WO2019106796A1

WO2019106796A1 - Powdered coal supply device and toxic trace element elution suppression method

Info

Publication number: WO2019106796A1
Application number: PCT/JP2017/043122
Authority: WO
Inventors: 英嗣清永; 健治引野; 啓一郎盛田
Original assignee: 中国電力株式会社
Priority date: 2017-11-30
Filing date: 2017-11-30
Publication date: 2019-06-06
Also published as: JP6744401B2; JPWO2019106796A1

Abstract

The present invention provides a powdered coal supply device with which the ratio between coal and an elution prevention agent for toxic trace elements can be uniform. This powdered carbon supply device 10 is provided with: a coal bunker 11 in which coal is stored; a coal feeder 12 that has therein a transportation conveyor 12c that transports the coal supplied from the coal bunker 11; and a coal pulverizer 14 that pulverizes the coal charged from the coal feeder 12 and generates powdered coal. The coal feeder 12 is provided with a box-like frame 12f and an elution suppression agent adding device 13. The frame 12f has a coal dropping port 12s from which the coal is discharged and which is open at a lower part of another end part. The elution suppression agent adding device 13 can drop, toward the coal dropping port 12s in the frame 12s, an elution suppression agent Ea for suppressing the elution of toxic trace elements from combustion residue of the coal.

Description

Pulverized coal supply device and harmful trace element elution suppression method

TECHNICAL FIELD The present invention relates to a pulverized coal feeding device and a harmful trace element elution suppression method. In particular, it is a pulverized coal feeding apparatus and a harmful trace element elution suppression method for use in a coal thermal power plant using pulverized coal as a fuel for a boiler, wherein the elution inhibitor is a fine powder that suppresses the elution of harmful trace elements from combustion residue of coal. The present invention relates to the structure of a pulverized coal feeding device and a method for suppressing harmful trace element elution, which can be reliably added to charcoal at a constant rate.

For example, in a coal-fired power plant, pulverized coal is used as fuel for a boiler. In this coal thermal power plant, the coal stored in the coal storage plant is discharged, and coal is transported to the pulverized coal feeding device by a coal transport mechanism such as a conveyor. The pulverized coal supply apparatus includes a coal pulverizer (mill) that pulverizes massive coal into fine particles to form pulverized coal.

Pulverized coal produced by the coal pulverizer is sent to a boiler and burned in the boiler. The combustion heats the water to generate steam. In the case of ignition inside the boiler, oil may be supplied to the boiler.

The steam generated in the boiler is supplied to a steam turbine, a generator is driven by the steam turbine, and power can be supplied by the generator. The steam that has passed through the steam turbine is condensed by the condenser and condensed to the boiler together with the makeup water.

The pulverized coal supply apparatus described above includes a coal bunker storing coal, a coal feeder, and a coal pulverizer. In the coal bunker, coal transported from the coal storage station by the coal transport mechanism is temporarily stored. Then, coal is supplied from the coal bunker to the coal feeder via the first coal feeding pipe.

The coal feeder has a transfer conveyor inside, and coal supplied from the coal feeding pipe is horizontally transferred by the transfer conveyor. Then, coal is discharged from the transfer conveyor to the coal discharge port formed at the end of the transfer conveyor. Furthermore, coal is introduced into the coal pulverizer through a second coal feed pipe formed in connection with the coal discharge port. In the pulverized coal feeding device described above, the call gate valve for opening and closing the first coal feeding pipe is disposed immediately above the feeder. The call gate valve can be opened and closed manually.

By the way, when the call gate valve is manually driven in the closing direction to close the first coal feeding pipe, coal is still accumulated between the coal feeding pipe after the call gate valve and the transport conveyor. This may cause coal clogging in the first coal feed pipe. And after stopping a coal pulverizer for a long period of time, when resuming operation, the pulverized coal supply device which can stably supply coal to a coal pulverizer is disclosed (for example, refer to patent documents 1). .

