EP0591215B1 - A device for protecting condenser tubes - Google Patents

A device for protecting condenser tubes Download PDF

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Publication number
EP0591215B1
EP0591215B1 EP91920508A EP91920508A EP0591215B1 EP 0591215 B1 EP0591215 B1 EP 0591215B1 EP 91920508 A EP91920508 A EP 91920508A EP 91920508 A EP91920508 A EP 91920508A EP 0591215 B1 EP0591215 B1 EP 0591215B1
Authority
EP
European Patent Office
Prior art keywords
shield
cooling tube
tube
condenser
cooling
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP91920508A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0591215A1 (en
Inventor
Josef Weiss
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Original Assignee
Siemens AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Publication of EP0591215A1 publication Critical patent/EP0591215A1/en
Application granted granted Critical
Publication of EP0591215B1 publication Critical patent/EP0591215B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers
    • F28F19/002—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers by using inserts or attachments

Definitions

  • the present invention relates to a condenser according to the preamble of Claim 1, comprising a shield for protecting condenser tubes against erosion by the waterdroplet-containing steam that flows rapidly into a condenser.
  • the steam is normally conducted from the low pressure turbine of the plant to a condenser.
  • the steam is caused to condense in the condenser under a pronounced subpressure, by cooling the condenser with cold water.
  • This cooling water is conducted through a large number of cooling tubes which are mounted in groups or bundles and which extend horizontally in the condenser housing.
  • the cooling tubes of each group are placed in mutually parallel and closely adjacent relationship. Since the steam is condensed primarily within the groups while the majority of the heat is removed from the narrow spaces defined between the closely adjacent cooling tubes, the largest subpressure occurs in this region.
  • the velocity of the steam at the condenser inlet may be in the order of 200 m/s, and the steam flowing into said condenser seeks a path to these regions of highest subpressure. In doing so, the steam is forced to pass between the outermost cooling tubes in the groups of cooling tubes, the so-called rim tubes. Because the steam contains water droplets which cannot be guided in between the rim tubes, but which strike against said tubes at the same velocity as that of the steam arriving at the tubes, the water droplets cause erosion on the outwardly-facing sides of the rim tubes. After a time, the erosion, which is due to fatigue of the grain boundaries, will be so extensive as to form penetrating holes in the tube walls.
  • U.S. 3,568,763 discloses a condenser which partially solves the erosion problem.
  • This closest prior art condenser comprises a structure in the form of a ridge roof which is mounted immediately above each group of cooling tubes.
  • the device protects the uppermost rim tubes of a respective group against the steam that enters directly from the condenser inlet, but affords small protection to the rim tubes located on a lower level.
  • a further drawback is that the device cannot be used with existing steam power plants without reconstructing the plants at high costs.
  • Another known protective device has the form of a grid which is mounted immediately outside the rim tubes of a group of cooling tubes, so as to take the force of the erosion attack. This solution, however, results in high losses due to the resistance presented to the flow of steam.
  • U.S. 1,341,784 teaches a device for protecting automobile-radiator tubes against freesing.
  • the device is fastened on the rear side of the tube with clamping action and will not give any protection for water droplets in the flow.
  • U.S. 2,853,279 teaches a heat transfer retarding shield that also serves to protect surfaces against erosion.
  • the shield is rigid and covers the frontside of a tube to which it is welded.
  • the fastening is complicated and the shield will imply power loss as it is meant to retard heat transfer.
  • U.S. 3,149,667 teaches a shield for protecting a radiator tube with elongated section against erosion caused by a fluid flow.
  • the shield is of U-shaped form and dimensioned to embrace the leading edge and the parallel sides of the tube to which the shield is solder bonded. As the shield is fastened by soldering, this protection device is not suitable for fitting to existing structures in steam power plants.
  • the device shall be capable of protecting all types of cooling tubes in a tube group, shall result in the smallest possible power loss and shall have a long useful life.
  • the device shall also be suitable for use in both new plants and existing plants, and in the latter case shall be capable of being fitted during the operational season of the plant without requiring the plant to be shut down for long periods of time.
  • the object of the present invention is to provide a condenser with a shield of the kind mentioned in the introduction which will solve the aforesaid technical problems.
  • This object is achieved in accordance with the invention with a condenser having the characteristic features set forth in the Claims 1.
  • a condesner with a shield which is comprised of a casing in the form of a shell which is intended to cover that part of a condenser tube which is subjected to erosion.
  • the shell can be considered to have the form of a so-called half-tube which is secured to each cooling tube to be protected, so as to be located on the side of said tube which is subjected to erosion or exposed to the risk of erosion.
  • the casing has a length which is appropriate with respect to its position and also with respect to the length of the free cooling-tube section to be protected, etc.
  • the half-tube includes that part of a circular "base tube” of preferably uniform thickness which is defined by two generatrices on the "base tube” with a centre angle of about 180° .
  • said shell is provided with mutually converging devices which project from the long sides of the shell and which are preferably made from the same material and have the same thickness as said shell. These attachment devices first extend generally parallel with one another and are then bent in towards one another into engagement with the rear side of the cooling tube, thereby providing means for holding the shell firmly on the cooling tube.
  • the shell can be brought into intimate contact with said tube, when the shape of said shell conforms with the shape of the cooling tube, due to a wide contact surface and a satisfactory contact pressure over said surface.
  • These spring or tension forces also contribute to the generation of frictional forces which ensure that the shell will be affixed against rotation on the cooling tube.
  • the ability of the shield to fasten to the cooling tube depends, among other things, on the extent to which the outermost parts of the shield that are in contact with the cooling tube extend around said tube, i.e. on the centre angle encompassed by the shield. This angle should be at least 180° in order for the shield to fasten at all.
