JPS63258990A - Additive for high-concentration coal-water slurry having long life - Google Patents

Abstract

PURPOSE:To obtain the titled additive for a slurry of coal having low ash content, transportable with a pump and directly usable as a fuel for boiler of power plant, by using a naphthalenesulfonic acid formaldehyde condensate, etc., and bentonite, etc., as essential components. CONSTITUTION:The objective additive to be added to a slurry produced by the wet-pulverization of coal having an ash content of <=3% (preferably <=1%) contains (A) an (alkyl)naphthalenesulfonic acid formaldehyde condensate having an average polymerization degree of 10-500 (preferably 35-100), (B) a compound produced by adding 50-300mol. (preferably 75-125mol.) of ethylene oxide to an alkylphenol having 8-12C alkyl group or a compound produced by adding 3-150mol. (preferably 5-30mol.) of ethylene oxide (based on 1mol. of active hydrogen) to a polyhydric alcohol containing 3-6 active hydrogen atoms in one molecule and (C) bentonite.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an additive for coal-water slurry produced by a wet process, 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.

Shubei Huang Ai ■ In recent years, due to the depletion of oil resources and the rise in 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 dilatancy 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. Furthermore, in JP-A-58-17195 and JP-A-58-122991, a nonionic surfactant and naphthalene sulfonate formaldehyde condensate (1,2-3
0 nuclear body) is described. To be more specific, JP-A-58-17195 discloses (a) naphthalene sulfonic acid formalin condensate (2-10 nuclei) and (b) M-alkylene (ethylene oxide: 95-40 mol%, and propylene oxide or Butylene oxide: 5-60
A compound to which 10 moles or more of (mol%) has been added (al:
It is described that (b) is used in combination at a ratio of 5-2:5-8. Furthermore, in JP-A-58-122991, (a) naphthalene sulfonic acid formalin condensate (1,
2-30 nuclear bodies) and fb) a compound having 4-800 moles of ethylene oxide and/or propylene oxide added to a compound having one or more active hydrogen atoms is described. However, in these methods, the stability of the slurry was simply evaluated using a rod penetration test, which was extremely inappropriate when considering actual scale. In other words, after one month of standing,
Even if the rod runs smoothly, the slurry may have increased viscosity or formed soft packs, causing problems in dispensing from the storage tank or static tank, or the spray nozzle may become clogged during combustion. There was a problem. In fact, these additives are extremely problematic when used with low-grade coal (less than 3%), forming hard packs after 3 days.
It was not possible to create a slurry that had self-flowing properties, and it was not possible to create a slurry that maintained 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 slurries that has self-flowing properties and has a long life when the slurry is evaluated using the pot method.

In other words, the present invention provides a method for producing a highly concentrated coal-water slurry by crushing low ash content coal having a natural content of 3% or less, preferably 1% or less in the presence of water. (al) having an average degree of condensation of 10 to 500, preferably 35
-100 formaldehyde condensate of naphthalene sulfonic acid and/or alkylnaphthalene sulfonic acid or a salt thereof;

Preferably, a compound obtained by adding 75 to 125 moles of ethylene oxide per active hydrogen to a polyhydric alcohol having 3 to 6 active hydrogens in the molecule.
Provided is a long-life, high-concentration coal-water slurry additive characterized by containing a compound obtained by adding 0 mol, preferably 5 to 30 mol, and (C) bentonite.

Examples of formaldehyde condensates of naphthalene sulfonic acid and/or alkylnaphthalene sulfonic acids or salts thereof of the additives of the present invention include, for example, naphthalene, methylnaphthalene, ethylnaphthalene, propylnaphthalene, butylnaphthalene, or their salts. Formaldehyde condensates of sulfonated mixtures of or salts thereof may be mentioned.

The average degree of condensation of these formaldehyde condensates of sulfonic acids is 7 to 500. Preferably it is 35-100. If the average degree of condensation is lower than this range, the dispersion power is insufficient;
A highly concentrated slurry cannot be obtained. If the average degree of condensation is too high, the viscosity increases, making it impossible to obtain a fluid additive.

