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WO1998039398A9 - Procede de traitement du charbon - Google Patents

Procede de traitement du charbon

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Publication number
WO1998039398A9
WO1998039398A9 PCT/US1998/004108 US9804108W WO9839398A9 WO 1998039398 A9 WO1998039398 A9 WO 1998039398A9 US 9804108 W US9804108 W US 9804108W WO 9839398 A9 WO9839398 A9 WO 9839398A9
Authority
WO
WIPO (PCT)
Prior art keywords
coal
fluidized bed
temperature
degrees fahrenheit
bed reactor
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.)
Ceased
Application number
PCT/US1998/004108
Other languages
English (en)
Other versions
WO1998039398A1 (fr
Filing date
Publication date
Priority claimed from US08/811,127 external-priority patent/US5830246A/en
Priority claimed from US08/928,858 external-priority patent/US5830247A/en
Priority claimed from US08/928,828 external-priority patent/US5858035A/en
Application filed filed Critical
Publication of WO1998039398A1 publication Critical patent/WO1998039398A1/fr
Publication of WO1998039398A9 publication Critical patent/WO1998039398A9/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Definitions

  • a process for irreversibly removing moisture from coal while simultaneously reducing its particle size is provided.
  • coals contain up to about 30 weight percent of moisture. This moisture not only does not add to the fuel value of the coal, but also is relatively expensive to transport .
  • United States patent 4,495,710 of Ottosan discloses a drying process in which par- ticulate low rank coal is dried in a fluidized bed in which the coal is fluidized above a first portion of a gas flow distributor using a hot fluidizing gas, and also above a second portion of the gas flow distributor using a recycle gas stream at a temperature less than about 200 degrees Fahrenheit.
  • the disclosure of each of these United States patents is hereby incorporated by reference into this specification.
  • the coal produced by the processes of the prior art tend to suffer from several disadvantages.
  • the drying processes used to produce them often are reversible, and when the coal is allowed to stand in the presence of a moisture-laden atmosphere, it regains some or all of its initial water content.
  • the coal In the second place, the coal is often likely to undergo spontaneous combustion upon standing in air.
  • a process for preparing an irreversibly dried coal In the first step of this process, there is provided a fluidized bed reactor with a fluidized bed density of from about 20 to about 40 pounds cubic feet, wherein said reactor is at a temperature of from about 150 to about 200 degrees Fahrenheit. To this reactor is fed coal with a moisture content of from about 25 to about 30 percent, an oxygen content of from about 10 to about 20 percent, and a volatile matter content of from about 35 to about 45 percent; and it is subjected to a temperature of from about 150 to about 200 degrees Fahrenheit for from about 1 to about 5 minutes while simultaneously being comminuted and dewatered.
  • the comminuted and dewatered coal is passed to a second fluidized bed reactor with a fluidized bed density of from about 20 to about 40 pounds per cubic foot and a reactor temperature of from about 480 to about 600 degrees Fahrenheit. Also fed to this second fluidized bed reactor is from about 0.5 to about 3.0 weight percent of mineral oil, thereby producing a coated coal.
  • Figure 1 is a schematic diagram of one preferred process of the instant invention.
  • FIG. 2 is a schematic diagram of another preferred process of the instant invention.
  • Figure 3 is a schematic of a test apparatus used to conduct certain experiments described in this specification.
  • Figures 4A, 4B, 4C, and 4D are graphs of data obtained from a series of experiments involving one of applicant's processes in which the bed temperature of the reactor, the carbon monoxide concentration in the off gas produced, the carbon dioxide concentration in the off gas produced, and the oxygen concentration in the off gas produced are plotted as a function of time and illustrated in Figures 4A, 4B, , 4C, and 4D, respectively.
  • the first of such processes is especially suitable for making a marketable coal from low rank coal.
  • the second of these processes is especially suitable for producing a marketable coal-fluid slurry from low rank coal, which normally contains 30 weight percent of water.
