The use of urea (NH2CONH2) to remove nitric oxide (NO) from exhaust streams was investigated using a laboratory laminar-flow reactor. The experiments used a number of gas compositions to simulate different combustion exhaust gases. The urea was injected into the gases as a urea-water solution. The decomposition processes of the urea-water solutions and urea powder were examined. For both the nitric oxide removal and the urea decomposition experiments, a Fourier transform infrared (FTIR) spectrometer was used to determine the concentrations of the product species. The products from the decomposition were examined every 50 K from 500 K to 800 K. The dominant products were ammonia (NH3), isocyanuric acid (HNCO) and carbon dioxide (CO2). In case of urea-water solution decomposition, for gas temperatures between 550 and 650 K, the highest concentrations were for NH3 and HNCO. On the other hand, the concentrations of CO2 were highest for gas temperatures of about 500 - 550 K. For temperatures above about 650 K, the amount of these three dominant prod-ucts slightly decreased as temperature increased. ivFor the nitric oxide removal (SNCR) experiments, the gas mixture was heated to temperatures between 800 K and 1350 K. Depending on the temperature, gas composition, residence time, and urea feed rate, removal levels of up to 95% were obtained. Other by-products such as N2O were detected and quantified. The effects of the urea/NO (beta) ratio were determined by varying the urea concentration for a constant NO con-centration of 330 ppm. The effects of the levels of oxygen (O2) in the exhaust gases and the residence time also were investigated. Increasing the urea/NO ratio and residence time resulted in higher NO removal and increased the temperature window of the nitric oxide removal.

Utsläpp av kväveoxider (NOx) från förbränningsanläggningar har kraftigt minskat sedan kväveoxidavgiften infördes. Berörda anläggningar använder därför oftast rökgasrening med selektiv icke-katalytisk reduktion (SNCR). Metoden innebär att man tillsätter ammoniak i rökgaserna för att reducera NOx-halterna. Detta resulterar dock i att oreagerad ammoniak följer med ut i rökgaserna som därmed ger höga ammoniumhalter i rökgaskondensatet. Många anläggningar har villkor på ammonium i kondensatet som kräver att detta renas bort innan vattnet släpps ut till en recipient. Genom samarbete med kraftvärmeverket i Kiruna har deras anläggning använts som objekt att utgå ifrån eftersom de är i behov av att rena ammonium ur rökgaskondensatet för att i framtiden klara de kommande utsläppsvillkoren. Därmed undersöker detta arbete vilken reningsteknik som är mest lämplig för Kirunas värmeverk. Genom detta arbete har fyra olika reningstekniker för ammoniumkväve, samt en alternativmetod till detta undersökts. Reningsteknikerna är ammoniakstripper, kontaktmembran, återföring av ammoniakhaltigt vatten till eldstaden samt rening med RO. Alternativmetoden är att installera en slip-SCR som tar hand om överbliven ammoniak i rökgaserna. Resultaten visar att alla reningstekniker har en reningsgrad på ca 90%. Den mest lämpliga reningstekniken för Kirunas värmeverk är enligt denna undersökning en ammoniakstripp som också är den vanligaste och mest beprövade tekniken. / Emissions of nitrogen oxides (NOx) from incineration plants have decreased since the introduction of nitrogen oxide charge. Flue gas treatment with selective non-catalytic reduction (SNCR) is used to reduce the NOx-levels where ammonia is added. This results in unreacted ammonia in the flue gas, which ends up in the condensate as ammonium. Many plants have conditions of ammonium in condensate which require purification before the water is released to a recipient. Through cooperation with the heating plant in Kiruna, their plant has been used as a study object. They need to purify ammonium from the flue gas condensate to cope with future limits of emissions. Thus, this work investigates which technique for ammonium removal is the best for Kiruna´s heating plant. Four different purification techniques for ammonium and an alternative method has been investigated. The techniques are ammonia stripper, contact membrane, return of ammonia-containing water to boiler and removal with RO. The alternative method is to install a slip-SCR that takes care of the ammonia residues in the flue gas. The results show that all techniques have a purification rate of about 90%. According to this study, the best technology for Kiruna´s heating plant is an ammonia stripper that is also the most common and proven technology.

Techn. Universiẗat, Diss., 2004--Clausthal.

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.

