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The Selective Non-Catalytic Reduction process was investigated through experiments and modelling in a bench scale cyclone reactor. Outlet and internal profiles of NO and NH3 concentrations were measured at varying operating conditions. Cyclone inlet temperatures between 866 and 1023 °C were used, while the inlet NO concentration was kept at ~500 ppm. Gaseous ammonia was injected in the cyclone inlet, with nitrogen carrier gas. 60-69% NO reduction was achieved at inlet temperatures of 975-982 °C, and stoichiometric ratio NH3/NO β ≈ 1.6, with no ammonia slip. The main reaction zone was the inlet and upper cyclone chamber. The experiments was modelled using simple and detailed kinetics combined with simple reactor models and a compartment model suggested in this work. The qualitative trends of NO reduction and ammonia slip were predicted by the models. However, the ammonia slip was significantly over-predicted in most cases. The outlet concentrations were insensitive to choice of reactor model, while sensitive to temperature and kinetics. The compartment model quantitatively reproduced the cyclones NO concentration profiles, through its simplified representation of the cyclone flow and temperature gradients, while the NH3 profiles were only qualitatively predicted. The choice of bypass fractions showed a large influence on the ammonia profiles.

Phosphorus (P) from biomass can cause operational problems in thermal conversion processes. In order to explore the release mechanism of P to the gas phase, carbothermic reduction of meta-, pyro-, and orthophosphates of ash elements commonly found in biomass; sodium, potassium, magnesium, and calcium was investigated. Mixtures of each phosphate and activated carbon were heated to 1135 °C in a laboratory-scale reactor, with the CO and CO2 evolving from the sample monitored, and the chemical composition of selected residues analyzed to quantify the release of P. Thermal gravimetric analysis was also performed on selected samples. The alkaline earth phosphates were reduced in steps, following the sequence meta → pyro → ortho → alkaline earth oxide. However, the alkali metaphosphates appear to be reduced in one step, in which both alkali and P are released. Alkali pyro- and orthophosphate appear to undergo a two-step process. In the first step, mainly alkali is released and in the second step both alkali and P. An intermediate is produced in the first step, which has a K:P:O atomic ratio of about 2:1:2.7, indicating it might be a phosphite with the overall stoichiometry; K4P2O5. The reduction of alkaline earth phosphates could be interpreted using available thermodynamic data, whereas thermodynamic equilibrium calculations for the alkali phosphates did not correspond well to the experimental observations. Kinetics were derived for the different reduction reactions, and can be used to compare the reactivity of the phosphates. The work suggests that carbothermic reduction reactions are important for the release of P in the temperature range 850–1135 °C and relevant for biomass combustion, pyrolysis and gasification.

Biomass can be used to generate heat, power, or biofuels in thermal conversion processes such as combustion, gasification and pyrolysis. However, some types of biomass contain high levels of phosphorus, which can be released to the gas phase and cause operational or environmental problems. The mechanism(s) responsible for phosphorus release has not been convincingly established. Understanding the high-temperature phosphorus chemistry is also important in order to enable efficient recovery of phosphorus in residues from thermal conversion of biomass. In this work, the release of phosphorus from wheat bran char and sunflower seed char in different gas environments (100 % N2, 1–20 % O2, and 10 % CO2) and temperatures (900–1100 °C) was studied. The chars were converted in a horizontal tube reactor and characterized using ICP-OES, XRD, SEM-EDS, and 31P NMR. The release of ash-forming elements was determined using ICP-OES analysis of the char and sample residues, whereas the release of carbon was determined using CO and CO2 gas analysis. In both chars, phosphorus was present primarily together with potassium and magnesium, mainly as pyrophosphates in the wheat bran char, and largely as orthophosphates in the sunflower seed char. For wheat bran char, the release of phosphorus increased from 27 % at 900 °C to 71 % at 1100 °C in N2, whereas the release was at least 20 % lower in the oxidizing atmospheres (1–20 % O2, or 10 % CO2). The sunflower seed char reached a maximum release of 55 % at 1100 °C in N2. For wheat bran char, the molar ratio of released carbon/phosphorus was close to 2.5, which fits well with the theoretical value for carbothermic reduction of phosphates (P2O5(s, l) + 5C(s) → P2(g) + 5CO(g)). At 1100 °C, in N2, the release of phosphorus, potassium and sodium occurred mainly during the first 10 min. It was shown that KMgPO4, used as a model compound, could be reduced by carbon starting from 950 °C, but that some of the phosphorus remained in the condensed phase. The work provides a better understanding of phosphorus release and presents evidence showing that carbothermic reduction reactions can be an important phosphorus release mechanism for seed- and grain-based biomass char.

The Hansen solubility parameters (HSP) are frequently used for solvent selection and characterization of polymers, and are directly related to the suspension behavior of pigments in solvent mixtures. The performance of currently available group contribution (GC) methods for HSP were evaluated and found to be insufficient for computer-aided product design (CAPD) of paints and coatings. A revised and, for this purpose, improved GC method is presented for estimating HSP of organic compounds, intended for organic pigments. Due to the significant limitations of GC methods, an uncertainty analysis and parameter confidence intervals are provided in order to better quantify the estimation accuracy of the proposed approach. Compared to other applicable GC methods, the prediction error is reduced significantly with average absolute errors of 0.45 MPa1/2, 1.35 MPa1/2, and 1.09 MPa1/2 for the partial dispersion (δD), polar (δP) and hydrogen-bonding (δH) solubility parameters respectively for a database of 1106 compounds. The performance for organic pigments is comparable to the overall method performance, with higher average errors for δD and lower average errors for δP and δH.

The effect of gasification reactions on biomass char conversion under pulverized fuel combustion conditions was studied by single particle experiments and modelling. Experiments of pine and beech wood char conversion were carried out in a single particle combustor under conditions of 1473-1723 K, 0.0-10.5% O2, and 25-42% H2O. A comprehensive progressive char conversion model, including heterogeneous reactions (char oxidation and char gasification with CO2 and H2O), homogeneous reactions (CO oxidation, water-gas shift reaction, and H2 oxidation) in the particle boundary layer, particle shrinkage, and external and internal heat and mass transfer, was developed. The modelling results are in good agreement with both experimental char conversion time and particle size evolution in the presence of oxygen, while larger deviations are found for the gasification experiments. The modelling results show that the char oxidation is limited by mass transfer, while the char gasification is controlled by both mass transfer and gasification kinetics at the investigated conditions. A sensitivity analysis shows that the CO oxidation in the boundary layer and the gasification kinetics influence significantly the char conversion time, while the water-gas shift reaction and H2 oxidation have only a small effect. Analysis of the sensitive parameters on the char conversion process under a typical pulverized biomass combustion condition (4% O2, 13% CO2, 13% H2O), shows that the char gasification reactions contribute significantly to char conversion, especially for millimeter-sized biomass char particles at high temperatures.

