CASE67 · Manufacturing · Boiler combustion correlations
Using stack temperature and oxygen to investigate boiler fuel-intensity changes
Field correlations connect gas-per-steam intensity to flue-gas temperature and oxygen. They guide inspection and combustion tests while preserving the distinction between observed association and confirmed cause.
01 · CASE ANALYSIS
Move from poor efficiency to an explainable question
Fuel intensity can worsen because of load, combustion, heat transfer, feedwater or metering. An intensity alarm alone does not identify the correct action.
The source separately analyzed final stack temperature and flue-gas O₂ against boiler intensity.
02 · CASE ANALYSIS
What the field analysis showed
The material reported more favorable efficiency at lower observed stack temperature and lower observed O₂. Individual-boiler correlations also included load and outdoor conditions.
These are field associations without a published independent saving from adjusting only the two variables.
| Variable | Diagnostic role |
|---|---|
| Gas / steam flow | Fuel intensity in Nm³/tonne |
| Load factor | Condition matching |
| Stack temperature | Heat-transfer/exhaust conditions |
| Flue-gas O₂ | Excess-air condition |
| Steam pressure / temperature | Equivalent service |
03 · CASE ANALYSIS
Interpret combustion within its constraints
Excess air increases the amount of heated exhaust, while too little air can produce incomplete combustion. Lower O₂ is not an unconditional operating objective.
Use qualified combustion checks including CO/combustibles, flame stability and burner conditions when testing a change. The source supplies no universal safe O₂ setpoint.
04 · CASE ANALYSIS
Differentiate possible causes
Persistently high stack temperature can motivate checks of heat-transfer surfaces, economizer, firing rate, air supply and sensor condition. Persistently high O₂ motivates checking air/fuel control and sensor calibration.
These are engineering diagnostic directions, not confirmed source findings that all these faults occurred.
| Step | Meaning |
|---|---|
| Trend and correlation | Observed association |
| Meter/condition review | Check comparability |
| Cause hypothesis | Choose investigation |
| Controlled combustion/maintenance test | Evaluate a feasible action |
| Matched fuel-intensity comparison | Confirm or reject the improvement |
05 · CASE ANALYSIS
Test and verify
Align gas, steam, load, pressure and flue-gas measurements. Compare similar load regions, make a controlled change and remeasure specific fuel use.
No savings percentage or annual amount is added where the source provides only correlation and optimization direction.
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