Lifting system for solar power tower components

ES 2 379 522 B2

DESCRIPTION

LIFTING ASSEMBLY AND METHOD FOR MOVING COMPONENTS TOWARDS

UP AND DOWN FOR A SOLAR POWER TOWER

The present invention relates generally to a lifting assembly and a method for moving components up and down for a solar power tower. More particularly, the present invention relates to a lifting assembly for a solar power tower having an elevated central receiver.

BACKGROUND

All over the world there is a growing demand for energy. Due to the scarcity of resources and adverse environmental effects, alternatives to fuels based on petroleum and coal are becoming increasingly popular. As technology advances, the use of clean renewable energy sources to replace, or at least increase, conventional power plants is becoming feasible.

Solar power plants have proven to be effective and have become the subject of global attention. In a typical arrangement, a centralized tower is located within a heliostat field. Heliostats are tracking mirrors, reflecting sunlight to a solar receiver located at the top of the tower. Inside the receiver, absorbed sunlight heats a fluid to elevated temperatures, thereby converting solar energy into thermal energy. The fluid containing the thermal energy is then sent down the tower to be stored or converted into electrical energy for use.

The solar receiver is often placed atop the central tower to increase the field of view so that many heliostats can focus sunlight on the receiver. Tall central towers with solar receivers located 76.2 meters (250 feet) or more above the ground can harness a large amount of solar energy. Although they are desired

ES 2 379 522 B2 tall towers with elevated center receivers, improvements in technology are needed to increase efficiency and reduce construction cost.

DESCRIPTION

An object of the present invention is a lifting assembly for a solar power tower. The solar power tower has a top and a base. A track runs longitudinally along a span of the tower between the top and the base. A cable is anchored to the top of the tower and extends toward the base of the tower adjacent to the runway. One component is mounted on the track and connected to the cable. A winch is attached to the top of the tower and is anchored to the cable. The winch winds or unwinds the cable to guide the component along the track.

Another object of the present invention is a method for moving components up and down a solar power tower. The method includes coupling a component to a cart mounted on a track that extends longitudinally along the solar power tower and winding or unwinding a cable having a first end connected to a top of the solar power tower and a second end connected to the carriage, so that the carriage supporting the component is guided along the track.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a diagram of a concentrated solar power generation system having a lift assembly in accordance with the present invention.

Figure 2 is a side view of a tower having a lift assembly.

Figure 3 is a perspective view of a top of the tower having a winch for lifting and a crane for use with the lifting assembly.

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Figure 4 is a cross section of a track and carriage for use with the lift assembly.

DETAILED DESCRIPTION

FIG. 1 is a schematic diagram of a concentrated solar power generation system 10 having a lift assembly 12 in accordance with the present invention. In the embodiment shown, the system 10 comprises a power tower system having a lift assembly 12, a solar collector system 14, a central receiver 16, a tower 18, a cold storage tank 20, a storage tank hot water 22, a heat exchanger 24, a generator 26 and pumps 28A, 28B and 28C. Solar collector system 14 and central receiver 16 transmit heat from the sun to a molten heat transfer medium contained in storage tanks 20 and 22 so that thermal energy can be converted to electrical energy using heat exchanger 24 and the conversion system 26. The lift assembly 12 transports tower components up the tower 18 of the solar power generation system 10.

The solar collector system 14 comprises an arrangement of solar tracking mirrors, or heliostats, that concentrate the sun's rays on the central receiver 16 to heat a heat transfer medium. In one embodiment, approximately 8,500 heliostats, having surface areas of approximately 42 m² (square meters) at approximately 94 m², are arranged concentrically around a tower, which is approximately 170 meters high, to cover an area of ​​approximately 2.59 square kilometers (~ 1 square mile). The heat transfer medium typically comprises molten salt which is kept in a molten state between about 260.0 ° C (~ 500 ° F) and ~ 648.9 ° C (1200 ° F) so that it remains liquid. The pump 28A directs the cold heat transfer medium from the cold storage tank 20 into a plurality of tubes within the receiver.