The development and performance in practice of a commercial automatically controlled wood stove is described. The digital control system controls the three combustion air inlets individually, based on the combustion phase, measured flue gas temperature, measured O2 outlet concentration and desired room temperature. The control system ensured a well-controlled combustion cycle with respect to temperature and oxygen concentration, yielding improved thermal efficiency and minimized carbon monoxide emissions. A minimum in CO emissions was identified for the oxygen operation range 10–13% O2. The improved performance has been verified by field tests in 5 private homes, demonstrating more stable and optimal O2 concentrations and temperatures compared to manual operation. This resulted in significant lower CO concentrations (up to 27%) alongside higher thermal efficiency (up to 20%) when comparing manually and automatically controlled wood stoves. This new technology has a great potential for improving the stove efficiency/biomass utilisation and reducing the emissions of pollutants at low altitude close to private homes.

There is an immense potential for the computer-aided tools in the design of paints and coatings. Significant advances have been made, involving also the use of thermodynamic and in general property models for the study and theoretical formulation of these products. Algorithms and tools based on such models enable the formulation chemist to speed up the design process, by allowing them to focus their experimental efforts on a selected number of reliable constituents for the coating formulation. Even though model-based methods and tools can save resources and time required for the design, service life prediction and formulation of new products, the experimental validation cannot be done away with; as certain interactions in these complex systems can be accounted for only by using practical design procedures. Machine learning algorithms can, however, be used to improve the accuracy of predictive methods, if sufficient data on observed anomalies from physicochemical based theoretical predictions, is available.

Photocatalytic coatings have potential as an air purifying technology for removal of pollutants such as NOx gases, which are converted into and immobilized as nitrate via photo-oxidation. This work is an investigation of the photocatalytic conversion of nitrite into nitrate in the aqueous phase. The study of this reaction is important to understand the mechanism through which the immobilization of the NOx species as nitrates takes place during NOx conversion, especially in humid environments. We investigate the photocatalytic performance of TiO2 nanoparticles (Aeroxide® P25) and the corresponding photocatalytic coatings prepared using acrylic binder (TiO2 NP-acrylic) towards the photo-conversion of nitrite. The combination of a simple colorimetric method (Griess test) for nitrite quantification and UV–vis spectroscopy for nitrite and nitrate analysis is shown to be a useful method for monitoring the nitrite conversion. Photocatalytic tests with suspended TiO2 nanoparticles show that the nitrite conversion benefits from lower pH, higher temperature and higher concentration of the photocatalyst. The advantage of lower pH is attributed to electrostatic attraction between TiO2 with adsorbed H3O+ and NO2−, which facilitates transport of nitrite to the active surface. When the photocatalyst is immobilized in a coating the factor of primary significance is the pigment volume concentration relative to critical pigment volume concentration (λ), as the nitrite conversion increases linearly with λ in the range 0.6–1.2. This is attributed to the creation of a more porous structure that facilitates the access of nitrite and light to the active TiO2 surface sites.

Physical cleaning, an important factor in maintaining ships' hulls free from biofouling, can help to prolong the lifetime of fouling-control coating systems. This study investigated how mechanical cleaning parameters (cleaning force, duration and frequency) affected antifouling coatings' performance including fouling resistance property and cleaning efficiency using a specially designed manual cleaning system. Meanwhile, coating surface conditions, including visual appearance condition, roughness, contact angle were evaluated in detail. Biocide release rates of copper-based soluble antifouling paint (Cu-AF) under different cleaning conditions were also assessed by Scanning Electron Microscopy - Energy Dispersive X-ray (SEM-EDX) analysis. Results from the field testing in Danish sea area showed that cleaning frequency affected more than cleaning force and duration on antifouling coating performance. Algae glue attachment increased the difficulty in the cleaning of non-coated acrylic surface (A-BS) and fluorine-based copper free insoluble antifouling paint (F-AF). For Cu-AF coated panels, no significant mechanical damages were observed after cleaning. For F-AF, scratches formed on the coating surface after cleaning were more related to cleaning force and cleaning frequency. The biocide release rates of Cu-AF under various cleaning condition were between 15.7 and 24.6 μg Cu cm−2 day−1. Gentle cleaning of Cu-AF with proper frequency has little influence on the copper release rate. This study provides guidance on cleaning strategies for antifouling coatings.

Hydrocarbon intumescent coatings are an efficient means to passive fire protection of steel structures in high-risk environments such as petrochemical plants and offshore platforms. In the present study, the effects of zinc borate on the performance of hydrocarbon intumescent coatings were investigated. The analyses include steel temperature-time relationships and char expansion, as well as structural investigations and compositional profiles of the char. Furthermore, transient rheological coating behaviors and thermal degradation of the coatings were measured and analyzed. Results of furnace experiments, conducted under a standard hydrocarbon fire curve (UL1709), showed that a formulation containing 15 wt.% zinc borate gave the best performance. Fully expanded char measurements and the associated rheological recordings, evidenced that adjusting the zinc borate content from 0 to 20 wt.% increased the dynamic viscosity minimum of the incipient char from 6.2 to 5671.4 Pa⋅s. The increased dynamic viscosity resulted in a more uniform, but less expanded char layer. Compositional profiles of intumescent chars, measured using X-ray Diffraction, showed an increasing phosphate (especially BPO 4 ) content with increasing levels of zinc borate in the intumescent coatings. Finally, the thermogravimetric analyses revealed that zinc borate can help to reduce epoxy binder degradation and oxidation of the carbon-inorganic residue. Due to the health risks associated with borate and its compounds, there is a requirement to find alternatives. The present work has mapped out some of the beneficial properties of zinc borate, and the results may provide some insight as to how to formulate without these compounds in the future.

Calcium tannate was synthesized, characterized, and dispersed into an epoxy coating as an inhibitive pigment. Electrochemical Impedance Spectroscopy (EIS) was employed to monitor the anti-corrosive performance of the coating formulated with the as-prepared pigment after exposure to the salt spray chamber. Reference coatings with the commercial calcium phosphate pigment and unpigmented coating were also evaluated for comparison reasons. EIS results showed that epoxy coating pigmented with calcium tannate has higher coating impedance after 21 days of exposure compared with reference coatings, either unpigmented or calcium phosphate pigmented coatings. XPS analysis was employed for a deeper understanding of the inhibitive action of calcium tannate towards corrosion protection and verified the incorporation of tannate molecules in the protective film formed on the steel substrate under the calcium tannate pigmented coating.

The effect of a partial replacement of spherical zinc particles by stainless steel flakes (SSF) on the corrosion protection performance of zinc-rich epoxy (ZRE) coating was studied. Salt spray test, open circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization tests were utilized to evaluate the anticorrosion performance of the coatings. The results demonstrate that a partial replacement of zinc particles by SSF enhanced the anticorrosion properties of the ZRE coating, and the enhancement was attributed to the synergistic effects by increasing the coating impedance and extending the cathodic protection duration.

A methodology for product design of organic coatings is developed to help a formulator screen, modify, or design a paint formulation according to the desired functionality. The computer-aided product design (CAPD) method aims to improve and expand the current state of computer-aided coating formulation through a combination of databases and models capable of estimating various physicochemical properties. Additional paint-specific component interactions are considered, and new properties and estimation methods are included that better suit modern environmental, health, and safety-related considerations in the product design of paints. This work aims to provide a clear description of all property models, estimation methods, tools, and software used throughout the systematic framework. The solvent selection methodology is tested for several commercial paint formulations, using the original solvent mixtures to verify the results, while providing formulation alternatives to guide further experimental testing. For investigated case studies, the methodology provides both viable formulations and solvent selection alternatives. The suggested options can be used to retain key functionalities while lowering cost, substituting unwanted ingredients, or improving factors including health and safety, as indicated by lethal concentration, flash points, and biodegradability.

