FR2543282A1 - CLOSED REFRIGERANT WITH FORCED VENTILATION AND WATERTIGHT CIRCUIT - Google Patents

Abstract

THE EXCHANGER CIRCUIT 7 IS COMPOSED OF ELEMENTS 12 SHAPED BY HORIZONTAL TRUNKS OF THE CIRCULAR FINTED TUBES WHOSE LOWER PART IS ECHANCED. THE TUBES MAY BE OFFSET ON EACH OTHER OF A COMMON VERTICAL PLANE. THE ELEMENTS ARE ARRANGED SIDE BY ONE OVER THE ENTIRE SURFACE OF THE ENCLOSURE 1. THE HOT FLUID INLET 17 IS PROVIDED AT ONE END OF THE UPPER TRUNKS AND THE COOLED FLUID OUTLET 20 AT ONE END OF THE LOWER TRUNKS. A COOLING WATER TREATMENT STATION 11 INCLUDES A COMPENSATION CIRCUIT 10 FOR THE WATER LOST BY EVAPORATION, MEANS FOR MEASURING THE ACIDITY OF THE WATER ALLOWED BY THE COMPENSATION MEANS AND MEANS OF DISCHARGE CONTROL OF RECYCLED COOLING WATER. A NOTCH IS PROVIDED IN THE LOWER PART OF THE FINS.

Description

The invention relates to a closed ventilated refrigerant.

  forced and sealed circuit comprising an enclosure, open upwards, connected to forced ventilation means, means for spraying cooling water, and an exchanger circuit, in which the fluid to be cooled is disposed, arranged so as to receive water from

means of spraying.

  The use of large thermal machines

  power by industry and, in particular, in the cen-

  thermal or nuclear power generation,

  requires removal of degraded heat This is ob-

  held by circulation of a heat transfer fluid which is charged

  calories we want to get rid of.

  When the fluid is water, an evacuation

  direct could be considered, but this is not possible.

  ble for many reasons and, in particular, to avoid

  ter thermal pollution of rivers or as a result of

  limited water flow The water is then cooled by trickle-

  lying on bleachers or screens in an air circulation.

  The cooling being a function of the height of fall, the refrigerators reach large sizes and the vaporization of a part of the water forms mists which

  create an undesirable micro-climate.

  In the case where the heat transfer fluid cannot be brought into direct contact with the cooling air, it is

  forced to use closed circuit heat exchangers in the

  which the fluid passes through tubes on which water is made to flow in an air stream Such a refrigerant

  is known from French patent N O 2 319 098 the fluid to be

  cooling passes through exchangers made up of a bundle of parallel tubes held together by fins Several exchangers are arranged in steps inside

  a cooling tower, so that the axis of the tu-

  bes makes an angle of between 15 and 450 with respect to the vertical Projection ramps are provided above the exchangers and project water onto the fins against which it trickles Air circulation is ensured

by natural draft in the tower.

  The refrigerant described above would allow a reduction in dimensions compared to those of conventional towers, and the rejection of a small quantity of vapor into the atmospheric air from which results in a saving in cooling water and the elimination harmful micro-climates. The refrigerant according to the invention has as

  known a tubular exchanger, a sprinkling of cooling water

  but has a continuous tubular heat exchanger

  preferably cutting all the air-swept area

  cooling may be provided by mechanical means

  ventilation ques The efficiency of the exchanger is, in

  tre, augmented by a particular shape of the fins pre-

  views of the tubes and - by unusual operating conditions of the sprayers allowing uniform wetting of the finned tubes of the exchanger, The loss of efficiency of the exchanger by formation of deposits on the exchange surfaces is eliminated by the

  cooling water flow treatment and control

recycled.

  The explanations and figures given below to

  example will help understand how the invention

tion can be achieved.

  Figure 1 is a schematic sectional view of a

  refrigerant according to an embodiment of the invention.

  Figures 2 and 2 A are partial sectional views, on a larger scale along II II of Figure 1 of

  two embodiments of the refrigerant.

  Figures 3 and 3 A are sectional views of a

  finned tube according to two exemplary embodiments.

  Figures 4 and 5 are sectional, plan and side views of a sprayer and the shape of the c 8

spray.

