JPH0711974A - Corrosion preventing method for blast furance gas energy recovering turbine - Google Patents

Abstract

PURPOSE:To prevent corrosion and to enable continuous operation for a long time when a corrosion component exceeding a specified value is detected by a drain mist analyzing means, by deciding among dry, and dry/wet mixed operations, and by preventing condensed mist from being generated or lowering concentration of the corrosion component. CONSTITUTION:After drain mist (d) in a turbine outlet pipe 13 is collected in the pocket 16 of a drain mist analyzing means 15, it is introduced from a discharge device 17 to a component analyzing device 18, and a corrosion component in drain is detected. A detecting signal is introduced to an alarm sequence 19 serving as a discriminating means, wherein a detecting value is compared with an allowable value. As a result, when the detecting value exceeds the allowable value, a discriminating signal is inputted to an operation condition variation sequence 20, where it is confirmed whether dry operation or dry/wet mixed operation is executed. Thereafter, for example, in case of dry operation, an exhaust gas pressure at the inlet of a turbine 12 is decreased through a pressure regulating mechanism 10 by means of a pressure regulator 21, and the drain mist (d) is prevented from generation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing corrosion of a turbine in a furnace top pressure recovery turbine, and more particularly to a turbine in a furnace top pressure recovery turbine for both wet and dry conditions in which exhaust gas from a blast furnace is guided through the turbine to recover energy. The present invention relates to a method of preventing corrosion.

[0002]

2. Description of the Related Art Exhaust gas discharged from the top of a blast furnace has a high temperature and a considerable pressure, and since the amount of the gas is large, the so-called furnace top pressure is used as a device for recovering and utilizing the physical energy of the exhaust gas. Recovery turbines are known. By the way, corrosive gas components and a large amount of dust are present in the exhaust gas from this blast furnace, and this dust is removed in order to prevent it from adversely affecting the recovery of physical energy and the recovery of chemical energy on the downstream side. To be done. As a dust removing method, conventionally, a method has been adopted in which exhaust gas from a blast furnace is first subjected to dust removal by a dust catcher, then guided to a wet dust remover, and finally removed there. In the process of dust in a wet dust remover, corrosive components (e.g. Cl ^-, SO ₄ ^-, etc.) is melted in the dust water after dust cleaning, and entrained in the exhaust gas within the turbine as part mist of dust water Flow into.

However, use of this wet dust collector causes a considerable pressure loss and a decrease in sensible heat due to a decrease in exhaust gas temperature, resulting in a decrease in power recovery rate using the turbine. For this reason, it is conceivable to maintain the sensible heat of the exhaust gas and collect the dust with a dry dust collector with a small pressure loss, but in this case, the corrosive components in the exhaust gas cannot be removed. This corrosive component is melted in the condensed mist generated in the latter stage of the turbine, and the corrosive component in this mist is melted in the mist flowing into the turbine and the condensed mist generated inside the turbine when the wet dust collector is used. The concentration is higher than that of the corrosive components, and the inside of the casing and the turbine blades are contacted with each other to significantly corrode them.

Therefore, it has been proposed to construct a furnace top pressure recovery turbine for both dry and wet conditions as shown in FIG. 8 and perform anticorrosion coating on a portion of the turbine where corrosion is likely to occur. That is, the exhaust gas G of the blast furnace 1 is supplied to the pipeline 3 having the dust catcher 2.
To a first line 6 having a wet dust collector 4 and a first switching valve 5, or a second pipe 6 having a dry dust collector 7 and a second switching valve 8.
It is adapted to be guided to the turbine 12 via the third conduit 11 having the flow rate adjusting mechanism 10 via the second conduit 9.

After the turbine 12 is driven, it is discharged from the turbine outlet pipe 13 to the outside of the system. Reference numeral 14 provided behind the dry dust collector 7 is a dust densitometer. When the densitometer reaches a predetermined dust concentration or more, the second switching valve 8 is closed and the first switching valve 8 is closed. The dust collector is switched by opening the valve 5. A coating film made of anticorrosive paint or the like is formed on the main part of the turbine 12, particularly on the inner surface of the rear casing.

