JP4297430B2 - Non-combustion gas recovery type exhaust gas treatment device gas recovery device and gas recovery method - Google Patents

Description

The present invention, by suppressing the variation of excessive gas pressure during the recovery / dissipation of the non-combustion-type converter exhaust gas treatment system gas, ejection of the gas from the furnace opening, or with the suction air to minimize the blow Gas recovery device and gas recovery method for non-combustion type gas recovery type exhaust gas treatment equipment for converters using a dry electrostatic precipitator, which can increase the gas recovery amount by extending the gas recovery time inside is there.

In the operation of the converter, a large amount of gas mainly composed of carbon monoxide (CO) is generated. Since this gas is high temperature and high in dust content, it is cooled and removed, and then recovered and used for fuel, etc., but the dust removal system has a wet dust collector system and a dry electric dust collector. There is a system used.
As an exhaust gas treatment apparatus for a converter using a dry electrostatic precipitator, there are those described in Japanese Examined Patent Publication No. 59-18625, and those composed of the components shown in FIG. In the exhaust gas treatment apparatus for a converter using a dry electrostatic precipitator shown in FIG. 1, a high temperature and high dust content gas of about 1500 ° C. generated from the converter 1 by blowing is sent to the skirt by an induction fan 9. 2 is sucked into the cooler 3 installed above the converter and cooled to about 1000 ° C. by the cooler 3. Next, in order to obtain a highly efficient dust collection rate, the cooled gas is sprayed with water with an evaporator cooler 4 so that the apparent specific resistance of the converter dust becomes an optimum value, and the gas temperature is set to 150 ° C. to The temperature is controlled at 200 ° C. and guided to the dry electrostatic precipitator 7. The clean gas removed by the dry electrostatic precipitator 7 is diffused into the atmosphere from the diffusion tower (chimney) 11 via the gas flow switching device 10 or the gas recovery duct 12, depending on the concentration of carbon monoxide (CO) contained. It is collected in the gas holder 14 through the gas cooler 13.

  The gas flow switching device 10 is connected to two sealed butterfly valves as shown in Japanese Patent Publication No. 59-18625 with a 90 ° phase shift, and the two valves are always simultaneously at the same speed in the opposite direction. When one valve operates in the opening direction, the other valve operates in the closing direction, and when the operation ends, one valve is always fully open and the other valve is fully closed. A device using two bell-type valves disclosed in Japanese Patent Laid-Open No. 3-21605 is used.

  In addition, the converter exhaust gas treatment facility using a dry electrostatic precipitator has much less pressure loss than the converter exhaust gas treatment facility using a wet venturi scrubber, and the boosting capacity of the blower is 1/3 to 1 / 4 Therefore, when the gas holder pressure is set to 300 to 350 mmAq, the inlet pressure of the induction fan is -150 to -200 mmAq, the outlet pressure is 400 to 450 mmAq including the pipe resistance, and the axial flow fan having a boosting capacity of about 550 to 650 mmAq is used. Adopted.

When blowing is started, the blown oxygen reacts with the carbon in the hot metal to generate a large amount of gas, but at the initial stage of blowing, the carbon monoxide (CO) concentration is low, so combustion occurs and carbon dioxide (CO ₂ ) Dissipated into the atmosphere. The gas pressure at this time is -150 to -200 mmAq at the inlet of the induction fan, and 0 to 50 mmAq at the outlet due to the difference between the pressure loss of the diffusion cylinder and the draft pressure. When blowing progresses and the amount of generated gas increases and the carbon monoxide (CO) concentration becomes sufficiently high, the gas flow path at the outlet of the induction blower is changed from the atmospheric emission side to the gas holder side via the gas flow switching device. Switched. At this time, if the flow path switching is simply performed by the gas flow path switching device, the gas pressure at the outlet of the induction blower rapidly changes from 0 to 50 mmAq at the time of dissipation to 400 to 450 mmAq by adding pipe resistance to the gas holder pressure. On the contrary, when the gas recovery is switched to the atmospheric dissipation, the suction blower outlet pressure suddenly changes from 400 to 450 mmAq to 0 to 50 mmAq.

On the other hand, in converter blowing, the amount of gas generated at the furnace port always fluctuates due to changes in the amount of acid sent, the addition of auxiliary materials, the reaction in the furnace, etc., so the gas pressure between the converter port and the cooler is controlled. In other words, so-called furnace pressure control is performed to minimize the amount of air sucked into the furnace port and the amount of gas blown out. However, in an exhaust gas treatment device for a converter using a dry electrostatic precipitator, the time constant is large because the passing gas flow rate in the precipitator is slow, the volume of the precipitator is large, the pressure boosting capacity of the induction fan is small, etc. There are various problems in controlling the gas pressure or the exhaust gas flow rate using a general damper, and the control method by changing the rotation speed of the induction fan is adopted, and the GD responds to the rotation speed change in a short time. ^{2 An} axial fan with a small (second moment of inertia) is used.

