RU2473855C2 - Multi-circuit ejection cooling tower - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: multi-circuit ejection cooling tower comprises a body in the form of a regular polyhedral prism based on supports, comprises two reservoirs in the lower part for collection of cooled water - outside a pool of polyhedral shape, which belts a receiving chamber along the cooling tower contour placed in the centre, from which cooled water is supplied to a load, in the upper part the body changes into a confusor, narrowing of which covers a drop catcher, and above the confusor there is an exhaust channel. The cooling tower has two cooling circuits - internal and external, separated with a partition, arranged concentrically to body walls along its entire height, in the lower part of the separating partition along its perimetre from inside there are inclined spillways mounted in the form of a truncated tilted pyramid, outside of the partition, and along the contour of the body walls from inside at the same level, there are also spillways mounted with inclination towards each other, above spillways there are ejection units, and directly under them there are headers of the water-distribution system in the form of closed octahedrons, in the projection link under spillways, at the level of top of water-collecting reservoirs there are technological sites - internal and external, besides, decking of the external site is solid and covers the peripheral part of the pool surface, and decking of the internal one is latticed, between lower edges of all spillways and contours of technological sites there are wind partitions installed, which prevent steam and drop moisture carryover from the volume of the cooling tower, at the same time in the space above the internal technological site under adjacent spillways there is a water-intake corridor.

EFFECT: improved operational and technical characteristics of a cooling tower, reduced capital costs for construction, higher cooling capacity of a cooling tower, improved conditions of device maintenance.

7 cl, 4 dwg

Description

The invention relates to a power system and can be used as a circulating water cooler at large industrial facilities, including power plants such as TPPs, state district power stations and nuclear power plants, where the water flow rate is not less than 4000 m ³ / h. The proposed cooling tower is an alternative to a typical tower and large, free-standing, cooling towers of the SK-400 and SK-1200 type.

Known tower cooling tower containing a housing with air-supplying nozzles, openings in the casing and additional openings, a water-air ejector. Each water supply nozzle is placed inside the pipe shell introduced into the housing, water-air ejectors are formed by said air supply nozzles and pipe shells, while gaps between the air supply nozzles and pipe shells are filled with air, and additional openings are formed by the indicated gaps, while the water supply nozzles and pipe shells are placed inside the casing cooling towers so that their inlet ends are located near the openings in the casing (see patent RU, No. 2295099, C1, F28C 1/00, 03/10/2007).

Such a cooling tower has the following main disadvantages.

The location of the ejectors only along the perimeter cannot have a significant impact on the operational performance of the tower as a whole, because they work only in the peripheral zone, and the dimensions of tower cooling towers in plan, as a rule, are measured in tens of meters.

Based on the above ratio (1.05 ÷ 1.03): 1 between the diameters of the tube shell of the ejector and the water supply nozzle, the gap between them will be several mm, because the diameter of real water supply nozzles does not exceed 200 mm. It is impossible to pump a large amount of air through such small gaps, even at very high speeds, which practically eliminates the effect of ejectors on the operation of the cooling tower, since the tower draws millions of cubic meters of air, and the performance of such cooling towers in chilled water is thousands of cubic meters per hour.

The closest in technical solutions is a cooling tower containing a vertical tower with an air intake window, a reservoir for collecting chilled water and a water distribution system, which includes an annular water supply manifold with radial nozzles installed with an inclination from the center to the periphery, and tiered nozzles whose nozzles are oriented to the center of the tower at different angles to the horizontal plane - the prototype (see patent RU, No. 2099662, F28C 1/00, 12.20.1997).

Such a cooling tower also has a number of significant drawbacks.

In the absence of ejection channels and the placement of nozzles inside the active zone of the tower, the ejection ability of free flares generates only recirculation of moist air in the volume and contributes little to the suction of additional air.

The practice of operating tower towers shows that the streamlines of the air flows immediately after the air intake window bend upward under the influence of the towing tower. In this regard, only the nozzles of the upper rows mounted at angles of 30-45 ° to the horizon get into the air flow. The water flows pushed out by the nozzles of the lower rows in the horizontal direction are outside the zone of the air flow, and therefore, a significant part of the water is practically not cooled. Moreover, the waterfalls created by the nozzles of the upper rows, falling down, oppress the torches of the lower rows.

The construction of expensive towers with a height of 50 m or more, capable of creating the necessary self-pulling, is economically feasible if the water flow through the tower is estimated at thousands of cubic meters per hour. The overall dimensions of such cooling towers are several tens of meters, while the nozzles of the lower rows, with an average pressure of 0.1-0.15 MPa, can push out water at a distance of no more than 6-7 m, i.e. in the central part of the cooling tower, a “dead zone" is created, where there is no movement of coolants.

The hydraulic circuit of the tower is inconvenient, because does not allow for maintenance of nozzles without a complete shutdown of the unit.

