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A combination of experimental techniques was employed to test primary fragmentation and char particle attrition by abrasion during fluidized bed (FB) combustion of raw paper sludge (Raw-PS), hydrothermally treated paper sludge (HTT-PS), and a subbituminous coal (Sub-C), for comparison. The hydrothermal treatment (HTT) was conducted by a pilot-scale reactor at 197 °C (1.9 MPa) for 30 min. The results showed that all three samples extensively underwent primary fragmentation. Char attrition tests under inert conditions showed that Sub-C intensely experienced particle rounding off at the beginning, but after that it became very strong against mechanical abrasive attrition, followed by HTT-PS and Raw-PS, respectively. The oxidative char attrition tests showed that Sub-C exhibited an initial low amount of carbon elutriation rate followed by an attrition enhancement effect at later stages of burn-off, whereas for the Raw-PS and HTT-PS attrition was always lower than under inert conditions due to extensive postcombustion of fines. HTT-PS always produced a lower amount of elutriated carbon than Raw-PS and this indicates better combustion performance as well as lower unburned carbon emission. Finally, the Primary Ash Particle Size Distribution (PAPSD) of the three fuels was determined, showing that the paper sludge would contribute much more than coal to the ash bed inventory in a full-scale FB combustor. [ABSTRACT FROM AUTHOR]

This paper shows how chemical sludge (CS) generated during wastewater treatment at a paperboard mill can be quickly dried at low-temperature and employed in bark-fired boilers to reduce slagging and corrosion problems. By using a cyclone-dryer operated at an inlet-air velocity of 110 m/s and a temperature of 90 °C, the dry-matter content of CS was increased from approximately 19 to 82%. The residence time of CS inside the cyclone was approximately 2 s when using the inlet-air velocity mentioned above. Disaggregation of the feedstock caused by collisions with the cyclone wall and between particles played a crucial role in enhancing the efficiency of heat and mass transfer. Three co-pelletized mixtures of Scots pine bark (SPB) and dried-CS were combusted in a 40 kW fixed-bed burner. Flue gas analysis was performed with a gas analyser. Coarse and fine ash were analysed by SEM-EDS and XRD. NO x and SO 2 emissions increased with increasing amount of CS in the mixtures. Mono-combustion of SPB resulted in a large quantity of slag (i.e., molten ash) with a high degree of sintering (i.e., hardness of the slag), and ash deposits formed on heat transfer surfaces were rich in K 2 SO 4 and KCl. Mixtures of SPB and CS were less prone to slagging, and the amount of alkali chloride in the deposits was reduced in favour of alkali sulphate formation. Unlabelled Image • Chemical sludge was dried in a cyclone dryer operated at inlet-air temperatures of ~60–90 °C and velocities of ~60–110 m/s • The dry matter content of the sludge increased from 19 to 82% when the dryer was operated at 90 °C and ~110 m/s • Co-pelletized mixtures of Scots pine bark and dried chemical sludge were combusted in a 40 kW fixed-bed burner • NO x and SO 2 emissions increased with increasing amount of chemical sludge in the mixtures • All mixtures were less prone to slagging, and KCl in ash-deposits was reduced in favour of K 3 Na(SO 4) 2 formation [ABSTRACT FROM AUTHOR]

Reconstructing industrial waste slags as adsorbents to purify ammonium‐nitrogen and phosphorus wastewater is a promising method. However, owing to the tight structure, most slags only have a few exposed strong metal adsorption sites for limited treatment. Thus in this paper, paper mill sludge rich in both CaCO 3 and organic carbon was selected to construct a highly-active multi-porous carbon‑calcium nanocages adsorbent (Ca-p PSC 750). Activation test reflected that KOH intervention not only made sludge organic matter into multistage-pore carbon, but also facilitated the uniform distribution of active CaCO 3 nanoparticles. Adsorption results showed that the maximum removal capacity of Ca-p PSC 750 for NH 4 +-N and PO 4 3−-P was up to 248.9 and 104.1 mg g−1, more than 10 times that of the same kind of adsorbents. The whole adsorption process is not limited by the initial pH and coexisting ions of water. This work not only experimentally verifies the existence of a slightly-alkaline microenvironment on the surface of hierarchical pore carbon‑calcium nanocages adsorbents for the first time, but also eliminates the pH limitation of the adsorption reaction for pollutant remediation, thereby expanding the applicability of papermaking sludge adsorption technology. It provides a solution for the efficient purification of high concentration NH 4 +-N and PO 4 3−P wastewater. [Display omitted] • Synthesized a carbon‑calcium nanocage-type adsorbent from paper mill sludge. • A slightly-alkaline environment on the surface of hierarchical pore carbon‑calcium nanocages adsorbents. • The adsorption of NH 4 +-N is mainly through electrostatic attraction and ion exchange. • NH 4 +-N and PO 4 3−-P was removed in the form of crystal deposition. [ABSTRACT FROM AUTHOR]

