Attemperator and a use of a such

Abstract

The invention relates ton attemperator. It has a pipe section (3) and a liner pipe section (4) arranged within the pipe section (3) and being attached thereto. The pipe section (3) has an internal wall surface (33) and the liner pipe section (4) has an external wall surface (43). The internal wall surface (33) and external wall surface (43) form a gap (6) between them. The pipe section (3) and liner pipe section (4) each has an inlet end (31, 41) for connection to a steam supply and an outlet end (32, 42) for steam. The attemperator is provided with water injection means (2) arranged for supplying water into the interior of the liner pipe section (4). The inlet end (31) of the liner pipe section (3) has an outwardly extending wall portion (44) forming an outer circumferential outer zone (45), which zone (45) may contact the internal wall surface (33) of the pipe section (3). According to the invention there is provided a plurality of openings (47) arranged to allow steam to enter the space formed by the gap (6) between the internal wall surface (33) and the external wall surface (43). The invention also relates to a use of the attemperator.

Claims

1. An attemperator including a pipe section (3) and a liner pipe section (4) arranged within the pipe section (3) and being attached thereto, the pipe section (3) having an internal wall surface (33) and the liner pipe section (4) having an external wall surface (43), which internal wall surface (33) and external wall surface (43) form a gap (6) between them along at least a major part of the axial extension of the liner pipe section (4), which pipe section (3) and liner pipe section (4) each has an inlet end (31, 41) for connection to a steam supply and an outlet end (32, 42) for steam, and which attemperator is provided with water injection means (2) arranged for supplying water into the interior of the liner pipe section (4), the inlet end (41) of the liner pipe section (4) having an outwardly extending wall portion (44) forming an outer circumferential zone (45), which zone (45) is adjacent or in contacts with the internal wall surface (33) of the pipe section (3) wherein there is provided at least one opening (47) at the inlet end (41) of the liner pipe section (4) arranged to allow steam to enter the space formed by the gap (6) between said internal wall surface (33) and said external wall surface (43), wherein the at least one opening (47) is a plurality of openings, and wherein the liner pipe section (4) is attached to the pipe section (3) by a clamp connection means (5) adjacent the outlet end (42) of the liner pipe section (4) which clamp connection means (5) is fastened to the interior wall surface (33) of the pipe section (3) and has an inner surface (52) that abuts the external wall (43) of the liner pipe section (4).

2. An attemperator according to claim 1, wherein the openings (47) are evenly distributed in the circumferential direction.

3. An attemperator according to claim 1 wherein each opening (47) is formed between said internal wall surface (33) and a recess (46) in said contact zone (45).

4. An attemperator according to claim 1, wherein the total circumferential extension of the least one opening (47) is in the range of 5 to 20% of the circumferential length of the contact zone.

5. An attemperator according to claim 1, wherein the total through flow area of the least one opening (47) is in the range of 1 to 10% of the total cross area of said space in a section perpendicular to the axial extension of the pipe section.

6. An attemperator according to claim 1, wherein there is provided at least one axially extending opening (51a, 51b) at the outlet end (42) of the liner pipe section (4) arranged to allow steam to exit the space formed by the gap (6) between said internal wall surface (33) and said external wall surface (43).

7. An attemperator according to claim 1, wherein said wall portion (44) extends obliquely out from the inlet end (41) of the liner pipe section (4) towards the internal wall surface (33) of the pipe section (3) and is widening in the direction to the inlet end (31) of the pipe section (3).

8. An attemperator according to claim 7, wherein the angle (a) of said wall portion (44) with the axial direction of the liner pipe section (4) is in the range between 15 and 45.

9. An attemperator according to claim 1, wherein the clamp connection means (5) includes at least one said opening (51a, 51b) establishing communication between the two axial sides of the clamp connection means (5).

10. An attemperator according to claim 1, wherein the clamp connection means (5) includes at least two units (5a, 5b) separated in the circumferential direction by a circumferential gap at each circumferential end of the units (5a, 5b), which circumferential gaps form said at least one said opening (51a, 51b).

