RU2279616C1 - Air cooling system for heat transfer agent - Google Patents

Abstract

FIELD: power engineering, namely systems for air cooling of heat transfer agent pumped through heat exchange equipment, possibly heat removal from second circuit of nuclear plant.

SUBSTANCE: high power system for air cooling of heat transfer agent is in the form of recuperative heat exchanger and it is made of vertical bundles of finned tubes housed in polyhedral casing and assembled to sectors from which full heat exchanging surface is formed. Said full heat exchanging surface is in the form of cone with apex turned downwards. Above cone there is pressure annular manifold with radial dispensing branch pipes; under cone there are accumulating annular manifold with discharging radial branch pipes. In lower part pipelines with sprinkling water jets turned upwards are arranged. Between annular manifolds dampers are mounted for controlling air supply into heat exchangers. Invention enhances appearance of industrial object due to prevention of steam generation over it and lowering intensity and repetition frequency of acidic rains and mists.

EFFECT: enhanced appearance of industrial object, reduced contamination degree of sanitary-technological zone.

4 cl, 5 dwg

Description

The invention relates to the field of energy, and in particular to air cooling systems of a heat carrier pumped through heat-exchange equipment, and can be used to remove heat from the secondary circuit of a nuclear installation.

A device is known for air cooling of a heat carrier, comprising a pressure manifold with dispensing nozzles, a collecting manifold with outlet pipes located beneath it, vertically mounted finned tubes in communication with the dispensing and outlet nozzles, gates located between the pressure and collecting manifolds, and an electric fan (see Patent RF №2075714 dated 03.20.97. MKI: F 28 D 1/04).

The disadvantage of this device is the inability to increase the flow of coolant from 90 000 to 300 000 cubic meters. m / h, necessary for cooling the steam spent in the turbine, as well as cooling the coolant circulating in the secondary circuit of the nuclear installation, in case of an emergency with the appearance of excess heat, cool the coolant to the nominal value at temperature pressures of 5-10 ° C and at ambient temperatures above + 25 ° C.

The objective of this invention is to provide the necessary removal of waste heat from saturated steam turbines with a capacity of 500, 1000 and 1500 MW using air heat exchangers, that is, without loss of circulating coolant in normal operation time. An additional objective of this invention is the provision of heat removal from a nuclear reactor in emergency situations, for example in passive heat removal systems.

This task is achieved by the fact that in the known air cooling system of a coolant containing a pressure manifold with dispensing nozzles, a collecting collector with outlet nozzles located below it, vertically mounted longitudinally finned tubes in communication with the dispensing and outlet nozzles, gates located between the pressure and collecting manifolds , and electric fan. What is new is that the pressure and discharge manifolds are ring-shaped, the dispensing and outlet nozzles are staggered to the collectors, radially and obliquely: the discharge nozzles are down, and the outlet nozzles are up, with each nozzle made up of pipes of variable diameter, which decreases to the center, moreover, on the finned tubes along the dispensing nozzles, multifaceted casings are connected stepwise connected by the sides so that an air cavity is formed under them, shaped like a cylinder with a cone located inside with a vertex pointing down.

In addition, the air system may have nozzles installed in the lower part of the air cavity, radially directed upwards.

In addition, the air system may have compensation bends made in sections of finned tubes above the casing and under the casing.

In addition, the electric fan of the air system can be installed above the pressure manifold.

The execution of pressure and collecting collectors ring-shaped provides the ability to bifurcate the flow of coolant and accordingly pass through the collectors of the coolant with an increased flow rate. From the point of view of process technology, the ring system is more reliable, since a double supply of coolant is carried out. When a part of the heat exchange surface is disconnected, the heat carrier flow through the remaining sections of the heat exchanger will be increased.

The connection of the dispensing and outlet pipes to the annular collectors in a checkerboard pattern prevents the weakening of the design of the body of the annular collector by mechanical stresses due to cutouts and provides a more complete removal of heat from the nozzles.

