JPS629643B2 - - Google Patents

Description

Detailed Description of the Invention The present invention controls the top pressure of a blast furnace by using a device that removes dust from blast furnace gas generated in a blast furnace plant of a steel mill and a device that recovers energy from the blast furnace gas. This relates to a device for

Conventionally, the gas generated in a blast furnace was removed using a dust catcher, ventilate scrubber, etc.
After being purified and passing through a septum valve, which is operated to maintain a constant pressure at the top of the furnace in response to a signal from the furnace top pressure control device, it is sent to a gas holder for other uses.

However, in recent years, the function of the bench turret scrubber has been expanded to make the area of the throat part of the bench turret variable, and by operating this variable throat type bench turret, it has become possible to maintain a constant pressure at the top of the furnace. As an alternative to the combination of a scrubber and a septum valve, a device has been put into practical use that controls the furnace top pressure and removes dust.

Since this method uses a ventilator to control the furnace top pressure, it has the characteristic that it can reduce the amount of noise generated when blast furnace gas pressure is reduced compared to the conventional method of controlling the furnace top pressure using a septum valve. On the other hand, in order to effectively utilize the gas energy generated in the blast furnace from the viewpoint of energy saving, there is also a device that connects a turbine in parallel to the septum valve and recovers the gas energy as electric energy by driving a generator with the turbine. It is put into practical use.

At this time, the turbine control valve has very good responsiveness due to the technical requirements of the turbine itself, and if the furnace top pressure is controlled using this highly responsive turbine control valve, the furnace top pressure can be controlled by the septum valve, and the furnace top pressure can be varied. The control performance can be dramatically improved compared to furnace top pressure control using a throat-type ventilate.

The purpose of the present invention is to increase the energy recovery efficiency and improve the furnace top pressure control performance as the first priority by using three control elements that are capable of controlling the furnace top pressure: a turbine control valve, a variable throat ventilee, and a septum valve. In order to achieve this, the furnace top pressure is controlled by the turbine control valve, and when the turbine is not operating, or when a load shedding or trip occurs during turbine operation, the furnace top pressure is controlled by the variable throat ventilator scrubber as the second priority. This is beneficial in terms of pollution in that it can reduce the amount of noise generated when blast furnace gas pressure is reduced, and when the variable throat ventilary scrubber cannot be operated automatically, the septum valve can be used as a final control means to control the furnace top pressure. The blast furnace is designed to be able to perform three types of furnace top pressure control in order to ensure a reliable backup system for the blast furnace.

Figure 1 shows the basics of a blast furnace system equipped with the aforementioned variable-throat ventilide scrubber, for example a ventilium scrubber in which a plurality of annular gap type variable-throat ventilator elements are housed in a tower, and a turbine. The gas discharged from the blast furnace 1 is sequentially guided to a dust catcher 2 and a ventilary scrubber 3 to remove dust and be purified, and then passes through a turbine 8 installed in parallel with a septum valve 6. Electrical energy is generated by driving the generator 9 at the gas holder 10, and is finally used for other purposes via the gas holder 10. At this time, the septum valve 6 is normally closed to allow the entire blast furnace gas to pass through the turbine 8. When the turbine 8 is not operated, the septum valve 6 is opened and the turbine control valve 7 is closed, thereby allowing the blast furnace gas to pass through the turbine 8. It functions to directly bypass the gas holder 10 from the bench ure scrubber 3.

In the blast furnace system shown in FIG.
After the generator 9 enters parallel operation with the electric power system as a step, the septum valve 6 is operated to allow the entire amount of blast furnace gas to pass through the turbine 8, thereby increasing the recovery efficiency of blast furnace gas energy and at the same time increasing the recovery efficiency of the blast furnace gas energy. A top pressure control device, that is, a turbine furnace top pressure control device 11, operates the turbine control valve 7 to control the top pressure of the blast furnace, and operates the variable throat type ventilic element 4 to cause the ventilic scrubber 3 to remove dust. Control to a predetermined differential pressure that can be effective.

In the second stage, when the turbine 8 is not operated, the septum valve 6 is opened and the turbine control valve 7 is closed by the turbine furnace top pressure control device 11. To control the furnace top pressure of the blast furnace while removing dust by operating the variable throat type ventilary element 4 using the control device 12.