Experimental characterization and computational fluid particle dynamics (CPFD) simulations of a cold pilot–scale cement calciner were carried out to investigate the dispersion and heating of cold cement raw meal particles in the hot gas flow. During the experiments, the gas velocity and temperature were measured at different locations upstream and downstream of the place where the particles were fed to the calciner. The simulations were carried out using Eulerian–Lagrangian approach together with the Multi–Phase Particle–In–Cell (MP–PIC) method, based on the commercially available Barracuda Virtual Reactor® 17.1.0 software. For the particle–free flow, it was shown that the grid–independent velocity profiles predicted from the simulations are in proper agreement with the measured values. For the particle–laden flow, the simulation results from two drag models of EMMS and Gidaspow were compared with the gas temperature measurements and visual observations. The simulation results from the Gidaspow model exhibited an over–prediction of the amount of falling particles to the upstream regions. Both drag models exhibited a local minimum temperature region at a location slightly different from the measured one in a cross–section close to the particle feed position. For the Gidaspow model, a second low gas temperature region was observed at the opposite position of the particle feed that was not detected by the measurements. Overall, it is concluded that the Barracuda Virtual Reactor® software is able to capture the particle dispersion and gas–solid interactions in the studied pilot–scale calciner and the EMMS drag model is more reliable for prediction of the gas–solid flow.

Agglomeration is one of the main challenges for combustion and gasification of biomass in fluidized beds. Bed agglomeration is related to K species present in biomass. Understanding the role of different types of K species on formation of agglomerates at different conditions can reveal the mechanisms of biomass ash induced agglomeration. Extensive experiments are conducted in a laboratory scale fluidized bed reactor, using mixtures of quartz sand and K species, including KCl, K2SO4 and K2CO3, to study the agglomeration mechanisms. The effects of gas composition, including air, H2– and H2O– containing gas are investigated. The morphology and elemental analyses of the agglomerate samples are examined by SEM/EDS analysis. Thermodynamic equilibrium calculations are performed for verifying the proposed mechanisms. The results show that the role of various forms of potassium salts on agglomeration in fluidized beds is different. Gas composition also has strong impact on the agglomeration tendency. In the air and H2-containing gas, defluidization of KCl in a sand bed is caused by the melt of KCl. However, KCl reacts with SiO2 to form K-silicates in the H2O-containing gas, which results in a lower defluidization temperature. No defluidization is observed for K2SO4 in the presence of oxygen or water. However, K2SO4 decomposes and reacts with SiO2 to form K-silicates, causing defluidization at 850 °C in the H2-containing gas. In the air, H2– or H2O-containing gas, K2CO3 would react with SiO2 to form potassium silicates and KOH may be additionally formed in the H2– and H2O-containing gas. The possible mechanisms of agglomeration of various potassium salts at different conditions are discussed.

Conversion of single high density polyethylene (PE) particles has been studied by experiments and modeling. The experiments were carried out in a single particle combustor for five different shapes and masses of particles at temperature conditions of 900 and 1100°C. Each experiment was recorded using a camera. For selected experiments, the center and surface temperatures of the particles were measured using a thermocouple and an IR camera, respectively. During each experiment, the polyethylene particles went through melting, deformation, and decomposition. After the start of decomposition, the surface temperature became almost constant within the range of 480–550°C. The total conversion times of polyethylene particles were mainly influenced by the reactor temperature and particle mass, and the effect of particle shape was less significant. A non–isothermal 1D model was established and validated against the experiments as well as literature data. Furthermore, a simplified isothermal model appropriate for CFD applications was developed, in order to model the combustion of plastic particles in cement calciners. By comparing predictions with the isothermal and the non–isothermal models under typical calciner conditions, it is shown that the accuracy in prediction of the total conversion times of thermoplastic particles is within ± 30%, for particles lighter than 1000 mg.

Agglomeration is one of the operational problems in fluidized bed combustion of biomass, which is caused by interaction between bed materials (e.g. silica sand) and the biomass ash with a high content of potassium species. However, the contribution of different potassium species to agglomeration is not fully understood yet. In the present work, the reaction between K2CO3 and silica sand has been studied extensively by thermogravimetric analysis. The reacted samples were analyzed by SEM-EDX to reveal the reaction mechanism. The results indicated that the reaction occurs in a solid-solid phase already at temperatures around 700°C. The reaction rate increases with increasing temperature, but decreases with an increase of CO2 partial pressure. Using smaller particle size and well mixed solid reactants results in an increased reaction rate. It is observed that the reaction initiates in the contact area between K2CO3 and silica sand, forming a thin product layer. The layer acted as a reactive media further reacting with K2CO3 and silica sand. The results provide a basis for understanding of potassium induced agglomeration process in fluidized bed biomass combustion.

The use of TiO2 nanoparticles in organic-based photocatalytic coatings imposes several challenges: poor activity under visible light, binder photo-degradation, need for UV activation and toxicity concerns. Here we present a scalable two-step synthesis route to prepare TiO2-based hollow microspheres (HoS) as alternative photocatalyst to commercial TiO2 nanoparticles. The hollow microspheres of TiO2 or WO3-doped TiO2 (3 mol% WO3) are synthesized via template-assisted spray-drying followed by calcination. The structure and composition of the powders are characterized and their photocatalytic performance is assessed using methylene blue photo-degradation under UV irradiation as model reaction. XRD analysis reveals the presence of anatase and TiO2(B) phases, indicating the heterostructured nature of the samples. The results of the dye photo-degradation tests confirm the photocatalytic functionality of the TiO2-based HoS. Moreover, the introduction of WO3 (TiO2/WO3 HoS) leads to an enhancement of the performance, approaching that of commercial (Aeroxide P25, ~21 nm) nanoparticles. The most active TiO2/WO3 HoS are incorporated into an acrylic formulation and the resulting coatings tested towards pollutant abatement under UV light. A coating containing P25 nanoparticles undergoes an activation process where binder degradation leads to increased TiO2 exposure and a rise in catalytic activity but possibly at the expense of coating stability. By contrast TiO2/WO3 HoS-acrylic coatings exhibit catalytic activity similar to the initial activity of P25 containing coatings, but does not cause the same partial binder photo-degradation.

Rust creep is one of the most important criteria for the prequalification of anti-corrosive coating systems for offshore applications. The standard method for rust creep evaluation, as established in ISO 12944-9, is destructive in nature, which means that one panel only gives one reading of rust creep due to the removal of the coating beyond the rust area. Non-destructive methods allow for the evaluation of coating performance in a faster and more cost-effective way, i.e. the same coated panel can be tested over time and the propagation of the rust creep can be detected and monitored. In the present work, three methods based on ISO 12944-9, optical 3D Profilometry and Scanning Acoustic Microscopy (SAM) for rust creep assessment are compared and results show that the optical 3D Profilometry and SAM can act as complementary non-destructive tools which can provide efficient rust creep monitoring.

