NOx and N2O Emission Formation Tendency From Multifuel CFB-Boilers: A Further Development of the Predictor

2005 ◽  
Author(s):  
Markus Engblom ◽  
Pia Kilpinen ◽  
Fredrik Klingstedt ◽  
Kari Era¨nen ◽  
Ranjit Katam Kumar
Keyword(s):  
Nitrogen Oxides ◽  
Fixed Bed ◽  
Operating Conditions ◽  
Fixed Bed Reactor ◽  
Municipal Sewage ◽  
Municipal Sewage Sludge ◽  
Wood Pellets ◽  
Char Particle ◽  
Technical University ◽  
Fuel Mixtures

Present paper is a part of our on-going model development activities with aim to predict formation tendency of gaseous emissions from CFB combustion of different fuels, and especially, fuel-mixtures in real furnaces of various scale. The model is based on detailed description of homogeneous, catalytic, and heterogeneous chemical kinetics, and a sound but simple 1.5D representation of fluid dynamics. Temperature distribution is assumed known. With the tool, different fuels and fuel mixtures can be compared in respect to their tendency to form nitrogen oxides (NOx, N2O). In this paper the model was tested to predict nitrogen oxide emissions from mono- or co-combustion of coal, wood, and sludge. The plants simulated were the 12MWth CFB combustor located at Chalmers Technical University (A = 2.25m2, h = 13.6m) and the pilot scale CFB unit at the Technical University Hamburg-Harburg (d = 0.1m, h = 15m). The results gave reasonable representation of the measured emission data, and reflected correctly to the changes in the fuel characteristics and in the furnace operating conditions in most cases. An extensive laboratory fixed-bed reactor study was also performed in order to obtain input values for the kinetic constants of the catalytic reactions for the reduction and decomposition of nitrogen oxides. In literature, there is a limited data available regarding the catalytic activity of CFB solids during combustion of wood- and waste-derived fuels, especially at co-firing conditions. The kinetics for the NO reduction by CO in the temperature range of 780–910°C was determined to be of the following form (NO = 300ppm, CO = 5000ppm): −rNO=k·[NO]0.48·[CO]0.55mol/g-s with k=8.15·exp(−8869/T)m3/kg-s(emptyreactoreffectincluded)ork=830·exp(−14930/T)(emptyreactoreffectexcluded), when using a bed sample (250–355 μm) taken from the transport zone in the CTH boiler while burning a mixture of wood pellets and a pre-dried municipal sewage sludge. The role of char particle size and shape as well as the incorporation of energy balance on the char reactivity and the formation of nitrogen oxides is further illustrated by single char particle oxidation simulations.

scholarly journals Co-Combustion of Municipal Sewage Sludge and Biomass in a Grate Fired Boiler for Phosphorus Recovery in Bottom Ash

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1708 ◽  
Author(s):  
Andreas Nordin ◽  
Anna Strandberg ◽  
Sana Elbashir ◽  
Lars-Erik Åmand ◽  
Nils Skoglund ◽  
...  
Keyword(s):  
Heavy Metals ◽  
European Union ◽  
Sewage Sludge ◽  
Fixed Bed ◽  
Bottom Ash ◽  
Phosphorus Recovery ◽  
Fixed Bed Reactor ◽  
Municipal Sewage ◽  
Municipal Sewage Sludge ◽  
Critical Element

Phosphorus has been identified as a critical element by the European Union and recycling efforts are increasingly common. An important phosphorus-containing waste stream for recycling is municipal sewage sludge (MSS), which is used directly as fertilizer to farmland. However, it contains pollutants such as heavy metals, pharmaceutical residues, polychlorinated bi-phenyls (PCBs) and nano-plastics. The interest in combustion of MSS is continuously growing, as it both reduces the volume as well as destroys the organic materials and could separate certain heavy metals from the produced ashes. This results in ashes with a potential for either direct use as fertilizer or as a suitable feedstock for upgrading processes. The aim of this study was to investigate co-combustion of MSS and biomass to create a phosphorus-rich bottom ash with a low heavy metal content. A laboratory-scale fixed-bed reactor in addition to an 8 MWth grate-boiler was used for the experimental work. The concentration of phosphorus and selected heavy metals in the bottom ashes were compared to European Union regulation on fertilizers, ash application to Swedish forests and Swedish regulations on sewage sludge application to farmland. Element concentrations were determined by ICP-AES complemented by analysis of spatial distribution with SEM-EDS and XRD analysis to determine crystalline compounds. The results show that most of the phosphorus was retained in the bottom ash, corresponding to 9–16 wt.% P2O5, while the concentration of cadmium, mercury, lead and zinc was below the limits of the regulations. However, copper, chromium and nickel concentrations exceeded these standards.

