GB1600521A

GB1600521A - Cooling tower

Info

Publication number: GB1600521A
Application number: GB14849/78A
Authority: GB
Original assignee: Lummus Co
Current assignee: CB&I Technology Inc
Priority date: 1977-04-18
Filing date: 1978-04-14
Publication date: 1981-10-14
Also published as: HU184162B; BR7802262A; DE2816293A1; NL7802825A; JPS53131551A; FI65377C; ZA781028B; JPS5624189B2; CA1075025A; IT7848445A0; IT1104110B; FR2388235B1; FR2388235A1; DE2816293C2; FI780630A; FI65377B

Description

(54) IMPROVEMENTS IN OR RELATING TO A COOLING TOWER (71) We, THE LUMMUS COMPANY, a Corporation organised and existing under the Laws of the State of Delaware, United States of America, of 1515 Broad Street, Bloomfield, New Jersey, 07003, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to cooling towers, and more particularly to cooling towers in which tubular heat exchangers are arranged whereby fluid flowing through the tubes is indirectly cooled by air flow through the tower.

According to this invention there is provided a cooling tower comprising a hollow tower including means for introducing air into a lower portion of the tower and means for withdrawing air from the top of the tower, a plurality of heat exchangers positioned inwardly from the tower wall and circumferentially arranged to form at least two radially spaced heat exchanger rings, the heat exchanger surfaces of each said heat exchanger ring lying substantially vertically to form a ring wall, and air directing means for directing air introduced into the tower through the heat exchangers.

The means for withdrawing air from the top of the tower is preferably a hole in the top of the tower. The heat exchangers of each ring are preferably arranged so that the heat transfer surfaces thereof form concentric cylindrical heat transfer walls.

The spacing between the rings and/or the height of the exchangers are co-ordinated to provide the required ratio of heat transfer surface to air flow area and sufficient area for airflow to the heat transfer surface.

The heat exchangers are provided with suitable air directing means for directing air which is introduced into the tower through the heat exchangers. The air directing means is preferably in the form of a plurality of air shields which extend between adjacent rings of heat exchangers, with the shields being upwardly inclined from the tower periphery to the tower centre. The air shields extend from the bottom of the exchanger of one ring to the top of the exchanger of the next inner ring. The exchangers and shields are arranged so that the air shield inclination corresponds to the tangent to the average direction of air flow through the tower to thereby reduce parisitic losses.

In order that the invention may be more readily understood and so that further features thereof may be appreciated the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a schematic sectional view of an embodiment of the present invention; Figure 2 is a partial section in elevation of the embodiment of Figure 1; Figure 3 is a partial top sectional view taken along line 3-3 of Figure 1; Figure 4 is a partial section along line I 4 of Figure 2; Figures 5a, 5b and Sc are schematic representations of various ring configurations; and Figure 6 is a schematic representation of an embodiment including a modified air directing shield.

Referring to the drawings, there is shown a hollow cooling tower in the form of a natural draught hyperbolic cooling tower 10, having inlets 11 through which cooling air flows, by natural draught or convection, from the surrounding atmosphere. It is to be understood that the tower could be of the forced air type or could be a natural draught tower with a shape other than hyperbolic i.e., cylindrical or flared.

The lower interior of the cooling tower 10 is provided with a plurality of heat exchangers 21, each of which has a heat exchanger surface 22 in the form of tube bundle having a plurality of tubes 23. The tubes 23 may be horizontal or vertical tubes, and as particularly shown, the tubes are horizontal. As known in the art, the tubes 23 of each exchanger are suitably arranged to permit air flow through the exchanger so that fluid flowing through the tubes is cooled by such air flow.

The heat exchangers 21 are circumferentially arranged to form radially spaced rings 24a, 24b, 24c, 24d and 24e, with the heat transfer surfaces 22 thereof forming substantially vertical ring walls.

As particularly shown, the heat exchanger surfaces of bundles 22 are arranged along tangent planes of concentric vertical cylinders whereby the heat exchanger surfaces define concentric generally vertical substantially cylindrical heat transfer walls.

Air directing means in the form of a plurality of flat shields 26 are provided for each ring of heat exchangers to prevent air from flowing upwardly through the spaces between the heat exchanger rings and thereby direct air through the heat exchangers of each ring. The air shields for each ring are tapered in width from bottom to top and are arranged around the ring coextensive with the heat exchanger surfaces of the ring. The shields 26 interconnect adjacent heat exchanger rings and are downwardly inclined from the top of the heat exchangers of a ring, to the bottom of the heat exchangers of the next outer ring.Each heat exchanger of a ring is preferably individually provided with an air shield 26, although it is possible to provide individual air shields which act as air directing means for two or more exchangers of a ring, or to provide a plurality of shields for each exchanger in the ring. The air shields 26 for the outer ring of exchangers extend downwardly from the top of the exchangers of the outer ring 24e to the tower wall.

