GB2078358A - A cooling tower and a method for the stabilisation of the boundary flow in the cooling tower - Google Patents
A cooling tower and a method for the stabilisation of the boundary flow in the cooling tower Download PDFInfo
- Publication number
- GB2078358A GB2078358A GB8118048A GB8118048A GB2078358A GB 2078358 A GB2078358 A GB 2078358A GB 8118048 A GB8118048 A GB 8118048A GB 8118048 A GB8118048 A GB 8118048A GB 2078358 A GB2078358 A GB 2078358A
- Authority
- GB
- United Kingdom
- Prior art keywords
- flow
- cooling tower
- cooling
- wall
- air
- 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.)
- Granted
Links
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
- F28F25/00—Component parts of trickle coolers
- F28F25/10—Component parts of trickle coolers for feeding gas or vapour
- F28F25/12—Ducts; Guide vanes, e.g. for carrying currents to distinct zones
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)
- Separation By Low-Temperature Treatments (AREA)
Abstract
A cooling tower has a wall (1) defining a cooling air flow passage which reduces in cross-section along the direction of air flow towards a neck region (2) and then widens again. A body (3) is mounted on the wall in the neck region (2) to direct air from a central portion of the passage to a radially outer portion of the passage. In this way energy rich air from a region in the passage substantially uneffected by wall friction is injected into the energy-poor air in the boundary layer in the vicinity of the neck region. This helps to avoid boundary layer separation and thereby maintain the cooling efficiency of the tower which would otherwise be reduced. <IMAGE>
Description
SPECIFICATION
A cooling tower and method for the stabilisation of the boundary flow in the cooling tower
The invention relates to a cooling tower and to a method of stabilising the boundary flow in the cooling tower.
Cooling towers have a flow cross-section converging in the lower zone in the direction of flow of the cooling air and diverging in the upper zone.
With such cooling towers when operating by natural draught then under certain weather condi- tions and operational requirements unstable flow conditions can arise at the outlet of the cooling air from the cooling tower. These unstable flow conditions lead to interruptions in the cold air in the upper part of the cooling tower and thereby to a worsening of the cooling tower operational efficiency. In order to overcome this disadvantage it has been proposed to use in place of a hyperbolic cooling tower with divergent outlet zone, a cooling tower in which the outlet zone is made narrower for the purpose of reduction of the flow cross-section, in order to hold off from the cooling tower cold air in spite of its higher specific weight by means of the acceleration of the heated cooling air associated with this reduction in cross-section.Other proposals relate to the deflection and the drawing up of the lateral wind to increase the drawing effect of the cooling tower by the provision of lateral openings in the mouth zone of the cooling tower, which are to be opened or closed in dependence upon the direction of the wind.
These known proposals have not only the disadvantage, that they are unsuitable for incorporation into existing cooling towers, but this involves, in relation to known hyperbolic cooling towers, a higher constructional expenditure, which at least partially offsets any achieved improvement in the cooling tower operational efficiency.
The described cooling tower and method stabilise the boundary flow in the cooling tower having a flow cross-section in the direction of flow of the cooling air that converges in the lower zone and diverges in the upper zone, and can be applied both to newly constructed and also to existing cooling towers and achieves with low technical as well as financial expenditure a substantial improvement in the working efficiency of the cooling tower.
The solution to the problem stems from the recognition that the cold air interruptions which worsen the working efficiency of a cooling tower are the result of detachment of the flow in the inner wall of the cooling tower, such flow detachments arise if the flow friction and the pressure increase at the same time. Since at the cooling tower inner wall the upwardly directed flow of the cooling air is decelerated by friction, a flow boundary layer exists. The thickness of this layer increases with continued length of passage of the flow along the wall. The flow zone adjacent the wall thus continually loses energy, so that it can be detached from the wall by for example, a pressure increase, or by sharp edges or by bundles of cold air effecting a disturbance.As a result of this cold air bundles have the opportunity of penetrating into the cooling tower up to the position of detachment of the flow boundary layer.
In order to reduce the effect of wall friction on the boundary layer flow of the cooling air, thereby to avoid the conditions for the detachment of the flow from the wall, the boundary layer is injected with a supply of air flow from the central zone of the cooling tower substantially uninfluenced by the wall friction. This injection is effected by bodies generating vortices and arranged in the narrowest flow cross-section in order to maintain the boundary layer of the cooling air on the inner wall surfaces of the cooling tower.
