EP0412985A1 - Extraction de solvants et deshydratation de la tourbe - Google Patents

Extraction de solvants et deshydratation de la tourbe

Info

Publication number
EP0412985A1
EP0412985A1 EP89905143A EP89905143A EP0412985A1 EP 0412985 A1 EP0412985 A1 EP 0412985A1 EP 89905143 A EP89905143 A EP 89905143A EP 89905143 A EP89905143 A EP 89905143A EP 0412985 A1 EP0412985 A1 EP 0412985A1
Authority
EP
European Patent Office
Prior art keywords
peat
solvent
water
slurry
bitumen
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.)
Withdrawn
Application number
EP89905143A
Other languages
German (de)
English (en)
Inventor
John A. G. Drake
Michael Anthony Hughes
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.)
Amec Foster Wheeler Energy Ltd
Original Assignee
Foster Wheeler Energy Ltd
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 Foster Wheeler Energy Ltd filed Critical Foster Wheeler Energy Ltd
Publication of EP0412985A1 publication Critical patent/EP0412985A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10F—DRYING OR WORKING-UP OF PEAT
    • C10F5/00—Drying or de-watering peat
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal
    • C10G1/04—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal by extraction

Definitions

  • This invention relates to the solvent extraction and dewatering of peat.
  • Peat can be dewatered and concurrently solvent extracted with organic solvents.
  • One method of achieving this is by means of the Carver-Greenfield counter-current solvent dewatering system. This is an extremely efficient and cost-effective way of dewatering peat but is less efficient in extracting peat bitumens.
  • GB 2060417 discloses a process wherein the oil is subsequently separated from water.
  • a wide variety of hydrocarbon oils aliphatic alcohols and aliphatic acids are proposed.
  • EP244233 discloses use of such a process for extraction of peat bitumens.
  • Use of a variety of solvents is disclosed.
  • a benzene/ethanol azeotrope was preferred to petroleum ether. Mixtures of solvents afforded higher bitumen yields than individual solvents. The effect of extraction conditions on the nature of the product was discussed in detail.
  • solvents have been used for dewatering peat including benzene and diethyl ketone but benzene/ethanol mixtures were preferred.
  • the invention seeks to provide an improved method for the combined solvent extraction and dewatering of peat and to produce better yields and/or better quality peat bitumens.
  • a process for dewatering and extraction of bitumen from peat including the steps of: contacting peat with an organic solvent having an aromatic content of 6% or more and a boiling point of 120-200°C or more removing water from the peat by distillation separating the solvent with dissolved peat bitumen from residual solid matter and evaporating said solvent to yield peat bitumen.
  • white spirit is particularly preferred.
  • the term 'white spirit' is intended to include refined products such as is sold under the trade mark SHELL SBP11 and other petroleum hydrocarbon fractions or mixtures of boiling range 120-200°C of which the major compoenents are alkanes and alkenes (each being either straight chain or branched chain structures) , naphthenes (being polyalkyl or heterocyclic derivatives of cyclohydrocarbons whether saturated or partially unsaturated) and aromatics (including benzene, naphthalene and tricyclic aromatic compounds being alkyl , polyalkyl or heterocyclic derivatives of these ring structures) .
  • the heteroatoms in these compounds could commonly be 0,N or S.
  • the relative - - percentages of these groups of compounds can vary widely and may generally contain at least 6% aromatics.
  • White spirit has a boiling point of 140- 170°C, generally 155-168°C. The flash point is high and only a trace of benzene or sulphur compounds is normally present. Toxicity is therefore low.
  • White spirit may commonly contain 15-25% of aromatics.
  • the solvent preferably forms an azeotrbpe with water, to facilitate removal by distillation.
  • Preferred solvents have an aromatic content of 10°C or more, but not exceeding 40% preferably not more than 30%. The percentage of aromatics is based on the weight of components having aromatic groups.
  • the solvent is particularly suitable for use in a system such as the Carver-Greenfield counter-current solvent dewatering system.
  • a non-aromatic or low aromatic solvent such as low aromatic content kerosene.
  • the use according to the invention, of a solvent having a higher aromatic content leads to a much better dewatering and extraction of peat bitumens and to production of peat bitumen extracts which are less degraded and hence have a higher value.
  • the top limit of the boiling range of the solvent should be no greater than about 200°C.
  • the solvent should meet other criteria such as ease of availability, low cost, environmental and health acceptability, low sulphur content, and acceptable flashpoint and explosive characteristics. Selection of the solvents of this invention from the wide range of available compounds and mixtures affords a number of unique benefits and advantages which were not evident from the relevant prior art, in relation to the treatment of peat.
  • Volatile solvents may be considered to be generally desirable for solvent extraction on account of their easy separation from the extracted material.
  • criteria for dewatering processes are different. Generally, acetone, other ketones, ethanol or other alcohols are chosen for dewatering processes. We have found that these are too polar for bitumen extraction from peat.
  • the solvating power is greater than for alkane solvents but the polarity is not as high as alcohol or ketone solvents. In addition, toxicity is low and the solvent is cheap.
  • the physical properties are particularly suited to the Carver-Greenfield process.
  • the boiling point of 140-170°C allows easy recovery of the solvent by distillation preferably under vacuum without pyrolysis of the residual bitumen.
  • countercurrent extraction requires a solvent with a higher boiling point than water but below that of the bitumen.
  • Formation of an aqueous azeotrope having a boiling point of 90- 100°C is particularly beneficial, allowing simple extractor design and processing using steam heating.
  • white spirit is immiscible with water facilitating separation from the latter.
  • a further unexpected advantage is that white spirit has superior wetting properties on peat, particularly in comparison to paraffins. Slurries of peat and white - - spirit may be easily handled by pumping and similar means.
  • Peat typically containing 50% water
  • the chosen solvent which should of course be immiscible with water