The air shields 26 are positioned at an angle to approximate the direction of air flow which occurs in the cooling tower 10 to reduce parasitic losses. The proper inclination of the shields, such that they approximate the tangent to the average direction of air flow which occurs in tower 10, can be obtained by proper arrangement of the elevation of the cylindrical heat transfer walls with respect to each other the diameters of the heat exchanger rings and/or the height of the heat exchangers.

The air shields 26 for the outer ring of heat exchangers eliminates the ineffective zone at the lintel of the tower by guiding the air which is normally detached at the lintel through the outer ring of heat exchangers.

The heat exchangers 21 generally have a rectangular shape and are positioned with the longer dimension as the height, i.e., the height of each exchanger 21 is greater than its width. It is to be understood, however.

that the arrangement could be otherwise, although such an arrangement is preferred.

The overall geometry for arranging the concentric cylindrical heat exchanger surfaces can vary. Thus, the respective concentric heat exchange ring elevations can be arranged to provide a hyperbolic bundle geometry (Fig. 5a), a parabolic bundle geometry (Fig. 5b) or a single level bundle geometry (Fig. 5c). It is to be understood that other geometries are also possible.

Similarly, it is possible to select an economic tube bundle height and appropriately adjust the number of rings and distances therebetween to provide a required total bundle surface for a given tower diameter.

Similarly, the required ratio of bundle surface to airflow area can be maintained over the entire tower cross-section by increasing the distance between heat exchanger rings toward the tower centre while keeping the height of each bundle constant, or by decreasing the bundle height towards the tower centre while maintaining a constant distance between rings.

The heat exchangers of each ring 24a, 24b, 24c, etc. are conveniently supported within the tower on ringbeams 31 which are supported by suitable circumferentially spaced columns 32.

The heat exchangers 21 of each ring can be conveniently provided with a fluid to be cooled or condensed through a ring manifold 41 for the heat exchanger ring, which is appropriately connected to a vertical inlet manifold 42 for each heat exchanger 21 of the heat exchanger ring.

Similarly cooled fluid can be withdrawn from each heat exchanger of a heat exchanger ring through an outler ring manifold 43 which is appropriately connected to the outlet manifold 44 of each exchanger.

A fluid inlet pipe 45 is connected to each ring manifold through suitable interconnecting piping 56 which preferably includes suitable valving 47 whereby one or more rings can be selectively taken out of operation, while maintaining symmetrical air flow pattern through the remaining rings of heat exchangers. Suitable outlet piping (not shown) and interconnecting piping (not shown) are provided for withdrawing fluid from the outlet manifold rings 43.

Air flow can be controlled through the heat exchanger rings by providing movable air shield means which can be moved between a position which directs air flow through the exchanger and a position which prevents air from flowing through the exchanger. An example of such an embodiment is schematically illustrated in Figure 6.

Referring to Figure 6, the air shield 51 is divided into a stationary upper part 52 and a movable part 53, with the lower part having length sufficient to cover the distance between two rings of heat exchangers. The lower part 53 is suitably hinged to the supporting ringbeam 31 and can be moved by suitable hinge actuator 54, which can be a hydraulic, pneumatic or mechanicalelectric actuator. In the lower position, the lower portion 53 of air shields 51 effectively blocks air flow to its ring of exchangers 21.

In the upper position, the air shields function to direct air to their respective ring of exchangers.

The movable air shield can be employed to take one or more rings of exchangers or one or more exchangers of a ring out of operation by blocking air flow thereto. In addition, the shields can be effectively employed to control air flow under freezing conditions. Thus, air flow can be stopped to the heat exchangers of a ring by lowering the lower portions of the air shields for that ring, whereby the heat exchangers of that ring are in the warm-airside of the tower and the hot fluids in the tube are not rapidly cooled and do not freeze.

Although the invention has been described with respect to a specific embodiment thereof, the scope of the invention in not limited thereby. Thus, for example, although the heat exchanger ring walls are preferably in the form of a cylinder, such ring wall could have another form. Thus, for example, the ring walls could have a generally conical shape with the walls being downwardly inclined from the tower wall to the tower centre.

Similarly, although the tubes of the exchangers are shown as U-shaped tubes, straight tubes could be employed. Similarly, the tubes may be vertical rather than horizontal.

WHAT WE CLAIM IS: 1. A cooling tower comprising a hollow tower including means for introducing air into a lower portion of the tower and means for withdrawing air from the top of the tower, a plurality of heat exchangers positioned inwardly from the tower wall and circumferentially arranged to form at least two radially spaced heat exchanger rings, the heat exchanger surface of each said heat exchanger ring lying substantially vertically to form a ring wall, and air directing means for directing air introduced into the tower through the heat exchangers.

