Title of Invention	" A SLIT BURNER FOR USE IN SINTERING PLANTS OF STEEL INDUSTRY"
Abstract	The invention provides a slit burner for use in sintering plants of steel industry, which is capable of producing a curtain-type flame having uniform temperature at a reduced fuel consumption and mounted in. an assembly of a plurality of burners on the roof of the ignition hood of sintering plants with a flame of short length, increased turndown and excess air ratios, and two-stage combustion. The burner comprises a vertically erected central tube for supplying fuel gases, an intermediate tube for supplying primary air and an outer tube for supplying secondary air to the burner, the central tube terminating in a nozzle which extends upto the burner tip and is provided with a sleeve therein for controlling the flow of fuel gases therethrough, the space between the central tube and the intermediate tube being provided with a swirler near the burner tip for imparting a swirling motion to the primary air flowing therethrough, and the space between the intermediate tube and the outer tube being provided with pair of slits, one on each laterial side of the burner tip, for allowing the secondary air to flow therethrough and control the shape of the flame produced by the burner to be of curtain type, the burner tip being fitted into a burner block which is housed in a double walled metallic box and is provided with tapered groovy expanding downwardly.

Title of Invention

" A SLIT BURNER FOR USE IN SINTERING PLANTS OF STEEL INDUSTRY"

Abstract

The invention provides a slit burner for use in sintering plants of steel industry, which is capable of producing a curtain-type flame having uniform temperature at a reduced fuel consumption and mounted in. an assembly of a plurality of burners on the roof of the ignition hood of sintering plants with a flame of short length, increased turndown and excess air ratios, and two-stage combustion. The burner comprises a vertically erected central tube for supplying fuel gases, an intermediate tube for supplying primary air and an outer tube for supplying secondary air to the burner, the central tube terminating in a nozzle which extends upto the burner tip and is provided with a sleeve therein for controlling the flow of fuel gases therethrough, the space between the central tube and the intermediate tube being provided with a swirler near the burner tip for imparting a swirling motion to the primary air flowing therethrough, and the space between the intermediate tube and the outer tube being provided with pair of slits, one on each laterial side of the burner tip, for allowing the secondary air to flow therethrough and control the shape of the flame produced by the burner to be of curtain type, the burner tip being fitted into a burner block which is housed in a double walled metallic box and is provided with tapered groovy expanding downwardly.

