Experts in air filtration


Our in-house designed cleanNOx SNCR (selective non catalytic reduction) systems / urea skids are designed to reduce the NO and NO2 in the gas stream to meet the requirements of the Industrial Emissions Directive (formerly the Waste Incineration Directive), and BREF (the EU Best Available Techniques reference documents, or "BREFs").

BREFs represent the outcome of the ‘Sevilla process’. The majority of BREFs cover specific agro-industrial activities; such BREFs are referred to as 'sectoral BREFs'. However, there are also a number of 'horizontal BREFs' dealing with cross-cutting issues such as energy efficiency, industrial cooling systems, or emissions from storage with relevance for industrial manufacturing in general. A specific BREF was developed for the monitoring of emissions to air and water from installations under the Industrial Emissions Directive which includes nox emissions.

What are SNCR Systems?

Selective Non-Catalytic Reduction system (SNCR) solutions are used to remove harmful nitrogen oxides from hot flue gas by reaction with urea or ammonia solutions. Filter Designs use urea because of the relatively minimal COSHH issues when compared to handling ammonia slip. The urea solution is injected inside combustion chamber outlets or secondary (dwell) chambers, and is mainly used in power plants that burn biomass, municipal or clinical waste.

NOx injection can be a fine art as there are certain limitations required for optimal dosing and emission reduction which are:

  • Gas temperature range needs to be between 790°c - 1050°c
  • Ideally a temperature window of 850°c to 950°c for optimum efficiencies
  • Spray pattern and duct distribution
  • Lance design

Our SNCR Systems

We offer two different types of cleanNOx skids for our sncr systems, which are categorised as a ‘basic’ skid which uses urea solution in IBC container and needs to be integrated into a clients controls system, or the full 'prill' skid which has its own control system and uses pellets of prill, mixing with de-mineralised or towns water on site to control the nox emissions.

We are trialling a new skid to meet the the Regulation 61 notice, requiring companies to review their processes against best available techniques (BAT) and implement changes by December 3rd 2023. This test skid can dose between 4 to 400 litres per hour of urea solution. To find out more, please read this page -

By using our reagent waste calculator we can determine the quantity of urea needed and then recommend the skid to suit. It is an OPEX/CAPEX balance over the life of the plant which steers the decision with our clients.

IBC cleanNOx urea skid

This is our basic urea dosing system. It is mainly used when only small amounts of urea need to be dosed 0-20l/min. It is a small compact skid which uses IBC's (Intermediate Bulk Containers) of urea solution (pictured). The limitation is not the pumps, but at this upper rate of 20l/hr the IBC container needs changing every 48 hours.

The skid is a small stainless steel control cabinet and uses a small pump to send urea to the lance. This system can be equipped with 2 pumps and will run multiple lances if required. As the urea enters the lance, the compressed air is mixed and creates a fine mist inside the dosing chamber.

This sort of skid can be quickly retro-fitted into a plant with minimal downtime.

Prill cleanNOx urea skid

This cleanNOx urea skid is mainly used when only large amounts of urea need to be dosed 20lmin - 100l/min. This large skid uses urea prill which is mixed with demineralised or towns water to create a urea solution. This way of dosing urea is operationally cheaper than the IBC’s, and it also allows you to change the urea concentration should you have any spikes of NOx emissions.

The large skid has two built-in control panels - one to house all the pumps and dosing equipment and the other is to provide all the controls hardware and software, with its own HMI, which can be integrated into the sites SCADA system.

Again this system could also be retro fitted into a plant.

If you would like more information or if you have any enquiries about our cleanNOx range of SNCR system urea skids, or indeed any of our other products please don’t hesitate to give us a call on 01858 419104 or complete the enquiry form.

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T: 01858 419 104

E: [email protected]

Our recent Projects

We were contracted to provide 2 small Ceramic filters suitable for a small volume but with a design maximum temperature of 600°C. In addition the filters will be handling a syngas which cannot be mixed with oxygen so an alternative to compressed air would need to be used for the ‘Cleanpulse’ cleaning of the 25 Ceramic element in each of these CPC78 filters. In addition dosing of small amounts of a re-agent is required so the client also opted for a ‘Cleandose’ 25kg bag skid. Find out more about Project CAD below.

Project SRCL HH - GSA (Gas Suspension Absorber) Reactor Tower

Project BCI - Bag Filter, Gas Suspension Absorber, Reagent Dosing for a Challenging Carbon Process

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