Loosely packed biomass dusts may self-heat and spontaneously ignite, especially when kept under elevated temperatures as in power plant mills. In this work, a mechanistic model was developed to predict self-ignition of biomass under such conditions. The model takes temperature- and gas phase species gradients into consideration. Reaction kinetic parameters were taken from a previous work, while material properties of biomass where found in the open literature. The model therefore did not require any parameter fitting. Model equations were discretized in one spatial dimension (here: for a cylinder). A series of lab scale experiments (10–40 g biomass dust) with beech, pine, sunflower husk pellets and wheat straw were used to validate the model. Predicted ignition temperatures were in good agreement (≈5% error) with experimental data. A sensitivity analysis showed the model to be most sensitive to reaction kinetic parameters, and to a lesser degree towards parameters influencing heat transfer. Mass transfer limitations (oxygen diffusion) did not appear to have a significant effect on the predicted onset of ignition. A scaling study showed sample size to have a larger influence on ignition temperatures than bulk density of the sample or oxygen availability. This study demonstrates that models based on chemical kinetics, heat- and mass transfer phenomena (as opposed to numerical correlations based on the Frank-Kamenetskii method) can yield accurate predictions of self-ignition temperatures. It also underlines the importance of finding realistic reaction kinetic parameters for low temperatures.

This work investigates the interactions in NOX chemistry during biomass co-combustion in a continuous lab-scale bubbling fluidized bed reactor. Co-combustion experiments were performed at air staged and unstaged conditions, and the gas composition in the flue gas and within the reactor was measured. The used biomass fuels were straw, sunflower husk, sewage sludge, and sunflower seed. Based on the NO concentration in the flue gas, straw-sunflower husk and straw-sunflower seed co-combustion were additive, while co-combustion of straw and sewage sludge revealed a synergy effect. The main cause was the presence of sewage sludge ash, which could catalyse the formation of NO from NH3 and HNCO, and possibly HCN. The catalytic effect of the ash increased with lower ash preparation temperature and better mixing of the ash with straw. During straw-sewage sludge co-combustion, the NH3 initially released from sewage sludge favoured the reduction of NO, while at later stages, when a significant amount of ash accumulated in the bed, the catalytic oxidation of NH3 to NO was dominant. Compared to air unstaged conditions, the NO emission was reduced and the impact of ash on the nitrogen chemistry was less pronounced at air staged conditions.

The performance of commercial intumescent coatings is assessed by industrial norms and standards with clearly defined experimental conditions. In contrast, academic research on intumescent coatings is much more diverse and there are no clear guidelines on how such coatings should be characterised. Some researchers transfer the conditions defined in the industrial standards to laboratory-scale setups while others rely on cone calorimeters or Bunsen burners. This might not be an issue when comparing different coating formulations within one study. However, it significantly complicates the comparison of coatings characterised with different experimental approaches and usually provides little insight into the coating performance under industrial fire test conditions. This review article gives an overview over different experimental approaches reported in the academic literature for the performance evaluation of intumescent coatings. The heating conditions in these different groups of setups, ranging from furnaces and ovens over radiative heaters to impinging flames, are elaborated in a tutorial style fashion. Besides the sample heating, in-situ characterisation techniques, such as measurements of char expansion, temperature, and mechanical strength will be discussed. The aim is to aid researchers in evaluating literature reports as well as stimulate the development of new and the optimisation of existing experimental approaches.

NO emission from two in–line cement calciners operating with petcoke and coal, respectively, is predicted through computational particle fluid dynamics (CPFD) simulations using the commercial software Barracuda Virtual ReactorⓇ 17.4.1. In the Eulerian–Lagrangian approach used in this solver, the solid phase is modeled using the Multi–Phase Particle–In–Cell (MP–PIC) method. The chemistry of gas phase combustion and NO formation/reduction is modeled using a global reaction kinetic set. Comparison of the predicted gas temperature and species concentrations against extensive full–scale measurements along calciner height, exhibits acceptable accuracy of the CPFD model. The conversion of solid fuel is underpredicted in the lower and upper calciner vessels for both calciners, while at the calciner exit, it is well–predicted. Further evaluation of the simulation results reveals dominant contributions of NO formation by char–N and NO reduction by char–C. As a result of higher volatile content of coal in coal–fired calciner, the contributions of NO formation/reduction by CHi radicals and HCN become more noticeable, compared to the petcoke–fired calciner. For both calciners, the overall predicted NO formation is greater than NO reduction, leading to a positive net NO generation. The net NO generation in the coal–fired calciner is almost half of that of the petcoke–fired calciner.

Coal/bio-oil slurry (CBS) is a new partial green fuel for bio-oil utilization. CBS reacts with gasification agents at high temperatures and converts into hydrogen and carbon monoxide. This paper provides a feasibility study for the gasification of CBS in an atmospheric entrained flow reactor for syngas production. Experiments have shown that CBS can be successfully processed and gasified in the entrained flow reactor to produce syngas with almost no tar content and low residual carbon formation. High reactor temperature and steam/carbon ratio is favourable for H 2 production. At 1400 °C with steam/carbon ratio of 5, the syngas components are similar with that in equilibrium. A synergistic effect exists between coal and bio-oil in coal/bio-oil slurry gasification which might be caused by the catalysis effect of alkali metals and alkaline earth metals in bio-oil.

The atomization characteristics of a commercial spillback hydraulic nozzle were investigated in terms of droplet sizes, velocities, trajectories and spray angles. To replicate the fuel spray of a commercial auxiliary marine boiler, an experimental setup was designed and used to atomize water-glycerol solutions with various viscosities. Droplet size, velocity, position and shape were obtained with a novel pulsating LED backlight imaging system that employs a CCD camera to capture pairs of frames with a delay as short as 1 μs from one another. The overall spray characteristics of the nozzle and distributions for droplet size and velocity were examined for the operating conditions currently used in the burner and by varying three parameters: pressure drop, flow rate through the nozzle and liquid viscosity. Results include droplet size and velocity distributions in different spray regions, a description of the influence of each varying parameter on global indexes such as the Sauter Mean Diameter and a comparison with traditional correlations for pressure swirl nozzles.

Mapping the performance of intumescent coatings as a function of concentration of ingredients is of great significance for formulation optimization. In this work, the effects of ammonium polyphosphate (APP), melamine (MEL), TiO2, CaCO3, and vitreous silicate fiber, were investigated on the fire-resistance performance of selected zinc borate (ZB)-containing and ZB-free hydrocarbon intumescent coatings with exposure to the hydrocarbon fire testing curve UL 1709. Owing to the promoted interactions of APP with epoxy binder and zinc borate, increasing levels of APP in the ZB-containing coatings enhanced the critical times of steel substrate and the formation of macroporous and compact char layers. In contrast, when increasing the content of MEL, the performance of the ZB-containing coatings generally declined, due mainly to the restricted char formation resulting from the decreased binder content. Among the investigated formulations, the coating with 25 wt.% APP or 5 wt.% MEL obtained the best performance. The oxides TiO2 and CaCO3, and the fiber barely had effects on the performance of the ZB-containing intumescent coatings, but the critical times and char appearance were strongly affected for the ZB-free coatings. Increasing the content of any of the three inorganics led to reduced expansion of the ZB-free coatings, but improved the chars with more mechanically stable structures. The longest critical times (e.g. to 550 oC) were found with the ZB-free formulations containing 1.5 wt.% TiO2 (87.7 min), 2.5 wt.% CaCO3 (86.3 min), and 5 wt% vitreous silicate fiber (85.1 min).

