Techn. Hochsch., Diss.--Aachen, 2006.

An integrated NOx adsorption-reduction process has been proposed in this study for the treatment of flue gases under lean-burn conditions by decoupling the adsorption and reduction into two different zones. The hypothesis has then been validated in a novel internal circulating fluidized bed. The adsorption and reaction performance of Fe/ZSM-5 for the selective catalytic reduction (SCR) of NOx with propylene was investigated in a fixed bed reactor. The fine Fe/ZSM-5(Albemarle) catalyst showed reasonable NOx adsorption capacity, and the adsorption performance of the catalyst was closely related to the particle size and other catalyst properties. Fe/ZSM-5 catalyst was sensitive to the reaction temperature and space velocity, and exhibited acceptable activity when O₂ concentration was controlled at a low level. Water in the flue gas was found to slightly enhance the reactivity of Fe/ZSM-5(Albemarle), while the presence of CO₂ showed little effect. SO₂ severely inhibited the reactivity of Fe/ZSM-5(Albemarle), and the deactivated catalyst could be only partially regenerated. Configurations of the reactor influenced the hydrodynamic performance significantly in a cold model internal circulating fluidized bed (ICFB) reactor. For all configurations investigated, the high gas bypass ratio from the annulus to draft tube (RAD) and low draft tube to annulus gas bypass ratio (RDA) were observed, with the highest RDA associated with the conical distributor which showed the flexible and stable operation over a wide range of gas velocities. Solids circulation rates increased with the increase of gas velocities both in the annulus and the draft tube. Gas bypass was also studied in a hot model ICFB reactor. The results showed that the orientation of perforated holes on the conical distributor could be adjusted to reduce RAD and/or enhance RDA. Coarse Fe/ZSM-5(PUC) and fine Fe/ZSM-5(Albemarle) catalysts were used in an ICFB and a conventional bubbling fluidized bed to test the NOx reduction performance. Coarse Fe/ZSM-5(PUC) catalyst showed poor catalytic activity, while fine Fe/ZSM-5(Albemarle) catalyst exhibited promising NOx reduction performance and strong inhibiting ability to the negative impact of excessive O₂ in the ICFB reactor, proving that the adsorption-reduction two-zone reactor is effective for the NOx removal from oxygen-rich combustion flue gases.

An integrated NOx adsorption-reduction process has been proposed in this study for the treatment of flue gases under lean-burn conditions by decoupling the adsorption and reduction into two different zones. The hypothesis has then been validated in a novel internal circulating fluidized bed. The adsorption and reaction performance of Fe/ZSM-5 for the selective catalytic reduction (SCR) of NOx with propylene was investigated in a fixed bed reactor. The fine Fe/ZSM-5(Albemarle) catalyst showed reasonable NOx adsorption capacity, and the adsorption performance of the catalyst was closely related to the particle size and other catalyst properties. Fe/ZSM-5 catalyst was sensitive to the reaction temperature and space velocity, and exhibited acceptable activity when O₂ concentration was controlled at a low level. Water in the flue gas was found to slightly enhance the reactivity of Fe/ZSM-5(Albemarle), while the presence of CO₂ showed little effect. SO₂ severely inhibited the reactivity of Fe/ZSM-5(Albemarle), and the deactivated catalyst could be only partially regenerated. Configurations of the reactor influenced the hydrodynamic performance significantly in a cold model internal circulating fluidized bed (ICFB) reactor. For all configurations investigated, the high gas bypass ratio from the annulus to draft tube (RAD) and low draft tube to annulus gas bypass ratio (RDA) were observed, with the highest RDA associated with the conical distributor which showed the flexible and stable operation over a wide range of gas velocities. Solids circulation rates increased with the increase of gas velocities both in the annulus and the draft tube. Gas bypass was also studied in a hot model ICFB reactor. The results showed that the orientation of perforated holes on the conical distributor could be adjusted to reduce RAD and/or enhance RDA. Coarse Fe/ZSM-5(PUC) and fine Fe/ZSM-5(Albemarle) catalysts were used in an ICFB and a conventional bubbling fluidized bed to test the NOx reduction performance. Coarse Fe/ZSM-5(PUC) catalyst showed poor catalytic activity, while fine Fe/ZSM-5(Albemarle) catalyst exhibited promising NOx reduction performance and strong inhibiting ability to the negative impact of excessive O₂ in the ICFB reactor, proving that the adsorption-reduction two-zone reactor is effective for the NOx removal from oxygen-rich combustion flue gases.

