ES2736103T3 - Procedure for preparing a combustible acid oil from the acidification of a neutralization paste of vegetable and / or animal origin - Google Patents

Abstract

Method of preparing a fuel from biomass comprising: a) a step of supplying an acidic oil from the refining of one or more oils chosen from a vegetable oil and / or an animal oil, the acidic oil having a content of water less than or equal to 1% by weight, even less than or equal to 0.8% by weight, in particular from 0.1% to 0.7% by weight, this stage comprising a): a1) an extraction stage of the fatty acids present in a neutralization paste from the saponification of one or more oils chosen from a vegetable oil and / or an animal oil, this extraction stage being carried out in an acid medium under effective conditions to form an aqueous phase and an organic phase comprising said fatty acids, a2) a separation stage during which said previously formed organic phase is separated and recovered, the organic phase recovered in step a2) constituting an acidic oil having a content C of water less than or equal to 3% by weight, subjected to stage b), optionally after a step a3) of centrifugation when its water content is greater than 1%, but less than or equal to 3%, allowing said stage of centrifugation obtain a water content of less than or equal to 1% by weight, or even less than or equal to 0.8% by weight, in particular from 0.1% to 0.7% by weight, b) a reduction stage of the ash, sulfur, phosphorus, calcium and sodium content of the acid oil obtained in stage a), this reduction stage comprising one or several sub-stages chosen between a filtration and a precipitation, carried out under effective conditions to obtain an acid oil fuel comprising: - ashes less than or equal to 0.1%, ideally less than 0.05% by weight, - sulfur less than or equal to 150 mg / kg, preferably less than 100 mg / kg, - lower calcium or equal to 5 mg / kg, preferably less than 1 mg / kg, - phosphorus less than or equal to 150 mg / kg, - sodium less than or equal to 10 mg / kg, preferably less than 1 mg / kg.

Description

DESCRIPTION

Procedure for preparing a combustible acid oil from the acidification of a neutralization paste of vegetable and / or animal origin

Technical field

The present invention relates to a process for preparing a combustible acid oil from biomass, mainly from the acidification of a neutralization paste obtained by a refining process of a vegetable and / or animal oil. The invention also relates to a combustible acid oil and the use of this oil.

The combustible acid oil of the present invention is more particularly suitable for use in combustion facilities that consume exclusively, alone or in admixture, natural gas, liquefied petroleum gases, domestic fuel, coal, heavy fuels and biomass. The combustible acid oil of the invention is therefore not a fuel.

Mainly, the combustible acid oil of the present invention can be used in combustion plants classified in Section 2910 A (and more precisely in 2910 B and 2910 C) of the nomenclature of facilities classified for environmental protection (ICPE nomenclature ) defined in Decree No. 2013-814 of September 11, 2013, published in the Official Gazette of the République Frangaise of September 13, 2013.

Prior art

The oil refining industry, at least in Western Europe, has a tendency to decrease the production of heavy fuel, due to the decrease in demand. This decrease is related to the transition to alternative energy sources by customers, mainly natural gas, as well as to environmental restrictions that tend to limit the amounts of NOx, SO ² and dusts emitted into the atmosphere. To comply with the most stringent regulatory requirements, high-power combustion facilities must rely on a fuel free of nitrogen, sulfur and ash or smoke treatment techniques, which is not economically viable compared to other energies, such as for example natural gas

In addition, heavy fuel generally needs to be stored at a temperature close to 50 ° C in order to be pumpable and sprayable at a temperature between 85 and 130 ° C according to the technology of the burners, in relation to the viscosity of the product . These heating stages represent a non-negligible energy consumption.

In addition, the flash point of the heavy fuel (generally between 70 and 120 ° C) close to its application temperature may cause additional stress in terms of safety (explosive atmospheres).

Therefore, there is a need for a heavy fuel replacement fuel that is less restrictive during its application and that allows to meet the increasingly high requirements for atmospheric emissions resulting from its combustion.