Fluidized bed co-combustion of raw paper sludge (Raw-PS) and hydrothermally treated paper sludge (HTT-PS) with either low (Lo-Coal) or high reactivity coal (Hi-Coal) was investigated. The paper sludge was treated in a pilot-scale hydrothermal reactor at 197 °C and 1.9 MPa for 30 min. South African bituminous and Thai subbituminous coals were selected as representative of Lo-Coal and Hi-Coal, respectively. A 110-mm bubbling fluidized bed combustor was used in this study. During the steady combustion tests the nominal temperature was 858 °C, the fluidization velocity was 0.5 m/s, and the excess air was varied as 20%, 40%, and 60%. Both single fuel combustion and co-combustion were tested. Co-combustion tests were conducted by feeding the sludge at mixing ratios of 30% and 50% (mass basis) with coal. The main focus of this study was on NO x emissions and unburned carbon performance. Results showed that at 30% mixing ratio using HTT-PS instead of Raw-PS could reduce NO x emission by 3–6% and 9–17% in the case of Lo-Coal and Hi-Coal, respectively, and the loss of unburned carbon could be decreased by 15–18% and 36–53% for Lo-Coal and Hi-Coal, respectively. The particle size distribution of fly ash of all samples was similar regardless of the excess air variation. On the whole, the hydrothermally treated paper sludge showed better performance for co-combustion with coal and would be a better choice compared to the original raw paper sludge. [ABSTRACT FROM AUTHOR]

Kraft lignin, a side-product of the paper industry, is considered an attractive feedstock for the production of biorenewable chemicals. However, its recalcitrant nature and sulfur content render catalytic conversions challenging. This study demonstrates the efficacy of noble metal-based catalysts for the production of a lignin oil enriched in alkylphenolic and aromatic compounds, by a catalytic hydrotreatment of Kraft lignin without the use of an external solvent. Eight commercially available catalysts were evaluated using four different metals (Ru, Pt, Pd, Rh) on two supports (activated carbon and Al 2 O 3 ). The product oils were extensively analyzed by means of GPC, GCxGC-FID, GC–MS-FID, and elemental analysis. The catalysts were characterized by various techniques (N 2 physisorption, NH 3 -TPD, XRD and TEM) before and after reaction, and their physico-chemical properties were correlated with catalytic performance. Al 2 O 3 as support gave better results than carbon as support in terms of lignin oil yield and composition, due to a combination of higher total acidity, mildly acidic sites and a mesoporous structure. The metallic phase also significantly affected product distribution. The best results were obtained using a Rh/Al 2 O 3 catalyst, resulting in a lignin oil yield of 36.3 wt% on a lignin intake and a total monomer yield of 30.0 wt% on lignin intake including 15.3 wt% of alkylphenolic and 7.9 wt% of aromatic compounds, and with a sulfur content <0.01 wt%. [ABSTRACT FROM AUTHOR]

