EP0295345A1 - Verfahren und Vorrichtung zur Entschwefelung von Kohlen - Google Patents

Verfahren und Vorrichtung zur Entschwefelung von Kohlen Download PDF

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Publication number
EP0295345A1
EP0295345A1 EP87305399A EP87305399A EP0295345A1 EP 0295345 A1 EP0295345 A1 EP 0295345A1 EP 87305399 A EP87305399 A EP 87305399A EP 87305399 A EP87305399 A EP 87305399A EP 0295345 A1 EP0295345 A1 EP 0295345A1
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EP
European Patent Office
Prior art keywords
coal
sulfur
inorganic
pyrrhotite
organic
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Withdrawn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
EP87305399A
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English (en)
French (fr)
Inventor
David R. Kelland
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Massachusetts Institute of Technology
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Massachusetts Institute of Technology
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Publication date
Priority to US06/851,924 priority Critical patent/US4678478A/en
Application filed by Massachusetts Institute of Technology filed Critical Massachusetts Institute of Technology
Priority to EP87305399A priority patent/EP0295345A1/de
Publication of EP0295345A1 publication Critical patent/EP0295345A1/de
Withdrawn legal-status Critical Current

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    • 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
    • C10L9/00—Treating solid fuels to improve their combustion
    • C10L9/02—Treating solid fuels to improve their combustion by chemical means

Definitions

  • This invention is in the field of coal desulfuri­zation and the removal of ash-forming minerals from the coal.
  • the present invention relates to a relatively inexpensive method and apparatus for coal desulfurization and de-ashing in which both the inorganic (pyrite) and organic sulfur is removed from coal along with removal of ash-forming minerals.
  • Untreated coal comprises organic carbonaceous material and inorganic minerals.
  • Sulfur occurs in coal both in organic and inorganic forms. In the organic forms, the sulfur is chemically bonded into the hydrocarbon structure of the coal and generally cannot be removed by physical means such as magnetic separation.
  • the inorganic forms of sulfur generally occurs as pyrite, FeS2, but also includes other iron sulfur inorganics such as pyrrhotite Fe 1-x S, and occurs as iron sulfide mineral inclusions in the coal and, therefore, can be removed magnetically.
  • the relative proportions of organic and inorganic sulfur in coal vary with the source of the coal. In many coals from the Eastern half of the United States, the proportions are approximately equal.
  • the approaches to magnetic coal cleaning can be divided into two categories relevant to the present invention: direct desulfurization and deashing, and separating coal minerals which have had pretreatment to enhance their magnetic properties.
  • the first, direct desulfurization has been carried out on crushed coal in water, oils, alcohol and in air or inert gas.
  • the "direct” process depends on the difference between the magnetic properties of coal and those of its associated mineral impurities as found.
  • the invention comprises a desulfurization method and apparatus for removing both the inorganic and organic sulfur from coal.
  • the invention involves a combination of physical, chemical, and simple thermo-chemical cleaning steps to remove both kinds of sulfur.
  • a further, optional process, is described for removal of non-pyritic ash-forming minerals from the residue of the desulfurization process
  • the desulfurization process of the invention commences with coal as the starting material.
  • the coal contains minerals, inorganic sulfur in the form of pyrites and organically bound sulfur in the hydrocarbon structure.
  • microwave radiation is applied to the coal to preferentially heat the pyrite (FeS2) driving off some of the sulfur from the pyrite as gaseous H2S, SO2, COS, etc.
  • FeS2 pyrite
  • a flowing gas such as argon, carbon monoxide or hydrogen, is used in this step to prevent the sulfur from re-combining with the coal.
  • a hydrogenation agent in the form of a liquid hydrocarbon such as an alcohol, like ethanol, is used to remove the organic sulfur in the presence of a catalyst.
  • the troilite formed in the microwave heating step is an excellent catalyst for breaking thiophene and also thiol sulfur bonds, which bond the organic sulfur in the carbonaceous part of the coal.
  • the pyrrhotite formed in the preferential heating step is also a catalyst for thiol sulfur. This organic sulfur is removed as H2S, and some of it causes a shift in the stoichiometry of the troilite toward pyrrhotite. This step leaves clean coal i.e., organic sulfur removed and highly magnetic pyrrhotite (inorganic sulfur).
  • HGMS high gradient magnetic separation
  • non-pyrite ash-forming minerals remaining in the coal may be treated by an organic flocculant, such as Tergitol 7 (sodium heptadecyl sulphate) while adjusting the magnetization of the pyrite with H2S.
  • the flocculant serves to attach the non-pyrite minerals present in the residue with the pyrrhotite for removal together by magnetic separation in the final step so as to significantly reduce the ash in addition to the organic and inorganic sulfur already removed; thereby resulting in a superclean coal product.
  • the coal is subjected to microwave radiation for the purpose of preferentially heating the pyrite (FeS2) to transform the inorganic sulfur material in the coal to a more highly magnetic state and to extract some of the sulfur by thermo-chemical reactions.
  • the microwave heat source should have enough power to heat the pyrite to a sufficient temperature to shift the stoichiometry (Fe-S ratio) away from FeS2 towards Fe 1-X S; wherein 0 is less than or equal to x, and x is less than or equal to 0.5.
  • Preferential heating preferably by microwave energy, is economically advisable, in order to avoid heating the coal rather than the pyrite because energy used to heat the coal is wasted unless it is fully recovered.
  • Heating the whole coal would require a far larger, and hence, more expensive, energy source. Also, preferential heating to increase magnetization is advantageous because no dangerous chemicals like carbon monoxide are produced as is the case in the process of J.K Kindig supra, where iron is deposited on the pyrite from Fe(Co)5. Furthermore, no high pressures are needed; hence no high pressure vessels are required.
  • the time for heating the pyrite must be kept short, i.e. between about 1 minute, and 10 seconds.
  • the magnetization increases sharply upward from less than 0.1 cgs emu/gm at 9 k0e applied field to 4.5 emu/gm in a temperature range from 675 C to 740 C.
  • the magnetization increases from 0 at 665 C to about 0.5 emu/gm at 760 C.
  • Experimental data indicates that the same magnetization of 4 or 5 emu/gm would be reached at slightly over 800 C for the 10 second heating time.
  • the sulfur can also combine with the organic coal structure. To prevent this, a flowing gas stream is recommended during Step 1. This gas may comprise the hydrogen needed for the above reaction.
  • Step 1 if half of the total sulfur in the coal were in the inorganic mineral form of FeS2 to begin with, then roughly one-quarter of the total sulfur would be removed as the pyrite undergoes a transition to Fe7S8 (nearly FeS), provided none of it combines with the organic coal structure.
  • Fe7S8 nearly FeS
  • Troilite appears to be favored if a flowing gas is used to prevent recombination of the sulfur coming off the pyrite with the organic coal structure.
  • Step 2 the irradiated coal, which has been magnetically enhanced, is treated with a light organic hydrocarbon liquid, such as ethanol, methanol, or light fractions from coal hydrolysis, in the presence of the catalytic material, i.e., pyrrhotite or troilite produced by the enhancement in Step 1.
  • a light organic hydrocarbon liquid such as ethanol, methanol, or light fractions from coal hydrolysis
  • Step 3 the remaining inorganic iron sulfides are separated from the coal using well known magnetic separation techniques. Prior to this step, the organic sulfur has been removed from the coal and the coal and iron sulfide is suspended in an alcohol mixture. Experimental data indicates that magnetic separation in alcohol is somewhat preferable to that in water. In Step 3 the remaining approximately one-quarter of the sulfur is removed by magnetic separation as Fe 1-x S. The troilite which was essential for the breaking of the thiophenic sulfur bond in Step 2 will be at least partially converted to pyrrhotite during the chemical desulfurization step.
  • pyrrhotite and especially monoclinic pyrrhotite Fe7S8 is highly ferromagnetic; it is an ideal candidate for magnetic separation and will result in a substantial savings in cost and process complexity by avoiding the necessity in prior art magnetic processes of oxidizing the iron sulfide form to magnetite or hematite to achieve the requisite magnetic strength for efficient separation.
  • the separation in Step 3 would be carried out on a stream of coal coming from the reactor of Step 2 at approximately 1000 tons per hour.
  • the magnetic field may be less than about 2 Teslas (20 kOe), which is in the range of iron core copper coil magnets.
  • superconducting magnets could be used in this field range to save power costs.
  • the power to generate the microwave energy for preferential heating would represent about 1% of the heating value of the coal while the power to operate the magnetic separator would be about 1% to 2% so that the total operating cost for power stated as a percentage of the heating value of the coal should not exceed 3% in accordance with the invention.
  • Step 3(a) (Block 24), as indicated by the dotted lines, may be utilized to remove the non-pyritic ash-forming minerals remaining after Step 2.
  • the second step of organic desulfurization ends with a desulfurized "char" in the residual alcohol.
  • Addition of a flocculant, such as Tergitol 7, (sodium heptadecyl sulphate) at this point, as described in Step 3(a) associates the non-pyritic minerals with the pyrrhotite for removal by magnetic separation.
  • Fig. 2 is a plot of the ratio of ash and sulfur levels in the feed and product for various magnetic separations where liquefied coal is passed through the separator at velocity (v).
  • the separation traps solid mineral particles from the liquid coal stream. There is little, if any, dependence on the velocity in the range up to 6 cm/s and it is likely that considerably higher flow velocities could be used.
  • the improvement obtained with the H2S treatment in the autoclave before separation is performed is clearly displayed in these plots. Note, also, the improvement in ash reduction when the flocculant was used in Runs 7 and 8 (Table 1). This plot serves to demonstrate both the improvement in sulfur removal by adjusting the FeS ratio of "pyrite" with H2S and the additional removal of non-pyrite ash minerals by using an organic flocculant.
  • preferential heating of the coal minerals may be accomplished with laser irradiation or inductive heating or radio-frequency irradiation in place of microwave frequencies. In some applications simply heating the whole coal may be employed.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Chemistry (AREA)
  • Solid Fuels And Fuel-Associated Substances (AREA)
EP87305399A 1986-04-14 1987-06-18 Verfahren und Vorrichtung zur Entschwefelung von Kohlen Withdrawn EP0295345A1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US06/851,924 US4678478A (en) 1986-04-14 1986-04-14 Method for desulfurization of coal
EP87305399A EP0295345A1 (de) 1987-06-18 1987-06-18 Verfahren und Vorrichtung zur Entschwefelung von Kohlen