  The refrigerant, according to the embodiment re-

  shown schematically in Figure 1, consists of a

  girdle 1 of rectangular shape open at its upper end

  One of the sides of the enclosure is fitted with one or more fans 2 The watertight lower part of

  the enclosure serves as a collecting tank 3 for the cooling water

  cooling A drain pipe 4 and a canali-

  Suction station 5 are provided on the recovery tank.

  tion The suction line 5 is connected to a circulation pump 6 whose r 8 will be specified later. At the upper part of the enclosure is arranged a

  exchanger 7 consisting of parallel rows of tubes with ai-

  lettes in which the fluid to be cooled circulates from above

below.

  Ramps 8 of sprayers are arranged at-

  above the top rows of tubes and are fed

  through the circulation pump 6 The pul-

  verisers are distributed in a square arrangement.

  The opening of the enclosure is provided with a separa-

  tor 9 in which the cooling air flow abandons-

  do the water droplets - which he took care of while crossing

water spray.

  As the principle of cooling

  rants with forced ventilation is based on the fact that a par-

  tie cooling water is evaporated, a compensation circuit 10 is provided which is connected to the station

  treatment 11 supplying the coolant with cooling water

  sement. The industrial water commonly used in installations is generally loaded with mineral salts and a suspension of organic matter. The salts produce

  surface of the hot exchanger tubes of deposits which are bad

  go heat conductors and organic materials facilitate the proliferation of algae and moss in the recovery tanks To avoid these drawbacks, the water is treated in the treatment station 11 The water being

  generally loaded with calcium carbonates, we transform

  me these into more soluble sulfates by acidification with sulfuric acid In order to avoid corrosion of the ferrous parts (enclosure, tubes, etc. O), an inhibitor is added

corrosion.

  FIG. 2 represents a part of the refrigerant according to section II II The exchanger 7 is formed from horizontal tubes with fins, at least partly circular,

  occupying the entire surface of the enclosure.

  According to the embodiment shown, a

  element 12 of the exchanger, through which the coolant flows

  dir, is constituted by a tube formed by four sections of finned tubes, parallel in the vertical plane (figure 1) and horizontally offset as shown for the tubes 139 14, 15, 16 (figure 2) But the invention can be also apply to other cor-figurations For example figure 2 A,

  -the sections of finned tubes are arranged one at a time

  above the others These sections are connected to each other

  very by elbows welded at their ends The fluid

  hot arrives in a distributor (not shown) on the

  which are connected in parallel the upper inputs 17

  elements 129 18, 19, etc. the cooled fluid is collected

  found in a collector (not shown) on which are

  connected the lower outputs 20 of the preceding elements.

  The cooling water from the cooling tank

  cuperation is sent in ramps 8 provided at intervals

  21 regular sprayers producing a drop cone

  lettes evenly distributed throughout the horizon section-

  This result is obtained by unusual operation.

  sprayers and allows uniform cooling

  me tubes in the droplet cone Les

  known sprayers, used in refrigerants, pro-

  have a cone of droplets in which they are distributed in a ring leaving an almost dry interior zone We also know of sprayers at the outlet of which a mobile element carrying helical grooves Tdales, allows the formation of a supper uniformly distributed droplets These devices are relatively expensive and their reliability does not allow them to be used without control. A known sprayer, represented in FIGS. 4 and 5, comprising a swirl chamber, gives, for a

  pressure drop in the sprayer of O% 75 bar, an

  conical hollow hollow of fine droplets.

  Its supply with water for a pressure drop of 0.2 bar highlighted the formation of a pinch 23 of the jet which then deploys in the form of a full c 8

  larger, evenly distributed drops.

  The droplet side allows uniform and efficient cooling with low water consumption

finned tubes.

  Another measure taken to increase the ef-

  efficiency of the exchanger is the indentation of the part

  of the circular fins of the tubes In the example

  shown, the top three rows of finned tubes

  your have modified fins Figure 3 shows in section a tube provided with a notched fin in its lower part The notch 24 has an angular profile

  in the embodiment illustrated in Figure 3 From-

  very profiles could be provided Thus, Figure 3 A, the

  groove 24 has a curved profile, for example sensi-

definitely circular.

