Method for improving the stability of the coke discharge of a dry quenching furnace

Abstract

The present application belongs to the technical field of coking, and provides a method for improving the stability of coke discharging of a dry quenching coke oven, which comprises the control of the pre-storage section pressure, the circulating fan rotating speed and the circulating air volume by a circulating system; the adjustment of the opening degree of the dry quenching coke peripheral air duct and the central air duct; the adjustment of the structural parameters of the vibrating feeder and the periodic implementation of large-amplitude coke discharging; the precise suppression of the local discharging speed by adjusting the adjusting rod; and the setting of temperature safety protection for key equipment. The method can significantly reduce the coke discharging temperature, improve the coke discharging uniformity and processing capacity, increase the coke discharging amount of the vibrating feeder by 20% to 30%, and effectively improve the dry quenching coke efficiency.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical coking technology, specifically involving the optimization and control of dry quenching coke production process, and more specifically, a method for improving the stability of coke grate in dry quenching furnaces. Background Technology

[0002] Dry quenching is an advanced coke cooling process compared to traditional wet quenching. Its core principle involves using inert gas circulating in a closed system to exchange heat counter-currently with the hot coke, thereby recovering the sensible heat of the coke and cooling it. This process offers significant advantages such as energy saving, water saving, improved coke quality, and reduced environmental pollution, and has become a standard technology in modern large-scale coking plants. A typical dry quenching unit mainly includes: a coke charging device, a pre-storage chamber, a cooling chamber (cooling section), an annular flue, a primary dust collector, a waste heat boiler, a secondary dust collector, and a circulating fan. Driven by the circulating fan, the circulating gas flows through the cooling chamber, absorbs the heat from the hot coke, and becomes high-temperature gas. It then enters the annular flue, undergoes heat exchange and cooling in the waste heat boiler, is dusted, and returns to the circulating fan, forming a closed loop.

[0003] However, during the long-term operation of dry quenching, a series of complex problems have gradually emerged, severely restricting the maximization of its effectiveness.

[0004] First, construction errors may exist in the cooling section of the dry quenching furnace during the construction phase, or after long-term exposure to the abrasion of high-temperature coke and the scouring of airflow, the refractory lining may experience uneven erosion or deformation, causing the actual inner diameter of the cooling section to deviate from the design value, forming an irregular flow cross-section. This geometric distortion directly disrupts the uniform distribution of the coke bed, triggering "channeling" or "segregation" phenomena: the coke is unevenly distributed within the cooling section, with some areas (especially the central area) having a thinner material layer and higher porosity, allowing airflow to short-circuit and resulting in poor cooling, leading to higher temperature readings at corresponding points; while in the surrounding areas, the material layer may be densely packed, resulting in slow or even stagnant feeding. This uneven material distribution and cooling directly leads to uneven coke temperature at discharge, with an overall increase in average discharge temperature and significant temperature differences at four points.

[0005] Secondly, uneven coke distribution triggers a vicious cycle. Due to insufficient cooling of the coke in the central area, the proportion of high-temperature coke discharged increases, leading to an increase in the internal gas temperature of equipment such as rotary sealing valves. When the temperature exceeds the equipment's safety threshold (usually set at around 180°C), the rotary sealing valve may trigger a protective trip due to thermal expansion, lubrication failure, or overheating of electrical components, causing an interruption in coke discharge operations. To prevent this problem, operators are often forced to limit the speed of the circulating fan, reducing the total circulating air volume of the system. However, this, in turn, weakens the cooling capacity of the entire system, creating a dilemma of "high temperature -> reduced air volume -> worse cooling -> even higher temperature".

[0006] Furthermore, the coke discharge capacity of the vibrating feeder is limited by the original design parameters and actual operating conditions. Under uneven material distribution, the material pressure on the feeder is unstable, resulting in insufficient and fluctuating coke discharge volume at conventional amplitudes, making stable and continuous coke discharge difficult. Increasing the amplitude may be limited by the mechanical structure, coil gap, and electrical control system, making it ineffective. The combined effect of these problems ultimately results in a single dry quenching unit having a lower processing capacity than designed.

