JPS5948290B2 - Blast furnace top pressure power recovery method using dry dust remover - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a blast furnace top pressure power recovery method using a dry dust remover. The conventional blast furnace top pressure power recovery method is as shown in Figure 1.
B at approximately 130°C to 150°C discharged from the top of blast furnace 1
The gas passes through a coarse dust remover (to the dust catch) 3 provided in the gas path 2 and enters a wet type dust remover 4 such as a venturi scrubber or a wet type EP (electrostatic precipitator). After the furnace top pressure is adjusted by a septum valve (furnace top pressure adjustment valve) 5, it is led to a gas holder 6. Reference numeral 7 denotes a power generation facility installed in parallel with the septum valve 5, which is constantly connected to the power grid in the plant and has a heavy load. B gas is supplied from the side through the inlet cutoff valve 10 and the turbine governor valve 11, and after driving the gas turbine 9, the B gas is output through the inlet cutoff valve 12 to the -1 side of the septum valve 5. In such a conventional method, it is used in the following two ways: ○ Moist B gas at 40°C to 60°C from the wet dust remover 4 is heated to 120°C to 120°C by partial combustion of the B gas. The gas is heated to about 140°C and introduced to the turbine 9. This raises the gas temperature sufficiently to prevent moisture condensation within the turbine 9 and prevents dust from accumulating on the turbine blades. ○Wet type dust remover 4 The moist B gas from the air is directly guided to the turbine 9.The idea is to wash away the dust with water droplets, so
To prevent water droplets from attacking the blade material, axial flow turbines eliminate stationary blades, although this is less efficient, and axial flow turbines, although more expensive, use multiple stages to reduce relative speed. In any of the above-mentioned embodiments, power is recovered from the B gas after passing through the wet dust remover 4, so the B gas has already been cooled, so it cannot be said to be an effective power recovery method. As mentioned above, B gas is discharged from the top of the furnace at a temperature of 130°C to 150°C, so if it can be guided to the turbine 9 at this temperature, the power recovered by the turbine 9 will be 2.
Increases from 0 to 35%. Therefore, instead of the wet type dust remover 4 shown in Fig. 1, a dry type EP
It is possible to use a dry dust remover such as a bag filter or a bag filter. However, such dry dust removers are generally not suitable for high temperatures;
The atrium of the blast furnace 1 cannot withstand the high temperatures (gas temperature rises to 500°C to 700°C). Another dry dust removal method uses granular solids such as sand for the filtration layer, but it is fine and thin like blast furnace dust.
There are considerable technical problems in filtering sticky dust. Therefore, the present invention provides a blast furnace top pressure power recovery method that can solve the above problems while using a dry dust remover such as a dry EP or a bag filter. This will be explained based on FIG. In FIG. 2, the same reference numerals as in the conventional example (FIG. 1) indicate the same components. Namely, 1 is a blast furnace, 2 is a gas path, 3 is a coarse dust remover, 5 is a septum valve, 6 is a gas holder, 7 is a power generation equipment,
8 is a generator, 9 is a gas turbine, 10 is an inlet shutoff valve, 1
Reference numeral 1 indicates a turbine governor valve, and reference numeral 12 indicates an outlet shutoff valve. In the present invention, a dry dust remover 13 such as a dry EP or a bag filter is provided in place of the conventional wet dust remover. and in said gas flow 2 which includes a coarse dust remover 3;
A plurality of (three shown in the example) cooling fluid injectors 15A, 15B, 1 each having an electric valve 14A, 14B, 14C.
5C, and cooling fluid supply channels 16A, 16B,
16C is connected. Here, the injectors 15A, 15B, and 15C may be located at the top of the riser pipe as shown in FIG. The maximum injection amount (maximum opening degree) of each electric valve 14A, 14B, 14C may be
(θ■M1) (θVM2) (θ■M3) is constant. A temperature detection sensor 18 is provided in the pipe 17 near the gas outlet of the dry dust remover 13. This sensor 18 detects the B discharged from the dry dust remover 13.
The temperature of the gas is detected and a detected temperature signal T is issued to the control section 19. At the initial stage when the temperature detection sensor 18 detects a temperature higher than the setting, the control unit 19 controls the temperature detection sensor 18.
