JP4906495B2 - Boiler equipment and feeder control method for conveying ash to ash treatment equipment - Google Patents

Description

  The present invention relates to a boiler facility that collects ash generated from a boiler with a dust collector and transports the collected ash to the ash treatment facility side with a feeder, and a feeder control method that transports ash to the ash treatment facility side.

  In a fluidized bed (fluidized bed) boiler that blows air from below and floats (flows) the coal and fluid medium (bed material) and burns the suspended coal, coal is applied under pressure to increase combustion efficiency. A pressurized fluidized bed boiler for burning is known. Also, there is known a combined power generation system that uses such a pressurized fluidized bed boiler to drive (rotate) a steam turbine and a gas turbine (see, for example, Patent Document 1).

In this combined power generation system, water is supplied to a heat transfer pipe disposed in a pressurized fluidized bed boiler to generate steam, and the steam turbine is driven by the steam. On the other hand, the ash in the combustion gas discharged from the pressurized fluidized bed boiler is collected by a dust collector, and the gas turbine is driven by the dedusted combustion gas. Further, the ash collected by the dust collector is conveyed (transferred) to the ash treatment facility by the screw feeder, and high-temperature cooling water for cooling the ash is supplied into the shaft of the screw feeder.
Japanese Patent Laid-Open No. 08-114305

  By the way, in the combined power generation system as described above, in order to obtain an ash treatment amount corresponding to the load (output) of the pressurized fluidized bed boiler, the conveying speed (rotational speed) of the screw feeder is set to the load of the pressurized fluidized bed boiler. It was controlled in proportion. For this reason, if the amount of ash dust collected by the dust collector exceeds the amount of ash transported by the screw feeder for some reason, ash accumulates on the hopper of the dust collector and the system may stop. On the other hand, if the conveying speed of the screw feeder is excessively high relative to the amount of ash dust collected by the dust collector, the ash will not be sufficiently cooled, and it will be necessary to enhance the heat resistance of the ash treatment equipment and the power of the screw feeder. Costs increase (becomes inefficient).

  Accordingly, the present invention provides a boiler facility capable of efficiently cooling ash without depositing ash in the dust collector, and a feeder control method for conveying ash to the ash treatment facility side. Objective.

In order to achieve the above object, the invention described in claim 1 is directed to a boiler that burns fuel, a dust collector that collects ash generated from the boiler, and an ash that is supplied with cooling water and collected by the dust collector. And a feeder that conveys to the ash treatment facility while cooling with cooling water, and in a normal state, a first control that defines a conveying speed of the feeder corresponding to the output of the boiler When the ash content of the fuel supplied to the boiler is increased according to the line, the conveyance speed of the feeder is controlled according to the second control line that is moved in parallel to the high speed side. Control means for controlling the conveying speed of the feeder according to a third control line that controls the conveying speed and moves the first control line to the low speed side when the amount of ash in the fuel becomes low . That It is a symptom.
(Function)
When fuel with a high ash content is supplied to the boiler, the feeding speed of the feeder is controlled according to the second control line, which is a parallel movement of the first control line to the high speed side, and fuel with a low ash content is supplied to the boiler. Then, the feeding speed of the feeder is controlled according to the third control line in which the first control line is moved in parallel to the low speed side .

According to a second aspect of the present invention, in the boiler facility according to the first aspect, when the load of the boiler is increased and fluctuated, the control unit controls the conveying speed of the feeder to a maximum speed, and this state is controlled by the boiler. This is continued until the combustion state becomes stable, and thereafter, the feeding speed of the feeder is lowered at a constant descent rate, and the feeding speed of the feeder is controlled according to the first control line .
(Function)
When increasing the load on the boiler , the conveying speed of the feeder is controlled by the control means so that the amount of ash dust collected by the dust collector increases and the conveying amount by the feeder also increases.

