TOP COMBUSTION STOVE

Abstract

A burner assembly for top combustion hot blast stove including a burner surrounded by a burner shell, where the burner has a circular cross-section; a number of air nozzles arranged for tangentially feeding air to the burner, the air nozzles being connected to one or more air distribution chambers; a number of gas nozzles arranged for tangentially feeding gas to the burner, the gas nozzles being connected to one or more gas distribution chambers; wherein the air nozzles are arranged in one or more inclined or vertical stacked arrays of air nozzles, each inclined or vertical stacked array being in connection with one inclined or vertical air distribution chamber; the gas nozzles are arranged in one or more inclined or vertical stacked arrays of gas nozzles, each inclined or vertical stacked array being in connection with one inclined or vertical gas distribution chamber; and the inclined or vertical air distribution chamber(s) and the inclined or vertical gas distribution chamber(s) are arranged along the circumference of the burner shell.

Claims

1. A burner assembly for top combustion hot blast stove comprising a burner surrounded by a burner shell, wherein said burner has a circular cross-section; a number of air nozzles arranged for tangentially feeding air to the burner, the air nozzles being connected to one or more air distribution chambers; a number of gas nozzles arranged for tangentially feeding gas to the burner, the gas nozzles being connected to one or more gas distribution chambers; wherein the air nozzles are arranged in one or more inclined or vertical stacked arrays of air nozzles, each inclined or vertical stacked array being in connection with one inclined or vertical air distribution chamber; wherein the gas nozzles are arranged in one or more inclined or vertical stacked arrays of gas nozzles, each inclined or vertical stacked array being in connection with one inclined or vertical gas distribution chamber; and wherein the inclined or vertical air distribution chamber(s) and the inclined or vertical gas distribution chamber(s) are distributed along the circumference of the burner shell.

2. The burner assembly as claimed in claim 1, wherein the inclined or vertical air and gas distribution chambers are arranged within the burner shell.

3. The burner assembly as claimed in claim 1, wherein the number of nozzles per stacked array is between 2 and 20.

4. The burner assembly as claimed in claim 1, wherein the inclined stacked arrays are inclined at an angle up to 60? relative to a vertical axis of the burner.

5. The burner assembly as claimed in claim 1, further comprising a frustoconical secondary combustion chamber surrounded by a cone shell and arranged below the burner.

6. The burner assembly as claimed in claim 5, wherein the burner is detachably affixed to the cone shell of the frustoconical secondary combustion chamber by a flange assembly.

7. The burner assembly as claimed in claim 5, wherein the aperture angle of the frustoconical secondary combustion chamber is between 50? and 70?.

8. The burner assembly as claimed in claim 5, wherein the height of the frustoconical section will be chosen to be 0.3 to 5 times the height of the primary combustion chamber.

9. The burner assembly as claimed in claim 1, comprising two or more air distribution chambers and two or more gas distribution chambers, further comprising a manifold type air feeding pipes and gas feeding pipes arranged outside the burner shell and fluidly connecting the air and gas distribution chambers to air and gas supply, respectively.

10. A top combustion hot blast stove comprising a stove shell; a volume of checker bricks arranged within said stove shell; and a burner assembly as claimed in claim 1, wherein said burner is axially arranged in an upper section of the stove shell.

11. The hot blast stove as claimed in claim 10, further comprising a circulation zone above the volume of checker bricks.

12. The hot blast stove as claimed in claim 10, further comprising a hot blast downpipe within the stove shell.

13. The burner assembly as claimed in claim 1, configured to refurbish renovate or upgrade an existing hot blast stove.

14. A method for refurbishing, renovating or upgrading an existing hot blast stove with an existing burner assembly, the method comprising the steps of removing the existing burner assembly from said hot blast stove and mounting a burner assembly as claimed in claim 1 to said hot blast stove.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] A preferred embodiment of the disclosure will now be described, by way of example, with reference to the accompanying drawings in which:

[0022] FIG. 1 is a cross sectional view of an upper part of a hot blast stove equipped with a preferred embodiment of a burner assembly according to the disclosure; and

[0023] FIG. 2 is a partial cross sectional top view of a preferred embodiment of a burner assembly according to the disclosure.

