Process control method for online dynamic balance adjustment of dry quenching circulating fan

Abstract

The application discloses a process control method for online dynamic balance debugging of a dry quenching circulating fan, which comprises the following steps: stopping coke charging of a coke oven; under the premise that coke discharging temperature meets the requirements, stopping coke discharging when coke level in the dry quenching furnace is lowered to at least 1 meter below the lower edge of the inclined pass; lowering the boiler inlet temperature to about 250 DEG C and below; closing the flat gate, stopping the circulating fan, closing the pre-storage chamber pressure regulating valve and opening the pre-storage chamber pressure relief valve to control the pressure in the pre-storage chamber to 30-90 Pa; closing the circulating fan inlet nitrogen filling valve, keeping the circulating fan outlet nitrogen filling valve open; closing the dry quenching furnace inlet baffle; opening the bottom manhole of the circulating fan and the bottom manhole of the heat exchanger to ventilate the circulating fan. The method can shorten the production stop time during dynamic balance debugging, increase dry coke supply, promote smooth production of a blast furnace, and reduce the loss of power generation benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dry quenching process, in particular to a process control method for online dynamic balance adjustment of a dry quenching circulating fan. BACKGROUND

[0002] The dry quenching system is a process system for recovering the red coke sensible heat by using nitrogen gas as the main component of the inert gas as the intermediate medium. The circulating fan is the most important power equipment in the dry quenching device, which conveys the inert circulating gas in the closed system and completes the process task of recovering the red coke sensible heat. Since the inert circulating gas in the dry quenching furnace exchanges heat with the descending red coke in counter flow, the coke powder is inevitably carried. Although the coke powder is separated by two-stage process dust collectors, there is still a certain concentration of coke powder when entering the circulating fan. After long-period operation of the circulating fan, the impeller is continuously worn by the coke powder, and the dynamic balance is gradually deteriorated, which is reflected by the gradual increase of the fan shaft vibration. When the fan shaft vibration increases to the critical value, the circulating fan will not work normally. When the initial deterioration of the circulating fan dynamic shaft vibration occurs or the condition of replacing the new impeller is not met, the impeller can be temporarily not replaced, and the online dynamic balance method is adopted to adjust the impeller.

[0003] The difficulty of the online dynamic balance adjustment of the dry quenching circulating fan is that the high-temperature red coke in the dry quenching furnace will interfere with the dynamic balance adjustment. If the system is not cooled, in the process of doing dynamic balance on the circulating fan impeller, the circulating fan needs to be stopped and its manhole needs to be ventilated so that the debugging personnel can work inside the circulating fan, and then a large amount of air will enter the dry quenching furnace, ignite the red coke in the furnace, cause local over-temperature in the furnace, damage the refractory and the central air cap of the gas supply device and other equipment. If the red coke is completely lowered below the ignition point, the system cooling, dynamic balance adjustment and system warming-up process need about 8 days, that is, the dry quenching will be stopped for about 8 days, which will cause the interruption of dry coke supply, affect the smooth operation of the blast furnace production, and reduce the dry quenching power generation benefit. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a process control method for online dynamic balance adjustment of a dry quenching circulating fan.

[0005] To solve the above technical problems, the technical solution adopted by the present application comprises the following steps: a, stopping coke charging in the coke oven; under the premise of ensuring that the coke discharging temperature meets the requirements, stopping coke discharging when the coke level in the dry quenching furnace is lowered to at least 1 meter below the lower edge of the chute;

[0006] b, lowering the boiler inlet temperature to about 250 DEG C or below;

[0007] c, closing the flat gate, stopping the circulating fan, closing the pre-storage chamber pressure regulating valve and opening the pre-storage chamber diffusing valve to control the pressure in the pre-storage chamber to 30-90 Pa;

[0008] d. Close the nitrogen charging valve at the inlet of the circulating fan, and keep the nitrogen charging valve at the outlet of the circulating fan open;

[0009] e. Close the inlet damper of the dry quenching furnace; open the bottom manhole of the circulating fan and the bottom manhole of the heat exchanger to ventilate the inside of the circulating fan;

[0010] f. Power off the circulating fan and tag it. Detect the gas composition inside the circulating fan through the manhole at the bottom of the fan. After the test is passed, the commissioning personnel enter the circulating fan to inspect the impeller and weld the adjustment block.