However, in the rotational speed control method, it is difficult to quickly follow a rapid gas pressure fluctuation, and the gas pressure fluctuation particularly at the time of switching of gas recovery / dispersion becomes a problem. In other words, at the time of gas emission and recovery when the induction fan is operated at a rotation speed of 100%, the outlet pressure of the induction fan fluctuates greatly from 0 to 50 mmAq ← → 400 to 450 mmAq in a short time, and the influence is It spreads to the converter furnace mouth. For this reason, a large amount of converter gas is ejected from the furnace port at the start of recovery, while a large amount of air is sucked into the furnace port at the start of emission.
Ejection of the converter exhaust gas from the furnace opening portion, the suction by equipment breakage of hot gas deterioration and building ventilation precipitator working environment in the factory, also a draw a large amount of air to the recovery at the end end of the blow cooler In this case, there is a risk that a premixed gas of CO and O ₂ (air) having high explosive properties is generated, which is not preferable for safety.

Methods for preventing these inconveniences are disclosed in Japanese Patent Publication No. 37-18355, Japanese Patent Publication No. 47-11562, and Japanese Patent Publication No. 3-21605, all of which sufficiently solve the above problems. It has not reached.
That is, in the thing of Japanese Examined Patent Publication No. 37-18355, during the recovery and the emission, both “the control to make the gas pressure upstream of the chimney damper (the emission pressure control damper) equal to the holder pressure” is adopted. During the recovery, the chimney damper is fully closed and a large pressure fluctuation occurs when switching from recovery to emission. Therefore, there is no problem in the case of emission → recovery, but the problem is not solved in the case of recovery → emission.

  Japanese Patent Publication No. 47-11562 has been made to solve the above problem, and when the gas is released, the gas pressure in the diffusion tower (atmospheric emission side) is detected to set the damper opening to the set value. The exhaust gas flow rate is measured during gas recovery, and the damper opening degree is controlled according to the exhaust gas flow rate every moment. However, this method has the following problems.

(1) During converter operation, the amount of gas generated constantly fluctuates, and the gas holder pressure during gas recovery is not constant due to fluctuations in the amount of gas discharged to the recovery gas user. In the “method of controlling the opening degree to the pressure”, the difference between the diffusion tower internal pressure and the gas holder internal pressure becomes large, and this difference is not constant, so it is difficult to determine the diffusion tower pressure as an actual problem. For this reason, the pressure fluctuation at the time of emission → recovery cannot be completely suppressed, and there is only an effect of slightly reducing the influence of the gas pressure fluctuation.

(2) Measuring the exhaust gas flow rate during recovery and controlling the damper opening according to the exhaust gas flow rate every time, when the flow meter is installed on the inlet side of the induction fan, the pressure / temperature conditions are different from the induction fan outlet Although the actual air volume must be calculated, the converter exhaust gas treatment system using a dry electrostatic precipitator cannot accurately measure the amount of water vapor in the exhaust gas, so the specific weight of the exhaust gas is unknown, and the correct actual gas flow rate is obtained. I can't.

More specifically, when a dry electrostatic precipitator is used as the precipitator, the gas temperature is set to 150 ° C. to 200 ° C. by water spray in order to improve the dust collecting efficiency. In the operation of the converter, the reaction state in the furnace constantly fluctuates, so that the amount of gas generated, furnace port combustion rate, and gas temperature constantly fluctuate. For this reason, the amount of sprayed water in the evaporation cooler is always controlled in order to keep the electric dust collector inlet gas temperature constant. Although the amount of water sprayed to the evaporation cooler is controlled by feeding back the gas temperature at the outlet of the evaporation cooler, it cannot completely follow the fluctuations in the exhaust gas amount and the gas temperature. Alternatively, it is trapped by dust and falls to the bottom of the evaporation cooler, so the amount of water vapor in the exhaust gas cannot be accurately grasped. That is, since the water vapor in the exhaust gas is not in a saturated state, the amount of water vapor in the exhaust gas cannot be obtained, and therefore the accurate exhaust gas flow rate cannot be measured.
Therefore, simply by adjusting the opening degree using the exhaust gas flow rate, there is a large error with respect to the opening degree in accordance with the actual exhaust gas flow rate, and it is difficult to completely avoid the gas pressure fluctuation at the time of recovery / dispersion switching. It is a fact.