In the third stage, even when the turbine 8 is not operated and the variable throat ventilary element 4 cannot be automatically operated due to equipment failure of the ventilic scrubber 3, etc., the third furnace top pressure control device is activated. That is, the septum valve 6 is operated by the septum valve furnace top pressure control device 13 to control the top pressure of the blast furnace. By automatically or manually switching between the first stage, second stage, and third stage according to the respective states of 3, the blast furnace can be operated in any state of the turbine and ventilium scrubber. An object of the present invention is to provide a control device for a blast furnace gas cleaning energy recovery plant that stably controls furnace top pressure.

FIG. 2 is an embodiment explaining the present invention in more detail.

In the figure, the control system is roughly divided into a turbine furnace top pressure control device 21, a ventilium scrubber furnace top pressure control device 22, a septum valve furnace top pressure control device 23, a furnace top pressure control switching device 24, a furnace top pressure setting device 25, and a bench. It consists of a Ury scrubber differential pressure setting device 28, a furnace top pressure detector 33, a turbine front pressure detector 36, a turbine start/stop controller 37, a turbine start/stop signal generator 40, and a generator 9 is connected to the power system. By operating the variable throat type ventilary element 4 with the output of the ventilate scrubber furnace top pressure control device 22, or by operating the septum valve 6 with the output of the septum valve furnace top pressure control device 23. The top pressure of blast furnace 1 is being adjusted.
After the generator 9 is connected to the power system, the turbine control valve 7 is operated by the output of the turbine furnace top pressure control device 21 to control the furnace top pressure.

Here, the turbine furnace top pressure control device 21 includes a turbine furnace top pressure regulator 26, a turbine control valve operation switching device 27, a ventilium scrubber differential pressure calculator 29,
The ventilary scrubber furnace top pressure control device 2 consists of a ventilary scrubber differential pressure regulator 30, a turbine front pressure setting device 31, and a turbine front pressure regulator 32.
2 is a bench uary scrubber furnace top pressure regulator 34;
It consists of a variable throat type ventilator element operation switching device 35, and a septum valve furnace top pressure control device 2.
3 consists of a septum valve furnace top pressure regulator 38 and a septum valve operation switching device 39.

In addition, when starting the turbine, a signal is issued to sequentially operate the septum valves in the closing direction, and when the amount of gas passing through the turbine suddenly decreases due to turbine load shedding or tripping, the furnace top pressure control switching device 24 A turbine start/stop signal generator 40 generates a feed forward signal that opens and closes a septum valve by a predetermined opening degree in order to prevent a rise in furnace top pressure in response to a signal, and a known signal generator 40 that generates a feed forward signal that opens and closes a septum valve by a predetermined opening degree in order to prevent a rise in furnace top pressure. Turbine start/stop controller 37 performs rotation speed control, known maximum output limit to protect the generator 9 from being overloaded due to an excessive increase in the amount of gas passing through the turbine during turbine parallel operation, etc.
Set up.

Furthermore, the furnace top pressure control state using the variable throat type ventilary element or the furnace top pressure control state using the septum valve can be switched to the furnace top pressure control state using the turbine control valve 7, or the above-mentioned load shedding, tripping, etc. It detects the disturbance and issues a trigger signal to generate a feedforward signal to the turbine start/stop signal generator 40, and also controls the furnace top pressure to the variable throat ventilary element 4 or septum valve 6. For this purpose, a furnace top pressure control switching device 24 is installed to switch the operating signals to the variable throat ventilary element 4, turbine control valve 7, and septum valve 6, respectively.

The operation and principle of FIG. 2 are as follows.

The first stage, that is, the state of furnace top pressure control by the turbine control valve 7 will be explained.

Setting signal PBs set by furnace top pressure setting device 25
and the furnace top pressure signal detected by the furnace top pressure detector 33
PBf is compared and subtracted by the turbine furnace top pressure regulator 26, and then subjected to calculations such as proportionality and integration to generate a control output signal e ₁ that makes the furnace top pressure equal to the set value.
Output.

On the other hand, the ventilate scrubber differential pressure setting device 28
The setting signal Pds set in , the signal PBf from the furnace top pressure detector 33 and the turbine front pressure detector 3
The signal Pdf from the differential pressure calculator 29 which takes out the difference with the front pressure signal PTf detected at 6 is compared and subtracted by the ventilium scrubber differential pressure controller 30, and then subjected to proportional and integral calculations and sent to the bench. Outputs a control output signal _e2 that makes the Uly scrubber differential pressure equal to the set value.

Further, the turbine front pressure setting device 31 subtracts the furnace top pressure setting signal PBs and the ventilure scrubber differential pressure setting signal Pds, adds an appropriate bias, and outputs the signal as the turbine setting signal PTs. This turbine front pressure setting signal PTs and the turbine front pressure signal PTf are compared and subtracted by a turbine front pressure regulator 32, and then subjected to calculations such as proportionality and integral, and outputted as a control output signal _e3 .