There are fuel compositions based on heavy fuel and products made from biomass, such as for example the fuel compositions produced by the applicant company and described in WO2013 / 098524 and WO2014 / 102492. The combustible compositions described in WO2013 / 098524 are a mixture of heavy fuel and a tall oil or a neutralization oil (fatty acid composition neutralized by a base and then acidified), allowing tall oil and neutralization oil stabilize the fuel composition. The compositions described in WO2014 / 102492 are mixtures of a neutralization paste and a heavy fuel of petroleum origin. However, these different combustible compositions do not come entirely from biomass.

There is a need for a heavy fuel replacement fuel that is less restrictive during its application, which allows it to meet the increasingly high requirements for atmospheric emissions resulting from its combustion and which is completely obtained from biomass.

US2011 / 0203168A1 describes the manufacture of compositions of oils containing triglycerides and fuels using particular microorganisms. The composition of oils is obtained by culturing these microorganisms in the presence of a carbon source. Therefore, the composition of oils is not obtained from the chemical refining of a vegetable or animal oil, but is produced by microorganisms. In addition, this document mentions the manufacture of fuels (biodiesel) by transesterification of the oil produced by microorganisms. These fuels are therefore composed of C ¹⁴ -C ¹⁸ alkyl fatty acid esters and do not include free fatty acids.

Document CA2541327A1 describes a biodiesel purification process with the aid of adsorbent materials. This biodiesel is produced by reacting triglycerides with an alcohol in order to form esters of fatty acids. The fuel purification process thus obtained allows mainly soaps, mono- and di-glycerides to be eliminated as well as polymerized triglycerides. The biodiesel described does not therefore include free fatty acids.

Brief summary of the invention

The requesting company proposes a procedure for preparing a fuel, mainly a liquid fuel, from biomass that can replace a fuel, mainly to be burned in an industrial boiler or an industrial furnace instead of a fuel.

A first object of the invention thus relates to a process for preparing a fuel from biomass according to claim 1.

Advantageously, step b) can also allow the content of alkali metals other than sodium to be reduced, mainly to a value less than or equal to 1 mg / kg.

The acid oil provided in step a) is defined as that obtained from the acidification of a neutralization paste.

Acid oils naturally have low but variable sulfur and nitrogen contents, so that their combustion produces low emissions of SO ² and NOx. However, it is necessary to decrease the sulfate content (hence sulfur) in order to limit particle emissions. Its water and ash content is however important and leads, on the one hand, to a decrease in combustion performance and on the other hand to particle emissions that do not meet environmental requirements.

The process according to the invention allows to obtain a combustible acid oil, constituting the fuel derived from the biomass of the present invention, which has a good calorific value and can be burned producing low emissions of air pollutants. Therefore, it can replace a heavy fuel type fuel.

The invention thus makes it possible to obtain a fuel derived solely from biomass, ie neutralization pastes, whose emissions meet the high environmental restrictions.

In addition, despite the variable compositions of acid oils depending on their origin (mainly depending on the nature of the vegetable and / or animal oil from which they originate and the quality of this oil), the process according to the present invention allows obtain a fuel that has constant characteristics in terms of emissions of air pollutants, guaranteeing the use of fuel in combustion facilities that usually use a heavy fuel or the other types of fuel mentioned above (mainly installations classified according to types 2910A, 2910B , 2910C ICPE nomenclature).

Another object of the invention relates to a combustible acid oil, derived from the acidification of a neutralization paste obtained by a refining process by saponification of a vegetable and / or animal oil, according to claim 8.

According to advantageous forms, the ash content may be less than or equal to 0.04% by weight.

Advantageously, the combustible acid oil according to the invention may further comprise an alkali metal content other than sodium less than or equal to 1 mg / kg.

The combustible acid oil according to the invention has a water content of less than or equal to 1% by weight, advantageously less than or equal to 0.8% by weight, in particular from 0.1% to 0.7% by weight.

Advantageously, the combustible acid oil according to the invention may have a flash point greater than or equal to 200 ° C (measured according to NF EN ISO 2719 by means of an apparatus called Pensky Martens type). A high flash point makes it possible to reduce the safety restrictions associated with storage in relation to a heavy fuel that has a lower flash point. This results in lower application costs and easier application.

