EP0050412B1 - Procédé pour la préparation d'une suspension de charbon dans l'eau et produit obtenu - Google Patents

Procédé pour la préparation d'une suspension de charbon dans l'eau et produit obtenu Download PDF

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Publication number
EP0050412B1
EP0050412B1 EP81304187A EP81304187A EP0050412B1 EP 0050412 B1 EP0050412 B1 EP 0050412B1 EP 81304187 A EP81304187 A EP 81304187A EP 81304187 A EP81304187 A EP 81304187A EP 0050412 B1 EP0050412 B1 EP 0050412B1
Authority
EP
European Patent Office
Prior art keywords
slurry
coal
mmd
particles
water
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP81304187A
Other languages
German (de)
English (en)
Other versions
EP0050412A3 (en
EP0050412A2 (fr
Inventor
Robert Stephen Scheffee
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Atlantic Research Corp
Original Assignee
Atlantic Research Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Atlantic Research Corp filed Critical Atlantic Research Corp
Priority to AT81304187T priority Critical patent/ATE11927T1/de
Publication of EP0050412A2 publication Critical patent/EP0050412A2/fr
Publication of EP0050412A3 publication Critical patent/EP0050412A3/en
Application granted granted Critical
Publication of EP0050412B1 publication Critical patent/EP0050412B1/fr
Expired legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L1/00—Liquid carbonaceous fuels
    • C10L1/32—Liquid carbonaceous fuels consisting of coal-oil suspensions or aqueous emulsions or oil emulsions
    • C10L1/326—Coal-water suspensions

