Patent Application
20100276129
The present invention relates to a natural draft cooling tower with heat exchangers of the dry-type, operating by natural draft and achieving the exchange of heat between two fluids such as atmospheric air, ordinarily, and another fluid, generally water.
Indirect dry cooling plants are typically tower arrangements or formations having multiple towers, utlilized to dissipate heat from industrial plants using large machinery, such as steam turbines, or industrial processes. For example, one type of cooling tower used in these plants is a chimney-type natural draft cooling tower which has a thin veil of concrete forming the side wall thereof. The chimney is open at the top and is supported above the ground by a plurality of legs, and the space between the lower edge of the veil and the ground defines the cooling air inlet for the heat exchange tower.
In one design of a cooling tower, hot water from a condenser, is directed to the heat exchange units within the tower via a conduit, and the cooled water is directed back to the condenser via the conduit and a pump. As the name suggests, the condenser condenses and cools the exhaust exiting from a turbine and the cooled liquid is pumped to a boiler.
In one example, traditional dry-type heat exchange batteries have finned tubes mounted vertically in pairs and are erected on the ground and concentric to an opening. The batteries are typically V-shaped, so that the heat exchange surface creates a toothed polygon, the teeth of which are directed toward the inside of the tower.
A unit of traditional batteries of dry-type heat exchangers with finned tubes is placed horizontally or in slightly inclined fashion toward the bottom center of the tower, between the upper end of support columns and the upper end of the vertical batteries. The support columns are typically located in a single circular row near the opening inside the tower. Heat exchangers are mounted in pairs in V-shaped configurations, the peaks of which are directed upwards; each of the two units are connected by means of brackets. Because of the radial arrangement of the batteries situated above the air entry, an open space in the shape of a sector whose arc takes the shape of the periphery of the chimney exists between each pair of batteries. The spaces are typically sealed by plates to force the air to cross the batteries. The annular space between the wall and the extremity of the horizontal batteries is sealed off in analogous manner by plates. The same is done with triangular plates for the open space between the upper end of the vertical bottom and the inner end of the horizontal batteries.
Each exchanger unit usually includes two beds. Each unit can be fed with water to be cooled separately or otherwise by means of the heater boxes in which the ends of the tubes of the heat exchange units are connected. Some beds are directly exposed to the cooling air while other beds receive air already partially heated in passing through the first beds.
If the liquid to be cooled is to be circulated in series in each vertical battery and the horizontal battery to which it is affixed, and the cold air is first to meet the ascending current of hot water, the mounting described herein is carried out.
The hot water is typically brought to the tower via a conduit, and deposited in a circular part forming a hot water collector. The collector is provided with a circulation pump, the collector is arranged at right angles to the vertical batteries. Next to the collector, a second circular collector is usually installed and is connected to the conduit to evacuate the cooled water. The orifice of the lower water box of a bed of batteries is connected to the hot water collector; by means of a pipe, the orifice of the upper water box of a bed of batteries is connected to orifice of the water box which is most inside the tower of the bed of batteries. By means of a pipe, the orifice of the water box most inside the tower of a bed of batteries is connected to the orifice of the upper water box of the bed of batteries. By suppressing the internal partition of water boxes of batteries which are most outside the tower, the beds of each horizontal battery are placed into communication with each other. Orifice of lower water box of a bed is connected to the cold water collector.
Since water boxes of the batteries are common to both beds the water circulates automatically from the hot water entry towards the cold water evacuation piping using the beds successively, as soon as the siphon has been primed by a low output pump of greater manometric height than the circulation pump.
The equipment may also have piping that is small in diameter, connected to the highest point of each battery. The pipes evacuate the gas contained in the batteries at the time of the filling of the batteries and the introduction of the gas at the time of the emptying of the batteries. This gas is either atmospheric air, possibly dried, or an inert gas such as nitrogen and its pressure will generally be greater than atmospheric.
The aforementioned dry towers typically have wind screens, analogous to those provided in so-called wet towers, to control the strong winds prevailing in storms, and to minimize the disturbances in the distribution of the air inside the tower. The wind screens consist of flat, vertical walls which extend from the periphery of the tower to the extremities of the batteries, arranged in this case in a cross to divide the cooling system into quarters.
