Field of the invention

The invention relates to the method of incineration of glycerol and glycerol mixtures coming mainly as liquid waste and to the design of suitable atmospheric evaporation burner. The invention comes under the topic ecological utilization of liquid glycerol wastes and by-products of chemical production.

Background of the invention

The disposal of liquid industrial wastes, including wastes associated with the production of biodiesel - the so-called G-phase, consisting mainly of glycerol has become a problem.

Trans-esterification of TAG found in vegetable oils or animal fats gives rise to 12 - 15 % of raw glycerol. It is a natural by-product, requiring additional processing before further use. The purity of raw glycerol can be 50 to 60%, depending on starting materials and technology used. Accordingly, the raw glycerol phase formed during manufacturing of biodiesel contains 52 to 58 % glycerol, 21 to 23% methanol, 1 to 2% water, 4.2 - 4.8% potassium hydroxide and 15 to 23% of fats. The raw glycerol phase - GVS arising during manufacturing of rape oil methyl ester is on the one hand supplied for further processing by suitable chemical and separatory procedures to pure glycerol, on the other it is also offered as an alternative fuel. Its direct use involves either co-burning or use in production of cement.

However, burning glycerol waste in standard incinerator units is difficult, since without additives it does not burn in classic burners. Glycerol can be incinerated only if other flammables and additives are added. Experiments towards improving the burnability (professor Cvengros ^" - Difficulties of burning G-phase and raw glycerol - APROCHEM 2008) were made showing that G-phase, when mixed with light fuel oil in the ratios 4: 1 to 1 : 1 could not be ignited, even in the Kroll burner, type KB/UB 200. Attempts to burn the 1 : 1 mixture of G- phase and vacuum distillate (V02) with an addition of detergent too met with failure, since the burning process remained unstable. Industrial scale experiments involving incineration of fuel oil mixed with G-phase containing some methanol in a monoblock Kroll burner, modified for burning processed waste oils were carried out. It turned out, that the G-phase could be burned provided the burner was started with the fuel oil and later switched to the G-phase + fuel oil mixture. The necessary prerequisite however seems to be the preheating of G-phase in order to lower its viscosity. However, the use of detergent, facilitating the mixing of fuel oil and glycerol, is demanding, both physically and economically.

In view of the above described difficulties a solution was sought for incineration of raw glycerol or glycerol wastes without additional flammables and oxidizing substances and without the need of complicated spraying burners.

As a result we now present the method of incineration of glycerol or glycerol mixtures, as well as the design of the requisite atmospheric evaporation burner.

Summary of the invention

The present process of burning glycerol and glycerol mixture as well as requisite new design of burner remove the above described shortcomings, the gist of the invention being feeding the liquid waste, such as glycerol or mixtures containing glycerol to an atmospheric evaporation burner, equipped with organized or non-organized porous and/or filamentous material with heat conductivity λ = 1 to 430 W.m ^"1 . K ^{" 1} . The glycerol is evaporated from the surface of the hot evaporation burner. It is essential that the mass or material of the atmospheric evaporation burner be soaked with glycerol or glycerol mixture. There are various ways to achieve this objective. One example can be the use of burner tray containing the evaporation material itself, whereby liquid glycerol or glycerol mixture is fed into it. Successful burning requires that the porous/filamentous mass or material not be totally submerged in the liquid.

The process of burning glycerol and glycerol mixtures according to this invention has been developed for raw glycerol mixtures such the wastes formed during the production of biodiesel - the so-called G- phase, but also for burning of pure glycerol.

The method of incineration of glycerol or glycerol mixture according to this invention involves the use of atmospheric evaporation burner, the key design feature of which is the use of organized/non- organized porous/filamentous matter or material with heat conductivity λ = 1 to 430 W.m ^"1 .K ^"1 . The burner is advantageously made wholly or partly of metal. Thus atmospheric evaporation burner can consist of steel wool as filamentous non-organized material. The burner can just as well be formed of organized e.g. copper filaments. Another embodiment of the burner can use organized structure of metallic and inorganic filaments. In yet another embodiment the atmospheric evaporation burner is formed of porous inorganic matter.

