CARBONACEOUS MATERIAL SUSPENSION

Abstract

The present invention concerns a suspension comprising carbonaceous material particles, an alkoxylated phenol surfactant, and an aqueous liquid phase providing a high stability to the suspensions over time. The invention also concerns a process for the production of said suspensions and methods for generating power comprising combustion of said suspensions, notably with appropriate devices.

Claims

1. A suspension comprising: (a) carbonaceous material particles having an average diameter D50 between 0.1 and 100 m; (b) an alkoxylated phenol surfactant; and (c) an aqueous liquid phase.

2. A suspension according to claim 1 wherein carbonaceous material particles are chosen in the group consisting of: coal, coke, graphite, char, and biocoal.

3. A suspension according to claim 1 wherein carbonaceous material particles comprise torrefied biomass.

4. A suspension according to claim 1 wherein carbonaceous material particles comprise torrefied wood.

5. A suspension according to claim 1 wherein carbonaceous material particles provide the size distribution as follows: D.sub.10 between 1 and 30 m, D.sub.50 between 0.1 and 100 m, and D.sub.90 between 50 and 200 m.

6. A suspension according to claim 1 wherein the alkoxylated phenol surfactant comprises between 2 and 100 oxyalkylene units.

7. A suspension according to claim 1 wherein the alkoxylated phenol surfactant comprises one, two or three linear or branched hydrocarbon group(s).

8. A suspension according to claim 7, wherein the each of the one, two, or three hydrocarbon groups is selected from the group consisting of: alkyl groups, aryl groups, alkylaryl groups, and aryalkyl groups, that may optionally comprise a heteroatom such as N, O or S.

9. A suspension according to claim 1, wherein the alkoxylated phenol surfactant comprises a functional group that is connected to the alkoxylated chain and selected from the group consisting of: PO.sub.4.sup.M.sup.+, SO.sub.4.sup.M.sup.+, SO.sub.3.sup.M.sup.+ or COO.sup.M.sup.+; wherein M.sup.+ is a cation.

10. A suspension according to claim 1, wherein the alkoxylated phenol surfactant is a compound according to formula (I):
(R.sub.1)(R.sub.2)(R.sub.3)Phe-(OX).sub.nR (I) wherein Phe is phenyl and: R.sub.1 R.sub.2 and R.sub.3 are each independently a hydrogen or a linear or branched hydrocarbon group; X is a divalent linear or branched alkylene radical comprising from 2 to 8 carbon atoms; n is an integer comprised between 2 and 100; R is H, OH, alkoxy group, PO.sub.4.sup.M.sup.+, SO.sub.4.sup.M.sup.+, SO.sub.3.sup.M.sup.+ or COO.sup.M.sup.+; and M.sup.+, if present, is a cation.

11. A suspension according to claim 1, wherein the alkoxylated phenol surfactant in selected from the group consisting of: alkoxylated alkylphenol, alkoxylated alkylarylphenol, alkoxylated sulfated and/or phosphate alkylphenol and alkoxylated sulfated and phosphate alkylarylphenol.

12. A suspension according to claim 1, wherein said suspension comprises from 0.01 to 5% by weight of the alkoxylated phenol surfactant, by weight of dry carbonaceous material particles.

13. A suspension according to claim 1, wherein the liquid phase of said suspension comprises water, water/water-miscible organic liquid mixture, and/or a blend of water and an organic liquid or mixture thereof.

14. A suspension according to claim 1, wherein the liquid phase comprises an organic liquid which is an energy carrier liquid derived from petroleum products or an energy carrier liquid derived from biomass and/or fossil reagents.

15. A suspension according to claim 1 wherein the liquid phase of the suspension is water or a water/water-miscible organic liquid mixture, and said suspension exhibits a viscosity between 1 and 5000 mPa.s, at a temperature of 20 C.

16. A suspension according to claim 1 wherein said suspension further comprises a pseudoplastic water-soluble polymer.

17. A suspension according to claim 16 wherein the pseudoplastic water-soluble polymer is a polysaccharide or polysaccharide derivative.

