JP2868432B2 - Hazardous gas treatment method and treatment equipment in blast furnace slag granulation system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and equipment for treating harmful gases in a blast furnace slag granulation system, and more particularly to a quenching reaction when slag discharged from a blast furnace is cooled and granulated. without releasing the generated H ₂ S gas and SO ₂ gas out of the system by, by circulating the exhaust gas during the granulated processed in the system of closed circuit including the blast furnace, H ₂ S gas and SO ₂ gas The present invention relates to a gas treatment method capable of realizing a detoxification process and a facility realizing the same.

[0002]

2. Description of the Related Art In a smelter, impurities contained in iron ore are removed by auxiliary raw materials when refining pig iron, and are discharged as slag from the blast furnace. The slag is usually granulated,
Separately supplied to cement raw materials or disposed of. on the other hand,
The blast furnace gas generated from the blast furnace contains a large amount of CO, and is used as a fuel or the like for generating hot air blown into the blast furnace, and is also used as a heat source of a boiler or the like. A large amount of cooling water is required to granulate the above-mentioned slag, but the slag-cooled wastewater whose temperature has increased after cooling the slag is collected, and the temperature is lowered in a collection hot water cooling tower. And used again for granulation. As described above, the gas discharged from the blast furnace and the slag granulated water are prevented from escaping out of the system as much as possible by performing the respective treatments.

However, in the granulation of the slag, cold water supplied through a spray box is injected into the slag flowing out of the discharge gutter to cool the slag, and a large amount of water vapor is generated when the slag is granulated in the slag tank. Occur. Although cold water when rapidly cooling the溶滓is H ₂ or O ₂ undergoes thermal decomposition occurs, reacts with sulfur to the H ₂ and O ₂ are contained in溶滓, 600Pp
It is assumed that m to 800 ppm of H ₂ S gas and about 100 ppm of SO ₂ gas are generated. This H ₂
Although S gas and SO ₂ gas are harmful gases, they are usually released into the atmosphere from a smoke stack covering a granulation gutter or a granulation tank together with exhaust gas containing a large amount of water vapor.

[0004]

From the viewpoint of preventing air pollution, the emission amount of H ₂ S gas and SO ₂ gas is required to be a certain regulation value, for example, (H ₂ S + SO ₂ ) <250 ppm. Needless to say, it is desirable to be sufficiently lower or close to nothing. For these reasons, studies have been made to render the above H ₂ S gas and SO ₂ gas harmless by a water treatment technique.

The main processing methods are H ₂ S gas and SO ₂
This is a method of chemically neutralizing exhaust gas containing gas. That is, the exhaust gas is washed with caustic soda and made harmless by generating chemically stable Na ₂ SO _{4 and the} like. However, when such a neutralization treatment is performed,
Not only is the equipment for this expensive, but also the disposal of a large amount of waste liquid generated is a major issue. That is, since the neutralized wastewater cannot be reused, introduction of wastewater treatment equipment is indispensable, and disposal of the wastewater increases the amount of industrial water required in the granulation system.

The present invention has been made in view of the above problems, and an object of the present invention is to discharge harmful gases such as H ₂ S gas and SO ₂ gas generated when blast furnace slag is rapidly cooled and granulated. That the equipment required to treat harmful gases can be prevented from becoming large-scale and complicated,
Effective use of industrial water required for granulation is achieved,
In other words, it is an object of the present invention to provide a method and a facility for treating harmful gases in a blast furnace slag granulation system that can minimize the amount of new water that must be replenished.

[0007]

SUMMARY OF THE INVENTION According to the present invention, when slag discharged from a blast furnace is given cold water and granulated, the slag and cold water are rapidly cooled from a large amount of exhaust gas generated by the granulation. H ₂ S gas and SO generated and mixed when reacting
₂ Applies to the method of removing gas. The feature of this is that, with reference to FIG. 1, cooling water 21W and 22W are sprayed and cooled on the exhaust gas 6 containing H ₂ S gas and SO ₂ gas to lower the temperature of the exhaust gas 6G and to reduce the temperature of the exhaust gas. steam to condense in its condensed water was separated and the exhaust gas 6G saturated, followed by removal of the fine water droplets suspended in the exhaust gas 6G and gas body 6G ₃ of saturated steam, the gas body 6G ₃ Is returned to the blast furnace 1 and contained H ₂ S
That is, gas and SO ₂ gas are converted into slag by a desulfurization reaction in the blast furnace 1.

When cooling water is sprayed on the exhaust gas containing H ₂ S gas or SO ₂ gas to cool the exhaust gas 6 G, primary cooling water 21 W having a high temperature is sprayed on the exhaust gas 6 G, and then the primary cooling is performed. by been newly water 20 of the exhaust gas 6G ₁ as lower secondary cooling water 22W temperature is to secondary cooling.

[0009] Primary cooling exhaust gas 6 derived after primary cooling
With the temperature in G ₁ so as not higher than 10 ° C. relative to the temperature at the time of supply of the primary cooling water 21W, new water temperature of the secondary cooling gas 6G ₂ derived after the secondary cooling 20
Is not to be higher than 10 ° C. with respect to the water temperature at the time of supply.

In the primary cooling, 21 W of primary cooling water of 35 ° C. to 45 ° C. is supplied to the exhaust gas which has become about 90 ° C. after being generated in the granulation process, and the temperature of the primary cooled exhaust gas 6G ₁ is 45 ° C. or less. The water amount of the primary cooling water 21W was adjusted to 55 ° C.
° C. to supplies 55 ° C. of the primary cooling gas 6G ₁ to 25 ° C. to 30 ° C. new water 20, secondary to the cooled temperature of the exhaust gas 6G ₂ is not 30 ° C. so that the 35 ° C. secondary cooling water 22W Is to adjust the amount of water.

