JPS62124192A - Dispersion stabilizer for coal-water slurry - Google Patents

Abstract

PURPOSE:A dispersion stabilizer which disperses coal powder into water and makes pipe line transportation possible, containing a specific polyether compound (derivative) as an essential component. CONSTITUTION:The aimed dispersion stabilizer containing a polyether compound (derivative), as an essential component, which is obtained by adding an alkylene oxide containing ethylene oxide as an essential component to a polytetramethylene glycol having 500-2,000 average molecular weight and has part of polyoxyethylene chain with 40-99wt% molecular weight and 2,000-100,000 molecular weight.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a dispersion stabilizer for coal-water slurries.

More specifically, the present invention relates to a dispersion stabilizer for dispersing coal powder in water and stabilizing the dispersion to a state suitable for pipeline transportation.

[Conventional technology and problems]

In recent years, petroleum has been the most commonly used energy source, but due to its limited reserves and the resulting soaring prices, diversifying energy sources and securing a stable supply have become important issues. For this reason, the effective use of coal, which has large reserves and is not unevenly distributed around the world, is being reconsidered.However, unlike oil, coal is a solid substance. , cannot be transported by pipeline, and is extremely disadvantageous in terms of handling.

Furthermore, coal generally contains a larger amount of minerals than petroleum, and there are also problems such as a decrease in calorific value and the processing of fly ash.

For this reason, in order to improve the handling disadvantages, various methods have been studied in which coal is pulverized and dispersed in water to form a slurry. However, in this case as well, if the coal concentration is increased, the coal will significantly thicken and lose fluidity, and if the coal concentration is decreased, the transportation efficiency will decrease and the dewatering process will also be costly, which is not practical. This is because the coal particles in the coal-water slurry aggregate in water, causing an increase in viscosity and a decrease in fluidity.

The smaller the coal particles in the water slurry, the better the dispersion stability, but the cost of pulverization increases as the degree of pulverization increases. Currently, the pulverized coal burned in thermal power plants has a particle size of 200 mesh, 80% pass, or approximately 74 microns, so it is expected that this particle size will be used as a guideline for the particle size of pulverized coal. be done. When a surfactant, which is a dispersant, is added to the coal-water slurry, the surfactant adsorbs to the interface between the coal particles and water, loosening the coal particles and preventing them from agglomerating together. It is expected that this effect will create a good dispersion state.

The present inventors have already developed a dispersant with such an effect (Japanese Patent Application Laid-Open No. 56-20090, JP-A No. 56-216).
36, No. 56-57890, No. 56-57891).

However, although such a dispersant improves fluidity, it is not necessarily satisfactory in practice because, when left standing, the precipitate consolidates and forms a hard cake. Therefore,
The present inventors conducted various studies in order to improve the stationary stability and fluidity, which are drawbacks of conventional coal-water slurries, and added alkylene oxide containing ethylene oxide as an essential component to a polyamine compound. , and the total weight of the polyoxyethylene chain portions is 40% of the total molecular weight.
〜95% by weight, and the amount is 5,000 to 20% by weight.
A stabilizer containing as an essential component one or more nitrogen-containing compounds selected from polyether compounds or their derivatives having a molecular weight of 0.000 and amine compounds or amide compounds has excellent static stability and fluidity. We have already proposed this (Japanese Unexamined Patent Publication No. 60-55087).

However, this dispersion stabilizer also had problems when the coal-water slurry was exposed to high temperatures (e.g. 60°C).

It is absolutely necessary for the coal-water slurry to maintain its fluidity and stability from the time it is produced until it is burned in the boiler, but the additives that have been developed so far do not predict the effects that the slurry will undergo during boiler combustion. The present inventors have discovered that it is extremely weak against high-temperature shear forces. That is, 20
A slurry with very good fluidity at ~30°C
It has the disadvantage that it instantly gels when heated to ℃ and subjected to shearing force. Therefore, in slurry containing such additives, coal particles aggregate during boiler combustion, which is heated to 50-60"C and sprayed with high shear force, resulting in poor combustion efficiency and a large amount of unburned coal particles. The rest is extremely inefficient.

Measures to Solve Problem c] Therefore, the present inventors endeavored to develop a dispersion stabilizer for coal-water slurry that does not lose fluidity even under high-temperature shearing force. First, they discovered a dispersion stabilizer that exhibits extremely excellent effects in terms of stability, and completed the present invention.

That is, the present invention is a compound obtained by adding an alkylene oxide containing ethylene oxide as an essential component to polytetramethylene glycol having an average molecular weight of 500 to 2,000, wherein the polyoxyethylene chain portion of the compound has a molecular weight of 40 to 99. The weight and molecular weight are 2000 in weight percentage
-100,000 polyether compound or its derivative as an essential component.
The present invention provides a dispersion stabilizer for water slurry.

