JPS5950853B2 - Control method for top pressure recovery turbine power generation equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling a furnace top pressure recovery turbine power generation facility, and is intended to cover blast furnace safety power in the event of a power outage with the power obtained by the furnace top pressure recovery turbine power generation facility. It is a purpose.

Traditionally, this safety power has been supplied by separate equipment, but since steelworks are generally equipped with multiple blast furnaces, it is difficult to cover the safety power for all blast furnaces with a single safety power supply facility. For example, in addition to the high cost of laying power transmission lines, it is also necessary to increase the amount of power normally transmitted by private power generation equipment (generally not highly efficient) used to secure power for security, which is undesirable from the point of view of energy consumption.

In the event of a power outage in the power system, the main sources of power for blast furnace safety are the water pump for cooling the blast furnace body and the water pump for cooling the hot air valve, which generally require about 500 to 4000 KW of power.

If a furnace top pressure recovery turbine power generation equipment is installed to recover energy from blast furnace gas, the maximum output will be 2 to 5 times the power for safety, although there will be considerable differences depending on the capacity and pressure of the blast furnace.
You get twice as much.

However, as a result of a temporary decrease in the volumetric flow rate of blast furnace gas during raw material charging, coke charging, and accompanying pressure equalization operations during blast furnace operation, the output of the furnace top pressure recovery turbine power generation equipment fluctuates. The minimum value may reach less than the security power.

This also happens when the blast furnace gas flow rate decreases during a power outage due to the stoppage of air blowing to the blast furnace, resulting in less than the safety power.

Therefore, a problem remains when the power for blast furnace safety in the event of a power outage in the power system is covered by the power obtained from the furnace top pressure recovery turbine power generation equipment.

The present invention is designed to reduce the volumetric flow rate of blast furnace gas when the power system is out of power as described above and the output of the top pressure recovery turbine power generation equipment is used as power for safety purposes. This purpose proposes a control method for top pressure recovery turbine power generation equipment that can increase the minimum value so that even if the output of the power generation equipment fluctuates, the minimum value does not fall below the safety power. .

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

In FIG. 1, blast furnace gas discharged from a blast furnace 1 is subjected to coarse particle removal by, for example, a dust catcher 2, then fine particle dust is removed by, for example, a bag filter 3, and then guided to a gas holder 5 via a bypass valve 4.

On the other hand, the turbine 6 of the furnace top pressure recovery turbine power generation equipment is connected in parallel to the bypass valve 4 via the flow control valve 7, and the generator 8 driven by the turbine 6 sends its output to the main power transmission system 10 through the circuit breaker 9. Supplied.

The furnace top pressure of the blast furnace 1 when the turbine 6 is not used is controlled by the bypass valve 4, and the furnace top pressure of the blast furnace 1 detected by the pressure detector 11 is a predetermined furnace top pressure setting value P.

The pressure controller A12 controls the opening degree of the bypass valve 4 by a predetermined allowable deviation setting value ΔP1 so that

The furnace top pressure when the turbine 6 is used is controlled by a flow control valve 7 attached to the turbine 6, and the furnace top pressure detected by the pressure detector 11 is a predetermined furnace top pressure set value P.

The pressure controller B13 controls the opening degree of the flow rate control valve 7 by a predetermined allowable deviation setting value ΔP1 so that

The detection output of the pressure detector 11 is switched and supplied to the pressure controller A12 side by the selector 14 when the turbine 6 is not used, and to the pressure controller B13 side when the turbine 6 is used.

Note that normally, when the turbine 6 is not used, the flow control valve 7 is
is fully closed, and when the turbine 6 is used, the bypass valve 4 is fully closed or close to it.

Now, as shown in FIG. 2, the furnace top pressure is at a predetermined furnace top pressure setting value P.

The solid line in FIG. 3 shows the change in the gas flow rate during operation in a steady state in which the gas flow rate is controlled to be above a predetermined allowable deviation setting value ΔP1.

That is, it can be seen that the volumetric flow rate of blast furnace gas temporarily decreases during raw material charging, coke charging, and associated pressure equalization operations during operation.

Therefore, the recovered power obtained by such a gas flow rate is also the fourth
It fluctuates as shown by the solid line in the figure, and the minimum power value may be less than the security power.

Next, if we consider the case where the allowable deviation setting value is set to ΔP2, which is larger than ΔP1, the control speed becomes slower because the range of allowable variation in the furnace top pressure becomes larger, and the change in gas flow rate during operation becomes slower. As shown by the dotted line in FIG. 3, the minimum gas flow rate value is larger than in the case of ΔP1 above the small allowable deviation setting value (solid line).

Therefore, the recovered power obtained by this will fluctuate as shown by the dotted line in Figure 4, and the minimum power value will also be larger than in the case of △P1 above the small allowable deviation setting value (solid line), and there is a risk that it will fall below the security power. I know it will disappear.

In this way, the minimum gas flow rate value fluctuates in close relation to the allowable deviation set value of the furnace top pressure set value, and this result appears as a change in the recovered power. When the air blowing to the blast furnace stops and the blast furnace gas flow rate decreases, the furnace top pressure recovery turbine power generation equipment in FIG. 1 is controlled as follows.

In the event of a power outage in the power system, the circuit breaker 9 is first turned off to stop power supply to the main power transmission system 10, and the output of the generator 8 is sent to the safety power transmission system 15.

At the same time, the selector 14 is switched to the pressure controller A12 side by the cutoff signal a of the circuit breaker 9, and the allowable deviation setting value of the pressure controller A12 is reset to a larger value of ΔP2.

Therefore, as mentioned above, the gas flow rate from the blast furnace 1 is as shown by the dotted line in FIG. 3, and as a result, the gas flow rate flowing through the turbine 6 is commensurate with the dotted line in FIG. The minimum value is increased as indicated by the dotted line in FIG.

The opening degree of the flow rate control valve 7 attached to the turbine 6 at this time is controlled by another control system so that the turbine 6 rotates at a constant speed, as in the steady state.

In addition, the upper limit deviation value △P2 and the lower limit deviation value -△P2 of the newly set allowable deviation setting value upper △P2 are 10 △P21
A relationship of <1-ΔP21 is desirable from the standpoint of increasing the minimum power value.

Further, the flow rate control valve 7 attached to the turbine 6 is composed of a cover valve, a turbine variable blade, or the like.

Furthermore, if the air blowing to the blast furnace is stopped during a power outage, the gas pressure in the blast furnace will drop and the gas flow rate will drop. Therefore, the control of the furnace top pressure does not require the high level of accuracy that is required during steady operation. Thus, it is possible to increase the permissible fluctuation range of the furnace top pressure.

According to the present invention, when the turbine is in use and there is a power outage in the power system, the furnace top pressure is controlled by the control valve to increase its permissible fluctuation range, thereby reducing the pressure from the blast furnace. Since the minimum value of gas flow rate can be increased, the minimum value of recovered power can be higher than the minimum value in the steady state. Therefore, even if this recovered power is used for security power during a power outage, There is no need to worry about the power going down.

[BRIEF DESCRIPTION OF THE DRAWINGS] The drawings show one embodiment of the present invention, and Fig. 1 is an overall control system diagram, and Fig. 2 compares the allowable deviation set value adopted for the furnace top pressure set value. FIG. 3 is a gas flow rate transition characteristic diagram illustrating a comparison of gas flow rates, and FIG. 4 is a generateable power transition characteristic diagram illustrating a comparison of recovered power. 1...Blast furnace, 4...Bypass valve, 6.
...Turbine, 7...Flow control valve, 8.
... Generator, 9 ... Circuit breaker, 11 ...
...Pressure detector, 12.13...Pressure controller A, B, 14...Selector.

Claims (1)

[Claims] 1 It has a flow rate control mechanism attached to the furnace top pressure recovery turbine and a control valve installed in a flow path that bypasses the turbine, and when the turbine is not used during steady operation of the blast furnace, the furnace top pressure is adjusted to the furnace top pressure setting When using the turbine during steady operation of the blast furnace, the furnace top pressure is controlled within the required allowable deviation set value with respect to the furnace top pressure set value. A control method for a furnace top pressure recovery turbine power generation equipment in which energy is recovered by controlling a flow rate control mechanism attached to the turbine so that the furnace top pressure is In addition, the constant speed rotation of the turbine is controlled by the flow rate control mechanism attached to the turbine, and the power recovered by the top pressure recovery turbine is A control method for a furnace top pressure recovery turbine power generation equipment, characterized by increasing the minimum value of.