Referring to FIG. 1, an exhaust gas inlet 21a for introducing an exhaust gas 6G containing H ₂ S gas and SO ₂ gas and a primary cooling water 21W are featured in the invention of the harmful gas treatment equipment. Cooling water supply port 21b for supplying
And an exhaust gas outlet port 21c to derive the primary cooling gas 6G ₁ is provided, the primary cooling water 21W to condense water vapor in the exhaust gas with reducing the temperature of the exhaust gas by contacting directly with the flue gas 6G, and the condensed water The primary cooling tower 21 which removes is installed. New upper to supply new water 20 as a secondary cooling water 22W lower temperature than the primary coolant 21W with exhaust gas inlet 22a is provided in the lower part for introducing the primary cooling gas 6G ₁ that is primary cooling A water supply port 22b is provided, and the secondary cooling exhaust gas 6G ₂ is provided above the new water supply port 22b.
Exhaust gas outlet 22c for discharging the secondary cooling water 2
The temperature of the exhaust gas is reduced by bringing the exhaust gas into countercurrent contact with the exhaust gas while flowing down 2W, and the primary cooling exhaust gas 6G
_A secondary cooling tower 22 is provided to condense the water vapor in ₁ and remove the condensed water to make the exhaust gas saturated. To capture fine water droplets suspended in the secondary cooling gas 6G ₂ containing the secondary cooling tower 22 H ₂ S gas and SO ₂ gas exiting from the wet electrostatic precipitator 7B to gas of the saturated vapor provided it is, is that the wet electrostatic precipitator 7B gas body 6G ₃ exiting the furnace 1 is attracted blower 26 for feeding back to the (see Figure 4) are provided.

Referring to FIG. 4, after the slag 3 is granulated, the temperature of the granulated wastewater 28v and the primary cooling tower 21 increased.
The recovered hot water cooling device 8 (see FIG. 3) for collecting and cooling the primary cooling wastewater 21v composed of the condensed water in which the water vapor in the exhaust gas 6G is condensed and the primary cooling water 21W and the cooling water discharged from the recovered hot water cooling device 8 Part of the cold water 4 was replaced with primary cooling water 21W.
Pump 31 (FIG. 3)
) Is provided.

Referring to FIG. 1, circulating water supply pipe for supplying cold water 4A from recovered hot water cooling device 8 (see FIG. 3) to water supply device 34 for supplying primary cooling water 21W to primary cooling tower 21. 33 and a new water supply pipe 35 for supplying the new water 20 is connected.

[0014]

According to the harmful gas treatment method of the present invention, the H ₂ S gas or SO ₂ gas generated when the slag is granulated is returned to the blast furnace without being discharged to the outside of the blast furnace without slag formation. can do. Therefore, air pollution can be prevented as much as possible without dispersing the harmful gas into the atmosphere. Further, the granulated exhaust gas accompanied by H ₂ S gas and SO ₂ gas is cooled to almost the same temperature and water content as the outside air, and does not cause any trouble even when returned to the blast furnace. Not only that, the water that has cooled the exhaust gas is not discharged out of the system, and the installation of a water treatment device with high equipment costs can be avoided. In addition, the consumption of industrial water used for the granulation and the gas treatment is suppressed as much as possible.

Exhaust gas containing H ₂ S gas and SO ₂ gas has a temperature of about 90 ° C. This is primarily cooled with high-temperature primary cooling water, and then secondary-cooled with low-temperature new water. A suitable gas temperature for collecting fine water droplets in the final treatment stage can be obtained.

In each cooling step of the exhaust gas, if the difference between the temperature of the exhaust gas and the temperature of the supplied cooling water is set not to be higher than 10 ° C., evaporation from the cooling water is suppressed, and dissipation of the cooling water is suppressed. It is possible to save energy, reduce the operation of removing water droplets floating in the exhaust gas, and make the gas returned to the blast furnace almost the same as the atmosphere.

The primary cooling water of 35 ° C. to 45 ° C. is supplied to the exhaust gas of about 90 ° C. so that the temperature of the primary cooling exhaust gas becomes 45 ° C. to 55 ° C. , The temperature of the secondary cooling exhaust gas can be set to 30 ° C. to 35 ° C. Therefore, the dust collection effect of the wet electric dust collector is exhibited to a high degree, and a gas body in a state close to the outside air is generated. Thus, it is possible to prevent the H ₂ S gas or the SO ₂ gas from reacting with the subsequently liquefied water vapor to generate a corrosive substance.

If the harmful gas treatment equipment is provided with a primary cooling tower and a secondary cooling tower as a gas treatment device, a wet-type electrostatic precipitator, and an induction blower, the cooling of the exhaust gas generated by the water granulation treatment and the inclusion in the exhaust gas are included. H ₂ S gas or S
O ₂ to prevent release to the outside the system of toxic gases such as gas, H ₂
By returning S gas or SO ₂ gas to the blast furnace, slag formation by the desulfurizing material is achieved. At that time, direct contact between the exhaust gas in the primary cooling tower and the cooling water, heat exchange by countercurrent contact between the exhaust gas and the cooling water in the secondary cooling tower are promoted, and it is possible to reuse the cooling wastewater. Become. Exhaust gas that produces as little steam as possible from the cooling water can be extracted as a gaseous saturated steam in a wet electric precipitator, and the gaseous body can be reused in a blast furnace.

The primary cooling wastewater composed of the condensed water obtained by condensing the water vapor in the exhaust gas and the primary cooling water in the water granulation treatment wastewater and the primary cooling tower and the primary cooling water is cooled by the recovery hot water cooling device, and the primary cooling tower is used as the primary cooling water by the circulation pump. If supplied to the system, the wastewater can be reused as cooling water, and the amount of new water supplied into the system can be suppressed.

If a circulating water supply pipe and a new water supply pipe are connected to a water supply device for supplying the primary cooling water to the primary cooling tower, the primary cooling water is kept at a desired temperature range of 35 ° C. to 45 ° C. Thus, it becomes possible to prepare cooling water suitable for cooling the exhaust gas of about 90 ° C. to be introduced.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for treating harmful gases in a blast furnace slag granulation system according to the present invention will be described below in detail with reference to the drawings showing processing equipment for realizing the method. FIG.
Is a pig iron making apparatus 2 including a smelting furnace 1 for refining pig iron, a smelter 3 discharged from the smelting furnace 1, spraying cold water 4 on the slag 3, and quenching the slag 3 to granulate the slag 3.溶滓3 and H ₂ produced by quenching the reaction with cold water 4 at the time of
A gas treatment device 7 for removing most of a large amount of water vapor generated by water granulation from an exhaust gas 6 containing S gas and SO ₂ gas, and cooling of hot water after water granulation and waste water after gas cooling. It is the block diagram which showed arrangement | positioning of each apparatus of the collection | recovery hot-water cooling device 8 which can be used again.

As shown in FIG. 2, the water granulation treatment apparatus 5 includes a slag from the blast furnace 1 at 1,500 ° C. to 1,550 ° C.
The molten slag 3 is guided to a water granulation gutter 9A and granulated by cold water 4 sprayed from a spray box 9B, which is rapidly cooled in a water granulation tank 10 to form vitreous fine granular slag. Is a well-known thing. In the granulation gutter 9A and the granulation tank 10, the sensible heat of the slag 3
A large amount of steam is generated from the injected cold water 4 and water 11 in the tank.