  • the shell is made of an elastic material, of uniform thickness, and is configured so that, when fitted, it includes that part of the "base tube” which is defined by two generatrices having "a centre angle" slightly above 180°, preferably between 200° and 220° .
  • the cup-shaped bands which form continuations of the contemplated shell function as securing devices along its long sides.
  • the shell or casing is given a generally circular or possibly a slightly elliptical cross-sectional shape prior to being fitted, with an inner diameter which is slightly smaller than the outer diameter of the cooling tube.
  • the shell or casing is widened to a state in which it is fitted to the cooling tube, the whole of the inner surface of the shell or casing, including that part which is considered as the fastening means, will assume essentially the shape of the cooling tube and will obtain the aforesaid retaining property and said intimate contact with said cooling tube.
  • the shell When the shell has a relatively small wall thickness and is made of a material, such as a metal alloy, which has good spring properties, the shell can also be widened to an extent which will enable its mutually parallel long sides to be fitted over the cooling tube from one side thereof without plastically deforming the shell. When the shell strives to spring back to its original shape, the shell will partially embrace the cooling tube, as before mentioned.
  • the inventive fastening devices projecting out from the shell are not limited to parts of a "base tube".
  • the fastener devices may have the form of strip-like extensions which first extend in mutually parallel relationship through a given distance and then folded in towards one another and into contact with the cooling tube.
  • an advantage is afforded when the fastening devices directly abut the rear side of the cooling tube, it may be beneficial in some cases to place some form of insert between the fastener devices and the cooling tube, for instance in order to increase the pressure of the fastener devices against the cooling tube when fitting the shell.
  • the fastener devices may, instead, comprise a plurality of mutually spaced narrower tongues.
  • the inventive condenser can be used both in planned plants and in existing plants for preventing erosion of cooling tubes and for protecting rim tubes which have already been eroded from further damage, therewith to avoid long plant shut-down periods during the plant operating season. If erosion has caused penetrating holes in the tubes, a good and effective seal can be obtained with the aid of glue or a locking liquid between the shield and the cooling tube. This would also improve locking of the shield against rotation.
  • the shield is inexpensive to produce and can be fitted quickly and simply. In the case of the preferred shield, the shield is pushed over the cooling tube from one side thereof by exerting pressure on the spine of the shield, whereupon the shield will open and then spring back around the tube.
  • Figure 1 is a vertical, sectional view of a condenser.
  • FIG 2 illustrates a cooling tube of the condenser shown in Figure 1, fitted with a protective shield constructed in accordance with the invention.
  • FIG. 3 illustrates the protective shield shown in Figure 2.
  • FIG. 4 and 5 illustrate alternative protective shields.
  • Figure 1 is a cross-sectional view of the upper part of a condenser section 1 which includes a cooling tube group 2 comprised of a number of cooling tubes 3 from which heat is removed by means of internally-flowing cooling water.
  • a cooling tube group 2 comprised of a number of cooling tubes 3 from which heat is removed by means of internally-flowing cooling water.
  • the cross-sectional view is taken on a plane which extends between two support plates which function to support the cooling tubes 3.
  • the distal plate of these support plates is referenced 4 in the Figure.
  • the used steam exiting from the low pressure turbine 5 of the plant flows through the condenser inlet 6 and into the condenser section 1.
  • the steam flow at the inlet 6 has a significant velocity which, in the case of large plants, can be in excess of 200 m/s.
  • the steam flow divides and seeks entry into the group of cooling tubes 2 from different directions, between the peripherally located rim tubes 7 (as indicated by the arrows in Figure 1).
  • the used steam contains small water droplets which are not guided in between the rim tubes 7, but which strike the rim tubes 7 at a velocity corresponding to the inlet velocity of the steam, and gradually result in needle-like pits or holes and other erosion damage to an extent such as to form penetrating holes through the tube walls.
  • the present invention proposes the use of protective shields 8 which in the case of the preferred embodiment (see Figure 2) are configured as tubular shells having a centre angle v which, when the shell is fitted, is about 210° and a length which is somewhat shorter than the distance between the support plates 4.
  • the protective shield is made of a thin, elastic material, such as acid-proof stainless steel, which has good spring properties and is highly resistant against this type of corrosion. In the electrogalvanic stress chain, the material also lies close to the material from which the cooling tubes are made, in the present case titanium, and hence crevice or contact erosion between the protective shield and its associated cooling tube need not be feared.
  • the protective shield can be manufactured directly, by rounding strip material in a known manner, or indirectly by dividing standard tubes along a generatrice and thereafter pressing the tube into the shape intended.
  • the protective shield is given a generally circular-arcuate cross-sectional shape with an inner diameter which is slightly smaller than the outer diameter of the cooling tube to be protected, and consequently with a larger centre angle than in its fitted state (see Figure 3).
  • the protective shield When the protective shield is to be fitted around a cooling tube, the shield is simply snapped over the cooling tube from one side thereof, so as to be positioned over those parts of the tube which are exposed or subjected to erosion damage.
  • the protective shields are suitably placed in positions in which only one of the shields will encroach on this gap (see Figure 1).
  • the shield may be provided with separate fastener devices which extend out from the shell.
  • Figure 4 illustrates a protective shield 9 provided with tongues 10 which are attached to both long sides of the shell.
  • Figure 5 illustrates a shield 11 in which fastener devices on one edge are included by the shell and on the other edge have the form of tongues 12. As illustrated in the drawing, the tongues may be formed from parts of the same tube as that from which the shell was formed.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
  • Mutual Connection Of Rods And Tubes (AREA)
  • Centrifugal Separators (AREA)
EP91920508A 1990-11-16 1991-11-18 A device for protecting condenser tubes Expired - Lifetime EP0591215B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE9003669 1990-11-16
SE9003669A SE467802B (sv) 1990-11-16 1990-11-16 Erosionsskydd foer kondensorroer i form av ett fastsnaeppt skal
PCT/SE1991/000782 WO1992008942A1 (en) 1990-11-16 1991-11-18 A device for protecting condenser tubes

