CONDENSER WHICH IS EXPOSED TO AIR
The invention relates to a condenser (1) which is exposed to air, having a ventilator (2) which conveys cooling air, is arranged in particular below condensation elements (4, 5) arranged in an A-shape, and presses intake cooling air into the triangular interior space (6) which is delimited by the ventilator (2) and the condensation elements (4, 5). Also provided are means for adiabatic cooling of the cooling air, wherein the means for adiabatic cooling are contact bodies (7) which can be placed in contact with water to be evaporated and which are arranged in the region of the cooling air flow (3).
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The invention relates to a condenser which is exposed to air having the features as set out in the generic clause of patent claim 1.
It is known that by pre-moistening the cooling air, i.e. so-called adiabatic cooling, the cooling performance of air-cooled condensers can be increased substantially, in particular during operation in summer. Particularly in the case of relatively large plants in the power plant sector it was not possible to date to find a practical and reliable solution of this problem as H B Goldschagg describes in “Lessons learned from the world's largest forced draft direct air cooled condenser”, EPRI Conference, Washington D.C., 01-Mar. 3, 1993. On the other hand, there is an increasing demand for functional and efficient pre-moistening means by operators of such plants.
The fundamental drawback of known adiabatic cooling systems is soaking of the cooling elements, support structures and other structural plant components arranged below the cooling elements. Soaking of the cooling elements, in the long term, results in an undesirable deposit of insoluble substances, while electric components such as e.g. transformers must be protected entirely against the entry of moisture in order to avoid short circuits. Exact dosing of the water as well as its distribution can only be calculated with difficulty, since the distribution of the water droplets depends, inter alia, on the wind direction and the temperature distribution. Uneven distribution results inevitably in localised soaking and, consequently, also in drop formation, i.e. the water drips down along the condensers and the support structure. This may result in undesirable corrosion, even if demineralised water is used.
Proceeding on this basis, it is the object of the invention to so improve a condenser exposed to air that the condensing elements are not soaked by the means provided for adiabatic cooling of the cooling air, the said means for adiabatic cooling also being able to be retrofitted with little effort.
This object is attained by a condenser exposed to air having the features of patent claim 1.
The essence of the invention is that the means for adiabatic cooling are contact bodies to which water to be evaporated is to be fed and which are arranged in the region of the cooling air flow, that is to say on the flow-impacted side of the condensing elements. The contact bodies possess a large surface area, on which water fed into the contact bodies may evaporate. The water is at no point in time kept freely within the cooling air flow, as is the case when spraying with nozzles. In contrast to atomising or spraying, virtually no excess water is required since the water taken up by the contact bodies is transferred to the cooling air flow by mass transfer, i.e. evaporation, alone. This further ensures that damage caused by corrosion due to undesirable moisture on components in the vicinity, such as e.g. the ventilator, is avoided.
A substantial increase in performance at moderately increased investment costs is expected from the condenser exposed to air, designed according to the invention. New plants to be set up may be built smaller in size, even with a predetermined output, if adiabatic cooling, using contact bodies, is provided. As a result, the production costs of new plants can most probably be reduced. It is a further advantage that output deficits, e.g. necessitated by hot air recirculation, may be reduced and that, on the other hand, the output of a power plant may be increased at the same time by several 10 kPA by reducing the turbine waste steam pressure.
Advantageous embodiments of the inventive concept form the subject of the subsidiary claims.
The condenser exposed to air according to the invention is preferably provided for the condensation of water vapour. In particular, condensers are provided for condensing the waste steam flow from a turbine of a power plant. In principle, it is, however, also conceivable to provide the condensers exposed to air for condensing other substances, such as, for example, for condensing propane. The inventive concept is not limited to condensing water vapour. The condenser exposed to air, according to the invention, is likewise also not limited to a specific type of condenser. In principle, the contact bodies to which water to be evaporated is to be fed, may be used in combination with condensation elements arranged in an A-shape, V-shape, vertically or horizontally. The use of these contact bodies in conjunction with condensation elements arranged in an A-shape or in a roof-like fashion is considered to be particularly advantageous.
With regard to the arrangement of the contact bodies in the region of the cooling air flow, various modifications are possible. In a first embodiment, the contact body may be arranged in the intake region of the ventilator upstream of the condensation elements, i.e. it is present in the flow direction upstream of the ventilator. The air pre-moistened in this manner flows through the ventilator, subsequently entering e.g. into the triangular interior between condensation elements arranged in an A-shape. Contact bodies may, for example, be mounted in conjunction with a protective screen fitted upstream of the ventilators.
In a second modification, contact bodies may also be arranged in the exit region of the cooling air flow of the ventilator, i.e. in the direction of the cooling air flow downstream of the ventilator.
