JPH0443957B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a dispersion stabilizer for a water slurry of coal powder. 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. In recent years, petroleum, which has been the most widely used energy source, has reached the limit of its reserves and its price has soared, making it important to diversify energy sources and ensure a stable supply. There is. For these reasons, the effective use of coal, which has large reserves and is not unevenly distributed around the world, is being reconsidered. However, unlike petroleum, coal is a solid, so it cannot be transported by pipeline and is extremely disadvantageous in terms of handling. Furthermore, coal generally contains a larger amount of ash than petroleum, which causes problems such as lower calorific value and fly ash disposal. Due to this, in order to improve the handling disadvantages, coal is pulverized and dispersed in water to form a slurry.
Various methods are being considered. However, in this case as well, increasing the coal concentration will result in a marked increase in viscosity and loss of fluidity, while decreasing the coal temperature will reduce transport efficiency and further increase the cost of the dehydration process, 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 amount of pulverized coal being burned in thermal power plants is 200 mesh.
Since the particle size is 80% pass, that is, about 74 microns, it is expected that this particle will be used as a guideline for the particle size of pulverized coal. 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 having such an effect (see Japanese Patent Application No. 54-95173). However, although such a dispersant improves fluidity, it is not necessarily satisfactory in practice because the sediment is compacted and a hard cake is formed when the dispersant is allowed to stand still. The present inventors have conducted extensive research to improve the static stability and fluidity, which are the drawbacks of conventional coal-water slurries, and have found that the dispersion stability, which has excellent effects on static stability and fluidity, has been found. discovered the agent and completed the present invention. That is, the present invention provides (a) an alkylene oxide that essentially contains ethylene oxide is added to a polyamine compound, and the total weight of the polyoxyethylene chain portion is 40 to 95% by weight of the total molecular weight, and the molecular weight is 5,000 to 200,000. Contains as an essential component one or more nitrogen-containing compounds selected from polyether compounds or derivatives thereof, and (b) amine compounds or amide compounds, and optionally
(c) 1 selected from the group consisting of aliphatic alcohols, sorbitan fatty acid esters, and silicone compounds;
A dispersion stabilizer for water slurry of coal powder characterized by containing one or more species. Further, the dispersion stabilizer of the present invention is a dispersion stabilizer for water slurry of coal powder, which is effective also for coal deashed by flotation method or underwater granulation method. The polyamine compounds used as raw materials for the polyether compound or its derivatives obtained by adding an alkylene oxide containing ethylene oxide to the polyamine compound used as component (a) of the dispersion stabilizer of the present invention include ethylenediamine, propylene diamine, diethylene triamine, triethylene tetramine, Examples include polyalkylene polyamines such as tetraethylenepentamine and polyethyleneimine. A polyether compound can be easily obtained by adding an alkylene oxide essentially containing ethylene oxide to a polyamine compound by a conventional method. Among these, block or partially block-like adducts of ethylene oxide and propylene oxide are particularly preferred, although the order of addition may be in any order, but propylene oxide (hereinafter abbreviated as PO) is added first, and then ethylene oxide is added. (hereinafter abbreviated as EO) shows good dispersion stability. The molecular weight of the polyether compound or its derivative is
The range is 5,000 to 200,000, preferably 10,000 to 100,000, and more preferably 30,000 to 80,000. Also
The total weight of the EO chain portions is 40-95% by weight of the total molecular weight, preferably 80-95%. Examples of the derivatives of the polyether compound of the present invention include sulfates, phosphoric oxides, carboxylalkylated products, fatty acid esterified products of the terminal hydroxyl group of the polyether compound, and those obtained by cationizing a part of the nitrogen atom of the polyether compound. Among these, fatty acid esters and cationized products are particularly preferred. In the case of fatty acid esterification, the fatty acid used preferably has 7 to 23 carbon atoms,
The number of double bonds, branching, etc. have no effect on performance.
Examples of cationized products include compounds obtained by cationizing a polyether compound with dialkyl sulfuric acid, alkyl halide, etc., and cationized products neutralized with acetic acid, alkylbenzenesulfonic acid, etc. As component (b) of the present invention, one or more nitrogen-containing compounds selected from amine compounds and amide compounds are used. Among nitrogen-containing compounds,
Amine compounds include primary amines such as octylamine, laurylamine, tallow amine, secondary amines such as diethylamine, distearylamine, morpholine, etc., tertiary amines such as dimethylstearylamine, dimethyllaurylamine, aromatic amines such as aniline, dibenzyl, etc. Amine, toluidine, etc. and polyamine compounds include polyalkylene polyamine, alkyl (or alkenyl) polyalkylene polyamine, polyethylene imine, etc. Examples include ethylene diamine,
These include triethylenetetramine, laurylpropylene diamine, stearyltriethylenetetramine, stearyltetraethylenebentamine, and stearylpentaethylenehexamine. Also effective are amine salts produced by neutralizing these amine compounds with acidic compounds and quaternary ammonium salts quaternized by known methods. Examples of amine salts include acetates, hydrochlorides, sulfates, etc. of the above-mentioned amine compounds, and quaternary ammonium salts include compounds obtained by cationizing the above-mentioned amine compounds with alkyl halides, dimethyl sulfate, etc. by a known method. Examples include lauryltrimethylammonium chloride and stearyltrimethylammonium chloraoid. 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 the components (c) used as necessary in the dispersion stabilizer of the present invention, the aliphatic alcohol specifically has a carbon number of 6 to 12.
