TECHNICAL FIELD The present invention relates to a plant and method for producing electricity from oleaginous plant seeds and fruits.

BACKGROUND ART

As known, the problems related to the availability and cost of the traditional energy sources have made the search for new energy sources, specifically renewable energy sources, more and more urgent.

One of the renewable sources which has aroused considerable interest is that related to vegetable oil as a fuel. The vegetable oil is mostly obtained by chemical extraction from oleaginous plant seeds or fruits, such as for example sunflowers, rape and soy.

DISCLOSURE OF INVENTION

It is the object of the present invention to provide a complete cycle plant capable of producing electric energy by using agricultural products and products deriving from the oleaginous plant transformation.

The object of the present invention is a plant for producing electric energy characterized in that it includes milling means for oleaginous plant seeds and/or fruits, at least one vegetable oil tank, at least one diesel engine connected to a corresponding electric power generator and adapted to use the vegetable oil produced by said milling means as a fuel, at least one fluidized bed combustor adapted to burn the solid- residues from the milling means, a plurality of vaporizers adapted to use the exhaust gases from both said diesel engine and said fluidized bed combustor, and at least one turbine connected to a corresponding electric power generator and adapted to be fed with the steam produced by said vaporizers. According to a preferred embodiment, the fluidized bed combustor is accommodated inside a solar power tower adap.ted to accommodate a solar collector for heating the air to be introduced into at least one of the vaporizers; the plant comprising a plurality of heliostats for concentrating the solar radiation onto the receivers .

A further object of the present invention is a method for producing energy characterized in that it includes a step of milling oleaginous plant seeds and/or fruits, a step of combusting by means of the fluidized bed in which the solid residues from the step of milling are burnt in a fluidized bed combustor, a first step of producing energy in which the vegetable oil produced in the step of milling is used as a fuel in one or more diesel engines connected to corresponding electric power generators, and a second step of producing energy in which the exhaust gases produced during the first step of producing energy and the exhaust gases produced during the step of combusting by means of the fluidized bed are used by one or more vaporizers for producing steam,- said steam being introduced into a turbine connected to a corresponding electric power generator. BRIEF DESCRIPTION OF THE DRAWING

The following example is provided for illustrative and non- limiting purposes, for a better understanding of the invention with the aid of the figure in the accompanying drawing, which schematically shows the plant according to the present invention.

BEST MODE FOR CARRYNG OUT THE INVENTION

In the figure, numeral 1 indicates as a whole the plant object of the present invention.

The plant 1 includes milling means 2 for milling oleaginous plant seeds and/or fruits. Such milling means may consist in a wind turbine connected to an electric power generator, and a mill operated by the energy of the electric power generator.

The plant 1 includes a plurality of vegetable oil tanks, schematically indicated by numeral 3, and adapted to contain the vegetable oil obtained from the milling means 2.

The plant 1 includes a plurality of diesel engines schematically indicated by numeral 4 , each of which is connected to a corresponding electric power generator, also schematically indicated by numeral 5. The vegetable oil is supplied as a fuel to each of the diesel engines 4 by means of a piping 6 which takes the vegetable oil from the tanks 3.

Specifically, at the plant start-up, the diesel engines 4 are only fed by diesel fuel to gradually pass to a diesel fuel/vegetable oil mixture increasingly richer in the latter, until they are fed with vegetable oil alone. As known to a person skilled in the art, the assembly consisting of the tanks 3 and the engines 4 includes an oil heating system, an engine cooling system and a lubrication system, which are neither described nor illustrated because they are known.

The plant 1 includes a plurality of vaporizers, schematically shown by numeral 7, in some of which the exhaust gases of the diesel engines 4 are conveyed by means of a piping 8. Each of the vaporizers 7 includes a water pre-heater and a superheater adapted to generate the steam (both known and not described for simplicity) . The plant 1 includes a solar power tower 9, in which a fluidized bed comfoustor 10 is accommodated and at the top of which a solar collector 11 is arranged. At least part of the fuel used in the fluidized bed combustor consists of ligneous -cellulose biomass obtained as a waste product from the milling carried out by the milling means 2. After being produced by the means 2, the ligneous -cellulose biomass is placed in a storage tank, schematically shown by numeral 12, and then introduced into the combustor by means of a feeding systems, .such as for example a belt.

As known to a person skilled in the art, the fluidized bed combustor has a series of combustion features such as to ensure low emissions and, therefore, a moderate environmental impact. As known, the advantageous, peculiar features of the fluidized bed combustion relate to a large surface for the Combustion and the heat exchange due to the turbulence generated by the fluidized bed, a good contact between the comburent air and the fuel due to the intense mixing generated in the fluidized bed, a great heat capacity of the sand bed in relation to the amount of fuel fed and an optimal combustion of the effluents in virtue of the free space over the bed where the combustion of the gases generated during the process is completed. Specifically, heavy oil, propane or natural gas may be used as a fuel for the ignition, while the sand may be of the river silica type, not crushed and dry, having an average grain size of 0,32 mm.

The residual combustion material, such as the ashes, is mainly withheld in the bed and is removed by means of an extraction system placed at the lower part of the combustion chamber. The ashes are accommodated in a storage container and used for fertilization. The particles, such as particulate, which are carried by the combustion gases are collected in one or more cyclone filters 13. The combustion gases are then conveyed into one or more vaporizers 7 by means of a piping 14.

The solar receiver 11, according to the known art, receives the solar radiation concentrated by a number of heliostats 15. The solar receiver 11 has the task of heating the air, which is conveyed into one or more vaporizers 7 through a piping 16.

The vaporizers 7 are aided by a disposal assembly of the output exhaust gas and by a water feeding assembly, known and not described in detail.

The plant 1 includes a turbine 17 connected to a corresponding electric power generator 18, both schematically illustrated in the figure, and fed with the steam produced by the vaporizers 7 by means of a piping 19. The steam output from the turbine 17 is subjected to the action of a condenser connected to an evaporation tower and returned to the liquid state in the water feeding assembly of the vaporizers 7. The plant object of the present invention is able to use both pure vegetable oil and milling waste as a fuel for energy generating purposes, resulting in producing a high amount of electric energy from oleaginous plant seeds and/or fruits. Such advantage derives from the creation of a process for producing energy from the exploitation of oleaginous plants which determines an efficient, short and self-sustaining supply chain, the technical features of which are such to use different types of machines connected to corresponding electric current generators at the same time, and are able to optimize the use of the two different types of energy sources.

Specifically, such machines are summed up in a solar power tower with heliostat field and solar receiver thereof; a fluidized bed combustor which is an integral part of the tower and is adapted to produce steam from the milling waste ligneous -cellulose biomass; diesel, electricity-generating engine assemblies, adapted to be directly fed with the pure vegetable oil from the mill; steam production assemblies fed by the solar contribution, the fluidized bed combustor and the engine exhaust fumes; and a steam turbine with a specific electric generator.

Specifically, the presence of the solar collector in the solar power tower offers the advantage of exploiting the solar energy integrated in the biomass and therefore compensating transients and day/night cycle. Furthermore, the plant consumes less biomass in proportion to the solar energy contribution, the energy production being equal .

Finally, the combustion ashes in the fluidized bed of the ligneous-cellulose biomass combustion may be used for fertilizing the oleaginous biomass cultivation fields .