JPS6020021A - Fuel device for power plant with combustion of coal - Google Patents

Abstract

PURPOSE:To eliminate a delay in crushing of coal in coal pulverizer and perform a superior feeding of fuel by a method wherein classifying vanes installed in the coal pulverizer are enabled to rotate and a degree of opening of the classifying vanes is controlled in advance for their opening and closing operation. CONSTITUTION:A mill 6 has mill balls 7 therein, and these mill balls 7 are rotatably arranged on a mill table 9 to be driven by a gear reducer 8. The gear reducer 8 decreases the rotating force of an electric motor 10 to transmit the force to the mill table 9. The mill 6 has classifying vanes 11 to be rotatably installed on the top thereof. These classifying vanes 11 are connected to a connector ring 12, and when a driving force from a control drive 13 is transmitted to the connector ring 12 through a lever mechanism 14, the classifying vanes 11 are set to have a desired degree of opening in response to the driving distance. In this way, it is possible to perform a more superior combustion control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a fuel system for a coal-fired couplant, in particular,
The present invention relates to a fuel system for a coal-fired couplant that is suitable for movable classifier vanes of a pulverized coal machine and eliminates delays in pulverized coal.

[Background of the invention]

This type of coal-fired couplant fuel system converts coal supplied from a coal feeder into pulverized coal using a pulverizer, transports this pulverized coal through primary air, and supplies fuel to the boiler via a burner. The system takes in information on the amount of coal supplied by the coal feeder and the amount of coal supplied by the coal feeder, and based on this information, drives and controls the fuel supply device in advance in response to requests for changes in the boiler load. The fuel tank is configured to include a control device that adjusts the amount of fuel supplied.

The pulverized coal machine (hereinafter simply referred to as "mill") is equipped with a fixed classifier vane, which can adjust the amount of pulverized coal recirculated within the mill and the pulverized coal particle size. be.

According to the above-mentioned fuel system, since the amount of coal fed and the amount of fuel are driven in advance, the control characteristics are improved. Since it takes about three mills for the coal to be output from the mill, there has been a drawback that the pulverization delay of the coal mill cannot be fundamentally improved.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel system for a coal-fired couplant that eliminates the drawbacks of the prior art described above, reduces the delay in pulverizing coal in a mill to one, and performs good fuel control.

[Summary of the invention]

In order to achieve the above object, the present invention uses a classifier vane provided in the mill as a movable blade, so that the coal held in the mill can be carried out in advance.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a configuration diagram showing an embodiment of a fuel system for a coal-fired couplant according to the present invention. In FIG. 1, a fuel system 100 for a coal-fired couplant includes a fuel supply device 200 that converts coal into pulverized coal and supplies it to a boiler via a burner, and a control device that controls the drive of this fuel supply device 200 to adjust the amount of fuel supplied. The device 300 is comprised of the following.

The fuel supply device 200 converts coal supplied by a coal feeder into pulverized coal by a mill 6, conveys this pulverized coal by primary air, supplies it to a boiler via a burner, and supplies it to a boiler through a burner. A classifier vane 11 provided in the classifier vane 11 is movable.

Further, the control device 300 receives information on the amount of coal supplied by the coal feeder and the amount of air, and based on this information, the control device 300 controls the fuel supply device 200 in advance in response to a boiler load change request. The amount of fuel supplied can be adjusted by controlling the drive.

Here, the fuel supply device 200 will be explained in more detail with reference to FIGS. 2 to 4.

The coal feeder 2 includes a rotation detector 3 that detects the speed of the belt conveyor, and a load cell 4 that measures the weight of the coal placed on the belt conveyor. can be supplied to mill 6.

The mill 6 is equipped with a mill ball 7 therein.
These mill balls 7 are movably arranged on a mill table 9 driven by a reduction gear 8. The reducer 8 reduces the rotational force of the electric motor 10 and transmits it to the mill table 9. In addition, the mill 6 has a classifier vane 11 on its upper part.
are rotatably provided, and these classifier vanes 11
is connected to the coupling ring 12, and the control drive 1
The driving force from 3 is applied to the connecting ring 1 via the lever mechanism 14.
2, the classifier base 7
11 is configured to have a predetermined opening degree.

