ES2396078B2 - Device for capturing concentrated solar radiation, with drainage of heating fluid - Google Patents

Abstract

Device for capturing concentrated solar radiation, with drainage of the heating fluid, consisting of an aligned and inclined set of sealed housings with a transparent window for the passage of concentrated radiation, at least one beam of at least one absorber tube exists, and disposing in the longitudinal half of the beam inside the housing of an expansion hose, which forms with the pipes a drain conduit in which there are no steps or projections, and which ends in a vertical drain pipe, usually closed by a valve . The pipe discharges into an insulated fluid storage tank, from which it is pumped when the installation is to be filled. To compensate for pressures during emptying, an inert gas injected at moderate pressure is used.

Description

CONCENTRATED SOLAR RADITION CAPTURE DEVICE. WITH HEAT FLUID DRAINAGE: FIRE

SECTOR OF THE TECHNIQUE

The invention is framed in the field of solar power plants that require concentration of the original yield, which in this case is reflected by a series of longitudinal Icm mirrors whose longer axes are horizontal or slightly inclined, and rotatable in direction to rotate around its axis of longitudinal symmetry; focusing the radiation reflected on a similarly longitudinal receiver, with its long horizontal axis or slightly inclined, and parallel to the mirrors' axes. Said device is usually referred to as the Fresnel of reflection, but the novelty does not refer to its optics, but to the longitudinal conduits pOlr which circulates the heating fluid, which must be drained when it is pervasive, for example to prevent its solidification in the receiver tubes when there is no solar radiation and the environment is cold with respect to the freezing point of said fluid.

BACKGROUND OF THE INVENTION

The invention has two immediate antecedents, of the same applicants, which are the patent ES 234542782 as regards the field of mirrors and the Fresnel structure, and the patent ES 234575982 as regards the receiver, particularly its figure 8, which a In turn, the patent of the same first applicant, ES 232157682, which deals with a compensated expansion and pressure manifold, is such an immediate antecedent, such collector, with an important innovation, being used as a receiver module in this new invention.

As regards the drainage of the fluid, there is a significant number of patents and applications that deal with the drainage of pipes and deposits, although the applicants do not know any! that refers to the circuits of a Fresnel-type solar concentration device, or of another type of distributed configuration collector. There are several devices in the state of the art for water drainage, particularly from fuel tanks, but none have the geometric and functional characteristics of the assemblies considered here. As examples you can cite documents US2012193300A1, which drains by gravity and logically has a lower drainage collection tank, similar to the one raised in an auxiliary way in this application; and W02012024013 A 1, c () n less similarities in the macroscopic configuration of the pipeline circuit.

You can also mention several inventions of the food industry, such as GB 2471307, GB 2414284, dedicated to the cleaning of beer dispensing circuits, and US 2006097008 dedicated to emptying and cleaning chemical fluid circuits in general, without any direct antecedents in them of the novel solutions, contributed in this invention. The same is true of GB 2142 ~ 112 patents, on the same subject as the previous one, and precedent for it.

Inventions are also found, drainage works dedicated to agriculture, such as W02012040252 (A2) and also to geological surveys and underground drilling, such as US2012043081A1. None of them contain elements such as those here ideal for the drainage of fluids that may also have very different temperatures depending on the operating conditions (or non-operation) of the solar plant.

TECHNICAL PROBLEM TO BE SOLVED

Heat fluids such as water, thermal oils and molten salts are used to reach high temperatures, but in the absence of the sun they logically cool down, and may even freeze, with the subsequent negative effect; that in the water the pipes can burst, and in the molten salts to cause a solid plug of such considerable dimensions, that the tubes have to be replaced, since their heating until the salts melt, would lead to a strong deterioration in the tubes.

The solution to this problem consists in emptying the ducts exposed to the cold weather, transferring the fluid to suitably insulated tanks, from which it can again be introduced into the radiation absorbing tubes. These actions must be compatible with the geometry and arrangement of said tubes to carry out their work as heat fluids.