By means of such an energy supply from the air flow not influenced by the wall friction in the central zone of the cooling tower, to the boundary layer flow the possibility is further provided of overcoming other disturbances, in particular an increase in pressure without flow detachment and by individual pulses to force upwardly cold air particles. The reduction of the friction effect in the boundary layer flow by the energy exchange within the cooling tower thereby stabilises the boundary flow in a hyperbolic cooling tower, so that the diffuser action based on the divergent cooling tower crown can be fully used for the purpose of reduction of the smaller outlet pulses as a result of the smaller flow velocities.Simultaneously, the contour for the cooling tower can be optimized within the technically predetermined limits in accordance with purely static principles, whereby the hyperbolic cooling tower in comparision with other forms of cooling tower shells can be made even lighter and thus enable costfavourable construction.
The edges of the body flow components transverse to the flow direction of the cooling air are generated with vortices which become broader in the direction of the cooling air flow. By this means the energy-weak air particles are moved away from the wall of the cooling tower and replaced by energetic air particles from the core flow of the cooling tower, so that the boundary layer flow contains sufficient energy, to follow a pressure increase, that is a flow deceleration without detachmenu from the wall.
Since the bodies do not serve as flow guidance surfaces for the cooling air, but generate by their edges vortices, the flow resistance of the bodies is comparatively small and indeed not only related to the overall resistance of the heat exchange devices incorporated in the cooling tower. This follows from the fact that the vortex-generating surfaces are small in comparison with the flow cross-section of the cooling tower and the cooling air flow is given only a vortex impulse. The cooling tower for carrying out the method uses at least one body mounted in the flow direction of the heated up cooling air downstream of the heat-exchange devices of the cooling tower.This body is mounted in the zone of the narrowest flow cross-section of the cooling tower as well as in the neighbourhood of the cooling tower wall, so that the boundary layer flow in the upper zone of the cooling tower is enriched with energy with increasing flow cross-section and thus protected against detachment from the wall.
The body can be adapted in accordance with the technical data and construction of the cooling tower in an optimum manner and indeed having regard to its size, number, geometry and position of construction. In the simplest case the body is constructed as an annular member concentric with the cooling tower wall, preferably with a circular cross-section.
In place of a closed ring a plurality of individual insert bodies of arcuate form can be mounted along an imaginary ring within the cooling tower.
Each insert body is preferably delta-shaped with the tips directed in the opposite sense to the direction of flow of the cooling air and placed at any acute angle to the flow direction. By this means there is produced an edge length, which has a component extending both in the flow direction of the cooling air and also transversely thereto and generates powerful vortices by the incidentflowofthe cooling air, which broadens out in the direcion of flow of the cooling air and has a predetermined flow components transverse to the flow direction of the cooling air. As a result of this, energy-weak air particles from the wall are transported away and are replaced by energetic air particles from the core flow of the cooling tower.
The delta-shaped bodies can either be mounted radially or tangentially on the wall of the cooling tower. Furthermore, it is possible to accommodate the delta-shaped bodies in several rows and offset from one another overthe height orthe crosssection plane of the cooling tower. The possibility also arises of changing the position and the mounting of the bodies in dependence upon different operational conditions of the cooling tower.
According to the invention there is provided a method of stabilising the peripheral air flow in a cooling tower providing a flow cross-section in the direction of flow of the cooling air which converges in a lower zone and diverges in an upper zone, comprising the step of mounting on the inner wall surface of the cooling tower at least one vortexgenerating body of such configuration and so positioned as to lead energy from the flow in the central region of the cooling tower and uninfluenced by wall friction into the region of the boundary layer flow.
According to the invention, there is further provided a cooling tower having a wall defining a cooling passage which in cross-section first converges and then diverges in the direction of airflow therealong and at least one body mounted in the wall downstream ofthe heat-exchange devices of the cooling tower, the body being located in the zone of the narrowest air cross-section of the cooling passage in the region of the cooling tower wall.
According to the invention, there is still further provided a method of stabilising the peripheral flow of cooling air in a cooling tower defining a cooling passage having a neck region, the method comprising the steps of diverting the air flow from a region remote from the wall in the neck region towards the wall in the neck region whereby to augment the flow in the boundary layer of air in the neck region, with air flow substantially uneffected by wall friction.
According to the invention, there is yet further provided a cooling tower comprising a wall defining a cooling passage with a neck region, and at least one body mounted on the wall in the neck region, the body being of such configuration and so located as to direct air flow from a region in the passage remote from the wall and substantially uneffected by wall friction to augment the flow in the boundary layer of air along the wall in the neck region.