The polytetramethylene glycol used as a starting material for the polyether compound according to the present invention has the following general formula (1
), which can usually be easily obtained by ring-opening polymerization of tetrahydrofuran using fuming sulfuric acid as a catalyst (Japanese Patent Laid-Open No. 48-25438).

HO-(-C11□CHzC1lzCII□0-)-H
(1) The average molecular weight of polytetramethylene glycol is 5
00-2000, preferably 700-1800. Outside the above range, the remarkable effects of the present invention cannot be obtained.

The polyether compound can be easily obtained by adding an alkylene oxide which essentially contains ethylene oxide to the above-mentioned polytetramethylene glycol by a conventional method. Among these, block or partially block adducts of ethylene oxide and propylene oxide are particularly preferred, and the order of addition may be in any order, but
Good dispersion stability is shown when propylene oxide (hereinafter abbreviated as PO) is added first and then ethylene oxide (hereinafter abbreviated as EO) is added.

The molecular weight of the polyether compound or its derivative is 2,00
0 to 100,000, preferably 5,000 to s
o, ooo, more preferably 10,000 to 60,00
It is 0. Further, the total weight of the EO chain portion is 40 to 99% by weight, preferably 80 to 99% by weight of the total molecular weight.

Examples of the polyether compound derivatives of the present invention include sulfates, phosphoric oxides, carboxyalkylated products, and fatty acid esterified products of the terminal hydroxyl group of the polyether compound. Among these, fatty acid esters are particularly preferred. The fatty acid used preferably has 7 to 23 carbon atoms, but the number of double bonds, technique, etc. have no effect on performance.

The polyether compound or derivative thereof of the present invention has the following (b)
-1) By using a compound selected from (b-2) in combination, even more excellent fluidity can be obtained.

(b-1) Amine compound or amide compound (b-2)
MFa aliphatic alcohol, sorbitan fatty acid ester or silicone compound Therefore, the second aspect of the present invention is (a) a compound obtained by adding an alkylene oxide containing ethylene oxide as an essential component to polytetramethylene glycol having an average molecular weight of 500 to 2000. Therefore, the polyoxyethylene chain portion of the compound has a molecular weight of 4
0-99% by weight and a molecular weight of 2000-100
．． The present invention provides a dispersion stabilizer for coal-water slurry, which is characterized by containing a polyether compound of 000 or a derivative thereof, and the following (b-1) and/or (b-2) as essential components. .

(b-1) Amine compound or amide compound (b-2) Aliphatic alcohol, sorbitan fatty acid ester or silicone compound Among the nitrogen-containing compounds selected from the amine compound or amide compound (b-1) of the present invention, as an amine compound is a primary amine such as octylamine, laurylamine,
Tallow amines, secondary amines such as diethylamine, distearylamine, morpholine, etc., tertiary amines such as dimethylstearylamine, dimethyllaurylamine, aromatic amines such as aniline, dibenzylamine, toluidine, etc., and polyamine compounds such as polyalkylene polyamines, alkyl (or alkenyl) polyalkylene polyamines, polyethyleneimine, etc. Examples include polyethylenediamine, triethylenetetramine, laurylpropylenediamine, stearyltriethylenetetramine, stearyltetraethylenepentamine, and stearylpentaethylenehexamine. In addition, amine salts produced by neutralizing these amine compounds with acidic compounds and quaternary ammonium salts quaternized by known methods are also effective. Examples of amine salts include acetates, hydrochlorides, sulfates, etc. of the above amine compounds,
In addition, as quaternary ammonium salts, there are compounds obtained by cationizing the above-mentioned amine compounds with alkyl halasites, dimethyl sulfate, etc. by a known method. Examples include:
Examples include lauryltrimethylammonium chloride and stearyltrimethylammonium chloride.

Further, as the amide compound, there are reactants of carboxylic acid and ammonia or the above-mentioned amine compounds, and examples thereof include stearic acid amide, ethylenediamine lauric acid monoamide, triethylenetetramine stearic acid diamide, and the like.

In addition, (
Among component b-2), specifically, aliphatic alcohols having 6 to 12 carbon atoms are used, such as octyl alcohol, 2-ethylhexyl alcohol, lauryl alcohol, and the like. Examples of sorbitan fatty acid esters include sorbitan monolaurate, sorbitan monopalmitate, sorbitan monooleate, sorbitan monostearate, and the like. Also, similarly,
Among component (b-2), silicone compounds include polydimethylsiloxane, dimethylsilicone oil, fluorosilicone oil, and the like.

The dispersion stabilizer of the present invention has a concentration of 0.0% with respect to the water slurry.
Coal particles can be dispersed in water by adding 0.01 to 5.0% by weight, preferably 0.05 to 2.0% by weight.

