JP7294799B2 - fuel supply system - Google Patents

Description

The present invention relates to fuel supply systems.

2. Description of the Related Art Conventionally, a fuel supply system combining a table feeder and a weighing conveyor is known as a fuel supply system for supplying powdery or pitch-like fuel to a combustion apparatus. As a system similar to such a fuel supply system, for example, there is a powder discharge amount control device proposed in Patent Document 1.

The powder discharge amount control device of Patent Document 1 includes a hopper that stores powder such as dust that is a by-product in the steel process, a table feeder provided at the lower end of the hopper, and powder such as dust that is cut out from the table feeder. and a conveyor for stably discharging the body. The powder discharge amount control device of Patent Document 1 further includes a table feeder drive inverter that drives and controls the drive motor of the table feeder, and a conveyor drive inverter that drives and controls the drive motor of the conveyor.

JP 2013-10626 A

By the way, in a conventional fuel supply system employing the system of Patent Document 1, when the driving motors of the table feeder and the conveyor are rotated at a constant speed, the powdered fuel is placed on the conveyor in a manner of repeating peaks and valleys. be done. This is because the amount of fuel supplied from the table feeder to the conveyor per unit time fluctuates periodically. When such peaks and troughs occur in the fuel, the accuracy of the constant supply to the combustion device becomes poor, which greatly affects stable combustion in the combustion device.

In addition, when the rotation speed of the table feeder is changed to change the amount of fuel supplied, the thickness of the fuel on the conveyor changes, and a certain time lag occurs before the changed thickness of the fuel appears at the discharge section of the conveyor. . This time lag can have a detrimental effect on controlling the combustion system.

In order to prevent the fuel from overflowing from the conveyor, it is conceivable to reduce the thickness of the fuel on the conveyor by increasing the conveying speed of the conveyor. Increasing the conveying speed of the conveyor in this way also has the advantage of shortening the time lag. However, in addition to an increase in power consumption and a decrease in the belt life of the conveyor, the distance between peaks and troughs of the fuel generated on the conveyor increases, and the accuracy of constant supply to the combustion device remains poor and cannot be improved. do not have.

Therefore, in Patent Document 1, in order to smooth the peaks and troughs of the fuel, the rotation speed of the drive motor of the conveyor is increased in the region where the fuel is peaked, and the rotation speed of the drive motor of the conveyor is increased in the region where the fuel is trough. is stated to be delayed. Specifically, the frequency command value of the inverter for driving the table feeder is controlled to a value proportional to the target supply amount by the control device, and the frequency command value for the inverter for driving the conveyor is set to the target supply amount by the supply amount calculator. and the deviation of the supply amount actual value.

However, even if the peaks and troughs of the fuel are smoothed by controlling the inverters according to the method described in Patent Document 1, the conveying speed of the conveyor fluctuates, which causes fluctuations in the amount of fuel supplied to the combustion device. , it is considered that the problem of poor precision of quantitative supply cannot be practically solved.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a fuel supply system capable of accurately supplying the fuel in the form of powder or pitch required per unit time to the combustion apparatus. do.

In order to solve the above problems, a fuel supply system according to the present invention is a fuel supply system for supplying fuel in the form of powder or pitch to a combustion device, comprising: a reservoir for storing the fuel; a table feeder having a first motor as a drive mechanism provided for a discharge port for discharging the fuel stored in the reservoir; and weighing the amount of fuel supplied from the table feeder with high accuracy, A conveyor having a second motor as a driving mechanism provided for conveying the fuel to the fuel crusher in the trailing stream, and a control device capable of sequentially controlling the rotation speed of each of the first and second motors. a weight detector for detecting the weight of fuel per unit length along the conveying direction on the conveyor; and a weight signal transmitter for transmitting a weight signal including the fuel weight detected by the weight detector. and a speed detector for detecting the transport speed of the fuel on the conveyor, and a speed signal transmitter for transmitting a speed signal including the transport speed detected by the speed detector, The controller controls the amount of fuel supplied per unit time by the table feeder to the conveyor, which is derived based on the weight signal and the speed signal, to be the amount of fuel supplied per unit time required by the combustion device. The rotation speed of the first motor is sequentially controlled so as to match the set value, and the fuel weight per unit length along the conveying direction on the conveyor is maintained along the conveying direction regardless of the amount of fuel supplied. The rotation speed of the second motor is sequentially controlled in proportion to the fuel supply amount required per unit time in the combustion device so that the rotation speed of the second motor is constant.

