JPS6240531B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blast furnace top pressure power recovery system using a dry dust remover.

As shown in Figure 1, the conventional blast furnace top pressure power recovery system uses approximately 130
B gas at a temperature of 150° C. passes through a coarse dust catcher 3 provided in the gas path 2 and enters a wet dust remover 4 such as a bench scrubber or a wet EP (electrostatic precipitator). After passing through a septum valve (furnace top pressure adjustment valve) 5 that adjusts the furnace top pressure, 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 always connected to the in-house power grid and has a heavy load. The B gas introduced through the inlet cutoff valve 10 and the turbine governor valve 11 is supplied, and after driving the gas turbine 9, the B gas is returned to the outlet side of the septum valve 5 through the outlet cutoff valve 12. Such conventional systems are used in the following two ways.

Moist B gas at 40° C. to 60° C. from the wet dust remover 4 is heated to about 120° C. to 140° C. by partial combustion of the B gas, and then guided 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.

The wet B gas from the wet dust remover 4 is directly guided to the turbine 9. The idea behind this is to wash away the dust with water droplets, so in order to prevent the water droplets from attacking the blade material, a radial turbine eliminates stator blades, although this is less efficient, and a radiant turbine uses multiple stages, although it is more expensive. Considerations are being taken to reduce the 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
Since it is discharged from the top of the furnace at a temperature of 130°C to 150°C, if it can be led to the turbine 9 at this temperature, the power recovered by the turbine 9 will increase by 20 to 35%. Therefore, instead of the wet type dust remover 4 shown in FIG. 1, it may be possible to use a dry type dust remover such as a dry type EP or a bag filter. However, such a dry dust remover is generally not suitable for high temperatures, and cannot withstand the high temperature (gas temperature rises to 500° C. to 700° C.) during the blow-through of the blast furnace 1. Another dry dust removal method uses granular solids such as sand as a filter layer, but there are considerable technical problems in filtering fine and sticky dust such as blast furnace dust.

Therefore, the present invention provides a blast furnace top pressure power recovery system that can solve the above problems while using a dry type dust remover such as a dry type 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
9 is a generator, 9 is a gas turbine 10 is an inlet shutoff valve,
Reference numeral 11 indicates a turbine governor valve, and reference numeral 12 indicates an outlet shutoff valve. In the present invention, instead of a conventional wet dust remover, a dry dust remover such as a dry EP or a bag filter 1 is used.
There are 3. A cooling fluid supply path 15 having a valve 14 is connected to the gas path 2,
Further, an abnormal temperature detection sensor 16 is provided near the gas outlet of the dry dust remover 13. This abnormal temperature detection sensor 16 emits a signal 17 when the B gas discharged from the dry dust remover 13 reaches a set temperature or higher, thereby opening the valve 14.
As shown in FIG. 3, from the cooling fluid injector 18 attached to the tip of the cooling fluid supply path 15,
Then, a cooling fluid 19 such as a cooling liquid or a cooling gas is injected to cool the B gas. The reason why the abnormal temperature detection sensor 16 is provided downstream of the dry dust remover 13 is to prevent the sensor 16 from being covered with dust and causing a time delay in abnormal temperature detection. That is, for example, when the amount of dust upstream of the dry dust remover 13 is 3 to 10 g/Nm ³ , the amount of dust downstream is 10 mg/Nm ³ or less. Further, as shown in FIG. 4, the sensor 16 installed in the piping 20 from the dry dust remover 13 directly
It is exposed to gas so that there is no time delay in temperature detection. Sensor 16 is connected to dry dust remover 13
The time delay (within 2 seconds) caused by the provision after the ``time'' 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.
Furthermore, the temperature rise at the beginning of the blow-through is at most 15°C/second, and the gas temperature only rises by 45°C during a total time delay of about 3 seconds. Now, let's consider a bug filter with a maximum operating temperature of 240℃. If the set temperature is 170℃,
The gas temperature when injecting the cooling fluid 19 is the highest,
[170°C + 45°C = 215°C], which is sufficiently lower than the maximum operating temperature. When the temperature detected by the sensor 16 becomes lower than the set temperature, the signal 17 will no longer be emitted, the valve 14 will close, and the injection of the cooling fluid 19 will be stopped.