The furnace top pressure control switching device 24 detects that it is in the first stage and outputs the control output signals e ₁ , e ₂ , e ₃ described above.
are connected to the turbine control valve operation switching device 27, the variable throat type ventilium element operation switching device 35, and the septum valve operation switching device 39 so that they can be connected to the turbine control valve 7, variable throat type ventilary element 4, and septum valve 6, respectively. and generates a switching signal.

Through the above operations, the top pressure of the blast furnace 1 is controlled by the turbine control valve 7, and at the same time,
The ventilate scrubber 3 is controlled to a predetermined differential pressure necessary to exhibit a dust removal effect.

Moreover, since the turbine front pressure setting signal PTs is set higher than the turbine front pressure signal PTf, the turbine front pressure regulator 32 indicates that the septum valve 6 is operated in the closing direction in order to increase the turbine front pressure. The control output signal _e3 is output, and all the gas from the blast furnace 1 flows through the turbine 8, increasing the recovery efficiency of blast furnace gas energy. When the pressure increases abnormally, the turbine front pressure becomes higher than the set value.
The turbine front pressure regulator 32 outputs a control output signal _e3 that operates the septum valve 6 in the opening direction in order to lower the turbine front pressure, thereby preventing an abnormal rise in the turbine front pressure and, in turn, an abnormal rise in the furnace top pressure of the blast furnace 1. prevent the rise,
Furnace top pressure can be stably controlled.

When a load shedding or tripping occurs in the turbine 8 in the first stage, the furnace top pressure control switching device 24 detects that the load shedding or tripping occurs and sends the signal generator 40 for starting and stopping the turbine the above-described signal. At the same time as issuing a trigger signal for generating the feed forward signal e ₄ , a switching signal is issued to the septum valve operation switching device 39 so that the feed forward signal e ₄ can be connected to the septum valve 6 .

In addition, the furnace top pressure control switching device 24 is configured to
The state of the ventilium scrubber 3 before a trip occurs is monitored, and when the variable throat ventilator element 4 is operating normally, the control output signal e ₅ from the ventilium scrubber furnace top pressure controller 34 is monitored. A switching signal is issued to the variable throat ventilator element operation switching device 35 so that the valve can be connected to the variable throat ventilator element 4, and the second stage, that is, the furnace top pressure control by the variable throat ventilator element 4 is started. transition to state.

In addition, variable throat type ventilly element 4
When the valve cannot be operated by the control output signal e ₅ from the ventilate scrubber furnace top pressure controller 34 due to a control equipment failure or the like, the control output signal e ₆ from the septum valve furnace top pressure controller 38 A switching signal is issued to the septum valve operation switching device 39 so that the septum valve 6 can be connected to the furnace top pressure control state.

During the transition from the first stage to the second stage, the turbine start/stop signal generator 40 starts and stops the septum according to a predetermined schedule from the time when the above-described transmission of the feed forward signal is completed. A signal e ₄ is issued to operate the valve in the opening direction and finally open it to the fully open position. Since the septum valve is opened to the fully open position, it is possible to reduce the amount of noise generated when blast furnace gas pressure is reduced.
(See FIG. 3a) Next, the second stage, that is, the state of furnace top pressure control by the variable throat ventilator element 4 will be explained.

The furnace top pressure setting signal PBs and the furnace top pressure signal PBf
is compared and subtracted by the ventilly scrubber furnace top pressure regulator 34, and then subjected to calculations such as proportionality and integration to output a control output signal _e5 that makes the furnace top pressure equal to the set value. Furnace top pressure control switching device 24
detects that it is in the second stage and issues a switching signal to the variable throat ventilator element operation switching device 35 so that the control output signal _e5 can be connected to the variable throat ventilator element 4.

Through the above-described operation, the top pressure of the blast furnace 1 is controlled by the variable throat ventilate element 4 in the second stage. When restarting the turbine 8 in the second stage, the furnace top pressure control switching device 24 detects a startup command from the turbine and
An output command is issued to the turbine start/stop signal generator 40 to output a signal _e4 for operating the turbine in the closing direction according to a predetermined schedule.

The startup of the turbine after the septum valve is operated in the closing direction goes through the well-known rotation speed control mode, prepressure control mode, and initial load taking, and finally the generator 9 is connected to the power grid. and end.

The furnace top pressure control switching device 24 detects that the generator is connected to the power system and enters the first stage, and switches the turbine furnace top pressure controller 26, ventilium scrubber differential pressure controller 30, a turbine control valve operation switching device 27 so that control output signals e ₁ , e ₂ , e ₃ from the turbine front pressure regulator 32 can be connected to the turbine control valve 7, the variable throat ventilary element 4, and the septum valve 6, respectively; A switching signal is issued to the variable throat ventilary element operation switching device 35 and the septum valve operation switching device 39.

Further, in the second stage, when the variable throat type ventilic element 4 cannot be operated by the control output signal _e5 from the ventilic scrubber furnace top pressure regulator 34 due to a control equipment failure or the like, the furnace top pressure control switching device 24 detects the inoperability of the variable throat ventilator element, and switches the septum valve operation switching device 39 so that the control output signal _e6 from the septum valve furnace top pressure regulator 38 can be connected to the septum valve 6. A signal is issued and the process moves to the third stage, that is, the furnace top pressure is controlled by the septum valve. (See Figure 3b) Next, the third stage will be explained.

The furnace top pressure setting signal PBs and the furnace top pressure signal PBf
is a control output signal e ₆ which is compared and subtracted by the septum valve furnace top pressure regulator 38 and then subjected to calculations such as proportionality and integral so that the furnace top pressure becomes equal to the set value.
and this control output signal e ₆ is prepared to be connected to the septum valve 6 by the furnace top pressure control switching device 24. Therefore, even in the third stage, the septum valve 6 controls the blast furnace 1 The furnace top pressure can be controlled.

When starting the turbine in the third stage, the generator is connected to the power grid through the well-known speed control mode and initial load taking.

Until the generator is connected to the power system,
Since the septum valve 6 is operated by the control output signal e ₆ from the septum valve furnace top pressure regulator 38, when the turbine increases the intake amount of blast furnace gas to control the rotation speed and take up the initial load, the furnace Since the top pressure falls below the set value, the septum valve furnace top pressure regulator 38 outputs a control output signal e ₆ that operates the septum valve 6 in the closing direction to reduce the amount of gas passing through the septum valve. Control the top pressure at a constant level.

The furnace top pressure control switching device 24 detects that the generator is in the first stage when it is connected to the electric power system, and switches the turbine furnace top pressure controller 26, ventilium scrubber differential pressure controller 30, and turbine Front pressure regulator 3
The turbine control valve operation switching device 27 and the variable throat ventilator are connected so that the control output signals e ₁ , e ₂ , and e ₃ from the turbine control valve 7 , variable throat ventilator element 4 , and septum valve 6 can be connected to the turbine control valve 7 , variable throat ventilator element 4 , and septum valve 6 , respectively. A switching signal is issued to the element operation switching device 35 and the septum valve operation switching device 39 to move to the first stage, that is, the furnace top pressure control state using the turbine control valve.

However, in the transition from the third stage to the first stage, the variable throat type ventilic element 4 cannot be operated even by the control output signal _e2 from the ventilic scrubber differential pressure regulator 30, and therefore Although it is not possible to automatically control the ventilure scrubber 3 to a predetermined differential pressure even after the transition to stage 1,
It is possible to manually operate the variable throat ventilator element 4 to maintain a sufficient differential pressure to perform the dust removal function, and since the entire amount of blast furnace gas flows through the turbine 8, the blast furnace gas energy is reduced. It is possible to increase the collection efficiency.

Further, in the third stage, when the variable throat ventilator element 4 has no failure and can be operated, the furnace top pressure control switching device 24 detects the furnace top pressure control start command from the ventilator scrubber,
so that the control output signal e ₅ from the bench unit scrubber furnace top pressure regulator 34 can be connected to the variable throat type vent unit unit 4 and the operation signal e ₄ from the turbine start/stop signal generator 40 can be connected to the septum valve 6. Each variable throat type bench lily
A second step is to issue a switching signal to the element operation switching device 35 and the septum valve operation switching device 39;
In other words, the furnace top pressure is controlled by the ventilate scrubber.

After transitioning to the second stage, the transition from the first stage to the second stage
As mentioned in the explanation at the time of transition to the step, the turbine start/stop signal generator 40 outputs the signal _e4 that opens the septum valve to the fully open position.
The septum valve 6 can be opened to a fully open position to reduce the amount of noise generated when blast furnace gas pressure is reduced. (See Figure 3c) The septum valve 6 is usually constructed by connecting a plurality of butterfly valves in parallel, and a specific valve among the plurality of butterfly valves is used as an automatic control valve. Other valves are well known to those skilled in the art and are prepared for manual operation as necessary by blast furnace operators while monitoring the operating status of the blast furnace.

