JPS5821194B2 - Ryuutaioreikiyakusuruhouhou Oyobi Souchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluid cooling method and a fluid cooling tower, and in particular to a fluid cooling tower that is capable of maintaining its operating characteristics regardless of the wind direction and that has a high fan-equipped chimney or a natural draft type. The present invention relates to a circular mechanical draft type cooling tower that eliminates the need for chimneys, thus minimizing tower design cost and minimizing recirculation of hot air.

In some countries, natural draft water cooling towers are designed to transport water from the surrounding atmosphere to a fill assembly or dry surface exchanger that exchanges heat between the hot water that falls downward by gravity into the fill and the cooling air. It has been used for many years to circulate air.

Although natural draft towers having relatively long chimneys to provide a full chimney effect are effective and do not require power to operate the fans, natural draft cooling towers are relatively expensive to manufacture.

Natural-draft cooling towers with tall stacks also include a dry surface heat exchanger or fill assembly around the entire perimeter of the base of the tower so that its operation is relatively independent of wind direction. It also has the advantage of being easy to install.

This advantage is due to the recirculation of the hot air discharged from the natural draft tower to the dry surface heat exchanger or fill assembly at the base of the chimney, since the point of discharge of the hot air to the atmosphere is high. , stems from the fact that it is minimized.

In order to provide sufficient stack effect to guarantee air flow through the dry heat exchanger or fill assembly of the tower even under the most difficult ambient temperature and loading conditions encountered in the special application. Since natural draft chimneys must be relatively tall, it has been found that it is optimal to manufacture a three-dimensional hyperbolic chimney for structural strength or rigidity.

Generally, concrete is used as the material for making chimneys.

This is because concrete is strong and easily forms complex curved shapes that define hyperbolic units.

Natural draft hyperbolic fluid or liquid cooling towers are expensive to manufacture, so from an economic point of view they can only be used in the case of large heat loads and with limited space and area for the manufacture and operation of towers of this character. It can only be used in areas where it is technically available.

For example, chimneys suitable for use in hyperbolic natural draft cooling towers and especially currently manufactured cooling towers have heights of several hundred feet (30-90 m) and correspondingly large base diameters. .

Mechanical draft-type fluid or liquid cooling towers (using motor-operated fans to induce air flow through dry surface heat exchangers or fill assemblies) are widely used commercially. , and are manufactured and used based on many important factors.

The most important of these factors is its favorable price due to its characteristics.

Mechanical draft towers can be sized to handle special heat loads at minimal cost and configured to meet special geographic (area) requirements.

In the case of evaporative water cooling towers, mechanical ventilation type cross-flow type (
Water cooling towers (cross-flow type) are advantageous over other types of mechanical draft towers because of their combination of more ideal fluid flow characteristics and lower pressure drop due to high cooling surface area. This is what I have learned from many years of experience.

However, for the most effective operation of mechanical draft towers, whether cross-flow or counterflow, the hot, moist air discharged from the tower must Recirculation back to the fill must be minimized.

This is especially true for the lower portion of the fill assembly where the ultimate cooling effect is caused by contact between the coldest water and the surrounding air.

Therefore, if the hot humid air discharged from the tower is to be recirculated, the tower must be sized larger than the required design dimensions to obtain the cooling water temperature.

The problem of recirculating hot, humid air is sometimes exacerbated by problems associated with the direction of the ambient airflow blowing toward one face of the tower.

For example, mechanically ventilated cross-flow water cooling towers, which are currently popular, are designed in a roughly rectangular shape, with inlets on large opposing surfaces of the tower, and a large number of fans projecting upwardly from the top of the casing of the tower, these fans communicate with the moist air pressure chamber (fill chamber) of the tower and draw air from the surrounding atmosphere to feed the tower. The aspirated air is moved through the fill assembly on opposite sides in intersecting relation with the water falling downward by gravity within the fill assembly, and then each horizontally located power-operated fan is moved. It operates to discharge moist, hot air vertically from the tower through a corresponding surrounding velocity recovery cylinder.

To minimize the recirculation of hot moist air released from the tower through the fan cylinder, the cylinder (chimney ) is as high as possible.

However, raising the height of the chimney creates cost and design problems.

If a sufficiently tall cylinder is not used in a rectangular type water cooling tower, recirculation of hot moist air may not be effectively reduced.

The reason is that the wind flow blowing towards the base during the operation of the tower under normal conditions has strong turbulence on the leeward side of the tower and a large This is because they tend to produce wake regions characterized by swirls.

These wake areas occur not only along the leeward upright side edge of the tower, but also along the upper horizontal edge of the tower.

The reduced pressure zone on the lee side of the tower naturally tends to draw the discharge fluid from the inclined discharge fluid column (due to the wind) into the wake zone, thus immediately following the discharge of air from the tower fan cylinder. tend to cause recirculation of moist, hot air back through the air.

As is well known, the tendency of hot, humid air to be drawn into the swirl area below the tower is such that ambient winds deflect the emitted discharge column towards the wake area on the leeward side of the tower. It is increased by the fact that it is put away.

This same limiting factor can be applied to rectangular-type air-cooled dry surface liquid or It can equally be applied to fluid cooling towers.

Moreover, the extremely expensive mechanically ventilated fan cylinders are expensive to assemble.

Technical problems that arise from the point of view of mounting a cylinder on top of a mechanically ventilated tower include being subjected to stress-inducing winds, and the use of internal spiders or similar structures to increase the structural stiffness of the cylinder. These include the fact that the cylinder must be supported by reinforcing aggregate and that it does not flex under heavy wind loads.

It is therefore a primary object of the present invention to provide a practical and economical solution to many of the aforementioned problems encountered in the installation of circular mechanically ventilated cross-type dry fluid cooling towers. .