  • a low rank is is treated to produce a marketable coal is an economical process which produces irreversibly dried coal which is not susceptible to spontaneous combustion. In this process, the amount of coal fines in the finished product is minimized.
  • a particular coal is charged to a fluidized bed reactor 10, preferably by means of a coal feeder 12. It is essential that the coal used in this process have certain properties. If other coals are used, the process will not function as well.
  • the coal used in the process of Figure 1 contain from about 15 to about 30 weight percent of moisture and, more preferably, from about 20 to about 30 weight percent of moisture.
  • the moisture content of coal may be determined by standard A.S.T.M. testing procedures. Means for determining the moisture content of coal are well known in the art; see, e.g., United States patents 5,527,365 (irreversible drying of carbonaceous fuels), 5,503,646, 5 , 411 , 560 (production of bin- derless pellets from low rank coal), 5,396,260, 5 , 361 , 513 (apparatus for drying and briquetting coal), 5,327,717, and the like. The disclosure of each of these United States patents is hereby incorporated by reference into this specification.
  • the coal used in the process of Figure 1 contain at least about 10 weight percent of combined oxygen and, more preferably, from about 10 to about 20 weight of combined oxygen, in the form, e.g., of carboxyl groups, carbonyl groups, hydroxyl groups, and the like.
  • combined oxygen means oxygen which is chemically bound to carbon atoms in the coal. See, e.g., H.H. Lowry, Editor, “Chemistry of Coal Utilization” (John Wiley and Sons, Inc., New York, New York, 1963). Without wishing to be bound to any particular theory, applicant be lieves that his process will not function well unless the coal contains at least 10 weight percent of combined oxygen.
  • the combined oxygen content of coal may be determined by standard analytical techniques such as, e.g., United States patents 5,444,733, 5,171,474, 5,050,310, 4, 852 , 384 (combined oxygen analyzer), 3,424,573, and the like. The disclosure of each of these United States patents is hereby incorporated by reference into this specification.
  • the coal charged to reactor 10 contains at least about 10 weight percent of ash.
  • the coal charged to reactor 10 contains at least about 10 weight percent of ash.
  • ash refers to the inorganic residue left after the ignition of combustible substances; see, e.g., United States patents 5,534,137 (high ash coal), 5,521,132 (raw coal fly ash), 4,795,037 (high ash coal), 4,575,418 (removal of ash from coal), 4 , 486 , 894 (method and apparatus for sensing the ash content of coal), and the like.
  • United States patents 5,534,137 (high ash coal), 5,521,132 (raw coal fly ash), 4,795,037 (high ash coal), 4,575,418 (removal of ash from coal), 4 , 486 , 894 (method and apparatus for sensing the ash content of coal), and the like.
  • United States patents 5,534,137 (high ash coal), 5,521,132 (raw coal fly ash), 4,795,037 (high ash coal), 4,575,418 (removal of ash from coal), 4 , 486 , 894 (
  • the coal which is added to feeder assembly 12 may be, e.g., lignite, sub-bituminous, and bituminous coals. These coals are described in applicant's United States patent 5,145,489, the entire disclosure of which is hereby incorporated by reference into this specification.
  • the coal charged to reactor 10 preferably is 2" x 0", and more preferably 2" by 1/4" or smaller. As is known to those skilled in the art, 2" by 1/4" coal has all of its particles within the range of from about 0.25 to about 2.0 inches .
  • crushed coal conventionally has the 2" x 0" particle size distribution. This crushed coal can advantageously be used in applicant's process.
  • the process of United States patent 4,324,544 of Blake, by comparison, requires coal which has been ground to 8 mesh or smaller.
  • Feeder 12 can be any coal feeder commonly used in the art. Thus, e.g., one may use one or more of the coal feeders described in United States patents 5,265,774, 5, 030, 054 (mechanical/pneumatic coal feeder), 4 , 497 , 122 (rotary coal feeder), 4,430,963, 4 , 353 , 427 (gravimetric coal feeder), 4,341,530, 4, 142 , 868 ( rotary piston coal feeder), 4, 140,228(dry piston coal feeder), 4,071,151 (vibratory high pressure coal feeder with helical ramp), 4,149,228, and the like.