At this time, the cold water 4 is thermally decomposed by the high-temperature slag 3 to generate H ₂ and O ₂ . This H ₂ and O
₂ reacts with the sulfur contained in the slag 3 and produces 600 pp
H ₂ S gas of m to 800 ppm and SO ₂ gas of about 100 ppm are generated. Therefore, from the granulation apparatus 5, the harmful gas such as H ₂ S gas and SO ₂ gas and a large amount of water vapor are mixed in the outside air 12 to be sucked at about 93 ° C.
Is generated as white smoke, and is led out of the smoke stack 13. The granulated slag 14 moves to the storage tank 15 with the water overflowing from the granulated tank 10, is collected by the screw conveyor 16, and is carried out to the slag storage bin 18 by the belt conveyor 17. I have.

When the slag 3 is discharged from the blast furnace 1 at a rate of, for example, 6 tons / minute, it is said that the amount of the cold water 4 required for water granulation is 48 times / 48 tons / minute. on the other hand,
In this case, the amount of evaporating water is 150 kg per ton of slag based on the conventional results, and 150 × 6 = 900 kg / min =
The evaporation amount is 1,120 Nm ³ / min. Further, the amount of the outside air 12 sucked along with the evaporation is 336 Nm ³ / min, which is about 30% of the evaporation amount, and the exhaust gas 6 of 1,456 Nm ³ / min is eventually discharged. The above-mentioned supply water of 48 tons / min is the cold water 4 or the like collected and cooled from the granulation treatment device 5 or the gas treatment device 7, and is supplied from the collected hot water cooling device 8 shown in FIG. It has become.

On the other hand, the gas treatment device 7 is provided with H ₂ S gas or S
The cooling water is sprayed and cooled on the exhaust gas 6 containing O ₂ gas to lower the temperature of the exhaust gas 6 and condense the water vapor in the exhaust gas. The condensed water is separated from the exhaust gas to make the exhaust gas saturated. Thereafter, fine water droplets floating in the exhaust gas are removed to obtain a saturated vapor gas corresponding to the gas temperature. It comprises a gas cooling device 7A and a wet electric precipitator 7B.

The gas cooling device 7A comprises a primary cooling tower 21 and a secondary cooling tower 22, as shown in FIG.
Exhaust gas 6G containing H ₂ S gas and SO ₂ gas is introduced into the primary cooling tower 21, and the exhaust gas 6 G is slightly condensed with white smoke while the exhaust gas 6 at 93 ° C. passes through the smoke stack 13. The temperature is lowered and is almost saturated at about 90 ° C. Since the condensed water accounts for more than 30% of the evaporation amount, the water vapor contained in the exhaust gas 6 is 756 Nm ³ / min.
The amount of exhaust gas 6G entering the tank is 756 Nm ³ / min +
The suction outside air amount is 336 Nm ³ / min = 1,092 Nm ³ / min. The exhaust gas 6G contains 600 pp of H ₂ S.
m and SO ₂ are contained in an amount of about 100 ppm.

An exhaust gas inlet 21a is provided at a lower portion of the primary cooling tower 21 for introducing the exhaust gas 6G, and a cooling water supply port 21b is opened at an upper portion for supplying the primary cooling water 21W. And the cooling water supply port 2
And a gas outlet 21c for leading out the primary cooling gas 6G ₁ from above the 1b. This primary cooling tower 21
Is a partition shelf 2 which is arranged up and down and the directions of the ends are alternated
By bringing the exhaust gas 6G, which rises while the primary cooling water 10 flows down 1d and 21d, into countercurrent contact, the temperature of the exhaust gas is lowered and the water vapor in the exhaust gas 6G is condensed.
In addition, the condensed water is removed.

The primary cooling water 21W is supplied to the primary cooling tower 2
The water stored in the chilled water tank 23 installed beside the pump 1 is pumped up by the primary cooling water pump 23p, and is 35 ° C. to 45 ° C. water supplied as described later.
In the primary cooling tower 21, the primary cooling exhaust gas 6G
1 the temperature of ₁ with respect to the water temperature at the time of supply of the primary cooling water 21W
Care is taken not to exceed 0 ° C.

This is because the exhaust gas 6G of about 90 ° C. introduced from the exhaust gas inlet 21a is cooled in countercurrent contact with the primary cooling water 21W flowing down the partition 21d. The primary cooling water 21W due to the sensible heat of the exhaust gas 6G.
Is to suppress as much as possible the evaporation of a part of. Thereby, it is possible to make it as much as possible the consumption of the primary cooling water 21W less, little by adding water vapor to the primary cooling gas 6G ₁ derived from the primary cooling tower 21.

[0030] Therefore, the primary cooling water 21W of water so that the temperature of the primary cooling gas 6G ₁ is to not 45 ° C. 55 ° C. is determined. For example, 21C of primary cooling water at 45 ° C.
When supplied at tons / minute, the cooling water reaches about 88 ° C. when it reaches the lower part of the primary cooling tower 21, and the primary cooling exhaust gas 6
The temperature of G ₁ is 55 ° C. And the exhaust gas inlet 21
Primary cooling water 2 flowing down with exhaust gas 6G even in the vicinity of a
The temperature difference of 1 W is much smaller than 10 ° C.
The evaporation of the primary cooling water 21W in the primary cooling tower 21 is suppressed.

[0031] Thus, the temperature of the primary cooling gas 6G ₁ derived from the primary cooling tower 21 in advance so as not higher than 10 ° C. relative to the temperature at the time of supply of the primary cooling water 21W, described next two When cooling is performed in the same manner also in the secondary cooling tower 22, it is possible to introduce exhaust gas with little floating water droplets at normal temperature or a temperature close thereto, for example, 30 ° C. to 35 ° C., into the wet type electrostatic precipitator 7B. The dust collection effect can be maintained at a high level.

The secondary cooling tower 22 supplies the secondary cooling water 22W of 25 ° C. to 30 ° C. to the primary cooling exhaust gas 6G ₁ of 45 ° C. to 55 ° C., and the temperature of the secondary cooled exhaust gas 6G ₂ is as described above. It is cooled to a temperature of 30 ° C. to 35 ° C. as described above. This exhaust gas inlet 22a of the primary cooling gas 6G ₁ is introduced into the lower, primary cooling water 21
New water 2 as secondary cooling water 22W lower in temperature than W
The middle portion of the new water supply port 22b which 0 is supplied, and the secondary cooling gas outlet 2 the exhaust gas 6G ₂ is derived
2c is provided on the upper part.