Wood devolatilization experiments in a single particle combustor and comparison with a 1D devolatilization model were carried out to investigate the effects of wood particle properties and operating conditions on wood particle devolatilization time. The experiments were conducted with 3 mm spherical/cubic and 4 mm spherical particles at gas temperatures of 1200–1450 °C and oxygen contents of 0–4.4 vol%. Both experimental and modelling results showed that the devolatilization time increases linearly with particle density for raw, wetted, and torrefied wood particles. A sensitivity analysis done with the 1D devolatilization model showed that the biomass devolatilization time is sensitive to particle size, moisture content, gas temperature and particle density, and insensitive to volatiles fraction and gas velocity under the investigated experimental conditions. Using the same devolatilization kinetics, the 1D model could predict well the devolatilization time of different wood species with different particle size, density and moisture content. With this in mind, a simple correlation for devolatilization time has been developed based on the simulation data from the 1D model. The correlation uses a four-variable function with inputs of particle size, moisture content, gas temperature and particle density to determine the devolatilization time of biomass. Experimental devolatilization time found in literature could be predicted within ±25% for large particles (1–10 mm) under high temperature conditions (1000–1600 °C).

The initial kinetics of the CaO/SO 2 reaction have been investigated for reaction times shorter than 1 s and in the temperature interval between 450 and 600 °C under both carbonating and non-carbonating conditions (0–20 vol% CO 2 ) to clarify how recirculating CaO influences the emission of SO 2 from a modern dry kiln preheater system for cement production. Calcined Faxe Bryozo limestone with a particle size smaller than 400 μm was utilized as CaO source. It was shown, both theoretically and experimentally, that the observed reaction rates were influenced by mass transport limitations. The results showed that the CaO conversion with respect to SO 2 declined when the CO 2 concentration was increased. Under all conditions, larger specific surface areas of CaO gave higher reaction rates with SO 2 . Higher temperatures had a positive effect on the reaction between SO 2 and CaO under non-carbonating conditions, but no or even a negative effect under carbonating conditions. The results led to the conclusion that SO 2 released from raw meal in the upper stages of the preheater does not to any significant extent react with CaO recirculating in the preheater tower.

Rapid and reliable rain erosion screening of blade coatings for wind turbines is a strong need in the coatings industry. One possibility in this direction is the use of discrete water jets, where so-called jet slugs are impacted on a coating surface. Previous investigations have mapped the influence of water jet slug velocity and impact frequency. In the present work, the effects on coating erosion of water cushioning, substrate curvature, and water nozzle-coating distance were explored. The investigations showed that in some cases water cushioning (the presence of a liquid film on the coating surface prior to impact) influences the erosion. Contrary to this, substrate curvature and the water nozzle-coating distance ( Mechanical measurements to characterize selected blade coatings, including tensile strength, flexibility, impact, hardness, and abrasion experiments, were also conducted. The ranking of abrasion resistance of the blade coatings was in agreement with the ranking of rain erosion resistance measured in the whirling arm rig (an industrial standard). Results of this work, with more pertinent parameters explored, confirm the conclusion from the previous investigation that a direct correlation of data from discrete water jet experiments with those obtained in the whirling arm rig does not seem possible (at least not for the blade coatings considered). The underlying mechanisms of rain erosion are substantially different in a setup based on impacting water jet slugs and a setup where a rotor arm impacts falling water drops.

Driven by the growth of the wind power industry during the last decade, the size of wind turbines has grown considerably and single-turbine power can nowadays reach a capacity of 8 MW with rotor diameters exciding 160 m. Rain erosion is a considerable threat to the mechanical integrity of the blades in such equipment. To reduce expensive blade maintenance repairs and to avoid out-of-service periods, energy-absorbing blade coatings are required to protect rotor blades from rain erosion. In this work we describe the design, construction and evaluation of a laboratory setup for fast screening of up to 22 coating samples that is based on water jet slugs. Our objective is to study the effect of the parameters involved in the rain erosion process and to correlate our experimental results with data obtained with the complex and expensive whirling arm rig, which has become the industry standard method of test for rain erosion. Our results showed that water slug velocity and impact frequency are the most influential parameters in the coating erosion rate. Coating defects, often present on the specimens tested, appeared to play an important role in the erosion mechanism. Two particular experimental blade coatings were investigated using the proposed experimental design. The evaluation of the coatings under conditions where impact frequency and water hammer pressure were “matched” could not be directly correlated with the results obtained with the whirling arm rig. This result may be attributed, among other contributing factors, to the different contact modes in the two setups, i.e. the movement of coated panels against rain drops versus the movement of water drops against coated specimens. Additional factors that require further investigation are the specimen geometries and the potential significance of the presence of a thin water film on the coated surfaces. Our results endorse the complex nature of the rain erosion phenomenon, which is the result of the simultaneous combination of complex mechanisms and as such, it is difficult to reproduce at the laboratory scale.

The gas/solid heat exchanger (2D-HX), developed to replace the cyclone preheaters in cement plants is presented. This design aims at reducing construction height and operation costs. The separation process in the 2D-HX is experimentally investigated, and the results show that separation efficiencies up to 90% can be achieved in the gravitationally driven process. Based on the data, a model of the separation process is developed, utilizing relations from pneumatic transport and cyclone theory. The model fit is acceptable, especially in the area of interest. Based on experimental data, further development of the technology is encouraged.

Protection of steel structures, using so-called intumescent coatings, is an efficient and space saving way to prolong the time before a building, with load bearing steel constructions, collapses in the event of a fire. In addition to the intumescent coating, application of a primer may be required, either to ensure adhesion of the intumescent coating to the steel or to provide corrosion resistance. It is essential to document the performance of the intumescent coating together with the primer to ensure the overall quality of coating system. In the present work, two epoxy primers were used to investigate the potential failure mechanism of a primer applied prior to an intumescent coating. The analysis was carried out using; (1) gas-fired test furnace, (2) a specially designed electrically heated oven, and (3) thermo gravimetric analysis. When tested below an acrylic intumescent coating, exposed to a gas-fired furnace following the ISO834 fire curve (a so-called cellulosic fire), one of the primers selected performed well and the other poorly. From tests in the electrically heated oven, it was found that both primers were sensitive to the film thickness employed and the presence of oxygen. At oxygen-rich conditions, higher primer thicknesses gave weaker performance. In addition, a color change from red to black was observed in nitrogen, while the color remained red in the oxygen–nitrogen mixture. In summary, the results suggest that an adequate choice of primer, primer thickness, and intumescent coating is essential for a good performance of an intumescent coating system.

The flowability of cement raw meal is investigated at temperatures up to 850 °C in a specially designed monoaxial shear tester. Consolidation stresses of 0.94, 1.87 and 2.79 kPa are applied. The results show that the flowability is reduced as temperature is increased above 550 °C, indicated by increasing unconfined yield strength and reduced flowability factors. Deviation and reproducibility are acceptable for all temperatures except for 850 °C where belite formation and possibly calcination sinter the raw meal.

The properties of slurries made of pyrolysis oil mixed with wood, char or ground char were investigated with respect to phase transitions, rheological properties, elemental compositions, and energy density. Also the pumping properties of the slurries were investigated at temperatures of 25, 40 and 60 °C and solid loadings from 0 to 20 wt%. The phase transitions of the wood slurry samples were observed at lower solid loadings compared to the char slurry samples. The apparent viscosity of the slurry samples was found to be considerably impacted by solid loading (0–20 wt%) and temperature (25–60 °C), especially in the phase transition region. The slurry viscosities with 20 wt% char loading, 20 wt% ground char loading and 15 wt% wood loading (at a shear rate of 100 s −1 ) are 0.7, 1.0 and 1.7 Pa.s, respectively at 60 °C and these values increases 1.2–1.4 times at 40 °C and 3–4 times at 25 °C. The wood, char and ground char slurry samples with 5–20 wt% solid loading obtain a volumetric energy density of 21–23 GJ/m 3 . The slurry sample with 20 wt% ground char having a d 80 of 118 μm was pumped successfully into a pressurized chamber (0–6 bar) while plugging appeared when the slurry samples with 15 wt% char having a d 80 of 276 μm was pumped into the pressurized chamber.

Computational particle fluid dynamics (CPFD) simulation is carried out to study the effect of petcoke and solid recovered fuel (SRF) co–firing in a full–scale cement calciner. The simulations are conducted using the Multi–Phase Particle–In–Cell (MP–PIC) approach with the Barracuda Virtual Reactor® 17.3.1 solver. The results from the CPFD simulation are compared with extensive field measurements of gas temperature and composition at several points in different calciner cross–sections. In the simulation, the SRF particles are divided into three components of plastic, biomass, and inert. The plastic particles go through drying, melting and decomposition while the conversion of biomass particles involves drying, devolatilization, and char oxidation. The predicted concentrations of O2 and CO2 are in good agreement with the measurements, while the gas temperature is overpredicted, especially in the lower calciner vessel. However, the trends of changes in the gas temperature are well–captured. The converted fuel fraction and calcination factor are predicted with an acceptable degree of accuracy. The simulation results show that large biomass particles in SRF tend to leave the calciner without complete conversion. Furthermore, a recirculation pattern for SRF particles is observed in the lower calciner vessel and the conical section, leading to high conversion degree of this fuel.

The HCl absorption by cement raw meals was experimentally evaluated in the temperature range 100-180℃, using a fixed-bed set-up and gas phase HCl content between 50ppmv and 200ppmv. The effects of temperature, gas phase composition and dispersion of raw meal particles on HCl absorption capacity of raw meals were studied. The obtained data are consistent with our interpretation of HCl absorption mechanism based on a surface saturation phenomenon that corresponds to a certain specific HCl absorption capacity of raw meal. The experimentally observed active compound conversions were significantly less than 1%. The dilution of raw meal samples using fused silica with particle size range 50–100 μm increased the apparent HCl absorption capacity of raw meal 10 times due to the elimination of raw meal particle agglomerates. The HCl absorption was slightly enhanced as the temperature was decreased from 180℃ to 100℃ in the case of dry gas phase tests. A dependence of raw meal HCl absorption capacity on the raw meal moisture content was detected at the same experimental conditions. The presence of 5% v/v H2O in gas phase increased the absorption capacity of raw meal A by 25% at 180℃ and by 61% at 100℃ relative to the absorption capacity from dry gas phase. The presence of 3% v/v O2 and 30% v/v CO2 in gas phase did not have any apparent effect on the HCl absorption in the investigated temperature range.

An efficient and space saving method for passive fire protection is the use of intumescent coatings, which swell when exposed to heat, forming an insulating char layer on top of the virgin coating. Although the temperature curves related to so-called cellulosic fires are often referred to as slow heating curves, special cases where the protective char is mechanically damaged and partly removed can cause extremely fast heating of the coating. This situation, for a solvent based intumescent coating, is simulated using direct insertion of free films into a muffle oven. The char formed is evaluated with respect to the mechanical resistance against compression, degree of expansion, and residual mass fraction. Experimental results show that when using this type of shock heating, the mechanical resistance of the char against compression cannot meaningfully be correlated to the expansion factor. In addition, char properties, measured at room temperature, were dependent on the preceding storage conditions (in air or in a desiccator). The char was found to have the highest mechanical strength against compression in the outer crust facing the heat source. For thin (147 μm) free coating films, a tendency to contract in the horizontal plane was observed. The experimental approach is relevant for testing of intumescent coatings used in buildings where moving or falling objects may damage the char during a fire.

article i nfo Trace element partitioning in co-combustion of a bituminous coal and a solid recovered fuel (SRF) was studied in an entrained flow reactor. The experiments were carried out at conditions similar to pulverized coal combustion, with SRF shares of 7.9 wt.% (wet basis), 14.8 wt.% and 25.0 wt.%. In addition, the effect of additives such as NaCl, PVC, ammonium sulphate, and kaolinite on trace element partitioning was investigated. The trace elements studied were As, Cd, Cr, Pb, Sb and Zn, since these elements were significantly enriched in SRF as compared to coal. During the experiments, bottom ash was collected in a chamber, large fly ash particles were collected by a cyclone with a cut-off diameter of ~2.5 μm, and the remaining fly ash particles were gathered in a filter. It was found that when coal was co-fired with SRF, the As, Cd, Pb, Sb and Zn content in filter ash/cyclone ash increased almost linearly with their content in fuel ash. This linear tendency was affected when the fuels were mixed with additives. The volatility of trace elements during combustion was assessed by applying a relative enrichment (RE) factor, and TEM-EDS analysis was conducted to provide qualitative interpretations. The results indicated that As, Cd, Pb, Sb and Zn were highly volatile when co-firing coal and SRF, whereas the volatility of Cr was relatively low. Compared with coal combustion, co-firing of coal and SRF slightly enhanced the volatility of Cd, Pb and Zn, but reduced the volatility of Cr and Sb. The Cl-based additives increased the volatility of Cd, Pb and As, whereas addition of ammonium sulphate generally decreased the volatility of trace elements. Addition of kaolinite reduced the volatility of Pb, while the influence on other trace elements was insignificant. The results from the present work imply that trace element emission would be significantly increased when coal is co-fired with SRF, which may greatly enhance the toxicity of the dusts from coal-fired power plant. In order to minimize trace element emission in co-combustion, in addition to lowering the trace element content in SRF, utilizing SRF with low Cl content and coal with high S and aluminosilicates content would be desirable.