Full Text	The present invention relates to a slit burner for use in the sintering plants of steel industry. The invention relates, more particularly, to an assembly of five slit burners each comprising a vertically erected central tube for supplying fuel gases; an intermediate tube for supplying primary air; an outer tube for secondary air; and a quarl or refractory block called burner block , common for all the five burners in the assembly, housed in a double walled metallic box with five pairs of slits in-between the two vertical lateral walls of the box, one pair being provided for each burner, for supplying the secondary air to control the shape of the flame produced by the burners. The conventional burners used in sintering plants, such as turbulent burners, flat flame burners and tube-in-tube type burners have certain drawbacks, namely, instability of flame temperature, non-uniform ignition across the width of the sinter bed and increased fuel consumption. The flame produced is of relatively long bushy type, low turn down ratio, low excess air ratio and single stage corahustion. These are suitable for erection on the side walls of the ignition hood of sinter bed at an inclination to the sinter bed. The objective of the present invention is to provide a slit burner of improved design and construction, which is capable of producing a flame Of stable temperature at a reduced energy consumption, and of short length, increased turn down and excess air ratios, and two-stage combustion. The other objective is to provide a slit burner which can be mounted in an assembly on the roof of the ignition hood, perpendicular to the sinter bed. The invention is described fully and particularly, without restricting its scope in any manner, with reference to the accompanying drawings, in which Figure 1 is a sketch showing the section in the vertical plane of a conventional tube-in-tube type burner fitted in the wall of ignition hood of the sintering furnace; Figure 2 is a view of an embodiment of the invented slit burner in the vertical plane; Figure 3 is the plan view of the horizontal section at A-A in Figure 2; Figure 4 is a schematic diagram of the burner block and shape of the flame produced in an assembly of slit burners; Figure 5 is a sectional view of the gas nozzle sleeve of the slit burner; Figure 6 is a sketch of vane swirlers of different angles used in the slit-buraer; Figure 7 is the longitudinal section of the gear type swirler used in the slit burner; Figure 8 is the cross section of the gear type swirler used in the slit burner; aad Figure 9 is the sectional view of the sintering furnace in the vertical plane showing the position of the assembly of five slit burners fitted in the ignition hood thereof. Referring to Fig. 1, two tube-in-tube type conventional burners (1) are fixed on the side walls (2) of the ignition hood (3) having roof (4), at an inclination with the side walls. The flame of the burners is directed at the central part of the sinter bed (5) containing the raw material mix to be sintered. The mix across the width of the sinter bed is not uniformly ignited,the ignition being maximum at the central part and decreasing towards the side plates (6) of the bed. Localised fusion of the raw material takes place, affecting the heat permeability of the bed and also the quality of the sinter product. The size of the ignition hood (3) used with the conventional burners is relatively large, the typical dimensions being length 4.0 to 7.5m, width 2.5 to 4.0m and height 1.4 to 2.0mr. . The large dimensions of the hood cause an increased loss of heat in the hood and hence an increased consumption of fuel gases by the burners. The fuel gases i.e. coke oven gas plus mixed gas is supplied to the burners through line (7) and air through line (8). Referring to Figs. 2 to 8, the fuel gases i.e. coke oven gases is fed into the silt burner (9) through the vertically erected central tube(9), primary air through intermediate tube (10) and secondary air through outer tube (11). The central tube is provided with a nozzle Cl2) of preferred diameter 14mm extending to tip (13) of the burner. Sleeve (13A) (Fig. 5) of different sizes is fitted with the nozzle to control the velocity of fuel gases through the nozzle. A vane-type (14A) (Fig. 6)/ gear-type {14B) (Figs. 7 and 0) swirler is fitted at the burner tip, in between the nozzle and the intermediate tube, for imparting a swirling motion to the stream of primary air ejecting at the burner tip. The assembly (15) of five burners (Fig. 3) are put in a single burner block (16) {Figs. 2 and 4) in a manner such that the flames of all the five burners protrude in