DE102011050275A1 - Air-dried dry cooler - Google Patents

Abstract

Air-loaded dry cooler with pipes provided with cooling fins on the outside, the pipes being provided for a medium to be cooled to flow through on the inside and cooling air (K) to flow around on the outside, the fins at an angle of 5 ° to 60 ° to a perpendicular to the The longitudinal axis of the pipes is a transverse plane.

Description

The invention relates to an air-cooled dry cooler according to the features of patent claim 1.

Air-cooled dry coolers, in particular in the form of capacitors, serve for the direct condensation of fumes, in particular of turbine steam. They may be considered as a specific use form of air-cooled heat exchangers which serve to cool media (eg, steam or water) by ambient air in various processes of the chemical, petrochemical, and power industries. The heat exchangers used consist essentially of heat exchanger tubes, which are provided on the outside with ribs due to the poor thermal conductivity of air to improve the heat transfer. Several of these finned tubes are combined to form so-called tube bundles, which are exposed to a cooling air flow in areal construction. The cooling medium air is conveyed through the tube bundles with the aid of fans arranged in an inlet or outlet.

Frequently, the tube bundles are arranged roof-shaped over the fans. In order to ensure a supply of air at the lowest possible pressure losses, the roof-shaped arranged tube bundle with the fans arranged underneath are supported by a support structure. The turbine waste steam to be condensed is directed through an exhaust steam line and the subsequent steam distribution lines into the finned tubes.

In addition to the roof-shaped construction, air condensers also belong to the state of the art, in which the tube bundles extend in the vertical direction and form a closed jacket of a polygon ( EP 1 710 524 A1 ). Such a polygon requires less space, because a complex substructure is eliminated.

The resulting pressure losses have a significant influence on the efficiency of a dry cooler. The higher the effort required to convey cooling air through the dry cooler, the more energy is consumed by the fans. However, since such dry coolers are often used in power plants, which aim at a high overall efficiency of the entire system, in addition to the cooling power and the energy consumption of dry coolers is a very important factor. If, for example, it were possible to reduce the pressure losses between the air inlet side and the air outlet side of the dry cooler, more air could be transported through the tube bundles with the same drive power, so that a higher cooling capacity can be achieved. Conversely, with the same cooling capacity, the power consumption of the fans can be reduced. The power consumption can also be reduced by the fact that the angle of inclination of the roof-shaped arrangement is chosen to be smaller in the case of roof-shaped capacitors. However, this results in the roof-shaped construction becoming wider at the base. Due to the size of the capacitors (length approx. 10 m), however, an increase of the angle by only 1 ° would lead to a width increase of 310 mm at the base. At 5 ° it is already 1,550 mm. It should be noted that as a rule several rows of such capacitors are placed side by side, so that the space required by the condensation plant increases considerably. In addition, the cost of the supporting substructure also increases because more material must be expended in order to build the individual fan fields with the increased width.

There is also the possibility of making modifications in the area of the fans, for example by changing the angle of attack of the blades of the fans. As a result, the delivery rate can be adjusted. With increasing angles of attack at a constant speed, the delivery rate increases, but so does the energy consumption.

If the tube bundles are set up vertically, there is the problem that side wind can strike through the tube bundles due to the tubes running in this case and horizontally oriented ribs. If in such an arrangement usually air from the outside to the inside is to be sucked into a cell formed from tube bundles and is sucked up through a fan from the cell, the crosswinds lead to a highly uneven cooling effect of the individual tubes.

The invention is based on the object to show an air-dried dry cooler, which compared to conventional designs with finned tubes has a higher efficiency due to lower air-side pressure losses.

This object is achieved in an air-dried dry cooler with the features of claim 1.

The subclaims relate to advantageous, not self-evident developments of the inventive concept.

