JP6628490B2 - Combustion device and method for preventing dust generation in combustion device - Google Patents

Description

  The present disclosure relates to a combustion device capable of preventing dust generated when coal is burned in a boiler from adhering to a heat exchanger provided in the boiler or an inner wall of the boiler, and a dust generation prevention method for the combustion device.

  In recent years, with the rise in oil prices, coal-fired thermal power has been reviewed again from the viewpoint of abundant reserves and economic efficiency. However, coal as a fuel for thermal power generation is solid in nature, and the combustion in the coal-fired boiler generates dust, which collides with or adheres to the heat transfer surface of the heat exchanger installed in the boiler. Then, there is a possibility that the heat transfer surface may be damaged or heat absorption may be difficult.

  On the other hand, in Patent Document 1, ions generated from outside the boiler are injected into the boiler with respect to dust (ash) generated by the combustion of coal in the boiler, and charge is generated in the dust from the reaction between the dust and the ions. In addition, a method of preventing ash adhesion is proposed, in which the same kind of charge is generated on the heat transfer surface of heat exchange, and the electrostatic repulsion acting on both surfaces is used to prevent dust from adhering to the heat transfer surface. Have been.

Showa 63-202013

  In the method for preventing ash deposition described in Patent Document 1, a discharge electrode is provided in a flow path for supplying pulverized coal pulverized coal to a boiler, and charging ions generated from the discharge electrode are injected into the boiler. Then, charging ions are attached to the dust (ash) generated by the combustion of the pulverized coal in the boiler to charge the dust. However, since the generated dust flows in the boiler toward the heat exchanger, it is difficult for the injected charging ions to adhere to all the dust (ash) and charge. Therefore, dust (ash) may collide with or adhere to the heat transfer surface, causing a problem that the heat transfer surface is damaged and that heat absorption becomes difficult.

  In view of the above circumstances, at least some embodiments of the present invention relate to a fuel device using coal as fuel, and dust generated when burning coal in a boiler collides with a heat transfer surface of a heat exchanger. An object of the present invention is to provide a combustion device and a method for preventing generation of dust in the combustion device, which are not likely to adhere.

The combustion device according to some embodiments of the present invention includes:
A crushing device for crushing coal,
A fuel supply device for supplying the pulverized coal of the coal pulverized by the pulverization device,
A boiler in which a heat exchanger is provided for burning the pulverized coal supplied from the fuel supply device,
The fuel supply device,
From the pulverized coal of the coal pulverized by the pulverizer, classification means for classifying pulverized coal having a predetermined particle size or less,
And separating and removing the negatively charged pulverized coal from the pulverized coal having a predetermined particle size or less separated by the classification means.

  According to the combustion apparatus, when the coal is pulverized by the pulverizer, the coal is separated into fine powder of carbon (c) and other components (for example, silicon dioxide, aluminum oxide, and the like). Then, the pulverized coal of the separated carbon and the pulverized coal of the other components are frictionally charged by stirring or the like at the time of pulverization, the carbon is charged to a plus (+), and the pulverized coal of the other components is set to a minus (-). It has the property of being charged. The pulverized coal pulverized by the pulverizer is classified into pulverized coal having a predetermined particle size or less by a classification means. Then, the pulverized coal that is negatively charged among the pulverized coal classified by the classification means is separated and removed by the separation and removal means. For this reason, since the pulverized coal charged positively is supplied to the boiler, the fine powder supplied to the boiler contains a large amount of carbon components. Therefore, it is possible to suppress the generation of dust when the fine coal is burned in the boiler, and it is possible to suppress the possibility that the dust collides with or adheres to the heat exchanger. Therefore, it is possible to realize a combustion device in which dust generated when burning coal in the boiler does not collide with or adhere to the heat transfer surface of the heat exchanger.

Also, in some embodiments,
The separation and removal unit is configured to have an attachment member that generates a positive charge and electrostatically attaches the negatively charged pulverized coal.

  In this case, the separation / removal means has an attaching member that generates a positive charge and electrostatically attaches the negatively charged pulverized coal, so that the negatively charged pulverized coal is effectively attached. It can be attached to a member. Therefore, the ratio of the negatively charged pulverized coal contained in the pulverized coal supplied into the boiler from the separation and removal means can be reduced. Therefore, the amount of dust generated during the combustion of the pulverized coal supplied into the boiler can be reliably reduced.

