar air /gas flow passage modulation means comprising variable grate bar width for increasing air/gas flow.

According to yet another aspect there is disclosed a method of controlling sintering involving sinter system including pallet car/sinter bed and grate bar combination having extended width of pallet car/sinter bed as above for uniform air flow across all grate bars for favouring uniform combustion and maintaining sinter quality comprising:

step of blocking said dead zone at the side/end of said pallet car/sinter bed such as to avoid any inefficient combustion or sintering and enabling uniform combustion and maintaining sinter quality.

According to yet another aspect of the present invention there is provided a method as above wherein said step of blocking said dead zone comprises selectively:

(a) Filling said dead zone with hearth material layer preferably upto a level of 10-20 cm from base hearth layer.
(b) blocking the dead zone in said pallet car/sinter bed by welding steel plate.
(c) by fastening blank plate on the side of the pallet car including by extending locking pin in a way to accommodate the required geometry of dead zone thus blocking the dead zone.

According to another aspect there is disclosed a method as above comprising the step of increasing air/gas flow though grate bars by modulation grate bar width for increasing air/gas flow.

Thus, it would be apparent from the above stated that the advancement according to the present invention is directed to a modified sinter bed configuration incorporating modified grate bars at extended width of sinter bed for uniform air flow comprising any one of (i) physical blocking of the dead zone at the side corner of pallet car to avoid the bad quality sinter and thus leading to improvement in sinter yield and overall quality, and optionally, additionally (ii)decreasing the width of the grate bars in 10 grate bars in the side by 5 mm, thus making space for 12 grate bars thereby increasing the total gap area in the affected zone and thus increase the air flow in the dead zone and adjoining area by 12-13% thus improving the product quality.

A further aspect of the present invention is directed to a modified sinter bed configuration incorporating (i) physical blocking of the dead zone at the side corner of pallet car to avoid the bad quality sinter and thus leading to improvement in sinter yield and overall quality and optionally (ii) modified grate bars at extended width of sinter bed for uniform air flow comprising a combination of solution (i) and (ii) above that is blocking of the dead zone side wall and reduced width of side grate bars to increase number of grate bars and gaps in between to enhance the sinter yield and quality.

A still further aspect of the present invention is directed to a modified sinter bed configuration incorporating modified grate bars at extended width of sinter bed comprising grate bars at side locations on pallet car comprising arrangements of grate bars consisting of narrower grate bars at the side followed by regular arrangement to ensure more gap at sides avoiding blind spot/dead zone at the corner and uniform air flow across the width.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Figure 1: Show the schematic line diagram disposition of existing grate bars in relation to existing pallet cars with width extension in front view, side view and top view and the existing shape configuration of grate bars that causes non uniform air flow.

Figure 2: shows non uniform air flow across the sinter bed with width extension in existing sinter plant specifically in the area marked with arrow.

Figure 3: shows the uniform air flow across the modified sinter bed configuration involving blocking of side wall in the dead zone and introducing grate bars with reduced width near the sides to increase gap for passage of air according to present invention.

Figure 3A is a 3D line view of pallet car mentioning dead zone area;
Figure 3B Front view of pallet car (line diagram);
Figure 3C Front view of pallet car for modification done by blanking dead zone;
Figure 3D Front view of pallet car showing modified locking pin design;
Figure 3E Front view of pallet car showing change location of locking pin design;
Figure 4: shows the schematic top view of the Pallet car consisting of multiple grate bars.

Figure 5: shows the sectional Front view of one grate bar used according to present invention.
Figure 6: shows the schematic disposition of grate bars in the modified configuration of sinter bed/pallet car which show the narrow grate bars placed near each sides in a row followed by regular grate bars.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS

The present invention is directed to provide sinter bed configuration incorporating modified grate bars at extended width of sinter bed for uniform air flow. The invention involves blocking the side wall of dead zone/blind spot of Pallet cars/sinter bed and optionally further involves a modified sinter bed configuration incorporating modified grate bars at side locations on pallet car comprising arrangements of grate bars consisting of narrower grate bars at the side followed by regular arrangement to ensure more gap at sides avoiding blind spot/dead zone at the corner and uniform air flow across the width favouring improved sinter quality and productivity.

In order to increase the productivity, the width of existing sinter plant was increased by 10% which improved productivity and yield. In existing system, due to non-uniform air flow across the width of the sinter bed, selective damage of specific grate bars was observed.