A cooling tower and a method for stabilising the boundary flow in a cooling tower, both embodying the invention, will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which:
Figure 1 is a partial section through a hyperbolic cooling tower with a vortex-generating body inserted in the narrowest flow cross-section;
Figure 2 is a side elevation of a cooling tower including a first embodiment of the body;
Figure 3 is a plan view of one half of the cooling tower of Figure 2;
Figure 4 is a diagram of the temperature distribution at the mount of the cooling tower of Figure 2 without the body;
Figure 5 is a diagram corresponding to Figure 4 for a cooling tower with bodies according to Figures 2 and 3;
Figure 6 is a side elevation of a cooling tower including a second embodiment of the body;;
Figure 7 is a plan view of approximately one half of the cooling tower of Figure 6;
Figure 8 is a side elevation of a cooling tower with bodies staggered over the height of the tower;
Figure 9 is a side elevation of a further cooling tower with bodies staggered over the cross-sectional plane;
Figure 10 is a plan view of one half of the cooling tower of Figure 9;
Figure ii is a side elevation of a cooling tower incorporating yet another embodiment of the body; and
Figure 12 is a plan view of one half of the cooling tower of Figure 11.
Figure 1 shows the upper part of a hyperbolic cooling tower having a cooling tower wall 1 defining a cooling passage having a neck region. As indicated the flow direction of the cooling air converges up to the narrowest cross-section or neck region 2 and subsequently diverges in the manner of a diffuser.
The upwardly-directed flow of the cooling air is decelerated on the inner side of the cooling tower wall, so that it produces over the flow cross-section of the cooling tower the velocity profile for the cooling air indicated below the narrowest crosssection 2. The velocity of the inner face of the cooling tower wall is substantially equal to zero.
In order to act against any increase in this flow boundary layer, the thickness of which increases with increasing path length of the flow along the cooling tower wall 1, and to prevent the detachment -- of the flow cross-section from the cooling tower wall 1, a series of circumferentially arranged bodies 3 are mounted on the inner face of the wall 1 in the zone of the narrowest flow cross-section 2. Each body is delta-shaped having a tip which is directed in the opposite direction to the direction of flow of the cooling air and positioned to make an acute angle to the flow direction of the cooling air. By this means there is produced an edge locus of the delta-shaped body 3, which has components both in the flow direction of the cooling air and also components extending transversely thereto.This edge locus generates a strong vortex 4 broadening or widening in the direction of flow of the cooling air, which has flow components transverse to the direction of flow of the cooling air and carries away energy-poor air particles from the cooling tower wall 1 and replaces them by energy-rich air particles from the core flow in the central region of the cooling tower. By this means the boundary layer flow at the inner surface of the cooling tower wall is supplied with energy from the central zone of the cooling tower uninfluenced by the effect of wall friction on the flow.The velocity distribution in the upper half of the vortex 4 illustrated in Figure 1 indicates accordingly that even in the zone of the boundary layer flow directly adjacent the cooling tower wall 1, a predetermined outwardly directed velocity is provided, so that the boundary layer flow and the layers adjacent the wall are again in such a position that they can overcome external disturbances. In particularthey can follow a pressure rise without fear of detachment from the cooling tower wall and can displace pockets of cold air by self impulse.
In the cooling tower illustrated in Figures 2 and 3 a total of twelve delta-shaped insert bodies 3 are mounted in the zone of the narrowest cross-section tangentially on the cooling tower wall. (see Figure 3).
The effect of these insert bodies 3 has been explained with reference to Figure 1.
Figure 4 is a diagram, of the temperature difference between the cooling air in the internal part of the cooling tower and the outer air in the zone of the cooling tower outlet along the diameter dof a cooling tower in which the bodies 3 are omitted. As shown in Figure 4 there occurs at the right-hand side of the cooling tower a cold air intrustion. Such a cold air intrusion is prevented when the bodies 3 illustrated in Figures 2 and 3 are mounted in the tower as the diagram shown in Figure 5 indicates. The bodies 3 thus prevent the intrusion of cold air by an energy enrichment of the boundary layer flow as illustrated by the comparative temperature distribution over the whole of the flow cross-section of the cooling tower in the region of the cooling tower mount (see
Figure 5).
Instead of mounting the bodies 3 tangentially as shown in Figures 2 and 3 the delta-shaped bodies 5 can also be mounted radially in the cooling tower, as shown in Figures 6 and 7. Also as shown in Figure 8 the tangentially mounted bodies 3 can be staggered over the height of the cooling tower. Figures 9 and 10 show delta-shaped bodies 5 staggered in a cross-sectional plane.
