WO1996010093A1

WO1996010093A1 - Transportability improver for pulverized coal

Info

Publication number: WO1996010093A1
Application number: PCT/JP1995/001976
Authority: WO
Inventors: Reiji Ono; Yoshio Kimura; Takashi Nakaya; Kenichi Miyamoto; Takashi Matoba; Takehiko Ichimoto
Original assignee: Kao Corporation
Priority date: 1994-09-29
Filing date: 1995-09-28
Publication date: 1996-04-04
Also published as: KR970706406A; CN1159834A; EP0783589A1

Abstract

The transportability of dry pulverized coal originating from raw coal having an average HGI of 30 or above can be improved by adhering an organic compound which has a polar group and is substantially water-soluble to the pulverized coal, examples of such an organic compound including anionic surfactants, cationic surfactants, amphoteric surfactants, organic acids and salts thereof, and phenol compounds and salts thereof. The transportability of the pulverized coal is improved to enable the use of the coal as the fuel to be injected into a metallurgical furnace or combustion furnace. Further, the use of the compound prevents the occurance of hanging and channeling in a hopper and the choking of a pipeline.

Description

TRANSPORTABILITY IMPROVER

FOR PULVERIZED COAL

[Field of the Invention]

The present invention relates to a transportability 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.

[Description of Related Art]

In the operation of a metallurgical furnace, e.g., a blast furnace, a process of charging coke and iron ore from the top of the furnace alternately has been generally employed. Recently, however, there has frequently been employed another process of replacing part of the coke to be charged from the top by

pulverized coal which is inexpensive and exhibits a high calorific power and injecting the pulverized coal together with hot blast into the furnace through an injection tuyere. This process of injecting

pulverized coal into the furnace is superior to the process using only coke as the fuel in fuel cost and so forth.

With respect to the fuel for a combustion furnace such as a boiler, coal has been reconsidered as a substitute for fuel oil. Although coal is used in a combustion furnace in the form of CWM (coal-water mixture), COM (coal-oil mixture fuel), pulverized coal or the like, a pulverized coal combustion furnace is particularly noted, because it can dispense with other media such as water or oil. However, 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, classification 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. Specifically, 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. Therefore, 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.

In order to solve these problems, there have been proposed various processes for improving the transportability of pulverized coal. Examples of the processes include a process of mixing pulverized coal with 5 to 20% of char (Japanese Patent Laid-Open No. 268004/1992), a process of regulating the content of inert components (i.e., the total content of

micrinite, 1/3 semifusinite, fusinite and mineral matters as stipulated in JIS M 8816-1979) in coal prior to the pulverization of the coal (Japanese Patent Laid-Open Nos. 9518/1993, 25516/1993 and

222415/1993), a process of enhancing the fluidity index of pulverized coal up to the standard value of a blast furnace or above by limiting the variety of coal (Japanese Patent Laid-Open No. 224610/1992), a process of regulating the coefficient of friction between pulverized coal and the pipeline (Japanese Patent Laid-Open No. 214417/1993), and a process of

controlling the water content of pulverized coal to be of the optimum value (Japanese Patent Laid-Open No. 78675/1993). Further, there has also been proposed a process of improving the efficiency of comminution of pulverized coal by making a dispersant adsorbed on pulverized coal (Japanese Patent Laid-Open No.

224744/1988), but this process is silent on the transportability of pulverized coal.

However, the above processes are problematic in that the variety of coal to be used in pulverized coal injection is limited, that the occurrence of hanging or channeling in the hopper or the choking of the pipeline cannot be completely prevented, that the control unit or equipment used is costly, and so on. Thus no substantially satisfactory process has been provided as yet.

Although 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. However, the above

processes fail in increasing the amount thereof remarkably, because the transportability of pulverized coal is not always satisfactory.

Under these circumstances, 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.

[Summary of the Invention]

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.

Namely, the present invention provides a transportability 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.

The term "an organic compound which is water- soluble" as used herein refers to one satisfying the requirements that no milky turbidity appears when 10 times (by weight) as much water (ion-exchanged water at 10ºC) 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 μm, 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 transportability 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 transportability improving effect, while the addition thereof in an amount exceeding 10% by weight cannot give any additional effect uneconomically.