11. An attemperator according to claim 1, wherein the exterior wall surface (43) of the liner pipe section (4) and the inner surface (52) of the clamp connection means (5) are shaped to provide axial locking relative each other.

12. An attemperator according to claim 11, wherein the axial locking is formed by at least one outwardly extending projection (48) of the external wall surface (43) of the liner pipe section (4) and a correspondingly shaped and located recess (52) in the inner surface of the clamp connection means (5) for each projection.

13. An attemperator according to claim 12, wherein there is only one projection (48) formed as a circumferentially extending rim.

14. A method of supplying steam at a controlled temperature to a turbine with an attemperator according to claim 1.

15. An attemperator according to claim 1 wherein the clamp connection means 5 is in the form of rotatable connecting members, wherein the liner pipe section 4 is arranged with a plurality of rim portions, symmetrically displaced along the inner periphery with corresponding gaps them between, and the pipe section 3 is provided with a corresponding arrangement, wherein the gaps and rim portions are arranged to allow the inner pipe section to be moved axially for fitting the inner pipe section within said clamp connections and thereafter the liner pipe section 4 may be rotated whereby the rim portions enter into the recess within the rim portions of the pipe section to from a bayonet connection.

16. An attemperator according to claim 7, wherein the angle (a) of said wall portion (44) with the axial direction of the liner pipe section (4) is in the range between 25 and 35.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an end view of an attemperator according to the invention as seen from the outlet end.

(2) FIG. 2 is a section along line II-II of FIG. 1.

(3) FIG. 3 is a section along line of FIG. 2 but with some details left out.

(4) FIG. 4 is a perspective view of the inlet end of the liner pipe section of the attemperator of FIGS. 1-3, and

(5) FIG. 5 is a section along line V-V of FIG. 4.

DESCRIPTION OF EXAMPLE

(6) FIGS. 1 and 2 depict an attemperator according to an example of the present invention. The attemperator consist of an attemperator pipe section 1 and a water injection device 2. The attemperator has externally a pipe section 3. Inside the pipe section 3 is a liner pipe section 4. The pipe section 3 and the liner pipe section 4 in this example both are of circular shape and are coaxial. In operation the pipe section 2 is intended to be a part of a supply pipe for supplying superheated steam to a turbine.

(7) The water injection device 2 is arranged to spray water into the attemperator pipe section 1 in order to cool the superheated steam flowing therethrough. The water injection device has an inlet 21 which is to be connected to a water supply. From the inlet 21 the water flows into a circumferential water pipe 22 that surrounds the attemperator pipe section 1.

(8) The water is introduced into the interior of the liner pipe section 4 through a number of nozzles 24 extending through both the pipe section 3 and the liner pipe section 4. In the example the number of nozzles 24 is four, and they are evenly distributed in the circumferential direction. Each nozzle 24 is provided with an atomizer 23 for supplying the water as small droplets. The nozzles 24 are located axially adjacent the inlet end 41 of the liner pipe section 24.

(9) An axially directed water distribution pipe (not shown in the figures) extends outside of the pipe section 3 from the circumferential water pipe 22 to each atomizer/nozzle 23/24.

(10) The water is supplied from the inlet 21 via the circumferential pipe 22, the distribution pipes, the atomizers 23 and the nozzles 24 into the steam flowing through the liner pipe section 4 so that the steam is cooled.

(11) The internal diameter of the pipe section 3 is larger than the external diameter of the lining pipe section 4. A gap 6 thus is formed by the internal wall surface 33 of the pipe section 3 and the external wall surface 43 of the liner pipe section 4. The gap is relatively small. For a tube pipe section 3 of about 700 mm diameter, the gap 6 should be in the order of 10 to 20 mm.

(12) At its inlet end 41 the liner pipe section 4 has a conical portion 44, which conical portion extends outwardly along an angle to the internal wall surface 33 of the pipe section 3 and to preferably contact therewith along a circumferential contact zone. The large end of the conical portion 44 is directed towards the inlet end 31 of the pipe section 3 and thus decreases in diameter in the steam flow direction. The conical portion is shown to form an angle with the axis of the liner pipe section that is about 30, preferably within 20-40.

