WO2011127869A1

WO2011127869A1 - Method for processing of a mixture of waste substances containing glycerol as a prevailing component

Info

Publication number: WO2011127869A1
Application number: PCT/CZ2010/000048
Authority: WO
Inventors: Alois Vasicek
Original assignee: G.F. Agro A.S.
Priority date: 2010-04-15
Filing date: 2010-04-15
Publication date: 2011-10-20

Abstract

It is a method for processing of a mixture of waste substances containing glycerol as a prevailing component in which at first the mixture is deoxidized using a catalytic- reduction agent with co-acting of an external field, producing the main components - methane and carbon dioxide with subsequent partial oxidation of methane to methanol. The methanol produced is used e.g. as a entering product for oil re- esterification.

Description

Method for processing of a mixture of waste substances containing glycerol as a prevailing component

Technical Field

The invention relates to the method for processing of a mixture of waste substances containing glycerol as the prevailing component, in particular recycling of waste glycerol phase from the rape-seed oil methyl ester production.

Background Art

Lots of chemical manufactures produce various amounts of more or less chemically contaminated waste glycerol which is not economic to be further processed.

The waste glycerol contains usually various amounts of water (up to 50 wt %) and various amounts of other waste materials, whereas owing to prevailing technologies such as processing of fats, oils or related substances a waste glycerol mixture contains in particular substances of basic character such as alkaline salts or hydroxides.

Over the last years, considerable amount of glycerol waste forming in the technology of alternative production of fuels for combustion engines is produced whereas the current situation in the market of fuels for motor vehicles have brought to the market an alternative fuel in the form of rape oil methyl ester.

This fuel is produced from vegetable oils by way of re-esterification. In this process triacylglyceride of fatty acid is converted to methyl ester of the respective fatty acid using methanol. 15 - 20 % of the product, containing 70 - 80 % of glycerol wastes off the reaction, the rest being water and reaction admixtures after separation from the main product, the rape oil methyl ester. A state-of-the art method of processing of the waste product is based on receiving of pure glycerol which is further treated for acrylaldehyde or epichlorohydrin. Ho wever, the process of purification of the glycerol phase to technical-pure anhydrous glycerol is not a cheap one. Excess of glycerol in the market causes fall of its value needed for purification. This is the reason why producers of the rape oil methyl ester often have to dispose of excess of the glycerol phase which consequently increases their costs. On the other hand, the producers often buy methanol for their own production the price of which also affects the price of the outgoing raw material. Regarding the state of the art the producers of methyl esters from vegetable oil are not able to influence the present state owing to technology.

Disclosure of the Invention

The drawback of the state of the art as for the raw-material and production balances of the above-mentioned technologies eliminates substantially Method for processing of a mixture of waste substances containing glycerol as the prevailing component. It involves the following steps:

a) deoxidization of the above-mentioned mixture with a catalytic-reduction agent and combined action of external field leading to formation of the main components - methane and carbon dioxide;

b) partial oxidation of methane to methanol.

Preferably, a step al) in which produced methane is separated from carbon dioxide is carried out before the partial oxidation of methane in the step b).

Mixtures of waste substances containing glycerol may have various composition and dilution. For the method according to the invention the preferable waste mixture is the glycerol phase of the rape oil methyl ester production. The method of processing of methyl esters of the respective vegetable oils eliminates considerably the recycling method of the glycerol phase of these productions according to the invention in which methanol is recovered from the raw waste phase.

According to the present invention it is also preferable if the external acting field during deoxidation is heterogeneous electric and magneto-electric field, whereas it is more preferable if heterogeneous electric field is generated by pulsed high-frequency current combined with low-frequency or direct current.

In more convenient preferable embodiment the above-mentioned mixture of waste substances passes an electric field in the full range of electric current 30 to 400 A with co-acting of pulsed high-frequency current of resonance bands of oscillation from 100 Hz to 100 kHz resulting in corona of cold plasma with a temperature between 700 °C to 2100 °C, and simultaneously a circular magnetic field forms the outside edge of which covers the space of the cold plasma formed in the process. According to the present invention elementary carbon is a convenient example of a catalytic-reduction agent which can be preferably coke, anthracite, graphite, carbon black or charcoal or their mixture, and the range of size of carbon particles is preferably 5 to 50 mm. . ;^' ·.,

The most preferable embodiment involves, according to the invention, coke as the elementary carbon.

Surface of elementary carbon is in the preferable embodiment treated with deposition (adsorbing) of organic and/or inorganic substances/compounds containing iron, chrome and copper ions. The deposition is performed via immersion the particles into aqueous solutions or suspensions containing the substances.

