JPH0777060A - Bypass operation method for blast furnace gas recovery device and blast furnace top pressure recovery turbine - Google Patents

Abstract

PURPOSE:To provide a bypass operation device which is constituted to collect and purify dust in blast furnace gas by a dry type dust collector when a furnace top pressure recovery turbine and/or a generator is tripped and protect equipment situated downstream of blast furnace gas main pipe from a high heat and to provide an operation method. CONSTITUTION:Blast furnace gas is guided to a bypass pipe 4 and by regulating a cooling water amount of a cooling mechanism 3, the blast furnace gas is cooled to a preset temperature. A pressure is reduced to a value at which blast furnace gas is prevented from a reverse flow from a downstream blast furnace gas main pipe 10 and the gas is recovered to the blast furnace gas main pipe 10, whereby equipment installed downstream of the blast furnace gas main pipe is protected from a high heat. Since, after repair of trip, a furnace top pressure recovery turbine 6 is started by means of blast furnace gas freed from dust and purified by a dry type dust collector and having high energy, recovery efficiency of fed energy is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bypass operating device and operating method for a blast furnace top pressure recovery turbine during trip of the blast furnace top pressure recovery turbine and / or generator during blast furnace operation.

[0002]

2. Description of the Related Art Since blast furnace gas (B gas) generated in the furnace during operation of the blast furnace is useful as a fuel, it is supplied to the required equipment through the blast furnace gas main line after being cleaned without dust as it is. And use it as fuel. In recent years, such a blast furnace gas recovery system has been disclosed in, for example, Japanese Examined Patent Publication No. 3-77845 and “Industrial Heating” (Vo
1.25, No. 4, p. 17), it is shown that a wet dust remover is used together with a dry dust remover to clean and remove gas and control the temperature. A schematic diagram of such a general blast furnace gas recovery system is shown in FIG.

In the normal operation of the blast furnace, the blast furnace gas generated in the blast furnace 17 has a large amount of dust, so that the dust remover 20 is first used.
Is sent to the dry type dust remover 18 after the coarse particles are separated and settled to a considerable extent to remove the dust. Dry type dust remover 18
The blast furnace gas sent to the above enters the crude gas distributor 24 via the shutoff valve 22 at the inlet, and from there, enters the plurality of bag chambers 25 arranged radially about the distributor. 26
Is a bag filter in the bag chamber, which removes fine dust in the crude gas, and the cleaned blast furnace gas is shut off through a pipe 27 and an annular pipe 28 which communicates each bag chamber at its bottom. Valve 29 to top pressure recovery turbine 6
Is sent to the blast furnace gas main pipe 10 after giving rotational energy to the furnace top pressure recovery turbine 6. At this time, the butterfly valve 32 provided at the inlet and the butterfly valve 33 provided at the outlet of the wet dust remover 19 including the venturi scrubber 30 and the mist separator 31 are closed.

On the other hand, when the blast furnace gas is subjected to wet dust removal, the shutoff valves 22 and 23 and the butterfly valve 2 provided at the inlet of the dry dust remover.
1. The shut-off valve 29 at the outlet is closed and the blast furnace gas dusted by the dust remover 20 is sent to the venturi scrubber 30. The fine dust in the blast furnace gas that has entered the venturi scrubber 30 is removed by spraying water, etc.
At that time, the moisture is removed to form a clean gas, which is sent to the furnace top pressure recovery turbine 6. However, the temperature and pressure of the blast furnace gas cleaned by the wet dust remover 19 are remarkably lowered, and the effective energy of the blast furnace gas when sent to the furnace top pressure recovery turbine 6 is low. 1
9 is closed.

Now, during operation of the dry dust remover during operation of the blast furnace, the furnace top pressure recovery turbine 6 is
Alternatively, if the generator 7 trips, the shutoff valve 8 at the inlet of the furnace top pressure recovery turbine 6 is closed and the dry dust remover 18
The gas pressure adjusting valve 5 in the bypass pipe 4 connecting the dust removal pipe 34 and the blast furnace gas main pipe 10 on the outlet side of the furnace top pressure recovery turbine 6 is opened to allow the blast furnace gas to pass through the bypass pipe 4.
Send to the blast furnace gas main 10. Furthermore, when the furnace top pressure recovery turbine 6 and / or the generator 7 are stopped for a long time for restoration, the water sealing valve 9 after the furnace top pressure recovery turbine 6 is also closed. The blast furnace gas that has passed through the dry dust remover 18 and has been cleaned by dust removal has a high temperature and high pressure. For this reason, the bypass pipe 4 is provided with a water spray type cooling mechanism 3 for cooling the blast furnace gas in order to protect the equipment of the gas pressure adjusting valve 5. The cooling mechanism 3 cools the gas pressure adjusting valve 5 to the heat resistant temperature.
In addition, the pressure is adjusted by the gas pressure control valve 5 to the blast furnace gas main pipe 10.
The pressure is reduced to. Further, the gas pressure adjusting valve 5
Holds the function of automatically opening and closing the blast furnace top pressure by a fluctuation signal of the blast furnace top pressure.