Examples of the salts of formaldehyde condensates of these sulfonic acids 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.

The component (b) of the additive of the present invention has an alkyl group of 08
- A compound obtained by adding 50 to 3 OO moles, preferably 75 to 125 moles of ethylene oxide to an alkylphenol that is 12 alkyl, such as octylphenol, nonylphenol or dodecylphenol, or a polyhydric alcohol having 3 to 6 active hydrogens in the molecule. , for example glycerin.

Butanetriol, hexanetriol, trimethylolpropane, triethanolamine, diglycerin, pentaerythritol, sorbitan.

Examples include compounds obtained by adding 3 to 150 moles, preferably 5 to 30 moles of ethylene oxide per active hydrogen to sorbitol, glucose, etc. These compounds can be prepared by adding ethylene oxide under pressure in the presence of an acid or alkali catalyst according to known methods.

The blending ratio (al/(
b) is preferably 65/35 to 9515 by weight.

If the amount of the ethylene oxide adduct of component (b) is too large, the slurry will gel and no effect will be obtained, so it is very important to maintain the above blending ratio.

As the bentonite component (C), those commonly used in polling, civil engineering, and construction industries, which are commercially available in Japan, can be mentioned.

The average degree of condensation of component (a) of the additive of the present invention is determined by GPC
It can be determined from the weight average molecular weight by analysis.

The GPC measurement conditions mentioned here are as follows.

Column: TSK GEL G-4000SW + G
-3000SW + guard column (Toyo Soda) Column size near, 5-1φX600mm x 2 Column temperature: Room temperature Mobile phase: Acetonitrile 10.05M sodium acetate = 40/60 Flow rate: 0.8511d2/win Detector: Ultraviolet absorption detector Wavelength 254nm standard Substance: Thorium polystyrene sulfonate.

Molecule 1t1600~65000 (Prsssure
Chemical Co.) The coal-water slurry produced using the additive of the present invention is produced by a wet method, specifically, by adding coal, water, and the additive to a pulverizer, and producing it 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 first introduce coal and water at a low concentration into a pulverizer to produce a low concentration slurry, 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.

Examples of the additive of the present invention include those containing the components (a), (b), and (e). The amounts of component Ta) and component (b) to be added are the blending ratio of both components, and the total amount is 0.01 to 5.0% relative to the coal-water slurry.
0% by weight, preferably 0.03-2.0% by weight, fcl
The component is preferably 0.1 to 2% by weight, and the additive of the present invention exhibits excellent effects at this amount. 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 coal concentration is 50% by weight.
Fluidity is lost before and after, but if the additive of the present invention is used, the viscosity decreases significantly, so the coal concentration can be reduced to 60% by weight.
As mentioned above, it has fluidity even at 64% by weight or more.

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.

The conventional formaldehyde condensate of naphthalene sulfonate having a low degree of condensation (degree of condensation of 30 or less) alone has a completely poor dispersion effect, and a highly concentrated water slurry cannot be obtained. For example, formaldehyde condensates of naphthalene sulfonates with a low degree of condensation (1,2 to 30 nuclei) are described in JP-A-58-17195 and JP-A-5B-122991.
When combined with nonylphenol propylene oxide/ethylene oxide adduct (30/70) (M: 33QQ) or adduct of 50 moles of glycerin propylene oxide and 240 moles of ethylene oxide, an increase in the viscosity of the slurry over time and generation of aggregates were observed, and low No effect was observed with Tenmin coal, and a highly concentrated coal-water slurry that formed a hard back in about 3 days and maintained fluidity for a long period of time immediately after production could not be obtained. In other words, as well as the formaldehyde condensate of naphthalene sulfonate with a high degree of condensation as the component (a), which is researched and developed by the present inventor and is unique, it is also unique (the ethylene oxide condensate of alkylphenol in the bl component). Excellent effects are exhibited only when an adduct or an ethylene oxide adduct of a polyhydric alcohol is used in combination with bentonite (C1 component) in a very limited combination.