The horizontal batteries are supported directly by the vertical batteries themselves and by a single circular row of poles braced by beams. The latter may, moreover, be replaced by the chimney lintel itself, or by any type of framework. Two gangplanks typically allow for the passage of those persons responsible for surveillance and maintenance of the system.
With the increase of the output of steam turbines, the heat dissipating capacity of conventional indirect dry cooling plants has been required to increase accordingly. This demand has led to the use of extremely tall cooling deltas, up to 30 meters in cases, when a vertical cooling delta arrangement is applied. The cooling delta typically includes of a pair of heat exchanger bundles arranged in delta (i.e., Δ) form, with an apex angle of approximately 60 degrees. In the aforementioned delta arrangement, the two inclined sides are the two bundles, and the horizontal side is an airflow control louver assembly. The delta assembly is supplied with a self supporting prismatic steelwork.
Other solutions have been proposed to increase heat dissipating capacity, for example, a single-pass heat exchanger. However, it does not provide very good heat transfer capabilities. Another example is the use of a larger tube diameter, however, it has too high a pressure drop of the liquid being cooled as the air side pressure drop increases. For good heat transfer, a cross-counter flow pattern is preferred in the deltas, which can be implemented with two passes on the waterside. However, the water has to flow through a 60 meter length of tubes, which involves a high water side pressure loss.
Accordingly, there is a need and desire to provide an indirect dry cooling tower that has good heat transfer and a low pressure drop.
Embodiments of the present invention advantageously provide an indirect dry cooling tower that has good heat transfer and a low pressure drop.
An embodiment of the invention includes a heat exchange apparatus that extends vertically along a longitudinal axis, that cools a liquid, the apparatus including: a first delta positioned at a first point along the longitudinal axis, the first delta including: a first inlet conduit for inlet liquid flow, the first inlet conduit being in fluid communication with a first inlet main, and a first outlet conduit for outlet fluid flow, the first outlet conduit being in fluid communication with the first inlet conduit and a first outlet main, and a second delta positioned at a second point along the longitudinal axis above the first delta, the second delta including: a second inlet conduit for inlet liquid flow, the second inlet conduit being in fluid communication with a second inlet main, and a second outlet conduit for outlet fluid flow, the second outlet conduit being in fluid communication with the second inlet conduit and a second outlet main.
Another embodiment includes a method for cooling a fluid, the method including: passing a first portion of a fluid to be cooled through a first delta, and passing a second portion of the fluid to be cooled through a second delta above the first delta, and passing air over the first and second deltas.
Another embodiment includes an apparatus for cooling a liquid, the apparatus including: a means for passing a first portion of a fluid to be cooled through a means for a first delta, and a means for passing a second portion of the fluid to be cooled through a means for a second delta above the means for first delta, and a means for passing air over the means for first and second deltas.
Another embodiment includes a heat exchange apparatus that extends vertically along a longitudinal axis, that cools a liquid, the apparatus including: a first delta positioned at a first point along the longitudinal axis, the first delta including: a first inlet conduit for inlet liquid flow, the first inlet conduit being in fluid communication with an inlet main, and a first outlet conduit for outlet fluid flow, the first outlet conduit being in fluid communication with the first inlet conduit and an outlet main, a second delta positioned at a second point along the longitudinal axis above the first delta, the second delta including: a second inlet conduit for inlet liquid flow, the second inlet conduit being in fluid communication with the inlet main, and a second outlet conduit for outlet fluid flow, the second outlet conduit being in fluid communication with the second inlet conduit and the outlet main.
Another embodiment includes an indirect dry cooling tower for providing heat exchange to a fluid, the tower including: a delta tower, including: a first delta positioned at a first point along the longitudinal axis, the first delta including: a first inlet conduit for inlet liquid flow, the first inlet conduit being in fluid communication with a first inlet main, and a first outlet conduit for outlet fluid flow, the first outlet conduit being in fluid communication with the first inlet conduit and a first outlet main, and a second delta positioned at a second point along the longitudinal axis above the first delta, the second delta including: a second inlet conduit for inlet liquid flow, the second inlet conduit being in fluid communication with a second inlet main, and a second outlet conduit for outlet fluid flow, the second outlet conduit being in fluid communication with the second inlet conduit and a second outlet main.