As described above, as the cooling fluid 19, a cooling gas using sensible heat and a cooling liquid using latent heat are used. As a cooling gas, B gas does not necessarily become wet. (a) Water vapor of 3 to 6 atg,
(b) Inert gas such as N ₂ and CO ₂ , (c) Reducing gas such as B gas and C gas (coke oven gas), etc. are used. In addition, the cooling liquid must be completely evaporated in the B gas before the B gas reaches the dry dust remover 13 in order to prevent the dust from caking.
Water, (e) light liquid fuel, liquefied gas 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 position of the abnormal temperature detection sensor 16 is such that the temperature measuring part 21 of the sensor 16 is located at the top of the cross section of the pipe through which the highest temperature gas flows since there is a temperature distribution in the pipe 20. is desirable.

According to the present invention described above, the following effects can be expected.

(b) Since both the coarse dust remover and the fine dust remover are dry types and do not use washing water for dust removal, most of the thermal energy of the blast furnace gas generated from the top of the blast furnace is lost during dust removal. The high-temperature gas discharged from the top of the furnace can be directly guided to the turbine without much effort, and the amount of energy recovered by the turbine on the downstream side can be increased.
Moreover, even after dust removal, clean gas (clean means 5.
Contains dust of about mg/Nm ³ . ) 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 (machines) are dry types, dust can be transported out as is, eliminating the need for large and expensive thickeners and water treatment equipment required for wet types, which generate large amounts of sewage.

(c) When the gas temperature becomes abnormally high due to blast furnace atrium, etc., the initial temperature sensor detects the abnormally high temperature and supplies cooling fluid to the gas path to cool the high-temperature gas. The temperature will drop after that,
It is possible to prevent adverse effects on the dry dust remover.

In addition, by injecting the cooling fluid into the gas passage between the blast furnace and the coarse dust remover, it is possible to uniformly mix the exhaust gas and the cooling fluid until the dry dust remover is reached, and when the cooling fluid is liquid, In addition to ensuring time for its complete evaporation, it is also possible to separate dust that has become coarse due to adhesion of moisture, especially with a coarse dust remover, and can also separate high-temperature exhaust gas due to temperature unevenness. baby boomers,
It is possible to prevent the adverse effects of caking dust on the dry dust remover.

(iv) 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, so the temperature measurement part can be directly exposed to the blast furnace gas without a protection tube, and therefore detection delays are reduced. Less accurate. In addition, as mentioned above, since the blast furnace gas is dry, even the slightest fine dust in the gas does not adhere to the temperature measuring part, so abnormal temperature detection can be performed accurately (quickly) without time delay. be able to.

[Brief explanation of the drawing]

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 an enlarged view of the injector installation part, 5 and 5 are enlarged views of the sensor arrangement portion, respectively. 1... Blast furnace, 2... Gas path, 3... Coarse dust remover, 5... Septum valve, 7... Power generation equipment, 9... Gas turbine, 13... Dry type dust remover, 15... Cooling fluid supply path, 16... Abnormal temperature detection 18...Cooling fluid injector, 19...Cooling fluid.

Claims (1)

[Claims] 1. In a system in which gas discharged from a blast furnace is guided to a coarse dust remover and 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 cooling fluid supply path is connected to the gas path between the blast furnace and the coarse dust remover in the gas path leading to the dry type dust remover, and a protective tube is provided in the temperature measuring part near the gas outlet of the dry type dust remover. A sensor for detecting abnormal temperature is provided, and when the sensor detects abnormal temperature detects a temperature higher than a set temperature, cooling fluid is supplied from the cooling fluid supply path to the gas path, and when the temperature falls below the set temperature, cooling fluid is supplied. A blast furnace top pressure power recovery system using a dry dust remover, which is characterized by controlling the exhaust gas temperature in the event of abnormality in the blast furnace by shutting down the blast furnace.