The resent invention relates to the field of aix-coDled condensers, generally for use i n conjunction with a power plant; More particularly, the invention relates to wind guiding ane apparatus configured to improve operation of an air-cooled condenser,
Condensers are used in power plants to condense the motive fluid exhausted from turbines. They are also used in ref igeration plants to condense refrigeration vapors such as ammonia or fluoridate hydrocarbons, and in the petroleu and chemical industries such .as for use in a fuel distillation apparatus to condense a variety of chemical vapors.
Air-cooled condensers (ACCs) are used in those geographical: regions where cooling water for reducing the temperature of heat depleted vapor is scarce. In. ACCs, heat is rejected ixom the hot fluid that flows through the tubes to the aaahient- air by passive or forced air flow, generally in counterftow by means of a fan, on the external side of the; heat exchanger tubes. Axial fans often having a diameter of greater than 10 ft , e.g. 26 36 it are often installed above the ACC tube bundles: to induce air across the bundles. In additio to the plentiful nature of air serving; as the condensing medium, an additional advantage of an A0O is that air will not freeze as opposed to water. The inherently low heat transfer coefficient is compensated for fey high fin areas.
The thermal pprfbrmanee of ACCs during windy h hάb, howeve , is reduce due to cross winds, as a result of a decreased flow of air through the fans, esusing in turn a decreased cooling capacity. In addition. ACC performance can also h@ degraded due fco the recirculation of warm outlet air that is mixed with ambient air, resulting in increase air inlet temperature and in increased turbine hack pressure.
One prior art method to reduce the influence of cross winds an of airreeireuiation involves the use of porous wind screens. These wind screens are expensive to manufacture and install, and usually involve a reduction in static pressure underneath the AGO structure.
Another method involves positioning the AGO so that the long edge of the AGO structure is parallel to the prevailing wind direction. However gydh ACC positioning is often infeasible due to topographical constraiiits.
IIS 9,587,842, t¾59, 651,269 and 089,689.680, the disclosure: of which are incorporated: by reference, disclose wind guiding vanes or deflect ©rs that are mminted fo rotation about a vertical axis, so that their pivot angle or height is changeable in response to sensor readings. The need for controlling displacement of the wind guiding vanes or deflectors unduly adds costs to the system,
It is an object of the present: invention to provide stationary win guiding vane apparatus for increasing the thermal perf rmance of AOCs during· windy perio s.
Other objects and advantages of the invention will become apparent as the description proceeds.
The present inyentibft provides wind guiding va&@· apparatus for mitigating a detrimental influence of cross winds So ing in the vicinity of an .aircooled condenser (ACC) and through one or more fans, positioned in lateral direction of the ACC, to which ambient air is directed an discharged to the atmosphere after cooling condenser tubes q£ said AGO, comprising one or momstationary wind guiding vanes positioned along at least a portion of an air flow streamline and below a. -plurality of condenser tubes of said ACC, wherein said one or more wind guiding vanes are configured to redirect .air flow during winfty conditions towards a portion of said plurality of condenser tubes an at least one of said fans at such an angle that sxgnifieantly deviates from perpendicular, fairly horizontal inflow,
The one or ore wind guidhig vanes are also suitable to maintain a nominal flow rate of air during quiescent wind con itions Brief Description o
in the drawings;
Fig. 1 is a perspective view from the top of an ACC;
Fig. £ is: ¾ perspective view item one longitudinal end of W d guiding vane apparatus, aeeordiug to one embodiment of the present invention;
Fig. 8 is a side view from one longitudinal end of wind guiding vane apparatus, according to one embodiment of the present invention, showing air flow during quiescent conditions;
Fig. 4 is a side view from one longitudinal end of the apparatus of Mgv S, showing air flow during windy conditions;
Fig, 5 is a side view from one longitudinal end of wind guiding vane apparatus, according to another emhodinient of the present invention, showing- air flow during windy conditions;
Fig, 0 Schematically illustrates the generation of induced air flow streamlines during quiescent conditions; and
Fig, 7 schematically illustrates the generation of forced air flow streamlines during: quiescent conditions.