[0033] In this secondary cooling tower 22, the primary cooling gas with the primary cooling gas 6G ₁ and is countercurrent contact between to flow down the secondary cooling water 22W, thereby lowering the temperature exhaust gas 6
To condense water vapor in the G _1, and, removing the condensed water. In addition, the secondary cooling gas 6G _2, functions to maintain a substantially saturated condition. The reason why the new water 20 is used as the secondary cooling water 22W is that a low-temperature secondary cooling water is required, and that, as will be described later, water that has been taken out of the system and disappeared is supplied. It is also intended.

Although the secondary cooling tower 22 also employs a cooling system by countercurrent contact, its internal structure is different from that of the primary cooling tower 21. A known eliminator 24A is installed above the exhaust gas inlet 22a, and a refrigerant chamber 25 filled with a large number of plastic fillers 25a as a gas cooling medium is formed at a position separated from the eliminator 24A by a certain space, creating a vapor-liquid equilibrium by the plastic filler 25a, increasing the degree of contact between the secondary cooling water 22W and primary cooling gas 6G ₁ from the new water supply port 22b, so that improvement in heat exchange efficiency is achieved I have.

The new water supply port 22b in the middle stage is a spray device, and the secondary cooling water 22W is sprayed on the refrigerant chamber 25. An eliminator 24B is disposed above the eliminator 24B. Wherein the eliminator 24A is intended to capture water droplets and hairy scum floating on the primary cooling gas 6G _1, it is obtained by forming a maze bending and rustproof steel. The eliminator 24B may have the same structure,
Traps water droplets floating in the exhaust gas cooled by the cooling.
Therefore, 30 ° C. derived from the exhaust gas discharge port 22c
To the only leaving a very fine water droplets in the secondary cooling gas 6G ₂ of 35 ° C..

Also in the secondary cooling tower 22, care is taken so that the temperature of the secondary cooling exhaust gas 6G ₂ that is led out does not become higher than 10 ° C. with respect to the water temperature when the secondary cooling water 22W is supplied. This is the primary cooling gas 6G ₁ to about 55 ° C., introduced from the exhaust gas inlet 22a is cooled while contacting new water 20 and countercurrent gas outlet of the secondary cooling tower 22 2
This is because the secondary cooling water 22 </ b> W is prevented from evaporating due to the sensible heat of the exhaust gas as much as possible when the temperature rises to near 2c. Thus, so as not to adding little water vapor in the secondary cooling gas 6G ₂ derived from the secondary cooling tower 22, also dissipate prevention of secondary cooling water 22W are also considerations.

Therefore, the amount of the secondary cooling water 22W is adjusted such that the temperature of the secondary cooling exhaust gas 6G ₂ is 30 ° C. to 35 ° C. For example, when new water 20 at 30 ° C. is supplied at 1 ton / min, the new water reaches about 53 ° C. when it reaches the lower part of the secondary cooling tower 22, and the secondary cooling exhaust gas 6G ₂
Is 33 ° C., for example. And exhaust gas inlet 2
Temperature difference of the secondary coolant 22W flowing down the exhaust gas 6G ₁ also in the vicinity of 2a is within 10 ° C., the secondary cooling tower 22
Inside, the evaporation of the new water 20 is suppressed.

The above-mentioned wet type electrostatic precipitator 7B collects fine water droplets floating in the secondary cooling exhaust gas 6G ₂ containing H ₂ S gas and SO ₂ gas derived from the secondary cooling tower 22. This is a known structure having a discharge electrode connected to a negative electrode of a high-voltage DC power supply and a dust collecting electrode connected to a positive electrode, as opposed to the discharge electrode. This is to generate positive and negative ions near the discharge electrode by corona discharge, negatively charge water droplets existing on the way that negative ions move in the electric field to the collection electrode, and attract it to the collection electrode Water droplets are trapped, and the exhaust gas is made into a gaseous state with no suspended matter in a saturated state.

As described above, the temperature of the secondary cooling exhaust gas 6G ₂ derived from the secondary cooling tower 22 is
The supply temperature of W is not made higher than 10 ° C. This is because when the difference between the temperature of the secondary cooling temperature of the exhaust gas 6G ₂ and the secondary cooling water 22W is greater than 10 ° C., since the amount of water droplets which are brought into a wet electrostatic precipitator 7B increases the secondary cooling gas 6G ₂ It is. That is, the discharge electrode and the dust collection electrode are short-circuited by a large amount of water droplets, resulting in insufficient charging of the water droplets, which hinders the collection of the water droplets. Although the secondary cooling tower 22 and the wet-type electrostatic precipitator 7B are illustrated independently in the figure, the wet-type electric precipitator 7B
Is disposed above the secondary cooling tower 22, the gas processing device 7
The area occupied by the device can be reduced.

The main body of the wet type electrostatic precipitator 7B is supplied with a cleaning liquid for cleaning the electrode surface to which water droplets have adhered. Therefore, a spray device 7m is provided above the electrode, and the secondary cooling water 22W supplied to the secondary cooling tower 22 is provided.
A small amount of new water 20w is supplied as needed.
An induction blower 26 for extracting exhaust gas is provided in such a wet electric dust collector 7B, and a duct is connected to a gas outlet 7n at an upper portion of the dust collector main body.

The induction blower 26 is provided with a wet electric precipitator 7.
The body of gas 6G ₃ derived from B with is fed back to the ironmaking apparatus 2, the granulated processing apparatus primary cooling tower 21 to the exhaust gas 6 discharged above from 5, the secondary cooling tower 22 and the wet electrostatic precipitator 7B in It works to attract sequentially. As will be described in detail later, the gas body 6G ₃ sent out by the induction blower 26 is supplied to the blast furnace 1, and H ₂ S gas and SO ₂ gas contained in the gas body 6G ₃ are charged for iron making. It reacts with desulfurizing materials such as lime to prevent the release of harmful gases to the atmosphere by slagging. In addition, the induction blower 2
The amount of the gas 6G ₃ exhausted by the exhaust gas 6 substantially corresponds to 336 Nm ³ / min sucked in the smoke stack 13.

As described above, in order to cool the exhaust gas 6, new water 20 as the primary cooling water 21W and the secondary cooling water 22W are required. Not only that, a large amount of cold water 4 is consumed in the granulation apparatus 5 as well. On the other hand, in the gas processing device 7, condensed water and cooling water accumulate in each of the cooling towers 21 and 22. In the water granulation apparatus 5 as well, waste water of the granulated water whose temperature has been raised is generated. Therefore, the water generated or used in the system is recovered, and can be reused after cooling for the purpose of saving industrial water.