According to a third aspect of the present invention, in the boiler facility according to the first or second aspect , the boiler is a fluidized bed boiler, and the control means transports the feeder when a fluid medium is put into the boiler. The speed is controlled to the maximum speed, and this state is continued until the combustion state of the boiler is stabilized. Thereafter, the transport speed of the feeder is decreased at a constant rate of decrease, and the transport speed of the feeder is followed according to the first control line. It is characterized by controlling.
(Function)
When the fluidized medium is put on the fluidized bed boiler, the conveying speed of the feeder is controlled by the control means so that the amount of ash dust collected by the dust collector is increased and the amount of conveyance by the feeder is also increased.

The invention according to claim 4 is a feeder control method for conveying the ash generated from the boiler and collected by the dust collector to the ash treatment facility side while cooling with cooling water, and in the normal state, the output of the boiler The feeder transport speed is controlled in accordance with a first control line that defines the feeder transport speed correspondingly, and when the ash content of the fuel supplied to the boiler becomes high, the first control line is According to the second control line moved in parallel to the high speed side, the feeder transport speed is controlled, and when the fuel ash content becomes low, the first control line is moved in parallel to the low speed side. A feeder control method for transporting ash to an ash treatment facility, wherein the feeder transport speed is controlled according to a line .

According to the first and fourth aspects of the present invention, in the normal state, the transport speed of the feeder is controlled in accordance with the first control line, so that the transport speed and the ash treatment amount according to the output of the boiler can be obtained. In addition, when fuel with a high ash content is supplied to the boiler, the feeder transport speed is controlled according to the second control line on the high speed side. It is possible to prevent deposition. On the other hand, when fuel with a low ash content is supplied to the boiler, the transport speed of the feeder is controlled according to the third control line on the low speed side . For this reason, it can be prevented that the ash is not sufficiently cooled because the transport speed of the feeder is excessively high with respect to the ash dust collection amount. That is, the ash can be efficiently cooled, and the power cost of the feeder can be kept low.

According to invention of Claim 2 , if the load of a boiler fluctuates, the conveyance speed of a feeder will be controlled noting that ash dust collection amount will fluctuate. For this reason, even if the ash dust collection amount fluctuates due to fluctuations in the boiler load, it is possible to prevent ash from accumulating in the dust collector and the feeder transport speed from becoming excessively high relative to the ash dust collection amount. It becomes possible to do. Moreover, the feeder transport speed is controlled to the maximum speed until the combustion state of the boiler is stabilized, preventing ash from accumulating in the dust collector even if the amount of ash dust collection is maximized due to complete combustion or the like. It becomes possible.

According to the third aspect of the present invention, the conveying speed of the feeder is controlled on the assumption that the ash dust collection amount fluctuates when the fluid medium is put into the fluidized bed boiler. For this reason, even if the ash dust collection amount fluctuates when the fluidized medium is put into the fluidized bed boiler, the ash accumulates in the dust collector, and the feeder transport speed becomes excessively high with respect to the ash dust collection amount. This can be prevented. In addition, the feeder conveyance speed is controlled to the maximum speed until the combustion state of the boiler is stabilized, so even when the fluid medium is spread, the fine fluid medium is scattered and the ash dust collection amount is maximized. It is possible to prevent ash from accumulating in the dust collector.

  The present invention will be described below based on the illustrated embodiments.

  Drawing 1 is a mimetic diagram showing boiler equipment 1 concerning this embodiment, and its peripheral equipment. The boiler facility 1 is installed in a pressurized fluidized bed combined power plant, and mainly includes a pressurized fluidized bed boiler (boiler) 2, a dust collector 3, a screw feeder (feeder) 4, and a control device 5 (control means). It has.