  • the solvent is heated to a temperature below 100°C.
  • a certain amount of the water will evaporate and after a fixed time the partially treated peat is moved on to a second pot where it is treated in a similar manner at a higher temperature.
  • Four pots in all may be involved and the solvent may be introduced into pot 4 and transferred sequentially through pots 3 and 2 to pot 1 while the peat itself moves in the opposite direction. This provides efficient thermal transfer between the pots. It has been found that solvent in accordance with the invention shows markedly improved dewatering properties as well as improved bitumen extraction.
  • Table 1 (page 5a) gives details of two preferred solvents in accordance with the invention, Shell SBP11 and Shell White Spirit, together with two solvents previously used in the Carver-Greenfield system Esso ispoar L and Esso solvent 2012, the latter being a commercial grade of kerosene.
  • the solvents of the method of the invention also exhibit superior wetting rates with these being roughly in line with the aromatic content.
  • the peat (about 50g) is continuously washed with clean solvent at appro imately room temperature, but the syphoned solution is boiled continuously at the relatively high boiling temperature of the commercial solvent (Table 1). Hence the extracted peat bitumens are subjected to high temperatures for prolonged periods and the extract was pale yellow coloured.
  • the digestion procedure about lOOg of milled peat wrapped in muslin was stirred in the refluxing solvent for about three hours.
  • the peat bitumen solution was filtered and the water layer separated form the organic solvent layer.
  • the solvent was distilled from the peat bitumen under vacuum (0.89 torr, measured on a McLeod gauge) on a rotary evaporator, the last solvent being removed by freeze drying.
  • the initial and final water content of the peat was determined by the Dean and Stark method to avoid confusion between solvent and water losses if the peat residue water content is estimated by the oven method.
  • the yields, saponification value and acid value of the peat bitumens and initial and final water contents of the peat after solvent extraction with three solvents by Soxhlet and digestion methods are given in Table 4.
  • the Esso 2012 solvent was difficult to distil from the extracted peat bitumens because of its relative high upper boiling point (240°C at atmosphere pressure) when some of the peat bitumens also distil. Bumping of the solution during distillation could only be avoided by high speed agitation and probably arose from colloidally dispersed water in the solvent.
  • the colloidal water would explain the poor efficiency of the digestion method in removing water from peat when compared with the other solvents.
  • the collodial water would be in equilibrium with the water saturated peat whereas in the white spirit and SBP11 very little collodial water exists; it separates into a layer or is lost as the low boiling azeotrope.
  • the solvent was distilled from the extracted peat bitumens under reduced pressure at about 100°C.
  • peat bitumens contain three classes of material :
  • Peat bitumen is an ester-type wax.
  • the resins present in wax are relatively more soluble in non-polar solvents such as paraffins.
  • Various procedures have been used to determine the resin content of waxes. They involve classifying as resins those wax constituents which are soluble in cold alcohol or cold ethyl acetate. Such a classificiation is crude and allows for considerable overlap of constituent material.
  • bitumen is very complex and no one component would represent more than 1% of the bitumen.
  • Table 5 The resin content and de-resinated wax content were similar for bitumen extracted at 40°C, 60°C and 80°C.
  • the bitumen extracted at 20°C differed from the other bitumens in the larger resin and lower wax content.
  • the bitumen from the large scale extraction gives larger wax content than resin content.
  • the solvent used in this extraction was SBPll rather than white spirit and may extract ester waxes in preference to resins.
  • the deresinated wax was harder than the crude bitumen from which it was derived. This was quantified by the increased melting points. Determination of melting point by capillary tube (sometimes called slip-point) is not normal practice for these waxes but was used in this case for simplicity. Only the large scale bitumen resin fraction had a melting point above room temperature.
  • the high aromatic solvent employed in the method of the present invention enable processes such as the Carver-Greenfield peat dewatering process to operate more efficiently and in particular to give maximum yields of peat bitumen and better wetting of the peat. Moreover the composition of the peat bitumen extracted, being higher in waxes, is superior so the products are therefore more valuable commercially.
  • the dewatered peat may be used as a fuel as is conventional and the removal of the bitumens may actually improve its utility as a fuel since it burns with less smoke.
  • Figure 1 illustrates use of a Carver-Greenfield process in accordance with this invention.
  • Raw peat is placed in a fluidising tank 2 with the solvent, white spirit.
  • the slurry produced is pumped into a first evaporator 6.
  • the evaporator is heated by waste water vapour through line 14 on the second evaporator stage 7.
  • Water vapour from the first evaporator stage 6 passes through a cooling system 3 to a vacuum system 1 and vent.
  • Solvent condensed by the cooling system 3 is separated in the separator 4 and returned to the fluidising tank 2.
  • Dehydrated peat in a slurry with the solvent is pumped into the second evaporator stage through the line 13.
  • the second evaporator stage is steam heated and completes the dehydration and extraction from the peat.
  • the pressure in the second evaporator is lower, allowing further water to be removed at a lower temperature.
  • the slurry of dry peat and bitumen containing solvent is pumped to a centrifuge 9.
  • the solid material from the centrifuge is passed to a de-oiling apparatus 8 which produces dry de-oiled peat 15 for use as combustible fuel.
  • the solvent from the centrefuge and the de-oiler is recycled to a recovery system 10 wherein solvent is distilled to yield bitumen and pure solvent for re-use.
  • Figure 1 shows a two stage evaporator system three, four or more stages may be employed in accordance with conventional Carver-Greenfield practice.
  • Deoiled peat may find use as a combustible fuel, in animal feedstuffs and may yield beneficial hydrolysis products.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
  • Working-Up Tar And Pitch (AREA)