The objectives of this invention are: increasing the cooling ability of the tower, reducing capital costs for construction and improving the conditions of maintenance of the unit.

The present invention allows to achieve lower temperatures of the cooled water, to provide almost any water flow through the tower while reducing capital costs, and to improve the conditions of maintenance of the unit.

A schematic diagram of a cooling tower is shown in figures 1-4. Figure 1 is a section along the axis of the tower. Figure 2 - hydraulic circuit of the receiving chamber. Figure 3 is a top view of the tower. Figure 4 is a transverse section of the ejection nodes.

According to the scheme, the tower body 1 in the form of a regular multifaceted prism mounted on supports 2, at a height of about two meters above the ground. In the lower part of the tower there are two containers for collecting chilled water - outside, a multi-faceted pool 3 encircling the circuit of the tower located in the center of the receiving chamber 4, from which the chilled water is supplied to the consumer. Each sector of the pool is connected to the receiving chamber by an overflow pipe 5, with each pipe directed tangentially and oriented parallel to the nearest wall of the chamber. The cooling tower has two cooling circuits - internal and external, separated by a partition 6, located concentrically to the walls of the housing. The height of the partition panel is equal to the height of the walls of the housing. The elongated racks 7 of the partition frame support the supporting frame 8 of the droplet eliminator 9. In the upper part, the housing passes into the confuser 10, the narrowing of which overlaps the droplet eliminator. Over the confuser mounted exhaust channel 11 of the tower. At the base of the confuser and the exhaust channel, the tower has external ramps 12 and 13. In the plane of the droplet eliminator, internal ramps are arranged 14. In the lower part of the dividing wall along its perimeter, inclined spillways 15 are mounted from the inside in the form of a truncated inverted pyramid. At the same level, weirs 16 and 17 with a slope towards each other are also mounted on the outside of the partition and along the contour of the walls of the housing from the inside. Ejection units are located above the weirs. Directly under the spillway mounted collectors of the water distribution system, in the form of closed octahedrons parallel to the walls of the housing. Below, at the top of the drainage tanks, in projection communication under each spillway, technological platforms are arranged - internal 18 and external 19. The floor of the external technological platform is continuous and covers the peripheral part of the pool surface. The flooring of the internal area is trellised. Between the lower edges of all weirs and the contours of the technological platforms, wind partitions 20, 21, 22 are installed to prevent the removal of steam and drip moisture from the volume of the tower. Moreover, in the space above the internal technological platform under adjacent spillways, an air intake corridor 23 is formed. Air enters the corridor from under the bottom of the tower through the slots of the grating. Thus, the complete localization of the active zones ensures the supply of dry atmospheric air to the ejection units.

The design of the ejection unit, shown in figure 4, includes nozzles 25 located in rows along the axes of the openings of the air windows, made in the planes of the weirs, above which there are slit-like ejection channels 26. The width of each ejection channel along the upper edge is less than the diameter of the dispersed liquid in the same plane. At the same time, the nozzle spacing is chosen so that the torches deformed by the channel walls close together, forming a guaranteed water seal in the belt with a width of not more than 150 mm from the upper edge of the channel.

Studies show that the most effective is the ejection channel in the form of a Laval nozzle. In this regard, the channel walls are curved and have a cross-sectional profile of this nozzle. Flanges 27 are made along the edges of each air window, forming a system of gutters for collecting and discharging water flowing in the form of films along the walls of ejection channels from the hydraulic seal zone.

Depending on the flow rate of the chilled water, the cooling tower may have several external cooling circuits arranged according to a similar scheme and separated by partitions. With this design of the tower, the unit height does not exceed 25 m.

The cooling tower works as follows. Water under pressure is supplied to the collectors 24 of the water distribution system, from which it is pushed through the nozzles 25 into the ejection channels 26, in the volume of which the required amount of dry, not moistened by vapor atmospheric air is sucked.

Water films formed in the zones of hydraulic locks slide along the walls of the channels 26 into the gutters, through which water flows into the reservoirs 3 and 4. Thus, water losses from the ejectors are excluded when they are oriented upward.

In the internal cooling circuit after ejection units, the flows of dispersed liquid together with air move upward along curved paths with a slope to the axis of the tower. In the upper part of the cooling tower, a multilateral frontal collision of flows occurs, accompanied by repeated crushing and droplet dropping in the process of chaotic movement, i.e. flows seem to freeze in volume for a while. After the collision, the cooled water drops down in the form of rain. At the same time, some of the ejected air saturated with steam leaves the collision zone through the exhaust channel into the atmosphere. Another part of the air carried away by the rain moves down. At the surface of the liquid in the receiving chamber 4, the air turns and, distributed in volume, rushes into the exhaust channel 11 of the tower, "sifting" between the drops of freely falling rain. In the external circuit, the movement pattern and the nature of the interaction of the coolant flows are similar to the process in the internal circuit. The difference lies only in the fact that in the upper part of the volume between opposing spillways a two-way collision of flows occurs. The dividing wall 6 prevents the movement of stray flows that spontaneously occur in volumes of large heat and mass transfer units.