  • the disclosure of each of these United States patents is hereby incorporated by reference into this specification.
  • feeder 12 is comprised of a hopper (not shown) and a star feeder (not shown). As will be apparent to those skilled in the art, it is preferred that feeder 12 be capable of continually delivering coal to fluidized bed 10.
  • a star feeder is used.
  • a star feeder is a metering device which may be operated by a controller which controls the rate of coal removal from a hopper; see, e.g., United States patent 5,568,896, the entire disclosure of which is hereby incorporated by reference into this specification.
  • a fluidized bed 14 is provided in a reactor vessel 10.
  • the fluidized bed 14 is comprised of a bed of fluidized coal particles, and it preferably has a density of from about 20 to about 40 pounds per cubic foot. In one embodiment, the density of the fluidized bed 20 is from about 20 to about 30 pounds per cubic foot.
  • the fluidized bed density is the density of the bed while its materials are in the fluid state and does not refer to the particulate density of the materials in the bed.
  • Fluidized bed 14 may be provided by any of the means well known to those skilled in the art. Reference may be had, e.g., to applicant's United States patents 5,145,489, 5,547,549, 5 , 546 , 875 ( heat treatment of coal in a fluidized bed reactor), 5, 197 , 398 (separation of pyrite from coal in a fluidized bed), 5 , 087 , 269 (drying fine coal in a fluidized bed), 4,571, 174(drying particulate low rank coal in a fluidized bed), 4, 495, 710 (stabilizing particulate low rank coal in a fluidized bed), 4 , 324 , 544 (drying coal by partial combustion in a fluidized bed), and the like.
  • Fluidized bed 14 is preferably maintained at a temperature of from about 150 to about 200 degrees Fahrenheit. In a more preferred embodiment, the fluidized bed 14 is maintained at a temperature of from about 165 to about 185 degrees Fahrenheit.
  • Various means may be used to maintain the temperature of fluidized bed 14 at a temperature of from about 150 to about 200 degrees Fahrenheit. Thus, e.g., one may use an internal or external heat exchanger (not shown). See, e.g., United States patents 5,537,941, 5,471,955, 5,442,919, 5,477,850, 5,462,932, and the like.
  • hot gas from, e.g., a separate fluidized bed reactor 18 is fed via line 20 into fluidized bed 14.
  • This hot gas preferably is at temperature of from about 480 to about 600 degrees Fahrenheit and, more preferably, at a temperature of from about 525 to about 575 degrees Fahrenheit.
  • the coal removed from fluidized bed 14 is partially dehydrated.
  • the untreated coal charged to reactor 10 generally has a moisture content of from about 25 to about 30 weight percent.
  • the coal which is removed from fluidized bed 14 generally contains no more than about 15 weight percent moisture .
  • the partially dehydrated coal is passed via line 22 to fluidized bed reactor 18, in which a fluidized bed 24 is preferably maintained at a temperature of from about 480 to about 600 degrees Fahrenheit and, more preferably, from about 525 to about 575 degrees Fahrenheit.
  • the fluidized bed 24 is fluidized with the air introduced via line 26, and the temperature of the bed is controlled with the water introduced via line 28.
  • the dehydrated coal, air, and water are introduced at rates sufficient to produce a fluidized bed with a density of from about 20 to about 40 pounds per cubic foot and, more preferably, from about 25 to about 35 pounds per cubic foot.
  • air may be flowed into the system via line 26.
  • the air may be at ambient temperature, or it may be heated, as required, to maintain the desired temperature.
  • liquid water may be introduced via line 28. Again, depending upon the temperature control desired, the liquid water may be at ambient temperature.
  • the quantities of air and/or water, and their temperatures, may be varied to maintain the desired temperature within the fluidized bed 24.
  • the temperature within fluidized bed 24 may be monitored by conventional means such as, e.g., by means of thermocouple 30.
  • the coal fed to fluidized bed 24 via line 22 preferably is maintained in fluidized bed 24 for from about 1 to about 5 minutes, and preferably for from about 2 to about 3 minutes, while being subjected to the aforementioned temperature of from about 480 to about 600 degrees Fahrenheit.
  • oil is fed via line 32 into fluidized bed 24.
