Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B5/00—Making pig-iron in the blast furnace
• • 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
  • C10L9/10—Treating solid fuels to improve their combustion by using additives
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
  • B65G53/00—Conveying materials in bulk through troughs, pipes or tubes by floating the materials or by flow of gas, liquid or foam
  • B65G53/34—Details
  • B65G53/52—Adaptations of pipes or tubes
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B5/00—Making pig-iron in the blast furnace
  • C21B5/001—Injecting additional fuel or reducing agents
  • C21B5/003—Injection of pulverulent coal

Definitions

• the present invention relates to a trans ⁇ portability improver for pulverized coal which can improve the transportability of the pulverized coal to be injected into a metallurgical furnace or combustion furnace through an injection tuyere or inlet and thereby enables stable injection thereof into the furnace at a high feed rate, and a process for the operation of a metallurgical furnace or combustion furnace by the use of this transportability improver.
• coal has been reconsidered as a substitute for fuel oil.
• CWM coal-water mixture
• COM coal-oil mixture fuel
• pulverized coal a pulverized coal combustion furnace is particularly noted, because it can dispense with other media such as water or oil.
• a pulverized coal combustion furnace also has the same problems as those occurring in the use of pulverized coal in a blast furnace.
• the process of injecting pulverized coal into a furnace comprises the preparation of pulverized coal by dry pulverization of raw coal, classi ication of the pulverized coal, storage thereof in a hopper, discharge thereof from a hopper, pneumatic transportation thereof through pipeline, injection thereof into a metallurgical or combustion furnace through an injection tuyere and combustion thereof in the furnace, among or the group consisting of which discharge of pulverized coal from a hopper and pneumatic transportation thereof through pipeline have the following problems.
• the variety, particle size and water content of pulverized coal affect the fundamental physical properties (such as fluidity) thereof, thus having a great influence also on the discharge thereof from a hopper and transportation thereof through pipeline.
• pulverized coal having fundamental physical properties deviating from the optimum range causes the hanging and channeling in the hopper and choking of the pipeline during pneumatic transportation, so that the injection of such pulverized coal into the furnace is difficult to continue stably for a long time.
• the amount of the pulverized coal injected into a blast furnace through an injection tuyere in the current operation of the furnace is about 50 to 250 kg/t of pig iron, it is desirable in cost to increase the amount of pulverized coal injected into the furnace.
• the above processes fail in increasing the amount thereof remarkably, because the transportability of pulverized coal is not always satisfactory.
• the present invention aims at solving the problems of the prior art processes i.e., at preventing the choking of the pipeline and the handing in the hopper by improving the transportability of pulverized coal to thereby enable stable injection of pulverized coal into the furnace at an enhanced change rate without any limitation on the variety of coal.
• the inventors of the present invention have intensively studied to attain the above object and have found that the transportability of pulverized coal originating from raw coal having an average HGI of 30 or above is remarkably improved by adhering an organic compound which has a polar group and is substantially water-soluble to the pulverized coal.
• the present invention has been accomplished on the basis of this finding.
• the present invention provides a trans ⁇ portability improver for pulverized coal characterized by comprising an organic compound which has a polar group and is substantially water-soluble and being applied to dry pulverized coal originating from raw coal having an average HGI of 30 or above, and pulverized coal comprising such a transportability improver, and finely pulverized coal. Further, the present invention also provides a process for the operation of a metallurgical furnace or combustion furnace by the use of the above transportability improver and finely pulverized coal.
• an organic compound which is water- soluble refers to one satisfying the requirements that no milky turbidity appears when 10 times (by weight) as much water (ion-exchanged water at 10"C) is added to an organic compound in a powdered state, and that when the resulting mixture is filtered through a membrane filter having a mesh size of 0.1 ⁇ , the amount of the filter cake is 10% by weight or below based on the amount of the organic compound used in this test.
• the process for the operation of a metallurgical furnace or combustion furnace by the use of the transportability improver according to the present invention is characterized by adding the trans ⁇ portability improver to pulverized coal in an amount of 0.01 to 10% by weight, preferably from the standpoint of transportability improving effect, 0.05 to 5% by weight to thereby decrease the quantity of triboelectrification of the pulverized coal, and thereafter injecting the pulverized coal thus treated into a metallurgical furnace or combustion furnace through an injection tuyere.
• the amount of the transportability improver added to pulverized coal may be 0.01% by weight or above to attain the trans ⁇ portability improving effect, while the addition thereof in an amount exceeding 10% by weight cannot give any additional effect uneconomicall .
• the pulverized coal to be used in the present invention is dry one originating from raw coal having an average HGI of 30 or above.
• dry refers to the state having a water content of 10% by weight or below as calculated based on the weight loss found in the drying according to JIS M 8812-1984. Pulverized coal haying too high a water content is unsuitable for use as the fuel to be injected into a metallurgical furnace or combustion furnace.
• the use of the transportability improver according to the present invention enables smooth transportation of such pulverized coal. Further, the present invention is effective even for pulverized coal originating from raw coal having an average HGI of 50 or above, though such pulverized coal is very difficult to transport by the current pneumatic transportation technique.
• HGI Hardgrove Griding Index
• the inventors of the present invention have elucidated that the above problems of pulverized coal is due to the electrification of between the pulverized coals and have found that the above problems can be solved by decreasing the quantity of triboelectrification of pulverized coal. Further, they have found that there is a high interrelation between the quantity of triboelectrification of pulverized coal and the fluidity index or pipelining characteristics thereof.
• Pulverized coal exhibiting poor transportability is characterized in that many finer coal particles adhere to an ordinary coal particle having a particle size near the mean size, while one having excellent transportability is characterized in that few finer coal particles adhere thereto.
• the strong adhesion of finer coal particles to an ordinary coal particle worsens the fluidity of pulverized coal, because (1) the apparent shape of pulverized coal is distorted by the adhesion of finer coal particles and (2) the finer coal particles adherent to an ordinary coal particle adhere also to another ordinary coal particle to act just like a binder.
• the transportability of the pulverized coal can be improved by adding the trans ⁇ portability improver thereto to thereby decrease the quantity of triboelectrification to 2.8 ⁇ C/g or below.
• the quantity of triboelectrification given in this invention is one determined by the method which will be described in the Example in detail.
• Fluidity index and pressure loss in pipelining which will be described in the Example in detail, were used as the indication of the transportability of pulverized coal.
• the discharge characteristics of pulverized coal from a hopper can be simulated based on the fluidity index thereof, while the flow characteristics of pulverized coal in a pipeline during pneumatic transportation can be simulated based on the pressure loss.
• the fluidity index In order to attain an improvement in the transportability of pulverized coal according to the present invention, the fluidity index must be enhanced by at least three points and the pressure loss must be lowered by at least 3 mm O/m. Further, when pulverized coal is very poor in transportability, the fluidity index must be enhanced to 40 or above and the pressure loss must be lowered to 16 or below.
• the inventors of the present invention have further advanced studies and have found that an organic compound which has a polar group and is substantially water-soluble is suitable for decreasing the quantity of triboelectrification of pulverized coal to thereby improve the transportability thereof.
• the transportability improver according to the present invention serves to decrease the quantity of triboelectrification of pulverized coal and comprises a compound having at least one polar group selected from among carboxylic and sulfonic acid groups and salts thereof, amide, sulfuric acid and salts thereof, amine salt, nitrile, phenol group, and salts thereof and so forth.
• the transportability improver be one or more members selected from among anionic surfactants, cationic surfactants, amphoteric surfactants, lower aliphatic acids, and lower aliphatic acid salts.
• the transportability improver be used as liquid either as such or in a state dissolved in a solvent at a proper concentration.
• the concentration be 1% by weight or above.
• the use of water as the solvent is preferable from the standpoint of easiness in dryness of the solvent.
• the transportability improver of the present invention may be added either before or after the pulverization of raw coal and the effects attained in both of the cases are equivalent.
• anionic, cationic and amphoteric surfactants include the following:
• Alkyl ether carboxylic acid salts R0(CH 2 CH 2 0) n CH 2 C00M [R: Cg to C 20 ; M: H, Na, K, NH 4 , organic amine salts or the like; n: 0 to 40]
• Lignosulfonic acid salts salts of lignosulfonic acid with sodium, calcium, potassium, ammonium, triethanol- amine and so forth
• Sulfated oils turkey red oil (lowly sulfated castor oil), lowly sulfated olive oil, sulfated beef tallow and sulfated peanut oil
• MO 0 [R: Cg to C 20 ; M: H, Na, K, NH 4 , organic amine salts or the like; n: 0 to 40]
• Examples of the vinylic monomers constituting the above (co)poly ers include vinylpyrrolidone, acrylo ⁇ nitrile, acrylic acid, methacrylic acid, maleic acid and salts of these acids with alkali metals and ammonium, and vinylsulfonic acid, methallylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, styrenesulfonic acid and salts of these acids with alkali metals and ammonium. 22.