Japanese Patent Publication No. 3-21605 discloses a method of suppressing gas pressure fluctuations during emission → recovery using two bell valves, and this method has the following problems.
(1) At the time of switching from collection to diffusion, the recovery side valve is fully closed and then the diffusion side is opened, so there is a moment when the outlet pipe of the induction blower is momentarily completely closed. It is inevitable that the gas pressure fluctuates.
(2) At the time of switching from diffusion to recovery, the operation time of the two bell-shaped valves is different, and further, they operate independently independently. Therefore, the induction blower with a smooth pressure change as described in the specification in a short time It is difficult to make the discharge side pressure completely equal to the gas holder pressure, and the operation time of each valve has to be long. Therefore, the switching time to the recovery system becomes long.

(3) Since the gas holder pressure constantly fluctuates, it is inevitable that there are cases where the pressure fluctuation increases if the operating time of the bell-shaped valve is fixed at a certain time.
(4) Switching from diffusion to recovery is performed by closing the diffusion side valve until the inside of the gas flow path switching device in which the two bell-shaped valves are housed rises to a predetermined pressure, and after raising the predetermined pressure, The release side valve is fully closed by operating in the opening direction. As is apparent from FIG. 3, after the release side valve opening and the recovery side valve opening are equal, the release side valve is fully closed. Is unfavorable for safety, because gas flows out to the diffusion tube side.
(5) Since the operation method and operation time of the two bell-shaped valves are different, the control system becomes complicated and it takes time to adjust the operation time.
Further, these prior arts do not consider measures for emergency stop of blowing, and there is a problem in safety with respect to the interruption of blowing during the most dangerous blowing season in the converter operation.

Japanese Patent Publication No.37-18355 Japanese Patent Publication No. 47-11562 Japanese Patent Publication No. 3-21605

The present invention has been made in view of the above circumstances, and its purpose is to suppress excessive gas pressure fluctuations during recovery / dispersion of converter exhaust gas, thereby minimizing gas ejection from the furnace port and air suction. At the same time, the induction blower discharge pressure control time during recovery / dispersion can be shortened, the gas recovery time during blowing can be extended, and the amount of recovered gas can be increased. Provide a safe exhaust gas treatment apparatus and exhaust gas recovery method.

[Solution 1] (corresponding to claim 1)
Solution 1 for solving the above-mentioned problems is based on the following (a), (b), and (c) in a non-combustion gas recovery type exhaust gas treatment apparatus for a converter using a dry electrostatic precipitator. is there.
(A) Pressure detection device in the gas recovery duct, suction side gas pressure detection device and discharge side gas pressure detection device of the induction fan, suction side gas temperature detection device and discharge side gas temperature detection device, and rotation of the induction fan A number detection device, a current value or shaft power detection device of the induction fan driving motor, and a diffusion pressure control damper provided in the air diffusion side duct.
(B) The opening of the diffusion pressure control damper is set so that the gas pressure on the atmospheric diffusion side is the same as the pressure in the gas recovery duct during the period in which the converter gas generated during blowing is diffused into the atmosphere. To control.
(C) During the period in which the converter generated gas is collected in the gas holder, the suction side gas pressure, the discharge side gas pressure, the suction side gas temperature, the discharge side gas temperature, and the rotation of the induction fan The performance curve of the induction blower is created based on the number, the current value or shaft power of the induction blower drive motor, and the exhaust gas composition, and this is corrected to the use state by the value actually measured in actual operation. The actual gas amount at the outlet of the induced blower is obtained from the intersection of the induced blower total pressure curve and the induced blower total pressure (suction pressure + discharge pressure) measured in actual operation, and in advance according to the obtained actual gas amount. Controlling the opening degree of the diffusion pressure control damper so as to obtain a predetermined opening degree;

[Operation]
During the period in which the converter gas generated during blowing is released into the atmosphere, the gas pressure on the atmosphere release side is the same as the pressure inside the gas recovery duct, so the gas is released into the atmosphere. Even when switching is made so as to recover the gas, it is possible to prevent a sudden change in the suction blower discharge pressure. Further, during the period when the converter generated gas is collected in the gas holder, the actual gas amount at the outlet of the induction blower is obtained, and the opening of the diffusion pressure control damper is controlled according to the actual gas amount. Even when the gas is switched from the recovered state to the atmosphere, it is possible to prevent a sudden change in the suction blower discharge pressure.

[Embodiment 1] (corresponding to claim 2)
Embodiment 1 is the gas recovery type exhaust gas treatment apparatus of Solution 1 described above, in which the control of the diffusion pressure control damper is performed during the period from the start of blowing to the completion of the gas recovery operation of the gas flow path switching device, and the end of gas recovery This is performed during a period from an appropriate time before the scheduled time until the gas diffusion operation of the gas flow path switching device is completed.
[Operation]
The control of the diffusion pressure control damper is performed only for a period from a predetermined time before switching the gas flow path by the gas flow path switching device until the switching is completed.