The amount of component (b) in the dispersion stabilizer of the present invention is 30% by weight or less, preferably 15 to 5% by weight, based on the polyether compound or derivative thereof of component (a), and is added to the coal slurry together with component (a). They may be added or may be added separately.

The fluidity of a coal-water slurry generally varies depending on the type and particle size of the coal powder, but when no dispersion stabilizer is added, the viscosity increases rapidly when the coal concentration exceeds 30% by weight. On the other hand, when a predetermined amount of the dispersion stabilizer of the present invention is added, coal particles are dispersed, fluidity is significantly improved, and a highly concentrated slurry can be obtained. It is possible to obtain a slurry that does not form, has excellent storage stability, and does not lose fluidity even under high-temperature shearing. If the concentration of coal constituting the coal-water slurry is too low, the transportation efficiency will be poor, and the dewatering process will be expensive, making it meaningless. Also, if it is too large,
Since the viscosity becomes too high, it varies depending on the type and viscosity of the coal, but generally 30 to 85% by weight, preferably 50 to 7% by weight.
It is 8% by weight.

Conventionally, various compounds have been proposed as dispersion stabilizers for coal-water slurries. Examples of compounds similar to the present invention include polyether compounds in which alkylene oxides such as ethylene oxide and propylene oxide are added to compounds having active hydrogen. has been proposed (Japanese Unexamined Patent Publication No. 57-102
No. 994, Japanese Unexamined Patent Publication No. 147595/1983). However, in order to obtain a satisfactory effect with these conventional dispersion stabilizers, it is necessary to add them in a relatively large amount.
Moreover, it was largely influenced by the particle size distribution of coal and the preparation conditions. In addition, if it is added during wet grinding, the fluidity decreases as the grinding progresses, so it is necessary to increase the amount added as the surface area increases, and it also gels instantly under high temperature shear stress. I end up.

The dispersion stabilizer of the present invention has as an essential component a polyether compound obtained by adding fullkylene oxide to polytetramethylene glycol or a derivative thereof, and one or more nitrogen-containing compounds selected from amine compounds or amide compounds. Or/and by using one or more of aliphatic alcohol, sorbitan fatty acid ester, or silicone compound in combination as necessary, excellent effects can be achieved with a relatively small amount of addition, and the effect can be influenced by particle size distribution and preparation conditions. It has revolutionary performance that has never been seen before.

This is because component (b), which has a lower molecular weight than component (a), adsorbs to the pores on the coal surface and makes the pores hydrophobic, thereby preventing the water necessary for dispersion from entering. ) It is thought that this is because the dispersion stability is dramatically improved compared to using the component alone. In addition, because the adsorption power of component (a) to the coal surface is large, the static stability and fluidity under high temperature shear stress are dramatically improved compared to conventional dispersion stabilizers.

The coal used in the present invention may be of various types such as anthracite, bituminous coal, sub-bituminous coal, lignite, etc., and is used after being pulverized. The particle size of this coal powder may be any particle size that allows direct combustion in the boiler, but the general particle size currently used in thermal power plants for this purpose is 200 mesosyu pass rate of 70 to 90%. It is of granularity.

The mixing order of coal, dispersion stabilizer, and water may be any order.
In addition, the preparation method includes a method in which a dispersion stabilizer is dissolved or dispersed in water, dry charcoal is added, and the mixture is stirred and mixed using an attritor, a method in which coarse charcoal, water, and a dispersion stabilizer are pulverized and stirred in a ball mill, Wet-pulverize raw coal using a ball mill to 50%
There are methods such as adding water and a dispersion stabilizer to a dehydrated cake after preparing a slurry without adding a dispersion stabilizer before and after the slurry, and adding water and a dispersion stabilizer to the resulting dehydrated cake and stirring and mixing with an attrike. It also shows excellent performance.

Currently, consideration is being given to removing the ash content from coal by various methods and burning it as a deashed coal-water slurry in a heavy oil-fired boiler. Coal deashing methods at this time include a method that applies the principle of flotation to collect coal by retaining it in water using a collection agent and a foaming agent, and adsorbing the coal to foam, and a method that uses oil and oil in coal slurry. Underwater granulation methods (for example, Japanese Patent Application Laid-open No. 37901/1983), in which coal is recovered by adding and stirring an emulsion and selectively granulating it, have been attracting attention. It shows extremely good dispersion stability even in coal slurry deashed by such a method.In addition, in this case, hydrocarbon oil (for example, diesel oil, heavy oil, B heavy oil, C heavy oil, etc.) is present in the coal slurry. However, the dispersion stabilizer of the present invention exhibits excellent performance without losing its dispersion effect even in systems where such hydrocarbon oils coexist.

