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Flameless Combustion Technology

The WTE-Tech Superflox Flameless Combustion technology is based on full hydrocarbon combustion under auto-oxidation conditions. This technology is robust and effective at very Low Heating Values (LHV) of the off-gas and shows robust operation at stable temperatures ensuring full hydrocarbon combustion, full oxidation of pollutant components (S, N and other) and with zero NOx formation.

Applications of Flameless Combustion include waste gas or fuel gas utilization in the process industry, thus covering emission and energy efficiency issues in industry segments such as coal gasification, carbon black industry, power generation, steel industry, (petro) chemical industry, refining, oil and gas production upstream.

Direct combustion disadvantage

Direct combustion disadvantage

Waste gas streams are often produced at low energy content (Lower Heating Values or LHV), insufficient to maintain direct flame based combustion without addition of other combustible gases. Direct combustion solutions therefore create a number of problems:

  1. Additional combustible gas requirement (NG, LPG or other) resulting in additional cost and at expense of additional CO2 emissions;
  2. High temperature combustion zone (temperatures above 1400 °C) resulting in, amongst others, NOx formation;
  3. Incomplete combustion resulting in formation of contaminants like CO, SOx, particulate matter (PM) etc.

Pollution and waste-of-energy

The problems the WTE-Tech Flameless Combustion targets to solve are:

  1. VOC emissions through waste gases being sent to air without further treatment;
  2. Emissions of contaminated fuel gases resulting from incomplete combustion and/or NOx formation;
  3. Waste of energy due to lack of energy recovery on LHV waste gas streams

Flameless Combustion – The Solution

Flameless Combustion (FC) is a mode of auto oxidation in which oxidation takes place above auto-ignition temperature (650-700 °C) and below adiabatic flame based combustion temperatures (1950-2000 °C).

Under conditions of FC any hydrocarbon containing steam is intensively mixed with the required amount of combustion air (mixing only at the furnace inlet, no pre-mixing). In the combustion chamber, kept at temperatures above auto-ignition temperature a homogeneous oxidation reaction takes place in the gas phase, utilizing the full volume of the combustion chamber. Preferably temperatures are kept at a level of 900- 1200 °C, in any case at temperatures below 1400 °C to avoid NOx formation.

Technology

1. Key design parameters

WTE-Tech has selected E-Flox burners and controls as basis for the new technology development for waste gas utilization for the following reasons:

  • Separated feed streams fuel gas and combustion air;
  • No pre-mixing of fuel gas and combustion air;
  • Minimum gas rates at the burner tip required to meet mixing requirements;
  • Pre-heat of furnace above auto-ignition temperature (650-700 °C) required;
  • Reduced oxygen level in the combustion chamber (3-10 %v);
  • Compact design of combustion chamber;
  • Inventive burner design for max heat recovery and overall energy efficiency.

2. Operational performance

WTE-Tech unit operations are characterized by:

  • Intensive mixing of the separately introduced gas streams in the combustion chamber;
  • Effective and homogeneous combustion of all hydrocarbons available;
  • Flat temperature (<1400 °C) and concentration profiles through combustion chamber (see figure);
  • Wide concentration range – 1,5-15 %v;
  • Wide range of hydrocarbons can be applied;
  • Non-hydrocarbons are fully oxidized (H, S, N and other);
  • Reduced oxygen levels are applied, no interference with Lower Explosion Limits, LEL;
  • High robustness from safeguarding perspective;
  • High overall efficiency and heat recovery.

Industrial Applications and References

The technology has been applied in many industrial fields, with over 60 projects in Europe and over 80 projects in China in various industries:

Steel industry and tempering heat treatment

  • Carburizing and tempering furnaces
  • Annealing furnaces
  • Galvanizing lines
  • Forging furnaces
  • Tube furnaces

Chemical industry

  • Rotary kiln

Ceramic industry

  • Indirect heated furnaces

WTE Tech and Hofung Engineering

WTE-Tech BV is a company focused on development of new proprietary technology for waste gas utilization and energy efficiency in the process industry. The technology results into significant CO2 emission reduction and emission reductions of a.o. SOx and NOx below regulatory boundaries and transforms waste gas into electricity or steam without additional gas sourcing for flaring. Activities include technology licensing, new development, engineering and design, implementation, project and asset management, and support in investment and finance.

Hofung Engineering is the exclusive engineering partner and official sublicensor of WTE-Tech for Flameless Combustion technology.