The Critical Role of Insulation Bricks in Industrial Furnaces

Jul 15, 2023

Insulation bricks, also known as refractory insulating bricks, are a critical component in lining industrial furnaces and insulating high temperature equipment. Insulation bricks provide the crucial function of reducing heat loss, improving energy efficiency, and allowing process temperatures to be maintained.

The most common types of insulation bricks include mullite and silica based products. Let’s take a closer look at mullite insulation bricks and the popular JM23 grade.

insulation fire clay bricks

Mullite Insulation Bricks

Mullite insulating brick is as composed of mullite as the key mineral phase. Mullite refers to an aluminosilicate mineral with a chemical composition of 3Al2O3-2SiO2.

Some key properties and advantages of mullite insulation bricks include:

• Low thermal conductivity resulting in excellent insulation performance even at high temperatures above 1,000°C. This reduces heat losses and improves energy efficiency.
• Good refractoriness allowing long service life at both high temperatures and thermal cycling. Mullite insulation bricks can operate continuously at temperatures up to 1,700°C.
• Excellent thermal shock resistance due to low thermal expansion and high thermal stability. This enhances reliability during start-ups and shutdowns.
• Resistant to aggressive alkali vapors that are present in certain processes like cement manufacturing. This improves durability of the insulation.
• Higher strength and lower creep compared to pure silica insulation products. This allows mullite insulation bricks to sustain mechanical forces and vibration.
• Cost effective insulation solution for many applications compared to special products like alumina.

Due to their well rounded properties, mullite insulation bricks are extensively used in applications like:

• Backup insulation for working lining in furnaces and kilns across industries like steel, glass, aluminum, and cement.
• Insulation linings for petrochemical and chemical process heaters and reformers operating at temperatures over 1,000°C.
• Hot gas duct linings in high temperature furnaces.
• Expansion joints in refractory linings.

So mullite insulation bricks provide an optimal combination of insulation performance, high temperature capability, and mechanical strength at a reasonable cost across a wide range of industries and applications.

JM23 Insulation Bricks

JM23 is a proprietary brand of mullite insulation brick manufactured by Jindal Refractories Limited in India. It conforms toGrade 23 insulation brick specifications as per the Indian Standards IS-8.

Some salient characteristics of JM23 insulation bricks include:

• Low thermal conductivity of under 1 W/m-K resulting in excellent insulation capability. This maximizes energy efficiency.
• Continuous service temperature of 1600°C with excursion capability up to 1700°C thereby meeting requirements of most furnace linings.
• Cold crushing strength greater than 23 MPa for adequate load bearing capacity in service conditions.
• Thermal shock resistance to safely withstand heating and cooling cycles during furnace operations.
• Resists penetration and chemical attack by slag, alkali vapors, and minor process upsets thereby enhancing lining life.
• Precise sizing and dimensional accuracy for ease of installation in furnace linings.

JM23 insulation bricks have proven performance and have been extensively utilized in major industries like:

• Backup insulation linings for coreless induction furnaces in the steel industry.
• Wall and roof backup insulation lining for arc furnaces.
• Backup linings for cement rotary kilns and precalciner chambers.
• Petrochemical cracking heaters, reformers and downstream equipment like sulfur recovery units.

The Critical Role Of Insulation Bricks

Insulation bricks play an indispensable role across industries like metals, glass, aluminum, cement and petrochemicals by containing the high process temperatures inside the furnaces and high temperature equipment. This improves thermal efficiency, reduces energy costs, and protects capital equipment like steel shell. The use of high quality insulation bricks results in major energy savings over the lifetime of industrial furnaces and kilns.