[0011] g. After the impeller has been preliminarily inspected and adjusted, and the commissioning personnel have withdrawn, close the bottom manhole of the circulating fan and the bottom manhole of the heat exchanger, close the pre-storage chamber vent valve, open the dry quenching furnace inlet baffle, and de-signal and power on the circulating fan.

[0012] h. Start the circulating fan;

[0013] i. Open the nitrogen charging valve at the inlet of the circulating fan and start the circulating fan to charge the system with nitrogen;

[0014] j. When the oxygen content in the circulating cooling gas reaches below 5 vol%, intermittent coke loading in the coke oven begins, and dry quenching coke production is gradually restored.

[0015] Furthermore, in step b, the cooling rate is controlled to not exceed 45℃ / h.

[0016] Furthermore, in step h, the rotational speed of the circulating fan is gradually increased.

[0017] Furthermore, the speed of the circulating fan should not be increased by more than 2% each time.

[0018] Furthermore, while increasing the speed of the circulating fan, observe whether the shaft vibration value of the circulating fan is qualified. If it is qualified, proceed to the next step. If it is not qualified, repeat steps e to h until the shaft vibration of the circulating fan is qualified.

[0019] The beneficial effects of adopting the above technical solution are as follows: When the circulating fan is dynamically balanced, the present invention can prevent a large amount of air from entering the dry quenching furnace and igniting the coke, avoid damage to the central air cap of the gas supply device, and also enable the dynamic balancing of the circulating fan impeller without completely cooling the dry quenching system. This shortens the downtime during the dynamic balancing process, increases the supply of dry coke, promotes the smooth operation of blast furnace production, and reduces the loss of power generation benefits.

[0020] The present application can realize the safe on-line debugging of the dynamic balance of the circulating fan of the dry quenching system, prevent coke rekindling during the debugging, fully ensure the safety of the dry quenching refractory, gas supply device and the debugging personnel, shorten the shutdown time of the dry quenching system, and shorten the dry quenching shutdown time by about 7 days compared with the method of completely cooling the system, reduce the influence on the blast furnace production, reduce the loss of dry quenching power generation, and improve the overall economic benefit of the dry quenching. BRIEF DESCRIPTION OF DRAWINGS

[0021] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0022] Figure 1 is a structural schematic diagram of the dry quenching system described in the present application.

[0023] In the figure: coke discharging device 1; flat gate 2; dry quenching furnace 3; pre-storage chamber diffusion regulating valve 4; pre-storage chamber diffusion valve 5; primary dust collector 6; pre-storage chamber pressure regulating valve 7; boiler 8; secondary dust collector 9; circulating fan inlet nitrogen charging valve 10; circulating fan 11; circulating fan outlet nitrogen charging valve 12; heat exchanger 13; dry quenching furnace inlet baffle 14; dry quenching furnace bottom nitrogen charging valve 15; pre-storage chamber I; inclined path area II; cooling chamber III; gas supply device IV. DETAILED DESCRIPTION