Definitions

  • This invention relates to the production of fuel slurries of coal in water which can be injected directly into a furnace as a combustible fuel.
  • a high fuel value coal slurry can supplant large quantities of increasingly expensive fuel oil presently being used by utilities, factories, ships and other commercial enterprises. Since the inert water vehicle reduces fuel value in terms of BTU/lb (J/kg) it is desirable to minimise its concentration and maximise coal concentration for efficient use of the slurry as a fuel.
  • a high coal content also improves the combustion characteristics of the slurry.
  • the slurry be loadable with finely-divided coal in amounts as high, for example, as about 50% to 70% of the slurry.
  • the slurry must be sufficiently fluid to be pumped and sprayed into the furnace.
  • the coal particles must also be uniformly dispersed. The fluidity and dispersion must be stably maintained during storage.
  • An object of this invention is to provide an improved process for producing a slurry suitable for this purpose.
  • This invention further provides a coal-water slurry which comprises:
  • fluid, pourable slurries comprising up to about 70% or higher of coal stabley dispersed in water are produced by admixing finely-divided coal having a critical distribution of particle sizes, water, and an organic dispersant in a high shear rate mixer.
  • An inorganic buffer salt may also be added.
  • fluid as used in this specification and claims means a slurry which is fluid and pourable both at rest and in motion or a slurry which gels or flocculates into a substantially non-pourable composition at rest and becomes pourably fluid with stirring or other application of relatively low shear stress.
  • UF particles should comprise 10 to 30% by weight of the slurry, preferably 15 to 25%.
  • the actual degree of coal loading is not critical and will vary with the given use and operating equipment.
  • concentration of coal successfully incorporated into a given slurry varies with such factors as the relative amounts of UF and F/C particles, size of the F/C particles used within the effective range, and the like. In general, percentage loading increases with increasing F/C size.
  • An organic dispersant is essential to maintain the coal particles in stable dispersion. It has been found that the highly-loaded slurried are very sensitive to the particular type of surfactant used, especially with respect to fluidity and storageability. Examples of dispersants which have proven to be effective in producing stable fluid mixes are high molecular weight alkaline earth metal (e.g. Ca, Mg) organosulfonates in which the organic moiety is poly-functional. Molecular weight of the organosulfonate is desirably 1,000 to 25,000.
  • the surfactant is used in minor amount, e.g. 0.5 to 5 pph of coal, preferably 1 to 2 pph.
  • an inorganic, alkali metal (e.g. Na, K) buffer salt to stabilize pH of the slurry in the range-of from pH 5 to 8, preferably from pH 6 to 7.5.
  • the salt improves ageing stability, pourability and handling characteristics of the slurry. It may be that the buffer counteracts potentially adverse effects of acid leachates from the coal.
  • the salt such as sodium or potassium phosphate or carbonate, including their acid salts is used in minor amounts sufficient to provide the desired pH, e.g. 0.1 to 2% based on the water.
  • the inorganic salts also serve to reduce gaseous sulfur pollutants by forming non-gaseous sulfur compounds.
  • the ultrafine and larger F/C coal particles, water, dispersant, and inorganic salt components are mixed in a blender or other mixing device which can deliver high shear rates.
  • High shear mixing e.g. at shear rates of at least about 100 sec -1 , preferably at least about 500 sec -1 , is essential for producing a stable slurry free from substantial sedimentation.
  • the use of high shear mixing and the dispersant appears to have a synergistic effect.
  • Dispersant with low shear mixing results in an extremely viscous, non-pourable slurry, while high shear mixing without dispersant produces a slurry which is unstable towards settling. With both dispersant and high shear mixing a fluid, pourable, stable slurry an be obtained.
  • the slurries are viscous, fluid dispersions which can generally be characterized as thixotropic or Bingham fluids having a yield point.
  • the slurries may gel or flocculate when at rest into a substantially non-pourable composition but are easily rendered fluid by stirring or other application of relatively low shear stress. They can be stored for considerable periods of time without excessive settling or sedimentation.
  • the slurries can be employed as fuels by injection directly into a furnace previously brought up to ignition temperature of the slurry. The finely divided state of the coal particles improves combustion efficiency. Since the dispersants are organic compounds, they may be biodegraded with time. This can readily be prevented by addition of a small amount of biocides.
  • the ultrafine coal particles can be made in any suitable device, such as a ball mill or attritor, which is capable of very fine comminution.
  • the coal is milled with water so that the UF particles are in water slurry when introduced into the mixer.
  • Some of the dispersant can be included, if desired, in the UF milling operation to improve flow and dispersion characteristics of the UF slurry.
  • the required larger size coal particles (20 ⁇ m to 200j M ) can be made from crushed coal in a comminuting device such as a hammermill equipped with a grate having appropriately sized openings. Excessively sized coal residue can be used for making the UF particles.
  • coal concentrations as used in the specification and in the following examples is on a dried coal basis which normally equals 98.5% by weight of bone-dried coal.
  • the 3.6 ⁇ m MMD UF particles employed in Examples 3-8 were prepared in accordance with Example 1 and the UF particles were introduced in the form of the Example 1 aqueous slurry containing a portion of the dispersant.
  • the total amount of dispersant given in the Examples includes the portion introduced in this way.
  • Sedimentation measurement which is based on Stoke's Law giving the relationship between particle size and settling velocity, was used experimentally in all cases to determine sub-sieve particle sizes.
  • the particular sedimentation technique employed is one conventionally known as centrifugal sedimentation.
  • the sedi- mentometer used was the MSA Particle Size. Analyzer (C.F. Casello & Co, Regent House, Britania Walk, London N1).
  • centrifugal sedimentation the local acceleration due to gravity, g, is multiplied by w 2 r/g where w is rotational velocity and r is radius of rotation.
  • the "two layer" method was used in the experimental procedures.
  • coal powder is initially concentrated in a thin layer floating on top of the suspending water fluid in a centrifuge tube.
  • the fluid is centrifuged at incrementally increasing rotational speeds, The amount of sedimenting powder is measured as a function of time at a specified distance from the surface of the fluid.
  • the cumulative size distribution was determined by plotting the fractional weight settled out against the free-falling Stoke's diameter.
  • the sub-sieve particle sizes disclosed and claimed herein were obtained by sedi- ment ation measurement.
  • Example 3A A 65% coal slurry was made identical to Example 3A except that no dispersant was added. The resulting product had the consistency of a stiff grease.
  • Example 4A A mix was made identical to Example 4A except that Na z HP0 4 in amount providing buffered pH 7 was added in the blender. The resulting slurry was fluid and pourable. Its viscosity was EOM-T-bar 0.92 kP. It retained its stability and pourability during storage and after 12 days was free from separation.
  • Example 3 demonstrates the need for the UF particles in controlled size distribution to impart stability.
  • Examples 4 and 5 show the need for high shear rate mixing.
  • Example 6 shows the importance of the dispersant.
  • Example 7 illustrates the improvement made in a highly-loaded 70% slurry by use of an inorganic buffer salt and the adverse effect of low shear mixing.
  • Example 8 shows that the use of the pH buffer salt maintained the slurry in a stable fluid condition.
  • Example 9 shows that the buffer salt improved aging and its user and handling characteristics.
  • the cost of the coal-water slurries including processing is about t that of No. 6 fuel oil at present prices.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Liquid Carbonaceous Fuels (AREA)
  • Solid Fuels And Fuel-Associated Substances (AREA)
  • Emulsifying, Dispersing, Foam-Producing Or Wetting Agents (AREA)
  • Colloid Chemistry (AREA)

Claims (13)