For the purpose of this invention it must be understood that the term "atmospheric evaporation burner" represents a design element or simple device for gasification of the fuel and supporting the burning of the generated vapours.

The advantages of burning glycerol and glycerol mixtures according to this invention as well as the design and material of the atmospheric evaporation burner itself become apparent from the way the burner operates. It principal advantage is the simplicity of its design.

By using the above described materials flammable vapours are generated at the surface of burner without the need for forced air circulation, evaporation taking place at the high-surface area of the burner material, soaked in the fuel. Another important aspect is safety of the burning process. Overview of drawings

The design of the atmospheric evaporation burner for incineration of glycerol and glycerol mixtures according to this invention will be elucidated on attached drawings, where Figure 1 shows the technical design of a partly submerged atmospheric evaporation burner in burner tray with glycerol inlet. Figure 2 shows the design of the glycerol inlet itself, a fixture bringing glycerol directly to surface of the atmospheric evaporation burner.

Examples of various embodiments

It is understood that the individual embodiments of the technical design serve only illustration purposes without any limitations. Specialists skilled in art should be able to find by nothing more than a routine experimental work many equivalent solutions to the embodiments described here. Such equivalent solutions too are to be included in the patent claims.

Specialists skilled in the art should have no problems to select the scale of equipment as well as construction materials and arrangements, so that here we refrain from giving such details.

Example 1

This example shows an embodiment of the invention involving one method of incineration of glycerol or glycerol mixtures according to this invention as well as an atmospheric evaporation burner, which is part of the solution. In this embodiment glycerol or glycerol mixture is fed into the inlet 1 of the atmospheric evaporation burner 3^ made of non-organized filamentous material with mean heat conductivity λ = 45 to 47 W.m ^"1 .K ^"1 . At the hot surface of atmospheric evaporation burner the fuel is first converted to vapour and then the glycerol and other vapours are burned in atmospheric oxygen 2, as shown on Figure 1 . The material in this embodiment of the atmospheric evaporation burner 3 was steel wool. The technical design of the atmospheric evaporation burner 3 involves the use of an approx. 3 cm thick strip of steel wool, laid into the burner tray 4. Glycerol or glycerol mixture is fed in a controlled manner into the tray inlet 1, as shown on Figure 1 . Capillary forces transport the glycerol up to the surface of the material, making it ready to be ignited by e.g. liquid starter. After the glycerol has been ignited, the steel wool surface heats up and owing to its high heat conductivity the heat is transferred from the surface of burner 3 into its inner structure, thus leading to more evaporation of glycerol to be burned above the surface of the atmospheric evaporation burner 3. An alternative design involves fuel flowing through inlet 1 directly at the surface of the atmospheric evaporation burner 3, as shown in Figure 2.

Example 2

In this embodiment of the invention we describe the second method of incineration of glycerol or glycerol mixtures according to present invention. Now glycerol or mixtures containing glycerol are fed into the atmospheric evaporation burner 3 formed by organized filamentous material (copper mesh) with heat conductivity λ = 386 W.m ^{" 1} .K ^"1 . At the surface of atmospheric evaporation burner 3 glycerol is first evaporated and then the vapours ignited and burned in atmospheric oxygen. One embodiment of organized filamentous material, used in atmospheric evaporation burner 3 can be e.g. a plaited wick made of copper wires of 0.02 to 0.08 mm diameter. The technical design of the atmospheric evaporation burner itself uses e.g. a cut piece of copper plaited wick with 20 cm width, piled up in pleats to a height of approx. 1 cm, and fixed in a supporting body. Atmospheric evaporation burner 3 can alternatively be made of mineral fibres or fabric or of porous inorganic matter. Industrial utility

Method of incinerating glycerol or glycerol mixtures according to this invention finds application mainly in burning of otherwise nonflammable liquid glycerol wastes.