In the hyperbolic cooling tower, instead of a plurality of bodies a single body in the form of a torus 6 is mounted in the zone of the narrowest cross-section 2. This torus 6 which is concentric with the cooling tower wall 1 generates vortices, which lead energy from the central zone of the cooling tower uninfluenced by wall friction into the boundary layer flow of the cooling tower at the inner surface of the cooling tower wall and thus effects a stabilisation of the peripheral flow in the cooling tower.
Claims (14)
1. A method of stabilising the peripheral air flow in a cooling tower providing a flow cross-section in the direction of flow of the cooling air which converges in a lower zone and diverges in an upper zone, comprising the step of mounting on the inner wall surface of the cooling tower at least one vortex-generating body of such configuration and so positioned as to lead energy from the flow in the central region of the cooling tower and uninfluenced by wall friction in the region of the boundary layer flow.
2. A method according to claim 1, wherein the edges of the body are so arranged as to generate widening vortices in the direction of flow of the cooling air with flow components extending transversely to the flow direction of the cooling air.
3. A cooling tower having a wall defining a cooling passage which in cross-section first converges and then diverges in the direction of air flow therealong and at least one body mounted in the wall downstream of the heat-exchange devices of the cooling tower, the body being located in the zone of the narrowest flow cross-section of the cooling passage in the region of the cooling tower wall.
4. A tower according to claim 3, wherein the body is in the form of an annular member arranged to lie concentric with the cooling tower wall.
5. A tower according to claim 4, wherein the annular member is in the form of a torus.
6. A tower according to claim 3, including a plurality of said bodies arranged circumferentially of the wall.
7. A tower according to claim 6, wherein each body is of delta configuration with one tip directed in a direction opposite to the direction of flow of the cooling air and makes an acute angle of incidence to the flow direction of the cooling air.
8. A tower according to claim 7, wherein each delta shaped body extends radially of the cooling tower.
9. A device according to claim 7, wherein each delta shaped body extends tangentially of the cooling tower.
10. A tower according to claim 8 or to claim 9, wherein the delta-shaped bodies are arranged in several rows and are offset over the height or over the cross-sectional plane of the cooling tower.
11. A method of stabilising the peripheral flow of cooling air in a cooling tower defining a cooling passage having a neck region, the method comprising the step of diverting the air flow from a region remote from the wall in the neck region towards the wall in the neck region whereby to augment the flow in the boundary layer of air in the neck region, with air flow substantially uneffected by wall friction.
12. A cooling tower comprising a wall defining a cooling passage with a neck region, and at least one body mounted on the wall in the neck region, the body being of such configuration and so located as to divert air flow from a region in the passage remote from the wall and substantially uneffected by wall friction to augment the flow in the boundary layer of air along the wall in the neck region.
13. A method of stabilising the peripheral flow of cooling air in a cooling tower substantially as hereinbefore described, with reference to any one of
Figures 1 to 3 and 5 to 12 of the accompanying
drawings.
14. A cooling tower substantially as hereinbefore
described with reference to any one of Figures 1 to 3
and 5 to 12 of the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3023982A DE3023982C2 (en) | 1980-06-26 | 1980-06-26 | Device for stabilizing the edge flow in a cooling tower |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2078358A true GB2078358A (en) | 1982-01-06 |
| GB2078358B GB2078358B (en) | 1984-07-25 |
Family
ID=6105551
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8118048A Expired GB2078358B (en) | 1980-06-26 | 1981-06-12 | A cooling tower and method for the stabilisation of the boundary flow in the cooling tower |
Country Status (7)
| Country | Link |
|---|---|
| BR (1) | BR8104001A (en) |
| DE (1) | DE3023982C2 (en) |
| ES (1) | ES503390A0 (en) |
| FR (1) | FR2485713A1 (en) |
| GB (1) | GB2078358B (en) |
| IT (1) | IT1138417B (en) |