In addition to a rational scheme of movement and interaction of flows, which significantly extend the contact time of the heat carriers, other factors contribute to the process of effective heat and mass transfer. Due to the fact that the flows coming through the overflow pipes 5 are directed tangentially, the entire volume of water in the receiving chamber 4 is constantly rotating. The friction force causes rotation of the air above the surface of the whirlpool, as a result of which a tornado-like upward flow is created in the volume of the internal cooling circuit, increasing the traction of the entire cooling tower. In addition, the presence of vortex flows even more intensifies the process of heat and mass transfer between water and air.

The cooling tower is very convenient for maintenance. From the surfaces of the lower technological platforms 18 and 19, free access to ejectors and elements of the water distribution system is provided even during operation of the unit, as weirs protect personnel from falling rain. Penetration into the active zones of the tower is carried out from the same sites through the doors in the walls of the wind partitions (not shown in the diagram). To ascend to technological sites, the design provides for marching stairs (not shown in the diagram). From the external 13 ladder to the internal 14 ladder, personnel enter through the door (not shown in the diagram) in the wall of the exhaust channel 11. To assess the condition and carry out repair work on the main load-bearing structures, personnel can freely move under the bottom of the tower.

Thus, the proposed design of the cooling tower and the technological scheme of the cooling process allow to achieve a deeper cooling of the water. Material consumption and capital costs for the construction of the unit, compared with typical tower cooling towers, are reduced by 30-40%. The operation of each row of nozzles in a separate ejection channel having a Laval nozzle profile, as well as the presence of a reliable water seal in it, provide high ejection coefficients while reducing the working pressure in the system to 0.2-0.25 MPa, which reduces the energy consumption of the ejection tower.

Claims (7)

1. A multi-circuit ejection cooling tower, having a housing in the form of a regular multi-faceted prism, based on supports, contains two containers for collecting chilled water in the lower part - a multi-faceted pool outside, encircled by the circuit of the tower located in the center of the receiving chamber from which the chilled water is supplied water to the consumer, in the upper part of the body passes into the confuser, the narrowing of which overlaps the drip tray, and an exhaust channel is mounted above the confuser, characterized in that it has two cooling circuits I - internal and external, separated by a partition located concentrically to the walls of the housing along its entire height, inclined spillways are mounted inside the bottom of the separation partition along its perimeter in the form of a truncated inverted pyramid, outside the partition and along the contour of the walls of the inside of the housing at the same level weirs with a slope towards each other, ejection units are located above the weirs, and collectors of the water distribution system in the form of closed eights are mounted directly below them Grannikov, in projection communication under the spillway, at the top of the drainage tanks, technological platforms are arranged - internal and external, with the flooring of the external platform continuous and covering the peripheral part of the pool surface, and the flooring internal - trellised, between the lower edges of all the spillways and the contours of technological platforms installed partitions to prevent the removal of steam and drip moisture from the volume of the tower, while in the space above the internal technological platform under adjacent spillways formed by the air intake passage. 2. The multi-circuit ejection tower according to claim 1, characterized in that the nozzles are arranged in rows along the axes of the openings of the air windows, made in the planes of the spillways, over which slit-like ejection channels are installed. 3. The multi-circuit ejection tower according to claim 2, characterized in that the cross section of each ejection channel has the shape of a Laval nozzle. 4. The multi-circuit ejection cooling tower according to claim 3, characterized in that the width of the ejection channel along the upper edge is less than the diameter of the dispersed liquid in the same plane, and the nozzle spacing is chosen so that the torches deformed by the channel walls close to each other, forming a guaranteed water seal in a belt with a width of not more than 150 mm from the upper edge of the channel. 5. The multi-circuit ejection cooling tower according to claim 2, characterized in that flanges are made on the edges of each air window to form a gutter system for collecting and draining water flowing in the form of films along the walls of the ejection channels from the hydraulic seal zone. 6. The multi-circuit ejection tower according to claim 1, characterized in that each sector of the pool is connected to the receiving chamber by an overflow pipe, each pipe directed tangentially and oriented parallel to the nearest wall of the chamber, ensuring a constant rotation of water in its volume, as a result of which a surface is created above its surface rising vortex, improving the gravity of the cooling tower. 7. A multi-circuit ejection cooling tower according to any one of claims 1 to 6, characterized in that its body mounted on supports is raised to a height of about two meters, providing dry air from under the bottom of the tower to the intake corridor through the slots of the grating, and also free movement of staff, while its total height does not exceed 25 m.

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