[Embodiment 2] (corresponding to claim 3)
In the gas recovery type exhaust gas treatment apparatus according to the above-described Solution 1 or Embodiment 1, any one of the period in which the converter generated gas being blown is released to the atmosphere and the period in which the converter gas is recovered in the recovery gas holder Regardless of the period, when blowing is stopped by a method other than the normal method, the damper operation system is switched from the control system to the emergency stop system by the control system-emergency stop system switching signal, and the damper full open signal is The release pressure control damper is immediately fully opened.
[Operation]
When the operation is stopped by an abnormal method during blowing, the diffusion pressure control damper can be immediately fully opened to quickly discharge the converter exhaust gas into the atmosphere.

[Solution 2] (corresponding to claim 4)
Solution 2 for solving the above-mentioned problems is based on the following (a) and (b) in the gas recovery method of the non-combustion gas recovery type exhaust gas treatment device for a converter using a dry electrostatic precipitator. is there.
(B) During the period when the exhaust gas at the time of blowing is diffused into the atmosphere, the opening of the diffused pressure control damper of the atmospheric diffuser side duct is adjusted so that the atmospheric diffused gas pressure is adjusted to the same pressure as the gas recovery duct internal pressure. By controlling the gas flow and preventing sudden changes in the induction blower discharge pressure when switching the gas flow path from gas dissipation to gas recovery, it is possible to prevent gas blowout from the furnace port and reduce the gas flow path switching time. Increase the amount of recovered gas.
(B) The period during which the exhaust gas is collected includes the suction side gas pressure, the discharge side gas pressure, the suction side gas temperature, the discharge side gas temperature, the rotation speed of the induction fan, and the induction fan. Create a performance curve of the induction blower from the current value or shaft power of the driving motor and the exhaust gas composition , correct this to the use state by the value actually measured in the actual operation, and the induced blower total pressure curve of this correction performance curve And the actual gas amount at the outlet of the induction blower from the intersection of the induced blower total pressure (suction pressure + discharge pressure) measured in actual operation, and a predetermined opening according to the obtained actual gas amount. Excessive air intake from the furnace port by controlling the opening of the diffusion gas pressure control damper to prevent sudden change in the induction blower discharge pressure when switching the gas flow path from gas recovery to gas diffusion Prevent cooler Avoiding CO and O ₂ Danger of premixed gas generation _(air) at.

[Operation]
During the period in which the converter gas generated during blowing is released into the atmosphere, the gas pressure on the atmosphere release side is the same as the pressure inside the gas recovery duct, so the gas is released into the atmosphere. Even when switching to recover the gas, it is possible to prevent a sudden change in the suction blower discharge pressure, and to prevent the gas from being blown out from the furnace port. Further, during the period when the converter generated gas is collected in the gas holder, the actual gas amount at the outlet of the induction blower is obtained, and the opening of the diffusion pressure control damper is controlled according to the actual gas amount. Even when the gas is switched from the recovered state to dissipate into the atmosphere, a sudden change in the suction blower discharge pressure can be prevented, and excessive intake of air from the furnace port can be prevented.

[Embodiment 3] (corresponding to claim 5)
Embodiment 3 is the exhaust gas recovery method of Solution 2 above, regardless of whether the exhaust gas being blown is released to the atmosphere or the recovery gas holder is recovered in the blowing gas. Is stopped by a method other than the normal method, the opening degree of the diffusion pressure control damper is immediately fully opened.
[Operation]
The operation is the same as that of the second embodiment.

The effects of the present invention are summarized for each main claim as follows.
(1) Effects of the Inventions According to Claims 1 and 4 A diffusion pressure control damper is installed in the air diffusion side duct so that the pressure is the same as the internal pressure of the gas recovery duct during gas diffusion, and during recovery during gas recovery. Since the opening is controlled to match the furnace gas volume, the gas pressure does not fluctuate significantly when switching between gas emission and gas recovery, and even when switching from gas recovery to gas diffusion, the converter-skirt It is possible to prevent the generation of premixed gas that may explode in the cooler without sucking excess air from the space (furnace port). In addition, when switching from gas emission to gas recovery, a large amount of converter exhaust gas is not ejected from between the converter and the skirt, which deteriorates the working environment in the factory and sucks in high-temperature gas from the building ventilation dust collector. It is possible to prevent the equipment from being damaged by.
And since it is possible to operate two valves (for example, bell-shaped valve) in the gas flow path switching device at the same time, the amount of recovered gas is increased and the safety is improved. Furthermore, since the operation times of the two valves can be made the same, the operation sequence of the gas flow path switching device is simplified, the adjustment of the operation time is facilitated, and the time required for maintenance is greatly reduced. Can do.

