JPH05118767A - Sintering and operating method - Google Patents

Abstract

PURPOSE:To prevent corrosion at a dust collector or a duct and a blower discharging gas processing system by a method wherein SO2 and H2O in the discharged gas of sinterring machine are measured, a rapid metal corrosion starting temperature is calculated in response to a result of measurement and a discharged gas temperature in the discharging gas processing system is controlled to be higher than this starting temperature. CONSTITUTION:A sinterring machine is comprised of a raw material feeding hopper 1, a sinterring machine pallet boggie 3, an air box 4, a boiler 5, dust collectors 6, 12, and discharged gas suction blowers 19, 20. Sensitive heat of the discharged gas at a rear half part of the sinterring machine is recovered by vapor at a boiler 5, resulting in that the temperature is lowered at the dust collector 6, sulfuric acid dew formation is produced within the dust collector 6 and so the dust collecting facility is apt to be corroded. In view of this fact, an SO2 meter 13, an H2O meter 14 and a thermometer 15 are mounted at an outlet side of the dust collector, a metal rapid corrosion starting temperature is calculated at 10 in reference to the SO2 value and H2O value. Boiler water feeding amount is adjusted by a water volume adjusting valve 11 in such a way as a practical temperature value is higher than the metal rapid corrosion starting temperature and the temperature of discharged gas is controlled. At the dust collector 12, the hot gas supplying damper 17 is similarly controlled.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a detail relates exhaust gas sensible heat recovery operation method of sintering machine, SO ₂ and H in the flue gas
_The present invention relates to the prevention of corrosion of exhaust gas treatment equipment and ducts by the sulfuric acid of exhaust gas by detecting ₂ O, determining the temperature at which metal starts to be rapidly corroded by sulfuric acid of exhaust gas, and maintaining the exhaust gas temperature above the temperature.

[0002]

2. Description of the Related Art In a Dwightroid-type sintering machine, powdered ore is mixed with powdered coke, the powdered coke is ignited, air is sucked downward, the powdered coke is burned and solidified to produce a sintered ore. There is.

Since the powdered ore contains S, SO ₂ and SO ₃ are contained in the exhaust gas of the sintering machine. S
The O _{3 component} is combined with H ₂ O in the exhaust gas to form H ₂ SO ₄ , which is condensed as sulfuric acid. Sulfuric acid dew point is generally higher than water dew point, and even high temperature exhaust gas will condense, but temperature control cannot be done because the sulfuric acid dew point temperature is unknown. Particularly, in recent years, in a method of recovering heat from a high temperature exhaust gas portion of a sintering machine to lower the exhaust gas temperature as started in JP-A-56-142830, the exhaust gas temperature falls below the sulfuric acid dew point, and Corrosion is severe.

As measures against these, water in the exhaust gas, S
Japanese Unexamined Patent Publication No. 56-100654 has been proposed to detect the O ₃ concentration and operate at a temperature above the sulfuric acid dew point.

[0005]

However, in Japanese Unexamined Patent Publication No. 56-100654, the trace amount of SO ₃ present in the exhaust gas of a sintering machine is detected as a trace amount of SO ₃ .
SO ₂ , H ₂ O, CO, CO ₂ , harmful to O ₃ concentration detection,
It is impossible to accurately detect the concentration of SO _{3 in the} sintering exhaust gas containing NO and the like. In addition, since the properties of the powdered ore for sintering and the sintering operation are constantly changing, and the sulfuric acid dew point of the exhaust gas is constantly changing accordingly, it is necessary to continuously detect the sulfuric acid dew point. Therefore, the problem of corrosion of gas treatment equipment due to sulfuric acid dew point is still unsolved.

The present invention has been made to solve this drawback, and provides a sintering operation method for preventing corrosion of exhaust gas treatment equipment by preventing sulfuric acid dew point of exhaust gas from a sintering machine.

[0007]

The present invention relates to an exhaust gas sensible heat recovery operation method for a sintering machine. More specifically, it detects SO ₂ and H ₂ O in the exhaust gas, and detects the SO ₂ value and the H ₂ O value from the SO ₂ value and the H ₂ O value. The present invention provides a sintering operation method for determining the rapid corrosion start temperature of a metal by sulfuric acid and controlling the exhaust gas temperature of the exhaust gas treatment system to be higher than the above temperature.
O ₂ and H ₂ O were measured to determine the SO ₂ value and H ₂
The sintering operation method is characterized in that the rapid corrosion start temperature of the metal is obtained from the O value and the exhaust gas temperature of the exhaust gas treatment system is controlled to be equal to or higher than the above temperature.

