JPS5950854B2 - 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 paper 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 equipment fluctuates, the minimum value does not fall below the safety power. be.

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 transmits its output to the main power transmission system by connecting the circuit breaker 9 to the main power transmission system. 10.

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 gas flow rate during operation in a steady state controlled with a predetermined allowable deviation setting value ΔP1 such that

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, set the furnace top pressure to P.

Set to a lower P, and increase the positive allowable deviation setting value by +△ so that the allowable upper limit value at that time maintains the allowable upper limit value in the steady state.
Considering the case of setting P2, as shown in Figure 2,
For a low furnace top pressure set value, a negative tolerance set value -△P2 becomes -ΔP1, and a positive tolerance set value becomes +△P.
2 (as mentioned above, P+△P2-Po+△P1)
As a result, the allowable deviation setting value for the newly set furnace top pressure setting value will be larger than the allowable deviation setting value in the steady state, so the control speed will be The gas flow rate during operation is as shown by the dotted line in FIG. 3, and the minimum gas flow rate is larger than in the case where the allowable deviation setting value in the steady state is ΔP1 (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 steady state allowable deviation setting value (solid line), and will be below the security power. You will find that your fear is gone.

In this way, the minimum gas flow rate varies in close relation to the furnace top pressure set value and its tolerance set value, and this result appears as a change in 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 is controlled as follows in FIG. 1.

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 A side by the cutoff signal a of the circuit breaker 9, and the pressure controller A12 is switched to the pressure controller A12, taking into account that the air blowing to the blast furnace has stopped due to the power outage and the gas pressure in the blast furnace has decreased. Set the furnace top pressure to P.

In addition to setting a lower P, the positive allowable deviation set value of the allowable deviation set value for the furnace top pressure set value is set to +△P2 (P+
ΔP2=Po+ΔPt).

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.

At this time, the opening degree of the flow control valve 70 attached to the turbine 6 is controlled by another control system so that the turbine 6 rotates at a constant speed, as in the steady state.

Note that the flow rate control valve 7 attached to the turbine 6 is composed of a governor 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, and at that time the furnace top pressure set value is lowered and its permissible fluctuation range is increased. As a result, the minimum value of the gas flow rate from the blast furnace can be increased, and the minimum value of recovered power can be higher than the minimum value in steady state. Even if the power is used for commercial purposes, there is no danger that the power will fall below the level required for security purposes.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and Fig. 1 is an overall control system diagram, Fig. 2 is an explanatory diagram for comparing adopted furnace top pressure set values and allowable deviation set values, and Fig. 3 is an illustration of the overall control system. FIG. 4 is a gas flow rate transition characteristic diagram illustrating a comparison of gas flow rates, and FIG. 4 is a power generation change characteristic diagram illustrating a comparison of recovered power. 1...Blast furnace, 4...Bypass valve, 6.
...Turbine, 7...Flow control valve, 8.
... Generator, 9... Breaker, 11...
...Pressure detector, 12, 13...Pressure controller A, B, 14...Selector.

Claims (1)

[Claims] 1 The furnace top pressure recovery turbine has a flow 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 set to the furnace top pressure set value When the turbine is used during steady operation of the blast furnace, the furnace top pressure is controlled within the required tolerance deviation setting value with respect to the furnace top pressure setting value. A method for controlling 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 when the gas flow rate in the blast furnace decreases due to a power outage in the power system, Adopting a furnace top pressure set value that is smaller than the top pressure set value and a permissible deviation set value having a positive deviation set value whose permissible upper limit at the time is at least equal to the permissible upper limit of the required permissible deviation set value during steady operation. The furnace top pressure is controlled by the control valve so as to be within the newly adopted allowable deviation setting value with respect to the small furnace top pressure setting value, and the constant speed rotation of the turbine is controlled by the flow rate control attached to the turbine. 1. A method for controlling a top pressure recovery turbine power generation equipment, characterized in that the control is performed by a mechanism to increase the minimum value of recovered power of the top pressure recovery turbine.