Detailed Descnripilnn
Some geothermal rea wees a d /fluids desired to be. exploited have swob a low energy OBtetit, for example extracted at a te per atee of 260-28 *1^ that a power lant utilfeing a motive fluid, to which heat is transferred from the geotliepnai resou ce, is economically viable particularly when the turbine discharge is condense ci by an air-cooled eoadeneer (ACC), As described above the thermal efficiency of an ACC is dependent upon the performance of the AOO fans through which ambient air is directed anil discharged to the atmosphere, after cooling the motive fluid present in the- Condenser tubes.
Dining wit4y conditions, however, according to oae explanatioxi, perpendicular inflo to the ACC causes the dynamic pressure below the AOO to increase, and the static pressure which: is reflective of resistance to .airflow decreases. The differential static pressure between the inlet and outlet of the ACC fans mereases» and the mean velocity of air exiting the ACC fans is consequently caused to. decrease, and at times can ovea decrease to stalled conditions, resulting in a decrease cooling capacity and a. reduced effective heat exchange area used due to -a .reduced flow rate of air across the condenser tubes. Under such conditions, the AGO fans find it difficult to. perform at nominal conditions and their air intake drops. As aoonsequenee of this, the: air velocity under the upstream portion of the AO€ structure is low so that the performance, he.· the oritiet air flow rate of the upstream fan, as well as, to seme extent, the second upstream fan·, is reduced. Use of the win guiding vanes, described herein, positioned, ift accordance with the present i mntion, beneath the A0G structure and advantageously, under the first upstream fan, causes a lesser reduction in the performance of the first two upstream i¾nS The economic viability of an ACO-based power plant is therefore dependent: upon the reliable reduction of the influence of cross winds or winds having a component in the cross wind direction, so that cooling air will reliably flow across the condenser tubes prior to being discharged through an AQC fan even during windy conditions.
The apparates Mfihe present invention is advantageously able f;o mitigate the detrimental infih&nde of cross win s by carefully positioning one or more stationary wind guiding vanes along at least a portion of an air flow streamline, below the AGO sb cttt . The windy air flow, a ter contacting the win guiding vanes, is redirected towards the condenser tubes and fans at; such. an. angle that significantly deviates from the perpeBdieidar, fahiy horizontal inflow. The wind guiding vanes are also suitable to aintain a nominal Sow rate during quiescent wind conditions.
The actual location of the; wind guiding vanes along the streamlines, as well as their size and orientati/ . havn been defcermixied with use of co putational fluid dynamics (CFD) analysis, based on a numerical N iem&okes equation solution to model the general air Ho in and around the ACC structure, together with shear stress transport ($ST) turbulence odel to evaluate the turbulent flow in the boundary layer of air wit hin the AC 0 structure,, ne ar the wind guiding vanes, finned tubes sad ACC fans.
Sefafemse is first made to Fig. X, which schematically illustrates an AGO designated ACC 2, typically located outdoors. AGO 2 com rises condenser tube section -4, each of which may be· finned, and a plurality of fens 8, Usually three fans are used, while sometimes two Or even mo fans, located in the lateral or widt direction W of AC€ 2 can he used. he spaced tubes through which motive, fluid to be condensed flows are arranged so that cooling air can flow over the tubes anddissipate the thermal energy of the motive fluid flowing i herein. AGO 2 is; generally arranged as a rectangular array with a length L, width W and height H. AC.0 2 is
typically installed above the level of ground at a distance FH from the ground to allow free flow of air underneath the ACC. In order to increase the rate of heat diesipation, fans 6 are installed above tube section 4 to : induce the flow of air from the area beneath AGO 2 up through tube- section 4. In addition, such an arran ement reduces to a large extent the possible recirculation of air exiting the- fans being drawn into the inlet flow of air under AOC %.
The efficiency of heat dissipation of AOC 2 depends on various ambient conditions, such as the amount of exposure to direct sun light, the ambient temperature and the actual wind conditions (direction and magnitude) a t the given loeatioa of ACC For large ACCs with a high aspect ratio (L/W) figure, wind blowing parallel to its length di ension has a negligible effect. In contrast, wind blowing parallel to its Width dimension has a sub tantial effect due to the perpendicular inflow.
