Ceramic fiber products are ideal materials for cracking furnace.

Introduction

Ethylene cracking furnaces are vital components in the petrochemical industry, responsible for breaking down hydrocarbon feedstocks into valuable chemicals such as ethylene and propylene. Operating at extremely high temperatures, these furnaces require advanced thermal insulation solutions that can withstand harsh conditions while minimizing energy loss. Ceramic fiber products, known for their lightweight, excellent thermal resistance, and versatility, have become the preferred choice for lining and insulating ethylene cracking furnaces.

Why choose ceramic fiber products?

The cracking furnace is one of the key equipment in the ethylene plant. It is a reaction equipment that heats the small molecular alkane or heavy oil atomization and other raw materials in the furnace tube to a certain temperature to make them undergo cracking reaction to produce the required ethylene, propylene, C4 and other products and by-products.

Because the furnace temperature of the cracking furnace is high (1300 ℃), the flame center temperature is as high as 1350~1380 ℃. Reducing heat loss through superior insulation lowers fuel consumption and operational costs while protecting furnace components from thermal damage. In order to select materials economically, reasonably, safely and reliably, it is necessary to have a full understanding of various refractory materials to achieve the purpose of application.

The traditional lightweight refractory brick or refractory castable structure, due to its high thermal conductivity, leads to overheating of the outer wall of the cracking furnace shell and large heat loss. As a new type of fire-resistant and thermal insulation material, ceramic fiber has the advantages of good thermal insulation performance, high temperature resistance, thermal shock resistance and mechanical vibration resistance, and easy installation. Therefore, it is suitable to choose ceramic fiber products as refractory and thermal insulation materials for cracking furnace.

 Overview of High Temperature Resistant Ceramic Fiber Materials

High temperature resistant ceramic fiber materials are primarily produced from natural and synthetic raw materials, mainly alumina and silica sources. The most common raw materials include high-purity alumina (Al₂O₃) and silica (SiO₂) powders, which are carefully processed to create ceramic fibers. In some specialized applications, zirconia (ZrO₂) additives are incorporated to enhance the thermal stability of the fiber.

These fibers are then manufactured into various product forms to meet different insulation needs in ethylene cracking furnaces and other high-temperature environments, including:

Ceramic Fiber Boards: Rigid panels made by compressing ceramic fibers and binders, used for structural insulation and support in furnace linings.

Ceramic Fiber Blankets: Flexible, lightweight mats composed of intertwined fibers, ideal for lining irregular or curved surfaces.

Ceramic Fiber Papers: Thin sheets made by felting fibers, often used as gasketing materials or for thermal barriers in tight spaces.

Custom-Made Ceramic Fiber Modules: Pre-formed shapes created through molding or vacuum forming, engineered to fit complex geometries such as tubes, cones, domes, and other specialized components within the furnace.

This variety of product formats allows ceramic fiber insulation solutions to be highly adaptable and customizable, perfectly matching the diverse structural and thermal protection requirements of ethylene cracking furnace applications.

The advantages

Compared to traditional refractory materials, ceramic fiber has the following advantages:

1.High service temperature

With the development of ceramic fiber production and application technology, ceramic fiber products have achieved serialization and functionalization. They can meet different requirements for service temperature from 600℃ to 1500℃. Morphologically, ceramic fiber has evolved from the traditional cotton, blanket, felt, module, board, shaped pieces, paper, textile and other secondary processing or deep-processed products. They can fully meet the needs of different industrial furnaces. 

2. Low bulk density

The bulk density of ceramic fiber products is generally 64-320kg/m3, about 1/3 of lightweight bricks and 1/5 of lightweight refractory castables. It can not only save steel, but also simplify the structure. 

3. Low thermal capacity

Ceramic fiber products, compared to refractory bricks and insulation bricks, have low thermal capacity. Since their bulk density is quite different, their thermal capacity is quite different. The thermal capacity of ceramic fiber is about 1/14-1/13 of refractory bricks and 1/7-1/6 of insulation bricks. For cyclical operation cracking furnaces, it can reduce the fuel consumption. 

4.Convenient construction and short circle

Due to the excellent elasticity, it is no need to reserve expansion joints when construction and general workers can be competent for operation. 

5.No preheating and Maintenance

Refractory brick and castable structure require preheating and maintenance. The maintenance period of castables is long, generally 4-7 days. This will reduce the utilization rate of the furnace. If the whole furnace is built with complete ceramic fiber linings, ignoring the limitation of other metal accessories, it can greatly increase the heating rate and improve the utilization rate and reduce energy consumption. 

6.Low thermal conductivity

Ceramic fiber is an assembly of fiber with a diameter 3-5um. There are a lot of voids in it, so its thermal conductivity is low. But at different temperature, the minimum thermal conductivity and the corresponding bulk density increase with the rising of temperature. According to the experience in recent years, the optimal bulk density is 200-220kg/m3. 

7.Good chemical stability and resistance to air scouring

Ceramic fiber can only be corroded by phosphoric acid, hydrofluoric acid and hot soda, but keep stable in other corrosive media.

Key Applications of Ceramic Fiber Products in Ethylene Cracking Furnaces

Radiant Chamber Sidewalls and Roof Insulation
Specialized ceramic fiber modules, often containing zirconia for enhanced thermal stability, are installed on the sidewalls of the radiant section where temperatures may reach 1260°C. At the furnace crown, suspended ceramic fiber insulation structures provide a lightweight yet robust thermal barrier.

Custom-Shaped Ceramic Fiber Linings
Vacuum-formed and pre-shaped refractories fit perfectly around burners, expansion joints, and complex geometries, improving sealing and insulation efficiency. These low thermal conductivity insulation products greatly reduce thermal bridging and hot spots.

Burner and Nozzle Areas
Heat-resistant ceramic fiber blankets and textiles wrapped around burner bricks help protect metal components from thermal damage and prolong their service life, ensuring stable combustion performance.

Convection Section Insulation
Though temperatures decrease here, ceramic wool linings maintain insulation while accommodating thermal expansion with minimal cracking risks.

Installation Techniques and Maintenance Best Practices

Modern insulation solutions like ceramic fiber modules come with engineered anchoring systems (Y-anchors, M-anchors) that enable fast, secure installation on irregular steel surfaces. Modular construction promotes efficient repairs and partial replacements without extensive downtime.

Daily operation requires cautious temperature ramping during furnace start-up and shutdown to avoid thermal shock damage. Expansion joints need continuous monitoring to prevent fiber lining detachment. In case of damage, modular ceramic fiber linings allow swift exchange, maintaining furnace integrity.

Innovative Forms: Ceramic Insulation and Textiles

Beyond modules and boards, ceramic insulation and textiles such as blankets, papers, ropes, and fabrics play crucial roles in sealing, gasketing, and vibration isolation inside furnace systems. Their flexibility and heat resistance make them indispensable in varied petrochemical furnace applications.

Environmental and Economic Impact

The adoption of ceramic fiber insulation reduces energy consumption and greenhouse gas emissions by significantly minimizing heat loss. Their lightweight nature also decreases structural steel requirements, lowering capital costs. Quick installation and less maintenance translate into operational savings and higher productivity for ethylene producers.

Conclusion

The use of diverse high-temperature resistant ceramic fiber products — from modules and boards to textiles — has revolutionized insulation in ethylene cracking furnaces. Their outstanding qualities such as low thermal conductivity, excellent thermal shock resistance, and installation convenience make them essential materials in modern petrochemical manufacturing. For industry leaders seeking to enhance furnace efficiency and reliability, investing in state-of-the-art ceramic fiber linings is a strategic choice with proven benefits.