The tertiary air duct of the cement plant is a pipe connecting the decomposition furnace and the preheater, which is used to transport hot air from the cooler to the decomposition furnace to provide the heat needed for the decomposition of materials in the decomposition furnace. The temperature of the gas in the tertiary air duct is very high, usually between 300°C and 800°C or even higher, and is accompanied by a large dust content. Therefore, the expansion joints used in the tertiary air ducts must be able to withstand high temperatures, wear and corrosion, while having good sealing and compensation capabilities.
Under such working conditions, metal expansion joints are generally used in the tertiary air ducts of cement plants, especially high-temperature metal expansion joints. The advantage of metal expansion joints is that they can handle high-temperature, high-dust environments while providing good compensation ability and low reverse thrust, reducing the impact on the pipeline system. They are typically constructed from multiple layers of composite materials, including:
Inner wear layer: Constructed of high temperature and wear resistant materials such as glass fiber or special coated fabrics, direct contact with high temperature gases and dust, providing wear resistance and prolonged service life.
Frame structure: The frame made of stainless steel or heat-resistant alloy is used to support the whole expansion joint and ensure the structural stability.
The selection and design of non-metallic expansion joints should consider the following factors:
Operating temperature: The expansion joint must be able to withstand the high temperature inside the tertiary air duct.
Dust wear: The material needs to have good wear resistance to resist dust wear carried in high speed airflow.
Displacement compensation: The expansion joint shall have sufficient compensation capacity to accommodate the displacement of the tertiary air duct due to thermal expansion and contraction.
Sealability: In order to prevent dust leakage and the influence of external environment, the expansion joint needs to have good sealing performance.
Ease of maintenance: The expansion joint should be designed to facilitate inspection and maintenance so that problems can be found and solved in time.
The metal expansion joint of the tertiary air duct of the cement plant is usually customized by a professional manufacturer according to the specific application conditions to ensure its performance to meet the special needs of the cement production line.