JPH0718273A - Method and apparatus for producing high-concentration coal-water paste - Google Patents

Abstract

PURPOSE:To improve the flowability of the paste to make it pumpable. CONSTITUTION:The method comprises the step of crushing coal to obtain a crushed coal contg. 10-100wt.% particles with particle sizes of 6mm or lower, the step of pulverizing coal in wet to obtain a coal-water slurry contg. 20-95wt.% particles with particle sizes of 200mesh or lower and having a coal concn. of 30-80wt.%, and the step of mixing the crushed coal, the slurry, and a desulfurizing agent to provide the paste with a coal concn. of 60-90wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a high-concentration coal / water paste as a fuel which can be pumped.

[0002]

2. Description of the Related Art Combustion apparatus, for example, pressurized fluidized bed combustion (P
pressed Fluidized Bed
Combustion, PFBC) Boiler fuel supply methods include a dry method and a wet method. The dry method is a method of pressurizing pulverized coal with a lock hopper and transporting it by air, while the wet method is a method of adding water to coal to form a paste, pressurizing it with a slurry pump and spraying it into the fluidized bed. is there.
Japanese Patent Laid-Open No. 62-155433 discloses crushed coal,
A method and apparatus for producing a fuel for a pressurized fluidized bed combustion (PFBC) boiler by mixing a desulfurizing agent and water into a paste is described.

[0003]

Currently, in the PFBC boiler, the above-mentioned lock hopper method is the mainstream as a coal supply method, but there are problems in valve durability and reliability, and there is a scale-up of the lock hopper. However, it has a problem that it cannot be used as a supply device on a practical scale.

Further, the conventional coal / water paste has a problem that the coal concentration cannot be increased because it has poor fluidity. On the other hand, we investigated the conventional technology, but when the paste is made, a certain amount of fine coal / water slurry is added to adjust the particle size distribution to improve the fluidity of the paste and increase the coal concentration, By adding a small amount of anionic or nonionic dispersant to the slurry and further reducing the viscosity of the paste, it is possible to increase the concentration and reduce the load on the pump used for supplying to the boiler. No production method or device enabling the production is found.

The present invention has been made to solve the above problems, and an object of the present invention is to mix coarse coal, fine coal / water slurry and a desulfurizing agent to adjust the particle size distribution, and
It is an object of the present invention to provide a method and an apparatus for producing a high-concentration coal / water paste that can be pumped by adding an additive as needed.

[0006]

In order to achieve the above object, the method for producing a high-concentration coal / water paste of the present invention will be described with reference to FIG. A step of crushing to obtain coarsely crushed coal having a particle size of 10 to 100 wt% with a particle size of 6 mm or less;
20 to 95 wt% below mesh, coal concentration 30 to 80 wt%
(C) kneading the coarsely crushed coal, the coal / water slurry, and a desulfurizing agent to prepare a high-concentration coal / water paste having a coal concentration of 60 to 90 wt%. It is characterized by that. As a desulfurizing agent,
Limestone, dolomite, quick lime, slaked lime, etc. are used.

As the coal to be wet-milled, coarsely-pulverized coal is usually used. However, it is also possible to use agglomerated coal, as indicated by the dashed line. As the coarsely pulverized coal, the coarsely pulverized carbon from the coarse pulverization step or the coarse pulverized carbon from another coarse pulverization step (not shown) is used as indicated by a broken line. It is preferable that the coal to be wet-milled is a part of the coarsely pulverized coal from step (a), and the coarsely pulverized coal used in step (c) is the rest of the coarsely pulverized coal from step (a). Further, as the coarsely pulverized coal supplied to the kneading step, it is preferable to use the coarsely pulverized carbon from the coarse pulverization step as described above, but as shown by the broken line, the coarse pulverized carbon from other coarse pulverization steps (not shown) is used. You can use crushed charcoal.

Although the desulfurizing agent is added in the kneading step as shown in FIG. 1, it may be added in the coarse pulverizing step as shown in FIG. Also, the desulfurizing agent may be added in both of these steps. Although not shown, it is also possible to add them in a wet grinding process. The desulfurizing agent is preferably pulverized in advance to a particle size of 3 mm or less and 1 to 99 wt%. If the particle size is coarser than this, there is a problem that the desulfurization rate becomes low when the high-concentration coal / water paste is burned.

In the high-concentration coal / water paste, the ratio of the coarsely pulverized coal and the finely pulverized coal is 60/40 by weight.
It is preferably 95/5. If the coarsely pulverized coal is less than 60 wt%, when burning high-concentration coal / water paste, fine powder is discharged from the fluidized-bed boiler together with gas without burning, and black ash with a large amount of unburned content is generated. ,
On the other hand, if the coarsely pulverized coal exceeds 95 wt%, there is a problem that the amount of water necessary for imparting fluidity increases and the coal concentration of the high-concentration coal / water paste decreases.