From then on, according to the temperature rise rate by the signal T from the Based on the cooling fluid injector 15A,
Number of 15B and 15C used and the cooling fluid injector 1
5A, 15B. Electric valves 14A, 14B, 14C provided in 15C
Each injector 15A, 15B, 15
A cooling fluid 20 such as cooling liquid or cooling gas is injected from C into the gas path 2 to cool the B gas. Incidentally, stepwise means that the cooling fluid 20 is first injected from the downstream injector 15A, and when the electric valve 14A reaches the maximum injection amount, it is injected from the one upstream injector 15B, and then sequentially from the upstream injector 15C. It is to move on to... Of course 15A and 15B. 15C may be at the same location in the gas path 2. That is, in the control unit 19, as shown in FIG. 3, the set temperature signal (T1) from the temperature setting device 21 and the detected temperature signal T of B gas from the sensor 18 are input to the adder 22, and the difference between them is input to the adder 22. (ΔT), that is, [ΔT=T1−Tl
is determined and input to the circuit switch 23. Here, [ΔT<0], that is, the detected temperature signal T of B gas
is higher than the set temperature signal (T1), the difference (-ΔT
) is input to the arithmetic unit 24. The computing unit 24 increases the valve opening signal in proportion to (-ΔT) in consideration of the cooling effect, and also increases the valve opening signal in proportion to the temperature rise per unit time in order to compensate for the thermal inertia of the system. Then, the valve opening signal is further increased, and if the temperature starts to drop even if it is above the set temperature, the valve opening signal is decreased depending on the temperature and its rate of decline (per unit time), or as necessary. generates a signal that causes the engine to open fully. The calculation transfer function of this calculation unit 24 may be, for example. where k is the proportionality constant, S is the Laplace operator, (TD) is the differential time constant, and (1+TFs) is the valve opening that would otherwise be differentially calculated by (TDS) if there was a sudden temperature change. degree signal A. B and C fluctuate extremely rapidly, electric valves 14A and 14B. 14C, etc., so this filter is provided to alleviate this action, and (TF) is a filter temporary constant. The output signal (θ1) from the computing unit 24 is transmitted to the electric valves 14A and 14B as described later. The opening signals A, B, and C of 14C are generated. Note that when [ΔT≧0], that is, when the temperature of B gas is lower than the set temperature, the signal transmission path is switched by the determination and circuit switch 23, and the signal is transmitted to the 0 generator 25 manually. The O generator 25 controls the electric valve opening degree.

Signal E to set it to [0]
is given to the amplifier (described later). As a result, the electric valve opening degree is

[0], the injection of the cooling fluid 20 from the injector is stopped, and the cooling by the cooling fluid 20 is stopped.6 The output signal (θ,) from the arithmetic unit 24 is sent to the first discrimination and circuit switching device 26A. enter. This first discrimination and circuit switching device 26A receives a signal (θ, )
is smaller than the maximum injection amount (θVM1) of the first electric valve 14A, this signal (θ, ) is given to the first amplifier 27A. That is, this signal (θ,) and the first potentiometer 2
The signal (θ) from 8A enters the first adder 29A, and the difference is amplified by the first amplifier 27A to form the opening signal A, which drives the first electric valve 14A by a so-called servo mechanism. In response to the opening movement of the first electric valve 14A, the injection amount of the cooling fluid 20 from the injector 15A is controlled, and the degree of cooling of the B gas is controlled. At this time, the second and third electric valves 14B and 14C are operated by the first and second switch circuits 30A and 30B, respectively.
20th generator 31A. 31B, and the valve opening degree is controlled to be [O]. The signal (θl) is the maximum injection amount (θVM) of the first electric valve 14A.
1), this signal (θ, ) is given to the third switch circuit 30C, the first θVM transmitter 32A and the first electric valve control circuit are connected, and the signal (θVM.) causes the first electric valve 14A to operate. At the same time, the signal (θ, ) is given to the fourth switch circuit 30D, which is activated, and the signal (θ M1) from the first θVM oscillator 32A enters the first polarity inverting amplifier 33A.