One of the most preferable embodiment is if the inorganic particles adsorbed on the elementary carbon is iron(III) oxide in the case of iron compounds, copper(I) oxide in the case of copper compounds, or adsorbed aqueous solution of iron(III) and chromium(III) salts.

It is also preferable if the step of separation of methane from carbon dioxide is performed specifically using a hydroxide or hydroxide mixture, with calcium hydroxide-Ca(OH)₂ being the most preferable one, particularly in the form of lime milk.

In the method according to the invention the step b) partial oxidization of methane to methanol is realized preferably using the following sequential steps

i) mixing methane with the oxidization gas in a stoichiometric ratio producing a gaseous mixture;

ii) contact of the passing stream of the above-mentioned gaseous mixture with electrical resistance conductor heated to a temperature up to max. 850 °C;

iii) condensing of vapours of the methanol formed.

Preferable oxidization gas for partial oxidization is air and/or oxygen whereas the rate of passing stream of gaseous mixture is in the range from approx. 0.1 to 1 m/s.

The subject of the invention is also a device for performing of partial oxidization of methane to methanol; it comprises a catalytic oxidization reactor consisting of at least one tube of electrically non-conductive material through the centre of which an electric resistance conductor passes connected outside to a source of electric current with feedback regulation.

As an electrically non-conductive material of the tube glass or ceramics are used preferably.

A preferable embodiment according to the invention is the embodiment in which the electrical resistance conductor is made of iron, whereas another preferable material of an iron, nickel and chromium can be used.

Brief Description of the Invention

The method according to the present invention involves two main technological steps. In the first step, the deoxidization step, to which raw glycerol containing waste mixture of glycerol and minor amount of other waste substances enter, glycerol is deoxidized using a plasma reactor with reduction filling controlled by an electric field, with production of two main products of the reaction - methane and carbon dioxide. The controlling non-homogenous electric field leading the reaction develops in the space between electrodes in which the catalytic reduction filling is also placed; the filling consists of particles containing in their composition carbon selected from the group of materials containing coke, charcoal, anthracite surface of which is preferably treated with deposition of substances containing chromium and/or iron and/or copper. The deposition is performed via immersing the particles in aqueous solution or suspensions containing the substances.

The electrodes are connected to a source of electric current. Electric current in the space between two electrodes passes in a regime of co-acting low-frequency current of 30 to 400 A and high-frequency current in resonance bands of oscillation from 100 Hz to 100 kHz. Such a generated electric field activates the filling between electrodes so that coronas of cold plasma having the temperature of 700 °C to 2100 °C form in between the particles of the reduction filling of the reactor. While the glycerol phase passes through the π^ίμιη it is immediately decomposed to methane and carbon dioxide, whereas the reduction filling of the reactor is also involved in stoichiometry of this reaction. The products having average temperature between 350 °C and 550 °C go from the reactor to a cooler in which they are cooled to a temperature under 30 °C and then continue to the room of gas purification in which the mixture of methane and carbon dioxide is counterflown with hydroxide solution/solutions, preferably

Ca(OH)₂, and a main part of carbon dioxide is removed. Methane, which is produced in the reaction, enters in the second technological step, partial catalytic oxidization where it enters in a blending equipment at first in which it is mixed with air in a stoichiometric ratio of partial oxidization and then the mixture is led to the catalytic oxidization reactor which consists of parallel tubes made of electrically non- conductive material, preferably glass or ceramics, with a diameter of 8 to 15 mm. Through the centre of the tubes an electric conductor passes, connected to a source of electric current. The source has been constructed so that enables fluent and feedback regulation of electric current. Passing of current through the conductor causes increase in the conduction temperature. The conduction radiation depending on its composition acts as catalyst on the partial oxidization in the blender of the present methane to methanol whereas the oxidization reaction runs in the point of the highest radiation intensity, in the close surroundings of the conductor.

The output products of the oxidization reactor are cooled, vapours of methanol are condensed and the formed liquid is led e.g. to the preparation phase of methyl ester production in oil re-esterification where it is used as an entrance material.

The gaseous rest of condensation is removed for final purification in which it is disposed of all organic parts and released to the atmosphere.