The luftbeaufschlagte dry cooler according to the invention, which can also be referred to as a heat exchanger and in particular as an air condenser, has a plurality of tubes which are provided on their outer sides with ribs. The pipes are for it provided to be flowed through by a medium to be cooled inside. Outside, cooling air flows past the ribbed pipes. It is essential that the ribs are at least predominantly in particular completely in an angle of attack of 5 ° to 60 ° to a plane perpendicular to the longitudinal axis of the tubes transverse plane. It is assumed that the ribs are perpendicular to the surface of the rib viewed in the radial direction. The angle of attack refers to the course of the ribs in the circumferential direction. The ribs may have elevations, depressions, recesses or turbulators, which, however, represent only local deviations from the overall straight course of the ribs in order to improve the cooling performance. The angle of attack, which is 0 ° in the prior art, refers to the overall course of a rib.

With the inclination of the cooling fins cooling air-side pressure losses, which are caused by the usually required sharp deflection at the air inlet side and the air outlet side of the cooling fins, can be reduced.

This effect is independent of the way in which the individual ribs are formed on the tubes or attached thereto.

The ribs may therefore be annular single ribs, for example, which are mounted on the tube.

The ribs may also be part of a ribbed band wound around the tube, the winding direction corresponding to an angle of attack of 5 ° to 60 °.

It is also possible that the ribs are formed by rolling out a pre-pipe pushed onto the pipe.

If the tubes are configured as flat tubes, it is also conceivable that ribs arranged on flat sides of the tubes are materially integral constituents of a corrugated ribbed strip. These corrugated fin ribbons may be directly connected via their respective arches to two adjacent tubes.

The inclined ribs can be used in all types of tube bundles combined tubes, regardless of whether it is a pressing or a sucking arrangement.

In an advantageous embodiment of the invention, the ribs over the course of the tube may have varying rib spacing. In particular, approaching a pipe end, the fin clearance between two adjacent ribs on one side of the pipe may decrease and increase on the opposite side. Since the tube ends of dry coolers open into tubesheets, which are perpendicular to the longitudinal axis of the tubes, resulting in a deviating from 90 ° to the longitudinal axis ribs a certain dead zone, in which the ribs would hit the tubesheets at an angle. In order to avoid this effect, it is conceivable that the angle of attack of those ribs which run adjacent to the pipe ends, is changed continuously, so that the rib adjacent to the tube plate is again parallel to the tube sheet. This inevitably means that on one side of the tube, the rib distance must be slightly increased, while the distance of the same pair of ribs on the other side of the tube is slightly smaller. For ribs that are part of a corrugated ribbed tape, the individual corrugations on one side of the pipe can be compressed slightly closer and stretched on the other side of the pipe. By a corresponding holding device, the thus-fixed ribbed tape can be connected to the tubes.

To avoid dead zones, it is possible to adapt the tubesheets to the orientation of the ribs. Ie. The tubesheets may be at an angle to the transverse plane of the tubes which is greater than 0 ° but less than or equal to the angle of attack of the ribs. Theoretically, an angle is conceivable that is greater than the angle of attack, but in this case again increase the dead zones. Preferably, the tubesheets are at the same angle to the longitudinal axis or transverse plane of the tubes as well as the ribs.

The dry coolers according to the invention have in particular a construction in which a plurality of ribbed tubes are combined to form a tube bundle, the tube bundles defining two legs of a triangular interior. The third leg is open for the passage of cooling air. The tube bundles have an air inlet side and an air outlet side for the cooling air, wherein the cooling air meets in a deviating from 90 ° angle of attack on the air inlet side and must be deflected to the inlet between the ribs. The angle of attack is oriented so that the air inlet and air outlet side deflection angle is reduced.

If a tube bundle z. B. is arranged at an angle of 30 ° to a vertical axis and the air flows from below into such a tube bundle, must be done at ribs which are at 90 ° to the longitudinal axis of the tube or the rib bundle, a deflection of 60 °. Due to the angle of attack of the ribs, this deflection angle can be reduced. The cooling air must be deflected less strongly. The pressure losses decrease. Also on the air outlet side is a less strong diversion required. Here it can be assumed that the heated cooling air at the air outlet side endeavors to flow off vertically upwards.