ES 2 379 522 B2 central 16, whereby heat is transmitted from the concentrated solar rays to the heat transfer medium. The pump 28B directs the heated heat transfer medium from the receiver 16 to the hot storage tank 22 where it is stored in a state ready to produce energy with the heat exchanger 24. When it is desired to produce energy, the heated heat transfer medium is routed by pump 28C from the hot storage tank 22 to the heat exchanger 24 where the heat is fed into the conversion system 26. The conversion system 26 can comprise any conventional system that converts thermal energy into mechanical energy, such as the Brayton cycle or Rankine cycle systems. In the embodiment shown, the conversion system 26 comprises a steam turbine generator having a first phase expander 32A, a second phase expander 32B, a generator 34, and a condenser 36. The water within heat exchanger 24 is heated by the molten heat transfer medium to produce steam that rotates the first 32A and second 32B phase expanders. Expanders 32A and 32B rotate a shaft to drive generator 34 to convert mechanical energy to electrical energy. Thus, heat exchanger 24 removes heat from the heat transfer medium before the heat transfer medium is returned to the cold storage tank 20 through tube 30D. The use of a heat transfer medium such as molten salt enables the system 10 to efficiently store thermal energy in salt contained in the hot storage tank 22 so that electrical energy can be generated at times when the solar collector system 14 operates below the maximum peak. Thus, the system 10 can operate 24 hours a day at low energy production levels or at higher production levels for shorter intervals. Although the solar power generation system 10 is shown using three pumps to move molten salt through tubes 30A - 30D,

ES 2 379 522 B2 more or less pumps can be used. For example, in various embodiments, the height of tower 18 provides sufficient pressure to move molten salt into hot storage tank 22 so that pump 28B is not needed.

Although the solar collector system 10 is desirable, the construction of the central receiver 16 above the tower has proven difficult. Historically, cranes have been used to lift receiver components to the top of a solar power tower. With a crane, adverse weather conditions such as strong winds can cause construction delays and damage tower components. Specifically, if a crane and cable are used to lift a component such as a receiver panel up a tower, then wind conditions can cause the receiver panel to collide with the tower resulting in damage to the receiver panel. Lifting assembly 12 can be included in tower 18 to decrease construction time due to weather delays and costs associated with damaged components. The use of lift assembly 12 prevents components from colliding with the tower, thus allowing construction to continue even in windy conditions.

Figure 2 is a schematic side view of tower 18 having lift assembly 12. Lift assembly 12, receiver 16, tower 18, tower top 34, tower bottom 36 are illustrated. tower, track 38, cables 40A, 40B, winch 42, crane 43, wheels 44, trolley 46, and receiver panel 48. Lifting assembly 12 provides a means to safely move tower components, such as a tower receiver panel 18.

The tower surface lift assembly 18. The lift assembly 12 is

48, up and down is located on an illustrated embodiment, the one located on the surface

ES 2 379 522 B2 exterior of tower 18, although in an alternative embodiment, lift assembly 12 is located on the interior surface of tower 18. Receiver 16 is located on top 34 of tower and is supported by Tower 18. Tower 18 is a large vertical structure having a base or bottom 36 in contact with the ground and the top 34 extending several hundred meters (feet) into the sky. In one embodiment, tower 18 is about 91 meters (about 300 feet) high and in an alternate embodiment, tower 18 is more than 182 meters (600 feet) tall. Track 38 is substantially linear and extends longitudinally along the outer surface of the tower between top 34 and bottom 36. The first cable 40A is attached to the top 34 and extends downward toward the bottom 36 adjacent to the track 38. At the top 34, the first cable 40A is coupled to the winch 42. The winch 42 is coupled to and supported by tower 18, at a location adjacent to receiver 16. Second cable 40B extends downward adjacent winch 42 and receiver 16. Near top 34 and receiver 16, second cable 40B is coupled to crane 43. Crane 43 is coupled to and supported by receiver 16 at a location above winch 42. Wheels 44 are coupled to and can roll along track 38. In the embodiment shown, two sets of wheels 44 can be seen but more or fewer sets can be contemplated. Carriage 46 is coupled to at least one wheel and receiver panel 48 is releasably coupled, yet firmly coupled, to carriage 46.

