OA16958A - Solid fuel in the form of a powder, including a lignocellulosic component. - Google Patents
Solid fuel in the form of a powder, including a lignocellulosic component. Download PDFInfo
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- OA16958A OA16958A OA1201400324 OA16958A OA 16958 A OA16958 A OA 16958A OA 1201400324 OA1201400324 OA 1201400324 OA 16958 A OA16958 A OA 16958A
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- 239000000843 powder Substances 0.000 title claims abstract description 202
- 239000004449 solid propellant Substances 0.000 title claims abstract description 36
- 238000002485 combustion reaction Methods 0.000 claims abstract description 70
- 238000004519 manufacturing process Methods 0.000 claims abstract description 17
- 239000000446 fuel Substances 0.000 claims description 80
- 239000002245 particle Substances 0.000 claims description 77
- 239000010902 straw Substances 0.000 claims description 60
- 238000000227 grinding Methods 0.000 claims description 48
- 238000000034 method Methods 0.000 claims description 34
- 239000000470 constituent Substances 0.000 claims description 32
- 239000000203 mixture Substances 0.000 claims description 22
- 238000001035 drying Methods 0.000 claims description 17
- 241000196324 Embryophyta Species 0.000 claims description 14
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 14
- 235000013339 cereals Nutrition 0.000 claims description 13
- 239000000725 suspension Substances 0.000 claims description 13
- 239000003039 volatile agent Substances 0.000 claims description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 239000002023 wood Substances 0.000 claims description 10
- PNEYBMLMFCGWSK-UHFFFAOYSA-N AI2O3 Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 8
- XKRFYHLGVUSROY-UHFFFAOYSA-N argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 8
- CURLTUGMZLYLDI-UHFFFAOYSA-N carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 8
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 8
- 239000007788 liquid Substances 0.000 claims description 8
- 239000002699 waste material Substances 0.000 claims description 8
- 239000007789 gas Substances 0.000 claims description 7
- 239000000377 silicon dioxide Substances 0.000 claims description 7
- 235000021307 wheat Nutrition 0.000 claims description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 238000007873 sieving Methods 0.000 claims description 6
- 229910052786 argon Inorganic materials 0.000 claims description 4
- 240000007594 Oryza sativa Species 0.000 claims description 3
- 235000007164 Oryza sativa Nutrition 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 230000001590 oxidative Effects 0.000 claims description 3
- 235000009566 rice Nutrition 0.000 claims description 3
- 244000075850 Avena orientalis Species 0.000 claims description 2
- 235000007319 Avena orientalis Nutrition 0.000 claims description 2
- 241000195493 Cryptophyta Species 0.000 claims description 2
- 240000005979 Hordeum vulgare Species 0.000 claims description 2
- 235000007340 Hordeum vulgare Nutrition 0.000 claims description 2
- 240000002057 Secale cereale Species 0.000 claims description 2
- 235000007238 Secale cereale Nutrition 0.000 claims description 2
- 239000010816 packaging waste Substances 0.000 claims description 2
- 240000008529 Triticum aestivum Species 0.000 claims 1
- 239000002283 diesel fuel Substances 0.000 description 26
- 239000003570 air Substances 0.000 description 23
- 239000002028 Biomass Substances 0.000 description 15
- OKTJSMMVPCPJKN-UHFFFAOYSA-N carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 15
- 238000006243 chemical reaction Methods 0.000 description 14
- 239000003245 coal Substances 0.000 description 14
- 238000009826 distribution Methods 0.000 description 11
- 238000002347 injection Methods 0.000 description 11
- 239000007924 injection Substances 0.000 description 11
- 239000001913 cellulose Substances 0.000 description 10
- 229920002678 cellulose Polymers 0.000 description 10
- 150000001875 compounds Chemical class 0.000 description 9
- 235000010980 cellulose Nutrition 0.000 description 8
- 239000002360 explosive Substances 0.000 description 7
- 235000013305 food Nutrition 0.000 description 7
- 229920005610 lignin Polymers 0.000 description 7
- UDHXJZHVNHGCEC-UHFFFAOYSA-N Chlorophacinone Chemical compound C1=CC(Cl)=CC=C1C(C=1C=CC=CC=1)C(=O)C1C(=O)C2=CC=CC=C2C1=O UDHXJZHVNHGCEC-UHFFFAOYSA-N 0.000 description 6
- 241000209140 Triticum Species 0.000 description 6
- 229920002472 Starch Polymers 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- -1 and the like) Substances 0.000 description 4
- 239000000919 ceramic Substances 0.000 description 4
- 239000003610 charcoal Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 239000002803 fossil fuel Substances 0.000 description 4
- 238000011068 load Methods 0.000 description 4
- 239000002002 slurry Substances 0.000 description 4
- 238000003860 storage Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 239000000835 fiber Substances 0.000 description 3
- 235000013312 flour Nutrition 0.000 description 3
- 150000002430 hydrocarbons Chemical class 0.000 description 3
- 239000003921 oil Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000008107 starch Substances 0.000 description 3
- 235000019698 starch Nutrition 0.000 description 3
- YJISHJVIRFPGGN-UHFFFAOYSA-N 5-[5-[3,4-dihydroxy-6-(hydroxymethyl)-5-methoxyoxan-2-yl]oxy-6-[[3,4-dihydroxy-6-(hydroxymethyl)-5-methoxyoxan-2-yl]oxymethyl]-3,4-dihydroxyoxan-2-yl]oxy-6-(hydroxymethyl)-2-methyloxane-3,4-diol Chemical compound O1C(CO)C(OC)C(O)C(O)C1OCC1C(OC2C(C(O)C(OC)C(CO)O2)O)C(O)C(O)C(OC2C(OC(C)C(O)C2O)CO)O1 YJISHJVIRFPGGN-UHFFFAOYSA-N 0.000 description 2
- 229920002488 Hemicellulose Polymers 0.000 description 2
- 229920000168 Microcrystalline cellulose Polymers 0.000 description 2
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitrogen oxide Substances O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 2
- 229940100445 WHEAT STARCH Drugs 0.000 description 2
- 238000005296 abrasive Methods 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 239000012080 ambient air Substances 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 239000011324 bead Substances 0.000 description 2
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium monoxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000002349 favourable Effects 0.000 description 2
- 235000019813 microcrystalline cellulose Nutrition 0.000 description 2
- 239000008108 microcrystalline cellulose Substances 0.000 description 2
- 229940016286 microcrystalline cellulose Drugs 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000006011 modification reaction Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000001737 promoting Effects 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 238000004642 transportation engineering Methods 0.000 description 2
- 238000004450 types of analysis Methods 0.000 description 2
- 238000004438 BET method Methods 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-N Carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 1
- GUBGYTABKSRVRQ-UUNJERMWSA-N Lactose Natural products O([C@@H]1[C@H](O)[C@H](O)[C@H](O)O[C@@H]1CO)[C@H]1[C@@H](O)[C@@H](O)[C@H](O)[C@H](CO)O1 GUBGYTABKSRVRQ-UUNJERMWSA-N 0.000 description 1
- 240000007817 Olea europaea Species 0.000 description 1
- 241001438449 Silo Species 0.000 description 1
- ZSDSQXJSNMTJDA-UHFFFAOYSA-N Trifluralin Chemical compound CCCN(CCC)C1=C([N+]([O-])=O)C=C(C(F)(F)F)C=C1[N+]([O-])=O ZSDSQXJSNMTJDA-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000002902 bimodal Effects 0.000 description 1
- 239000000292 calcium oxide Substances 0.000 description 1
- 235000014633 carbohydrates Nutrition 0.000 description 1
- 150000001720 carbohydrates Chemical class 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000002817 coal dust Substances 0.000 description 1
- 239000005321 cobalt glass Substances 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 229920001940 conductive polymer Polymers 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000010192 crystallographic characterization Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000001962 electrophoresis Methods 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002708 enhancing Effects 0.000 description 1
- 230000001747 exhibiting Effects 0.000 description 1
- 239000003502 gasoline Substances 0.000 description 1
- 150000004676 glycans Polymers 0.000 description 1
- 238000000892 gravimetry Methods 0.000 description 1
- 239000000383 hazardous chemical Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000004128 high performance liquid chromatography Methods 0.000 description 1
- 239000010903 husk Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atoms Chemical class [H]* 0.000 description 1
- 125000000471 iminomethylidene group Chemical group [H]N=C=* 0.000 description 1
- 238000009616 inductively coupled plasma Methods 0.000 description 1
- 239000003999 initiator Substances 0.000 description 1
- 230000000977 initiatory Effects 0.000 description 1