[0007] While existing technologies offer localized solutions for individual problems, such as adjusting fan speed or unblocking feed inlets, they lack a comprehensive and systematic solution encompassing airflow organization, material distribution adjustment, equipment optimization, and process monitoring. In particular, how to safely and effectively enhance system processing capacity without causing equipment failure, while simultaneously ensuring the quality and uniformity of coke cooling, remains a pressing technical challenge. Summary of the Invention

[0008] The purpose of this invention is to address the aforementioned deficiencies in existing dry quenching coke technology by providing a method to improve the stability of coke discharge in dry quenching furnaces. This method optimizes the airflow distribution within the furnace by precisely controlling the air-material matching relationship; improves the uniformity of coke distribution through physical and operational means; and overcomes the bottleneck in coke discharge capacity by optimizing and protecting the parameters of key coke discharge equipment. Ultimately, this method achieves safe, stable, and efficient operation of the dry quenching furnace, comprehensively, collaboratively, and operably improving the coke discharge situation in dry quenching.

[0009] The technical solution adopted by the present invention to achieve the above objectives is as follows: A method for improving the stability of coke discharge from a dry quenching furnace includes: S1. Refined and coordinated control of circulating air volume and air-material ratio; S11. Strictly control the pressure of the pre-storage section of the dry quenching furnace within the range of slightly negative pressure to slightly positive pressure (-50Pa~+50Pa). S12. Gradually increase the operating speed of the circulating fan from the conventional approximately 900 r / min to ≥1200 r / min; the system's circulating air volume reaches and stabilizes in the range of 190000 m³ / h-21000 m³ / h; S13. The air volume increase is coupled with the target coke discharge volume to control the air-to-material ratio in the range of 1240m³ / t-1300m³ / t. S2. Optimization and adjustment of airflow distribution in the cooling section cross-section; Reduce the opening of the central air inlet duct of the dry quenching furnace to 90%-95%; increase the opening of the peripheral air duct of the dry quenching furnace to 40%-45%. S3. Modify the vibrating feeder: S31. Add a shim to the drive end of the vibrating feeder and adjust its installation angle to 6°-7°. S32. Adjust the working air gap between the electromagnetic coil driving the vibrating feeder and the vibrating body to 2.2mm-2.4mm; S33. Implement "short-term high-amplitude coke removal" operation regularly for each shift. Increase the amplitude setting of the vibrating feeder to 40% of the rated maximum amplitude within 5 minutes to perform high-intensity coke removal.

[0010] S4. Precise suppression of local feeding speed; When the temperature at one or more points in the cooling section is consistently significantly higher than at other points, it indicates that the coke layer below that point may be experiencing problems such as excessively rapid feeding and an insufficiently thin material layer. In this case, it is recommended to increase the insertion depth of the section bar to 50mm-60mm.

[0011] S5. Temperature safety protection is installed on critical equipment; A nitrogen top-blowing port is installed on the top of the rotary sealing valve or at a critical high-temperature location. When the gas temperature inside the rotary sealing valve is detected to exceed the safety warning line of 180°C, the nitrogen top-blowing valve is immediately opened automatically or manually to inject room-temperature nitrogen into the valve chamber.

[0012] The pressure of the top-blown nitrogen pipeline should be controlled within the range of 10000Pa-12000Pa.

[0013] The beneficial effects of this invention are: 1. Improved cooling efficiency and coke quality: By increasing the total air volume and optimizing its cross-sectional distribution, sufficient and uniform heat exchange between coke and cooling gas is ensured, significantly reducing the average coke discharge temperature (by 20-40℃) and the uniformity of the coke discharge temperature (significantly reducing the temperature difference at four points), thereby improving the cold strength and hot performance stability of coke.