The cooling tower described above operates with equal efficiency regardless of the wind direction;
The advantage of having multiple fans arranged in clusters and mounted for rotation in corresponding air velocity recovery cylinders is that the circulation of hot air can be minimized.

The air velocity recovery cylinder releases hot air from the tower in the form of a concentrated air column, so that the wind flow first impinges on this air column and significantly deflects the upwind part of the air column, but the leeward side of the air column is deflected considerably. There is no tendency to bend parts.

As such, the tendency to circulate hot air back into the tower air inlet is virtually reduced or completely eliminated.

A further important object of the present invention is to provide a circular mechanical draft multi-fan fluid cooling tower, particularly one useful for cooling fluids where precise temperature control is essential or desired. That's true.

In this case, the number of fans actually activated can be adjusted to accommodate the ambient temperature or There is no problem in sequentially decreasing the number of units, such as decreasing the number of units.

In a similar manner, multiple fans may be used that can operate at full speed, half speed, or even full stop to provide more effective temperature control of the fluid being cooled.

Yet another object of the present invention is to provide a circular dry multi-fan fluid cooling tower with heat exchangers arranged in a cylindrical shape for rapid fluid discharge.

Therefore, when this cooling tower is used for cooling liquids such as water, the liquid is easily and quickly drained from the system, so that the cooling tower is operating under abnormally low temperature conditions or low temperatures. In some cases, freezing of the tower can be prevented without loss of heat load on the tower.

A further important object of the present invention is to minimize the size of the column by creating a cylindrical shape (actually formed by a series of flat heat exchange modules of polygonal shape approximating a cylindrical shape). It is an object of the present invention to provide a circular multi-fan type dry fluid cooling tower equipped with a dry heat exchanger that minimizes the number of elements constituting the tower.

The number of heat exchanger elements can be reduced because the casing wall can be eliminated and many other parts normally required in conventional square columns can be omitted.

The ultimate object of the present invention is to provide a circular mechanical ventilation type dry heat exchanger having a circular dry heat exchange structure with fans installed in clusters inside the periphery and cylinders cooperating with the fans. The purpose is to provide cooling towers.

This heat exchange structure allows the use of relatively low fanned cylinders in order to minimize problems with economy and wind deflection, thereby allowing the use of towers with very tall fanned cylinders or chimneys. It is possible to provide a column with as low a degree of hot air recirculation as can be obtained.

A further important object of the present invention is to collect a large number of fans in a circular manner to direct a column of hot air into the atmosphere above the tower in a manner that minimizes the recirculation of hot air regardless of wind direction or speed. An object of the present invention is to provide a mechanical cross-flow air-drying fluid cooling tower with discharge.

The heat load that this type of tower can handle is limited only by the required footprint or equipment costs for a particular customer.

The reason is that if you want to handle a large heat load, you just need to make the tower larger.

In that case, it is sufficient to increase the number of fans in proportion to the increase in the diameter of the tower.

The present invention also provides that the round tower structure reduces the influence of the surrounding atmosphere compared to a rectangular tower, and that even areas of the terrain that happen to have a particular wind direction do not necessarily contain emissions due to the steady wind direction. This eliminates the need to take into account the effects of diffusion of cooling towers, so a mechanical cross-flow circular design that minimizes recirculation by hot air by concentrating a large number of adjacent cooling towers in a "square" is recommended. The purpose is to provide a dry fluid cooling tower.

Furthermore, the present invention minimizes depressurization due to the generation of vortices and turbulence on the leeward side directly below the tower by making the shape of the tower circular. To provide a mechanical interlacing source type dry fluid cooling tower in which the tendency of air to return to the mouth is reduced and discharged air flows out linearly on a diffusion flow toward the periphery of the tower.

The present invention also utilizes a plurality of fans and speed recovery cylinders concentrically arranged around the central axis of the tower to optimize the energy of the air discharged from the cylinders, reducing space, equipment costs, and cooling. It is the object of the present invention to provide a circular dry fluid cooling tower of a mechanically complex type that allows intensive consideration of practical capacity constraints; in this connection, the main focus of the present invention is to The fans and their cylinders were arranged in a number of concentric hexagons that occupied the main part of the tower fan deck, and other installation constraints made it difficult to use the hexagonal arrangement described above. In some cases, the fans and cylinders are arranged concentrically in a circular manner.

FIGS. 1 to 4 show four embodiments of a circular mechanically ventilated cross-flow water cooling tower according to the present invention, each numbered 10.
, 12, 14.16.

Each of the towers 12-16 is of substantially similar shape and performs a similar function, except that the diameter of the tower varies;
Each has a different arrangement of fan and cylinder structures.

Therefore, only the embodiment of FIG. 4 will be described in detail, and common structures in the embodiments of FIGS. 1 to 3 will be given the same numbers as corresponding structures in the embodiment of FIG. do.

Relatively shallow annular cold water collection tank 18 with an open top
has a circular bottom wall 20 connected to a vertical inner wall 22 of cylindrical shape and extending to the top of the tower, while a relatively low cylindrical outer wall 24 forms the outer edge of wall 20. There is.

As is common practice in the construction of relatively large industrial water cooling towers, the cold water storage tank 18 is preferably constructed of reinforced concrete.

A suitable concrete foundation is provided for the storage tank 18;
This foundation supports an annular frame unit 26 of reinforced concrete frame members 28 extending upwardly from the bottom wall 20, the frame members providing a trellis frame for a number of fill assemblies, and around the entire perimeter of the circular tower 16. It is equipped with an annular support structure that extends.