On the other hand, in coal-fired power generation using pulverized coal as a fuel for boilers, coal ash to be a residue after combustion contains trace amounts of harmful trace elements such as boron, fluorine, selenium, arsenic and hexavalent chromium. For this reason, techniques for reducing the elution concentration of harmful trace elements contained in coal ash to less than legally regulated values have been studied.

For example, by adding an elution inhibitor for coal addition consisting of calcium carbonate (CaCO ₃ ) to coal, many harmful trace elements are transferred to ash coal ash by the action of calcium oxide (CaO), and additionally the action of alkali Discloses a method for suppressing the elution of harmful trace elements that contributes to the suppression of elution of harmful trace elements (see, for example, Patent Document 2).

Unexamined-Japanese-Patent No. 2012-26724 JP 2008-275181 A

The harmful trace element elution suppression method according to Patent Document 2 can be easily applied to the improvement of existing equipment because addition of the elution inhibitor is added at the stage of coal during combustion or before combustion instead of coal ash after combustion. And. Moreover, the harmful trace element elution suppression method by patent document 2 will not be specifically limited if the timing of addition is addition in the state of coal, Any of a coal feeder, a coal pulverizer, and a boiler may be sufficient, And

However, although the harmful trace element elution suppression method according to Patent Document 2 discloses the timing of the addition of the harmful trace element elution inhibitor, the place where the harmful trace element elution inhibitor is injected is not specified.

For example, when granular calcium carbonate (CaCO 3) is mixed on a conveyor that transports coal to a coal bunker, calcium carbonate having a much smaller particle size than the bulk coal falls first at the bottom of the coal bunker, and This results in variations in the mixing ratio of calcium carbonate. And, since the mixing ratio of coal and calcium carbonate does not fall within a certain numerical range, there is a concern that harmful trace elements can not be suppressed well. There is a concern that it will be difficult to add an elution inhibitor of harmful trace elements at an appropriate ratio to the coal in the post process of the coal bunker.

Pulverized coal supply apparatus and harmful trace element elution suppression method for use in a coal thermal power plant using pulverized coal as fuel for a boiler, wherein mixing ratio of coal and elution control agent of harmful trace element falls within a certain ratio There is a need for possible pulverized coal supply devices and methods for controlling the release of harmful trace elements. And, the above can be said to be the problem of the present invention.

The present invention has been made in view of such problems, and it is a pulverized coal supply device and a harmful trace element elution suppression method used for a coal-fired power generation facility using pulverized coal as a fuel for a boiler It is an object of the present invention to provide a pulverized coal feeding apparatus and a harmful trace element elution suppression method, in which the mixing ratio of a trace element elution inhibitor can be contained in a constant ratio.

The present inventors comprise a pulverized coal feeding apparatus comprising a conveyer for conveying coal, and a coal pulverizer disposed below the downstream end of the conveyer and crushing coal to form pulverized coal. , Dispense elution inhibitor that suppresses elution of harmful trace elements from above the conveyer conveyor or coal pulverizer to make the mixing ratio of coal and elution inhibitor of harmful trace elements constant by dropping it into the coal pulverizer Based on this idea, the inventors have invented the following new pulverized coal feeding apparatus and harmful trace element elution suppression method as follows.

(1) A pulverized coal supply apparatus according to the present invention includes: a coal bunker storing coal; a coal feeder including therein a conveyer for conveying coal supplied from the coal bunker from one end to the other end; And a pulverized coal feeder including a coal pulverizer for pulverizing coal input from the other end of the feeder to produce pulverized coal, wherein the feeder is configured to discharge coal. And a box-shaped frame with the coal discharge opening at the bottom of the other end, and an elution inhibitor that can suppress the elution of harmful trace elements from the combustion residue of coal toward the coal discharge opening of the frame. And an elution inhibitor addition device.

(2) The elution inhibitor addition device includes a hopper storing the elution inhibitor, and a screw feeder for feeding the elution inhibitor supplied from the hopper toward the coal discharge port of the frame. Is preferred.

