FR3092626A1 - DEVICE TO ENSURE THE COOLING OF THE ELECTROMECHANICAL EQUIPMENT OF A HYDROELECTRIC POWER PLANT - Google Patents

Abstract

This device for cooling the electromechanical equipment of a hydroelectric power station comprises at least one access pipe or penstock (2) of the water, at the level of the turbine (s) (3) actuating an alternator or generator ( 4) for the production of electricity, this device comprising a closed circuit within which circulates a heat transfer fluid and in particular water, under the action of a pump, conveying said heat transfer fluid or water at the level one or more individual exchangers associated with said electromechanical equipment, said heat transfer fluid or water being cooled in contact with a cold source (1). The cooling of the heat transfer fluid or of the water circulating in the cooling circuit by the cold source is carried out by means of a main exchanger, consisting of the filtration grid (s) (8) positioned upstream of the ( of) water access pipes (2) at the level of the turbine (s) (3), said grid (s) consisting of tubes (10, 11, 12) within which the coolant circulates or water and bars (13) joining part of said tubes together. Figure for the abstract: Fig 1

Description

DEVICE FOR COOLING THE ELECTROMECHANICAL EQUIPMENT OF A HYDROELECTRIC POWER STATION

The invention falls within the general field of hydroelectric power stations, that is to say power stations generating electricity from waterfalls, dams, etc. It relates more specifically to the cooling or refrigeration of the electromechanical equipment of such power stations.

Prior state of the art

The genesis of electricity in hydroelectric power stations is fundamentally based on the rotation of turbines driving a shaft line of an alternator (rotor + stator), the rotation of the turbine being obtained by the energy of water from a river or river, or a water reservoir (dam), the water passing through a pipeline or penstock ending at the level of the turbine(s).

In this particular context, it is known that the lubricants (mainly oils) ensuring the lubrication of the elements of the pivoting of the shaft integral with the turbine(s) (the pivots, the bearings, multipliers, etc.) heat up due to the rotation of said shaft and therefore require their cooling.

In the same way, it is also known that due to the rotation of the rotor mounted on the shaft integral with the turbine (or connected via a multiplier), and the circulation of the electric current then created within the stator, it Here again, a rise in temperature is created, de facto also requiring cooling of the confined enclosure in which the rotor and the stator are located.

To this end, it is known to implement a cooling circuit provided with individual heat exchangers at the level of the mechanical elements heating up due to the rotation of the shaft, but also at the level of the enclosure confined in which the rotor and the stator are present. This cooling circuit can be closed or open. Such a circuit consists of a set of pipes, pumps, filters and heat exchangers. A heat transfer fluid and typically water circulates in the pipe(s), due to the heat capacity of the latter being much greater than that of air, and therefore developing efficiency in terms of heat exchange which is also very significantly improved compared to that of air.

An open circuit is supplied with water from a cold source, typically constituted by the river at which the plant is located, or from a well. The water from the cold source is pumped into said circuit and circulates through filters and heat exchangers and is then returned downstream, in this case the river.

It is also known to implement a double cooling circuit, respectively consisting of an open circuit of the type described above, and a closed circuit, the latter ensuring the effective cooling of the electromechanical equipment. A main heat exchanger cools the closed circuit with the water circulating in the open circuit.

Whatever the cooling circuits implemented, they systematically comprise at least one open circuit, or alternatively an open loop. However, experience shows that the implementation of such an open loop is subject to the clogging of filters and exchangers, due to the suspended solids present in the cold water source, in particular during episodes of raw. When the cold source supplying this open loop consists of water stored in a well or a water table, clogging of the open loop, and therefore of the open circuit, by the bacteria present in these wells is also observed, due to the formation of deposits of biofilms of organic matter generated by said bacteria.

Whatever the origin of the clogging or fouling of the covered loop, it is necessary to periodically carry out a complete cleaning of the piping, most often requiring the shutdown of the hydroelectric power station, and therefore as a corollary a significant loss of earnings for the operator. In addition, when the cold source consists of water pumped into a well, it may prove necessary to carry out periodic chemical treatments of said water to prevent bacterial proliferation, such operations being liable to prove incompatible with current environmental regulations.

The invention aims to overcome these various drawbacks.

Firstly, the invention proposes to eliminate any open loop or open circuit, in order to avoid these problems of clogging or fouling of the piping and the associated filters, whether these problems come from suspended matter or are from organic origin. Secondly, the invention proposes to use one of the elements present in all hydroelectric power stations, to constitute the main exchanger with the cold source, necessary for the desired cooling.

It proposes a device for ensuring the cooling of the electromechanical equipment of a hydroelectric power station, of the type comprising at least one supply channel, an access pipe or a penstock water pipe, at the level of the turbine or turbines actuating an alternator or generator for the production of electricity, this device comprising a closed circuit within which circulates a heat transfer fluid and in particular water, under the action of a pump, conveying said heat transfer fluid or water at one or more individual exchangers associated with said electromechanical equipment, said heat transfer fluid or water being cooled in contact with a cold source.