Modeling of a Fixed-Bed Reactor for the Production of Phthalic Anhydride

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Amir Rahimi ◽  
Sogand Hamidi
Keyword(s):  
Phthalic Anhydride ◽  
Fixed Bed ◽  
Tubular Reactor ◽  
Operating Conditions ◽  
Fixed Bed Reactor ◽  
Conversion Degree ◽  
Reactor Length ◽  
Reactor Temperature ◽  
Reported Data ◽  
Reactor Pressure

In this study, the performance of a fixed–bed tubular reactor for the production of phthalic anhydride is mathematically analyzed. The conversion degree and reactor temperature values are compared with the measured one in a tubular reactor applied in Farabi petrochemical unit in Iran as well as reported data in the literature for a pilot plate. The comparisons are satisfactory. The effects of some operating parameters including reactor length, feed temperature, reactor pressure, and existence of an inert in the catalytic bed are investigated. The optimum value of each parameter is determined on the basis of the corresponding operating conditions.

Theoretical Investigations of Methane Conversion to Heavier Hydrocarbons in a Plasma Reactor

2012 ◽  
Vol 548 ◽  
pp. 153-159
Author(s):  
Mohammad Kazemeini ◽  
Masoud Habibi Zare ◽  
Nora Safabakhsh ◽  
Shadi Roshdi Ferdosi ◽  
Moslem Fattahi
Keyword(s):  
Methane Conversion ◽  
Plasma Reactor ◽  
Fixed Bed ◽  
Oxidative Coupling Of Methane ◽  
Operating Conditions ◽  
Fixed Bed Reactor ◽  
Plasma Process ◽  
Process Yield ◽  
Theoretical Investigations ◽  
Product And Process

In this study, mathematical modelling of oxidative coupling of methane (OCM) to C2hydrocarbons (C2H6and C2H4) over La2O3/CaO catalyst in a fixed-bed reactor operated under isothermal and non-isothermal conditions was investigated using the MATLAB program. In this process, methane and acetylene were the inputted feed and ethane, ethylene, propylene, propane, i-butane and n-butane were the output products. The amount of methane conversion obtained was 12.7% for the former feed however; if pure methane was inputted this conversion rose to 13.8%. Furthermore, the plasma process would enhance the conversion, selectivity towards desired product and process yield. A comparison between the thermal and the plasma process showed that the methane conversion and production yield in the plasma were higher than in the thermal process under the same operating conditions. Finally, the results of the catalytic OCM and methane conversion processes in the plasma phase were compared with one another.

The Fixed Bed Reaction of Residual Natural Rubber for Oil Production by Pyrolysis Process

2014 ◽  
Vol 931-932 ◽  
pp. 225-230
Author(s):  
Khanita Kamwilaisak ◽  
Mallika Thabuot
Keyword(s):  
Particle Size ◽  
Pyrolysis Temperature ◽  
Fixed Bed ◽  
Maximum Amount ◽  
Operating Conditions ◽  
Fixed Bed Reactor ◽  
Pyrolysis Process ◽  
Pyrolysis Reaction ◽  
Benzenedicarboxylic Acid ◽  
Chemical Feedstock

