JPH0119052B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stator blade control mechanism for a blast furnace gas energy recovery turbine having variable pitch stator blades, and a method for controlling a blast furnace gas energy recovery turbine plant using the same.

Conventionally, in order to recover the energy contained in the blast furnace gas discharged from the blast furnace, a recovery turbine 5 is disposed in the blast furnace gas discharge system in parallel with the septum valve 3, as shown in Fig. 1a, and the furnace top pressure is controlled by the septum valve. 3 to maintain the preset value,
A part of the blast furnace gas was guided to a recovery turbine 5 to recover energy. In such prior art, energy recovery from the blast furnace gas passing through the septum valve 3 is not performed, so the recovery efficiency is quite low.

Conventionally, one method to solve this problem is to use the septum valve 3 during normal operation as shown in Figure 1b.
is fully closed, the furnace top pressure is controlled by the governor valve 14, and the septum valve 3 is activated in the event of an abnormality in the blast furnace, when the turbine starts or stops, or when the control range of the governor valve 14 is exceeded. was considered. This method also has the problem that when the blast furnace gas flow rate decreases, the regulating valve throttles the flow rate to keep the furnace top pressure constant, resulting in large throttling losses and low energy recovery efficiency.

Furthermore, in order to solve this problem, in another prior art, a variable pitch stator blade is installed in the recovery turbine 5, and the stator blade pitch is changed in place of the speed regulating valve 14 to adjust the flow rate of gas passing through the turbine. It has been considered that the pressure control device 7 controls the furnace top pressure and controls the rotation speed when starting and stopping the recovery turbine 5.
When the stator vane pitch angle is 0 degrees, i.e., in a slightly opened state where the opening gradually increases from the fully closed state, not only does it generate a large amount of noise, but the sensitivity of the opening vs. flow rate is very high, especially when the generator load In such cases, it is very difficult to design a rotation speed control device when controlling the rotation speed to the no-load rated speed and synchronizing the rotation to the power grid.

One solution to this problem is to use the governor valve 14 to control startup, shutdown, synchronization, and other operations when the flow rate passing through the turbine is small, and set the furnace top pressure to a predetermined set value in response to disturbances such as inputting raw materials into the blast furnace. The furnace top pressure is controlled by changing the pitch of the stationary blades to maintain the furnace top pressure. Even in such a method, when the speed regulating valve is slightly opened, a large noise is generated due to the throttle, and a shock wave is generated, which adversely affects downstream stationary blades and rotor blades.

FIG. 1c shows a prior art blast furnace gas energy recovery plant. The blast furnace gas discharged from the blast furnace 1 passes through the dust remover 2, and when the recovery turbine is stopped, the septum valve 3 maintains the furnace top pressure Pb at the furnace top pressure set value _PBS by the control signal from the furnace top pressure control device 7. The flow rate is adjusted so that it flows downstream.

On the other hand, when starting the recovery turbine 5 from this state, first fully open the shutoff valve 4, and then gradually increase the setting value of the rotation speed setting device 811 of the speed regulating function 81 of the governor 8. The stator blade angle of the stator blade 51 of No. 5 is gradually opened from 0 degrees (fully closed), and the blast furnace gas is introduced to the recovery turbine 5, and the rotation of the recovery turbine 5 and the generator 6 driven by the recovery turbine 5 is gradually increased. To go. When the rotational speeds of the recovery turbine 5 and the generator 6 reach the rated rotational speed, the generator 6 is synchronously connected to the power system. At this point, the speed regulating function 81 becomes unstable, so the rotation speed setting device 811 is released to the upper limit. The function of the governor 8 is rotated by the function of the low selector 83 in the governor 8.
1 to the pressure regulating function 82, and the stator blade angle of the stator blade 51 of the recovery turbine 5 is changed by the signal from the pressure regulating function 82 of the governor 8, so that the furnace top pressure Pb is maintained at the set value _PSS . It acts on At this time, the set value P _SS is a value slightly lower than the furnace top pressure set value P _BS of the furnace top pressure control device 7 that drives the septum valve 3 (i.e.
P _SS =P _BS −ΔP _BS ). As a result, the septum valve 3 is fully closed and the entire amount of blast furnace gas passes through the recovery turbine 5, so that the generator 6 can convert and recover the maximum amount of energy contained in the blast furnace gas into electric power.

