In this interview, industry expert Sandra Beal discusses the challenges of NOx control in industrial furnaces and how MS-DFTO technology offers a cleaner, cost-effective alternative for NOx reduction, aligning with global sustainability goals.
What are some of the key air pollution and emission control challenges from industrial furnaces?
A wide range of industries utilize high-temperature furnaces for manufacturing processes that require heat treating, melting, casting, sintering, forging or rolling. Many operate under oxygen-depleted conditions, emitting high levels of ammonia, NOX, and other nitrogen-bearing compounds. Depending on the application, the furnace exhausts may also contain tar, condensables or particulate. This presents a significant challenge for manufacturers striving to meet air quality regulations and limit carbon output while maintaining system up time.
Why are nitrogen-bearing compounds such as ammonia and NOX particularly difficult to manage from industrial furnace applications?
Emission streams that contain nitrogen-bearing hazardous air pollutants (HAPs) such as ammonia and hydrogen cyanide cannot be thermally treated in a traditional oxidizer system without forming additional NOX, making adherence to an air permit NOX level difficult. In such cases, a secondary abatement device downstream of the thermal oxidizer is required for additional NOX reduction, adding to the cost of compliance.
Image Credit: Anguil
What are some of the limitations and costs associated with traditional Selective Catalytic Reduction (SCR) systems for NOX control?
Historically, the industry has relied on Selective Catalytic Reduction (SCR) systems following traditional thermal oxidizers to achieve an additional NOx reduction. This add-on technology injects ammonia or urea into the process stream before passing it through a specialized catalyst that converts the NOX into nitrogen gas (N2) and water vapor. SCR systems are capable of a NOX reduction of up to 95 %.
However, this approach comes with significant operational burdens:
- Ammonia or urea storage, pumps, and customized control systems are needed to maintain injection rates.
- High operating costs due to chemical consumption, catalyst maintenance, and periodic catalyst replacement.
- Fresh air must be added to dilute the inert process streams to safe levels, increasing the treatment volume and leading to condensation issues.
- Additional winterization equipment to prevent freezing in cold water climates.
Can you introduce us to the Multi-Staged Direct Fired Thermal Oxidizer (MS-DFTO) and what makes it different from traditional oxidizers or SCR systems?
Anguil has provided thousands of thermal and catalytic oxidizers around the world, many of which incorporated the SCR technology. Recognizing the inefficiencies, engineers at Anguil came up with a better solution. The objective was to maintain very high levels of HAP removal, eliminate the catalyst and associated maintenance, prevent the need to dilute the stream, making it safer to operate, and eliminate the use of add-in chemicals.
This solution was a Multi-Staged Direct Fired Thermal Oxidizer (MS-DFTO) – a ground-breaking, proprietary technology that compartmentalizes the oxidation process across multiple temperature-controlled stages with varying oxygen levels, to dramatically reduce the formation of greenhouse gases. By properly staging the operating conditions and temperature profile throughout the MSDFTO, we achieve high destruction rates of the hazardous compounds and volatile organic compounds with minimal NOX formation in a single system.
Image Credit: Anguil
Why is the first stage of the MS-DFTO oxygen-starved, and what benefit does that bring in reducing NOX formation?
In the MS-DFTO system, nitrogen-bearing hazardous air pollutants (HAPs) are introduced into the first stage of the thermal oxidizer—the reducing zone—which operates at high temperatures but in the absence of oxygen. This allows the HAPs to break down without forming NOX.
Carefully controlled operating sequences maintain oxygen-starved conditions in this stage. The resulting high-temperature, oxygen-depleted gas then moves to a second stage, where it is rapidly cooled just below the oxidation temperature. In the third chamber, air is reintroduced at this moderated temperature, allowing for the complete combustion of the compounds.
The system is designed to ensure that the post-oxidation temperature remains below the threshold, typically 1800 °F (980 °C), where thermal NOX formation could occur.
In terms of efficiency and sustainability, what kinds of performance metrics has the MS-DFTO achieved in the field, particularly regarding destruction efficiency and permit compliance?
The Anguil MS-DFTO has been field-proven to achieve over 99.5 % HAP and VOC destruction efficiency while emitting NOX emissions that were a small fraction of the allowable permit value. This allows customers to surpass their NOX requirements in a single system. Many permit requirements are still being written around the secondary SCR technology but the MS-DFTO continually proves to be a more suitable option for regulators.
What kinds of cost savings—both upfront and ongoing—can facilities expect when choosing the MS-DFTO over a traditional SCR system?
This staged combustor from Anguil is changing the way industries approach greenhouse gas abatement in process furnaces. The Anguil MS-DFTO operates without the need for chemical injections or ongoing catalyst maintenance, resulting in significantly lower operational costs compared to SCR systems.
Inert process streams can remain inert throughout the system, enhancing safety by eliminating the need for upstream dilution air. Additionally, the compact design of the equipment reduces the overall footprint, which contributes to lower capital costs.
How do you see this technology shaping the future of air pollution control in industrial settings, especially as ESG and sustainability initiatives continue to grow?
As industrial facilities continue implementing Environmental, Social, and Governance (ESG) strategies to comply with regulations and improve sustainability, further carbon footprint reduction is expected.
This technology allows facilities to achieve their ESG initiatives while also reducing equipment cost, footprint, and maintenance costs.
About Sandra Beal 
With decades of experience in the selection, optimization, and design of air pollution control systems, Sandy utilizes a strategic engineering approach to apply Anguil abatement technologies throughout the world, ensuring they meet various international regulatory requirements and efficiency standards. Sandy currently manages sales for the European market while supporting the company’s business development efforts in target regions and emerging industries. She holds a Bachelor of Science in Mechanical Engineering from Rensselaer Polytechnic Institute.
This information has been sourced, reviewed and adapted from materials provided by Anguil Environmental Systems.
For more information on this source, please visit Anguil Environmental Systems.
Disclaimer: The views expressed here are those of the interviewee and do not necessarily represent the views of AZoM.com Limited (T/A) AZoNetwork, the owner and operator of this website. This disclaimer forms part of the Terms and Conditions of use of this website.