Polyacrylonitrile (PAN) based carbon nanofiber (CNF) papers have unique physicochemical properties including flexibility, good electrical conductivities, and excellent mechanical properties for supercapacitor electrodes. However, their surface-to-weight ratios and density of active sites on the surface are much poorer than those of other active carbons. Herein, a simple, renewable, multifunctional, and effective way is described to fabricate three-dimensional (3D) heteroatom-enriched porous PAN-based CNF papers by adding a moderate amount of microalgae-derived oil that has a large fraction of light compounds and nitrogen- and oxygen-containing functional components. CNF papers with enhanced porosity and large specific surface area, unique pore structure, and 3D heteroatom-enriched surfaces were successfully fabricated by stabilization and carbonization of PAN nanofibers with the algae oil. The as-fabricated algal-30% CNF paper is scalable and highly flexible as a free-standing supercapacitor electrode material and can deliver a specific capacitance of 272 F/g under a scan rate of 10 mV/s with noticeably high charge-discharge cycling stability, with 94% retained even after 10,000 cycles. The fabrication mechanism and the enhancement of the electrochemical behaviors of three-dimensional, heteroatom-enriched, porous CNF papers are proposed. Our work underlines the promise of algae oil-modified PAN-based CNF papers for high-capacity supercapacitor electrode materials. [Display omitted] • Microalgae is pyrolyzed, generating bio-oil, used for energy storage. • N- and O-doped carbon nanofibers with hierarchically micro- and mesoporous structure were prepared. • Binder-free electrodes prepared from algae-derived bio-oil exhibit excellent flexibility. • A specific capacitance of 272 F/g with noticeably high charge-discharge cycling stability was obtained. [ABSTRACT FROM AUTHOR]

Significant amounts of waste sludge and rejects are generated by pulp and paper mills, and stricter environmental regulations have made waste handling a global challenge. Thermochemical conversion of mechanically dewatered by-products is expensive and inefficient due to their high moisture content; therefore drying is a vital unit operation in waste management. This paper reports results from drying of light coarse fiber reject in a bench-scale cyclone that allows changes in geometry. For the sake of comparison, convective fixed-bed drying tests were also performed. The results showed that the drying rate in the cyclone was hundreds of times higher than in the fixed-bed. For cyclone drying, the inlet air velocity was the most important factor in both determining the drying rate and residence time of the material. This led to the hypothesis that grinding of the reject particles due to particle-wall and particle-particle collisions play a crucial role in enhancing the efficiency of heat and mass transfer. In addition to inlet air velocity, cyclone geometry was the main factor that determined particle residence time, as drying air temperature mainly determined drying rate. [ABSTRACT FROM AUTHOR]

Abstract: The main aim of this work was to study the chemical and ecotoxicological properties of ashes produced in a biomass boiler of a pulp and paper industry and evaluate possible differences depending on the particle size of bottom and fly ashes. This industry produces electricity by burning eucalyptus and pine bark in a bubbling fluidized bed combustor. Bottom and fly ashes and their size fractions, obtained by sieving, were analysed for a set of metals and leaching behaviour. The eluates were also submitted to ecotoxicological characterization, using five indicators. The highest concentrations of metals and metalloids were found in the lower particle size fractions of bottom and fly ashes. However, generally, it could not be observed any specific releasing pattern of metals depending on the particle size, except for fly ashes in which the releasing rate of some earth and alkali-earth metals seemed to increase for lower particle size fractions. No specific pattern of the ecotoxicity levels could be associated to the different particle size fractions of ashes. The fractions of bottom ashes with 4,000–10,000μm and >10,000μm have presented the lowest ecotoxicity levels. All the samples were classified as ecotoxic, except the fraction of bottom ashes >10,000μm. [Copyright &y& Elsevier]

The structural property of soot particles released during the pellet combustion of different municipal solid waste (MSW) was comparatively investigated through high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and X-Ray diffraction (XRD). The results showed under the same combustion condition, soot particles generated from different waste components have the same typical core-shell shape. But soot mass and aggregate morphology were strongly dependent on waste component material. When plastic (textiles) waste was burned, the soot obtained featured a much higher mass and more compact morphology with larger particle size compared to that from burning biomass and kitchen waste. Nanostructural characterization results revealed that paper and kitchen waste possessed the highest graphitization degree in soot, followed by wood waste, textiles, and plastic. Additionally, with the increasing addition of plastic in the mixed waste, the flame temperature was slightly reduced. And the soot was formed a lot and became more disordered in the nanostructure with shorter, more tortuous fringes and larger separation distances, which suggested a higher oxidation tendency. The A D1 /A G ratio had a linear relationship with the fringe separation distance and fringe tortuosity, with R2 values of 0.824 and 0.847, respectively. • Soot from burning municipal solid waste was comparatively studied. • Morphology and nanostructure varied largely among the soot samples. • Biomass fraction formed soot particles with well graphitic nanostructure. • Fringe characteristics play an important role in reactivity. • Plastic in mixed MSW enhanced the soot reactivity. [ABSTRACT FROM AUTHOR]