[0006]

In the above furnace top pressure recovery turbine, the dust in the exhaust gas abrades the coating film on the main part of the turbine, and as a result, the coating film has a relatively short life and therefore a long time. There is a problem that corrosion tends to occur during operation, and in practice it is impossible to prevent the occurrence and progress of corrosion.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and has a blast furnace, a turbine inlet, a wet dust collector, and a first switching valve.
Second pipeline having the above pipeline, the dry dust collector, and the second switching valve, and the third pipeline having the pressure adjusting mechanism and collecting the first pipeline and the second pipeline. In the furnace top pressure recovery turbine connected by and, the drain mist analysis means is arranged in the turbine outlet pipe, the signal of the drain mist analysis means is introduced into the discrimination means, and the signal from the discrimination means is confirmed by the operation confirmation means. And a method for preventing corrosion of a turbine in a furnace top pressure recovery turbine, wherein any one of the first switching valve and the second switching valve or the pressure adjusting mechanism is operated by a signal from the operation confirmation means. Is intended to be provided.

[0008]

[Operation] In the method of preventing turbine corrosion in such a furnace top pressure recovery turbine, the first switching valve is now closed,
When the second switching valve is opened and the dry operation is performed, the corrosive component is detected by the drain mist analysis means, and this signal is guided to the discrimination means, compared with a predetermined value allowable here, and the drain mist is being processed. When the corrosive component of is above a predetermined value, the signal from the discriminating means is introduced into the operation confirming means, and the pressure adjusting mechanism is operated by the command signal from this. That is, the pressure adjusting mechanism lowers the gas pressure at the turbine inlet so that condensation mist is not generated on the turbine discharge side. On the other hand, when the first switching valve and the second switching valve are in the semi-open state and the dry-wet mixing operation is performed, the first switching valve and the second switching valve are operated by the command signal from the operation confirming means, and the wet type is operated. It can be switched to driving. By controlling in this way, the operating state is such that no condensation mist is generated during dry operation, while wet operation is switched during dry-wet mixing operation, so the concentration of corrosive components contained in mist inside the turbine is low. Corrosion of the turbine is prevented or mitigated.

[0009]

[Examples] Examples of a method for preventing corrosion of a turbine in a furnace top pressure recovery turbine according to the present invention will be described below with reference to FIGS. 1 to 7. In these figures, the same symbols as those in FIG. 8 indicate the same names. (Embodiment 1) In FIG. 1, 15 is a turbine outlet pipe 13
A drain mist analysis means provided in the collection pocket 16, a drain discharge device 17, and a drain component analysis device 1.
8 and. And turbine outlet pipe 13
The drain mist d in the inside is collected in the collecting pocket 16 and guided from the drain discharge device 17 to the drain component analyzer 18, where the corrosive component in the drain is detected, and this signal V
₁ is introduced into the alarm sequence 19 as a discrimination means,
Here, it is compared with a predetermined value which is an allowable value.

When the corrosive component exceeds the predetermined value, the signal V ₂ is generated and input to the operation condition changing sequence 20 as the operation confirmation means. In this operation condition change sequence 20, it is confirmed whether the dry operation or the dry-wet mixed operation state, and in the case of the dry operation, the command signal V ₃ is generated,
In response to this signal V ₃ , the pressure regulator 21 gives a control signal V ₄ to the pressure regulating mechanism 10 to lower the exhaust gas pressure at the turbine inlet. That is, the condensation mist d is prevented from being generated in the turbine outlet pipe 13.

On the other hand, in the dry / wet mixing operation, the command signal V ₄
Occurs, the second switching valve 8 is closed by the dry / wet switching sequence 32, and the first switching valve 5 is opened to switch to the wet operation. As a result, the turbine 12
The concentration of the corrosive component that melts in the mist becomes low. Therefore, the corrosion of the main part in the turbine 12 can be prevented or reduced. (Embodiment 2) In FIG. 2, the signal V ₅ from the temperature detector 22 arranged in the turbine outlet pipe 13 is introduced into the temperature controller 23, and the command signal V ₃ is confirmed in this temperature controller 23, and the control signal V ₃ is detected. It becomes ₆ and is input to the subtractor 24.