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. The term "dry" as used herein 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.

Although pulverized coal originating from raw coal having an average HGI of 30 or above is poor in transpotability, 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.

The term "HGI" is the abbreviation of "Hardgrove Griding Index" and serves as an indication of the crushing resistance of coal as stipulated in ASTM D409.

As a result of the above studies, 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. It has been ascertained by determining the quantity of triboelectrification between a coal particle having a size of 38 μm or above and one having a size of 38 μm or below by the blowoff method (which is generally used for

determining the quantity of triboelectrification between different kinds of substances having different particle size distributions, e.g., between toner and carrier) that the force between a finer coal particle and an ordinary coal particle is due to Coulomb attraction. Further, it has been found that the transportability of pulverized coal can be improved when the quantity of triboelectrification thereof is decreased by at least [the average HGI of raw coal] x 0.007 μC/g. Furthermore, it has also been found that when pulverized coal exhibits a quantity of triboelectrification higher than 2.8 μC/g and so is very poor in transportability, the transportability of the pulverized coal can be improved by adding the transportability improver thereto to thereby decrease the quantity of triboelectrification to 2.8 μC/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. 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 mmH₂O/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 mmH₂ O/m 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.

In particular, it is preferable that 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.

It is preferable from the standpoint of the evenness of spraying that the transportability

improver be used as liquid either as such or in a state dissolved in a solvent at a proper

concentration. In this case, it is favorable for the dryness of the solvent that the concentration be 1% by weight or above. Further, 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.

Specific examples of the above compounds usable as the transportability improver according to the present invention will now be described.

(A) Examples of the anionic, cationic and amphoteric surfactants include the following:

1. N-Acylamino acids and salts thereof

• N-acyl-N-methylglycine salts

• N-acyl-N-methyl- β-alanine salts

• N-acylglutami c acid salts

[R: C₆ to C₂₀; M: H, Na , K, NH₄, organic amine salts or the like]

2. Alkyl ether carboxylic acid salts

R0(CH₂CH₂O)_nCH₂COOM [R: C₆ to C₂₀; M: H, Na, K, NH₄, organic amine salts or the like; n: 0 to 40]

3. Lignosulfonic acid salts

salts of lignosulfonic acid with sodium, calcium, potassium, ammonium, triethanol- amine and so forth

4. Acylated peptides

RCO(NHR'CO)_nOM

[R,R': C₆ to C₂₀; M: H, Na, K, NH₄, organic amine salts or the like; n: 1 to 40]

5. Alkylbenzenesulfonic acid salts

[R: C₆ to C₂₀; M: H, Na, K, NH₄, organic amine salts or the like]

6. Alkylnaphthalenesulfonic acid salts

[M: H, Na, K, NH₄, organic amine salts or the like]

7. Salts of dialkyl sulfosuccinates

[R₁, R₂: C₄ to C₁₀; M: H, Na, K, NH₄, organic amine salts or the like]

8. Salts of alkyl sulfoacetates

[R: C₁₀ to C₁₈; M: H, Na. K, NH₄, organic amine salts or the like]

9. α-Olefinsulfonic acid salts

(mixture of alkenemonosulfonic acid salt with hydroxyalkanesulfonic acid salt)

• alkenemonosulfonic acid salts

R-CH=CH-(CH₂)_n-SO₃M

[R: C₈ to C₃₀; M: H, Na, K, NH₄, organic amine or the like]

• hydroxyalkanesulfonic acid salts

[R: C₈ to C₂₄; M: H, Na, K, NH₄, organic amine salts or the like]

10. N-Acylmethyltaurines

[R: C₆ to C₂₀; M: H, Na, K, NH₄, organic amine salts or the like]

11. Sulfated oils

turkey red oil (lowly sulfated castor oil), lowly sulfated olive oil, sulfated beef tallow and sulfated peanut oil

12. Salts of higher alcohol sulfates

RSO₃M

[R: Cg to C₂₀: M: H, Na, K, NH₄, organic amine salts or the like]

13. Salts of secondary higher alcohol sulfates

[R, R': C₆ to C₂₀; M: H, Na , K, NH₄, organic amine salts or the like]

14. Salts of alkyl ether sulfuric acids

R(OCH₂CH₂)_nOSO₃M

[R: Cg to C₂₀; M: H, Na, K, NH₄, organic amine or the like; n: 0 to 40]

15. Secondary higher alcohol ethoxy sulfates

[R, R': C₆ to C₂₀; M: H, Na, K, NH₄, organic amine salts or the like; n: 0 to 40]

16. Salts of polyoxyethylene alkylphenyl ether sulfates

[R: C₆ to C₂₀; M: H, Na , K, NH₄, organic amine salts or the like; n: 0 to 40]

17. Monoglyceride sulfates

0

[R: C₆ to C₂₀; M: H, Na, K, NH₄, organic amine or the like]

18. Salts of aliphatic acid alkylolamide

sulfates

RCONHCH₂CH₂OSO₃M

[R: Cg to C₂₀; M: H, Na, K, NH₄, organic amine salts or the like]

19. Salts of alkyl ether phosphates

• monoesters o

[R: C₆ to C₂₀; M: H, Na, K, NH₄, organic amine salts or the like; n: 0 to 40]

• diesters

20. Salts of alkyl phosphates

• monoesters

[R: C₆ to C₂₀; M: H, Na, K, NH₄, organic amine salts or the like]

• diesters

[R: C₆ to C₂₀; M: H, Na , K, NH₄, organic amine salts or the like]

21. (Co)polymers obtained from the following (1) and (2) and having a molecular weight of 1000 to 1000000:

(1) α, β-unsaturated carboxylic acids and salts thereof and sulfonated vinyl compounds and salts thereof,

(2) acrylonitrile, vinylpyrrolidone and aliphatic olefins having 2 to 20 carbon atoms,

(a) homopolymers and copolymers

comprising one or more members selected from among the monomers (1)

(b) copolymers comprising one or more members selected from among the monomers (1) and one or more members selected from among the monomers (2)

Examples of the vinylic monomers constituting the above (co)polymers include vinylpyrrolidone, acrylonitrile, 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.

23. Aliphatic amine salts

• primary amines

RNH₂X.

[R: C₆ to C₂₀; X: inorganic or organic acid]

• secondary amines

[R: C₆ to C₂₀; R₁: CH₃; X: inorganic or organic acid]

• tertiary amines

[R: C₆ to C₂₀; R₁, R₂: CH₃; X: inorganic or organic acid]

24. Aliphatic quaternary ammonium salts "

[R₁: C₆ to C₂₀; R₂: C₁₂ to C₁₈ or CH₃; X: Cl or

Br]

25. Benzalkonium salts

[R: C6 to C₂₀; X: Cl or Br]

26. Benzethonium chloride

27. Pyridinium salts

[R: C₆ to C₂₀; X: Cl or Br]

Imidazolinium salts

[R: C₁ to C₄ or H; R₁: C₁₂ to C₂₄; R₂: C₁ to C₅ X: Cl or Br]

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.

[wherein R₄ represents a hydrogen atom or a methyl group; R₅ and R₆ each represent a hydrogen atom or an alkyl group having 1 to

3 carbon atoms]

[wherein m₁ is a number of 1 to 3; n₁ is a number of 1 to 3; and R₄, R₅ and R₆ are each as defined above]

[wherein R₇ represents a hydrogen atom or an alkyl or alkyloyl group having 1 to 3 carbon atoms; and R₄ is as defined above] /

[ wherein m₂ and n₂ are each a number of 0 to

3 ; and R₄ , R₅ and R₆ are each as def ined

[wherein A represents -O- or -NH-; and R₄, R₅, R₆ and n₁ are each as defined above] /

[wherein R₄, R₅, R₆ and n₁ are each as defined above ]

[wherein R₄ is as defined above; and the position of substitution on the pyridine is 2 or 4]

[wherein R₄ and R₅ are each as defined above; and the position of substitution on the piperidine is 2 or 4]

[wherein R₄, R₅ and R₆ are each as defined above]

Specific examples of these monomers will now be described.

Specific examples of the formula (I) 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,

N,N-dimethylaminomethylene-capped diethylene glycol methacrylate, N,N-dimethylaminoethylene-capped diethylene glycol methacrylate, N,N-dimethyl- aminopropylene-capped diethylene glycol methacrylate, N,N-diethylaminomethylene-capped ethylene glycol methacrylate, N,N-diethylaminoethylene-capped ethylene glycol methacrylate, N,N-diethylaminopropylene-capped ethylene glycol methacrylate, N ,N-diethylamino- methylene-capped diethylene glycol methacrylate, N.N-diethylaminoethylene-capped diethylene glycol methacrylate, N,N-diethylaminopropylene-capped

diethylene glycol methacrylate, and so forth;

those of the formula (III) include

N-2-hydroxymethyl-2-α-methylvinylimidazole,

N-2-hydroxyethyl-2-α-methylvinylimidazole,

N-2-hydroxypropyl-2-α-methylvinylimidazole, and so forth;

those of the formula (IV) include

N , N-dimethylmethyleneimine methacrylamide,

N,N-dimethylethyleneimine methacrylamide, N,N- dimethyldimethyleneiminemethacrylamide, N ,N-dimethyl- diethyleneiminemethacrylamide, N,N-diethylmethylene- iminemethacrylamide, N,N-diethylethyleneimine- methacrylamide, N.N-diethyldimethyleneiminemethacryl- amide, N,N-diethyldiethyleneiminemethacrylamide, and so forth;

those of the formula ( V) include

N , N-dimethylaminoethyl acrylate, N,N-diethylaminoethyl acrylate, N ,N-dimethylaminoethyl methacrylate,

N,N-diethylaminoethyl methacrylate, N,N- dimethylaminopropylacrylamide, N,N-diethylaminopropyl- acrylamide, N ,N-diethylaminopropylmethacrylamide and so forth; those of the formula (VI) include

N ,N-dimethylaminoethylethylene, N,N- diethylaminomethylethylene, N,N-dimethylaminomethyl- propene, N.N-diethylaminomethylpropene and so forth; those of the formula (VII) include vinylpyridine and so forth;

those of the formula (VIII) include

vinylpiperidine, vinyl-N-methylpiperidine and so forth; and

those of the formula (IX) include

vinylbenzylamine, vinyl-N,N-dimethylbenzylamine and so forth.

30. Copolymers comprising one or more vinylic monomers selected from the group consisting of α,β-unsaturated carboxylic acids and salts and derivatives thereof, sulfonated vinyl compounds and salts thereof, acrylonitrile, 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.

Examples of the vinylic monomer include vinylpyrrolidone, 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.

31. Product of ring-opening polymerization of ethyleneimine, salts thereof, quaternary ammonium salts thereof, and derivatives thereof

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.

[wherein n₃ is an integer of 1 to 5; and n₄ is an integer of 0 to 5]

32. Polycondensates of aliphatic dicarboxylic acids with polyethylenepolyamine and

dipolyoxyethylenealkylamine; and salts and quaternary ammonium salts thereof

Specific examples thereof include polycondensates of polyethylenepolyamine with aliphatic dicarboxylic acids which are composed of repeating units represented by the general formula (XI) and those of dipolyoxyethylenealkylamine with aliphatic

dicarboxylic acids which are composed of repeating units represented by the general formula (XII), the molecular weight thereof ranging from 1,000 to

1,000,000:

-[-CO-R₈-CONH-KH₂CH₂NH-]-_n5 CH₂CH₂NH-]- (XI)

[wherein R₈ represents an alkylene or alkenylene group having 1 to 10 carbon atoms; and n₅ is an integer of 2 to 7]

[wherein R₈ is as defined above; R₉ represents an alkyl group having 1 to 8 carbon atoms; R₁₀ represents a hydrogen atom or a methyl group; and n₆ and n₇ are each an integer of 1 to 10]

33. Polycondensates of dihaloalkanes with

polyalkylenepolyamines; 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 polyalkylenepolyamines having at least two tertiary amino groups in the molecule, the average molecular weight thereof ranging from 1,000 to 1,000,000. Examples of the polyalkylenepolyamine to be used in this case include tetramethylethylenediamine, tetramethylpropylene- diamine, pentamethyldiethylenetriamine, hexamethylene- tetramine, triethylenediamine, and so forth.

34. Polycondensates of epihalohydrins with

amines, and salts and quaternary ammonium salts thereof

Specific examples thereof include those composed of repeating units represented by the following general formula (XIII) and having an average molecular weight of 1,000 to 1,000,000:

[wherein R₁₁ to R₁₃ represents a methyl group or an ethyl group; and X represents a halogen atom]

35. Salts of chitosan, and starch, cellulose and cationic modification products thereof

36 . Carboxybetaines

[R₁: C₆ tb C₂₀; R₂, R₃: CH₃ or the like; n: 1 to 2; m: H, Na, K, NH₄, organic amine or the like]

37. Aminocarboxylic acid salts

RNH(CH₂)_nCOOM

[R: C₆ to C₂₀; n: 1 to 2; M: H, Na , K, NH₄, organic amine salts or the like]

38. Imidazolinium betaines

[R: C₆ to C₂₀]

39. Lecithins

Among the surfactants described above, those described in the items 3, 21, 22 and 29 to 35 are excellent in the effect.

(B) 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).

According to the present invention, 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 transportability 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.

Simultaneously, 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. In addition, 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.

[Example]

The present invention will now be described by referring to the following Examples, though the present invention is not limited to them.

Examples 1 to 88 and Comparative Examples 1 to 7

[1] Pulverization of raw coal and preparation of

pulverized coal samples

The pulverization of raw coal and the addition of a transportability improver were conducted by the following procedure:

(1) 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. In this step, 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.

(2) The resulting pulverized coal is dried at 105°C for one hour to adjust the water content thereof to 0.5 to 1.0%.

(3) The resulting pulverized coal is filtered through a screen having a mesh size of 106 μm to recover pulverized coal having a particle size of 106 μm or below. In all of the examples, 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 μm.

(4) The volume-average diameter is defined by the following formula:

d_i: particle diameter

n_i: number of particles having a particle diameter of d_i

[2] Evaluation of pulverized coal

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 μm, 5 dust hole, and 6 electrometer. Such 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). In the present invention, a mesh having an opening of 38 μm 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/cm² onto the coal sample to thereby blow off coal

particles having a diameter of 38 μm or below into the dust hole. The quantity of triboelectrification of the coal particles having a diameter of 38 μm 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.

1. 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.

2. Compressibility: determined by measuring the bulk density ρ_s(g/cm³) of a powdery material in a loosely packed state by the use of a cylindrical container (capacity: 100 cm³), tapping the resulting container given times (180 times), measuring the bulk density ρ_c(g/cm³) of the material in a closely packed state, and calculating the compressibility Φ(%) according to the following equation: Φ = (ρ_c - ρ_s) x 100/ρ_c (%)

3. 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.

4. 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:

(amt. of powder on the top sieve/2 g) x 100

(amt. of powder on the intermediate sieve/2 g) x 100 x 3/5

(amt. of powder on the bottom sieve/2 g)

x 100 x 1/5

The pulverized coal used in the present invention exhibits little difference among the weights of powder remaining on the above three sieves, so that the extent of agglomeration thereof is difficult of calculation. In the present invention, therefore, 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. In Fig. 2, 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 (P₁ and P₂). This experiment was conducted under the following conditions:

feed rate of pulverized coal: 0.8 kg/min

carrier gas: nitrogen (N₂) feed rate of carrier gas: 4 Nm³/h (67

litter/min)

transportation time: 6 min.

Each pulverized coal sample was evaluated for the following item:

1. Pressure loss

The sampling of data was conducted at pressure gauges P₁ and P₂ at 500 Hz. The pressure loss was determined by calculating the whole mean of (P₁ - P₂) over the transport time (6 min).

The results are given in Tables 1 to 9.

The above evaluation was repeated except that the following compounds were each used. The results are given in Tables 10 to 13.

(A) phosphoric acid salt of diethylaminomethyl

methacrylate polymer (MW: 10,000)

(B-1) Copolymer comprising diethylaminoethyl

methacrylate borate, vinylpyrrolidone and sodium acrylate at a ratio of 5 : 4 : 1 (by mole, hereinafter the same applies)

(MW: 200,000)

(B-2) ditto (MW: 50,000)

(B-3) ditto (MW: 5,000)

(B-4) ditto (MW: 1,500)

(C) copolymer comprising phosphoric acid salt of

diethylaminoethyl methacrylate and sodium

methacrylate at a ratio of 4 : 5 (MW: 20,000)

(D) product of ring-opening polymerization of

ethyleneimine phosphate (MW: 100,000)

(E) copolymer comprising ethylphosphinous acid salt of dimethylaminoethyl methacrylate and sodium acrylate at a ratio of 3 : 1 (MW: 300,000)

(F) copolymer comprising ethylphosphonic acid salt of dimethylaminoethyl methacrylate and sodium 2- acrylamino-2-methylpropanesulfonate at a ratio of 4 : 1 (MW: 100,000) (G) copolymer comprising phosphoric acid salt of vinylpyridine, vinylpyrrolidone and sodium acrylate at a ratio of 6 : 3 : 1 (MW: 450,000) (H) polycondensate of diethylenetriamine

thiophosphate with dimer acid (MW: 800,000) (I) copolymer comprising phosphoric acid salt of

diethylaminoethylmethacrylamide, sodium acrylate and sodium vinylsulfonate at a ratio of 3 : 1 : 1

(MW: 400,000)

(J) copolymer comprising quaternary ammonium salt of vinylpyridine with dimethylphosphinic acid, vinylpyrrolidone and sodium acrylate at a ratio of 6 : 3 : 1 (MW: 450,000)

(K) the same as the copolymer (I) except that the

phosphoric acid salt of diethylaminoethyl- methacrylamide is replaced by boric acid salt thereof.

(L) quaternary ammonium salt of cationized cellulose

(MW: 1,000,000)

(M) polycondensate of 1,2-dichloroethane with

hexamethylenetetramine phosphate (MW: 50,000) (N) polycondensate of diethylenetriamine

ethylphosphinate with dimer acid (MW: 800,000) (O) phosphorous acid salt of quaternary ammonium type product of ring-opening polycondensation of epichlorohydrin with trimethylamine (MW: 100,000) (P) polycondensate of quaternary ammonium salt of

tetramethylpropylenediamine with

diethylphosphonic acid (MW: 100,000)

(Q) the same as the copolymer (G) except that the

phosphoric acid salt of vinylpyridine is replaced by sulfuric acid salt thereof

(R) the same as the polycondensate (H) except that the diethylenetriamine thiophosphate is replaced by diethylenetriamine nitrate

(S) the same as the copolymer (F) except that the

ethylphosphonic acid salt of dimethylaminoethyl methacrylate is replaced by hydrochloric acid salt thereof

(T) the same as the copolymer (E) except that the

ethylphosphinous acid salt of dimethylaminoethyl methacrylate is replaced by glycolic acid salt thereof

(U) the same as the product (D) except that the

ethyleneimine phosphate is replaced by

ethyleneimine acetate

(V) copolymer comprising quaternary ammonium salt of vinylpyridine with dimethyl sulfate,

vinylpyrrolidone and sodium acrylate at a ratio of 6 : 3 : 1 (MW: 450,000) (Y) sodium salt of N-1 dimethylsulfoethylacrylamide homopolymer (MW: 70,000)

(Z) copolymer comprising sodium salt of N-1

dimethylsulfoethylacrylamide and phosphoric acid salt of dimethylaminoethyl methacrylate at a ratio of 1 : 1 (MW: 20,000)

(AA) 1 : 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

(DD) quaternary ammonium salt of cationized starch

Example 89

An application example will now be described, wherein the transportability improver of the present invention is applied to equipment for injecting pulverzied coal into a blast furnace.

Conditions:

pulverized coal injection rate: 40 t/hr transportability improver:

β-naphthalenesulfonic acid-formalin condensate

amt.: 0 or 0.3% by weight

pulverized coal:

volume-average diameter ...74 μm water content ...1.5%

average HGI of raw coal...45, 55, 70

[Brief Description of the Drawings]

[Figure 1]

Schematic view of the instrument used for measuring the quantity of triboelectrification [Figure 2]

Schematic view of the equipment used for measuring pipelining characteristics

[Figure 3]

Schematic view of the actual equipment used in Example 89 for injecting pulverized coal into a blast furnace

[Figure 4]

Chart showing the transfer times determined in

Example 89

[Figure 5]

Chart showing the pipeline pressure losses determined in Example 89

[Figure 6]

Chart showing the pipeline pressure losses determined in Example 89

[Figure 7]

Schematic view of the pulverized coal fired boiler used in Example 90

[Figure 8]

Chart showing the pipeline pressure losses determined in Example 90

[Figure 9]

Chart showing the relationships between the average HGI of raw coal and the quantity of triboelectrification when various

transportability improvers were used

[Description of numerals]

1: compressed gas

2: nozzle

3: Faraday gauge 4: mesh

5: dust hole

6: electrometer

7: pulverized coal

8: table feeder

9: flowmeter

10: horizoptal pipe

11: cyclone

12: blast furnace

25: combustion chamber of boiler 26: burner

Fig. 3 shows a schematic view of the equipment for injecting pulverized coal into a blast furnace used in this Example. In Fig. 3, 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. In the course of the transport of the coal to the pulverizer, 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.

First, 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 transportation of pulverized coal was

conducted under the above conditions to determine the influence of the transportability improver on the transfer time taken to transfer the pulverized coal from the tank 17 to the tank 15 and the influence thereof on the pressure loss occurring in the injection pipeline 14 (i.e., the pressure difference between the tank 15 and the blast furnace 12). The results are given in Figs. 4, 5 and 6.

In Fig. 4 and 5; the line (a) shows the result obtained without adding any transportability improver and the line (b) shows that obtained with the above transportability improver. In Fig. 6, the line A shows the acceptable upper limit of the equipment.

When raw coal having an average HGI of 45 was use, as shown in Figs. 4 and 5, both the pressure loss in the pipeline and the transfer time from tank were reduced. Accordingly, the pulverized coal injection rate can be enhanced. Further, the use of the

transportability improver of the present invention enables the employment of simpler equipment for attaining the same injection performance. Figs. 4 and 5 show relative evaluation wherein the value obtained without adding any transportability improver is taken as 1.

The above injection of pulverized coal into a blast furnace was repeated by the use of raw coal having an average HGI of 45, 55 or 70 to determine the dependence of pressure loss in the pipeline on the average HGI of raw coal and the results are given in Fig. 6. The pressure loss can be lowered to the acceptable upper limit of the equipment or below by the use of the transportability improver, even when pulverized coal originating from raw coal having a high HGI is used, which enables the use of a wide variety of coal including inexpensive ones. Fig. 6 shows relative evaluation wherein the value obtained when raw coal having an average HGI of 45 is used without adding any transportability improver is taken as 1.

Example 90

Another application example will now be

described, wherein the transportability improver of the present invention is applied to the pulverized coal to be injected into a pulverized coal fired boiler.

additive:

β-naphthalenesulfonic acid-formalin condensate

amt.: 0 or 0.3% by weight

pulverized coal: volume-average diameter ...74 μm water content ...1.5%

average HGI of raw coal

...45, 55, 65, 75

Fig. 7 shows a schematic view of the pulverized coal fired boiler used in this Example. In Fig. 7, 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. In the course of the transport of the coal to the pulverizer, 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.

The transportation of 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.

Although coals having various average HGI values (i.e., 45, 55, 65 and 75) were used in the above test as the raw coal, the pressure loss in the pipeline could be lowered to the acceptable upper limit of the equipment or below by the addition of the

transportability improver even when raw coal having a high HGI was used, whereby it has become possible to use a wide variety of coals.

Examples 91 to 102 and Comparative Examples 8 to 15

The transportability improvers listed in Tables 14 to 16 were evaluated in a similar manner to that of Examples 1 to 88 and Comparative Examples 1 to 7.

The data of fluidity index, pressure loss and quantity of triboelectrification were given together with their differences (increase or decrease) from the data of Comparative Examples 8 to 11 wherein no transportability improver was used. In other words, Tables 14 to 16 also show how much the fluidity index was increased by the addition of each transportability improver and how much the pressure loss and the quantity of triboelectrification were decreased by the addition thereof as compared with those of Comparative Examples 8 to 11 (for example, the data of Comparative Example 5 and Examples 91, 95 and 99 were compared with those of Comparative Example 8).

Claims

1. A transportability 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.

2. The transportability improver for pulverized coal as set forth in claim 1, which can

decrease the quantity of triboelectrification of the dry pulverized coal by at least [the average HGI of raw coal] x 0.007 μC/g when added thereto in an amount of 0.3% by weight (in terms of dry coal).

3. The transportability improver for pulverized coal as set forth in claim 2, which can decrease the quantity of triboelectrification of the dry pulverized coal to 2.8 μC/g or below when added thereto in an amount of 0.3% by weight (in terms of dry coal).

4. The transportability improver for pulverized coal as set forth in claim 1, wherein the organic compound is one or more members selected from the group consisting of anionic, cationic and amphoteric surfactants.

5. The transportability improver for pulverized coal as set forth in claim 1, wherein the organic compound is one or more members selected from the group consisting of lower aliphatic acids and salts thereof.

6. A process for improving the transportability of pulverized coal, characterized by adhering an organic compound which has a polar group and is substantially water-soluble to the surface of dry pulverized coal originating from raw coal having an average HGI of 30 or above.

7. The process for improving the transportability of pulverized coal as set forth in claim

6, characterized in that the organic compound is added to the pulverized coal in an amount of 0.01 to 10% by weight to decrease the quantity of

triboelectrification of the pulverized coal by at least [the average HGI of raw coal] x 0.007 μC/g.

8. The process for improving the transportability of pulverized coal as set forth in claim

7, characterized in that the organic compound is added to the pulverized coal in an amount of 0.01 to 10% by weight to decrease the quantity of triboelectrification of the pulverized coal to 2.8 μC/g or below.

9. The process for improving the transportability of pulverized coal as set forth in claim 6, wherein the organic compound is one or more members selected from the group consisting of anionic, cationic and amphoteric surfactants.

10. The process for improving the transportability of pulverized coal as set forth in claim 6, wherein the organic compound is one or more members selected from the group consisting of lower aliphatic acids and salts thereof.

11. Dry pulverized coal originating from raw coal having an average HGI of 30 or above and

containing, adhering thereto, an organic compound which has a polar group and is substantially water- soluble.

12. The dry pulverized coal as set forth in claim 11, characterized in that the organic compound adheres in an amount of 0.01 to 10% by weight to decrease the quantity of triboelectrification by at least [the average HGI of raw coal] x 0.007 μC/g.

13. The dry pulverized coal as set forth in claim 12, characterized in that the organic compound adheres in an amount of 0.01 to 10% by weight to decrease the quantity of triboelectrification to 2.8 μC/g or below.

14. The dry pulverized coal as set forth claim 11, wherein the organic compound is one or more members selected from the group consisting of anionic, cationic and amphoteric surfactants.

15. The dry pulverized coal as set forth claim 11, wherein the organic compound is one or more members selected from the group consisting of lower aliphatic acids and salts thereof.

16. A process for the operation of a

metallurgical furnace or combustion furnace,

characterized by injecting dry pulverized coal

originating from raw coal having an average HGI of 30 or above and containing, adherent thereto, an organic compound which has a polar group and is substantially water-soluble into the furnace through an injection inlet.

17. The process for the operation of a

metallurgical furnace or combustion furnace as set forth in claim 16, characterized by injecting the pulverized coal containing, adherent thereto, 0.01 to 10% by weight of the above organic compound into the furnace through an injection inlet.

18. The process for the operation of a

metallurgical furnace or combustion furnace as set forth in claim 16 or 17, characterized by injecting the pulverized coal containing, adherent thereto, 0.01 to 10% by weight of the above organic compound and being decreased in the quantity of

triboelectrification by at least [the average HGI of raw coal] x 0.007 μC/g into the furnace through an injection inlet.

19. The process for the operation of a

metallurgical furnace or combustion furnace as set forth in claim 18, characterized by injecting the pulverized coal containing, adherent thereto, 0.01 to 10% by weight of the above organic compound and having a quantity of triboelectrification of 2.8 μC/g or below into the furnace through an injection inlet.

20. The process for the operation of a

metallurgical furnace or combustion furnace as set forth in claim 16, wherein the organic compound is one or more members selected from the group consisting of anionic, cationic and amphoteric surfactants.

21. The process for the operation of a

metallurgical furnace or combustion furnace as set forth in claim 16, wherein the organic compound is one or more members selected from the group consisting of lower aliphatic acids and salts thereof.