Proven Method to Reduce NOX and SOX from Recovery Boilers

Much progress has been made globally to reduce sulfur oxides (SOx) and nitrogen oxides (NOx) emissions into the atmosphere. For global pulp and paper producers proven methods utilizing on-site equipment can now be provided to further contribute to improve the air quality.



EU Best Available Techniques reference documents (BREFs)

Harmful emissions have become a global concern and several NOx reduction initiatives are taken worldwide primarily driven by legal frameworks. New legislation regulating NOx emissions will soon put increased pressure on industrial companies. The European Union has a series of reference documents, BREFs, covering industrial activities listed in the EU’s Integrated Pollution Control Bureau (IPPC) Directive. Member states are required to take these documents into accout when determining best available techniques. It’s reasonable to believe that the pulp and paper industry once again will be at the forefront of further reducing their environmental footprint. To facilitate advances in this area, new technologies are being investigated for best available technology (BAT) for the pulp and paper industry. Outside Europe, certain provinces in China are demanding lower NOx emissions, in addition South Korea has recently implemented new legislations with lower NOx limits.

A long collaboration with Chalmers University of Technology

Nouryon has a long history of research to develop new technologies, including theoretical and practical advances with Chalmers University of Technology. This includes developing the most efficient chlorine dioxide (ClO2) De-NOx technology that reduces the day-to-day costs. “It’s well known that scientists around the world are making progress in reducing the emissions of carbon dioxide (CO2), for example through carbon capture and sequestration. Less often mentioned in the news is the important step forward in reducing NOx and SOx, like the technique from Nouryon and Valmet,” said Fredrik Normann, Professor in Energy and Emission Control at Chalmers University in Sweden.

Nouryon and Valmet offering De-NOx technology

Nouryon, a global specialty chemicals leader, and Valmet, a leading global technology provider, are now both promoting the NOx abatement technology based on ClO2, to offer the best technique for the global pulp and paper industry. As a world leading supplier of ClO2 technology, with more than 90% of new production units supplied globally, Nouryon can now also give the pulp and paper customers a front edge technology to make major advances in pollution abatement. “Nouryon’s know-how about safe and efficient traditional ClO2 delivery and technological developments with gaseous solutions are an important factor in economic feasibility,” said Rikard Papp Global Marketing Manager Renewable Fibers at Nouryon.

Valmet’s De-NOx scrubbers for recovery boilers, employing ClO2, have been proven successful in achieving a significant reduction in NOx and SOx emissions. On average, both are cut by 90% or more, compared with current global practices at pulp and paper mills. The first De-NOx scrubber has run continuously for the last six years at Sun Paper in Shandong Province, China. "Many years of development work and testing for NOx scrubbers gave us advantages on behalf of Sun Paper. We were up and running ahead of schedule, and meeting strict emission targets right from the start,” commented Lari-Matti Kuvaja, Manager from Valmet’s Environmental Systems Unit.

Nouryon and Valmet are working together to advance gains in NOx and SOx reductions in the global pulp and paper industry. Rikard Papp from Nouryon and Lari-Matti Kuvaja from Valmet are leading the effort.

Finding the most suitable solution

Technically, it’s possible to use ClO2, ozone, and hydrogen peroxide as an NOX oxidizing agent in the flue gases. After careful consideration and internal evaluation of the costs and operability, Sun Paper decided to choose the ClO2-based NOx scrubber process. "Using ClO2 as the scrubber oxidizing agent at chemical pulp mills has several advantages. The chemical is already available at the mill site as it is used for bleaching. It is inexpensive compared to other oxidizing media, and the ClO2 turns into chlorides during the oxidation process, which has no effect on the environment," explained Kuvaja.

"Valmet De-NOx using ClO2 is an ideal fit for us," said Hongjin Liang, Mill Manager of the Yanzhou Kraft Pulp Mill from Sun Paper. “Their team has helped us reduce NOx safely and efficiently. The units run well on a continuous basis.”

Available De-NOx pilot plant and engineering expertise

Concerning potential projects, Rikard Papp remarked, “Nouryon ClO2 engineering expertise can help expand plant capacity by debottlenecking existing processes, if ClO2 capacity is limited. The application of both gaseous and aqueous ClO2 is possible and a De-NOx pilot plant is available for pulp mills which want to try this technology.”

Read more about Nouryon’s ClO2 engineering and De-NOx technologies and Valmet’s multi-emission control scrubber:

The Valmet flue gas scrubber employing chlorine dioxide to reduce NOx and SOx emissions. (Image courtesy of Valmet)

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If you have questions about chlorine dioxide based De-NOx technology, please contact our technical experts. We look forward hearing from you.

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