Techn. Universiẗat, Diss., 2004--Kaiserslautern.

An integrated NOx adsorption-reduction process has been proposed in this study for the treatment of flue gases under lean-burn conditions by decoupling the adsorption and reduction into two different zones. The hypothesis has then been validated in a novel internal circulating fluidized bed. The adsorption and reaction performance of Fe/ZSM-5 for the selective catalytic reduction (SCR) of NOx with propylene was investigated in a fixed bed reactor. The fine Fe/ZSM-5(Albemarle) catalyst showed reasonable NOx adsorption capacity, and the adsorption performance of the catalyst was closely related to the particle size and other catalyst properties. Fe/ZSM-5 catalyst was sensitive to the reaction temperature and space velocity, and exhibited acceptable activity when O₂ concentration was controlled at a low level. Water in the flue gas was found to slightly enhance the reactivity of Fe/ZSM-5(Albemarle), while the presence of CO₂ showed little effect. SO₂ severely inhibited the reactivity of Fe/ZSM-5(Albemarle), and the deactivated catalyst could be only partially regenerated. Configurations of the reactor influenced the hydrodynamic performance significantly in a cold model internal circulating fluidized bed (ICFB) reactor. For all configurations investigated, the high gas bypass ratio from the annulus to draft tube (RAD) and low draft tube to annulus gas bypass ratio (RDA) were observed, with the highest RDA associated with the conical distributor which showed the flexible and stable operation over a wide range of gas velocities. Solids circulation rates increased with the increase of gas velocities both in the annulus and the draft tube. Gas bypass was also studied in a hot model ICFB reactor. The results showed that the orientation of perforated holes on the conical distributor could be adjusted to reduce RAD and/or enhance RDA. Coarse Fe/ZSM-5(PUC) and fine Fe/ZSM-5(Albemarle) catalysts were used in an ICFB and a conventional bubbling fluidized bed to test the NOx reduction performance. Coarse Fe/ZSM-5(PUC) catalyst showed poor catalytic activity, while fine Fe/ZSM-5(Albemarle) catalyst exhibited promising NOx reduction performance and strong inhibiting ability to the negative impact of excessive O₂ in the ICFB reactor, proving that the adsorption-reduction two-zone reactor is effective for the NOx removal from oxygen-rich combustion flue gases. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

My master’s thesis deals with the problems of NOx abatement that are included in flue gases. The accent is put on combined flue gases treatment throug ceramic candles, where the deposited catalyst enables NOx reduction throug the method of selective catalytic reduction. The main aim of my master’s thesis has been the design of experimental equipment for current removal of gas pollutants (dioxins, VOC and NOx) and fly-ash on catalitic ceramic candle. Design of experimental equipment consisted in the calculation of basic characteristics like pipe diameter, filtration chamber diameter, heater performance etc. During the design it was necessary to build pressure drop model that was split into head loss of ceramic candle and piping system. For the evaluation of experimentally measured data and for description of ongoing catalytic reaction in various operating conditions was made prediction model of catalytical filter. The last chapter deals with planned experimental testings.