2. A cooling tower according to claim 1 wherein the means for withdrawing air from the top of the tower comprises a hole at the top of the tower.

3. A cooling tower according to claim I or claim 2, wherein the heat exchangers are arranged to form concentric cylindrical heat exchanger surface walls.

4. A cooling tower according to any one of claims 1 to 3, wherein the air directing means is comprised of flat air shields for each heat exchanger ring, the air shields being downwardly inclined from the tower centre and extending between adjacent heat exchanger rings, with the air shields for the outer heat exchanger ring extending to the tower wall.

5. A cooling tower according to claim 4, wherein the air shields are inclined at an angle to approximate natural air flow through the tower.

6. A cooling tower according to any one of the preceding claims, wherein the heat exchangers have a greater height than width.

7. A cooling tower according to any one of the preceding claims, wherein there is a plurality of rings of heat exchangers which extend to a progressively higher elevation from the inner ring to the outer ring.

8. A cooling tower according to any one of the preceding claims, wherein each heat exchanger surface is formed from a plurality of tubes.

9. A cooling tower according to claim 8, wherein the plurality of tubes are vertical tubes.

10. A cooling tower according to claim 8, wherein the plurality of tubes are horizontal tubes.

11. A cooling tower according to claim 3 or any claim dependent thereon, wherein the heat exchangers are arranged along tangent planes of concentric vertical cylinders to form said cylindrical heat exchanger surface walls.

12. A cooling tower according to claim 4 or any claim dependent thereon, wherein the air shields are tapered in width from bottom to top.

13. A cooling tower according to claim 4 or any claim dependant thereon, wherein at least some of said air shields are comprised of a fixed upper part and a movable lower part, said lower part having length to cover the distance between heat exchanger rings, said movable lower part being movable between an open position which directs air through the heat exchangers and a closed position which blocks air flow to the heat exchangers.

14. A cooling tower according to any one of the preceding claims, wherein the cooling tower is a natural draught tower.

15. A cooling tower according to any one of the preceding claims, wherein there is a plurality of heat exchanger rings with the spacing between heat exchanger rings increasing towards the centre of the tower.

16. A cooling tower according to any one of claims 1 to 14, wherein there is a plurality

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Referring to Figure 6, the air shield 51 is divided into a stationary upper part 52 and a movable part 53, with the lower part having length sufficient to cover the distance between two rings of heat exchangers. The lower part 53 is suitably hinged to the supporting ringbeam 31 and can be moved by suitable hinge actuator 54, which can be a hydraulic, pneumatic or mechanicalelectric actuator. In the lower position, the lower portion 53 of air shields 51 effectively blocks air flow to its ring of exchangers 21. In the upper position, the air shields function to direct air to their respective ring of exchangers. The movable air shield can be employed to take one or more rings of exchangers or one or more exchangers of a ring out of operation by blocking air flow thereto. In addition, the shields can be effectively employed to control air flow under freezing conditions. Thus, air flow can be stopped to the heat exchangers of a ring by lowering the lower portions of the air shields for that ring, whereby the heat exchangers of that ring are in the warm-airside of the tower and the hot fluids in the tube are not rapidly cooled and do not freeze. Although the invention has been described with respect to a specific embodiment thereof, the scope of the invention in not limited thereby. Thus, for example, although the heat exchanger ring walls are preferably in the form of a cylinder, such ring wall could have another form. Thus, for example, the ring walls could have a generally conical shape with the walls being downwardly inclined from the tower wall to the tower centre. Similarly, although the tubes of the exchangers are shown as U-shaped tubes, straight tubes could be employed. Similarly, the tubes may be vertical rather than horizontal. WHAT WE CLAIM IS:

1. A cooling tower comprising a hollow tower including means for introducing air into a lower portion of the tower and means for withdrawing air from the top of the tower, a plurality of heat exchangers positioned inwardly from the tower wall and circumferentially arranged to form at least two radially spaced heat exchanger rings, the heat exchanger surface of each said heat exchanger ring lying substantially vertically to form a ring wall, and air directing means for directing air introduced into the tower through the heat exchangers.

of heat exchanger rings with the heat exchanger height of each ring decreasing toward the tower centre.

17. A cooling tower substantially as herein described with reference to and as shown in Figures 1 to 4 as modified by Figure drawings.

18. A cooling tower substantially as herein described with reference to and as shown in Figuresl to 4 as modified by Figure 5a.

19. A cooling tower substantially as herein described with reference to and as shown in Figures 1 to 4 as modified by Figure 5b.

20. A cooling tower substantially as herein described with reference to and as shown in Figures 1 to 4 as modified by Figure 5c.

21. A cooling tower substantially as herein described with reference to and as shown in Figure 6.