  The pressurized fluidized bed boiler 2 is a boiler that supplies combustion air from below to float the fuel and the fluid medium, and burns the suspended fuel under pressure. In this embodiment, coal, limestone, and water are used. Is supplied as fuel. A heat transfer tube 21 is disposed in the pressurized fluidized bed boiler 2, water is supplied to the heat transfer tube 21 to generate steam, and the steam is sent to the steam turbine 6 to drive the steam turbine 6. On the other hand, the combustion gas discharged from the pressurized fluidized bed boiler 2 collects the ash C by the dust collector 3, and the deashed (dedusted) combustion gas is sent to the gas turbine 7 to drive the gas turbine 7. . Each generator 8 generates electric power by rotational driving of the steam turbine 6 and the gas turbine 7.

  The dust collector 3 is a dust collector that collects the ash C generated from the pressurized fluidized bed boiler 2, and is schematically configured as shown in FIG. 2. That is, a plurality of cyclones 32 are disposed in a substantially cylindrical hopper 31, and combustion gas flows into the cyclone 32 from an inlet 31 a at the top of the hopper 31 through an inflow pipe 33. . The cyclone 32 generates a centrifugal force and causes the ash C in the combustion gas to flow out from the outlet 32a by the centrifugal force. And the ash C which flowed out from the cyclone 32 falls to the lower part of the hopper 31, and is discharged | emitted from the discharge port 31b to the screw feeder 4 side. On the other hand, the combustion gas deashed by the cyclone 32 is sent from the outlet 31c above the hopper 31 to the gas turbine 7 side.

  The screw feeder 4 is a feeder that conveys the ash C discharged from the dust collector 3 to an ash treatment facility such as a relay hopper or an ash silo. The screw feeder 4 is constituted by a screw type conveyor, and high temperature cooling water (cooling water) is supplied into the shaft 41 so that the ash C is conveyed to the ash treatment facility side while being cooled with the high temperature cooling water. It has become. Here, the high-temperature cooling water is replenished (supplied) from the water supply system, and the water whose temperature has risen by performing heat exchange in each system is returned to the water supply system. For this reason, an increase in the temperature of the high-temperature cooling water leads to an increase in the thermal efficiency of the power plant. Further, the conveying speed (rotational speed) of the screw feeder 4 is controlled by the control device 5.

  As shown in FIG. 3, the control device 5 mainly includes a boiler output receiving unit 51, a fluctuation information input unit 52, a command output unit 53, a timer 54, and a CPU (Central Processing Unit) 55 for controlling these. And. The boiler output receiving unit 51 is a receiving unit that receives the output of the pressurized fluidized bed boiler 2 from the outside. The fluctuation information input unit 52 is an interface that receives the fluctuation information of the ash dust collection amount by the dust collector 3 from the outside, and the command output unit 53 is an interface that transmits a conveyance speed control command to the screw feeder 4.

  As shown by the first control line L <b> 1 in FIG. 4, the control device 5 uses basic control to control the conveyance speed of the screw feeder 4 to be proportional to the output of the pressurized fluidized bed boiler 2. That is, the output of the pressurized fluidized bed boiler 2 is received by the boiler output receiving unit 51, and a control command for the conveyance speed suitable for the boiler output is transmitted from the command output unit 53 to the screw feeder 4 according to the first control line L 1. Here, for example, if the conveying speed of the screw feeder 4 is too fast with respect to the amount of the ash C from the pressurized fluidized bed boiler 2 (dust collector 3), the cooling of the ash C becomes insufficient (the temperature of the high-temperature cooling water is low). Does not increase) and the thermal efficiency decreases. For this reason, the first control line L1 can transport all the ash C from the pressurized fluidized bed boiler 2 (dust collector 3) without any stagnation (the ash C does not accumulate on the hopper 31), and the ash C can be transferred to the relay hopper It is set so that it can be cooled to the lowest possible temperature below the heat-resistant temperature (so that the temperature of the high-temperature cooling water is increased as much as possible). The same applies to control lines L2 and L3 described later.

  Further, the control device 5 controls the conveyance speed of the screw feeder 4 so that the conveyance amount of the ash C by the screw feeder 4 follows the fluctuation of the ash dust collection amount by the dust collector 3 (variation of the generation amount of ash). That is, when a factor (event) that increases the amount of ash dust collected by the dust collector 3 occurs, the conveyance speed of the screw feeder 4 is controlled to increase so that the conveyance amount of ash C by the screw feeder 4 also increases. On the other hand, when a factor that reduces the amount of ash dust collected by the dust collector 3 occurs, the conveyance speed of the screw feeder 4 is controlled to decrease so that the amount of ash C conveyed by the screw feeder 4 also decreases.

  Specifically, the conveyance speed of the screw feeder 4 is controlled in the following case.

  First, the ash content of the fuel supplied to the pressurized fluidized bed boiler 2 changes. In this case, since the amount of ash in the combustion gas changes even if the fuel input amount is the same, the conveying speed of the screw feeder 4 is controlled on the assumption that the amount of ash dust collected by the dust collector 3 varies. Specifically, based on the fuel ash content (variation information) input to the variation information input unit 52, the conveyance speed is controlled so that proportional control is performed according to the ash content. For example, when the amount of ash content is changed to high fuel, the amount of ash dust collected by the dust collector 3 increases, and therefore the screw feeder is moved according to the second control line L2 in which the first control line L1 is translated upward (high speed side). 4 is controlled. Thereby, the conveyance amount by the screw feeder 4 also increases. Similarly, when the amount of ash content is changed to low fuel, the amount of ash dust collected by the dust collector 3 decreases, so the screw is moved according to the third control line L3 in which the first control line L1 is moved downward (low speed side) in parallel. The conveyance speed of the feeder 4 is controlled. Thereby, the conveyance amount by the screw feeder 4 also falls.

  Secondly, the load on the pressurized fluidized bed boiler 2 fluctuates upward. In this case, the amount of air is increased prior to the amount of fuel to promote complete combustion in the pressurized fluidized bed boiler 2, the gas velocity of the fluidized bed is increased, and the ash C is emptied (free board). It becomes easy to scatter. Further, in the dust collector 3, the centrifugal force is increased by the increase of the gas flow rate. As a result, the conveying speed of the screw feeder 4 is controlled assuming that the amount of ash dust collected by the dust collector 3 fluctuates upward.

  Specifically, based on the load increase information (variation information) input to the variation information input unit 52, the conveyance speed of the screw feeder 4 is controlled as shown in FIG. That is, the conveying speed of the screw feeder 4 is controlled to the maximum speed, and this state is continued until the combustion state of the pressurized fluidized bed boiler 2 is stabilized. Here, the maximum speed means that all ash C can be transported without delay even when the amount of ash dust collected by the dust collector 3 becomes maximum during the complete combustion as described above, that is, the ash C in the hopper 31. The rotation speed is such that no deposition occurs. The time until the combustion state of the pressurized fluidized bed boiler 2 is stabilized is predicted and set in advance according to the characteristics of the pressurized fluidized bed boiler 2 and the fuel. Thus, the conveyance amount by the screw feeder 4 increases by setting the conveyance speed of the screw feeder 4 to the maximum speed. Thereafter, the conveying speed of the screw feeder 4 is gradually lowered at a constant rate of drop and returned to normal speed control, that is, control (basic control) proportional to the output of the pressurized fluidized bed boiler 2 as described above. Here, the reason why the conveying speed is gradually decreased is to prevent the temperature of the ash C on the inlet side (the discharge port 31b side) of the screw feeder 4 from being lowered.

  Thirdly, when the power generation unit including the boiler facility 1 is started, a fluid medium is put into the pressurized fluidized bed boiler 2. In this case, since the fluid medium is put in while rotating the air in the pressurized fluidized bed boiler 2, the fine fluid medium is scattered to the empty tower and collected by the dust collector 3. At this time, since the output of the pressurized fluidized bed boiler 2 is zero, the conveyance speed of the screw feeder 4 is controlled to the minimum in the basic control as described above. For this reason, when sticking a fluid medium, the conveyance speed of the screw feeder 4 is controlled on the assumption that the amount of ash dust collected by the dust collector 3 fluctuates upward.

  Specifically, based on the sticking information (variation information) input to the variation information input unit 52, the conveying speed of the screw feeder 4 is controlled as shown in FIG. 5 as in the second case. Thereby, when the ash dust collection amount by the dust collector 3 increases due to the fluid medium being stuck, the conveyance speed of the screw feeder 4 becomes the maximum speed, and the conveyance amount by the screw feeder 4 increases. Here, the time for maintaining the maximum speed is set in advance based on the size of the pressurized fluidized bed boiler 2 and the time required for installation.

  By the way, the input of the fluctuation information to the fluctuation information input unit 52 may be manual or automatic. That is, an input panel or the like is provided, and the fuel ash content, boiler load increase information, or fluid medium sticking information is manually input from the input panel. Alternatively, the ash content is calculated at the fuel input section, and the calculation result is directly input (transmitted) from the input section to the fluctuation information input section 52, or the boiler load increase information and the fluid medium installation information are stored in the boiler facility 1. It may be directly input (transmitted) from the control device to the fluctuation information input unit 52.

  Next, the operation of the boiler equipment 1 having such a configuration and the control method of the screw feeder 4 will be described.

  First, in the normal state, the control device 5 performs basic control on the conveying speed of the screw feeder 4 based on the first control line L1 as described above. That is, it controls so that the conveyance speed of the screw feeder 4 is proportional to the output of the pressurized fluidized bed boiler 2. Next, when an event occurs in which the amount of ash dust collected by the dust collector 3 fluctuates, the conveying speed of the screw feeder 4 is controlled by the control device 5 so that the conveying amount of the screw feeder 4 follows the fluctuation. That is, when the ash content of the fuel to the pressurized fluidized bed boiler 2 changes, the conveying speed of the screw feeder 4 is controlled according to the second control line L2 and the third control line L3 as described above. When the load of the pressurized fluidized bed boiler 2 fluctuates upward or when the fluidized medium is stuck in the pressurized fluidized bed boiler 2, the conveying speed of the screw feeder 4 is set to the maximum speed for a certain time as described above. After that, the basic control is performed by reducing the speed to the basic control speed at a constant descent rate.

  As described above, according to the control method of the boiler equipment 1 and the screw feeder 4, the conveyance speed of the screw feeder 4 is controlled so that when the amount of ash dust collected by the dust collector 3 increases, the conveyance amount by the screw feeder 4 also increases. Therefore, even if the amount of ash dust collected by the dust collector 3 increases, the ash C can be prevented from accumulating in the hopper 31 of the dust collector 3. On the other hand, when the ash dust collection amount by the dust collector 3 decreases, the conveyance speed of the screw feeder 4 is controlled so that the conveyance amount by the screw feeder 4 also decreases. For this reason, it is possible to prevent the ash C from being sufficiently cooled because the conveying speed of the screw feeder 4 is excessively high with respect to the ash dust collection amount. That is, the ash C can be efficiently cooled, and the power cost of the screw feeder 4 can be kept low.

  Specifically, the amount of fuel ash to the pressurized fluidized bed boiler 2 changes, the load of the pressurized fluidized bed boiler 2 fluctuates, or the fluidized medium is put into the pressurized fluidized bed boiler 2. Even if the amount of ash dust collected by the dust collector 3 fluctuates, the conveying speed of the screw feeder 4 is controlled as described above. For this reason, accumulation of the ash C in the hopper 31 and inefficient cooling of the ash C can be prevented.

  Although the embodiment of the present invention has been described above, the specific configuration is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention, the present invention is not limited to this embodiment. include. For example, in this embodiment, the basic control is to control the conveyance speed of the screw feeder 4 in proportion to the output of the pressurized fluidized bed boiler 2 according to the first control line L1, but other control methods are used. May be used as basic control. For example, as shown in FIG. 6, when the output of the pressurized fluidized bed boiler 2 is less than or equal to a predetermined output, the conveying speed of the screw feeder 4 is controlled to be proportional to the boiler output, and the boiler output is higher than the predetermined output. When it is large, the basic control may be to keep the conveying speed of the screw feeder 4 constant. Further, in this embodiment, the control device 5 as the control means is separately provided, but a control circuit as the control means may be provided in the control device of the boiler facility 1 or the like. Furthermore, although the case where the boiler was the pressurized fluidized bed boiler 2 was described, it is needless to say that other boilers may be used.

It is a schematic diagram which shows the boiler equipment which concerns on this embodiment, and its peripheral equipment. It is sectional drawing which shows schematic structure of the dust collector in the boiler installation of FIG. It is a schematic block diagram of the control apparatus in the boiler installation of FIG. It is a figure which shows the relationship (control line) of the boiler output by the control apparatus of FIG. 3, and the rotational speed of a screw feeder. It is a figure which shows the change of the rotational speed of the screw feeder by the control apparatus of FIG. 3 at the time of the load increase of a boiler, and the sticking of a fluid medium. It is a figure which shows the other relationship (basic control line) of the boiler output by the control apparatus of FIG. 3, and the rotational speed of a screw feeder.

Explanation of symbols

1 Boiler equipment 2 Pressurized fluidized bed boiler (boiler)
21 Heat Transfer Tube 3 Dust Collector 31 Hopper 31a Inlet 31b Outlet 31c Outlet 32 Cyclone 32a Outlet 33 Inlet Pipe 4 Screw Feeder (Feeder)
41 axis 5 control device (control means)
6 Steam turbine 7 Gas turbine 8 Generator C Ash

Claims (4)

A boiler that burns fuel,
A dust collector for collecting ash generated from the boiler;
A boiler facility comprising: a feeder that is supplied with cooling water and transports ash collected by the dust collector to the ash treatment facility side while cooling with the cooling water;
In a normal state, when the feeder transport speed is controlled according to a first control line that defines the feeder transport speed corresponding to the output of the boiler, and the ash content of the fuel supplied to the boiler increases. Controls the feeding speed of the feeder according to a second control line obtained by moving the first control line in parallel to the high speed side, and when the ash content of the fuel is low, the first control line is set to the low speed side. Boiler equipment comprising control means for controlling the conveying speed of the feeder in accordance with a third control line moved in parallel with each other. When the load of the boiler rises and fluctuates, the control means controls the feeding speed of the feeder to the maximum speed, continues this state until the combustion state of the boiler is stabilized, and then keeps the feeding speed of the feeder constant. The boiler equipment according to claim 1, wherein the feed rate of the feeder is controlled according to the first control line . The boiler is a fluidized bed boiler, and the control means controls the feeding speed of the feeder to the maximum speed when the fluid medium is put into the boiler, and continues this state until the combustion state of the boiler is stabilized. and, thereafter, lowering the conveying speed of the feeder at a constant rate of descent, according to any one of claims 1 or 2, characterized in that to control the conveying speed of the feeder according to the first control line Boiler equipment. A feeder control method for conveying ash generated from a boiler and collected by a dust collector to the ash treatment facility while cooling with cooling water,
In a normal state, when the feeder transport speed is controlled according to a first control line that defines the feeder transport speed corresponding to the output of the boiler, and the ash content of the fuel supplied to the boiler increases. Controls the feeding speed of the feeder according to a second control line obtained by moving the first control line in parallel to the high speed side, and when the ash content of the fuel is low, the first control line is set to the low speed side. A feeder control method for transporting ash to the ash treatment facility side, wherein the transport speed of the feeder is controlled in accordance with a third control line that is moved in parallel .

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