Field of the invention

The present invention refers to the technical field of alternative and renewable energy production and in particular it refers to torrefied biomasses/peat and apparatuses and methods of handling and delivering torrefied biomasses/peat. State of the art

It is known that a huge amount of biomass and peat is potentially available, for energy and industrial utilisation, from a wide range of agro-forestry residues, wastes, energy-crops, peat fields. According to the EU, the long-term biomass potential is estimated at 600 MTOE / year (Million Tons of Oil Equivalent per year) with a large share obtained from low-quality agro-forestry residues.

New, high energy efficient technology for the production of so called "agro pellets" - which are pellets energetically and physically similar to conventional wood pellets, but obtainable from any type of agro-forestry residues, wastes or mixtures thereof - is based on the fact that most of the moisture content of said agro- forestry residues is eliminated mechanically and not thermally. This technology is already able to allow the direct pelletising of very humid biomasses / peat, and it will allow, in the near future, the production of a very large volume of lower-quality agro-pellets that will soon be available on the market for trading and delivery to biomasses based power plants and factories.

A large fraction of said very large volume of lower-quality agro-pellets will then very likely be processed by torrefaction. In fact, torrefaction will have a benefit homogenisation effect in that the final torrefied products (in form of chips, pellets or granules), coming from different types of biomasses including low-quality biomasses, will acquire very similar energy characteristics.

Therefore, it's easy to envisage that in the near future as already being anticipated a very large volume of torrefied agro-pellets, obtained with biomasses, peat, or their mixtures will be made available because of their many good qualities as solid-refined bio fuel: lower emissions, higher volumetric energy density, improved homogeneity, low moisture content, hydrophobicity, easy grindability, etc. As an obvious consequence of said increasing availability of large quantities of torrefied agro-pellets(peat/biomass) a corresponding growth of international trading of said torrefied agro-pellets is to be expected due to the worldwide increasing use of Bio-Heat (district heating), Bio-electricity (cofiring with coal, cogeneration), Biofuels for transportation and Biochemicals.

The handling, transportation and logistics connected to the delivery of large volumes of torrefied biomasses and peat will thus become a very important and challenging activity, requiring considerable infrastructures and investments, like it happens today regarding coal and petroleum. It's therefore an object of the present invention to provide a new apparatus and a new method for handling transportation and supply of torrefied biomasses and peat, in particular in the form of agro-pellet

Summary of the invention

The method according to the present invention exploits, in particular, the high hydrophobicity of torrefied material. In fact, torrefied materials show, at normal equilibrium conditions, a low moisture rate of 3-4% in weight and they do not absorb water even when immerged in water for periods of time as long as many days or months. According to the present invention, the hydrophobicity of torrefied material is not only exploited for low-cost outside storage, but also for low-cost handling, charging, discharging, transportation and supply of torrefied small size biomass and/or peat (in form of chips, pellets, granules etc.) by mixing the torrefied materials with a liquid (like water, slurry - which is made of torrefied powder mixed with water - vegetal oil, exhausted vetegal oils, biethanol and others liquid biofuels), and pumping the torrefied solid-liquid mixture to the remote storage / handling, utilisation site, where the separation of the solid matter from the liquid vessel will be carried out to make the original high value of the refined solid biofuel thus available for its efficient use.

Brief description of drawings

Fig. 1 describes a schematic block diagram of a preferred embodiment of the apparatus for the delivery of torrefied small biomass and peat material according to the present invention. Fig. 2 describes a schematic diagram showing preparation of "slurry" as a transport fluid.

Fig. 3 describes a schematic diagram showing a possible layout of a torrefied biomass/peat charging system.

Fig. 4 describes a schematic diagram showing a possible layout of a torrefied biomass/peat discharging system.

Detailed description of the invention

Method and apparatus for handling transportation and supply of large amount of torrefied biomass and peat material in form of pellets, granules, small-chips and powder.

