FR3052459A1 - MIXTURE FOR FEEDING A BOILER OR A DIESEL ENGINE COMPRISING SPECIFIC ESTERS AND ALKANES - Google Patents

Abstract

The subject of the invention is a mixture of liquid fuels for boilers or diesel fuels with esters and alkanes of particular chain lengths, and its use for reducing the emissions of particles and nitrogen oxide during the operation of boilers or diesel engines.

Description

MIXTURE FOR FEEDING A BOILER OR A DIESEL ENGINE COMPRISING SPECIFIC ESTERS AND ALKANES

The present invention relates to a mixture based on liquid fuel for a boiler or diesel engine fuel, comprising particular compounds which make it possible to reduce the emissions of particles and nitrogen oxide from boilers and diesel engines during their operation.

Diesel engines are efficient engines from the point of view of the fight against the greenhouse effect since, at equivalent power, they emit about 20% less greenhouse gas emissions than gasoline engines. Nevertheless, they are more and more criticized because of certain emissions harmful for the man, in particular the emissions of particles and oxides of nitrogen. In some large cities, or even entire regions, air pollution from these emissions is a major problem.

Particulate and nitrous oxide emissions from diesel engines are regulated in many countries. This is particularly the case in Europe where the limits set by the regulations are more and more stringent (today Euro6 standards). This is also the case in other large countries, particularly the United States, but with very low limits in some states such as those set by the California Air Resources Board.

Particles fall into two categories of measures: • measurements that characterize the color of exhaust gases (smoke measurements) • measurements of weight, diameter and number of particles.

The particles are of different sizes. Four categories of fine particles are generally distinguished: PMio with a diameter of less than 10 μm, PM2.5 with a diameter of less than 2.5 μm, ultrafine particles with a diameter of less than 0.1 μm and nanoparticles, characterized by a diameter less than 50 nm.

Most particles emitted by diesel engines have a diameter of minus 1 μm. They therefore represent a mixture of fine or ultrafine particles and nanoparticles. The smaller ones are considered the most dangerous for the man.

Diesel engines have made remarkable progress over the last 30 years thanks to the improvement of fuel quality (reduction of sulfur content), of the combustion process (optimization of injection systems) and of treatment processes. exhaust gases (exhaust gas recirculation, catalytic oxidation systems and particulate filters). But despite a reduction of about 98% in the order of thirty years of particulate emissions on new engines, the problem of particles remains considered serious enough that some cities come to want to ban Diesel vehicles in the city. This is due in particular to the fact that Diesel vehicles are kept for many years (8 to 10 years for private vehicles and often more than 15 years for coaches and trucks).

It would therefore be very useful, in addition to the measures to reduce emissions on new vehicles and the promotion of alternative energies (electric vehicles or NGV vehicles, for example) to find solutions for existing diesel vehicles.

The same problems of particle emission and nitrogen oxides are encountered with liquid fuels for boilers, in particular with old boilers whose contribution to pollution by particles and nitrogen oxides is also very significant. The objective of the present invention is to respond to these problems and in particular to provide an effective, simple and economical solution for reducing emissions from diesel engines and liquid fuel boilers. For this purpose the invention proposes to incorporate in the diesel engine fuel or in the boiler fuel together one or more esters and one or more specific alkanes.

Before the 1990s, there was no biofuel for diesel engines while ethanol had long been used in gasoline, especially in Brazil and the USA. From 1992 began to be developed in France, then in Europe and in the world, the use of biodiesel which is a methyl ester (or ethyl) of vegetable oil. Today, different types of esters are used depending on the origin of the fats that are trans-esterified by an alcohol: vegetable oils, animal fats or recovered cooking oils. These are fatty acid esters whose chain length is mainly between 16 and 18 carbon atoms. These products are generally incorporated at a rate of less than 8% in conventional diesel or they are used at 20% or 30% or exceptionally pure in captive transport fleets. But the gains that can be expected in reducing the particles of such mixtures are limited (reduction of the order of half the rate of incorporation of the esters). In addition, these esters tend to increase nitrogen oxides. They are submitted in Europe to the EN14214 standard and, in other parts of the world, to similar standards and the rate of incorporation into unconfined diesel is generally limited to 8% by volume, in particular for this reason.

