JP5063761B2 - Thermal power generation system - Google Patents

Description

  The present invention relates to a thermal power generation system using coal.

Conventionally, in a thermal power generation system using coal, coal ash such as clinker ash and fly ash (dust) is generated as a by-product by the combustion of coal.
Fly ash is collected with high efficiency (for example, 95% or more) mainly by a dust collector of a thermal power generation system. This fly ash is reused for cement materials, concrete admixtures, ground improvement materials and the like.

  In general, a thermal power generation system includes a denitration device that removes nitrogen oxides contained in exhaust gas obtained by burning coal, a heat exchange element that exchanges heat between the exhaust gas from which nitrogen oxides are removed, and combustion air. And a dust collector that collects fly ash from the exhaust gas from which nitrogen oxides have been removed (see, for example, Patent Document 1).

  The smoke emission treatment (thermal power generation) system described in Patent Document 1 includes a denitration device, a dust collector, and a treatment agent supply means for supplying a treatment agent for insolubilizing selenium (Se) in the exhaust gas, Selenium in the exhaust gas is removed.

JP-A-8-266855

  Here, in the denitration apparatus, a dry ammonia catalytic reduction method in which ammonia gas is injected as a reducing agent into the exhaust gas, and nitrogen oxides in the exhaust gas are decomposed into harmless nitrogen and water vapor by the action of the ammonia gas and the denitration catalyst. Is used.

  Since the heat exchange element is located on the downstream side of the denitration apparatus, a part of the heat exchange element may be corroded by the ammonia gas used in the denitration apparatus. When a part of the heat exchange element is corroded and dropped, a part of the dropped heat exchange element may be mixed in the fly ash, which may impair the quality of the fly ash.

  An object of this invention is to provide the thermal power generation system which can suppress mixing of the foreign material to a fly ash.

  The present invention relates to a thermal power generation system using coal, which includes a denitration device that removes nitrogen oxides contained in exhaust gas generated by coal combustion, and thermal energy of the exhaust gas from which nitrogen oxides have been removed by the denitration device. A heat exchange element for exchanging heat with combustion air, a dust collector for collecting fly ash contained in the exhaust gas heat-exchanged by the heat exchange element, and discharging the fly ash collected by the dust collector A hopper, a pressure transporter that transports the fly ash discharged by the hopper by the pressure of an air flow, and a discharge device that humidifies the fly ash transported by the pressure transporter and discharges the fly ash to the outside. The fly ash is provided in each of the hopper, the pressure transporter, and the discharge device, and passes through the fly ash. A mesh strainer that causes the mesh to remain, a switching device that switches each mesh strainer to one having a different roughness of each mesh, a flow rate of the fly ash transported by the pressure of the air flow, or a discharge from the discharge device The mesh strainer is switched to one having a different roughness of each mesh based on the measurement unit that measures the weight of the fly ash and the flow rate of the fly ash or the weight of the fly ash measured by the measurement unit. The present invention relates to a thermal power generation system including a control device that controls the switching device.

  According to the present invention, the thermal power generation system can automatically switch the mesh strainer to one having a different roughness of each mesh based on the flow rate of fly ash or the weight of fly ash. It can suppress that a foreign material mixes in the discharged fly ash.

  Moreover, it is preferable that the said mesh strainer is provided with the 1st mesh strainer whose space | interval of each mesh is 10-15 mm, and the 2nd mesh strainer whose space | interval of each mesh is 5-10 mm.

  In addition, when the flow rate of the fly ash measured by the measurement unit is lower than a predetermined flow rate, the control device is configured to switch the mesh strainer to one having a different roughness of each mesh. It is preferable to control the switching device.

  In addition, when the weight of the fly ash measured by the measuring unit is greater than a predetermined weight, the control device switches the mesh strainer to one having a different roughness of each mesh. It is preferable to control the switching device.

  ADVANTAGE OF THE INVENTION According to this invention, the thermal power generation system which can suppress mixing of the foreign material to fly ash can be provided.

It is a lineblock diagram showing the outline of thermal power generation system 1 which is one embodiment of the present invention. 2 is a configuration diagram showing an outline of a configuration of a thermal power generation system 1 after a hopper 260. FIG. It is a figure which shows the 1st mesh strainer 351 whose space | interval of each mesh is 5 mm. It is a figure which shows the 2nd mesh strainer 362 whose space | interval of each mesh is 15 mm. It is a figure which shows the 2nd mesh strainer 372 whose space | interval of each mesh is 5 mm. It is a figure which shows the 1st mesh strainer 371 whose space | interval of each mesh is 10 mm. It is a block diagram for demonstrating operation | movement of the thermal power generation system 1 of this embodiment.

  Below, the thermal power generation system which is one Embodiment of this invention is demonstrated, referring FIGS. 1-7. 1 and 2 are configuration diagrams showing an outline of a thermal power generation system 1 according to an embodiment of the present invention.