1. Procédé pour confectionner des suspensions charbon-eau pratiquement stables comprenant les stades de:
a) Mélanger:
i) des particules ultrafines de charbon ayant au maximum une grosseur (déterminée par une méthode de sédimentation fondée sur la loi de Stokes) de 10µm MMD (diamètre moyen pour toute la masse) à raison de 10 à 30% en poids de la suspension;
(ii) des particules de charbon plus grosses, sur la plage de grosseurs allant de 20 à 200µm MMD, en quantité suffisante pour assurer, dans la suspension, la concentration globale désirée pour la charbon;
(iii) de l'eau;
(iv) une faible quantité d'un dispersant essentiellement constitué d'un organosulfonate d'un métal alcalino-terreux dans lequel la portion organique est polyfonctionnelle; et
b) soumettre le mélange à un fort cisaillement d'au moins 100 sec-1.
2. Procédé selon la revendication 1, dans lequel un sel-tampon d'un métal anorganique est ajouté pour maintenir le pH sur la plage allant de 5 à 8.
3. Procédé selon la revendication 2, dans lequel le sel-tampon est un phosphate d'un métal alcalin.
4. Procédé selon l'une quelconque des revendications 1,2 ou 3, dans lequel:
a) les particules ultrafines sont sur la plage de grosseurs allant de 1 à 8µm MMD et font de 15 à 25% en poids de la suspension;
b) les particules de charbon plus grosses sont sur la plage de grosseurs allant de 20 à 150µm MMD.
5. Procédé selon une des revendications 1 à 4 dans lequel le dispersant est du lignosulfonate de calcium:
6. Procédé selon une des revendications 1 à 5 dans lequel le gradient de cisaillement est au moins de 500 sec-1.
7. Procédé selon l'une quelconque des revendications 1 à 6 dans lequel les particules ultrafines sont produites en présence d'eau et d'au moins une partie du dispersant.
8. Suspension eau-charbon qui comprend:
a) des particules ultrafines de charbon ayant une grosseur maximale (déterminée par une méthode de sédimentation fondée sur la loi de Stokes) de 10µm MMD (diamètre moyen pour toute la masse), en quantité comprise entre 10 et 30% en poids de la suspension;
b) des particules plus grosses, sur la plage de grosseurs allant de 20 à 200µm MMD, en quantité suffisante pour assurer, dans la suspension, la concentration globale désirée pour le charbon;
c) de l'eau;
d) une faible quantité d'un dispersant constitué essentiellement par un organosulfonate d'un métal alcalino-terreux dans lequel la partie organique est pofyfonctionnelle.
9. Suspension selon la revendication 8 dans laquelle:
a) les particules ultrafines se trouvent sur la plage de grosseurs allant de 1 à 8µm MMD;
b) les particules plus grosses se trouvent sur la plage de grosseurs allant de 20 à 1 50µm MMD.
10. Suspension selon la revendication 8 ou la revendication 9, dans laquelle le dispersant est du lignosulfonate de calcium.
11. Suspension selon l'une quelconque des revendications 8 à 10, qui est tamponnée pour un pH de 5 à 8 au moyen d'un sel-tampon anorganique d'un métal alcalin.
12. Suspension selon la revendication 11, dans laquelle le sel-tampon est un phosphate d'un métal alcalin.
13. Suspension selon l'une quelconque des revendications 1 à 12, ayant sensiblement le caractère thixotropique (celui d'un pseudo- fluide binghamien).
EP81304187A 1980-10-17 1981-09-14 Procédé pour la préparation d'une suspension de charbon dans l'eau et produit obtenu Expired EP0050412B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81304187T ATE11927T1 (de) 1980-10-17 1981-09-14 Verfahren zur herstellung von kohle-wasserbrennstoffsuspensionen und das daraus erhaltene produkt.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US19785380A 1980-10-17 1980-10-17
US197853 1980-10-17

Publications (3)

Publication Number Publication Date
EP0050412A2 EP0050412A2 (fr) 1982-04-28
EP0050412A3 EP0050412A3 (en) 1982-08-04
EP0050412B1 true EP0050412B1 (fr) 1985-02-20

Family

ID=22731003

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81304187A Expired EP0050412B1 (fr) 1980-10-17 1981-09-14 Procédé pour la préparation d'une suspension de charbon dans l'eau et produit obtenu

Country Status (8)

Country Link
EP (1) EP0050412B1 (fr)
JP (1) JPS5796090A (fr)
AT (1) ATE11927T1 (fr)
AU (1) AU554293B2 (fr)
CA (1) CA1178441A (fr)
DE (1) DE3169061D1 (fr)
IL (1) IL63866A (fr)
ZA (1) ZA816150B (fr)

