This degree project studies implementation and comparison of different AI models to predict (1) solid biofuel elements including carbon, hydrogen, nitrogen, and oxygen as well as moisture content, ash content, and higher heating value (HHV) of the fuel and (2) flue gas compositions such as concentration of carbon dioxide, carbon monoxide, nitrogen, nitrogen oxides, and water content using near-infrared spectroscopy and chemometric approaches. The study executes these predictions by simulating the operation of a combined heat and power plant (CHP) that is equipped with carbon capture and storage (CCS). The focus of this study is to investigate the possibility of using Near-Infrared spectroscopy (NIRs) technology to predict the emissions from a CHP plant, which can further improve the performance of the CCS system by providing the necessary fuel data in real time. The acquired NIR data is used to develop the Artificial Intelligence (AI) models using several regression algorithms including Linear regression, Gaussian process, Support Vector Machine, Artificial Neural Network, Ensemble Trees, and Tree regression. NIR data has been pre-processed using Savitzky-Golay (SG) and Multi scatter correction (MSC) techniques. Highest accuracy has been achieved for moisture content of the fuel using Exponential Gaussian Process, where an RMSE of 2.5687 and an R2-value of 0.9 has been obtained. Indeed, only a handful of regression algorithms have shown reasonable accuracy when predicting the fuel elements, where the HHV of the fuel has been predicted poorly as none of the algorithms have been able to execute the prediction successfully which leads to negative values of R2. Prediction of flue gas composition has been done resulting in reasonable accuracies for CO2 fraction with values of 0.1051 and 0.6 for RMSE and R2 respectively. Furthermore, the computational time of the algorithms has been investigated, which indicates that some of the pre-processing techniques could improve the computational time for a certain regression model, but not for all of them. It is conclusively possible to predict fuel elements and flue gas compositions based on data acquired from NIR spectroscopy. However, great effort must be put into model development including data treatment and AI model calibration to achieve desirable precision and reliable results.

Porous organic polymers (POPs) with high physicochemical stability have attracted significant attention from the scientific community as promising platforms for small gas separation adsorbents. Although POPs have amorphous morphology in general, with the help of organic chemistry toolbox, ultrahigh surface area materials can be synthesized. In particular, nitrogen-rich POPs have been studied intensively due to their enhanced framework-CO2 interactions. Postsynthetic modification (PSM) of POPs has been instrumental for incorporating different functional groups into the pores of POPs which would increase the CO2 capture properties. We have shown that functionalizing the surface of POPs with nitro and amine groups increases the CO/N2 and CO2/CH4 selectivity significantly due to selective polarization of CO2 molecule. In addition, controlled postsynthetic nitration of NPOF-1, a nanoporous organic framework constructed by nickel(0)-catalyzed Yamamoto coupling of 1,3,5-tris(4-bromophenyl)benzene, has been performed and is proven to be a promising route to introduce nitro groups and to convert mesopores to micropores without compromising surface area. Reduction of the nitro groups yields aniline-like amine-functionalized NPOF-1-NH2. Adequate basicity of the amine functionalities leads to modest isosteric heats of adsorption for CO2, which allow for high regenerability. The unique combination of high surface area, microporous structure, and amine-functionalized pore walls enables NPOF-1-NH2 to have remarkable CO2 working capacity values for removal from landfill gas and flue gas. Benzimidazole-linked polymers have also been shown to have promising CO2 capture properties. Here, an amine functionalized benzimidazole-linked polymer (BILP-6-NH2) was synthesized via a combination of pre- and postsynthetic modification techniques in two steps. Experimental studies confirm enhanced CO2 uptake in BILP-6-NH2 compared to BILP-6, and DFT calculations were used to understand the interaction modes of CO2 with BILP-6-NH2. Using BILP-6-NH2, higher CO2 uptake and CO2/CH4 selectivity was achieved compared to BILP-6 showing that this material has a very promising working capacity and sorbent selection parameter for landfill gas separation under VSA settings. Additionally, the sorbent evaluation criteria of different classes of organic polymers have been compared in order to reveal structure-property relationships in those materials as solid CO2 adsorbents.