The implementation of the pipes with composite pipes of variable diameter, which are reduced to the center, is caused by the need to keep the velocity of the coolant equal along the length of the pipes and equal to the pressure drops on the finned tubes and, therefore, the equal flow of coolant through the tubes, while reducing the metal consumption of the structures.

The installation of multifaceted casings stepwise on finned tubes with the formation of an air cavity under them, made in the form of a cylinder with a cone located inside with the top pointing downward, reduces the hydraulic resistance of the air flow at the inlet and outlet of the air system.

The invention is illustrated by drawings, where:

in figure 1. shows a general view of the heat exchanger,

figure 2. shows a section of a heat exchange surface,

figure 3. shows a section of a group of tubes of a heat exchanger,

figure 4. shows a longitudinal section of one of the tubes of the heat exchanger,

figure 5. shows a cross section of a heat exchanger tube.

The air coolant cooling system consists of a frame 2 located on the base 1 with an air duct 3 fixed on it. A pressure ring collector 4 and a collecting ring collector 5 are supported on the frame 2. Radially and staggered are installed on the pressure 4 and collecting 5 collectors distributing 6 and branch pipes 7. The dispensing 6 nozzles are installed obliquely downward, and the outlet 7 nozzles are installed obliquely upward. In this case, the dispensing 6 and outlet 7 nozzles are made of composite pipes of variable diameter, decreasing towards the center.

Between the dispensing 6 and the outlet 7 pipes are installed vertical tubes 8 with a longitudinal finning 9 having compensation bends: a bend 10 at the top and a bend 11 at the bottom, which are communicated by means of the supply tubes 12 and the discharge tubes 13, respectively, with the dispensing 6 and the outlet 7 pipes.

The finned tubes 8 are enclosed in multifaceted casings 14, each of which has a number of faces equal to half the number of fins 9 of the tube 8. The finned tubes 9 are installed with the possibility of free sliding along the inner surface of the casing 14. The height of the finned tubes 8 is approximately equal to the height of the casing 14 The casings 14 are stepwise located on the finned tubes 8 along the radial nozzles 6, are interconnected by the sides so that an air cavity 15 is formed under them, made in the form of a cylinder with nnym inside a cone with a vertex directed downwards. This is necessary for uniform, radial and volumetric air velocities when approaching finned tubes 8.

Inductors 16 with fixing protrusions 17 are placed inside vertically mounted finned tubes 8. This is necessary in order to distribute the coolant evenly through the tubes 8 and create the same conditions for heat exchange. The outer fin 9 of the tube 8 is made in the form of longitudinal plates, which are mounted on the outer surface of the tube 8 with the possibility of free movement relative to the inner surface of the polyhedral casing 14.

To increase the air draft in the duct 3 and the efficiency of the air system for removing heat from the coolant above the pressure collector 4, an air fan 18 can be installed, consisting of a fan housing 19, an impeller 20, and a drive motor 21. There are 22 valves installed between the pressure 4 and collecting 5 collectors and on the radial nozzles 23 located in the lower part of the air cavity 15, nozzles 24 are connected to the water supply network.

The air coolant cooling system works as follows: the hot circulating coolant is supplied to the pressure annular manifold 4, then to the radial dispensing nozzles 6, of which the coolant is distributed through the supply pipes 12 to the finned tubes 8. The coolant passes inside the tubes 8, by fins 9 gives off heat to the air passing inside the multifaceted casing 14 along the fins 9 and tubes 8, while the gate 22 is in the "regulation" position or is fully open. From the finned tubes 8, the coolant enters the outlet pipes 13 connected to the radial outlet pipe 7, through which the cooled coolant enters the annular manifold 5, and then is supplied to the condenser.

When the temperature of the coolant changes, the tube 8 with the fins 9 heats up and increases in size, while the temperature and dimensions of the casing 14 remain unchanged. Due to the provided gap between the inner wall of the casing 14 and the fins 9, they move relative to each other, thereby compensating for linear dimensional changes in any dynamic situation.

