Standard Working Condition Adjustment Scheme for Rotary Kiln Burners

1. General Provisions

This scheme applies to daily working condition adjustment, abnormal flame adjustment and anthracite adaptation operation of multi-channel burners for rotary kilns in cement, metallurgy and other industries. It focuses on the adjustment of three major air volume parameters: axial flow air, swirling air and central air. Combined with coal characteristics and kiln internal condition fluctuations, standardized operation specifications are formulated. The objectives are to stabilize flame shape, ensure complete combustion of pulverized coal, avoid kiln coating damage and thermal condition fluctuations. All adjustments shall follow the core principles of minor fine-tuning, steady observation and delayed verification.

2. Standard Adjustment for Conventional Flame Shapes

2.1 Lengthen the flame (for kiln heating and insufficient preheating in the rear kiln zone)

1. Core adjustment parameters: Increase the air volume of axial flow air, and slightly reduce the air volume of swirling air.

2. Adjustment principle: Axial flow air is direct current air. Higher air volume improves the axial injection velocity of the flame and extends the penetration distance of the flame. Reducing swirling air weakens the swirling and dispersion effect of air, prevents radial diffusion of the flame, so as to achieve an overall lengthened and narrowed flame.

3. Application scenarios: Low kiln tail temperature, insufficient preheating in the calcining zone, delayed material calcination, excessively short flame at the kiln head concentrated at the burner nozzle, and other working conditions.

4. Operation precautions: Do not increase axial flow air significantly at one time, to prevent the over-long flame from sweeping the kiln tail and causing high-temperature falling off of the rear kiln coating.

2. Shorten and thicken the flame (for kiln head heating and concentrated calcination in the burning zone)

1. Core adjustment parameters: Increase the air volume of swirling air, and reduce the air volume of axial flow air.

2. Adjustment principle: Enhanced swirling air can strongly disperse pulverized coal and combustion-supporting air, and strengthen radial mixing and diffusion. Reduced axial flow air weakens the axial propulsion force of the flame and shortens the flame injection distance, forming a short, thick flame with concentrated high temperature.

3. Application scenarios: Low temperature in the burning zone, poor clinker granulation, insufficient kiln head temperature, over-long and divergent flame without high-temperature core, and other working conditions.

4. Operation precautions: Do not excessively increase swirling air, to prevent the over-thick flame from attaching to the kiln lining, which will lead to overheating of the front kiln coating, ring formation and lining refractory erosion.

3. Special Adjustment for Abnormal Flame Faults

3.1 Unstable, swaying flame

1. Core fault causes: Insufficient central air resulting in poor flame rigidity, fluctuating pulverized coal supply, segregation of pulverized coal during conveying, and unbalanced air-coal ratio.

2. Adjustment and disposal steps

(1) Appropriately increase central air first to improve the rigidity and stability of the flame center, fix the central position of the flame and eliminate flame swaying;

(2) Inspect the pulverized coal conveying system, troubleshoot unstable bin pressure, fluctuating Roots blower pressure, pipeline dust accumulation and blockage, and stabilize coal supply;

(3) Check the quality of pulverized coal. If pulverized coal segregation and uneven particle size occur, adjust coal mill parameters in a timely manner and clean conveying pipelines to ensure uniform conveying and combustion of pulverized coal;

(4) Fine-tune the ratio of axial flow air and swirling air to ensure uniform mixing of air and pulverized coal and avoid local oxygen deficiency and combustion disorder.

4. Exclusive Adjustment Scheme for Special Coal (Anthracite)

4.1 Coal characteristics

Anthracite has extremely low volatile matter, high ignition temperature, slow combustion rate and long burnout time. It is prone to flame root fire detachment, unstable ignition, incomplete combustion, high carbon content in fly ash and other problems.

4.2 Exclusive adjustment parameters

Significantly increase swirling air, properly match axial flow air and stabilize central air

1. Increased swirling air can strongly disperse dense pulverized coal airflow, expand the recirculation zone of high-temperature flue gas inside the kiln, and continuously draw high-temperature flue gas to the flame root;

2. Stabilize the ignition temperature at the flame root, solve the problems of difficult ignition and easy fire detachment of anthracite, and ensure stable continuous combustion at the flame root;

3. Do not blindly increase axial flow air, so as to avoid flame lengthening and backward shift of ignition point, which will lead to insufficient burnout of anthracite and reduced thermal efficiency.

5. Standard Operation Principles for Fluctuating Kiln Conditions

1. No large-scale adjustment allowed: When the temperature, negative pressure and material state inside the kiln fluctuate, all adjustments of air circuit and coal quantity shall adopt fine-tuning mode, and the adjustment range of single air volume and coal quantity shall not exceed 5% of the total parameters.

2. Delayed observation and verification: The thermal reaction of the rotary kiln has hysteresis. After each fine-tuning, keep stable operation for 10 to 20 minutes, observe the changes of flame shape, kiln temperature, clinker state and kiln tail exhaust gas parameters, and then judge whether secondary adjustment is needed.

3. Linked adjustment of multiple parameters: Frequent modification of a single parameter is prohibited. When adjusting air parameters, monitor coal quantity, kiln rotational speed, negative pressure and other parameters synchronously to match the system working condition.

4. Priority of steady state: When the kiln condition fluctuates violently, stabilize the coal supply and air supply parameters first. After the flame and kiln temperature are initially stabilized, further optimize the flame shape finely.

6. General Operation Prohibitions

1. Do not allow an excessively short and thick flame attaching to the kiln lining, to prevent rapid erosion of front kiln refractory, kiln coating falling off, ring and clinker ball formation;

2. Do not allow an over-long flame sweeping the kiln tail, to avoid over-temperature of the kiln tail smoke chamber and crust blockage;

3. Do not frequently adjust air and coal parameters repeatedly, to avoid continuous disorder of thermal conditions and fluctuation of calcination quality;

4. Under anthracite combustion working conditions, it is strictly prohibited to reduce swirling air and increase axial flow air to eliminate hidden dangers of fire detachment and flameout.