Fig- 2 illustrates wind guiding vane apparatus 1(1, according· to one embodiment of the present invention. Wind guiding vane: apparatus 10 comprises two vertically apaeed elongated and stationary wind guiding vanes 2:2 and 28 that are fixed in place, below one lateral end 11 of the schematically illustrate AGC 14, i.e. the condenser tube section for condensing the motive fluid, such as organic motive fluid, present in the finned tubes- The wind guiding vanes are preferably straight to reduce their cost by virtue of the relative ease in manufacturing·, but curved wind guiding vanes are also ih the scope of the invention. wind guiding vanes 8 and 23 are generally inclined with respect to horisontal support elements 18 in the vicinity of lateral end 11,. such that the downstream edge 17 of each wind
guidin vane is located at a greater height than the: coianspondrng upstrea edge 16 thereof to ensure that wind -derived ait flow will fee redirected thereby towards the condenser tubes and fans at an angle that significantly deviates from per eftdioHla fairly horizontal inflow:. The wind guiding vanes ate sufficiently sturdy to withstand the relatively high ferees associated with the kinetic ener y in high-velocity wind, an are made for example: from stainless steel to resist corrosio when exposed to precipitation.
The upstream edge 16 of Upper wind guiding vane 22 may bo co moted to three spaoed columns ISA-lfiO, spaced in the longitudinal direction, adapted to support the underside of AGO 14, The downstream edge 17 of upper wind guiding· vane 2 may be connected to brace wind guiding vane support structure 27A-27G, The downstream edge 17 of lo er wind guiding vane 23 may be connected to each brace 18A-18G extending upwardly from the bottom of a corresponding column 15A lfiC to a top reg on of a corresponding intermediate column 27A-2? C The upstream edge 16 of lower wind guiding vane 23 may bo connected to an additional support structure fir example one connected to u per wind guiding vane 22,
In this fashion, the support structures sufficiently itnmobilise wind guiding vanes 22 and 23 without appreciably interfering with the wind-derived air flow in the vicinity of the win guiding vanes
A1 though ACC 14 is shown to be configured as a rectangular array, it will be appreciated that the AGO may be configured in other ways as well.
Figs..3 and 4 schematically illustrate the utility of the· win guiding va es to adequa tely irect an air flow to the condenser tubes and to the ACC Ians during both quiescent conditions and windy conditions. As referred to herein, windy conditions are considered to |>e those environmental conditions that induce the speed of winds to be greater th n 5 is, for example between 6-10 m/s. Such windy conditions may occur on.. seasonal basis, such as during continued periods in the summer season, or even during a shortened period, such as one hour or a period of six hours. Even so, the wind guiding v nes described herein also bring about an improvement of performance of thu first two fens o en when winds of about 8 mis prevail.
The vertical cross section of wind guiding· vane apparatus 10 illustrates a unit of three; laterally or width spaced fans 20A-C, each of which surrounded by a corresponding shroud 2 Ά-270, Fans AO, usually of the axial type but which may be configured in other ways as well, are .su ported by fan deck 23 located above ACC 14, m as to he in fluid co unication ith a corresponding region oi’AOC 14 in order to itduce the flow of air across the condenser tubes. Alternatively, a ibrced- draft arrangement can also he used.
Vertically spaced wind guiding-vanes 22 and 23 are positioned below AOC 14, and are inclined with respect to,· and located above, miderlying groun surface 10. The inclination of wind guiding vanes 22 an 23 is arranged such that the r ownstrea edge 17 is inclined upwards towards the direction of second lateral end 12 of ACC 14 arid a ay fro first lateral end 11 thereof Wind guiding vanes 22 and 23 may he connected to a support structure as· illustrated in Fig. 2, or ma
be connected in other ways to wind guiding vane apparatus? 10 ind guiding vanes % and 23 ma be positione directly below the first upstream fan 26A,,¾o achieve more direct, cdntrel of the wind-derived air flow towards the condenser tubes and AGO fans.
Apparatus 10 is shown to include in one embodiment a diffuser 34 for receiving organic motive fluid vapor from the outlet of an organic vapor turbine and su plying it fco· the internal volume of the condenser tubes of ACC 14. Apparatus 10 also comprises collector 29 for collecting liquid organic motive fluid condensate produeed fey ACC 14, to supply the same by a steady and continuous flow to the inlet of the cycle pump.