Families Citing this family (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4551179A (en) * 1981-01-29 1985-11-05 The Standard Oil Company Coal-aqueous mixtures
US4441889A (en) * 1981-01-29 1984-04-10 Gulf & Western Industries, Inc. Coal-aqueous mixtures
GR76426B (fr) * 1981-05-21 1984-08-10 Snam Progetti
IT1211049B (it) * 1981-05-21 1989-09-29 Snam Progetti Sospensione acquosa di carbone.
JPS5896690A (ja) * 1981-12-03 1983-06-08 Electric Power Dev Co Ltd 石炭の高濃度スラリ−の製造方法
NZ202639A (en) * 1982-03-22 1986-03-14 Atlantic Res Corp Stable coal-water slurries and a method for their preparation
US4498906A (en) * 1982-03-22 1985-02-12 Atlantic Research Corporation Coal-water fuel slurries and process for making
US4504277A (en) * 1982-04-16 1985-03-12 Atlantic Research Corporation Coal-water fuel slurries and process for making same
SE8202879L (sv) * 1982-05-07 1983-11-08 Carbogel Ab Vattenuppslamning av ett fast brensle samt sett och medel for framstellning derav
EP0094786B1 (fr) * 1982-05-19 1987-11-04 The British Petroleum Company p.l.c. Boues minérales
GB2121819B (en) * 1982-06-14 1985-03-27 Smidth & Co As F L Method of manufacturing a pumpable coal/liquid mixture
US4511365A (en) * 1982-09-10 1985-04-16 Sohio Alternate Energy Development Company Coal-aqueous mixtures
US4722740A (en) * 1982-09-30 1988-02-02 Oxce Fuel Company Dispersions of coal in water useful as a fuel
FR2538407A1 (fr) * 1982-12-27 1984-06-29 Raffinage Cie Francaise Combustible liquide a base de combustible solide pulverise, de residus petroliers et d'eau, son procede de preparation et son application dans des chaudieres ou des fours industriels
CA1255905A (fr) * 1983-07-05 1989-06-20 Hirofumi Kikkawa Production d'une bouillie aqueuse surconcentree de houille
GB8319033D0 (en) * 1983-07-14 1983-08-17 Carbogel Ab Sulphur capture
JPS6058491A (ja) * 1983-09-09 1985-04-04 Electric Power Dev Co Ltd 炭素含有組成物の水スラリ−の安定化処理方法
JPS6071693A (ja) * 1983-09-29 1985-04-23 Babcock Hitachi Kk 石炭−水スラリ製造法
JPS6136398A (ja) * 1984-07-30 1986-02-21 Babcock Hitachi Kk 高濃度石炭・水スラリ製造方法
US4810259A (en) * 1985-09-19 1989-03-07 Oxce Fuel Company Method to minimize viscosity and improve stability of coal-water fuels
DE3707941A1 (de) * 1987-03-12 1988-09-22 Henkel Kgaa Dispergiermittel und ihre verwendung in waessrigen kohlesuspensionen
JPH02232296A (ja) * 1989-03-06 1990-09-14 Central Res Inst Of Electric Power Ind 石炭・水スラリーの製造方法
JP2595465B2 (ja) * 1994-04-13 1997-04-02 英司 池田 水・石炭混合燃料
US8177867B2 (en) * 2008-06-30 2012-05-15 Nano Dispersions Technology Inc. Nano-dispersions of coal in water as the basis of fuel related technologies and methods of making same
US20130074396A1 (en) 2008-06-30 2013-03-28 Gustavo A. Núñez Nano-dispersions of carbonaceous material in water as the basis of fuel related technologies and methods of making same
SG10201602735VA (en) * 2011-04-07 2016-05-30 Nano Dispersions Technology Inc Nano-dispersions of carbonaceous material in water as the basis of fuel related technologies and methods of making same

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1522575A (en) * 1976-06-24 1978-08-23 Texaco Development Corp Production of solid fuel-water slurries
US4261701A (en) * 1980-01-09 1981-04-14 Gulf Research & Development Company Uniform coal suspensions and process for preparing same

Also Published As

Publication number Publication date
ZA816150B (en) 1982-09-29
IL63866A0 (en) 1981-12-31
IL63866A (en) 1984-07-31
ATE11927T1 (de) 1985-03-15
AU554293B2 (en) 1986-08-14
CA1178441A (fr) 1984-11-27
JPS5796090A (en) 1982-06-15
EP0050412A3 (en) 1982-08-04
DE3169061D1 (en) 1985-03-28
EP0050412A2 (fr) 1982-04-28
AU7543981A (en) 1982-04-22

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