Oxides of nitrogen from coal-fired power stations are considered to be major pollutants, and there is increasing concern for regulating air quality and offsetting the emissions generated from the use of energy. Reburning is an in-furnace, combustion control technology for NOx reduction. Another environmental issue that needs to be addressed is the rapidly growing feedlot industry in the United States. The production of biomass from one or more animal species is in excess of what can safely be applied to farmland in accordance with nutrient management plans and stockpiled waste poses economic and environmental liabilities. In the present study, the feasibility of using biomass as a reburn fuel in existing coal-fired power plants is considered. It is expected to utilize biomass as a low-cost, substitute fuel and an agent to control emission. The successful development of this technology will create environment-friendly, low cost fuel source for the power industry, provide means for an alternate method of disposal of biomass, and generate a possible revenue source for feedlot operators. In the present study, the effect of coal, cattle manure or feedlot biomass, and blends of biomass with coal on the ability to reduce NOx were investigated in the Texas A&M University 29.31 kW (100,000 Btu/h) reburning facility. The facility used a mixture of propane and ammonia to generate the 600 ppm NOx in the primary zone. The reburn fuel was injected using air. The stoichiometry tested were 1.00 to 1.20 in the reburn zone. Two types of injectors, circular jet and fan spray injectors, which produce different types of mixing within the reburn zone, were studied to find their effect on NOx emissions reduction. The flat spray injector performed better in all cases. With the injection of biomass as reburn fuel with circular jet injector the maximum NOx reduction was 29.9 % and with flat spray injector was 62.2 %. The mixing time was estimated in model set up as 936 and 407 ms. The maximum NOx reduction observed with coal was 14.4 % and with biomass it was 62.2 % and the reduction with blends lay between that of coal and biomass.

Oxides of nitrogen from coal-fired power stations are considered to be major pollutants, and there is increasing concern for regulating air quality and offsetting the emissions generated from the use of energy. Reburning is an in-furnace, combustion control technology for NOx reduction. Another environmental issue that needs to be addressed is the rapidly growing feedlot industry in the United States. The production of biomass from one or more animal species is in excess of what can safely be applied to farmland in accordance with nutrient management plans and stockpiled waste poses economic and environmental liabilities. In the present study, the feasibility of using biomass as a reburn fuel in existing coal-fired power plants is considered. It is expected to utilize biomass as a low-cost, substitute fuel and an agent to control emission. The successful development of this technology will create environment-friendly, low cost fuel source for the power industry, provide means for an alternate method of disposal of biomass, and generate a possible revenue source for feedlot operators. In the present study, the effect of coal, cattle manure or feedlot biomass, and blends of biomass with coal on the ability to reduce NOx were investigated in the Texas A&M University 29.31 kW (100,000 Btu/h) reburning facility. The facility used a mixture of propane and ammonia to generate the 600 ppm NOx in the primary zone. The reburn fuel was injected using air. The stoichiometry tested were 1.00 to 1.20 in the reburn zone. Two types of injectors, circular jet and fan spray injectors, which produce different types of mixing within the reburn zone, were studied to find their effect on NOx emissions reduction. The flat spray injector performed better in all cases. With the injection of biomass as reburn fuel with circular jet injector the maximum NOx reduction was 29.9 % and with flat spray injector was 62.2 %. The mixing time was estimated in model set up as 936 and 407 ms. The maximum NOx reduction observed with coal was 14.4 % and with biomass it was 62.2 % and the reduction with blends lay between that of coal and biomass.

No description available.

