JPS58117284A - Viscosity depressant for highly concentrated coal/water slurry - Google Patents

Abstract

PURPOSE:To provide a vicosity depressant which can greatly lower the viscosity of a coal/water slurry by the addition of a small amount thereof and makes it possible to pump a highly conc. coal slurry, consisting of a polyether compd. having a specified MW obtd. by adding an alkylene oxide to an active hydrogen- contg. alcohol. CONSTITUTION:An alkylene oxide such as ethylene oxide is added to an alcohol contg. at least one active hydrogen per molecule or its derivative, such as xylitol or a partially saponified polyvinyl acetate. If necessary, the adduct is reacted with an acid to obtain a viscosity depressant consisting of a polyether compd. (derivative) having an MW of 1,000-100,000. 0.01-5.0pts.wt. said viscosity depressant is added to 100pts.wt. coal/water slurry to obtain a slurry having a lowered viscosity. EFFECT:Pumping of a slurry contg. coal at a concn. of 61wt% or above, particulary 70wt% or above becomes possible.

Description

[Detailed description of the invention] The present invention relates to a thinner for coal-water slurries.

More particularly, it relates to a thinning agent for dispersing pulverized coal in water to provide a highly concentrated coal-water slurry that can be pumped.

In recent years, due to the depletion of oil resources, the use of coal has been reconsidered.
Various ways of using it are being considered. However, unlike oil, coal is a solid and cannot be transported by pump. Therefore, various methods are being considered for pulverizing coal and dispersing it in water to create a water slurry. However, with current technology, this method becomes difficult to pump as increasing the coal concentration significantly thickens the coal and loses its fluidity.

On the other hand, lowering the coal concentration reduces transportation efficiency and requires a dehydration process before combustion, which is expensive and impractical.

The present inventors have previously succeeded in stably dispersing coal in oil using polyethers, and are currently applying for a patent. Japanese Patent Publication No. 54-52105. 54-52106, 54-5
3105. 54-53106, 54-53107.
54-53108゜54-53109. 54-6
5708. 54-65709. 54-111506
．． See 55-152789. However, these are for stably dispersing coal in oil and are not for use in coal-water slurries.

JP-A-56-62538 describes an agent for stably dispersing fine powder in water at a low concentration, but its purpose is different from that of a thinner for highly concentrated coal-water slurries.

The present inventors fluidized a highly concentrated coal-water slurry,
We have conducted intensive research into a thinning agent for coal-water slurry that enables pumping, and with the addition of a small amount, the viscosity of coal-water slurry can be significantly reduced.As a result, coal can be transported by pump even at high coal concentrations. Successfully developed a viscosity reducing agent that provides water slurry.

By using the thinner of the present invention, coal can be fluidized with a small amount of water, making it possible to not only transport it by pump, but also to burn it in a boiler as it is, and also eliminate the dehydration step before combustion. be able to. By using the thinning agent of the present invention, handling of coal becomes extremely simple, and its applications are greatly expanded.

The coals used in the coal-water slurry include anthracite, bituminous coal,
Any type of coal may be used, such as sub-bituminous coal, lignite, or cleaned versions thereof. In addition, the particle size of the coal in the water slurry may be any particle size as long as it is powder, but since the pulverized coal currently burned in thermal power plants is 200 mesh 0% pass or higher, this particle size is fine. This is a guideline for the particle size of charcoal. However, the thinner of the present invention is not affected by particle size and exhibits excellent effects on coal powder of any particle size.

Cleaned coal is coal from which inorganic substances such as ash and sulfur have been removed.

Examples of methods for cleaning coal include heavy liquid separation method and oil aggregation method (hereinafter referred to as OA).
There are methods such as flotation method) and flotation method. However, methods other than these may also be used and are not particularly limited.

To describe the OA method, there is a dry method for coal. Alternatively, after wet pulverization, prepare a water slurry and add an appropriate amount of oil, or coat the coal with oil in advance, adjust the water slurry, and stir to mix the organic and inorganic components of the coal into oil. By utilizing the difference in wettability to water, oil that selectively wets the organic components of coal is used as a binder to cause aggregation of the organic components of coal. On the other hand, since inorganic substances have a weak affinity with oil, they are liberated in water, so this method can simultaneously remove inorganic substances by separating water from coagulated coal. O
The coal concentration in the coal-water slurry of method A is usually 10 to 65
The amount is %.

The oil used in the OA method is crude oil or various fractions obtained from crude oil, such as kerosene, light oil, A heavy oil, B heavy oil, C heavy oil, etc., tar or shale oil, ethylene cracked residual oil, or various blended oils, which are generally used as fuel. Mineral oils such as oils used for cleaning, lubricating oils, and cleaning oils. Also benzene,
Although water-insoluble oils such as toluene, xylene, and animal and vegetable oils can also be used, heavy oils such as C heavy oil and tar residue oil are particularly preferred because they are inexpensive. It is generally sufficient to use this oil in an amount of 30% by weight or less based on the coal in the coal-water slurry to be treated for mineral removal.

The flotation coal washing method is an existing coal washing method in which a very small amount of oil is added to the pulverized coal-water slurry and stirred to create foam.
Generate 70 spaces. Similar to the OA method, in this method, the organic components of the coal adhere to the 70% oil film, but the inorganic components are liberated in the water.
This is a method that can separate coal organic components.

The oils used in the flotation method are turpine oil, tar, A heavy oil, C heavy oil, light oil, and kerosene.

Generally, several tens of weight percent or more of inorganic substances are removed from coal by the above method.

If the coal cleaned in this manner is used, the effect of the thinner of the present invention will be significantly superior to that of uncleaned coal, and a coal-water slurry with several points higher concentration can be obtained. Furthermore, when cleaned coal is used, in addition to this effect, boiler corrosion during combustion is suppressed, and the burden on ash removal equipment and desulfurization equipment is reduced.

The thinner for coal-water slurry of the present invention has one or more active hydrogen atoms, preferably three or more active hydrogen atoms, and more preferably five active hydrogen atoms in the molecule.
A polyether compound having a molecular weight of 1,000 to 100,000, obtained by adding an alkylene oxide to an alcohol and its derivatives having 1 or more as a starting material,
Alternatively, it is characterized by containing a derivative obtained by subjecting the terminal hydroxyl group of the polyether compound to various reactions.

Examples of starting materials include the following.

Alcohols having one active hydrogen such as ethyl alcohol, butyl alcohol, octyl alcohol, cyclohexyl alcohol, benzyl alcohol, etc. Alcohols having two active hydrogens such as ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, butylene glycol,
Polybutylene> alcohols having 3 active hydrogens such as liquor, butanediol, bentanediol, hexanediol, etc., such as glycerin, butanetriol,
Alcohols with 4 active hydrogen atoms such as hexanetriol, trimethylolpropane, triethanolamine, etc. Alcohols with 5 or more active hydrogen atoms such as diglycerin, pentaerythritol, sorbitol, etc. such as xylitol/sorbitol, glucose, Sucrose, partially saponified polyvinyl acetate, partially saponified polyvinyl acetate copolymer, cellulose, starch, etc. are useful, as well as derivatives such as partially esterified alcohols having two or more active hydrogens. can also be used if at least one active hydrogen remains.

The thinner of the present invention is a polyether compound obtained by adding alkylene oxide to these starting materials and having a molecular weight of 1,000 to 100,000, or a derivative obtained by subjecting the terminal hydroxyl group of the polyether compound to various reactions. In particular, those having a molecular weight of 10,000 to 10,000 are more effective.

Ethylene oxide, propylene oxide, butylene oxide, etc. are used as the alkylene oxide, and these may be used alone or in combination of two or more types. In the case of two or more types, the arrangement is block polymerization type or random polymerization type. Although any type may be used, block polymerization type is common. In particular, polyether compounds containing ethylene oxide as alkylene oxide and having a content of 10 to 95% by weight, preferably 60 to 90% by weight of the total alkylene oxide, or derivatives obtained by various reactions of the terminal hydroxyl groups of the polyether compounds are used. Demonstrates excellent effects.

Also effective are derivatives obtained by subjecting the terminal hydroxyl groups of the above polyether compounds to various reactions. For example, we can cite the one listed in F.

1) Esterified product reacted with organic acid or inorganic acid.

2) Reaction with hydrogen halide or phosphorus halide Hydroxyl group is substituted with halogen.

3) Aldehydes and carboxylic acids produced by oxidation reactions.

4) Reaction product between hydroxyl group and monoisocyanate.

However, the present invention is not limited to the above-mentioned examples. The reason why the present invention's thinning agent exhibits excellent effects is that after it is strongly adsorbed to the particle surface due to its special structure, many ether bonds are bonded to the surrounding water. It is thought that the coal particles are stabilized as primary particles and their fluidity is improved because the water is hydrated and the water is converted into a structure that acts like a lubricating oil. At the same time, a significant decrease in viscosity occurs.

In addition, if you use clean coal that has been deashed, the effect will further increase because deashing removes ash, which is highly hydrophilic and has fine particles with a large surface area, improving its organic properties. This is because the thinner of the present invention effectively acts on the coal surface, thereby increasing the coal concentration.

The thinning agent of the present invention has a zero viscosity for coal-water slurry.
．． Excellent effects can be achieved by adding O in an amount of 1 to 5.0% by weight, preferably 0.03 to 2.0% by weight. The fluidity limit of a coal-water slurry differs depending on the type and particle size of the coal, but generally, if a thinner is not added, the fluidity will be lost at a coal concentration of around 50% by weight, but with the addition of the thinner of the present invention. If this is done, the viscosity will drop significantly, so the coal concentration will be
It has fluidity even at 1% by weight or more, especially 70% by weight or more. If even cleaner coal is used, the coal concentration will be several points higher, generally 3 to 1
Increase by O points.

The thinner of the present invention can also be used in combination with other surfactants.

Methods for producing coal-water slurry Inferior methods for adding a thinner include a method in which the coal is dry-pulverized in advance and then the thinner is mixed into an aqueous solution, or a method in which the thinner is added after making a coal-water slurry. Adding coal, water, and a thinner to the mill and mixing while crushing the coal; or using cleaned coal instead of coal in each method. This method can be implemented.

The thinner of the present invention has an excellent effect of stably dispersing coal in water, and does not cause water separation even when left standing for a long period of time, for example, one month, and maintains a homogeneous coal-water slurry. There is.

Thus, the thinner of the present invention is preferably 0.01 to 5.0% by weight, preferably 0.03 to 20% by weight, based on the coal-water slurry.
By adding only % by weight, the viscosity of coal-water slurry IJ- can be significantly reduced, and a highly concentrated coal-water slurry that can be transported by pump can be produced.

Examples are shown below. In the examples, percentages are by weight.

Example 1 Into an aqueous solution containing a predetermined amount of the thinner shown in Table 1,
Coal pulverized to 0 mesh 80% pass is added at room temperature with stirring to prepare a coal-water slurry of a predetermined concentration. The viscosity of this slurry is measured at 25°C and the fluidity is observed. Furthermore, after this slurry was allowed to stand for one month, the state of water separation was measured. The test results are shown in Table 2.

As shown in Table 2, when the thinner of the present invention is added, the viscosity is 1100 to 2900 even at a coal concentration of 72 to 77%.
cp and has extremely good fluidity. On the other hand, when a general anionic surfactant is added or no thinner is added, the viscosity is 20,000 at a coal concentration of 50%.
CP or more, and there is no flow at all.

The thinner of the present invention significantly reduces the viscosity of the coal-water slurry, making it possible to form a highly concentrated coal-water slurry, and also significantly improves the stability of the coal-water slurry, allowing it to stand still for more than one month. However, no coal settling occurs, and no water separation occurs at all.

Example 2 A cleaned coal-water slurry of a predetermined concentration is prepared in the same manner as in Example 1 using cleaned coal. The coal particle size is 80% nomass of 200 mesh. The viscosity of this slurry is measured at 25°C and the fluidity is also observed. After this slurry was allowed to stand for one month, the state of water separation was measured.

The thinners of the present invention used in the test are shown in Table 1. The test results are shown in Table 3.

As shown in Table 3, when the thinner of the present invention is added to the cleaned coal-water slurry, the viscosity is 1500 to 2500 cp even at a coal concentration of 76 to 80%, and the fluidity is extremely good. On the other hand, if a thinner other than the present invention is added or if no thinner is added, the viscosity will be 20,000 cp or more at a coal concentration of 50%, and it will not flow at all.

(Margin below)

Claims (1)

[Scope of Claims] (1) A thinning agent for highly concentrated coal-water slurry used to reduce the viscosity of coal-water slurry and improve its fluidity, which contains one or more active hydrogen molecules in the molecule. . Preferably, alcohols having 3 or more, more preferably 5 or more, and their derivatives are used as starting materials, and an alkylene oxide is added thereto to form a molecule of 111,000
1. A thinning agent for coal-water slurry, characterized in that it contains as an essential component a polyether compound having a molecular weight of 100,000 to 100,000 or a derivative obtained by subjecting the terminal hydroxyl group of the polyether compound to various reactions. (21) The thinner for coal-water slurry according to claim 1, wherein the polyether compound has a molecular weight of 10,000 to 10,000. 10 to 95% by weight, preferably 60 to 90% by weight of the coal-water slurry thinner according to claim 1 or 2. (4) The coal concentration is 61 to 95% by weight or more, preferably 60 to 90% by weight. is a coal-water slurry thinner according to any one of claims 1 to 3 for use in a coal-water slurry containing 70% by weight or more. (5) A patent in which the coal is cleaned coal. A thinning agent for coal-water slurry according to any one of claims 1 to 4.