- 150000002484 inorganic compounds Chemical class 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 201000002161 intrahepatic cholestasis of pregnancy Diseases 0.000 description 1
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 1
- 229910000460 iron oxide Inorganic materials 0.000 description 1
- 239000002655 kraft paper Substances 0.000 description 1
- 239000008101 lactose Substances 0.000 description 1
- GUBGYTABKSRVRQ-XLOQQCSPSA-N lactose Chemical compound O[C@@H]1[C@@H](O)[C@@H](O)[C@@H](CO)O[C@H]1O[C@@H]1[C@@H](CO)O[C@H](O)[C@H](O)[C@H]1O GUBGYTABKSRVRQ-XLOQQCSPSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 230000001264 neutralization Effects 0.000 description 1
- 229910052813 nitrogen oxide Inorganic materials 0.000 description 1
- 239000010742 number 1 fuel oil Substances 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 230000001151 other effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N oxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 239000000123 paper Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 229920001282 polysaccharide Polymers 0.000 description 1
- 239000005017 polysaccharide Substances 0.000 description 1
- 150000004804 polysaccharides Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 229940072033 potash Drugs 0.000 description 1
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Substances [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 1
- 235000015320 potassium carbonate Nutrition 0.000 description 1
- KWYUFKZDYYNOTN-UHFFFAOYSA-M potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 1
- 235000008476 powdered milk Nutrition 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Inorganic materials [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 1
- 230000001340 slower Effects 0.000 description 1
- KEAYESYHFKHZAL-UHFFFAOYSA-N sodium Chemical compound [Na] KEAYESYHFKHZAL-UHFFFAOYSA-N 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011122 softwood Substances 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 230000001131 transforming Effects 0.000 description 1
- 239000011882 ultra-fine particle Substances 0.000 description 1
- 235000013311 vegetables Nutrition 0.000 description 1
Abstract
The present invention relates to a solid fuel in the form of a powder, including at least one lignocellulosic component in the form of a powder. The present invention also relates to the method for preparing said lignocellulosic component in the form of a powder, as well as to the use thereof in the production of a solid fuel intended for an internal combustion engine or a burner. The invention further relates to a method for generating energy using the solid fuel according to the invention.
Description
SOLID FUEL IN THE FORM OF A POWDER, INCLUDING A LIGNOCELLULOSIC COMPONENT
The présent invention relates to a solid fuel, in the form of a powder, comprising at least 5 one lignocellulose constituent in the form of a powder.
The présent invention also relates to the process for the préparation of said lignocellulose constituent in the form of a powder and to its use for the manufacture of a solid fuel intended for an internai combustion engine or for a bumer.
The invention has in addition as subject matter a process for the production of energy 10 employing the solid fuel according to the invention.
In the past, numerous studies hâve been carried out on the development of alternative fuels for internai combustion engines (ICEs) in order to overcome the difïïculties of supplying with oil during the Second World War or during the oil crisis in the 1970s.
Apart from the viewpoint of a crisis in fossil hydrocarbon resources, climate change has 15 led scientists to take an increasing interest in energy drawn from biomass.
The technologies developed for the production of replacement fuels for oil and gas products, for use in engines or bumers, hâve very largely concemed the production of liquid or gas fuels, the latter requiring only little or no modification to engines of gasoline or of diesel type already existing on the world market. These technologies can prove to be expensive and 20 complex.
Added to this are the problème related to the storage and/or transportation of these fuels.
The use of a solid fuel is an advantageous alternative. Thus, the use of mined coal as solid fuel for internai combustion engines has formed the subject of various studies, largely as a resuit of its availability worldwide. Due to the difïïculties in maintaining a homogeneous 25 suspension of coal dust in air (agglomération, blockage), studies carried out since the Second World War hâve focused on minerai coal/diesel oil and minerai coal/water mixtures, the flow and thus the feeding of which to the engine are more easily controllable. This technological choice has made it possible to reduce the constraints occasioned by dry powders. On the other hand, the addition of a stage of production of the mixture (or slurry) to the process has reduced 30 the économie advantage presented by the direct use of a ground crude solid fuel in comparison with the liquid or gaseous synthetic fuels obtained via expensive and complex thermochemica! or bîochemical conversion processes. Furthermore, the studies by Bell S. R. et al. (Fuel, vol. 67, pages 474-481, 1988) conclude that coal-based mixtures or slurries cannot make possible highspeed use of the engines, limiting the field of their applications.
Due to the composition and properties of plant powders, the possibility of directly using biomass, in particular lignocellulose biomass, in engines or bumers, in the fine powder form, ofiers an advantageous alternative to minerai coal. This is because, in contrast to the minerai coal used in the past, the content of abrasive minerai compounds in lignocellulose materials is relatively low, and their volatility is much greater. Thus, the use of lignocellulose materials can reduce the constraints occasioned in an engine by the use of coal in the powder form.
The use of cellulose materials would make it possible in particular to reduce the wear on the engine and to increase the rate and the quality of the combustion.
In addition, the explosive nature of plant powders has been known for a long time (Amyotte P.R. et al.. Journal of Chemical Health and Safety, pages 15-28, 2010). Numerous accidents which hâve occurred in the food processing industry (flour silos, and the like) and wood sawing industry (sawdust) hâve resulted in a large number of studies describing the related explosive phenomena (Abbasi T. et al., Journal of Hazardous Materials, 140, pages 7-44, 2007). The explosive nature of these powders can be advantageous for their use in an engine, if it is controlled.
Studies relating to the use of biomass in the dry powder form in an internai combustion engine hâve recently been described.
WO 01/98438 describes a solid fuel comprising predominantly at least one constituent, which mainly comprises at least one compound selected from the group consisting of starch, lactose, cellulose and at least 15% by weight of carbohydrates with respect to the total weight of the constituent(s) being in the form of a powder, the mean diameter and the médian diameter of the particles of which are greater than or equal to 150 pm, preferably between 150 and 500 pm. The powders given as examples are dried chocolaté powder, dried milk powder and the remilling fraction of a wheat flour. The powders described in this patent application exhibit the disadvantage of competing with the food industry. Furthermore, as they are not able to operate under self-ignition conditions, the powders described in this patent application cannot constitute a solution suitable for many engine applications.
WO 2008/063549 describes fuels in the form of a biomass powder having a relatively heterogeneous particle size distribution, namely less than 5% by weight of the particles hâve a size of greater than or equal to 74 pm and at least 25% by weight hâve a size of less than 44 pm.
The particle size distribution of the powders in this document varies according to the origin of the biomass. For example, in the case of wood particles, less than 5% by weight of the particles hâve a size of greater than or equal to 177 pm and at least 30% by weight hâve a size of less than pm. In the case of soft wood biomass particles, less than 5% by weight of the particles hâve a size of greater than or equal to 297 pm, less than 15% by weight of the particies hâve a size of greater than or equal to 177 pm and at least 20% by weight hâve a size of less than 74 pm. With a powder resulting from herbaceous biomass, less than 5% by weight of the particies hâve a size of greater than or equal to 74 pm, at least 65% by weight of the particies hâve a size of less than 44 pm and at least 25% by weight of the particies hâve a size of less than 37 pm. The heterogeneity in the particle size distribution of the powders in this document may prove to be préjudiciai to satisfactory conversion of these powders into energy and to a quality of combustion suitable for the operation of an engine.
