Refractory, also known as the lining on the inside of rotary kilns, is essential to the rotary kiln’s process efficiency and lifespan. In this article, we will go over all you need to know about Rotary Kiln Refractory, from its function and various forms to the best ways to maintain it.
How Often Does A Rotary Kiln Require Refractory?
Rotary kilns utilise extremely high temperatures to effect a desired chemical or physical transformation in a substance. The high operating temperatures would typically destroy the carbon steel casing instantly. Rotary Kiln Refractory is employed for this purpose.
Refractory is only used in indirect-fired rotary kilns since it is the primary heat transfer medium; in indirect kilns, heat is transferred through the kiln shell wall. The efficiency of the process would decrease if heat had to travel through refractories before reaching the material. Therefore, indirect-fired kilns often utilize a higher heat-resistant shell instead of refractory.
Furthermore, the flame is always in direct contact with the internal parts of the direct burning kiln. Because these kilns generally do not have combustion chambers. Carbon steel cannot tolerate the extreme heat of the production environment. Which is usually between 1600 and 3200 degrees Fahrenheit (depending on added air).
The shell is the backbone of the system and must be protected at all costs. So as to ensure that the equipment lasts as long as possible without the need for expensive and time-consuming overhaul. That’s why it’s so important to get the refractory setup right and take precautions to keep it safe once it’s in use.
Refractory’s primary function is to prevent the kiln shell from being damaged, but it also helps keep the heat in. Poor Rotary Kiln Refractory might keep the shell from melting, but it can also let a lot of heat escape, decreasing productivity and driving up maintenance costs.
Types of Refractory
Castable and refractory bricks are the two most common varieties, and each has its own benefits and drawbacks.
It is delivered as a powder that requires on-site hydration. Anchors must be set up before the mixture is poured in. These y-shaped anchors function similarly to rebar in concrete, lending strength to the castable lining. The cement-like slurry is pumped into the rotary kiln’s liner once the anchors are set and left to cure for several days.
In terms of hot insulation material, castable refractory is competitive with brick. Brick installation, on the other hand, is far more labor-intensive because each brick must be set in place manually. As a result, brick lining is more expensive than Castable Refractory Cement in terms of total cost.
There are many benefits to the use of castable refractories in a rotary kiln, including lower total cost and ease of troubleshooting. The damaged section can be replaced with a new refractory with minimal downtime.
Firing brick in a furnace gives better characteristics than firing castable refractory of similar composition.
Brick is more expensive than castable, but its higher quality and ease of installation more than make up for the price difference. In most cases, brick refractory is preferable to castable for processing extremely abrasive Refractory Materials since castable is not as durable as brick.
When designing a direct-fired rotary kiln, refractory is essential. Because it shields the kiln shell from the intense heat and pressure of the processing zone. The rotary kiln is an adaptable component of refractory kiln design. Which manipulates elements like content and multiple layers. And can be tailored to meet the specific needs of an application.