Studying pure ethanol spray flame has the potential to achieve the carbon neutrality vision. This paper studies the effects of fuel injection masses (12, 24, 36 mg) and fuel injection pressures (30, 40, 50 MPa) on ethanol spray flame on an optically visualized constant volume combustion chamber. Further compared with the spray flame of methanol and n-butanol. The combustion characteristics and flame development process were revealed by flame self-illumination high-speed imaging method, and the soot distribution was revealed by wavelength integration two-color method. Results show that ethanol spray flame presents an unstable yellow flame with many wrinkles. Small injection masses exist a partial flame-quenching phenomenon. As injection mass increases, the soot lift-off length decreases, and the flame brightness, soot concentration, and ignition delay increase. The high soot concentration areas locate upstream of the flame, and there is almost no soot downstream. Increased injection pressure increases the soot lift-off length and decreases the flame brightness. The ignition delay is shortened from 8.388 ms to 6.955 ms when injection pressure increases from 30 MPa to 40 MPa. But higher injection pressure has a negligible effect on reducing ignition delay. Finally, an ethanol spray combustion conceptual model is proposed. This paper gives particular guiding significance to the future use of carbon-neutral ethanol in diesel engines. • Ethanol spray flame exhibits a yellow unstable flame with many wrinkles • The KL factor of ethanol spray flame is in the range of 0–0.06. • There is almost no soot downstream of the ethanol spray flame. • Small injection masses exist a partial flame quenching phenomenon. • Higher injection pressure has small effect on reducing ignition delay. [ABSTRACT FROM AUTHOR]

Hydrogen (H 2) as a clean and environmentally-friendly carrier can be introduced as the fuel of future to mitigate the air pollution caused by industrial anthropogenic activities. With the aim of fulfilling the need of a green H 2 green production, disparate technological processes have been developed in current decades. Purposeful review of these H 2 production processes can allow the expert readers as well as non-expert readers to properly perceive the limitations and future perspectives for future research. H 2 may be manufactured from renewable or non-renewable energy sources. Despite significant advancements in the techniques of H 2 production, the emergence of various operational/technical challenges in obtaining a steady state and stable H 2 economy via increasing the process yield and decreasing production costs has motivated the researchers the study more to develop more efficient processes. Therefore, development of a scientific techno-economic analysis for all existed H 2 production techniques is of great importance to highlight the future perspective of this important energy source. The main objective of this paper is to comprehensively review the advantages and disadvantages of various H 2 production techniques. Moreover, the economic dimensions of each technique along with the role of nanotechnology in the production of H 2 are aimed to be reviewed in this paper. • Review of limitations and future perspectives for future research of H 2 production. • Operational/technical challenges in obtaining a steady state and stable H 2. • Techno-economic analysis for all existed H 2 production techniques. • The role of nanotechnology in the production of H 2. [ABSTRACT FROM AUTHOR]

This paper explores pyrolysis potential for effective modified biochar (MB) production, serving as a green and novel carbon-based catalyst support in Fischer-Tropsch to olefins synthesis. For this purpose, the MB produced from the pyrolysis of pre-treated Peanut shell (PS) and Cladophora glomerata algae (CG) was used as a high porosity support for cobalt catalyst synthesis. The impregnation technique was applied to prepare the cobalt catalysts, and the catalysts were promoted with potassium. Various methods examine catalysts physico-chemical properties. After 10 h of reduction at 400 °C, the catalysts' activity and selectivity were studied in a fixed-bed reactor. TEM images show that the metal particles are suitably distributed on the porous surface of the modified biochars. The majority of the particles were between 5 and 15 nm in size. Also, TPR results indicate a suitable metal dispersion of about 10% and good catalyst reducibility have been achieved. The cobalt catalysts produced on MBs of CG and PS exhibited FT rates of 0.245 and 0.223 (g HC/g cat.h), with CO conversion rates of 50.25% and 45.68% in each case. Finally, K-promoted cobalt catalysts supported on MBs of CG and PS showed the α-olefins selectivities of 38.67% and 35.49% for C2-C13 hydrocarbons, respectively. • Utilization of biomass-derived biochars contributes to sustainable catalyst development. • Promising pyrolyzed peanut shells and algal biochars as catalyst supports for high-performance olefin synthesis. • biochar supports offer novel and eco-friendly alternative to conventional metal oxide supports. • Potassium-promoted cobalt catalysts on modified biochar supports exhibit enhanced selectivity towards α-olefins. [ABSTRACT FROM AUTHOR]

