Burner Selection
Burner capacity is calculated by dividing the boiler's thermal output by its efficiency; the burner manufacturer's operating curve for capacity versus gas-side counter-pressure and fuel type should guide the correct burner selection.
BURNER SELECTION
A burner is a device that burns gas (natural gas, LPG, propane) or liquid fuels in a controlled manner, mixed with air in the ideal ratio, thereby producing heat energy.
Before selecting a burner, determine the following information from the boiler's technical file.
- Boiler thermal output
- Boiler efficiency
- Boiler gas-side counter-pressure
- Burner inlet fuel pressure
Once you have this information, calculate burner capacity using the following formula:
Burner Capacity = Boiler Thermal Output / Efficiency
EXAMPLE BURNER SELECTION
- Boiler thermal output: 600,000 kcal/h
- Boiler efficiency: 90%
- Burner capacity: 600,000 / 0.90 = 667,000 kcal/h
Calculating Fuel Flow Rate
| FUEL TYPE | NET CALORIFIC VALUE |
|---|---|
| Natural Gas | 8,250 kcal/Nm³ |
| Diesel | 10,200 kcal/kg |
| Fuel Oil | 10,200 kcal/kg |
| LPG | 11,000 kcal/kg |
| Propane | 11,100 kcal/kg |
Note
The values above are approximate.
Fuel Flow Rate = Burner Capacity / Fuel Net Calorific Value
Example Calculation for Natural Gas
- Fuel flow rate: 667,000 / 8,250
- Fuel flow rate: 80.85 Nm³/h natural gas
- Use the operating curve declared by the burner manufacturer for each burner type to help decide on burner selection. Using these curves, decide on the burner type; the curve's x-axis shows burner capacity, and the y-axis shows the boiler's gas-side counter-pressure. Determine the burner's operating range at the point where these two values intersect. To select the most suitable burner, choose one whose operating point falls in the middle portion of the curve. Remember that factors such as different fuel types and flue draft affect burner combustion efficiency; don't select a burner operating at the edge of its range; choose the next capacity size up.
- The burner's combustion head (barrel) length should be selected to match the boiler; get help from the boiler manufacturer on this.
- Remember that your system's gas pressure must be compatible with the burner's operating gas pressure range.
Frequently Asked Questions
How is burner capacity calculated?
Burner capacity is calculated by dividing the boiler's thermal output by the boiler's efficiency (Burner Capacity = Boiler Thermal Output / Efficiency). For example, for a boiler with 600,000 kcal/h thermal output and 90% efficiency, the required burner capacity is approximately 667,000 kcal/h. Fuel flow rate is then found by dividing burner capacity by the net calorific value of the fuel used.