As best shown in FIG. 6, frame unit 26 includes a plurality of vertical frame members 28 extending between horizontal frames 286.
a to 28d, and the outermost inclined frame member 28
1-, which member 28f extends outwardly beyond the wall 24 of the reservoir 18 as it approaches the top of the frame unit.

The fill assembly 30 supported by the frame unit 26 may include a number of different configurations that increase the area for cooling the hot water as it descends downwardly through the fill assembly. However, in the preferred embodiment shown in FIG. 9, a series of wire materials or fiberglass reinforced composites such as polyester having vertical rod sections 32a interconnected by vertically spaced horizontal fill member support rods 32b are used. Resin material lattice 3
2 are mounted between the lattice frames in a suspended relationship from each horizontal frame member of the frame unit 26.

Horizontal portions 32b of the grid 32 placed vertically and spaced horizontally
The fill member 34 supported by the fill member 34 has a plurality of corrugated plates and also has a series of openings 34a & extending through the corrugations 34b of each member 34.

As best shown in FIG. 6, in one preferred arrangement of grid and fill members 34, the vertical rows of fill members are provided with continuous steps of fill units. It is offset inwardly into the tower to compensate for the tendency of water descending through the fill assembly to be drawn toward the inner plenum of the tower as it approaches the reservoir.

The vertical rows of fill members are also vertically offset from adjacent vertical rows.

6.7. To retain the water within the fill assembly 30 11, a long, relatively wide, reinforced concrete inlet shroud 38 is provided to prevent large amounts of water from splashing out from the interior of the tower. As shown in FIG. 8, it is provided on the outer surface of the frame unit 26 so as to bridge the individual lattice frames.

As shown in FIG.
The lower end of the armor plate is held on the frame member 28e, and the armor plate is held at the correct inclination at an angle of approximately 45° with respect to the horizontal.

Because the baffles are relatively wide, they can be spaced significantly apart in the vertical direction to minimize the pressure drop of the air flowing through the fill assembly 30 and into the column.

As shown in FIG. 6.7, the entrance armor plates 38 are stacked one on top of the other, and are inclined and spaced apart from each other in an overlapping relationship.

That is, water that falls by gravity from the lower edge of one armor plate falls onto the lower armor plate, and the water falls on the lowermost armor plate 38a.
is located above the reservoir inside the wall 24 of the cold water reservoir 18 so that water flowing from the lower edge of the shroud 38a returns to the reservoir 18.

A conventional removal plate 42 is provided across the vertical frame member 28a (FIG. 6) to remove water droplets contained in the air leaving the fill assembly 30 and entering the annular fill chamber 36.

The longitudinally inclined removal plate 42 is L-shaped so that the air leaving the fill assembly changes direction before entering the plenum chamber 36.

As a result, water droplets in the humid air come into contact with the removal plate 42 and are effectively removed from the air stream.

Although the removal plate 42 is shown in an upright position, it may be angled to match the angle of water withdrawal in the fill assembly 30 if desired.

An upper horizontal frame member 28g extending in the radial direction of the tower and supported by frame members 28a-28f supports an annular hot water distribution device generally indicated at 44.

4.6.7, the distribution device 44 is preferably made of reinforced concrete and has a series of side-by-side pie-shaped bottom portions 46 supported directly on the frame member 28g. .

The upright portion 48 that is integral with the bottom portion 46 is a frame member 28g.
, forming a generally circular element arranged in parallel and surrounding the periphery of the distribution device 44 and decreasing in diameter as it approaches the center of the tower 16 .

L-section end walls 50, 52, respectively connected to the outer and inner edges of the corresponding bottom portions 46, project upwardly from the dispensing device and define the outer and inner ends of the dispensing device.

Thus, the end wall 50.52 and the bottom portion 4 connected thereto.
6 provides a relatively shallow annular hot water distribution device (vessel) 44 open at the top, in which the end wall 52
is above the cold water reservoir 18, and the end wall 50 is external to the cold water reservoir wall 24 and aligned with the upper end of the adjacent frame member 28f.

Although not shown in detail in the drawings, the bottom portion 46 of the dispensing device 44
includes a series of orifices 54 arranged in a generally rectangular pattern for uniformly delivering hot water to the lower fill assembly 30 when the annular distributor 44 is filled to a predetermined depth with hot water to be cooled; has.

Each orifice 54 may be provided with a diffusion and distribution nozzle if more uniform delivery of water to the flats of the lower fill assembly 30 is desired.

The annular fan and cylinder support deck 56 is connected to No. 4.6.
As shown in FIG. 7, it is supported by the upper edge of the end wall 52 and the upper edge of the cylindrical inner wall 22 spaced therefrom.

The components of the distributor and the inner walls 22 and decking 56 can be made of a variety of materials, but in the illustrated embodiment reinforced concrete is the most satisfactory material from a strength and non-combustibility standpoint.

A series of upright, circumferentially spaced, radially extending bulkheads 57 below deck 56 support the deck and connect with wall 22 to divide air-filled chamber 36 into a series of adjacent individual bulkheads. It acts to divide into chambers.

The circular water cooling tower of the present invention is most effectively used for high heat loads, typically handling thousands of gallons of water per minute.

Therefore, they typically have a relatively large diameter when designed as a replacement for natural draft hyperbolic cooling towers of corresponding capacity.

For example, column 16 has a length of 60 to 120 m, and columns 10, 12.14 have a length of 120 to 180 m.

A large number of clustered fan units 58 (typically 10 to 18 for column 16 and 6 for column 10° 12.14)
0 or more) are passed through the air inlet face of the fill assembly to the surrounding area to effectively cool the water that exits the distributor reservoir 44 and passes under the action of gravity through the fill assembly toward the cold water reservoir 18. required to draw in sufficient air from the

In column 16, hot water distribution device 44 typically has 9
With an outside diameter of 6 m, the diameter of the cylindrical wall 22 is approximately 54 m, where 18 8.4 m fans filter outside air to effectively cool the hot water passing through the fill assembly. This is provided to ensure reliable introduction into the assembly.

