JPH11237032A - Manufacture of coal-water paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the adjustment of moisture with a kneader, even in the case of making use of such coal that the moisture is over 10 wt.%. SOLUTION: In the manufacture of coal-water paste, which manufactures coal-water paste (hereinafter, referred to CWP) 21 by mixing raw coal 1 water 11 while crushing a part of the pulverized coal 19 with a pulverizer 5 after crushing of the raw coal 1 so as to manufacture powder slurry 20, and further, mixing the residual crushed coal 19, a lime stone 22, powder slurry 20, and water 11 with a kneader 6, the viscosity of the CPW 21 is managed by detecting the viscosity of the CWP 21 at the outlet of a kneader 6, and lowering the viscosity of the CWP 21 and also, injecting an interface activator 17 into a pulverizer 5 thereby raising the concentration of the coal of the powder slurry 20 within the pluverizer 5 and performing fine crushing, when the viscosity of the CWP 21 drops, and adjusting the quantity of water to be supplied to the kneader 6 after the viscosity of the CWP 21 at the outlet of the kneader 6 goes up.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to combustion of a solid fuel such as coal in a pressurized fluidized bed, driving a steam turbine by generated steam, and further driving a gas turbine by high-pressure, high-temperature combustion gas. The present invention relates to a combustion furnace for a pressurized fluidized-bed boiler combined cycle power plant that obtains electric power with high efficiency, and more particularly to a method for producing a mixture of coal and water supplied to the combustion furnace.

[0002]

BACKGROUND OF THE INVENTION Pressurized fluidized bed boilers are capable of selling energy from the steam generated and the high pressure combustion gases. However, one of the issues is to continuously and stably supply solid coal particles into a combustion furnace in a pressurized state. Conventionally, as a method of supplying coal to a fluidized bed combustion furnace, a paste-like fluid (hereinafter, referred to as CWP) obtained by mixing coal particles and water.
There is known a wet supply system in which the CWP is pressurized and pressure-fed by a pump and supplied from a spray nozzle (for example, JP-A-62-155433). This wet supply method does not require pretreatment such as drying as compared with a dry supply method, for example, a method in which the pressure is increased by a lock hopper and then pneumatic transport is performed.

[0003] As shown in FIG. 8, conventionally, raw coal 1 is supplied to a crusher 3 by a raw coal conveyor 2 and a weight average diameter of 1-2 mm.
Crush to become. Here, a method for calculating the weight average diameter will be described. In the particle size analysis by sieving, the relationship between the opening of the sieve as shown in FIG. 9 and the weight of the particles passing through the sieve (hereinafter referred to as the cumulative weight under the sieve) is drawn on a dry coal basis. At this time, the opening of the sieve corresponds to the maximum value of the particle diameter passing through the sieve. From this relationship, the cumulative weight ratio under the sieve (= 100 × (cumulative weight under the sieve) / (crushed coal weight))
Is 50% (value of sieve opening, FIG. 9).
F) is the weight average diameter.

A part of the crushed coal obtained by crushing the raw coal 1 by the crusher 3 is put into the pulverizer 5 via the crushed coal hopper 4, and is weight-averaged together with the water 11 sent by the water pump 16. Coal concentration 50 so that diameter becomes 0.03-0.07mm
% Or less, and the fine powder slurry 20 is produced.
The kneading machine 6 adjusts the water injection amount of the manufactured fine powder slurry 20, the crushed coal 19 and the limestone 22 so as to have a predetermined viscosity.
To produce CWP21. This CWP is CW
After being stored in the tank 7 while being stirred by the P stirrer 10, it is pumped to the furnace 9 by the CWP pump 8. The viscosity of the CWP is adjusted with moisture so as not to cause clogging in the pipe, and water is injected by the kneader 6 and mixed so that the viscosity at 100 rpm in the pin type viscometer 23 becomes about 10 Pa · s. ing. At this time, the water content of CWP varies depending on the type of coal, but is about 20 to 30% by weight.

