COOLING SHIELD FOR A LIQUOR INJECTION PIPE OF A LIQUOR GUN, LIQUOR GUN SYSTEM COMPRISING THE COOLING SHIELD, AND METHOD FOR COOLING A LIQUOR INJECTION PIPE IN A LIQUOR GUN SYSTEM

Abstract

A cooling shield for a liquor injection pipe of a liquor gun for supplying liquor to a combustion chamber of a recovery boiler, which has a first and a second side edge, the side edges extending in a longitudinal direction (L) of the cooling shield, and a first end edge and a second end edge extending between the side edges, the cooling shield comprising an outside shield wall, and an inside shield wall, the outside shield wall and the inside shield wall being connected along the side edges of the cooling shield, the cooling shield comprising a cooling medium space being arranged between the outside shield wall and the inside shield wall, the cooling shield comprising a cooling medium inlet and a cooling medium outlet the cooling medium inlet and the cooling medium outlet being arranged in communication with the cooling medium space.

Claims

1-16. (canceled)

17. A cooling shield for a liquor injection pipe of a liquor gun for supplying liquor to a combustion chamber of a recovery boiler, wherein the cooling shield has a first and a second side edge, the side edges extending in a longitudinal direction (L) of the cooling shield, and a first end edge and a second end edge extending between the side edges, the cooling shield comprising an outside shield wall, and an inside shield wall, the outside shield wall and the inside shield wall being connected along the side edges of the cooling shield, the cooling shield comprising a cooling medium space being arranged between the outside shield wall and the inside shield wall, the cooling shield comprising a cooling medium inlet and a cooling medium outlet the cooling medium inlet and the cooling medium outlet being arranged in communication with the cooling medium space, the cooling medium outlet comprising a plurality of openings or pores in the outside shield wall.

18. A cooling shield according to claim 17, wherein the outside shield wall is formed from a first plate and the inside shield wall is formed from a second plate.

19. A cooling shield according to claim 17, wherein the cooling shield is adapted to be mounted in a combustion chamber as a part separate from a liquor gun.

20. A cooling shield according to claim 17, wherein the cooling shield forms an integral part of a liquor gun.

21. A cooling shield according to claim 17, wherein the outside shield wall is curved.

22. A cooling shield according to claim 21, wherein the inside shield wall is curved.

23. A cooling shield according to claim 22, wherein the cooling shield extends in a circumferential direction of the cooling shield over a circle segment of from 60° to 300°.

24. A cooling shield according to claim 17, wherein the outside shield wall is connected to the inside shield wall by a first side wall extending along the first side edge of the cooling shield and by a second side wall extending along the second side edge of the cooling shield.

25. A cooling shield according to claim 17, wherein the outside shield wall is connected to the inside shield wall along the second end edge of the cooling shield and optionally wherein the outside shield wall is connected to the inside shield wall along the first end edge of the cooling shield.

26. A liquor gun system comprising a liquor gun and the cooling shield according to claim 17, the liquor gun comprising a liquor injection pipe for supplying liquor to a combustion chamber of a recovery boiler, the liquor injection pipe comprising a nozzle arranged at a combustion chamber end of the liquor injection pipe, the combustion chamber end of the liquor injection pipe being configured for being inserted into the combustion chamber of the recovery boiler, the nozzle being arranged for ejecting liquor into the combustion chamber of the recovery boiler, wherein the cooling shield is configured for being applied at least at the combustion chamber end of the of the liquor injection pipe, and to cover at least a portion of the length of an upper outer surface of the liquor injection pipe, with the inside shield wall of the cooling shield facing the liquor injection pipe and with the outside shield wall of the cooling shield facing away from the liquor injection pipe.

27. A liquor gun system according to claim 26, wherein the width (w) of the cooling shield is equal to or greater than a width of the combustion chamber end of the liquor injection pipe.

28. A liquor gun system according to claim 26, wherein a circumferential extension of the cooling shield around the liquor injection pipe is from 60° to 300°.

29. A liquor gun system according to claim 26, wherein a longitudinal extension of the combustion chamber end of the cooling shield along the upper outer surface of the liquor injection pipe is from 70% to 115% of a length of the combustion chamber end of the liquor injection pipe.

30. A method for cooling and shielding a liquor injection pipe in a liquor gun system according to claim 26, wherein the liquor gun system is mounted with the combustion chamber end of the liquor injection pipe and the cooling shield being inserted into a combustion chamber of a recovery boiler, the method comprising supplying a cooling medium comprising water and a gaseous transport medium to the cooling space in the cooling shield.