Fjärrvärme är den vanligaste uppvärmningsformen i Sverige och mer än hälften av alla lokaler och bostäder får sin uppvärmning från gemensamma fjärrvärmeanläggningar. Rökgaskondensering producerar 11 % av all fjärrvärme vilket gör den till den tredje största fjärrvärmeproducenten i Sverige. Det är därför är det viktig att den är så effektiv som möjligt. För att öka effektiviteten i förbränningsanläggningar i fjärrvärmesystem kan rökgaskondensering installeras i sammanband med de flesta bränslen som avger fuktig ånga. Rökgaskondenseringen har en viktig roll i samhället då den tar vara på energi som annars skulle gå förlorad samtidigt som den kan rena avgaserna från förorenade utsläpp. Borlänge‑Energi äger ett rökgaskondenseringssystem på Stora Enso Kvarnsvedens Pappersbruk. De vill nu utreda om deras rökgaskondenseringssystem körs så effektivt som den skulle kunna göra. Den här rapporten undersöker därför hur driften påverkas av förändrade fram- och returledningstemperaturer samt vad produktionskostnadsförändringarna på den producerade värme blir. Beräkningar har genomförts med hjälp av fjärrvärmevattnets densitet, specifikvärmekapacitet, flödes- och temperaturskillnad i Excel. Alla beräkningar har utgått från medianvärdet för månaden och sedan jämförts med vad som händer vid förändrad fram‑ och returledningstemperatur. Som underlag för beräkningarna har data insamlad under perioden januari 2015 och december 2018 använts. Resultatet visar att öka framledningstemperaturen till 95 °C från medianframledningstemperaturerna för respektive månad, det vill säga från temperaturintervall på 79 – 88 °C till 95 °C, ökar energikostnaderna med cirka 2,5 miljoner SEK per år. Kostnaden kan minskas med 400 000 SEK/år genom att sänka returledningstemperaturen till 40 °C. Minskas istället framledningstemperaturen till 75 °C när utomhustemperaturen är varmare än ‑1 °C, minskar de nuvarande energikostnaderna. En minskad framledningstemperatur ger även minskade förluster i ledningarna, minskat slitage, minskad bränsleförbrukning och minskade utsläpp. Temperatursänkning till 75 °C från temperaturintervallet 79 – 88 °C kan minska kostnaderna med 620 000 SEK per år. Skulle returledningstemperaturen sänkas men framledningstemperaturen bibehållas som den är idag kan en kostnadsminskning på över 400 000 SEK nås. Genom att sänka både fram- och returledningstemperaturerna kan en kostnadssparning på över 1 miljon SEK per år ske. Den framledningstemperatur som rekommenderas att Borlänge‑Energi strävar efter är: 75 °C när utomhustemperaturen är varmare än -1 °C 80 °C mellan -2 och -4 °C 85 °C vid -5 °C 90 °C mellan -6 och ‑7 °C 95 °C mellan -8 och -11 °C / The most common way of heating buildings in Sweden is by district heating, more than half of all the locales and homes is heated this way. Flue gas condensation is the third largest contributor of energy in district heating at 11 %. The importance of its efficiency is thereby big. Flue gas condensation can be installed at combustion boilers to increase the efficiency, it can be used in combination with most fuels that exhaust steam. The flue gas condensation has an important role by harnessing the energy in flue gases and cleansing it from environmental hazards. The flue gas condensation unit on Stora Enso Kvarnsveden Mill is owned by Borlänge‑Energi. They want to know if the condenser is operating as effective as it could be. This report investigates how the condenser and external heater at Stora Enso Kvarnsveden Mill is affected by different supply and return temperatures as well as what the production costs of the energy is. The calculations have been accomplished by using the density, specific heat capacity, flow- and temperature differences in Excel. All the calculations have originated from the median value for each month and used in comparison. The basis of the calculations is data that has been collected in the period of January 2015 to December 2018. The results indicate that increasing the supply temperature to 95 °C increases the energy costs by about 2 500 000 SEK per year. These costs can be reduced by 400 000 SEK per year by decreasing the return temperature to 40 °C. If the supply temperature is instead decreased to 75 °C when the temperature outside is higher than -1 °C, the costs decreases. A low supply temperature leads to less wear on the pipes, less heat losses, less fuel consumption and less emissions. This temperature reduction can decrease the costs by 620 000 SEK per year. If the return temperature is reduced but the supply temperature retained as it is today the costs could decrease by over 400 000 SEK per year. And by reducing both the supply and return temperature a cost saving of over 1 000 000 SEK per year could be achieved. The recommendation is therefore a lowering of the supply temperature to 75 °C when the temperature outside is warmer than -1 °C. The recommended supply temperature is: 75 °C when the temperature outside is warmer than -1 °C 80 °C between -2 and -4 °C 85 °C at -5 °C, 90 °C between -6 and ‑7 °C 95 °C between -8 and -11 °C