Fig, 8 illustrates the air flow during quiescent conditions to fane S^A-ghC, and Fig; 4 illustrates the air flow during windy conditions ans 26A-26B are considered as upstream fans as their operation is affected by the wind guiding vane-influertced! wind-derived air flow, wh le iaa 260 is considered as a downstream fan as its operation is to a large extent t affeeied by the wind guiding vane-influeiieed, wind-derived air Sow,
It. will be appreciated that wind guiding vane apparatus 10 ay comprise additional fans, longitudinally and/or laterally or width spaced fro the fhn unit of fans 26A-20C, e,g. 2 laterally a jacent ACC structures, and in fluid communication with a corresponding region of ACC 14·, whether by repeating the sequence of fans 2(14-260 or· by roviding any otter desired sequence, depending on the amount of heat to he dissipated. The. number of fan units, present in the
longitudinal direction h of ACC 2 fees Fig. I), may vary from e.g, 7-8 to 20-24, depen ing also on the type of motive fluid used.
As. shown in. Fig. 8. air flow 31 dinti g quiescent wind conditions is equals rawn into each of the m 28Ά.-260, an from. all directions. Wind guiding vanes 2 and 23 do not disturb air flow 31 as far as operation of ACC 14 is concerned, while flowing across the condenser tubes towards fans 26A-26C, because the wind guiding yanes· are positioned on the streamlines of air flow 31. Oonshf iiently. the nominal power of the fans is maintained under quiescent conditions et® with the presence of wind guiding vanes 22 and 23,
As. shown in Fig 4, wind guiding vaites- 22 and 28 remain physically located below the first upstream fan. A» being in the same position during windy conditions as during quiescent wind conditions. Although wind dd ng vanes 22 and 28 do sot disturb the .air flow during quiescent wind co ditions, they cause redirection of the air flow uring windy conditions when the wind-derived air flo 83 blows .in- the direction shew in Fig. 4 Following interaction with wind guiding vanes 22 and M. the direction of ind-derived air flow 3.3 is caused to change, being directed to a speciflc: region .of condenser ubes and to a sp.e fe flag at an angfe that significantly .deviates from virtually !xoiisontai inflow. Upper wind guiding vane 22 is configured to direct the air flow to the fleet upstream fan 26A, while lower wind guiding vane 2-8 influences to a greater extent the air flow to the second upstream fan 26B,
The deflection of air flow 38 provided by each of. wind guiding vanes 22 and 28 is a function of the wind guiding vane inclination relative to underlying
ground surface 10, the horizontal and vertical distance to an outer edge of the portion of th# coiu!ensef tubes to be cooled by the -redirected airflow, oad the length and wid th: of the wind guiding van©.
As to downstream fail 2SC, its operation has. been fepid to bp virtually imafiected by the residual air flow flowing downstream to wind uiding vanes: 22 and 28, insignificant disturbance apparently remaining in this residual air flaw following the influence of wind guiding vanes 22 and 28 Consequently, a third ind guidin vane to redirect the air flow to downstream fan 260 is unnecessary · Thus, ap aratus 10 achieves a cost-effective solution since only two wind guiding vanes are nee ed for a unit of three fans, although three, or any other nu ber of wind guiding vanes, may also ho employed.
Fig. S illustrates: wind guiding vane apparatus 40 for use in conjunction with environmental conditions that are characteristic of wind direction shife, which can sometimes be sudden, such as winds that change direction with respect to a Median direction to produce air flow 47 oppositely directed to air flow 88,
Apparatus 40 is identical to app aratus 10 of Fig, 4, font with the addition of wind guiding vanes 42 and 43 positioned directly beneath .fan 26C, wind guiding vanes 42 nd 43 M y be connected to: a support structure as ilktsfrated in Fig. 2, of may he connected in ether ways to wind guiding vaiie apparatus 40, The inclination of wind guiding vanes 42 and 43 is arranged such that their downstream edge 17 is pointing in the direction of first longitudinal end 11 of ACC 14 and away from secon longitudinal end 12 thereof. In this fashion, apparatus 40 is capable of suitably redirecting air flow 33 toward fans 26A-26B, au
* fbilowiug
a wind shift, of suitably redirecting air flow 47 toward fans 2i3B-26C, to further increase: the thermal performance of a power plant provided with apparatus 40.