According to the invention, the cooling of the heat transfer fluid or of the water by the cold source is carried out by means of a main exchanger, consisting of the filtration grid(s) positioned upstream of the pipeline(s) of water access at the level of the turbine or turbines, said grid(s) being made up of tubes within which the heat transfer fluid or water circulates and of bars securing the tubes together.

In other words, the invention consists in modifying equipment that already exists within hydroelectric power stations, in this case the filtration grid located upstream of the inlet pipe or penstock conveying the water at the level of the turbine, and immersed in the river or in the water retaining dam in question, and to modify this grid so as to allow the circulation within it of the heat transfer fluid and in particular of the cooling water of the cooling of the various electromechanical equipment.

Indeed in a traditional way, this filtration grid is systematically implemented in order to filter the water conveyed at the level of the turbine and thus to avoid the introduction at this level of floating bodies of any kind, such as branches, various detritus, etc Such a screen is conventionally placed and fixed on a concrete frame and has a screen system for manual or automatic cleaning.

In order to optimize the heat exchange with the water of the river or the reservoir, constituting the cold source, and therefore located upstream of the turbine, the bars joining together said tubes have a substantially planar shape, and extend radially from said tubes.

The various constituent elements of the grid are typically made of metallic materials, and therefore good thermal conductors, and of which an optimized contact is also ensured between them, precisely in order to ensure the thermal conduction typically between the bars and the tubes, this in the objective of optimizing the heat exchange between the water from the cold source and the heat transfer fluid or the water circulating in the cooling circuit.

According to the invention, the cooling circuit of the electromechanical equipment can be a double circuit, respectively a primary circuit, connected with the aforementioned grid, conveying the water or a heat transfer fluid to the level of a main exchanger, at the level of which a heat exchange with a secondary circuit, also closed, which itself cools the electromechanical equipment. In this configuration, there are two closed circuits.

Brief description of figures

The way in which the invention can be implemented, and the resulting advantages, will become clearer from the example of embodiment which follows, given by way of indication and not limitation in support of the appended figures.

Figure 1 is a schematic representation of a hydroelectric power station in section.

Figure 2 is a schematic representation in perspective of a filtration grid located upstream of the water supply pipe at the level of the turbines or the penstock.

Figure 3 is a schematic view of the grid according to the invention, of which Figure 4 is a detail view.

Figure 3 is a schematic view of the grid according to the invention, of which Figure 4 is a detail view.

FIG. 5 schematically illustrates a portion of the grid of the invention.

Detailed description of the invention

As indicated above, Figure 1 shows a schematic sectional view of a traditional hydroelectric dam. Basically, this dam defines a water reservoir (1) and incorporates a pipeline or penstock (2) conveying the water (1) to the level of a turbine (3), ensuring the rotation of the rotor of an electric generator (5) located in the engine room (4). After rotating the turbine, the water is evacuated downstream, typically at the level of a river or a demodulation basin (6). The rotation of the generator rotor causes the production of electricity, which is then routed by means of high voltage lines (7) in connection with the electrical network considered.

The penstock or pipe (2) comprises upstream, typically submerged in the reservoir (1), a filtration grid (8), intended, in a known manner, to filter the water conveyed to the level of the turbine, in order to exclude all floating bodies, and preserve the integrity and durability of the turbine(s). A screen-type cleaning device is conventionally installed with the screen. Such a grid is illustrated in relation to Figure 2.

Such a grid is conventionally fixed at the level of the concrete structure (9) constituting the actual dam. In the example described, it appears inclined with respect to the horizontal. It is located upstream of the upper opening of the penstock, at the level of which the water from the reservoir falls by simple gravity. The grid is sized in such a way as to resist in particular the pressure of the water stored in the reservoir defined by the dam.

According to the invention, the grid in question is modified to act as a heat exchanger for a cooling circuit for the electromechanical equipment integrated into the power plant itself, and more specifically, for the lubricating oils of the components receiving the drive shaft. the turbine and/or the shaft of the generator rotor, including the multiplier, and of the enclosure receiving said generator, respectively rotor and stator.

This cooling circuit (not shown) typically consists of a pipe within which circulates a heat transfer fluid and in particular water, this circulation resulting from the implementation of one or more pumps.

This cooling circuit is therefore looped, and therefore closed, at the level of said grid (8), the latter being for this purpose provided with hollow tubes (10, 11, 12), respectively with a distributor tube (10), at which the heated water C of the cooling circuit is conveyed, a collecting tube (11), recovering the cooled water following the passage of the water within the grid, the said collecting tube (11) being itself in continuity with the pipe constituting the cooling circuit and leading the then cooled water F to the level of the individual exchangers present in the plant, and ensuring, as already said, the cooling of the electromechanical equipment, and of the intermediate tubes (12 ), connecting at discrete intervals the distributor tube (10) to the collector tube (11) in order to allow the circulation of the water of the cooling circuit.

