An arrangement and a method for connecting a spraying nozzle to a liquor gun of a recovery boiler and a liquor gun

Abstract

The invention relates to an arrangement (10) for connecting a spraying nozzle (11) to a liquor gun of a recovery boiler. The arrangement (10) comprises a support frame (13) that holds a black liquor feeding duct (12) at the liquor gun such that the spraying nozzle (11) can be connected to the outlet end (12a) of the black liquor feeding duct (12) by squeezing a first end (11a) of the spraying nozzle (11) against the outlet end (12a) of the black liquor feeding duct (12) and thereby 10 allowing black liquor to flow from the black liquor feeding duct (12) into the spraying nozzle (11). In the arrangement according to the invention squeezer (16) is an actuator operated squeezer being arranged to squeeze the first end (11a) of the spraying nozzle (11) against the outlet end (12a) of the black liquor feeding duct (12) through a first connecting element (14) at the outer end (12a) of the black liquor feeding duct (12) and a second connecting element (15) at the first end of the spraying nozzle (11). The invention relates also to a liquor gun and a method for connecting a spraying nozzle (11) to a liquor gun.

Description

[0001] AN ARRANGEMENT AND A METHOD FOR CONNECTING A SPRAYING NOZZLE TO A LIQUOR GUN OF A RECOVERY BOILER AND A LIQUOR GUN

[0002] Field of the invention

[0003] The invention relates to an arrangement and a method for connecting a spraying nozzle to a liquor gun of a recovery boiler and a liquor gun.

[0004] Background of the invention

[0005] In modern pulp mills the used cooking chemicals are recovered. After washing the pulp, the obtained black liquor is evaporated and used as a fuel in a recovery boiler for producing steam for electricity generation in the mill. Burning the black liquor in a recovery boiler is carried out in reducing atmosphere at a furnace of the recovery boiler where the fire bed has approximately 1000°C temperature. In feeding the black liquor into the furnace, several liquor guns (usually 3 to 7) having spraying nozzles designed to spread the flow of black liquor into droplets of suitable size are typically used.

[0006] Over the time more and more black liquor gets burnt and stuck adjacent to mouths of the spraying nozzles and distributing plates connected thereto. Above all, the material tends to stick on the side edges and undersides of the distributing plate of the spraying nozzle and thereby forming successively growing scale depositions on these surfaces. Such accumulating scale influences on the spreading of the black liquor in a manner gradually deteriorating the combustion process in the furnace. Thus, the black liquor guns need to be maintained by cleaning and / or replacing their spraying nozzles periodically. Many known recovery boiler plants include automatic spraying nozzle cleaning devices in connection with arrangements for moving and positioning the liquor gun. However, these devices only extend the service life of the spraying nozzles limitedly among others because usually they have mere mechanical cleaning means which typically have been designed to scrape only the most critical areas at the external surfaces of the spraying nozzle. Therefore, the spraying nozzles need to be finally replaced by new or fully serviced ones.

[0007] When replacing a spraying nozzle, the liquor gun must be retracted such that the spraying nozzle is fed out from the furnace through the respective liquor spraying opening at the recovery boiler wall. Then the spraying nozzle is detached from its attachment at the liquor gun (most typically the current spraying nozzle has threads by means of which it has been screwed to the respective threads at the outlet end of the black liquor feeding duct at the liquor gun). Thus, in current recovery boiler plants spraying nozzle replacement is still carried out manually. However, in some most modern recovery boiler plants also automated or robotized nozzle change systems (such as it is described e.g., in FI126366) may have been applied. Regardless of the method of the replacement the used spraying nozzle must be detached from its attachment and the new one must be attached. However, because of the harsh conditions at recovery boiler also the portions of the liquor gun and the spraying nozzle at their connection region are suffering the effects of the burnt black liquor. Thus, it may sometimes occur that the spraying nozzle has got stuck at the liquor gun which naturally may cause interruptions to the liquor spraying process due to such issues and hence negative effects on production rate, and in worst cases, to the quality of the recovered cooking chemicals. It is also very hazardous to the operators to work long periods for solving such problems at the liquor gun area where they expose hot smelt splashes from the recovery boiler furnace. Therefore, it would be extremely beneficial if the spraying nozzle changes could be accomplished without above-described troubles with their detachment and / or attachment, as quickly as possible.