This reduces the pressure losses between the air inlet and outlet side of the tube bundle. This reduction of the pressure losses means that with the same fan power a larger amount of air can be forced through the tube bundles. The cooling capacity and thus the efficiency are improved. Conversely, with the same cooling capacity, the engine power of the fans can be reduced. The noise emissions and the own energy demand of the cooling system decrease.

In an advantageous development, it can be provided that the ribs have end sections shaped into guide vanes on their air inlet side and / or air outlet side, in order to further reduce the pressure losses resulting from the deflection of the cooling air. Due to the shaped end portions, the individual ribs may have an approximate L- or S-shaped contour.

The advantages of the invention are particularly useful in tube bundles, which are arranged in a roof shape and are arranged at an angle of 58 ° to 80 ° to each other, wherein the cooling air is conveyed through an arranged below the tube bundle fan in the direction of the tube bundle. It is a pressing arrangement, which can also be referred to as an A-shaped tube bundle arrangement.

The alternative embodiment provides tube bundles which form side walls of a cell in the form of a polygon closed on the circumference, wherein the side walls and the tubes extend in the vertical and wherein a fan is arranged above the polygon. It is therefore a sucking arrangement. The cooling air does not flow from below but laterally into the cell. In this embodiment, there are advantages because the susceptibility to crosswind can be reduced by the inclination of the ribs. The inflowing crosswinds must exit side, d. H. be less deflected on the inside of the cell. In addition, even in crosswind, the cooling air is diverted straight up through the slanted ribs.

The tube bundles, which due to their vertical orientation can also be referred to as stationary bundles, are preferably arranged on a dry cooling tower or around a dry cooling tower.

Regardless of the arrangement of the tube bundles, the ribs on the air inlet side can be arranged at a different distance from one another than ribs on the air outlet side. In particular, the rib spacing, i. H. the rib pitch, smaller on the air outlet side than on the air inlet side. As a result, a better utilization of the cooling fins and thus a better cooling performance or alternatively a material saving is effected.

In terms of production technology, it is simplest to provide ribs which have a uniform angle of attack, but in principle it is also possible to control the angle of attack over the course of the rib, ie. H. to vary in the flow direction of the air. It is possible on the air inlet side a first angle of z. B. 30 ° and on the air outlet side a different angle of z. B. 45 ° to choose. In this case, about one half of the rib can have the first angle of attack and the second half of the rib can have the second angle of attack. However, the division does not necessarily have to be made in half. A division is also conceivable in which the area of the rib which is flown first is greater than the region of the rib located downstream, with the deviating angle of attack.

In principle, it is also possible that the angle of attack over the course of a rib assumes more than just two discrete values. He can, for example, change continuously, for. B. in an arcuately curved rib. The rib may also have a substantially S-shaped course. An arcuate course can also result from individual segments with divergent angles of attack.

For divergent angles of attack it may also be advantageous to manufacture the individual rib sections separately from one another and to arrange them at the fixation on the tube such that the desired angle of attack results, for. B. by two ribs of the same or divergent rib division are arranged one behind the other.

The invention will be explained in more detail with reference to the embodiments illustrated in schematic drawings. It shows:

1 a schematic representation of a dry cooler in A-shape or roof construction according to the prior art;

2 a schematic representation of a dry cooler in A-shape or roof construction;

3 a single tube of a tube bundle of a dry cooler according to 2 ;

4 another embodiment of a tube with ribs;

5 another embodiment of a tube with ribs;

6 another embodiment of a tube with ribs;

7 Another embodiment of a tube with ribs and

8th another embodiment of a tube with ribs.