[0014] 2. Breakthrough Improvement in System Processing Capacity: The modification and optimization of the vibrating feeder directly broke through the hardware bottleneck of coke discharge capacity, increasing the coke discharge volume by 20-30%, enabling the dry quenching furnace to operate continuously at a higher load, close to its design capacity. Combined with the increase in air volume, this significantly increased the daily processing capacity of the unit for red-hot coke.

[0015] 3. Significantly enhanced operational stability and continuity: The nitrogen protection system of the rotary sealing valve effectively prevents equipment tripping due to high temperatures, ensuring continuous and stable coke discharge operations. The application of local regulating rods and short-term large-amplitude operation can dynamically and proactively correct material feeding deviations, avoiding large-scale deterioration of operating conditions or forced shutdown for maintenance caused by the accumulation of local problems.

[0016] 4. Improved economic benefits: The increased efficiency of dry quenching coke directly increases steam production (more than 0.1 tons of steam can be recovered per ton of red coke), thus improving power generation or heating efficiency. At the same time, high-quality dry-quenched coke can indirectly benefit blast furnace ironmaking by reducing the fuel ratio and improving the quality of molten iron. Detailed Implementation

[0017] The present invention will be further described below with reference to embodiments: A method for improving the stability of coke discharge from a dry quenching furnace includes: S1. Refined and coordinated control of circulating air volume and air-material ratio; This step aims to establish and maintain the basic gas-solid phase heat transfer conditions required for efficient cooling; The key is to achieve flexible matching of "production determined by air volume" or "air volume adjusted by production volume".

[0018] S11. Strictly control the pressure of the pre-storage section of the dry quenching furnace within the range of slightly negative to slightly positive pressure (-50Pa~+50Pa). This pressure range helps maintain the airtightness of the system, prevents air intake or gas leakage, and is a prerequisite for subsequent precise air volume adjustment.

[0019] S12. Based on the stable pre-stored pressure, gradually increase the operating speed of the circulating fan from the conventional 900 r / min to 1200 r / min or higher; the corresponding system circulating air volume reaches and stabilizes in the higher range of 190000 m³ / h-21000 m³ / h. S13. The above-mentioned increase in air volume must be coupled with the target coke discharge volume to ensure that the air-material ratio is precisely controlled within the optimized range of 1240m³ / t-1300m³ / t. This air-material ratio range has been verified in practice and can ensure sufficient heat exchange while avoiding excessive airflow velocity that could lead to coke pulverization or a sharp increase in system resistance.

[0020] S2. Optimize and adjust the airflow distribution in the cooling section; This step addresses the problem of uneven cooling caused by uneven material distribution in the furnace. By adjusting the opening of the air inlet, the airflow entering the cooling section is redistributed.

[0021] The air intake of a dry quenching furnace typically consists of a central air duct and peripheral air ducts. To correct the imbalance of "large central air volume and small peripheral air volume," which leads to excessively rapid cooling of the central coke (which may actually be insufficient due to a thin material layer) and insufficient cooling of the periphery, the air duct opening needs to be adjusted asymmetrically, namely: Increase the opening of the peripheral air duct of the dry quenching furnace to 40%-45%; increasing the peripheral air intake can enhance the cooling intensity of the coke layer in the peripheral area where the coke is thick or the feeding is slow, and promote the cooling of the coke in that area. Reducing the opening of the central air intake channel of the dry quenching furnace to 90%-95% and moderately limiting the air volume in the central area helps to balance the airflow distribution across the entire cooling section, allowing the airflow to penetrate the coke layer more evenly, achieving "air following the material" rather than "air taking a shortcut".

[0022] The duct opening adjustment described in S2, combined with the total air volume increase in S1, ensures that the air volume distribution is more reasonable and meets the local matching requirements of the air-material ratio at various points in the cross section when the total air volume increases.