a single conical groove (17) (Figs. 2 and 4) of the block. The burner block is housed in a double walled rectangular shaped metallic box {18) (Figs. 2 and 3), having five pairs of slits (11A) (Fig. 3), one pair being for each burner (9) (Fig. 3), for supplying secondary air to the burners for controlling the shape of the flame produced. The vanes (14A) used for providing swirling motion to the primary air may be of different angles such as 30°, 45° and 60° (Fig. 6). The gear type swirler (14B) used may be of shape as shown in Figs. 7 and 8. Referring to Fig. 9, the assembly (15) of five slit burners (9) is mounted on the roof (4) of ignition hood (3) of the sintering furnace, having sinter bed (5) with side walls (6). Unlike the method of mounting the conventional burners on the side walls of the ignition hood at an inclination to the bed surface (Fig. 1), the assembly of slit burners is mounted on the roof of the ignition hood in a manner so that the curtain type flame of the burners is directed vertically downward onto the surface of the sinter bed (5), and ignites the entire width of the sinter bed uniformly and thereby improves the quality of the sinter product. With a view to checking the distribution of the flame temperature in the hood, a number of thermocouples re mounted in five rows (20) at different heights above the sinter bed. in exhaust pipe (21) is provided to remove the combustion products from inside the hood. The height of the hood is reduced for lowering the heat loss inside the hood. A stable and homogeneous flame (19) of curtain shape (Fig. k) and length 500 mm is produced, due to the supply of secondary air through five pairs of slits, by the assembly of five slit burners inside the hood of Fig. 9 to cause uniform ignition of the raw materiel mix across the entire width of the sinter bed. The invented burner is capable of operating under a turn down ratio of 1:10 and at an excess air ratio of as high as 3.0 (i.e. 200%), without affecting the stability of the flame produced. The quality of the sinter product improves and the consumption of fuel is lowered by using the invented slit burners in the hood of reduced height of the sintering plants. The comparative flaae characteristics of the conventional and invented burners are presented in Table I. Table I (Table Removed) We Claim : 1. A slit burner for use in sintering plants of steel industry, which is capable of producing a curtain-type flame of stable temperature at a reduced fuel consumption and being mounted in an assembly of a plurality of burners on the roof of the Ignition hood of sintering plants with of short length, increased turndown and excess air ratios, and two-stage combustion, is characterised in that the burner comprises a vertically erected central tube C9A) for supplying fuel gases, an intermediate tube (10) for supplying primary air and an outer tube (11) for supplying secondary air to the burner, the central tube terminating in a nozzle (12) which extends upto the burner tip (13) and is provided with a sleeve (13A) therein for controlling the flow of fuel gases therethrough, the space between the central tube and the intermediate tube being provided with a swirler (14A/14B) near the burner tip for imparting a swirling motion to the primary air flowing therethrough, and the spaee between the intermediate tube and the outer tube being provided with a pair of slits (HA), one on each laterial side of the burner tip, for allowing the secondary air to flow therethrough and control the shape of the flame (19) produced by the burner to be of curtain type, the burner tip being fitted into a burner block (16) which is housed in a double walled metallic box (18) and is provided with a tapered groove (17) expanding downwardly. The burner as claimed in claim 1, wherein the gap between the two lateral side walls of the metallic box, housing the burner block,is the said slit on each lateral side of the burner. 2. The burner as claimed in claim 1, wherein the swirler is of vane type (14A) having vanes of different angles such as 30°, 45° and 60°. A. The burner as claimed in claim 1, wherein the swirler (14B)is of gear type 5. The burner as claimed in claim 1, wherein the sleeve is provided with an outlet hole of different diameters, selected for controlling the velocity of fuel gases therethrough. 6. The burner as claimed in claim 1, wherein the central tube is provided with an internal bore of diameter 1A mm. 7. The burner as claimed in any of the preceding claims, which is suitable for being constructed as an assembly of five burners filled into a cotamon burner block, housed in a common double walled metallic box.