DESCRIPTION OF THE INVENTION

The invention consists in mounting the absorber tubes of the solar radiation concentration device with a certain inclination on the horizontal plane of the place, which obliges the axes of the mirrors that constitute the concentration units of the radiation, calling master lines of inclination to which it is parallel, at the point of interest, to said axes, and master planes of inclination or assembly to the formed, at the point of interest, by the master line and the normal horizontal to it, configuring the structure of the abberator tubes as a set of modules characterized because:

the tubes are contained in longitudinally-shaped housings, which follow the master inclination plane, said housings hanging, and hence Ic) s tubes, of a longitudinal beam or truss with the same inclination as said master line of the device;

each row of consecutive housings forming a unit of the solar device, there are usually several of these units in a solar power plant, and each unit is equipped with its own drainage equipment, consisting of the set of pipes, sensors, valves, tanks and pumps, and also each unit equipped with a gas supply equipment, preferably inert, for filling the pipes that are emptied when the heating fluid is drained;

each housing can contain one or more tube bundles, suspended from IEI back cover of the housing, in turn suspended from the truss of the unit, each bundle of tubes topped at each end by a manifold, provided with connection conduit with the outside, said conduit passing through the corresponding head of the housing, being fixed to said head by welding or other joining mechanism, which includes a hermetic seal between the head and the tube conduit;

and each tube bundle having an interruption as such a beam, in half of its length inside the housing, both longitudinal halves of the beam being connected by an expansion hose, which runs from a side end of the manifold where the half ends upstream of the tube bundle, to the side end of the other side of the manifold that has half the beam connecting downstream of the hose;

the virtual plane tangent to the inferior surface of the hose coinciding with the virtual plane tangent to the lower surface of

the collectors of the tubes as well as the tubes themselves, both from the upstream semi-beam and the downstream semi-beam, forming a single plum on which virtually supports the entire bottom surface of pipes, manifold, hose, downstream manifold , downstream pipes and connecting conduit with the downstream housing, without rungs or projections on said lower surface from the highest part of the unit tubes, to the lowest part of the unit, and said plane being unique, flat assembly master;

said lower part of the unit being connected to the vertical drain pipe, at whose head there is a valve, closed in the operating conditions of the plant, and open when the set of absorber tubes is emptied or filled with the heating fluid .

The drainage device consists of said vertical drainage pipe, its upper opening-closing valve, the thermally insulated tank in which the fluid is stored to prevent freezing, and which can be equipped with an auxiliary heating device, and the filling pump, which takes the fluid from the tank to transfer it to the unit's tube bundles.

In turn, the invention consists of a gas injection system in the tubes when they are emptied, which acts from the top, with the compressed gas tank located above the truss or beam from which the housing assembly hangs. , or above an adjoining unit upstream; and existing, in the upper part of each unit, a relief valve for gas extraction, which is sucked by a compressor that houses the gas in said tank or upper tank, from which it can be directly injected into the tubes, to the same time they drain.

The units or alignments of housings with their tubes, can be located one after the other, with the connections considered for the heating fluid, always being the master lines of these units parallel to each other. In these cases, the location of the gas injection and extraction device can be located on the truss or master beam of an adjoining unit upstream.

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DESCRIPTION OF THE FIGURES

The figures, in general, are not to scale, since the relative sizes of the elements are very different; for example, the width of the receiver and the mirrors will be noticeably less than their length, and also much less than the height at which the receiver is supported.

Figure 1 shows a schematic: side of the assembly of a unit. Figure 2 shows the side diagram in greater detail of the components of the drainage system and the gas injection system. Figure 3 shows a transverse sectional elevation of a receiver support pillar and the drainage circuit. Figure 4 shows the diagram of a module of the collector of the invention, in top view, with the beams inside the housing. Figure 5 shows the straight section of a collector module of the invention, in longitudinal section.

PREFERRED EMBODIMENT OF THE INVENTION

In order to facilitate the understanding of the figures of the invention, and of their embodiments, the relevant elements thereof are listed below:

one.

Solar radiation receiver, Composed of tube bundles.

2.

Case.

3.

Beam or master truss,

Four.

Stands or tall pillars that keep the receiver in height and position

(1) of radiation and all its associated elements.

5.

Generic longitudinal mirror that reflects the original solar radiation on the receiver (1). There is a plurality of parallel mirrors in all of them, which reflect the radiation on the same receiver (1).

6.

Low pillars that maintain their height and position at the axes of the mirrors, generically represented by (7).

7.

Spinning axis of a longitudinal mirror.

8.

Motor and rotation clutch of a mirror O.

9.

Ground.

10.

Heat fluid that goes inside the tubes.

eleven.

Glass window of the housing.

12.

Drain pipe (of the unit shown in figure 2).

13.

Pipeline valve 12.

14.

lyre of expansion and disconnection, for extraction of the lower part of the pipe.

fifteen.