According to the above configuration, the control device successively controls the rotation speed of the second motor as described above, so that the fuel does not overflow from the conveyor even if the conveying speed of the conveyor is not increased more than necessary. As a result, it is possible to smooth the peaks and valleys by narrowing the intervals between the peaks and valleys of the fuel that may occur on the conveyor and reducing the difference between the peaks and valleys.

Also, since the average thickness of the fuel on the conveyor is approximately constant, there may be further provided a scraper for smoothing the thickness of the fuel on the conveyor by horizontally traversing the upper edge of the fuel. According to the above configuration, peaks and troughs of the fuel that may occur on the conveyor can be made smoother.

If the ridges and troughs on the conveyor are sufficiently smoothed as described above and the thickness of the fuel on the conveyor becomes uniform, the amount of fuel supplied per unit time will depend only on the conveyor speed. The amount of fuel supplied per unit time passing through any of the scraper outlet, the intermediate section with the weight detector, and the fuel outlet is the same. Since the control device sequentially controls the rotation speed of the second motor as described above, when the set value of the fuel supply amount required per unit time in the combustion device changes, the conveyor speed changes at the same time. It is possible to eliminate the time lag between when the amount of fuel supplied to the conveyor by the feeder per unit time is adjusted and when the amount of fuel actually discharged from the conveyor starts to change. As a result, the fuel supply system according to the present invention can accurately supply the fuel in the form of powder or pitch required per unit time to the combustion apparatus at the entrance and exit of the conveyor.

A function of performing at least one of moving average processing and first-order lag processing on the fuel weight signal per unit length along the conveying direction on the conveyor to smooth the signal may be provided.

According to the above configuration, it is possible to realize more stable fuel supply amount control without being affected by periodic fluctuations due to peaks and valleys of the fuel slightly remaining on the conveyor.

For example, the control device may determine that the transport speed of the fuel on the conveyor is the desired amount of fuel per unit length along the transport direction on the conveyor, which is required per unit time in the combustion device. The rotation speed of the second motor may be controlled sequentially so as to achieve the first transport speed derived by dividing by the weight.

For example, the desired fuel weight per unit length along the conveying direction on the conveyor remains unchanged, and the controller receives input of the fuel supply required per unit time in the combustion device. The first transport speed may be derived using a function for deriving the first transport speed or a physical quantity corresponding thereto.

It further comprises a fuel weight setting device capable of arbitrarily setting a desired fuel weight per unit length along the conveying direction on the conveyor, and the control device controls the combustion device to perform fuel weight per unit time. The first conveying speed may be derived by dividing the required fuel supply by the desired weight of fuel per unit length along the conveying direction on the conveyor.

According to the above configuration, the fuel weight setter can arbitrarily set the desired fuel weight per unit length along the conveying direction on the conveyor.

According to the present invention, it is possible to provide a fuel supply system capable of accurately supplying the fuel in the form of powder or pitch required per unit time to the combustion apparatus.

1 is a schematic diagram showing the overall configuration of a fuel supply system according to an embodiment of the invention; FIG. It is a schematic diagram showing the whole composition about the 1st modification of the fuel supply system concerning the embodiment of the present invention. It is a schematic diagram showing the whole composition about the 2nd modification of the fuel supply system concerning the embodiment of the present invention.

A fuel supply system according to an embodiment of the present invention will be described below with reference to the drawings. It should be noted that the present invention is not limited by this embodiment. Also, hereinafter, the same or corresponding elements are denoted by the same reference numerals throughout all the drawings, and redundant descriptions thereof are omitted.