Examples

Example 1

The recycling method of waste glycerol phase was performed in a laboratory scale. The first stage of decomposition of glycerol phase was performed in a 30 litre reactor in which a couple of graphite electrodes was placed. The electrodes were fed with direct voltage of 36 V and high-frequency voltage with pulses of 10 kV and frequency 16 kHz. A catalytic and reduction filling consisting of coke particles was placed between the electrodes. Before being put in the reactor, the coke was activated in aqueous solution of iron(III) and chromium(III) salts. To the reactor an inlet pipe with a diameter of 10 mm was led, connected also to a feed pump of glycerol phase. The reactor outlet pipe was connected to a copper tube-type cooler with tube diameter of 15 mm. The tube was corkscrewed and immersed in water. The cooler outlet was led through a shower in a closed vessel in which a calcium hydroxide solution was sprayed through counterflow nozzles. The gas produced was led to a 100 litre gasholder filled with water, pushed out by the entering gas. The gas-holder outlet was connected through a stopcock to a blender consisting of a closed 200 litre vessel equipped with a fan of an explosion-proof type of construction. Air was supplied from another, 100 litre gas-holder to the blender through a stopcock. The blender outlet was connected to a feeding membrane pump which was connected to the reactor of partial oxidization of methane consisting of one glass tube, 12 mm in diameter and 1.2 m long, through the centre of which a conductor was led - iron wire with the diameter of 1 mm. The conductor was fed with voltage 14 V. The feed pump fed to the first-stage reactor the glycerol phase till the gas-holder was filled with 20 litres of gaseous products. The air-holder was filled up to the full volume using a compressor. Both fillings were brought into the blender and after approx. 60 s blending the membrane pump was turned on with a flow-rate of 10 litres per minute. The product of the oxidization reactor was cooled with water in a laboratory glass cooler. During the time of a six-hour test 20 kg of glycerol phase was treated from which 12 kg of methanol was obtained.

Example 2

In another example embodiment of the method according to the invention the first stage of the method - deoxidation of the glycerol phase - was performed in a closed 300 litre vessel containing six plasma reactors connected to a common source of electric voltage 48 V and a pulse source of electric voltage 10 kV. Each of them contained in the space between electrodes a reduction catalytic filling - a mixture of coke, iron(III) oxide, copper(I) oxide in the weight ratio of 100 : 5 : 0.5. Each of the six of plasma reactors was connected through a solenoid valve to a pressure pipe in which pressure 1.6 MPa of the circulating glycerol phase was created using a gear pump. When opening the particular solenoid valves the glycerol phase entered in the particular areas of the reactor and decomposed to methane, carbon dioxide and minor by-products according to the composition of the raw glycerol phase. The gas produced was taken off the vessel through a tube-type cooler to a vessel containing a lime milk solution through which it was bubbled and led off to a membrane feeding device into which air was added and mixed with it in a volume ratio of 2-3 volume parts to 1 part of the produced gas. The mixture was taken off to another vessel, hermetically sealed, in which a battery of glass tubes having 0 10 mm, length 1.35 m each, was placed. The tubes were interconnected so that gas passes through the tube space only. In the centre of each tube a conductor having 0 7mm, made of a material containing iron, chromium and nickel passed. Each conductor was connected to a voltage source terminal and provided with feedback regulation of current flow so that the conductor reached the max. temperature of 850 °C. Gas was led to the tubes so that its flow-rate did not exceed 0.5 m/s. Products from this reactor were in gaseous state and condensed in the subsequent tube-type condenser (cooler). The condensed liquid contained more than 95 % of methanol.

Example 3

Another example embodiment using the laboratory apparatus as in Example 1 dealt with treating of distiller's solubles from which ethanol was distilled off. The method of processing of distiller's solubles containing 5 % of dry matter was performed in a laboratory scale. The first stage of decomposition of distiller's solubles was carried out in a 30 litre reactor in which a couple of graphite electrodes was placed. The electrodes were fed with direct voltage of 36 V and high-frequency voltage with pulses of 10 kV and frequency 16 kHz. A catalytic and reduction filling consisting of coke particles was placed in between the electrodes. Before being put in the reactor, the coke was activated in aqueous solution of iron (III) and chromium (III) salts. To the reactor an inlet pipe with a diameter of 10 mm was led, connected also to a feeding pump of liquid distiller's solubles. The reactor outlet pipe was connected to a copper tube-type cooler with tube diameter of 15 mm. The tube was corkscrewed and immersed into water. The cooler outlet was led through a shower in a closed vessel in which a calcium hydroxide solution Was sprayed thnrngh counterflow nozzles. The gas produced was led to a 100 litre gas-holder filled with water, pushed out by the entering gas. The gas-holder outlet was connected through a stopcock to a blender consisting of a closed 200 litre vessel equipped with a fan of an explosion-proof type of construction. Air was supplied from another, 100 litre gas holder to the blender trough a stopcock. The blender outlet was connected to a feeding membrane pump which was connected to the reactor of partial oxidization of methane consisting of one glass tube, 12 mm in diameter and 1.2 m long, through the centre of which a conductor was led - iron wire with the diameter of 1 mm. The conductor was fed with voltage 14 V. The feeding pump fed to the first-stage reactor distiller^'s solubles till the gas-holder was filled with 10 litres of gaseous products. The air-holder was fed to a volume of 30 litres using a compressor. Both fillings were brought into the blender and after approx. 60 s blending the membrane pump was turned on with a flow-rate of 7 litres per minute. The product of the oxidization reactor was cooled with water in a laboratory glass cooler. During the time of a two-hour test 10 kg of distiller's solubles was treated from which 3.6 kg of methanol was obtained.