It is well known that torrefied materials show, at normal equilibrium conditions, a low moisture content rate of 3-4% in weight and do not absorb more water even when immerged in water for periods of time of several days or months. Tests carried out on torrified pellets - having diameter of 6 to 8 mm and specific density of about 1 .2 gr/cm ³ - completely immersed in water for a long period of time (150hr and more), show that the water absorption of said torrified pellets is neglectable and they show no sign of disintegration or physical deformation. Further trials demonstrated that after a 6 months immersion period, in water 6mm diameter torrefied pellets absorbe nearly 0% of water, maintaining the same mechanical/physical characteristics. Because of this important quality, torrefied pellets, granules, small-chips etc. can be mixed with a fluid, like e. g. water or slurry, acting as fluid-dynamic transport means, and efficiently pumped and delivered - with a capacity ranging up to hundreds of tons per hour and more - to the utilisation site where easy separation of the refined solid material from said fluid can be easily carried out by state of the art well known systems to restablish the original high value biofuel making it available for a prompt use.

Torrefied biomass or peat material, in particular in form of "torrefied pellets" obtained by direct torrefaction treatment of crude pellets - e.g. by large scale process of conversion adaptable for very large production capacity (i.e; 1 , 2, 3 million tons/year or more) - represent a promising new solid biofuel and even a promising new commodity of large potential use and great economic and environmental interest. Considering the improved characteristics of the torrefied materials in comparison with the original feedstocks, higher heating value, higher volumetric energy density, hydrophobicity, better grindability, lower emissions, etc. two aspects appear of particular interest for large-scale utilisation of torrefied biomass or peat: the homogenization of the refined product, even when obtained from different feedstocks, and the Hydrophobic nature of torrefied materials.

The homogenization of the refined product induced by the torrefaction refining process will have a strong beneficial effects on the deployment and enlarged use of all types of biomasses available, with special reference to the large amounts of agro-pellets potentially widely available, ( first of all obtained from every type of agro-forestry residue) the quality of which can be considerably improved through torrefaction (low water, low oxygen and low chlorine content).

The hydrophobic characteristic of torrefied materials like biomasses and peat that allow also important benefits for long-term outside storage and for the logistics like handling, charging, discharging and transport and can be exploited, according to the present invention, by mixing the torrefied fuel with a fluid like e.g. water or slurry and pumping the mixture of the transport fluid like water or torrefied material to the final storage/utilization sites, .where separation from the water is carried out to restablish the original biofuel.

With reference to the enclosed figure 1 , a preferred embodiment of the apparatus according to the present invention comprises means 1 1 for producing a mixture 15 of small torrefied particles 10 like pellets, granules, small-chips, powder and the like obtained by biomass and peat and a liquid transport fluid 16 like, e.g., water, means for pumping 12 said mixture 15 along a suitable pipeline 14 adapted to deliver said mixture 15 at a required distance, means for separating said mixture 15 into said torrefied small particles 10 and said liquid transport fluid 16.

Said small particles 10 are made of torrefied material, said means for separating said mixture 15 into said small particles 10 and said liquid fluid vessel 16 comprise a rotating screen, a trommel screen, a simple sifter or similar device, said means for pumping 12 comprise pumping systems for solid-liquid mixtures of the type normally available on the market and in particular centrifugal pumps with very large delivery capacity and said suitable pipeline 14 comprises plastic material pipes.

In a preferred embodiment, in order to save and re-use the said transport liquid, said suitable pipeline 14 comprises a closed loop pipeline.

In a further preferred embodiment of the present invention, , said suitable pipeline 14 comprises a single pipeline with a bidirectional pumping means.

For the transport of torrefied material, said liquid transport fluid 16 comprises water or slurry. Also sea water can be advantageously employed. Other suitable transport liquid fluids can be chosen in the group of liquid transport biofuels comprising vegetal oil, exhausted vetegal oil, biethanol, etc., depending on the solid refined material to be transported.

The apparatus and method according to the present invention will be suitable for charging and discharging torrefied solid fuel, in the form of pellets, granules, small- chips, powder and the like, in and from trucks, trains or ships and for supplying said solid torrefied refined biofuel to power plants and conversion plants.