Then, the opening signal V ₇ output from the electric governor and the calculator 25 is subtracted to become an opening control signal V _8, and the adjusting valve 10a which is a pressure adjusting mechanism is throttled,
By reducing the inlet gas pressure of the turbine 12, the outlet gas temperature will be controlled. On the other hand, the temperature controller 23
The signal V ₉ from V is the ratio setter 26 for the stationary blade setting angle signal.
Is led to the adder 27 through the electric governor and the arithmetic unit 2
It is added to the control signal V ₁₀ from 5 to become the signal V ₁₁ , which is guided to the turbine vane variable mechanism 28 to control the angle of the vanes 29 and maintain the passage amount of the exhaust gas G passing through the turbine 12.

By controlling in this way, the temperature of the turbine blade cascade outlet gas does not fall below the saturation temperature, that is, below the temperature at which the condensation mist d is generated. Therefore, the corrosion of the turbine 12 can be prevented. (Embodiment 3) FIG. 3 is another system diagram for controlling the turbine blade cascade outlet gas temperature so as not to fall below the saturation temperature, in which the temperature is detected in the third conduit 11 which is the turbine inlet gas pipe. The temperature detector 30 and the pressure detector 31 are provided with a signal V ₁₂ from the temperature detector 30 and a signal V ₁₃ from the pressure detector 31.
Are input to the pressure regulator 21, a signal V ₉ for controlling the angle of the stationary blades 29 is generated, and an opening control signal V ₆ for controlling the speed regulating valve 10a which is a pressure adjusting mechanism is generated. It is.

In this way, the pressure of the exhaust gas G at the turbine inlet is controlled so that the gas temperature at the blade row outlet of the gas turbine 12 does not fall below the saturation temperature. (Embodiment 4) FIG. 4 has a governor valve 10a and a variable stator vane 29 for controlling the furnace top pressure, the power generation end output or the number of revolutions by the control signals V ₇ and V ₁₀ from the electric governor and the calculator 25. Fig. 7 shows still another embodiment for controlling the exhaust gas temperature at the outlet of the turbine blade cascade in the operating turbine so as not to fall below the saturation temperature. That is,
A temperature detector 22 is arranged in the turbine outlet pipe 13, and its signal V ₅ is introduced into a temperature controller 23, and this temperature controller 23
The inlet stop valve 10b is throttled by a control signal V ₁₅ from the above to reduce the turbine inlet gas pressure so that the turbine blade row outlet gas temperature does not fall below the saturation temperature. (Example 5) FIG. 5 is a chromatic electric governor and the furnace top pressure by the control signal V _7, V ₁₀ from the arithmetic unit 25, a governor valve 10a and the variable stator vanes 29 for controlling the power output or rotation speed This is another embodiment for controlling the exhaust gas temperature at the turbine blade cascade outlet so as not to fall below the saturation temperature in the turbine 12 that is operating. That is, the temperature detector 30 and the pressure detector 31 are provided in the third pipeline 11,
The respective signals V ₁₂ and V ₁₃ are input to the pressure regulator 21, and the inlet valve 10b is throttled by the control signal V ₁₅ . (Embodiment 6) FIG. 6 shows a turbine 12 having a variable vane 29 for controlling the furnace top pressure, the power generation end output or the rotation speed by a control signal V ₁₀ from the electric governor and the calculator 25. It is another embodiment for controlling the exhaust gas temperature at the blade cascade outlet so as not to fall below the saturation temperature. That is, the signal V ₅ is introduced from the temperature detector 22 of the turbine outlet pipe 13 into the temperature controller 23, and the inlet stop valve 10b is throttled by the control signal V ₁₅ . (Embodiment 7) FIG. 7 shows a turbine 12 having a variable stator vane 29 for controlling the furnace top pressure, the power generation end output or the rotation speed by a control signal V ₁₀ from the electric governor and the calculator 25. It is another embodiment for controlling the exhaust gas temperature at the blade cascade outlet so as not to fall below the saturation temperature. That is, the temperature detector 30 is connected to the third conduit 11.
Further, a pressure detector 31 is provided, the respective signals V ₁₂ and V ₁₃ are input to the pressure adjuster 21, and the inlet stop valve 10b is throttled by the control signal V ₁₅ .

[0015]

The method of preventing corrosion of the furnace top pressure recovery turbine according to the present invention comprises a blast furnace, a turbine inlet, and a wet dust collector.
And a second pipeline having a dry dust collector and a second switching valve, the first pipeline and the second pipeline, and the pressure adjustment. In the furnace top pressure recovery turbine connected to the third pipeline having the mechanism, the drain mist analyzing means is arranged in the turbine outlet pipe, and the signal of the drain mist analyzing means is introduced into the determining means,
A signal from the discriminating means is introduced into the operation confirming means, and one of the first switching valve and the second switching valve or the pressure adjusting mechanism is operated by the signal from the operating confirming means. ing.

