What is DeNOx
DeNOx is the process of removing nitrogen oxides (NOx) from industrial exhaust gases. NOx forms when nitrogen and oxygen react at high temperatures during combustion, drying, roasting, steaming, frying, and many other chemical processes. Left untreated, these emissions cause acid rain, smog, and serious respiratory health risks for workers and communities.
Most widely used DeNOx methods are Selective Catalytic Reduction (SCR) or Selective Non Catalytic Reduction (SNCR). These catalyst-based systems work well in power plants and cement kilns. But in food processing, chemical manufacturing and FMCG production the exhaust gas compositions are often more complex, unstable, or carrying contaminants that prevent catalysts from performing reliably.
JOA takes a different approach. Instead of relying on high temperature DeNOx methods, we focus on a low temperature DeNOx solution designed for challenging, real world exhaust conditions.
Our three stage DeNOx system uses wet scrubbing combined with ozone oxidation and packed bed absorption. Instead of relying on catalyst, a robust, low maintenance system that handles dust, recovers heat, and removes NOx in one integrated solution.
How JOA’s DeNOx System Works
STAGE 1 – Wet Scrubber for Dust Removal and Heat Recovery
The exhaust gas first enters a wet scrubber that removes particulate matter and recovers thermal energy from the hot gas stream. This stage cools the gas to the temperature range needed for effective ozone oxidation in the next stage. The recovered heat can be redirected back into the production process, effectively recycling waste heat into useful energy. By removing dust and dropping the temperature early, this stage also protects downstream equipment and ensures stable conditions for NOx treatment.
STAGE 2 – Reaction Chamber with Ozone Injection
The dust-free, cooled gas enters a reaction chamber where ozone (O₃) is injected. Ozone oxidizes the insoluble nitric oxide (NO) into higher order nitrogen oxides, primarily NO₂ and N₂O₅, which are water soluble. This is the critical step that makes wet scrubbing effective for NOx. Without oxidation, nitric oxide (NO) passes straight through a scrubber because it barely dissolves in water. The ozone dosage is controlled precisely based on the measured NOx concentration, ensuring efficient utility usage (oxygen source and electricity) and minimal residual ozone.
STAGE 3 – Packed Bed Scrubber for NOx Absorption
The oxidized gas passes through a packed bed scrubber where the water-soluble nitrogen oxides are absorbed into an alkaline scrubbing solution. The packed bed provides a large contact surface between the gas and liquid, maximizing absorption efficiency. The result is clean exhaust gas that meets emission limits, and a scrubbing liquid that can be treated or neutralized in standard wastewater processes. This final stage delivers the NOx removal performance that closes the loop on compliance.
Why Wet Scrubbing Instead of SCR or SNCR?
SCR and SNCR are well established DeNOx technologies. These are considered the “reduction” method where NOx is broken down into nitrogen and oxygen, with the help of ammonia as reduction agent. They work reliably in applications with clean, consistent, high temperature exhaust streams, such as gas turbines and large combustion plants. But in many other manufacturing environments, they fall short.
SCR catalysts are sensitive to dust, moisture, and chemical contaminants in the exhaust gas. In food and chemical manufacturing, exhaust streams often contain exactly these compounds. Catalyst poisoning, fouling, and degradation lead to declining performance, unplanned maintenance, and costly catalyst replacement. SNCR requires very high temperatures (above 850°C) and offers limited removal rates, often below 70%.
JOA’s wet scrubbing approach avoids these challenges entirely. It enables DeNOx operation at low temperatures (exhaust gas temperatures below 300°C), tolerates contaminated and variable exhaust streams, and combines NOx removal with dust extraction and heat recovery in one system.
NOx Challenges Across Industries
Every manufacturing process generates NOx differently. The temperature profile, gas composition, dust load, moisture content, and operational variability all determine what works. JOA’s DeNOx wet scrubbing approach is designed for the industries where standard solutions struggle most.
