JPS62232494A - High-concentration coal/water slurry composition - Google Patents

Abstract

PURPOSE:To obtain a high-concn. coal/water slurry compsn. having an increased coal concn., having a low viscosity and an excellent flowability and permitting ready transportation and combustion as in the case of heavy fuel oil, by suspending fine grains of coal in an aq. medium in the presence of a particular compd. CONSTITUTION:Polyethylene glycol diamine having an MW of 148-4,000 is addition-polymerized with ethylene oxide and a 3C or higher alkylene oxide (e.g., propylene oxide), thereby obtaining a compd. having an MW of 5,000-100,000 and comprising a plurality of polyalkyl ether chains, which compd. has a polyoxyethylene group content of 40-90wt%, pref. 70-90wt%, based on the whole amt. of the alkylene oxide and always has a polyoxyethylene group at its terminal. Then, fine grains of coal having such a grain size that at least about 70wt% grains pass through a 200-mesh (74mum) sieve are suspended, in an amt. of 60wt% or more in an aq. medium contg. 0.1-1.0wt%, based on the coal, of the compd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a coal/water slurry composition that has low viscosity and excellent fluidity despite having a high coal concentration.

[Conventional technology]

In recent years, the development of the use of coal as an energy alternative to oil has become a worldwide trend, as oil as an energy source has concerns about its long-term supply stability and is considered to be more economical than oil even when handling costs are included. is being promoted. The main problems in handling coal are that it is solid, making it difficult to transport by pipeline or storing in tanks, and that it contains ash. ), coal/water slurry (CWM or CwS), coal/methanol slurry (Methacoal), and other slurry compositions have been investigated. As a medium for these slurry compositions, it is practical to use water, which is inexpensive and easy to supply, and is the focus of research.

Although coal has hydrophilic groups such as hydroxyl and carboxylic acid groups in its molecules, it is hydrophobic as a whole and does not wet well with water when a large amount of fine coal powder is mixed with water. Therefore, the slurry is not uniformly distributed and has extremely poor fluidity.Currently, only a slurry with a coal concentration of about 60% at maximum can be obtained. In order for a coal/water slurry to work effectively as a fuel, it is generally desired that the coal concentration be at least 70 g, taking into consideration the latent heat of vaporization of water. In order to achieve this,
Studies have been conducted on additives that are surfactants that can maintain an appropriate particle distribution state of coal, maintain dispersion of coal by intervening between coal and water, and improve fluidity.

Conventionally, lignin sulfonate (Japanese Unexamined Patent Application Publication No. 1989-1999
7-96090, etc.), polycyclic aromatic sulfonate formalin condensates (Japanese Patent Publication No. 57-145193, etc.), or polyether compounds similar to the compounds used in the present invention (Japanese Patent Application Publication No. 57-147595, etc.). be. Although each of these additives has its own characteristics, there are problems in that a relatively large amount must be added in order to make a slurry with a coal concentration of 70 cm, and that the fluidity is insufficient and the additives tend to crumble.

[Problem that the invention seeks to solve]

There is no point in creating a highly concentrated coal/water slurry using additives if the cost of the additive increases the total cost of the slurry and eliminates the cost advantage as a petroleum substitute. Alternatively, it is required that the desired slurry can be obtained by adding a small amount.

The object of the present invention is to provide a coal/water slurry composition that meets this requirement and can be transported and burned on a par with heavy oil.

[Means for solving problems]

According to the present invention, there is provided a highly concentrated coal/water slurry composition characterized in that at least 60 parts by weight of coal is finely suspended at low viscosity in an aqueous medium in the presence of the following compounds: provided.

Compound: A compound having multiple polyalkyl ether chains obtained by addition polymerizing ethylene oxide and alkylene oxide having 3 or more carbon atoms to polyethylene glycol diamine.

In the present invention, preferably, the above compound is added to the aqueous medium as an additive in an amount of 0.1 to 1.0 weight i-
A coal/water slurry composition is provided in which 60% by weight or more of the total amount of coal is suspended in a low viscosity with a particle size of about 70 coefficient or more on a 200 mesh (74 μm) pass.

The compound used as an additive in the present invention has a molecular weight of 40 to 90% by weight, preferably 70 to 90% by weight of polyoxyethylene groups based on the total added alkylene oxide, and has a plurality of polyalkyl ether chains. is between 5,000 and 100,000,
It is obtained by converting polyethylene glycol diamine into a polyalkyl ether, and it necessarily has a polyoxyethylene group at the end.

Additives are characterized by their ionicity, type of hydrophilic group, type of hydrophobic group, bond structure between hydrophilic group and hydrophobic group, amount ratio of hydrophilic group and hydrophobic group,
Although the performance of the compound is greatly influenced by its molecular weight, etc., the compound useful in the present invention is particularly determined by the bonding structure of the hydrophilic group and the hydrophobic group, the weight ratio of the hydrophilic group and the hydrophobic group, and the balance of the molecular weight. performance.

The synthesis of the compounds useful in the present invention has a molecular weight of 148-4.
,000 polyethylene glycol diamine is subjected to addition polymerization with ethylene oxide, zolopylene oxide, butylene oxide, styrene oxide, etc. under normal conditions. The addition polymerization may be performed by block polymerization or random polymerization of these alkylene oxides, but block copolymerization is preferably employed. Ethylene oxide forms a hydrophilic group in alkylene oxide, and it is preferable to add-polymerize part or all of it to form a terminal group. During these polymerizations, if polyethylene glycol or the like is produced as an impurity by-product due to the presence of a trace amount of water, it is obvious that sufficient performance cannot be achieved, and therefore synthesis is carried out to avoid such by-products.

The coal may be deashed coal or non-deashed coal, and any type of coal can be used. Coal can be coarsely pulverized and then mixed with water containing additives to make a finely pulverized slurry in a wet pulverizer, or first pulverized in a dry pulverizer and then mixed with water containing additives to make a slurry. You may take the following method. The coal particle size in the slurry is desirably about 70 inches or more, preferably about 80 inches or more as the amount of coal passing through a 200 mesh (74 μm) sieve. In general, the finer the coal particle size, the better the ignitability during combustion, but the slurry properties tend to increase due to the increased surface area. There are also negative aspects such as agglomeration. However, such problems are rare in the composition of the present invention.

The concentration of coal used is about 60% or more in the coal/water slurry, preferably 70-75%. Water is the cheapest fluidizing medium, but it absorbs latent heat of vaporization during combustion, resulting in calorie loss. Furthermore, if the amount increases, it may cause the fire to go out, so it is desirable to keep the amount of water as small as possible. From this point of view, a coal concentration of 70% or more is generally desired, and the present invention achieves this concentration while still providing a slurry of low viscosity. The low viscosity means that it is not only easy to transport, but also allows for spray combustion with conventional combustion caps.

Note that the coal/water slurry composition of the present invention includes deaeration,
It is also possible to add chemicals for the purpose of rust prevention, antiseptic, antifreeze, and stability improvement.

〔Example〕

Next, the present invention will be further explained by examples. All parts and parts in tables and examples are based on weight unless otherwise specified.

Example 1 Pacific coal (volatile content 42.3%, ash content 14.9%, total So
, 19%) in a hammer mill for 2,300 r, p,
m.

The powder was pulverized at a rotation speed of 200 mesh, 50 mesh, and an average particle size of 70 μm.

Next, the additives of the present invention were added in the formulation shown in Table 1 in a total amount of 0.
．． After dissolving 7 parts in 60 parts of water, 140 parts of the above coarse coal particles were added, and after thorough mixing in a kneader, the mixture was heated to 6 O in a ball mill.
Coal with good fluidity was wet-pulverized for 2 hours at r, p, m.
200 parts of water slurry was obtained.

Comparative examples of additives include sodium ligninsulfonate, sodium naphthalenesulfonate, narmaline condensate,
or polyethylene glycol (molecular weight 20,000)
Table 1 shows the results obtained by adding 1.4 parts of each of these.

Note that the symbols in the table are described after Table 2.

The physical property values in the table were measured using the methods described below.

Coal/water slurry made with 200 mesh pasties! j-3,! i' with water 5
Dilute it to 0 times, pour it onto a sieve with a minimum of 200 mesh, wash it with 11 water after starting shaking, dry weigh the coal on the sieve, and calculate (shaking time 10 minutes).

Measuring device: Sieve shaker VSS-50 (manufactured by Tsutsui Rikagaku Kikai) Pour 3d of the prepared coal/water slurry into a cup and EL
The viscosity was measured after 3 minutes using a D-8Ti rotor. Rotation speed: 2 Or, p, m, (7s@e-'), measurement temperature: 30°C.

Measurement material = E-type rotational viscometer (manufactured by Tokyo Keiki) Static stability Approximately 200 mJ of the prepared coal/water slurry was placed in a graduated cylinder and left to stand, and the state after one week was observed by penetrating the cylinder with a rod.

Example 2 South African coal (volatile content 33.3%, ash content 9.6%, total S
0.6%) was ground with a fine grinding hammer mill, and
A mesh pass of 78% was obtained.

Next, the additives of the present invention were added in a total amount of 0 in the formulation shown in Table 2.
．． After dissolving 7 parts in 60 parts of water, add 140 parts of the above fine coal powder, and mix with an autohomogen mixer (manufactured by Tokushu Kika) to 4.00 parts.
Mixed for 5 minutes at Or, p, m, coal with good fluidity/
Water sla! J-200 parts were obtained.

Physical property values were measured by the method shown in Example 1.

Similarly, when preparing by dissolving 0.75 parts or 1.05 parts of the total amount of additives in 50 parts of water and then adding 150 parts of the above coal powder, streak IJ- with good fluidity was obtained. .

As comparative examples of additives, the results were shown in which 1.4 parts of each of the additives listed in Table 1 were added.

Margin below

Claims (1)

[Claims] 1. A highly concentrated coal/water slurry composition, characterized in that at least 60% by weight of coal is finely suspended with low viscosity in an aqueous medium in the presence of the following compound: . Compound: A compound having multiple polyalkyl ether chains obtained by addition polymerizing ethylene oxide and alkylene oxide having 3 or more carbon atoms to polyethylene glycol diamine. 2. The compound contains 40 to 90% by weight, preferably 70 to 90% by weight of polyoxyethylene groups based on the total alkylene oxide added to the molecule, and necessarily has a polyoxyethylene group at the end. , and 5,000 to 10
A composition according to claim 1 having a molecular weight of 0,000. 3. The particle size of the coal constituting the composition is 200 mesh (
74 μm) pass approximately 70% or more
The composition according to item 1 or 2. 4. The composition according to any one of claims 1 to 3, which contains 0.1 to 1.0% by weight of the compound based on coal.