18. A suspension according to claim 16, wherein pseudoplastic water-soluble polymer is selected from the group consisting of: polyacrylic acids, xanthan gums, cellulose, and cellulose ethers.

19. A Process for the preparation of a suspension according to claim 1 by mixing at least components (a), (b) and (c).

20. A process for the preparation of a suspension according to claim 19, wherein the mixing comprises milling under wet conditions.

21. A method for improving the stability over time of a suspension, comprising adding an alkoxylated phenol surfactant to a suspension comprising a carbonaceous material particles having an average diameter D50 comprised between 0.1 and 100 m and an aqueous liquid phase.

22. A method for generating power comprising combusting the suspension according to claim 1.

23. The suspension 18, wherein pseudoplastic water-soluble polymer is selected from the group consisting of hydroxypropylmethyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, and sodium carboxy methyl cellulose.

Description

EXPERIMENTAL PART

[0141] Compounds used in the following examples are as follows: [0142] Torrefied wood chips: 28 GJ/Ton, 10% RH, feedstock origin, from New Biomass Energy LLC [0143] Soprophor 4D360 provided by Solvay: sulfated polyarylphenol ethoxylate, NH.sub.4 salt [0144] Soprophor 796P provided by Solvay: ethoxylated propoxylated polyarylphenol [0145] Soprophor BSU provided by Solvay: alkoxylated polyarylphenol [0146] Soprophor CY/8 provided by Solvay: ethoxylated tristyrilphenol [0147] Soprophor FL provided by Solvay: ethoxylated polyarylphenol phosphate amine salt [0148] Soprophor S25 provided by Solvay: tristyrylphenol ethoxylate, HLB=14.5 [0149] Igepal CO-887 EP provided by Solvay: nonylphenol ethoxylate

[0150] Ages Rhodasurf BC 420: tridecylalcohol ethoxylate (3OE) Xanthan gum Rhodigel USP

Example 1

Preparation of Torrefied Wood Particles

[0151] The torrefied wood chips obtained from a torrefactor process and having cm scale was first grinded by dry grinding process to obtain 300 m to 1 mm particle size. Then, this powder is dried milled by Retsch ZM200 dry miller with the following characteristics: grid 120 m, speed 18000 rpm, 25 C., nitrogen purge, 80 g per batch in 10 min; to obtain particle size distribution centered at 25 m as followed: [0152] D.sub.10=6 m [0153] D.sub.50=23 m [0154] D.sub.90=60 m
These size distributions are measured with Sympatec laser diffraction sensors.

Example 2

Water Slurries Preparation

[0155] Water slurries are prepared by mixing 1% wt of torrefied wood particles as obtained in Example 1 with water in vials with a micro-dosing machines Mettler-Toledo (Quantos). On an automated platform 1% wt of surfactants are added within the vials and each solution is then vortexed during 30 s.

Example 3

Time Stability Trials

[0156] Each 30 minutes water slurries as prepared in Example 2 were brought then by a robotic arm to a camera to take a picture. The stability is characterized by the absence of demixing/settling in samples after 6 hours of static storage in vials placed at 25 C.

[0157] Results are mentioned in the following Table 1:

TABLE-US-00001 TABLE 1 Visual aspects of formulations Surfactants after 6 hours C1. No surfactant Heavy sedimentation C2. Ages Rhodasurf BC 420 Sedimentation 1. Soprophor 4D360 Dispersion 2. Soprophor 796P Dispersion 3. Soprophor BSU Dispersion 4. Soprophor CY/8 Dispersion 5. Soprophor FL Dispersion 6. Soprophor S25 Dispersion 7. Igepal C0-887 EP Dispersion Dispersion: corresponds to a monophasic aspect Sedimentation: corresponds to a biphasic aspect

[0158] It appears then that the polyalkoxylated phenol surfactants of the present invention permit to provide a sufficient stability to the suspensions.

[0159] The term stability as used herein includes static and dynamic stability and as applied to a carbonaceous material particles slurry means the capability of the slurry to maintain its level of homogeneity over a selected period of time, such as, for example, a time measured from formation of the slurry with its particles dispersed to the time at which the slurry tends to undergo a change in its rheological properties. The term stability implies that the physical state of the slurry will not readily change or undergo fluctuations which would impair its use.