Developing efficient and stable non-noble metal electrocatalysts for alkaline hydrogen evolution poses a challenge for current research. Herein, a novel hierarchical hetero-electrocatalyst of Ni 3 S 2 @2D Co MOF was synthesized with cobalt metal-organic frameworks (Co-MOFs) crystallization on carbon paper (CP) and in-situ electrodeposition of Ni 3 S 2 nanosheets. The catalyst Ni 3 S 2 @2D Co-MOF/CP exhibited an excellent hydrogen evolution reaction (HER) activity with a low overpotential of 140 mV and a small Tafel slope of 90.3 mV dec−1 at a current density of -10 mA cm−2. This catalyst demonstrated a lower overpotential (395 mV) than commercial Pt/C catalyst at a high current density (>130 mA cm−2). The efficient and stable HER performance of Ni 3 S 2 @2D Co-MOF/CP was attributed to nickel sulfide honeycomb nanosheets grown on two-dimensional MOF frameworks, which were conducive to charge transfer and hydrogen evolution. The electron-rich nickel sulfide surface significantly diminished H* adsorption and reduced energy barrier of H 2 generation to promote HER process. This work provides a new strategy for practical preparation of efficient and stable transition metal electrocatalysts. Schematic representation of hydrogen evolution reaction in alkaline solution over Ni 3 S 2 @2D Co MOF. [Display omitted] • A novel hierarchical hetero-electrocatalyst was synthesized to promote HER. • 2D Co MOF and Ni 3 S 2 contributed to synergistic catalytic effect on efficient HER. • The electron-rich Ni 3 S 2 surface significantly diminished H* adsorption. • Ni 3 S 2 @2D Co-MOF/CP exhibited a low overpotential of 140 mV at -10 mA cm−2. [ABSTRACT FROM AUTHOR]

Abstract Flue gas desulfurization (FGD) technology is now basically compulsory in the fossil power industry under the pressing environmental challenges globally, and the wet type of it particularly prevails thanks to the higher desulfurization efficiency than the dry type. However, the service conditions of wet FGD units are usually so harsh due to corrosivity and erosivity of the flue gases and the limestone slurries, which therefore drives special attention to the reliability of relevant equipment in the units. In this paper, to comprehensively command the degradation extent of one wet FGD unit in service, and especially to identify the causes of the failed components in the absorber, corrosion evaluation and failure analysis was performed on the four process systems of it during the overhaul. Then, by means of field investigation and multiple materials characterization methods, the vulnerable locations and components in the unit were revealed, and the causes of severe degradation and failure of them were clarified. Finally, related mechanisms were discussed in detail and pertinent recommendations were proposed point by point. Graphical abstract Flue gas desulfurization (FGD) technology is now basically compulsory for the fossil power industry under the pressing environmental challenge globally, and the wet type of it particularly prevails for the higher desulfurization efficiency than the dry type. However, the service conditions of wet FGD unit are usually so harsh due to corrosivity and erosivity of the flue gases and the limestone slurries, which therefore drives special attention to the reliability of relevant equipment in the unit. In this paper, to comprehensively command the degradation extent of one wet FGD unit in service, corrosion evaluation was performed on the four process systems of it during the overhaul for causes analysis of the failed components in the absorber, including limestone preparation system, boiler air and gas system, absorption system, and gypsum dewatering system, seen in Fig. 1. Then, based on the field investigation, the vulnerable locations and components in the unit were identified, and by means of multiple materials characterization methods, the causes of severe degradation and failure of them were clarified, such as erosion on the rubber liners of the pipe fittings, erosion and perforation on the support beams of the spray nozzles etc., as displayed in Fig. 2. Finally, related mechanisms were discussed in detail and pertinent recommendations were proposed point by point. Unlabelled Image Highlights • Comprehensively evaluated the corrosion and erosion conditions of the main systems of one wet flue gas desulfurization unit. • By means of field investigation, the vulnerable locations and components in the unit were identified. • Through material characterization, the causes of severe degradation and failure of the components in the unit were clarified. • The paper would provide technical support for degradation management and failure prevention of similar desulfurization units. [ABSTRACT FROM AUTHOR]