Said combustible acid oil can be obtained directly by the process according to the invention.

Another object of the invention relates to a combustion process of a fuel in a combustion installation, mainly of the type 2910A or 2910B or 2910C according to the ICPE nomenclature, in which a combustible acid oil directly obtained by the process is burned as fuel according to the invention or a combustible acid oil according to the invention.

Detailed description of the invention

Stage a) of supplying an acid oil

The acid oil supplied in step a) comes from the refining of one or several oils chosen from a vegetable oil and / or an animal oil.

It is mainly an oil from the acidification of a neutralization paste, this neutralization paste being obtained from the refining of one or several oils chosen from a vegetable oil and / or an animal oil. The neutralization paste is preferably obtained from the chemical refining of one or more vegetable oils.

An acidic oil can be defined as fatty acid compositions neutralized by a base and then acidified.

Advantageously, the fatty acids come directly from the saponification of a vegetable and / or animal oil, such as, without limitation, a sunflower, soybean, rapeseed, palm oil, coconut oil, peanut oil, olive oil, an oil of fish, and typically comprising mostly C ¹⁶ -C ¹⁸ , saturated or unsaturated carbon chains, among which C ¹⁸ unsaturated carbon chains are preferred. Vegetable oils usually comprise palmitic, oleic, linoleic acid and other acids in smaller amounts. Fatty acid compositions neutralized by a base are typically neutralization pastes.

Typically, an acid oil contains 30 to 70% by weight of fatty acids.

The acid oil supplied in step a) has a water content of less than or equal to 1% by weight, or even less than or equal to 0.8% by weight, in particular 0.1% to 0.7% by weight .

Step a) may mainly comprise the supply of an acidic oil from the refining of one or more oils chosen from a vegetable oil and / or an animal oil, which has a water content of less than or equal to 3% by weight but greater than 1% by weight, followed by a centrifugation step that allows to obtain a water content of less than or equal to 1% by weight, even less than or equal to 0.8% by weight, in particular 0.1% to 0.7 % in weigh.

According to the invention, step a) of supplying an acidic oil comprises:

a1) a stage of extraction of the fatty acids present in a neutralization paste from the saponification of one or several oils chosen from a vegetable oil and / or an animal oil, this extraction stage being carried out in an acid medium under conditions effective for forming an aqueous phase and an organic phase comprising said fatty acids,

a2) a separation stage during which said previously formed organic phase is separated and recovered.

The organic phase recovered in step a2) constitutes an acidic oil that generally has a water content of less than or equal to 3% by weight.

Neutralization paste used during stage a1)

The neutralization paste treated in step a1) can be a mixture of neutralization pastes from the refining of different oils or it can be a neutralization paste from the refining of a single oil. This refining is preferably chemical.

Said neutralization pastes come, mainly directly, from the saponification of a vegetable oil and / or an animal oil. In general, this saponification is carried out by adding a base, usually soda, and allows eliminating the free fatty acids present in the oil, which are found in the neutralization paste (in English " soapstock ") in the form of alkaline salts of fatty acids. Prior to this saponification, vegetable and / or animal oil may undergo a de-gumming or demucilagination operation that aims to eliminate phospholipids, lecithins, sugar complexes and other impurities. The separation of the oil and the neutralization paste resulting from the saponification can be carried out by centrifugation.

The neutralization pastes thus essentially comprise fatty acids neutralized by a base. They typically comprise 30 to 70% by weight of fatty acids.

In addition to the neutralized fatty acids by a base, the neutralization pastes may contain, depending on their origin and the quality of the saponification, unreacted phospholipids or mono-, di- or tri-glycerides. Usually, the fatty acids have carbon chains of C ¹² -C ²⁴ , preferably C ¹⁶ -C ²⁰ or better of C ¹⁶ -C ¹⁸ .