The coolant, having entered the tube 8, encounters a cylindrical throttle 16 in its path, which is concentric with respect to the tube 8 by means of the projections 17. In the annular channel of the tube 8, the hydraulic resistance of the coolant increases and is displaced by the throttle 16, thereby ensuring uniform distribution of the coolant along all parallel tubes 8.

The cooling air, passing through the gates 22, washes the vertical outlet pipes 13 from the periphery to the center, turns up and passes into the gaps between the finned tubes 8 and the casing 14, where it removes the main heat, leaving the finned tubes 8, the air washes the supply tubes 12 and transfer 6 nozzles.

Due to the fact that the process of supplying air to the vertical tubes 8 occurs continuously with the extraction of air from the cavity 15, the speed from the periphery to the center is maintained, and the finned tubes 8 are cooled uniformly both at the periphery and in the center.

In the event of an emergency, when natural air circulation may be insufficient, the forced air circulation fan 18 is turned on, which increases traction by another 100%, and at ambient air temperatures above the calculated temperature, water-spraying nozzles 24 located in the lower part of the air cavity are turned on 15. The nozzle torch 24 is directed upward and sequentially wets and washes the surfaces of the outlet pipes 13, finned tubes 8, inlet tubes 12 and radial dispensing tubes 6. In this case e refrigerated coolant temperature may be below ambient temperature up to 15-20% and, therefore, the air cooled system capacity can be increased.

In order to avoid overcooling of the coolant, shutters 22 are used, upon closing of which the air flow is reduced and the temperature of the coolant at the outlet remains design. To temporarily increase the output power, it is possible to allow (within the permissible limits) subcooling of the coolant.

An increase in the ambient temperature above the design temperature will lead to an increase in the temperature of the coolant, which in turn will lead to a decrease in the generated power, efficiency and excessive consumption of fuel at a constant electric load and in violation of the technological regime. In order to avoid violations of the technological regime, in the lower part of the air cavity 15 there are radially placed water nozzles 24 directed upward by the torch, when the water nozzles are turned on, the air cavity 15 under the covers 14 is saturated with water in the droplet phase, which sequentially washes the outlet pipes 13, finned tubes 8 , inlet pipes 12 and radial distributing collectors 6. In all of the above areas, water evaporates, removing heat energy from the structure, reduces the temperature of the coolant below the temperature urs ambient air by humidity difference between the environment and the surface of structural elements - the finned tubes. This phenomenon is subject to the dependence: the lower the moisture content in the ambient air, the higher the cooling efficiency by irrigation.

The technical and economic effect consists in improving the ecology of the industrial facility, namely the formation of water vapor above it is prevented, the intensity and frequency of acid rains and mists are reduced, and the sanitary-technical zone is becoming cleaner. There is an opportunity to build nuclear power plants in low-water areas.

Claims (4)

1. An air coolant cooling system comprising a pressure manifold with dispensing nozzles, a collecting manifold with outlet nozzles located below it, vertically mounted finned tubes in communication with the dispensing and outlet nozzles, gates located between the pressure and collecting manifolds, and an electric fan, characterized in that the pressure and collecting manifolds are ring-shaped, the dispensing and outlet pipes are mounted on the collectors in a checkerboard pattern radially and obliquely: the discharge nozzles are downward, and the outlet nozzles are upward, each nozzle being made up of pipes of variable diameter, which is reduced to the center, moreover, on the finned tubes along the dispensing nozzles, polyhedral casings are connected in steps that are interconnected by the lateral sides so that an air cavity is formed under them made in the form of a cylinder with a cone located inside with a vertex pointing down. 2. The air system according to claim 1, characterized in that the nozzles are radially mounted in the lower part of the air cavity. 3. The air system according to claim 1, characterized in that the sections of pipes located above the casing and under it are made with a compensation bend. 4. The air system according to claim 1, characterized in that the electric fan is installed above the pressure manifold.

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