31. A method according to claim 30, wherein the water and the gaseous transport medium are supplied to the cooling space as a pre-formed mixture or as separate components.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The cooling shield as disclosed herein will be further explained hereinafter with reference to the appended drawings wherein:

[0059] FIG. 1 shows a cooling shield for a liquor gun;

[0060] FIG. 2 shows a first example of a cross-section through a cooling shield for a liquor gun;

[0061] FIG. 3 shows a second example of a cross-section through a cooling shield for a liquor gun;

[0062] FIG. 4 shows a third example of a cross-section through a cooling shield for a liquor gun;

[0063] FIG. 5 shows a fourth example of a cross-section through a cooling shield for a liquor gun; and

[0064] FIG. 6 shows a liquor gun system as disclosed herein.

DETAILED DESCRIPTION

[0065] Different aspects of the present disclosure will be described more fully hereinafter with reference to the drawings. The cooling shield, the system and the method disclosed herein should not be construed as being limited to the aspects set forth herein but can be varied within the scope of the appended claims. In particular, it is to be understood that the exemplary shapes of the cooling shields shown in the Figures may be freely varied within the scope of the claims.

[0066] The drawings are schematic and are not necessarily drawn to scale.

[0067] FIG. 1 shows a cooling shield 1 for a liquor injection pipe of a liquor gun for supplying liquor to a combustion chamber of a recovery boiler. The cooling shield 1 is shown in a highly simplified and shortened manner, having the form of a straight tubular structure with an open underside. As disclosed herein, the cooling shields of the invention may have any useful shape in the longitudinal direction and may be configured to conform to a bent shape of a liquor injection pipe of a liquor gun. Furthermore, it is to be understood that also the cross-sectional shape of the cooling shield may be different from that shown in FIG. 1, as disclosed herein.

[0068] The cooling shield 1 has a first side edge 3 and a second side edge 4, the side edges 3, 4 extending in a longitudinal direction L of the cooling shield 1. A first end edge 5 extends between the side edges 3,4 at a first end 7 of the cooling shield 1 and a second end edge 6 extend between the side edges 3, 4 at a second end 8 of the cooling shield 1. When the cooling shield is used to cool, clean and protect a liquor gun inside a combustion chamber of a recovery boiler, the first end 7 is an outer end of the cooling shield 1 which is located outside the combustion chamber of the recovery boiler and the second end 8 of the cooling shield 1 is an inner end or combustion chamber end which is located in the interior of the combustion chamber and protrudes from the combustion chamber wall a distance into the combustion chamber.

[0069] The cooling shield 1 has an outside shield wall 11 formed from a first steel plate, and an inside shield wall 12 formed from a second steel plate. The outside shield wall 11, has an outer surface 11′ facing away from the inside shield wall 12 and an inner surface 11″ facing the inside shield wall 12. The inside shield wall 12, has an outer surface 12′ facing away from the outside shield wall 11 and an inner surface 12″ facing the outside shield wall 11. The outside shield wall 11 and the inside shield wall are connected by side walls 13, 14 extending along the side edges 3, 4, of the cooling shield 1. The provision of side walls for connecting the outside and inside shield walls 11, 12 is optional to the cooling shields as disclosed herein. The side walls may be directly connected to each other in the manner shown in FIGS. 3 and 4.

[0070] The outside shield wall 11 and the inside shield wall 12 are placed at a distance from each other such that a cooling medium space 15 is formed between the inner surface 11″ of the outside shield wall 11 and the inner surface 12″ of the inside shield wall 12. In the cooling shield 1 shown in FIG. 1, the thickness t of the cooling shield 1, as measured in a radial direction R from the outer surface 11′ of the outside shield wall 11 is uniform over the full cross-section of the cooling shield 1 from the first side edge 3 to the second side edge 4. In a variation of the FIG. 1 cooling shield 1, the outside shield wall 11 may be directly connected to the inside shield wall 12 along the first and second side edges 3, 4. In such case, a cross section through the cooling shield 1 will show the cooling medium space 15 with a shape that tapers towards the side edges 3,4.

[0071] The cooling shield 1 is shown with two cooling medium inlets 16′, 16″ arranged at the first end 7 of the cooling shield 1. When the cooling shield is mounted to a recovery boiler with the second end 8 protruding into the combustion chamber of the recovery boiler, the cooling medium inlets 16′, 16″ will generally be on the outside of the combustion chamber wall as is the case with the cooling shield 1 shown in FIG. 6. However, it is conceivable to alternatively or in addition thereto arrange one or more cooling medium inlets on the part of the cooling shield which is inserted into the combustion chamber. The cooling medium space 15 of the cooling shield 1 in FIG. 1 is closed at the first end 7 with a first end wall 18 and is closed at the second end 8 with a second end wall 19. The first and second end walls are optional to the cooling shields as disclosed herein. The outside shield wall 11 and the inside shield wall 12 may be directly coupled to each other. Furthermore, one wall or both of the end walls can be omitted. An open first end may serve as a cooling medium inlet. It is preferred that the second end 8 is a closed end to provide adequate circulation of cooling medium in the cooling medium space 15. Furthermore, it is to be understood that the number of cooling medium inlets may be only one or more than two, as set out herein. It is also to be understood that the one or more cooling medium inlets may be differently placed on the cooling shield.