A neutralization paste is therefore a product from biomass. The advantages associated with such neutralization pastes lie, on the one hand, in their low cost of application and, on the other hand, in the absence of undesirable toxic substances, such as pesticides, aflatoxins, heavy metals, dioxin and furan precursors, PCBs and nitrites

However, the water content of these neutralization pastes is prohibitive in their use only as fuel. In fact, such pastes may contain significant proportions of water that come from the Saponification reaction or the addition of water for fluidization in the industrial process. Typically, the aqueous phase represents at least 50% of the mass of the neutralization paste. Another difficulty is related to the fact that it is treated according to the case of emulsions, which should be treated specifically.

The use as fuel therefore needs to apply methods to remove this water and other solid waste or unwanted viscous liquids.

Stage a1) extraction

The step a1) for extracting the process according to the invention has the function of extracting the fatty acids contained in the neutralization paste. This extraction is carried out in an acid medium under effective conditions to form an aqueous phase and an organic phase comprising the fatty acids initially contained in the neutralization paste.

This organic phase comprising fatty acids is generally referred to as "acid oil" or even "neutralization oil."

The acid used to extract the fatty acids present in the salt neutralization paste is generally an inorganic acid, such as for example sulfuric acid, phosphoric acid or hydrochloric acid.

However, sulfuric acid is preferred, because it allows a better extraction of fatty acids at a favorable economic cost.

The extraction is generally carried out under heating, at a temperature between 70 and 100 ° C (both included), preferably between 80 and 90 ° C (both included).

In order to obtain a good fatty acid extraction, an acidic pH is preferably maintained during the reaction time, for example, a pH less than or equal to 6, preferably less than or equal to 4.

The reaction time is chosen to allow extraction of all fatty acids. For example, from 1 hour to 12 hours, depending on the geometry of the reactor, the nature and the composition of the load to be treated. Extraction is preferably performed with stirring.

In this way the formation of an aqueous phase and an organic phase containing the fatty acids is obtained. Stage a2) of separation

During this stage, the organic phase formed during stage a1) is separated from the aqueous phase. In other words, the acid oil that is subsequently subjected to step b) of the process according to the invention is isolated, optionally after a step a3) of centrifugation when its water content is greater than 1% but less than or equal to 3% .

This separation can be done by distillation, decantation or even centrifugation. This stage can be performed on any suitable device, known and commercially available.

Advantageously, this separation is carried out by decantation, followed by a removal of the aqueous phase. The decantation depends on the difference in density of the liquids and their viscosity, parameters that can be modified in a manner known to those skilled in the art if necessary to promote separation.

Advantageously, a 150 pm filtration of the acid oil can be performed before any subsequent stage.

Centrifugation stage

When the water content of the acid oil is less than or equal to 3% by weight, but greater than 1% by weight, the acid oil can be advantageously subjected to a centrifugation prior to step b). An objective of this centrifugation is to decrease the water content of the acid oil.

The centrifugation is advantageously carried out of an acid oil obtained in steps a1) and a2) described above.

This centrifugation operation makes it possible to obtain an acid oil that very advantageously has a water content of less than or equal to 1% by weight, or even less than or equal to 0.8% by weight, in particular 0.1% to 0.7 % in weigh. In addition to removing the water, recovered in an aqueous phase, centrifugation also allows the removal of a part of the solid waste in suspension.

The centrifugation step has the advantage of a simplified embodiment, avoiding resorting to complex methods of chemical separation, such as distillation, which can be restrictive in terms of undesirable and expensive precautions and corrosion.

The centrifugation step can advantageously be a three-phase centrifugation.

However, the centrifugation stage may itself be a combination of stages, in particular comprising a first stage of centrifugation of the biphasic type, which makes it possible to separate the suspended solid materials in sludge form, coupled to a second stage of three-phase centrifugation. , which separates the organic phase, the purified aqueous phase and the solid suspended solid materials from the first centrifugation. This stage can be performed on any suitable device, known and commercially available.

Typically, centrifugation can be performed with speeds of 4000-6000 rpm.

The duration of centrifugation depends on the nature of the species to be separated, their distribution coefficient, the difference in density between the aqueous phase, the oily organic phase and the particles, the size of the particles, the surface tension of the species to be separated, the temperature and the speed of centrifugation. The separation duration (called residence time) is therefore adapted on a case-by-case basis by those skilled in the art by conventional means of measurement and control.