For this purpose, a recovered hot water cooling device 8 as shown in FIG. 3 is installed. First, in the granulating apparatus 5, as shown in FIG. 2, most of the slag particles 14 are removed in the storage tank 15, and the wastewater overflows and is transferred to the filtration tank 27. For example, a rotary drum type filter device 28 is installed in the filtration tank 27, and fine slag is collected. The slag accumulated at the bottom of the filtration tank 27 is mud-like, and is returned to the granulation tank 10 by a slurry pump. The filtrate 28v filtered by the filter device 28 is granulated wastewater, 29. Water also adheres to the slag 14 carried out by the belt conveyor 17, and water accumulates in the slag storage bin 18. The exuded water 18 v is also introduced into the hot water tank 29.

On the other hand, the primary cooling wastewater 21v accumulated in the primary cooling tower 21 shown in FIG. 1 is a primary cooling water 21W of 88 ° C. after cooling the high-temperature exhaust gas 6G and condensed water generated by cooling. Is also returned to the hot water tank 29. The secondary cooling wastewater 22v accumulated in the secondary cooling tower 22 and a small amount of dust collector cleaning water 7v are supplied to the primary cooling tower 21 by the primary cooling water 2v.
It is put into a cold water tank 23 supplying 1 W. Therefore,
As described above, if the secondary cooling tower 22 is disposed so as to overlap the wet electric dust collector 7B, the secondary cooling waste water 22v and the dust collector cleaning water 7v are mixed, but this does not cause any adverse effect.

The hot water 29v stored in the hot water tank 29 is sent to the recovered hot water cooling device 8 in FIG. The cooling device 8 includes a main recovered water cooling tower 8A, a thickener 8B, and a sub-recovered water cooling tower 8C. The main recovered water cooling tower 8A is a known air cooling device, and is supplied with all of the hot water 29v. In this tower, outside air is circulated by a fan, and the hot water 29v is cooled by latent heat of evaporation. The cooled water has a temperature of 50 ° C to 60 ° C.

Although this water has a relatively high temperature, it has a water temperature sufficient to granulate the slag 3. As shown in FIG. 2, the water is supplied from the cold water tank 8a to the spray box 9B by the circulation pump 31. . As described above, the amount can be up to 48 tons / minute. The remaining cold water 4A is introduced into the thickener 8B of FIG. 3, and the small residual slag and the like that have come out of the filter device 28 and the slag storage bin 18 are removed. This is a known device in which a coagulant is introduced to promote the sedimentation of suspended matter, and the sediment is discharged by a distributor 8d or a rake 8e attached to the center shaft 8s.

The cold water 4A purified by the thickener 8B overflows, is introduced into the sub-recovery water cooling tower 8C, and is cooled in the same manner as the main recovery water cooling tower 8A. This cold water 4A
Has been cooled to 35 ° C. to 40 ° C., and is sent out from the cold water tank 8c by the delivery pump 32, and the cold water tank 23 in FIG.
To the primary cooling tower 21
Used as the primary cooling water 21W. When the sub-recovery water cooling tower 8C is provided at a position higher than the cold water tank 23, the delivery pump 32 is not necessary.

The chilled water tank 23 returns the chilled water 4A, the above-mentioned secondary cooling waste water 22v and the dust collector cleaning water 7v to reuse industrial water. However, that water vapor returned to the blast furnace 1 by saturated gas body 6G ₃ of water vapor generated during the granulated processing, also from the reservoir 15 and filter tank 27 there is some evaporation, slag storage bottle 18 Since there is water taken out of the slag that is discharged from the truck and transported by truck, and water is evaporated in the recovered hot / cold water system 8, the subsequent in-system processing becomes impossible with the amount of water existing in the system. Therefore, the above-mentioned new water 20
Is replenished.

The new water 20 is newly introduced industrial water, which is usually about 30 ° C., and has a lower temperature than the water circulating in the system. Therefore, when introducing the new water 20 into the system, it is preferable to supply it to a place where the lowest temperature is required, and supply the new water to the secondary cooling tower 22 and the wet-type electrostatic precipitator 7B as described above. Is done. On the other hand, the amount of the new water 20 required in the secondary cooling tower 22 is about 1 ton / min as described above, and the amount of water for washing the wet electric dust collector 7B is also small. Therefore, this amount of fresh water is not sufficient for replenishment in the system, and therefore, the water supply device 34 for supplying the primary cooling water 21W so that the total amount of new water supplied is equal to the amount dissipated outside the system. A new water supply pipe 35 faces the cold water tank 23, and a part of the new water is used as the primary cooling water 21W.

As described above, when the new water is also supplied to the cold water tank 23, it is possible not only to secure 8 tons / minute as the amount of the primary cooling water 21W, but also to recover about 5 tons returned from the secondary cooling tower 22.
It can also contribute to lowering the temperature of the secondary cooling wastewater 22v at 3 ° C or the cold water 4A at 35 ° C to 40 ° C. The moisture taken out from the wet electric precipitator 7B to the blast furnace 1 is 30 ° C.
A saturated vapor contained in the exhaust gas 6G _3, the amount is, for example, 0.0272kg water / kg dry air × 336 nm ³
/Min×1.29 kg / Nm ³ = 12 kg / min.

By the way, the amount of steam escaping in the recovered hot water cooling device 8 is about 3,400 kg / min, and the amount of water carried out by truck from the slag storage bin 18 is about 1,400 kg / min.
000 kg / min. On the other hand, the pump sealing water supplied to each of the circulation pump 31 of the main recovered water cooling tower 8A and the delivery pump 32 of the hot water tank 29 is new water, but the amount is at most 500 kg / min. As a result, the amount of the new water 20 supplied to the secondary cooling tower 22 and the wet type electrostatic precipitator 7B is 3,
400 + 1,000 = 4,400 kg / min, and the total amount of new water 20 is 4,400 + 500 = 4,900 kg
/ Minute ≒ about 5 tons / minute. The amount of the new water 20 always balances the water in the system, and the amount discharged as wastewater out of the system is eliminated. Therefore, a water treatment facility for wastewater that goes out of the system is not required.

By the way, even in the conventional cold water circulating equipment having only the water granulation treatment device 5 without the above-mentioned gas treatment device 7, replenishment of new water is performed. Since the recovered hot water cooling device 8 has only the above-mentioned main recovered water cooling tower 8A, new water is introduced into the main recovered water cooling tower 8A.
Also in this case, the escape of about 2,800 kg / min during cooling with hot water and the removal of trucks of about 1,000 kg / min
It is necessary to replenish a total of 4,900 kg / min of sealing water of 00 kg / min and further evaporation during the granulation treatment of 600 kg / min, and about 5 tons / min of new water is supplied. From this, it can be seen that even if the gas treatment device 7 according to the present invention is added to the water granulation treatment equipment, the consumption of industrial water hardly increases.

In the harmful gas treatment facility configured as described above, H ₂ generated during the water granulation treatment is as follows.
Without releasing S gas or SO ₂ gas out of the system,
It is not necessary to neutralize the wastewater after being used for the granulation of the slag 3 and the cooling of the exhaust gas 6. First, a slag 3 at a maximum of, for example, 6 tons / min is discharged from a smelter 1 for refining pig iron by adding an auxiliary material such as coke to iron ore. The slag 3 also includes a slag converted from sulfur by a desulfurization reaction in the blast furnace 1.

Slag 3 at 1,500 ° C. to 1,550 ° C.
Is supplied to the water granulation gutter 9A of the water granulation treatment device 5 through the discharge gutter, and is cooled by spraying the cold water 4 sent out by the circulation pump 31 of the recovered hot water cooling device 8 from the spray box 9B.
The slag 3 is immediately introduced into the granulation tank 10 and granulated by granulation with the water 11 in which the cold water 4 is stored. At this time, the granulation tank 9
The cold water 4 and the tank water 11 in A come into contact with the high-temperature slag 3,
Although about 900 kg / min of steam is generated, the exhaust gas 6 at about 93 ° C. is generated together with the mixed air, and is guided from the smoke stack 13 to the primary cooling tower 21.

Some of the water vapor undergoes thermal decomposition to produce H ₂ and O
While generating a _2, H ₂ and O ₂ is combined with sulfur in溶滓3 in quench reaction with溶滓3 and cold water 4, harmful H ₂
S gas and SO ₂ gas are generated. These gases also rise in the smoke stack 13 with the exhaust gas 6. In addition, fine hairy scum is generated and floats at the time of water granulation, and the hairy scum is also accompanied by the exhaust gas 6.

On the other hand, the granulated slag particles are transferred to a storage tank 15 along with overflowing tank water 11, and are taken out while draining on a screw conveyor 16. Further, it is transported by the belt conveyor 17 and stored in the slag storage bin 18. Fine granulated slag remains in the water in the storage tank 15, and is transferred to the filtration tank 27 and separated by, for example, a rotary drum type filter device 28. The filtrate 28 v is charged into the hot water tank 29. The slag accumulates at the bottom of the filtration tank 27 in a mud-like manner, but is returned to the granulation tank 10 together with the high-temperature water in the filtration tank 27.

For example, 600 ppm of H ₂ S gas and 100 ppm of SO ₂ gas mixed in the exhaust gas 6 rising in the smoke stack 13
Although it is on the order of ppm, it is not preferable to emit it to the atmosphere as it is. Therefore, the exhaust gas 6 is led out from the flue gas tube 13 to the gas treatment device 7. Although the exhaust gas 6 is turned into white smoke with a lot of fine water droplets, the white smoke is condensed while rising up the smoke stack 13 and 365 Nm ³ / min = 293 kg /
The condensed water is returned to the granulation tank 10 to be converted into a substantially saturated exhaust gas 6G at about 90 ° C. and introduced into the exhaust gas inlet 21 a of the primary cooling tower 21.

In the primary cooling tower 21, for example, the water is supplied from the cold water tank 23 of the water supply device 34 by the primary cooling pump 23 p to, for example, 45.
The primary cooling water 21 W of 10 ° C. is pumped at 8 tons / minute and supplied from the cooling water supply port 21b. H ₂ S gas or SO ₂
The exhaust gas 6G containing gas is supplied to the partition 21 forming a maze.
d and 21d, while the primary cooling water 21W flows down each partitioning shelf 21d. At this time, the exhaust gas 6G is cooled by a countercurrent contact method, so that the temperature of the exhaust gas 6G decreases and the water vapor in the exhaust gas 6G is condensed.

The primary cooling exhaust gas 6G ₁ discharged from the exhaust gas outlet 21b is still accompanied by H ₂ S gas and SO ₂ gas, but its temperature is about 55 ° C.
It is about 10 ° C. higher than W of 45 ° C. On the other hand, the temperature of the primary cooling water 21W that has exchanged heat with the exhaust gas 6G rises to about 88 ° C. The condensed water flow rate generated during this time is 558 kg / min, but since the temperature difference during heat exchange is small, the primary cooling water 21 W
There is almost no evaporation from the secondary cooling tower 22 in a saturated state at about 55 ° C. In addition, the total amount of the primary cooling water 21W and the condensed water are stored in the liquid pool at the lower part of the primary cooling tower 21, and the temperature is 8,000 kg / min + 55
8kg / min = 8,558kg / min primary cooling wastewater 21v
Is returned to the hot water tank 29 of the granulation apparatus 5.

The primary cooling exhaust gas 6G ₁ is introduced from an exhaust gas inlet 22a of the secondary cooling tower 22, and is supplied from a spray device 22b, which is a new water supply port provided in the middle stage of the secondary cooling tower 22, to a new water 20 ° C. of about 30 ° C. Is sprayed as the secondary cooling water 22W. The secondary cooling water 22W is supplied to the gas refrigerant 25 in the refrigerant chamber 25.
heat exchange is performed by the primary cooling gas 6G ₁ countercurrent contact while passing through the gap a.

First, the introduced primary cooling exhaust gas 6G _{1 at} 55 ° C. comes into contact with the new water 20 flowing down. Water droplets suspended scattered At that time, the primary cooling gas 6G ₁ to accompanied water droplets and hairy dregs are removed while passing through the eliminator 24A. Since they separated in this eliminator 24A hairy scum from the primary cooling gas 6G _1, gas refrigerant member 25a of the coolant chamber 25 nor clogged by hairy slag. The exhaust gas rising to the refrigerant chamber 25 is discharged from the secondary cooling water 22.
The gas is cooled efficiently by touching the gas cooling medium 25a cooled by W. Before the heat-exchanged exhaust gas reaches the exhaust gas outlet 22c, the eliminator 2
4B removes water drops again.