WO 2009/158709 describes methods for the préparation of lignocellulose biomass powders intended for use in combustion. According to the level of energy and of explosiveness desired for the fuel, the powders hâve more or less heterogeneous particle size distributions. For example, for a heating fuel, 5% by weight of the particies hâve a size of greater than or equal to 177 pm and 15% by weight of the particies hâve a size of less than 74 pm. For an explosive fuel, at least 5% of the particies hâve a size of greater than or equal to 74 pm and at least 25% by weight hâve a size of less than 44 pm. In the case of a very high-energy and very explosive fuel, at least 50% of the particies hâve a size of less than 44 pm and at least 15% by weight hâve a size of less than 37 pm. On the basis of this document, it is thus apparent that, the smaller the size of the particies and the less heterogeneous the particle size distribution, the higher the energy and explosiveness of the biomass particies. However, a high explosiveness, in particular when it is not controlled, is not necessarily reflected in a good conversion of the powders into energy and thus a combustion suitable for the satisfactory operation of the engine.
It should be noted that excessively fine lignocellulose biomass powders are not suitable for use in an internai combustion engine. This is because, when the particies are excessively fine, they hâve a tendency to combine together to form agglomérâtes which are harmful to the quality of the combustion of these powders (incomplète and/or slower combustion, more difficult delïvery in the combustion chamber, and the like).
There thus exists a real need for a solid fuel, in the form of a powder, which overcomes the disadvantages of the prior art.
In particular, there exists a real need to develop a solid fuel, in the form of a powder resulting from biomass, intended for an internai combustion engine or for a bumer,
- which makes possible complété and/or rapid conversion of the powder,
- which makes possible better control of the risks related to the high explosiveness of these powders,
- which exhibits better rheologicat characteristics, facilitating the delivery of the fuel in the combustion chamber and also better homogeneity of the explosive ctoud formed in the combustion chamber,
- which makes it possible to reduce the constraints occasioned by the use of a dry fuel, in the powder form, in an engine, such as, for example, the constraints related to the feeding, to the incomplète combustion of the fuel, to the wear on the feeding equipment (pump, injector) and on the moving parts in contact with the fuel or with its combustion residues,
- which can be easily transported and/or stored, and/or
- which can be obtained by inexpensive and simple processes which do not invotve complex thermochemical or biochemical conversion.
It is speciftcally an aim of the présent invention to meet these needs by provîding a solid fuel, in the form of a powder, characterized in that it comprises at least one lignocellulose constituent in the form of a powder (P):
- the mean diameter and the médian diameter (d50) of the particles are less than or equal to 35 pm, preferably between 10 and 30 pm, more preferably between 10 and 20 pm, limits inctuded, and
- the moisture content of the particles of the powder (P) is at most 15% by weight, preferably at most 10% by weight, more preferably less than or equal to 5% by weight and more preferably still less than or equal to 2% by weight of water, with respect to the total weight of the powder (P).
As a result of the smalt size of the particles of the powder (P), or their homogeneous particle size distribution and of their moisture content, the rate of combustion of the fuel according to the invention is high, comparable to that of diesel oil, for example, occasioning a production of energy and/or a release of heat which is also high and comparable to that of diesel oil.
The solid fuels according to the invention thus make possible operation at high rotational speed of the engines.
Furthermore, the characteristics of the powders (P), in particular of size (mean diameter and the médian diameter) and of composition, in particular the moisture content, make possible complété conversion and/or of the solid fuel, in the powder form.
The improved rheological characteristics of the powder (P) make possible easier delivery of the pulvérulent solid fuel according to the invention in the combustion chamber and also better homogeneity of the explosive cloud formed in the combustion chamber.
In addition, the characteristics of the powders (P), in particular of size (mean diameter and the médian diameter) and of composition, in particular the moisture content, make possible high compaction of the pulvérulent solid fuel according to the invention, making it possible to reduce the space necessary for the storage of the latter.
Furthermore, the use of lignocelluloses as engine fuel exhibits the advantage that the CO2 produced does not constitute an environmental surplus, in contrast to that which is discharged by the use of fossil fuels.
Furthermore, the process for the manufacture of the powder (P) according to the invention makes it possible to remain in a “dry-route” die, thus exhibiting the advantage of not generating effluents.
These advantages constitute as many factors favorable to the use of lignocellulose powders (P) according to the invention in internai combustion engines or in bumers.
In the context of the présent invention, the term “lignocellulose constituent is understood to mean a biomass of plant origin, composed of lignin, of hemicellulose and of cellulose in variable proportions. The term “plant origin” comprises ail the compounds produced by living plant organisme.
The lignocellulose constituent of the invention which can be used in the context of the invention can originate from herbaceous plants, algae, microalgae, cereal straw, wood, wood grown for energy purposes, wood resulting from waste (carpentry, construction, and the like), other waste of agricultural origin (olive kernels, rice husks, and the like), paper industry waste, or wood and board packaging waste.
Preferably, the lignocellulose constituent of the invention results from cereal straw, in particular from wheat straw, barley straw, oats straw, rye straw, rice straw or any other straw. One of the advantages of this typology of products is that of not competing with crops having a food purpose since the plant offers both a food use (flours présent in the seed) and a use for energy purposes.
Thus, the fuel according to the invention comprises at least one lignocellulose constituent which comprises:
- at most 100% by weight of lignin, with respect to the total weight of the powder (P),
- at most 100% by weight of cellulose, with respect to the total weight of the powder (P), and
- at most 100% by weight of hemicellulose, with respect to the total weight of the powder (P).
The cellulose can be in its various forms: microcrystalline and/or amorphous.
The mean and médian <dso) diameters of the lignocellulose constituents of the invention were measured by the laser particle size measurement method with a Mastersizer 2000 device from Malvem.
The mean diameter is the diameter calculated by the software of the device and is représentative of the diameter which the particles, the size of which is measured, hâve on average.
The médian diameter (djo) corresponds to the size of the particles at which 50% by weight of the particles constituting the powder (P) and the size of which is measured hâve a lower size and 50% by weight of the particles constituting the powder (P) and the size of which is measured hâve a greater size.
The closer the mean diameter and the médian diameter (dso), the more homogeneous in size the powder for which the size of the particles is measured.
Specifically, the particle size distribution of the powder (P) constituting the fuel of the invention is also an important criterion.
Advantageously, in the présent invention, the particle size distribution of the size of the particles of the powder (P) îs narrow, that is to say that the fuel according to the invention comprises the fewest possible different particle size populations. This means that, in the fuel according to the invention, more than 70% by weight, preferably 80% by weight and more preferably 90% by weight of the powder (P) consists of particles having a mean diameter and a médian diameter (d50) of less than or equal to 35 pm, preferably of between 10 and 30 pm, more preferably between 10 and 20 pm.
As already indicated, the moisture content is another important characteristic of the powder (P).
Within the meanîng of the invention, the term moisture content” is understood to mean the amount of water, expressed as percentage by weight of water, présent in the particles of the powder (P). It is determined by the standard AFNOR XP CEN/TS 14774-3.
As already indicated, the moisture content of the particles of the powder (P) is at most 15% by weight, preferably at most 10% by weight, more preferably less than or equal to 5% by weight and more preferably still less than or equal to 2% by weight of water, with respect to the total weight of the powder (P).
Another advantage of the solid fuel of the invention is its low content of minerai matter, thus generating a low ash content. Thus, the solid fuel according to the invention is characterized in that the lignocellulose constituent in the form of a powder (P) produces, after combustion, at most 10% by weight of ash, preferably between 0% and 10% by weight of ash, more preferably between 0% and 5% by weight and more preferably still between 0% and 1% by weight, limits included, with respect to the total weight of the powder (P).