Therefore, when the drain mist analysis means detects a corrosive component of a specified value or more, either dry type or dry / wet mixed operation is determined, and the turbine inlet gas pressure is controlled during dry operation to control the turbine. The temperature of the gas at the blade outlet is kept above the saturation temperature to prevent the generation of condensed mist. On the other hand, during dry-wet mixing operation, the operation is switched to wet operation, so the concentration of corrosive components contained in the mist inside the turbine is low and it is possible to prevent or reduce the corrosion of the main part of the turbine, enabling long-term continuous operation. Has the effect of becoming.

[Brief description of drawings]

FIG. 1 is a system diagram of a method of preventing corrosion in a top pressure recovery turbine according to the present invention during dry and wet mixed operations.

[Fig. 2] As a control method during dry operation of a method for preventing turbine corrosion in a furnace top pressure recovery turbine according to the present invention, in a turbine having a speed control valve and variable vanes, the speed control valve is controlled by the turbine outlet gas temperature. It is a system diagram.

FIG. 3 is a control method during dry operation of a method for preventing corrosion of a turbine in a furnace top pressure recovery turbine according to the present invention, in which a speed control valve and a turbine having variable vanes are used to control the speed control valve by turbine inlet gas temperature and pressure. FIG.

FIG. 4 is a control method during dry operation of a method of preventing corrosion of a turbine in a furnace top pressure recovery turbine according to the present invention, in which a turbine having a speed governing valve and variable vanes controls an inlet stop valve according to a turbine outlet temperature. It is a system diagram.

[FIG. 5] As a control method during dry operation of a method for preventing turbine corrosion in a furnace top pressure recovery turbine according to the present invention, an inlet stop valve is controlled by a turbine inlet gas temperature and pressure in a turbine having a speed governing valve and variable vanes. FIG.

FIG. 6 is a system diagram in which an inlet stop valve is controlled by a turbine outlet temperature in a turbine having variable vanes as a control method during dry operation of a method for preventing turbine corrosion in a furnace top pressure recovery turbine according to the present invention. .

FIG. 7 is a diagram showing a method of controlling an inlet stop valve in a turbine having variable vanes by controlling the temperature and pressure of turbine inlet gas as a control method during dry operation of a method for preventing corrosion of a turbine in a furnace top pressure recovery turbine according to the present invention. It is a system diagram.

FIG. 8 is a system diagram of a conventional dry and wet combined furnace top pressure circuit turbine.

[Explanation of symbols]

1 Blast Furnace 2 Dust Catcher 3 Pipes 4a, 4b Wet Dust Collector 5 First Switching Valve 6 First Pipeline 7 Dry Dust Collector 8 Second Switching Valve 9 Second Pipeline 10 Flow Control Mechanism 10a Speed Control Valve 10b Inlet Stop valve 11 Third line 12 Turbine 14 Dust concentration meter 15 Drain mist analysis means 16 Collection pocket 17 Drain discharge device 18 Drain component analysis device 19 Alarm sequence 20 Operating condition change sequence 21 Throttle valve controller 22,30 Temperature detection 23 Temperature controller 24 Subtractor 25 Electric governor and calculator 26 Ratio setter 27 Adder 28 Stator vane variable mechanism 29 Stator blade 31 Pressure detector 32 Pressure regulator

Claims (1)

[Claims] 1. A first pipeline having a wet dust collector and a first switching valve for a blast furnace and a turbine inlet, a second pipeline having a dry dust collector and a second switching valve, and the first pipeline. In a furnace top pressure recovery turbine in which a pipe line and a second pipe line are combined and connected by a third pipe line having a pressure adjusting mechanism, a drain mist analysis means is arranged in a turbine outlet pipe, The signal of the drain mist analyzing means is introduced into the discriminating means, the signal from the discriminating means is introduced into the operation confirming means, and the signal from the operation confirming means is used for the first switching valve and the second switching valve or the above. A method for preventing corrosion of a furnace top pressure recovery turbine in which either one of the pressure adjusting mechanisms is operated.