Establishing how secondary abatement could be utilised to abate emissions of NOx and unburned hydrocarbons from Spark Ignition Engine`s, combusting a range of fuels and across a range of applications and operating patterns

Descriptions

Reciprocating engines are a mature technology utilised in a wide variety of industrial and commercial stand-alone power and/or combined heat and power applications. They are a common technology on processes regulated by the Environment Agency and are being utilised for flexible gas generation across the UK to support the transition to renewable electricity supply. NOx control on reciprocating engines has principally been through primary controls on combustion which in general, is sufficient to meet emission limits specified by the Medium Combustion Plant Directive and Specified Generator regulations. Engines are however known to experience "methane slip" which can be influenced by the maintenance strategy as well as combustion control. Selective Catalytic Reduction (SCR) has mainly been used where local air quality standards require significant reduction of NOx emissions, and where it is used there is evidence that rich-burn and SCR combined can both reduce NOx emissions and increase energy output. Whilst the LCP BREF derives BAT AEL`s for Methane and Ammonia that can be applied to plant >15MWth, neither the cross media effects and constraints on using secondary abatement techniques are not particularly well quantified or documented. Both the UK`s Clean Air Strategy and the NECD require action on nitrogen dioxide and ammonia reduction. The Environment Agency are looking to engage a consultant to explore what opportunities and limitations exist for further NOx reduction on Medium Combustion Plant scale activities through rich burn combustion with SCR, reducing methane slip and increasing power output, without resulting in unacceptable cross media effects. The output from this process will also be used to support the development of the Best Available Techniques (BAT) under a future framework for UK BAT, where BAT applies, and best practice for medium sized combustion plant.