Stickoxide NOx werden von Menschenhand in verschiedenen Verbrennungsprozessen emittiert. Die selektive katalytische Reduktion mit Ammoniak (NH3-SCR) hat sich weltweit als wichtigste Methode zur Minderung von NOx-Emissionen etabliert. Derzeit erhältliche Katalysatoren für die NH3-SCR werden bei Temperaturen unterhalb von 473 K stark in Gegenwart von Wasser desaktiviert, welches unvermeidbar in Abgasen aus der Verbrennung von organischen Stoffen enthalten ist. In dieser Arbeit werden drei verschiedene Arten der Modifikation von SCR-Katalysatoren diskutiert, die eine gesteigerte H2O-Resistenz bewirken. Eine Methode ist die Verwendung von mischoxidischen Trägermaterialien, eine Andere ist eine mischoxidische aktive Komponente und schließlich eine postpräparative Oberflächenmodifikation mit Organosilylgruppen. Die Katalysatoren wurden sowohl auf ihre katalytische Aktivität als auch auf ihre adsorptiven, redox und andren Oberflächeneigenschaften untersucht. Die Wechselwirkungen zwischen H2O und der Katalysatoroberfläche wurden mittels temperaturprogrammierter Desorption (TPD), isothermaler Adsorption bei erhöhtem Druck und einer gravimetrischen Methode untersucht. Besonders die H2O-TPD hat sich als eine leistungsstarke Methode für diesen Zweck herausgestellt. Jede der drei Modifikationen bewirkte eine Verminderung der Wechselwirkungen zwischen H2O und der Katalysatoroberfläche. Neben einer allgemeinen Erhöhung der Aktivität eines SCR-Katalysators, wird die gezielte Verminderung dieser Wechselwirkungen als Schlüsselrolle in der Entwicklung von Katalysatoren mit verbesserter H2O-Resistenz angesehen. Jedoch gibt es zur Zeit kaum Publikationen, die diesen Zusammenhang behandeln. Daneben wurde auch die Bildung von N2O als ungewünschtes Nebenprodukt bei der SCR-Reaktion untersucht. Dessen Treibhauspotential entspricht ungefähr dem 300-fachen von CO2. Die Verwendung von einem mischoxidischem Trägermaterial kann die Freisetzung von N2O während der SCR verringern, was größtenteils auf die Unterdrückung der Bildung nach einem ER-Mechanismus zurückgeführt wurde. Auch die N2O-Bildung wird in vielen Publikationen über die Entwicklung von SCR-Katalysatoren nicht betrachtet.:0.1 Abbreviations 0.2 Symbols 1 Introduction and Objectives 2 Literature Overview 2.1 NH3-SCR 2.1.1 NH3-SCR Catalysts 2.1.2 Mechanisms of NH3-SCR Reaction 2.1.3 N2O-Formation under SCR-Conditions 2.2 Deactivation of NH3-SCR Catalysts 2.2.1 Deactivation by H2O 2.2.2 Deactivation by SO2 2.3 Low-Temperature NH3-SCR 2.3.1 Requirements and Challenges of LT-SCR 2.3.2 LT-SCR Catalysts 2.4 Silylation of Metal Oxide Surfaces 3 Experimental Section 3.1 Catalyst Preparation 3.1.1 Support Modification with Different Metal Oxides 3.1.2 Deposition of Active Component 3.1.3 Catalyst Modification with Organosilyl Groups 3.2 Catalyst Characterization 3.2.1 Texture Analysis 3.2.2 Phase Analysis 3.2.3 Elementary Analysis 3.2.4 Adsorption Properties 3.2.5 Surface Spectroscopy 3.2.6 Redox Properties 3.3 Catalytic Experiments 4 Results and Discussion 4.1 Impact of Mixed-Oxide Support on Catalyst Activity 4.1.1 Impact in Dry Gas-Flow: Reduced N2O-Emission 4.1.1.1 Catalytic Activity 4.1.1.2 Catalyst Characterization 4.1.1.3 Discussion 4.1.2 Impact in Wet Gas-Flow: Higher H2O-Resistance 4.1.2.1 Catalytic Activity 4.1.2.2 Catalyst Characterization 4.1.2.3 Discussion 4.1.3 Summary of SiO2-Impact 