(3) The coal feeder includes a first motor for driving the conveyer, and the anti-elution agent addition device includes a second motor for driving the screw feeder, and corresponds to the rotational speed of the first motor. Preferably, the rotational speed of the second motor is adjusted.

(4) It is preferable that the said elution inhibiting agent contains 1 or more types selected from the group which consists of a limestone, a limestone, and quick lime.

(5) The elution inhibitor is preferably in the form of granules or powder.

(6) The harmful trace element elution suppression method according to the present invention is the harmful trace element elution suppression method in a coal-fired thermal power plant equipped with a pulverized coal feed device, wherein the pulverized coal feed device comprises a conveyor for conveying coal; A coal pulverizer disposed below the downstream end of the conveyer and crushing coal to form pulverized coal; harmful trace elements from above the conveyer or the coal pulverizer The elution inhibitor which suppresses the elution of is dropped to the said coal pulverizer.

(7) The rotational speed of the second motor for driving the screw feeder that feeds the elution inhibitor toward the coal pulverizer is adjusted in accordance with the rotational speed of the first motor for driving the transport conveyor. Is preferred.

The pulverized coal feeding device according to the present invention is disposed at the end of the conveyer, and the elution inhibitor addition device is disposed above the coal discharge port from which coal is discharged, and the elution of harmful trace elements in the elution inhibitor addition device The mixing ratio of coal and the elution inhibitor of harmful trace element can be made constant by storing the inhibitor and supplying the elution inhibitor of harmful trace element from the elution inhibitor addition device toward the coal discharge port.

The harmful trace element elution suppression method according to the present invention is a harmful trace element elution suppression method in a coal-fired power plant equipped with a pulverized coal feeding device, wherein the pulverized coal feed device comprises a conveyer for conveying coal, and a downstream of the conveyer. And a coal pulverizer, which is disposed below the end of the side to pulverize coal to produce pulverized coal, and which prevents elution of harmful trace elements from above the conveyer conveyor or the coal pulverizer. By dropping the agent into a coal pulverizer, the mixing ratio of coal and the elution inhibitor of harmful trace elements can be made constant.

It is the schematic which shows the structure by an example of the coal-fired-power-generation installation using the pulverized coal supply apparatus by one Embodiment of this invention. It is a front view which shows the structure of the pulverized coal supply apparatus by one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Composition of coal-fired power plant)
First, a configuration according to an example of a coal-fired power plant using a pulverized coal supply device according to an embodiment of the present invention will be described.

FIG. 1 is a schematic view showing a configuration of an example of a coal-fired power plant using a pulverized coal supply apparatus according to an embodiment of the present invention. FIG. 2 is a front view showing the configuration of a pulverized coal supply device according to an embodiment of the present invention.

Referring to FIG. 1, a coal-fired power plant 100 according to an example of the present invention includes a pulverized coal supply device 10 and a boiler 20. The coal-fired power plant 100 further includes a steam turbine 30 and a condenser 40.

Referring to FIG. 1 or 2, the pulverized coal supply device 10 includes a coal bunker 11 and a coal feeder 12. The pulverized coal feeding device 10 further includes an elution inhibitor adding device 13 and a coal pulverizer 14.

Referring to FIG. 1 or 2, bulk coal C is conveyed to a coal bunker 11 by a conveyor 15 with a dustproof cover from a coal storage station (not shown). Then, massive coal C is temporarily stored in the coal bunker 11. Coal C stored in the coal bunker 11 is supplied to the coal feeder 12.

Referring to FIG. 2, the coal feeder 12 internally includes a transport conveyor 12 c. The transport conveyor 12 c can transport the coal C supplied from the coal bunker 11 from one end to the other end. The coal pulverizer 14 can pulverize the coal C fed from the other end of the coal feeder 12 to produce pulverized coal.

