JPH0247520B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to an additive for coal-water slurry for stably dispersing coal powder in water at a high concentration. Due to its solid form, coal had long been dethroned as a fuel by petroleum, but coal was reconsidered in the wake of oil shocks, and coal became a fuel as exemplified by coal-oil mixed fuel (COM). Many attempts have been made to treat coal as a fluid by turning it into powder and mixing it with a medium. However, in the case of coal-oil mixed fuel, it is impossible to avoid the disadvantage that about half of the fuel is oil, and there is a desire to develop another slurry fuel. In recent years, attempts have been made to use water as a medium to create slurry as a fluid in which coal is dispersed at a high concentration, making it suitable for transportation by pipeline or oil tanker, and furthermore, attempting to use it as an alternative fuel to oil in various boilers. Attempts are being made. In the case of this slurry, since the medium is water, it is preferable that the slurry has the following properties. That is, it must have a high coal concentration and low viscosity, and have excellent long-term stability without causing coal powder agglomeration or sedimentation. It is also desired that the slurry be able to maintain stability even when mechanical shearing force is applied. By the way, conventionally, in order to modify the characteristics of coal-water slurry, rust preventives, antioxidants,
It is already known to add various additives such as dispersants. However, among these known additives, there are hardly any that give very good results on coal concentration or viscosity and satisfy both this property and the stability of the slurry. for example,
Phosphate esters, various amines, alkylene oxides, alkylphenols, naphthols, and other acidic phosphates disclosed in U.S. Patent No. 2346151, Japanese Patent Publication No. 55-45600, and Japanese Patent Application Laid-open No. 54-16511, etc. Additives such as salts of polycarboxylic acids such as polymethacrylic acid have poor viscosity-lowering properties and are difficult to obtain highly concentrated slurries. Also, JP-A No. 52-71506 and JP-A No. 53-581
The lignin sulfonate proposed in JP-A-56-21636, the naphthalene sulfonate and the salt of formaldehyde condensate of naphthalene sulfonic acid proposed in JP-A-56-21636 have a viscosity-lowering function compared to the above-mentioned additives. Although it contributes to the stability of the slurry to some extent, there is still room for improvement in these properties.
Moreover, it has the disadvantage that when mechanical shearing force is applied to the resulting slurry, its stability is extremely reduced.
The results were far from satisfactory for practical use. The present invention aims to provide an industrially useful additive that has an improved viscosity-reducing function compared to those proposed above and also provides good results in static stability and shear resistance stability of slurry. The gist of this is that the alkali metal salt, ammonium salt or lower amine salt of the formaldehyde condensate of a mixture of sulfonated melamine and an aromatic compound with or without a sulfonic acid group in its aromatic ring is It is an additive for coal-water slurry as an active ingredient. As described above, the additive of the present invention has a formaldehyde condensation product of a mixture of sulfonated melamine and an aromatic compound or a salt thereof as an active ingredient, and according to this additive, it has a higher concentration than the above-mentioned proposal. It has been found that a coal-water slurry having low viscosity, excellent long-term stability, and improved shear force stability can be obtained. In particular, by using the formaldehyde condensate of the above mixture or its salt, the shear resistance stability is significantly improved compared to the case of using the formaldehyde condensate of sulfonated melamine alone or its salt, and It has been found that a highly stable coal-water slurry is obtained which does not easily consolidate under forces. Slurry with excellent shear resistance stability can be manufactured overseas and transported by long-distance pipelines or ships for long periods of time before being consumed in Japan. It has extremely high practical value because the stability of the slurry can be maintained sufficiently. Note that, with the additives proposed above, it is impossible to obtain a slurry with such excellent shear force resistance stability. Formaldehyde condensate of a mixture of sulfonated melamine used in this invention and an aromatic compound with or without a sulfonic acid group in its aromatic ring (hereinafter referred to as melamine mixed condensate)
can be easily obtained by a conventionally known method. In this case, the sulfonation of the melamine or aromatic compound may be carried out at any time, for example, according to the method described in JP-A No. 56-26758,
First, melamine, formaldehyde, and sulfite or sulfamate are reacted to obtain a sulfonated melamine that has been condensed to some extent, and then an aromatic compound with or without a sulfonic acid group in the aromatic ring, formaldehyde, and concentrated sulfuric acid are added to this. In addition, a condensation reaction may be performed. The aromatic compound used here with or without a sulfonic acid group in its aromatic ring may be monocyclic or polycyclic. An aromatic compound having a sulfonic acid group can be obtained by reacting an aromatic compound not having a sulfonic acid group with a sulfonating agent such as sulfuric acid, oleum, chlorosulfonic acid, or sulfuric anhydride in a conventional manner. Specific examples of aromatic compounds include benzene, naphthalene, fluorene, anthracene, phenanthrene, pyrene, naphthacene, pentacene, coronene, hexacene, heptacene, octacene, nonacene, decacene, undecacene, dodecacene,