[0008] Summary of the invention

[0009] The object of the invention is to achieve an arrangement and method by means of which replacement of the black liquor spraying nozzles of a recovery boiler can be carried out, in general, safer and quicker than by using the known methods and by means of which the spraying nozzle replacements can be accomplished manually or with an automated spraying nozzle change systems with remarkably smaller probability of assembly complications typically caused by the scale formed by the burnt black liquor. The aim of the invention is also to bring forth a liquor gun wherein the spraying nozzle is attached by the arrangement according to the invention.

[0010] The object of the invention is reached because at the liquor gun the squeezing of the first end of the spraying nozzle against the outlet end of the black liquor feeding duct and it’s release is accomplished by an arrangement comprising a squeezer that is actuator operated and hence having capability to attach and detach the spraying nozzles to the liquor guns quicker and more reliably regardless of the scale formed on the region of spraying nozzle attachment with the black liquor feeding duct. More specifically, the arrangement for connecting a spraying nozzle to a liquor gun of a recovery boiler according to the invention is characterized by what is described in the independent claim 1 , the liquor gun according to the invention is characterized by what is described in the independent claim 13, and the method for connecting a spraying nozzle to a liquor gun of a recovery boiler according to the invention is characterized by what is described in the independent claim 14. The dependent claims 2-12 describe advantageous embodiments of the arrangement, and the dependent claims 15 and 16 describe advantageous embodiments of the method according to the invention.

[0011] A technical effect of the arrangement, the liquor gun, and the method according to the invention is that replacement of spraying nozzles can be carried out safer, smoother and quicker, without any specific tools and in a way that regardless of the method of the replacement being manual or automated less assembly issues and complications are encountered in attachment and / or detachment due to the scale formed by burnt black liquor on the spraying nozzles.

[0012] Brief description of the drawings

[0013] In the following, the invention will be described in more detail with reference to the appended drawings in which: Fig. 1 shows an arrangement according to an embodiment of the invention in connection with a liquor gun shown obliquely from the side of the liquor gun, and

[0014] Fig. 2 shows a spraying nozzle to be connected to the liquor gun by the arrangement of the figure 1 seen obliquely from the direction of its first end being the end to be attached against the outlet end of the black liquor feeding duct.

[0015] Detailed description of some advantageous embodiments

[0016] Figure 1 shows an embodiment of an arrangement 10 for connecting a spraying nozzle 11 to a liquor gun of a recovery boiler. In this patent application a liquor gun is considered to comprise a black liquor feeding duct, a liquor gun rack and a spraying nozzle. Black liquor feeding duct is for instance a tube or a pipe that is lead from an evaporation plant of a pulp mill, typically from a storage tank where - evaporated, high solids containing black liquor is stored before it is lead to the recovery boiler for burning. The liquor gun rack is a part of the liquor gun that moves the liquor gun (or at least its part comprising the spraying nozzle) towards and away from the wall of the recovery boiler such that at least part of the spraying nozzle can be extended into the furnace of the recovery boiler through a black liquor feeding opening at the wall of the recovery boiler and retracted back outside the recovery boiler. The liquor gun rack may further comprise position adjustment means for moving the liquor gun vertically up and down and / or for tilting the liquor gun in respect of a horizontal axis that is perpendicular to the longitudinal axis of the liquor gun such that the spraying can be set in appropriate position and orientation when it is extended into the furnace of the recovery boiler.

[0017] The spraying nozzle 11 is an exchangeable component of the liquor gun. An example embodiment of a spraying nozzle is shown in the figure 2. It’s object is to convey the black liquor from the outlet end of the black liquor feeding duct 12 inside the furnace of the recovery boiler and spread it appropriately into the furnace. Thus, it is designed so that the droplets formed in the spraying during the normal operation of the recovery boiler have optimal size and will be distributed in a way to ensure appropriate combustion of the black liquor in the furnace.

[0018] The spraying nozzle 11 shown in the figure 2 has a first end 11 a being connectable to an outlet end 12a of a black liquor feeding duct 12 and a second end 11 b having at least one opening for exiting the black liquor out from the spraying nozzle 11 .

[0019] In the embodiment shown in the figure 1 , an arrangement 10 comprises parts which of some locate at the liquor gun rack as well as some others in the spraying nozzle 11 . In the arrangement 10 these parts cooperate with each other during the time when the spraying nozzle 11 is attached to the outlet end 12a of the black liquor feeding duct 12, and in the moment when they are detached from each other. Especially, when the first end 11 a of the spraying nozzle 11 is attached to the outlet end 12a of the black liquor feeding duct 12 it is also aligned with the black liquor feeding duct 12 such that black liquor channels in these are interlinked.