Full Text

The present invention relates to a slit burner for use in the sintering plants of steel industry.
The invention relates, more particularly, to an assembly of five slit burners each comprising a vertically erected central tube for supplying fuel gases; an intermediate tube for supplying primary air; an outer tube for secondary air; and a quarl or refractory block called burner block , common for all the five burners in the assembly, housed in a double walled metallic box with five pairs of slits in-between the two vertical lateral walls of the box, one pair being provided for each burner, for supplying the secondary air to control the shape of the flame produced by the burners.
The conventional burners used in sintering plants, such as turbulent burners, flat flame burners and tube-in-tube type burners have certain drawbacks, namely, instability of flame temperature, non-uniform ignition across the width of the sinter bed and increased fuel consumption. The flame produced is of relatively long bushy type, low turn down ratio, low excess air ratio and single stage corahustion. These are suitable for erection on the side walls of the ignition hood of sinter bed at an inclination to the sinter bed.
The objective of the present invention is to provide a slit burner of improved design and construction, which is capable of producing a flame Of stable temperature at a reduced energy consumption, and of short length, increased turn down and excess air ratios, and two-stage combustion.
The other objective is to provide a slit burner which can be mounted in an assembly on the roof of the ignition hood, perpendicular to the sinter bed.
The invention is described fully and particularly, without restricting its scope in any manner, with reference to the accompanying drawings, in which
Figure 1 is a sketch showing the section in the vertical plane of a conventional tube-in-tube type burner fitted in the wall of ignition hood of the sintering furnace;
Figure 2 is a view of an embodiment of the invented slit burner in the vertical plane;
Figure 3 is the plan view of the horizontal section at A-A in Figure 2;
Figure 4 is a schematic diagram of the burner block and shape of the flame produced in an assembly of slit burners;
Figure 5 is a sectional view of the gas nozzle sleeve of the slit burner;
Figure 6 is a sketch of vane swirlers of different angles used in the slit-buraer;
Figure 7 is the longitudinal section of the gear type swirler used in the slit burner;
Figure 8 is the cross section of the gear type swirler used in the slit burner; aad
Figure 9 is the sectional view of the sintering furnace in the vertical plane showing the position of the assembly of five slit burners fitted in the ignition hood thereof.
Referring to Fig. 1, two tube-in-tube type conventional burners (1) are fixed on the side walls (2) of the ignition hood (3) having roof (4), at an inclination with the side walls. The flame of the burners is directed at the central part of the sinter bed (5) containing the raw material mix to be sintered. The mix across the width of the sinter bed is not uniformly ignited,the ignition being maximum at the central part and decreasing towards the side plates (6) of the bed. Localised fusion of the raw material takes place, affecting the heat permeability of the bed and also the quality of the sinter product.
The size of the ignition hood (3) used with the conventional burners is relatively large, the typical dimensions being length 4.0 to 7.5m, width 2.5 to 4.0m and height 1.4 to 2.0mr. . The large dimensions of the hood cause an increased loss of heat in the hood and hence an increased consumption of fuel gases by the burners. The fuel gases i.e. coke oven gas plus mixed gas is supplied to the burners through line (7) and air through line (8).
Referring to Figs. 2 to 8, the fuel gases i.e. coke oven gases is fed into the silt burner (9) through the vertically erected central tube(9), primary air through intermediate tube (10) and secondary air through outer tube (11). The central tube is provided with a nozzle Cl2) of preferred diameter 14mm extending to tip (13) of the burner. Sleeve (13A) (Fig. 5) of different sizes is fitted with the nozzle to control the velocity of fuel gases through the nozzle. A vane-type (14A) (Fig. 6)/ gear-type {14B) (Figs. 7 and 0) swirler is fitted at the burner
tip, in between the nozzle and the intermediate tube, for imparting a swirling motion to the stream of primary air ejecting at the burner tip. The assembly (15) of five burners (Fig. 3) are put in a single burner block (16) {Figs. 2 and 4) in a manner such that the flames of all the five burners protrude in a single conical groove (17) (Figs. 2 and 4) of the block. The burner block is housed in a double walled rectangular shaped metallic box {18) (Figs. 2 and 3), having five pairs of slits (11A) (Fig. 3), one pair being for each burner (9) (Fig. 3), for supplying secondary air to the burners for controlling the shape of the flame produced. The vanes (14A) used for providing swirling motion to the primary air may be of different angles such as 30°, 45° and 60° (Fig. 6). The gear type swirler (14B) used may be of shape as shown in Figs. 7 and 8.
Referring to Fig. 9, the assembly (15) of five slit burners (9) is mounted on the roof (4) of ignition hood (3) of the sintering furnace, having sinter bed (5) with side walls (6). Unlike the method of mounting the conventional burners on the side walls of the ignition hood at an inclination to the bed surface (Fig. 1), the assembly of slit burners is mounted on the roof of the ignition hood in a manner so that the curtain type flame of the burners is directed vertically downward onto the surface of the sinter bed (5), and ignites the entire width of the sinter bed uniformly and thereby improves the quality of the sinter product. With a view to checking the distribution of the flame temperature in the hood, a number of thermocouples
re mounted in five rows (20) at different heights above the sinter bed. in exhaust pipe (21) is provided to remove the combustion products from inside the hood. The height of the hood is reduced for lowering the heat loss inside the hood.
A stable and homogeneous flame (19) of curtain shape (Fig. k) and length 500 mm is produced, due to the supply of secondary air through five pairs of slits, by the assembly of five slit burners inside the hood of Fig. 9 to cause uniform ignition of the raw materiel mix across the entire width of the sinter bed.
The invented burner is capable of operating under a turn down ratio of 1:10 and at an excess air ratio of as high as 3.0 (i.e. 200%), without affecting the stability of the flame produced.
The quality of the sinter product improves and the consumption of fuel is lowered by using the invented slit burners in the hood of reduced height of the sintering plants.
The comparative flaae characteristics of the conventional and invented burners are presented in Table I.
Table I
(Table Removed)

