JP4676720B2 - Exhaust gas dust collection method - Google Patents

Description

The present invention relates to an exhaust gas dust collection method for a converter that efficiently collects exhaust gas having a high temperature of 600 ° C. or higher that is generated when the converter molten iron is charged.

  As dust collection of hot gas exhaust gas, for example, as shown in FIG. 1, when hot metal is charged in a converter operation in which hot metal 12 is charged into the converter 1 from the ladle 3, it is contained in the stored scrap 13. A large amount of gas is burned and generated from combustible materials, and dust such as iron oxide is generated in a short time. The gas containing a large amount of dust at this high temperature is collected by the rectangular ventilation dust collection hood 2 located on the furnace of the converter 1 and collected by the ventilation dust collection duct 4 of the converter, and then other parts of the factory. The exhaust gas flowing from the ventilation dust collection duct 5 provided with the damper 6 is diluted, mixed and cooled, collected by the blower 7, removed by the bag filter 8, and discharged. In particular, when hot metal is charged, since the high-temperature exhaust gas 9 flows from the converter, the exhaust gas 9 becomes hotter than usual, and flows through the ventilation dust collection duct 4 at a flow rate of 10 m / sec or more.

  As a general blower characteristic, the suction pressure of the blower decreases as the temperature increases. For this reason, the amount of dust collected in the converter ventilation was reduced during the hot metal charging in which a large amount of dust was released.

Furthermore, since the high-temperature exhaust gas is expanded, it causes pressure loss when flowing through the duct, and the higher the temperature is, the more difficult it is to flow and the dust is collected during the hot metal charging in which a large amount of dust is released. The amount of gas decreased and the exhaust gas that did not enter the hood 2 filled the factory building, leading to environmental degradation.

  In addition, from the viewpoint of protecting the bagfitter, the damper 6 in the duct is adjusted so as to dilute the exhaust gas from the converter with other dust collecting gas having a lower temperature so that it becomes 150 ° C. or less even when the hot metal is charged. The exhaust gas from the converter must be suppressed to collect dust.

  In response to this problem, the duct is made into a double pipe to selectively suck only the high-temperature exhaust gas being charged in the hot metal, and if the exhaust gas is too hot, water is injected into the exhaust gas from the cooling water spray as necessary. Then, after lowering the exhaust gas temperature, a proposal for collecting dust with a dust collector such as a venturi scrubber has been proposed (see, for example, Patent Document 1).

However, when water is poured into a duct that contains a large amount of iron flowing in high-temperature gas and is susceptible to self-sintering dust, etc., the dust flowing along with the exhaust gas falls with water droplets and falls, causing the bottom surface of the duct to fall. There is a problem that the dust is not collected due to the blockage of the duct due to the fixing with.

Furthermore, as ventilation dust duct of the converter, if the horizontal duct, even if they exhaust gas flows through a 10 m / sec or more flow rates, the dust tends to fall into the duct, the further closure of the duct It had the problem of being easy to do.

  In addition, if water injection is performed in an environment where high-temperature exhaust gas flows at a high speed of 10 m / sec or more only when the hot metal is charged, such as in a converter, and dust is accumulated in the duct, the accumulated dust Heated with exhaust gas flowing through, or conversely, water particles from water injection wet the dust, or the dust in the part where it is repeatedly humidified and dried becomes very hard dust, making it difficult to remove the accumulated dust Industrially, there was a fear that it would be a very big evil.

  Therefore, there has been a demand for a technology for cooling exhaust gas so that dust in the exhaust gas does not accumulate when the exhaust gas is cooled by water injection.

JP 52-155108 A

An object of the present invention is to provide an exhaust gas dust collection method for a converter that cools efficiently in a duct in which high-temperature gas and dust are flowing, and collects dust so that dust does not accumulate in the duct. .

The present invention has been made in order to solve the above-described problems, and the means thereof includes arranging a water spray facility in a duct through which exhaust gas containing dust generated in a converter flows , and the water spray facility. An exhaust gas thermometer is installed on the upstream side, and when the exhaust gas temperature measured by the exhaust gas thermometer is 600 ° C. or higher, the average mist particle size is reduced in the downstream direction in the duct through which the exhaust gas flows from the water spray facility. Is an exhaust gas dust collection method for a converter, wherein dust is collected by discharging water particles of 500 μm or less in an amount of 50 g to 500 g per 1 Nm ³ volume of exhaust gas.

In the present invention, when the exhaust gas from the converter becomes high temperature, water particles having an amount of 50 g to 500 g and an average mist particle size of 500 μm or less per 1 Nm ³ volume of the exhaust gas that is sucked and flows from the upstream. By discharging the gas in the downstream direction, it is possible to collect the exhaust gas after reducing the gas temperature without attaching dust from the exhaust gas to the duct with a simple facility. It is possible to increase the dust collection efficiency.

  The present inventor makes use of the existing equipment and provides a water spray equipment 10 in the duct 4 of the converter installed horizontally as shown in FIG. The effect on dust deposition rate was investigated. In addition, the water spray is arranged in the center of the duct 4 with 6 nozzles 10 m downstream from the rectangular converter hood 2, and the exhaust gas temperature is 30 m downstream from the position of the converter hood 2. Then, a thermocouple was inserted immediately before the blower, and measurement was performed.