Some other biofuels, particularly alkanes from biomass, are beginning to be developed, whether vegetable oils or hydrotreated animal fats (treated with hydrogen to remove oxygen atoms) which also have 16 to 18 carbon atoms. carbon or products of the type BTL (Biomass to Liquid) resulting from the gasification of biomass followed by the synthesis of Fischer Tropsch. Other solutions are developed, still experimental, such as hydrotreated pyrolysis oils and alkanes that can be obtained by anaerobic fermentation of biomass followed by Kolbe electrolysis (patent application WO2014170603).

These hydrocarbons are interesting because they generally have a high cetane number which favors a reduction of NOx emissions. Their effect on particles, however, remains limited.

In addition, the addition to fuels of various oxygenated components (alcohols or esters) has been proposed for many years, for objectives that were not the reduction of particulate emissions but the improvement of other functionalities (improvement of resistance to cold, lubricity, impact on agriculture, impact on the greenhouse effect, ...), for example: the use of more than 10% ethanol in diesel but this requires the presence of expensive additives the incorporation of butanol into diesel (example: Energy Conservation and Management Vol 51, Issue 10, October 2010, Effects of butanol-diesel fuel blends on the performance and emissions of a high-speed diesel engine DI) incorporation of esters derived from the anaerobic fermentation of biomass in gasoline, gas oil or kerosene (patent FR 2757539A1, Dupré-Kaplan, use of esters as fuels or fuels).

Tests have also been made for the use of aldehydes in diesel fuel (Reducing the Emission of Particles from a Diesel Engine by Adding an Oxygenate to the Fuel Environmental Science and Technology 39 (16): 6260-5 · September 2005) in the purpose of reducing the emitted particles, but the emissions of acetaldehyde, which are also considered dangerous, were greatly increased. Nevertheless, none of these solutions has resulted in a satisfactory solution.

The present invention is specifically aimed at incorporating into fuels for diesel engines or liquid fuels for a boiler: at least one ester with a chain length of between 8 and 14 carbon atoms, and at least one alkane with a length of chain of between 8 and 14 carbon atoms, the ester (s) having a chain length of between 8 and 14 carbon atoms representing between 1% and 80% by volume of said mixture and the alkane or alkanes of chain length included between 8 and 14 carbon atoms representing between 1 and 80% by volume of said mixture.

The mixture according to the invention is a liquid mixture which has a variable composition. Advantageously, such a mixture makes it possible to reduce particulate emissions and nitrogen oxide emissions during the operation of boilers or diesel engines, without there being a degradation of the other emissions (nitrogen monoxide CO, hydrocarbons). HC-imbricated, etc.). In addition, the invention makes it possible to ensure that the mixture meets all specifications of fuels and liquid fuels, including those that are the most difficult to meet, namely the flash point must be above 55 ° C and the calculated cetane number which must be greater than 46. In addition, the mixture according to the invention makes it possible to preserve the characteristics of the diesel engine fuel and the liquid fuel for the boiler, such as, for example, the cold strength, the viscosity, etc.

The esters and / or alkanes used can in particular be biobased, that is to say be biofuels from agricultural or forestry biomass or organic waste, which then also has an advantage in combating the effect of tight. Other features and advantages will become apparent from the following detailed description of the invention. The invention therefore relates to a mixture for supplying a boiler or a diesel engine, comprising: at least one liquid fuel for a boiler or a fuel for a diesel engine, and at least one ester with a chain length of between 8 and 14 carbon atoms and at least one alkane with a chain length of between 8 and 14 carbon atoms, the ester (s) with a chain length of between 8 and 14 carbon atoms representing between 1% and 80% by volume of said mixture and the alkane or alkanes of chain length of between 8 and 14 carbon atoms representing between 1 and 80% by volume of said mixture.

The liquid fuel for a boiler or the fuel for a diesel engine is preferably chosen from diesel fuel, domestic fuel oil or kerosene.

The ester (s) with a chain length of between 8 and 14 carbon atoms present in the mixture may be chosen from all esters of this size. It may be preferentially ethyl hexanoate (C8), butyl butyrate (C8), butyl valerate (C9), butyl hexanoate (C12) and / or butyl caprylate (C14).

The alkane (s) with a chain length of between 8 and 14 carbon atoms present in the mixture may be chosen from all the alkanes of this size (connected or unconnected). It may be preferentially decane, dodecane and tetradecane.

According to the invention, the specifically selected esters having a chain length of between 8 and 14 carbon atoms advantageously make it possible to continue to comply with all the current specifications for diesel fuels and boiler fuels, including at a rate of incorporation. between 1 and 8%, except the maximum level of esters since the esters thus produced are not methyl esters of fatty acids complying with the standard EN14214. Also, according to a variant the invention is a mixture as described above wherein the ester (s) chain length of between 8 and 14 carbon atoms represent between 1% and 8% by volume of said mixture. This mixture can be distributed as an unmarked fuel in all dispensing pumps.

In addition, the esters used according to the invention can also be used at higher levels. Also, according to another variant, the invention relates to a mixture as described above in which the ester (s) with a chain length of between 8 and 14 carbon atoms represent between 8% and 80% by volume of said mixture which will be distributed either as an unmarked fuel if it is approved for that purpose or as a fuel for captive transport fleets.

Preferably, the ester (s) of chain length of between 8 and 14 carbon atoms present in the mixture are esters obtained by anaerobic fermentation of volatile fatty acids and esterification with an alcohol.

Similarly, a mixture in which the alkane or alkanes of chain length of between 8 and 14 carbon atoms present in the mixture are alkanes obtained by anaerobic fermentation of volatile fatty acids and electrolysis of Kolbe, as described in US Pat. patent application WO2014170603.

The mixture according to the invention, in addition to the fuel or fuel, esters and alkanes of specific chain lengths, may optionally contain at least one additional additive to improve the cetane number and / or enhance the reduction of particulate emissions. and / or reduce the emissions of nitrogen oxides by the boiler or the diesel engine during its operation. It may be for example tetranitromethane. Other additives may be added to enhance other functionality of the mixture such as cold strength, viscosity, etc.

The mixture according to the invention can be obtained by conventional techniques of the art. Preferably, it is obtained by simply mixing the constituents in the same tank or by mixing two streams in the same pipe. In most countries such a mixture will have to be under the control of the Customs Service.

Surprisingly and advantageously, the mixture according to the invention, incorporating particular esters and alkanes in fuels for diesel engines or in boiler fuels, allows a very significant reduction of particulate emissions without there being any degradation. other emissions, in particular nitrogen oxide and other emissions such as CO, HC, etc. The reduction rate of the particles by mass and by number is of the order of twice the incorporation rate (30 to 40% for 20% incorporation, 60 to 80% for 40% incorporation, 80 to 90% for 50% incorporation), which is a considerable asset for reducing particulate emissions in cities.

The reduction being parallel for the mass and the number of particles, this process does not favor the finest particles which are the most dangerous. The invention therefore specifically relates to the use for supplying a boiler or a diesel engine, of a mixture comprising: at least one liquid fuel for a boiler or a fuel for a diesel engine, and at least one ester with a chain length of between 8 and 14 carbon atoms, and at least one alkane with a chain length of between 8 and 14 carbon atoms, the ester (s) with a chain length of between 8 and 14 carbon atoms representing between 1% and 80% in volume of said mixture and the alkane or alkanes of chain length of between 8 and 14 carbon atoms representing between 1 and 80% by volume of said mixture.

In particular, the invention aims to use the mixture in a boiler or a diesel engine to reduce particulate emissions and / or reduce nitrogen oxide emissions during operation. Advantageously, the invention also makes it possible to improve the cetane number of the fuel.

The mixture according to the invention can be used in any liquid fuel boiler and in any diesel engine, in particular in a fixed diesel engine or a diesel engine installed on transport vehicles or boats or construction machinery or agricultural machinery. or small household gear such as lawn mowers or tillers.