[0072] A plurality of cooling medium outlets 17 are arranged in the outside shield wall 11 of the cooling shield 1. The cooling medium outlets 17 may be evenly distributed over the full outer surface 11′ of the outside shield wall 11 in the combustion chamber end 8 of the cooling shield 1, as shown in FIG. 1 or in any other suitable manner, as disclosed herein. The cooling medium outlets 17 are arranged at the second end 8 constituting the combustion chamber end 8 of the cooling shield 1. The cooling medium outlets 17 are in communication with the cooling medium space 15 and are arranged to pass gaseous cooling medium and small amounts of water out from the cooling medium space 15 to the surroundings of the cooling shield 1 inside the combustion chamber of a recovery boiler when the cooling shield 1 is being used. The gaseous cooling medium which is let out through the cooling medium outlets 17 will generally be a mixture of a gaseous transport medium, vaporized water and a small amount of non-vaporized water. The part of the cooling shield 1 in FIG. 1 which is directed upward in the figure is also the part of the cooling shield 1 which will be directed upward in a combustion chamber of a recovery boiler when the cooling shield is being used. It is to be understood that the arrangement of cooling medium outlets may be different from that shown in FIG. 1. The number of cooling medium outlets may be greater or smaller, their distribution may be different and they may have other shapes than the circular shape shown in FIG. 1, such as a slit shape. Circular openings may have a diameter in the order of from 0.5 mm to 5 mm. Elongated, slit-shaped openings may have a width in the order of from 0.2 mm to 1.5 mm and a length in the order of from 2 mm to 20 mm.

[0073] As set out herein, the cooling medium outlets 17 may comprise or consist of a plurality of pores in the outside shield wall 11. Such pores are generally provided by the outside shield wall 11 being made by an inherently porous material. A porous material may have additional cooling medium outlets 17 formed therein, e.g., to create a higher outflow of spent cooling medium in selected portions of the cooling shield.

[0074] As set out herein, the cooling shield 1 may be adapted to be removably mounted to a liquor gun as a separate part or may form an integral part of a liquor gun.

[0075] FIGS. 2 to 5 show examples of cooling shields 1 having different cross-sectional shape. The same reference numbers have been used to denote the same components of the cooling shields 1 of FIGS. 2 to 5. It is to be understood that features of the different cross-sections may be freely combined with each other. In particular, the outside and inside shield walls 11, 12 may be directly connected to each other along the side edges 3, 4 or may be connected by means of side walls 13, 14. When the outside and inside shield walls 11, 12 are directly connected to each other the cross-sectional shape of the cooling space 15 will be tapering towards the side edges 3, 4 as illustrated by FIGS. 3 and 4. By way of example, the FIGS. 1 and 5 cooling shields 1 may be modified by directly connecting the outside shield wall 11 to the inside shield wall 12 along the first and second side edges 3,4, resulting in a cooling shield 1 having a smaller thickness adjacent the side edges 3, 4 then centrally between the side edges 3, 4.

[0076] When both the outside shield wall 11 and the inside shield wall 12 are curved as shown in FIGS. 2 and 4, the thickness of the cooling shield 1 is measured from the outer surface 11′ of the outside shield wall 11 to the outer surface 12′ of the inside shield wall 12, in the radial direction R of the outer surface 11′ of the outside shield wall 11.

[0077] When the inside shield wall 12 is planar, the thickness of the cooling shield is measured perpendicular to the plane of the inside shield wall 12 from the outer surface 11′ of the outside shield wall 11 to the outer surface 12′ of the inside shield wall 12. This is illustrated in FIGS. 3 and 5.

[0078] No cooling medium inlets or cooling medium outlets are shown in FIGS. 3-5. Such inlets and outlets may be arranged in any suitable manner as described herein, e.g., as shown in FIG. 1. Furthermore, the cooling shields 1 shown in FIGS. 2-5 may may be open at one or both ends. However, it is generally preferred that at least the second end which is configured for being arranged in the interior of a combustion chamber is a closed end, such that cooling medium can only exit from the cooling medium space 15 through the cooling medium outlets 17 arranged in the cooling shield 1.