[0024] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0025] Figure 1 As shown, the dry quenching system comprises a dry quenching furnace 3, a primary dust collector 6, a boiler 8, a secondary dust collector 9, a circulating fan 11, a heat exchanger 13, a coke charging device and a coke discharging device 1. The circulating cooling gas outlet of the dry quenching furnace 3 is sequentially communicated with the primary dust collector 6, the secondary dust collector 9, the circulating fan 11 and the heat exchanger 13 through pipelines, and the heat exchanger 13 is communicated with the circulating cooling gas inlet of the dry quenching furnace 3. The top of the dry quenching furnace 3 is provided with a diffusion pipeline, and the diffusion pipeline is provided with a pre-storage chamber diffusion regulating valve 4 and a pre-storage chamber diffusion valve 5. The inlet and outlet of the circulating fan 11 are both communicated with nitrogen charging pipelines, the nitrogen charging pipeline of the inlet is provided with an inlet nitrogen charging valve 10, and the nitrogen charging pipeline of the outlet is provided with an outlet nitrogen charging valve 12. The pipeline between the heat exchanger 13 and the circulating cooling gas inlet of the dry quenching furnace 3 is provided with a dry quenching furnace inlet baffle 14. The diffusion pipeline of the heat exchanger 13 is provided with a pre-storage chamber pressure regulating valve 7. The bottom of the dry quenching furnace 3 is communicated with the coke discharging device 1 through the flat gate 2; the coke discharging device 1 is communicated with a nitrogen charging pipeline, and the nitrogen charging pipeline is provided with a dry quenching furnace bottom nitrogen charging valve 15.

[0026] After the above structure, the circulating cooling gas from the gas supply device IV in the lower part of the dry quenching furnace 3 enters the cooling chamber III of the dry quenching furnace 3 and exchanges heat with the red coke, and the cooled coke is discharged through the coke discharge device 1; the circulating gas heated to 880-960℃ enters the primary dust collector 6, removes the large particles of coke powder by gravity, and then enters the boiler 8 to exchange heat with the steam and water medium in the internal heat exchange components of the boiler 8, so that the temperature of the circulating gas is reduced to 160-180℃, and then the circulating gas enters the secondary dust collector 9 to further remove the small particles of coke powder carried therein, and then enters the heat exchanger 13 after being pressurized by the circulating fan 11, and the temperature of the circulating gas is reduced to about 130℃ after exchanging heat with the boiler feed water, and then the circulating gas enters the dry quenching furnace 3 again, so that the closed-circuit circulation of the circulating cooling gas and the recovery of the sensible heat of the red coke are realized.

[0027] The positions and purposes of each device in the dry quenching coke system are as follows:

[0028] The dry quenching furnace 3 is a vertical tank with a circular cross section, the outer shell is made of steel plate, and the inner lining is made of refractory material; in the dry quenching furnace, the red hot coke loaded from the top and the cold circulating gas blown from the bottom exchange heat in reverse, reducing the temperature of the coke from 1000±50℃ to an average of ≤200℃; the upper part of the dry quenching furnace is a pre-storage chamber I, the middle part is a chute area II, the lower part is a cooling chamber III, and the bottom part is a gas supply device IV; the chute area II is provided with a chute opening; the gas supply device IV is provided with a cone, a central air cap, an air duct and a peripheral air ring and other components, which supply the cold circulating gas into the cooling chamber of the dry quenching furnace in the form of a central air cap and a peripheral air ring to exchange heat with the red coke; and the coke in the furnace can uniformly fall.

[0029] The boiler 8 mainly recovers the heat of the high-temperature circulating gas after heat exchange with the red coke in the dry quenching furnace 3, generates steam for heating and power generation.

[0030] The flat gate 2 is installed at the bottom outlet of the dry quenching furnace 3. During normal production, the flat gate 2 is completely opened; when annual maintenance or the coke discharge device needs to be repaired, the flat gate 2 is closed to cut off the coke flow at the bottom of the dry quenching furnace.

[0031] The circulating fan 11 is installed between the secondary dust collector and the heat pipe heat exchanger, and is used to continuously send the closed-circuit circulating gas into the dry quenching furnace after pressurization. The circulating fan 11 mainly consists of a fan body, a motor and an inlet baffle.

[0032] The pre-storage chamber vent valve 5 is located at the upper end of the vent pipe of the pre-storage chamber I of the dry quenching furnace 3, and is a water seal valve structure. Under special conditions, the pre-storage chamber vent valve 5 adjusts the pressure in the pre-storage chamber by venting the gas in the pre-storage chamber.