V současnosti musí velké energetické podniky k dodržení emisních předpisů, zejména pak vyžadovaných limitů NOx, uplatňovat denitrifikační metody. Tématem předkládané diplomové práce jsou moderních denitrifikační metody a jejich praktické uplatnění v lokálních poměrech uhelného kotle s parním výkonem 640 t.h-1 v elektrárně Počerady. Práce obsahuje rešerši moderních denitrifikačních metod používaných velkými uhelnými kotli se zaměřením zejména na sekundární denitrifikační metody. Jsou uvažovány dvě možné varianty denitrifikace – varianta 1 využívá selektivní katalytickou redukci (SCR) a varianta 2 selektivní nekatalytickou redukci (SNCR) společně s nízkoemisními hořáky a stupňovaným přívodem spalovacího vzduchu. Pro výběr vhodné denitrifikační metody jsou studovány investiční náklady jednotlivých variant – nižší investiční náklady (o 19.4%) slibuje varianta 2. Při srovnávání SCR se SNCR vyšlo najevo, že investiční náklady metody SNCR jsou 5krát nižší než metody SCR. V souladu s investičními náklady, s dispozicí kotle a se složitostí jeho instalace je pro navazující studium problematiky využita varianta 2. Stěžejní část práce se zabývá stanovením optimálního tzv. teplotního okna pro konkrétní metodu SNCR. Těžištěm práce je tepelný výpočet ohniště a části deskového přehříváku pro stanovený rozsah paliv a výkon kotle v rozmezí 60-100%. S uvažováním výsledků z výpočtu jsou navrženy dvě vstřikovací roviny, které mají zaručit vysokou efektivitu denitrifikačního procesu při uvažovaných provozních podmínkách kotle. Diplomová práce rovněž diskutuje obecnou vhodnost instalace SNCR a SCR ve stávajících uhelných kotlích.

Studiens syfte var att studera en ombyggnation av SNCR-anläggningen i Filbornaverket, enavfallseldad rosterpanna, på uppdrag av Öresundskraft Kraft & Värme AB. Anledningen var attse om en minskning av NOx-utsläpp var möjlig då det innebär en minskning av försurning avskog och mark. Naturvårdsverket har som mål att minska mängden NOx-utsläpp genom attanvända sig av ekonomiska styrmedel.Filbornaverket är en panna på cirka 60 MW fjärrvärmeeffekt och 18 MW eleffekt. Metodensom användes var en jämförande metod. Ombyggnationen ledde till en minskning av NOxutsläppunder perioden oktober till november 2018 på 5,45% jämfört med samma period2017. Detta innebar en årlig besparing på cirka 250 000 kr i minskade NOx-avgifter tillNaturvårdsverket för Öresundskraft Kraft & Värme AB. Mängden insprutad ammoniak blev igenomsnitt 4,73% lägre 2018 jämfört med 2017. / This study examined the reconstruction of the SNCR equipment in Filbornaverket, a wasteburning grate boiler, on behalf of Öresundskraft Kraft & Värme AB. The purpose was to see ifa reduction of NOx was possible. A reduction of NOx means a reduction in acidification offorest and land. Naturvårdsverkets goal is to reduce the amount of NOx by using economiccontrol means.Filbornaverket is a boiler of about 60 MW district heating power and 18 MW electrical power.A comparative method was used in this study. The reconstruction lead to a reduced amountof NOx during the period October to November 2018 of 5,45% compared to same period2017. This means an annual saving of around 250 000 kr in reduced NOx-fees toNaturvårdsverket for Öresundskraft Kraft & Värme AB. The amount of injected ammonia wasin average 4,73% lower during 2018 compared to 2017.

The Master thesis deals with utilization possibilities of fly ash after selective non-catalytic reduction (SNCR) process for Portland cement preparation as a correction component to the raw material with regard to contaminated fly ash by ammonium sulphate or ammonium hydrogensulfate that is one of the products from SNCR process. Presented thesis was focused on behaviour of raw meal with ammonia hydrogensulfate contaminated fly ash after SNCR during burning of Portland clinker in simulated kiln conditions. The thesis deals with Portland clinker preparation from this kind of raw mix and it studies mainly clinker quality, clinker phases and structure. Quantitative phase composition of prepared samples of clinker was performed by optical microscopy measurements using point counting method and XRD analysis (Rietveld method). Hydration heat flow of prepared clinker was measured by Isothermal Calorimetry. TG-DTA analysis of prepared raw meal was studied due to better comparison of prepared samples and better understanding of processes during burning process.

<p>The aim of this thesis is to improve the control of urea injection at the combined power and heating plant Framtidens Gärstad (FTG). Tekniska Verken i Linköping AB is the owner of the plant.</p><p>The FTG plant consists of a boiler where garbage combustion is done. From the combustion nitrogen oxides are emitted. These nitrogen oxides are hazardous to the environment. To reduce the nitrogen oxides, injection of urea into the boiler is used. Urea is an organic compound of carbon, nitrogen, oxygen and hydrogen. When urea reacts with nitrogen oxides they transform into harmless nitrogen gas and water. In the plant the urea is injected by six lances.</p><p>The control of the urea injection at FTG could be improved which would save some money for the company. This is the main reason for the aim of this thesis. It is the control of the total flow of urea to the lances that is studied in this work.</p><p>Some literature about reduction of nitrogen oxides is studied, especially reduction using urea injection. There are a lot of factors that affect how good the reduction becomes. The most important factors are the amount of urea being used and the temperature of the flue gases where the reaction with urea takes place. A model with these two factors as inputs and the content of nitrogen oxides as output is derived. This is done with experiments in the boiler and system identification. The system is modelled as a linear system.</p><p>The proposal about the improved control uses the temperature from a temperature measurement just below the urea injection in the boiler. This is a parameter that the existing control does not use. The temperature is divided into three intervals. For each interval different parameters for the function of the system and the nitrogen oxide controller are used. The nitrogen oxide controller in the proposed control is derived with help from a new method of controldesign called AMIGO.</p><p>The identification models gave good results in two of the temperature intervals. The result for the third interval was not so good. This is probably due to lack of good data.</p><p>The proposed control structure could for practical reasons not be tested online but preliminary tests using measurement data gave qualitatively reasonable results.</p><p>In order to improve the results temperature dependence has to be treated more systematically.</p>

Abstract The decrement of Nitrogen Oxide (NOx) emission can slow down the impaction to the natural environment as well as avoiding the global warming become worse continuously. The three coal fired boilers in CSC were designed as capable of multi-fuel burning but its primary fuel is coal. The original designed coal is PCI coal from Australia. The NOx emission generating while using PCI coal is around 320 ppm and can,t meet the local EPA emission requirement set for year 2001, which is 300ppm. To cope with more stringent environmental requirement, the first stage strategy is to evaluate the NOx removal technologies and selecting the optimum one of them to fight against NOx emission. By means of MCDM (Multi-Criteria Decision-Making) methodologies, SNCR is chosen due to its simplicity and acceptable NOx-out ability. The 45% NOx reduction rate can be achieved and the control NOx final output will be lower than 200ppm, which is the promised level to the local EPA. In compromising the NOx reduction requirement and the practical running cost factor, the 240ppm NOx level has been determined for operating the SNCR system. The second stage of NOx reduction evaluation is focused on the coal brands selection. It¡As believed that through the right choose of suitable coal can offer the contribution to both environment and economic. After surveying the different coal composition analysis and carrying out real trial burn, the ADARO coal from Indonesia was picked up from competition and deem as the most environment friendly coal in terms of owning the optimum coal compositions and the lowest pollutants generation including NOx, SO2, as well as ash. As a result, the ADARO coal application is highly successful in the aspects of less pollutant generation and saving cost expenditure caused by the related environment equipment systems operation and maintenance. Obviously, the positive and close relationship between environment and economic has been proved. Base on the real evidence, this paper proves that by choosing the suitable methodologies, the NOx reduction can be accomplished to some extent. The whole environment can be benefited by this action and meanwhile the air pollution tax plus operation and maintenance cost can be reduced further. It¡As hoped that by announcing this paper, the outstanding performance of remarkable NOX reduction outcome and its coat saving advantage can be applied to the whole industrial field. Let¡As work together for the purpose of decreasing the pollutants emission, lightening the harms to the natural environment and fulfilling the duties of protection the all eco system. Key words: Nitrogen Oxide, Selective Non-Catalytic Reduction(SNCR), environmental coal, Multi-criteria decision-making(MCDM)

The aim of this thesis is to improve the control of urea injection at the combined power and heating plant Framtidens Gärstad (FTG). Tekniska Verken i Linköping AB is the owner of the plant. The FTG plant consists of a boiler where garbage combustion is done. From the combustion nitrogen oxides are emitted. These nitrogen oxides are hazardous to the environment. To reduce the nitrogen oxides, injection of urea into the boiler is used. Urea is an organic compound of carbon, nitrogen, oxygen and hydrogen. When urea reacts with nitrogen oxides they transform into harmless nitrogen gas and water. In the plant the urea is injected by six lances. The control of the urea injection at FTG could be improved which would save some money for the company. This is the main reason for the aim of this thesis. It is the control of the total flow of urea to the lances that is studied in this work. Some literature about reduction of nitrogen oxides is studied, especially reduction using urea injection. There are a lot of factors that affect how good the reduction becomes. The most important factors are the amount of urea being used and the temperature of the flue gases where the reaction with urea takes place. A model with these two factors as inputs and the content of nitrogen oxides as output is derived. This is done with experiments in the boiler and system identification. The system is modelled as a linear system. The proposal about the improved control uses the temperature from a temperature measurement just below the urea injection in the boiler. This is a parameter that the existing control does not use. The temperature is divided into three intervals. For each interval different parameters for the function of the system and the nitrogen oxide controller are used. The nitrogen oxide controller in the proposed control is derived with help from a new method of controldesign called AMIGO. The identification models gave good results in two of the temperature intervals. The result for the third interval was not so good. This is probably due to lack of good data. The proposed control structure could for practical reasons not be tested online but preliminary tests using measurement data gave qualitatively reasonable results. In order to improve the results temperature dependence has to be treated more systematically.