Practical Measures to Reduce Brick Firing Energy Saving in Fired Brick Production

When running a tunnel kiln for fired brick production, high firing energy consumption is one of the biggest cost burdens for brick manufacturers. Many brick plants are seeking reliable ways to cut energy use while maintaining stable brick quality. There are four core directions to lower firing energy consumption: guarantee full fuel combustion, optimize kiln heat exchange, adopt proper brick stacking patterns, and standardize daily kiln operation.

1. Achieve Complete Fuel Combustion

Fuel combustion is an oxidation reaction releasing heat. Complete fuel combustion happens when sufficient combustion air is supplied. Under this condition, there will be no combustible components such as CO, methane, hydrogen or sulfur vapor in flue gas. For solid fuel, no flammable residue remains.

By contrast, incomplete fuel combustion wastes fuel heat. It falls into two categories:

1.  1. Gas incomplete combustion: insufficient oxygen supply leads to unfinished chemical reactions, leaving combustible gas in flue gas.
2.  2. Solid incomplete combustion: enough air is available, yet fuel cannot fully contact air, forming local oxygen shortage.

Only full combustion can maximize heat output for green brick firing.

2. Build Excellent Heat Exchange Conditions Inside the Kiln

The whole brick firing process is continuous heat exchange between green brick bodies and hot gas from fuel combustion. Hot gas transfers heat to the brick body until chemical reactions take place for brick formation.

Preheated air from the cooling zone delivers oxygen to the firing zone and boosts fuel burning. Hot flue gas from firing zone heats wet bricks in the preheating zone and removes residual moisture. After firing, finished hot bricks are cooled by incoming cold air. Gas flow inside the kiln is essential for every stage of brick firing.

3. Apply Reasonable Brick Stacking Methods

Brick stacking aims to build proper brick piles matching firing requirements. The stacking scheme depends on gas flow rules, kiln structure, exhaust system and fuel burning conditions.

Once brick piles are stacked, internal airflow volume, airflow uniformity, distribution of internal fuel and external fuel combustion status are mostly fixed. The airflow meets two types of resistance: fixed resistance from kiln structure, and adjustable resistance from brick piles. Changing stacking density can adjust resistance and airflow.

•   1. Low stacking density brings smaller resistance, larger airflow and better heat transfer.

General stacking principles: keep sparse stacking within a reasonable range. Different schemes for externally-fired bricks and internally-fired bricks.

•   2. Externally fired brick: top dense bottom sparse; middle dense, inner sub-dense, outer sparse; transverse dense, longitudinal sparse; curved kiln section: inner dense outer sparse.
•   3. Internally fired brick: top dense bottom sparse, edge dense middle sparse. Leave gaps beside branch flues to guarantee smooth and balanced airflow across the kiln cross-section.

4. Standardize Kiln Firing Operations

Standardized operation is critical to save energy in tunnel kiln production:

1.   1. Control residual moisture of dry green brick, reduce heat consumption for water evaporation and speed up temperature rise in preheating zone.
2.   2. Stabilize the length and position of preheating zone, firing zone and cooling zone, avoid drifting of each thermal zone.
3.   3. Properly adjust kiln dampers to recycle waste heat as much as possible. Higher waste heat utilization reduces firing energy consumption.
4.   4. Check kiln sealing regularly. Prevent hot gas leakage and cold air infiltration, both will cause heat loss.
5.   5. Accelerate kiln operation cycles to cut heat storage loss of kiln body and kiln cars.
6.   6. Improve finished brick yield rate. This is the most direct and effective measure to save energy. Higher yield saves heat, electricity, labor and raw material costs, and extends equipment service life.

FAQ

Q1: What is the main reason for high energy consumption in brick kilns?

A: Common causes include incomplete fuel combustion, poor internal heat exchange, unreasonable brick stacking, unstable kiln thermal zones, air leakage of kiln body and low finished product rate.

Q2: How does brick stacking affect tunnel kiln energy consumption?

A: Brick stacking determines airflow resistance inside kiln. Improper stacking causes uneven airflow, poor fuel combustion and low heat transfer efficiency, which greatly increases energy cost.

Q3: What is the difference between internal fuel brick and external fuel brick stacking design?

A: Externally fired bricks adopt "top dense bottom sparse, middle dense outer sparse". Internally fired bricks use "top dense bottom sparse, edge dense middle sparse".

Q4: How to improve waste heat utilization in brick tunnel kiln?

A: Optimize damper operation, strengthen kiln sealing, stabilize thermal zones, and use waste flue gas for preheating raw bricks.

Q5: Why is finished brick yield rate important for energy saving?

A: Defective bricks consume the same fuel and heat but cannot be sold. Boosting yield directly cuts energy consumption per ton of qualified fired brick.