An attractive option for reducing the net CO 2 emissions is to substitute coal with biomass in large power plant boilers. However, the presence of chlorine (Cl) and alkali metals (K, Na) in biomass may induce large operational problems due to ash deposit formation on the superheater tubes. The aim of this study was to investigate ash transformation and deposition behavior in two biomass-fired boilers, firing wheat straw and/or wood. The influence of straw firing technology (grate and suspension) on the ash transformation, deposit formation rate and deposit characteristics has been investigated. Bulk elemental analysis of fly ashes revealed that fly ash from suspension firing of straw has high contents of Si, K and Ca, while fly ash from straw firing on grate was rich in the volatile elements K, Cl and S. Investigations of deposit formation rates were made in the superheater and convective pass regions of the boilers by use of an advanced online deposit probe. During straw firing on grate, the measured deposit formation rate was close to 38 g/m 2 /h. Data from straw suspension firing showed a deposit formation rate of 41 g/m 2 /h. The deposit formation rates during straw suspension firing and straw grate firing were on similar levels. This was observed even though the concentration of fly ash in the flue gas was significantly higher during straw suspension firing. The influence of co-combustion of wood with straw on deposit formation rate, probe heat uptake and deposit characteristics was also investigated during suspension firing conditions. Data from 35% straw suspension firing with wood showed a deposit formation rate of 33 g/m 2 /h for the first 12 h. The deposit formation rate increased to 41 g/m 2 /h with 100% straw firing. The probe heat uptake reduction up to 40 h of exposure time was 3.0, 7.3, 8.4 and 16.5 kW/m 2 during 35, 65, 80 and 100% straw firing, respectively.

A novel filter reactor system for continuous production of selected pharmaceutical intermediates is presented and experimentally verified. The filter reactor system consists of a mixed flow reactor equipped with a bottom filter, to retain solid reactant particles, followed by a conventional plug flow reactor, where residual reactant is converted by titration. A chemical case study, production of the pharmaceutical intermediate allylcarbinol by a reaction between allylmagnesium chloride and 2-chloro-thioxanthone, in the presence of a side reaction is considered. The synthesis is conducted in tetrahydrofuran solvent. The use of the filter reactor design was explored by examining the transferability of a synthesis step in a present full-scale semi-batch pharmaceutical production into continuous processing. The main advantages of the new continuous minireactor system, compared to the conventional semi-batch operation, are reduced impurity formation and the use of much lower reactor volumes (factor of 1000 based on the laboratory reactor) and less solvent consumption (from 5.8 to 2.3 L/kg reactant). Added challenges include handling of continuous solid powder feeding, stable pumping of reactive slurries, and a possibility of continuous control.

The mixing of solid alternative fuel particles in cement raw materials was studied experimentally by visual observation in a pilot scale rotary kiln. Fuel particles were placed on top of the raw material bed prior to the experiment. The percentage of particles visible above the bed as a function of time was evaluated with the bed predominantly in the rolling bed mode. Experiments were conducted to investigate the effects of fuel particle size and shape, fuel particle density, rotary kiln fill degree and rotational speed. Large fuel particles and low-density fuel particles appeared more on top of the bed than smaller particles and high-density fuel particles. Fuel particle dimensions and sphericity were important parameters for the percentage of visible particles. Increasing bed fill degree and/or increasing rotational speed decreased the percentage of particles visible on top of the bed. Results can be up-scaled to industrial conditions in cement rotary kilns and show that even relatively large fuel particles will predominantly be covered by raw material after less than 30 s in the rotary kiln. This affects the heating and combustion mechanisms for the fuel particles.

Co-combustion of a bituminous coal and a solid recovered fuel (SRF) was carried out in an entrained flow reactor, and the influence of additives such as NaCl, PVC, ammonium sulphate, and kaolinite on co- combustion was investigated. The co-combustion experiments were carried out with SRF shares of 7.9 wt.%, 14.8 wt.% and 25 wt.%, respectively. The effect of additives was evaluated by maintaining the share of secondary fuel (mixture of SRF and additive) at 14.8 wt.%. The experimental results showed that the fuel burnout, NO and SO2 emission in co-combustion of coal and SRF were decreased with increasing share of SRF. The majority of the additives inhibited the burnout, except for NaCl which seemed to have a promoting effect. The impact of additives on NO emission was mostly insignificant, except for ammonium sulphate which greatly reduced the NO emission. For SO2 emission, it was found that all of the additives increased the S-retention in ash. Analysis of the bulk composition of fly ash from different experiments indicated that the majority of S and Cl in the fuels were released to gas phase during combustion, whereas the K and Na in the fuels were mainly retained in ash. When co-firing coal and SRF, approximately 99 wt.% of the K and Na in fly ash was present in water insoluble form such as aluminosilicates or sili- cates. The addition of NaCl, PVC, and ammonium sulphate generally promoted the vaporization of Na and K, resulting in an increased formation of water soluble alkalis such as alkali chlorides or sulphates. The vaporization degree of Na and K was found to be correlated during the experiments, suggesting an interaction between the vaporization of Na and K during pulverized fuel combustion. By collecting depos- its on an air-cooled probe during the experiments, it was found that the ash deposition propensity in co- combustion was decreased with increasing share of SRF. The addition of NaCl and PVC significantly increased the ash deposition propensity, whereas the addition of ammonium sulphate or kaolinite showed a slight reducing effect. The chlorine content in the deposits generally implied a low corrosion potential during co-combustion of coal and SRF, except for the experiments with NaCl or PVC addition. 2011 Elsevier Ltd. All rights reserved.

Self-healing materials have the ability to ‘repair’ themselves upon exposure to an external stimulus. In the field of coatings, extensive laboratory research has been conducted on these so-called smart materials in the last decade. In the present work, a self-healing concept for epoxy-based anticorrosive coatings, based on incorporation of microcapsules, filled with reactive agents, into the coating matrix, is investigated. Upon small damages to the coating, the reagents are released from the capsules and react, thereby forming a cross-linked network, which heals the crack. However, for the concept to work, microcapsules have to be strong enough to remain intact during storage and coating formulation and application. Furthermore, the capsules must remain stable for many years in the dry coating. Laboratory experiments, using four out of several encapsulation methods available in the literature, have been conducted to investigate the challenges associated with the synthesis of stable microcapsules. It was found that the nature of the core material strongly affects the microcapsule stability and performance. Furthermore, it was evident that experimental procedures developed for certain core materials were not suitable for encapsulation of other compounds without modifications. This is a severe limitation as not many of the encapsulation procedures have been developed for industrially relevant core materials such as epoxy resin. Results of experiments, aiming at finding optimal conditions for robust microcapsule production, are discussed.

Production of bio-oil, gas and biochar from pyrolysis of biomass is considered a promising technology for combined production of bioenergy and recalcitrant carbon (C) suitable for sequestration in soil. Using a fast pyrolysis centrifuge reactor (PCR) the present study investigated the relation between fast pyrolysis of wheat straw at different reactor temperatures and the short-term degradability of biochar in soil. After 115 days incubation 3–12% of the added biochar-C had been emitted as CO2. On average, 90% of the total biochar-C loss occurred within the first 20 days of the experiment, emphasizing the importance of knowing the biochar labile fraction when evaluating a specific biochars C sequestration potential. The pyrolysis temperature influenced the outputs of biochar, bio-oil and syngas significantly, as well as the stability of the biochar produced. Contrary to slow pyrolysis a fast pyrolysis process may result in incomplete conversion of biomass due to limitations to heat transfer and kinetics. In our case chemical analysis of the biochars revealed unconverted cellulosic and hemicellulosic fractions, which in turn were found to be proportional with the short-term biochar degradation in soil. As these labile carbohydrates are rapidly mineralized, their presence lowers the biochar-C sequestration potential. By raising the pyrolysis temperature, biochar with none or low contents of these fractions can be produced, but this will be on the expense of the biochar quantity. The yield of CO2 neutral bio-oil is the other factor to optimize when adjusting the pyrolysis temperature settings to give the overall greatest climate change mitigation effect.