A thermal power generation system 1 shown in FIG. 1 is mainly used in a thermal power plant, and generates electric power by rotating a turbine with steam generated by burning coal.
Moreover, in the thermal power generation system 1, coal ash, such as clinker ash and fly ash, is produced as a by-product by burning coal.
According to the thermal power generation system 1, coal ash can be recovered from exhaust gas generated by burning coal.

  As shown in FIG. 1, the thermal power generation system 1 includes a coal bunker 20, a pulverized coal machine 30, a combustion boiler 40, an exhaust passage (flue) 50, a denitration device 60, an air preheater 70, and ventilation. Machine 77, heat recovery gas heater 80, electrostatic precipitator 90, induction fan 210, desulfurizer 220, reheating gas heater 230, desulfurizer fan 240, and chimney 250.

Hereinafter, each part of the thermal power generation system 1 will be described.
The coal bunker 20 stores coal supplied from a coal silo (not shown) by a coal transportation facility.
The pulverized coal machine 30 pulverizes the coal supplied from the coal bunker 20 via the coal feeder 25 to a fine particle size to form pulverized coal. The pulverized coal machine 30 supplies the formed pulverized coal to the combustion boiler 40.

  The combustion boiler 40 burns the pulverized coal supplied from the pulverized coal machine 30 together with the forcibly supplied air. By burning pulverized coal, coal ash such as clinker ash and fly ash is generated and exhaust gas is generated. As will be described later, fly ash is collected by the electrostatic precipitator 90.

The exhaust passage 50 is provided on the downstream side of the combustion boiler 40 and introduces exhaust gas generated in the combustion boiler 40 into the denitration device 60.
The denitration device 60 removes nitrogen oxides in the exhaust gas. Specifically, the denitration device 60 injects ammonia gas as a reducing agent into the exhaust gas at a relatively high temperature (300 ° C. to 400 ° C.), and converts nitrogen oxides in the exhaust gas into harmless nitrogen by the action of the denitration catalyst. Nitrogen oxides in the exhaust gas are removed by a so-called dry ammonia catalytic reduction method that decomposes into water vapor.

  The air preheater 70 includes a heat exchange element 75 inside. The heat exchange element 75 exchanges the heat energy of the exhaust gas from which nitrogen oxides have been removed by the denitration device 60 with the combustion air.

The ventilator 77 introduces the combustion air heat-exchanged by the air preheater 70 into the combustion boiler 40.
The heat recovery gas heater 80 recovers the exhaust gas heat-exchanged by the air preheater 70 and sends the exhaust gas after the heat recovery to the electric dust collector 90.

  The electric dust collector 90 collects coal ash such as clinker ash and fly ash in the exhaust gas with an electrode. The fly ash collected by the electric dust collector 90 is discharged by the hopper 260.

The induction fan 210 introduces the exhaust gas that has passed through the electrostatic precipitator 90 into the desulfurizer 220.
The desulfurization apparatus 220 sprays a mixed liquid of limestone and water on the exhaust gas, thereby absorbing the sulfur oxide contained in the exhaust gas into the mixed liquid, thereby generating a desulfurized gypsum slurry. The desulfurizer 220 generates desulfurized gypsum by dehydrating the desulfurized gypsum slurry.
The desulfurization gypsum recovery device 222 recovers the desulfurization gypsum generated by the desulfurization device 220.

The reheating gas heater 230 heats the exhaust gas from which the sulfur oxide has been removed by the desulfurization apparatus 220.
The desulfurization ventilator 240 introduces the exhaust gas heated by the reheating gas heater 230 into the chimney 250. The reheating gas heater 230 can efficiently discharge the heated exhaust gas from the chimney 250 by utilizing the chimney effect by heating the exhaust gas.

FIG. 2 is a configuration diagram showing an outline of the configuration after the hopper 260 of the thermal power generation system 1.
As shown in FIG. 2, the thermal power generation system 1 includes a hopper 260, a pressure transporter 270, a pressure blower 280, a transport pipe 290, a flow rate measuring device 300, a flywheel, in addition to the configuration described in FIG. 1. Ash silo 310, bag filter 320, dustless unloader 330, weight measuring device 340, mesh strainer 350, 360, 370, and switching device 380, 390, 400 are provided.

The hopper 260 discharges fly ash collected by the electrostatic precipitator 90 to the pressure transporter 270. The downstream side of the hopper 260 branches into a plurality of paths (six in FIG. 2). Each branched path is connected to the pressure transporter 270.
The pressure transporter 270 is provided corresponding to each path of the hopper 260, and transports fly ash discharged by each path of the hopper 260 to the fly ash silo 310 by the pressure of the air flow generated by the pressure blower 280. .