In such operation of the recovery turbine 5, the recovery turbine 5 is operated by the stationary blades 51 from startup to synchronization.
It is necessary to adjust the rotation speed of the recovery turbine 5 by operating it at a minute opening. In addition, under normal operating conditions for energy recovery, the stator blade angle is opened as much as possible, and the furnace top pressure Pb is adjusted so as not to disturb the gas flow as much as possible by slightly opening and closing the stator blade angle near the rated point. It is necessary to control the furnace top pressure to maintain it at the set value _PSS .

The prior art stator vane control mechanism 200 shown in FIG. 1c will now be described with reference to FIG. 2. The stator blade drive signal ζ output from the electric governor 8 is input to the stator blade driver 52, converted into a mechanical displacement amount x, and drives the stator blade angle θ. Using this mechanism, the recovery turbine 5 is started and turned on synchronously (no-load rated rotation speed)
It is very difficult to adjust the rotation speed by driving all the stator vanes 51 at minute openings during the speed increase process and the process of matching the synchronous rotation speed, and synchronization often fails.

The purpose of the present invention is to solve the above-mentioned technical problems,
Further, in steady-state operation, all the stator blades change at the same angle, thereby providing a stator blade control mechanism that does not cause turbulence in the flow of blast furnace gas, and a method of controlling a blast furnace gas energy recovery turbine plant using this mechanism. That's true.

FIG. 3 shows a block diagram of the main parts of one embodiment of the present invention. The stator blade drive signal ζ sent from the governor 8 is given to two converters 91 and 92 of the signal converter 9 via the line l1, where the signal is converted and the output signals ζ1 and ζ2 are sent to the line l1.
2 and l3. The stator vane driver 521 is
Receiving output signal ζ1 via line l2, stator vane driver 522 receives output signal ζ2 via line l3.
receive. Therefore, the stator blade drive rods 531 and 532 are driven and converted into mechanical displacements x1 and x2, which drive the stator blade angle θ1 of some of the stator blades 511 and the stator blade angle θ2 of the remaining stator blades 512, respectively. is configured to do so.

FIG. 4 shows the relationship between the stator blade drive signal ζ sent from the electric governor 8 and the stator blade angle θ1 of some of the stator blades 511 and the stator blade angle θ2 of the remaining stator blades 512 when configured as described above. Indicates the relationship between settings. By setting as shown in FIG. 4, in the range of 0≦ζ<ζA where the stator vane control signal ζ is small, only some of the stator blades 511 change in angle, and the remaining stator blades 512 remain fully closed. then the stator vane control signal increases and ζA≦ζ
<ζB, some of the stator blades 511 remain stationary at a predetermined constant angle, and the remaining stator blades 512 change in angle. Further, when the stator vane control signal ζ becomes ζ≧ζB, all the stator vanes 51 change their angles at the same angle. With this configuration, when it is necessary to control a minute flow rate with the stator blades, such as from the start of the recovery turbine 5 to the synchronization, that is, when the stator blade drive signal ζ operates in a range smaller than ζA, The gas flow rate can be easily controlled by only changing the angle of some of the stator vanes 511. Furthermore, in the normal operating state where the recovery turbine 5 is operated under the top pressure control state, that is, when the stator vane drive signal ζ operates near the rated operating point ζR, all the stator vanes 51 change at the same angle. Therefore, the recovery turbine 5 can be operated stably without causing any turbulence in the wake of the stationary blades 51, and the generator 6 can be driven to convert the energy possessed by the blast furnace gas into electric power and recover it.

As described above, one embodiment of the present invention includes a signal converter 9 comprising converters 91 and 92 driven by a stator blade drive signal ζ output from a governor 8;
Regarding the stator vane control mechanism 200 composed of the stator vane drivers 521 and 522 and the stator vane drive rods 531 and 532, the signal converter 9 functions as a signal level converter and is driven by its output. Ru. Each stator vane driver 521 and 522 is
receiving output signals ζ1 and ζ2 at signal levels;
The explanation has been given by taking as an example a servo mechanism that converts mechanical displacements x1 and x2.

FIG. 5 shows another embodiment of the servo mechanism. The stator blade drive signal ζ from the governor 8 is directly inputted to a compound cam driver 52a composed of, for example, a servo mechanism, and the compound cam 10 as shown in FIG.
It is also possible to configure the stator vane control mechanism 200 to drive and displace the stator vane drive rods 531 and 532 in the y direction, thereby driving the stator vane drive rods 531 and 532.

