LT and HT furnaces generate emissions streams heavily concentrated with pollutants. This makes these furnaces an ideal application for the DFTO where high destruction is required, however special design considerations should be taken to reduce operating costs and greenhouse gas emissions. The DFTO is a robust, dependable and effective destruction device for hazardous air pollutants (HAPs), volatile organic compounds (VOCs) and odorous emissions that are often discharged from Carbon Fiber processing. It is an ideal combustion technology for process streams heavily laden with pollutants and is capable of destruction efficiencies over 99%.
While these oxidizers do prevent harmful emissions from entering the atmosphere, they may also require a significant amount of supplemental fuel to achieve destruction temperatures within the system. Subsequently, they can be a large source of carbon dioxide (CO2) and nitrogen oxide (NOx) emitted. Precautions and design considerations incorporated into the standard DFTO on Carbon Fiber applications to reduce NOx emissions should include:
- Independent process and combustion air blowers to ensure the proper oxygen content during ignition
- Various process streams strategically introduced into the oxidizer to reduce the amount of by-products emitted during oxidation
- Depending on the application, oxidation oven exhaust can be used as combustion air in the DFTO, further reducing the energy demand in the oxidizer
During operation, furnace exhaust is pulled through the system with an induced draft fan configuration. Doing this increases safety by ensuring that all of the Hydrogen Cyanide emissions are drawn into the oxidizer for destruction, protecting the company’s employees and neighborhood from the potentially lethal gas leaking out of flanges, instruments, etc. This also ensures that oxygen does not migrate back to the furnaces.
Additional cost and energy saving modifications can be made to further enhance the efficiency of a DFTO. Adding a secondary heat recovery system to the oxidizer stack can provide heat for the ovens and furnaces, reducing the amount of energy input for these process devices. The recovered heat can also be used directly in the oxidizer itself by preheating combustion air. Tempered air makes the destruction device itself more energy efficient and reduces the amount of supplemental natural gas required to maintain destruction temperatures.
Learn more about Direct Fired Thermal Oxidizers with this interactive diagram.