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 (component (a)), so the steric masking is large, and the additive has a high degree of condensation. This is because when acting at the interface between coal particles and water, the larger the coverage, the more the coal particles are prevented from aggregating and the dispersion power is improved. Moreover, since this prevents the coal from coagulating and settling, it is thought that almost no change in the slurry occurs over time. Also fb
By using the ethylene oxide adduct of alkylphenol or polyhydric alcohol (component) together with bentonite (component (C)), the naphthalene sulfonic acid formaldehyde condensate adsorbed on coal particles is prevented from peeling off, and a network of coal particles is formed. Since the structure can be maintained for a long period of time, it is thought that a highly concentrated coal-water slurry with a long life can be obtained.

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

Example 1 Coal-water slurries were manufactured using the following two methods using Cerrejon coal containing 1% of selected natural ingredients and the additives shown in Table 1.

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

Method (A): Crushed coal (approximately 3 vua or less), water, and additives were put into a ball mill in predetermined amounts and pulverized until the coal particle size reached 80% of the amount passing through 200 meshes.

Method (B): A predetermined amount of coarsely crushed coal (approximately 3 mm or less) and water are put into a ball mill, and the coal concentration is 40% and the coal particle size is 2.
A slurry with a 0.00 mesh passing rate of 80% was produced. Thereafter, the mixture was hydrophilized 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 at a shear rate of 100 sec'.

2) Slurry life: Measured by pot method. In other words, the produced slurry was put into a 250-sized wide robolibin and 1
After allowing the slurry to stand still for several months, the slurry was discharged from the polybottle by gravity and passed through a 5Il1m sieve. At this time, the amount remaining in the polyethylene bottle and the amount of slurry on the 5-tsuru sieve were measured as the amount of agglomeration, 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, a slurry with good fluidity with a coal concentration of 73% and a viscosity of 1000 cps or less can be obtained by wet-producing a coal-water slurry using method (A) or method (B). 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 a coal concentration of 63% and a viscosity of 10,000 cps, resulting in poor fluidity.

Furthermore, although the initial viscosity of the slurry was low even when a nonionic surfactant other than the product of the present invention was used in combination, a hard pack was formed after 3 days, making it unsuitable for dispensing from a tank or the like.

(Left below) Procedural amendment 1. Display of the case 1985 Patent Application No. 093695 2 Title of the invention Additive for long-life, high-concentration coal-water slurry 3 Person making the amendment Relationship to the case Patent applicant name (c35) Dai-ichi Kogyo Seiyaku Co., Ltd. 4. Agent 8, Contents of the Amendment As shown in the attached sheet, Contents of the Amendment ■: Correct "Bate" in the 9th line of page 14 of the specification to "Ba-u-".

Claims (4)

[Claims] (1) An additive added when producing a high concentration coal-water slurry by pulverizing low ash content coal having an ash content of 3% or less, preferably 1% or less in the presence of water, the additive comprising: (a ) Average degree of condensation is 10-500, preferably 35-1
(b) a formaldehyde condensate of naphthalene sulfonic acid and/or alkylnaphthalene sulfonic acid or a salt thereof, which is
A compound obtained by adding 75 to 125 moles of ethylene oxide per active hydrogen to a polyhydric alcohol having 3 to 6 active hydrogens in the molecule.
An additive for a long-life, high-concentration coal-water slurry, characterized in that it contains a compound obtained by adding ~150 mol, preferably 5 to 30 mol, and (c) bentonite. (2) The blending ratio of component (a)/component (b) is 65/35~
1. The long-life, high-concentration coal-water slurry additive according to item 1, which has a rating of 95/5. (3) 0.1 to 2% by weight of component (c) based on slurry
The long-life, high-concentration coal-water slurry additive according to item 1. (4) The additive for long-life, high-concentration coal-water slurry according to items 1 to 3, wherein the coal concentration is 60% by weight or more, preferably 64% by weight or more.