Track 38 is configured to guide tower components, such as receiver panel 48, from base 36 to top 34 of tower 18. Equally possible is the use of track 38 to guide components from top 34 to the base of tower 18. Thus, track 38 provides a stable lifting platform for the

ES 2 379 522 B2 longitudinal movement of tower components regardless of adverse weather conditions. In use, a tower component is suitably attached to track 38 prior to traversing the vertical run of tower 18. In the illustrated embodiment, carriage 46 supports and attaches receiver panel 48 to track 38. With The lift assembly 12 may be used with a latch, catch, or any other means to secure the receiver panel 48 to the carriage 46. The carriage 46 is coupled to at least one wheel 44, a plurality of which are coupled to the track 38 and carry the load of the receiving panel 48 while using the track 38. The wheels 44 slide or roll along the track. track 38 to keep carriage 46, and hence receiver panel 48, on track 38.

The winch winds the first cable 40A to initiate the movement of the carriage 46 up the track 38. In alternative embodiments, the winch 42 is a pulley, a crane, or any other suitable means of lifting. Winch 42 continues to wind, retract, or wind first cable 40A, such that carriage 46 and docked receiver panel 48 move from bottom 36 to top 34 of tower 18. Once the receiver panel 48 is near the top 34 of the tower, the winch 42 stops lifting the first cable 40A and stops the movement of the carriage 46 and the attached receiver panel 48. In one embodiment, a friction brake is applied so that carriage 46 is held in place on track 38 near top 34. Second cable 40B is then coupled to receiver panel 48 so that crane 43 can take control of the movement of the receiving panel

48. Once the second cable 40B is strapped to and supports the load of the receiver panel 48, the receiver panel 48 and the carriage 46 is now free of the carriage 46.

eliminates the coupling between so that the receiver panel 48 The crane 43 can then rotate the receiver panel 48 three hundred and sixty degrees around the receiver 16 to position the receiver panel 48 at a predetermined location on the receiver 16. In embodiments

In alternative ES 2 379 522 B2, the crane 43 may be a winch, a pulley, or any other means of lifting and rotating. Furthermore, the crane 43 can be considered a positioning device. Once the receiver panel 48 is in a desired location, it can be fixed in the desired location and uncoupled from the second cable 40B and crane 43. The lift assembly 12 allows the receiver panel 48 to be lifted to the top 34 of the tower so that the central receiver 16 can be built or repaired even in high winds.

Figure 3 is a schematic perspective view of the upper part 34 of the tower with the lifting assembly 12.

<td colspan="4">Elevation Assembly Shown</td><td> 12,</td><td>the receptor</td><td>16, the</td>

<td>tower 18</td><td>, track</td><td> 38,</td><td>40A cables,</td><td>40B,</td><td>lathe 42,</td><td>Crane</td>

<td>43, the</td><td>car 46,</td><td>the</td><td>receiver panel</td><td> 48,</td><td>the rails</td><td>50, the</td>

<td>cover</td><td>lower</td><td> 52,</td><td>the cover of the</td><td>rec</td><td>eptor 54 and 1</td><td>Besides</td>

<td>higher</td><td colspan="3">56 of the receiver. Set</td><td>of</td><td>elevation 12</td><td>with the</td>

crane 43 allows the receiver panel 48 to be placed on the receiver 16.

The lift assembly 12, receiver 16, tower 18, track 38, cables 40A, 40B, winch 42, crane 43, trolley 46, and receiver panel 48 are arranged as described above with reference to Figure 2. In the embodiment shown, the track 38 includes two longitudinally spaced bars or rails 50 that extend vertically up the tower 18. An inner surface of bars 50 is adjacent to tower 18 and an outer surface of rails 50 is adjacent to carriage 46. Carriage 46 covers the distance between, and is coupled to, both rails 50. Bottom cover 52 protrudes from one side of the tower 18 and surrounds a portion of the track 38 near the top 34. The receiver cover 54 is located above the bottom cover 50 and supports the winch 42 as well as the central receiver 16. The upper part 56 of the receiver is located above the receiver cover 54 above the receiver 16 and supports the crane 56.