Examples include acenaphthene and derivatives having one or two substituents such as an amino group, a hydroxyl group, a carboxyl group, or an alkyl group having 1 to 20 carbon atoms on an aromatic ring thereof. Other aromatic compounds useful in this invention include mixtures of aromatic hydrocarbons such as creosote oil, lignin, coal tar, and petroleum decomposition products. The proportion of sulfonated melamine in the melamine mixed condensate is usually 5% by weight or more, preferably 10% by weight or more of the total amount of the condensate; if this proportion is too small, the stability of the slurry may be affected. I can't get good results on this front. On the other hand, as mentioned above, this type of melamine mixed condensate is a formaldehyde condensate of sulfonated melamine alone (hereinafter referred to as
Melamine has the characteristic of being able to further improve shear resistance stability compared to melamine (single condensate), so if you wish to take advantage of this characteristic and highly improve its practicality, the proportion of sulfonated melamine should be The upper limit is usually 95% by weight or less, preferably 90% by weight or less. In addition, in the above-mentioned condensation reaction of a melamine mixed condensate, the viscosity may increase during the condensation reaction and stirring may become difficult, but in this case, stirring may be facilitated by adding a small amount of water. In general, the longer the condensation reaction time in this operation, the higher the degree of condensation can be obtained. In the case of a melamine single condensate, the degree of condensation has a large effect on the viscosity reduction or stability of the slurry, but in the case of a melamine mixed condensate, the above tendency is not so pronounced, and the range of the applicable degree of condensation is is more widespread than the former. In the additive of the present invention, the melamine mixed condensate described above can be used as an active ingredient as is, or an alkali metal salt, ammonium salt, or lower amine salt of this condensate can be used as an active ingredient. Each of these salts can be obtained by neutralizing with a base, and by-products produced in this neutralization reaction can be removed by known liming, sodation, etc., if necessary. The above alkali metal salts include lithium salt,
Mention may be made of sodium or potassium salts. In addition, lower amine salts include methylamine, dimethylamine, trimethylamine, ethylamine,
Amines with an alkyl group having 1 to 4 carbon atoms such as diethylamine, triethylamine, propylamine, butylamine, dibutylamine, tributylamine; monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, Amines with alkanol groups having 2 to 3 carbon atoms such as N-hydroxyethylethylenediamine; ethylenediamine, diethylenediamine, triethylenetetramine, NN-
There are salts of polyalkylene polyamines such as dimethylpropylene diamine; and cyclic amines such as morpholine and piperidine. In this invention, one or more of the above-mentioned active ingredients can be selected and used as is or in a state of being included in a medium such as water, alcohol, or hydrocarbon. . Such additives may include known slurry additives such as gelling agents, rust preventives, and preservatives, if necessary. The amount added to the coal-water slurry varies depending on the characteristics of the slurry, that is, the particle size and concentration of the coal powder, or the type of active ingredient itself, but in general, the amount of active ingredient added to the slurry is 0.01 to 5% by weight. %,
Particularly preferably, the amount is 0.05 to 1.0% by weight. As the amount added increases, the viscosity lowering effect becomes greater and better results are obtained in terms of stability. However, if the amount exceeds a certain level, no further effect can be expected, which is economically disadvantageous. The addition method is arbitrary, and an appropriate method may be selected depending on whether the coal powder is obtained by dry pulverization or wet pulverization. For example, in the dry pulverization method, it is preferable to add and mix the additive of the present invention in advance into water in which the pulverized powder is to be dispersed, and then add and mix the pulverized powder thereto. On the other hand, in the wet pulverization method, it may be added in advance to the water used for wet pulverization, or it may be added during wet pulverization or after each pulverization. However, if the additive of this invention is used only by underwater pulverization or normal impeller agitation,
When it is difficult to obtain a stable slurry, it is best to mix using a stirrer with strong shearing force, such as a homogenizer or line mixer. The coal to be applied to this invention may be sub-bituminous coal, bituminous coal, anthracite coal, etc. and is not particularly limited, but coal with fewer pores is preferable. Further, this coal is pulverized by a dry pulverization method or a wet pulverization method to obtain a powder for water slurry, but the particle size of this powder is also not particularly specified. However, in order to avoid problems such as wear and blockage during pipeline transportation and burner combustion, it is usually preferable that the 200 mesh pass be 50% by weight or more, and more preferably 70% by weight or more. Next, examples of the present invention will be described in more detail. Comparative Example 1 Melamine and formaldehyde were condensed in an alkaline aqueous solution at about 75°C to form approximately trimethylol, and Na ₂ S ₂ O ₅ to
After adding NaHSO ₃ and reacting to introduce approximately one sulfonic acid group per molecule of melamine, the condensation reaction was continued by adjusting the reaction time and temperature.
Three types of melamine single condensates having different degrees of condensation were obtained. In addition, these condensates were further neutralized with a base. In this way, six types of additives for coal-water slurry shown in Table 1 below were obtained.