Within the meaning of the invention, the term “ash” is understood to mean the înorganic basic waste obtained by complété combustion of the solid fuel according to the invention.
The composition of the ash varies according to numerous parameters which dépend essentially on the plant species încinerated, the parts of the plants (bark, trunk or young branches, for example), the nature of the soil and also the period of the year during which these plants were harvested. In the context of the invention, the ash predominantly comprises, for example, calcium oxide, potash, soda, magnésium oxide, silica, alumina, iron oxide and manganèse oxide. Among the inorganic compounds présent, silica and alumina are the most abrasive compounds. Preferably, the solid fuel according to the invention is characterized in that the lignocellulose constituent in the form of a powder (P) comprises, after combustion, at most 3% by weight of alumina, more preferably between 0% and 3% by weight and more preferably still between 0% and 1% by weight, with respect to the initial total weight of the powder (P). As regards the silica content, the solid fuel according to the invention is characterized in that the lignocellulose constituent in the form of a powder (P) comprises, after combustion, at most 3% by weight of silica, preferably between 0% and 3% by weight and more preferably between 0% and 1% by weight, with respect to the initial total weight of the powder (P).
The ash results from the combustion of the lignocellulose constituent of the invention, resulting in the oxidation of the minerai eiements présent in the lignocellulose compounds. Their content is determined by the standard AFNOR XP CEN/TS 14775.
The low content of ash, in particular silica and alumina, reduces the wear on the feeding equipment (pump, injector) and on the moving parts in contact with the fuel or with its combustion residues; it also makes possible better control of the risks related to the high explosiveness of these powders. This results in satisfactory combustion of the fuel, suitable for the operation of an internai combustion engine and/or of a bumer.
One of the advantageous characteristics of the solid fuel of the invention is the high content of volatile matter emitted by the fuel at the beginning of combustion.
In the context of the invention, the term “volatile matter” is understood to mean the condensable or noncondensable gaseous compounds which are emitted by the lignocellulose constituent of the powder (P) during its combustion, in particular at the beginning of its combustion. The beginning of the combustion is generally indicated by the first measurable release of heat. The volatile matter is generally hydrocarbons, hydrogen, carbon monoxide, carbon dioxide, nitrogen oxides, and the like. Depending on the composition of the lignocellulose constituent of the powder (P), the content of volatile matter given off can vary.
Depending on the composition of the lignocellulose constituent of the powder (P), the release of the volatiles can begin at different températures. The lower this température, the sooner the combustion begins.
Preferably, the fuel according to the invention is characterized in that the lignocellulose
S constituent in the form of a powder (P) emîts, in the form of volatiles, at least 50% by weight, preferably between 50% and 70% by weight, more preferably between 70% and 80% by weight and more preferably still between 80% and 100% by weight of volatiles, with respect to the total weight of the powder (P).
The content of volatile matter given off is generally determined by the volatile matter 10 index. This index dénotés the fraction of organic matter volatilized according to the standard AFNOR XP CEN/TS 15148.
The high content of volatile matter makes it possible to improve the quality and the progression of the combustion. The more volatiles there are, the less solid caibon-based waste (charcoal) there is, which bums more slowly than the volatiles. Consequently, the greater the 15 content of volatiles, the greater the portion of the original fuel capable of rapîdly buming.
Another subject matter of the invention is a process for the préparation of a lignocellulose constituent in the form of a powder (P):
- the mean diameter and the médian diameter (djo) of the particles of which are less than or equal to 35 μτη, preferably between 10 and 30 μτη, more preferably between 10 and
20 μιη, limits included, and
- the moisture content of the particles of which is at most 15% by weight, preferably at most 10% by weight, more preferably less than or equal to 5% by weight and more preferably still less than or equal to 2% by weight of water, with respect to the total weight of the powder (P), from cereal straw, comprising at least one stage of grinding cereal straw and optionally at least one drying stage.
The number of grinding stages will dépend, for example, on the nature of the lignocellulose constituent to be ground, on the particle size ofthe powder (P) which it is desired to obtain, on the type of mill used and thus on the efficiency of the grinding.
According to an alternative form of the invention, the process for the préparation of a lignocellulose constituent in the form of a powder (P) comprises the following stages:
(i) a first stage of grinding cereal straw which makes it possible to obtain a powder (A), the mean diameter and the médian diameter (djo) of the particles are greater than 0 and range up to 3000 pm, preferably between 200 and 3000 pm and more preferably between 200 and 2000 pm;
(ii) a second stage of grinding the powder (A) which makes it possible to obtain a powder (B), the mean diameter and the médian diameter (djo) of the particles are less than or equal to 150 pm and preferably less than or equal to 135 pm;
(iii) a third stage of grinding the powder (B) resulting from stage (ii) which makes it possible to obtain a powder (P), the mean diameter and the médian diameter (dso) of the particles are less than or equal to 35 pm, preferably between 10 and 30 pm and more preferably between 10 and 20 pm;
a drying stage being carried out before stage (iii), after stage (iii) or before and after stage (iii).
During stage (i) of the process, the crude cereal straw can be ground by any type of mill which makes it possible to go down to a partide size of greater than 0 and which can range up to 3000 pm, preferably between 200 and 3000 pm and more preferably between 200 and 2000 pm, such as, for example, a knife mill or a hammer mill. The knife mill can be of the Retsch® brand.
The powder (A) resulting from stage (i) can be subjected directly to a second grinding stage (stage (ii)).
Preferably, prior to stage (ii), the partides for which the mean diameter and the médian diameter (dso) are less than 200 pm are removed from the powder (A). These particles can be removed by any séparation means, for example by sieving and/or by a sorting process, such as, for example, an electrostatic sorting process (which makes it possible to sort the particles according to their chemical nature) or an air séparation sorting process (which makes it possible to separate the particles by means of a stream of air). The fraction for which the mean diameter and the médian diameter (dîo) are less than 200 pm corresponds to the extemal part of the stalk which is generally more easily reduced as richer in minerais. Its removal makes it possible to reduce, for example, the ash content.
The powder (A) resulting directly from stage (i) or after the séparation stage is subjected to a second grinding stage (ii). This stage can be carried out using a blade mill, for example such as that of the Hosokawa brand. Alpine 100 UPZ model, rotating at 18 000 revolutions/minute and with a flow rate for introduction of the straw resulting from stage (i) of kg/h. This stage makes it possible to obtain a powder (B) for which the mean diameter and the médian diameter (djo) of the particles are less than or equal to 150 pm, preferably less than or equal to 135 pm.
On conclusion of stage (ii) and prior to stage (iii), the particles for which the mean diameter and the médian diameter (djo) are less than 20 pm can optionally be removed from the powder (B). These particles can be removed by any séparation means, for example by sievîng and/or by a sorting process as described above. The powder (B) can optionally be subjected to sorting with the aim of obtaining a fraction which is more or less rich in lignin and/or in cellulose.
The powder (B) resulting from the stage (ii) can subsequently be dried at a température of between 30 and 120°C, preferably between 50 and 100°C. The drying time can be from 2 to 72 hours, preferably from 4 to 48 hours. On conclusion of this drying stage, the powder (B) exhibits a moisture content of less than 10% by weight, preferably of less than 5% by weight and more preferably still of less than or equal to 2% by weight of water, with respect to the total weight ofthe powder.
The powder (B) is subsequently subjected to a third grinding stage (stage (iii)) in order to obtaîn a powder (P) for which the mean diameter and the médian diameter (djo) of the particles are less than or equal to 35 pm, preferably of between 10 and 30 pm and more preferably between 10 and 20 pm. This stage can be carried out by a slow grinding technique, for example by means of a bail mill, as represented in figure 1, or by a rapid grinding technique, for example by means of an air jet mill, as represented in figure 2.
As represented in figure 1, the bail mill comprises a shell 1 comprising ceramic balls 2 and the product to be ground 3. The shell 1 is rotated in the direction of the arrow. The impacts occasioned 7 by the balls 2 bring about the réduction in particle size of the product 3. The addition of the dotted fine represents the trajectory ofthe balls.
The air jet mill, as represented in figure 2, projects the particles to be ground 3 against one another at very high speed. The collisions between the particles are represented by the arrow
9. Compressed air is injected into the grinding chamber 5 via the nozzles 6. The particles to be ground 3 are introduced by means of the feed pipe 4. The particles 3 are fluidized in the grinding chamber 5. The accelerated particles subsequently mix at the point of convergence, where many air jets also mix with one another. The collisions between the particles generate ultrafine particles.
These grinding methods are well known to a person skilled in the art.
In the case of the bail mill, the duration of this grinding operation can be adjusted to the final particle size desired. The duration of the grinding stage (iii) can be between 1 and
240 hours, preferably between 12 and 216 hours and more preferably still between 48 and
216 hours.
The grinding température at this stage is advantageously less than or equal to 25°C, preferably between -10 and 15QC. These température ranges promote the grinding of the powder (B) as, at these températures, lignocellulose fibers are rigid and thus weaker.
The grinding of the powder (B) can also be promoted by carrying out the grinding in the presence of compounds which weaken said powder. Still with the aim of promoting the grinding on the powder (B), said powder can be subjected to an acidic or basic treatment prior to the grinding or during the grinding.
In order to limit the exposure of the powder obtained (powder (P)) to moisture and/or to the ambient air, the third grinding stage (iii) can preferably be carried out under an inert atmosphère, for example under argon, nitrogen and/or CO2.
As indicated, a drying stage is carried out before stage (iii), after stage (iii) or before and after stage (iii).
The drying, whether it occurs before and/or after stage (iii), is carried out at a température of between 30 and 120QC, preferably between 50 and 100°C. The drying can be carried out for 2 to 72 hours, preferably for 4 to 48 hours.
Advantageously, according to this alternative form, the process of the invention satisfies at least one ofthe following conditions:
- the drying before and/or after stage (iii) is carried out at a température of between 30 and 120°C, preferably between 50 and 100°C,
- the drying before and/or after stage (iii), is carried out for from 2 to 72 hours, preferably from 4 to 48 hours,
- on conclusion of the drying before stage (iii), the powder (B) exhibits a moisture content of less than 10% by weight, preferably of less than 5% by weight and more preferably less than 2% by weight, with respect to the total weight of the powder,
- the duration of the third grinding stage (iii) is between 1 and 240 hours, preferably between 12 and 216 hours and more preferably between 48 and 216 hours,
- the third grinding stage (iii) is carried out at a température of less than or equal to 25°C, preferably between -10 and 15°C,
- the third grinding stage (iii) is carried out under an inert atmosphère which can be composed of argon, nitrogen and/or CO2,
- prior to stage (ii), the particles for which the mean diameter and the médian diameter (d5o) are less than 200 pm are removed from the powder (A) by sieving and/or by a sorting process as described above,
- prior to stage (iii), the particles for which the mean diameter and the médian diameter (djo) are less than 20 pm can optionally be removed from the powder (B) by sieving and/or by a sorting process as described above.
Advantageously, a sélective sorting of the particles resulting from stage (iii) can be carried out by a sorting process as described above, in order to obtain different populations of powders for the purpose of improving their qualities as engine fuel. For example, a population of sorted particles having a greater lignin content and thus a higher calorific value can be selected.
The process according to the invention is simple and économie.
The powder (P) obtained according to the process of the invention can be used directly, without other transformation or treatment, as fuel.
The further subject matter of the invention is the use of a lignocellulose constituent in the form of a powder (P), the mean diameter and the médian diameter (dso) of the particles are less than or equal to 35 pm, preferably between 10 and 30 pm and more preferably between 10 and 20 pm, obtained according to the process of the invention, in the manufacture of a solid fuel intended for an internai combustion engine.
The fuel according to the invention can be used alone or as a mixture with other fuels. It can be used, for example, for the operation of internai combustion engines, whether this is a controlled ignition or diesel engine, or for the operation of turbines, boilers or industrial fumaces involving bumers.
It should be noted that, with the fuels according to the invention, it is possible to replace in an extremely simple way (sending straw powder via the intake) a portion of the diesel oil fed to a diesel engine. This is done without modifying the engine. The problème relating to the injection of the powder or of the mixture (slurry) are thus dismissed and it is ail the same possible to achieve maximum performances of the engines (like those obtained with conventional liquid petroleum fuels), while considerably restricting the consumption of diesel oil.
The fuel of the invention is to be used alone, optionally in suspension, for example in air, în order to produce a combustible mixture. In this case, the proportion of the fuel of the invention în one Iîter of air can then be, for example, 200 mg of fuel in one liter of air. This value is the minimum ignition concentration and can vary according to the composition of the fuel under considération. It corresponds to the stoichiometric value resulting in complété combustion.
The discharges produced during the combustion of the fuel according to the invention do not comprise lead.
The amounts of sulfur discharged by the combustion of a tignocetlulose powder are considerabty restricted in comparison with a fossit fuel. On average, they may be lower by a factor of 10.
The fuel according to the invention can be used without major modification to current internat combustion engines.
The fuel of the invention also has many advantages. It is economically more advantageous than refined petroteum products and liquefied gases, it is available in abundance and it is an indefinitely renewable energy source. It is biodégradable, neutral with regard to the greenhouse effect and easily storable.
This is because, although the composition of the discharges from the combustion of the fuel of the invention includes CO2, like liquid hydrocarbons, the combustion of the fuel of the invention only restores the CO2 absorbed during the growth of the cereats from which the lignocellulose constituent of said fuel originates, in contrast to the products of fossit origin, which displace on a huge scale reserves of carbon from the substratum to the atmosphère.
As regards cereal straws producing grains for the food industry, the straw used does not compete with fuel in terms of avaîlabitity of land.
Furthermore, the handling of the fuels according to the invention présents a minimal danger in comparison with the standard fuels for man.
The présent invention also relates to a process for the production of energy, characterized in that it comprises the stages of:
a) introducing the solid fuel according to the invention in the form of a powder, alone or as a mixture with an oxidizing gas or a liquid fuel in order to form a suspension;
b) passing said fuel or said suspension following a controlled stream close to a source of combustion, and
c) triggering the combustion of said fuel or of said suspension and consuming the solid fuel, in the form of a powder, in order to produce energy.
The energy produced by this process is advantageously thermal energy which may lend itself to any form of conversion.
In this process, the proportion of the solid fuel with respect to the oxidizing gas in the suspension can, for example, be 1 part of solid fuel per 7 parts of gas, by weight.
In this process, the term “controlled stream” is understood to mean the flow rate of the solid fuel in the powder form. By adjusting the flow rate of the solid fuel, the production of energy can be adjusted.
Other advantages and characteristics of the présent invention may also become apparent on reading the examples below, given by way of illustration, and the appended figures.
- Figure 1 represents a schematic diagram of the bail mill. This type of grinding consists in rotating a shell 1 containing ceramic balls 2 and the product to be ground 3. The impacts occasioned by the balls bring about the réduction in particle size of the product.
- Figure 2 represents a schematic diagram of the air jet mill. This type of grinding consists in projecting the particles to be ground against one another at very high speed.
- Figure 3 represents the progression of the various stages of the alternative form of the process according to the invention as described in ex ample 1.
- Figure 4 represents the comparative pressures of the straw according to the invention, of the diesel oîl and of those obtained in the absence of fuel, measured in the cylinder of the engine during the operating cycle, at 790 revolutions/minute, 13 Nm (in joules/CD). The pressure, expressed in bar, is represented on the ordinale and the displacement of the piston, expressed in crankshaft degrees (CD), is represented on the abscissa.
- Figure 5 represents the degree of release of heat (on the ordinate and expressed in joules/CD), calcuîated on the basis of the pressure cycles obtained in the absence of fuel, with injection of diesel oil and with feeding, via the intake, of powder only, the displacement of the piston, expressed in crankshaft degrees (CD), is represented on the abscissa.
-Figure 6 represents the diagrams of pressure (on the ordinate and expressed in bar) as a function of the volume (on the abscissa and expressed in m3) obtained for the diesel oil and the straw according to the invention at 790 revolutions/minute, 13 Nm.
EXAMPLES
EXAMPLE 1: Process for the préparation of straw powders according to the invention
Wheat straw was selected as an advantageous dry biomass source due to its high availability and its residual nature. As the rate of combustion is under the direction of the ftneness of the material, it is a matter of grinding, down to the micron scale, a batch of straw originating from the Tarn région (81430 Le Fraysse).
The operations of grinding the wheat straw took place in several stages as represented in figure 3, starting from the original baie. The straw was first of all ground with the knife mil!
(Retsch SM 100). This operation made it possible to reduce the size ofthe particles and to obtain particles for which the mean diameter and the médian diameter (djo) are greater than 0 and range up to 2000 microns. The ash content was reduced by sieving, the fraction of less than
200 microns, which corresponds to the extemal part ofthe stalk, which is more easilyreduced as richer in minerais, being removed.
During a second grinding stage, the straw was fed to a Hosokawa Alpine 100UPZ blade mill at ambient température (approximately 20°C). This operation made it possible to reduce the size of the particles down to approximately one hundred microns (the mean diameter and the médian diameter (dso))·
The product obtained, dried at 60°C for 48 h, was subsequently used as basis for the successive grinding operations; it will subsequently be referred to as “powder B”. The drying stage was carried out under air in an Memmert oven, 100-800 model.
In order to be able to evaluate the impact of the type of grinding on the combustible qualities of the straw, two technologies were compared: bail grinding, slow but relatively simple 10 to carry out, and air jet grinding, which is faster and more complex.
In both cases, particles with a mean diameter and a médian diameter (dso) of 10 and 20 microns were obtained.
Bail mill
This type of grinding, represented diagrammatically in figure 1, consists in rotating a 15 shell 1 containing ceramic halls 2 and the product to be ground 3. The impacts occasioned by the balls 2 bring about the réduction in particle size of the product.
The bail mill used is the Marne 0 No. 55 model distributed by Faure.
The operations took place in a cold chamber, maintained at 5°C. The shell, containing 1/3 of powder B, 1/3 of alumina balls and 1/3 of air by volume, were subjected to a rotation of 20 1 revolution/second in installments of 24 h, on conclusion of which a sample was withdrawn. In order to minimize the exposure of the product to the moisture of the ambient air during the withdrawal operations, the air was replaced with argon; the other effect being to control the oxidation of the product.
The grinding operation takes place as follows: one kilogram of straw powder (B) is 25 inserted into an 8 Iiter ceramic shell in the presence of 4 kilograms of alumina balls with a diameter of 17 mm and of 4 kilograms of balls with a diameter of 25 mm. After 48 hours, the balls are changed for 4 kilograms of beads with a diameter of 9 mm and 4 kilograms of beads with a diameter of 7 mm. This has the effect of optimizing the grinding by reducing the space between the balls and by thus enhancing the impacts occasion!ng the grinding.
Starting from one kilogram of powder B, a powder for which the particles hâve a mean diameter and a médian diameter (dso) of 20 microns was obtained in 48 to 72 hours and of 10 microns in 216 hours (i.e., 9 days).
Air jet mill
/.
This type of grînding, represented diagrammatically in figure 2, consists in projecting the particies to be ground against one another at very high speed. This technology offers the advantage of not influencing the chemical characteristics of the material.
The air jet mill used is the 100 AFG model from Hosokawa Alpine.
Particies having a mean diameter and a médian diameter (dso) of 20 microns were obtained with a feed rate of 700 g/hour approximately (i.e., 20 revolutions/minute for the hopper) and a rotational speed ofthe selector of6000 revolutions/minute.
Particies having a mean diameter and a médian diameter (d50) of 10 microns were obtained at 200 g/hour approximately (i.e., 6 revolutions/minute for the hopper) and the selector adjusted to 12 000 revolutions/min.
Characterization of the powders
The straw powders obtained on conclusion of the second grînding stage (blade mill) and on conclusion of the third grînding stage with a bail mill (ball-10 straw and ball-20 straw) and with an air jet mill (air jet-10 straw and air jet-20 straw) were characterized, compared with one another and compared with the following commercial plant powders:
• microcrystalline cellulose (Serva-Electrophoresis), crystalline parts of the cellulose portion of plant fibers, médian diameter 23 microns (djo) and not very dispersed;
• α-cellulose (Sigma-Aldrich), amorphous part of the cellulose portion of the plant fibers, connecting together with crystalline régions, médian diameter 65 microns (djo);
• lignin (Sigma-Aldrich), obtained by the kraft process, with a high content of sodium and approximately 3% of sulfur, médian diameter 100 microns (djo);
• wheat starch (Prolabo), quasispherical grains, diameter 23 microns (djo) and not very dispersed;
• com starch (Maîzena), spherical grains, médian diameter 20 microns (dso).
A noncommerciai powder was also used:
• Ultracarbofluid (vegetable charcoal dry residue used as a slurry); bimodal particle size distribution (probable agglomération of particies having a médian diameter (djo) of 18 microns to give clusters of 350 microns).
These combined powders hâve formed the subject of the following analyses:
• elemental (Thermal Electron Flash EA 112 CHN analyzer) • immédiate (biomass standards moisture content: AFNOR XP CEN/TS 14774-3; volatiles: AFNOR XP CEN/TS 15148; ash: AFNOR XP CEN/TS 14775) • chemical analysis of the polysaccharides and lignins (HPLC, GLC, gravimetry) • chemical analysis of the ash (Inductively Coupled Plasma or ICP method Varian CCD detector) • particle size (Mastersizer 2000 - Malvem) • thermogravimetric (modified Sartorius) • spécifie surface (BET method on Tristar 3000 — Micromeritics)
The results of these analyses are given in the following table 1. These results clearly show that the straw powders of the invention:
- exhibit a reduced particle size distribution favorable to rapid and homogeneous combustion suitable for engines;
- exhibit a high content of volatiles in comparison with the known minerai coals, thus promoting rapid combustion;
- the ash content of which is reduced in comparison with the known minerai coals, which results in a low degree of wear of the combustion system under considération.
Conclusions
The fuel powders according to the invention do not compete with the food industry in tenus of use of agriculture! land.
The fuel powders according to the invention cause lower wear to the Systems used for their conversion into energy, in contres! to the coal powders used in the past.
In contrast to coal powders, the fuel powders according to the invention make possible better control of the risks related to their handling by virtue of their spécifie rheological properties.
The fuel powders according to the invention make possible optimized storage by virtue of their particle size properties (low dispersion and size of about a micron), allowing them to be compacted.
Contrary to coal powders, which require stirring in order to maintain a suspension, the fuel powders according to the invention do not require improved storage conditions.
The production of the fuel powders according to the invention does not require high processing costs for the purpose of their conversion into energy.
The production of the fuel powders according to the invention does not require the use of complex grinding technologies.
The production of the fuel powders according to the invention is consequently possible at reduced cost and in a simple way, which extends the field of their use to developing countries and to isolated régions, whatever they are, in contrast to fossil fuels, whatever they are, including coal powders.
The production by simple dry-route grinding of the fuel powders according to the invention does not generale liquid or gaseous effluents which impact the environment
The conversion into energy of the fuel powders according to the invention does not add
CO2 to the environmental balance, in contrast to fossil fuels, whatever they are, including coal powders.
The conversion into energy of the fuel powders of the invention does not generate or generates little in the way of sulfur-comprising compounds, in contrast to fossil fuels, whatever they are, and in particular coal powders.
The conversion into energy of the fuel powders according to the invention in an internai 10 combustion engine applies to high-speed applications and in particular transportation, in contrast to coal powders.
The conversion into energy of the fuel powders according to the invention in an internai combustion engine can apply to high-power applications, in contrast to coal powders, in particular in suspension.
| Table 1 | |||||||||||||
| Partide size distribution (pm) | Elemental analysis (by weight on an ash-free dry basis) | Silica and alumina content (by weight on a dry basis) | Spécifie surface (ΒΕΓ) ln m -g | ||||||||||
| Product | Moisture content %by weight on the crude basis | Volatiles %by weight on the crude basis | Ash content %by weight on the crude basis | dio | d» | dH | %C | %H | %O | %N | SiO, (Xby weight) | Al (ppm) | |
| Com starch | 11.5 | 87.0 | 0.1 | 8 | 18 | 36 | 43.3 | 7.8 | 48.8 | <0.1 | - | - | <1 |
| Wheat starch | 11.2 | 86.5 | <0.01 | 12 | 23 | 38 | 44.6 | 7.7 | 47.6 | <0.1 | 0.008 | 3.5 | <1 |
| Lignin, alkali | 9.9 | 60.0 | 20.0 | 52 | 102 | 187 | 69.7 | 7.3 | 22.9 | 0.1 | 0.03 | 53.0 | - |
| Microcrystalline cellulose | 4.5 | 91.2 | <0.01 | 6 | 23 | 52 | 44.2 | 6.7 | 49.0 | <0.1 | 0.008 | 11.2 | <1 |
| a-Cellulose | 5.8 | 85.0 | 0.1 | 17 | 65 | 271 | 45.0 | 6.9 | 48.0 | 0.1 | 0.007 | 2.4 | - |
| Powder (P) | <2.0 | 76.0 | 6.1 | 4 | 20 | 71 | 48.1 | 6.3 | 45.1 | 0.5 | 2.93 | 201.3 | <2 |
| Chocolaté | 4.5 | 72.0 | 2.4 | 50 | 134 | 330 | 43.6 | 6.9 | 48.7 | 0.8 | - | - | - |
EXAMPLE 2: Engine test rig
The engine on the test rig is a 4 stroke single cylinder direct injection Hatz 1D80 diesel model, with a cylinder of 667 cm3 and with a compression ratio of 18. This engine is equipped with an eddy current electromagnetic break.
it is equipped with a cylinder pressure sensor (Kistler 6125b mode!) which retums a 010V signal over a range extending from 0 to 250 bar.
An injection pressure sensor (Kistler 4067B2000) is fitted to the feed pipe of the injector. In the présent case, the injection pressure does not constitute a dominating parameter; it is given with the sole aim of indicating the presence or the absence of diesel oil.
An angle encoder (Kistler 2614A) is fitted to the shaft of the engine. It retums one blip per révolution, which is positioned to correspond to top dead center (TDC), and one blip per half-degree of crank angle, which is used to dock the acquisition.
The LabView 2010 software is used for the data acquisition. The pressures and températures and also the speed and the torque are recorded therein and displayed as a function of the acquisition point.
The different modes of feeding the powder to the engine were as follows:
• using a weight metering hopper which feeds a fixed flow rate of powder to the intake. The K-Tron (KT20) hopper model was used during the tests for feeding powder alone continuously, • in duel fuel mode, i.e.: powder in the intake + diesel oil injection, • by injection of lignocellulose powder/diesel oil mixture (suspension).
2.1. Continuous feeding
Further to the setup of the K-Tron KT20 model gravimétrie metering hopper, we were able to feed the motor with a continuous flow rate of powder according to the invention at 4 kg/h approximately, i.e. the stoichiometric amount for a rotation of the engine at 1000 révolutions per minute.
These tests hâve allowed us to drive the engine with the powder alone and for several hundred consecutive cycles, which corresponds to several minutes.
The tests which led to the most significant results are given below.
The pressure profiles measured in the cylinder of the engine during the operating cycle brought about by the straw alone according to the invention and the diesel oil are compared in figure 4. Although the maximum pressure achîeved in operation with the diesel oil is markedly greater than that of the straw, both exhibit a very different profile. A double pressure peak related to the combustion of the straw according to the invention should be noted, and also a “train” brought about by the combustion of the residual charcoal.
Figure 5 represents the release of heat calculated on the basis of the pressure cycles obtained in the absence of fuel, with injection of diesel oil and with feeding via the intake of straw powder alone. The release of heat gives the amount of heat emitted by the combustion of the straw according to the invention and of the diesel oil in joules/CD and as a fonction of the time. In order to be able to locate the various phases of this release in the rotational cycle of the engine, this time is given in crankshaft degrees (CD). These data were obtained at idling (790 revolutions/minute) and at light load (13 Nm), i.e. at a mean température of 150°C in the combustion chamber, with diesel oil in normal operation and straw powder according to the invention (mean diameter and médian diameter (djo) of 20 microns) obtained with the air jet mill as described in example 1.
First of ail, there occurs a sizable release of heat with the straw according to the invention as foel and this release extends as far as the opening of the exhaust valve (approximately 125 CD). This significant release makes possible the recovery of the energy of the straw in mechanical form. The total amount of energy released is comparable to that resulting from the release of heat obtained with diesel oil.
The offset in time of the release of heat occasioned by the straw according to the invention with respect to that of the diesel oil can be explained as follows: the time necessary for the combustion of a solid partide is longer than that of a droplet of liquid, were it of the same size. This is because, in addition to the évaporation phase which gives rise to the volatile compounds, initiators of the combustion, a solid requires a drying time (on this scale, the time for transfer of heat from the surface to the interior of the partide can be neglected). The drying stage is in fact a critical parameter which considerably slows down the initiation of the combustion.
Furthermore, the product from the devolatilization of the straw partide is charcoal, which bums more slowly (the diffusion of the oxygen into its pores controls the combustion). This explains the extension of the release of heat over time.
The calculation of the work indicated for each of these pressure cycles corroborâtes this observation. This work is obtained by studying the diagram of cylinder pressure as a fonction of the volume, as represented in figure 6.
The calculation ofthe areas ofeach ofthe cycles proves that the work provided by the straw powder according to the invention is suffîcient to bring about driving of the engine. This is because the combustion of the straw releases 300 joules, versus 250 for the diesel oil. It should be noted that the Net Calorific Values ofthe air/straw or air/diesel oil stoichiometric mixtures are very similar (respectively 2.4 MJ/kg and 2.7 MJ/kg).
2.2, în dual fuel mode
During these tests, the wheat straw used (djo=2O pm) is obtained with the bail mill as described in example 1.
During the tests, the injection of diesel oil was maintained at a known operating point: 1250revolutions/minute and 10% of the maximum acceptable load (torque of 3.6 Nm with regard to the 36 Nm maximum). For this précisé operating point, the diesel oil consumption was approximately 250 g/h. The powder was fed by virtue of the hopper (cf. § 2.2.) via the intake pipe. In this way, the variations in speed or in torque brought about can only be attributed to the powder alone.
1- In torque régulation, that is to say that the torque applied to the shaft of the engine (by the braking system) is maintained at 3.6 Nm. Any form of additional energy introduced into the engine results in an increase in speed.
From the first seconds of introduction of the powder, the engine accelerates very rapidly to reach 3000 and then 3200 revolutions/minute (2 tests). As the maximum speed given by the manufacturer for the engine is exceeded, the test was halted.
Conclusion: the rate of combustion of the straw powder does not lïmit the speed of the engine, at least up to 3200 revolutions/minute.
2- In régulation of speed, that is to say that the rotational speed of the engine is limited to the value of 1250 revolutions/minute. Any form of the additional energy introduced into the engine requires the system to brake, in conséquence of which the torque increases. This increase in load can be directly related to the work which the engine can provide and thus to the effort which it can sustain.