[0033] Pre-storage chamber venting regulating valve 4: Located at the inlet end of the pre-storage chamber venting valve 5, it is a heat-resistant butterfly valve used to control the amount of vented gas from the pre-storage chamber venting valve 5 and to assist in regulating the pressure inside the pre-storage chamber I.

[0034] Nitrogen charging valve 10 at the inlet of the circulating fan and nitrogen charging valve 12 at the outlet of the circulating fan: located on the nitrogen charging pipelines at the inlet and outlet of the circulating fan 11, respectively, used to charge nitrogen into the circulating gas system and control the oxygen content in the circulating gas system.

[0035] Nitrogen charging valve at the bottom of the dry quenching furnace: Located on the nitrogen charging pipeline connected to the coke discharge device 1, it is used to directly charge nitrogen into the dry quenching furnace 3.

[0036] Dry quenching furnace inlet baffle 14: Located between the outlet of heat exchanger 13 and the circulating cooling gas inlet at the bottom of dry quenching furnace 3, it is used to regulate and cut off the amount of circulating gas entering the gas supply device.

[0037] Heat exchanger 13: Installed on the circulating gas pipeline between the outlet of the circulating fan 11 and the inlet of the circulating cooling gas of the dry quenching furnace 3, it uses boiler feedwater to exchange heat with the circulating gas to reduce the temperature of the circulating gas entering the dry quenching furnace 3 and enhance the heat exchange effect of the dry quenching furnace; preferably a heat pipe heat exchanger.

[0038] Pre-storage chamber pressure regulating valve 7: Located on the circulating gas vent pipe at the top of heat exchanger 13, it controls the pressure of the dry quenching coke circulating gas system by adjusting the pressure in the pre-storage chamber I of the dry quenching furnace.

[0039] The process control method for online dynamic balancing and commissioning of the dry quenching circulating fan includes the following steps:

[0040] a. The dry quenching process notifies the coke oven to stop charging; on the premise of ensuring that the coke discharge temperature meets the requirements, the coke material level in the dry quenching oven 3 is lowered to at least 1 meter below the lower edge of the inclined chute to stop coke discharge, preferably to 1 to 1.5 meters below the lower edge of the inclined chute to stop coke discharge.

[0041] b. By increasing or decreasing the circulating air volume and the amount of nitrogen charged before and after the circulating fan 11, the inlet temperature of boiler 8 is reduced to 250℃ or below, preferably 230-250℃, and the cooling rate is controlled not to exceed 45℃ / h to avoid damaging the refractory material inside the furnace.

[0042] c. Close the flat gate 2 and stop the operation of the circulating fan 11; close the pre-storage chamber pressure regulating valve 7, open the pre-storage chamber vent valve 5, and control the internal pressure of the pre-storage chamber I to 30-90 Pa.

[0043] d. Close the nitrogen charging valve 10 at the inlet of the circulating fan, insert a blind flange at the outlet of the nitrogen charging valve 10 at the inlet of the circulating fan, and keep the nitrogen charging valve 12 at the outlet of the circulating fan open.

[0044] e. Close the inlet damper 14 of the CDQ furnace, open the bottom manhole of the circulating fan 11 and the bottom manhole of the heat exchanger 13, and ventilate the inside of the circulating fan 11 for at least 30 minutes.

[0045] f. Power off the motor of the circulating fan 11, detect the gas composition inside the circulating fan 11 from the bottom manhole of the circulating fan, and after the detection is qualified, the commissioning personnel enter the inside of the circulating fan 11 to check and weld the adjustment block of the impeller.

[0046] g. After the preliminary check and adjustment of the impeller are completed, the commissioning personnel withdraw, the bottom manhole of the circulating fan 11 and the bottom manhole of the heat exchanger 13 are closed, the pre-storage chamber vent valve 5 is closed, the inlet damper 14 of the CDQ furnace is opened, and the motor of the circulating fan 11 is powered on.