(13) Referring now to FIG. 3 which is a partial section along line III-III of FIG. 2, it can be seen that the conical portion 44 may be in contact with the interior wall surface 33 of the pipe section 3 along a circumferential outer zone 45. At four equally distributed locations along the outer zone 45, the possible contact zone is broken by a recess 46 in the conical portion 44. Thereby forming a small opening 47 between the recess 45 and the internal wall surface 33 of the pipe section 3. When the inlet end 31 of the pipe section 3 is connected to a pipe supplying superheated steam most of the steam will flow through the interior of the liner pipe section 4 where it mixes with the injected water before reaching the outlet end 32 of the pipe section 3. A small fraction of the steam, however will flow through the openings 47 into the gap 6 between the pipe sections 3, 4. The steam thereby will heat the pipe section 3 somewhat.

(14) The openings may alternatively be obtained by making recesses in the internal wall surface 33 of the pipe section, in the area where this surface may contact the outer zone 45. A further alternative is to obtain the openings by borings through the conical portion 44. Within the scope of invention, the number of openings may of course be other than four, and the circumferential extensions of the openings as well as their through flow areas may also vary. It is also to be understood that the conical portion 44 may be a wall portion having a shape deviating from that of a cone, and also that alternatively to positioning the front end 41 by means of contact of the outer zone 45, it may be achieved by the nozzle devices 24.

(15) FIG. 4 illustrates the attachment of the liner tube section 4 to the tube section 3. This connection is arranged adjacent the outlet end 42 of the liner tube section. A clamp connection means 5 is welded to the internal wall surface 33 of the pipe section 3 and is clamped around the liner pipe section 4. The clamp connection means 5 in this example consists of two separate units 5a, 5b. At both locations where the units 5a, 5b meet each other, a small circumferential clearance is formed whereby an opening 51a, 51b is established in the axial direction. At least one of these opening extends into the gap 6 and thereby allows the steam which has entered the gap to escape from the gap at the outlet end of liner pipe section 4. Preferably both of said openings 51a, 51b extend into the gap to provide two flow paths for the steam in the gap. Thus, there is provided at least one opening 51a, 51b at the outlet end 42 of the liner pipe section 4 arranged to allow steam to exit the space formed by the gap (6) between said internal wall surface 33 and said external wall surface 43 and enter the pipe section 3 at the end of the liner pipe section 4. Additional openings may be provided to provide redundancy in the event of an opening becoming blocked and/or to achieve a desired flow rate. While the opening(s) may conveniently be made by providing the small circumferential clearance where the units 5a, 5b meet as described above, it is possible to make openings that extend substantially in the axial direction from the gap in other ways, for example by bore holes or grooves or the like in the clamp connection means or one or more of the internal or external wall surfaces.

(16) FIG. 5 is an enlarged section through the clamp connection means 5 and adjacent elements. The exterior wall surface 43 of the liner pipe section 4 is provided with a radially extending projection 48. The projection 48 may be a rim extending along the complete circumferential. The inside of the clamp connection means has a recess 52 of corresponding shape such that the projection 48 projects into the recess 52 and thereby provides axial locking of the liner pipe section 4.

(17) The invention is not limited by the examples described above but may be varied within the scope of the appended claims. For instance it may be used a different clamp connection means 5 in the form of rotatable connecting members, e.g. having the liner pipe section 4 arranged with a plurality of rim portions, symmetrically displaced along the inner periphery with corresponding gaps them between and the pipe section 3 having a corresponding arrangement, enabling interfit by means of first axially introducing the liner pipe section 4 into the pipe section 3, wherein the gaps and rim portions allow the pipe sections to be moved for interfit. Thereafter the liner pipe section 4 may be rotated whereby the rim portions enter into the recess within the rim portions of the pipe section, according to the bayonet connecting principle.