• Condensates (average molecular weight: 1000 to 1000000) of aliphatic aldehydes with one or more members selected from among naphthale"nesulfonic acid and salts thereof, melaminesulfonic acid and salts thereof, phenolsulfonic acid and salts thereof, and ligninsulfonic acid and salts thereof.
• the above salts includes the salts with alkali metal cations and ammonium.
• R 2 [R: Cg to C 20 ; R j , R 2 : CH 3 ; X: inorganic or organic acid]
• Homopolymers comprising one member selected from among nitrogenous monomers represented by the following general formulae (I) to (IX) and salts thereof, and copolymer comprising two or more members selected from among them.
• R 6 [wherein R 4 represents a hydrogen atom or a methyl group; Rg and Rg each represent a hydrogen atom or an alkyl group having 1 to
• R 6 [wherein m ⁇ is a number of 1 to 3; n j is a number of 1 to 3; and R 4 , R 5 and Rg are each as defined above]
• R represents a hydrogen atom or an alkyl or alkyloyl group having 1 to 3 carbon atoms; and R 4 is as defined above]
• formula (I) examples include 3-methacryloxy-2-hydroxypropyldimethylamine , 3-methacryloxy-2-hydroxypropylethylmethylamine, 3-methacryloxy-2-hydroxypropyldiethylamine, 3-methacryloxy-2-hydroxypropyldipropylamine , and so forth; those of the formula (II) include N,N-dimethylaminomethylene-capped ethylene glycol methacrylate , N,N-dimethylaminopropylene-capped ethylene glycol methacrylate,
• Copolymers comprising one or more vinylic monomers selected from the group consisting of ⁇ , ⁇ -unsaturated carboxylic acids and salts and derivatives thereof, sulfonated vinyl compounds and salts thereof, acrylo ⁇ nitrile, vinylpyrrolidone, and aliphatic olefins having 2 to 20 carbon atoms and one or more members selected from among the nitrogenous monomers represented by the above formulae (I) to (IX) and salts thereof.
• vinylic monomer examples include vinyl ⁇ pyrrolidone, acrylonitrile; acrylic acid, methacrylic acid, maleic acid, salts of these acids with alkali metals and ammonium, and amide compounds and esters of the acids, and vinylsulfonic acid, methallylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, p-styrenesulfonic acid and salts of these acids with alkali metals and ammonium.
• Specific examples of the product include those composed of repeating units represented by the following general formula (X) and having an average molecular weight of 1,000 to 1,000,000.
• n 3 is an integer of 1 to 5; and n 4 is an integer of 0 to 5]
• Rg is as defined above; Rg represents an alkyl group having 1 to 8 carbon atoms; R 10 represents a hydrogen atom or a methyl group; and ng and n 7 are each an integer of 1 to 10] 33.
• Polycondensates of dihaloalkanes with polyalkylenepolya ines; and salts and quaternary ammonium salts thereof Specific examples thereof include quaternary ammonium salts of polycondensates of dihaloalkanes (such as 1,2-dichloroethane, 1,2-dibromoethane, 1,3- dichloropropane, and so forth) with polyalkylene ⁇ polyamines having at least two tertiary amino groups in the molecule, the average molecular weight thereof ranging from 1,000 to 1,000,000.
• polyalkylenepolyamine examples include tetramethylethylenediamine, tetramethylpropylene- diamine, pentamethyldiethylenetriamine, hexamethylene- tetramine, triethylenediamine, and so forth.
• RJ to R 13 represents a methyl group or an ethyl group; and X represents a halogen atom
• Examples of the lower aliphatic acids include mono- and di- aliphatic acids having 1 to 8 carbon atoms. Specific examples thereof include formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, adipic acid, maleic acid and caproic acid.
• Those of the lower aliphatic acid salts include sodium, potassium and ammonium salts of formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, adipic acid, maleic acid and caproic acid.
• the metallurgical furnace and combustion furnace according to the present invention include furnaces using pulverized coal as the fuel and/or reducing agent (for example, shaft furnace, cupola, rotary kiln, smelting reduction furnace, cold iron charge melting furnace, and boiler) and dry distillation equipment using pulverized coal (for example, fluidized bed dry distillation furnace and gas reforming furnace).
• pulverized coal for example, shaft furnace, cupola, rotary kiln, smelting reduction furnace, cold iron charge melting furnace, and boiler
• dry distillation equipment using pulverized coal for example, fluidized bed dry distillation furnace and gas reforming furnace.
• pulverized coal originating from raw coal having an average HGI of 30 or above can be improved in transportability by lowering the quantity of triboelectrification thereof to thereby enable the mass transport of such pulverized coal. Further, even pulverized coal poor in transportability can be improved in the trans ⁇ portability by the addition of the transportability improver of the present invention to enable mass transpotation of such pulverized coal, by which the variety of coal usable in pulverized coal injection can be widened.
• the pulverized coal treated with the transportability improver of the present invention to be injected into the furnace through an injection tuyere is so excellent in fluidity as to prevent hanging from occurring in a hopper.
• the change in the amount of the coal taken out of a hopper with time and the deviation of the amount of distribution can be remarkably reduced.
• each of the raw coals listed in Tables 1 to 9 and each of the transportability improvers listed therein are fed into a pulverizer [small-scale pulverizer SCM-40A mfd. by Ishizaki Denki Seisaku-sho] and pulverized and mixed together therein for such a time as to give particles of a desired diameter.
• the transportability improver is added in a state dissolved in each of the solvents listed in Tables 1 to 9 in an amount (based on the pulverized coal) specified therein while pulverizing the raw coal.
• the resulting pulverized coal is filtered through a screen having a mesh size of 106 ⁇ m to recover pulverized coal having a particle size of 106 ⁇ m or below.
• the water content of the pulverized coal is adjusted to 0.5 to 1.0%, while the volume-average diameter thereof is adjusted to 75 ⁇ m.
• volume-average diameter is defined by the following formula:
• the pulverized coal samples prepared above were evaluated for quantity of triboelectrification, fluidity index and pipelining characteristics by the following methods to determine the effects of the additives.
• the quantity of triboelectrification of pulverized coal was determined by the use of a blowoff type instrument as shown in Fig. 1, wherein numeral 1 refers to compressed gas, 2 nozzle, 3 Faraday gauge, 4 mesh having an opening of 38 ⁇ m, 5 dust hole, and 6 electrometer.
• a blowoff type instrument is generally used for determining the quantity of triboelectrification between different kinds of substances having different particle diameters (e.g., between toner and carrier).
• a mesh having an opening of 38 ⁇ m was used and 0.1 to 0.3 g of each pulverized coal sample was put thereon.
• Compressed gas such as air was applied at 0.6 kgf/cm 2 onto the coal sample to thereby blow off coal particles having a diameter of 38 ⁇ or below into the dust hole.
• the quantity of triboelectrification of the coal particles having a diameter of 38 ⁇ or below was measured.
• Fluidity index is an indication for evaluating the fluidly of powder, which is determined by converting the each factor of powder (i.e., angle of repose, compressibility, spatula angle and extent of agglomeration) into indexes respectively and calculating the sum of the indexes.
• the methods for determining the each factor and the indexes are described in detail in "Funtai Kogaku Binran (Handbook of Powder Technology)” (edited by the Society of Powder Technology, Japan, and published by Nikkan Kogyo Shinbunsha (1987)) pp. 151 and 152. The methods for determining the above each factor will now be described.
• Angle of repose determined by filtering a powdery material through a standard sieve (25-mesh), pouring the material onto a circular plate having a diameter of 8 mm through a funnel, and measuring the inclination of the accumulation formed on the plate.
• Spatula angle determined by inserting a spatula having a width of 22 mm into an accumulation of a powdery material, elevating the spatula to form an accumulation thereon, measuring the inclination of the accumulation, applying a light impact to the spatula to make the accumulation reshape, measuring the inclination of the resulting accumulation, and averaging the inclinations.
• Extent of agglomeration determined by piling three sieves different from each other in opening (60, 100 and 200 mesh in the order of from the top to the bottom) , putting 2 g of a powdery material on the top sieve, vibrating the three sieves simultaneously, measuring the weights of the material remaining on the sieves respectively, and summing the three values calculated by the following formulae:
• each fluidity index was determined by calculating the sum of indexes of angle of repose, compressibility and spatula angle.
• each pulverized coal sample was evaluated for pipelining characteristics by determining the pressure loss thereof by the use of equipment shown in Fig. 2 according to the method described in "CAMP-ISIJ" vol.6, p.91 (1993) in detail.
• numeral 7 refers to pulverized coal
• 8 table feeder 9 flowmeter
• 10 horizontal pipe having a diameter of 12.7 mm, and 11 cyclone.
• the pulverized coal 7 discharged from the feeder 8 was pneumatically transported with a carrier gas to determine the pressure loss between pressure measuring holes (P j and P 2 ) .
• This experiment was conducted under the following conditions: feed rate of pulverized coal: 0.8 kg/min carrier gas: nitrogen (N 2 ) feed rate of carrier gas: 4 Nm 3 /h (67 litter/min) transportation time: 6 min.
• the sampling of data was conducted at pressure gauges P j and P at 500 Hz.
• the pressure loss was determined by calculating the whole mean of (P j - P 2 ) over the transport time (6 min).
• ⁇ p _ ⁇ n l (p -n ⁇ p an )
• (C) copolymer comprising phosphoric acid salt of diethylaminoethyl methacrylate and sodium methacrylate at a ratio of 4 : 5 (MW: 20,000)
• (E) copolymer comprising ethylphosphinous acid salt of dimethylaminoethyl methacrylate and sodium acrylate at a ratio of 3 : 1 (MW: 300,000)
• AA 1 mixture of polyethyleneimido phosphonate (MW: 60,000) and ethylphosphinic acid salt of dimethylaminoethyl methacrylate (MW: 60,000)
• (BB) copolymer comprising 3-methacryloxy-2-hydroxy- propyltrimethylammonium phosphate and ethylphosphinic acid salt of dimethylaminoethyl methacrylate at a ratio of 2 : 1 (MW: 50,000)
• CC mixture comprising phosphonic acid salt of methacryl dimethylaminoethylethoxylate (MW: 80,000) and polyethyleneimine (MW: 80,000) at a ratio of 1 : 1
• FIG. 3 shows a schematic view of the equipment for injecting pulverized coal into a blast furnace used in this Example.
• numeral 12 refers to a blast furnace, 13 injection tuyere, 14 injection pipeline, 15 distribution tank, 16 valve, 17 pressure- equalizer tank, 18 valve, 19 pulverized coal storage tank, 20 coal pulverizer, 21 additive spraying nozzle, 22 belt conveyer for coal transportation, 23 coal- receiving hopper, and 24 air or nitrogen compressor.
• Coal is thrown into the receiving hopper 23 and fed into the pulverizer 20 by the conveyer 22.
• the coal is sprayed with a transportability improver ejected from the nozzle 21.
• the resulting coal is pulverized by the pulverizer 20 into particles having the above diameter and the pulverized coal thus prepared is transferred to the storage tank 19.
• the valve 18 is opened in a state wherein the internal pressure of the equalizer tank 17 is equal to the atmospheric pressure to feed a predetermined amount of the pulverized coal into the equalizer tank 17 from the storage tank 19. Then, the internal pressure of the tank 17 is enhanced to the same level as that of the distribution tank 15.
• the valve 16 is opened in a state wherein the internal pressure of the tank 15 is equal to that of the tank 17, by which the pulverized coal drops by gravity.
• the pulverized coal is pneumatically transported by compressed air fed by the compressor 24 from the distribution tank 15 to the injection tuyere 13 through the injection pipeline 14 and injected into the blast furnace 12 through the injection tuyere 13.
• the line (a) shows the result obtained without adding any transportability improver and the line (b) shows that obtained with the above transportability improver.
• the line A shows the acceptable upper limit of the equipment.
• Fig. 7 shows a schematic view of the pulverized coal fired boiler used in this Example.
• numeral 25 refers to a combustion chamber of a boiler, 26 burner, 27 injection pipeline, 28 pulverized coal storage tank, 29 coal pulverizer, 30 additive spraying nozzle, 31 belt conveyer for coal transportation, 32 coal receiving hopper, and 33 air or nitrogen compressor.
• Coal is thrown into the receiving hopper 33 and fed into the pulverizer 29 by the conveyer 31.
• the coal is sprayed with a transportability improver ejected from the nozzle 30.
• the resulting coal is pulverized by the pulverizer 29 into particles having the above diameter and the pulverized coal thus prepared is transferred to the storage tank 28.
• the pulverized coal is pneumatically transported by compressed air fed from the compressor 33, fed into the burner 26, and fired therein.
• pulverized coal was conducted under the above conditions to determine the influence of the addition of the transportability improver on the pressure loss occurring in the injection pipeline 27 (i.e., the pressure difference between the tank 28 and the burner 26).
• the results are given in Fig. 8, wherein the line A shows the acceptable upper limit of the equipment and X represents the occurrence of choking of the pipeline.
• Fig. 8 shows relative evaluation wherein the value obtained when pulverized coal originating from raw coal having an average HGI of 45 is used without adding any improver thereto is taken as 1.

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• 1995
  • 1995-09-28 EP EP95932929A patent/EP0783589A1/de not_active Withdrawn
  • 1995-09-28 WO PCT/JP1995/001976 patent/WO1996010093A1/en not_active Application Discontinuation
  • 1995-09-28 CN CN95195383A patent/CN1159834A/zh active Pending
• 1997
  • 1997-03-15 KR KR1019970701704A patent/KR970706406A/ko not_active Application Discontinuation

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