Publications (2)

Publication Number Publication Date
EP0591215A1 EP0591215A1 (en) 1994-04-13
EP0591215B1 true EP0591215B1 (en) 1998-05-06

Family

ID=20380939

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91920508A Expired - Lifetime EP0591215B1 (en) 1990-11-16 1991-11-18 A device for protecting condenser tubes

Country Status (8)

Country Link
EP (1) EP0591215B1 (sv)
AU (1) AU8939591A (sv)
DE (1) DE69129372T2 (sv)
DK (1) DK0591215T3 (sv)
ES (1) ES2118092T3 (sv)
FI (1) FI110206B (sv)
SE (1) SE467802B (sv)
WO (1) WO1992008942A1 (sv)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1365205A1 (en) * 2002-05-21 2003-11-26 Lung-Hsi Chuang Protective wrapping device for a condenser tube

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1341784A (en) * 1918-05-20 1920-06-01 Clish Joseph Automobile-radiator
US1942211A (en) * 1933-04-20 1934-01-02 Charles W Hartwig Combination guard and heat transfer device
US2853279A (en) * 1953-11-27 1958-09-23 Gilbert Associates Heat transfer retarding shields
US3149667A (en) * 1962-09-24 1964-09-22 Young Radiator Co Core-unit for vehicular-radiator-type heat exchanger and protective shields therefor

Also Published As

Publication number Publication date
SE9003669L (sv) 1992-05-17
AU8939591A (en) 1992-06-11
FI932198A0 (fi) 1993-05-14
DE69129372T2 (de) 1998-10-29
EP0591215A1 (en) 1994-04-13
FI932198A (fi) 1993-06-10
SE467802B (sv) 1992-09-14
WO1992008942A1 (en) 1992-05-29
DK0591215T3 (da) 1999-03-15
SE9003669D0 (sv) 1990-11-16
ES2118092T3 (es) 1998-09-16
FI110206B (sv) 2002-12-13
DE69129372D1 (de) 1998-06-10

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