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As described above, the winch is used to raise the receiver panel 48 to a location near the top 34 of the tower. Two parallel rails 50 form track 38 to guide carriage 46 and receiver panel 48 up the tower 18. Once receiver panel 48 reaches a location near the top 34 of the tower, winch 42 stops. pulling the first wire 40A and thereby stops the movement of the carriage 46 and the attached receiver panel 48. The bottom cover 52 can be used to monitor and assist in the transfer of the receiver panel 48 from the adapter 46 to the second cable 40B. In an alternative embodiment, where track 38 is inside tower 18, bottom deck 52 would also be located inside tower

18. Once the receiver panel 48 is attached to the second cable 40B and uncoupled from the cart 46, the crane 43 has control over the movement of the receiver panel 48. In the depicted embodiment, the crane 43 lifts the receiver panel 48 above the deck. of receiver 54, which is essentially a scaffolding area used for maintenance or to service receiver 16. After reaching a predetermined height, the crane 43 can rotate the receiver panel 48 three hundred and sixty degrees around the receiver 16. The crane 43 functions as a positioning device for the receiver panel 48 as it guides the receiver panel 48 to a predetermined location on the receiver. 16. After being secured in place, the receiver panel 48 is uncoupled from the second cable 40B and the crane 43. Thus, the lift assembly 12 lifts and safely positions the receiver panel 48 over the receiver 16 at the top 34 of the tower. Track 38 reduces any unwanted movement of receiver panel 48 as it traverses the length of tower 18.

Figure 4 is a schematic cross section of tower 18, track 38, wheels 44, carriage 46, and receiver panel 48. Tower 18, track 38, wheels 44, carriage 46, panel are illustrated. receiver 48, rails 50, the

ES 2 379 522 B2 latch 58, bolts 60, running wheels 62, guide wheels

64, upper retaining wheels 66, and a bracket 68. The relationship between track 38 and wheels 44 restricts unwanted movement of carriage 46 and receiver panel 48 as they pass through tower 18.

Receiver panel 48 is coupled to carriage 46 via latch 58. In alternate embodiments, latch 58 may be a clip or hook or any other suitable means to non-permanently but securely attach receiver panel 48 to carriage 46. another side of carriage 46 is connected to at least one wheel 44 and bracket 68, which surrounds rail 50 and connects wheels 44 to each other. Wheels 44 are in contact with bracket 68 and rails 50 of track 38. The rails 50 are attached to the tower 18 by bolts 60. In alternative embodiments, the bolts 60 may be dowels or screws or any other suitable means to permanently attach the rails 50 to the tower 18. In the depicted embodiment, the wheels 44 are configured similarly to roller coaster wheels used in amusement parks. Wheels 44 are presented as sets, each set including three different types of wheels 44. More specifically, each assembly includes at least one caster wheel 62, at least one guide wheel 64, and at least one upper retaining wheel 66. The caster wheels 62 are positioned between carriage 46 and rail 50 so that they can travel on an outer surface of rail 50. Guide wheels 64 are located on a side surface of rail 50 and may be located on the inner or outer side of track 38. The upper retaining wheels 66 are located between the rail 50 and the tower 18 so that they travel on an inner surface of the rail 50. Thus, the wheels 44, as well as the connecting bracket 68, surround three sides of the rail 50. .

Wheels 44 are configured to allow vertical movement along track 38 but restrict a

ES 2 379 522 B2 movement away from track 38. Wheels 44 hold carriage 46, and thus receiving component 48, fixedly on track 38. More specifically, wheels 44 are configured to restrict movement in the steering away from the rail 50 to which the wheels 44 are attached. The rolling wheels 62 carry the load of the carriage 46 and the receiver panel 48 and keep these components rolling on the track 38. Guide wheels 64 prevent lateral movement of carriage 46 and receiver panel 48 away from track 38. Upper retaining wheels 66 further secure carriage 46 and receiver panel 48 to track 38 so that components cannot jumping onto the track or falling off the track 38. Wheels 44 secure carriage 46 and receiver panel 48 to rails 50 of track 38 so that movement in any direction other than vertical is prevented.

A lift assembly for use with a solar power tower was described above. In the depicted embodiment, the lift assembly extends vertically along an outer surface of the tower. In an alternative embodiment, the entire lift assembly is located within the tower. The lift assembly uses a track, cable, and winch used together to guide a tower component from the base of the tower to the top of the tower. In one embodiment, the tower component is a receiver panel, which is transferred to a crane (also known as a placement means) on top of the tower. The crane rotates the receiver panel to its predetermined location on the receiver. Once all the tower components, such as the central receiver, are disassembled, the lift assembly can be converted into a freight elevator. The cart, which was previously used to attach receiver panels to the runway, can be replaced with a bracket or simply modified to carry teams or men up and down in the same way that the cart once traversed the tower.

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Although the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that changes can be made with respect to form and detail without departing from the spirit and scope of the invention.