[0020] The arrangement 10 shown in the figure 1 comprises a support frame 13. The support frame 13 may be a part of the liquor gun rack that is movable by the liquor gun rack. The support frame 13 is arranged to hold the black liquor feeding duct 12 at the liquor gun such that the spraying nozzle 11 can be connected to the outlet end 12a of the black liquor feeding duct 12 by squeezing the first end 11 a of the spraying nozzle 11 against the outlet end 12a of the black liquor feeding duct 12. Thus, when the spraying nozzle 11 is squeezed like that the black liquor can flow from the black liquor feeding duct 12 into the spraying nozzle 11 .

[0021] For squeezing, the embodiment shown in the figures 1 and 2 has a squeezer 16. The squeezer 16 comprises an actuator 17 for operating the squeezer 16. Term “operating” is meant in this regard that actuator 17 has been configured to accomplish the squeezing and / or at least release of the squeezing. The actuator 17 is in this embodiment a single-act pneumatic cylinder. The working motion of the actuator 17 accomplishes release of the squeezing since the squeezing, in this embodiment, is accomplished by springs 19 at each side of the actuator 17. However, in the other embodiments the actuator could be alternative dual-act pneumatic, hydraulic cylinder, rotative actuator or any other suitable actuator producing appropriate linear movement by means of which also the squeezing the first end of the spraying nozzle against the outlet end of the black liquor feeding duct can be accomplished with or without any springs. Thus, in some other embodiments the actuator can be alternatively, for instance a manually operated actuator, comprising a mechanical means for operating the actuator by hand.

[0022] As described above, in the embodiment of figures 1 and 2 the squeezer 16 is arranged at the support frame 13. However, in the other embodiments the squeezer 16 may be e.g., external squeezer that is placed at the liquor gun during the time when it is used.

[0023] To realize the squeezing the embodiment of the arrangement shown in the figures 1 and 2 has a first connecting element 14 at the outlet end 12a of black liquor feeding duct 12, and a second connecting element 15 at the first end 11a of the spraying nozzle 11. Moreover, in this embodiment, the first connecting element 14 and the second connecting element 15 comprise each a flange. However, in other embodiments the first connecting element and / or the second connecting element may be other kind of connecting elements by means of which the squeezing can be arranged correspondingly. Thus, the first connecting element and / or the second connecting element may be, for instance, lugs, brackets, grooves, or slots being at the outer periphery of the spraying nozzle and the black liquor feeding duct being designed such that they can be used for squeezing the first end of the spraying nozzle against the outlet end of the black liquor feeding duct. It should be further notified that the first connecting element and the second connecting element need not to be exactly at the outlet end of the black liquor feeding duct and the spraying nozzle such that e.g., the second connecting element may locate at distance from the first end to the direction of the second end of the spraying nozzle. Thus, to accomplish the squeezing in this embodiment the squeezer 16 is arranged to squeeze the second connecting element 15 against the first connecting element 14 and thereby the first end of the spraying nozzle against the outlet end of the black liquor feeding duct. For that purpose, the squeezer 16 in the embodiment of figures 1 and 2 comprises a squeezing part 18 cooperating with the second connecting element 15. The squeezing part 18 is movable from a releasing position, releasing the second squeezing element 15, to a squeezing position, squeezing the second connecting element 15 against the first connecting element 15, and vice versa. In the other embodiments squeezing element may have been arranged to squeeze also or alternatively both, first connecting element and the second connecting element. This may be the case, for instance, if the squeezer would be an external squeezer i.e., such that it is not built into liquor burner rack.

[0024] In the embodiment shown in the figures 1 and 2 the squeezer 16 comprises two springs arranged to urge the squeezing part 18 from the releasing position to the squeezing position. Each of the two springs 19 is arranged at each side the side of the actuator 17 of the squeezer. In other embodiments there may be only one spring or more than two springs for this purpose, or the squeezing may be accomplished by only an actuator, preferably being configured to squeeze at least partly without continuous feeding of energy (i.e., e.g., compressed air, hydraulic pressure, or electricity).

[0025] In case the at least one spring is used to urge the squeezing part 18 from the releasing position to the squeezing position the actuator 16 can be a single act actuator providing a linear movement such as a single-act pneumatic cylinder. In this embodiment squeezing has been accomplished such that the actuator 17 pushes the squeezing part 18 when it releases the squeezing attachment of the spraying nozzle 11. In some alternative embodiments this may have been arranged such that the actuator pulls the squeezing part when it releases the squeezing. In such case there is an additional, stationary squeezing part on the outer side of the second connecting element and the (movable) squeezing element being moved by the actuator (and optionally by the at least one spring) is placed on the inner side of the first connecting element such that second connecting element can be squeezed against the first connecting element correspondingly.