Each of the fan units 58 includes a drive motor 60 supported on the deck 56, and the motor is connected to a drive shaft 62.
is connected to a reduction gear device 64 that supports a multi-blade fan 66 that rotates in a horizontal plane.

Each fan 66 is an upright acceleration cylinder 6 with open upper and lower ends.
The cylinder 68 is rotatable within the deck 5.
6 and surrounding the open lower 0, this opening communicates each unit 58 with a corresponding compartment of the filling chamber 36 below it.

Each of the cylinders 68 is configured to form a venturi passage to increase the exhaust efficiency of the fan 66 rather than trapping it to limit the area in which the fan operates to be slightly larger than the diameter of each fan 66. is desirable.

Towers 10 and 16 each have a different group arrangement of fan units 58.

To that end, the decks 56 of the tower 10 extend further toward the central axis than the decks 56 of the tower 16 and support the fan units in an array forming at least two coaxial hexagons about the axis.

If it is necessary to increase the number of fan units to increase the capacity of the tower 10, additional fan units can be placed in a hexagonal arrangement outside the existing ones.

In such an arrangement, the distance between the innermost hexagon and the central axis is much smaller than the distance between the outer hexagon and the central axis, so that Most of the area can be used to create an exhaust column for the hot and humid air exhausted from the fan unit 58.

The bulkhead 57 of the column 10, unlike the column 16, does not radiate radially.

Adjacent partition walls 57 cooperate to form compartments within the chamber 36, since the non-radial partition walls 57 are spaced apart from the central axis and are spaced apart from each other by a constant distance around the central axis. , a separate cylindrical wall 22 like tower 16 is not required.

It can be seen that the inner ends of the partition wall 57 thus cooperate to form an upright hexagonal cylindrical wall in place of the cylindrical wall 22.

In the arrangement shown in tower 10, each set of bulkheads forms a generally triangular pie-shaped wedge housing three fan units 58, with each bulkhead positioned tangentially to at least two fan units. are doing.

The array configuration of the tower 16 with 18 fan units 58 arranged in a single circle represents a typical array of diameter towers using a single circle.

That is, from the viewpoint of cost, space, capacity, and operating conditions, tower 1
For towers with diameters larger than 6, it is preferable to arrange the fan units in multiple concentric circles or polygons rather than increasing the open area inside the tower by increasing the number of single circular fan units. .

In this regard, columns 12 and 14 of FIGS. 2 and 3 represent another preferred example of a fan unit arrangement for a column approximately 180 meters in diameter.

A tower of such dimensions would require 60 fan units as mentioned above to effectively satisfy the required cooling capacity, and in order to combine the required cooling capacity with the energy concentration necessary to create a stable discharge column. It has been found that three concentric circles of 20 fan units each or two concentric circles of 30 fan units each can be used.

A hexagonal arrangement could be used in which the towers 12 and 141C extend outward from the central axis rather than inward from the outer structure 44, but such an arrangement would increase the area of the deck and the associated Cost and weight issues must also be considered.

In operation, hot water to be cooled is introduced into the annular distribution device 44, the level of the hot water being maintained above the reinforcement of the distribution device and extending over the entire circular area of the hot water distribution device. Water is allowed to flow freely.

A stream of water falls from an orifice 54 at the bottom of the distributor 44 and contacts the flat surface of the assembly 30 below the distributor.

The corrugated one fill member 34 disperses the water flow and increases its surface area, so that when the water flow impinges on the fill member 34 below it, it breaks up into droplets, creating a droplet that spreads across each fill member. Thin layer surface cooling is performed when water flows over the surface of the fill member 34, and the holes 3 of the corrugated shape 34b of the fill member 34
As the water stream passes through 4a, it breaks up into small streams or droplets.

The fan unit 58 exhausts air vertically, thereby drawing cold ambient air through the annular sloped inlet face of the fill assembly 30 and causing it to fall by gravity down the assembly 30 toward the cold water reservoir 18. It flows as if intersecting with the water passing through it.

As mentioned above, the incoming air tends to draw water back out of the annular inlet of the tower;

Preferably, the fill assembly 30 is sloped to compensate for this backflow of water.

By doing so. It is possible to avoid the increased cost of providing an extra fill member around the outer periphery of the tower that is effectively impermeable to water flow.

Water droplets accompanying the humid air exiting the fill assembly 30 are removed by a removal plate 42, and the humid hot air delivered to the chamber 36 is discharged upwardly by the action of the fan unit 58.

As shown schematically in FIG. 10, the hot, humid air stream discharged from the column coalesces into a single exhaust column 72 above the multiple fan units 58.

This is particularly noticeable in tower 10, but in towers 12 to 16, where the fan units are located farther from the central axis than in tower 10.
But I can say it.

In either case, the individual energy of each discharge stream is concentrated to form a single discharge column, so it can be seen that such a discharge column has a greater upward force and is more stable than the conventional one.

For example, assuming that the surrounding wind blows from left to right as seen in Figure 10, the windward portion of the discharge column 72 will be displaced by the wind, but the leeward portion of the discharge column 72 will be protected by the windward portion. It rises almost perpendicular to the ground without much displacement.

Therefore, the fill assembly 30 can be removed from either side of the discharge column 72.
There is no problem of backflow of hot and humid air.

In addition, since the upward force of the exhaust column 72 is large, the humid exhaust air is diffused away from the ground, and therefore the damage caused by the increase in the temperature of the surrounding air is less likely to be caused to nearby houses and other buildings. Become.

One means of increasing the stability of the hot, humid air exiting fan unit 58 is to increase the velocity of the exhaust air relative to the velocity of the surrounding airflow.

If the ratio of the exhaust air velocity to the ambient air velocity is expressed as k, the greater the value of k, the greater the resistance of the outflow air to the wind on the outer periphery.

Therefore, the possibility of backflow of exhaust air decreases as k increases.

By clustering the fan units together, the total energy of the airflow flowing out from the fan units is concentrated in a sufficiently small area, resembling the single chimney exhaust normally obtained in large hyperbolic natural draft towers. It is clear from the fact that the individual exhaust air acts on

The "momentum east density" of all discharge columns is the mass of the hanging column, ■ is the discharge speed, and a is the cross-sectional area of the discharge column.

Similarly, "buoyancy east density J (indicated by BFD) is BFD-
It can be calculated from d-m/a, where d is the density difference between the exhaust air and the surrounding air, m is the density of the exhaust column, and a is the cross-sectional area of the exhaust column.

Therefore. An increase in the ejection velocity V necessarily increases the momentum flux density of the ejection column, other parameters being constant, which increases the total energy concentration of the ejection column.

For economic reasons, it is usually not desirable to simply increase the fan power in order to increase the discharge rate of the discharge column.

By arranging the fan units 58 in groups, "a"
'' is small, i.e., the cross-sectional area of the discharge column is smaller than the sum of the cross-sectional areas of each of the non-clustered series of humid and hot discharge air, and the density of the discharge momentum of the column and its total energy concentration are increases.

In this way the resistance of the evacuation column to deflections due to the surrounding air flow is greatly increased and the recirculation of the evacuation column becomes less.

From FIG. 11 it is clear that the gas-dynamic geometry of the circular column creates a very small wake area on its leeward side.

Experimental results have shown that only about a quarter or less of the circumference of the column is in contact with the wake area.

Therefore, less than 1/4 of the fluid passing through the fill assembly comes from within the wake fluid.

Furthermore, in a circular column, the concentration of effluent in the wake area is much more effective than in the wake area of a square column, as the wake area is continually diluted by the flow around the sides of the column. This will reduce it somewhat.

Recirculation of humid hot air back to the air intake on the leeward side of the tower must be avoided, which is also aided by the hydrodynamic shape of the circular tower.

As shown in Figure 11, the surrounding air moving from left to right is
It tends to flow in a substantially streamlined flow around the circumference of the circular tower, so there is little tendency for moist air to be drawn back into the tower.

This is because on the leeward side of the column, ie in the reduced air area, a stagnation vortex is formed, such as occurs when an ambient air stream is passed around a rectangular column as previously described.

A particularly important advantage obtained by using a circular water cooling tower of the mechanical crossflow type as illustrated is that its operation is substantially independent of wind direction.

This is because preventing recirculation of humid hot air can be done regardless of the direction of the wind blowing at any given time.

Recirculation of moist, hot air exiting the fan cylinder 68 and returning to the column fill assembly occurs at the height of the cylinder.
It has been found that three quarters of the fan diameter can be avoided at any lower value.

Therefore, the tower can be manufactured at low cost without adversely affecting the operation of the tower.

In all examples, the height of cylinder 68 can be less than the diameter of the fan used therein.

12 to 16 illustrate a preferred embodiment of a mechanically ventilated dry circular cooling tower, including tower 100 (FIG. 12).
is shown as having 19 separate fans, which is more common than the configuration of tower 200 (FIG. 15), which has 7 fans.

Tower 100 includes a group of vertical fin canals 106 (FIG. 14).
It has a number of upright side-by-side heat exchangers 102 formed by a series of internal vertical tubes arranged in alignment with or staggered inside the tubes.

A header 108 communicates with the upper ends of the matched or staggered pairs of tubes 104 and 106, respectively, and a support member 110, which is part of the column frame, provides stability at the top of each heat exchanger 102. It is set up to encourage people.

It is therefore clear that tubes 106 form the outer surface of the heat exchanger, while tubes 104 form the inner surface of the heat exchanger.

A header assembly 112 connected to the lower ends of tubes 104 and 106 has a portion 114 that communicates with the lowermost end of upwardly extending fin canal 104, while portion 116 of the header assembly also has a Each tube 106 of each exchanger 102
The lowermost end of the

As shown clearly in FIGS. 12 and 13, the exchanger 10
2 are arranged in the form of a polygon to form a generally cylindrical heat exchange structure defining a plenum chamber 118 therein.

Cylindrical heat exchange structure 12 made by heat exchanger 102
0 is closed at its top by a perforated wall 122 of the fan deck, which is supported in a horizontal position by a frame containing support members 110.

Hot fluid (often highly wet water, such as when tower 100 is used to indirectly cool steam in a power generator) is transferred to header section 114 by distribution piping 126.
is fed to column 100 via pipe 124 connected to.

This distribution pipe 126 is connected to the header portion 11 of each exchanger 102.
The inner header tube 128 has a series of radial distribution tubes 130 extending directly from the inner header tube 128 .

A butterfly valve 132 interposed in the distribution pipe 126 can be operated manually, but is typically provided with a powered adjustment device 134.

Fluid return passage 136 , also with return tube 138 , includes outer header tube 1 that extends around the periphery of heat exchange assembly 120 .
It has 40.

A radial return tube 142 coupling the header portion 116 of each exchanger 102 to the header tube 140 allows cooled fluid to return from the fin tube 106 to the return passageway 136.

Another butterfly valve 144 interposed in the return tube 138 can also be operated manually, but is preferably actuated by a power regulator 146.

The concrete sump 148 is located below the distribution pipe 126 and the return pipe 138, as shown in FIGS. 150 and 15
2 is adapted to collect the liquid drained from the exchanger 102.

A large number of clustered fan units N58 (e.g. shown as 19 in FIG. 12 and as 7 fan units 258 in tower 200) pass through corresponding holes in the horizontal deck wall. Te fan deck 1
22, draws air from the surrounding atmosphere through the heat exchanger 102, and discharges hot air from the cooling tower vertically upward in the form of a discharge column.

Each series of exhaust streams collectively forms a rising column of hot air exhaust that resists its return to the cylindrical surface of the dry cooling tower regardless of wind direction.

For a column 100 with 19 fans, exchanger 102
The diameter of the heat exchange structure 120 is typically about 200 mm.
feet (60 m), and its height is usually 60 feet (18 m).

As such, each of the fan units 158 will typically have a diameter of approximately 28 feet (8.4 m).

Each fan unit 158 is connected to a fan deck 122.
a drive motor 160 supported by and coupled to a reduction gear and fan bubble assembly 164 via a drive shaft 162;
The reduction gear and fan assembly supports a horizontally rotatable multi-blade fan 166.

Each fan 166 is rotatable within an upright open top and bottom speed recovery cylinder 168 (its height is, for example, approximately 5.5 m in the embodiment of FIG. 12.13); The fan unit 158 and the lower filling chamber 118 are communicated with each other.

Each cylinder 168 is shaped to define a venturi-type passageway to increase the exhaust efficiency of each fan 166 by limiting the passageway area so that the respective fan 166 operates within a passageway slightly larger than its diameter. It is desirable to do so.

In FIG. 12, the distance between adjacent fan units 158, that is, the length of the fan deck 122 portion, is smaller than the effective diameter of the minimum cross-sectional area portion of each cylinder 168, and the fan unit 158 is circular in the fan deck 122. Note that it occupies a substantial portion of the area.

Preferably, the motor 160 is of the full speed type or of the fully stopped type.

Alternatively, the motor may be selectively operable at half speed to allow for precise control.

Individual fan units 158 may be selected to operate at full speed, operate at half speed, or be stopped by a controller (not shown).

(In some cases, 1. When the drive motor stops, the fan 166
When it is desirable to prevent automatic rotation of the fan, a brake may be incorporated into the drive mechanism to prevent automatic rotation of the fan (77).

) Figure 151 The tower 2 +Li'l has almost the same structure as the tower 100 shown in Figure 12, but only seven fan units 258 are clustered inside the heat exchange structure 220. They are different in some respects.

The details of each component of tower 200 are similar to those described for tower 100, and therefore will not be described in detail.

In operation, assuming that the tower 100 is used to cool a fluid such as hot water used in an indirect steam condenser for a power plant, etc., the hot water from the condenser is transferred to the inner header pipe. 128 and distributed to the inner tube array of multiple fin tubes 104 of each heat exchanger 102.

The high temperature water flows upward in the pipe 104 as shown in FIG.
It then flows downwardly through each fin bone canal 106.

As the liquid flows upward and downward within each heat exchanger 102, outside air is drawn through the cylindrical surface of the heat exchange assembly 120 by the fan unit 158.

The number of fans to be operated at this time is determined by the outside air temperature and the heat load of the tower 100.

First, if the heat load is large compared to the outside temperature,
Assuming that it is necessary to operate all nineteen fan units 158 as shown, the hot air exhausted from the plenum chamber 118 will be equal to the amount of hot air exhausted from each cylinder or air passage 168. The combined flow creates a column of hot air that rises vertically so that diffusion of the hot air occurs at a sufficient distance from the ground surface, thus tending to return the hot air to the cylindrical inlet face of the heat exchange structure 120. are significantly less.

By arranging the fan units 158 in clusters as described above, it is possible to effectively concentrate the total energy of each airflow flowing through the cylinder 168 into a sufficiently small area, so that the individual outgoing airflows are concentrated. , which has the same functionality as a conventional large-sized natural-draft hyperbolic cooling tower.

The mathematical considerations for the circular water cooling tower shown in Figures 1-11 are also applicable to the dry circular cooling tower 100.200.

For example, if the heat load on the cooling tower 100 decreases or the outside air temperature decreases, one or more fans 158 may be reduced to half speed or stopped to maintain the water leaving the cooling tower through the return passage 136 at the appropriate temperature. do.

The illustrated circular dry cooling tower 100, 200 can be used for various fluids such as water vapor, gas, liquids such as water, etc., but it is also used to cool water used to condense water vapor in power plants. It was developed.

In this case, the cooling tower 100.20 (1) is used to cool the water that is circulated through the surface condenser.

When operating a power plant, it is common practice to operate each piece of equipment in the power plant so that it can produce electricity that can be sold at the lowest unit price depending on the state at the time.

The temperature at which the steam is condensed determines the back pressure of the steam turbine.

This determines the steam requirement of the turbine and the power produced by the generator mechanically coupled to the turbine.

The condensation temperature in the condenser is adjusted by controlling the amount and temperature of cooling water.

On for dry baths of the traditional "cell" type (i.e. with the air side split so that each increment of the heat exchanger is supplied by its fan's cooling air).

There are certain limitations to the use of off-type fan drive motors.

In so-called cellular dry towers. The water passing through each section of the heat exchanger that cooperates with the fan in the "on" state is affected by the total cooling air.

The remaining water is passed around without cooling or is circulated to the respective compartments of the heat exchanger in cooperation with the fans which are in the "off" state.

In the latter case, there may be a cooling effect due to a small amount of air movement due to natural ventilation.

If the ambient temperature is low, this control method will cause the water in each section of the heat exchanger where the fan is still "on" to be in a frozen state.