[0079] FIG. 2 shows a cross section through a cooling shield 1 of the type shown in FIG. 1, where the outside and inside shield walls 11, 12 provide the cooling shield 1 with a uniform curvature, the radius of curvature of the outside shield wall 11 being larger than the radius of curvature of the inside shield wall 12 and the distance between the inner surface 11″ of the outside shield wall 11 an the inner surface 12″ of the inside shield wall 12 being the same all the way from the first side edge 3 to the second side edge 4 of the cooling shield 1. The cooling shield 1 in FIGS. 1 and 2 may be described as having a tubular shape with a gap 20 in the tube wall extending in the longitudinal direction of the cooling shield 1 between the first and second side edges 3, 4. As set out herein, the gap 20 may be larger or smaller than the gap shown in FIGS. 1 and 2. When the cooling shield 1 shown in FIGS. 1 and 2 is in use and is applied to cool and protect a liquor injection pipe of a liquor gun, as shown in FIG. 6, the cooling shield will cover and protect the upper part of the liquor injection pipe, as well as providing at least partial protection to the sides of the liquor injection pipe. The width of a cooling shield 1 as shown in FIGS. 1 and 2 is determined as the maximum width w, as measured in the width direction W between diametrically opposite points on the outer surface 11′ of the outside shield wall 11. The cooling shield 1 in FIGS. 1 and 2 is sized such that a liquor injection pipe 21 of a liquor gun may be inserted into the cavity 22 defined by the outer surface 11′ of the outside shield wall 11 such that the cooling shield 1 partially surrounds the liquor injection pipe 21 as illustrated by FIG. 6. The cross-section of a curved cooling shield such as the curved cooling shields 1 shown in FIGS. 1, 2 and 6 preferably occupies a circle segment which is large enough to allow a full width of a liquor injection pipe 21 to be covered. More preferably, the cooling shield 1 curves downward to at least partly cover also at the sides of the liquor injection pipe 21. As set out herein, a cooling, cleaning and protecting effect may be achieved also with a relatively narrow cooling shield which covers only the uppermost part of the liquor gun. However, a cooling shield 1 which is arranged above a liquor injection pipe 21 in a combustion chamber of a recovery boiler preferably has a width which is at least as large as the width of the liquor injection pipe 21. As set out herein, a circumferential extension of the cooling shield 1 around a liquor injection pipe 21 may be from 60° to 300°.

[0080] In all instances, the cooling shield as disclosed herein does not fully cover the lower part of the liquor injection pipe 21.

[0081] The cooling shields shown in FIGS. 3 and 4 have a curved outside wall 11. The provision of a curved outside wall may be beneficial in that solid matter which impinges on the shield may slide off the shield.

[0082] FIG. 6 shows a liquor gun system 100 comprising a liquor gun 30 and a cooling shield 1 as disclosed herein. The liquor gun system is shown when applied inside a combustion chamber 34 of a recovery boiler with a combustion chamber end of a liquor injection pipe 21 of the liquor gun 30 and a combustion chamber end 8 of the cooling shield 1 protruding from an opening 40 in the combustion chamber wall 35 into the combustion chamber 34. The liquor injection pipe 21 is arranged for supplying liquor to the combustion chamber 34 and comprises a nozzle 38 arranged at a combustion chamber end of the liquor injection pipe 21, the nozzle 38 being arranged for ejecting liquor into the combustion chamber 34 of the recovery boiler. The cooling shield 1 is applied at the upper outer surface 39 and on the sides of the liquor injection pipe 21, at a distance from the upper outer surface 39 of the liquor injection pipe 21, with the inside shield wall 12 of the cooling shield 1 facing the liquor injection pipe 21 and with the outside shield wall 11 of the cooling shield facing away from the liquor injection pipe 21. The cooling medium inlets 16′, 16″ are shown to be arranged on the first end 7 of the cooling shield 1 which is located on the outside of the combustion chamber 34.

[0083] The longitudinal extension of the combustion chamber end of the cooling shield 1 when applied to a liquor gun 30 as shown in FIG. 6 may be from 70% to 115% of the length of the combustion chamber end of the liquor injection pipe 21, i.e. of the length of the part of the liquor injection pipe 21 which is inserted into the combustion chamber 34.

[0084] When the liquor gun system 100 is applied inside a combustion chamber 34 of a recovery boiler as shown in FIG. 6, the cooling shield 1 may be used to cool the liquor injection pipe 21 of the liquor gun 30 by supplying a cooling medium comprising water and a transport medium to the cooling space 15 in the cooling shield 1. In addition to providing cooling of the liquor injection pipe 21, the spent cooling medium which exits through the cooling medium outlets, serves to reduce the amount of matter in the space around the liquor injection pipe 21, thus preventing deposits forming on the cooling shield and on parts of the liquor injection pipe which are not covered by the cooling shield. As set out herein, the water and a gaseous transport medium may be supplied to the cooling space 15 as a pre-mixed emulsion or as separate cooling medium components.