Fuel and related compositions – Liquid fuels – Emulsion fuel
Reexamination Certificate
2001-06-11
2003-01-07
Toomer, Cephia D. (Department: 1714)
Fuel and related compositions
Liquid fuels
Emulsion fuel
C516S022000, C043S002000
Reexamination Certificate
active
06503286
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a combustible composition in the form of an emulsion, to a process for its production from heterogeneous fatty waste and to a combustion process using this combustible composition.
BACKGROUND OF THE INVENTION
Organic waste such as that from the agro-food industry (meat flour, viscera, etc.) are characterized by a moderate gross calorific value but cause enormous problems with combustion, in particular because of their substantial heterogeneity.
Thus when supplying combustion apparatus with such waste, the heterogeneity of the waste renders it difficult to manipulate and combustion regulation is hazardous. Combustion furnaces supplied by that type of waste are subjected to substantial and rapid variations in calorific value: such a modus operandum is technically unacceptable for a conventional combustion facility.
Further, because of the heterogeneity of the waste, the combustion furnace can come into contact with either a fraction of waste with a very high volatile matter content or with a waste fraction which is depleted in volatile material. Whatever the case, combustion causes problems: in the first instance, combustion is very rich and the temperatures reached in the furnace cause material resistance problems; in the second case, combustion is poor and results in residues and unburned material.
SUMMARY OF THE INVENTION
The present invention aims to overcome the problems mentioned above.
In particular it aims to provide, from heterogeneous fatty organic waste, a stable homogeneous combustible composition in the form of an emulsion. It also aims to provide a process that can easily produce such a combustible composition. It further aims at providing a combustion process which has none of the disadvantages observed during combustion of untreated fatty waste.
DETAILED DESCRIPTION OF THE INVENTION
In general, the combustible composition of the invention consists of a water-in-oil and/or organic compound emulsion, which is homogeneous and stable, formed from heterogeneous fatty waste and further containing solid particles in suspension.
In the combustible composition of the invention, the water is in the form of droplets dispersed in the continuous phase, which is an organic phase or a fatty phase.
It should be noted that, in terms of combustion, an emulsion of water in an organic material is more interesting than an emulsion of an organic material in water, as if the continuous phase were water, sufficient energy would have to be added to the combustion apparatus to evaporate the water surrounding the organic material before triggering combustion, while if the continuous phase were the organic material, it would be sufficient to supply energy to reach the ignition temperature of the fatty phase to trigger combustion: in the solution recommended by the invention, the heat released on combustion is used to evaporate the water contained in the composition.
Depending on the nature of the fatty waste treated to prepare the combustible composition of the invention, the distribution by weight between the different constituents can be as follows:
10% to 60% by weight of water;
10% to 60% by weight of fats; and
1% to 80% by weight of solid matter.
A preferred weight distribution is:
10% to 55% by weight of water;
15% to 45% by weight of fats; and
3% to 75% by weight of solid matter.
The solid matter generally contained in the combustible compositions of the invention are generally in the form of pieces with relatively homogeneous sizes with their largest dimension of 10 cm or less, preferably 2 cm or less and more preferably, 1 cm or less.
The combustible compositions of the invention generally have a net calorific value (NCV) of at least 6000 kJ/kg, preferably at least 10000 kJ per kilogram.
In general, production of the combustible compositions of the invention comprises two principal operations:
a) reducing the granulometric heterogeneity of the waste; and
b) forming an emulsion by agitation, and optionally adding an emulsifying agent.
The two operations can be combined into a single step or dissociated into a plurality of steps carried out in succession.
More particularly, the starting fatty waste can consist of all sorts of waste from the agro-food industry, animal flour, waterfowl viscera, etc.
By way of indication, the proportion of fats in animal flour is generally 10% to 35% by weight. This proportion can, for example, be 20% to 40% by weight in viscera. In these, the proportion of water can, for example, be 35% to 55% by weight.
To reduce the heterogeneity of fatty waste, it is subjected to a homogenisation operation (a) termed a “dynamic homogenisation operation” which can, for example, consist of shredding, grinding, chopping or any other operation enabling the size difference between the various solid components of the waste to be reduced. This operation can be carried out, for example, in a grinder, a chopper or any other apparatus that can shear the fatty waste pieces. The operation can be carried out in batches or continuously.
As already indicated above, the granulometry which is to be obtained can correspond to particles with a variety of shapes, the largest dimensions of which can be 10 cm or less, preferably 2 cm or less, and more preferably, 1 cm or less.
The temperature at which homogenisation is carried out is generally less than 70° C. and preferably less than 55° C., for reasons which will be given below.
Emulsion formation or structure homogenisation (operation (b) in the production process of the invention) is carried out by agitating the fatty waste after or simultaneously with operation (a) carried out above.
The water in the emulsion composition constituting the dispersed phase can originate from the treated organic waste. It can also be water added during the emulsion formation step. In general, it is preferable not to add water.
The emulsion is formed by agitation and optional addition of an emulsifying agent which is preferably soluble in the organic (or fatty) phase. Compounds with a low hydrophilic/lipophilic balance (HLB) are selected. This balance, which represents the relative weight of the fatty chain of the molecule to the solubilising group, is in the range 2 to 8, preferably in the range 3 to 6.
Groups of emulsifying compounds encouraging the formation of an emulsion of water in the fat include ethoxylated or propoxylated alcohols, fatty acids or esters, amines or amides with high molecular weights. Preferably, higher fatty alcohols are selected, such as sterols or polyglyol mono- and di-esters with a short polyglycolic chain.
The amount of such emulsifying compounds with respect to the overall weight of the liquid mixture, fat plus water, will be in the range 0.5% to 5% by weight and preferably 1% to 3% by weight.
Sulfonated or sulfated oil type emulsifying agents can also be used, but during combustion they liberate non-negligible quantities of oxides of sulfur.
Pairs of emulsifying agents, with different behaviours when taken separately can, when they are associated in suitable proportions, lead to stable water-in-oil emulsions. Examples that can be cited are higher alcohol esters mixed with quaternary ammonium salts.
In a preferred version of the invention, the emulsifying agent is produced in situ by adding to the waste traces of a base generally consisting of an alkali or alkaline-earth metal hydroxide such as sodium, potassium, calcium or magnesium hydroxide, after or during granulometric homogenisation.
Fatty waste contains traces of free fatty acids and also undergoes partial hydrolysis, which liberates fatty acids and alcohols (in general glycerol). As a result, adding an alkaline or alkaline-earth base causes neutralisation of the acids and the formation of alkaline or alkaline-earth soaps, which act as emulsifying agents during emulsion preparation.
If the organic fraction contained in the waste is represented as being in the form of triglycerides, the reactions can be schematically represented as follows:
The hydrolysis reaction is encouraged by raising the temperature, so it
Collin Jean-Claude
Flament Patrick
Hendou Mouloud
Lacaze Pierre
Institut Francais du Pe'trole
Millen White Zelano & Branigan P.C.
Toomer Cephia D.
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