4.2 Mn-Ce Mixed-Oxide as Active Component 4.2.1 Catalytic Activity 4.2.2 Catalyst Characterization 4.2.3 Discussion and Summary 4.3 Catalyst Modification with Organosilyl Groups 4.3.1 Stability of Organosilyl Groups 4.3.2 Impact of Organosilyl Modification on H2O-Adsorption 4.3.3 Impact of Organosilyl Modification on Catalytic Activity in Pre- and Absence of H2O 4.3.3.1 Catalytic Activity 4.3.3.2 Catalyst Characterization 4.3.3.3 Discussion 4.3.4 Summary of Organosilyl Modification 4.4 Discussion on the Investigation of H2O-Adsorption 5 Conclusions and Outlook 5.1 Conclusions 5.2 Outlook 6 References 7 Appendix 7.1 Evaluation of H2O-Sorption Data through BET-Theory 7.2 Evaluation of Kinetic SCR Investigation 7.3 Calculation of the Average Oxidation State of Mnz+ from H2-TPR 7.4 Calculation of the Surface-Density of Mn 7.5 Supplementary Data 7.6 Scientific Contributions 7.7 Curriculum Vitae 8 Summary (german) 8.1 Einleitung 8.2 Experimentelles 8.3 Ergebnisse und Diskussion 8.3.1 Einfluss eines mischoxidischen Trägermaterials auf die katalytische Aktivität 8.3.2 Mn-Ce-Mischoxide als aktive Komponente 8.3.3 Modifikation von Katalysatoren mit Organosilyl-Gruppen 8.4 Schlussfolgerungen / Nitrogen oxides NOx were anthropogenically emitted by various combustion processes. The selective catalytic reduction with ammonia (NH3-SCR) has been established worldwide as the most important technique for the abatement of NOx . Currently available catalysts for NH3-SCR become strongly deactivated at temperatures below 473 K in presence of H2O which is unavoidable present in the exhaust gas arising from the combustion of organic matter. In this work three different kinds of a modification of an SCR-catalyst were discussed that cause a higher H2O-resistance. One is the application of a mixed-oxide support material, the other is a mixed-oxide active component and finally a post-preparative surface modification with organosilyl-groups. The catalysts were assessed for their catalytic activity as well as their adsorptive, redox and other surface properties. The interactions between H2O and the catalyst surface were investigated by means of temperature programmed desorption (TPD), isothermal adsorption at elevated pressure and a gravimetric method. Especially the H2O-TPD turned out to be a powerful method for this purpose. Each of the three modifications caused a reduction in the H2O-catalyst interactions. Beside a general increase of the activity of an SCR-catalyst, the purposeful reduction of these interactions is considered to play a key role in the development of catalysts with an enhanced H2O-resistance. However, there is a lack of publications that deal with this correlation. Also the formation of the unwanted by-product N2O was investigated. Its global warming potential is about 300-times that of CO2. The application of a mixed-oxide support can reduce the release of N2O during SCR which was attributed mainly to the suppression of the ER-type formation pathway. Also the N2O-formation is not considered in many publications dealing with the development of SCR-catalysts.:0.1 Abbreviations 0.2 Symbols 1 Introduction and Objectives 2 Literature Overview 2.1 NH3-SCR 2.1.1 NH3-SCR Catalysts 2.1.2 Mechanisms of NH3-SCR Reaction 2.1.3 N2O-Formation under SCR-Conditions 2.2 Deactivation of NH3-SCR Catalysts 2.2.1 Deactivation by H2O 2.2.2 Deactivation