Example 4

Time Stability Trials

[0160] Water slurries as prepared in Example 2 are used there by adding 0.3% wt of xanthan gum. Each day these water slurries were brought then by a robotic arm to a camera to take a picture. The stability is characterized by the absence of demixing/settling in samples after 3 weeks of static storage in vials placed at 25 C.

[0161] Results are mentioned in the following Table 2:

TABLE-US-00002 TABLE 2 Visual aspects of formulations Surfactants after 3 weeks C1. No surfactant Heavy sedimentation C2. No surfactant, xanthan gum only Sedimentation 1. Soprophor FL and xanthan gum Dispersion Dispersion: corresponds to a monophasic aspect Sedimentation: corresponds to a biphasic aspect

[0162] Viscosity of water slurries comprising 25% wt of torrefied wood of Example 1, 1% wt of Soprophor FL and 0.3% wt of xanthan gum are also measured at different time with a rheometer AR-G2 (TA Instruments) at 25 C. Results are expressed in Table 3 as follows:

TABLE-US-00003 TABLE 3 Viscosity (cP) at Surfactants 100 s(1) C1. No surfactant 250 C2. No surfactant, xanthan gum only 840 1. Soprophor FL and xanthan gum/t = 0 880 2. Soprophor FL and xanthan gum/t = 24 h 877 3. Soprophor FL and xanthan gum/t = 863 1 week 4. Soprophor FL and xanthan gum/t = 872 2 weeks 5. Soprophor FL and xanthan gum/t = 868 3 weeks

[0163] Rheological properties of the suspensions were measured using a ARG2000 rheometer (cone plate system) under controlled shear rate conditions. A cone and plate geometry was chosen with a 40 mm cone diameter and a 90 m gap between the cone and the plate. In order to prevent solvent evaporation during measurements, a cover was used to isolate the sample. A constant temperature was maintained at 25 C. with a controlled thermostatic water bath. The shear stress as a function of the shear rate was recorded for progressively increased shear rates. The shear rate was increased in 10 times from 0.1 to 400 s.sup.1, respectively, at which the shear rate was kept constant. Each time interval lasted 2 min and the shear stress was recorded at the end of each time interval. For each pair of shear stress and shear rate, the viscosity was calculated and plotted as a function of the shear rate. The standard used before the viscosity measurement was a silicone oil (viscosity=500 cP at 25 C.).

[0164] It appears then that the polyalkoxylated phenol surfactants of the invention permit to provide a sufficient stability to the suspensions, notably by keeping fluidity of the suspension over time.

Example 5

Water/Diesel/Particles Slurries

[0165] These slurries are prepared by first mixing 20% wt of water, 63% of diesel (Shell V-Power Diesel CAS number: 68334-30-5) and 2% wt of Soprophor BSU. 15% wt of torrefied wood particles as obtained in Example 1 are then added and mixed with the first mixture to obtain a stable dispersion. An oil-in-water (o/w) emulsion is obtained with the torrefied wood particles located in the continuous phase. It can be observed that the torrefied wood particles get caught between the droplets in the continuous phase, which prevents them from settling. At the same time, the torrefied wood particles seem to act as emulsifying agents, preventing the coalescence of the droplets.

Example 6

Water/Glycerol/Particles Slurries

[0166] These slurries are prepared by first mixing 80% wt of glycerol, 20% of water and optionally 1% wt of Soprophor FL and 0.3% wt of xanthan gum. 30% wt of torrefied wood particles as obtained in Example 1 are then added and mixed with the first mixture to obtain a stable dispersion.

[0167] The stability is determined as expressed in Example 3 and results are mentioned in the following Table 4:

TABLE-US-00004 TABLE 4 Visual aspects of Viscosity (cP) formulations Surfactants and additive at 100 s(1) after 3 days C1. Nothing 1500 Heavy sedimentation C2. Xanthan gum 2300 Dispersion 1. Soprophor FL and xanthan gum 2980 Dispersion

[0168] It appears then that the polyalkoxylated phenol surfactants of the present invention permit to provide a sufficient stability to the suspensions.