Utilizing this configuration of the septum valve, the automatic control valve is used as a furnace top pressure control valve or a turbine startup/stop control valve, and the manual operation valve is opened to a predetermined opening degree in advance. turbine 8
It is also possible to bypass part of the blast furnace gas to be taken in.

Developing this idea, when installing a turbine that cannot take in the entire amount of blast furnace gas, the remaining blast furnace gas that cannot be taken in by the turbine 8 can be bypassed using the manual operation valve of the septum valve 6. It is also possible to control the furnace top pressure and recover energy by operating the turbine control valve 7, that is, to perform an operation corresponding to the first stage.

Therefore, in the first stage of operation, the furnace top pressure is controlled by operating the turbine control valve 7 while bypassing a part of the blast furnace gas using the manual operation valve of the septum valve 6. When the load is cut off or a trip occurs in the turbine 8, the furnace top pressure is controlled by the variable throat ventilary element 4, that is, the second stage, or the furnace top pressure is controlled by the automatic control valve of the septum valve 6, that is, the third stage. Control means for switching to the above stage should also be construed as falling within the scope of the above claims.

As described above, the present invention makes it possible to control the top pressure of a blast furnace in any state of the turbine and ventilary scrubber, and also to control the feedstock pressure even when a load cutoff or trip occurs in the turbine. By the action of the word signal, it is possible to quickly shift to a state where the furnace top pressure is controlled by a variable throat type ventilary element or a septum valve, respectively, and stable and reliable operation of the blast furnace plant is possible.

Furthermore, the order in which the furnace top pressure is controlled is first to control the furnace top pressure by the turbine control valve, second to control the furnace top pressure by the variable throat ventilary element, and third, that is, the final control means. By prioritizing the furnace top pressure control using a septum valve, which has been carried out in the past, it is possible to increase the energy recovery efficiency of blast furnace gas, and at the same time, it is possible to reduce the amount of noise generated when blast furnace gas is depressurized. This has the effect of making it possible.

The control device according to the present invention can be constructed from conventionally known electric, pneumatic, and hydraulic control elements, or a combination thereof.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a blast furnace system equipped with a variable throat ventilary scrubber and a turbine, Fig. 2 is a block diagram showing an embodiment of the blast furnace gas cleaning/energy recovery plant control device according to the present invention, and Fig. 3 Figures a, b, and c are block diagrams of the furnace top pressure control order. 1...Blast furnace, 2...Dust catcher, 3...
Ventilation scrubber, 4...Variable throat type ventilium element, 6...Septum valve, 7
... Turbine control valve, 8 ... Turbine, 9 ... Generator, 10 ... Gas holder, 11, 21 ... Turbine furnace top pressure control device, 12, 22 ... Venture scrubber furnace top pressure control device, 13, 23... Septum valve furnace top pressure control device, 14, 24... Furnace top pressure control switching device.

Claims (1)

[Claims] 1. A ventilium scrubber having a variable throat section for cleaning blast furnace gas is installed in the gas exhaust system generated in the blast furnace, and a ventilium scrubber is installed on the downstream side of the ventilium scrubber to convert the blast furnace gas energy into electricity. In a furnace top pressure control system for a blast furnace, which comprises a plant consisting of a turbine and a generator, which are equipped with a turbine control valve installed in front of the turbine control valve to recover as target energy, and a septum valve installed in parallel with the turbine, (a) the inlet of the turbine; The turbine control valve provided on the side is connected to the furnace top pressure control switching device 24 via the turbine control operation switching device 27, and the turbine control valve is operated by a switching signal from the furnace top pressure control switching device 24, and the blast furnace a first order turbine furnace top pressure control device 21 configured to keep the furnace top pressure constant; A second-order ventilium scrubber furnace top pressure control unit is connected to the control device 24 and operates a variable throat section in response to a switching signal from the furnace top pressure control switching device 24 to keep the furnace top pressure of the blast furnace constant. (c) connecting the septum valve to the furnace top pressure control switching device 24 via a septum valve operation switching device 39, and operating the septum valve by a switching signal from the furnace top pressure control switching device 24; and a third-order septum valve furnace top pressure control device 23 that keeps the furnace top pressure of the blast furnace constant;
A furnace top pressure control device for a blast furnace, characterized in that a backup system is established for the blast furnace.