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP87305399A EP0295345A1 (de) 1987-06-18 1987-06-18 Verfahren und Vorrichtung zur Entschwefelung von Kohlen

Publications (1)

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EP0295345A1 true EP0295345A1 (de) 1988-12-21

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EP87305399A Withdrawn EP0295345A1 (de) 1986-04-14 1987-06-18 Verfahren und Vorrichtung zur Entschwefelung von Kohlen

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105176626A (zh) * 2015-10-12 2015-12-23 中国矿业大学 一种脱除煤炭硫分的方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4052170A (en) * 1976-07-09 1977-10-04 Mobil Oil Corporation Magnetic desulfurization of airborne pulverized coal
FR2378087A1 (fr) * 1977-01-21 1978-08-18 Hazen Research Perfectionnements apportes aux procedes d'amelioration du charbon
US4148614A (en) * 1978-04-13 1979-04-10 Kirkbride Chalmer G Process for removing sulfur from coal
US4155715A (en) * 1977-09-06 1979-05-22 Occidental Petroleum Corporation Process for reducing the organic sulfur content of char
US4678478A (en) * 1986-04-14 1987-07-07 Massachusetts Institute Of Technology Method for desulfurization of coal

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4052170A (en) * 1976-07-09 1977-10-04 Mobil Oil Corporation Magnetic desulfurization of airborne pulverized coal
FR2378087A1 (fr) * 1977-01-21 1978-08-18 Hazen Research Perfectionnements apportes aux procedes d'amelioration du charbon
US4155715A (en) * 1977-09-06 1979-05-22 Occidental Petroleum Corporation Process for reducing the organic sulfur content of char
US4148614A (en) * 1978-04-13 1979-04-10 Kirkbride Chalmer G Process for removing sulfur from coal
US4678478A (en) * 1986-04-14 1987-07-07 Massachusetts Institute Of Technology Method for desulfurization of coal

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105176626A (zh) * 2015-10-12 2015-12-23 中国矿业大学 一种脱除煤炭硫分的方法
CN105176626B (zh) * 2015-10-12 2018-05-22 中国矿业大学 一种脱除煤炭硫分的方法

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