The logistics correlated to the apparatus and method according to the present invention is very similar to the logistics regarding heavy oil handling and distribution due to the fact that the small torrified material(pellets, granules, small- chips) are temporarily transformed into a solid-liquid mixture easy to be efficiently pumped and finally separated into the liquid vessel (preferably water) plus the small particles to recover the torrefied material with the original characteristics.

The method and apparatus according to the present invention can be adapted to deliver small torrefied material like pellets, granules, small-chips etc. to wide distances range, up to several hundreds of kilometres and it will be able to match future large scale trading and diversified torrefied material demand (biomass/peat) all over the world.

Some very important side effects are connected to the use of the apparatus and method according to the present invention: the actual constrains situation of ports will be improved by reducing the quantity of goods which are received and stored at the port facility; in fact, the mixtures of small torrefied material and water can be pumped directly from ships through underground pipeline to low-cost storage sites away from the very expensive storage locations within the port area with obvious benefits in terms of reduction of the port activity congestion, cost reduction of the storage in the port of the fuel waiting to be delivered to its final destination and reduction of the operating time and cost connected to the charging and discharging of the torrefied materials.

The method according to the present invention will allow huge amounts of highly refined torrefied biomass / peat material - that could become a new recognised commodity ("Torrefied Agro-pellets") of universal value.

For example: In the contest of a future international large scale trading, three situation exploiting the present invention can be envisaged:

1 ) Long distances transportation from internal torrefaction plants to port charging/discharging sites

2) Charging and discharging operations on cargos away from congested port areas as already explained above.

3) Delivering large amount of torrefied material from large storage to the utilisation/conversion sites.

. Torrefied agro-pellets may represent thus a vital resource for a more friendly production of Energy and Chemicals world wide, progressively replacing oil, natural gas and coal.

Considering as an example a mixture comprising water at 70% in weight and torrefied pellets at 30% in weight and a moderate speed of transfer of about 1 m/sec (3.6 km/h) inside the pipeline: in 150 hrs time, the mixture will cover a distance of about 450Km with no energy density loss for the delivered torrefied materials (biomass - peat) once separate from the water, and with a very low energy consumption for their transport, due to the low energy input required for pumping mixture with specific density higher than 1 gr / cm ³ . To achieve the above result with the delivery of 1 million tons of torrefied pellets per year (equivalent to about 125 tons of torrefied pellets per hour) and considering the above example of mixture (water at 70%, torrefied pellets at 30%), the required volume transfer through the pipeline is about 350 m ³ /h = 0.097 m ³ /sec. Choosing a simple pipeline in plastic material with an internal diameter of 35cm (0.09 m ² ), the speed of transfer of the mixture corresponds to about 1 m/sec. According to the present invention, mixtures characterised by a ratio in weight between said small particles and said transport liquid in the ranges from 20% to 60% and more (preferentially above 30%) can be easy delivered.

The major and typical applications connected to the present invention can be summarised by the following: 1 ) the replacement of old type conveyor systems such as mechanical belt or screw-conveyors for the transfer of solid biomass; 2) the replacement of large scale road transport & distribution network in congested urban and suburban areas by pipelines and pumping /separation systems; 3) the replacement of mechanical torrefied biomass/peat supply systems to power-plants or conversion-plants with large delivery of torrefied materials (pellets, granules, small chips) that can easily reach 0.5 -1 million tons /year and more; 4) the replacement of conventional charging and discharging operations (i.e. to and from cargo ships and the like) of torrefied material, with systems for the pumping of solid / liquid mixtures through underground pipelines up to the storage site located outside the port area, to avoid the high storage costs in the port, the road congestion around the port area thus reducing local air pollution. When a liquid bio fuel is employed as transfer liquid the final separation phase between the solid bio fuel and the said liquid may not be required in some cases because the produced solid / liquid slurry could be directly used for the combustion/conversion purpose.