Run-of-River, Marine and Tidal Streams

"Under Water System comprising a Cylindrical Symmetry Duct with Hydroreactor Profile"

Application:  To be Installed at relative depth places on estuaries, big rivers or sea where the streams may change direction and way of flow and where marine traffic may exist

Table of Contents:

Description of the Technology

Representation

Advantages

Description of the Technology

This technology comprises a cylindrical symmetry duct with hydroreactor profile that stands immersed in the streams, at some depth bellow the water surface, attached to an elevating platform by means of a bearing device, the platform connected by means of an extensible part to an inert base anchored at the riverbed or seafloor.

The inside duct channel is formed by an inlet converging zone of compression, an intermediate zone of narrower cross section (gorge) where flow loading is significantly higher than the outside free stream loading and finally by an exhaust diverging zone where a suction effect is generated by diffusion of the inside flow and deflection of the outside stream nearby the channel outlet.  

The duct edge if defined by a quadratic decrease of the channel diameter and by a soft quadratic increase of the duct external surface diameter at the inlet converging zone, a minimum constant channel diameter at the intermediate zone where the channel is narrower (gorge), an initial accentuated increase and almost null final increase of the channel diameter at the outlet diverging zone, and slight linear decrease of the duct external surface diameter with same inclination at intermediate and outlet diverging zones.

The general dimensions of the cylindrical symmetry duct with hydroreactor profile can be taken with relation to the diameter dt of the channel at the narrower zone, being: the maximum diameter de of the duct external surface about 4.5 times higher than dt and the duct length about 7 times higher than dt.  

The duct has one helm being autonomously orientated according the streams direction and way of flow, without the need to expend any external power, allowing to take the maximum profit from marine an tidal streams.

A Selective Grid stands attached to the duct, located immediately before the channel inlet, to avoid the entrance of objects bigger than a specific size in the channel.

In the narrower channel zone works a low head (low pressure/high speed) axial flow turbine that drives by means of a transmission device a low rpm generator housed in one impervious chamber located at the duct edge.

The location is signaled by a floating buoy, connected by means of a cable with some allowance to the duct. The buoy keeps two pipes for air circulation through the generator housing chamber, both with one of the ends always above the water surface connected to the buoy and the other end connected to the generator housing chamber.

Maintenance is performed outside of water from an embarkation anchored with a rigid rod to the riverbed/seafloor, lifting the duct above the water surface. The platform has a weight that enables autonomous diving of the duct and shrinking of the extensible part after maintenance. At most of the time the extensible part remains shrinked, expanding only for maintenance proposes.

The generated electrical power is transmitted by electrical cables lied on the riverbed of seafloor to a central station at the coast or river sides, where electrical power storage and conversion is performed. The electrical cable comprises two parts connected together by a sealed rotating union nearby the duct, to avoid cumulative torsion and consequent rupture.  

 

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Representation of the Technology:

 

Impeller

 

Legend:

1 - cylindrical symmetry duct with “hidroreactor” profile

2 - selective grid at the duct inlet to avoid entrance objects bigger than a specific size

3 - elevating platform to which the duct is attached by means of a bearing device

4 - Inert base anchored to the riverbed or seafloor

5 - Selective grid at the duct inlet to avoid entrance objects bigger than a specific size

 

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Advantages:

Use of a highly efficient stream accelerator of optimized profile "Hydroreactor", that introduces a significant net head creating a flow of higher loading than the stream, promoting the extraction of power from streams on a higher number of sites.

The duct has an helm being autonomously directed according the streams direction and way of flow, without the need to expend any external power, allowing to take the maximum profit from marine an tidal streams.  

The duct stays at some depth bellow water surface being is position signaled with a buoy connected with some allowance to it, not causing any barriers to marine traffic.

Maintenance can be easily performed outside of water from a embarkation anchored with a rigid rod to the riverbed/seafloor, lifting the duct above the water surface.  

Use of an inert base anchored to the riverbed/seafloor dimensioned properly, avoiding the construction of  foundations.

Installation/de-installation are not complicated being almost all of the operations performed outside of water from a embarkation anchored with a rigid rod to the riverbed/seafloor.

The present technology does not offer barriers to the migration of species in inlets and estuaries, as in the case of the construction of dams. The entrance of fish and objects bigger than a specific size into the channel, is avoided with the use of a selective grid that stands attached to the duct edges, immediately before the channel inlet. 

The conversion of mechanical to electrical power is performed locally at the place of profit minimizing the mechanical energy losses before turbines.

 

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