Accompanying Figure 1 show the schematic line diagram disposition of existing grate bars in relation to existing pallet cars with width extension in front view, side view and top view and the existing shape configuration of grate bars that causes non uniform air flow. Figure 1 clearly show the following features of the existing sinter bed configuration:
1. Sinter feed mix (front view)
2. Sinter feed mix (front view)
3. Grate bar plane (front view)
4. Suction area
5. Grate bar plane (side view)
6. Dead zone which is out of suction zone

Sinter feed mix is charged in zone 1 & 2 shown in Figure 1. This feed mix contains coal/coke as fuel among other feed mix (including iron ore fine, fluxes, secondary materials etc). Air is sucked from bottom (4 in fig 1) through grate bars (3 in fig 1). Feed mix is burnt from top and ignition layer travels downwards in a movement similar to a cigarette smoking. Maximum temperature reaches to around 1300oC in burning zone. Outlet gas leaving grate bars is at a significantly high temperature at a high velocity. This erodes the grate bars. In existing sinter bed, due to non-uniform air flow through various grate bars, those grate bars where air flow is more, gets damaged earlier than other grate bars.

Accompanying Figure 2 shows the nature of non uniform air flow across the sinter bed with width extension in existing sinter plant specifically in the area marked with arrow.

Due to width extension, a dead zone was created on the corner (6 in fig 1 & circle marked in fig 2). Air flow is restricted due to geometry and grate bars 1-3 comes under a blind spot. Suction air finds its path from grate bar no 4 onwards.

Hot air (generally around 400oC) leaves past the grate bars. Under ideal conditions, air flow across all the grate bars should be same and they should be exposed to the similar temperature. But, in existing sinter bed condition, due to 1-3 grate bars falling in blind spot, air velocity and temperature are increased in 4-6 grate bars. Moving ahead to grate bars no. 7 onwards, it tends to be more or less uniform. That is why grate bars no. 4-6 are having more damage.

In order to ensure uniform air flow across the width of the sinter bed/Pallet car, following solutions have been provided by way of the present invention which provide an improved sinter bed configuration involving a combination approach which is directed to improve the sinter productivity and yield as well as sinter quality by avoiding formation of blind spot/dead zone and ensuring uniform combustion of sinter mix:

Solution 1: (blocking the dead zone):

As explained earlier, present case suffers from a dead zone at the corner due to which, poor quality sinter is getting generated.
In proposed solution 1, physical blocking of the dead zone is done using modification in existing designs. This modification is very challenging as this ‘end part’ of the Pallet car (dead zone) have some functional role like mechanical locking of the grate bars. This modification will avoid the bad quality sinter and thus lead to improvement in sinter yield and overall quality. Solution 1 thus helps avoiding any material in dead zone where only bad sinter is made. This bad sinter contributes to fluctuation in overall quality and loss of yield parameter. This solution will prevent production of absolutely bad sinter.

Accompanying Figure 3 shows the uniform air flow across the modified sinter bed configuration involving blocking of side wall in the dead zone with or without introducing grate bars with reduced width near the sides to increase gap for passage of air according to present invention.

Solution 1: As described hereinbefore based on air flow simulation a dead zone is formed on the sides which causes poor sinter properties. Studies done at plant trial to physically validate the findings of simulation. We have measured the dimensions of the dead zone. Dimensions of the dead zone may vary from 15-30mm width and 5-20mm height. For example, in our present case measured Width of dead zone is 23 cm and measured height is 11 cm. Fraction of dead zone is calculated close to 1.4 % of total volume of working sinter bed but may vary from 0.5% to 5% depending on the geometry.

Figure 3A shows a 3D line view of pallet car mentioning dead zone area dimensions. Line 2 is for Hearth layer level.

As shown in Figure the same illustrates 1 – Dead zone area Blanking and 2- Hearth layer level below dotted line

Importantly, when a feed mix (or charge mix/ green mix) is added in the pallet car, among other input materials (e.g. iron ore fine, secondary iron bearing materials, flux etc) fuel is also added in the form of coal/ coke fines. If a dead zone forms where sintering is not taking place due to inadequate air flow, fuel might burn slowly without giving required heat hence will not produce sinter of acceptable quality resulting in very less yield of usable sinter from that zone. Now, this bad quality of sinter will again be recirculated as input feed and will require fuel second time also. So, if a bad quality of sinter is generated which is recirculated (typically called return fine) every time it will consume extra fuel in proportion to its quantity. This extra fuel results in extra cost and extra CO2 emission alongwith less sinter yield. Hence dead zone needs to be blocked so that no charge mix is fed into the zone which creates bad sinter

Accordingly, the present advancement provides for system and method of blocking of dead zone as discussed hereunder:

(i) Feeding extra hearth layer material at both side, so that dead zone is filled with hearth layer material. Hearth layer material is actual product sinter material (15-20 mm size) which is used in the bottom layer of the sinter charge mix. This helps in preventing over heating of grate bars as well as gives desired permeability at the bottom layer.