  Wet cooling calf droplets

  suitably slow the upper row (or first row

  ) of finned tubes Due to the small separation space

  By the fins of two neighboring tubes of the same horizontal row, the second row is only slightly affected by the droplets and receives almost only the water from

  runoff from the upper row The pheno-

  leads reproduces a fortiori for the third and fourth rows So that water passes from the fins of a hot tube of a row to the fins of a less hot tube near a

  immediately lower row, the droplets that leak

  saddle on the fins come together in the form of drops at the ends of the notch and fall on the

  fins of the tubes next to the row immediately below

  better. The cooling water flow of a

  row to row is clearly shown in figure 2, 2 A

  notch 24 must be such that its ends 25 (protrusion

  formed by the connection between the perimeter circular part

  wing spherical and notch) are plumb

  fins of the corresponding lower tubes and

  vertical junction, between the wall of the tube (a) and the edge

wing (b).

  The dimensions of the fins and their notch

  re are however dependent on the compactness of the exchanger which is defined to allow air circulation

  under low pressure without significant pressure drop.

  Recycling of provo-

  that, despite the compensation for evaporated water, a concentration

  salt tration which could reach such a value

  that cooling would be seriously reduced

  naked; also the treatment station 11 comprises means for metering the acidity of the cooling water admitted by the compensation circuit 10 and controlled discharge of the recycled cooling water. This rejection controlled by

  a valve 30 makes it possible to eliminate the water too loaded with salts.

  The supply of treated water makes it possible to compensate for the flow of evaporated water and the flow of deconcentration. The means used, known per se and maintaining the concentration of

  salts at a given value, allow better

efficiency of the refrigerant.

  According to the embodiment, the exchanger comprises

  carries four horizontal rows of tubing but it can

  have only two or three rows, the choice being

  finished with the quantity of heat to be evacuated.

  In a refrigerant according to an exemplary embodiment

  tion of the invention, the exchanger consists of elements comprising four sections of finned tubes arranged according to FIG. 2 The central tube has an outside diameter of approximately 25.4 mm (1 inch) and the fins, of about 57 mm The tubes are distant in horizontal projection of

  mm and in vertical projection, 55 mm The rope under

  stretched by the notch is 25 mm and the distance from its

  central part in the center of the tube, 17 mm.

  The speed of the air delivered by the fans

is between 2 and 6 m / s.

  The air inlet temperature is 15 to 250 C

  and the outlet temperature of the humid air, from 25 to 3000.

  Cooling water consumption per m 2

  front surface of the exchanger (i.e. perpendicular

  air flow) is: for sprayed water 100 g s-1 m 2 for evaporated water 20 to 25 g s m for recycled water rejected 20-to 25 g s m 2

  With the previous characteristics, the-then-

  evacuated heat output is 70 to 80 KW m-2.

  Compared to a refrigerant without spraying

  cooling water, multiply the coefficient of

  changes by two, without changing the pressure drop O

Claims (7)

  1 Closed refrigerant with forced ventilation and sealed circuit with an enclosure open to the   high, means of forced ventilation, means of suction   sion of cooling water and an exchanger circuit, in which the fluid to be cooled circulates, arranged so as to receive the water coming from the spraying means and passed through   by the air flow produced by the ventilation means   çée, the cooling water being recycled, characterized in that the exchanger circuit (7) consists of elements (12) formed by substantially horizontal sections of   finned tubes, the elements being arranged one beside the other   tee of the others in horizontal rows and in that the ai-   lettes have a notch in their lower part.   2 Refrigerant according to claim 1, character-   laughed in that the notch has an angular profile.   w Refrigerant according to claim 1, character-   laughed in that the notch has a curved profile.   4 Refrigerant according to any one of the res-   dications 2 to 4, characterized in that the indentation of a   finned tube is made in such a way that its ends   mites (25) lie directly above the fins of the corresponding lower tubes and project vertically   between the wall of the tube (a) and the edge of the fin (b).   Refrigerant according to any one of the preceding claims, characterized in that the fins   are, at least partially, circular.   6 Refrigerant according to any one of the res-   dications preceding, characterized in that the sprinkling is done vertically from top to bottom and against the current 3 of the cooling air flow O   7 Refrigerant according to any one of the res-   dications preceding, characterized in that the spraying means comprise sprayers with swirl chamber fed under a reduced pressure difference   to produce a cone full of evenly distributed drops ties. 1 2543282   8 Refrigerant according to any one of the res-   dications previous, characterized in that the inlet (17) of the hot fluid is provided at one end of the sections   upper and the outlet (20) of the cooled fluid is pre-   view at one end of the lower sections.