As shown in FIG. 1, the sensible heat recovery of the exhaust gas of the sintering machine is usually performed on the exhaust gas of the latter half of the sintering machine having a relatively high temperature, so that it is divided into the first half and the second half. As a result, the exhaust gas temperature when passing through the dust collector is extremely lowered, so that SO ₃ in the exhaust gas is combined with H ₂ O and liquefied, so-called sulfuric acid dew condensation occurs. As a result, the corrosion of the collector and the like is increased. According to a study by the inventors, it has been found that the sulfuric acid dew point temperature is not constant and changes when the sintering operation changes. The reason for this is that, as shown in Fig. 2, the peak of the amount of SO _X (SO ₂ + SO ₃ ) generated in the sintering exhaust gas is biased toward the latter half of the sintering machine, but this peak fluctuates back and forth with the sintering operation. This is because SO _{3 in} SO _X fluctuates. This fluctuation of the SO _X generation pattern changes depending on changes in the production amount of the sintering operation, the powder ore properties, the air suction amount, and the like. For example, if the sintering air suction amount is small, the peak of the generation of progress is delayed SO _X sintering also shifted towards the back. As a result, the amount of SO _X in the exhaust gas flowing in the latter half increases.

For this reason, the sulfuric acid dew point temperature of the first half exhaust gas decreases, and the sulfuric acid dew point temperature of the second half exhaust gas rises. Such fluctuations in the sulfuric acid dew point temperature always occur in the normal operation of sintering.

Therefore, in order to prevent the sulfuric acid dew condensation on the exhaust gas treatment equipment, it is necessary to constantly detect the sulfuric acid dew point temperature which changes every moment and maintain the exhaust gas temperature higher than the dew point temperature. Conventionally, SO ₂ + SO ₃ in exhaust gas is analyzed by total sulfur oxide analysis (JIS
K0103) and SO ₂ were measured by a sulfur dioxide automatic measuring device (JIS B7981), and the measured value of SO _{2 was} measured.
The remainder obtained by subtracting SO ₂ from + SO ₃ was taken as SO _3, and the acid dew point temperature was calculated from this SO ₃ value.
When the normal exhaust gas temperature below the acid dew point temperature increases rapidly corrosion of metals by sulfuric acid condensation, but the inventors actually exposing the easily corrosive metal during the sintering exhaust gas various SO _X value, corrosion increases rapidly It was found that there was a large difference between the value obtained by measuring the temperature and the acid dew point temperature obtained by the above method. The results are shown in Fig. 3.

As can be seen from the figure, there is a large difference between the acid dew point temperature of the conventional method and the corrosion start temperature of the metal. Moreover,
The difference between the two values is not constant and varies in magnitude. This shows that the acid dew point temperature obtained by the conventional method is not accurate.

Further, the sulfuric acid dew point temperature obtained by the conventional method is relatively higher than the temperature of the method of the present invention, and it is difficult to greatly reduce the exhaust gas temperature by this method, and the amount of exhaust heat recovery becomes small. In order to increase this amount of exhaust heat recovery, it is desirable to obtain a rapid corrosion start temperature of the metal that is lower than the sulfuric acid dew point temperature obtained by the conventional method, and to operate above this temperature.

The inventors have found by various experiments that the rapid corrosion initiation temperature of this metal is related to the amounts of SO ₂ and H ₂ O in the exhaust gas. The relationship is shown in FIG.

For example, the amount of SO ₂ in the exhaust gas is 100 ppm
Therefore, if the amount of H ₂ O is 10%, the rapid corrosion start temperature of the metal is 90 ° C, and by maintaining the exhaust gas temperature higher than this temperature, the corrosion of metal exhaust gas treatment equipment and piping is prevented. You can do it.

The cause of metal corrosion in this case is that SO ₃ in the exhaust gas, not SO ₂ , reacts with H ₂ O to form sulfuric acid, which condenses on the metal surface. Thus, rapid corrosion initiation temperature of the metal by using the following equation (1) from the SO ₂ concentration SO ₃
Is calculated, and the rapid corrosion start temperature of the metal is calculated from the SO ₃ and the H ₂ O value in the exhaust gas using the following equation (2).

[0016]

[Equation 1]

That is, the point of the present invention is to find out the relationship between SO ₂ and SO ₃ in the sintering exhaust gas, quantify this, and finally obtain the rapid corrosion start temperature of the metal.

As a method of controlling the exhaust gas temperature, for example, in the low temperature exhaust gas in the first half of the sintering machine, it is possible to change the mixing amount of the high temperature exhaust gas in the rearmost part of the sintering machine in the low temperature exhaust gas. The exhaust gas temperature can be controlled by changing the sensible heat of the high-temperature exhaust gas in the latter half of the sintering machine, and heating with another burner, steam heating, or the like may be used.