This thesis contributes to an increased understanding of the formation of dioxins and dioxin-like compounds in combustion processes. Although emissions to air from waste incineration facilities have been greatly reduced by the use of efficient air pollution control measures, the resulting residues (ashes and filters) are highly toxic and are classified as hazardous waste. The main objective of the work underlying this thesis was to elucidate the formation and chlorination pathways of dioxins and dioxin-like compounds in waste combustion flue gases in the temperature range 640-200°C in a representative, well-controlled laboratory-scale reactor using artificial municipal solid waste. This could contribute to the reduction of harmful emissions to air and also reduce the toxicity of waste incineration residues, thus reducing or even eliminating the need for costly and potentially hazardous after-treatment. A comparison of four different quenching profiles showed that the formation of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) was rapid and mainly occurred in the 640-400°C temperature region, with high dependency on sufficient residence time within a specific temperature region. Prolonged residence time at high temperatures (450/460°C) reduced the PCDD yields, even at lower temperatures along the post-combustion zone. PCDD, PCDF and PCN (polychlorinated naphthalene) isomer distribution patterns indicated contributions from chlorophenol condensation as well as chlorination reactions for all three classes of compounds. The formation of PCDDs was largely influenced by chlorophenol condensation and to some extent by chlorination reactions. For the PCDFs, chlorine substitution adjacent to the oxygen bridges was unfavoured, as demonstrated by the notably lower abundance of 1,9-substituted congeners. This was supported by bidirectional orthogonal partial least squares (O2PLS) modelling. The variable with the greatest influence on the distribution of PCDD congeners was the relative free energy (RΔGf). The O2PLS models displayed distinct clusters, dividing most of the homologues into two or three sub-groups of congeners which seemed to correspond to the probability of origination from chlorophenol condensation. The effects of injection of aromatic structures into the flue gas differed for each class of compounds. Injection of naphthalene increased the formation of monochlorinated naphthalene but the remaining homologues appeared to be unaffected. This was probably due to insufficient residence time at temperatures necessary for further chlorination. Injected dibenzo-p-dioxin was decomposed, chlorinated and re-condensated into PCDDs and PCDFs, whereas injection of dibenzofuran and fluorene reduced the PCDD levels in the flue gas. / Denna avhandling fokuserar på olika aspekter som kan bidra till en ökad förståelse av bildning av dioxiner och dioxin-lika föreningar i förbränningsprocesser. Även om utsläppen till luft från sopförbränningsanläggningar har minskat kraftigt tack vare effektiva rökgasreningsmetoder, så återstår problemet med mycket giftiga rökgasreningsprodukter (askor och filter), vilka klassificeras som farligt avfall. Det huvudsakliga syftet med arbetet bakom denna avhandling var att klarlägga bildnings- och kloreringsvägarna för dioxiner och dioxin-lika föreningar i temperaturintervallet 640-200°C i rökgaser från sopförbränning. Detta kan möjliggöra lösningar för ytterligare emissionsminskningar och en avgiftning av biprodukterna från avfallsförbränning, vilket minskar eller till och med eliminerar behovet av kostsam och riskfylld efterbehandling. Realistiska och välkontrollerade försök har utförts i en lab-skalereaktor där en artificiell hushållssopa har förbränts. En jämförelse av fyra olika temperatur- och uppehållstidsprofiler visade att bildning av polyklorerade dibenso-p-dioxiner (PCDD) och dibensofuraner (PCDF) sker snabbt och huvudsakligen inom temperaturintervallet 640-400°C. Bildningen var starkt beroende av en tillräckligt lång uppehållstid inom ett visst temperaturområde. En förlängd uppehållstid vid höga temperaturer (>450°C) resulterade i minskade halter av PCDD, vilka förhöll sig låga även senare i efterförbränningszonen. Isomermönstren av PCDD, PCDF och PCN (polyklorerade naftalener) visade alla tecken på att härröra från både klorfenolkondensation och kloreringsreaktioner. PCDD-mönstret visade tydliga indikationer på bildning från klorfenoler, och till mindre grad bildning via klorering. För PCDF var klorsubstitution i positioner angränsande till syrebryggan missgynnad, vilket bekräftades av multivariat modellering (O2PLS). Den variabel som starkast påverkade bildningen av PCDD var relativa fria energin (RΔGf). Modellerna visade på en distinkt gruppering av PCDD- och PCDF-kongenerna i två eller tre grupper för varje kloreringsgrad, och föreslås vara relaterad till sannolikheten för respektive kongen att bildas via klorfenolkondensation. Injektion av aromatiska kolstrukturer i rökgaskanalen gav upphov till skilda effekter. Injektion av naftalen ökade bildningen av monoklorerad naftalen medan resterande homologer inte verkade påverkas, sannolikt på grund av för kort uppehållstid för ytterligare klorering. Dibenso-p-dioxin spjälkades sannolikt till fenoliska fragment som klorerades och sedan återkondenserades till PCDD och PCDF, medan dibensofuran och fluoren kraftigt reducerade PCDD-koncentrationerna.

One of the most common ways to produce heat and electricity in Europe today is by the incineration of waste or combustion of coal. These materials can be very sulfurous and during combustion sulfur dioxide is produced. This is an environmental and health related toxic substance which is why power plants have strict regulations on removing it from the flue gas. Sulfur dioxide is removed from the flue gas by adding a limestone reagent. The sulfur dioxide reacts with the limestone and the synthetic product obtained is “Flue Gas Desulfurization gypsum”. This byproduct, from combustion, provides an environmentally friendly solution when used in building material such as plasterboards. The FGD gypsum that is being used in different types of building materials does not derive from waste incinerated power plants. We have more than 30 of these in Sweden and some of them get FGD gypsum as a byproduct. The purpose of this thesis was to find out whether a particular waste incineration plant in Sweden can reuse their gypsum waste instead of disposing it at landfill.

The thermal formation of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), and naphthalenes (PCNs) is a major problem in waste incineration. Ideally, rather than relying on air cleaning systems and treatment techniques, their formation should be minimized or, if possible eliminated. The work presented in this thesis was conducted to obtain a deeper understanding of the thermal formation of PCDDs, PCDFs, PCBs, and PCNs during incineration using a 5 kW laboratory scale incinerator and two artificial wastes that were designed to reflect regional differences in waste composition. The first part of the thesis focuses on the validation of a recently-developed flue-gas sampling probe with enhanced cooling capabilities. Artifact formation of PCDDs and PCDFs can occur during the sampling of hot flue gases if the cooling is insufficient. The new probe was successfully used to collect samples at 700 °C without biasing the measured POP levels. The thermal formation of PCDDs, PCDFs, PCBs, and PCNs in the post-combustion zone of the incinerator was then studied by collecting flue gas samples at 400 °C, 300 °C, and 200 °C during the incineration of the two artificial wastes. Highly chlorinated POPs were formed in larger quantities when burning the waste with the higher content of metals and chlorine, which suggests that high metal levels in the waste favor the chlorination of less chlorinated POPs or otherwise facilitate the formation of highly chlorinated polyaromatics, possibly via the condensation of highly chlorinated phenols. The concentrations of these pollutants and the abundance of highly chlorinated homologues increased as the flue gas cooled. Fly ash particles play an important role in thermal POP formation by providing essential elements (carbon, chlorine, etc.) and catalytic sites. The chemical and mineralogical properties of fly ash samples were studied by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscopy/Energy Dispersive X-ray (SEM/EDX), and X-ray photoelectron spectroscopy (XPS) to determine their impact on thermal POP formation. Orthogonal Partial Least Squares (OPLS) modeling was used to identify correlations between the observed POP distributions and the physicochemical data. This investigation provided new insights into the impact of fly ash chemistry on thermal POP formation. In addition, the POP isomer distribution patterns generated during waste combustion were examined. These patterns are used to “fingerprint” mechanisms of POP formation. It was found that wastes containing large quantities of metals and chlorine favored the formation of highly chlorinated homologues including the very toxic 2,3,7,8-congeners. The data suggest that reducing fly ash emissions might increase the SO2 content of the flue gas and thereby suppress the Deacon process and the formation of harmful highly chlorinated aromatic species.