  • the oil used in the process preferably has an initial boiling point of at least 900 degrees Fahrenheit.
  • Mineral oils are derived from petroleum coal, shale and the like and consist essentially of hydrocarbons. Thus, e.g., one may use residual fuel oil, heavy crude oil, coal tars, and the like, as long as they have an initial boiling point at least 900 degrees Fahrenheit.
  • the initial boiling point of a mineral oil is the recorded temperature when the first drop of distilled vapor is liquefied and falls from the end of the condenser. See, e.g., United States patents 5,451,312 (initial boiling point of a hydrocarbon fraction), 5,382,728 (initial boiling point of a hydrocarbon blend), 5,378,739, 5,370,808 (initial boiling point of a petroleum oil), and the like.
  • the oil used is residual fuel oil.
  • Residual fuel oil which is often referred to as “residual oil,” refers to the combustible, viscous, or semiliquid bottoms produced from crude oil distillation. see, e.g., United States patents 4,512,774, 4,462,810, 4,404,002, 4,297,110, 3,977,823, 3,691,063, and the like.
  • the oil fed via line 32 preferably is fed at rate so that, within fluidized bed 24, from about 0.5 to about 3.0 weight percent of such oil is present, based upon the weight of dried coal withdrawn from fluidized bed 24 via line 34.
  • the oil fed via line 32 preferably is fed at rate so that, within fluidized bed 24, from about 0.5 to about 3.0 weight percent of such oil is present, based upon the weight of dried coal withdrawn from fluidized bed 24 via line 34.
  • the dried coal produced in applicant's process contains from about 0.5 to about 3.0 weight percent of oil (by weight of dried coal), and from about 0 to about 2.0 weight percent of moisture.
  • the comminution of the coal is enhanced by conventional attrition devices. It is known to those that attrition may be increased by the addition of impact targets or other such devices .
  • the coal produced by applicant's process is irreversibly dried. Thus, when such coal is allowed to sit in an environment at a temperature of 25 degrees Centigrade at a relative humidity of exceeding 50%, it will pick up less than 2.0 percent of moisture from this environment in 48 hours.
  • the dried coal produced by applicant's process contains from about 0 to about 2 weight percent of moisture, from about 8 to about 10 weight percent of ash, from about 36 to 39 weight percent of volatile matter, and from about 50 to about 65 weight percent of carbon.
  • the dried coal produced by this embodiment contains a relatively large amount of volatile matter.
  • Volatile matter is any material which volatilizes at a temperature of 900 degrees Centigrade in an inert atmosphere, and its presence in coal may be analyzed by conventional means. See, e.g., United States patents 5,605,722, 5,601,631, 5,568,777, 5,551,958, 5,512,074, 5,435,983, 5,389,117, 5,374,297, 5,366,537, 4,459,103 (automatic volatile matter content analyzer), 4,257,778 (process for preparing coal with a high volatile matter content), and the like.
  • FIG. 2 is a schematic representation of this process, which is especially suitable for producing a coal/liquid slurry from the low rank coal.
  • the low rank coal described elsewhere in the specification is fed into feeder 12 and thence into fluidized bed reactor 50.
  • Air is fed into reactor 50 via line 26 and a sufficient rate vis-a-vis the coal feed to maintain the fluidized bed 52 so that its temperature is from about 480 to about 600 degrees Fahrenheit and its density is from about 20 to about 40 pounds per cubic foot.
  • Water is fed to the fluidized bed 52 via line 28 as necessary to provide temperature control.
  • the fluidized bed 52 is substantially identical to the fluidized bed 24 (see Figure 1) with the exception that the coal fed to bed 52 is not at least partially dehydrated, and with the additional exception that the coal fed to bed 52 is not at least partially comminuted.
  • the coal fed to bed 52 contains at least about 25 weight percent of moisture, depending upon ambient conditions, and frequently contains at least about 30 weight percent of moisture.
  • the coal fed to bed 52 generally has a particle size in the range of from 2" by 0".
  • cyclone 54 the cyclones described in United States patents 5,612,003 (fluidized bed with cyclone), 5,174,799 (cyclone separator for a fluidized bed reactor), 5,625,119, 5,562,884, and the like.