[0026] In the embodiment shown in the figures 1 and 2 the squeezing part 18 is a U-shaped part, having two branches 18a and 18b between which the spraying nozzle 11 can be fitted such that the said two branches 18a and 18b can squeeze the second connecting element 15 against the first connecting element 14. In the embodiment of figures 1 and 2 squeezing part 18 is made of enough thick metal plate, e.g., steel plate. However, in the other embodiments squeezing part can be formed somehow differently. It can be e.g., formed of two separate flat elongate pieces of suitable material (e.g., steel) that have been fitted each side of the spraying nozzle such that they are able to squeeze the second connecting element against the first connecting element correspondingly.

[0027] Furthermore, in the embodiment shown in the figures 1 and 2 the arrangement 10 comprises holding element 20 at the spraying nozzle 11. The purpose of the holding element 20 is to allow a manipulator gripper (or corresponding manually operated tool) to grip the spraying nozzle 11 . In this embodiment the holding element is formed of boss at the spraying nozzle 11 having angular shape. The purpose of the angularity is that it prevents rotation of the spraying nozzle 11 when it is gripped by a gripper or tool having corresponding internal shape. Furthermore, in this embodiment the holding element 20 is placed at a known distance from the second connecting element 15. Thus, when an automated spraying nozzle replacing apparatus (e.g., a robot) is used for changing the spraying nozzle 11 the position of the first end in respect of the position of the apparatus 10 is always exactly known. This will help in positioning the spraying nozzle 11 during its assembly to the liquor gun.

[0028] When replacing a used spraying nozzle 11 with a new spraying nozzle 11 in a liquor gun having arrangement shown in the figures 1 and 2 following phases will be typically carried out: 1. Flow of the black liquor in the black liquor feeding duct 12 is ceased.

[0029] 2. The liquor gun is retracted from its spraying position (where the spraying nozzle is at least partly inside the recovery boiler furnace) to the spraying nozzle 11 change position (i.e., the position wherein the spraying nozzle is completely outside the recovery boiler furnace).

[0030] 3. The spraying nozzle 11 is gripped at the position of the holding element 20 with a gripping tool corresponding the holding element 20. If an automated spraying nozzle exchange apparatus is applied, the gripper of the automated spraying nozzle exchange apparatus is moved to the position of the holding element 20 prior the gripping. Such system typically has corresponding gripping tool at the gripper than the one used in manual spraying nozzle exchange work.

[0031] 4. The squeezing part 18 is moved from the squeezing position to release position by providing compressed air into the actuator 17.

[0032] 5. The spraying nozzle 11 to be replaced is detached from its connection with the black liquor feeding duct 12 and transported e.g., to a storage of the spraying nozzles 11 for storing and / or cleaning.

[0033] 6. A new spraying nozzle 11 is hold at its holding element 20 and moved to the liquor gun for assembly.

[0034] 7. The new spaying nozzle 11 is positioned in respect of the black liquor feeding duct 12 such that the first end 11a of the new spraying nozzle 11 is against the outlet end 12a of the black liquor feeding duct 12.

[0035] 8. The squeezing part 18 of the squeezer 16 is moved to the squeezing position by releasing the compressed air from the actuator 17 whereupon the two springs 19 urge the squeezing part 18 against the second connecting element 15.

[0036] 9. Pumping of the black liquor into the spraying nozzle 11 through the black liquor feeding duct 12 is continued. The afore-described replacement can be carried out manually or by means of an automated spraying nozzle handling robot / manipulator. In both cases the spraying nozzle 11 is preferably gripped by a gripping tool or gripper which fits around the holding element 20. In the embodiment shown in the figures 1 and 2 the holding element 20 is a boss having hexagon shaped outer periphery. The advantage of this shape is that it prevents the rotation of the spraying nozzle 11 in respect of its longitudinal axis and thereby ensures that the spraying nozzle 11 remains always in correct orientation when it is assembled to the liquor gun. However, it should be notified that the holding element may have also other shape which may be correspondingly latching than the said hexagonal shape. Latching connecting elements may have for instance other kind of angular shapes, such as e.g., square, or octagonal shape or other kind of latching shape such as e.g., oval. However, in some other embodiments the holding element may alternatively have non-latching shape. In such embodiments its purpose is only to help in positioning the gripper in respect of its distance from the first end of the spraying nozzle. Furthermore, the holding element at the spraying nozzle is not always necessary at all since e.g., in case of manual assembly the person who carries out the spraying nozzle change is able to position the spraying nozzle e.g., in between the squeezing part and the second connecting element without such holding element. This may be the case also with an automated spraying nozzle exchange apparatus if the apparatus has suitable positioning system based on e.g., to machine vision or some other positioning technology.