Experiments with both quantitative and qualitative factors always complicate the selections of experimental settings and the statistical analysis for data. Response surface methodology (RSM) provides the systematic procedures such as the steepest ascent method to develop and improve the response models through the optimal settings of quantitative factors. However the sequential method lacks of exploring the direction of the maximum increase in the response among the qualitative levels. In this dissertation the optimal designs for experiments with both qualitative and quantitative factors are investigated. Focused on the second-order response surface model for quantitative factors, which is widely used in RSM as a good approximation for the true response surface, the approximate and exact D-optimal designs are proposed for the model containing the qualitative effects. On spherical design regions, the D-optimal designs have particular structures for considering the qualitative effects to be fixed or random. In this study, the exact D-optimal designs for a second-order response surface model on a circular design region with qualitative factors are proposed. For this model, the interactions between the quantitative and qualitative factors are assumed to be negligible. Based on this design region, an exact D-optimal design with regular polygon structure is made up according to the remainder terms of the numbers of experimental trials at each qualitative levels divided by 6. The complete proofs of exact D-optimality for models including two quantitative factors and one 2-level qualitative factor are presented as well as those for a model with only quantitative factors. When the qualitative factor has more than 2 levels, a method is proposed for constructing exact designs based on the polygonal structure with high efficiency. Furthermore, a procedure for minimizing the number of support points for the quantitative factors of exact D-optimal designs is also proposed for practical consideration. There are no more than 13 support points for the quantitative factors at an individual qualitative level. When the effects between the quantitative and qualitative factors are taken into consideration, approximate D-optimal designs are investigated for models in which the qualitative effects interact with, respectively, the linear quantitative effects, or the linear effects and 2-factor interactions of the quantitative factors or quadratic effects of the quantitative factors. It is shown that, at each qualitative level, the corresponding D-optimal design consists of three portions as a central composite design but with different weights on the cube portion, star portion and center points. Central composite design (CCD) is widely applied in many fields to construct a second-order response surface model with quantitative factors to help to increase the precision of the estimated model. A chemical study is illustrated to show that the effects of the qualitative factor interacts with 2-factor interactions of the quantitative factors are important but absent in a second-order model including a qualitative factor treated as a coded variable. The verification of the D-optimality for exact designs has become more and more intricate when the qualitative levels or the number of quantitative factors increase, even when the patterns of the exact optimal designs have been speculated. The efficient rounding method proposed by Pukelsheim and Rieder (1992) is a model-free approach and it generates an exact design by apportioning the number of trials on the same support points of a given design. For constructing the exact designs with high efficiencies, a modified efficient rounding method is proposed and is based on the polygonal structure of the approximate D-optimal design on a circular design region. This modification is still based on the same rounding approach by apportioning the number of trials to the concentric circles where the support points of the given design are standing on. Then a regular polygon design will be assigned on the circles by the apportionments. For illustration, the exact designs for a third-order response surface model with qualitative factors are presented as well as those for the second-order model. The results show that nearly D-optimal designs are obtained by the modified procedure and the improvement in D-efficiency is very significant. When the factors with the levels selected randomly from a population, they are treated as with random effects. Especially for the qualitative effects caused by the experimental units that the experimenter is not interested in, one should consider the model with random block effects. In this model, the observations on the same unit are assumed to be correlated and they are uncorrelated between different units. Then the mean response surface is still considered as second-order for quantitative factors but the covariance matrix of the observations is different from the identity matrix. In the fourth part of this dissertation, the locally D-optimal designs on a circular design region are proposed for given the value of the correlations. These optimal designs with the structures based on the regular polygons are similar to the D-optimal designs for the uncorrelated model.

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Research of conditions when sulphure dioxide is absorbed from flue gas, is the main objective of this master's thesis. Efficiency of this flue gas cleaning was measured on an experimental device, which consist of an absorption column filled with structured packing’s, and another component so-called "O-element". Further, a possibility of upgrade this "O-element" to tread more flue gas is presented.