Further, at the bottom of the mill 6, there is a rod damper 15 containing a secondary ventilation fan, a secondary ventilation fan 16, and an orifice 17 provided downstream thereof.
and a control drive 18 for driving the damper 15. A primary air supply means is connected thereto.

The operation of the fuel system configured as described above will be described below.

Coal from bunker 1 is sent to coal feeder 2.

The weight of the coal on a belt provided in the coal feeder 2 is detected by a load cell 4. Further, the rotation speed of the belt of the coal feeder 2 is detected by a rotation detector 3.

By multiplying these weight values and the number of rotations, the amount of coal fed on a weight basis can be detected.

On the other hand, coal from the coal feeder 2 is fed onto the vane and into the simulator 6, and is pulverized into fine powder by the mill balls 7 in the mill 6. The pulverized coal thus produced is conveyed to the classifier vane 11 together with primary air for conveyance as shown by arrow G in the figure. The pulverized coal classified by the classifier 11 that exceeds a predetermined size passes through a recirculation path as indicated by arrow H in the figure and is pulverized again. The other fine pulverized coal is sent through a pulverized coal conveyance path to an excess burner as shown by arrow J in the figure, and is supplied into the boiler and burned.

The above-mentioned conveying air is controlled by giving a control command to the air control drive 18 for controlling the amount of air necessary for pulverized coal combustion, and controlling the opening degree of the air damper 15 containing the ventilation fan. . Further, the pressure is increased by the secondary ventilation fan 16 and used as conveying air within the mill 6. The amount of this secondary air is detected by the differential pressure at the orifice 17 using a secondary air differential pressure detector.

The electric motor 10 applies rotational force to the mill table 9, which is decelerated by a reducer 8 to provide appropriate rotation to the mill balls 7.

Therefore, in this mill 6, the conventional type in which the classifier vanes 11 are fixed has a coal/-primary air ratio of about 0.5 to 0.6 and a vane angle of 40 to 50 degrees. It was operated within a fixed range.

If the vane angle is always fixed at a slightly large angle, the speed at which the fine powder is conveyed will be slow, which will cause wear of the classifier vanes 11. 〜If you reduce the angle,
If the fine powder conveyance speed is low, a backfire will occur. Therefore, the conventional coal-fired couplant was operated for base load and the load change rate was 0.5.
~1. The opening degree of the conventional classifier vane 11 was fixed because there was no high load operation at about Q%/min.

However, there is a growing demand for coal-fired couplants to operate at variable loads, and this type of operation cannot meet this demand. Therefore, an attempt was made to address the above-mentioned disadvantages as described below in order to meet the demand.

(1) Technology has been established to prevent wear of classifiers by strengthening materials and using ceramics.

(2) Regarding the bank fire phenomenon, classifier vane 1
The movable blades can be controlled by limiting the movable range in step 1, especially regarding the lower limit opening, by installing a minimum lock, using a mechanical lock on the control drive, and further limiting the minimum lock with a low selector in the control system. It is something.

(3) Regarding the use of coal retained within the mill, in general, approximately 20% of the remaining coal based on the mill capacity is recirculated, and this amount of retained coal is temporarily used when the classifier vane is opened during load increasing. By increasing the rate, the flow velocity of the pulverized coal is increased, and thereby the retained coal is carried out, thereby compensating for the delay in pulverization of the coal.

Therefore, when the load change is requested, the control device 300 issues a coal feeder command and drives the motor 5 to increase the amount of coal fed.
Driving the electric motor 10 to increase the capacity of the mill ball 7,
And - control drive 18 for popular people and popular people Roben
He gives Danno Kukai commands to the people so that he can respond to their requests.

FIG. 5 shows 'r+' of the control device used in the embodiment of the present invention.
FIG. In Figure 5, 22
is a total fuel detector, 23 is a first-order lag device, 24 is a subtractor,
25 is a multiplier, 26 is a proportional integral calculator, 27 is a multiplier,
28 is an adder, 29 is a bias setting device, 30 is an automatic manual switch, 31 is an automatic manual switch, 33 is a function generator, 3
4 is a bias setting device, 35 is an adder, 36 is a primary air differential pressure detection signal, 37 is a subtracter, 38 is a signal limiter, 39 is an automatic manual switch, 40 is an output demand signal, 41 is a differential calculator, 52 is a differential calculator, 54 is a signal limiter, 55 is a rate of change limiter, 57 is an adder, 58 is a multiplier, 59 is a signal switcher, 60 is an adder, 61 is a differentiator, 62 is a signal generator , 63 is a signal switch, 64 is an upper and lower limit limiter, 65 is a lower limit limiter, 66 is a signal generator, 67 is an automatic manual switch, and 69 is an adder.

The operation of such a control device 300 will be explained.

In response to the mill master command as a coal amount command value commensurate with the plant load, the total value of the amount of coal fed from the coal feeder 2 is sent as a signal 2.
2 is detected, and a subtractor 24 subtracts a value that is first-order delayed by a first-order lag detector 23 of the time required for the coal to come out after pulverization with respect to the command value. A multiplier 25 applies gain correction based on the number of mills in operation to the deviation signal from the subtracter 24.
After making the correction, the proportional-integral regulator 26 performs proportional-integral calculations, and the coal feeder 2 is operated until the deviation disappears. The multiplier 27 performs calorie correction on the deviation signal from the proportional integrator 26, and the calorie-corrected command value is output as a coal feed amount command signal for each mill in operation. According to the instructions for each of these mills 6, the coal feeder 2
The electric motor 5 of is driven, the amount of coal is limited, and -
The amount of primary air is controlled via the air pump 18. When control is possible for each mil unit, the coal feeder command and the fuel supply command are adjusted using bias setters 29 and 34 and adders 28 and 35. Further, the automatic manual switching device 30 converts the primary air amount to the coal feeding amount using the function generator 33, and sets it as a -popular air damper command. With respect to this command value, the air flow rate is detected by the signal 36 from the differential pressure detector 18, the deviation is detected by the subtractor 37, and proportional integral adjustment is made so that the deviation disappears. The primary air damper 15 is operated by the device 38.

Now, for the load request value 40 during load change, the differential calculator 5
2 to create a fuel amount commensurate with the load change, and after limiting the range of change with the upper and lower limit limiter 54, the rate of change limiter 5
5 to 56 and an adder 57, a fuel-rich system signal and an excess fuel command/insufficient fuel command are created to determine the optimum rate of change and width of change. This signal is subjected to gain correction based on the number of mills in the multiplier 58, and added to the adder 60, thereby making it possible to drive the coal feeding amount and the negative air amount in advance. Therefore, controllability is improved.

The control system for the classifier vanes operates as follows.

First, during normal operation, the a side of the switch 63 is selected, and the b side is selected during the process of load change including start and stop.

Now, during normal operation, the switch 63 has selected the a side, and the signal generator 62 has been set to a certain specified angle (about α+45°). According to the opening signal of the signal generator 62 mentioned above,
Controls the movable vane classifier vane control drive 13. On the other hand, during load changes including startup and stop processes, the switch 63 selects the b side, and the load change request value 42
is differentiated by a differentiator 61 to create a leading signal with good response, and a signal with a large change limited to this signal by an upper/lower limit limiter 64 is created.

An adder 69 adds the load change opening degree (±β) signal created as described above as the opening degree signal during load change to the specified angle (α) signal from the signal generator 62. Using this total signal, the classifier vane control drive 12 is driven to eject the remaining coal from the mill 6. By operating in this way, the crushing delay of the mill 6 can be compensated for.

FIG. 6 is a waveform chart shown to explain the operation of the fuel system according to the present invention. In FIG. 6, the horizontal axis shows time, and the vertical axis shows load and pulverized coal amount. In FIG. 6, (I) shows the load, and (■) to (IV) show the amount of pulverized coal.

As shown in FIG. 6, an example of the response of the amount of pulverized coal discharged from the mill 6 is shown if the load increases stepwise.

(II) in the figure shows the response of the total fuel amount of the feedback system in the conventional control device 300. As can be seen from this figure, it takes about 180 seconds to secure the specified amount of coal.

(I[[) shows the response when the conventional control device 300 is added with advance control of overaction of excess coal amount/insufficient coal amount to control the amount of coal fuel according to the range of change of the load request signal. Although it is effective in dealing with main steam temperature and main steam pressure changes because the amount of coal is injected over or under in advance, the delay in crushing the fuel is caused by the delay in crushing as described in (II) above. However, it can be understood that the crushing delay requires 2 to 3 minutes.

(IV) shows the operation of the embodiment according to the present invention), except for the response delay of the control drive 12.
It can be seen that the response is quick. As can be seen, it can be expected that the rate of change in load and the ability to follow the load can therefore be improved.

In short, according to this embodiment, the fuel supply device 200 converts the coal supplied to the coal feeder into pulverized coal by the pulverizer 6, conveys the pulverized coal to the primary air, and supplies it to the boiler via the burner. The classifier vane 11 installed in the pulverizer 6 is configured to be movable, receives information on the amount of coal fed and the amount of secondary air, and uses this information to respond to the boiler load request. The control device 300, which controls the drive of the fuel supply device 200 in advance to adjust the fuel supply amount, is configured to be able to control the opening degree of the classifier vane in advance with respect to the load request value. This has the advantage of eliminating coal pulverization delays and providing good fuel supply control.

〔Effect of the invention〕

As described above, according to the present invention, the classifier vanes provided in the pulverized coal machine are made movable, and the opening degree of the classifier vanes is controlled in advance. Since the coal can be carried out, there is no delay in the pulverization of the coal pulverizer, which has the effect of providing a good fuel supply system.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of a fuel system for a coal-fired couplant according to the present invention, Fig. 2 is a sectional view showing the structure of a pulverizer, and Fig. 3 is a structure of a classifier vane used in the pulverizer. 4 is a plan view showing the configuration of the classifier vane, FIG. 5 is a block diagram showing an example of the configuration of the control device,
FIG. 6 is a waveform diagram showing the operation of the embodiment of the present invention together with the conventional example. 1... Coal bunker, 2... Coal feeder, 3... Speed detector, 4... Load cell, 5... DC motor,
6... Pulverized coal machine (mill), 7... Pulverized coal ball, 8
...Reducer, 9...Electric motor, 11...Classifier, 1
3... Control drive, 15...-Next air damper drive, 16...-Next ventilation fan, 19...-Next air differential pressure detector, 18...-Next air damper drive Control drive, 22... Total fuel detector, 23...-
Next lag unit, 24... Subtractor, 25... Multiplier, 26
...Proportional-integral calculator, 27... Multiplier, 28...
Adder, 29... Bias setting device, 30... Automatic manual switching device, 31... Automatic manual switching device, 33... Function generator, 34... Bias setting device, 35... Addition device, 37... subtractor, 38... signal limiter, 39...
・Automatic manual switch, 41... Differential calculator, 52...
Differential calculator, 54... Signal limiter, 55... Rate of change limiter, 57... Adder, 58... Multiplier, 59...
... Signal switch, 60... Adder, 61... Differentiator, 62... Signal generator, 63... Signal switch, 64
...Upper limit limiter, 65...Lower limit limiter, 66.
...Signal generator, 67...Automatic manual switch, 69...
Adder, 100...Fuel device, 200...Fuel supply device, 300...Control device. Agent Patent Attorney Tatsuyuki Unuma 1st Prisoner − “＼”−Boo〜lθ Yam U Tamago 3 Ward Kan 4 Senro 6 Kun

Claims (1)

[Claims] 1. A fuel supply device that converts coal supplied from the coal feeder into pulverized coal using a pulverizer, transports the pulverized coal through primary air, and supplies it to the boiler via a burner; Incorporating information on the amount of coal supplied and the amount of people
In a fuel system for a coal-fired couplant, which includes a control device that controls the drive of the fuel supply device in advance in response to a boiler load change request based on this information and adjusts the fuel supply j, the fuel system is installed in the pulverizer. The classifier vane is configured to be movable, and the control device is configured to drive the classifier vane to open and close in advance in response to the load change request value. fuel equipment.