FIG. 1 is a schematic diagram showing the overall configuration of the fuel supply system according to this embodiment. The fuel supply system 10 according to the present embodiment includes a combustion device 140 (for example, burner, etc.).

The fuel supply amount required per unit time in the combustion device 140 generally fluctuates sequentially due to fluctuations on the steam consumption side and the like during boiler operation. Unless the fuel supply amount is adjusted sequentially according to the fluctuation, the steam flow rate generated from the boiler cannot be appropriately adjusted. Therefore, the fuel supply system 10 according to the present embodiment is used to precisely supply the combustion device 140 with the amount of fuel required per unit time.

(overall structure)
As shown in FIG. 1, the fuel supply system 10 according to the present embodiment includes a hopper 20 (reservoir) for storing fuel F and a discharge port 21 under which fuel F stored in the hopper 20 is discharged. outlet) and has a first motor 31 as a drive mechanism; a conveyor 40 having a motor 41 . The fuel supply system 10 also includes a control device 50 capable of sequentially controlling the rotational speeds of the first motor 31 and the second motor 41 .

Further, the fuel supply system 10 includes a weight detector 70 for detecting the weight of fuel per unit length along the conveying direction on the conveyor 40, and a weight signal containing the fuel weight detected by the weight detector 70. A weight signal transmitter 71 for transmitting PV1, a speed detector 75 for detecting the transport speed of the fuel F on the conveyor 40, and a speed signal PV2 containing the transport speed detected by the speed detector 75 are transmitted. and a speed signal transmitter 76 .

The weight detector 70 may be a load cell that detects the fuel weight per unit length at the center of the conveyor 40 in the conveying direction. Further, the speed detector 75 may detect the rotational speed of the second motor 41 or the rotational speed of the pulleys, and detect the conveying speed of the conveyor belt based on the rotational speed.

(hopper 20)
The hopper 20 has a funnel shape whose width dimension decreases from the upper end to the lower end, and a discharge port 21 for the fuel F is formed at the lower end. In this embodiment, since the fuel F is required to have fluidity, a lubricant or the like is added to the hopper 20 in order to prevent the fuel F stored in the hopper 20 from solidifying or forming bridges. can be put in. Note that the hopper 20 may be omitted when a cylindrical storage tank is used.

(Table feeder 30)
The table feeder 30 has a structure in which, for example, a plurality of rotary vanes (not shown) are rotated by the rotation of the first motor 31 to supply the fuel F to the conveyor 40 . Due to such a structure, the amount of fuel supplied from the table feeder 30 to the conveyor 40 per unit time generally fluctuates periodically. The average amount of fuel supplied to the conveyor 40 by the table feeder 30 per unit time is proportional to the rotational speed of the first motor 31 .

(Conveyor 40)
The conveyor 40 is horizontal so that its upstream end is positioned below the table feeder 30 and its downstream end is positioned above the fuel chute 110 for feeding fuel into the fuel crusher 100 . arranged along a direction.

(Rotary valve 120)
The fuel chute part 110 may be provided with a rotary valve 120 so that the fuel F supplied from the conveyor 40 is smoothly supplied to the fuel crusher 100 having a pressure difference while sealing the pressure. The rotary valve 120 may have a third motor 121 as a driving mechanism.

(Fuel grinder 100)
A fuel crusher 100 may be provided to crush the fuel F if the particle size of the fuel F is too large to burn in the combustion device 140 . The fuel crusher 100 may have a fourth motor 101 as a drive mechanism.

(Fuel transfer fan 130)
A fuel conveying fan 130 for airflow conveying the fuel F pulverized by the fuel pulverizer 100 to the combustion device 140 may be further provided. The fuel transfer fan 130 may have a fifth motor 131 as a driving mechanism. A fuel conveying fan 130 may be provided between the fuel grinder 100 and the combustion device 140 .

(Scraper 80)
Further, the fuel supply system 10 according to the present embodiment includes a scraper 80 that horizontally crosses the upper end of the fuel F on the conveyor 40 to smooth the thickness of the fuel F on the conveyor 40. good.

(control device 50)
The control device 50 has a first inverter 51 for controlling the rotational speed of the first motor 31 and a second inverter 52 for controlling the rotational speed of the second motor 41 . By controlling the rotational speed of the first motor 31 with the first inverter 51 , the control device 50 can sequentially adjust the amount of fuel supplied to the conveyor 40 by the table feeder 30 per unit time. Further, the control device 50 can sequentially adjust the transport speed of the fuel F on the conveyor 40 by controlling the rotation speed of the second motor 41 using the second inverter 52 .

Based on the weight signal PV1 received from the weight signal transmitter 71 and the speed signal PV2 received from the speed signal transmitter 76, the control device 50 controls the amount of fuel supplied to the conveyor 40 by the table feeder 30 per unit time. It further has a first calculator 61 that derives the supply amount and outputs a fuel supply amount signal PV3 including the fuel supply amount.

Specifically, the first computing unit 61 outputs a weight signal PV1 (that is, a fuel weight signal per unit length along the conveying direction on the conveyor 40) and a velocity signal PV2 (that is, a fuel F on the conveyor 40). (conveyance speed signal) is multiplied by the table feeder 30 to derive the amount of fuel actually supplied to the conveyor 40 per unit time. The fuel supply amount per unit time thus derived is transmitted to the flow control section 63, which will be described later, as a fuel supply amount signal PV3.

Further, the control device 50 determines that the fuel supply amount signal PV3 received from the first computing unit 61 is a fuel supply amount set value required per unit time in the combustion device 140 (fuel supply amount setting signal SV in FIG. 1). ), the flow control unit 63 sequentially controls the rotation speed of the first motor 31 using the first inverter 51 by, for example, performing PID control processing on the deviation.

The output of the flow control section 63 is sent to the first inverter 51 as the rotational speed command signal MV. Note that the flow control unit 63 may be realized by, for example, a known processor such as a CPU operating according to a program stored in a storage unit such as a memory.

Then, the controller 50 divides the fuel supply amount required per unit time in the combustion device 140 by the desired fuel weight per unit length along the conveying direction on the conveyor 40, thereby determining the first conveying speed. has a second calculator 62 for deriving

Here, in this embodiment, the desired fuel weight per unit length along the conveying direction remains unchanged. Then, the second computing unit 62 inputs the fuel supply amount required per unit time in the combustion device 140, and uses the function Fx for deriving the first transport speed or a physical quantity corresponding thereto. 1 Derive the transport speed.

Here, the first conveying speed is derived by dividing the fuel supply amount required per unit time in the combustion device 140 by the desired fuel weight per unit length along the conveying direction on the conveyor 40. is equivalent to the value As shown in FIG. 1, in the present embodiment, the signal extraction point 69 of the second calculator 62 is the fuel supply amount setting signal SV indicating the fuel supply amount required per unit time in the combustion device 140. and

The control device 50 sequentially controls the rotational speed of the second motor 41 using the second inverter 52 so as to achieve the first conveying speed. As a result, the control device 50 controls the fuel weight required per unit time in the combustion device 140 so that the weight of fuel per unit length along the conveying direction on the conveyor 40 is constant along the conveying direction. The rotation speed of the second motor 41 is sequentially controlled in proportion to the fuel supply amount.

(effect)
In this embodiment, the control device 50 sequentially controls the rotation speed of the second motor 41 as described above, so that the fuel F does not overflow from the conveyor 40 even if the conveying speed of the conveyor 40 is not increased more than necessary. There is no As a result, the intervals between peaks and troughs of the fuel F that may occur on the conveyor 40 are narrowed to reduce the difference between the peaks and troughs, so that the peaks and troughs can be smoothed.

Moreover, since the fuel supply system 10 according to the present embodiment includes the scraper 80 , it is possible to further smooth the peaks and valleys of the fuel F that may occur on the conveyor 40 .

Since the control device 50 sequentially controls the rotation speed of the second motor 41 as described above, when the fuel supply amount required per unit time in the combustion device 140 fluctuates, the conveyor by the table feeder 30 can be adjusted accordingly. It is possible to eliminate the time lag from when the amount of fuel supplied per unit time to the conveyor 40 is adjusted until the amount of fuel actually discharged from the conveyor 40 starts to change.

In the fuel supply system 10, the fuel weight signal PV1 per unit length along the conveying direction on the conveyor 40 is subjected to at least one of moving average processing and first-order lag processing by the third calculator 64. It may have a function of applying one and smoothing.

As a result, the fuel supply system 10 according to the present invention can accurately supply to the combustion device 140 the particulate or pitch-like fuel F required per unit time in the combustion device 140 .

(Modification)
From the above description many modifications and other embodiments of the invention will be apparent to those skilled in the art. Therefore, the above description is to be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. Substantial details of construction and/or function may be changed without departing from the spirit of the invention.

First, a first modified example of the fuel supply system according to the above embodiment will be described with reference to FIG. FIG. 2 is a schematic diagram showing the overall configuration of the first modified example. Note that the first modification has the same configuration as the fuel supply system 10 according to the above embodiment except for the configuration for deriving the first transport speed. Therefore, the same parts are denoted by the same reference numerals, and similar illustrations and descriptions are not repeated.

As shown in FIG. 2, the fuel supply system 10' of the first modification includes a fuel weight setting device 90 capable of arbitrarily setting a desired fuel weight per unit length along the transport direction. there is The signal extraction point 69 of the second calculator 62 is the same as in the above embodiment, and the fuel supply amount setting signal SV indicating the fuel supply amount required per unit time in the combustion device 140 is used. there is

In the first modification, the second calculator 62 divides the fuel supply amount required per unit time in the combustion device 140 by the desired fuel weight per unit length along the transport direction. The first conveying speed is derived by:

According to the above configuration, the fuel supply system 10' of the first modified example includes the fuel weight setting device 90 to arbitrarily set the desired fuel weight per unit length along the conveying direction on the conveyor 40. can be set.

Next, a second modification of the fuel supply system according to the above embodiment will be described with reference to FIG. FIG. 3 is a schematic diagram showing the overall configuration of the second modified example. It should be noted that the second modification has the fuel supply system according to the above embodiment, except that the automatic/manual switch 92 is provided and the signal extraction point 69 of the second computing unit 62 is located at a different position. 10 is the same configuration. Therefore, identical parts are given the same reference numerals, and similar illustrations and descriptions are not repeated.

In the above-described embodiment and first modification, the fuel supply systems 10 and 10' automatically control the first motor 31 and the second motor 41. FIG. On the other hand, the fuel supply system 10'' of the second modified example includes automatic/manual switches 92a and 92b, so that the first motor 31 and the second motor 41 are automatically controlled in an automatic mode and a manual mode. It is possible to switch between manual mode and manual mode.

As shown in FIG. 3, the fuel supply system 10'' of the second modification is provided with an automatic/manual switch 92a between the flow control unit 63 and the first inverter 51, and similarly, the second computing unit 62 and the second inverter 52, an automatic/manual switch 92b is provided.

For example, when the rotation speed of the first motor 31 is manually adjusted and then switched to the automatic mode by the automatic/manual switch 92a, a sudden change in the rotation speed of the first motor 31 that may occur when the automatic mode is set is prevented. In order to start the automatic mode smoothly, it is common to keep the fuel supply amount set value SV equal to the actual fuel supply amount PV3 at all times during the manual mode. In this case, if the fuel supply amount set value SV is set as the take-out point of the second calculator 62, a slight fluctuation in the fuel supply amount changes the rotational speed setting of the second motor 41. FIG. This change causes further fluctuations in the amount of fuel supplied, and there is a risk that this repeats an unstable operation.

Therefore, in the second modification, the fuel supply amount per unit time expected from the rotation speed command value to the first inverter 51 is estimated by the fourth computing unit 65 as the output point of the automatic/manual switch 92a. , the output of the fourth calculator 65 is used as a substitute signal for the fuel supply amount setting signal SV required per unit time in the combustion device 140 . By using the proxy signal as the extraction point of the second calculator 62, the unstable operation described above can be avoided. Also, the fourth calculator 65 and the second calculator 62 can be integrated into one function Fx calculator.

In addition to the first and second modifications, the following modifications are conceivable. For example, the fuel supply amount estimation signal per unit time calculated by the fourth calculator 65 is divided by the desired fuel weight per unit length along the conveying direction on the conveyor 40 as in the first modification. The first conveying speed may be obtained from the output signal.

Furthermore, in the above embodiment and its modification, the case where the fuel supply system 10 supplies fuel to the combustion device 140 provided in a boiler (not shown) has been described, but the present invention is not limited to this and other combustion. Fuel may be supplied to the device.

10 fuel supply system 20 hopper 21 outlet 30 table feeder 31 first motor 40 conveyor 41 second motor 50 control device 51 first inverter 52 second inverter 61 first calculator 62 second calculator 63 flow control section 64 third third calculator 65 fourth calculator 69 signal output point 70 weight detector 71 weight signal transmitter 75 speed detector 76 speed signal transmitter 80 scraper 90 fuel weight setter 92 automatic/manual switch 100 fuel crusher 101 fourth Motor 110 Fuel Chute Part 120 Rotary Valve 121 Third Motor 130 Fuel Conveying Fan 131 Fifth Motor 140 Combustion Device F Fuel

Claims (5)

A fuel supply system for supplying particulate or pitch fuel to a combustion device,
a reservoir for storing said fuel;
a table feeder having a first motor as a drive mechanism provided for a discharge port for discharging the fuel stored in the reservoir;
a conveyor provided for conveying fuel supplied from the table feeder to the combustion device and having a second motor as a drive mechanism;
a control device capable of sequentially controlling the rotational speeds of the first and second motors;
A weight detector for detecting the fuel weight per unit length of the conveyor, wherein the unit length of the conveyor is the amount of movement of the conveyor per unit time along the conveying direction on the conveyor, The unit time is a time shorter than the cycle of fluctuations in the amount of fuel supplied from the table feeder to the conveyor. a signal transmitter;
A speed detector for detecting the transport speed of the fuel on the conveyor, and a speed signal transmitter for transmitting a speed signal including the transport speed detected by the speed detector,
The control device is
The amount of fuel supplied per unit time to the conveyor by the table feeder derived based on the weight signal and the speed signal is shorter than the period of fluctuation of the amount of fuel supplied from the table feeder to the conveyor, sequentially controlling the rotation speed of the first motor so as to match the fuel supply amount set value required per unit time in the combustion device;
The rotation speed of the second motor is increased in proportion to the fuel supply amount required per unit time in the combustion device so that the fuel weight per unit length along the conveying direction on the conveyor is constant. A fuel supply system characterized by sequential control. 2. The fuel delivery system of claim 1, further comprising a scraper that horizontally traverses the top of the fuel on the conveyor to smooth the thickness of the fuel on the conveyor. 2. A function of performing at least one of moving average processing and first-order lag processing on a fuel weight signal per unit length along the conveying direction on said conveyor for smoothing. Or the fuel supply system according to 2. The controller controls the speed at which the fuel is conveyed on the conveyor so that the fuel supply amount required per unit time in the combustion device is the desired fuel weight per unit length along the conveying direction on the conveyor. 4. The fuel supply system according to any one of claims 1 to 3, wherein the rotation speed of said second motor is sequentially controlled so as to obtain a first transfer speed derived by dividing. the desired fuel weight per unit length along the conveying direction on the conveyor remains unchanged;
The control device uses a function for deriving the first transport speed or a physical quantity corresponding to the first transport speed by inputting a fuel supply amount required per unit time in the combustion device. 5. The fuel supply system according to claim 4, which derives .

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