In a can-type calciner, optimizing the air ratio for the secondary combustion of volatile matter to achieve self-heat balance requires comprehensive adjustments from five aspects: precise calculation of air volume, stratified air distribution control, adjustment of excess air coefficient, management of negative pressure inside the furnace, and application of automation control. The specifics are as follows:
I. Precise Calculation of Air Volume
- Volatile Matter Combustion Requirements: Calculate the precise amount of air required for the complete combustion of volatile matter based on its content and calorific value in the raw material. Volatile matter, primarily composed of hydrocarbons, requires sufficient oxygen for its combustion reactions.
- Carbon Burnout Requirements: Consider the burnout process of fixed carbon in the raw material and calculate the amount of air required for its combustion. The combustion of fixed carbon is one of the important heat sources in the calcination process.
- Sulfur Combustion Requirements: If the raw material contains sulfur, calculate the amount of air required for its combustion. Sulfur combustion produces gases such as sulfur dioxide, and ensuring complete combustion is essential to reduce pollutant emissions.
II. Stratified Air Distribution Control
- Fire Lane Stratification Design: Can-type calciners typically have multiple fire lanes, with different temperature distributions and combustion requirements in each lane. Therefore, independent air ratio control is necessary for each fire lane based on its temperature distribution curve.
- Preheated Air Utilization: Preheat cold air through preheated air ducts at the furnace bottom or side walls before introducing it into the fire lanes. Preheated air can enhance combustion efficiency and reduce heat loss.
- Volatile Matter Draw Plate Adjustment: Install draw plates between the volatile matter collection channels and fire lanes. Adjust the opening of the draw plates to control the flow rate and combustion position of volatile matter, thereby optimizing the air ratio.
III. Adjustment of Excess Air Coefficient
- Oxidizing Atmosphere in the Preheating Zone: In the preheating zone, introduce a small amount of primary air to create an oxidizing atmosphere with an excess air coefficient greater than 1. This facilitates the complete combustion of volatile matter and raises the furnace temperature.
- Reducing Atmosphere in the Calcination Zone: In the calcination zone, control the introduction of secondary air to create a reducing atmosphere with an excess air coefficient less than 1. This helps reduce the oxidation burnout of materials and improves the quality of calcined coke.
- Tertiary Air Supplementary Combustion: Introduce an appropriate amount of tertiary air near the end of the kiln to ensure the complete combustion of volatile matter escaping from the preheating zone. This helps raise the overall furnace temperature and extend the length of the calcination zone.
IV. Management of Negative Pressure Inside the Furnace
- Negative Pressure Regime Adjustment: Shift from past negative pressure operations to small negative pressure operations, adjusting the negative pressure in the calciner flue to 80–95 Pa. This helps reduce the intake of cold air and minimize heat loss.
- Negative Pressure Balance Control: Improve the balance of negative pressure through a dual-control approach involving branch and main ducts. Reduce the negative pressure differential between branch and main ducts from 50 Pa to 20 Pa to ensure stable negative pressure in each fire lane.
- Negative Pressure and Temperature Coordinated Adjustment: Coordinate the adjustment of negative pressure and air volume based on the temperature distribution inside the furnace. Increase negative pressure appropriately in high-temperature areas to promote heat dissipation; reduce negative pressure in low-temperature areas to minimize heat loss.
V. Application of Automation Control
- Temperature and Pressure Automatic Regulation System: Promote the application of temperature and pressure automatic regulation systems to automatically adjust temperature and pressure based on a reasonable fire lane temperature distribution curve. This helps maintain stable furnace conditions and improve thermal efficiency.
- Numerical Simulation Optimization: Utilize numerical simulation tools to analyze the thermal and flow fields inside the furnace and perform precise design of the furnace structure based on the distribution characteristics of temperature and negative pressure. Optimize the structures of air ducts and volatile matter channels to enhance the combustion efficiency of volatile matter.
- Online Monitoring and Data Analysis: Install online monitoring equipment to continuously monitor parameters such as temperature, pressure, and air volume inside the furnace. Analyze the monitored data to promptly adjust the air ratio and negative pressure regime, achieving optimized control of self-heat balance.
Post time: Apr-22-2026