Abstract Circulating fluidized bed (CFB) boilers face sever challenges in China due to the new ultra-low emission rules, more specifically, the NOx emission must be lower than 50 mg/m3. In this paper, NOx evolution inside CFB furnaces and the gas-solid flow characteristics were reviewed. It is found that NOx emission can be reduced through re-specification of fluidization state, namely, improving the bed quality. A low NOx emission (de-NOx) technology applied to CFB boilers was thus proposed. The keys of the technology are decreasing the average size of bed materials, limestone included, and increasing the solid circulating rate by improving the performance of circulating loop including improving cyclone efficiency, controlling slag discharge, etc. Some industrial practices showed that when the average size of bed inventories is markedly reduced, and when using ultrafine limestone, NO x emission can be significantly decreased without undermining high efficiency desulfurization. This paper provides a new solution to low-cost pollution control of CFB boilers. Highlights • NOx emission can be reduced through re-specification of fluidization state, namely, improving the bed quality. • Using ultrafine limestone can relieve the contradiction between high efficiency desulfurization and de-NOx combustion. • A low NOx emission technology applied to CFB boilers was proposed. • Some industrial practices showed that the ultra-low NO x emission can be achieved by applying this technology. [ABSTRACT FROM AUTHOR]

Only when problems in ultrafine coal particle beneficiation process are well understood and clarified, efficient methods can be devised to recover ultrafine coal particles in an economically viable way. When minerals are fully liberated from organic substances in the grinding process, coal beneficiation methods are needed to efficiently separate organic materials from mineral ones. This is necessary for clean coal technologies as the pollutants associated with coal utilization are the key factor in limiting the sustainability of coal utilization. To assess the current state of knowledge available in this area, a comprehensive literature review on the ultrafine coal particle beneficiation techniques is carried out with main focus on recent progresses. In this paper, previous studies on the ultrafine coal beneficiation have been critically analyzed with respect to the effects of particle sizes and surface properties. The techniques are classified into two categories, physical separation (including gravity, magnetic and electrostatic separation method) and physico-chemical separation (including oil agglomeration and bubble flotation method). The aim of this paper is to review developments and limitations of current ultrafine coal particle beneficiation techniques and also to identify the future development in recovering ultrafine coal particles. [ABSTRACT FROM AUTHOR]

Two Cl-free refuse plastic and paper fuels (RPFs) produced by hydrothermal treatment with Ca(OH) 2 , as well as two biomasses, were co-fired with bituminous coal in a lab-scale drop tube furnace (DTF). The results indicate that the addition of biomass and RPF partially reduced the emission of SO 2 , which can readily cause corrosion, deposition and pollution. For the biomass co-firing, the particulate matter (PM) emissions from the black pellet (BP) series were 5.0% higher than those from the white pellet (WP) series because more sticky particles were formed with the increment of Ca-Al-Si and K-Al-Si, which absorbed alkali vapor and fine grains in the gas bulk to inhibit the PM emissions. For RPF, the major origins of sticky particles turned into Ca-Al-Si and Ca-K-Al-Si, the proportion of which was dramatically higher than that from the biomass, resulting in a stiffer suppression of PM formation. In general, the promotion of Ca from additives conversely restrained its transformation into PMs during both biomass and RPF co-firing. It can be concluded that the co-firing of RPF with bituminous coal provides an alternative approach to simultaneously control the emissions of greenhouse gases, gaseous pollutants and PM while remediating plastic waste. [Display omitted] • Co-firing of bituminous coal with RPF and biomass was investigated. • Ca transformation during co-firing dominated the formation of PMs. • The CCSEM + FactSage method can be applied to RPF. • The formation of sticky particles was predominantly influenced by M-Al-Si. • The addition of high-plastic fuel (HPF) reduced the emissions of SO 2 and PM. [ABSTRACT FROM AUTHOR]