FIG. 7 shows still another embodiment of the stator vane control mechanism 200. Applying the stator blade drive signal ζ from the governor 8 directly to the linked rod driver 52b consisting of a servo mechanism,
The continuous rod driver 52b drives one stator blade drive rod 530. Furthermore, regarding the joint between the stator blade drive rod 530 and each stator blade drive link rod 540, the stator blade drive link rod 542 that drives some of the stator blades 512 is connected to the stator blade drive rod 53.
0 and is connected to the elliptical groove 552 so as to be rotatable and movable up and down, and a spring 56 is further provided below.
It is attached and biased by 2. Therefore, the seventh
When the stator vane drive rod 530 moves in the direction in which all the stator vanes 51 are closed from the fully open state in the order of figures a, b, and c,
In FIG. 7b, some of the stator blades 511 are partially open, while the remaining stator blades 512 are fully closed. When the stationary vane drive rod 530 further moves downward, the seventh
In the state shown in FIG. c, the partial stator blades 511 are also in a fully closed state. In this case, the tip of the stator blade drive connecting rod 542 that drives the remaining stator blades 512 that are already closed is the oval groove 5.
The spring 5 is attracted to the lower end in the groove of 52.
By moving away from the lower end of the groove portion 552 against the force of 62, the stator vane drive rod 530 is allowed to move downward.

FIG. 8 shows the stator blade drive signal ζ sent from the governor 8, the stator blade angle θ1 of some of the stator blades 511, and the remaining stator blades when the stator blade drive mechanism 200 is configured as shown in FIG. 512 and the stator blade angle θ2. In this case as well, if the stator blade drive signal ζ is in the range of 0<ζ<ζA that requires a minute opening, some of the stator blades 51
Only the stator blade 511 opens the stator blade angle θ1, and in the vicinity of ζ = ζR, which is the normal operating region, the stator blade angle of some stator blades 511 and the remaining stator blades 512 changes at approximately the same angle to adjust the blast furnace gas flow rate. enable.

As shown in the embodiments above, the stator blade control mechanism 200
is realized using an electric type, hydraulic type, mechanical type, or a combination thereof, and the stationary blade 5 of the recovery turbine 5 is
When some of the stator blades 511 and the remaining stator blades 512 of the stator blade 1 are slightly opened, the opening degree of only some of the stator blades 511 is changed, and the remaining stator blades 512 are kept in a fully closed state. In addition, the normal operating range of the recovery turbine 5, that is, the stationary blade 51
When the recovery turbine 5 is operated with a sufficient opening degree, the recovery turbine 5
Even if the throttling function provided by the speed regulating valve of the conventional recovery turbine 5 is removed, operation in the normal operating range from start-up can be performed safely, quietly and efficiently.

The above embodiments are all blast furnace gas energy recovery turbine plants in which the septum valve 3 is installed in parallel with the recovery turbine 5 in the exhaust gas system of the blast furnace plant.

FIG. 9 is another embodiment of a blast furnace gas energy recovery turbine plant. In Figure 9, the first
Components that are the same as those shown in the figures are given the same reference numerals.
This embodiment is a blast furnace gas energy recovery turbine plant including a ring slit washer 11 having a dust removal function and a furnace top pressure control function in the blast furnace gas exhaust gas system. A bypass valve 12 is installed in parallel with the recovery turbine 5. The furnace top pressure PB is always controlled by the ring slit washer 11, and the recovery turbine 5
From startup to synchronization, the bypass valve 12 controls the turbine front pressure by the turbine front pressure control device 13.
Controls PF constant and bypass valve 1 after synchronization
Keep 2 fully closed. The recovery turbine 5 controls the turbine front pressure PF based on a signal from the governor 8. In this type of blast furnace gas energy recovery plant, the furnace top pressure can be read as the turbine front pressure, and the septum valve can be read as the bypass valve, as in the case of the blast furnace gas energy recovery plant that has the septum valve 3 shown in FIG. It is clear that it is possible to control the recovery turbine using a blast furnace gas energy recovery turbine controller having a stator vane control function.