1 shows a dry cooler 1 in A-construction, as it is known in terms of its basic design in the prior art. The dry cooler 1 is on a steel framework 2 mounted, so that cold cooling air K laterally in the horizontal direction under the dry cooler 1 in the steel frame 2 can flow in. The cooling air flow is in its further course by the fan 3 sucked in this case by 90 ° in the direction of the vertically oriented inflow or the fan race 4 diverted. The cooling air flow enters the interior of the fan 3 and the tube bundles arranged in an A-shape 5 . 6 limited space of the dry cooler 1 in the vertical direction and flows the non-illustrated ribbed tubes of the tube bundle 5 . 6 at. In this case, the cooling air flow from the vertical direction is deflected a second time and when entering the tube bundle 5 . 6 braked. The cooling air K is heated in this case and flows laterally out of the tube bundles 5 . 6 out. Laterally the tube bundles 5 . 6 arranged wind walls 7 prevent re-suction of the heated cooling air K by the fan 3 and lead them upwards in a vertical direction. As a result, the cooling air flow is deflected once more. In total, there are several deflections of the cooling air flow, which leads to high air-side pressure losses within the arrangement.

By contrast, in the case of the dry cooler according to the invention 8th as he is in 2 is shown, provided that the deflection in the region of the tube bundle 5 . 6 less severe by the ribs of the tubes are inclined by a certain angle. This will be explained below with reference to 3 explained.

3 shows a pipe 9 , the outside with ribs 10 is provided. At the pipe 9 it is a flat tube looking towards one of two flat sides 11 on which the ribs 10 are attached. The longitudinal axis L of the pipe 9 runs at an angle W1 of 30 ° to a vertical axis. The arrow K shows that cooling air from below on the pipe 9 flows.

Ribs 10 are in this embodiment at an angle W2 of 30 ° to 85 ° to the longitudinal axis L. However, reference will be made below to the angle of attack W3, which is related to a perpendicular to the longitudinal axis L extending transverse plane Q. With an assumed angle of attack W3 of, for example, 20 °, the cooling air K must be at an air inlet side 12 by a deflection angle W4 = 90 ° - W1 - W3, ie in this case by 90 ° - 30 ° - 20 ° = 40 ° to be deflected. The same conditions arise on an air outlet side 13 , Also there is a deflection by only 40 ° instead of 60 ° required. This allows the air-side pressure losses at the air inlet and the air outlet side 12 . 13 be significantly reduced.

3 shows that at the ends of the pipe 9 tube sheets 14 . 15 are arranged, with some of the tube sheets 14 . 15 adjacent ribs 10 inevitably due to the angle of attack W3 not over the entire width of the tube 9 can extend, but at the tube sheets 14 . 15 end up. As a result, dead zones T are formed in the end region in terms of flow. These dead zones T are of the total length of the tube 9 from Z. B. 10 m, however, are relatively small and depending on the angle of attack W3 of the ribs 10 in the order of <1%. For example, the dead zone T at an angle of attack W3 of 5 ° is only 0.17% of the pipe length. At an angle of attack W3 of 20 °, the proportion of the dead zone T increases to 0.69% of the pipe length. These values are relatively low. If the dead zone T should be kept as small as possible, it is expedient to choose the angle of attack W3 in a range of 5 ° to 20 °.

Basically, there must be an optimum of the inclination of the ribs 10 be determined because with each degree of inclination of the ribs 10 At the same time a certain rib section can not be supplied with cooling air K.

It should also be noted that the length of the individual ribs 10 increased at an initial length of 190 mm at an angle of attack W3 from 0 ° to 190.8 mm at 5 °, to 192.8 mm at 10 °, to 196.5 mm at 15 ° and to 202.1 mm at 20 ° , The extension of the rib 10 leads to a slightly lower cooling efficiency, but which can be compensated by an optimal inclination while reducing the pressure losses by a multiple.

Due to the inclination of the ribs 10 can be increased from the reduction of the air-side pressure loss either the cooling capacity at a constant own use or the domestic demand can be reduced with constant cooling capacity. It is also conceivable to increase the rib pitch, ie the rib spacing, without reducing the cooling capacity per square meter of cooling surface. This would mean a saving of material and thus a cost reduction. Another not negligible effect is that with a reduction of the fan power at the same time results in a reduction of sound immission.