The aim of this study is to use pyrolysis reaction to produce oil product as a fuel or chemical feedstock. The fixed bed reactor was used as a pyrolysis system. The pyrolysis reaction of residual para rubber was operated in the absence of catalyse. The operating conditions such as particle size (0.5 and 1.0 cm3) and pyrolysis temperature (500, 550 and 600 OC) were studied under N2 conditions and retention time 90 min. The result shows the para rubber size 1.0 cm3 can be produced liquid phase more than of para rubber size of 0.5 cm3. The optimised condition with the highest oil yield was at 550OC with rubber size of 1.0 cm3. The percentage of the product was 60% of liquid, 35% of gas and 5% of solid (char). Furthermore, the FTIR result can be presented the supported evidence that the transformation of aliphatic contents to be aromatic contents was increased with increased temperature. Also, GCMS analysis was used for the identification and quantification of the product. It was found 5 major products that can be used as a chemical feedstock. The maximum amount of component was 2-Benzenedicarboxylic acid, diisooctyl ester (Isooctyl phthalate) with 22.08%. This is a plasticizer with higher cost than fuel.

Utilisation of Biogas From an Urban Sewage Treatment Plant in a Solid Oxide Fuel Cell

2010 ◽  
Author(s):  
Andrea Lanzini ◽  
Pierluigi Leone ◽  
Massimo Santarelli
Keyword(s):  
Sewage Treatment ◽  
Fixed Bed ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Cell Voltage ◽  
Operating Conditions ◽  
Fixed Bed Reactor ◽  
Urban Sewage ◽  
Anode Degradation ◽  
Anode Supported Cell

A biogas coming from anaerobic digestion of urban sewage has been used to feed a SOFC planar anode-supported cell. The sewage is produced from the urban area of Torino (IT), and eventually collected and treated by SMAT (the municipal company managing the potable and waste water of the city). The biogas is produced by the thermophilic fermentation of the sludge which remains after the several treatments the sewage goes through in the above-mentioned plant. The biogas is of a high quality: it has on average a a methane content around 65% (the balance being essentially CO2), and the only significant impurity measured is H2S in a range of 70–80 ppm. The as-produced biogas has been used for feeding a planar Ni-YSZ anode-supported SOFC with a LSCF cathode. The biogas desulphurization was accomplished flowing the gas in a fixed-bed reactor, filled with activated. The fuel processing with POX has been assessed to avoid carbon deposition into the Ni-YSZ anode and convert the CH4 into H2 and CO. Short tests to check for eventual anode degradation were performed under typical operating conditions. The cell voltage was always stable under load with the tested mixtures. A cell electrical efficiency around 45% has been measured at 800°C and 80% FU. System simulations have performed as well to assess the whole system configuration under a biogas feeding. Optimization routines have been implemented to predict the best net AC efficiency achievable by a SOFC system running on biogas. Additional considerations on the management of poor LHV biogas mixture have been also assessed, showing how dry-reforming of CH4 with the CO2 already available in the biogas stream would be an excellent option needed to be investigated with further detail in the next future.

scholarly journals Integrated Ozonation-Enzymatic Hydrolysis Pretreatment of Sugarcane Bagasse: Enhancement of Sugars Released to Expended Ozone Ratio

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1274 ◽  
Author(s):  
Daryl Rafael Osuna-Laveaga ◽  
Octavio García-Depraect ◽  
Ramiro Vallejo-Rodríguez ◽  
Alberto López-López ◽  
Elizabeth León-Becerril
Keyword(s):  
Enzymatic Hydrolysis ◽  
Sugarcane Bagasse ◽  
Fixed Bed ◽  
Operating Conditions ◽  
Fixed Bed Reactor ◽  
Particle Sizes ◽  
Combined Effects ◽  
Sugar Release ◽  
The Relationship ◽  
Ozonation Process

The combined effects of three key ozonation process parameters on the integrated ozonation-enzymatic hydrolysis pretreatment of sugarcane bagasse (SCB) were investigated, with emphasis on the relationship between sugar release and ozone consumption. A lab-scale fixed bed reactor was employed for ozonation at varying ozone doses (50, 75 and 100 mg O3/g SCB), particle sizes (420, 710 and 1000 µm) and moisture contents (30, 45 and 60% w/w) in multifactorial experiments, keeping a residence time of 30 min. The ozonated SCB showed a reduction in the content of acid-insoluble lignin from 26.6 down to 19.1% w/w, while those of cellulose and hemicellulose were retained above 45.5 and 13.6% w/w, with recoveries of 100–89.9 and 83.5–72.7%, respectively. Ozone-assisted enzymatic hydrolysis allowed attaining glucose and xylose yields as high as 45.0 and 37.8%, respectively. The sugars released/ozone expended ratio ranged between 2.3 and 5.7 g sugars/g O3, being the higher value achieved with an applied ozone input of 50 mg O3/g SCB and SCB with 420 µm particle size and 60% moisture. Such operating conditions led to efficient ozone utilization (<2% unreacted ozone) with a yield of 0.29 g sugars/g SCB. Overall, the amount of sugars released relative to the ozone consumed was improved, entailing an estimated cost of ozonation of USD 34.7/ton of SCB, which could enhance the profitability of the process.

scholarly journals Temperature Influence on Ordinary Concrete Modified with Fly Ashes from Thermally Conversed Municipal Sewage Sludge Strength Parameters

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5259
Author(s):  
Gabriela Rutkowska ◽  
Paweł Ogrodnik ◽  
Joanna Fronczyk ◽  
Ayla Bilgin
Keyword(s):  
Compressive Strength ◽  
Sewage Sludge ◽  
Chemical Properties ◽  
Waste Recycling ◽  
Operating Conditions ◽  
Municipal Sewage ◽  
Municipal Sewage Sludge ◽  
Fly Ashes ◽  
Strength Parameters ◽  
Physical And Chemical

Concrete is the most commonly used structural material, without which modern construction could not function. It is a material with a high potential to adapt to specific operating conditions. The use of this potential is made by its material modification. The aim of the performed investigations was the assessment of rational application possibilities of fly ashes from thermally conversed municipal sewage sludge as an alternative concrete admixture. A concrete mix was designed, based on the Portland cement CEM I 42.5R and containing various quantity of ash, amounting to 0–25% of cement mass. The samples were conditioned and heated in a furnace at the temperature of 300 °C, 500 °C, and 700 °C. Physical and chemical properties of the ashes as well as utility properties of the concrete, i.e., density, compressive strength after 28, 56, and 90 days of maturation, frost resistance, and compressive strength in high temperature were determined. The tests were performed at cubic samples with 10 cm edge. The replacement of a determined cement quantity by the fly ashes enables obtaining a concrete composite having good strength parameters. The concrete modified by the fly ashes constituting 20% of the cement mass achieved its average compressive strength after 28 days of maturation equal to 50.12 MPa, after 56 days 50.61 MPa and after 90 days 50.80 MPa. The temperature growth weakens the composite structure. The obtained results confirm the possibility of waste recycling in the form of fly ashes as a cement substitute in concrete manufacturing.

Modeling of transport phenomena in fixed-bed reactors for the Fischer-Tropsch reaction: a brief literature review

2017 ◽  
Vol 33 (2) ◽  
Author(s):  
José R.G. Sánchez-López ◽  
Angel Martínez-Hernández ◽  
Aracely Hernández-Ramírez
Keyword(s):  
Liquid Fuel ◽  
Transport Phenomena ◽  
Fixed Bed ◽  
Reaction System ◽  
Operating Conditions ◽  
Fixed Bed Reactor ◽  
Fuel Production ◽  
Fischer Tropsch ◽  
Fixed Bed Reactors ◽  
The Impact

AbstractCurrently, few processes can be considered practical alternatives to the use of petroleum for liquid fuel production. Among these alternatives, the Fischer-Tropsch synthesis (FTS) reaction has been successfully applied commercially. Nevertheless, many of the fundamentals of this process are difficult to understand because of its complexity, which depends strongly on the catalyst and the reactor design and operating conditions, as the reaction is seriously affected by mass and heat transport issues. Thus, studying this reaction system with transport phenomena models can help to elucidate the impact of different parameters on the reaction. According to the literature, modeling FTS systems with 1D models provides valuable information for understanding the phenomena that occur during this process. However, 2D models must be used to simulate the reactor to correctly predict the reactor variables, particularly the temperature, which is a critical parameter to achieve a suitable distribution of products during the reaction. Thus, this work provides a general resume of the current findings on the modeling of transport phenomena on a particle/pellet level in a tubular fixed-bed reactor.

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