Combustion of fuel oil in power boilers with overpressure and under pressure

Purpose

Experimental study and comparison of operating parameters of power boilers during fuel oil combustion under pressurization versus draft conditions to increase fuel oil utilization efficiency (boiler efficiency improvement) and reduce hazardous nitrogen oxide emissions.

Methods

The study involved full-scale experimental testing on industrial boilers TGM-84B and TGME-464. The boiler efficiency was evaluated using the heat-loss (indirect) balance method. To verify the results, an integrated set of interrelated methods was applied, including gas analysis of nitrogen, sulfur, and carbon oxide emissions, optical flame pyrometry, and a comparative analysis of the auxiliary energy consumption of draft fans and blowers.

Results

Fuel oil combustion is characterized by high temperatures in the flame core and elevated nitrogen oxide emissions, while the necessity to protect downstream heating surfaces from sulfuric acid corrosion requires maintaining a higher flue gas temperature, which reduces boiler efficiency compared to gas-fired operation. One method to enhance fuel oil utilization efficiency is its combustion in pressurized boilers, where positive air pressure is maintained inside a gas-tight furnace, completely eliminating cold air infiltration through the casing defects. In pressurized boilers, the evacuation of combustion products occurs due to the overpressure in the furnace chamber and the natural draft of the stack.

Conclusion

As a result of the experimental study of M100 fuel oil combustion in the TGME-464 boiler under pressurization and in the TGM-84B boiler under draft conditions, an increase in boiler efficiency by 0,33% and a reduction in nitrogen oxide emissions were obtained. The specific electricity consumption for forced and induced draft under pressurization is two times lower than under draft conditions.