The aqueous slurry of coal powder obtained by adding the dispersion stabilizer of the present invention has a small increase in viscosity even under high concentration and high temperature shear stress, has good fluidity, and does not form a hard cake even after long storage. Since it does not generate any product and maintains good dispersion stability, it can be transported by pipeline, stored in tanks, or directly fired in boilers. In addition, the water slurry of coal powder obtained using the dispersion stabilizer of the present invention has good properties, with few bubbles during production (no increase in volume of the slurry, and thickening due to bubbles is prevented).

〔Example〕

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples.

(1) Coal preparation method i) Manufacturing method of deashed coal by underwater granulation method Preasol coal with the following composition of 200 mesh 80% pass 428 g (contains 7.0% water, so pure content is 400 g ) is dispersed in water at room temperature and stirred to obtain a coal-water slurry.2 times heavy oil is added to this mixture.
Add 0g of lab body spar (manufactured by Tokushu Kika Kogyo) at room temperature.
The mixture obtained by stirring at 11,000 rpm for 30 minutes was passed through an 8-mesh sieve to remove the ash content, and dried at 105°C to obtain a deashed and dehydrated granulated product (referred to as deashed coal A).
I got it.

The residual ash content of this product is 4.8wt% (based on coal)
Met.

ii) Method for producing deashed coal by flotation method Similar to i), 428 g of Preasol coal was dispersed in water at room temperature,
Place it in a F-W type flotation machine with 0.5 g of pine oil and perform flotation treatment. Then, the deashed coal slurry collected together with the foam is dehydrated under reduced pressure to obtain deashed coal B.

The residual ash content of this product was 4.0 wt% (coal base $
)Met.

*1 Preasol charcoal calorific value 6720 kcal/kg (JIS M
8814) Ash content 7.1% (JIS 8812) Moisture 7.0% (JIS M 8811) Fixed carbon 59.
7% (JIS M 8812) Table 1 Test coal list (2) Water slurry preparation and fluidity evaluation Table 2, No. 4
Compound 1.85g, Table 3, Compound No. 3 0.19
g, and 0.19 g of the compound in Table 4, No. 100 g
397.8 g of Preasol charcoal No. 1 shown in Table 1 was added little by little to this mixture at room temperature.

After adding the entire amount, use a homo mixer (manufactured by Tokushu Kika Kogyo)
A coal-water slurry was prepared by stirring at 5000 rpm for 5 minutes.

The viscosity was measured at 25°C and was 310 centivoise, indicating good fluidity. Also, in a constant temperature bath at 60℃
When the viscosity was measured after heating for 0 minutes, it was 360 centipoise, indicating good fluidity.

In addition, under the same conditions, the sample charcoal shown in Table 1, the polyether compound or its in 7 substance shown in Table 2 (a component), the (b4) component shown in Table 3, and the (b-2) component shown in Table 4 were added. The results are shown in Table 5.6, including other examples and comparative examples in which various combinations of the above were carried out. Low viscosity indicates good fluidity.

(3) Evaluation of stability of water slurry The stability of the slurry was evaluated for 30 days and 60 days after producing the slurry.
After leaving it for a day, a stainless steel rod with a diameter of 5 dragons (weight 50g)
) was gently placed in the slurry and its sedimentation state was observed.

The slurry prepared in (2) had good stability and 60%
There was almost no compaction even after several days had passed. The results, including other Examples and Comparative Examples, are shown in Table 5.6.

Table 2 -H *2: Q upper h *3=Table 3 showing ester/la$ for terminal hydrogen Table 4 Notes to Table 5.6 *1: See Table 1 *2: See Table 2 *3: Against dry base coal *4: See Table 3 *5 Nidry base coal *6: See Table 4 *7: Dry base coal *8: Against dry base coal *9:○: Good fluidity Δ: Paste-like and slightly fluid.

×: No fluidity *10: ○: Good stability (no consolidation of coal): Slightly good (minimal consolidation of coal) ×: Poor (large consolidation of coal)

Claims (1)

[Scope of Claims] 1. A compound obtained by adding alkylene oxide containing ethylene oxide as an essential component to polytetramethylene glycol having an average molecular weight of 500 to 2000,
The polyoxyethylene chain portion of the compound has a molecular weight of 40
-99% by weight, and the molecular weight is 2000-100,
Dispersion stabilizer for coal-water slurry, characterized in that it contains a polyether compound of 000 or a derivative thereof as an essential component. (a) Alkylene containing ethylene oxide as an essential component in polytetramethylene glycol having an average molecular weight of 500 to 2,000. A compound obtained by adding an oxide, wherein the polyoxyethylene chain portion of the compound accounts for 40 to 99% by weight of the molecular weight, and the molecular weight is 2000 to 1
A dispersion stabilizer for coal-water slurry, characterized in that it contains a polyether compound having a molecular weight of 0.00,000 or a derivative thereof, and the following (b-1) and/or (b-2) as essential components. (b-1) Amine compound or amide compound (b-2) Aliphatic alcohol, sorbitan fatty acid ester or silicone compound