[Table] Comparative Example 2 Sodium salt of naphthalene sulfonic acid (Sample No.
23), Sodium salt of formaldehyde condensate of naphthalene sulfonic acid (degree of condensation 6.0) (Sample No. 24)
and sodium salt of ligninsulfonic acid (sample
No. 25) were used as additives for coal-water slurry different from those of this invention. Using each of the additives in Example 1 and Comparative Examples 1 and 2 above, a coal-water slurry was actually prepared according to Test Examples 1 and 2 below, and the viscosity of this slurry (25
°C), static stability, and the influence of shear force on stability. The industrial analysis values of Miike charcoal (produced in Japan) and Orchiad Valley charcoal (produced in the United States) used in this test are as follows.

[Table] The viscosity of the obtained coal-water slurry (25
°C) was measured using a B-type viscometer, and the static stability was examined using the method described in (1). That is, a stainless steel cylinder with a diameter of 5 cm and a height of 20 cm was provided with outlets with stoppers at positions 6 cm and 12 cm from the bottom, and the obtained coal-water slurry was poured into the cylinder to a depth of 18 cm from the bottom, and the mixture was heated at room temperature. It was left undisturbed for one week. Next, the upper layer above 12cm from the bottom of the cylinder,
It was divided into a middle layer portion of 6 to 12 cm and a lower layer portion below 6 cm, and the solid content of each layer was measured by the loss on drying method of leaving it in a dryer at 105° C. for 1 hour. In addition, stability due to shear force was determined by the following method. That is, the obtained coal-water slurry was put into a beaker 1 with a diameter of 10.5 cm and a height of 15 cm up to the 800 ml line, an impeller with a blade diameter of 2 cm was set at the 400 ml position, and the slurry was stirred at 200 rpm for 24 hours. After stopping stirring,
The impeller was removed and left as it was for 3 days. After standing still for 3 days, tilt the beaker to pour out the slurry. If all of the slurry flows out, it will remain at the bottom, but if it can be easily re-fluidized with a glass rod, etc.
Cases in which hard sediment is formed at the bottom and cannot be easily removed with a spatula are represented by ◎, 〇, and ×, respectively. In the case of ◎ and 〇, a slurry that is strong against shearing force is obtained. It was determined that Test Example 1 Miike charcoal was dry-pulverized to obtain coal powder containing 70% by weight of 200 mesh charcoal. The moisture content of this powder was 4% by weight (including adhering water). Next, 1
135.4 g of an aqueous solution in which predetermined amounts of each of the additives of Comparative Examples 1 and 2 were dissolved was placed in a beaker, and mixed using a Homomixer M type manufactured by Tokushu Kika Kogyo Co., Ltd.
While slowly stirring at ~500 rpm, gradually add 364.6 g of the above coal powder, and after the addition, increase the rotation speed of the homomixer to 5000 rpm and stir for 10 minutes to create a coal-water slurry with a solid content of 70% by weight. I got it. Next, Table 2 shows the results of Test Example 1 above.
In the table, the amount added is expressed as the proportion of the additive in the slurry. In addition, the symbol (*) in the table means that the viscosity of the slurry was so high that it was impossible to take out the slurry from the outlet of the cylinder, making it impossible to measure it. The same applies to each table below. As is clear from this table, by using the additive of Comparative Example 1, compared to the additive of Comparative Example 2, the slurry has a higher concentration and lower viscosity, and also has better stability. Although coal-water slurries with improved shear stability have been obtained, it can be seen that there is still room for improvement in terms of shear stability.

[Table] In addition, the following Table 3 shows sample No. 3 as an additive.
Table 2 shows the results when the amount added was varied, and the same results as in Table 2 were obtained in both cases.

[Table] Test Example 2 Moisture content 14% by weight, coarsely ground to a particle size of approximately 2 mm in a ball mill with a capacity of 5 (ball filling rate: 30% by volume)
Take 407 g of Orchiad Valley coal, add 93 g of an aqueous solution in which predetermined amounts of each additive of Samples No. 3 and 5 of Comparative Example 1 and each additive of Comparative Example 2 are dissolved, and stir for 30 minutes. Solid content 70 with particle size of powder 200 mesh pass 80% by weight
A coal-water slurry of % by weight was obtained. The following Table 4 shows the results of Test Example 2,
Therefore, according to the additive of Comparative Example 1, even when the type of coal powder is changed and it is applied to the wet pulverization method, it has a high concentration and low viscosity as shown in Tables 2 and 3 above. Moreover, although a coal-water slurry having excellent slurry stability and improved shear force resistance stability has been obtained, it is clear that there is still room for improvement in terms of shear force resistance stability.

【table】

[Table] Example: Put melamine, sulfite, and formalin (formaldehyde aqueous solution) into a reaction container, and adjust the pH to 10~
13. React for 1 to 5 hours at a temperature of 50 to 100℃, neutralize with sulfuric acid, then add formalin and concentrated sulfuric acid together with various aromatic compounds with or without sulfonic acid groups in the aromatic ring, and 70~
Various melamine mixed condensates were obtained by stirring at 100°C for 1 to 3 hours and then raising the temperature to 90 to 120°C to carry out a condensation reaction. In addition, this condensate was further neutralized with a base. In this way, 16 kinds of additives for coal-water slurry according to the present invention shown in Tables 5 and 6 below were obtained. In addition, in Tables 5 and 6, ( ) indicates the proportion (% by weight) of sulfonated melamine. In addition, in Table 5, sample No.
12 Coal tar is a commercially available coal tar distillation residue with a boiling point of 300℃/760mmHg and a softening point of 30℃ or higher.
For the creosote oil of sample No. 17, JIS standard No. 1 raw materials were used.

【table】

【table】

[Table] Coal-water slurry was prepared according to Test Examples 1 and 2 in the same manner as in Comparative Examples 1 and 2 using each of the additives of the above Examples, and the viscosity of this slurry (25℃ ), the influence of static stability and stability due to shear force was investigated. The following Table 7 shows the test results according to Test Example 1 when each of the additives shown in Table 5 was used. In this case, a coal-water slurry with high concentration, low viscosity, and excellent static stability can be obtained, and this slurry also maintains a high degree of stability even when shear force is applied, and has excellent shear resistance. It can be seen that the force stability is improved compared to the additive of Comparative Example 1.

Table 8 below shows the test results of Test Example 1 using samples with different contents of sulfonated melamine shown in Table 6 as additives. In either case, the same results as in Table 7 above were obtained.

[Table] Furthermore, the following Table 9 shows the test results according to Test Example 2 when using the additives of Sample Nos. 8, 11, 13, 14, and 21 in Tables 5 and 6. As can be seen from this table, when the additive of the present invention is used, it is possible to achieve high concentration, low viscosity, and static stability, as in Tables 7 and 8 above. In addition to obtaining an excellent coal-water slurry, this slurry maintains its stability to a high degree even when subjected to shearing force, and the shearing force resistance stability is improved by one level compared to Comparative Example 1.

【table】

Claims (1)

[Claims] 1 Coal-water whose active ingredient is a formaldehyde condensate of a mixture of sulfonated melamine and an aromatic compound with or without a sulfonic acid group in its aromatic ring, or an alkali metal salt, ammonium salt, or lower amine salt of this condensate. Additive for slurry.