The bypass operation is executed when it is predicted that the time from the trip of the furnace top pressure recovery turbine 6 and / or the generator 7 to the restart thereof is up to about 2 hours,
When it is longer than that, the method for removing dust from the blast furnace gas is switched from the dry method to the wet method to operate.
This is because the cooling mechanism 3 has the durability temperature (1
The amount of water injection is determined so as to cool it to 20 to 130 ° C., and this temperature is the heat resistant temperature (50 to 80) of the blast furnace gas holder and expansion joint arranged downstream of the blast furnace gas main 10.
This is because the temperature is higher than that of (° C), and there is a risk of damaging these facilities over a long period of time.

Next, in restarting the furnace top pressure recovery turbine 6 after the trip is solved, first, the shutoff valve 8 at the inlet of the furnace top pressure recovery turbine 6 is opened, and the shutoff valve 8 and the furnace top pressure recovery turbine 6 are connected. While gradually opening a control valve (not shown) provided therebetween, the gas pressure adjusting valve 5 is gradually closed and the furnace top pressure recovery turbine 6 is started up. After stabilizing the blast furnace gas properties,
Shutoff valves 22 and 23 provided at the inlet of the dry dust remover 18,
The shutoff valve 29 at the outlet is opened, the butterfly valve 21 at the inlet of the dry dust remover 18 is gradually opened, and the butterfly valve 32 provided at the inlet of the wet dust remover 19 and the butterfly valve 33 provided at the outlet are gradually opened. When closed, switching to the dust removal cleaning method by the dry dust remover 18 is performed. In other words, the method for removing dust from the blast furnace gas is switched from the wet method to the dry method with less energy loss.

[0008]

However, after the trip of the furnace top pressure recovery turbine 6 and / or the generator 7, in order to return to the normal operation state, that is, the operation by the dry dust removal method with less energy loss, the cause of the trip is In addition to restarting the furnace top pressure recovery turbine 6 after elucidation and restoration, it is necessary to switch from the wet dust removal method to the dry dust removal method. Compared to restarting with the dry dust removal method with less energy loss, this means that after restarting with the wet dust removal method, the power recovery amount is obtained with the wet dust removal method while switching from the wet dust removal method to the dry dust removal method. The difference between the generated electric power and the electric power obtained by the dry dust removal method causes a loss, which poses a serious problem in terms of economic efficiency. The present invention has been made in view of the above-mentioned conventional problems, and the furnace top pressure recovery turbine 6 and / or
Alternatively, when the generator 7 is tripped, the dry type dust remover 18 removes and cleans the blast furnace gas until the top pressure recovery turbine 6 is restarted, and the blast furnace gas temperature is set to the heat resistant temperature of the gas holder and the expansion joint downstream of the blast furnace gas main 10. It is an object of the present invention to provide an apparatus and a method for performing a bypass operation by lowering the temperature. Another object of the present invention is to provide a method for restarting the furnace top pressure recovery turbine 6 by the high-energy blast furnace gas that has been dust-cleaned by the dry dust remover 18 by the bypass operation.

[0009]

In order to achieve the above object, the present invention provides: A dry type dust collector (18) and a wet type dust collector (19) are provided side by side in the blast furnace gas recovery system, and after the blast furnace gas is supplied to the furnace top pressure recovery turbine (6) through one of the above dust collectors,
In a facility for recovering blast furnace gas to the blast furnace gas main pipe (10), required cooling is performed by signals of the temperature, pressure and flow rate of the blast furnace gas in the dust remover pipe (34) and the cooling water temperature signal of the cooling mechanism (3). It is characterized by being provided with an arithmetic unit (1) for calculating the amount of water. 2. The flow rate control valve (1) is calculated by the calculation result of the calculation device (1) and the signal of the amount of cooling water injected from the cooling mechanism (3).
6) is provided with a control device (2) for controlling opening and closing. 3. A dry dust collector (18) and a wet dust collector (19) are provided together in the blast furnace gas recovery system, and the blast furnace gas is fed to the dry dust collector (1).
After supplying to the furnace top pressure recovery turbine (6) via 8),
In the blast furnace gas recovery method for recovering the blast furnace gas to the blast furnace gas main pipe (10), the furnace top pressure recovery turbine (6) and / or the generator (7) immediately after tripping the furnace top pressure recovery turbine (6 ) A cooling mechanism (3) provided in the path of the bypass pipe (4) by closing the shutoff valve (8) at the inlet and opening the gas pressure adjusting valve (5) to pass the blast furnace gas through the bypass pipe (4) ), When cooling the blast furnace gas, while adjusting the water injection flow rate in the cooling mechanism (3) so as to cool the blast furnace gas to a preset temperature,
The gas pressure adjusting valve (5) reduces the blast furnace gas pressure on the inlet side of the gas pressure adjusting valve (5) to be higher than the blast furnace gas pressure on the outlet side of the main valve, and recovers the blast furnace gas to the blast furnace gas main pipe (10). It is characterized by doing.

