DE202004004397U1 - Air-cooled dry cooler for condensing water vapor - Google Patents

Abstract

Air-cooled dry cooler for condensing water vapor, the inclined cooling elements (10, 11) of which have finned tubes connected on the one hand to an upper steam distribution line (12) and on the other hand to a common condensate collecting line (13), and which has at least one counterflow condenser (dephlegmator), the cooling elements (10, 11) are arranged in a V-shape and form adjacent legs of a triangle standing on the tip, in which the cooling elements (10, 11) are arranged inclined at 45 ° to a horizontal, the inflow surfaces of the cooling elements (10, 11) facing away from each other and the outflow surfaces of the cooling elements (10, 11) facing the interior of the triangle, at least two fans (9) being provided in the region of an upper leg of the triangle, and wherein cooling air heated by the cooling elements (10, 11) through the Fans (9) can be extracted from inside the triangle.

Description

It is state of the art, exhaust steam to condense from a steam turbine with an air-cooled condenser. It flows the exhaust steam from the turbine through an exhaust pipe and enters in bundles of finned tubes Cooling elements, so-called finned tube bundle in which the steam is condensed. The condensate is in returned the feed water circuit. The Finned tubes are under vacuum on the inside, the non-condensable ones Gases are extracted. The cooling air flow is generally generated with fans. The dry coolers will assembled according to the modular principle, the roof construction (A arrangement) is the most common. Here form the cooling elements the legs of a triangle, at the base of which the fans are arranged are. The cooling elements are for this purpose arranged on a platform by a substructure Steel or concrete is worn. The fans are in the platform arranged, which suck in the ambient air as cooling air and over the Outer surfaces of the Press finned tubes. The cooling air takes the heat of condensation of the condensing water vapor and leaves the finned tube bundle as warm exhaust air the outside the order.

This arrangement is disadvantageous the very complicated flow path the air, which is caused by turbulence, numerous deflections and permanent Acceleration and deceleration the air flow to a high degree so-called secondary losses leads. These secondary losses can only be conveyed through high static pressure Air volume can be compensated, which means a high energy requirement for the fans connected is.

Another disadvantage of the oppressive The arrangement is the inclined flow in the Fan entry, reducing the static efficiency of the fan across from an ideal vertical flow decreases by a few percentage points.

With fans arranged in a pressing manner arise when the cooling air exits from the fan race and when entering the attic below the finned tube bundle strong turbulence in the air flow. These lead to a very uneven air distribution on the upstream side the finned tube bundle. Leading in turn, a loss of efficiency in heat transfer during condensation.

For example, in the prior art Process cooling arrangements pressing and sucking from the chemical industry known. Also become water coolers in the most common Operated with suction. The fan can be used immediately on a cooling element be arranged so that there is a vertical flow against the finned tubes. It is also possible, that of several spaced-apart cooling elements a chamber is formed, on the top of which the fan is arranged. Cold cooling air is sucked in transversely, flows through the cooling elements and is after a Redirection by 90 ° vertically dissipated upwards. Also V-shaped Arrangements of the cooling elements are known. For water coolers one falls back on a suction arrangement because the temperature gradients of the cooling water and the warming one cooling air run relatively flat and the temperature difference is therefore relatively small is. This also means that due to the thermal expansion The volume flow increases relatively little. The volume of cooling air increases with the usual Temperature differences between inlet temperature and outlet temperature approximately by 2% and 4%. In contrast, the temperature difference of the cooling air flow for surface capacitors significantly larger. consequently is the volume of the heated Cooling air flow also bigger. at surface condensers should an 8% larger funding volume coped with by a fan that must convey heated exhaust air instead of cold ambient air. Consequently, surface capacitors basically a pressing arrangement for condensing water vapor preferred, the required increased static pressure of the to be promoted Air volume is accepted.

From DE-AS 1 263 789 is already an air-cooled surface condenser known in V-construction, in which cooling elements and a fan form an approximately isosceles triangle. This arrangement is fluidic not optimal as the cooling air on the outflow surface of the cooling elements must be strongly redirected.

The invention is based on this based on the task of an air-cooled dry cooler for To show condensation of water vapor, which with constant cooling capacity and constant fan efficiency the use of fans with less power required, and a smaller design with an associated reduction in material allows.

This task is with a dry cooler the features of protection claim 1 solved. Advantageous configurations of the inventive concept are the subject of the dependent claims.

In a departure from the usual A-shape or roof construction with a pressing arrangement, a V-shaped arrangement of the cooling elements is provided in the dry cooler according to the invention, the cooling air being drawn through the cooling elements by at least two fans arranged next to one another. In addition, the cooling elements are arranged at right angles to each other. Each cooling element is inclined at 45 ° to the horizontal. This enables an optimal flow with minimal deflection and reduced overall height. Such an arrangement has decisive advantages with regard to the energy balance, since far fewer redirections of the cooling air flow are required than in the pressing arrangement. This enables a more even speed curve for the cooling air.