Stage b) of reducing the content of ashes, sulfur, calcium, phosphorus, sodium and possibly alkali metals other than sodium

During this stage b), the content of ashes, sulfur, calcium, phosphorus, sodium and possibly alkali metals other than sodium, of the acid oil supplied in stage a) is reduced by means of one or more sub-stages of filtration and / or precipitation.

This step b) can be performed on any appropriate, known and commercially available device.

The filtration can therefore be carried out by means of a filter press or a cartridge filter or a filter membrane or it can be an ultrafiltration, a nanofiltration or even a reverse osmosis filtration.

Step b) can advantageously comprise at least one filtration stage carried out with the aid of at least one pass through a cellulose filter. Said cellulose filter can allow the improvement of the filtration efficiency avoiding clogging.

The precipitation step can be advantageously carried out under conditions effective to precipitate the sulfates present in the acid oil. These sulfates may come from the saponification of the oil and / or the acid extraction of fatty acids.

Without wishing to be bound by any theory, sulfate precipitation seems to be associated with the precipitation of calcium, phosphorus, sodium and eventually alkali metals other than sodium, which has the effect of decreasing the ash content of the product.

In general, the conditions for carrying out the precipitation will be determined by those skilled in the art by conventional means depending on the species to be precipitated.

Precipitation of sulfates can be carried out mainly by the addition of Ca2 + ions, for example, in the form of CaCl ² (calcium chloride).

The choice and number of these sub-stages can easily be determined by one skilled in the art by controlling the ash, sulfur, calcium, phosphorus and sodium content of the final organic phase, which constitutes the combustible acid oil according to the invention.

In one embodiment, step b) may comprise at least two successive filtration stages with filters with a smaller and smaller mesh opening. As an example, filtrations can be carried out by means of a first filter from 20 to 30 pm and a second filter from 0.5 to 1.5 pm.

In another embodiment, step b) may comprise a filtration stage followed by a precipitation stage, mainly sulfates.

Eventually, these filtration and precipitation stages may be preceded or followed by one or more filtration stages, including one or several precipitation stages. Advantageously, the last stage may be a filtration stage.

The method may comprise a succession of filtrations by means of decreasing mesh filters to reach the final objective, for example, from 200 pm to 25 pm. Advantageously, the last filtration stage is then carried out by means of a filter having a mesh opening of 0.5 to 1.5 pm.

Thanks to this stage b), it is possible to obtain an acidic oil that constitutes a final combustible acidic oil that has very advantageous contents of:

• ashes less than or equal to 0.1%, ideally less than 0.05% by weight,

• sulfur less than or equal to 150 mg / kg, preferably less than 100 mg / kg,

• calcium less than or equal to 5 mg / kg, preferably less than 1 mg / kg,

• phosphorus less than or equal to 150 mg / kg,

• sodium less than or equal to 10 mg / kg, preferably less than 1 mg / kg,

and eventually an alkali metal content other than sodium less than or equal to 1 mg / kg.

The ash content can be measured according to NF EN ISO 6245.

The sulfur content can be measured according to NF EN ISO 20846.

The calcium content can be measured according to NF T 60106.

The phosphorus content can be measured according to NF T 60106.

Sodium content may be measured according to NF T 60106.

The content of alkali metals other than sodium may be measured according to NF T 60106.

It will be observed that the process according to the invention can allow to obtain oils whose contents of ash, sulfur, calcium, phosphorus, sodium and possibly alkali metals other than sodium are much lower than the aforementioned thresholds, even null or almost null and undetectable by the means usual quantification.

In addition, the final fuel acid oil has a water content of less than or equal to 1%, even less than or equal to 0.8%, in particular 0.1% to 0.7% by weight.

Examples

Example 1

Table 1 shows some typical physicochemical characteristics of an acid oil and a very low sulfur heavy fuel (MBCA) (heavy fuel without additives), as well as the specifications imposed by the CSR 500 for a heavy fuel. These specifications are established by the Chambre Syndicale du Raffinage in France.

Step a) of the process according to the invention can mainly provide an acidic oil having characteristics such as those shown in Table 1. It will be noted that a typical acidic oil meets CSR 500 specifications.

Table 1

Example 2: Pilot combustion test

This pilot test was carried out in a decanted oil, but which had not been subjected to centrifugation or filtration / precipitation. In other words, the oil tested corresponds to an acidic oil that has a water content of less than or equal to 3% by weight.

Obtaining the acid oil

A neutralization paste was subjected to the following treatment:

a1) injection of 120 L of 97% sulfuric acid in a reactor containing 4000 kg of neutralization paste, where the temperature was 80 to 90 ° C. The reaction time was 24 hours under continuous pH control in order to keep the pH below 4.

a2) decantation of the aqueous phase and the organic phase formed during step a1) and then elimination of the aqueous phase.

An acidic oil (Sample A) was obtained that was not subjected to further treatment, such as centrifugation and precipitation / filtration.

Table 2 presents the characteristics of this acidic oil (Sample A) compared to those of a very low sulfur heavy fuel (MBCA) (Sample B, MBCA heavy fuel without additives) and of a liquid fuel according to the invention ( Sample D).

The liquid fuel according to the invention (sample D) was prepared according to the methodology described in Example 4 from neutralization pastes obtained essentially from rapeseed, soybean and sunflower oils.

Table 2:

(*) Measurement carried out according to the method of the Union Frangaise des Industries Pétroliere (UFIP) and the Association Technique Energie Environnement (ATEE).

Combustion test

Each fuel (samples A, B and D) was burned separately in a 1 MW, 1 burner smoke boiler with mechanical spraying without assistance. The fumes were analyzed by means of analyzers placed in combustion fumes (analyzers placed in the evacuation ducts).

Table 3 below shows the combustion conditions of this test, as well as the measured emissions.

Table 3

m3 (n): normal cubic meters, measured at P = 101.3 kPa and T = 273K

It will be noted that the combustion performances of the sample A and the heavy fuel are substantially equivalent, showing that an acidic oil can be replaced by a heavy fuel in a combustion plant. In addition, the spray temperature and the priming temperature are lower for acidic oil, treated (Sample D) or not (Sample A), so that the total energy consumption of the installation is reduced with respect to the combustion of a heavy fuel . The use of acid oil is also simpler.

Due to the nature of an acidic oil, the NOx and SO ² emissions are zero or very low. On the contrary, the emission of powders from an acidic oil is greater than for a heavy fuel and does not allow compliance with regulatory restrictions related to combustion plant emissions, (being the exposure limit value (VLE) for powders between 20 and 50 mg / m3). The fuel according to the invention meets these restrictions, with even lower NOx emissions.

Example 3: Industrial Combustion Test

Fuel analysis

The physicochemical characteristics of the tested fuels are shown in table 4.

Unlike in the pilot test, the heavy fuel (Sample C) is an MBCA heavy fuel additive with a combustion additive that has the effect of reducing dust emissions.

Table 4:

(*) Measurement carried out according to the method of the Union Frangaise des Industries Pétroliere (UFIP) and the Association Technique Energie Environnement (ATEE).

Industrial Combustion Test

Samples A and C were burned in a 39 MW water tube boiler, comprising 3 burners with mechanical spraying with steam assistance. Sample D was burned in a 52 MW water tube boiler, comprising 4 burners with mechanical spray with air assistance.

The fuels were burned among other fuels: the fouling of the boiler before each combustion test could therefore be different.

The combustion conditions and the measured emissions are shown in table 5.

Table 5

m3 (n): normal cubic meters, measured at P = 101.3kPa and T = 273K

(*) NF EN 14385

Although the yields are not directly comparable due to a potentially different fouling of the boiler before the combustion of Samples A and C, an acceptable combustion performance for the acid oil is observed, for a much lower injection temperature with respect to the heavy fuel .

It will be noted that the heavy fuel does not meet the NOx Emission Limit Value: 450 mg / m3 (n) imposed by the regulations.

Dust emissions from acid oil are very important and do not respect the limits of the different laws.

Mainly, dust emissions are much higher than the VLE of 50 mg / m3. In order to burn an acidic oil of this type, the combustion plant should be equipped with a smoke treatment, such as an electrofilter.

Without wishing to be bound by any theory, it is assumed that dust emissions are due to the high contents in the acidic oil of ashes, calcium, sodium and possibly phosphorus.

The combustion of the sample D according to the invention shows the obtaining of a good combustion efficiency and a low dust emission.

It should be taken into account that the combustion of a heavy fuel without additives in a boiler, such as in which the sample D was burned would require the use of a smoke treatment to comply with the VLE.

The VLE specifications in force in France in 2016 are shown in tables 6 and 7 below. It is observed that these values are respected during the combustion of sample D, without any treatment of the fumes produced.

Table 6 shows the specifications required for liquid fuels other than domestic fuel, such as those contained in Decree of 08/26/13 that modifies Decree of July 25, 1997 on the general requirements applicable to facilities classified for the protection of the environment submitted to declaration in Section N ° 2910 (Combustion).

Table 7 shows the specifications required for liquid fuels other than domestic fuel, such as those contained in Decree of 08/26/13 relating to combustion facilities of a power greater than or equal to 20 MW, subject to authorization in the Title of Section 2910 and Section 2931.

Table 6

Table 7

(*) Water pipe boiler

Example 4: Characteristics of liquid fuels obtained according to the process of the invention. Obtaining liquid fuels

A neutralization paste was subjected to the following treatment:

a1) injection of 120 L of 97% sulfuric acid in a reactor containing 4000 kg of neutralization paste, where the temperature was 80 to 90 ° C. The reaction time, with stirring to ensure homogeneous mixing, was 24 hours, under continuous pH control in order to maintain the pH at a value lower than 4, a2) decantation of the aqueous phase and the organic phase formed during the step a1) and then elimination of the aqueous phase,

a3) centrifugation at 5000 revolutions min-1 for 5 minutes using an Alpha Laval® centrifuge apparatus, followed by the removal of the aqueous phase,

b) first filtration in a 25 jm paper filter followed by a second filtration in a 0.9 | jm cellulose filter, the two filtrations being carried out in series with a flow rate of one ton / hour.

The characteristics of the fuels thus obtained are shown in table 8. Sample D was prepared from neutralization pastes obtained essentially from rapeseed, soybean and sunflower oils, sample E was prepared from pasta neutralization obtained essentially from rapeseed oil.

Table 8

(*) Measurement carried out according to the method of the Union Frangaise des Industries Pétroliere (UFIP) and the Association Technique Energie Environnement (ATEE).).

Physicochemical characteristics of liquid fuel

Table 9 allows to visualize the evolution of the characteristics that influence the dust emissions during the fuel manufacturing process, as described in the present invention.

Table 9 shows the physicochemical characteristics of an acid oil stored in a tank (Sample No. 1). This acidic oil corresponds to an acidic oil that has a water content greater than 1% by weight.

The acidic oil stored in the tank was then subjected to mixing and a centrifugation step (5000 rpm in an Alpha Laval® apparatus) until sample No. 2 was obtained. Sample No. 2 therefore corresponds to an acid oil such as that provided in step a) of the process according to the present invention, with a water content of less than 1% by weight.

Sample No. 3 results from the filtration of sample No. 2 through a 25 micrometer filter followed by a 0.9 micrometer filter. Sample No. 3 corresponds to a combustible acid oil, such as that obtained in step b) of the process according to the present invention.

In view of these characteristics, it is observed that centrifugation makes it possible to significantly reduce the ash content and the sodium content (see sample No. 2). Likewise, there is a decrease in water content, as well as calcium and phosphorus content. This centrifugation step can also be used to reduce the water content, but also to decrease the ash content to the extent that centrifugation also seems to reduce the phospholipid content, which is the origin of the phosphorus, and the content of metals (see table 9).

Each of the subsequent filtrations allows this content to be further reduced (see Sample No. 3).