In principle, it is also conceivable to use the means for adiabatic cooling at a location where cooling air is not pressed through the condensation elements, but is sucked in. In this case, the ventilator is fitted downstream of the condensation element, which has no effect on the efficiency of adiabatic cooling.
A further modification provides that contact bodies are arranged immediately upstream of the condensation elements, covering at least a portion of the flow-impacted surface of the condensation elements. The contact bodies may in this case cover the entire flow-impacted surface of the condensation elements or even only part of the surface. It is conceivable that e.g. only some of the condensation elements are provided with contact bodies while others are not. Partial covering of the condensation elements may e.g. take place in the upper, central or lower third thereof. The respective degree of covering and the exact positioning of the contact bodies must depend on the local circumstances. No rigid rule can be mentioned here.
It is considered to be particularly advantageous if the degree of covering the flow-impacted surface can be adjusted by repositioning the contact bodies. In the event that the contact bodies are deactivated, i.e. that no pre-moistening of the cooling air is desired, the said contact bodies may e.g. be swivelled and lifted from the cooling air flow in a certain manner, so that a larger flow-impacted surface of the condensation elements becomes available for pure dry cooling. Swivelling has furthermore the advantage that no additional loss of pressure, caused by the contact bodies, arises.
The axis about which the contact bodies are swivelled depends on the spatial circumstances. For example, in the case of condensation elements arranged in an A-shape, the swivelling axis may extend in the ridge region, i.e. substantially horizontally, but at least parallel to the planes spanned by the condensation elements. It is also conceivable for the swivelling axis not to extend horizontally, but parallel to the planes spanned by the condensation elements, i.e. according to the inclination of the condensation elements in the case of condensation elements arranged in an A-shape. If spatial circumstances permit, the contact bodies may also be arranged in a manner to be translationally displaceable.
It is considered to be particularly advantageous if contact bodies are fixed directly to the condensation elements on their sides facing the ventilator. The contact bodies may e.g. be fixed to the end faces of tubes of the condensation elements, the said tubes being provided with fins on the transverse sides. Fixing of contact bodies directly to the condensation elements results only in a negligible increase of the flow resistance, so that no pressure losses whatsoever occur. The contact bodies are nevertheless situated entirely within the cooling air flow. As with the arrangement of contact bodies in the direction of flow upstream of the condensation elements, it is possible to provide contact bodies fixed directly to the condensation elements in some regions only. For example, each second tube of the condensation elements might be provided with contact bodies.
The contact bodies are preferably represented by a non-woven fabric, a woven fabric or porous plastics. The essential properties, which appropriate contact bodies exhibit, are a high storage capacity for water and a large surface area to permit rapid evaporation of the water. In addition, the material employed—depending on the disposition within the cooling air flow—should be adequately air permeable in order to limit pressure losses. Self-supporting materials are considered to be particularly advantageous, while composite multi-layered materials, wherein one layer of the contact body fulfils the support function while at least one other layer is designed especially for water absorption and high evaporation, may be employed as well. Commonly available and reasonably priced materials are geo-textiles or non-woven fabrics offering the desired absorbency and good water evaporation ability. The said materials are highly ageing resistant and are furthermore adequately mechanically resistant. The contact bodies can preferably be cleaned after a predetermined period of use and can subsequently be re-used. If possible, the contact body should, therefore, not decompose under the influence of air and water. By appropriately choosing the material, both high mechanical load-bearing capacity and, at the same time, a correspondingly desired water absorption capability may be attained. Both are prerequisites for the use within the cooling air flow in air-cooled condensers. The contact bodies preferably take the form of plane panels. It is, of course, possible that single-layered or multi-layered contact bodies deviate from plane panels with regard to their geometry, i.e. that they are, for example, corrugated or that their profile is adapted to the flow conditions of the air-cooled condenser or that they are provided to specifically influence the flow conditions by their positioning and contouring. This means that the contact bodies, depending on their positioning and contouring, may also possess a certain conducting or deflecting function in relation to the cooling air flow.
It is important for the condenser according to the invention that the amount of the water to be introduced into the contact bodies is so selected that no substantial excess occurs which would result in soaking the plant. For this reason, a metering system controlling the volume of the water to be introduced into the contact bodies is provided, which systematically feeds the exact amount of water to the contact body which needs to be fed under the given climatic conditions and operating states of the plant in order to ensure maximum evaporation in the region of the contact bodies. This system may in the present case be a control circuit or even a regulating circuit equipped with appropriate measuring devices. The measuring devices detect whether water is present at determined measuring points outside the contact bodies from which may be concluded that too much water for evaporation was fed to the contact bodies.