Importantly, it is by way of the present advancement that a selective coverage of hearth layer, only upto 15 cm (which can vary from 5 to 20 cm depending on geometry) from base hearth layer is to be filled up in a pallet car with feed mix height of 500-800mm is disclosed for the purpose to block the dead zone which has never been attempted earlier. This has resulted in the elimination of fines generation from same area.

Figure 3B illustrates the Front view of pallet car (line diagram).

As shown in Figure 3B the same illustrates :1 – Existing leveller outline
2 – Proposed leveller outline, 3 – Grate bar level.

Reference is now invited to accompanying Figure 3C which illustrates an embodiment of blanking dead zone by welding plate. As apparent from said Figure, the blanking done in pallet car by blocking the dead zone by welding steel plate. This can be achieved very simply and does not call for any design change such as the steel plate welded covering locking plate (2) & quarter pin (3) as shown in the figure.

Figure 3C - Front view of pallet car for modification done by blanking dead zone (line diagram)

In Figure 3C: 1- Blank Plate, 2- Locking pin, 3- End Grate bar.

According to yet another embodiment of the present invention the blanking of dead zone using modified locking pin is illustrated. Locking pin is used to fasten blank plate on the side of the pallet car attached to the side wall. In proposed invention, head of the locking pin can be extended in a way to accommodate the required geometry of dead zone thus blocking the dead zone

As shown in Figure 3D - Front view of pallet car showing modified locking pin design. (Elongated locking pin so easy removal in maintenance mode)

Figure 3D clearly illustrates: 1- Blanking plate, (part of the proposed inventive step) 2- Locking pin, 3- End Grate bar.

According to yet another aspect of the present advancement the said blanking can be done by modified end plate/ blanking plate. For the purpose one end of blanking plate is attached to the side wall. In proposed advancement, as per accompanying Figure 3E , there is illustrated Front view of pallet car showing change location of locking pin design. (Elongated locking pin so easy removal while in maintenance)

In Figure 3E: 2 – Locking pin, 4 - End plate design extended to block dead zone.

In accordance with yet another aspect of the present advancement there is provided for an optional additional Solution 2: (reducing grate bar width in side grate bars):

Analysis shows that the main cause of non-uniform air flow is less air flow in side grate is bars due to geometrical constraints. One proposed solution is to decrease the width (by 5 mm) of the grate bars in 10 grate bars in the side, thus making space for 12 grate bars. This solution increases the total gap area in the affected zone and thus increase the air flow in the dead zone and adjoining area by 12-14% thus improving the product quality. Thus under this option air flow will be improved by 12-14% next to dead zone, favouring improvement in quality & yield from this area.

According to modification implemented by way of present invention, 10 grate bars from the side/end are chosen for modification. Existing width of individual grate bars is 30 mm and the modification involves reducing the width to 25 mm keeping shape similar to earlier. It increases effective opening for gas flow in the side area where it was earlier restricted and causing problems. Analysis done using CFD (computational fluid dynamics) indicates that there is an increase of around 12-13% air flow from the dead zone.

Accompanying Figure 4 shows the schematic top view of the Pallet car consisting of multiple grate bars according to present invention and Figure 5 shows the sectional Front view of one grate bar used in the modified senter bed configuration according to present invention.

Accompanying Figure 6 show the disposition of grate bars in the modified configuration of sinter bed/pallet car which show the narrow grate bars placed near the sides followed by regular grate bars. This increases the total number of grate bars and hence total gap for air passage. Figure 6 shows schematically the comparative of grate bar arrangement in (a) existing sinter bed versus (b) modified configuration wherein reduced width in grate bar number 1-10 and introducing 2 extra grate bars on each side in each row on pallet car to increase gaps to improve flow of air.

According to an embodiment of the present invention as illustrated in Figure 6, following arrangement of grate bars were introduced:

Present width (including extension) is: 3.5m; Total no of grate bars: 309 (one Pallet car has three rows, approx. 100-103 grate bars are placed in one row);

Width after modification: 3.5m; Total no of grate bars after extension: 309+12;

2 grate bars will be added on each side. So for 2 sides in one row: 4 extra grate bars; For three rows in one Pallet car: 4x3=12 extra grate bars are provided hence increasing the number of gaps for air passage.