Manure-based biomass (MBB) has the potential to be a source of green energy at large coal-fired power plants and on smaller-scale combustion systems at or near confined animal feeding operations. Although MBB is a low quality fuel with an inferior heat value compared to coal and other fossil fuels, the concentration of it at large animal feeding operations can make it a viable source of fuel. Mathematical models were developed to portray the economics of co-firing and reburning coal with MBB. A base case run of the co-fire model in which a 95:5 blend of coal to low-ash MBB was burned at an existing 300-MWe coal-fired power plant was found to have an overall net present cost of $22.6 million. The most significant cost that hindered the profitability of the co-fire project was the cost of operating gas boilers for biomass dryers that were required to reduce the MBB's moisture content before transportation and combustion. However, a higher dollar value on avoided nonrenewable CO2 emissions could overrule exorbitant costs of drying and transporting the MBB to power plants. A CO2 value of $17/metric ton was found to be enough for the MBB co-fire project to reach an economic break-even point. Reburning coal with MBB to reduce NOx emissions can theoretically be more profitable than a co-fire project, due to the value of avoided NOx emissions. However, the issue of finding enough suitable low-ash biomass becomes problematic for reburn systems since the reburn fuel must supply 10 to 25% of the power plant?s heat rate in order to achieve the desired NOx level. A NOx emission value over $2500/metric ton would justify installing a MBB reburn system. A base case run of a mathematical model describing a small-scale, on-the-farm MBB combustion system that can completely incinerate high-moisture (over 90%) manure biomass was developed and completed. If all of the energy or steam produced by the MBB combustion system were to bring revenue to the animal feeding operation either by avoided fueling costs or by sales, the conceptualized MBB combustion system has the potential to be a profitable venture.

SCA Ortvikens energiavdelning har fem stycken fastbränslepannor som försörjer interna förbrukare med processånga. Bränslet är i huvudsak bark, biologiskt slam och pelletspulver. SCA är ålagda att registrera utsläpp till luft och redovisa detta enligt de i verksamhetstillståndet villkorsbelagda utsläppen samt för kväveoxid-deklaration och för handel om utsläppsrätter för CO2. Förutom verksamhetstillståndet innefattas SCA Ortviken dessutom av förordningen 2013:252 Stora förbränningsanläggningar. För att redovisa detta används miljöredovisningssystemet ”MRS” från Entric AB. Drift-och underhåll saknar i nulägen en övergripande bild över MRS vilket skulle underlätta deras arbete för att säkerställa funktion på ingående signaler och därmed minska risken för mätbortfall vilket kan förebygga höga utsläpp under produktionen i framtiden. I detta arbete har, genom flödesscheman för de mest relevanta signaler och mätvärden vad gäller utsläpp som är kopplade till MRS, kunna underlätta för processoperatörer och underhållsorganisationen att säkerställa mätfunktionen. Arbetet har dessutom, genom analys av historiska data över driften, lett till förslag på åtgärder för att minska bildandet av olika utsläpp. Arbetet har visat att det finns många enkla åtgärder som kan göras för att minska utsläppen på redan befintligt installerad teknik på pannorna, men även gett förslag på annat teknik, och hur denna kan appliceras. Arbetet har också visat på brister i den nuvarande dokumentation-och signalhanteringen i avseende att göra mätvärden synliga i processystem andra än MRS.