FIG. 3 shows the test results of investigating the temperature reduction allowance 30 m downstream from a hood in which water was poured with an average mist particle size of 400 μm when the exhaust gas temperature was 900 ° C. If the amount of water injection is increased from Fig. 3, the temperature reduction allowance 30m downstream from the hood will increase, but if the amount of water injection is 500g / Nm ³ or more, the cooling effect allowance will decrease and the amount of water beyond that It has been found that even if it increases, the effect is saturated and has no industrial significance. On the other hand, when the amount of water injected was 50 g / Nm ³ or less, it was found that the cooling effect was only about 50 ° C., and an industrially sufficient cooling effect could not be obtained. However, at the test level with various conditions changed, dust deposits as shown at 11 in FIG. 2 were found at a position about 20 m downstream from the converter hood 2. Although this phenomenon tends to occur when the amount of water is large, it has been found that the phenomenon is also related to the evaporation process of water after discharging from the nozzle.

  Therefore, if the water discharged from the nozzle is evaporated at high speed and the mist particle size is reduced so as not to wet the dust in the exhaust gas, the dust adhesion phenomenon as described above can be solved, and the nozzle type is changed. The experiment was carried out by changing the mist particle size by four levels. In addition, it measured with the laser Doppler apparatus for every nozzle to use beforehand, and calculated | required the average mist diameter (the sum total of the diameter of all the particles divided by the number of particle | grains).

As a result, as shown in FIG. 4, when the average mist particle size of water discharged per 1 Nm ³ of the exhaust gas is 500 μm or less and the water injection amount is 500 g / Nm ³ or less, water is not injected. It was possible to find a condition at which the dust adhesion speed was 100 μm / charge or less at the same level and without causing any trouble in operation.

In addition, when the exhaust gas temperature is not always high and the exhaust gas temperature becomes high only when the converter molten iron is charged as described above, it is not always necessary to perform water injection by water spray. It is particularly desirable to install an exhaust gas thermometer upstream of the spray and inject water at a predetermined flow rate from the water spray when the exhaust gas temperature reaches 600 ° C. or higher.
In addition, although the number of nozzles arranged and the conditions for nozzle arrangement are not limited, it can be confirmed that a better effect can be obtained by reducing the amount of water per nozzle in order to reduce the dust adhesion rate. It is particularly preferable to increase the number of nozzles and reduce the amount of water per nozzle.

  In the following, embodiments corresponding to the claims of the present invention will be described.

In the embodiment of the present invention, water spray nozzles are arranged in the center of the duct 4 with 10 nozzles 10 m downstream from the hood 2 of the rectangular converter, and an exhaust gas thermometer is installed upstream of the water spray. When the exhaust gas temperature reaches 600 ° C or higher, an amount of 300 g per 1 Nm ³ volume of exhaust gas is discharged in the flow direction with water particles having an average mist particle size of 400 µm, and the exhaust gas charged in the hot metal is reduced to 600 ° C or lower. At that time, the injection of water was controlled to stop, and 4000 hot metal charging was performed to measure the amount of dust collected. On the other hand, as a conventional example, even when water injection by spraying was not performed, 4000 charge hot metal was similarly charged and the amount of dust collected was measured.

As a result, compared to the dust collection amount of the conventional example in which water injection is not performed, the present invention has an effect of increasing the dust collection amount by an average of 38%. In addition, the dust adherence of the present invention is only 55 μm / charge on the duct , and the accumulated dust is a slightly harder dust layer compared to the conventional example in which water is not injected, It was not at a level that would hinder.

Furthermore, the number of nozzles was set to 2 and the diameter of the duct was arranged at a position where it was divided into 3 parts, and it was carried out for 4000 ch under the same conditions, but there was a tendency for the amount of dust collection to decrease slightly, The same effect was confirmed.

It is a block diagram of converter ventilation dust collection. It is a block diagram of the water spray equipment. It is a figure which shows the relationship between the temperature of waste gas in the water spray downstream 30m position, and the amount of water injection. It is a figure which shows the relationship between the average particle diameter of water and the amount of water injection which affects the adhesion rate of dust.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Converter 2 Ventilation dust collection hood of rectangular converter 3 Hot metal ladle 4 Dust collection duct of converter 5 Ventilation dust collection duct other than converter 6 Damper 7 Blower 8 Bag filter 9 Hot exhaust gas 10 Water spray equipment 11 Dust Deposit of 12 Hot metal 13 Scrap

Claims (1)

A water spray facility is disposed in a duct through which exhaust gas containing dust generated in the converter flows, an exhaust gas thermometer is installed upstream of the water spray facility, and the exhaust gas temperature measured by the exhaust gas thermometer is 600 ° C. In this case, water particles having an average mist particle size of 500 μm or less are discharged in an amount of 50 g to 500 g per 1 Nm ³ volume of exhaust gas in the downstream direction in the duct through which the exhaust gas flows from the water spray facility. A method for collecting dust from an exhaust gas from a converter, wherein the dust is collected.

Images