It is thus possible by way of the present invention to provide sinter bed configuration directed to sinter system including pallet car/sinter bed and grate bar combination having extended width of pallet car/sinter bed adapted for uniform air flow across all grate bars for favouring uniform combustion and maintaining sinter quality and also to a method for controlling sintering involving sinter system including pallet car/sinter bed and grate bar combination having extended width of pallet car/sinter bed. More particularly, therefore according to a basic aspect of the present invention the same is directed to provide a sinter bed configuration wherein the side wall of Pallet car near the dead zone/blind spot formed due to extension of width of Pallet car/sinter bed is blocked and optionally, in addition the grate bars of modified configuration incorporated near sides having more of less similar design/cross section but with a reduced width and increased number of gaps thus enables more air flow per unit area making air flow more uniform in side locations thus improving sinter productivity and quality as well as life of grate bars is enhanced.

Advantageously therefore, the present invention is directed to provide a sinter bed configuration wherein the side wall of Pallet car near the dead zone/blind spot formed due to extension of width of Pallet car/sinter bed is blocked to avoid generation of bad sinter and improve yield and optionally in addition the grate bars of modified configuration incorporated near sides having more of less similar design/cross section but with a reduced width and increased number of gaps thus enables increased air flow per unit area by 12-14% in side locations making air flow more uniform across the width of pallet car thus improving sinter productivity and quality as well as life of grate bars is enhanced.

,CLAIMS:WE CLAIM:

1. Sinter system including pallet car/sinter bed and grate bar combination having extended width of pallet car/sinter bed adapted for uniform air flow across all grate bars for favouring uniform combustion and maintaining sinter quality comprising:

Pallet car/sinter bed with extended width providing for feeding sinter input material alongwith fuel;

grate bars allowing passage of gas flow from thereunder said sinter bed wherein said extended width of said sinter bed beyond the grate bars width providing for dead zone at the side/end with insufficient supply of gas flow for effective combustion and sintering;

said dead zone at the side/end of said pallet car/sinter bed comprise blocked dead zone to avoid any inefficient combustion or sintering and enabling uniform combustion and maintaining sinter quality.

2. Sinter system as claimed in claim 1 wherein the dimensions of said dead zone vary from 15-30mm width and 5-20mm height.

3. Sinter system as claimed in anyone of claims 1 or 2 wherein said blocked dead zone comprise said dead zone filled with hearth material layer preferably upto a level of 15 cm from base hearth layer.

4. Sinter system as claimed in anyone of claims 1 to 2 comprising blocking the dead zone in said pallet car/sinter bed by welding steel plate.

5. Sinter system as claimed in claim 4 wherein said steel plate is welded covering locking plate & quarter pin.

6. Sinter system as claimed in anyone of claims 1 to 2 wherein said blocked dead zone comprising blocking of the dead zone in said pallet car/sinter bed by fastening blank plate on the side of the pallet car including by extending locking pin in a way to accommodate the required geometry of dead zone thus blocking the dead zone.

7. Sinter system as claimed in anyone of claims 1 to 2 wherein said blocked dead zone comprising said blocking said dead zone by blanking plate attached to the side wall.

8. Sinter system as claimed in anyone of claims 1 to 7 comprising said grate bar air /gas flow passage modulation means comprising variable grate bar width for increasing air/gas flow.

9. A method of controlling sintering involving sinter system including pallet car/sinter bed and grate bar combination having extended width of pallet car/sinter bed as claimed in anyone of claims 1 to 8 for uniform air flow across all grate bars for favouring uniform combustion and maintaining sinter quality comprising :

step of blocking said dead zone at the side/end of said pallet car/sinter bed such as to to avoid any inefficient combustion or sintering and enabling uniform combustion and maintaining sinter quality.

10. A method as claimed in claim 9 wherein said step of blocking said dead zone comprises selectively:

(a) Filling said dead zone with hearth material layer preferably upto a level of 15 cm from base hearth layer.
(b) blocking the dead zone in said pallet car/sinter bed by welding steel plate.
(c) by fastening blank plate on the side of the pallet car including by extending locking pin in a way to accommodate the required geometry of dead zone thus blocking the dead zone.

11. A method as claimed in anyone of claims 9 or 10 comprising the step of increasing Air/gas flow though grate bars by modulation grate bar width for increasing air/gas flow.

Dated this the 12th day of September, 2017 Anjan Sen
of Anjan Sen & Associates
(Applicants Agent)