Also, in some embodiments,
The classifying means includes a filter having a hole portion capable of passing only fine powder having a predetermined particle size or less among fine coals of coal pulverized by the pulverizer, and a pulverizer that pulverizes coal that cannot pass through the filter. It is configured to have a return flow path for returning the powder to re-grinding.

  In this case, the classification means is provided with a return flow path for returning the pulverized coal that cannot pass through the filter to the pulverizing device and re-pulverizing the coal. Crushed. Therefore, the pulverized coal can be reliably turned into pulverized coal having a small particle size, and the combustion of the pulverized coal in the boiler can be further improved.

Also, in some embodiments,
The boiler is configured to be provided with a charge supply unit capable of applying a positive charge to the boiler wall.

  In this case, since the boiler is provided with charge supply means capable of applying a positive charge to the boiler wall, the positively charged pulverized coal supplied into the boiler is charged by the electrostatic repulsion force. Can be prevented. Therefore, the combustion of the positively charged pulverized coal supplied into the boiler can be further improved.

A method for preventing dust generation of a combustion device according to some embodiments of the present invention includes:
Pulverizing coal as fuel to produce charged fine pulverized coal,
Classifying the pulverized coal to a predetermined particle size or less,
Negatively charged pulverized coal among the pulverized coal having a predetermined particle size or less is separated and removed,
The positively charged pulverized coal is separated and removed, and the positively charged pulverized coal remaining is supplied to a boiler of a combustion device to burn the positively charged pulverized coal in the boiler.

  According to the dust generation preventing method of the combustion apparatus, when the coal is pulverized, the coal is separated into fine powder of carbon (c) and other components (for example, silicon dioxide, aluminum oxide, and the like). Then, the pulverized coal of the separated carbon and the pulverized coal of the other components are frictionally charged by stirring or the like at the time of pulverization, the carbon is charged to a plus (+), and the pulverized coal of the other components is set to a minus (-). It has the property of being charged. The pulverized pulverized coal is classified into pulverized coal having a predetermined particle size or less, and of the classified pulverized coal, negatively charged pulverized coal is separated and removed. As a result, pulverized coal containing a large amount of pulverized coal that is positively charged is supplied to the boiler, and the generation of dust during the combustion of the pulverized coal in the boiler can be suppressed, and the dust is not heated. The possibility of colliding with or adhering to the exchanger can be suppressed. Therefore, it is possible to realize a method of preventing generation of dust in a combustion device in which dust generated when burning coal in the boiler does not collide with or adhere to the heat transfer surface of the heat exchanger.

  According to at least some embodiments of the present invention, in a fuel device using coal as fuel, there is a possibility that dust generated when burning coal in a boiler collides with or adheres to a heat transfer surface of a heat exchanger. And a method for preventing generation of dust in a combustion device.

It is a schematic structure figure of a combustion device concerning one embodiment of the present invention. It is a schematic structure figure of a classification device and a separation removal device of a combustion device. It is explanatory drawing for demonstrating the operation principle of a separation removal apparatus. It is explanatory drawing for demonstrating the flow until coal is supplied to a boiler.

  Hereinafter, an embodiment of a combustion device and a method of preventing generation of dust in a combustion device according to the present invention will be described with reference to FIGS. Note that the materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples.

  First, before describing a method for preventing generation of dust in a combustion apparatus according to an embodiment of the present invention, the combustion apparatus will be described. The combustion device 1 includes a crushing device 40, a fuel supply device 37, and the boiler 10, as shown in FIG.

  The pulverizing device 40 pulverizes the coal to generate pulverized coal having a small particle size. The pulverizing device 40 includes a rotary blade 41 having a plurality of blades 42 and rotatable. By the rotation of the rotary blade 41, the coal is pulverized into pulverized coal having a small particle size, and the pulverized coal is frictionally charged due to contact between the pulverized pulverized coal. Here, when the coal is pulverized by the pulverizer 40, the coal is separated into fine powder of carbon (c) and other components (for example, silicon dioxide, aluminum oxide, etc.). Then, the pulverized coal of the separated carbon and the pulverized coal of the other components are frictionally charged by stirring or the like at the time of pulverization, so that the carbon is positively (+) charged and the other components are negatively (-) charged. Has properties. The combustion device 1 of the present embodiment utilizes such a property relating to the charging of coal.

  The fuel supply device 37 includes the classification device 3 and the separation and removal device 20. As shown in FIGS. 1 and 2, the classification device 30 and the separation and removal device 20 are disposed adjacent to each other. The classification device 30 includes a classification main body 31 having a hollow box shape inside. A filter 33 having a hole through which only fine powder having a predetermined particle size or less among fine coals of coal pulverized by the pulverizer 40 is provided in the classification main body 31. The pulverized coal that has passed through the filter 33 is sent to the separation / removal device 20, and the coal that cannot pass through the filter 33 passes through the return channel 35, one end of which is connected to the bottom of the classification main body 31 and the other end of which communicates with the crusher 40. It is returned to the crushing device 40 through the crushing device 40 and crushed again. In addition, if the particle size of coal is relatively large, flammability deteriorates. For this reason, the pulverized coal is pulverized by using the pulverizing device 40.

  The separation and removal apparatus 20 includes a separation and removal main body 21 having a hollow box shape inside. As shown in FIG. 3, a pair of pole plates 23 arranged in the horizontal direction and extending in the vertical direction are provided in the separation removal main body 21. These electrode plates 23 are made of a metal material, and are electrically connected to a power supply 25. A positive charge (potential) is applied to these electrode plates 23 by a power supply 25. A space 23a through which fine coal classified by the classifier 30 can flow is formed between the electrode plates 23.

  The pulverized coal 50 passing through the space 23a is the pulverized coal 50a of carbon charged positively (+) and the pulverized coal 50b charged negatively (-) as described above. Of these pulverized coals 50, the pulverized coal 50b charged negatively (-) is electrostatically attracted to the electrode plate 23 having a positive charge (potential) and adheres to the electrode plate 23. For this reason, when passing between the pair of electrode plates 23, the pulverized coal 50b charged negatively (−) by the pair of electrode plates 23 is separated and removed, and the pulverized coal 50a of carbon charged positively (+) is removed. Pass through the space 23a. In addition, the power supply 25 may be capable of changing the positive charge (potential) according to the flow rate of the pulverized coal 50 or the like, or may be capable of keeping the charge (potential) constant.

  When the pulverized coal is combined with each other to increase the particle size when the pulverized coal 50 sent from the classification device 30 is distributed, the separated pulverized coal is sent to the pulverizing device 40. A return channel 26 (see FIG. 1) for returning and re-grinding is provided. In addition, the separation and removal device 20 communicates with the boiler 10 via the secondary air passage 14.

  As shown in FIG. 1, the boiler 10 has a window box 12 provided with a burner 11 on one side in the width direction of the boiler 10, and pulverized coal 50 a serving as fuel through a secondary air passage 14 is placed in a boiler furnace 15. And burned by the burner 11. An exhaust gas passage 16 for discharging combustion exhaust gas is provided in an upper portion of the boiler furnace 15, and a heat exchanger 17 is provided in an upper portion of the boiler furnace 15. The heat exchanger 17 includes a boiler tube 17a for flowing a heat medium (for example, water). The heat exchanger 17 of the present embodiment generates steam to be supplied to a turbine for driving a generator (not shown).

  Next, a method for preventing generation of dust in a combustion device according to an embodiment of the present invention will be described with reference to FIGS. First, as shown in FIG. 4, coal is charged into a pulverizing device 40, and the coal is pulverized by the pulverizing device 40. During the comminution of the coal, the coal is separated into pulverized coal of carbon (c) and other components (eg, silicon dioxide, aluminum oxide, etc.). Then, the pulverized coal of the separated carbon and the pulverized coal of the other components are frictionally charged by stirring or the like at the time of pulverization, and the carbon is charged to the pulverized coal 50a of plus (+), and the other components are minus (-). Of the pulverized coal 50b.

  The pulverized coal 50 generated by the pulverizer 40 is classified into pulverized coal having a predetermined particle size or less by the classification device 30 which is a part of the fuel supply device 37. Coal exceeding a predetermined particle size is returned to the pulverizing device 40 via the return channel 35 and re-pulverized. Pulverized coal 50 having a predetermined particle size or less is sent to the separation and removal device 20 which is a part of the fuel supply device 37. Of the pulverized coal 50 sent to the separation and removal device 20, the pulverized coal 50 b charged negatively (−) is separated and removed by the separation and removal device 20. Therefore, only the pulverized coal 50 a that is positively charged is sent to the boiler 10. When the pulverized coal 50 sent to the separation / removal apparatus 20 is distributed, the pulverized coal having a larger particle size due to the binding is dropped by its own weight or forcedly dropped by hammering. And returned to the crushing device 40 to be crushed again.

  The pulverized coal 50 sent from the separation and removal device 20 is supplied into the boiler furnace 15a. The pulverized coal 50 supplied into the boiler furnace 15a is positive (+) pulverized coal 50a. Therefore, when the pulverized coal 50a is burned in the boiler 10, the coal of the carbon component is mainly burned, so that the amount of generated dust can be reduced. For this reason, it is possible to suppress the possibility that the dust collides with or adheres to the boiler tube 17a of the heat exchanger 17. Therefore, it is possible to prevent the boiler tube 17a from being damaged and the heat from the boiler tube 17a from becoming difficult to be absorbed.

  As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the object of the present invention. For example, the various embodiments described above may be appropriately combined.

DESCRIPTION OF SYMBOLS 1 Combustion apparatus 10 Boiler 11 Burner 12 Window box 14 Secondary wind path 15 Boiler furnace 16 Exhaust gas flow path 17 Heat exchanger 17a Boiler tube 20 Separation removal device (separation removal means)
21 Separation removal main body 23 Electrode plate 23a Space 25 Power supply 26, 35 Return flow path 30 Classification device (classification means)
31 Classification main body 33 Filter 37 Fuel supply device 40 Crushing device 41 Rotary blade 42 Blade 50 Pulverized coal 50a Pulverized coal of carbon component 50b Pulverized coal charged negatively (-)

Claims (4)

A crushing device for crushing coal,
A fuel supply device for supplying pulverized coal of the coal pulverized by the pulverization device,
A boiler in which a heat exchanger is provided for burning the pulverized coal supplied from the fuel supply device,
The fuel supply device,
From the pulverized coal of the coal pulverized by the pulverizer, classification means for classifying pulverized coal having a predetermined particle size or less,
Among the pulverized coal having a predetermined particle size or less separated by the classification means, the pulverized coal that is negatively charged is a separation and removal means for separating and removing the pulverized coal, the separation and removal main body portion having a hollow inside. Separation removal means provided,
A pair of electrode plates to which a positive potential is applied are provided inside the separation and removal main body, and pulverized coal having a predetermined particle size or less separated by the classification means flows between the pair of electrode plates. A possible space is formed,
Positively charged pulverized coal among the pulverized coal that has passed through the space is configured to be supplied to the boiler via a secondary air passage that is communicated with the separation and removal main body. A combustion device characterized by the following. The classification means, a filter having a hole portion that can pass only fine powder having a predetermined particle size or less among the pulverized coal of coal pulverized by the pulverizing device, and pulverized coal that cannot pass through the filter to the pulverizing device The combustion device according to claim 1, further comprising a return flow path for returning and re-grinding. The said boiler is provided with the electric charge supply means which can apply a positive electric charge to a boiler wall. The combustion apparatus of Claim 1 or 2 characterized by the above-mentioned. Pulverizing coal as fuel to produce charged pulverized coal,
Classifying the pulverized coal to a predetermined particle size or less,
By passing the classified pulverized coal having a predetermined particle size or less through a space formed between a pair of electrode plates to which a positive potential is applied , the classified pulverized coal having a predetermined particle size or less becomes negative. Separating and removing charged pulverized coal,
Positively charged pulverized coal remaining after separating and removing the negatively charged pulverized coal is supplied to a boiler of a combustion device via a secondary air path, and the positively charged pulverized coal is A method for preventing the generation of dust in a combustion device, characterized by burning gas.

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