Fig, 0 illustrates the- positioning of curve wind guiding vanes 51-55 that are need to redirect the- air how SB during windy conditions towards %n shrou s
2fA and 27B of wind guiding wane apparatus §0* which are mounted above AGO
14 to produce an induced flow·. Each of wind guiding vanes 51~>55 is mounted one below the other, below first lateral end 11 of ACC 14, such that the projected hnriw tal
.dimension b · and the distance e from the wind guiding vane to the bottom plane of AA 14 of each wind guMin vane progressively increases
up er ost wind uiding vane Si to the lower ost wind guiding vane 55, Dimension a is t¾e .projected vertical dimension of each wind guiding vane, dimension d is theho onfal distance of the wind guiding vane from the upstream edge of ACC 14; and H refers to the radius of each wind guiding vane.
Each of wind guiding vanes 51-55 is shown to coincide with a different streamline 58 that produced as a result of the inter action of air flow SB with a corresponding wind guiding vane. Wind guiding vanes §1-58 redirect air flow S3 towards the fan mounted within shroud 2-7A, and wind guiding vanes 54-55 redirect air flow1 33 towards the fan ounted within shroud 27B.
Example 2
Fig- 7 illustrates the positioning of curved ®id gui ing vanes 61-65 that are used to redirect the air flo 33 during windy conditions towards fan shrouds 67 A and 67B of wind guiding vane ap aratus 60., which are mounted below ACC 14. to produce a forced flow, E ach of wind guiding vanes 61-65 is mounted one below the other·, below first lateral nd 11 of ACC 1;4, such that the projected horizontal dimension b and the distance ø from the wind guiding vane· to the bottom plane of AA 14 of each wind guiding vane progressively increases fro the uppermost wind guiding vane 61 to the lowermost wind guiding vane 65. Di ension a. is the projected vertical dimension of each wind guiding Vane, dihiOhsion cl is the·- horizontal distance of the wind guiding vane fmm the upstream edge of AGO 14, and B refers to the: radius of each wind guiding vane .
Each of wind guiding vanes 61 -65 is shown ip ooincitle with a different streamline 68 that is produce as a result of the inter action of air flow' 83 with a corresponding wind guiding vane. Wind guiding vanes 61-63 redirect air flow 33 towards the fan mounted within shroud 67 A, and wind guiding vanes 64-65 redirect air flow 33 towards the fare mo noted within shroud 67B.
A determmatiou of the streamlines along at least a portion of which the wind guiding vanes of the present invention are positioned was based cm a mimerieal GFD analysis together with SET tu bulence model, inputting the wind conditions measured at the Don Campbell geothermal power plant located in
Nevada, tTSA. A 26- iUioh mesh was used to o ver the ACC structure and its adjacent air Sow. The size, number and location ¾ the w d guiding vanes were designed fay use of the CPB analysis, physically tested at the Don Campbell geotherm l power plant, and reconfirmed fey use of : the CFO analysis.
The analysed ACC structure was a hay having a length of 60 ft and a width of 26 It, and containing three lube bundles of finned eo tensey tubes. The t ree fans used in the ACC bay all had a diameter of 16 ft.
The air flow streamlines were calculated according to· different ind speeds and predicted the decrease in air flow rate at the exit of the ACXXians during windy conditions. These predie ohs were verified by actualsmoke tests at the Go» Campbell geothermal power plant;.
Furtheinnore. 2 wind guiding vanes physi lly locate under the first fan of the ACC at the Don Campbell geothermal power plant in Nevada , U. S, A.* were found to improve the petforrnance. of the lat 2 upstream ACC fans, their performance and air flow rate at their exit being also checked by actual smoke tests and velocity measurements at the Don Campbell geothermal power plant and verified as well by the predicted numerical O D analysis together with SST analysis performed for such wind conditions.
While some embodiments of the invention have been described by way of illustration by referring to the drawings, it ill be apparent that the invention can be carried out with many modifications, variations and adaptations, and with the use of numerous equivalents· or alternative solutions; that are wi h!» the scope of
16
without e rting froxft the spirit of the invention ox sscee& g the scope of the claims.