[0047] h. Start the circulating fan 11, gradually increase the rotating speed of the circulating fan, each time not more than 2%, observe whether the shaft vibration value of the circulating fan 11 is qualified, if qualified, execute the next step, if not qualified, repeat steps e-h until the shaft vibration of the circulating fan 11 is qualified. During the test, the temperatures at each point of the cooling chamber III of the CDQ furnace 3 should be closely monitored. If the local temperature continues to rise, the flat gate 2 and the CDQ furnace bottom nitrogen charging valve 15 should be opened to supplement the amount of nitrogen to extinguish the red coke; at the same time, the rotating speed of the circulating fan 11 should be increased uniformly and slowly to prevent the inlet temperature of the boiler 8 from rising rapidly and the main steam temperature from exceeding the temperature.

[0048] i. Remove the blind plate at the outlet of the circulating fan inlet nitrogen charging valve 10 in step d and open the valve, and start the circulating fan 11 to charge nitrogen to the system.

[0049] j. After the oxygen content in the circulating cooling gas reaches 5 vol% or less, contact the coke oven to intermittently charge coke, and gradually resume the CDQ production.

[0050] Embodiment: The process control method for online dynamic balance adjustment of the CDQ circulating fan is as follows.

[0051] After the CDQ device of a certain steel plant has been operated for 730 days, online dynamic balance adjustment of the circulating fan is needed, and the specific steps are as follows:

[0052] a. The CDQ process notifies the coke oven to stop charging coke; under the premise that the coke discharge temperature meets the requirements, the coke level in the CDQ furnace 3 is lowered to 1 meter below the lower edge of the ramp, and the coke discharge is stopped; this step takes 2 hours.

[0053] b. The inlet temperature of the boiler 8 is lowered to 250℃ by increasing or decreasing the circulating air volume and the nitrogen charging amount before and after the circulating fan 11, and the temperature reduction speed is controlled to not more than 45℃ / h to avoid damaging the refractory in the furnace; this step takes 14 hours.

[0054] c. Close the flat gate 2, stop the circulating fan 11, close the pre-storage chamber pressure regulating valve 7, open the pre-storage chamber exhaust valve 5, control the pressure in the pre-storage chamber I to 80 Pa. This step takes 0.5 hours.

[0055] d. Close the circulating fan inlet nitrogen charging valve 10, insert a blind plate at the outlet of the circulating fan inlet nitrogen charging valve 10, keep the circulating fan outlet nitrogen charging valve 12 open; This step takes 0.5 hours.

[0056] e. Close the dry quenching furnace inlet baffle 14; open the bottom manhole of the circulating fan 11 and the bottom manhole of the heat exchanger 13, ventilate the inside of the circulating fan 11 for 35 minutes; This step takes 1 hour.

[0057] f. Power off the motor of the circulating fan 11, detect the gas composition inside the circulating fan 11 from the manhole, and after the detection is qualified, the commissioning personnel enter the inside of the circulating fan 11 to check and weld the adjusting block of the impeller; This step takes 1 hour.

[0058] g. After the preliminary inspection and adjustment of the impeller are completed, the commissioning personnel withdraw, close the bottom manhole of the circulating fan 11 and the bottom manhole of the heat exchanger 13, close the pre-storage chamber exhaust valve 5, open the dry quenching furnace inlet baffle 14, and power on the motor of the circulating fan 11; This step takes 0.5 hours.

[0059] h. Start the circulating fan 11, gradually increase the circulating fan speed, each time not more than 2%; observe whether the shaft vibration value of the circulating fan 11 is qualified, if qualified, execute the next step, if not qualified, repeat steps e-h until the shaft vibration of the circulating fan 11 is qualified. During the test, the temperature at each point in the cooling chamber III of the dry quenching furnace 3 should be closely monitored, if the local temperature continues to rise, the flat gate 2 and the dry quenching furnace bottom nitrogen charging valve 15 should be opened to supplement the amount of nitrogen to extinguish the red coke; At the same time, the circulating fan 11 speed should be increased evenly and slowly to prevent the inlet temperature of the boiler 8 from rising rapidly and the main steam temperature from exceeding the temperature; This step takes 2 hours.

