JPH04114091A - Coal-water slurry composition having long service life - Google Patents

Abstract

PURPOSE:To obtain the subject composition directly usable as boiler fuel in a power plant capable of being transported through a pump produced with a wet method containing respectively specific coal, condensate of naphthalenesulfonic acid, etc., phosphate, etc., and water in a specific ratio. CONSTITUTION:The aimed composition contains (A) coal containing >=20wt.% ash, (B) a mixture (0.1-1.0wt.% in the composition) composed of (i) formaldehyde condensate (or salt of said condensate) of (alkyl)naphthalenesulfonic acid having 10-500 (preferably 35-100) average degree of condensation and (ii) at least a species selected from the group consisting of phosphate, hydroxycarboxylate and poly(meth)acrylate in a weight ratio of 10/90-60/40 and (C) water.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a coal-water slurry composition produced by a wet method, and more specifically, a coal-water slurry composition with a long life that can be transported by pump and used as boiler fuel in power plants, etc. The present invention relates to a coal-water slurry composition.

(Prior Art) In recent years, due to the depletion of oil resources and high prices, the use of coal has been rediscovered, and various methods of using it are being studied. However, since coal is solid and cannot be transported by pump, a water slurry of pulverized coal that can be transported by pump and can be directly burned as boiler fuel in power plants, etc. is attracting attention. However, if a slurry of coal and water is produced without using chemicals, the viscosity of the slurry becomes high, making it impossible to produce a water slurry with a high coal concentration.

Coal also includes lignite, sub-bituminous coal, bituminous coal,
It has a wide range of ash content, ranging from low ash content of 3% or less to high ash content of 20% or more.

Therefore, various studies are being conducted on additives for producing water slurries with low viscosity suitable for these coals.

For example, the present inventors have already disclosed a low ash content coal having an ash content of 3% or less in JP-A-63-258990. However, the reality is that there is no suitable additive for coal with a high ash content of 20% or more. In fact, Japanese Patent Application Laid-open No. 56-21636 and No. 56-1
Even if a formalin condensate of naphthalene sulfonic acid or a salt thereof having a degree of condensation of 1.2 to 30 was used as disclosed in Japanese Patent No. 36665, it was not suitable at all for coal containing high ash content, and a slurry could not be produced.

(Section W1 to be solved by Issue 1) The present invention aims to solve these problems and provide a long-life coal-water slurry composition that has self-flowing properties and has a long life.

(Means for Solving the Problems) A long-life coal-water slurry composition with a final completion date of one month includes (A) coal having an ash content of 20% or more and (B) an average degree of condensation of 1O to 500, preferably 35 to 1.
00, formaldehyde condensates of naphthalene sulfonic acid and/or alkylnaphthalene sulfonic acids, and salts thereof; and (C) phosphates, hydroxycarboxylate salts, and poly(
In a long-life coal-water slurry composition consisting of at least one selected from the group consisting of meth)acrylates and (D) water, (B
) and (C) ratio (weight) is 10/! 110~EiO/
40, and the sum of (B) and (C) is 0.1 in the composition.
The gist is to add it so that it is present at ~1.0%.

As for the coal of component (A) in January, the ash content is 2.
It is an essential condition that the content is 0% or more, and specific examples include lignite, subbituminous coal, deep blue coal, and anthracite coal.

Examples of the formaldehyde condensate of naphthalene sulfonic acid and/or alkylnaphthalene sulfonic acid as component (B) include formaldehyde condensates of sulfonates of naphthalene, methylnaphthalene, ethylnaphthalene, propylnaphthalene, butylnaphthalene, or mixtures thereof. .

The average degree of condensation of these compounds is 10-500, preferably 35-100. If the average degree of condensation is lower than this range, the dispersion force will be insufficient and it will not be possible to obtain a highly concentrated slurry. If the average degree of condensation is too high, the viscosity will increase and it will not be possible to obtain a fluid additive. .

Examples of the salts of these compounds include alkali metal salts such as sodium salts and potassium salts, alkaline earth metal salts such as calcium salts and magnesium salts, ammonium salts, and amine salts.

Examples of the phosphate salts of component (C) include birophosphoric acid, hexametaphosphoric acid, and tripolyphosphoric acid, and examples of hydroxycarboxylic acid salts include citric acid, tartaric acid, malic acid, grape acid, tartronic acid, and salicylic acid.

Examples of the poly(meth)acrylates include sodium salts, potassium salts, calcium salts, magnesium salts, ammonium salts, etc., and examples of poly(meth)acrylates include those having a molecular weight of 10,000 or less, similar to the above salt types.

As mentioned above, the long-life coal-water slurry composition of the present invention consists of component (A), component (B), component (C), and water as component (D), and the ffi amount of (B) and (C). The ratio is 10/90
-80/40 and it is essential to add so that the total of (B) and (C) is present in the composition in an amount of 0.1-1.0%. If the ratio of (B) and (C) is outside this range, the slurry will gel and the desired composition cannot be obtained, and if the total of (B) and (C) is less than 0.1%, the slurry will gel. If the amount exceeds 1%, the viscosity of the slurry will increase rapidly.

Therefore, it is particularly important to maintain the ratio of (B) and (C) and the total addition amount of (B) and (C).

The coal-water slurry composition produced using the component (B) and the component CC) of the present invention is produced by a wet method, and specifically, it is passed to a pulverizer to remove the high ash content of the component (A) and the ( It is produced by adding additives (B) and (C) and water (D) while pulverizing coal.

At this time, components (B) and (C) may be added all at once at the beginning, or may be added in multiple stages in the middle.
Alternatively, a method may be used in which coal and water are put into a pulverizer at a low concentration to produce a low concentration slurry, which is then dehydrated and the components (B) and (C) are added thereto and mixed.

It is preferable that components (B) and (C) are not used separately, but are mixed in advance and used simultaneously.

However, the present invention is not limited to these specific production methods, but is directed to all production methods that include the step of pulverizing coal in water.

Also, the particle size of the coal in the water slurry may be any particle size, but the pulverized coal currently burned in thermal power plants is 200
Since the mesh pass is 70% or more, this particle size is a standard.

However, the coal-water slurry composition of the present invention is not affected by particle size, and provides a long-life coal-water slurry composition at any particle size.

(Function) Generally, unless additives are used, a coal-water slurry loses fluidity when the coal concentration is around 50%, but if high ash content coal is used, a slurry with fluidity can be obtained even at a coal concentration of 40%. I can't.

However, in the present invention, component (B) is divided into minutes and component (C) is divided into (
When used with component A), high ash content coal, the viscosity decreases significantly, and the slurry remains fluid even when the coal concentration is 60% or higher, especially 70% or higher, and no change in slurry is observed over time, and it lasts for one month. A long-life coal-water slurry composition that can be easily discharged from the tank without any A2 collection or sedimentation of coal even if left standing still can be obtained.

(Example) Examples and comparative examples of the present invention are shown below, and the percentages in these are based on the main gate standard.

The ash content and (B) component of the coal used in Table 1 of Examples and (
C) Indicates the types of components.

Note that the coal-water slurry was manufactured using the following two methods.

The coal used was coarsely ground to a particle diameter of 2 mm using a dry mill.

Method (A): Coarsely crushed coal (approximately 3 cm or less), water, and additives were placed in a ball mill in predetermined amounts and pulverized until the coal particle size was 80% through 200 mesh.

Method (B): A predetermined amount of coarsely crushed coal (approximately 31 mm or less) and water were put into a ball mill to produce a slurry with a coal grain size of 30% and a coal particle size of 80% passing through 200 meshes. Thereafter, the mixture was dehydrated to a predetermined concentration, additives were added thereto, and the slurry was stirred in a laboratory dispenser to obtain a slurry.

In addition, the manufactured slurry was evaluated by the test method shown below.

l) Slurry viscosity: Measured at 25°C using a Haake rotational viscometer and a shear rate of 1005ec-1.

2) Slurry life: Measured by the Bott method.

That is, the produced slurry is placed in a 25 GmjL wide roboli bottle and left to stand for one month, and then the slurry is discharged from the poly bottle by gravity and passed through a sieve with 51 inlets.

At this time, the amount remaining in the polyethylene bottle and the amount of slurry on the 5-inch sieve were measured using an aggregation lid, and the aggregation rate (%) with respect to the total slurry was determined.

The viscosity of the slurry was also measured after it had been allowed to stand for one month.

Slurry with a smaller amount of agglomeration and a viscosity that is unchanged from immediately after production is a better slurry with a longer lifespan.

The evaluation results are shown in Table tjS2.

As is clear from US2k, in accordance with the original EJJ, (A)
By wet-manufacturing a coal-water slurry using the method or the method (B), a slurry with good fluidity of around 700 cp and a coal content of 70% was obtained.

In addition, even after the slurry was allowed to stand for one month, there were almost no aggregates and the viscosity of the slurry hardly increased, making it possible to obtain a highly concentrated coal-water slurry composition with a long life.

On the other hand, in the case of a comparative example that does not meet the essential conditions for undeveloped IJJ, the viscosity is 10,000 cp at a coal concentration of 55% using only a naphthalene sulfonic acid formaldehyde condensate with a low degree of condensation.
As a result, the liquidity was extremely low.

Further, the viscosity of component (B) alone and component (C) alone was 3,000 cP and 10,000 cP, respectively, and the viscosity increased.

The blending ratio of component (B) and component (C), and the combination ratio of component (B) and (
When the amount of component C) added did not satisfy the conditions of the present invention, the slurry viscosity was 2000 cp, which was high.

(Effects of the Invention) The coal-water slurry composition obtained according to the present invention shows changes in the slurry over time, and Ishikawa's agglomeration after standing for one month.
To provide a self-flowing high-concentration coal-water slurry having a low viscosity and a long life, in which no sedimentation or the like is observed and which can be easily discharged from a tank by a pump.

Previously (Unexamined Japanese Patent Publication No. 56-21636 and 56-136665)
The dispersion effect of the formaldehyde condensate of naphthalene sulfonate (described in the above publication) is completely poor, and high concentration coal
No water slurry was obtained. In fact, it had no effect on coal containing high ash content, and slurry could not be produced.

In other words, it is effective only when components (B) and (C) are used in a very limited combination and in a limited amount in high-ash content coal containing 20% or more of ash, which is component (A). This is what I discovered.

The reason why the combination of component (B) and component (C) obtained according to 1 undeveloped IJJ has excellent performance is that the formaldehyde of naphthalene sulfonic acid and/or alkylnaphthalene sulfonic acid of component (B) The greater the degree of condensation of the condensate, the greater the three-dimensional coverage, which means that the adsorption layer for the unevenly shaped coal particles becomes thicker.

When acting at the interface between coal and water, the larger the coverage, the higher the concentration can be in order to prevent coal particles from colliding with each other and improve the dispersion force.This prevents coagulation and sedimentation of coal and reduces changes in slurry over time. This is considered to be something that almost never happens.

In addition, component (C), phosphate, hydroxycarboxylate, poly(meth)acrylate, etc., selectively adsorbs to the heavy metal ash exfoliated from the coal particles, forming an M absorption layer on the surface of the ash particles. However, it is considered to have an excellent effect of dispersing particles similar to coal particles and prevent agglomeration.

However, it is believed that these effects will not be exhibited if component (B) or component (C) is used alone, and that the above functions will be exhibited due to a synergistic effect only when both are used in the ratio according to the present invention. It will be done.

Therefore, it is particularly important to maintain the ratio and addition amount of components (B) and (C) for coal containing 20% or more of ash, which is component (A).

Claims (1)

[Scope of Claims] (A) Coal having an ash content of 20% or more and (B) an average degree of condensation of 10 to 500, preferably 35 to 1.
00, formaldehyde condensates of naphthalene sulfonic acid and/or alkylnaphthalene sulfonic acids, and salts thereof; and (C) phosphates, hydroxyl carboxylates, and poly(
In a long-life coal-water slurry composition consisting of at least one selected from the group consisting of meth)acrylates and (D) water, (B
) and (C) in a ratio (weight) of 10/90 to 60/40, and the total amount of (B) and (C) in the composition is 0.1 to 1.
A long-life coal-water slurry composition characterized in that the slurry composition is added in an amount of 0%.