Another advantage is that at least two, preferably three fans between the steam distribution lines can be arranged so that due to the positioning of the fans alone an air intake from below and an air release upwards is possible without the entire Arrangement on an elevated steel scaffolding must be installed. The overall height is due to the inclination of the cooling elements by 45 ° in total lower than the A-shape and other known V-shapes, from which additional Savings in steel construction result. While in realized dry coolers construction heights of 16 m not unusual are the overall height in the arrangement according to the invention be reduced by at least a third. It is even a reduction the overall height possible by 50% within the scope of the invention. This reduction in overall height results itself both when the cooling elements V-shaped are arranged standing on the floor as well as with arrangements, where the cooling elements V-shaped in a steel frame hanging are arranged.

Advantageous embodiments of the The concept of the invention is the subject of the dependent claims.

The invention is described below of the embodiments shown in schematic drawings and diagrams explained. Show it:

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

2 a schematic representation of the dry cooler according to the invention;

3 a diagram showing the air speed at different locations of a dry cooler in roof construction;

4 in the representation of the 3 the flow rate ratios in the dry cooler according to the invention and

5 and 6 a comparison of the pressure losses in a dry cooler in A design and in V design.

1 shows a dry cooler 1 in V-construction, as is known in the prior art. The dry cooler 1 is on a steel frame 2 mounted so that cold cooling air laterally in the horizontal direction under the dry cooler 1 into the steel frame 2 can flow in. The cooling air flow is continued by the fan 3 sucked in and thereby by 90 ° in the direction of the vertically oriented inflow opening or the fan race 4 diverted. The flow of cooling air enters the interior of the fan 3 and the V-shaped cooling elements 5 . 6 limited space of the dry cooler 1 in the vertical direction and flows the finned tubes of the cooling elements, not shown 5 . 6 on. The cooling air flow is redirected again from the vertical direction and when entering the cooling elements 5 . 6 heavily slowed down. The cooling air is heated and flows out of the cooling elements 5 . 6 out. On the side of the cooling elements 5 . 6 arranged baffles 7 prevent the heated cooling air from being drawn in again by the fan 3 and lead them up in the vertical direction. This redirects the cooling air flow again. In total, there is a deflection of the cooling air flow by at least 180 °, which leads to high static pressure losses within the arrangement and only through increased performance of the fan 3 can be compensated.

In contrast, in the dry cooler according to the invention 8th as he is in 2 is shown, provided that the already heated cooling air from the fans 9 is promoted. In the arrangement shown there are cooling elements 10 . 11 Configured in a V-shape, with steam distribution lines at their upper ends 12 are connected and with their lower ends to capacitor busbars 13 are connected. The individual finned tubes of the cooling elements 10 . 11 are not shown in detail to simplify the representations.

The fans arranged side by side 9 are located between the steam distribution lines 12 and form together with the cooling elements 10 . 11 a triangle. This triangle stands with the tip down on the floor, so that the entire arrangement has a significantly lower overall height than the embodiment of FIG 1 , This is particularly due to the fact that the dry cooler according to the invention 8th does not have to be mounted on a stand, as the fans are arranged on the top 9 a lateral inflow of the cooling air into the interior of the triangle through the cooling elements 10 . 11 through is possible. The horizontally sucked-in cooling air flow K is deflected by approximately 45 ° in the area of the cooling elements and flows after a further deflection by approximately 45 ° of the vertical inflow opening 14 of the fan 9 to. In the fan race 15 the heated cooling air is accelerated and blown upwards. Overall, the flow of cooling air results in significantly fewer deflections than with the A design. The flow losses are significantly lower.

3 shows the flow velocities listed in Table 1 at various locations of an air cooler in A design.

It is clear that with the A design or roof shape the air speed in the horizontal inflow approximately is 4 m / s. This speed is also the case with the redirection into the vertical inflow maintained. When entering the fan race, the air speed increases by more than double to over 8 m / s to build up the high static pressure inside the dry cooler. The air flow will then when entering the cooling elements decelerated to only 2 m / s, which with considerable flow losses accompanied. The air velocity is between the fins of the finned tube bundle increased due to the narrowed flow channels. Because of the subsequent enlargement of the cross-section decreases as it exits again. The one from the cooling elements emerging currents then unite to a vertically oriented exhaust air flow, the flow velocity is approx. 5 m / s. It can be seen that the flow rate from a relatively low level initially by adding Energy is raised sharply and then braked sharply, before heading towards the outflow opening again increases.