From here, [-θ■M1] is output. This signal [-θ■M1] and the first discrimination and circuit switch 2
The signal (.theta.1) from 6A is added by the fourth adder 29D, and the [.theta., +(-.theta..multidot.M1)] signal is manually input to the second discrimination and circuit switching device 26B. This [θ1+(-θVMI)) signal is [θ■M2]
When the [θ, +(−θVMI)) signal is smaller than the second
It is given to the second amplifier 27B as an opening degree control signal for the electric valve 14B, and the second electric valve 14B is appropriately controlled by the opening degree signal B. At the same time, the [θ, +(-θVMI)] signal is given to the second switch circuit 30B, and the 20th generator 31B and the third electric valve control circuit are connected.

[0] The third electric valve 1 is activated by the signal.
4C is fully opened. When the [θ1+(-θVMI)] signal is larger than [θ■M3], the fifth switch circuit 30E is activated as described above.
The signal from the second θVM oscillator 32B (θ■M2)
The second electric valve 14B is fully opened, and the sixth switch circuit 30
F conducts and the signal from the second θVM oscillator 32B (θ■
M2) enters the second polarity inverting amplifier 33B, and this output (-θ M2) and the output [θ, -(-θ M1)] from the second discrimination and circuit switch 26B are sent to the fifth adder 29E. and the sum [θ, + (-θVM, ) + (-θVM
2)] is given to the third amplifier 27C as an opening degree control signal for the third electric valve 14C, and the third electric valve 14C is appropriately controlled by the opening degree signal C. At this time, of course, the first electric valve 14A receives the signal (θV
M1) is input to the first amplifier 27A, so it is fully open. When each electric valve 14A, 14B, 14C reaches the fully open or fully closed position, in order to prevent excessive rotation of -L from occurring thereafter, a limiter is provided at the fully open or fully closed position as necessary.
It is also possible to cut off the current to the electric valves 14A, 14B, and 14C. In the figure, 28B is the second potentiometer, 28C is the third potentiometer, 29B is the second adder, and 29C is the third potentiometer.
An adder is shown. The reason why the temperature detection sensor 18 is provided downstream of the dry dust remover 13 is to prevent the sensor 18 from being covered with dust and causing a time delay in detecting abnormal temperature. That is, for example, when the amount of dust upstream of the dry dust remover 13 is 3' to Log/Nm3, the amount of dust downstream is 10 mg/Nm3 or less. In addition, as shown in Fig. 4, piping 1 from the dry dust remover 13
The temperature measuring section 34 of the sensor 18 provided in the sensor 7 is directly exposed to the B gas so that there is no time delay in temperature detection. The time delay (within 2 seconds) caused by providing the sensor 18 after the dry dust remover 13 does not substantially pose any problem. That is, since the time delay from detection of the set temperature to the injection of cooling fluid is also within 1 second, the total time delay is about 3 seconds. In addition, the initial temperature rise in the atrium is at most 15°C/second,
During a total time delay of approximately 3 seconds, the gas temperature increases by only 45°C. Now let's consider a bag filter with a maximum operating temperature of 240°C. When the set temperature is 170°C, the gas temperature when injecting the cooling fluid 20 is the highest, [170°C + 45°C = 215°C]
This is a value sufficiently lower than the maximum operating temperature. As described above, as the cooling fluid 20, a cooling gas using sensible heat and a cooling liquid using latent heat are used. As a cooling gas, there is no need to worry about B gas becoming wet. (a) 3 to 6 atg water vapor, (b) N2. Inert gas such as CO2, reducing gas such as (c) B gas, C gas (coke oven gas), etc. are used. In addition, the cooling liquid must be completely evaporated in the B gas before it reaches the dry dust remover 13 in order to prevent the dust from caking. fuel, etc. are used. In the case of (e), when both fuels are used, the injected fuel evaporates and mixes with the B gas, temporarily increasing the calorific value of the B gas and causing no loss. In this case, the piping is smaller and the power required for injection is smaller than in the case of cooling with cooling gas. As shown in FIG. 5, the temperature detection sensor 18 is located at the upper part of the cross section of the pipe through which the highest temperature gas flows because there is a temperature distribution in the pipe 17. desirable. According to the present invention described above, the following effects can be expected. (b) Both the coarse dust remover and the fine dust remover are dry type and do not use washing water for dust removal, so the thermal energy of the blast furnace gas generated from the top of the blast furnace is hardly lost during dust removal. , the high-temperature gas discharged from the top of the furnace can be directly guided to the turbine, and the amount of energy recovered by the turbine on the downstream side can be increased. Moreover, even after dust removal, the amount of clean gas (even though it is called clean) is 5mg/N.