During the test, the engine goes up to 34 Nm, i.e., more than 90% of the maximum torque accepted for diesel oil.
Conclusion: the energy given off by the combustion of the straw powder allows operation at high loads. This is essentiel for any type of application envisaged.
It should be noted that, with the powders according to the invention, it is possible to replace in an extremely simple way (sending straw powder via the intake) a portion of the diesel oil fed to a diesel engine. This is done without modifying the engine. The problems relating to the injection of powder or of mixture (suspension) are dismissed and it is ail the same possible to achieve entirely advantageous performances, while considerably restrictîng the consumption of diesel oil (which remains at 250 g/h in this particular case).
Example 3: Comparative test between the powder (P) and powdered chocolaté
A comparative test was carried out with the engine described in example 2. Wheat straw ground to 20 microns (powder (P) according to the invention) was compared with commercial powdered chocolaté, the particie size of which is similar to that used in the application WO 01/98438 (cf. table 1).
The conditions of the test were as follows: the engine is started with diesel oil and stabilized at 1000 revolutîons/minute at zéro load, the powder is fed via the intake pipe at a flow rate of 4 kg/h and feeding with diesel oil is halted.
During the test with the chocolaté powder, the motor stopped as soon as the injection of diesel oit was halted. Restarting was difficult, even though a few grams at most had been sucked in.
lmmediately after restarting and without cleaning the engine, the consecutive test was carried out with straw powder according to the invention (powder (P)), under the same conditions. During this test, the motor continued to operate, fed solely with straw powder, this being the case over several minutes.
On the basis of these results, it is clearly apparent that a fuel in the form of a powder, the particie size distribution of which is similar to that used in the application WO 01/98438, does not operate under self-ignition conditions and consequently cannot constitute a solution appropriate for many engine applications.
Conclusion
Contrary to the powders for which the particie size and the composition are similar to that used in the application WO 01/98438, the fuel powders according to the invention do not compete with the food industry.
Furthermore, the fuel powders according to the invention are suitable for use in any type of internai combustion engine for their conversion into energy, in contrast to the chocolaté powders used in the application WO 01/98438.
Claims (12)
1. A solid fuel, in the form of a powder, characterized in that it comprises at least one lignocellulose constituent in the form of a powder (P):
- the mean diameter and the médian diameter (djo) of the particles are between 10 and 30 pm, more preferably between 10 and 20 pm, limits included, and
- the moisture content of the particles is less than or equal to 5% by weight and more preferably less than or equal to 2% by weight of water, with respect to the total weight of the powder (P).
2. The fuel as claimed in claim 1, characterized in that more than 70% by weight, preferably 80% by weight and more preferably 90% by weight of the powder (P) consists of particles having a mean diameter and a médian diameter of between 10 and 30 pm, more preferably between 10 and 20 pm, limits included.
3. The fuel as claimed in either of claims 1 and 2, characterized în that the lignocellulose constituent in the form of a powder (P) produces, after combustion, at most 10% by weight of ash, preferably between 0% and 10% by weight of ash, more preferably between 0% and 5% by weight and more preferably stîll between 0% and 1% by weight, limits included, with respect to the total weight of the powder (P).
4. The fuel as claimed in any one of claims 1 to 3, characterized in that the lignocellulose constituent in the form of a powder (P) comprises, after combustion, at most 3% by weight of alumina, more preferably between 0% and 3% by weight and more preferably still between 0% and of 1% by weight, with respect to the initial total weight ofthe powder (P).
5. The fuel as claimed in any one of claims l to 4, characterized in that the lignocellulose constituent in the form of a powder (P) comprises, after combustion, at most 3% by weight of silica, preferably between 0% and 3% by weight and more preferably between 0% and 1% by weight, with respect to the initial total weight of the powder (P).
6. The fuel as claimed in any one of claims 1 to 5, characterized in that the lignocellulose constituent in the form of a powder (P) emits, in the form of volatiles, at least 50% by weight, preferably between 50% and 70% by weight, more preferably between 70% and 80% by weight and more preferably still between 80% and 100% by weight of volatiles, with respect to the total weight of the powder (P).
7. The fuel as claimed in any one of claims l to 6, characterized in that the lignocellulose constituent originates from herbaceous plants, algae, microalgae, cereal straw, wood, wood grown for energy purposes, wood resulting from waste, other waste of agricultural origin, paper industry waste, or wood and board packaging waste.
8. The fuel as claimed in any one of claims 1 to 7, characterized in that the lignocellulose constituent results from cereal straws, in particular from wheat straw, barley straw, oats straw,
5 rye straw or rice straw.
9. A process for the préparation of a lignocellulose constituent in the form of a powder (P):
- the mean diameter and the médian diameter (dso) of the particles of which are between 10 and 30 pm, more preferably between 10 and 20 pm, limits included, and
- the moisture content of the particles of which is less than or equal to 5% by weight and
10 more preferably still less than or equal to 2% by weight of water, with respect to the total weight ofthe powder (P), characterized in that it comprises the following stages:
(i) a first stage of grinding cereal straw which makes it possible to obtain a powder (A), the mean diameter and the médian diameter (dso) of the particles are greater than 0
15 and range up to 3000 pm, preferably between 200 and 3000 pm and more preferably between 200 and 2000 pm;
(ii) a second stage of grinding the powder (A) which makes it possible to obtain a powder (B), the mean diameter and the médian diameter (dso) of the particles are less than or equal to 150 pm and preferably less than or equal to 135 pm;
20 (iii) a third stage of grinding the powder (B) resulting from stage (ii) which makes it possible to obtain a powder (P), the mean diameter and the médian diameter (dso) of the particles are between 10 and 30 pm and more preferably between 10 and 20 pm;
a drying stage being carried out before stage (iii), after stage (iii) or before and after stage (iii).
25 10. The process as claimed in daim 9, characterized in that it satisfies at least one of the following conditions:
- the drying before and/or after stage (iii) is carried out at a température of between 30 and 120°C, preferably between 50 and 100°C,
- the drying before and/or after stage (iii), is carried out for from 2 to 72 hours, preferably
30 from 4 to 48 hours,
- on conclusion of the drying before stage (iii), the powder (B) exhibits a moisture content of less than 5% by weight and more preferably less than 2% by weight of water, with respect to the total weight of the powder,
- the duration of the third grinding stage (iii) is between ! and 240 hours, preferably between 12 and 216 hours and more preferably between 48 and 216 hours,
- the third grinding stage (iii) is carried out at a température of less than or equal to 25°C, preferably between -10 and 15°C,
- the third grinding stage (iii) is carried out under argon, nitrogen and/or CO2,
- prior to stage (it), the particles for which the mean diameter and the médian diameter (djo) are less than 200 pm are removed from the powder (A) by sieving and/or by a sorting process,
- prior to stage (iii), the particles for which the mean diameter and the médian diameter (djo) are less than 20 pm are optionally removed from the powder (B) by sieving and/or by a sorting process.
11. The use of a lignocellulose constituent in the form of a powder (P), the mean diameter and the médian diameter of the particles are between 10 and 30 pm, more preferably between 10 and 20 pm, limits included, obtained as claimed in either of claims 9 and 10, in the manufacture of a solid fuel intended for an internai combustion engine or for a bumer.
12. A process for the production of energy, characterized in that it comprises the stages of:
a) introducing the solid fuel, in the form of a powder, as claimed in any one of claims 1 to 8, alone or as a mixture with an oxidizing gas or a liquid fuel in order to form a suspension;
b) passing said fuel or said suspension following a controlled stream close to a source of combustion, and
c) triggering the combustion of said fuel or of said suspension and consuming the solid fuel, în the form of a powder, in order to produce energy.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR1250511 | 2012-01-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| OA16958A true OA16958A (en) | 2016-01-25 |
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