JPH1089676A - Method and apparatus for controlling pressure of fuel oil supply line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress drop of pressure of a fuel supply line to small and short time even when one pump is stopped at the stage of no use of a starting burner and to prevent closing of an igniting shut-off valve by forcibly reducing an opening of a pressure regulating valve when the one pump is stopped. SOLUTION: When one pump 4b is stopped at the stage of no use of a starting burner 1 at the time of starting a coal fired boiler, a switching unit 50 is switched to an (a) side by a pulse signal 42 from a pulse timer 43. A differential throttle opening signal 47 output from a subtracter 48 is output as an upper limit opening signal 49 to a proportional integral regulator 28 with a limiter, and an upper limit of an opening command signal 22 of a pressure regulating valve 17 output from the regulator 28 is forcibly suppressed to low. Therefore, the opening of the valve 17 is quickly reduced, and a pressure 20 of a fuel supply line 5 is instantaneously lowered, but immediately returned to an original value. As a result, an operation of the boiler may not be interrupted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling pressure in a fuel oil supply line.

[0002]

2. Description of the Related Art In general, in the case of a coal-fired boiler, in addition to a pulverized coal burner that injects and burns pulverized coal pulverized by a mill, a starter burner that is used only at startup by burning fuel oil such as light oil. And an ignition burner for burning fuel oil such as light oil and used for igniting the pulverized coal burner and the start-up burner.

FIG. 4 shows a fuel oil supply system for supplying fuel oil such as light oil to a conventional starter burner and an ignition burner, wherein 1 is a starter burner and 2 is an ignition burner. 3 is a tank for storing fuel oil such as light oil,
Reference numerals 4a and 4b denote pumps for pumping the fuel oil stored in the tank 3 to the fuel oil supply line 5, reference numeral 6 denotes a starting fuel oil supply line connected to the fuel oil supply line 5 and leading to the starting burner 1, and reference numeral 7 denotes starting. A start-up shut-off valve provided in the middle of the fuel oil supply line 6, a leak check valve 8 provided in parallel with the start-up shut-off valve 7, a start-up fuel oil return line 9 connected to the start-up burner 1, Reference numeral 10 denotes a start-up return valve provided in the middle of the start-up fuel oil return line 9, reference numeral 11 denotes an ignition fuel oil supply line connected to the fuel oil supply line 5 and communicates with the ignition burner 2, and reference numeral 12 denotes an ignition fuel oil supply. Line 11
An ignition shut-off valve provided in the middle, 13 is an ignition burner 2
The ignition fuel oil return line 14 is connected to the ignition fuel oil return line 13 provided in the middle of the ignition fuel oil return line 13.
5 is a fuel oil return line connected to the starting fuel oil return line 9 and the ignition fuel oil return line 13 and leading to the tank 3, and 16 is the fuel oil supply line 5 and the fuel oil return line 1.
5, a pressure control line provided in the middle of the pressure control line 16, and a pump 4a,
4b, a pressure detector for detecting the pressure 20 of the fuel oil supply line 5 at the outlet side;
7 is a controller that outputs an opening command signal 22.

The controller 19 calculates the difference between the pressure 20 detected by the pressure detector 18 and the pressure set value 21 output from the signal generator 23, and outputs a pressure deviation signal 24. The pressure deviation signal 24 output from the subtracter 25 is proportionally integrated so as not to exceed the maximum opening signal 27 (100%) output from the signal generator 26, and the opening command signal 22 is sent to the pressure control valve 17. And a proportional-integral adjuster with a limiter 28 for outputting.

[0005] When the coal-fired boiler is started, the fuel oil stored in the tank 3 is pumped to the fuel oil supply line 5 by the operation of the pumps 4a and 4b, and the starting fuel oil supply line 6 is started.
And to the ignition burner 2 via an ignition fuel oil supply line 11.

At this time, the pressure detector 18 detects the pressure 20 of the fuel oil supply line 5, and subtracts the difference between the pressure 20 detected by the pressure detector 18 and the pressure set value 21 output from the signal generator 23. The pressure deviation signal 24 obtained in the controller 25 is converted into a proportional-integral controller 28 with a limiter.
The pressure deviation signal 24 output from the subtractor 25 in the proportional-integral controller with limiter 28 is output to the maximum opening signal 27 (100) output from the signal generator 26.
%) So as not to exceed the value of the pressure control valve 17.
The opening degree command signal 22 is output, the opening degree of the pressure control valve 17 is adjusted, and the pressure 20 of the fuel oil supply line 5 is maintained at the pressure set value 21.

The start-up return valve 10 is closed when the number of the start-up burners 1 used is equal to or more than a certain number.
When the number of used burners 1 is less than that or when they are not used at all, the fuel burner 1 is opened, and surplus fuel oil is supplied from the fuel oil return line 9 to the tank 3 via the fuel oil return line 15.
It is to be returned to. Similarly, the ignition return valve 1
4 is closed when the number of used burners 2 is equal to or more than a certain number, while it is opened when the number of used burners 2 is less than or not used at all, and excess fuel oil is used for ignition. The fuel is returned from the fuel oil return line 13 to the tank 3 via the fuel oil return line 15.

After the start of the coal-fired boiler is completed,
The starting burner 1 is not used at all, and the flow rate of the fuel oil required to supply the ignition burner 2 is controlled by one pump 4.
The other pump 4b is stopped in order to reduce the power in order to be covered by a.

[0009]

As described above, when one of the pumps 4b is stopped to reduce the power at the stage when the start-up burner 1 is not used at the time of starting the coal-fired boiler, the fuel Although the pressure 20 of the oil supply line 5 is greatly reduced as shown in FIG. 5, the controller 19 as shown in FIG. After the pressure 20 in the supply line 5 drops to a certain value, it takes time to recover.

Here, if the pressure 20 of the fuel oil supply line 5 drops to a certain value, the supply of fuel oil to the ignition burner 2 becomes impossible, so that the ignition cutoff valve 12 is automatically closed. The ignition shut-off valve 1 is set.
2 is closed once, the fuel oil is supplied to the ignition fuel oil supply line 11 and the ignition fuel oil return line 13 and the ignition cutoff valve 12 and the ignition return valve 14 are closed. It is required by regulations to perform a so-called leak check to check for any leaks.

Therefore, conventionally, as described above,
When one of the pumps 4b is stopped at the stage when the start-up burner 1 is not used at the time of starting the coal-fired boiler, the ignition shut-off valve 12 is closed and a leak check must be performed. It takes a long time to use the burner 2, and during that time, the load of the boiler cannot be changed.

The present invention has been made in view of the above circumstances, and it is possible to suppress a decrease in pressure of a fuel oil supply line to be small and in a short time even when one pump is stopped at a stage when the starting burner is not used. An object of the present invention is to provide a pressure control method and apparatus in a fuel oil supply line which can prevent the shutoff valve for ignition from closing, eliminate the need for a leak check, and continue the load change of the boiler without interruption. is there.

[0013]

According to the present invention, there is provided a fuel oil supply line for supplying fuel oil stored in a tank to a starting burner and an ignition burner by operating a plurality of pumps. A fuel oil return line for returning fuel oil supplied to the ignition burner and the tank to a fuel oil return line is communicated by a pressure adjustment line provided with a pressure adjustment valve in the middle thereof, and a fuel oil return line is connected to the ignition burner for ignition. A pressure control method in a fuel oil supply line provided with an ignition shut-off valve in the middle of the fuel oil supply line, wherein when one pump is stopped, the opening of the pressure control valve is forcibly reduced. The present invention relates to a pressure control method in a fuel oil supply line.

Further, the present invention provides a fuel oil supply line for supplying fuel oil stored in a tank to a starting burner and an ignition burner by operating a plurality of pumps, and the starting burner and the ignition burner. And a fuel oil return line for returning the fuel oil supplied to the tank to a tank by a pressure adjusting line provided with a pressure adjusting valve in the middle thereof, and an ignition fuel oil supply line leading from the fuel oil supply line to an ignition burner. A pressure control device for a fuel oil supply line provided with an ignition shut-off valve on the way, wherein the pressure detector detects a pressure of the fuel oil supply line at an outlet side of the pump, and a pressure detected by the pressure detector. Find the difference from the pressure set value,
A subtractor that outputs a pressure deviation signal and, when one pump is stopped, a difference throttle opening signal obtained by subtracting the throttle opening signal from the opening command signal of the pressure control valve at that time as an upper limit opening signal. A switch that outputs the maximum opening signal as it is as an upper limit opening signal at other times,
A limiter-equipped proportional-integral controller for performing a proportional-integral process on the pressure deviation signal output from the subtractor so as not to exceed an upper-limit opening signal output from the switching device and outputting an opening command signal to the pressure control valve; And a pressure control device in a fuel oil supply line.

According to the above means, the following effects can be obtained.

In the pressure control method for a fuel oil supply line according to the present invention, when one of the pumps is stopped when the starting burner is not used at the time of starting the boiler, the opening of the pressure control valve is forcibly set. When the boiler is turned on, the pressure in the fuel oil supply line instantaneously drops, but immediately returns to its original value.As a result, when starting the boiler, one Even when the pump is stopped, the ignition shut-off valve is not closed, so that it is not necessary to perform a leak check, it is possible to always use the ignition burner, and it is not necessary to interrupt a change in the load of the boiler.

Further, in the case of the pressure control device in the fuel oil supply line of the present invention, when the boiler is started, the fuel oil stored in the tank is pressure-fed to the fuel oil supply line by the operation of a plurality of pumps. The fuel is supplied to the burner and also supplied to the ignition burner via the fuel oil supply line for ignition. At this time, the pressure of the fuel oil supply line is detected by the pressure detector, and the pressure detected by the pressure detector and the pressure setting The difference from the value is obtained in the subtractor, and the pressure deviation signal is output to the proportional-plus-integral controller with limiter. Here, since the plurality of pumps are operating, the maximum opening signal is not changed. It is configured to output to the limiter-equipped proportional-integral adjuster as an opening degree signal, and the pressure deviation signal output from the subtractor in the limiter-equipped proportional-integral adjuster, The upper limit opening signal output from the heat exchanger, that is, proportional integration processing is performed so as not to exceed the maximum opening signal, an opening command signal is output to the pressure control valve, the opening of the pressure control valve is adjusted, and fuel oil supply is performed. When the pressure of the line is maintained at the pressure set value, and subsequently, when starting the boiler, when one of the pumps is stopped at the stage when the start-up burner is no longer used, the pressure control at that time is performed from the switch. A subtraction throttle opening signal obtained by subtracting the throttle opening signal from the valve opening command signal is output as an upper limit opening signal to the proportional-plus-integral controller with limiter, and the pressure-control valve output from the proportional-plus-integral controller with limiter is output. Since the upper limit of the opening command signal is forcibly suppressed to a low level, the opening of the pressure control valve is rapidly narrowed, and as a result, the pressure of the fuel oil supply line is instantaneously reduced, but immediately, Returns to the value When starting the boiler, even if one pump is stopped when the start-up burner is no longer used, the ignition shut-off valve will not be closed, so there is no need to perform a leak check. It can be used, and the load change of the boiler does not need to be interrupted.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show an example of an embodiment of the present invention. In the drawings, the portions denoted by the same reference numerals as those in FIG. 4 represent the same components, and the basic configuration is shown in FIG. The present embodiment is the same as the conventional one shown in FIG. 1 except that the controller 19 outputs the pressure 20 detected by the pressure detector 18 and the output from the signal generator 23 as shown in FIGS. A subtractor 25 for obtaining a difference from the pressure set value 21 to be output and outputting a pressure deviation signal 24, and a pressure deviation signal 24 output from the subtracter 25 is converted into an upper limit opening degree output from a switch 50 described later. A proportional-integral controller with limiter 28 that outputs a degree-of-opening command signal 22 to the pressure control valve 17 by performing proportional-integral processing so as not to exceed the signal 49, and an operation signal 29a of the pump 4a and an operation signal 29b of the pump 4b are input. , Both operation signals 29
AND circuit 31 for outputting a logical product signal 30 of a and 29b
And the logical product signal 30 output from the AND circuit 31 is input. When the logical product signal 30 changes from “1” to “0”, a predetermined time delay t is generated to “0”. An OFF-delay timer 33 that outputs a delay signal 32 that changes to an operating signal 29a, a NOT circuit 35a that receives an operation signal 29a of the pump 4a and outputs a negation signal 34a obtained by inverting the operation signal 29a, and an operation signal of the pump 4b. 29b, a NOT circuit 35b that outputs a NOT signal 34b obtained by inverting the operation signal 29b, and a NOT signal 34a that is output from the NOT circuit 35a, and the NOT signal 34a changes from "0" to "1". When changed to
A pulse timer 37a for outputting a pulse signal 36a and a negative signal 34b output from the NOT circuit 35b are input. When the negative signal 34b changes from "0" to "1", the pulse signal 36b is output. Pulse timer 3
7b and an OR circuit 3 which receives pulse signals 36a and 36b output from the pulse timers 37a and 37b and outputs a logical sum signal 38 of both pulse signals 36a and 36b.
9, a delay signal 32 output from the off-delay timer 33, and a logical sum signal 38 output from the OR circuit 39, and a logical product signal 4 of the two signals 32, 38 is input.
0, and an AND signal 40 output from the AND circuit 41 are input to the AND circuit 41.
When 0 changes from “0” to “1”, the pulse signal 4
2 and the AND signal 41 output from the AND circuit 41 when the one pump 4b is stopped, the opening command signal 22 at that time is held and the opening command signal 22 '(in the figure, a
The switch 44 outputs the opening command signal 22 as it is as the opening command signal 22 '(switches to the b side in the figure).
And a throttle opening signal 46 (about 30%) set in the signal generator 45 is subtracted from the opening command signal 22 ′ output from the switch 44 to obtain a subtraction throttle opening signal 47.
When the one pump 4b is stopped, the subtractor 48 outputs the subtraction throttle opening signal 47 output from the subtractor 48 as the upper limit opening signal. Output to the proportional-integral controller with limiter as 49 (switched to the a side in the figure), otherwise, the maximum opening signal 27 output from the signal generator 26 is directly used as the upper limit opening signal 49
And a switch 50 (switched to the b-side in the drawing) to output to the proportional-integral controller with limiter 28 as shown in FIG.
The point is that when one pump 4b is stopped, the opening of the pressure control valve 17 is forcibly reduced.

Next, the operation of the illustrated example will be described.

When the coal-fired boiler is started, the fuel oil stored in the tank 3 is pumped to the fuel oil supply line 5 by the operation of the pumps 4a and 4b, and the starting fuel oil supply line 6 is started.
And supplied to the ignition burner 2 via the ignition fuel oil supply line 11. At this time, the pressure detector 18 detects the pressure 20 of the fuel oil supply line 5. , The difference between the pressure 20 detected by the pressure detector 18 and the pressure set value 21 output from the signal generator 23 is obtained in the subtractor 25, and the pressure deviation signal 24 is output to the proportional-integral controller 28 with limiter. .

Here, the switch 50 is provided with two pumps 4
Since a and 4b are operating, they are switched to the b side in the figure, and the maximum opening signal 27 output from the signal generator 26 is output as it is to the proportional-integral controller with limiter 28 as the upper limit opening signal 49. In the proportional-integral controller with limiter 28, the pressure deviation signal 24 output from the subtractor 25 is changed to the upper limit opening signal 49 output from the switch 50, that is, the output from the signal generator 26. The maximum opening signal 27 (100%) is not proportionally integrated so that the opening command signal 22 is output to the pressure control valve 17, the opening of the pressure control valve 17 is adjusted, and the fuel oil supply line 5 Is maintained at the pressure set value 21.

Subsequently, when one of the pumps 4b is stopped at the stage when the start-up burner 1 is not used when the coal-fired boiler is started, as shown in FIG. 2, only the operation signal 29b of the pump 4b is turned on. "" To "OFF" and the AN
The logical product signal 30 of the operation signals 29a and 29b output from the D circuit 31 switches from "1" to "0", but the delay signal 32 output from the off-delay timer 33 has a predetermined time delay t Is maintained at “1” until the time elapses, and is output to the AND circuit 41.

On the other hand, the negation signal 34a obtained by inverting the operation signal 29a output from the NOT circuit 35a remains at "0" and does not change. However, the negation signal 34b obtained by inverting the operation signal 29b output from the NOT circuit 35b is provided by a pump. At the time of stoppage of the pulse signal 4b, the pulse signal 36b is switched from "0" to "1", and the pulse signal 36b is output only from the pulse timer 37b. The sum signal 38 is output to the AND circuit 41.

The AND circuit 41 receives the delay signal 32 output from the off-delay timer 33 and the OR signal 38 output from the OR circuit 39, and calculates the logical product of the two signals 32 and 38. A
From the ND circuit 41, an AND signal 40 having the same waveform as that of the OR signal 38 output from the OR circuit 39 is output to the switch 44 and also to the pulse timer 43.

The switch 44 is switched to the side a in the figure by the AND signal 40 output from the AND circuit 41, and the opening command signal 22 at that time is held and the opening command signal 22 Is output to the subtractor 48 as
In the subtracter 48, the aperture opening signal 46 set in the signal generator 45 is subtracted from the opening command signal 22 'output from the switch 44, and a subtraction aperture opening signal 47 is subtracted.
Is output to the switch 50.

The switch 50 is provided with the pulse timer 43
Is switched to the side a in the figure according to the pulse signal 42 output from the, and the subtraction throttle opening signal 47 output from the subtracter 48 is output to the limiter-equipped proportional-integral controller 28 as the upper limit opening signal 49, Opening command signal 22 for pressure control valve 17 output from proportional-integral controller with limiter 28
Is forcibly kept low, the pressure regulating valve 17
As shown in FIG. 3, the opening degree of the fuel oil supply line 5 is rapidly narrowed down. As a result, the pressure 20 of the fuel oil supply line 5 instantaneously decreases, but immediately returns to the original value.

As a result, when the coal-fired boiler is started, when one of the pumps 4b
Is stopped, the shutoff valve 12 for ignition is not closed, the leak check is not required, the burner 2 for ignition can be used at all times, and the operation of the boiler does not need to be interrupted.

After the pulse signal 42 output from the pulse timer 43 becomes "0" again, the switch 50
Is switched again to the b side in the figure, and the maximum opening signal 27 output from the signal generator 26 is output as it is to the proportional-integral controller with limiter 28 as the upper limit opening signal 49,
Control is continued.

In this way, even when one of the pumps 4b is stopped when the starting burner 1 is no longer used, the drop in the pressure 20 of the fuel oil supply line 5 can be suppressed in a short time and can be reduced. It is possible to prevent the shut-off valve 12 from closing, and it is possible to continue without changing the load of the boiler without interrupting the leak check.

It should be noted that the pressure control method and apparatus in the fuel oil supply line of the present invention are not limited to the above illustrated examples, and that various changes can be made without departing from the gist of the present invention. Of course.

[0032]

As described above, according to the pressure control method and apparatus in the fuel oil supply line of the present invention, even if one pump is stopped when the starting burner is no longer used, the fuel oil is controlled. Excellent in that the pressure drop in the supply line can be suppressed small and in a short time, the ignition shut-off valve can be prevented from closing, the leak check is unnecessary, and the boiler load change can be continued without interruption. The effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of an embodiment of the present invention.

FIG. 2 is a diagram showing an output signal of each component of a control system when a pump is stopped in an example of an embodiment of the present invention.

FIG. 3 is a diagram showing a pressure of a fuel oil supply line and an opening of a pressure regulating valve when a pump is stopped in an example of an embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a conventional example.

FIG. 5 is a diagram showing a pressure of a fuel oil supply line and an opening of a pressure regulating valve when a pump is stopped in a conventional example.

[Description of Signs] 1 Starter burner 2 Ignition burner 3 Tank 4a Pump 4b Pump 5 Fuel oil supply line 11 Ignition fuel oil supply line 12 Ignition cutoff valve 15 Fuel oil return line 16 Pressure adjustment line 17 Pressure adjustment valve 18 Pressure detector 19 Controller 20 Pressure 21 Pressure set value 22 Opening command signal 22 'Opening command signal 24 Pressure deviation signal 25 Subtractor 27 Maximum opening signal 28 Proportional integral controller with limiter 46 Aperture opening signal 47 Subtraction diaphragm Opening signal 49 Upper limit opening signal 50 Switch

Claims (2)

[Claims] 1. A fuel oil supply line for supplying a fuel oil stored in a tank to a starting burner and an ignition burner by operating a plurality of pumps, and a fuel oil supply line for supplying the starting oil and the ignition burner. A fuel oil return line for returning fuel oil to the tank is communicated by a pressure adjustment line provided with a pressure adjustment valve in the middle, and an ignition fuel oil supply line is connected to the ignition burner from the fuel oil supply line. A pressure control method in a fuel oil supply line provided with a shut-off valve, wherein when one pump is stopped, an opening of a pressure control valve is forcibly reduced. Method. 2. A fuel oil supply line for supplying fuel oil stored in a tank to a starter burner and an ignition burner by operating a plurality of pumps, and is supplied to the starter burner and an ignition burner. A fuel oil return line for returning fuel oil to the tank is communicated by a pressure adjustment line provided with a pressure adjustment valve in the middle, and an ignition fuel oil supply line is connected to the ignition burner from the fuel oil supply line. A pressure control device for a fuel oil supply line provided with a shut-off valve, comprising: a pressure detector for detecting a pressure of the fuel oil supply line on an outlet side of a pump; and a pressure and a pressure set value detected by the pressure detector. And a subtractor that outputs a pressure deviation signal, and a differential throttle that subtracts the throttle opening signal from the opening command signal of the pressure control valve at that time when one pump is stopped. A switching device that outputs the maximum opening signal as it is as an upper limit opening signal while outputting the maximum opening signal as an upper limit opening signal, and a pressure deviation signal output from the subtractor, otherwise. A proportional-integral controller with a limiter that performs a proportional-integral process so as not to exceed an upper-limit opening signal output from the pressure controller and outputs an opening command signal to the pressure-regulating valve. Control device.