[0062] In the secondary cooling tower 22 is supplied 1 ton / min of the secondary cooling water 22W via a new water supply pipe 35, condensed water is generated with the primary cooling gas 6G ₁ of 55 ° C. is cooled . The secondary cooling exhaust gas 6G ₂ discharged from the exhaust gas outlet 22b is still H ₂ S gas or SO ₂
It remains with gas but its temperature is about 33 ° C,
It is not higher than 10 ° C. for the supply temperature of fresh water 20 of 30 ° C. On the other hand, the temperature of the heat exchanged secondary cooling water 22W rises to about 53 ° C. During this period, the condensate flow rate is 38
Although it is kg / min, there is almost no evaporation from the secondary cooling water 22W because the temperature difference at the time of heat exchange is small, and it is led to the wet type electrostatic precipitator 7B in a saturated state of about 33 ° C.

In the liquid pool below the secondary cooling tower 22, the entire amount of the secondary cooling water 22W and the condensed water are stored. 1,000k
g / min + 38 kg / min = 1,038 kg / min. The secondary cooling wastewater 22v has a lower temperature than the primary cooling wastewater 21v.
Even if the temperature is returned to the cold water tank 23 having a water temperature of 5 ° C. to 45 ° C., the temperature of the primary cooling water 21W is not changed enough, so that it is reused as the primary cooling water 21W. Note that the secondary cooling wastewater 22v may be returned to the hot water tank 29 of the granulation apparatus 5, but if it is returned to the cold water tank 23,
The cooling capacity of the recovered hot water cooling device 8 can be reduced.

The secondary cooling exhaust gas 6G ₂ is introduced into the wet electric dust collector 7B at about 33 ° C. where the dust collecting process is easy. Although the secondary cooling exhaust gas 6G ₂ still contains H ₂ S gas and SO ₂ gas, floating water droplets are considerably small. However, fine water droplets cannot be completely removed in the gas cooling device 7A, and are captured by charging the water droplets in the wet electric precipitator 7A. by this,
Dust collector exhaust gas becomes gas body 6G ₃ of saturated to about 30 ° C. required to maintain the stable operation of the blast furnace 1.

Incidentally, the slag 3 discharged from the blast furnace 1
Varies depending on the amount of refining, and accordingly, the amount of exhaust gas generated during the water granulation treatment also changes. Therefore, the amount of each cooling water supplied to the gas cooling device 7A is also adjusted. However, in any state, the gas cooling device 7A does not always completely remove water droplets from the exhaust gas 6A. However, by passing the wet electrostatic precipitator 7B, even somewhat on the amount of water droplets suspended in the secondary cooling gas 6G _2, always it is possible to obtain a gas body 6G ₃ of saturation.

In the dust collector liquid pool, dust collector cleaning water 7v after cleaning the electrodes with a small amount of new water 20w supplied from the spraying device 7m as needed is stored.
Since this dust collector cleaning water 7v can also be used as the primary cooling water 21W, it is returned to the cold water tank 23.

[0067] From the wet electrostatic precipitator 7B of the body of gas outlet 7n, further by inducing air blower 26 while the gas body 6G ₃ is accompanied by H ₂ S gas and SO ₂ gas in 2 main blowers 37
Is sent to the hot blast stove 36. In addition, the steam generated by the water granulation treatment is 900 kg / min, 293 kg / min is condensed while passing through the smoke stack 13, 558 kg / min in the primary cooling tower 21, 38 kg / min in the secondary cooling tower 22, some amount of wet electrostatic precipitator 7B is recovered as condensed water, eventually, 336 nm ³ / min gas body 6G ₃ would bring about 12 kg / min saturated vapor amount at 30 ° C..

[0068] In this way keep reducing the floating water droplets of gas element 6G ₃ as much as possible, that is, when the amount of water vapor contained in the gas body 6G ₃ keep the saturated vapor amount corresponding to gas temperature , even the body of gas 6G ₃ is fed back to the blast furnace 1 through a hot air oven 36, the humidity in the blast furnace 1 is easily kept constant, enabling stable operation of the blast furnace 1 which is substantially constant burn of the coke Become. Further, it is extremely unlikely that the H ₂ S gas or SO ₂ gas led out together with the gas body 6G ₃ reaches the main blower 37 and reacts with residual water droplets to generate corrosive substances. .

[0069] hot air oven 36 are intended to produce hot gas for combustion supplied to the blast furnace 1, since it requires a large amount of air, comprising a main blower 37 for taking in outside air with the gas body 6G _3. Since its suction port to allow the gas material 6G ₃ containing H ₂ S gas and SO ₂ gas when sucking the outside air can be taken without releasing to the atmosphere, the gas body return port of the suction opening It faces the center of the interior. Incidentally, the gas body 6G _{3 at} 30 ° C. is 336 Nm ³ / min = 372.
m ³ / min, and the main blower 37 has about 5,600
m ³ / min incorporation of outside air, about 6,000 m ³ / min is supplied to the hot air furnace 36.

The blast furnace gas is burned in the hot blast stove 36 to generate a hot gas at about 1,100 ° C.
Tuyere 1 of blast furnace 1 while containing ₂ S gas and SO ₂ gas
It is blown from a. When the gas body 6G ₃ is fed back to the blast furnace 1 forms part of the hot gas, H ₂ S gas and SO ₂ gas is desulfurized by such lime as auxiliary raw materials charged into the blast furnace 1 is slag formation. The slag 3 is subjected to water granulation as described above.

As described above, the H ₂ S gas and SO ₂ gas generated in the granulation process are discharged as slag after circulating in the system together with the exhaust gas 6, so that the H ₂ S gas and SO ₂ gas are removed. It will not be discharged out of the system.
On the other hand, the cold water 4 used for granulation and the cooling water used for gas cooling are also circulated and used again without going out of the system, and only new water that is insufficient is supplied into the system. As a result, harmful gases are processed in a closed circuit,
Also, weak alkaline wastewater generated in various places does not go out of the system, the amount of industrial water used is kept to the minimum necessary, and wastewater treatment equipment is not required.

By the way, the numerical example of the water balance in the above-mentioned system is for the case of refining 8,000 tons of pig iron per day, for example, and it is natural that the amount of water decreases when the amount of pig iron production is small. Actually, for example, three circulating pumps or the like described above are installed in order to balance the water in this case, and the amount of circulating water is adjusted by changing the number of operating units. In that case, the amount of fresh water supplied is also reduced. Regardless of the amount of new water,
Except for water taken out by truck and very little water discharged from the thickener, no water is discharged out of the system in a liquid state.

In the above description, the temperature and the amount of the cooling water are exemplified. However, the respective values in the case of using the primary cooling water of 21 ° C. at 35 ° C. are compared with the values in the case of using the primary cooling water of 45 ° C. in the following table. Shown in

[Table 1] The primary cooling tower 21 and the secondary cooling tower 22 have been described as countercurrent contact type gas cooling devices. Heat exchange between the exhaust gas and the cooling water can be promoted very efficiently if the countercurrent contact type is used. However, in the primary cooling tower 21, another type of cooling device such as a cocurrent contact type can be used. .

[Brief description of the drawings]

FIG. 1 is a configuration system diagram showing a harmful gas processing device according to the present invention.

FIG. 2 is a configuration system diagram showing a water granulation treatment device.

FIG. 3 is a configuration system diagram showing a recovered hot water cooling device.

FIG. 4 is a system block diagram showing an entire blast furnace facility including a harmful gas treatment facility in the blast furnace slag granulation system according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS ₁ ... Blast furnace, 3 ... Slag, 4,4A ... Cold water, 5 ... Granulation processing apparatus, 6,6G ... Exhaust gas, 6G1 ... Primary cooling exhaust gas, 6
G ₂ ... secondary cooling gas, 6G ₃ ... Gas body, 7B ... wet electrostatic precipitator, 8 ... recovery hot water cooler, 20 ... new water, 21
... primary cooling tower, 21a ... exhaust gas inlet, 21b ... cooling water supply port, 21c ... exhaust gas outlet, 21v ... primary cooling wastewater, 21W ... primary cooling water, 22 ... secondary cooling tower, 22a ...
Exhaust gas inlet, 22b: New water supply port, 22c: Exhaust gas outlet, 22W: Secondary cooling water, 26: Induced blower, 28
v: Granulation wastewater, 31: Circulation pump, 33: Circulating water supply pipe, 34: Water supply device, 35: New water supply pipe.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B01D 53/52 B01D 53/34 122Z F27D 17/00 104 126

Claims (7)

(57) [Claims] When slag discharged from a blast furnace is given cold water and subjected to water granulation, a large amount of exhaust gas generated by the water granulation produces and mixes when the slag and cold water undergo a rapid cooling reaction. a method for removing H ₂ S gas and SO ₂ gas, water vapor in the exhaust gas with reducing the temperature of the exhaust gas by cooling by spraying cooling water to the exhaust gas containing H ₂ S gas and SO ₂ gas Is condensed, the condensed water is separated to make the exhaust gas saturated, and then fine water droplets floating in the exhaust gas are removed to obtain a saturated vapor gas body,
Hazardous gas treatment in a blast furnace slag granulation system, wherein the gas body is returned to the blast furnace to contain H ₂ S gas and SO ₂ gas into a slag by a desulfurization reaction in the blast furnace. Method. 2. When cooling water is sprayed on the exhaust gas containing H ₂ S gas or SO ₂ gas to cool the exhaust gas, primary cooling water having a high temperature is sprayed on the exhaust gas to perform primary cooling. The harmful gas treatment method in the blast furnace slag granulation system according to claim 1, wherein the primary-cooled exhaust gas is secondary-cooled by new water having a low temperature as secondary cooling water. 3. The temperature of the primary cooling exhaust gas derived after the primary cooling is set to be 1 to the water temperature at the time of supplying the primary cooling water.
The temperature of the secondary cooling exhaust gas derived after the secondary cooling is set not to be higher than 10 ° C. with respect to the water temperature at the time of the supply of the new water, while not being higher than 0 ° C. Item 6. A method for treating harmful gases in a blast furnace slag granulation system according to Item 2. 4. The method according to claim 1, wherein in the primary cooling, the exhaust gas which is generated in the water granulation process and reaches about 90 ° C. is cooled to 35 ° C. to 4 ° C.
While supplying the primary cooling water at 5 ° C., the amount of the primary cooling water is adjusted so that the temperature of the exhaust gas after the primary cooling becomes 45 ° C. to 55 ° C., and in the secondary cooling, the primary cooling water is cooled to 45 ° C. to 55 ° C. Supplying fresh water of 25 ° C. to 30 ° C. to the primary cooling exhaust gas, and adjusting the amount of secondary cooling water so that the temperature of the secondary cooled exhaust gas is 30 ° C. to 35 ° C. Item 3. A method for treating harmful gases in a blast furnace slag granulation system according to Item 3. 5. When slag discharged from a blast furnace is given cold water and subjected to water granulation, a large amount of exhaust gas generated by the water granulation is produced and mixed when the slag and cold water undergo a rapid cooling reaction. in facilities for removing H ₂ S gas and SO ₂ gas, the exhaust gas introduction port for introducing the flue gas containing H ₂ S gas and SO ₂ gas described above, the cooling water supply port for supplying the primary cooling water An exhaust gas outlet for introducing primary cooling exhaust gas is provided, and the primary cooling water is brought into direct contact with the exhaust gas to lower the temperature of the exhaust gas and condense the water vapor in the exhaust gas, and remove the condensed water. A primary cooling tower, and a new water as a secondary cooling water having a lower temperature than the primary cooling water while an exhaust gas introduction port is provided at a lower portion for introducing the primary-cooled primary cooling exhaust gas. A new water supply port is provided at an upper portion for supplying the exhaust gas, and an exhaust gas outlet for drawing out the secondary cooling exhaust gas upward from the new water supply port is provided, and the exhaust gas counterflows while the secondary cooling water flows down. A secondary cooling tower that lowers the temperature of the exhaust gas by contacting it, condenses water vapor in the primary cooling exhaust gas, removes condensed water, and saturates the exhaust gas, and outputs H from the secondary cooling tower. A wet electric precipitator that captures fine water droplets floating in the secondary cooling exhaust gas containing ₂ S gas and SO ₂ gas and converts it into a gaseous saturated vapor, and a gas discharged from the wet electric precipitator into the blast furnace A harmful gas treatment facility in a blast furnace slag granulation system, comprising: an induction blower for returning. 6. A crushed granulated wastewater having a raised temperature after the slag is granulated, and a primary cooling wastewater composed of condensed water obtained by condensing water vapor in exhaust gas in the primary cooling tower and primary cooling water. And a circulating pump for supplying a part of the chilled water discharged from the recovered hot water cooling device to the primary cooling tower as the primary cooling water. Hazardous gas treatment equipment in the blast furnace slag granulation system described. 7. A water supply device for supplying primary cooling water to the primary cooling tower includes a circulating water supply pipe for supplying cold water from the recovered hot water cooling device and a new water supply pipe for supplying the new water. The harmful gas treatment equipment in the blast furnace slag granulation system according to claim 6, which is connected.