Preferably, the rib pitch is 2.3 mm +/- 0.1 mm. This rib distance is always to be measured perpendicular to the rib course. That means, even with slanted ribs 10 the rib division remains the same. The rib distance should in the non-scale embodiment of the 3 constant 2.3 mm. As a result, the material used remains the same compared to non-slanted ribs.

4 shows an embodiment in which, unlike the execution of the 3 Ribs 10 at the tube ends not on the tubesheets 14 . 15 run, but are fanned out. That is, the rib spacing of two adjacent ribs 10 in approach to the tube sheets 14 . 15 be changed so that the last rib 10 parallel to the tubesheet 14 . 15 runs. This requires the rib spacing on one side of the tube 9 slightly enlarged and on the opposite side of the pipe 9 to be downsized a bit. This creates the fan shape. Also in terms of manufacturing technology, there are advantages as individual ribs 10 do not have to be cut to the Rippenverlaufsrichtung crossing. Depending on the angle of attack of the ribs 10 This results in material savings on the order of the percentage values calculated above as deadband T relative to the length of the tube 9 have been specified.

5 shows a further embodiment of a tube 9 in which the tube sheets 14 . 15 at an angle W4 to the transverse plane Q stand. In this embodiment, the angle W4 corresponds to the angle of attack W3 of the ribs 10 , This is how the tube sheets run 14 . 15 parallel to the ribs 10 , In this way, dead zones can be reduced or avoided. Preferably, the angle W4 is equal to the angle of attack W3, because in this case dead zones are avoided to 100%. It is also conceivable that the angle W4 is smaller than the angle of attack W3. By this way, the dead zones can be at least reduced. The tube sheets 14 . 15 Depending on the installation situation, they may occupy different angles W4 to the transverse plane. It is therefore conceivable that only one of the tube sheets 14 . 15 opposite to the transverse plane Q is arranged at an angle.

6 shows an embodiment of a tube 9 in which ribs 10a to end vanes shaped end sections 16 have, each pointing in the direction of the air inlet and the air outlet. This also allows the pressure losses between the air inlet side 12 and the air outlet side 13 be minimized.

7 Finally, shows an embodiment in which two rows of ribs are provided. It can be clearly seen that the rib pitch, ie the distance between those ribs 10 that the air-entry side 12 are facing, is greater than the distance of those ribs 10b on the air outlet side 13 , In this way it is possible to increase the heat transfer and thus the cooling performance even further. It can be seen that the angle of attack both in the ribs 10 on the air entrance side 12 as well as the ribs 10b on the air outlet side 13 are the same.

8th Finally, shows an embodiment in which the distance between the ribs ( 10b ) on the air outlet side ( 13 ) is also less than the distance between the ribs ( 10 ) on the air entry side ( 12 ). In addition, the ribs ( 10b ) on the air outlet side ( 13 ) a larger angle of attack (W5) to the transverse plane (Q) of the tubes ( 10 ), than the ribs ( 10 ) the air entry side ( 12 ). Ribs ( 10 ) on the air entry side ( 12 ) are also longer than the ribs ( 10b ) on the air outlet side ( 13 ). Due to the modified rib geometry, the heat transfer is increased once again, thus further increasing the cooling capacity.

LIST OF REFERENCE NUMBERS

1

dry coolers

2

steel scaffolding

3

fan

4

Fan race

5

tube bundle

6

tube bundle

7

wind Wand

8th

dry coolers

9

pipe

10

rib

10a

rib

10b

rib

11

flat side

12

Air inlet side

13

Air-outlet side

14

tube sheet

15

tube sheet

16

end

K

cooling air

L

longitudinal axis

Q

transverse plane

T

dead zone

W1

angle

W2

angle

W3

angle of attack

W4

angle

W5

angle of attack

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1710524 A1 [0004]

Claims (13)