The viscosity of CWP is 5 to 15 with a pin type viscometer.
Pa · s, preferably 10 Pa · s. If the viscosity is higher than this, CWP tends to be clogged in the pipe, and if the viscosity is low, coal and water are easily separated.

[0006] Here, lines A and B shown in FIG. 3 indicate that particles having a particle size of 75 μm or less are added to the fine powder slurry pulverized by the pulverizer 5.
In other words, it indicates what percentage of the particles in the fine powder slurry are passed through the sieve having an opening of 75 μm, and if the ratio is in the range of 60 to 70%, it indicates that it is within the allowable range. ing. 50% coal concentration in the fine grinding machine 5
When the pulverization is performed as described above, as shown by the line A in FIG. 3, the viscosity of the fine powder slurry in the pulverizer 5 increases, the coal particle diameter becomes coarse, and the pulverization ability decreases, so that it is difficult to adjust the particle diameter. Therefore, pulverization is performed at a coal concentration of 50% or less during pulverization.

The fine powder slurry 20 and the crushed coal 19 in the kneader 6
As shown in FIG. 4C, the mixing ratio of the fine powder slurry is 20 to 25 wt% based on dry coal. If the amount is outside this range, the water content for making the viscosity 10 Pa · s cannot be reduced. If it is 20 wt% or less, coal and water are easily separated, and if it is 25 wt% or more, CWP is likely to have high viscosity. That is, it is preferable to mix a fine powder having a particle size of 60 to 70% of 75 μm or less with a content of 20 to 25% of the total CWP coal particles because the water content is the lowest and the combustibility is good, and there is almost no separation between water and coal. Is also an excellent optimal CWP.

[0008]

The amount of water contained in the raw coal 1 varies depending on the type of coal, the environment of the coal yard, the weather, and the like. Usually, it is about 9% by weight, but if raw coal is left in a high humidity state, it may become about 14% by weight. When the mixing ratio of coal and water in the pulverizer 5 and the kneader 6 in FIG. 8 is manufactured according to the conventional technique, the viscosity is 5 to 1 as shown by the dotted line in FIG.
Kneader 6 for making water to 5Pa · s (see Fig. 5)
The amount of water injected into the coal becomes 14 wt.
%, Water cannot be added by the kneader 6. Here, the water injection ratio% in the kneader in FIG. 6 is the water injection ratio in the kneader = ｛(water addition amount in the kneader) / (total C
(WP amount)｝ × 100 (total CWP amount is CWP weight including coal).

At the same time, if the water is not reduced by the pulverizer, the water does not become water for adjusting the viscosity of CWP21 to 5 to 15 Pa · s. However, as described above, when the pulverization is performed by setting the coal concentration in the pulverizer to 50% by weight or more, the pulverization ability is reduced. This is a problem.

An object of the present invention is to detect that the viscosity at the outlet of the kneading machine has decreased because the water is adjusted only by the kneading machine even when using raw coal having a water content of more than 10 wt%. The purpose is to reduce the amount of water in the pulverizer so as to facilitate the adjustment of water in the kneader.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention reduces the CWP viscosity at the kneader outlet when controlling the CWP properties at the kneader outlet and controlling the water injection amount of the kneader. That is, the amount of water supplied to the pulverizer is reduced. For this purpose, a surfactant is injected into the pulverizer together with water to reduce the viscosity of the pulverulent slurry in the pulverizer. Is to manufacture.

[0012] According to this method, the water content of the raw coal is directly controlled even if the kneader cannot adjust the viscosity of the raw coal to an easily transportable CWP because the water content of the raw coal exceeds 10 wt%. C without any properties kept in the required range
WP can be manufactured.

A first means of the present invention to achieve the above object is to crush raw coal, mix a portion of the crushed coal with water while crushing the crushed coal with a pulverizer to produce a fine powder slurry, In a method for producing a coal / water paste (hereinafter referred to as CWP) by mixing the remaining crushed coal, limestone, the fine powder slurry and water with a kneader, the viscosity of CWP at the kneader outlet is determined. Detecting and adjusting the coal concentration of the fine powder slurry in the fine crusher by the amount of water supplied to the fine crusher.

