ISE’s boiler oxygen trim control solution keeps your boiler burning right – complete combustion, no waste. An oxygen sensor continuously measures residual oxygen in the flue gas, and a PLC automatically adjusts the combustion-air fan via a VFD to hold oxygen at the optimum for each fuel and load.
At a glance:
- Cuts fuel costs by 2–10 % per year.
- Less black smoke and harmful emissions; easier compliance with Vietnam’s QCVN 19:2024/BTNMT.
- Fits new and existing boilers – no boiler replacement required.
- For rice husk, sawdust, wood chips, biomass pellets, coal, DO/FO oil and gas (LPG/CNG).
Why does a boiler need oxygen trim control?
For complete combustion a boiler needs just enough air (oxygen). In practice the air supply is set once and left alone, while fuel changes every day: husk is wetter, wood chips vary in size, load rises and falls. The boiler rarely operates at its best point – and that is the biggest opportunity for boiler fuel savings.
| Too little oxygen | Too much oxygen |
|---|---|
| Fuel does not burn completely – black smoke and soot | Excess air is heated and blown straight up the stack |
| Toxic CO is produced | Fuel is wasted heating useless air |
| Fouled tubes, faster wear, more maintenance | Fans work harder and use more electricity |
Typical symptoms: rising specific fuel consumption (kg fuel/tonne steam); smoke alternating between black and clear; high flue-gas temperature; operators constantly adjusting air by hand.
How does boiler O₂ trim control work?
| Step | Description |
|---|---|
| ① MEASURE | An oxygen sensor on the flue measures residual oxygen after combustion, continuously, every second. |
| ② COMPARE | The PLC compares it with the optimum oxygen setpoint for the fuel and boiler load. |
| ③ ADJUST | The combustion-air fan speed is raised or lowered via the VFD to bring oxygen back to setpoint – no operator intervention. |
Safety: the system only adjusts air within safe limits and never overrides boiler protection (pressure, water level, flame). If the sensor fails, the boiler automatically reverts to normal operation and alerts the operator.
Benefits of oxygen trim control
| Benefit | What it means |
|---|---|
| Fuel savings | 2–10 % lower fuel cost per year – the largest boiler operating cost |
| Electricity savings | Forced and induced draft fans run only as needed |
| Lower emissions | Less smoke and CO; easier environmental compliance (QCVN 19:2024/BTNMT) |
| Less maintenance | Less soot, cleaner tubes, longer equipment life |
| Stable operation | Independent of operator skill; steadier steam output |
| Better management | Oxygen, flue temperature and alarms on screen; data to verify savings |
How much fuel can be saved?
Example: 5 t/h rice-husk boiler, about 230 kg husk per tonne of steam, husk price 900 VND/kg.
| 1 shift (8 h/day) | 3 shifts (24 h/day) | |
|---|---|---|
| Annual fuel cost | VND 2.58 billion | VND 7.75 billion |
| 2 % saving (low) | VND 51.7 million | VND 155 million |
| 5 % saving (average) | VND 129 million | VND 388 million |
| 8 % saving (high excess air) | VND 207 million | VND 620 million |
Based on 26 days/month, 12 months/year. Indicative figures only; actual savings depend on boiler condition, fuel and operation and are determined by ISE after an on-site survey and measurement.
For continuously operating boilers the investment is usually paid back quickly from the fuel saved. ISE calculates the payback period for your boiler in the quotation.
Which boilers is it suitable for?
- Fuels: rice husk, sawdust, wood chips, biomass pellets, coal, DO, FO, gas (LPG/CNG).
- Boiler types: fire-tube, water-tube, thermal oil heaters, industrial burners.
- New boilers: integrated in the boiler control panel design.
- Existing boilers: retrofit the sensor and update the control program, reusing the existing PLC and VFDs where suitable. Short shutdown for installation.
Equipment and standards
- SST Sensing (UK) oxygen sensor – in-situ zirconia measurement in the stack, fast response, low maintenance, no sampling system.
- CE-marked electrical and control equipment complying with EU low-voltage and EMC directives.
- Design referencing European boiler and combustion standards (EN 12953 / EN 12952) and electrical safety of machinery (EN 60204-1); complies with Vietnam’s industrial emission regulation (QCVN 19:2024/BTNMT).
- Full documentation: certificate of origin (CO), quality (CQ), operating manual and acceptance report.
Implementation process
| Step | What you receive |
|---|---|
| 1. Survey & baseline measurement | Assessment of current losses and savings potential |
| 2. Proposal & quotation | Suitable solution, cost and expected payback |
| 3. Installation | Sensor installation, wiring, control program |
| 4. Commissioning & tuning | Optimum combustion at each load; before/after comparison |
| 5. Handover & training | Acceptance documents, operating instructions, warranty and technical support |
FAQ
Does the system affect boiler safety?
No. It only adjusts air within permitted limits; all boiler protection devices continue to work independently.
How long must the boiler be stopped for installation?
Most work is done while the boiler runs; only a short stop is needed to fit the sensor flange and wiring – scheduled to suit production.
Can my existing PLC and VFD be reused?
Often yes. ISE checks during the survey and reuses existing equipment where possible to reduce cost.
How do I know the savings are real?
ISE measures specific fuel consumption and combustion parameters before and after installation and records them in the acceptance report; operating data is logged on screen for your own monitoring.
Related equipment
- SST OXY-IE boiler oxygen sensor
- Tecnocontrol TS236 / TS237 zirconia oxygen sensor
- Flue gas analyzer CO, NO, NO₂, SO₂, O₂
- Vortex steam flow meter – measure tonnes of steam for fuel efficiency
- Cement kiln oxygen measurement
- Automatic boiler TDS blowdown control
Where to buy a boiler oxygen trim system?
EQUIPMENT INDUSTRIAL SOLUTION CO., LTD (ISE) – Ho Chi Minh City, Vietnam – supplies genuine a boiler oxygen trim system with technical consulting, fast quotation and on-site commissioning support across Vietnam and Southeast Asia.
Contact us: Sales +84 909 617 185 – Technical +84 979 117 185 – Email: [email protected]