Referring to FIG. 1, the boiler 20 internally includes a combustion chamber 2 r fueled by pulverized coal produced by the coal pulverizer 14. In the example shown in FIG. 1, oil is sent to the combustion chamber 2 r via an oil feed pipe (not shown). And in the combustion chamber 2r, while burning oil, pulverized coal can be burned. Further, combustion air is sent to the combustion chamber 2r by a ventilator. Thus, in the combustion chamber 2r of the boiler 20, two-stage combustion is performed. By this combustion, the water supplied from the feed pump 41 is heated to become superheated steam, and the superheated steam is sent from the boiler 20 to the steam turbine 30.

Referring to FIG. 1, the steam turbine 30 internally includes a turbine (impeller). If the superheated steam is fed into the turbine from its axial direction, the turbine can be rotated. The rotating shaft of the turbine is connected to the rotor of the generator 31. When superheated steam is fed into the steam turbine 30, power can be supplied by the rotor of the generator 31 rotating.

Referring to FIG. 1, the superheated steam that has consumed kinetic energy in the steam turbine 30 is returned to water by being cooled and condensed in the condenser 40. In other words, it is recovered. The condensed water is circulated to the boiler 20 by the feed water pump 41 together with the makeup water.

Thus, referring to FIG. 1 or FIG. 2, the coal thermal power generation facility 100 heats water with the boiler 20 using pulverized coal as fuel to generate superheated steam, and sends the superheated steam to the steam turbine 30. Power can be supplied by the generator 31.

[Composition of pulverized coal supply device]
Next, the configuration of the pulverized coal supply device 10 according to the embodiment of the present invention will be described.

(Coal bunker composition)
First, the configuration of the coal bunker 11 according to the embodiment will be described. Referring to FIG. 2, the coal bunker 11 is composed of an inverted conical main body 11 b whose top surface is opened and a coal feeding pipe 11 p extending from the bottom of the main body 11 b. The coal feed pipe 11 p is connected to one end of the coal feeder 12. Bulk coal C stored in the main body 11 b can be dumped into the inside of the coal feeder 12 through the coal feeding pipe 11 p.

Referring to FIG. 2, a call gate valve 11c is disposed in the middle of the coal feeding pipe 11p. The call gate valve 11c is internally provided with a valve body capable of opening and closing the pipe line of the coal feeding pipe 11p. The call gate valve 11 c connects the third motor 11 m.

Referring to FIG. 2, the call gate valve 11c is internally provided with a conversion mechanism (not shown) for converting the rotational movement of the third motor 11m into the forward and backward movement of the valve body. When the output shaft of the third motor 11m is rotated in one direction, the pipeline of the coal feeding pipe 11p can be opened. When the output shaft of the third motor 11m is rotated in the other direction, the pipeline of the coal feeding pipe 11p can be closed.

Referring to FIG. 2, after the pulverized coal feeding device 10 closes the pipe line of the coal feeding pipe 11 p, when the first predetermined time elapses, the coal feeding machine 12 is stopped, and then, Since the coal pulverizer 14 is controlled to stop when the time of 2 elapses, the coal C in the coal feeding passage after the call gate valve 11 c is supplied to the coal feeder 12, and the coal gate valve 11 c Coal C does not stay in the subsequent coal feeding passage. Therefore, even if the coal pulverizer 14 is stopped for a long time, it is possible to prevent coal clogging in the coal feeding passage.

(Configuration of the coal feeder)
Next, the configuration of the coal feeder 12 according to the embodiment will be described. Referring to FIG. 2, the coal feeder 12 includes a box-like frame 12 f and a conveyer 12 c. The frame 12 f opens the coal outlet 12 s from which the coal C is discharged at the bottom of the other end.

Referring to FIG. 2, as a substance, the coal discharge port 12s is an inlet opening of a coal feeding pipe 14p connecting the frame 12f and the coal pulverizer 14. The coal C discharged to the coal injection port 12s is fed to the coal pulverizer 14 and pulverized coal C is pulverized by the coal pulverizer 14, whereby pulverized coal can be produced.

Referring to FIG. 2, the conveyer 12c is composed of a pair of

rollers

121 and 122 and an endless belt 12v. The pair of

rollers

121 and 122 are spaced apart from each other. The endless belt 12v winds a pair of

rollers

121 and 122. In the example shown in FIG. 2, the roller 121 is a driving wheel, and the roller 122 is a driven wheel.

Referring to FIG. 2, the drive side roller 121 couples the first motor 12 m. When the first motor 12m is rotated in one direction, the upper side of the endless belt 12v can travel from one end to the other end, and the coal C supplied from the coal bunker 11 is conveyed toward the coal discharge port 12s it can. Moreover, the 1st motor 12m can adjust the input quantity per unit time of the coal C introduce | transduced into the coal pulverizer 14 by controlling the rotational speed.

(Configuration of elution inhibitor addition device)
Next, the configuration of the elution inhibitor adding apparatus 13 according to the embodiment will be described. Referring to FIG. 2, the anti-elution agent addition device 13 includes an inverted conical hopper 13 h having an open top and a screw feeder 13 f. The hopper 13h stores the elution inhibitor Ea. The elution inhibitor Ea can suppress the elution of harmful trace elements from the combustion residue of coal.

Referring to FIG. 2, a gate valve 13v is provided between the hopper 13h and the screw feeder 13f. The gate valve 13v can open and close a pipeline from the hopper 13h to the screw feeder 13f. By operating the handle, the pipeline from the hopper 13 h to the screw feeder 13 f can be opened and closed.

Referring to FIG. 2, the screw feeder 13 f can send out the elution inhibitor Ea supplied from the hopper 13 h toward the coal discharge port 12 s of the frame 12 f. The screw feeder 13f connects the second motor 13m.

With reference to FIG. 2, when the second motor 13m is rotated, the spiral screw 13s can be rotated to send out the elution inhibitor Ea in the axial direction. By controlling, it is possible to adjust the input amount per unit time of the elution inhibitor Ea input to the coal pulverizer 14 through the coal discharge port 12s.

Referring to FIG. 2, the rotation of the second motor 13m corresponds to the rotational speed of the first motor 12m, that is, corresponding to the input amount of coal C input to the coal pulverizer 14 per unit time. By adjusting the speed, the amount of the elution inhibitor Ea can be adjusted at an appropriate rate.

[Operation of pulverized coal supply device]
Next, the operation and effects of the pulverized coal supply device 10 according to the embodiment will be described.

Referring to FIG. 1 or 2, the pulverized coal feeding device 10 is formed at the end of the conveyer 12c, and places a hopper 13h with a screw feeder 13f above the coal discharge opening 12s from which coal is discharged, Disposal agent Ea of harmful trace elements is stored in hopper 13h, and screw feeder 13f is driven to feed elution stop agent Ea of harmful trace elements from hopper 13h to coal injection port 12s, thereby causing harmful effects to coal and harmful substances. The mixing ratio of the elution inhibitor Ea of trace element can be made constant.

Referring to FIG. 2, the coal feeder 12 includes a first motor 12 m that drives the transfer conveyor 12 c. Further, the elution inhibitor adding device 13 is provided with a second motor 13m that drives the screw feeder 13f. By adjusting the rotational speed of the second motor 13m, corresponding to the rotational speed of the first motor 12m, that is, corresponding to the input amount of coal C input to the coal pulverizer 14 per unit time, The amount of elution inhibitor Ea can be adjusted at an appropriate rate.

Referring to FIG. 2, the elution inhibitor Ea contains one or more selected from the group consisting of limestone, limestone and quicklime. The elution inhibitor Ea is preferably in the form of granules or powder. The average particle size of the elution inhibitor Ea preferably does not exceed 200 μm. The pulverized coal and the elution inhibitor Ea can be mixed and delivered to the boiler 20.

With reference to FIG. 1 or 2, it is preferable that the coal pulverizer 14 be internally provided with a classifier utilizing centrifugal force, so-called dry cyclone. After classifying the pulverized coal and the elution inhibitor Ea pulverized by the coal pulverizer 14 into predetermined particle sizes, it is possible to deliver the pulverized coal and the elution inhibitor Ea to the boiler 20.

Referring to FIG. 2, the means for supplying elution inhibitor Ea to coal feeder 12 is not limited to screw feeder 13f. The type of feeder or conveyor serving as the supplying means is not limited as long as the transportation means is suitable for powder transportation.

Referring to FIG. 2, the elution inhibitor Ea may be dropped onto the conveyer 12c, and the elution inhibitor Ea for suppressing elution of harmful trace elements from above the coal pulverizer 14 is pulverized by a coal pulverizer. By dropping it to 14, the addition amount of the elution inhibitor Ea can be adjusted at an appropriate ratio with respect to the coal.

The pulverized coal supply apparatus according to the present invention adds the elution inhibitor to the feed speed of the first motor for driving the conveyer by separately providing the means for injecting coal and the elution inhibitor into the feeder. You can adjust the amount.

The harmful trace element elution suppression method according to the present invention can separately supply the coal and the elution inhibitor upstream of the coal pulverizer without mixing the coal and the elution inhibitor on the conveyor for conveying the coal to the coal bunker. Therefore, the amount of elution inhibitor added to coal can be adjusted.

The pulverized coal supply device according to the present invention can be expected to have the following effects.
(1) By mixing with pulverized coal and feeding the elution inhibitor of the proper composition to the boiler and burning it at a high temperature, it is possible to accelerate the uptake of harmful trace elements into the coal ash.
(2) Since the elution inhibitor mixed with pulverized coal is fed into the boiler and burned at a high temperature, harmful trace elements flowing from the exhaust gas into the desulfurization apparatus can be suppressed.

DESCRIPTION OF SYMBOLS 10 pulverized coal supply apparatus 11 coal bunker 12 coal feeding machine 12c conveyer 12f flame | frame 12s coal pouring opening 13 elution inhibiting agent addition apparatus 14 coal pulverizer C coal Ea elution inhibiting agent

Claims

From the other end of the coal bunker which stored the coal bunker which stored coal, the conveyance conveyer which conveys the coal supplied from the coal bunker from one end to the other end, and the other side of the coal feeder A pulverized coal feeding apparatus comprising a coal pulverizer for pulverizing input coal to form pulverized coal,
The coal feeder is
A box-like frame that opens at the lower end of the other end of the coal outlet from which the coal is discharged;
A pulverized coal feeding apparatus, comprising: an elution inhibitor addition device capable of pouring an elution inhibitor that suppresses elution of harmful trace elements from combustion residue of coal toward a coal injection port of the frame.
The elution inhibitor addition device is
A hopper storing the elution inhibitor,
The pulverized coal feeder according to claim 1, further comprising: a screw feeder for feeding out the elution inhibitor supplied from the hopper toward a coal discharge port of the frame.
The coal feeder comprises a first motor for driving the transport conveyor,
The elution inhibitor addition device comprises a second motor for driving the screw feeder,
The pulverized coal feeding device according to claim 2, wherein the rotational speed of the second motor is adjusted according to the rotational speed of the first motor.
The pulverized coal supply device according to any one of claims 1 to 3, wherein the elution inhibitor contains one or more selected from the group consisting of limestone, limestone and quicklime.
The pulverized coal feeding device according to claim 4, wherein the elution inhibitor is in the form of particles or powder.
A method for suppressing harmful trace element elution in a coal-fired thermal power plant equipped with a pulverized coal supply device, comprising:
The pulverized coal supply device
A conveyer that conveys coal;
And a coal pulverizer, which is disposed below the downstream end of the transport conveyor and crushes coal to produce pulverized coal.
The harmful trace element elution suppression method which drops the elution inhibiting agent which suppresses elution of harmful trace element from the upper part of the said conveyance conveyor or the said coal pulverizer to the said coal pulverizer.
The rotational speed of a second motor for driving a screw feeder that feeds the elution inhibitor toward the coal pulverizer is adjusted in accordance with the rotational speed of a first motor for driving the transport conveyor. The harmful | toxic trace element elution suppression method of 6 statement.