by SO2 2.3 Low-Temperature NH3-SCR 2.3.1 Requirements and Challenges of LT-SCR 2.3.2 LT-SCR Catalysts 2.4 Silylation of Metal Oxide Surfaces 3 Experimental Section 3.1 Catalyst Preparation 3.1.1 Support Modification with Different Metal Oxides 3.1.2 Deposition of Active Component 3.1.3 Catalyst Modification with Organosilyl Groups 3.2 Catalyst Characterization 3.2.1 Texture Analysis 3.2.2 Phase Analysis 3.2.3 Elementary Analysis 3.2.4 Adsorption Properties 3.2.5 Surface Spectroscopy 3.2.6 Redox Properties 3.3 Catalytic Experiments 4 Results and Discussion 4.1 Impact of Mixed-Oxide Support on Catalyst Activity 4.1.1 Impact in Dry Gas-Flow: Reduced N2O-Emission 4.1.1.1 Catalytic Activity 4.1.1.2 Catalyst Characterization 4.1.1.3 Discussion 4.1.2 Impact in Wet Gas-Flow: Higher H2O-Resistance 4.1.2.1 Catalytic Activity 4.1.2.2 Catalyst Characterization 4.1.2.3 Discussion 4.1.3 Summary of SiO2-Impact 4.2 Mn-Ce Mixed-Oxide as Active Component 4.2.1 Catalytic Activity 4.2.2 Catalyst Characterization 4.2.3 Discussion and Summary 4.3 Catalyst Modification with Organosilyl Groups 4.3.1 Stability of Organosilyl Groups 4.3.2 Impact of Organosilyl Modification on H2O-Adsorption 4.3.3 Impact of Organosilyl Modification on Catalytic Activity in Pre- and Absence of H2O 4.3.3.1 Catalytic Activity 4.3.3.2 Catalyst Characterization 4.3.3.3 Discussion 4.3.4 Summary of Organosilyl Modification 4.4 Discussion on the Investigation of H2O-Adsorption 5 Conclusions and Outlook 5.1 Conclusions 5.2 Outlook 6 References 7 Appendix 7.1 Evaluation of H2O-Sorption Data through BET-Theory 7.2 Evaluation of Kinetic SCR Investigation 7.3 Calculation of the Average Oxidation State of Mnz+ from H2-TPR 7.4 Calculation of the Surface-Density of Mn 7.5 Supplementary Data 7.6 Scientific Contributions 7.7 Curriculum Vitae 8 Summary (german) 8.1 Einleitung 8.2 Experimentelles 8.3 Ergebnisse und Diskussion 8.3.1 Einfluss eines mischoxidischen Trägermaterials auf die katalytische Aktivität 8.3.2 Mn-Ce-Mischoxide als aktive Komponente 8.3.3 Modifikation von Katalysatoren mit Organosilyl-Gruppen 8.4 Schlussfolgerungen

Lillesjöverket är ett kraftvärmeverk som drivs av Uddevalla Kraft där förbränning sker av brännbart hushållsavfall och verksamhetsavfall. Vid förbränningen bildas kväveoxider så kallat NOX som renas bort med en metod som heter Selectiv Catalytic Reduction (SCR). I detta arbete har kvävereningsreningsprocessens effektivitet studerats i syfte att undersöka om Lillesjöverket kan minska deras miljöpåverkan samt minska deras kostnader för inköp av ammoniak eller minska kostnaden för utsläpp av NOX. Lillesjöverket använder en automatiserad dosering av ammoniak utifrån en förprogrammerad formel för att uppnå en effektiv och säker rening vid eventuella driftförändringar. Ett börvärde väljs utifrån en önskad halt av NOX som släpps ut, så kallad Set Point. I nuläget använder Lillesjöverket en Set Point på 10 mg NOX/Nm3 torr gas. I arbetet jämförs den automatiserade doseringen av ammoniak mot en manuell dosering av ammoniak. Driftfallen som har testkörts på systemet resulterade att en ammoniakdosering under cirka 50,9 l/h medförde en effektivare och bättre utnyttjande av ammoniaken med automatisk dosering.  