In contrast, the speed ratios of the cooling air flow in the arrangement according to the invention are much more uniform and harmonious. 4 shows that in the V-shaped arrangement of the cooling elements, the air velocity in the horizontal inflow is about 1.5 m / s and on et which is increased above 2 m / s in the area of entry into the cooling elements. Due to the previously described circumstances, the flow velocity between the fins increases and after exiting it drops to about the level as before entering the cooling elements. The heated individual cooling air flows are then deflected into a vertical flow, but the flow speeds prevailing inside the dry cooler only increase slightly. Only within the fan race is a higher air speed measured, which is approximately 6.5 m / s, which essentially corresponds to a doubling of the flow speed in the interior of the dry cooler. It can be seen that the air speeds over the flow path tend to increase continuously, with the cooling air not experiencing any energy-consuming deceleration. This is also reflected in the static pressures that can be measured within the dry cooler arrangement.

5 and 6 show the static pressure losses in Pa. They are plotted over the respective location of the pressure loss. The exact values are shown in Table 2.

It can be seen that the loss of inlet pressure, the pressure loss of the fan guard, the pressure loss of the fan bridge and the pressure loss when entering the cooling elements is seen individually and are also relatively small in total. The greatest pressure loss occurs inside the cooling element on. The losses when exiting the cooling elements as well as dynamic Pressure losses at the outlet are again relatively low. Less the Natural draft results in a pressure loss in the known arrangement between 120 and 140 Pa.

In contrast, pressure losses were measured in the arrangement according to the invention, which in 6 are shown. Due to the suction arrangements, pressure losses occur relatively early, particularly within the cooling element, but both the loss of entry into the cooling element and the loss of exit from the cooling element are significantly lower with the V-type construction than with the A-type construction, so that taking into account the others Pressure losses and the natural draft results in a total loss of static pressure of less than 100 Pascal. In the comparison it becomes clear that this results in a reduction of the static pressure of about 30%. However, the delivery volume increases by approx. 8%, since heated cooling air now has to be extracted. Since the fan output is proportional to the flow rate and proportional to the difference in static pressures, the fan output is reduced by approx. 25% with constant fan efficiency. This results in considerable savings potential in the operating costs of such a system. At the same time, the power plant efficiency is improved. Since the fan's sound emission is directly linked to its power requirement, a 25% lower power consumption also results in a reduction of the sound power level by approx. 1 dB (A).

Basically, it is also possible to use the Keep fan output constant, with the same cooling output a reduction in the cooling surface by 10 % possible is.

1

dry coolers

2

steel scaffolding

3

fan

4

Fan race

5

cooling element

6

cooling element

7

baffle

8th

dry coolers

9

fan

10

cooling element

11

cooling element

12

Steam distribution pipe

13

Condensate collection line

14

inflow

15

Fan race

K

Cooling air flow

Claims (5)

Air-cooled dry cooler for condensing water vapor, the inclined cooling elements ( 10 . 11 ) on the one hand to an upper steam distribution line ( 12 ) and on the other hand to a common condensate collector ( 13 ) have connected finned tubes, and which has at least one counterflow condenser (dephlegmator), the cooling elements ( 10 . 11 ) Are arranged in a V-shape and form adjacent legs of a triangle standing on top, in which the cooling elements ( 10 . 11 ) are arranged inclined at 45 ° to a horizontal, the inflow surfaces of the cooling elements ( 10 . 11 ) facing away from each other and the outflow surfaces of the cooling elements ( 10 . 11 ) facing the interior of the triangle, with at least two fans () in the region of an upper leg of the triangle ( 9 ) are provided, and wherein of the cooling elements ( 10 . 11 ) heated cooling air by the fans ( 9 ) can be extracted from inside the triangle. Dry cooler according to claim 1, characterized in that the at least two fans ( 9 ) between the steam distribution lines ( 12 ) is arranged. Dry cooling tower according to claim 1 or 2, characterized in that the cooling elements ( 10 . 11 ) Are arranged in a V-shape on the floor. Dry cooler according to claim 1 or 2, characterized in that the cooling elements ( 10 . 11 ) V-shaped in a steel frame ( 2 ) are arranged hanging. Dry cooling tower according to one of claims 1 to 4, characterized in that a first length section of the steam distribution line at the level of the lower tip of the triangle onto the cooling elements ( 10 . 11 ) and is further divided into a left branch and a right branch, each parallel to the long sides of the cooling elements ( 10 . 11 ) are arranged at an angle of 45 ° to the horizontal and in each case along the upper ends of the cooling elements ( 10 . 11 ) guided further sections of the steam distribution line ( 12 ) lead to.