Therefore, additional control equipment is required when using dry bases in climates cold enough to freeze the fluid in the fin canal.

In the present invention, the limitations of conventional tower designs are overcome by clustering individual fan units and communicating the fan units with a common plenum chamber surrounded by a tubular heat exchange structure.

By this method. Uniform air flow in each section of the heat exchanger is ensured whether all fans or some fans are "on".

Since all fans communicate with a common plenum chamber, the total pressure drop along the air flow path through any section of the heat exchanger to any fan is equal to the air flow velocity through the heat exchanger. It is the same as the pressure drop along any other air flow path.

The circular dry multi-fan tower 100.200 meets the criteria and requirements mentioned above.

Heat exchange surfaces and individually actuatable fan units 158
The relationship between the height of the column, denoted h (with respect to the heat exchanger) and the diameter of the column, denoted r (with respect to the heat exchanger ring), is such that r≧h≧ r, /
4 is preferable.

By matching the parameters to the mathematical relationships shown, constraints, velocity changes, or direction changes that would add a larger air pressure drop to the fluid pressure drop through the heat exchanger can be avoided.

Straight dry multi-fan cooling towers require significantly larger fill chambers than are conventional or economically reasonable in order to approach the optimum inherent in circular towers.

The recirculation relationship for a rectangular multi-fan dry cooling tower compared to a circular multi-fan tower is shown in the graph of FIG. 17, where the y-axis shows the speed ratio as k (constant); The y-axis shows the recirculation ratio with R (@).

For circular acids and rectangular towers, the amount of recirculation depends on two major dimensionless relationships.

One relational expression concerns the speed ratio, K2ve/va
, where Ve is the outflow velocity and Va is the ambient air velocity or wind velocity.

The other relation is the Froude coefficient for specific gravity, where g is a constant gravity, D is the diameter of the chimney,
e is the ambient air density and Δe is the density difference between the ambient air and the exit air.

For the test results shown graphically in FIG.
The values of and FD are selected to represent a wide range of operating conditions.

By testing these two important relationships to be the same for both column shapes, the recirculation rate for a rectangular column versus a circular column was determined, and the results are shown in Figure 17. Shown in the graph.

From the data in FIG. 17, it is readily apparent that for any operating condition, the recirculation in a circular column is much less than that in a rectangular column of the same capacity.

Flow observation tests revealed why the recirculation was smaller in the circular column than in the rectangular column.

In the case of a rectangular tower oriented at right angles to the blowing wind, a highly turbulent area was formed immediately downwind from the tower.

As previously mentioned, this turbulent zone is characterized by a large, swirling, intensely mixed air stream that continuously pulls the air stream back to the inlet of the column.

The leeward side of the rectangular tower draws air from the separation area between the chimney-like column section and the ambient air below.

In such cases, air enters from the turbulent area.

In the case of circular columns, on the other hand, the size of the downstream turbulence zone is significantly reduced due to the improved aerodynamic shape of the column.

Since only approximately 1/4 or less of the circumference of the column is exposed to the separation zone, correspondingly less effluent air is drawn back into the column.

Moreover, the concentration of the exhaust stream due to fan exhaust is somewhat reduced by increased "ventilation" which continuously dilutes the air flowing around the sides of the column.

This ventilation in round towers is more effective than in rectangular towers.

The first finding is that even with a large number of fans contributing to a common plenum, these fans cannot be used effectively without a regulating valve to prevent backflow through the inactive fans. However, it has now been found that even if a certain amount of backflow occurs, the inactive fan still acts as a restrictor (throttle) for the airflow and acts as a partially closed regulating valve.

If some fans stop, some of the air being distributed by the remaining active fans flows back through the inactive fans.

However, the other airflow is spread equally over the entire surface of the heat exchanger.

The total air flow rate per active fan increases as more fans are turned off.

The reason for this is that the pressure drop characteristics in the totano/system associated with the remaining operating fans are believed to decrease with each fan shutdown.

FIG. 18 shows a fan characteristic curve showing airflow as a function of static pressure.

In this case, to simplify the explanation, this characteristic curve is
5 for the tower 200 with seven fans shown in FIG.

Along with the fan curve, the characteristic curve of the tower as a function of the number of working fans is also shown.

When each fan is stopped, a new characteristic curve for the tower is generated.

FIG. 18 is a graph showing the performance of the fan.

In this graph, the horizontal axis represents the amount of air moved by the fan, and the units are C, F, M (i.e., cubic feet per minute: ft/+nju ''l), and the scale is in parts per million (10 ) indicates the value of

Therefore, for example, the scale rx, 6'' is 1600000f
t/mIITL.

In addition, 1 ft / - approximately 0.02 s 315rrr
'/T-.

On the other hand, the vertical axis shows the static pressure loss of the cooling tower, and the pressure unit is the water head height (measured in inches).

Note that 1 inch is approximately 25.4 mm.

Therefore, for example, "2" on the scale indicates a pressure loss corresponding to a water head height of 0.2 inches (approximately 5.08ii).

The seven first curves slightly upward to the right in the graph indicate the operating characteristics of the cooling tower when the corresponding number of fans in the figure are operating.

A second curve, sloping to the right, shows airflow through the fan as a function of hydrostatic pressure.

As can be seen from the seven intersections of the first and second curves in this graph, the fewer the number of activated fans, the greater the air flow rate through each activated fan.

FIG. 19 shows the stepwise control available for full heat loading of a tower 200 with 07 fans over a range of dry bulb temperatures.

Assuming a return water set point temperature of 80 degrees Fahrenheit for purposes of illustration, all fans must be maintained above 76 degrees Fahrenheit.