The various intermediate tubes (12) are also mechanically connected to each other by a certain number of transverse bars (13), substantially parallel to the distributor tube (10) and to the collector tube (11), in order in the first place to give the grid the mechanical resistance necessary for its primary function as a filter. According to the invention, these bars (13) may be in the form of fins, extending substantially radially with respect to said intermediate tubes, and as can be clearly seen in Figures 4 and 5. Ideally, these bars are substantially plane and extend parallel to the flow of the cooling water, with the aim of optimizing the contact between the water constituting the cold source and the bars and, as a corollary, the tubes (12), and therefore the heat exchange at this level.

These bars (13) are welded at the level (14) of the intermediate tubes (12), so as to optimize the contact of the bars with the tubes, with the aim of optimizing thermal conduction and, as a corollary, the dissipation of heat. water from the cooling circuit, this dissipation being symbolized in FIG. 4 by multicurvilinear arrows. The various arrows E have also symbolized the flow of water from the cold source crossing the grid before rushing into the penstock (2). The various constituent elements of the grid (8) are made of a material that is a good thermal conductor and also has good mechanical properties, and for example of metal, typically steel.

Due to the presence of the bars attached to the intermediate tubes, the heat exchange surface between the water from the river or the dam and the water from the cooling circuit circulating in the grid is significantly increased.

The grid thus produced therefore retains its initial filtration function, and also performs, in accordance with the invention, the function of heat exchanger.

Due to the size of the grate or gratings (depending on the number of forced pipes that the hydroelectric plant has), efficient cooling of the heat transfer fluid and in particular of the water circulating in the cooling circuit is ensured, making it possible to achieve at a temperature differential between the water C ending up in the distributor tube (10) and the water F collected by the collector tube (11) close to 5°C and in any case sufficient to dissipate the heat generated in the hydroelectric power station and, more specifically, by electromechanical equipment.

When required, the cooling circuit can consist of a double closed loop, respectively a primary circuit of the type described above, and a secondary circuit, comprising the unit exchangers and penetrating into the plant, the two circuits being in heat exchange with each other at the level of a heat exchanger of conventional invoice, and known from the prior state of the art.

One can in fact conceive the whole advantage of the present invention which makes it possible in an effective and simple way to overcome the disadvantages of the devices of the prior state of the art, and to use an element already existing at the level of hydroelectric power stations, in this case the filtration grid located upstream of the pipe or penstocks of a hydroelectric power station.

Furthermore, the invention has another significant advantage, namely that due to the heat exchange occurring at the level of the grid, it is therefore generated, in particular at the level of the surface of the water or the reservoir of water inherent in the dam, sufficient warming to melt the ice likely to be created in cold weather in the vicinity of said grid.

Claims (5)

Device for cooling the electromechanical equipment of a hydroelectric power station, of the type comprising at least one access pipe or penstock (2) for water, at the level of the turbine (s) (3) actuating an alternator or generator (4) for the production of electricity, this device comprising a closed circuit within which circulates a heat transfer fluid and in particular water, under the action of a pump, conveying said heat transfer fluid or water to the level of one or more individual exchangers associated with said electromechanical equipment, said heat transfer fluid or water being cooled in contact with a cold source (1), and cooling of the heat transfer fluid or water circulating in the heating circuit cooling by the cold source being carried out by means of a main exchanger, consisting of the filtration grid (s) (8) positioned upstream of the access pipe (s) (2) of the water at the level from where you rbines (3), said (said) grids consisting of tubes (10, 11, 12) within which circulates the heat transfer fluid or water and bars (13) joining part of said tubes together, characterized in that the bars (13) joining together the so-called intermediate tubes (12) adopt a substantially planar shape, extending radially from said intermediate tubes. Device for cooling the electromechanical equipment of a hydroelectric power station according to Claim 1, characterized in that the various constituent elements of the grid are made of metallic materials, and in particular of steel. Device for cooling the electromechanical equipment of a hydroelectric power station, of the type comprising at least one access pipe or penstock (2) for water, at the level of the turbine (s) (3) actuating an alternator or generator (4) for the production of electricity, this device comprising a first closed circuit within which circulates a heat transfer fluid and in particular water, under the action of a pump, conveying said heat transfer fluid or water at the level of one or more individual exchangers associated with said electromechanical equipment, and a second circuit in thermal exchange with said first circuit, within which also circulates a heat transfer fluid and in particular water, and ensuring the cooling of the water or heat transfer fluid circulating in the first circuit, characterized in that the second circuit is mounted in a closed loop, and in that the cooling of the heat transfer fluid or of the water circulating in the second circuit is carried out by means of a main exchanger, consisting of the filtration grid (s) ( 8) positioned upstream of the water access pipe (s) (2) at the level of the turbine (s) (3), said grids consisting of tubes (10, 11, 12) within which circulates the heat transfer fluid or water and bars (13) joining part of said tubes together. Device for cooling the electromechanical equipment of a hydroelectric power station according to Claim 3, characterized in that the bars (13) joining together the tubes (12) called intermediate tubes, adopt the shape of substantially plane fins, s' extending radially from said intermediate tubes. Device for cooling the electromechanical equipment of a hydroelectric power station according to one of Claims 3 and 4, characterized in that the various constituent elements of the grid are made of metallic materials, and in particular of steel.