[0010]

When the top pressure recovery turbine 6 and / or the generator 7 are tripped, a water spray type cooling mechanism 3 is used which can obtain fine water droplets, and the blast furnace gas is generated by latent heat when the water droplets are evaporated. Is adjusted to the heat resistant temperature (about 50 ° C.) of, for example, the gas holder installed downstream of the blast furnace gas main 10, so that the furnace top pressure recovery turbine 6 and / or the generator 7 trips. Until the system is restarted, it is possible to prevent equipment damage due to high heat such as the gas holder and expansion joints installed downstream of the blast furnace gas main 10. Further, after the recovery, the furnace top pressure recovery turbine 6 and the generator 7 can be started by the high-energy blast furnace gas that has been dust cleaned by the dry dust remover 18.

4 to 7 show an example of a water spray nozzle type cooling device. The mechanism of the present cooling mechanism in FIG. 4 will be described below. That is, the cooling water is pipe 4
1 through a header 42 installed on the upper part of the pipe. The water that has entered the header 42 is sprayed in a spray state from a large number of small holes 43 provided in the header 42. The mechanism of the present cooling mechanism in FIG. 5 will be described below. That is, the cooling water passes through the pipe 51 and enters the spherical header 52 installed at substantially the center of the bypass pipe 4. Header 52
Has a large number of small holes 53, and the cooling water is sprayed from the small holes 53 in a spray state. The mechanism of the present cooling mechanism in FIG. 6 will be described below. That is, the cooling water passes through the pipe 61 and enters the annular header 62. Header 62
The entering cooling water passes from the top, bottom, left and right of the header 62 to the nozzle 63 directed toward the center of the bypass pipe 4, and is sprayed in a spray state from a small hole 64 arranged at the tip of the nozzle 63 and on the downstream side of the blast furnace gas. The mechanism of this cooling mechanism in FIG. 7 will be described below. That is, the cooling water is pipe 7
1 and enters the header 72 installed on the upper part of the pipe. The cooling water entering the header 72 is distributed to a plurality of nozzles 73 from the lower part of the header 72 toward the center of the bypass pipe 4, and is sprayed from a small hole 74 arranged at the tip of the nozzle 73 and on the downstream side of the blast furnace gas. To inject.

The flow rate of the injected water is determined by the fact that the injected cooling water is entirely evaporated, the latent heat of evaporation thereof deprives the sensible heat of the blast furnace gas, and the blast furnace gas is cooled.
The relational expression is shown in Expression (1).

[0013]

[Equation 1]