The pressure blower 280 generates an air flow and introduces it into the transport pipe 290.
The transport pipe 290 transports fly ash discharged from the pressure transporter 270 from the pressure transporter 270 to the fly ash silo 310 by the pressure of the air flow generated by the pressure blower 280.

  The flow rate measuring device 300 is provided in the transport pipe 290 and measures the flow rate of fly ash transported by the pressure of the air flow. The flow rate measuring device 300 transmits the measured value of the flow rate of the fly ash to the control device 410 (see FIG. 7).

The fly ash silo 310 stores the fly ash transported by the pressure transporter 270.
Bag filter 320 cleans the air used to transport fly ash to fly ash silo 310.

  The dustless unloader 330 is provided on the downstream side of the fly ash silo 310, humidifies the fly ash stored in the fly ash silo 310, and discharges the fly ash to the outside (for example, the jet pack car 420).

  The weight measuring device 340 is provided in the dustless unloader 330 and measures the weight of fly ash discharged from the dustless unloader 330. The weight measuring device 340 transmits the measured fly ash weight value to the control device 410 (see FIG. 7).

The mesh strainers 350, 360, and 370 are formed of metal in a mesh (mesh) shape, and allow the fly ash to pass therethrough and leave foreign matter.
Here, the foreign matter is discharged together with fly ash, and for example, a part of the heat exchange element 75 is corroded and dropped by the ammonia gas used in the denitration apparatus 60.

  The mesh strainer 350 is provided in each of a plurality of paths on the downstream side of the hopper 260. The mesh strainer 350 allows the fly ash discharged from the hopper 260 to pass therethrough and leave foreign matter.

  The mesh strainer 360 is provided in each of a plurality of paths on the downstream side of the pressure transporter 270. The mesh strainer 360 allows the fly ash discharged from the pressure transporter 270 to pass therethrough and leave foreign matter. That is, the mesh strainer 360 is provided for the purpose of leaving foreign matter that has passed through the mesh strainer 350.

  The mesh strainer 370 is provided on the downstream side of the dustless unloader 330. The mesh strainer 370 allows the fly ash discharged from the dustless unloader 330 to pass therethrough and leave foreign matter. That is, the mesh strainer 370 is provided for the purpose of leaving foreign matter that has passed through the mesh strainers 350 and 360.

  The mesh strainers 350, 360, and 370 include first mesh strainers 351, 361, and 371 that have coarse (wide) intervals between meshes, and second mesh strainers 352, 362, and 372 that have fine (narrow) intervals between meshes. It is equipped with.

The interval between the meshes in the first mesh strainers 351, 361, 371 is preferably about 5 mm to 10 mm, and more preferably 5 mm.
The interval between the meshes in the second mesh strainer 352, 362, 372 is preferably about 10 mm to 15 mm, and more preferably 10 mm.

3-6 is a figure which shows the specific example of the mesh strainer 350,360,370. FIG. 3 is a diagram illustrating a first mesh strainer 351 in which the interval between the meshes is 5 mm, and FIG. 4 is a diagram illustrating the second mesh strainer 362 in which the interval between the meshes is 15 mm.
FIG. 5 is a diagram showing a second mesh strainer 372 in which the mesh interval is 5 mm, and FIG. 6 is a diagram showing the first mesh strainer 371 in which the mesh interval is 10 mm.

The switching devices 380, 390, and 400 switch the mesh strainers 350, 360, and 370 to those having different meshes.
Specifically, the switching devices 380, 390, and 400 include a storage unit (not shown) that stores a plurality of mesh strainers 350, 360, and 370, and a drive mechanism (not shown). Then, the switching devices 380, 390, and 400 collect the first mesh strainers 351, 361, and 371 by the driving mechanism and attach the second mesh strainers 352, 362, and 372 stored in the storage unit.

FIG. 7 is a block diagram for explaining the operation of the thermal power generation system 1 of the present embodiment. As shown in FIG. 7, the thermal power generation system 1 includes a control device 410 in addition to the configuration described in FIGS. 1 and 2.
The control device 410 changes the mesh strainers 350, 360, and 370 with different mesh roughness based on the fly ash flow measured by the flow meter 300 or the fly ash weight measured by the weight meter 340. The switching devices 380, 390, and 400 are controlled to switch to

Specifically, when the flow rate of fly ash measured by the flow rate measuring device 300 is lower than a predetermined flow rate, the control device 410 controls the mesh strainers 350, 360, and 370 so that the roughness of each mesh is increased. The switching devices 380, 390, and 400 are controlled to switch to different ones.
Here, as the predetermined flow rate, it is preferable to use the flow rate of the exhaust gas flowing through the transport pipe 290 in a state where almost no foreign matter is mixed.

In addition, when the weight of the fly ash measured by the weight measuring device 340 is greater than a predetermined weight, the control device 410 changes the mesh strainers 350, 360, and 370 to have different mesh roughness. The switching devices 380, 390, and 400 are controlled so as to be switched.
Here, the predetermined weight is preferably the weight of fly ash measured by the weight measuring device 340 in a state where almost no foreign matter is mixed.

According to the thermal power generation system 1 of this embodiment, the following effects are produced, for example.
In the thermal power generation system 1 according to the present embodiment, the control device 410 uses the mesh strainers 350, 360, and 360 based on the fly ash flow measured by the flow meter 300 or the fly ash weight measured by the weight meter 340. The switching devices 380, 390, and 400 are controlled so that 370 is switched to a mesh having a different roughness.

  Accordingly, the thermal power generation system 1 can automatically switch the mesh strainers 350, 360, and 370 to those having different meshes based on the flow rate of fly ash or the weight of fly ash. In addition, foreign matters can be prevented from entering the fly ash discharged to the outside (for example, the jet pack vehicle 420).

  In addition, when the flow rate of fly ash measured by the flow rate measuring device 300 is lower than a predetermined flow rate, the control device 410 according to the present embodiment causes the mesh strainers 350, 360, and 370 to have a roughness of each mesh. The switching devices 380, 390, and 400 are controlled so as to switch to different ones.

  Here, when the flow rate of fly ash is lower than the predetermined flow rate, it is considered that there is a high possibility that foreign matter is mixed in the exhaust gas (fly ash) flowing through the transport pipe 290. When the flow rate of fly ash is lower than a predetermined flow rate, the thermal power generation system 1 of the present embodiment causes the mesh strainers 350, 360, and 370 to have a mesh roughness of the mesh by the switching devices 380, 390, and 400. Since it switches to a different thing, it can suppress that a foreign material mixes in fly ash more suitably.

In addition, when the weight of the fly ash measured by the weight measuring device 340 is greater than a predetermined weight, the control device 410 according to the present embodiment causes the mesh strainers 350, 360, and 370 to have a roughness of each mesh. The switching devices 380, 390, and 400 are controlled so as to switch to different ones.
Here, when the weight of the fly ash is greater than the predetermined weight, it is considered that there is a high possibility that foreign matter is mixed in the fly ash in the dustless unloader 330. The thermal power generation system 1 according to the present embodiment switches the mesh strainers 350, 360, and 370 to those having different meshes by the switching devices 380, 390, and 400 when the weight exceeds the predetermined weight. More preferably, foreign matters can be prevented from entering the fly ash.

  As mentioned above, although preferred embodiment of this invention was described, this invention can be implemented with a various form, without being limited to embodiment mentioned above.

1 Thermal Power Generation System 60 Denitration Device 75 Heat Exchange Element 90 Electric Dust Collector (Dust Collector)
260 Hopper 270 Pressure transporter 300 Flow meter (Measurement unit)
330 Dustress unloader (discharge device)
340 Weighing instrument (measurement unit)
350, 360, 370 Mesh strainer 380, 390, 400 Switching device 410 Control device

Claims (4)

A thermal power generation system using coal,
A denitration device that removes nitrogen oxides contained in exhaust gas generated by coal combustion;
A heat exchange element for exchanging heat energy of the exhaust gas from which nitrogen oxides have been removed by the denitration device with combustion air;
A dust collector for collecting fly ash contained in the exhaust gas heat-exchanged by the heat-exchange element;
A hopper for discharging the fly ash collected by the dust collector;
A pressure transporter for transporting the fly ash discharged by the hopper by the pressure of an air flow;
A discharge device for humidifying the fly ash transported by the pressure transporter and discharging it to the outside,
A mesh strainer that is provided in each of the hopper, the pressure transporter, and the discharge device, allows the fly ash to pass therethrough, and leaves foreign matter,
A switching device for switching each mesh strainer to one having a different roughness of each mesh;
A measurement unit that measures the flow rate of the fly ash transported by the pressure of the air flow or measures the weight of the fly ash discharged from the discharge device;
Thermal power comprising: a control device that controls the switching device to switch the mesh strainer to one having a different roughness of each mesh based on the flow rate of the fly ash or the weight of the fly ash measured by the measurement unit Power generation system.   2. The thermal power generation system according to claim 1, wherein the mesh strainer includes a first mesh strainer in which a mesh interval is 10 to 15 mm and a second mesh strainer in which a mesh interval is 5 to 10 mm.   When the flow rate of the fly ash measured by the measurement unit is lower than a predetermined flow rate, the control device switches the mesh strainer to one having a different mesh roughness. The thermal power generation system according to claim 1, wherein the thermal power generation system is controlled.   When the weight of the fly ash measured by the measuring unit is greater than a predetermined weight, the control device is configured to switch the mesh strainer to one having a different mesh roughness. The thermal power generation system according to claim 1, wherein the thermal power generation system is controlled.

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