[0023] S3. Modify the vibrating feeder; This step aims to address the insufficient capacity of the coke discharge equipment and proactively improve the initial material distribution in the furnace. To address the issues of low coke discharge volume and limited amplitude enhancement, two key modifications can be implemented to the vibrating feeder: S31. Add a shim to the drive end of the vibrating feeder and adjust its installation angle to 6°-7°. Increasing the angle helps the coke to better converge and flow towards the discharge port under gravity, reducing the risk of "arching" and blockage.

[0024] S32. Adjust the working air gap between the electromagnetic coil driving the vibrating feeder and the vibrating body to 2.2mm-2.4mm; This adjustment allows for a larger vibration amplitude at the same input voltage / current, or a reduction in electrical load when the desired amplitude is reached, thereby safely increasing the given amplitude and directly improving the coke discharge capacity per unit time. Practice has shown that this modification can increase the coke discharge capacity of the vibrating feeder by 20%-30% under the same power consumption.

[0025] S33. Implement "short-term large-amplitude coke discharge" operation regularly per shift to break in the inner wall of the dry quenching furnace. For example, increase the amplitude setting of the vibrating feeder to 40% of the rated maximum amplitude within 5 minutes to perform high-intensity coke discharge. This short-term, strong coke discharge action can generate a strong scouring and vibration effect on the coke layer in the lower part of the cooling section, which helps to "grind" and break in the protruding parts of the newly built or deformed furnace wall, and promotes the coke to fall evenly along the entire coke discharge port section.

[0026] S4. Precise suppression of local feeding speed is used to address local overheating or excessively fast feeding issues detected in real-time monitoring. When the temperature of one or more points in the cooling section is consistently significantly higher than other points, it indicates that the coke area below that point may have problems with excessively fast feeding or an excessively thin material layer. At this time, the insertion depth of the regulating rod is increased to 50mm-60mm. The deeper insertion of the regulating rod into the material layer will locally increase the mechanical resistance of the coke's downward movement, effectively slowing down the downward speed of the coke in the "hot spot" area. This will thicken the material layer in that area, prolong the residence time, and achieve more sufficient cooling, causing the temperature at that point to drop, and ultimately promoting a more balanced feeding speed across the entire coke discharge section.

[0027] S5. Temperature safety protection is installed on critical equipment to ensure the operational reliability of critical equipment (rotary sealing valve) when the system load is increased (high air volume, high coke discharge), specifically including: 1. Set up a nitrogen active cooling mechanism: Install a nitrogen top-blowing interface and a nitrogen top-blowing valve on the top of the rotary sealing valve or in a critical high-temperature part. When the gas temperature inside the rotary sealing valve or the critical high-temperature part is detected to exceed the safety warning line of 180°C, the nitrogen top-blowing valve will be opened automatically or manually to inject room temperature nitrogen into the valve cavity.

[0028] 2. Pressure control mechanism: To ensure cooling effect and not interfere with the normal discharge function of the sealing valve, the pressure of the top-blown nitrogen pipeline is controlled in the range of 10,000 Pa to 12,000 Pa. This pressure range is sufficient to provide effective cooling airflow without blowing away coke or damaging the valve body seal due to excessive pressure. Example

[0029] To address the issue of excessively high coke discharge temperature and insufficient coke discharge volume in dry quenching furnaces, the method of this invention is used for optimization: The initial conditions are as follows: the pressure in the pre-storage section is about 0 Pa, the speed of the circulating fan is 850 r / min, the circulating air volume is about 170,000 m³ / h, the average coke discharge temperature is 170℃, the temperature difference at four points reaches 80℃, the coke discharge capacity of the vibrating feeder is only 70% of the design value, and the rotary sealing valve has an intermittent high temperature alarm.

[0030] The process of implementing this method is as follows: S1. Stabilize the pre-storage section pressure at 0±20Pa; gradually increase the speed of the circulating fan to 1180r / min, and stabilize the circulating air volume at approximately 210000m³ / h; calculate and control the air-to-material ratio at 1300m³ / t based on the target coke discharge rate.