A second means of the present invention for achieving the above object is the above-mentioned first means, wherein the viscosity of CWP at the outlet of the kneader is detected and the surfactant injected into the fine powder slurry in the fine pulverizer is used. Is characterized by adjusting the amount of

[0015] A third means of the present invention for achieving the above object is that, in the first means, a decrease in the amount of water injected into the kneader controlled by using the CWP viscosity at the kneader outlet as an input is detected. And adjusting the amount of water supplied to the pulverizer.

A fourth means of the present invention for achieving the above object is that, in the third means, a surfactant is added to the fine slurry in the fine pulverizer by detecting a decrease in the amount of water injected into the kneader. It is characterized in that the amount to be injected is adjusted.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. The illustrated CWP manufacturing apparatus includes a raw coal conveyor 2 for transporting raw coal 1, a crusher 3 for crushing the raw coal 1 conveyed on the raw coal conveyor 2 to a weight average diameter of 1 to 2 mm, and a crusher 3 for crushing. A plurality of crushed coal hoppers 4 for storing the generated crushed coal 19; an additive tank 12 having an additive stirrer 14 for storing a surfactant 17;
Pump 15 which is disposed with the suction side connected thereto and pressurizes and discharges the surfactant 17, an additive amount adjusting valve 24 interposed in the discharge pipe 29 of the additive pump 15, and water from the water source. A water pump 16 for sucking and discharging 11, a fine-pulverizer-side water amount adjusting valve 26 interposed in a first pipe 27 connected to the discharge side of the water pump 16, and fine pulverization of the first pipe A second pipe 28 branched and provided upstream of the machine-side water amount adjustment valve 26 and having a kneader-side water amount adjustment valve 25 interposed therebetween, one of the plurality of crushed coal hoppers 4, and a discharge-side pipe 29. And a pulverizer 5 connected to the downstream end of the first pipe 27
And a kneader connected to the other one of the plurality of crushed coal hoppers 4, the outlet side of the kneader 5, the downstream end of the second pipe 28, and the storage tank of the limestone 22. 6 and a pipe 30 arranged below the outlet side of the kneader 6
, A pin type viscometer 23 interposed in the pipe 30, and a CWP stirrer 1 installed in the tank 7 and stirring the CWP inside the tank 7.
0, CW that sucks CWP from tank 7 and sends it to furnace 9
And a P pump 9.

The operation of the apparatus having the above configuration will be described below. The raw coal 1 is supplied to the crusher 3 by the raw coal conveyor 2, crushed so as to have a weight average diameter of 1 to 2 mm, and turned into the crushed coal 19 and put into the crushed coal hopper 4. A part of the pulverized coal in the pulverized coal hopper 4 is supplied to the pulverizer 5 and is pulverized while being mixed with the water 11 which is pressurized by the water pump 16 and supplied through the pulverizer-side water amount adjusting valve 26. It becomes slurry 20. In the pulverizer 5, the surfactant 17 pressurized from the additive tank 12 to the additive pump 15 and supplied through the additive amount adjusting valve 24 is 0.01 to 0.9% based on the dry coal. Is injected at a rate of

The produced fine powder slurry 20 is sent to the kneading machine 6 and kneaded together with the crushed coal 19, limestone 22 and water 11 which are also supplied to the kneading machine 6, to form the CWP 21. At this time, the supplied water amount is supplied to the kneader 6 while adjusting the water amount adjusting valve 25 on the kneader side so that the viscosity of the CWP to be produced becomes a predetermined viscosity. Manufactured CWP21
Is measured with a pin type viscometer 23, and then the tank 7
Stored in CWP21 in the tank is CWP pump 8
To the furnace 9.

The kneader-side water amount adjusting valve 25 controls the amount of water sent to the kneader 6 so that the CWP viscosity detected by the pin type viscometer 23 is in the range of 5 to 15 Pa · s. If the water content of the raw coal is high, the CWP viscosity decreases. When the pin type viscometer 23 detects that the CWP viscosity is low, the additive amount adjusting valve 24 is opened, and at the same time, the opening of the pulverizer-side water amount adjusting valve 26 is narrowed to reduce the coal concentration of the fine powder slurry 20. The fine powder slurry is supplied to the kneader 6.
As a result, the water content at the outlet of the kneader 6 is reduced.
The viscosity of P21 increases. This is detected by the pin-type viscometer 23, and the kneading machine-side water amount adjusting valve 25 is set so that the water injection rate in the kneading machine falls within the range of the region E in FIG. The viscosity of the CWP is again controlled so that the relationship between the ratio of water injection in the kneader and the total water content of the CWP, which is indicated by an oblique line, falls within the range of the region E.

According to this method, as shown by the solid line in FIG.
Even if the coal has a water content of 14 wt%, the water content can be adjusted only by the kneader. Also, if a surfactant is added to the pulverizer, even if the coal concentration of the pulverizer is increased and pulverized, as shown by the line B in FIG. It can be seen that the particle size of No. 20 was maintained in the desired particle size range, and the pulverizing performance was not reduced.

Since it is also important to reduce the fuel cost, it is better not to use a surfactant except when the coal has a water content such that water cannot be injected by a kneader (having a water content of 10% or more). It is good, but in the case of coal having a water content of 10% or more, proper adjustment of water content and particle size cannot be performed unless a surfactant is used. Therefore, it is necessary to selectively use the operation method according to the prior art and the operation method according to the present invention according to the water content of the received coal. However, when a surfactant is suddenly added to a fine powder slurry in a fine pulverizer having a large amount of water as in the prior art, the dispersion is advanced and the coal is easily separated. Also, if the pulverizing concentration (coal concentration) of the fine powder slurry in the pulverizer containing no surfactant is suddenly increased, the pulverizing ability is reduced as described above. For this reason, it is important to simultaneously add the surfactant and increase the pulverization concentration.

For example, when the pulverization concentration is increased from 50% to 60% and the additive is added in an amount of 0.35% by weight based on the dry coal, the additive is not suddenly switched but is gradually added as shown in FIG. Operate to increase the amount of the agent and the pulverization concentration.

Next, a second embodiment of the present invention will be described with reference to FIG. This embodiment is different from the first embodiment shown in FIG. 1 in that the opening degree of the fine-pulverizer-side water amount adjusting valve 26 and the additive amount adjusting valve 24 is controlled by the output of the pin type viscometer 23. Instead, it is configured to be controlled based on the opening degree of the kneader-side water amount adjustment valve 25. The other components are the same as those in the first embodiment, and thus are denoted by the same reference numerals and description thereof will be omitted. Also in the present embodiment, the CWP viscosity is controlled based on the output of the pin type viscometer 23 so as to be in the range of 5 to 15 Pa · s. When the CWP viscosity output by the pin type viscometer 23 falls below the set value, the kneader-side water amount adjusting valve 25 is controlled so that the amount of injected water decreases. When it is detected that the opening of the kneader-side water amount adjustment valve 25 has been reduced, the additive amount adjustment valve 24 is opened, and at the same time, the opening of the pulverizer-side water amount adjustment valve 26 is reduced. When the fine powder slurry 20 thus manufactured is supplied to the kneading machine 6, C
The WP viscosity increases. This increase in viscosity is measured by a pin type viscometer 23.
Is detected, and the viscosity of the CWP 21 is again managed by the kneader-side water amount adjusting valve 25 as shown by the solid line in FIG.

[0025]

According to the present invention, even when the water content of the received coal exceeds 10%, the water content in the pulverizer is reduced by the addition of a surfactant to reduce the water content in the kneader. It is possible to make adjustments. As a result, even when the water content of the received coal exceeds 10%, it is possible to produce CWP in which the particle size of the coal pulverized by the pulverizer does not decrease.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a main configuration of a CWP manufacturing apparatus according to a first embodiment of the present invention.

FIG. 2 is a system diagram showing a main configuration of a CWP manufacturing apparatus according to a first embodiment of the present invention.

FIG. 3 is a graph comparing the relationship between the coal concentration and the particle size of the generated fine powder slurry in the conventional technology and the fine pulverizer according to the embodiment of the present invention.

FIG. 4 is a graph showing the relationship between the total water content of CWP and the mixing ratio (fine powder mixing ratio) of fine powder slurry and crushed coal in a kneader in a conventional technique.

FIG. 5 is a graph showing the relationship between CWP total moisture and CWP viscosity in a conventional technique.

FIG. 6 is a graph showing the relationship between the proportion of water added to the kneader and the total water content of CWP in the prior art and the embodiment of the present invention, comparing the water content of the coal of the pulverizer with the parameter.

FIG. 7 is a graph showing a comparison between changes in the coal concentration (pulverization concentration) and the amount of surfactant added over time in a pulverizer in a conventional technique and an example of the present invention.

FIG. 8 is a system diagram showing a main configuration of a CWP manufacturing apparatus according to a conventional technique.

FIG. 9 is a conceptual diagram showing a particle size distribution measured by sieving.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 raw coal 2 raw coal conveyor 3 crusher 4 crushed coal hopper 5 fine crusher 6 kneader 7 tank 8 CWP pump 9 furnace 10 CWP stirrer 11 water 12 additive tank 14 additive stirrer 15 additive pump 16 water pump DESCRIPTION OF SYMBOLS 17 Surfactant 19 Crushed charcoal 20 Fine powder slurry 21 CWP 22 Limestone 23 Pin type viscometer 24 Additive amount adjustment valve 25 Kneader side water amount adjustment valve 26 Pulverizer side water amount adjustment valve 27 First piping 28 Second piping 29 Discharge side piping 30 Piping

Continued on the front page (72) Inventor Hiroshi Yamaguchi 3-36 Takara-cho, Kure-shi, Hiroshima Prefecture Inside Babcock Hitachi Kure Research Laboratory (72) Inventor Yoshinori Otani 3-36 Takara-cho, Kure-shi Hiroshima Prefecture Inside Babcock Hitachi Kure Research Laboratory (72) Inventor Hiroshi Takezaki 3-36 Takara-cho, Kure City, Hiroshima Prefecture Inside Babcock Hitachi Kure Research Laboratory (72) Inventor Yoshitaka Takahashi 6-9 Takara-cho Kure City, Hiroshima Prefecture Inside Babcock Hitachi Kure Factory

Claims (4)

[Claims] After crushing raw coal, a part of the crushed coal is mixed with water while crushing the crushed coal with a pulverizer to produce a fine powder slurry, and the remaining crushed coal, limestone and the fine powder slurry are further mixed with a kneader. Of coal and water paste (hereinafter, referred to as CWP) by mixing water and water to detect the viscosity of CWP at the outlet of the kneader, and the coal concentration of the fine powder slurry in the pulverizer. And the amount of water supplied to the pulverizer. 2. The method for producing a coal / water paste according to claim 1, wherein the viscosity of CWP at a kneader outlet is detected.
A method for producing a coal / water paste, comprising adjusting an amount of a surfactant to be injected into a fine powder slurry in a fine pulverizer. 3. The method for producing a coal / water paste according to claim 1, wherein a decrease in the amount of water injected into the kneader controlled by using the CWP viscosity at the kneader outlet as an input is detected, and the fine pulverizer is operated. A method for producing a coal / water paste, wherein the amount of supplied water is adjusted. 4. The method for producing a coal / water paste according to claim 3, wherein when the amount of water injected into the kneader is reduced, the amount of the surfactant to be injected into the fine powder slurry in the fine pulverizer is adjusted. A method for producing a coal / water paste.