En dosering över cirka 50,9 l/h visade på att manuell dosering var effektivare. Driftfallet som visade på effektivast rening och bäst nyttjande av doserad ammoniak var driftfallet med manuell inställning på 52 l/h. Detta resulterade i ett utsläpp på 1,33 mg NOX/Nm3 torr gas och ett ammoniumutsläpp på 4,95 mg/l. Ekonomiskt innebär detta en total kostnad på 998 tkr/år, viket är en besparing på 204 tkr/år jämfört med dagens driftläge. Det är svårt att motivera en manuell dosering av ammoniak på grund av att driftförhållandet varierar. En manuell dosering kräver ständig övervakning för att minimera risken för ammoniakslip samt för höga halter ammonium i vattnet vid större förändringar i driften.  Utifrån detta arbete konstateras att det inte går att rekommendera någon optimal ammoniakdosering då driftförhållandena konstant ändras med tiden. Enligt resultaten kan Lillesjöverket sänka sin Set Point från 10 till 8 vid ett driftläge då det inte utvinns någon energi från kondensatorn, utan att riskera en kraftigt förhöjd ammoniumhalt eller ammoniakslip. Ekonomiskt innebär detta en besparing på 39 tkr/år från nuvarande Set Point. Ett driftläge då det utvinns energi föreslås att Lillesjöverket ändrar till Set Point 6 eller Set Point 3, vilket skulle ge en besparing på 56 tkr/år eller 133 tkr/år. / Lillesjöverket is a combined heat and power plant operated by Uddevalla Kraft, which combusts household waste and commercial waste. At the combustion nitrogen oxides, NOX are formed and is purified by a method called Selective Catalytic Reduction (SCR). This project purpose has been to analyze if Lillesjöverket can reduce their environmental impact and reduce their costs of purchasing ammonia or reduce the cost of NOX emissions.  Lillesjöverket has an automated dosage of ammonia based on a preprogramming formula to achieve an efficient and safe reduction of NOX in case of any changes in operating condition. Where you choose a desired NOX level, a so-called Set Point. Currently Lillesjöverket use Set Point 10 mg NOX/Nm3 dry gas. In this project, the automated dosage of ammonia is compared to a manual dosage of ammonia. The operating cases that have been tested on the system resulted in a dosage of ammonia below about 50,9 l/h, which resulted in a more efficient and better use of the ammonia with automatic dosing. While dosing above 50,9 l/h showed that manual dosing was more effective. The operating case that showed the most effective purification and best use of ammonia, was the operating case with a 52 l/h manual dosing which resulted in 1,33 mg NOX/Nm3 dry gas and an ammonia emission of 4,95 mg/l. Economically, this resulting in a total cost of 998 000 SEK/year, a saving of 204 000 SEK/year compared to current operating mode. It is difficult to justify a manual dosage of ammonia due to the operating mode, and a manual dosage would then require constant monitoring to remove the risk of ammonia slip and high levels of ammonium in the water. Based on this project, it can be noted that no optimal ammonia dosage can be recommended as operating conditions change constantly. According to the results can Lillesjöverket lower the Set Point from 10 to 8, which would save about 39 000 SEK/year at an operating mode when no energy is extracted from the capacitor without risking a high level of ammonium or ammoniaslip. When extracting energy, it is suggested that Lillesjöverket switches to Set Point 6 or Set Point 3, which would save about 56 000 SEK/year or 133 000 SEK/year.

No description available.