There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
The above-mentioned and other features and advantages of this disclosure, and the manner of attaining them, will become more apparent and the disclosure itself will be better understood by reference to the following description of various embodiments of the disclosure taken in conjunction with the accompanying figures, wherein:
a is a schematic view of a cooling system in accordance with the present invention.
b illustrates the automatic control of the cooling water distribution between the bottom end top level
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof and show by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice them, and it is to be understood that other embodiments may be utilized, and that structural, logical, processing, and electrical changes may be made. It should be appreciated that any list of materials or arrangements of elements is for example purposes only and is by no means intended to be exhaustive. The progression of processing steps described is an example; however, the sequence of steps is not limited to that set forth herein and may be changed as is known in the art, with the exception of steps necessarily occurring in a certain order.
The invention will now be described with reference to the drawing figures in which like reference numerals refer to like parts throughout. Referring now to
Referring back to
With the above-described two-level arrangement, the effective tower height (the height which creates the draft in the tower) of the bottom level 102 differs from the effective tower height of the top level 103. For example, the higher effective tower height of the bottom level 102 functions to induce more draft and more airflow through the bottom level deltas. In the case of identical water flow in both levels, for example, the exit water temperature of the bottom level deltas 104 is typically cooler than that of the top level. Since the exit water from the bottom and top-level coolers may differ, thermodynamic issues can arise, as mixing water flows having different temperatures increases entropy, which indicates inefficiency of the process. Therefore, it is preferred that the exit water temperature of both levels be equal to achieve maximum process efficiency. Accordingly, in order to achieve similar or equal exiting water temperature, the cooling water flow through the top-level deltas 105 is controlled (throttled) relative to the CW flow in the bottom level deltas 104. Thus, embodiments of the invention include a throttling device for controlling the top-level water flow. The throttling device can be a butterfly or gate valve, a throttling orifice, or other appropriate throttling or control device. Such a throttling device is described in further detail below.
Turning now to
The control or throttling of the cooling water flow from the top level delta 204 can be implemented such that both the bottom and top levels 106, 107 of the tower 100 are equipped with outlet and inlet mains 201a, 201b, 202a, 202b. Accordingly, the bundles of the deltas, e.g., shortened deltas 104, 105, are connected to these mains 201a, 201b, 202a, 202b, and the throttling device 212 is built into the connecting conduit 211 between the outlet mains 201a, 202a. The throttling device 212 can be a butterfly or gate valve, a throttling orifice, or other appropriate throttling or control device.
Referring to
Large natural draft cooling towers similar to the above-discussed towers 100, 200 may be divided into four to twelve similar sectors that allow for easy and safe filling and draining operations. The individual natural draft cooling sectors can be filled, drained, and operated independently from each other.
A thermometer (not shown) or similar temperature gauge may provide a temperature reading that may assist in controlling the throttling device 212 in such a way that the exit temperature of liquid from the top level 105 should preferably be approximately equal with that of the exit temperature of liquid from the bottom level 104. The thermometer or temperature gauge may be installed into the bottom level outlet main 201a and another one into the top level outlet main 202a and connecting these thermometers to an electronic or other type control device.
As illustrated in
Turning now to
Turning now to
Turning now to
b, illustrates the automatic control of the cooling water distribution between the bottom end top level a cooling system, it may include a controller 921, a temperature measuring device 922 on the top level delta 924, a temperature measuring device 923 on the bottom level delta 925, the top level delta 924, the bottom level delta 925, a throttle valve 926, a sector return pipe on the top level 927, a sector forward pipe on the top level 928, a sector return pipe on the bottom level 929, a sector forward pipe on the bottom level 930, the tower return ring main 931, a tower forward ring main 932, a sector isolating valve in the return pipe 933 and a sector isolating valve 934 in the forward pipe.
Depicted in
The processes and devices in the above description and drawings illustrate examples of only some of the methods and devices that could be used and produced to achieve the objects, features, and advantages of embodiments described herein. Thus, they are not to be seen as limited by the foregoing description of the embodiments, but only limited by the appended claims. Any claim or feature may be combined with any other claim or feature within the scope of the invention.
The many features and advantages of the invention are apparent from the detailed specification, and, thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and, accordingly, all suitable modifications and equivalents may be resorted to that fall within the scope of the invention.
The present application is a nonprovisional application that claims priority to U.S. Provisional Patent Application Ser. No. 61/175,319, filed May 2, 2009, the disclosure of which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61175319 | May 2009 | US |