Examples of aliphatic alcohols used include octyl alcohol, 2-ethylhexyl alcohol, and lauryl alcohol. Examples of sorbitan fatty acid esters include sorbitan monolaurate, sorbitan monobalmitate, sorbitan monooleate, sorbitan monostearate, and the like. Similarly, silicone compounds of component (c) include polydimethylsiloxane, dimethylsilicone oil, fluorosilicone oil, and the like. The dispersion stabilizer of the present invention can disperse coal particles in water by adding it in an amount of 0.01 to 5.0% by weight, preferably 0.05 to 2.0% by weight, based on the water slurry. Both components (b) and (c) in the dispersion stabilizer of the present invention are 30% by weight or less, preferably 15 to 5% by weight, based on the polyether compound or its derivative as component (a), and It may also be added to the coal slurry along with
It may also be added separately to the coal slurry. 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.At the same time, if left for a long time, it will settle and form a hard cake. This makes it possible to create a slurry with excellent storage stability. 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, the viscosity will become too high, so it varies depending on the type and viscosity of the coal, but it is generally 30-85% by weight, preferably 50-85% by weight.
It is 78% by weight. Conventionally, various compounds have been proposed as dispersion stabilizers for coal water slurry. 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 Publications No. 102994/1982 and No. 147595 of 1983). However, with these conventional dispersion stabilizers, it is necessary to add a relatively large amount in order to obtain a satisfactory effect, and it is greatly influenced by the particle size distribution of coal, preparation conditions, etc. When added during wet milling, fluidity decreases as milling progresses, so it is necessary to increase the required amount as the surface area increases. The dispersion stabilizer of the present invention has as an essential component a polyether compound obtained by adding alkylene oxide to a polyamine compound or a derivative thereof, and uses this in combination with one or more nitrogen-containing compounds selected from amine compounds or amide compounds. Furthermore, by using one or more of aliphatic alcohols, sorbitan fatty acid esters, or silicone compounds in combination as necessary, excellent effects can be achieved with a relatively small amount of addition, and particle size distribution, adjustment conditions, etc. It has revolutionary performance that is unaffected. This is because components (b) and (c), which have lower molecular weights than component (a), adsorb to the pores on the coal surface and make the pores hydrophobic, thereby preventing water necessary for dispersion from entering. This is thought to be because dispersion stability is dramatically improved compared to the hindering component (a) alone. Various types of coal are used in the present invention, including anthracite, bituminous coal, sub-bituminous coal, and lignite, which are pulverized and used. The particle size of this coal powder may be any particle size that allows direct combustion in the boiler, but the typical particle size currently used in thermal power plants for this purpose is 200 mesh with a pass rate of 70 to 90%.
particle size. The mixing order of coal, dispersion stabilizer, and water may be arbitrary, but the dispersion stabilizer may be dissolved or dispersed in water, and then coal may be added thereto to prepare the mixture using a suitable mixing device or crushing device. The dispersion stabilizer of the present invention can be used in combination with other anionic surfactants or nonionic surfactants. For example, in JP-A-54-20090, in which the present inventors have already invented the dispersion stabilizer for water slurry of the present invention,
56-21636, 56-57889, 56-57890, 56
-57891, 57-19024, 57-126891, 57-
If used in combination with a dispersion stabilizer for water slurry of coal powder described in Japanese Patent No. 133192, lignin sulfonate, and other lignin derivatives, even better dispersion ability can be obtained. In addition, other surfactants such as anine surfactants such as fatty acids, alkyl sulfate ester salts, alkylbenzene sulfonates, dialkyl sulfosuccinate ester salts, polyoxyethylene alkyl ethers, oxyethylene sorbitan fatty acid esters, glycerin fatty acid esters, etc. Even when the dispersion stabilizer of the present invention is used in combination with a nonionic surfactant, etc., excellent dispersibility can be obtained. Furthermore, by adding fatty acids such as oleic acid, phosphoric acid esters such as tributyl phosphate, or metal soaps such as aluminum stearate to the coal water slurry using the dispersion stabilizer of the present invention, inclusion of air bubbles can be prevented. It can be made into a less stable slurry. 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 in this case include a method that applies the principle of flotation and uses a scavenger and a foaming agent to keep the ash in water and adsorb the coal to the foam, and a method that collects coal by adsorbing it to the foam. An underwater granulation method in which an emulsion is added and stirred and coal is selectively granulated and recovered (for example, Japanese Patent Application Laid-Open No. 52-37901
issue) is attracting attention. The dispersion stabilizer of the present invention exhibits extremely good dispersion stability even in coal slurry deashed by such a method. Furthermore, in this case, it is possible that hydrocarbon oil (for example, diesel oil, heavy oil A, heavy oil B, heavy oil C, etc.) may be mixed into the coal slurry, but the dispersion stabilizer of the present invention is suitable for systems where such hydrocarbon oil coexists. However, it shows excellent performance without losing its dispersion effect. The water slurry of coal powder obtained by adding the dispersion stabilizer of the present invention has good fluidity with little increase in viscosity even at high concentrations, and has good dispersion stability without forming hard cakes even after long-term storage. Pipeline transportation, tank storage, and boiler direct combustion are possible. In addition, the aqueous slurry of coal powder obtained using the dispersion stabilizer of the present invention has fewer bubbles during production, less increase in volume of the slurry, and can be made to have good properties by preventing thickening due to air bubbles. . EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples. Example (1) Preparation method of deashed coal Manufacturing method of deashed coal by underwater granulation method 200 mesh 80% pass Preasol charcoal ^*1 with the following composition 428g (contains 7.0% water, so as pure content) 400g) in water at room temperature and stirred to obtain a coal-water slurry. 20 g of heavy oil A was added to this mixture, and the mixture was stirred at room temperature for 30 minutes at 1000 rpm using a Labo Disper (manufactured by Tokushu Kika Kogyo Co., Ltd.) to decalcify and granulate the mixture. The mixture thus obtained was passed through an 8-mesh sieve to remove the 105
Deashed and dehydrated granules (referred to as deashed charcoal A) were obtained by drying at ℃. The residual ash content of this product was 4.8 wt% (based on coal). Similar to the method for producing deashed coal using the flotation method, 428 g of Preasol coal ^*1 is dispersed in water at room temperature, and placed in a F-W type flotation machine with 0.5 g of pine oil for flotation. 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 is
It was 4.0wt% (coal standard). *1 Preasol charcoal Calorific value 6720Kcal/Kg (JIS M8814) Ash 7.1% (JIS M8812) Moisture 7.0% (JIS M8811) Fixed carbon 59.7% (JIS M8812)

[Table] (2) Preparation of water slurry and evaluation of fluidity Table 2 No. 4 compound 1.85 g, Table 3 No. 3 compound 0.19 g
Disperse 0.19 g of Compound No. 1 in Table 4 in 100 g of water, and add 397.8 g of Preasol charcoal No. 1 in Table 1 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. When the viscosity was measured at 25°C, it was 310 centipoise, indicating good fluidity. In addition, various combinations of the test coal shown in Table 1, the polyether compound or its derivative (a component) shown in Table 2, the (b) component shown in Table 3, and the (c) component shown in Table 4 were conducted under the same conditions. The results, including other examples and comparative examples, are shown in Table 5.
and 6. Low viscosity indicates good fluidity. (3) Evaluation of the stability of water slurry The stability of the slurry is determined by allowing the slurry to stand for 30 and 60 days after production, and then gently inserting a stainless steel rod with a diameter of 5 mm (weight 50 g) into the slurry and observing its sedimentation state. Observed. The slurry prepared in (2) had good stability and showed almost no compaction even after 60 days. The results, including other Examples and Comparative Examples, are shown in Tables 5 and 6.

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Claims (1)

[Scope of Claims] 1a A polyamine compound to which an alkylene oxide containing ethylene oxide as an essential component is added, and the total weight of the polyoxyethylene chain portion is 40 to 95% by weight of the total molecular weight, and the molecular weight is 5000 to 200000. A dispersion stabilizer for an aqueous slurry of coal powder, comprising as an active ingredient one or more nitrogen-containing compounds selected from a polyether compound or a derivative thereof, and b) an amine compound or an amide compound. 2. The dispersion stabilizer for a water slurry of coal powder according to claim 1, wherein the polyether compound is a block-like or partially block-like adduct of ethylene oxide and an alkylene oxide other than ethylene oxide. 3. The dispersion stabilizer for water slurry of coal powder according to claim 1 or 2, wherein the alkylene oxides in the polyether compound are ethylene oxide and propylene oxide. 4. The dispersion stabilizer for water slurry of coal powder according to claim 1, 2 or 3, wherein the polyamine compound is polyalkylene polyamine or polyethyleneimine. 5. According to any one of claims 1 to 4, the derivative of the polyether compound is a compound obtained by reacting a polyether compound with a fatty acid or a compound obtained by cationizing the nitrogen atom of the polyether compound. Dispersion stabilizer for water slurry of coal powder as described. 6a A polyether compound or The derivative thereof is characterized by containing as an active ingredient one or more nitrogen-containing compounds selected from camine compounds or amide compounds, and c one or more aliphatic alcohols, sorbitan fatty acid esters, or silicone compounds. Dispersion stabilizer for water slurry of coal powder.