W is a water injection flow rate (t / h). Cg is the specific heat (kcal / Nm) of the blast furnace gas passing through the bypass pipe.
³ ), which is a value determined by the temperature and pressure of the blast furnace gas. As a reference, when the gauge pressure is 2 kg / cm ² , the temperature is 2
00 ° C. In 0.367kcal / Nm ^3, which is 350 ° C. At 0.382kcal / Nm ^3. ΔTg is the temperature difference (° C) before and after cooling the blast furnace gas passing through the bypass pipe,
It is a value obtained by subtracting 50 ° C., which is the heat resistant temperature of the equipment downstream of the blast furnace gas main 10, from the temperature indicated by the thermometer 12. V is the amount of blast furnace gas (Nm ³ ) passing through the bypass pipe, which is measured by the meter 13. Cw is the specific heat (kcal / Nm ³ ) of water in the blast furnace gas passing through the bypass pipe, and is a value determined by the temperature and pressure of the blast furnace gas. As a reference, 0.3 at a temperature of 200 ° C when the gauge pressure is 2 kg / cm ^2.
45 kcal / Nm ³ , 0.355 kca at 350 ° C
1 / Nm ³ . M is the amount of water (Nm ³ / h) in the blast furnace gas that has been dust-cleaned by the dry dust remover that passes through the bypass pipe before water injection, and the blast furnace gas flow rate is 600,000 Nm ³
The present inventors have already confirmed by experiments that, when / h, the value is about 30,000 Nm ³ / h. S is the above-mentioned enthalpy (kcal / kg), which is a value determined by the temperature and pressure of the steam, and is shown in the steam table. Tw is the cooling water temperature (° C.) before injection and is measured by the thermometer 14.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing an embodiment of the present invention. In FIG. 1, 4 is a bypass pipe, the downstream end of which is connected to the blast furnace gas main pipe 10 and the upstream end of which is connected to the dust remover pipe 34. Reference numeral 3 is a water spray type cooling mechanism. Next, a bypass operation method of the present invention during the dust cleaning of the blast furnace gas by the dry dust collector and at the time of trip of the furnace top pressure recovery turbine 6 and / or the generator 7 will be described based on a specific example. FIG. 2 is a flowchart showing a bypass operation method when the furnace top pressure recovery turbine 6 and / or the generator 7 trip. Further, FIG. 3 is a flowchart showing a bypass operation method after the recovery of the furnace top pressure recovery turbine 6 and / or the generator 7 until the restart of the furnace top pressure recovery turbine 6 is completed. When the furnace top pressure recovery turbine 6 and / or the generator 7 trip during the dust cleaning of the blast furnace gas by the dry dust remover 18, first, the shutoff valve 8 at the inlet of the furnace top pressure recovery turbine 6 is closed to open the furnace top. The gas sent to the pressure recovery turbine 6 is shut off. At the same time, the gas pressure adjusting valve 5 on the bypass pipe 2 senses the blast furnace top pressure, opens and closes so as to keep the blast furnace pressure constant, and reduces the pressure from the blast furnace gas main pipe 10 to a pressure at which the blast furnace gas does not flow backward. At the same time, the arithmetic unit 1 and the control unit 2 are operated by the trip signal of the furnace top pressure recovery turbine 6 and / or the generator 7. The arithmetic unit 1 calculates the amount of cooling water required for cooling to the heat resistant temperature of the equipment on the downstream side of the blast furnace gas main pipe, using the values of the thermometers 12 and 14, the pressure gauge 11, and the flowmeter 13.

As an example, when the blast furnace gas temperature is 200 ° C., the flow rate is 600,000 Nm ³ / h, the gauge pressure is 2 kg / cm ² , and the cooling water temperature is 30 ° C., the heat resistant temperature of the downstream side equipment of the blast furnace gas main pipe is 5
The amount of cooling water required for cooling to 0 ° C. is as follows. In the formula (1), Cg is 0.352 kc
al / Nm ³ , ΔTg is 150 ° C., V is 600,000 Nm ³ /
h and Cw are 0.335 kcal / Nm ³ , M is 2986
7 Nm ³ / h, S is 664 kcal / kg, Tw is 30
℃. Therefore, the required cooling water amount is about 51 t / h. Next, the calculation result and the value of the flow meter 15 are input to the control device 2, and an open / close signal is sent to the flow rate control valve 16 so that both values become equal. The flow rate control valve 16 is the control device 2
The cooling water flow rate is adjusted by receiving the opening / closing signal and opening / closing operation.

Next, in order to restart the furnace top pressure recovery turbine 6 after the cause of the trip is determined and restored, first, the shutoff valve 8 at the inlet of the furnace top pressure recovery turbine 6 is opened, and the shutoff valve 8 and the furnace top pressure recovery are performed. A control valve (not shown) provided between the turbines 6 is gradually opened to introduce blast furnace gas into the furnace top pressure recovery turbine 6, and at the same time, the gas pressure adjusting valve 5 adjusts the opening so that the furnace top pressure becomes constant. While gradually closing it, the amount of blast furnace gas introduced into the furnace top pressure recovery turbine 6 is increased and then started.
After the flow rate and pressure of the blast furnace gas introduced into the furnace top pressure recovery turbine 6 become constant and become stable, the arithmetic unit 1 and the control unit 2 are stopped, the flow rate adjusting valve 16 is closed, and the cooling mechanism 3 is installed. Stop. In the present embodiment, the device having the cooling mechanism as shown in FIG. 4 has been described.
For example, it goes without saying that the cooling mechanism shown in FIGS. 5 to 7 can be similarly applied. Further, in the present embodiment, the dry dust remover 18 has been described as the device having the bag filter 26, but the present invention is not limited to this, and can be similarly applied to an electric dust collector.