Tank cap 16.

16.

Drained fluid storage tank.

17.

Insulation of the deposit, which can be underground.

18.

Refill pump

19.

Drain pipe of the unit following the one shown in the figure

2.

twenty.

Pipeline valve 19.

twenty-one.

Connection of the unit represented in Figure 2 with its gas system, similar to that represented in the figure, which serves the previous unit.

22

Connection valve 21,

2. 3.

Connection of the previous unit to that represented in figure 2 with its gas system (comprising elements from 24 to 28).

24.

Connection valve 23.

25.

Gas extraction pump or compressor, and injection into the pressure vessel 26.

26.

High pressure gas tank or tank.

27.

Tank 26 drain valve to fill the pipes when draining.

28.

Fastening of the gas system on the master truss.

29.

Hanging fastening of the carcas: sas of the unit.

30

Central tube beam

31.

Beam from side to right side, according to the direction of drainage.

32

Beam pipe side to sinister, according to the direction of drainage.

33.

Expansion hose of the central beam 30. Although the common designation of the hose is used because of the curves it makes, it can be of similar diameter to that of the beam tubes.

3. 4.

Side beam dilation hose 31.

35

Lateral beam expansion hose 32.

36.

Corner wedges to avoid backwater salt when emptying,

37.

Separation joints with the recessed part of the housing.

38.

Separation joints with the non-recessed part of the housing.

39.

Plenum or central beam input manifold in the hose.

40

Plenum or right-hand beam input manifold in the hose.

41.

Plenum or sinister beam input manifold in the hose.

42

Plenum or outlet manifold from the central beam hose.

43

Plenum or outlet manifold from the right hand beam hose.

44.

Plenum or collector output from the hose of the beam to sinister.

Four. Five.

Drain outlet head.

46.

Inlet head in the next drain flow housing.

47

Connection of the central beam with the next housing downstream in the drain.

48.

Right-hand beam connection with that of the following housing downstream in the drain.

49.

Sinister beam connection with that of the following housing downstream in the drain.

fifty.

Insulating wall of the housing.

51.

Inner side of the recess len the wall 50, to give slack to a small lateral movement of the tubes when dilated.

52

Welded flanges conduit-fits! Zal.

53.

Crossbar holding the tubes.

54

Ears for the hanging fastening of the housings.

55.

Vertical bar clamping braces 53.

56.

Glass-housing fastener.

57.

Side view of the dilatation hose.

58.

Insulating separator between beams.

59.

Plate-fin on the hose, solidary with it.

60

Upper head of the housing.

The preferred assembly of the invention starts from establishing the master line of the device, which will typically be a North-South line with a selected inclination. That slope will depend primarily on the viscosity and surface tension of the fluid under the conditions that are expected to be the worst for drainage, but will typically be a few degrees. For water, a more than enough slope is 1% (Ea even half of that), and for molten salts 2%, which would also be valid for hot oil. In the cold oil your Prandtl number increases a lot, so a little more slope would be necessary.

Once this is defined, the receiver assembly is sized, in particular its staff or porches, as well as its beam or master truss. The width of the receiver and the number of tubes per beam, plus the number of beams, must come from the optical project, along with the length of the receiver unit being considered. From this data the volume of fluid to be drained will be extracted, and therefore the storage size of that unit. The fluid that is in the power block or returning from it, will be drained by conventional methods to the respective tanks.

The pressure of the compensation gas is moderate, because in the end the drainage action will be activated by gravity, and the function of the gas is to prevent the vacuum effect that would cause a drain without compensation, which apart from the mechanical suction effect, which does not It would allow an effective emptying, could induce the formation of pores and entry of: air, with dire consequences for the corrosion of the material of the tubes.

Suppose it is water, which boils at 240 ° C and 38 bar in the main beam, while in the peripherals: it warms up from 40 ° C to 240 ° C. Steel tubes are selected, in tnes beams, the central 20 cm consisting of 4 tubes of 5 cm outside diameter, and each peripheral beam of 15 cm, with 5 tubes of 3 cm. Using a ring tension of 380 bars as the design reference, the required thickness is one tenth of the radius. This allows computing the volume of water in the 100 meters that we assign to each beam of a unit, with a total of 0.63 m3 in the plant and 0.5 between the two peripherals. This necessitates a volume of the tank, not counting other auxiliary inventories of water, of 1.13 m3, and would be stored at atmospheric pressure.