(2) Effects of the Inventions According to Claims 3 and 5 Even at the time of so-called emergency stop where the blowing is interrupted, the diffusion pressure control damper is immediately forced to fully open and the converter gas stays in the exhaust gas treatment facility. By discharging the water quickly, it is possible to ensure sufficient safety.

The purpose is to suppress excessive gas pressure fluctuations during converter gas recovery / dispersion to minimize gas blow-out and air suction from the furnace port, and gas recovery when converter-generated gas is released into the atmosphere. This was realized by controlling the opening of the diffusion pressure control damper of the atmospheric diffusion duct according to the pressure in the duct and according to the exhaust gas flow rate at the time of gas recovery.

Next, an embodiment of the present invention will be described with reference to FIGS.
Hot metal is introduced into the converter 1, and pure oxygen is blown into the converter 1 from the lance and / or the bottom of the converter 1, and this reacts with the carbon in the hot metal to convert carbon monoxide as a main component. Furnace gas is generated. Since the amount of gas generated from the converter 1 is small at the start of blowing, air is sucked in between the converter 1 and the skirt 2 with the skirt 2 as the upper limit. It descends to a level corresponding to the amount of gas generated, suppresses air suction and blow-off of the generated gas from between the converter 1 and the skirt 2, and guides it to the cooler 3 by the induction fan 9. The converter exhaust gas cooled to 800 to 1000 ° C. by the cooler 3 is further sprayed with water from the spray nozzle 6 by the evaporation cooler 4 and cooled to 150 to 200 ° C. suitable for the dust removal performance of the dry electrostatic precipitator 7. Is done. After the dust is removed by the dry electrostatic precipitator 7 to obtain a clean gas, the gas having a low carbon monoxide concentration at the initial stage and the final stage of the blowing is led to the diffusion tower 11 through the gas flow switching device 10, and the diffusion tower. (Chimney) Combusted at the top, turned into harmless carbon dioxide and released into the atmosphere.
When the carbon monoxide concentration in the converter gas and the generation amount thereof become sufficient as the blowing progresses, the gas flow switching device 10 switches to the gas recovery duct 12, and the converter gas is heated at 60 ° C. by the gas cooler 13. After being cooled below, it is stored in the gas holder 14.

At the end of the blowing, the converter gas is switched to the diffusion tower side by the gas flow switching device 10 as described above, and burns at the upper part of the diffusion tower as in the start of the blowing, and is harmless. Dissipated into the atmosphere as carbon.
In the conventional method, a large gas pressure fluctuation occurs during the operation of the gas flow path switching device 10 at the time of gas recovery and release, and a large amount of converter gas is blown out or air is sucked in between the converter 1 and the skirt 2. However, in the present invention, as shown in FIG. 2, a diffusion pressure control damper 15 is installed in the diffusion tower so that the diffusion pressure to the atmosphere side is adjusted at the time of gas diffusion, and at the time of gas recovery. These inconveniences were solved by adjusting the opening to match the amount of recovered gas.

Next, the features of the present invention will be described in detail with reference to FIG.
The converter gas is released into the atmosphere when the gas recovery conditions are not established since the blowing is started. During this time, the emission gas pressure is controlled by the emission pressure control damper 15 installed at the lower part of the emission tower 11. The gas pressure in the gas recovery duct 12 (the gas pressure detected by the gas recovery duct internal pressure detection device 24) and the diffused gas pressure are set to the same pressure. Thereby, the first control system switching device 28 is switched by the recovery / dissipation signal B, and it is avoided that the gas pressure fluctuates greatly when recovery is started.
Therefore, it is not necessary to individually operate the two bell valves in the gas flow path switching device 10 as in the prior art, and it is possible to operate them simultaneously. Therefore, the operation sequence of the bell-type valve in the prior art is simplified, the adjustment of the operation time is facilitated, and the amount of converter gas flowing out to the diffusion tower side at the start of recovery is reduced.
Furthermore, since two bell-type valves can be operated simultaneously, the effect of shortening the switching time and increasing the amount of recovered gas can be obtained.

  Next, during the converter gas recovery, the suction side gas pressure detection device 18 and the discharge side gas pressure detection device 21, the suction side gas temperature detection device 19 and the discharge side gas temperature detection device 22 of the induction blower 9, and the induction blower 9. Measure the gas pressure, gas temperature, rotation speed, current value or shaft power by the current value or shaft power detection device 23 of the induction fan driving motor 17 and the induction fan driving motor 17, respectively. By comparing, the converter exhaust gas flow rate during recovery is obtained by the exhaust gas flow rate calculator 25, and the opening degree control of the diffusion pressure control damper 15 is continued by the converter exhaust gas flow rate-diffusion pressure control damper opening degree setting device 26, and recovered. / Even if the first control system switching device 28 is switched by the diffusion signal B to switch from recovery to diffusion, the gas pressure in the gas flow path switching device 10 does not fluctuate. That. Therefore, it is possible to avoid the phenomenon that air is sucked from the furnace port that is generated when switching from the recovery to the diffusion side, and it is possible to prevent the generation of the premixed gas that may explode in the cooler 3.

