JP2747521B2 - Additive for coal-water slurry - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a coal-water slurry additive, and more particularly, to a coal-water slurry for dispersing coal powder in water at a high concentration and with good fluidity and stability. The present invention relates to additives for slurries, and particularly to additives for coal-water slurries that reduce wear of transport pipes and burner chips.

[Conventional technology]

In recent years, there has been a concern about depletion of petroleum resources, and coal has attracted attention again as a substitute. However, since coal is a solid, handling is complicated, there are problems such as environmental pollution due to scattering of coal dust at the time of unloading at a port and spontaneous ignition at the time of coal storage.

As a result, coal-water slurry (hereinafter referred to as “CWM”) made by dispersing pulverized coal in water at a high concentration and making it fluid can be handled in the same way as petroleum, can be transported by pipeline, and is stable during storage. Some of them have been put to practical use as a technology that has good performance and can directly burn.

CWM is required to have a high concentration of dispersed pulverized coal and to be excellent in fluidity and stability, and various additives have been developed to impart such properties. At the same time, problems that had not been conceived at the test stage in a small pilot plant became apparent.

For example, as an additive for CWM, naphthalene sulfonate and its formalin condensate (JP-A-56-21636),
Polydicyclopentadiene sulfonate (JP-A-60-96)
No. 689) and polystyrene sulfonate (JP-A-57-1)
CWM using anionic additives such as 45187
Is a problem at the practical stage due to severe wear of pipelines and burner tips.

CWM using an alkylene oxide adduct of polyalkyleneimine (JP-A-58-49795) and a polyether polyol type nonionic additive (JP-A-57-56034) have relatively little wear. However, there is a drawback that if the temperature is maintained at a high temperature, the viscosity increases and the pipeline cannot be transported. Furthermore, the stability of CWM using said additives is insufficient. For example, if left undisturbed for one month, the pulverized coal sediments to form agglomerates that have lost their self-fluidity, and cannot be discharged from the storage tank.

The half-ester saponified styrene-maleic acid copolymer (Japanese Patent Application Laid-Open No. 61-225284) has only a carboxylate as a hydrophilic group, and therefore CWM using the additive has poor dispersibility and high concentration. Can not.

CWM using a sulfonated styrene-maleic anhydride copolymer salt (JP-A-58-42694 and JP-A-61-221296) has poor stability.

[Problems to be solved by the invention]

An object of the present invention is to provide an additive which is excellent in high concentration property, fluidity and dispersion stability, and enables the production of CWM with less abrasion of a transport pipe.

[Means for solving the problem]

The present invention relates to a coal-water slurry additive containing a partially esterified styrene-maleic acid copolymer obtained by reacting the following components (A), (B) and (C).

The component (A) is a styrene-maleic anhydride copolymer represented by the following general formula (1).

(In the formula, 1 represents an integer of 1 to 5, m represents an integer of 1 to 3, and n represents an integer of 4 to 10.) The copolymer may be a random copolymer or a block copolymer. The number average molecular weight of the copolymer is between 1000 and 9000, preferably between 1500 and 3000. In the general formula (1), 1 represents the number of styrene units, and 1 to 5
M is the number of maleic anhydride units, and 1
And is preferably an integer of 1 to 3, preferably 1 / m = 3/1 to 1/1. n is an integer of 4 to 10, preferably 6 to 8.

The component (B) is a polyether derivative having a polyalkylene glycol chain represented by the following general formula (2).

X (R) p (C ₂ H ₄ O) qH (2) (wherein, X is a residue of a compound having one active hydrogen having 1 to 4 carbon atoms, and R is an alkylene having 3 to 8 carbon atoms) (The oxide group, p represents an integer of 0 to 10 and q represents an integer of 10 to 200.) The polyether derivative imparts hydrophilicity to a partially esterified styrene-maleic acid copolymer.

Examples of the compound having one active hydrogen having 1 to 4 carbon atoms include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, allyl alcohol, and t-butyl alcohol; carboxylic acids such as formic acid, acetic acid, and propionic acid; Examples thereof include secondary amines such as amine and diethylamine, and mercaptans such as methanethiol and ethanethiol. The above general formula (2)
In the formula, p represents the average addition mole number of the alkylene oxide, and q represents the average addition mole number of the ethylene oxide.
p is an integer of 0 to 10, preferably 0 to 5, and q is 10 to
It is an integer of 200, preferably 20-150. If q is less than 10, no water-soluble partially esterified styrene-maleic acid copolymer can be obtained, and if it exceeds 200, the dispersion stability of CWM deteriorates.

The component (C) is an alcohol having 6 or more carbon atoms. The alcohols impart lipophilicity to the partially esterified styrene-maleic acid copolymer. Examples of the alcohols include alcohols having 6 or more, preferably 8 or more carbon atoms, for example, n-hexanol, lauryl alcohol, stearyl alcohol, 2-ethylhexanol, cyclohexanol, benzyl alcohol, C ₁₂ -C ₁₄ second alcohol. Grade alcohol, coconut oil fatty acid reduced alcohol, and the like. Compounds obtained by adding several moles of an alkylene oxide to these can also be used.

The reaction molar ratio of component (A), component (B) and component (C) is (A) :( B) :( C) = 1: (1-10) :( 1-5)
It is. The molar ratio of the component (B) is preferably small when the polyethylene glycol chain of the component (B) is large, and is large when the polyethylene glycol chain is small. That is, the content of the component (B) in the partially esterified styrene-maleic acid copolymer is preferably 50 to 98% by weight. If the content of the component (B) is less than 50% by weight, the partially esterified styrene-maleic acid copolymer is hardly soluble in water, while if it is more than 98% by weight.
Poor dispersion performance of CWM.

The esterification reaction of the component (A), the component (B) and the component (C) is carried out by a usual method, for example, a method in which the reaction is carried out in a solvent such as methyl ethyl ketone, methyl isobutyl ketone or dioxane under reflux, or under a nitrogen stream without using a solvent. From 120 to 180
A method in which the reaction is carried out at a temperature of ° C can be employed. When a half esterification reaction is employed, the reaction can be carried out without a catalyst, but a catalyst such as p-toluenesulfonic acid is usually preferably used to accelerate the reaction.

The partially esterified styrene-maleic acid copolymer thus obtained may be a salt of sodium, potassium, ammonium or the like, since some carboxyl groups remain.

The number average molecular weight of the partially esterified styrene-maleic acid copolymer produced in this manner is from 5000 to 1000.
00, preferably 8000 to 50000. Number average molecular weight is 500
If it is less than 0, the dispersion stability of the pulverized coal is poor, and it tends to settle, while if it is more than 100,000, it is agglomerated and loses its self-flowability.

The additive for CWM of the present invention may be used together with other dispersants. Other dispersants that can be used in combination include anionic dispersants such as naphthalene sulfonate formalin condensate, polydicyclopentadiene sulfonate, and polystyrene sulfonate; and nonionics such as polyoxyethylene alkylphenyl ether and its formalin condensate. Various dispersants, such as a dispersant, are mentioned.

Although the amount of the additive for CWM of the present invention varies depending on the particle size of the coal, it is generally 0.1 to 2.0% by weight, preferably 0.1% by weight, based on a coal particle size of 200 mesh 80% by weight pass.
3 to 1.0% by weight.

The additive for CWM of the present invention may be dissolved in water in advance and pulverized coal added thereto, or may be added later to a mixture of pulverized coal and water. Also, as in the case of wet pulverization, coal may be pulverized and added together with water.

As the coal powder to be slurried using the additive of the present invention, one having a particle size of 1 mm or less is suitable, but not limited thereto. Examples of the type of coal include various types of coal such as bituminous coal, subbituminous coal, and lignite, and those of the locality of production.
The additive of the present invention can also be applied to coal decalcified by an oil agglomeration method or a flotation method.

[Action]

The reason why the additive for CWM of the present invention exhibits excellent effects is considered as follows. First, some additive dissolved in water adsorbs on the coal surface. Since the adsorbed additive is a polymer with several relatively long polyoxyethylene chains,
It is considered that the volume restriction effect and the osmotic pressure effect of the polymer act to cause a repulsion effect due to steric stabilization, or the pulverized coal is dispersed and stabilized by the compression repulsion effect of the polymer dissolved in water between the particles.

The additive also has some carboxyl groups and therefore exhibits some anionic properties, and is also stabilized by repulsive interaction between the electric double layer at the pulverized coal particle-water interface.

Further, it is considered that the pulverized coal forms a weak aggregate network structure by the adsorbed polymer and can maintain stability for a long period of time.

Further, regarding the lubricity, it is considered that when the polymer molecules existing in the water are compressed as the particles come close to each other, a repulsive force is generated, and the sliding between the particles is smoothed, thereby reducing the wear of the hype and the burner tip.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Examples 1 to 10 and Comparative Examples 1 to 3 Various additives for CWM were produced according to the formulation shown in Table 1.

A predetermined amount (Table 2) of an additive and water were put into a 500 ml container and dissolved therein, and then, Warkworth coal (Australian bituminous coal) pulverized and prepared to 80% by weight in a 200 mesh pass was gradually charged with stirring. After mixing for 10 minutes after charging, the mixture was mixed at 4000 rpm for 10 minutes with a homomixer (“Auto Homomixer” manufactured by Tokushu Kika Co., Ltd.) to prepare a coal-water slurry.

Table 2 shows the results of measuring the coal concentration, the representative viscosity, and the amount of sedimentation and coagulation of the obtained coal-water slurry, and Table 3 shows the abrasion loss of the disk.

 Each measurement was based on the following method.

(1) Coal concentration (% by weight): Determined from the amount of water loss on drying.

(2) Representative viscosity (mPa · s): The rheogram was measured with a “Rheometer” manufactured by Haake, and the viscosity at a shear rate of 100 sec ⁻¹ was determined.

(3) Settling and coagulation amount (% by weight): 300 g of coal-water slurry
The pot was placed in a 250 ml pot and left as it was. After 2 weeks, the pot was turned upside down and the amount remaining at the pot bottom without self-flow was measured.

(4) Disc wear loss (mg): Coal-water slurry 50
0 g was placed in a container, and a copper plate disk of 50 mmφ × 2 mm was immersed and rotated at 2000 rpm × 20 hours to determine the weight loss due to wear of the disk.

Comparative Examples 4 to 7 Coal-water slurries were prepared in the same manner as in Examples 1 to 10 and Comparative Examples 1 to 3 using the additives shown in Table 1, and the coal concentration, the representative viscosity, the amount of sedimentation and agglomeration were measured. Was measured for loss on wear. The results are shown in Tables 2 and 3.

As is clear from the table, the coal-water slurry using the additive of the present invention has a high coal concentration, low viscosity, excellent fluidity, excellent slurryability, low sedimentation and aggregation, and low stability. It can be seen that the disc is excellent in lubrication and that the wear loss of the disc is small.

〔The invention's effect〕

The additive for CWM of the present invention mainly contributes to the water reducing effect. By using the additive, the concentration of pulverized coal in CWM can be increased by 10 to 20% by weight as compared with the conventional case. In addition, it improves the fluidity of CWM, suppresses sedimentation and agglomeration of pulverized coal, maintains stability for a long time, and further enhances the lubricity of CWM to reduce wear on transport pipes and burner chips. it can.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08F 222/08 C08F 222/08

Claims (3)

(57) [Claims] An additive for a coal-water slurry containing a partially esterified styrene-maleic acid copolymer obtained by reacting the following components (A), (B) and (C): (A) Styrene-maleic anhydride copolymer represented by general formula (1) (In the formula, 1 represents an integer of 1 to 5, m represents an integer of 1 to 3, and n represents an integer of 4 to 10.) (B) Polyether derivative having a polyalkylene glycol chain represented by the general formula (2) X (R ) P (C ₂ H ₄ O) qH (2) (wherein, X is a residue of a compound having one active hydrogen having 1 to 4 carbon atoms, R is an alkylene oxide group having 3 to 8 carbon atoms, p represents an integer of 0 to 10 and q represents an integer of 10 to 200), (C) alcohols having 6 or more carbon atoms. 2. The reaction molar ratio of each of the components (A), (B) and (C) is (A) :( B) :( C) = 1: (1-10):
The additive for a coal-water slurry according to claim 1, which is (1 to 5). 3. The coal-water slurry additive according to claim 1, wherein the partially esterified styrene-maleic acid copolymer has a number average molecular weight of 5000 to 100,000.