The gas would have to fill the fluid dl9 circuit with a pressure above atmospheric, to avoid air ingress, but there is no need to pressurize the system strongly. A pressure of 2 bars seems to be a maximum very much in line with the engineering experience. This ignores that if it is stored in the tank at 20 bar, the volume of this will be the twentieth part of the volume to be filled, that is, 1.13 /twenty; therefore, about 60 liters. The power of the compressor would also be moderate. If we admit a gas evacuation (N2 in particular) with a flow rate of 1 liter per second, to inject it into the tank, at 20 bar, from the circuit at 1 bar (lower case of filling pressure), some power would have less than 200 W. The gas extraction time would be about 15 minutes; necessary in turn to pump the fluid to fill the circuit. On average it would be equivalent to increasing the potential energy of 1,130 kg of water in about 15 meters, in about 1000 seconds, which represents 170 W.

All this is considered very commensurable with the problem to be solved; although it is also important to analyze the problem of dilation. If it is considered a minimum temperature of -10 ° C (without soll, obviously) and the maximum at which the central beam will be is 240 oC, the jump, to be assimilated by the expansion hose is 250 oC; which has to be applied to a common steel, whose coefficient of linear expansion is in the order of or slightly above 10-5 ° C-1, which means that a length L at the minimum temperature will transform 1.0025 L, at maximum temperature. It should be borne in mind that the idea is that all the expansion is practically absorbed by the tubes, even when the housings are also heated, although much less. If the length L of a carcass is taken in 10m, the tubes will expand by about 2:, 5 cm, which must be absorbed in the hose. Note in the figures that the hose crosses 20 cm of the width of the beam from one side to the other, the faces of the beam being separated about 13 cm in this case; although this separation is reduced in the hot state by approximately 1.25 cm on each side. This makes it happen from a cold situation in which the angle of the hose arm is 60 ° at a more forced angle, 68 ° which in principle seems acceptable. If it were desired to lower the deformation, it could be achieved by increasing the longitudinal disitancy in cold between both halves, but logically that damages the radiation uptake. How

indicative separation between two semi-beams, taking into account the balance between not inducing excessive deformation in the hose, and not losing too much radiation captured, the separation must not be less than twice the maximum expected expansion, or greater than the lowest value between the sixfold of that dilation, or twice the width of the beam.

In any case, and optionally to reduce the loss of captured radiation, in the face of the hose on which it affects! The incident radiation is placed, attached to it, a radiation-absorbing plate (59), which covers the space of interruption of the beams.

And as for the carc: handle itself, its straight cross-sectional horizontal section, as shown in Figure 4, is set back on its inner face (51), separating more than! the tubes, in the parts corresponding to the transverse expansion zone of the hose, in such a way that said retraction leaves between the inner wall of the housing and the nearest edge (61) of the nearest bundle of tubes, a space between the maximum expected expansion in the tubes of! 1 semi-hotter beam, and this value multiplied by the number of beams plus one. This measure is adopted because the dilation of the beams will be partially absorbed with the dilatation of the hose itself, not only with its angular deformation. This implies that the hose grows transversely, which produces a small lateral displacement of each semi-beam, in the direction given by the growth of the hose; which must be accommodated in the housing. Obviously, this lateral displacement causes a certain turn in the tube-flange-head junction of each end, since the rotation is of the order of the thousandth of a radian, since the lateral displacement will be millimeters, and the length of the beam will be meters.

The tube bundles are mounted from supplied pipes, welded to the collectors at each end, and the collectors are in turn welded to the corresponding ducts: in the Class of the semi-beams upstream in the direction of drainage , the upper manifold receives the fluid inlet tube in that housing, and the lower one is connected to the hose; which at its other end is connected to the upper collector of the downstream semi-beam. This semi-beam, at its lower end, ends in the connecting conduit that exits that housing through its lower head (45), which is fixed by a welded flange (52); analogously to how the inlet pipe is going in the housing, going through the

upper head of the housing itself (60) or the next downstream of the drain (46).

Once the invention is clearly described, it is noted that the particular embodiments described above are subject to modifications in detail as long as they do not alter the fundamental principle and essence of the invention.

