Up-to-date Off-Gas Cleaning Systems with Selective Catalytic Reduction

conference paper

en

Flue gas (and/or off-gas in case of thermal processing of waste) cleaning system plays an important role from the environmental point of view because of more and more sweeping environmental legislation. Investment for such a system can achieve up to fifty percent of the overall unit. Reduction of nitrogen oxides (NOX) belongs to most important parts of systems like this. During combustion (incineration in case of waste treatment) process harmful emissions are released. Since the limits are stricter and stricter selective non-catalytic reduction (SNCR) becomes a not sufficient process at present. From this and other reasons selective catalytic reduction (SCR) becomes a more used off-gas cleaning system because of higher efficiency, functionality and flexibility enabling meeting the environmental requirements. A survey of using SCR in modern off-gas cleaning systems of WtE units with emphasis on applicability is shown. A comprehensive analysis is aimed at operational conditions of SCR especially the affection by inlet concentration of SO2 in off-gas and temperature of the reaction. Both of these parameters may in combination represent operating restrictions due to the formation of ammonium bisulfate and are thereby causing catalyst deactivation. The fact that a convenient integration of the SCR system into a complex off-gas cleaning system influences energy demand of the whole unit by minimizing repeating heating (re-heating), number of apparatuses (key pieces of equipment) and a consequent operational and investment costs are taken into account, analysed and designed to provide an optimum off-gas cleaning system.

Flue gas (and/or off-gas in case of thermal processing of waste) cleaning system plays an important role from the environmental point of view because of more and more sweeping environmental legislation. Investment for such a system can achieve up to fifty percent of the overall unit. Reduction of nitrogen oxides (NOX) belongs to most important parts of systems like this. During combustion (incineration in case of waste treatment) process harmful emissions are released. Since the limits are stricter and stricter selective non-catalytic reduction (SNCR) becomes a not sufficient process at present. From this and other reasons selective catalytic reduction (SCR) becomes a more used off-gas cleaning system because of higher efficiency, functionality and flexibility enabling meeting the environmental requirements. A survey of using SCR in modern off-gas cleaning systems of WtE units with emphasis on applicability is shown. A comprehensive analysis is aimed at operational conditions of SCR especially the affection by inlet concentration of SO2 in off-gas and temperature of the reaction. Both of these parameters may in combination represent operating restrictions due to the formation of ammonium bisulfate and are thereby causing catalyst deactivation. The fact that a convenient integration of the SCR system into a complex off-gas cleaning system influences energy demand of the whole unit by minimizing repeating heating (re-heating), number of apparatuses (key pieces of equipment) and a consequent operational and investment costs are taken into account, analysed and designed to provide an optimum off-gas cleaning system.

Off-gas cleaning system, Waste-to-Energy, Denitrification, SCR, Small-scale

23.08.2018

Czech Society of Chemical Engineering

Prauge, Czech republic

9781510881198

Conference Proceeding 23rd International Congress of Chemical and Process Engineering, CHISA 2018 and 21st Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction, PRES 2018

290–295

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