[0018]

According to the present invention, a gas holder, expansion joint, etc. installed at the blast furnace gas temperature downstream of the blast furnace gas main by a cooling mechanism can be used without switching to a dust cleaning method using a wet dust remover with a large energy loss. By-pass operation is performed with a bypass pipe that cools to a heat-resistant temperature and recovers to the blast furnace gas main, so after recovery of the furnace top pressure recovery turbine and generator, it is a high-energy blast furnace gas that has been dust cleaned by a dry dust remover. The furnace top pressure recovery turbine can be restarted, and the effect of recovery efficiency as energy can be improved.

[Brief description of drawings]

FIG. 1 is a schematic side sectional view showing an example of an embodiment of bypass operation according to the present invention.

FIG. 2 is a flowchart showing a bypass operation method at the time of trip of a furnace top pressure recovery turbine and / or a generator.

FIG. 3 is a flowchart showing a bypass operation method after trip recovery.

FIG. 4 is a diagram showing an example of an embodiment of a cooling mechanism used in the present invention.

FIG. 5 is a diagram showing an example of an embodiment of a cooling mechanism used in the present invention.

FIG. 6 is a diagram showing an example of an embodiment of a cooling mechanism used in the present invention.

FIG. 7 is a diagram showing an example of an embodiment of a cooling mechanism used in the present invention.

FIG. 8 is a schematic side sectional view showing an outline of a blast furnace gas recovery device.

[Explanation of symbols]

 1 computing device 2 control device 3 cooling mechanism 4 bypass pipe 5 gas pressure adjusting valve 6 furnace top pressure recovery turbine 7 generator 8 shutoff valve 9 water sealing valve 10 high pressure gas main pipe 11 pressure gauge 12 thermometer 13 flowmeter 14 thermometer 15 Flowmeter 16 Flow control valve 17 Blast furnace 18 Dry dust remover 19 Wet dust remover 20 Dust remover 21 Butterfly valve 22 Shutoff valve 23 Shutoff valve 24 Coarse gas distributor 25 Bag chamber 26 Bag filter 27 Piping 28 Ring pipe 29 Shutoff valve 30 Venturi Scrubber 31 Mist separator 32 Butterfly valve 33 Butterfly valve 34 Dust collector piping 41 Piping 42 Header 43 Small hole 51 Piping 52 Header 53 Small hole 61 Piping 62 Header 63 Nozzle 64 Small hole 71 Piping 72 Header 73 Nozzle 74 Small hole

Claims (3)

[Claims] 1. A dry type dust collector (18) and a wet type dust collector (19) are provided side by side with a blast furnace gas recovery system, and blast furnace gas is supplied to a furnace top pressure recovery turbine (6) through one of the dust collectors. In the facility for recovering the blast furnace gas to the blast furnace gas main pipe (10), the required temperature, pressure, flow rate signal of the blast furnace gas in the dust remover pipe (34) and the cooling water temperature signal of the cooling mechanism (3) A blast furnace gas recovery system comprising a calculation device (1) for calculating the amount of cooling water. 2. A control device (2) for controlling the opening and closing of the flow rate control valve (16) according to the calculation result of the calculation device (1) and a signal of the amount of cooling water injected from the cooling mechanism (3). The blast furnace gas recovery device according to claim 1. 3. A dry type dust collector (18) and a wet type dust collector (19) are provided together in the blast furnace gas recovery system, and after the blast furnace gas is supplied to the furnace top pressure recovery turbine (6) through the dry type dust collector (18). In the blast furnace gas recovery method in which the blast furnace gas is recovered into the blast furnace gas main pipe (10), the furnace top pressure recovery turbine (6) and / or the generator (7) immediately after the trip, the furnace top pressure recovery turbine ( 6) A cooling mechanism provided in the path of the bypass pipe (4) by closing the shutoff valve (8) at the inlet and opening the gas pressure adjusting valve (5) to pass the blast furnace gas through the bypass pipe (4) ( When cooling the blast furnace gas by 3), the water injection flow rate in the cooling mechanism (3) is adjusted so as to cool the blast furnace gas to a preset temperature, and the gas pressure adjusting valve (5) adjusts the gas pressure adjusting valve (5). 5) The blast furnace gas pressure on the inlet side is A bypass operation method for a blast furnace top pressure recovery turbine, characterized in that the blast furnace gas is decompressed to a pressure higher than the blast furnace gas pressure on the valve exit side and the blast furnace gas is recovered in the blast furnace gas main pipe (10).