Claims (1)

1 - Device for capturing concentrated solar radiation, with drainage of the heating fluid, in which the absorber tubes of the solar radiation concentration device are mounted with a certain inclination on the horizontal plane of the place, mounting the axes with the same inclination9 of the mirrors that constitute the radiation concentration units, calling master inclination lines to which it is parallel, at the point of interest, to said axes, and master plane of inclination, or of the assembly, to the formed, at the point of interest, by the master line and the horizontal line normal to it, configuring the structure of the radiation capture tubes as a set of modules, characterized in that: the tubes are c () held in housings (2) longitudinally, which follow the inclination master plane, said carcases hanging: handles, and therefore the tubes, of a longitudinal beam or truss (3) with the same inclination as said device master line (); each row of consecutive housings forming a unit of the solar device, there are usually several of these units in a solar power plant, and each unit is equipped with its own drainage equipment, consisting of the set of pipes (12, 19), valves (13, 20, 27), tanks (16, 26) and pumps and compressors (18, 25), and also each unit equipped with a gas supply equipment, preferably inert, for filling the pipes that empty when drained the heating fluid (10); each housing containing one or more bundles of tubes (30, 31, 32), suspended, slide the back cover of the housing, in turn suspended from the fence: there is or master beam of the unit, each bundle of tubes being topped on each end by a manifold, provided with a connection conduit with the outside, said conduit crossing the corresponding head of the housing (45, 46, 60), being solidary to said head by welding or other joining mechanism, which includes a hermetic seal or flange (52) between the head and the tube conduit; and each tube bundle having an interruption as such a beam, in half its length inside the housing, both longitudinal halves of the beam being connected by an expansion hose (33, 34, 35), which runs from a lateral end of the collector in which the half ends upstream of the tube bundle (39, 40, 41), the lateral end of the other side of the connection manifold (42, 43, 44) to the semi-beam downstream of the hose; the virtual plane tangent to the inferior surface of the hoses coinciding with the virtual plane tangent to the inferior surface of the collectors of the tubes as well as the tubes themselves, both of the upstream semi-beam and the downstream semi-beam, forming a single picana in which it virtually supports the entire bottom surface of pipes, manifold, hose, downstream manifold, pipes abijo and connection pipe with the housing downstream, without rungs or projections on said bottom surface from the highest part the tubes of the unit, to the lowest part of the unit, and said plane being the only, master plane of the assembly; said lower part of the unit being connected with the vertical drain pipe (12), in whose head there is a valve (13), closed in the operating conditions of the plant, and open when emptying or filling the set of tubes of the solar receiver with the heating fluid (10). 2 - Device for capturing concentrated solar radiation, with drainage of the heating fluid, according to claim one, characterized in that the drainage device consists of said vertical drainage pipe (12), its upper opening-closing valve (13), the thermally insulated tank (16) in which the fluid is stored, optionally! equipped with an auxiliary heating device, and the lIenadCl pump (18), which takes the fluid from the tank to transfer it to the unit's tube bundles. 3-Device for capturing concentrated solar radiation, with drainage of the heating fluid, according to first and second claims, characterized in that the invention consists of a yes!) Topic of gas injection into the tubes when they are emptied, which acts deisde the upper part, the compressed gas tank (26) being located above the truss or beam (3) from which the housing assembly hangs, or above a neighboring unit upstream; Y There is, in the upper part of each unit, a relief valve (24) for gas extraction, which is suctioned by a compressor (25) that houses the gas in said tank or upper tank (: 26), from which It can be directly injected into the tubes, at the same time they are drained. 4-Device for capturing concentrated solar radiation, with drainage of the heating fluid, according to any of the preceding claims, characterized in that the units or alignments of housings with their tubes, can be located one after the other, with the connections considered for the heating fluid, always being the master lines of these units parallel to each other. 5 - Device for capturing concentrated solar radiation, with drainage of the heating fluid, according to any of the preceding claims, characterized in that the orientation separation between two semi-beams for the location of the expansion hose, must not be less than double of the maximum expected expansion, or greater than the smallest value between the sixfold of that expansion, or double the beam width. 6-Device for capturing concentrated solar radiation, with drainage of the heating fluid, according to any of the preceding claims, characterized in that on the face of the hose in which the incident radiation strikes, a plate is attached, attached to it. radiation absorption fin (59), which covers the interruption space of the beams. 7 - Device for capturing concentrated solar radiation, with drainage of the heating fluid, according to any of the preceding claims, characterized in that in the parts corresponding to the transverse expansion zone of the hose, the space left in the assembly between each part of the recessed inner wall of the housing (51) and the nearest edge (61) of the nearest bundle of tubes, has a width between the maximum expected expansion in the tubes of the warmest semi-beam, and this value multiplied by the number of beams plus one.