By the way, in the exhaust gas treatment apparatus for a converter using a dry electrostatic precipitator, a method for obtaining the exhaust gas flow rate using the performance curve of the induction blower is as described below.
Measure the suction blower's suction side gas pressure, discharge side gas pressure, suction side gas temperature, induction fan's rotational speed, current value or shaft power, and exhaust gas composition to create a performance curve for the induction blower. It is corrected to the use state by the value actually measured in the operation. Then, the exhaust gas flow rate is obtained from the intersection of the induced blower total pressure curve of the correction performance curve and the induced blower total pressure (suction pressure + discharge pressure) measured in actual operation.

A specific example of the exhaust gas flow rate calculation method will be described with reference to FIGS. This specific example is used in a converter exhaust gas treatment apparatus using an axial fan and a dry electrostatic precipitator, and has the following specifications.
Converter capacity: 250T / Heat
Amount of acid sent: 60000m ³ N / Hr
Processing gas amount: 180,000m ³ N / Hr
Induction fan capacity: 180000m ³ N / Hr
Induction blower boosting capacity: 600mmAq
(Suction pressure during gas recovery / discharge pressure = −200 mmAq / 400 mmAq)
Induction blower suction gas temperature: 200 ° C
Induction blower suction gas specific weight: 1.301Kg / m ³ N
Attracting fan speed: 1800rpm

Here, the case where the actually measured value at the time of actual operation is the following value will be described.
Suction gas temperature of the induction fan: 200 ° C
Rotation speed: 1600rpm
Suction pressure: -150 mmAq
Discharge pressure: 350mmAq
Amount of acid sent: 60000 m ³ N / Hr
CO concentration: 70%, CO ₂ concentration: 16%, N ₂ concentration: 14%
Current value: 153A

First, the rotational speed of the induction fan is 1500 rpm, which is about 83% of the specified speed, and the fan performance curve [exhaust gas flow rate (m ³⁾ when air with a temperature of 20 ° C. and a relative humidity of 65% is sucked in at a pressure of −200 mmAq. / Min.) Relationship between the blower total pressure (mmAq) and the electric current value (A) of the electric motor] was created and used as a performance curve. This performance curve changes the suction air amount of the blower, measures the suction pressure, discharge pressure, suction temperature, current value, and rotation speed at each suction air amount, and sets each suction air to -200 mmAq, 20 It is created by converting the head (water head) and correcting the rotation speed so as to be in the state of ° C. The air density at this time is 1.177 kg / m ^{3 in the} suction state. The performance curve in FIG. 4 represents the performance when the suction air condition is −200 mmAq, the suction temperature is 20 ° C., and the rotation speed is 1500 rpm.

Next, the performance curve is corrected based on the actual values of the induced blower inlet gas temperature, the induced blower inlet gas pressure, and the rotational speed during actual operation, thereby creating a corrected performance curve (FIG. 4). The corrected performance curve represents the performance at the time of actual operation, the induction blower inlet gas temperature 200 ° C., the induction blower inlet gas pressure −150 mmAq, and the rotation speed 1600 rpm. At this time, since the gas density is unknown, the gas density of 1.301 Kg / m ³ N in the performance curve is adopted. Here, the measured value of the blower total pressure 500 mmAq intersects at three points A, B, and C on the total pressure curve of the correction performance curve.

Generally, the air blower has a plurality of gas flow rates for the same gas pressure, but the gas flow rate corresponding to the measured gas pressure can be identified by the in-furnace oxygen flow rate and the CO or CO ₂ concentration in the exhaust gas. it can.
That is, pure oxygen blown into the furnace reacts with carbon in the hot metal to generate 100% -concentration CO gas, but part of it is burned in the furnace, so-called secondary combustion in the furnace and the furnace port. In the gas recovery-type converter exhaust gas treatment apparatus, the CO concentration becomes 70 to 85% except in the initial stage of blowing due to combustion by the sucked air (furnace port combustion).
Therefore, if the in-furnace oxygen flow rate and the CO or CO ₂ concentration in the exhaust gas are known, the converter exhaust gas flow rate has the relationship shown in FIG. 5, and even if the in-furnace secondary combustion rate and the furnace port combustion rate are unknown. Since an approximate exhaust gas flow rate can be assumed, the exhaust gas flow rate can be specified on the correction performance curve.

It should be noted that the relationship between the oxygen flow rate in the furnace and the CO or CO ₂ concentration in the exhaust gas depends on the decarbonation efficiency, the converter-generated gas composition (the exhaust gas composition sucked into the cooler is basically CO, CO ₂ , N ₂ is but is slightly changed by there) when there is a H ₂ by operating methods, it is possible to cope by previously calculating the value by the respective conditions.