Food & Ingredients
Spray dryers, roasters, and gas fired ovens produce NOx in high moisture, dust laden exhaust streams. These conditions are hostile to SCR catalysts. JOA’s wet scrubber handles the moisture and particulates inherently, while the ozone stage tackles NOx. Heat recovery from the first stage reduces energy costs in a sector where margins are tight.
Consumer Goods
High throughput production lines in tobacco, personal care, and packaging rely on drying, curing, and thermal processes that generate NOx. Uptime is critical. JOA designs systems for continuous operation with minimal maintenance windows and remote monitoring. No catalyst replacement shutdowns mean no production interruptions.
Chemicals & Plastics
Chemical manufacturing produces exhaust with corrosive compounds, acid gases, VOCs, and particulates alongside NOx. Catalyst poisoning is a common failure mode for SCR in these environments. JOA’s wet scrubbing system tolerates corrosive conditions and can be combined with additional treatment stages for multi pollutant abatement.
Pulp & Paper
Recovery boilers, biomass boilers, and lime kilns generate NOx in humid, particulate-rich flue gas, often with corrosive components that foul or poison SCR catalysts. JOA’s wet scrubber handles moisture and dust inherently, while the ozone stage reduces NOx without catalyst dependency. Heat recovery from the first stage improves overall mill energy efficiency.
Why JOA for DeNOx
Pre-Engineering Study
Nobody dives as deep as we do. Before any design begins, we map your process conditions, emission profile, operational variability, and site constraints. This study determines whether wet scrubbing with ozone is the right approach, and exactly how to configure it for your specific exhaust emissions.
Air Technical Modelling
We identify, validate, and predict outcomes through proprietary air technical modelling. Your DeNOx system is proven before it is built. No tinkering on site. No trial and error. First time right implementation.
Process Guarantees
JOA provides written performance guarantees on emission levels. Our validated designs give you the certainty that your system will meet its targets from day one. That is peace of mind you will not get from a catalogue system supplier.
How JOA delivers your DeNOx System
JOA follows a structured four step process from first contact to long term operation. Each phase eliminates risk and ensures your system performs exactly as engineered.
Pre-Engineering Study
Design & Engineering
System Realization
DeNOx Solution FAQ
Nitric oxide (NO), which makes up about 95% of NOx in exhaust gas, is nearly insoluble in water. Ozone oxidizes NO into higher order nitrogen oxides like NO₂ and N₂O₅, which are more soluble in water. Once oxidized, these compounds can be efficiently absorbed in a packed bed wet scrubber, typically with the help of alkaline solution. The result is clean exhaust gas and a treatable liquid waste stream.
DeNOx refers to the removal of nitrogen oxides (NOx) from industrial exhaust gases. The term combines “de” (removal) with “NOx” (the chemical shorthand for nitrogen oxides, primarily NO and NO₂). Most DeNOx systems rely on reduction of NOx molecules with the help of ammonia, with (SCR, selective catalytic reduction) or without (SNCR, selective non-catalytic reduction) the use of catalysts. JOA uses an alternative approach based on ozone oxidation and wet scrubbing to achieve DeNOx at low temperature (< 100°C). We refer to this process as NOLTS (NOx Oxidation at Low Temperature and Scrubbing).
SCR catalysts are sensitive to dust, moisture, acid gases, and chemical contaminants. In food processing and chemical manufacturing, exhaust streams often contain these compounds. Catalyst poisoning and fouling lead to declining performance and costly replacements.
Wet scrubbing with ozone oxidation of NOx molecules at low temperatures combined with absorption in a wet scrubber is more versatile at tolerating contaminated gas streams. It also combines dust removal, heat recovery, and NOx abatement in one system.
Yes. This is the primary reason why JOA promotes the wet scrubbing method. Heat recovery implies cooling down the exhaust gas, which renders it incompatible with SCR or SNCR techniques.
In JOA wet scrubbing, the first stage dust-capture scrubber cools the hot exhaust gas and captures thermal energy. This recovered heat can be redirected into the production process.
What starts as a compliance investment becomes an energy efficiency gain that reduces operating costs.