Contains about m3 of dust. ) is dry, so it does not cause corrosion to the various equipment installed on the downstream side (turbine, valves, piping, various detectors, etc.). Since it does not adhere to the turbine blades, troubles can be minimized. (b) Since both dust removers are dry types, dust can be removed as is, eliminating the need for large and expensive thickeners and water treatment equipment that would be required in the case of a wet type, which generates a large amount of sewage. (c) When the gas temperature becomes abnormally high due to blast furnace blow-through, etc., the initial temperature sensor detects the abnormally high temperature and supplies cooling fluid to the gas path to cool the high-temperature gas. After that, the temperature will be lowered, and an adverse effect on the dry dust remover can be prevented. (ii) Since the gas is not cooled during normal blast furnace operation, the high-temperature gas discharged from the top of the furnace can be directly guided to the turbine, increasing the amount of energy recovered by the turbine. (e) By installing the temperature detection sensor near the gas outlet of the dry dust remover, there is no wear due to dust.
The temperature measurement part can be directly exposed to blast furnace gas without a protection tube.
Therefore, the detection delay is small and the detection is accurate. Furthermore, as mentioned above, since the blast furnace gas is dry, even the slightest fine dust in the gas will not adhere to the temperature measurement unit, making it possible to accurately (quickly) detect abnormal temperatures without time delay. can. (f) At the initial stage when the temperature detection sensor detects a temperature higher than the set temperature, it will be used in a predetermined order according to the temperature increase rate, and thereafter, according to the temperature increase rate and amount of temperature increase. First, the number of cooling fluid injectors used and the opening degree of the electric valve provided in the cooling fluid injectors are controlled to increase or decrease the amount of cooling fluid, thereby controlling the blast furnace gas temperature. The amount of cooling fluid most suitable for the climbing situation can be injected. In other words, if the blast furnace gas is cooled more than necessary due to over-injection of cooling fluid, the gas becomes too wet and the function of the dry-type dust remover deteriorates, and if too little is injected, the gas that is not cooled sufficiently will be According to the present invention, these problems can be prevented and automatic control can be made possible. Furthermore, when cooling water is used as the cooling fluid to be injected, by limiting the amount of water so that the cooling water completely evaporates, generation of dirty water can be prevented, and thickeners and water treatment equipment can therefore be made unnecessary.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing a conventional example, Figs. 2 to 5 show an embodiment of the present invention, Fig. 2 is a system diagram, Fig. 3 is a control circuit diagram, and Figs. 4 and 5. Each is an enlarged view of the sensor installation part. 1... Blast furnace, 2... Gas path, 7...
...Power generation equipment, 9...Gas turbine, 13
...Dry type dust remover, 14A. 14B, 14C...Electric valve, 15A, 15B,
15C...Cooling fluid injector, 18...
Temperature detection sensor, 19...control unit, 20.
...cooling fluid.

Claims (1)

[Claims] 1. In a blast furnace top pressure power recovery method in which gas discharged from a blast furnace is guided to a dry dust remover to remove dust while keeping its pressure almost constant, and then expanded in a turbine to recover power, the blast furnace A plurality of cooling fluid ejectors each having an electric valve are arranged in the gas path including the coarse dust dust remover from the dry dust remover to the dry dust remover, and a temperature sensor is installed near the gas outlet of the dry dust remover. The sensor for temperature detection and each of the electric valves are connected to a control unit, and when the temperature detection sensor detects a temperature higher than the set value, a control signal from the control unit based on the detected temperature signal is used to control the temperature at the initial stage of detection. Temperature - Depending on the temperature rise rate, and thereafter depending on the temperature rise rate and temperature rise amount, the number of used cooling fluid injectors and the number of cooling fluid injectors provided in the cooling fluid injector are determined based on a predetermined order. A blast furnace top pressure power recovery method using a dry dust remover characterized by controlling the opening degree of an electric valve to supply the necessary amount of cooling water into the gas path.