We Claim :
1. A slit burner for use in sintering plants of steel industry, which is capable of producing a curtain-type flame of stable temperature at a reduced fuel consumption and being mounted in an assembly of a plurality of burners on the roof of the Ignition hood of sintering plants with of short length, increased turndown and excess air ratios, and two-stage combustion, is characterised in that the burner comprises a vertically erected central tube C9A) for supplying fuel gases, an intermediate tube (10) for supplying primary air and an outer tube (11) for supplying secondary air to the burner, the central tube terminating in a nozzle (12) which extends upto the burner tip (13) and is provided with a sleeve (13A) therein for controlling the flow of fuel gases therethrough, the space between the central tube and the intermediate tube being provided with a swirler (14A/14B) near the burner tip for imparting a swirling motion to the primary air flowing therethrough, and the spaee between the intermediate tube and the outer tube being provided with a pair of slits (HA), one on each laterial side of the burner tip, for allowing the secondary air to flow therethrough and control the shape of the flame (19) produced by the burner to be of curtain type, the burner tip being fitted into a burner block (16) which is housed in a double walled metallic box (18) and is provided with a tapered groove (17) expanding downwardly.
The burner as claimed in claim 1, wherein the gap between the two lateral side walls of the metallic box, housing the burner block,is the said slit on each lateral side of the burner.
2. The burner as claimed in claim 1, wherein the swirler is of vane type (14A) having vanes of different angles such as 30°, 45° and 60°.
A. The burner as claimed in claim 1, wherein the swirler (14B)is of gear type
5. The burner as claimed in claim 1, wherein the sleeve is provided with an outlet hole of different diameters, selected for controlling the velocity of fuel gases therethrough.
6. The burner as claimed in claim 1, wherein the central tube is provided with an internal bore of diameter 1A mm.
7. The burner as claimed in any of the preceding claims, which is suitable for being constructed as an assembly of five burners filled into a cotamon burner block, housed in a common double walled metallic box.

Documents:

2-del-1997-abstract.pdf

2-del-1997-claims.pdf

2-del-1997-complete specification (granted).pdf

2-DEL-1997-Correspondence-Others-(28-05-2010).pdf

2-del-1997-correspondence-others.pdf

2-del-1997-correspondence-po.pdf

2-del-1997-description (complete).pdf

2-del-1997-drawings.pdf

2-del-1997-form-1.pdf

2-del-1997-form-19.pdf

2-del-1997-form-2.pdf

2-del-1997-form-3.pdf

2-del-1997-gpa.pdf

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Patent Number

241206

Indian Patent Application Number

2/DEL/1997

PG Journal Number

27/2010

Publication Date

02-Jul-2010

Grant Date

23-Jun-2010

Date of Filing

01-Jan-1997

Name of Patentee

STEEL AUTHORITY OF INDIA LTD.,RESEARCH & DEVELOPMENT CENTRE

Applicant Address

IRON & STEEL ENTERPRISE, ISPAT BHAWAN,LODI ROAD, NEW DELHI-110003,INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	PRABHAT KUMAR	RDCID/SAIL, P.O. DORANDA, RANCHI-834002, INDIA.
2	INDRANATH PRASAD GUPTA	RDCID/SAIL, P.O. DORANDA, RANCHI-834002, INDIA.
3	MUKESH KUMAR BAJPAI	RDCID/SAIL, P.O. DORANDA, RANCHI-834002, INDIA.
4	THODIMI SREENIVASA REDDY	RDCID/SAIL, P.O. DORANDA, RANCHI-834002, INDIA.
5	PREM KUMAR TRIPATHI	RDCID/SAIL, P.O. DORANDA, RANCHI-834002, INDIA.

PCT International Classification Number

F23J 15/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA