【Haichuan Ethylene Cracking Furnace】Ceramic fibers for ethylene cracking furnaces
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I. Structural Features of the Ethylene Cracking Furnace The cracking furnace is the core facility in an ethylene plant; it is a box-type heating furnace with bottom and side heating. A structure generally consists of two parts. The upper part is the convection zone, and the lower part is the radiation zone. The radiation section is equipped with vertical furnace tubes, which serve as the area where the heating and reaction of hydrocarbons take place; the burners of the cracking furnace are generally located at the bottom and side walls of the furnace.
II. Operating temperature inside the furnace and ceramic fiber products used: Since the energy consumption of the pyrolysis furnace is very high, accounting for 60% of the total energy consumption of the ethylene plant, it is particularly important to improve the efficiency of this furnace and reduce heat losses from its structure. Therefore, lightweight Aladdin ceramic fiber zirconium-containing insulation and refractory materials are the main choice for the lining of pyrolysis furnaces. The operating temperature of the furnace tube is 1100°C, while the temperature in the radiation section is generally 1260°C. The refractory lining is one of the components of the radiant and convection sections of an ethylene cracking furnace; ceramic fiber zirconium-containing modules are generally used for the side walls of the radiant chamber, while a ceramic fiber suspended structure can be employed for the refractory lining of the furnace roof.
III. Key points for the use of ceramic fiber refractory linings in ethylene cracking furnaces 1. Treatment of burner nodes at the furnace top: With burners having a fully fiber-based structure, the fiber material cannot bear weight; therefore, stainless steel components are required to secure the burner bricks in place. At the same time, the shape and structure of the burner bricks need to be modified accordingly. The joint area between the burner bricks and the ceramic refractory fiber modules is a key area that requires special attention. Before installing the modules, a 20 mm thick layer of zirconium-containing fiber blanket is wrapped around the burner bricks and secured with heat-resistant steel wire. After installing the zirconium-containing ceramic fiber modules, they are compressed to create a seal. 2. Precautions for use: When using ceramic fiber refractory linings in pyrolysis furnaces, it is important to avoid rapid changes in temperature when starting up or shutting down the furnace. The size and position of the expansion joints should be adjusted as necessary to ensure they meet the required standards; furthermore, care must be taken to prevent the ceramic fibers in the convection section from cracking or falling off during use ； After cracks or delamination occur, the ceramic fiber lining should be replaced promptly and the position of the expansion joints adjusted.
3. Maintenance: During use, it is necessary to regularly inspect and maintain the refractory lining (at least once a year). When checking the ceramic fiber refractory lining, attention should be paid to whether there are any gaps between the modules and at the corners of the furnace wall. It is also important to check whether the lining has become thinner, as well as whether the anchoring elements of the modules are loose or damaged. Furthermore, it is necessary to inspect and repair the refractory materials in the expanding areas of the brick wall based on the surface temperature of the exterior wall. 4. In terms of maintenance, after the installation of the zirconium-containing fiber modules, applying Aladdin high-temperature erosion-resistant coating to their surfaces can extend the time before the fibers crystallize and degrade due to exposure to high-temperature air currents over extended periods.