Industrial Applicability

The method according to the invention involving treating of waste mixtures of various materials with glycerol as the prevailing component can produce entering reaction materials for e.g. manufacture of bio-diesel fuel. This method can also considerably eliminate both ecological and economical burden caused by such wastes.

Claims

1. A method for processing of a mixture of waste substances containing glycerol as the prevailing component, characterized in that it contains the following steps: a) deoxidization of the mixture with a catalytic-reduction agent and co-acting external field, producing main components - methane and carbon dioxide;

b) partial oxidization of methane to methanol.

2. The method according to claim 1, characterized in that step a) is followed by step al) involving separation of the produced methane from carbon dioxide.

3. The method according to claim 1 or 2, characterized in that mixture of waste substances containing glycerol as the prevailing component is a glycerol phase from the production of rape-seed oil methyl ester.

4. The method according to one or more claims 1 to 3, characterized in that the external field acting during deoxidation is a heterogeneous electric and magneto- electric field.

5. The method according to claim 4, characterized in that the heterogeneous electric field is generated by pulsed high-frequency current in combination with low- frequency or direct current.

6. The method according to claim 5, characterized in that the above-mentioned mixture of substances goes through an electric field in the range of electric current values from 30 to 400 A with co-acting of pulsed high-frequency current with oscillation bands from 100 Hz to 100 kHz, causing occurrence of cold plasma with a temperature of 700 °C to 2100 °C and generation of a circular magnetic field encased iii the periphery with the occurring cold plasma.

7. The method according to one or more claims 1 to 6, characterized in that the catalytic-reduction agent includes elementary carbon.

8. The method according to claim 7, characterized in that elementary carbon is selected from of a group containing coke, anthracite, graphite, carbon black or charcoal or a mixture of them, with a particle size of 5 to 50 mm.

9. The method according to claim 8, characterized in that the elementary carbon is the coke.

10. The method according to claim 7 to 9, characterized in that inorganic and/or organic compounds containing iron, chromium or copper ions are adsorbed on the elementary carbon surface.

11. The method according to claim 10, characterized in that adsorbed inorganic compounds of iron is iron(III) oxide and that compounds of copper is copper(I) oxide, or aqueous solution of iron(III) or chromium(III) salts.

12. The method according to one or more claims 2 to 11, characterized in that in step al) methane is separated from carbon dioxide using hydroxide or a mixture of hydroxides.

13. The method according to claim 12, characterized in that the hydroxide is calcium hydroxide - Ca(OH)₂ .

14. The method according to claim 13, characterized in that calcium hydroxide - Ca(OH)₂ - is in the form of lime milk.

15. The method according to one or more claims 1 to 14, characterized in that the step b) of partial oxidization of methane to methanol includes the following steps: i) mixing of methane with oxidization gas in a stoichiometric ratio producing a gaseous mixture;

ii) contact of the passing stream of the gaseous mixture with an electric resistance conductor heated to the maximum temperature of 850 °C;

iii) condensing of vapours of methanol produced.

16. The method according to claim 15, characterized in that the oxidization gas is air and/or oxygen.

17. The method according to claim 15 or 16, characterized in that the flow-rate of passing stream of the gaseous mixture is approx. from 0.1 to 1 m/s.

18. The device for performing the method according to one or more claims 15 to 17, characterized in that it contains a catalytic oxidization reactor consisting of at least one tube of electrically non-conductive material, through the centre of which electric resistance conductor passes, connected externally to a source of electric current with feedback regulation.

19. The device according to claim 18, characterized in that the electrically non- conductive material of the tube is glass or ceramics.

20. The device according to claim 18, characterized in that the electric resistance conductor is made of iron.

21. The device according to claim 18, characterized in that the electric resistance conductor is made of an iron, nickel and chromium alloy.