Nearly half of the electrical power produced in the United States is generated with coal. Coal power is inexpensive and reliable, but coal combustion releases harmful pollutants including NOx and SOx into the atmosphere if not controlled. CO2, a greenhouse gas, is also released during coal combustion and may contribute to global warming. A promising technology enabling carbon capture is oxy-coal combustion. During oxy-combustion, coal is burned in an atmosphere of O2 and recycled flue gas to eliminate nitrogen which makes up the majority of air-combustion flue gas. Oxy-combustion flue gas is mainly composed of CO2 and H2O. H2O can be condensed out of the gas, and the CO2 can then be captured and permanently stored relatively easily. The composition of the gas inside an oxy-fired boiler will be different due to the absence of nitrogen and the recycling of flue gas. Corrosive sulfur and chlorine gas species concentrations will be higher, and CO and NOx concentrations will be effected. An understanding of the differences in gas concentrations is critical to oxy-combustion boiler design. Four different pulverized coals were combusted in a reactor under staged and unstaged oxy-combustion conditions with warm recycled flue gas (420°F) to simulate conditions in an oxy-fired coal boiler. The gas composition was measured in the reducing and oxidizing zones for staged combustion, and in the same locations, 57 cm and 216 cm from the burner, for unstaged combustion. The results were compared to the results from similar staged air-combustion experiments using the same coals and burner. CO concentrations were higher for staged oxy-combustion compared to air-combustion, and the increase was more substantial for lower rank coals. H2S concentrations in the reducing regions were also higher, and the fraction of gas phase sulfur measured as H2S was higher for oxy-combustion. SO2 concentrations were 2.9 to 3.8 times as high as air-combustion concentrations. The measured conversion of coal sulfur to SO3 was lower for oxy-combustion, and ranged from 0.61% to 0.98%. The average fraction of coal sulfur measured in the gas phase was 84%, 80%, and 85% for staged oxy-combustion, unstaged oxy-combustion, and staged air-combustion respectively. HCl concentrations were 2.8 to 3.1 times higher in the staged oxy-combustion oxidizing zone, and a smaller fraction of coal chlorine was measured in the reducing zone. On average 70.8%, 79.5%, and 71.1% of the coal chlorine was measured as HCl for staged oxy-combustion, unstaged oxy-combustion, and staged air-combustion respectively. The fractions of coal chlorine and sulfur measured in the gas phase for staged combustion were not significantly affected by combustion media. Some staged oxy-combustion NO concentrations were lower than air-combustion concentrations while others were slightly higher, and NO emission rates were much lower due to recycling NO through the burner.

[EN] In the last years, many modelling works of NOx, soot and fuel consumption in Diesel engines have been developed; some of them approach the problem determining the interactions between the engine inputs and outputs, following a causal approach based on experimentation. On the opposite side, it is common to find more or less complex models that address the problem taking into account all the physical phenomena related. Nevertheless, it is not usual the use of in-cylinder pressure as a fundamental signal to characterise the process to determine the engine performance in terms of emissions and fuel consumption. The present work has as main goal to explore the potential of such signal to use it with a few mean variables in order to model emissions and performance. Based on that, two approaches were raised: the first is semi-empirical combining a simple phenomenological sub-model with empirical corrections, the other approach consider a purely empirical correlations based on statistics. The proposed semi-empirical models allows to obtain NOx emissions in the exhaust based on heat release law and flame adiabatic temperature, including corrections to take into account the "reburning" phenomena and the local emissions in nominal reference points. On the other hand, the consumption estimation is based on the effective parameters calculation from indicated parameters and mechanical losses. These are obtained with specific sub-models of friction between the contact surfaces with relative movement and auxiliary devices power. Regarding the NOx, soot and fuel consumption empirical models, these are based on Design of Experiment and Response Surface Methodology, in which with an statistical focus, allows to fit mathematical expressions as function of some input variables (from injection and air path systems) and combustion burnt angles. The model has allowed quantifying the effect of using in-cylinder pressure signal to obtain the combustion burnt angles, facing the alternative to model it only taking into account the inputs. Finally, two applications of the model were presented: in one side, their performance was evaluated in transient conditions. On the other hand, the models have been used to perform a multi-objective optimisation to reduce emissions and fuel consumption simultaneously. / [ES] En los últimos años se han desarrollado diversos trabajos de modelado de NOx, hollín y consumo de combustible en motores Diesel, Algunos de ellos enfocan el problema mediante la determinación de las relaciones entre los parámetros de entrada y las salidas del motor siguiendo un enfoque causa-efecto basado en la experimentación. En el extremo contrario, también son habituales los modelos más o menos complejos que abordan el problema teniendo en cuenta toda la física implicada en los fenómenos relevantes. Sin embargo, no son muy habituales los modelos que utilizan la información de la señal de presión en el cilindro como entrada fundamental para caracterizar los fenómenos que van a determinar las prestaciones del motor en términos de emisiones y consumo. El presente trabajo tiene como objetivo fundamental explorar el potencial de dicha señal para modelar, junto con otras variables medias del motor, las emisiones y prestaciones. Para ello se han empleado dos enfoques: el primero semi-empírico en el que se combinan sub-modelos fenomenológicos sencillos con correcciones empíricas, y otro puramente empírico basado en correlaciones estadísticas. Los modelos semi-empíricos propuestos permiten obtener las emisiones de NOx en el escape basándose en la ley de liberación de calor y la temperatura adiabática de llama e incluyen sendas correcciones para tener en cuenta el fenómeno de reburning y las emisiones locales en puntos nominales de referencia. Por otro lado, la estimación del consumo se basa en el cálculo de los parámetros efectivos a partir de los indicados y las pérdidas mecánicas. Estas son obtenidas con sub-modelos específicos para la fricción en los contactos de los elementos con movimiento relativo y de accionamiento de auxiliares. Los modelos empíricos de NOx, hollín y consumo se basan en la metodología de Diseño de Experimentos y de Superficie de Respuesta que, con un enfoque estadístico, permite ajustar expresiones matemáticas en función de diferentes variables de entrada (tanto relacionadas con la renovación de la carga como con la inyección) y ángulos característicos de combustión. El modelo ha permitido cuantificar el efecto de usar la señal de presión experimental para obtener los ángulos de combustión, frente a la alternativa de modelarlos sólo con las entradas. Finalmente, se presentan dos aplicaciones de los modelos propuestos donde, en primer lugar, se ha evaluado sus prestaciones en condiciones transitorias, y en segundo lugar, se han empleado para realizar una optimización multi-objetivo para reducir simultáneamente emisiones y consumo / [CAT] En els últims anys s'han desenvolupat diversos treballs de modelatge de NOx, sutge i consum de combustible en motors dièsel. Alguns d'ells enfoquen el problema mitjançant la determinació de les relacions entre els paràmetres d'entrada i d'eixida del motor amb un enfocament causa-efecte basat en l'experimentació. D'una altra banda, també són habituals els models més o menys complexos que aborden el problema tenint en compte tota la física implicada en els fenòmens rel.levants. No obstant això, no són molt habituals els models que utilitzen informació del senyal de pressió en el cilindre com a entrada fonamental per caracteritzar els fenòmens que determinen les prestacions del motor en termes d'emissions i consum. El present treball té com a objectiu fonamental explorar el potencial d'aquest senyal per a modelar, juntament amb altres variables promedi del motor, les emissions i prestacions. Per això s'han emprat dos enfocaments: el primer semi-empíric en el qual es combinen sub-models fenomenològics senzills amb correccions empíriques, i un altre purament empíric basat en correl.lacions estadístiques. Els models semi-empírics proposats permeten obtenir les emissions de NOx en el escapament basant-se en la equació d'alliberament de calor i la temperatura adiabàtica de flama i inclouen sengles correccions per tindre en compte el fenomen de reburning i les emissions locals en punts nominals de referència . D'una altra banda, l'estimació del consum es basa en el càlcul dels paràmetres efectius a partir dels indicats i les pèrdues mecàniques. Aquestes són obtingudes amb sub-models específics per a la fricció en els contactes dels elements amb moviment relatiu i d'accionament d'auxiliars. Els models empírics de NOx, sutge i consum es basen en la metodologia de Disseny d'Experiments i de Superfície de Resposta que, amb un enfocament estadístic, permet ajustar expressions matemàtiques en funció de diferents variables d'entrada (tant relacionades amb la renovació de la càrrega com amb l 'injecció) i angles característics de combustió. El model ha permès quantificar l'efecte d'usar el senyal de pressió experimental per obtindre els angles de combustió, davant l'alternativa de modelar utilitzant les entrades. Finalment, es presenten dues aplicacions dels models proposats on, en primer lloc, s'ha avaluat les seues prestacions amb condicions transitòries, i en segon lloc, s'han emprat per a realitzar una optimització multi-objectiu per reduir simultàniament emissions i consum. / García Sarmiento, D. (2016). Aportaci ón al modelado de emisiones y consumo basado en la señal de presi ón en el cilindro en motores Diesel [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/62184 / TESIS