As described above, according to the present invention, in places where minute flow rate adjustment is required, such as when synchronizing a generator, only the stator vane angle of some of the stator vanes is changed, making it possible to precisely adjust the flow rate. Moreover, noise can also be reduced. In addition, during normal operation, all stationary blades are changed at the same angle in the same way to control the furnace top pressure in response to fluctuations in the flow rate of blast furnace exhaust gas due to material charging, etc., so there is no possibility of turbulence in the fluid. This results in more efficient energy recovery.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a blast furnace gas energy recovery plant according to the prior art, Fig. 2 is a diagram for explaining a stator vane control mechanism 200 of the prior art, and Fig. 3 shows the main parts of an embodiment of the first invention. Block diagram, 4th
The figure shows the stator blade drive signal ζ sent from the governor 8, the stator blade angle θ1 of some of the stator blades 511, and the remaining stator blades 5.
A graph showing the relationship between the setting and the stator blade angle θ2 of 12,
FIG. 5 is a configuration diagram of another embodiment of the first invention of the stator vane control mechanism 200, FIG. 6 is a diagram for explaining the displacement direction of the composite cam 10, and FIG. 7 is a diagram of the stator vane control mechanism 200.
Still another embodiment of the first invention of No. 0, FIG.
When the stator blade control mechanism 200 is configured as shown in the figure, the stator blade drive signal ζ sent from the governor 8, the stator blade angle θ1 of some of the stator blades 511, and the remaining stator blades 512
FIG. 9 is a block diagram of a control device for a blast furnace gas energy recovery turbine according to the second invention. 1...Blast furnace, 2...Dust remover, 3...Septum valve, 4...Shutoff valve, 5...Recovery turbine, 6...
Generator, 7... Furnace top pressure control device, 8... Governor,
9...Signal converter, 10...Compound cam, 11...
Ring slit washer, 12...bypass valve,
13...Turbine front pressure control device, 14...Governing valve, 51...Stator blade, 52...Stator blade driver, 52a
... Composite cam driver, 52b ... Continuous rod driver, 8
1... Speed regulating function, 82... Pressure regulating function, 83... Low selector, 91, 92... Conversion section, 200... Stator vane control mechanism, 511, 512... Stator vane, 521,
522... Stator vane driver, 530, 531, 532
... Stator blade drive rod, 540, 541, 542 ... Stator blade drive connection rod, 552 ... Groove, 562 ... Spring.

Claims (1)

[Scope of Claims] 1. In a blast furnace gas energy recovery turbine power generation plant in which a recovery turbine is installed in the exhaust gas system of a blast furnace plant to guide blast furnace gas and recover the energy contained in the blast furnace gas by converting it into electricity, the blast furnace gas that passes through the recovery turbine When the blast furnace gas flow rate is low, only some of the stator blades are opened and closed, and the stator blade angle of the remaining stator blades is kept fully closed, and the gas flow rate passing through the recovery turbine is large. A blast furnace gas energy recovery turbine control device characterized by having a stator blade control mechanism that opens and closes the stator blade angles of all stator blades at the same or substantially the same angle to adjust the flow rate of blast furnace gas passing through the recovery turbine. 2. In a blast furnace gas energy recovery turbine power generation plant where a recovery turbine is installed in the exhaust gas system of a blast furnace plant to guide blast furnace gas and recover the energy contained in the blast furnace gas by converting it into electricity, the generator is connected to the power system from the start of the recovery turbine. Until the synchronous input is started, the septum valve or bypass valve installed in parallel with the recovery turbine performs furnace top pressure control or turbine front pressure control, while the recovery turbine is controlled by the output signal from the governor. Through the stator vane control mechanism, only the stator blade angles of some of the stator vanes are opened and closed, and the stator blade angles of the remaining stator blades are kept fully closed to control the flow rate of blast furnace gas passing through the recovery turbine. The rotational speed of the recovery turbine is controlled by finely adjusting the rotation speed of the recovery turbine, and after the synchronization is started, the septum valve or bypass valve is kept in a nearly fully closed state, while the recovery turbine is controlled by the output signal from the governor. By opening and closing the stator blade angles of all the stator blades at the same or substantially the same angle through the stator vane control mechanism, the blast furnace gas flow rate passing through the recovery turbine is adjusted, and the furnace top pressure or turbine front pressure is controlled. A method for controlling a blast furnace gas energy recovery turbine, characterized in that: