How to Reduce Brick Kiln Gas Consumption with Burner Upgrades and Heat Recovery
Capital Expenditure Needs Evidence
UK brick manufacturers are under pressure from high gas costs, low demand and the need to protect margins. When production volumes are weak, every avoidable unit of gas has a greater effect on the cost of each saleable tonne.
This makes burner efficiency and heat recovery worth investigating, but it does not make every upgrade proposal commercially sound. Generic fuel-saving claims are not enough for works managers, energy managers and directors responsible for approving capital expenditure.
A credible burner business case should begin with a measured assessment of the kiln. It should connect burner performance, recovered heat, gas use, production output, product quality and project cost. This is the only reliable way to evaluate kiln burner upgrade ROI without relying on guesswork or an unsupported percentage saving.
Why Plans to Reduce Brick Kiln Gas Consumption Must Be Site-Specific
Every brickworks operates under different conditions. Two tunnel kilns of a similar size can have different burners, firing zones, insulation, air leakage, pressure profiles, control systems and production schedules.
The firing curve may also change between product types. A kiln firing engineering bricks at high temperatures may have a different heat demand from the same kiln producing a lighter or lower temperature product. Setting density, moisture content, throughput and stoppages can all affect gas consumption.
A site assessment should therefore examine:
Current burner condition and maintenance history
Kiln design and firing zone arrangement
Required firing curves
Combustion air temperature
Airflow and pressure
Gas consumption
Burner control range
Production schedule
Product mix
Reject rate
Gas use should be compared with saleable production, not total production alone. A reduction in gas consumption is not commercially useful if it also causes under-firing, colour variation, cracking, dimensional problems or more rejected bricks.
For a fair comparison, the baseline should use gas consumption per saleable tonne under comparable operating conditions. Start-ups, shutdowns, reduced production and unusual product runs should be identified separately.
Measuring Industrial Burner Efficiency
Industrial burner efficiency cannot be judged from the burner head alone. The burner operates as part of a complete kiln system that includes combustion air, controls, kiln pressure, exhaust conditions and heat losses.
Useful measurements may include:
Gas flow at different firing rates
Combustion air temperature and volume
Recovered air temperature and availability
Oxygen, CO and NOx readings
Kiln zone temperatures
Burner cycling and modulation
Product throughput
Saleable tonnes
Reject levels
Operating hours
These measurements establish where energy is going and whether a proposed change has a realistic chance of producing kiln energy savings.
They also provide the basis for a controlled before-and-after test. Without a defined baseline and agreed test conditions, it is easy to mistake lower production, a different product mix or warmer weather for improved efficiency.
The Role of Recovered Heat
Some kiln systems provide an opportunity to use heat that would otherwise be rejected. This can include hot air from the kiln cooling section where the temperature, cleanliness, pressure and timing make recovery practical.
Recovered cooling air is only useful if it is available when the firing zones require it. The assessment must also consider duct losses, fan power, insulation, pressure drop, controls and the physical route between the cooling and firing sections.
Preheated combustion-supporting air already contains useful thermal energy. If the combustion air enters the burner at a higher temperature, less fuel may be required to provide a given thermal duty, depending on operating conditions.
The burner does not recover cooling air by itself. It can form part of a combustion and heat recovery strategy where preheated combustion-supporting air is available and appropriate.
Gas as Part of a Measured Efficiency Project
The Rapidflame Extflame Burner can be considered as part of a site-specific kiln upgrade where its performance range matches the required duty.
Extflame specifications include:
Heat input range from 2-400 kW
50:1 turndown
Medium velocity and high velocity versions
Natural gas and LPG operation
Maximum flame or flue velocity of 150 m/s
Combustion air preheat capability up to 300 C
Customisable flame tube length
Low CO and NOx performance
Direct spark ignition
The 50:1 turndown can be useful where heat demand varies during start-up, product changes, reduced throughput or normal zone control. A wide stable operating range may allow heat input to follow demand more closely, reduce unnecessary burner cycling and support tighter temperature control.
The benefit depends on correct burner sizing, suitable controls, air and gas ratio management and proper kiln integration.
Low CO performance matters because elevated CO can indicate incomplete combustion, poor mixing, wasted fuel or unsafe operating conditions. Low NOx performance is also important as manufacturers manage environmental obligations, planning requirements and future compliance risk.
CO and NOx performance should be checked across the required operating range during commissioning. A reading taken at one firing rate does not demonstrate performance at every production condition.
Practical Checklist for the Burner Business Case
Before approving a burner or heat recovery project:
Define a representative gas and production baseline.
Record gas use per saleable tonne.
Separate normal production from start-ups, stoppages and abnormal runs.
Inspect the burners, controls, gas train and air supply.
Measure combustion air temperature, airflow and pressure.
Identify practical recovered heat sources, including cooling air where appropriate.
Review firing curves, product mix, throughput and rejects.
Set acceptable product quality and temperature uniformity limits.
Define required CO, NOx and safety performance.
Include burners, ducting, fans, insulation and controls in the project cost.
Include installation, commissioning, downtime and maintenance costs.
Model potential fuel efficiency savings as a range.
Test the calculation against different gas prices and production volumes.
Agree a before-and-after measurement method.
A payback calculation should only be treated as reliable when its assumptions can be traced to measured site data. No fixed saving or payback period should be promised before the kiln has been assessed.
Build the Case Around Measured Performance
The strongest case for fuel efficiency for brick manufacturers is not the highest headline saving. It is a commercially meaningful link between measured kiln conditions, burner capability, recovered heat, gas consumption, saleable output and product quality.
This gives technical teams a project they can test and gives directors a payback case they can challenge before committing capital.
Contact Rapidflame for a practical review of your kiln, current burner arrangement, recovered heat opportunities and likely payback case. Rapidflame can help define what should be measured, assess a suitable burner and establish how potential brick kiln gas savings should be verified, and ensure your company can reliably reduce Brick Kiln Gas Consumption with Burner Upgrades and Heat Recovery.
Frequently Asked Questions (FAQs)
How should a brickworks establish a reliable gas-use baseline?
Use a representative production period and compare metered gas consumption with saleable tonnes, operating hours, product mix, firing curve and reject rate. Start-ups, stoppages and abnormal production should be recorded separately.
Does preheated combustion air always reduce kiln gas consumption?
Not in every situation. Preheated combustion air can reduce the fuel required for a given thermal duty, but the result depends on air temperature, airflow, kiln balance, duct losses, burner controls and production conditions.
Why is 50:1 burner turndown useful in a brick kiln?
A 50:1 turndown can help a correctly sized burner follow changing heat demand during start-up, reduced throughput, product changes and zone control. This may reduce cycling and improve temperature control, depending on the complete combustion system.
What evidence should support a kiln burner upgrade ROI calculation?
The calculation should use measured gas, air, temperature, production and quality data. It should include the complete installed project cost, realistic operating scenarios and an agreed before-and-after test. Savings and payback should remain conditional until performance has been verified.
