About the Client
The client operates a large continuous‑process manufacturing site in Western Europe, producing high‑tonnage fertilizer products. The plant handles significant quantities of corrosive and dusty materials.
The site’s licence to operate is closely linked to its ability to reliably control particulate and acid‑gas emissions to the outside, with the client targeting emission levels of ≤ 5 mg/m³.
Challenge
Since the domestic area gets closer and closer to the factory, emission output legislation changes. In order to keep the license to operate the plant must significantly reduce emissions, targeting dust emissions of ≤ 5 mg/Nm³.
During production several high‑throughput drying drums discharge into a shared exhaust. The dryers generate a dense mixture of fine dust, moisture and corrosive HCl, HF, NH3 and Sox gases as is common in the fertilizer industry. The existing cyclone and wet scrubber are tightly embedded in the existing structures, leaving very little space to modify equipment or routing.
Domestic Encroachment: Housing areas coming closer to the factory
Emission Legislation: Cut dust emissions to ≤ 5 mg/m³, reduce HCl and HF
Exhaust Mixture: High sticky dust load with high humidity corrosive gas.
Limited Footprint: New design needs to fit in current setup
Approach
When a standard equipment is chosen, manufacturers gamble with securing performance. As the existing system at this site was underperforming, they faced some excessive emissions, complex exhaust mixtures and a limited available footprint for new systems. That’s why they contacted JOA, which came with a proven approach:
Pre-engineering study:
To start, JOA conducted a Pre-Engineering Study to assess the on-site challenges, beginning with the existing wet scrubber. During this phase, the team performed an in-depth assessment to secure future compliance with dust and acid gas emissions at ≤ 5 mg/m³. The full dryer–cyclone–scrubber chain was mapped, and a conservative design basis was defined for hot, humid exhaust streams containing dust and HCl/HF/NH₃/SOₓ.
- On‑site measurements around cyclones and scrubber (flow, Temperature, Relative Humidity, pressure, emission levels).
- Evaluation showing the existing cyclones are highly effective and can be retained as the first separation stage.
*Concept conclusion: add a dry dust filter, gas cooling and a high‑efficiency acid‑gas scrubber to meet future limits.
Design & Engineering:
Based on the study, JOA developed a tailored concept and translated it into a complete technical design: existing cyclones, JOA Dust Filter, exhaust‑gas cooler, 2‑stage Glassfibre Reinforced Plastic (GRP) packed‑bed scrubber for HCl/HF. Air‑technical modelling (GCM) and process simulations were used to balance the system and respect wastewater constraints.
- Sizing of filter, cooler, scrubber, fan and headers for the defined flow/temperature envelope and required pressure after the cyclones.
- Material selection for corrosive, hot, humid service.
- PFD, layout and automation concept, including safeguards against overheating/condensation and reserved space/capacity for future odor abatement and heat recovery.
System Realization:
The realization phase replaced the old scrubber by tying in after the three cyclone headers into a new filter building, then routed cooled and scrubbed gas via a new extraction fan to the existing stack. The modular ducting and equipment layout allowed phased implementation and future upgrades.
- GRP ducting with strategically placed bypass options for filter, cooler and scrubber.
- Scrubber recirculation skids, instrumentation and controls for stable performance under varying product recipes.
- Layout and capacities dimensioned to keep emissions within the permit and to accommodate future odor treatment and heat‑recovery integration.
Outcome & Conclusion
Based on the Pre‑Engineering Study and detailed air technical modelling, a new multi‑stage emission control solution was developed around the existing cyclones, complemented by a dust filter, gas cooler and two‑stage packed‑bed scrubber, completed with a new fan.
This configuration enables the plant to meet stringent limits for dust and acid gases while maintaining stable and predictable operation of the dryer line.
The solution also gives the option for future heat recovery from the exhaust stream, turning previously wasted thermal energy into energy savings and CO₂ reduction, while leaving room to add an odor abatement stage at a later point if required.
Key results:
- High dust and acid gas removal efficiencies, keeping stack emissions within current and expected future permit levels.
- Re‑use of the existing cyclone stage, minimizing process modifications while closing the gap to <5 mg/Nm³ dust at stack (design basis).
- Robust, maintainable layout in corrosion‑resistant materials (filter, cooler, scrubber and fan) supporting long‑term reliability.
- Minimum water consumption