[0024] Further details and advantages of the present disclosure will be apparent from the following detailed description of several not limiting embodiments with reference to the attached drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0025] FIG. 1 shows a cross-section of the upper part of a preferred embodiment of an apparatus for heating air for the operation of regenerators (hot blast stoves) for blast furnaces.

[0026] The burner 10 has a burner shell 11 of circular cross-section and is axially mounted by flange assembly 111 in the upper section of the hot blast stove 1 which comprises a stove shell 2 with a main volume of regenerative checker bricks 40 for storing and exchanging heat and a circulation zone or headroom 30 without checker bricks.

[0027] The burner (or combustion chamber) 10 is closed on top by dome 140 and has separate feeding arrangements for the combustion media air 12 and gas 13. The feeding arrangements include air and gas feeding pipes 125, 135 and air and gas connecting pipes 123, 124, 133, 134 connecting the feeding pipes to the vertical air and gas distribution chambers 121, 122, 131, 132, respectively. Air and gas are fed to the burner 10 through a number of alternating vertical arrays of air nozzles 120 and gas nozzles 130. The number of vertical nozzle arrays can be two or more (four arrays are shown in FIGS. 1 and 2) and mainly depends on the size (diameter) of the burner. The number of nozzles within one array generally is between 2 and 10 or more (five nozzles are shown in each array in FIG. 1)

[0028] As can be seen in particular in FIG. 2, the vertical air and gas distribution chambers 121, 122, 131, 132 not only allow to feed arrays having a high number of stacked nozzles (and thus a burner with a significant height), but more importantly they leave enough room for the supporting wall structure of the burner shell 11. There is no fluidic horizontal connection between distribution chambers within the burner shell, which would weaken the burner shell structure, each vertical distribution chamber being separate from the adjacent distribution chambers even if two adjacent distribution chambers convey the same combustion medium. Indeed prior solution are based on ring distribution of the combustion media, which not only require a huge number of differently shaped bricks to be assembled as a burner shell, but also result in poor overall constructional stability.

[0029] Alternatively, the air and gas distribution chambers 121, 122, 131, 132 could also be inclined relative to the vertical axis of the burner, each distribution chamber thereby forming a section of a helix. The cross-section shown in FIG. 2 could also be a section through such an inclined distribution chamber configuration with alternating gas-air chambers. In FIG. 1, an inclined configuration would generally (but not necessarily) have the nozzles 120, 130 stacked at the same inclination angle than that of the distribution chambers.

[0030] The nozzles 120, 130 are arranged so that a substantially tangential inlet of the combustion media takes place in the burner 10. This tangential inlet in the burner can be effected by orientating the entire nozzle at an angle within burner shell 11 (such as shown in FIG. 2) or by providing only the outlet part of the nozzle with an appropriate design. The distribution of the alternating air and gas nozzle arrays on the circumference and the number of nozzles 120, 130 in each array over the height of the burner are adjustable to the size of the plant. More importantly, the alternation of tangential gas and air injection in the burner creates a swirl flow of alternating layers of combustion media which is advantageous for the mixing and combustion within the combustion chamber of the burner.

[0031] The burner geometry and the nozzle arrangement of the present disclosure are thus designed so that a high velocity swirl flow is produced within the combustion chamber in both axial and tangential directions.

[0032] In a particularly preferred embodiment, this burner 10 is combined with a conical (in fact frustoconical) secondary burner 20 which serves as an extended combustion chamber to burner 10 as well as a distribution device for the generated flue gases over the checker bricks 40. In fact, due to the frustoconical shape of the secondary combustion chamber the swirl flow generated within burner 10 widens as it flows down along the cone shell 21 thereby generating an axial inner (partial) backflow towards the burner 10. The intensive backflow of hot flue gases from the conical secondary combustion chamber 20 to burner 10 has not only the effect of further mixing the combustion media, but it also heats up the incoming combustion media, thereby increasing their ignition potential.

[0033] Although the combustion media are generally burned off before leaving the burner 10, the swirl flow within the secondary combustion chamber 20 contributes to complete the burn off if necessary, especially during start up of the combustion stage.