  • the fine portion from cyclone 54 is passed via line 60 a second cyclone 62.
  • the fine portion from cyclone 62 is contacted with a fine portion from elutriator 64 at point 66, and the mixture thus produced is then passed via line 68 to quench vessel 70, wherein water is added via line 72.
  • the quenched product is then passed via line 74 to a coal-water fuel preparation plant (not shown).
  • comminuted coal from fluid bed 52 is passed via line 76 to elutriator 64.
  • the function of elutriator 64 is to separate fine particles from coarser particles by means of gravity.
  • Air is added to elutriator 64 via line 78 and acts as the elutriating gas.
  • the coarse fraction from elutriator 64 is recycled and passed via line 80 back to fluidized bed 52 for additional comminution.
  • Elutriating gases other than air may be used.
  • the cyclone separator 62 is designed to capture any solids which leave cyclone 54 via overhead line 60 and to return them to the system. These solids are passed via line 82, where the stream of solids contacts a stream of gas and solids from elutriator 64 (via line 84) at point 66.
  • the mixture of materials from lines 82 and 84 is passed via line 68 to quench 70, wherein it is contacted with water which introduced into quencher 70 via line 72. It is preferred that the water be at ambient temperature, and it is preferred that be introduced at a rate sufficient to reduce the temperature of the coal particles within about 5 seconds to ambient temperature.
  • the coal from quencher 70 is passed to a ixer/qrinder/blender 84 via line 86 wherein it may be mixed with one or more additional coal fractions to obtain any desired particle size distribution.
  • the blending occurs in such a manner to approach the particle size distribution disclosed in United States patent 4,282,006. If the nature of the coal fraction(s) in mixer/grinder/blender is not suitable for making such particle size distribution, the coal may be further ground as disclosed in such patent.
  • the slurry produced in applicant's process possesses some unexpected, beneficial results. It is substantially more combustible than prior art slurries.
  • coal segments after the coal segments have been blended in blender 84 they then may be beneficiated in a froth flotation cell or other conventional coal cleaner 90.
  • Froth flotation cleaning of coal is well known; see, e.g., United States patents 5,379,902, 4,820,406, 4,770,767, 4,701,257, 4,676,804, 4,632,750, 4,532,032, and the like.
  • the ash may be removed from froth flotation cell 90 via line 92, and the cleaned coal may be passed to slurry preparation tank 93 via line 94.
  • the cleaned coal is used to prepare a coal-water slurry in accordance with the teachings of United States patent 4 , 477 , 259.
  • This slurry preferably contains from about 60 to about 82 weight percent of coal, from about 18 to about 40 weight percent of carrier liquid (such as, e.g., water), and from about 0.1 to about 4.0 weight percent, by weight of dry coal) of dispersing agent.
  • This slurry preferably has a specific surface area of from about 0.8 to about 4.0 square meters per cubic centimeter and an interstitial porosity of less than 20 volume percent.
  • the slurry has a particle size distribution such that from about 5 to about 70 weight percent of the particles of coal in the slurry are of colloidal size, being smaller than about 3 microns.
  • unit 100 was comprised of a 12" diameter x 6 foot high reactor chamber 102 into which was charged 100 pounds of sand 104 via line 106.
  • the sand was disposed in the bed to act as a diluent and a heat transfer medium.
  • the top of the fluidized bed was connected to a disengaging chamber 108 which had an inner diameter of 2.0 feet and a length of 6 feet.
  • the coal was charged via coal supply vessel 110 after the sand had been brought the desired temperature.
  • the fluid bed section 114 was heated by an annular burner 116.
  • the sand was fluidized with either pure air, or air/nitrogen mixtures, which were introduced into the system by line 118.
  • coal was added to produce a fluidized bed density of about 30 pounds per cubic foot.
  • the off gas produced was continually monitored by an oxygen sensor (not shown), a carbon monoxide sensor (not shown), and a carbon dioxide sensor (not shown). Furthermore, the temperature of the fluidized bed was recorded about every five minutes.

Abstract

L'invention porte sur un procédé de préparation de charbon irréversiblement déshydraté utilisant un réacteur à lit fluidisé (10) dont le lit fluidisé (14) présente une densité d'environ 20 à environ 40 livres par pied cubique et dont la température est comprise entre environ 150 et environ 200 °F. Ledit réacteur est alimenté en charbon (12) dont la teneur en humidité est comprise entre environ 25 et environ 30 %, la teneur en O, entre environ 10 et environ 20 %, et la teneur en matières volatiles, entre environ 35 et environ 45 %, maintenu entre environ 150 et environ 200 °F pendant environ 1 à environ 5 minutes tout en étant simultanément fragmenté et déshydraté. Le charbon fragmenté et déshydraté passe (22) ensuite dans un deuxième réacteur à lit fluidisé (18) dont le lit fluidisé (24) présente une densité d'environ 20 à environ 40 livres par pied cubique et dont la température est comprise entre environ 480 et environ 600 °F, et en outre alimenté en huile minérale (32) représentant entre environ 0,5 et environ 3,0 % en poids.
PCT/US1998/004108 1997-03-03 1998-03-03 Procede de traitement du charbon Ceased WO1998039398A1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US08/811,127 1997-03-03
US08/811,127 US5830246A (en) 1997-03-03 1997-03-03 Process for processing coal
US08/928,828 1997-09-12
US08/928,858 US5830247A (en) 1997-03-03 1997-09-12 Process for processing coal
US08/928,858 1997-09-12
US08/928,828 US5858035A (en) 1997-03-03 1997-09-12 Process for processing coal

Publications (2)

Publication Number Publication Date
WO1998039398A1 WO1998039398A1 (fr) 1998-09-11
WO1998039398A9 true WO1998039398A9 (fr) 1999-02-25

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Application Number Title Priority Date Filing Date
PCT/US1998/004108 Ceased WO1998039398A1 (fr) 1997-03-03 1998-03-03 Procede de traitement du charbon

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CA (1) CA2251896A1 (fr)
WO (1) WO1998039398A1 (fr)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113252105B (zh) * 2021-05-13 2021-11-16 中国安全生产科学研究院 一种硫化矿石存储隐患检测方法及系统

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU530284B2 (en) * 1979-07-20 1983-07-07 Mitsui Kozan Chemicals Co. Ltd. Treating water containing coal
US5035721A (en) * 1989-03-30 1991-07-30 Electric Power Research Institute, Inc. Method for beneficiation of low-rank coal
GB9324328D0 (en) * 1993-11-26 1994-01-12 Ca Nat Research Council Drying fuel
DE4446401C2 (de) * 1993-12-27 1998-07-02 Kobe Steel Ltd Fester Brennstoff, hergestellt aus poröser Kohle und Verfahren und Vorrichtung zu dessen Herstellung
US5503646A (en) * 1994-06-30 1996-04-02 Fording Coal Limited Process for coal - heavy oil upgrading

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