The graph in FIG. 19 clearly shows that the relationship between the dry bulb temperature and the number of fans necessary to maintain the water at the set temperature is a non-linear relationship.

The use of a fan drive motor capable of full speed and half speed operating conditions allows for a greater amount of control over the operation of the tower.

If less cooling capacity is required, the fan can be gradually reduced to half speed.

The first fan, slowed down to half speed, primarily acts as a rotary damper, preventing backflow and increasing the amount of air passing through the heat exchanger due to the fan rotating at full speed. do.

As the other fans are slowed down to half speed, the system pressure decreases and the active fans deliver progressively more air.

Although the tower structure 120 has been described herein as having a substantially circular cross-sectional shape, it will be appreciated that in most cases the tower will be polygonal with multiple sidewalls.

Each heat exchanger 102, typically about 12 feet wide, forms a plane around the column.

As evidenced by the experimental results shown in Figure 1T, due to the favorable aerodynamic properties of the circular tower, a relatively large number of flat surfaces (at least 16 or or more) is desirable.

[Brief explanation of the drawing]

FIG. 1 is a diagrammatic plan view of a preferred embodiment of the circular mechanical ventilation cross-flow multi-fan water cooling tower of the present invention. 2 to 4 are diagrammatic plan views of other embodiments of the invention. FIG. 5 is a side view of the cooling tower shown diagrammatically in FIG. Figure 7 is an enlarged cutaway view of the plan view of a portion of the tower shown in Figure 4, with other parts cut away to better show the shape and structure of the lower parts. Fig. 8 is a partial side view of the cross-flow type water cooling tower;
The exterior is shown along line 8-8 of the figure. FIG. 9 is an enlarged, cutaway perspective view of one type of fill member for use in the film assembly of the present invention, while also illustrating a preferred grid support structure for the fill member. FIG. 10 is a diagrammatic side view in reduced size of one of the four embodiments described above, in which the recirculation of hot exhaust air back to the tower air inlet is clustered 1. shows how the leeward portion of the ejected hot air column is given by the upwind portion of the column. Diagram showing a nearly vertical rise for protection, thus minimizing recirculation of hot air. Figure 11 is a schematic diagram showing the tower shown in Figure 1 on a reduced scale.The flow of wind flowing from left to right through the circular tower shows an almost continuous flow pattern, and there is a minimum at the lee of the tower. forming a vortex of
Therefore, the vacuum zone is removed on the lee side of the tower to minimize recirculation of hot air. FIG. 12 shows an oval mechanical draft multi-fan cross-flow dry fluid cooling tower with means for delivering hot water to a tubular heat exchanger and removing cooled fluid therefrom. FIG. 2 is a diagrammatic plan view of the embodiment. FIG. 13 is a diagrammatic side view of the dry fluid cooling tower shown in FIG. 12; FIG. 14 is an enlarged, broken-away view of a vertical cross-section taken generally along line 14--14 of FIG. 12; FIG. 15 shows a diagrammatic plan view of a circular mechanically ventilated multi-fan cross-flow two' dry fluid cooling tower similar to the tower of FIG. 12, but with a smaller number of separately operable Figure with fan. FIG. 16 is a diagrammatic side view of the cooling tower shown in FIG. 15. FIG. 17 is a graph displaying the results of a comparative test conducted to demonstrate the hot air recirculation characteristics of a rectangular dry cooling tower versus a circular tower according to an embodiment of the present invention. FIG. 18 is a graph showing fan performance for the seven-fan circular fluid cooling tower shown in FIG. 15.16. FIG. 19 is a graph illustrating the number of fans that completely remove the heat load from a fluid, such as water, but are shut down as the dry bulb temperature decreases. 10.12, 14, 16: Water cooling tower, 20, 22. 24: Wall, 30: Fill assembly, 34 Nifil member, 3
6: Pressure chamber (filled chamber), 44: Distributor, 58: Fan unit, 66: Fan, 68... cylinder.

Claims (1)

[Scope of Claims] 1. A method of cooling a fluid by indirect heat exchange with the surrounding atmosphere, comprising: (a) transporting the fluid to be cooled through an upright tubular heat exchange zone containing a plenum; (b) blocking all air passing through a selected area across the top of the plenum; and (c) inhibiting indirect heat exchange with fluid flowing through the heat exchange area. drawing air from the surrounding atmosphere through the heat exchange zone to mix the air within the plenum and preventing circulation of airflow extending upwardly from the heat exchange zone and back to the heat exchange zone; discharging air from the plenum chamber through the heat exchange zone as a series of clustered, individually vertically oriented air streams exhibiting a rising column of air. 2. The fluid cooling method according to claim 1, including the step of varying the velocity of air discharged from the plenum chamber through the corresponding heat exchange chamber above the plenum chamber. A fluid cooling method characterized by: 3. In a fluid cooling tower with a dry surface, (a)
an upright tubular structure delimiting a central filling chamber and equipped with a heat exchange device capable of receiving the fluid to be cooled for indirect heat exchange with air from the surrounding atmosphere; b) for interrupting the air flow passing through the tubular structure;
wall means disposed across an upper portion of the structure; (c) extending through the wall means into the direct path of ambient wind flow and in common communication with the plenum;
a group of upright, tubular, open top and bottom fanned chimneys; (a) mounted for rotation about a corresponding upright axis within each chimney; (e) each one of said fans for rotating said corresponding fan; drive means coupled one by one, each drive means being independently adapted to cause the corresponding fan to rotate at a selected speed and to be selectively energized to energize the rotation of the corresponding fan; a drive means operable to cause the group of chimneys to produce a column of discharged fluid sufficient to prevent recirculation of discharged air into the structure. a fluid cooling tower arranged to concentrate the energy of the air emitted from the chimney to a certain extent;