Avfallsförbränning kan användas för att minska volymen hos avfallet, destruera farligt avfall och utvinna energi för el- och värmeproduktion. Umeå Energis kraftvärmeverk Dåva 1 förbränner hushålls- och verksamhetsavfall. Vid förbränningen bildas bland annat kväveoxider (NOx) vars utsläpp regleras dels av Förordning SFS 2013:253 om förbränning av avfall och dels av Lagen (1990:613) om miljöavgift på utsläpp av kväveoxider (NOx) vid energiproduktion (kväveoxidavgiften). Dåva 1 använder selektiv icke-katalytisk rening (SNCR) med ammoniakinsprutning för att rena rökgaserna från NOx. En del av ammoniaken förblir oreagerad (ammoniakslip) och bidrar troligen till korrosion på den kallare lågtrycksekonomisern nedströms rökgaskanalen. Umeå Energi vill minska sina utsläpp av NOx utan att öka risken för ammoniakrelaterad korrosion av lågtrycksekonomisern. I det här arbetet undersöktes om och hur NOx-bildningen kunde minskas och om det befintliga SNCR-systemet kunde optimeras. Vidare gjordes en utredning om användningen av selektiv katalytisk rening (SCR) på svenska avfallsförbränningsanläggningar samt om och var i Dåva 1 SCR skulle vara fördelaktig att installera. Effektiviteten hos SNCR-systemet testades genom att i perioder stänga av ammoniakdoseringen och logga rökgasinnehållet. Det visade sig vara mycket effektivt (80 %) om det kördes vid rätt temperaturintervall. Men det framkom också att temperaturgränserna för vilken tdoseringsnivå som används troligen kan behöva korrigeras för förbättringar i effektiviteten vid andra temperaturer. Det skulle kunna minska både NOx-utsläpp och ammoniakanvändningen. Användningen av SCR vid svenska avfallsanläggningar undersöktes genom intervjuer. Det visade sig vara bara fem anläggningar och där alla hade placerat katalysatorn i rengasposition, alltså efter elfilter och våt rening. Rökgasinnehållet vid tre olika positioner i Dåva 1 undersöktes för att se om det fanns höga halter av SO2, HCl och stoft, vilka i kombination med ammoniak kan skapa beläggningar som minskar effektiviteten hos en katalysator. Alla positioner låg efter slangfiltren och hade därmed låg stofthalt. Position A låg mellan slangfilter och högtryckseko1 hade den varmaste positionen (205℃) och position B efter ekopaketen (145℃). Position C var efter alla reningssteg i rengaspostion och svalaste positionen (65℃). Variationen hos temperaturerna för de olika positionerna medför en stor skillnad i behovet av att återvärma rökgaserna. Den säkraste positionen, med lägst innehåll av stoft, HCl och SO2 var rengaspositionen, men den krävde istället mest uppvärmning av rökgaserna. Med tanke på att SNCR-systemet visade sig ha förbättringspotential, borde det effektiviseras innan man överväger att installera ett SCR system. / Waste incineration is used to reduce the volume of waste, destruction of hazardous waste and to extract energy in combined heat and power plants (CHP). Umeå Energi’s CHP Dåva 1 incinerates municipal solid waste (MSW) and other hazardous waste. Nitrogen oxides (NOx) are formed in the combustion process. The emission of NOx is regulated in Sweden’s regulation SFS 2013:253 and law 1990:613. Dåva 1 uses selective non-catalytic reduction (SNCR) with ammonia as flue gas treatment, to reduce NOx in the flue gas. Some of the ammonia in the process remains unreacted (ammonia slip) and it probably contributes to corrosion in the colder economizer. Umeå Energi wants to reduce the NOx emissions without increasing the ammonia related corrosion of the economizer. In the present study, the possibility to reduce NOx formation by SNCR optimization was evaluated. Furthermore an investigation on the use of selective catalytic reduction (SCR) in waste incineration plants in Sweden, and whether it is beneficent to install in Dåva 1, was included. The current efficiency of the SNCR system was tested by switching of the ammonia in short periods of time and measuring and logging the flue gas composition. The efficiency (80 %) proved to be very high if operated at the optimal temperature. ButHowever, the test also showed that the temperature limits for the injection levels could be optimized for improved efficiency. Improved efficiency at all temperatures could reduce both NOx emission and ammonia use. The use of SCR in Swedish waste incineration plants was investigated through interviews. It was found that only five plants are equipped with SCR and they were placed in the clean gas position – after electrostatic precipitatorelectric filter and wet scrubber treatment. The contents of the flue gas was examined monitored at three positions at Dåva 1. The content of SO2, HCl and dust were measured, which in combination with ammonia can cause coating with reduces the efficiency of the catalyst. All three positions were located after the textile filters and had low contents of dust. Position A was located between the textile fabric filters and the economizers and was the hottest position with 205℃. Position B was located after the economizers and had the temperature of 145℃. Position C had the cleanest and thereby the safest position for a catalyst, due to its location after all the flue gas treatments, but the temperature was only 65℃ and requires most re-heating of the flue gas. Since the SNCR system proved to have potential to be more efficient, it should be optimized before considering an investment in a SCR system.