Cracking furnace is one of the key equipment in ethylene plant. It is a reaction equipment that heats the raw materials such as small molecule alkanes or heavy oil atomization in the furnace tube to a certain temperature, so that cracking reaction occurs to generate the ethylene, propylene, carbon quaternary products and their by-products required. Because the furnace temperature of cracking furnace is high (1300℃), the flame center temperature is as high as 1350~1380℃. In order to select materials economically, reasonably and reliably, we must have a full understanding of all kinds of refractory materials to achieve the purpose of application.
Due to the high thermal conductivity of traditional lightweight firebrick or refractory castable structure, the outer wall of cracking furnace shell overtemperature and great heat loss are caused. Ceramic fiber as a new type of refractory insulation material, it has good thermal insulation performance, high temperature resistance, thermal shock resistance and mechanical vibration resistance, convenient construction and other advantages, is more suitable for cracking furnace refractory insulation material.
Compared with traditional refractories, ceramic fiber products have the following advantages:
- High operating temperature:
With the development of application technology of refractory and thermal insulation materials, ceramic fiber products have achieved their serialization and functionalization, and can meet the requirements of different grades of service temperature from 600 ℃ to 1500 ℃ in terms of service temperature. From the form, it has gradually formed a variety of secondary processing or deep processing products from the most traditional cotton, blanket and felt products to fiber modules, boards, profiled parts, paper, fiber textiles and other forms. It can fully meet the needs of different forms of products in different application parts of industrial furnaces in various industries. - Small bulk density:
The bulk density of ceramic fiber products is generally 64~320kg/m3, which is about 1/3 of light bricks and 1/5 of light refractory castables. For the newly designed furnace body, it can not only save steel, but also further simplify the furnace structure. - Small heat capacity:
The thermal capacity of refractory ceramic fiber products is about 1/14~1/13 of refractory bricks and 1/7~1/6 of thermal insulation bricks. For periodically operated cracking furnace, non production fuel consumption can be reduced. - Convenient construction and short period:
Refractory ceramic fiber can be prefabricated into blocks, blankets, felt, rope, cloth, paper, etc. of various shapes, which is convenient to adopt three construction methods. Because of its excellent elasticity and predictable compression, it does not need to leave expansion joints during construction, which is simple and convenient. - Oven drying is not required after construction:
The structure of refractory bricks and refractory castables shall strictly comply with the oven drying curve and curing period. In particular, the curing period of refractory castables is quite long, generally 4-7 days, which reduces the utilization rate of the furnace. If full fiber furnace lining is adopted as a whole, it can quickly rise to the process temperature after construction if it is not limited by other metal components. The utility model not only improves the effective utilization rate of the industrial furnace, but also reduces the non production fuel consumption. - Very low thermal conductivity:
Aluminum silicate fiber is a fiber combination with a diameter of 3-5 um. There are many gaps in the masonry and the thermal conductivity is very low. However, at different temperatures, the thermal conductivity has a corresponding bulk density and a corresponding bulk density, which increases with the increase of temperature. - Good chemical stability and resistance to air scour.