| ZA (1) | ZA814140B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1986005577A1 (en) * | 1985-03-16 | 1986-09-25 | Saarbergwerke Aktiengesellschaft | Smoke gas exhaust by way of a cooling tower |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4231813C2 (en) * | 1992-09-23 | 1997-05-07 | Gea Energietechnik Gmbh | Natural draft cooling tower |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2123220A1 (en) * | 1971-05-11 | 1972-11-23 | Brandi Ingenieurgesellschaft mbH, 5020 Frechen | Method and device for operating a recooling plant or cooling tower |
| FR2275744A1 (en) * | 1974-06-19 | 1976-01-16 | Hamon Sobelco Sa | AIR DEFLECTOR FOR ATMOSPHERIC REFRIGERANT, ESPECIALLY FOR MIXED WET-DRY REFRIGERANT |
| FR2360059A1 (en) * | 1976-07-26 | 1978-02-24 | Chausson Usines Sa | Natural draught dry cooling tower - has control flaps fitted across tower outlet and inlet to modify draught and vary cooling capacity |
| DE2911873C2 (en) * | 1979-03-26 | 1982-08-19 | Balcke-Dürr AG, 4030 Ratingen | Cooling tower |
| FR2456297A1 (en) * | 1979-05-09 | 1980-12-05 | Hamon Sobelco Sa | TRIANGULAR DEFLECTOR DEVICE FOR MIXING DRY AND WET FLOWS OF MIXED ATMOSPHERIC REFRIGERANT WITH PARALLEL AIR FLOWS |
| DE2925461C2 (en) * | 1979-06-23 | 1982-06-09 | Balcke-Dürr AG, 4030 Ratingen | Method and device for stabilizing the edge flow at the outlet of a cooling tower |
-
1980
- 1980-06-26 DE DE3023982A patent/DE3023982C2/en not_active Expired
-
1981
- 1981-06-12 GB GB8118048A patent/GB2078358B/en not_active Expired
- 1981-06-16 IT IT22345/81A patent/IT1138417B/en active
- 1981-06-18 ZA ZA814140A patent/ZA814140B/en unknown
- 1981-06-25 BR BR8104001A patent/BR8104001A/en unknown
- 1981-06-25 FR FR8112512A patent/FR2485713A1/en active Pending
- 1981-06-25 ES ES503390A patent/ES503390A0/en active Granted
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1986005577A1 (en) * | 1985-03-16 | 1986-09-25 | Saarbergwerke Aktiengesellschaft | Smoke gas exhaust by way of a cooling tower |
| US4784810A (en) * | 1985-03-16 | 1988-11-15 | Saarbergwerke Aktiengesellschaft | Smoke gas exhaust by way of a cooling tower |
| US4885011A (en) * | 1985-03-16 | 1989-12-05 | Saarbergwerke Aktiengesellschaft | Cooling tower for the cooling water that drains/ from the condensor of a steam generator or the condensors/ of a plurality of steam generators |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2485713A1 (en) | 1981-12-31 |
| IT1138417B (en) | 1986-09-17 |
| DE3023982A1 (en) | 1982-01-14 |
| IT8122345A0 (en) | 1981-06-16 |
| ES8301357A1 (en) | 1982-12-01 |
| BR8104001A (en) | 1982-06-15 |
| ZA814140B (en) | 1982-07-28 |
| ES503390A0 (en) | 1982-12-01 |
| DE3023982C2 (en) | 1982-08-26 |
| GB2078358B (en) | 1984-07-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3123285A (en) | Diffuser with boundary layer control | |
| CA1204412A (en) | Inertial particle separator | |
| CA1327948C (en) | Vortex tube separating device | |
| US4175640A (en) | Vortex generators for internal mixing in a turbofan engine | |
| US5365731A (en) | Efficient anti-ice exhaust method | |
| US8047777B2 (en) | Turbomachine diffuser | |
| US3593518A (en) | Combustion chambers for gas turbine engines | |
| JPH0678735B2 (en) | Nacelle structure | |
| US5876182A (en) | Apparatus and method for preventing laminar boundary layer separation on rotor blades of axial turbomachinery | |
| EP1424526B1 (en) | Fuel nozzle | |
| EP0018840B1 (en) | Separator for removing entrained moisture from saturated steam in a nuclear steam generator | |
| US8221080B2 (en) | Method for improving the flow conditions on the propeller or fan of an aircraft engine and accordingly designed hub cone | |
| US5415114A (en) | Internal air and/or fuel staged controller | |
| US4899772A (en) | Mixing aids for supersonic flows | |
| IL43401A (en) | Aircraft system lift ejector | |
| US3703800A (en) | Humid de-dusting device for gas-conveyor conduits | |
| GB2078358A (en) | A cooling tower and a method for the stabilisation of the boundary flow in the cooling tower | |
| US4335995A (en) | Set of blades for a turbine and a turbine which includes such a set of blades | |
| US3817690A (en) | Combustion devices | |
| US4261517A (en) | Atomizing air metering nozzle | |
| US4648354A (en) | Steam generating apparatus having a feedwater header | |
| US3610775A (en) | Turbine wheel | |
| US4878785A (en) | Abrasive fluid flow | |
| EP3354849A1 (en) | Wall of a hot gas part and corresponding hot gas part for a gas turbine | |
| US3477358A (en) | Inspirator ventilator |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |