JPH11264006A - Control method of blower with steam turbine and electric motor - Google Patents

Abstract

(57) [Summary] [Problem] When blast furnace air is blown by motoring of an electric motor, the amount of steam supplied to a steam turbine is reduced as much as possible, and the amount of motoring is brought close to the maximum state to save energy. Aim. When the electric motor is motored, the amount of steam supplied to the steam turbine is set to the maximum value while the mechanical amount is limited to a minimum, and the amount of steam generated by the steam pressure adjusting boiler is adjusted to the steam pressure adjusting boiler. If the state of becoming equal to or less than the first predetermined value equal to or more than the automatic adjustment lower limit value continues for the first predetermined time or more, the amount of steam supplied to the steam turbine and the amount of motoring are decreased to increase the amount of generated steam. When the state in which it becomes equal to or more than the second predetermined value continues for the second predetermined time or more, the amount of steam supplied to the steam turbine is again set to the minimum mechanical constraint and the motoring amount is set to the maximum value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a blower for blowing air from a blast furnace, and more particularly, to a steam turbine having a steam turbine and an electric motor, which can be driven by either or both of them. The present invention is suitable for a method of controlling a blower with a turbine and an electric motor.

[0002]

2. Description of the Related Art A method of controlling a blast furnace blower provided with such a steam turbine and an electric motor is disclosed, for example, in Japanese Patent Application Laid-Open No. 60-258404 previously proposed by the present applicant. . This type of blast furnace blower is characterized in that the steam turbine and the electric motor have a so-called parallel hybrid configuration, and in particular, the electric motor is also used as a generator. That is, for example, during the daytime when the unit price of electric power is high, the blower is mainly driven by the steam turbine, and the electric motor is mainly used as a generator, that is, regenerates excess energy. On the other hand, during the night when the unit price of electric power is low, the blower is mainly driven by the electric motor, and the amount of steam supplied to the steam turbine is reduced as much as possible to save energy. The powering of the electric motor as it is is also referred to as motoring.Although the drive distribution of the blower by the steam turbine and the drive distribution of the blower by the electric motor are, for example, adjusting the motoring amount, the blast furnace The drive by the steam turbine is automatically increased so that the amount of air blown to the steam is constant, that is, the amount of steam supplied to the steam turbine is increased.
Of course, the reverse control mode is also possible.

[0003]

By the way, in such a blower with a steam turbine and an electric motor, the steam supplied to the steam turbine is obtained from a steam generation source called a steam pressure adjusting boiler. In an actual facility, steam from various boilers such as the steam pressure adjusting boiler is concentrated and distributed to various low-pressure steam-using facilities other than the steam turbine. Needless to say, the amount of steam consumed in equipment using low-pressure steam other than the steam turbine also changes, similarly to the steam turbine. Further, when the pressure of the concentrated steam (in this case, equivalent to its own generation amount) decreases, that is, when the consumed steam amount increases, the steam pressure returns to the steam pressure adjusting boiler. Thus, there is a function of automatically increasing and adjusting the amount of generated steam.

However, the steam pressure adjusting boiler has a lower limit in the function of automatically adjusting the generated steam amount. That is, when the amount of generated steam is less than the lower limit, there is a structural characteristic that the continuous operation of the steam pressure adjusting boiler cannot be performed. Therefore, conventionally, in order to prevent the amount of steam generated from the steam pressure adjusting boiler from being lower than the lower limit, for example, in consideration of fluctuation in the amount of steam consumed by the low-pressure steam-using equipment, the amount of steam supplied to the steam turbine is, for example, Instead of making it zero, only this fluctuation in the amount of consumed steam is always supplied. As a result, the amount of steam generated by the steam pressure adjusting boiler does not fall below the lower limit, but on the other hand, even if there is a margin in the blower drive capacity by the motoring of the electric motor, the capacity cannot be maximized. There is a problem.

The present invention has been developed in view of these problems, and reduces the amount of steam supplied to the steam turbine to reduce the amount of steam generated by a steam generation source such as a steam pressure adjusting boiler. It is another object of the present invention to provide a steam turbine and a method for controlling a blower with an electric motor, which is capable of maximizing the blower driving capability by motoring the electric motor as much as possible.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a control method for a blower with a steam turbine and an electric motor according to the present invention is provided.
A method of controlling a blower that enables a blower to be driven by one or both of them, wherein a detected steam amount of a steam generation source is detected, and the detected steam amount is automatically adjusted. When the state of being equal to or less than the first predetermined value set to be equal to or more than the lower limit continues for a predetermined time or more, the amount of steam supplied to the steam turbine is increased, whereby the detected amount of generated steam is reduced to the first predetermined value. The amount of steam supplied to the steam turbine is reduced when the state of being equal to or more than a second predetermined value set to be equal to or more than a predetermined value continues for a predetermined time or more.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a method for controlling a blower with a steam turbine and an electric motor according to the present invention will be described with reference to the drawings.

First, FIG. 1 shows an outline of a blower system in which a control method for a blower system with a steam turbine and an electric motor according to the present embodiment is developed. Reference numeral 1 in the drawing denotes a blower that blows air to the blast furnace. A steam turbine 2 and an electric motor 3 are attached to a rotating shaft of the one blower 1 so as to form a so-called parallel hybrid configuration. That is, the blower 1 can be driven by the steam turbine 2 or the electric motor 3, and can be driven by both at the same time. Further, the electric motor 3 can also be used as a generator. Further, the steam used in the steam turbine 2 is returned to the condenser.

The steam turbine 2 has a centralized steam pipe 1
Steam is supplied from 3 through a steam control valve 4. The amount of steam supplied to the steam turbine 2 by the steam control valve 4 is controlled by the opening amount of the steam control valve 4 by the governor 5, and a control signal to the governor 5 is output from the controller 6. The controller 6 detects, for example, a motoring amount or a power generation amount of the electric motor 3 and performs a well-known PID (proportional-integral-derivative) operation on a deviation between the detected value and a set value. The amount is replaced with a control signal and output. That is, for example, when the motoring amount of the electric motor 3 becomes large, the required blast furnace airflow from the blower 1 is determined. Therefore, the electric motor 3 is determined based on the amount of steam supplied to the steam turbine 2 that satisfies the blast furnace airflow. A value obtained by subtracting the steam amount of the steam turbine 2 corresponding to the motoring amount of No. 3 is defined as a deviation, and a PID calculation is performed on the difference to obtain a control amount of the steam turbine 2, that is, a supplied steam amount. However, in the present embodiment, the amount of steam supplied to the steam turbine 2 can be changed by a signal from a generated steam amount monitoring device described later. In addition, from the said central steam pipe 13,
After the pressure is reduced by the back-pressure power generation equipment 7, it is supplied to other equipment using low-pressure steam.

On the other hand, the steam from the steam pressure adjusting boiler 8 and a plurality of other boilers 9 is fed to the centralized steam pipe 13 by the receiver 10. this house,
The steam pressure adjusting boiler 8 has a function of automatically adjusting the generated steam amount according to the consumption amount as described above.
On the other hand, there is also a characteristic that continuous operation cannot be performed if the generated steam amount is less than the lower limit. Therefore, in the present embodiment, the generated steam amount of the steam pressure adjusting boiler 8 is detected by the generated steam amount transmitter 11, and the detected steam generation amount is monitored by the generated steam amount monitoring device 12. When the amount of generated steam decreases below a predetermined value, the controller 6
The continuous operation of the steam pressure adjusting boiler 8 is made possible by increasing the amount of steam supplied to the inside.

Next, the operation of the control method for the blower with the steam turbine and the electric motor according to the present embodiment will be described with reference to the timing chart of FIG. First, for example, during the daytime when the unit price of electric power is high and a sufficient amount of steam can be obtained from other boilers, the blower 1 is mainly driven by the steam turbine 2 as in the related art, so that the blast furnace blowing amount becomes excessive. In such a case, the surplus energy is regenerated as electric power by using the electric motor 3 as a generator.

On the other hand, during nighttime when the unit price of electric power is low and it is difficult to obtain a sufficient amount of generated steam from other boilers, first, the amount of steam supplied to the steam turbine 2 is at least the minimum which is limited by the mechanical restrictions of the steam turbine 2. So that the controller 6
The motoring amount of the electric motor 3 is set. In other words, the motoring amount of the electric motor 3 at this time is as shown in FIG.
The maximum value shown in FIG. Then, for example, when the amount of steam consumed in other low-pressure steam-using equipment decreases, the amount of steam generated by the steam pressure adjusting boiler 8 gradually decreases as shown by the solid line in FIG. The generated steam amount of the steam pressure regulating boiler 8 detected by the generated steam amount oscillator 11, the generated steam amount is from automatic adjustment limit value of the steam pressure adjusting boiler 8 at time t ₀₁ shown in FIG. 2 for example Is also the first predetermined amount H
_When it becomes equal to or less than a first predetermined value which is larger by 1 and continues for a _first predetermined time T ₁ , the steam pressure adjusting boiler 8
As the limit vicinity of the automatic adjustment of the supply amount of steam to the steam turbine 2 at a time t ₀₂ is to increase by a predetermined value amount decreases sets the motoring of the electric motor 3 by the adjusting meter 6. That is, the motoring amount at this time is the predetermined value for returning to the steam amount shown in FIG. 2, whereby the amount of steam supplied to the steam turbine 2 increases and is consumed.

Thus, the steam pressure adjusting boiler 8
Inevitably increases the amount of generated steam, and the automatic adjustment function is restored. Eventually, generation amount of steam of the steam pressure adjusting boiler 8, for example, the steam pressure than the automatic adjustment lower limit of the adjustment boiler 8 second predetermined amount H ₂ greater by a second predetermined at time t ₀₃ shown in FIG. 2 is the value above, if it is the second predetermined time T ₂ only continues as an automatic adjustment function of the steam pressure adjusting boiler 8 is sufficiently restored, motoring of the electric motor 3 by the adjusting meter 6 at time t ₀₄ Is set to increase to the maximum value. By the way, the second predetermined amount H
₂ is set larger than a predetermined amount H ₁ of the first, so as to suppress prevent hunting of so-called control.

As a result, in the present embodiment, the amount of steam generated by the steam pressure adjusting boiler 8 including the increase and decrease can be greatly reduced, and at least the time t _02.
Since the motoring amount may be the maximum value, except time to time t ₀₄ from, it is possible to significantly save energy by both.

On the other hand, in the conventional control method, as shown by a two-dot chain line in FIG. 2, for example, even if the amount of steam consumed in the equipment using low-pressure steam is reduced, the generation of the steam pressure adjusting boiler 8 is performed. The amount of steam supplied to the steam turbine 2 is set to be larger than the minimum amount due to the mechanical constraint so that the amount of steam is not significantly reduced and its automatic adjustment function is not impaired. 2, excessive steam is consumed, so that the amount of steam generated by the steam pressure adjusting boiler 8 increases, and at the same time, the amount of motoring of the electric motor 3 also exceeds the maximum value as shown by the two-dot chain line in FIG. It is slightly smaller. Therefore, there is an energy loss here, and there is a problem that the desired energy saving cannot be achieved.

The various predetermined values and the predetermined time in the above-described embodiment are to be tuned by a trial run of an actual plant.

[0017]

As described above, according to the method for controlling the steam turbine and the electric motor-provided blower of the present invention,
If the amount of generated steam of the steam generation source is detected, and the state in which the detected generated steam amount is equal to or less than a first predetermined value set to be equal to or more than the automatic adjustment lower limit value of the steam generation source continues for a predetermined time or more, It is determined that it is near the limit of the generated steam amount automatic adjustment function of the steam source, and the amount of steam generated by the steam source can be increased by increasing the amount of steam supplied to the steam turbine. Previously, the amount of steam supplied to the steam turbine was reduced as much as possible to reduce the amount of steam generated from the steam generation source as much as possible, and to maximize the blower driving capacity of the electric motor as much as possible. Can be
Further, after the detected steam amount becomes equal to or more than the second predetermined value which is set to be equal to or more than the first predetermined value after the increase in the amount of steam supplied to the steam turbine, if the state continues for a predetermined time or more, Since it is determined that the function of automatically adjusting the amount of generated steam of the generation source has been restored and the amount of steam supplied to the steam turbine can be reduced, the amount of generated steam from the steam generation source can be reduced as much as possible, at least thereafter. In addition, the blower driving capability of the electric motor can be maximized as much as possible.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a blower system in which a control method of a blower system with a steam turbine and an electric motor according to the present invention is developed.

FIG. 2 is a diagram illustrating the operation of the blower of FIG. 1;

[Explanation of symbols]

 1 is a blower 2 is a steam turbine 3 is an electric motor 4 is a steam control valve 5 is a governor 6 is a controller 7 is a back pressure power generation facility 8 is a steam pressure adjusting boiler 9 is a boiler 10 is a receiver 11 is a generated steam amount transmitter 12 Is the generated steam monitoring device 13 is the centralized steam pipe

Claims (1)

[Claims] 1. A steam turbine and an electric motor are provided side by side,
A method of controlling a blower that enables a blower to be driven by one or both of them, wherein a detected steam amount of a steam generation source is detected, and the detected steam amount is automatically adjusted. When the state of being equal to or less than the first predetermined value set to be equal to or more than the lower limit continues for a predetermined time or more, the amount of steam supplied to the steam turbine is increased, whereby the detected amount of generated steam is reduced to the first predetermined value. A method of controlling a steam turbine and an electric motor-equipped blower, comprising reducing the amount of steam supplied to the steam turbine when a state of being equal to or more than a second predetermined value set to be equal to or more than a predetermined value continues for a predetermined time or more.