[0037] Thus, the arrangement and method are not limited to the embodiments described above but can vary within the scope of the appended claims. Therefore, also other components, solutions, and details of the arrangement and method according to the invention can be realized in multiple different manners differing from those proposed in the above-described example embodiments without deviating from the scope of the appended claims.

Claims

Claims1 . An arrangement (10) for connecting a spraying nozzle (11 ) to a liquor gun of a recovery boiler, the spraying nozzle (11 ) having a first end (11 a) being connectable to an outlet end (12a) of a black liquor feeding duct (12) at the liquor gun, and a second end (11 b) having at least one opening for exiting the black liquor out from the spraying nozzle (11 ), the arrangement (10) further comprising-a support frame (13) arranged to hold the black liquor feeding duct (12) at the liquor gun such that the spraying nozzle (11 ) can be connected to the outlet end (12a) of the black liquor feeding duct (12) by squeezing the first end (11 a) of the spraying nozzle (11 ) against the outlet end (12a) of the black liquor feeding duct (12), and thereby allowing black liquor to flow from the black liquor feeding duct (12) into the spraying nozzle (11 ),-a first connecting element (14) at the outlet end (12a) of the black liquor feeding duct (12),-a second connecting element (15) at the first end (11 a) of the spraying nozzle (11 ),-a squeezer (16) to squeeze the second connecting element (15) against the first connecting element (14), and wherein the squeezer comprises an actuator (17) for operating the squeezer (16).

2. The arrangement (10) according to claim 1 wherein the squeezer (16) is arranged at the support frame (13).

3. The arrangement (10) according to claim 1 or 2 wherein the actuator (17) is arranged to at least release squeezing of the second connecting element4. The arrangement (10) according to any of preceding claims, wherein the squeezer (16) comprises a squeezing part (18) cooperating with the second connecting element (15) and being movable from a releasing position, releasing the second squeezing element (15), to a squeezing position, squeezing the second connecting element (15) against the first connecting element (15), and vice versa.

5. The arrangement (10) according to claim 4, wherein squeezer (16) comprises at least one a spring (19) arranged to urge the squeezing part (18) from the releasing position to the squeezing position.

6. The arrangement (10) according to claim 4 or 5 wherein the actuator (17) is arranged to move the squeezing part (18) from the squeezing position to the releasing position.

7. The arrangement (10) according to claim 6 wherein the actuator is a manually operated actuator, comprising a mechanical means for operating the actuator by hand.

8. The arrangement (10) according to claim 6 wherein the actuator (17) is a single-act pneumatic cylinder.

9. The arrangement (10) according to any of preceding claims wherein the first connecting element (14) is a flange at the outlet end (12a) of the black liquor feeding duct (12) and the second connecting element (15) is a flange at the first end (11 a) of the spraying nozzle (11 ).

10. The arrangement (10) according to claim 8 or 9 wherein the squeezing part (18) is a U-shaped part having two branches (18a, 18b) between which the spraying nozzle (11 ) can be fitted such that the two branches (18a, 18b) can squeeze the second connecting element (15) against the first connecting element (14).11 . The arrangement (10) according to any of preceding claims wherein the arrangement comprises holding element (20) at the spraying nozzle (11 ) allowing a manipulator gripper to grip the spraying nozzle (11 ).

12. The arrangement (10) according to claim 11 wherein the holding element is placed at a distance from the second connecting element (15).

13. A liquor gun of a recovery boiler wherein the liquor gun comprises an arrangement (10) according to any of claims 1 to 12.

14. A method for connecting a spraying nozzle (11 ) to a liquor gun of a recovery boiler wherein the spraying nozzle (11 ) has a first end (11 a) to be connected to an outlet end (12a) of a black liquor feeding duct (12) at the liquor gun, and a second end (11 b) having at least one opening for exiting the black liquor out from the spraying nozzle (11 ), and wherein the first end (11 a) of the spraying nozzle (11 ) is squeezed against the outlet end (12a) of the black liquor feeding duct (12) by an arrangement (10) according to any of claims 1 to 12.

15. The method according to claim 14 wherein the first end (11 a) of the spraying nozzle (11 ) is squeezed against the outlet end (12a) of the black liquor feeding duct (12) by at least one spring.

16. The method according to claim 14 or 15 wherein squeezing of the first end (11 a) of the spraying nozzle (11 ) is released by an actuator

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