In order to improve the water distribution inside the contact bodies, provision is made for a metering line to extend adjacent to a contact body, having a plurality of apertures, through which the water to evaporate can be fed into the contact body. In the present case, this may be a rigid or flexible line, extending in the peripheral region of the contact bodies. By utilising gravity, such a metering line can introduce water into a contact body, for example from above. The water flows down inside the contact body, wets its surface and evaporates within the cooling air flow. The amount of water is metered in such a way that on its way through the contact body it only just reaches the lower end, partially already evaporating on its way there. It is also conceivable for the metering lines to be arranged on the surface of the contact body facing the cooling air flow or facing away from it. As a result, the paths to be covered by the water inside a panel-shaped contact body are shorter, ensuring a more uniform distribution of the cooling water, which also simplifies metering. In this context, it is considered to be particularly advantageous if the metering line is embedded in the contact body. This may be realised, for example, by a metering line installed in a meandering fashion, positioned, for example, between two contact bodies in the form of a non-woven fabric. Both contact bodies are wetted equally with water by the metering line. This minimises the risk of water emerging from the non-woven fabric in an uncontrolled manner.
It is furthermore considered to be advantageous if the water to be evaporated is pre-heated in the metering lines, i.e. by heat transfer from the condensation elements to the metering lines. For this purpose, the metering lines may extend between the end faces of the condensation elements and the contact bodies fixed to the end faces. The water so pre-heated withdraws to a small extent heat from the condensation elements, thus evaporating more rapidly in the region of the contact bodies. This increases the efficiency of a condenser which is exposed to air in this manner.
The invention is elucidated in what follows by way of the embodiments shown in the schematic drawings. There is shown in:
In the embodiment according to
A third embodiment is shown in
The embodiment according to
In all aforegoing figures the illustration of one or more metering lines for feeding the contact bodies with water has been omitted.
In contrast thereto, the metering line 15 in the embodiment according to
It is also conceivable to embed the metering line between two contact bodies, the water to be evaporated being released on both sides of the metering lines.LIST OF REFERENCE NUMERALS
- 3—Cooling air
- 4—Condensation element
- 5—Condensation element
- 7—Contact body
- 7a—Contact body
- 7b—Contact body
- 7c—Contact body
- 7d—Contact body
- 7e—Contact body
- 8—Intake region
- 9—Outlet region
- 10—Flow-impacted surface
- 12—Transverse side
- 14—End face of 11
- 15—Metering line
- A—Position of 7b
- B—Position of 7b
19. An air-operated condenser, comprising:
- a condensation element,
- a ventilator for generating a cooling air flow in a region of the condensation element, and
- an evaporative element for adiabatic cooling of the cooling air flow, said evaporative element located in a region of the cooling air flow and receiving a quantity of water to be evaporated.
20. The condenser of claim 19, wherein the condensation element is configured to condense water vapor.
21. The condenser of claim 19, wherein the ventilator is installed upstream of the condensation element in a flow direction of the cooling air flow, the evaporative element being arranged in an intake region of the ventilator.
22. The condenser of claims 19, wherein the ventilator is installed upstream of the condensation element in a flow direction of the cooling air flow, the evaporative element being arranged in an outlet region of the ventilator.
23. The condenser of claim 19, wherein the ventilator is installed downstream of the condensation element in a flow direction of the cooling air flow.
24. The condenser of claim 22, wherein the evaporative element is arranged proximate to the condensation element and covers at least part of a surface of the condensation element exposed to the cooling air flow.
25. The condenser of claim 24, wherein an area of the surface of the condensation element covered by the evaporative element is adjustable by repositioning the evaporative element.
26. The condenser of claim 22, wherein the evaporative element is rotatable in the cooling air flow.
27. The condenser of claim 24, wherein evaporative element is affixed directly to the condensation element.
28. The condenser of claim 27, wherein the condensation element comprises tubes with end faces and fins, wherein the evaporative element is attached to the end faces of the tubes.
29. The condenser of claim 19, wherein the evaporative element comprises a non-woven fabric.
30. The condenser of claim. 19, wherein the evaporative element comprises a porous synthetic material.
31. The condenser of claim 19, further comprising a metering system for controlling the quantity of water received by the evaporative element.
32. The condenser of claim 31, wherein the quantity of water received by the evaporative element does not exceed a quantity amount of water evaporated from the evaporative element.
33. The condenser of claim 31, wherein the metering system comprises a metering line disposed proximate to the evaporative element and having apertures for supplying the quantity of water to the evaporative element.
34. The condenser of claim 31, wherein the metering system comprises a metering line embedded in the evaporative element and having apertures for supplying the quantity of water to the evaporative element.
35. The condenser of claim 33, wherein the quantity of water to be evaporated is pre-heated in the metering line by heat transfer from the condensation element to the metering line.
36. The condenser of claim 34, wherein the quantity of water to be evaporated is pre-heated in the metering line by heat transfer from the condensation element to the metering line.
37. The condenser of claim 28, wherein the metering line extends between an end face of the condensation element and the evaporative element attached to the end face.
International Classification: F28D 5/00 (20060101);