[0060] i. Remove the blind plate at the outlet of the circulating fan inlet nitrogen charging valve 10 in step d and open the valve, start the circulating fan 11 to charge nitrogen to the system; This step takes 2 hours.

[0061] j. After the oxygen content in the circulating gas reaches 5 vol% or less, contact the coke intermittent charging furnace, heat up the system, gradually restore the dry quenching coke production, the heating time is 6 hours; From the start of stopping charging to the normal dry quenching coke production, it takes about 30 hours in total.

Claims

1. A process control method for online dynamic balancing adjustment of a CDQ circulating fan, characterized in that, It comprises the following steps: a. Coke oven stops charging; Under the premise of ensuring that the coke discharge temperature meets the requirements, the coke level in the dry quenching furnace (3) is lowered to at least 1 meter below the lower edge of the ramp and stops discharging coke; b. The inlet temperature of the boiler (8) is lowered to 250℃ and below; c. The flat gate (2) is closed, the circulating fan (11) is stopped, the pre-storage chamber pressure regulating valve (7) is closed, and the pre-storage chamber vent valve (5) is opened to control the pressure in the pre-storage chamber to 30-90Pa; d. The circulating fan inlet nitrogen charging valve (10) is closed, a blind plate is inserted at the outlet of the circulating fan inlet nitrogen charging valve (10), and the circulating fan outlet nitrogen charging valve (12) remains open; e. The dry quenching furnace inlet baffle (14) is closed; the bottom manhole of the circulating fan and the bottom manhole of the heat exchanger are opened, and the circulating fan (11) is ventilated; f. The circulating fan (11) is powered off and hung, the gas composition inside the circulating fan (11) is detected from the bottom manhole of the circulating fan, and after the detection is qualified, the commissioning personnel enter the circulating fan (11) to check and weld adjustment blocks for the impeller; g. After the preliminary inspection and adjustment of the impeller are completed, the commissioning personnel withdraw, the bottom manhole of the circulating fan and the bottom manhole of the heat exchanger are closed, the pre-storage chamber vent valve (5) is closed, the dry quenching furnace inlet baffle (14) is opened, and the circulating fan (11) is powered on; h. Start the circulating fan (11); During the test, the temperatures at various points of the dry quenching furnace (3) cooling chamber (III) should be closely monitored. If the local temperature continues to rise, the flat gate (2) and the dry quenching furnace bottom nitrogen charging valve (15) should be opened to supplement the amount of nitrogen to extinguish the red coke; i. Remove the blind plate at the outlet of the circulating fan inlet nitrogen charging valve (10) in step d and open the valve, and start the circulating fan (11) to charge nitrogen to the system; j. When the oxygen content in the circulating cooling gas is below 5vol%, intermittent charging of the coke oven begins, and the dry quenching coke production gradually resumes.

2. A process control method for online dynamic balancing of a CDQ circulating fan as claimed in claim 1, wherein: In step b, the temperature reduction speed is controlled to be no more than 45℃ / h.

3. A process control method for online dynamic balancing of a CDQ circulating fan as claimed in claim 1 or 2, characterized in that: In step h, the circulating fan (11) speed is gradually increased.

4. A process control method for online dynamic balancing of a CDQ circulating fan as claimed in claim 3, wherein: Each increase in the circulating fan (11) speed is no more than 2%.

5. A process control method for online dynamic balancing of a CDQ circulating fan as claimed in claim 3, wherein: While increasing the circulating fan (11) speed, observe whether the circulating fan shaft vibration value is qualified. If it is qualified, the next step is performed. If it is not qualified, steps e-h are repeated until the circulating fan shaft vibration is qualified.

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