Further, as shown in FIGS. 3 and 4, it is preferable to add the additive in a wet pulverizing step and / or a kneading step. Although not shown, it is also possible to add an additive in the coarse grinding step. In this case, an anionic dispersant or / and a nonionic dispersant is used as an additive,
It is preferable to add 0.01 to 0.9 wt% of this dispersant to the total coal. Dispersant is 0.01 for all coal
If it is less than wt%, the effect of the dispersant does not appear, and there is a problem that the fluidity of the high-concentration coal / water paste decreases.
On the other hand, if it exceeds 0.9 wt%, the cost of the dispersant increases and the economical efficiency of the high-concentration coal / water paste is lost.

As the dispersant, it is preferable to use sodium lignin sulfonate, formalin condensate of sodium naphthalene sulfonate, sodium polystyrene sulfonate, sodium poly (meth) acrylate, or polyethylene glycol nonylphenyl ether formalin condensate. Among the above dispersants, the polyethylene glycol nonyl phenyl ether formalin condensate is nonionic and the others are anionic.

As shown in FIG. 5, the apparatus for producing high-concentration coal / water paste of the present invention is a coarse crusher 1 for coarsely crushing coal.
0 and a wet crusher 12 connected to the coarse crusher 10.
And a kneader 14 connected to the wet crusher 12 and the coarse crusher 10, and a desulfurizing agent supply means 16 connected to the kneader 14 and / or the coarse crusher 10. There is.

In FIG. 5, coal is put into a coal hopper 18 and is supplied to a coarse crusher 10 such as a hammer crusher by a quantitative feeder 20 to have a particle size of 6 mm or less 10
It is crushed to 100% by weight of coarsely crushed coal. The coarsely pulverized coal is supplied to a wet pulverizer 12 such as a wet ball mill by a quantitative feeder 24 through a distribution chute 22 and
Particle size 200 mesh or less 20-95 wt%, coal concentration 30
~ 80 wt% coal / water slurry is prepared. The remainder of the coarsely crushed coal, the coal / water slurry, and the desulfurizing agent are supplied to the kneader 14 to prepare a high-concentration coal / water paste having a coal concentration of 60 to 90 wt%.

The desulfurizing agent supplying means 16 is a desulfurizing agent hopper 26.
The desulfurizing agent supplying means 16 supplies the desulfurizing agent to the kneading machine 14 and / or the coarse crushing machine 10. The prepared high-concentration coal / water paste is once stored in the buffer tank 30 and then sent to the PFBC service tank by the piston pump 32. A plunger pump, a snake pump, a screw pump, or the like can be used instead of the piston pump.

[0015]

EXAMPLES The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to the following examples, and various modifications may be made without departing from the scope of the invention. Is possible. Example 1 The test coal was crushed with a hammer crusher to a particle size of 6 mm or less and 70 wt% to obtain crushed coal (A). On the other hand, the test coal was wet-milled with a ball mill to obtain a coal concentration of 60 wt%, 200
Finely pulverized to a mesh pass of 60 wt% to obtain a medium-concentration slurry (B). Further, the particle size of limestone was adjusted to 3 mm or less and 50 wt% to obtain limestone (C). The crushed coal (A), the medium-concentration slurry (B), and the limestone (C) were transferred to a kneader so that the proportion of pulverized coal in the medium-concentration slurry in the weight of the total coal was 20 wt% at a coal concentration of 80 wt%. 10 at 63 rpm
The mixture was kneaded for a minute to produce a coal / water paste.

Example 2 The sample coal was crushed with a hammer crusher to a particle size of 6 mm or less and 70 wt% to obtain crushed coal (A). 0.05% by weight of sodium polystyrene sulfonate was added as an additive, and the test coal was wet pulverized with a ball mill to obtain a medium concentration slurry (B) having a coal concentration of 60% by weight and 200 mesh pass of 60% by weight. The particle size of limestone was adjusted to 3 mm or less and 50 wt% to obtain limestone (C). Crushed coal (A), medium-concentration slurry (B) and limestone (C) coal concentration 83 wt%
Then, transfer to a kneading machine so that the ratio of pulverized coal in the medium-concentration slurry to the weight of all coal becomes 20 wt%, and at 1 rpm at 63 rpm.
The mixture was kneaded for 0 minutes to produce a coal / water paste.

Comparative Example 1 The test coal was crushed with a hammer crusher to a particle size of 6 mm or less and 70 wt% to obtain crushed coal (A). The particle size of limestone was adjusted to 3 mm or less and 50 wt% to obtain limestone (C). Crushed coal (A)
And limestone (C) were transferred to a kneader so that the coal concentration would be 80 wt%, and kneaded at 63 rpm for 10 minutes.

In Examples 1 and 2, it was possible to obtain a coal / water paste having a high concentration and fluidity, but in the production method of Comparative Example 1, a fluid paste-like coal / water mixture was obtained. Was not obtained. The fluidity and stability of the paste obtained in Example 1, the paste obtained in Example 2 and the paste obtained in Comparative Example 1 were measured. The results are shown in Table 1. By carrying out Example 1 according to the present invention, it was possible to manufacture a high-concentration coal / water paste which showed a viscosity of 11,000 cp at a high coal concentration of 80 wt% and was sufficiently transportable by a piston pump. Example 2
By carrying out the procedure, it is possible to produce a coal water paste having a coal concentration of 83 wt% and a viscosity of 7,000 cp, which is a higher concentration than that of Example 1, but has a lower viscosity, a higher fluidity and an excellent stability. It was

[0019]

[Table 1]

In the examples and comparative examples, the viscosity of the paste is measured according to JIS K 7117 "Method for testing viscosity of liquid resin by a rotational viscometer", and the flow value is measured according to JIS R 5201 "Physical properties of cement". "Test method", and the slump value is measured according to JIS A
1173 “Polymer cement mortar slump test method” is performed, and the breathing rate is measured according to JIS.
A 1123 "Breathing test method for concrete"
It was carried out according to.

[0021]

Since the present invention is configured as described above, it has the following effects. (1) When coal, water and a desulfurizing agent are kneaded to form a paste, finely pulverized coal / water slurry is added and kneaded to adjust the particle size distribution and improve the fluidity of the paste to increase the coal concentration. It is possible to produce a highly concentrated coal / water paste that can be pumped. (2) When a dispersant is added to the kneading step or / and the step upstream thereof, the paste can be further reduced in viscosity, the paste can be made more highly concentrated, and a pump for supplying to a combustion device such as a boiler. It is possible to reduce the load.

[Brief description of drawings]

FIG. 1 is a process drawing showing an example of a method for producing a high-concentration coal / water paste according to the present invention.

FIG. 2 is a process drawing showing another embodiment of the method of the present invention.

FIG. 3 is a process drawing showing another embodiment of the method of the present invention.

FIG. 4 is a process drawing showing still another embodiment of the method of the present invention.

FIG. 5 is a system diagram showing an example of an apparatus for producing a high-concentration coal / water paste according to the present invention.

[Explanation of symbols]

 10 Coarse crusher 12 Wet crusher 14 Kneader 16 Desulfurizing agent supply means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Takao 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries Ltd. Akashi factory (72) Inventor Yoshitaka Imori 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy industry Akashi factory

Claims (10)

[Claims] 1. A step of: (a) coarsely crushing coal to obtain coarsely crushed coal having a particle size of 6 mm or less and a particle size of 10 to 100 wt%, (b)
Coal is wet-milled to a particle size of 200 mesh or less 20-9
A step of preparing a coal / water slurry having 5 wt% and a coal concentration of 30 to 80 wt%; A method for producing a high-concentration coal / water paste, comprising the step of preparing a water paste. 2. The method for producing a high-concentration coal / water paste according to claim 1, wherein the coal to be wet-ground is coarsely-ground coal. 3. The coal to be wet-milled is a part of the coarsely pulverized coal from step (a), and the coarsely pulverized coal used in step (c) is the rest of the coarsely pulverized coal from step (a). A method for producing a high-concentration coal / water paste characterized by: 4. The method for producing a high-concentration coal / water paste according to claim 1, 2 or 3, wherein the desulfurizing agent is added in the kneading step and / or the coarse crushing step. 5. The method for producing a high-concentration coal / water paste according to claim 1, wherein the desulfurizing agent is previously pulverized to have a particle size of 3 mm or less and 1 to 99 wt%. 6. A high-concentration coal / water paste having a weight ratio of coarsely ground coal to finely ground coal of 60/40 to 95 /.
5. The method for producing a high-concentration coal / water paste according to claim 1, wherein the method is 5. 7. The method for producing a high-concentration coal / water paste according to claim 1, wherein the additive is added in a wet crushing step and / or a kneading step. 8. An anionic dispersant and / or a nonionic dispersant is used as an additive, and the dispersant is added in an amount of 0.01 to 0.9 wt% with respect to the total coal. A method for producing the high-concentration coal / water paste described. 9. A dispersant comprising sodium lignin sulfonate, formalin condensate of sodium naphthalene sulfonate, sodium polystyrene sulfonate, sodium poly (meth) acrylate, polyethylene glycol nonyl phenyl ether formalin condensate. The method for producing a high-concentration coal / water paste according to claim 8. 10. A coarse crusher (10) for coarsely crushing coal.
And a wet crusher (1 connected to this coarse crusher (10)
2), the wet crusher (12) and the coarse crusher (1)
0) and the kneading machine (1)
4) or / and a desulfurizing agent supply means (16) connected to the coarse crusher (10), the apparatus for producing a high-concentration coal / water paste.