[0031] S2. Adjust the opening of the peripheral air duct of the dry quenching coke from 25% to 41%, and the opening of the central air duct from 100% to 92%.

[0032] S3. Modify the vibrating feeder: Add shims to the rear and adjust its tilt angle to 7°; adjust the gap of the electromagnetic coil to 2.2mm; after the modification, the coke discharge rate increases by approximately 28% under the same given amplitude. Perform short-term, high-amplitude coke removal once a day: set the amplitude to 40% and run continuously for 5 minutes.

[0033] S4. Observing that the temperature at a certain point on one side of the cooling section is consistently high, the insertion depth of the two adjusting rods below that point is increased from 30mm to 55mm.

[0034] S5. A nitrogen top-blowing port is installed on the top of the rotary sealing valve; Set the rotary sealing valve temperature interlock: When the valve internal temperature is >180℃, the top nitrogen top blowing will be automatically opened, and the pressure will be set to 11000Pa.

[0035] After one week of implementation of the method of the present invention, the average coke discharge temperature dropped to 120℃, the temperature difference at four points decreased to less than 20℃, the coke discharge was continuous and stable, the rotary sealing valve did not trip due to high temperature again, and the steam production increased by 0.087t / ton of coke.

Claims

1. A method for improving the stability of coke discharge from a dry quenching furnace, characterized in that: include: S1. Refined and coordinated control of circulating air volume and air-material ratio; S2. Optimization and adjustment of airflow distribution in the cooling section cross-section; S3. Modify the vibrating feeder: S31. Add a shim to the drive end of the vibrating feeder and adjust its installation angle to 6°-7°. S32. Adjust the working air gap between the electromagnetic coil driving the vibrating feeder and the vibrating body to 2.2mm-2.4mm; S33. Regularly implement short-term, large-amplitude coke removal operations; S4. Precise suppression of local feeding speed; When the temperature at one or more points in the cooling section is consistently significantly higher than that at other points, the insertion depth of the adjusting rod is increased to 50mm-60mm. S5. Temperature safety protection is set for critical equipment.

2. The method for improving the stability of coke discharge from a dry quenching furnace according to claim 1, characterized in that: The specific control content in S1 includes: S11. Strictly control the pressure of the pre-storage section of the dry quenching furnace between -50Pa and 50Pa. S12. Gradually increase the operating speed of the circulating fan from the conventional approximately 900 r / min to ≥1200 r / min; the system's circulating air volume reaches and stabilizes in the range of 190000 m³ / h-21000 m³ / h; S13. The air volume increase is coupled with the target coke discharge volume to control the air-to-material ratio in the range of 1240m³ / t-1300m³ / t.

3. The method for improving the stability of coke discharge from a dry quenching furnace according to claim 1, characterized in that: The specific control content in S2 includes: Adjust the opening of the central air intake channel of the dry quenching furnace to 90%-95%; adjust the opening of the peripheral air duct of the dry quenching furnace to 40%-45%.

4. The method for improving the stability of coke discharge from a dry quenching furnace according to claim 1, characterized in that: The specific operation of short-term large amplitude coke removal in S33 is as follows: increase the amplitude setting value of the vibrating feeder to 40% of the rated maximum amplitude within 5 minutes to perform high-intensity coke removal.

5. The method for improving the stability of coke discharge from a dry quenching furnace according to claim 1, characterized in that: The specific content of S5 includes: A nitrogen top-blowing port is installed on the top of the rotary sealing valve or at a critical high-temperature location. When the gas temperature inside the rotary sealing valve is detected to exceed the safety warning line of 180°C, the nitrogen top-blowing valve is immediately opened automatically or manually to inject room-temperature nitrogen into the valve chamber.

6. The method for improving the stability of coke discharge from a dry quenching furnace according to claim 5, characterized in that: The pressure of the nitrogen top-blowing pipeline is controlled in the range of 10000Pa-12000Pa.