In FIG. 5, curves (a), (b), (c), and (d) indicate the furnace port combustion rate for the furnace secondary combustion rates of 0%, 10%, 20%, and 30%, respectively. Shows the rate of increase in the exhaust gas flow rate with respect to the amount of acid fed “1” injected into the furnace when the value changes from 0 to 100%. In the converter operation of this example, the secondary combustion rate in the furnace is It was about 5 to 20%.
In the embodiment, the vertical line E is drawn from the measured CO concentration of 70% to the point where the CO concentration in FIG. 5 is 70%, and the exhaust gas amount of the lines G and F drawn horizontally from the intersection of the curves (a) and (d). The intersection with the ratio is obtained, and the value is in the range of 1.9 to 2.5 times the amount of acid sent. Using this coefficient, the amount of exhaust gas when the amount of acid sent is 60000 m ³ N / Hr is calculated and converted into the blower suction state at the time of measurement (−150 mmAq, 200 ° C.), the exhaust gas flow rate to be calculated is 3340.4 m ^{3 /} min. located in the 4395.3m ³ / min. in the range, the exhaust gas flow rate suction measured at the attraction blower in the actual operation becomes 3890m ³ / min. of intersection C on the correction performance curve of FIG.

Next, when the measured current value 153A is plotted on the perpendicular of the intersection C, it can be seen that there is a difference between the current values 145A and 8A of the correction performance curve. This difference is due to the gas density. Since the gas density at the time of measurement is unknown, the performance curve of 1.301 Kg / m ³ N is adopted, so (1.301 (= performance curve). Gas density)) × (actual current value in actual operation) / (current value of performance curve), the actual gas density can be obtained, and the value is 1.373 Kg / m ³ N .
On the other hand, since an exhaust gas analyzer is always installed in a gas recovery type converter exhaust gas treatment device, the exhaust gas flow rate and the amount of water vapor in the standard state can be obtained from the exhaust gas composition and the previously obtained gas density.

  By the way, it is not necessary to carry out the control timing of the diffusion pressure control damper throughout the entire period of blowing, and if necessary, gas recovery will be completed from the start of blowing until the gas recovery operation of the gas flow path switching device is completed. It is also possible to set a period from an appropriate time before the gas flow switching device completes the gas diffusion operation.

  Furthermore, at the time of so-called emergency stop where the blowing is interrupted, it is the safest human and facility measure to quickly discharge the converter gas staying in the exhaust gas treatment facility. If there is an emergency stop when the amount of gas is low, and the opening of the diffusion pressure control damper is small, this will cause the discharge of the converter gas to be hindered. By providing a circuit for performing this operation and fully opening the diffusion pressure control damper 15, the exhaust gas from the converter can be discharged quickly even at a low air volume, and sufficient safety can be ensured.

That is, when the blowing is interrupted at the peak of blowing, the second control system switching device 29 is switched by the control system-emergency stop system switching signal A, and the actuator 16 is operated by the damper full open signal C. The diffusion pressure control damper 15 is fully opened, and high-concentration CO gas staying in the exhaust gas treatment device of the converter is combusted in the upper portion of the diffusion tower (see FIG. 3). As a result, the high-concentration CO gas staying in the exhaust gas treatment device of the converter can be made into harmless CO ₂ gas and quickly diffused into the atmosphere, thus ensuring safety.

It is a schematic diagram of the exhaust gas processing apparatus of the conventional converter which used the dry electric dust collector. It is a schematic diagram of the exhaust gas treatment apparatus of the converter of the present invention using a dry electrostatic precipitator. It is a schematic diagram which shows the principal part of the exhaust gas processing apparatus of the converter of this invention in detail. It is a graph which shows the performance curve and correction | amendment performance curve of an induction fan. It is a graph which shows the relationship between waste gas CO density | concentration and waste gas amount ratio for every secondary combustion rate in a furnace.

Explanation of symbols

1: Converter 2: Skirt 3: Cooler 4: Evaporation cooler 5: Dust hopper 6: Spray nozzle 7: Dry electrostatic precipitator 8: Dust hopper 9: Induction blower 10: Gas flow switching device 11: Dispersion tower 12: Gas recovery duct 13: Gas cooler 14: Gas holder 15: Dissipation pressure control damper 16: Actuator 17: Electric motor 18: Suction side gas pressure detection device 19: Suction side gas temperature detection device 20: Rotational speed detection device 21: Discharge side gas pressure detection Device 22: Discharge-side gas temperature detection device 23: Current value or shaft power detection device 24: Gas recovery duct pressure detection device 25: Exhaust gas flow rate calculator 26: Exhaust gas flow rate-dissipation pressure control damper opening degree setting device 27: Gas pressure -Dissipation pressure control damper opening setting device 28: first control system switching device 29: second control system switching device A Control system - emergency stop system switching signal B: recovered / dissipating signal C: damper full open signal