In addition to the mixture according to the invention, at least one additive may be added in the boiler and / or the engine, an additive capable of improving the cetane number and / or enhancing the reduction of particulate emissions and / or reducing the emissions of nitrogen oxides by the boiler or the diesel engine during its operation, and / or at least one additive capable of improving other functionality of the mixture such as cold resistance, viscosity, etc. The invention is now illustrated by examples of mixtures according to the invention and emission test results on a motor bench demonstrating their effectiveness.

The composition of the various mixtures tested is described in the table (Examples 1 to 5 with different loading rates which represent the number of revolutions per minute of the engine compared to the nominal number of revolutions). These mixtures are obtained by simply mixing the components in cans with manual stirring.

The measurements are carried out at the exhaust by a Horiba 9100 (CO, C02, 02, HC and NOx) berry and a PPS PEGASOR particle analyzer on a Renault brand car engine.

The results obtained are shown in the table below:

These results show that alkanes have no significant favorable impact on particle emissions, while esters and alkanes together unexpectedly allow very significant reductions of particles more or less proportional to the ester level (decrease particles of the order of twice the level of incorporated esters) at the same time as a significant decrease of NOx. Example 5 is very demonstrative in this respect.

The other parameters (CO, HC) are not degraded. There is even a significant decline in CO. By adjusting the levels of esters and alkanes, it will thus be possible to optimize the emissions of diesel engines.

Claims (15)

A mixture for supplying a boiler or a diesel engine, comprising: at least one liquid fuel for a boiler or a fuel for a diesel engine, and at least one ester having a chain length of between 8 and 14 carbon atoms, and at least one alkane with a chain length of between 8 and 14 carbon atoms, the ester (s) with a chain length of between 8 and 14 carbon atoms representing between 1% and 80% by volume of said mixture and the alkanes of chain length of between 8 and 14 carbon atoms representing between 1 and 80% by volume of said mixture. 2. Mixture according to claim 1, characterized in that the ester (s) of chain length of between 8 and 14 carbon atoms represent (s) between 1 and 8%. 3. Mixture according to claim 1, characterized in that the ester (s) of chain length of between 8 and 14 carbon atoms represent (s) between 8 and 80%. 4. Mixture according to one of the preceding claims, characterized in that the liquid fuel for the boiler or the diesel engine fuel is chosen from diesel fuel, domestic fuel oil or kerosene. 5. Mixture according to one of the preceding claims, characterized in that the ester (s) of chain length of between 8 and 14 carbon atoms present in the mixture are esters obtained by anaerobic fermentation of volatile fatty acids. and esterification with an alcohol. 6. Mixture according to one of the preceding claims, characterized in that the alkane or alkanes of chain length between 8 and 14 carbon atoms present in the mixture are alkanes obtained by anaerobic fermentation of volatile fatty acids and electrolysis of Kolbe. Mixture according to one of the preceding claims, characterized in that it comprises at least one additional additive capable of improving the cetane number and / or reducing the particulate emissions and / or reducing the emissions of oxides of nitrogen from the boiler or diesel engine in operation. 8. Mixture according to one of the preceding claims, characterized in that it comprises at least one additional additive capable of improving the cold resistance and / or the viscosity. 9. Use of a mixture according to one of the preceding claims for feeding a boiler or a diesel engine. 10. Use according to claim 9 in a boiler or diesel engine to reduce particulate emissions during operation of the boiler or the engine. 11. Use according to claim 9 or 10 in a boiler or a diesel engine to reduce emissions of nitrogen oxides during operation of the boiler or the engine. 12. Use according to one of claims 9 to 11 in a diesel engine for improving the cetane number of the fuel. 13. Use according to one of claims 9 to 12 in a boiler or a diesel engine in which other additives are added to improve the cetane number or enhance the reduction of emissions of particles or nitrogen oxides. 14. Use according to one of claims 9 to 13 in a diesel engine in which other additives are added to improve the cold resistance and / or the viscosity. 15. Use according to one of claims 9 to 14 in a fixed diesel engine or a diesel engine installed on transport vehicles or boats or construction machinery or agricultural machinery or small household gear.