Fine particles formed from combustion of a bituminous coal and co-combustion of coal with 7 th% (thermal percentage) solid recovered fuel (SRF) in a pulverized coal-fired power plant were sampled and characterized in this study. The particles from dedicated coal combustion and co-combustion both showed an ultrafine mode centered at approximately 0.1 μm. Compared with coal combustion, co-combustion of coal and SRF increased the formation of submicron particles, especially ultrafine particles below 0.2 μm. The morphology of the particles indicated that supermicron particles were primarily formed by the melting of minerals. The ultrafine particles were generated through nucleation and coagulation of vaporized inorganic species, while for the particles in between supermicron and ultrafine particles, condensation of vaporized species or aggregation of nucleates on the existing spherical submicron particles appear to be an important formation mechanism. The elemental composition of the particles from coal combustion showed that S and Ca were significantly enriched in ultrafine particles and P was also enriched considerably. However, compared with supermicron particles, the contents of Al, Si and K were depleted in ultrafine particles. The observed high volatility of Ca was likely related with the high combustion temperature and relative low oxygen condition in the boiler which may promote vaporization of Ca during char oxidation. The discrepancies on the observed volatilities of Ca and alkalis between some laboratory experiments and full-scale measurements were discussed. The composition of the fine particles from co-combustion was generally similar to those from coal combustion. The ultrafine particles from co-combustion were of slightly higher Ca, P, and K contents, and lower S content.

Solid oxide fuel cells (SOFC) systems with internal steam reforming have the potential to become an economically competitive technology for cogeneration power plants, exploiting its significantly higher electrical efficiency compared to existing technologies. Optimal design and operation of such a system require SOFC models that include accurate description of the steam reforming rate. The objective of this article is to review the reported kinetic expressions for the steam reforming reaction. Extensive work has been performed on traditional catalysts for steam reforming. Because of differences in operating conditions, catalyst support material and structure it is critical to transfer this knowledge directly to internal reforming in SOFCs, which is discussed in further detail in this article. There are big differences in the reported kinetic expression for steam reforming over both industrial Ni catalysts and SOFC anode materials. Surprisingly, there is a good agreement between measured rates pr. geometric anode area at high operating temperatures, even for very different anodes. Detailed experimental data on the intrinsic steam reforming kinetics of Ni-YSZ are necessary for micro structure SOFC modeling, such expression are however lacking, but it may be viable to use measurements on industrial steam reforming catalysts instead. Nevertheless there is a further need for experimental studies on determining the exact steam reforming kinetics for SOFC anodes.

Cathodic delamination is one of the major modes of failure for organic coatings immersed in seawater and refers to the weakening or loss of adhesion between the coating and the substrate. The diminished adhesion is the result of electrochemical reactions occurring at the coating–steel interface, where solid iron is oxidized to ferrous ions and oxygen is reduced to hydroxyl ions. In this work, the effects of various parameters on cathodic delamination have been investigated. The parameters are: permeability of the coating, concentration of dissolved oxygen and cations, polarization potential, type of binder, degree of curing, and pigment loading, shape and type. The results show that cathodic delamination increases with increasing concentration of cations up to the point where the concentration of dissolved oxygen becomes insufficient to maintain the corrosion rate. The rate of cathodic delamination is inversely proportional to the magnitude of polarization potential when ions can penetrate the coating, while cathodic polarization does not affect cathodic delamination when the ionic transport is restricted to the coating–steel interface. Increasing the pigment loading or partial replacement of spherical pigments with flake-shaped micaceous iron oxide or aluminium pigments reduces the rate of cathodic delamination. Finally, binders with an increasing amount of secondary hydroxyl groups in the polymer backbone reduce the rate of cathodic delamination while increasing the initial molar ratio of amide to epoxide increases cathodic delamination.

Hydrogen peroxide (H2O2) may be considered an environmentally friendly antifouling alternative to common biocides such as Cu2O and various organic compounds. In this work, the efficiency of antifouling coatings releasing hydrogen peroxide via enzyme-mediated conversion of starch, under Mediterranean and equatorial climatic conditions, is investigated. During seawater exposure of the coatings, starch is first converted to glucose by glucoamylase (rate-controlling step) and subsequently glucose is rapidly oxidised by hexose oxidase in a reaction producing hydrogen peroxide. The coatings formulated have been characterised in terms of common coating characteristics and immersed on rafts in seawater outside Singapore and Spain to monitor antifouling efficiency. The results have been compared to results previously reported from temperate waters in the North Sea outside The Netherlands. Using laboratory assays, the transient hydrogen peroxide release rate from the coatings at different temperatures has been measured. The investigations are used to evaluate the ocean performance of the antifouling coatings. Coatings can be formulated with starch/enzyme ‘pigments’ in considerable amounts and yet retain the mechanical properties required of an antifouling coating. However, the antifouling effect of the coatings immersed in seawater near Singapore and Spain, when inspected after 8 and 14 weeks, respectively, is insufficient. In comparison, previous studies under colder conditions showed an effect exceeding that of two commercial references over 67 days. The release rate of hydrogen peroxide from the coatings is shown to be greatly influenced by temperature, and therefore the results provided here suggest an antifouling effect that is highly dependent on the environment of the coating.

Product inhibition of cellulolytic enzymes affects the efficiency of the biocatalytic conversion of lignocellulosic biomass to ethanol and other valuable products. New strategies that focus on reactor designs encompassing product removal, notably glucose removal, during enzymatic cellulose conversion are required for alleviation of glucose product inhibition. Supported by numerous calculations this review assesses the quantitative aspects of glucose product inhibition on enzyme-catalyzed cellulose degradation rates. The significance of glucose product inhibition on dimensioning of different ideal reactor types, i.e. batch, continuous stirred, and plug-flow, is illustrated quantitatively by modeling different extents of cellulose conversion at different reaction conditions. The main operational challenges of membrane reactors for lignocellulose conversion are highlighted. Key membrane reactor features, including system set-up, dilution rate, glucose output profile, and the problem of cellobiose are examined to illustrate the quantitative significance of the glucose product inhibition and the total glucose concentration on the cellulolytic conversion rate. Comprehensive overviews of the available literature data for glucose removal by membranes and for cellulose enzyme stability in membrane reactors are given. The treatise clearly shows that membrane reactors allowing continuous, complete, glucose removal during enzymatic cellulose hydrolysis, can provide for both higher cellulose hydrolysis rates and higher enzyme usage efficiency (kg(product)/kg(enzyme)). Current membrane reactor designs are however not feasible for large scale operations. The report emphasizes that the industrial realization of cellulosic ethanol requires more focus on the operational feasibility within the different hydrolysis reactor designs, notably for membrane reactors, to achieve efficient enzyme-catalyzed cellulose degradation.