Abstract

Un procédé de déshydratation de la tourbe et d'extraction du bitume contenu dans celle-ci par extraction répétée à contre-courant avec de l'essence blanche peut être mis en oeuvre avec avantage au moyen d'une installation de type Carver-Greenfield.
EP89905143A 1988-04-30 1989-05-02 Extraction de solvants et deshydratation de la tourbe Withdrawn EP0412985A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8810347 1988-04-30
GB888810347A GB8810347D0 (en) 1988-04-30 1988-04-30 Solvent extraction of peat

Publications (1)

Publication Number Publication Date
EP0412985A1 true EP0412985A1 (fr) 1991-02-20

Family

ID=10636215

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89905143A Withdrawn EP0412985A1 (fr) 1988-04-30 1989-05-02 Extraction de solvants et deshydratation de la tourbe

Country Status (5)

Country Link
EP (1) EP0412985A1 (fr)
FI (1) FI905334A7 (fr)
GB (1) GB8810347D0 (fr)
NZ (1) NZ228938A (fr)
WO (1) WO1989010391A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4106281A1 (de) * 1991-02-28 1992-09-03 Ruhrkohle Oel & Gas Verfahren zur behandlung von wasserhaltigen, mit organischen schadstoffen belasteten materialien unter verwendung von leicht fluechtigen und mit wasser nicht mischbaren organischen loesungsmitteln

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR669519A (fr) * 1928-02-24 1929-11-18 Ig Farbenindustrie Ag Procédé pour l'extraction sous pression de substances carbonées
FR36611E (fr) * 1929-03-28 1930-07-07 Ig Farbenindustrie Ag Procédé pour l'extraction sous pression de substances carbonées
GB844556A (en) * 1958-08-27 1960-08-17 Glinka Carl Improvements in or relating to the removal of moisture from solid fuels
US3323575A (en) * 1966-04-05 1967-06-06 Greenfield Charles Apparatus and process for dehydrating waste solids concentrates
CA1306836C (fr) * 1986-04-30 1992-09-01 John A.G. Drake Liant bitumineux pour revetement routier

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8910391A1 *

Also Published As

Publication number Publication date
FI905334A0 (fi) 1990-10-29
GB8810347D0 (en) 1988-06-08
WO1989010391A1 (fr) 1989-11-02
FI905334A7 (fi) 1990-10-29
NZ228938A (en) 1992-01-29

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