It is also observed that each of samples N ° 2 and N ° 3 has water, ash, calcium, phosphorus and sodium contents lower than those of sample A and water, ash, calcium and sodium contents of the same order of magnitude than those of sample C of example 3. Therefore, the combustion of these samples can be expected to meet the emission requirements, particularly of powders.

The process according to the invention allows, therefore, to produce a combustible acid oil with a reduced content of both water and ash.

Table 9

Claims (12)

1. Procedure for preparing a fuel from biomass comprising: a) a step of supplying an acidic oil from the refining of one or several oils chosen from a vegetable oil and / or an animal oil, the acidic oil having a water content of less than or equal to 1% by weight, even less than or equal to 0.8% by weight, in particular from 0.1% to 0.7% by weight, comprising this stage a): a1) an extraction stage of the fatty acids present in a neutralization paste from the saponification of one or more oils chosen from a vegetable oil and / or an animal oil, this extraction stage being carried out in an acid medium under conditions effective to form an aqueous phase and an organic phase comprising said fatty acids, a2) a separation stage during which said previously formed organic phase is separated and recovered, constituting the organic phase recovered in step a2) an acidic oil having a water content of less than or equal to 3% by weight, subjected to stage b), optionally after a stage a3) of centrifugation when its water content is greater than 1%, but less than or equal to 3%, allowing said centrifugation step to obtain a water content less than or equal to 1% by weight, or even less than or equal to 0.8% by weight, in particular 0, 1% to 0.7% by weight, b) a stage for reducing the ash, sulfur, phosphorus, calcium and sodium content of the acid oil obtained in stage a), this reduction stage comprising one or several sub-stages chosen between a filtration and a precipitation, carried out under conditions effective in obtaining a combustible acid oil comprising a content of: • ashes less than or equal to 0.1%, ideally less than 0.05% by weight, • sulfur less than or equal to 150 mg / kg, preferably less than 100 mg / kg, • calcium less than or equal to 5 mg / kg, preferably less than 1 mg / kg, • phosphorus less than or equal to 150 mg / kg, • sodium less than or equal to 10 mg / kg, preferably less than 1 mg / kg. 2. The method according to claim 1, wherein the combustible acid oil obtained in step b) further comprises a content of alkali metals other than sodium, less than or equal to 1 mg / kg. 3. The method according to any one of claims 1 to 2, wherein step b) comprises at least two successive filtration stages with increasingly smaller mesh opening filters. 4. The method according to any one of claims 1 to 3, wherein step b) comprises a filtration stage followed by a precipitation stage. 5. The method according to any one of claims 1 to 4, wherein step b) comprises at least one filtration stage carried out with the aid of at least one pass through a cellulose filter. 6. A process according to any one of claims 1 to 5, wherein step b) comprises at least one precipitation step performed under conditions effective to precipitate the sulfates present in the acid oil obtained in step a). 7. Method according to any one of claims 1 to 6, wherein the combustible acid oil obtained in step b) is burned in a combustion plant. 8. Fuel acid oil from the acidification of a neutralization paste obtained by a refining process by saponification of a vegetable and / or animal oil, said combustible acid oil being capable of being obtained by performing the process according to one of the claims 1 to 7, comprising a content of: • ashes less than or equal to 0.1%, ideally less than 0.05% by weight, • sulfur less than or equal to 150 mg / kg, preferably less than 100 mg / kg, • calcium less than or equal to 5 mg / kg, preferably less than 1 mg / kg, • phosphorus less than or equal to 150 mg / kg, • sodium less than or equal to 10 mg / kg, preferably less than 1 mg / kg, and • a water content less than or equal to 1% by weight. 9. Fuel acid oil according to claim 8, having a content, of alkali metals other than sodium, less than or equal to 1 mg / kg. 10. Fuel acid oil according to claim 8 or 9, which has a flash point greater than or equal to 200 ° C. 11. Fuel acid oil according to any one of claims 8 to 10, comprising a water content of less than or equal to 0.8% by weight, particularly 0.1% to 0.7% by weight. 12. Method of combustion of a fuel in a combustion plant, wherein a combustible acid oil is burned according to any one of claims 8 to 11.