Air-cooled dry cooler with ribs on the outside ( 10 . 10a ) provided pipes ( 9 ), whereby the tubes ( 9 ) are provided for, flows through the inside of a medium to be cooled and outside of cooling air (K) are flowed around, the ribs ( 10 . 10a . 10b ) at least predominantly in an angle of attack (W3, W5) of 5 ° to 60 ° to a perpendicular to the longitudinal axis (L) of the tubes ( 9 ) extending transverse plane (Q) are. Dry cooler according to claim 1, characterized in that the ribs ( 10 . 10a ) are formed as annular single ribs with round, elliptical or rectangular shape, which on the tube ( 9 ) are raised. Dry cooler according to claim 1, characterized in that the ribs ( 10 ) Are part of a ribbed tape wound around the pipe, the pitch in the winding direction being at an angle of incidence (W3) perpendicular to the longitudinal axis (L) of the pipes ( 9 ) extending transverse plane (Q) of 5 ° to 60 ° corresponds. Dry cooler according to claim 1, characterized in that the ribs ( 10 ) from an outside on the tube ( 9 ) pushed forward tube are formed by rolling. Dry cooler according to claim 1, characterized in that the tubes ( 9 ) are configured as flat tubes, wherein the ribs ( 10 . 10a . 10b ) on flat pages ( 11 ) of the pipes ( 9 ) are arranged and are uniform material integral components of a corrugated ribbed tape. Dry cooler according to one of claims 1 to 5, characterized in that the ribs ( 10 ) over the course of the tube ( 9 ) have varying fin spacings, wherein, closer to a tube end, the fin spacing between two adjacent ribs (FIG. 10 ) decreases on one side of the tube and increases on the opposite side. Dry cooler according to one of claims 1 to 6, characterized in that a plurality of ribbed tubes ( 9 ) to a tube bundle ( 5 . 6 ), wherein the tube bundles ( 5 . 6 ) define two legs of a triangular-shaped interior, wherein the third leg for the passage of cooling air (K) is open, and wherein the tube bundles ( 5 . 6 ) an air entry side ( 12 ) and an air outlet side ( 13 ) for the cooling air (K), wherein the cooling air (K) to the air inlet side ( 12 ) and to the entry between the ribs ( 10 . 10a . 10b ), wherein the angle of attack (W3, W5) is oriented so that a deflection angle is reduced. Dry cooler according to claim 7, characterized in that the tube bundles ( 5 . 6 ) are arranged in roof form and are arranged at an angle of 58 ° to 80 ° to each other, wherein the cooling air (K) by a below the tube bundle ( 5 . 6 ) arranged fan ( 3 ) in the direction of the tube bundles ( 5 . 6 ). Dry cooler according to one of claims 1 to 8, characterized in that the tube bundles ( 5 . 6 ) Form side walls of a cell in the form of a peripherally closed polygon, wherein the side walls and the tubes ( 9 ) extend in the vertical and wherein above the polygon a fan is arranged. Dry cooler according to one of claims 1 to 9, characterized in that the ribs ( 10a ) on its air inlet side ( 12 ) and / or air outlet side ( 13 ) end sections ( 16 ) in order to reduce the pressure losses due to deflection of the cooling air (K). Dry cooler according to one of claims 1 to 10, characterized in that ribs ( 10 ) on the air entry side ( 12 ) are arranged at a different distance to each other than ribs ( 10b ) on the air outlet side ( 13 ). Dry cooler according to one of claims 1 to 11, characterized in that the ribs ( 10b ) on the air outlet side ( 13 ) at an angle (W5) to the transverse plane (Q) of the tubes ( 9 ), which depends on the angle of attack (W3) of the ribs ( 10 ) on the air entry side ( 12 ) deviates. Dry cooler according to one of claims 1 to 12, characterized in that the tubes ( 10 ) end with tube sheets ( 14 . 15 ), wherein at least one tubesheet ( 14 . 15 ) at an angle (W4) to the transverse plane (Q) of the tubes ( 10 ), wherein the angle (W4) is greater than 0 ° and less than or equal to the angle of attack (W3).

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