JPS63258988A - Additive for high-concentration coal-water slurry having long life - Google Patents

Abstract

PURPOSE:To obtain the titled additive for a slurry transportable with a pump and directly usable as a fuel for boiler, by reacting an aldehyde with a condensate of an (alkyl)naphthalenesulfonic acid and formaldehyde and using the produced specific compound (salt) as essential component. CONSTITUTION:The objective additive contains a compound or its salt produced by reacting (i) a condensation product of an (alkyl)naphthalenesulfonic acid and formaldehyde having an average condensation degree of 10-500 (preferably 35-100) with (ii) 0.1-1.0mol. (preferably 0.2-0.5mol.) of a >=2C aldehyde (e.g. acetaldehyde, butylaldehyde or benzaldehyde). The additive is applicable to a wet-pulverized slurry having a coal concentration of >=60wt.% (preferably >=64wt.%).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an additive for coal-water slurry produced by a wet method, and more specifically, it has a long life that can be transported by pump and can be used as boiler fuel in power plants, etc. The present invention relates to an additive for obtaining a long and highly concentrated coal-water slurry.

In recent years, due to the depletion of petroleum resources and soaring prices, the use of coal has been rediscovered, and various ways of using it are being considered. 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.

Lower coal concentrations reduce transportation efficiency and require a dehydration step before combustion, which increases costs.

Therefore, research is being conducted on thinning agents that reduce the viscosity of highly concentrated coal-water slurries.

JP-A-56-21636 and JP-A-56-136665 describe that a formalin condensate of naphthalenesulfonic acid or a salt thereof having a degree of condensation of 1.2 to 30 is useful for this purpose. However, it has been found that the formalin condensate of naphthalene sulfonic acid or its salt proposed in the prior art does not have a sufficient dispersion effect, and that giratancy occurs when the coal concentration exceeds 60%, making pumping difficult. Ta. In addition, there were many problems in that the produced slurry changed over time, that is, the viscosity increased over time, and sedimentation and consolidation occurred.

More specifically, the prior art describes naphthalene sulfonic acid formalin condensates (degree of condensation 4). However, the stability of these slurries had not been evaluated, and the coal concentration was 60% by weight or less, making them extremely inappropriate. In fact, these additives had no effect at all, and the viscosity of the slurry after standing for one month was 10,000 cps.
It was not possible to create a slurry that thickened rapidly and had self-flowing properties, and it was not possible to create a slurry that maintained its fluidity immediately after production for a long period of time and did not settle.

Therefore, it is an object of the present invention to solve these problems and provide an additive for highly concentrated coal-water slurry that has a long life and self-flowing properties.

In other words, the present invention is an additive that is added when producing a highly concentrated coal-water slurry by pulverizing coal in the presence of water, and preferably has an average degree of condensation of 10 to 500°. 35-1
00 naphthalene sulfonic acid and/or alkylnaphthalene sulfonic acid with formaldehyde and carbon number 2
The present invention provides a long-life, high-concentration coal-water slurry additive containing a compound obtained by reacting the above aldehyde or a salt thereof as an essential component.

Examples of the formaldehyde condensate of naphthalene sulfonic acid and/or alkylnaphthalene sulfonic acid as starting materials for the additive of the present invention include naphthalene, methylnaphthalene, and ethylnaphthalene.

Formaldehyde condensates of sulfonated products of propylnaphthalene, butylnaphthalene or mixtures thereof may be mentioned.

Next, examples of aldehydes having 2 or more carbon atoms include acetaldehyde, butyraldehyde, benzaldehyde, and the like.

Examples of the additive of the present invention include a compound obtained by reacting the formaldehyde condensate of the naphthalene sulfonic acid and/or alkylnaphthalene sulfonic acid with the aldehyde having 2 or more carbon atoms, or a salt thereof.

When an aldehyde having 2 or more carbon atoms is reacted, the ratio thereof is 0.1 to 1.
The reaction is preferably 0 mol, preferably 0.2 to 0.5 mol, and the addition time is during the reaction of formaldehyde condensation with naphthalene sulfonic acid and/or alkylnaphthalene sulfonic acid, or after the completion of the reaction.

The average degree of condensation of a compound obtained by reacting a formaldehyde condensate of naphthalene sulfonic acid and/or alkylnaphthalene sulfonic acid with an aldehyde having 2 or more carbon atoms is 10 to
500. Preferably it is 35-100. If the average degree of condensation is lower than this range, the dispersion force will be insufficient and a highly concentrated slurry cannot be obtained. If the average degree of condensation is too high, the viscosity will increase, making it impossible to obtain an additive with fluidity.

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

The average degree of condensation of a compound or a salt thereof obtained by reacting a formaldehyde condensate of naphthalene sulfonic acid and/or an alkylnaphthalene sulfonic acid with an aldehyde having 2 or more carbon atoms is determined from the weight average molecular weight by GPC analysis. The GPC measurement conditions mentioned here are as follows.

Column: TSK GEL c-4ooosW + G
-3000S enemy + guard column (Toyo Soda) Column size: 7.5 mmφ x 600 mm x 2 Column temperature: Room temperature Mobile phase: Acetonitrile 10.05 M sodium acetate = 40/60 Flow rate: 0.85 m/min Detector: Ultraviolet absorption detector Wavelength 254nm standard: sodium polystyrene sulfonate.

Molecular weight 1600-65000 (PressureC
chemical Co.) 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. 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 mesh pass 70
% or more, this particle size is a standard. However, the additive of the present invention is not affected by particle size (it exhibits excellent effects for any particle size).

Cleaned coal is coal from which inorganic substances such as ash and sulfur have been removed. Methods for cleaning coal include, for example, heavy liquid separation method, Oil Ag
There are methods such as glomeration method (hereinafter referred to as OA method) and flotation method. However, methods other than these may also be used and are not particularly limited.

Regarding the OA method, after dry or wet pulverization of coal, water slurry is prepared and 3j! Selectively add I amount of oil or coat coal with oil in advance, prepare a water slurry, and stir to utilize the difference in wettability of the organic and inorganic components of the coal to oil and water. The oil that wets the organic content of coal is used as a binder to cause coal organic content to coagulate. 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 50
%.

The oil used in the OA method is generally crude oil or various fractions obtained from crude oil, such as kerosene, light oil, A heavy oil, B heavy oil, C heavy oil, etc., cool or shale oil, ethylene cracked residual oil, or various blended oils. The oils used are mineral oils such as lubricating oils and cleaning oils. Although benzene, toluene, xylene, animal and vegetable oils, etc. 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% or less of 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 floss. Similar to the OA method, in this method, the organic components of the coal adhere to the froth 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 percent or more of inorganic substances are removed from coal by the above method.

When using coal that has been cleaned in this way, the effect of the additive of the present invention is significantly superior to that of coal that has not been cleaned, and a coal-water slurry that is several points higher in 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 sulfur dispersion equipment is reduced.

The coal-water slurry produced using the additive of the present invention is produced by a wet method, and specifically, coal, water, and the additive are added to a pulverizer, and the slurry is produced while pulverizing the coal. At this time, the additive may be added all at once at the beginning, or may be added in multiple stages in the middle. It is also useful to put coal and water in a pulverizer at a low concentration to produce a slurry at a low concentration, then dehydrate the slurry, add additives thereto, and mix the slurry. However, the present invention is not limited to these specific manufacturing methods, but is directed to all manufacturing methods that include the step of pulverizing coal in water.

The amount of the additive of the present invention used is 0.01 to 5.0% by weight, preferably 0.03 to 2.0% by weight, based on the coal-water slurry.
It is 0% by weight, and this amount exhibits excellent effects. The fluidity limit of a coal-water slurry varies depending on the type and particle size of the coal, but generally, if no additives are used, the fluidity will disappear when the coal concentration is around 50 M%, but if the additive of the present invention is used, Since the viscosity decreases significantly, the coal maintains fluidity even when the coal concentration is 60% by weight or more, especially 64% by weight or more. Furthermore, when cleaned coal is used, the coal concentration increases by several points.

In addition, there was no visible change in the slurry over time, and even after it was left standing for a month, no coal agglomeration or sedimentation occurred, and it had self-flowing properties that allowed it to be easily pumped out of the tank. A highly concentrated coal-water slurry with a long life can be produced.

In the conventional formaldehyde condensate of naphthalene sulfonate having a low degree of condensation (degree of condensation of 30 or less), the dispersion effect was quite poor, and a highly concentrated coal-hose slurry could not be obtained.

That is, only when using a compound obtained by reacting an aldehyde having 2 or more carbon atoms in the molecule of a condensate of naphthalene sulfonic acid formaldehyde with an unprecedentedly high degree of condensation, which was researched and developed only by the present inventor. It has been discovered that this method has excellent effects.

Considering the reason why the performance is so excellent, the additive of the present invention has a high degree of condensation of the formaldehyde condensate of naphthalene sulfonate, so the steric masking is large, and the additive has a high degree of condensation at the interface between coal and water. When the coal particles act together, the larger the coverage, the more the coal particles are prevented from agglomerating together.
This is to improve dispersion power. Moreover, since this prevents the coal from coagulating and settling, it is thought that almost no change in the slurry occurs over time. In addition, by further reacting aldehydes with carbon numbers of 2 or more, the additive becomes hydrophobic, increasing adsorption to coal particles, and maintaining the network structure of coal particles for a long time. It is assumed that a slurry is obtained.

Examples and comparative examples of the present invention are shown below. These percentages are by weight.

Example 1 Coal-water slurries were produced using bituminous coal and the additives shown in Table 1 using the following two methods.

The coal used was coarsely ground to a particle size of approximately 2 grains using a dry mill.

Method (A): A predetermined amount of coarsely crushed coal (approximately 3 mm or less), water, and additives were put into a ball mill and pulverized until the coal particle size became 80% N passing through 200 mesh.

Method (B): A predetermined amount of coarsely crushed coal (approximately 3 tm or less) and water were put into a ball mill to produce a slurry with a coal concentration of 40% and a coal particle size of 200 mesh passing through 80%. Thereafter, the mixture was dehydrated to a predetermined concentration, additives were added thereto, and the mixture was stirred with a laboratory spar to obtain a slurry.

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

1) Slurry viscosity = Measured at 25°C using a Burke rotational viscometer and a shear rate of 1005 ec-''.

2) Slurry life: Measured by pot method. In other words, the produced slurry was placed in a 250-glass wide-mouth polyethylene bottle.
After being allowed to stand for several months, the slurry is discharged from the polyethylene bottle by gravity and passed through a 5 fl sieve. At this time, the amount remaining in the polybottle and the amount of slurry on the 5n sieve were measured as the amount of aggregation, and the aggregation rate (%) with respect to the total slurry was determined. The viscosity of the slurry was also measured after it was left standing 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 2.

As is clear from Table 2, according to the present invention, by wet-producing a coal-water slurry using method (A) or method (B), a highly fluid slurry with a coal concentration of 77% and a viscosity of 1000 cps or less can be produced. 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 with a long life. on the other hand,
In the case of a comparative example that does not meet the essential conditions of the present invention, the naphthalene sulfonic acid formaldehyde condensate with a low degree of condensation had good fluidity with a viscosity of 1,300 to 1,400 cps at a coal concentration of 60%, but the viscosity after standing for one month was 10,000 cps.
The fluidity was extremely poor, and the amount of agglomeration was extremely large, making it unsuitable for discharging from a tank or the like.

Example 2 The same coal as in Example 1 was used, and the additives shown in Table 1 were used. The coal-water slurry was produced by the following two methods using deashed coal.

Method (C): A predetermined amount of coal, water, and additives cleaned by the OA method were put into a ball mill and pulverized until the coal particle size reached 80% of the amount passing through 200 mesh.

Method (D): A predetermined amount of coarsely crushed coal (approximately 31 m or less) and water were placed in a ball mill to produce a slurry with a coal concentration of 15% and a coal particle size of 200 m/nosh passing through 80%. This slurry was deashed by flotation and dehydrated to a predetermined concentration. Additives were added thereto and stirred with a lab body spar to obtain a slurry.

The final slurry produced was evaluated using the same test method as in Example 1. The evaluation results are shown in Table 3.

As is clear from Table 3, according to the present invention, by wet-producing a coal-water slurry using cleaned coal by method (C) or method (D), the viscosity is 1000 cps or less at a coal concentration of 80%. A slurry with good fluidity was obtained. In addition, even after the slurry had been allowed to stand for one month, there were almost no aggregates, and the viscosity of the slurry had hardly increased.
It was possible to obtain a high degree coal-water slurry with a long life.

On the other hand, the naphthalenesulfonic acid formaldehyde condensate with a small degree of condensation shown in the comparative example already has a slurry viscosity of 9000 cps or more at a coal concentration of 67%, and has poor fluidity.

(Margin below) Procedural amendment

Claims (5)

[Claims] (1) Naphthalene sulfone is an additive added when producing a highly concentrated coal-water slurry by pulverizing coal in the presence of water, and has an average degree of condensation of 10 to 500, preferably 35 to 100. An additive for a long-life, high-concentration coal-water slurry, characterized by containing a compound obtained by reacting an acid and/or a formaldehyde condensate of an alkylnaphthalene sulfonic acid with an aldehyde having 2 or more carbon atoms, or a salt thereof. (2) The long-life, high-concentration coal according to item 1, wherein the aldehyde having 2 or more carbon atoms is 0.1 to 1.0 mol, preferably 0.2 to 0.5 mol, relative to naphthalene and/or alkylnaphthalene. -Additive for water slurry. (3) The first aldehyde having 2 or more carbon atoms is acetaldehyde, butyraldehyde or benzaldehyde.
Additive for long-life, high-concentration coal-water slurry as described in . (4) The additive for long-life, high-concentration coal-water slurry according to any one of items 1 to 3, wherein the coal concentration is 60% by weight or more, preferably 64% by weight or more. (5) The additive for a long-life, high-concentration coal-water slurry according to any one of items 1 to 4, wherein the coal is cleaned coal.