The term "rapid corrosion initiation temperature of metal" as used herein means a value higher than the water dew point temperature and SO ₃ and H ₂ O in exhaust gas.
Reacts to form sulfuric acid and adheres to the metal surface, and this sulfuric acid is the temperature at which the metal begins to corrode. Next, the present invention will be described using examples.

[0020]

EXAMPLES Examples of the present invention will be described below. Figure 5
FIG. 3 is a schematic side view of a sintering machine for carrying out the present invention. In the figure, 1 is a raw material insertion hopper, 2 is an ignition furnace, 3 is a pallet truck for a sintering machine, 4 is a wind box, 5 is a boiler, 6 is a collector, 7 is an SO ₂ meter, 8 is an H ₂ O meter, 9 is a thermometer, 10 is a calculator, 11 is a water flow control valve, 12 is a collector, and 13 is SO.
₂ meters, 14 is an H ₂ O meter, 15 is a thermometer, 16 is a calculator,
Reference numeral 17 is a high temperature exhaust gas supply damper, 18 is a high temperature gas bypass duct, 19 is an exhaust gas suction blower, and 20 is an exhaust gas suction blower.

Since the sensible heat of the exhaust gas in the latter half of the sintering machine, which is relatively high temperature, is recovered by the steam in the boiler 5, the temperature is lowered in the collector unit 6 after the boiler. At this time, if the temperature at the exit of the collector is lower than the rapid corrosion start temperature of the metal, sulfuric acid dew will be generated in the collector, and the collector equipment will be corroded. In order to prevent this, SO ₂ meter 7 and H ₂ O meter 8 are installed on the exit side of the collector.
SO ₂ value of the thermometer 9 installed SO ₂ meter and H ₂ O
The rapid corrosion start temperature of the metal is calculated by the calculator 10 from the H ₂ O value of the meter, and the amount of water entering the boiler is adjusted by the water amount adjusting valve 11 so that the value of the thermometer becomes equal to or higher than the rapid corrosion start temperature of the metal. .

The temperature is relatively low. Exhaust gas in the first half of the sintering machine passes through the exhaust gas duct and passes through the collector 12, but when the temperature at the exit of the collector is lower than the rapid corrosion start temperature of the metal,
Sulfuric acid is condensed in the collector and the collector equipment is corroded. Suddenly from H ₂ O values established the SO ₂ meter 13 and H ₂ O meter 14 and thermometer 15 in the outlet side current麈機SO ₂ value of SO ₂ meter and H ₂ O gauge metal in order to prevent this The corrosion start temperature is calculated by the computer 16, the high temperature exhaust gas supply damper 17 is adjusted so that the value of the thermometer becomes equal to or higher than the rapid corrosion start temperature of the metal, and the high temperature exhaust gas amount is changed via the high temperature gas bypass duct 18. .

By implementing these, the sulfuric acid condensation in the exhaust gas treatment equipment or the duct is eliminated, and the equipment is prevented from corrosion.

[0024]

As described above, the SO ₂ value and the H ₂ O value of the present invention are detected to determine the rapid corrosion start temperature of the metal, and the exhaust gas temperature is kept above the rapid corrosion start temperature of the metal. Corrosion of the exhaust gas treatment system such as the collector and the duct and the blower is completely eliminated, and the life of the equipment is greatly extended.

[Brief description of drawings]

FIG. 1 is an exhaust gas treatment flow chart of a sintering machine for explaining a conventional technique.

FIG. 2 is a SO _X generation pattern diagram of the sintering machine.

FIG. 3 is a comparison diagram of the sulfuric acid dew point temperature by the conventional method and the rapid corrosion start temperature of the metal of the present invention.

FIG. 4 is a diagram showing the relationship between the amount of SO ₂ in the exhaust gas from the sintering machine and the rapid corrosion start temperature of metal.

FIG. 5 is a flow chart of exhaust gas treatment of a sintering machine for carrying out the present invention.

[Explanation of symbols]

1 ... Raw material insertion hopper 2 ... Ignition furnace 3 ... Sintering machine pallet trolley 4 ... Wind box 5 ... Boiler 6 ... Collecting machine 7 ... SO ₂ meter 8 ... H ₂ O meter 9 ... Thermometer 10 ... Computing machine 11 ... Water amount Control valve 12 ... Collector 13 ... SO ₂ meter 14 ... H ₂ O meter 15 ... Thermometer 16 ... Computing machine 17 ... High temperature exhaust gas supply damper 18 ... High temperature gas bypass duct 19 ... Exhaust gas suction blower 20 ... Exhaust gas suction blower

Claims (1)

[Claims] 1. SO ₂ and H ₂ O in the exhaust gas of the sintering machine are measured, the rapid corrosion start temperature of the metal is determined from the SO ₂ value and H ₂ O value, and the exhaust gas of the exhaust gas treatment system is heated to a temperature above the temperature. A sintering operation method characterized by controlling temperature.