If you see rows of shiny black bricks in steel, ceramic or chemical workshops, they are likely to be silicon carbide bricks. This article is mainly divided into three aspects to introduce the uses of silicon carbide.
1.Steel hot zone: from furnace throat to taphole
(1)Throat
The temperature in the throat, bosh and other parts of the blast furnace is higher than 1100 degrees Celsius all year round. At the same time, these parts are also subjected to mechanical erosion by falling furnace charge.
high alumina bricks
The hardness of silicon carbide bricks is second only to diamond and has a high wear resistance index. Therefore, it is embedded in these “throat” positions to cushion the impact.
(2)Taphole
When it reaches the main ditch of the iron outlet, the molten iron flows fast and contains a lot of slag. Ordinary high alumina bricks are easily eroded and thinned. The dense structure of silicon carbide bricks can reduce the erosion rate to the lowest level, thus ensuring the iron-through cycle.
It can be seen from this that silicon carbide bricks are almost indispensable as long as “high temperature + erosion” occurs at the same time in the steel process.
2.Ceramic and glass kilns: uniform firepower and energy saving
(1)Ceramic industry
The quenching zone of the ceramic roller kiln was originally made of heavy clay bricks. The brick has a large heat capacity and is slow to heat up and down. After replacing silicon carbide bricks, the thermal conductivity increased by more than four times. At the same time, the thickness of the kiln wall was halved.
As a result, the heating and cooling time is shortened, the production line is shut down for maintenance and then ignited, and the fuel cost is immediately reduced.
(2)Glass melting furnace
The walls of the clarifier tank of the glass melting furnace are exposed to chemical erosion by alkaline vapor.
silicon carbide bricks
A thin layer of silicon dioxide film will form on the surface of silicon carbide bricks. The membrane blocks further corrosion, extending the life of the pool wall from two years to more than three years.
Therefore, the ceramic and glass industries focus not only on “how high the temperature resistance is”, but also on “whether the size can remain unchanged during temperature changes”.
3.Silicon carbide bricks in chemical industry: acid resistance, thermal shock resistance, and wear resistance
Chemical furnace operating conditions often mix acids, bases, temperature fluctuations and solid particles. For example, the following three situations.
(1)Sulfuric acid boiling furnace
The furnace bed temperature is 400-500 degrees Celsius, and concentrated sulfuric acid vapor continuously penetrates. Silicon carbide bricks hardly react with acid, with weight loss less than one percent.
(2)Melamine reactor
The melamine reactor in the fertilizer plant heats up and cools down several times a day, and the thermal shock cycle can reach more than 50 times.
Silicon carbide bricks have a small thermal expansion coefficient and micro cracks can heal themselves. Thus, the furnace lining will not peel off.
(3)Cyclone separators in petrochemical catalytic cracking units
The high-speed catalyst powder rubs like sandpaper. Silicon carbide bricks have high hardness. Therefore, this characteristic can control the annual wear to less than two millimeters, reducing the need for parking and relining.
In short, as long as the “three evils” of corrosion, thermal shock and wear coexist, silicon carbide bricks will be written into the design manual.
Silicon Carbide Brick
Let’s talk about choosing refractory bricks. There are three main things to look at.First, check the working condition list. Second, check the material specifications. Third, check whether the refractory brick supplier can provide stable supply and provide thermal engineering calculation support.
Align the data before discussing the price, so that high-temperature equipment can be protected by “black armor” for a long time.