Claims (5)

In the non-combustion gas recovery type exhaust gas treatment equipment of the converter using the dry electrostatic precipitator,
Gas recovery duct internal pressure detection device, suction blower suction side gas pressure detection device and discharge side gas pressure detection device, suction side gas temperature detection device and discharge side gas temperature detection device, and rotation speed detection device of the induction blower And a current value or a shaft power detection device of the induction fan driving motor, and a diffusion pressure control damper provided in the air diffusion side duct,
During the period when the gas generated in the converter during blowing is diffused into the atmosphere, the opening of the diffusion pressure control damper is controlled so that the gas pressure on the atmosphere diffusion side is the same as the pressure in the gas recovery duct. ,
During the period in which the converter generated gas is collected in the gas holder, the suction side gas pressure of the induction fan, the discharge side gas pressure, the suction side gas temperature, the discharge side gas temperature, the rotation speed of the induction fan, A performance curve of the induction fan is created based on the current value or shaft power of the electric motor for driving the induction fan and the exhaust gas composition, and this is corrected to a use state by a value actually measured in actual operation, and the induction fan of the corrected performance curve The actual gas amount at the outlet of the induced blower is obtained from the intersection of the total pressure curve and the induced blower total pressure (suction pressure + discharge pressure) measured in actual operation, and is determined in advance according to the obtained actual gas amount. Controlling the opening of the diffusion pressure control damper so as to be the opening;
A gas recovery device for a non-combustion gas recovery type exhaust gas treatment device for a converter, characterized by suppressing gas pressure fluctuations during recovery / discharge of the converter gas.   When the control of the diffusion pressure control damper is performed, the gas diffusion operation of the gas flow path switching device is started from the time until the gas recovery operation of the gas flow path switching device is completed from the start of blowing and the appropriate time before the gas recovery scheduled end time. The gas recovery apparatus for a non-combustion gas recovery type exhaust gas treatment apparatus for a converter according to claim 1, wherein the gas recovery apparatus is performed in a period until completion.   When blowing is stopped by a method other than the normal method regardless of whether the gas generated in the converter during blowing is being released to the atmosphere or the period in which it is recovered in the recovery gas holder 3. The damper operation system is switched from the control system to the emergency stop system by a control system-emergency stop system switching signal, and the release pressure control damper is immediately fully opened by a damper full open signal. A gas recovery device for a non-combustion gas recovery type exhaust gas treatment device for a converter according to claim 1. In the gas recovery method of the non-combustion gas recovery type exhaust gas treatment device of the converter using the dry electrostatic precipitator,
During the period when the exhaust gas during blowing is diffused into the atmosphere, the opening degree of the diffusion pressure control damper of the atmospheric diffusion side duct is controlled so that the atmospheric diffusion side gas pressure is adjusted to the same pressure as the gas recovery duct internal pressure. By preventing the sudden change in the induction blower discharge pressure when switching the gas flow path from gas emission to gas recovery, it is possible to prevent the gas from being blown out from the furnace port and reduce the gas flow path switching time and the amount of recovered gas Increase
On the other hand, the period during which the exhaust gas is collected includes the suction side gas pressure, the discharge side gas pressure, the suction side gas temperature, the discharge side gas temperature, the rotation speed of the induction fan, and the drive of the induction fan. Create a performance curve of the induction blower from the current value or shaft power of the motor for motor and the exhaust gas composition , correct this to the use state by the value actually measured in actual operation, and the induction fan total pressure curve of this correction performance curve Then, the actual gas amount at the outlet of the induction fan is obtained from the intersection with the total pressure (intake pressure + discharge pressure) of the induced blower actually measured in actual operation , and the opening degree is determined in advance according to the obtained actual gas amount. Thus, by controlling the opening degree of the diffused gas pressure control damper and preventing a sudden change in the discharge pressure of the induced blower when switching the gas flow path from gas recovery to gas diffusion, excessive intake of air from the furnace port is prevented. Prevent cooler CO and O ₂ gas recovery method of the non-combustion gas recovery type exhaust gas treatment apparatus, characterized in that to avoid the risk of the premixed gas generation _(air) at.   Regardless of the period during which the exhaust gas being blown is released to the atmosphere or the period in which the exhaust gas is being collected in the recovery gas holder, if the blowing is stopped by a method other than the normal method, the emission 5. The gas recovery method for a non-combustion gas recovery type exhaust gas treatment device according to claim 4, wherein the opening degree of the pressure control damper is immediately fully opened.

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