One of the most important components in a kiln is the rotary kiln brick lining, also called a refractory lining, which covers the interior of the kiln.
This refractory serves two absolutely vital purposes. First, it is designed to reflect the heat of the kiln inwards and helps create and shape the heat envelope within. If the refractory is damaged or unreliable, the end product will also be unreliable. Secondly, it also protects the exterior of the kiln from damage. Should heat escape past the rotary kiln brick lining, it can quickly warp the shell and cause disastrous malfunctions.
So, few elements of a kiln need to be protected more than the refractory lining. Should it be damaged, both your product and the kiln itself are at risk. With decades of experiencing servicing kilns across America, we have a few tips for keeping your brick lining safe.
Preventing Damage to A Rotary Kiln Brick Lining
Know its erosion properties versus materials being fired
Erosion is somewhat unavoidable with brick linings, but the bricks can be more easily damaged by some materials. The harder and more abrasive the materials in the kiln, the more likely they are to erode the refractory.
Typically, a kiln manufacturer will consult on what materials you’ll be firing, and use a combination of bricks and protective coating selected to hold up under use. However, changing the materials being fired, without adapting the kiln to those new materials, can create extra wear on the refractory lining.
Avoid too many rapid temperature shifts
Generally speaking, once a kiln is at a high temperature, it should maintain that temperature as long as possible. While refractory bricks are chosen for their temperature resistance, numerous cycles of rapidly heating and cooling will cause the bricks to crack, or potentially begin peeling away from the walls. This allows heat to reach the exterior, and damage the shell.
If numerous hot/cold cycles are required, each cycle should be conducted as slowly as is feasible, to protect the bricks.
Stick to the same fuel type
Every fuel used inside a kiln will produce different off-gasses as it burns, and these gasses will coat the refractory lining. If the fuel type is changed too often, this can cause unexpected chemical interactions which damage the bricks. Or, in some cases, it can simply cause the bricks’ coating to become irregular – making it more difficult to maintain your heat envelope.
Maintain the rotation systems
If the systems turning the kiln are unreliable, they’ll introduce bumps and vibrations within the kiln’s interior, which can rapidly degrade the brick lining inside. Besides all the other reasons to maintain your kilns’ support systems, it’s necessary to protect the refractory lining from preventable damage.
Proper Installation Sets the Foundation
The brick lining is a critical component in a rotary kiln system. Taking care during the installation process ensures a strong, long-lasting lining. Key factors include selecting the appropriate brick quality, using the right mortar, and employing experienced technicians to lay the bricks correctly. Thorough inspection after installation identifies any deficiencies to correct.
Maintaining Your Brick Lining
Routine maintenance safeguards your brick lining investment. Inspections inside the kiln should check for hot spots, cracks, and spalling. Thermal imaging can identify issues before they are visible. Any damaged bricks should be replaced as soon as possible. Monitoring the thickness of the brick lining over time is also recommended, as thinning can indicate wear. Addressing problems early minimizes further deterioration.
With proper installation and consistent maintenance, rotary kiln brick linings can reliably withstand high production temperatures over many years. Safeguarding your lining leads to greater efficiency and significant cost savings over the lifetime of your kiln.
Kin Technology are your partners for rotary kiln brick lining installation, repair, and maintenance. If you’re having problems, or need to change to different stock or fuels, contact us for assistance!