Light aromatics, important organic intermediates, are mainly produced by naphtha reforming technology. However, recent attention has been focused on the development of processes that directly convert C 1 -C 6 to light aromatics due to the economics of C 1 -C 6 as a raw material. ZSM-5 is a potential catalyst for its excellent aromatization activity. The complexity of the internal chemical environment of ZSM-5 and the different interpretations of experimental results lead to the lack of a unified understanding of the molecular level details of the active sites and the reaction mechanism before and during the reaction. Therefore, in this paper, firstly, the widely studied Mo, Ga and Zn supported ZSM-5 were selected and the relationship between the anchoring sites or molecular structure of the metal and the catalyst activity in the preparation and reaction period was reviewed. Secondly, the activity and stability of Ga, Zn, Fe and B isomorphous substituted ZSM-5 were introduced. Finally, the controversy of monofunctional and bifunctional mechanism of ZSM-5 in alkane aromatization was discussed. This paper also provides suggestions for future research to fill the information gap found in the current literature. [Display omitted] • The structure and environment of metal sites in supported ZSM-5 were summarized. • The activity and stability of isomorphous substituted ZSM-5 were introduced. • The mono- and bifunctional mechanisms in the alkane aromatization were discussed. [ABSTRACT FROM AUTHOR]

Due to its strong fluidity and easy evaporation characteristic, high water-cut physical inhibitors (HWPIs) cause the decrease in moisture content of coal, so that its inhibitory effect on coal spontaneous combustion weakens or even fails. Aiming at solving the problem, this paper proposes to inhibit coal spontaneous combustion using thermo-responsive inhibitors (TRIs). These inhibitors are sensitive to specific temperatures and can retain their effects as long as the temperatures have not been reached. Besides, when the temperatures are reached, they are able to absorb heat and undergo physical and chemical changes to release H 2 O and inert gases (defined as gases that are not involved into the coal oxidation reaction in this paper) such as NH 3 and CO 2 , so as to inhibit the low-temperature oxidation of coal. Based on the temperature-programmed experiment of coal spontaneous combustion, this paper analyzed the effects of types and amounts of TRIs on coal spontaneous combustion by using differential scanning calorimetry (DSC), scanning electron microscope (SEM), thermogravimetry-derivative thermogravimetric analysis-differential scanning calorimetry (TG-DTG-DSC) and nitrogen adsorption test methods. The results show that CaCl 2 •6H 2 O achieves the most stable inhibitory effect, as its inhibiting rate rises steadily in the heating process to reach a maximum value of 79.9% at 200 °C. [ABSTRACT FROM AUTHOR]

In chemical-looping combustion (CLC), an oxygen carrier provides lattice oxygen for complete combustion of a fuel for heat and power production. The reduced metal oxide is then oxidized in a separate reactor. The combustion products CO 2 and H 2 O are obtained in pure form, without any nitrogen in the gas. As no gas separation work is needed, this could be a breakthrough technology for carbon capture (CCS). Normally, the fuel- and air-reactor are designed utilizing inter-connected fluidized beds. The same underlying reversible redox reactions of CLC can be used for other fuel conversion technologies. These include fluidized bed processes for gas, solid and liquid fuels for heat, power, syngas or hydrogen production. Some of these concepts were suggested as far back as the 1950's, while others have just recently been proposed. This paper will provide a review of some recent developments with respect to CLC with gaseous, liquid and solid fuels, with focus on operational experience. Today, more than 35 continuous units have been used worldwide, with over 9000 h of operational time. Although most experience has been reported for methane and natural gas, significant testing has now also been performed with various solid fuels. Some recent developments include i) shift from Ni-based materials to more benign metal oxide oxygen carriers, ii) use of different types of biomass and iii) operation at semi-commercial scale. Furthermore, this paper will also provide an overview some related technologies which also utilize oxygen carriers in interconnected fluidized beds: i) Chemical-looping gasification (CLG), ii) Chemical-looping reforming (CLR) and iii) Chemical-looping tar reforming (CLTR). In these processes, a pure syngas/hydrogen can be produced effectively, which could be utilized for chemical or fuel production. [ABSTRACT FROM AUTHOR]

The paper analyzes the combustion process of foamed emulsion on the basis of experimental research and phenomenological representations. The foamed emulsion represents a multiphase system consisting of oxygen bubbles dispersed in the oil-in-water emulsion. The research interest to such combustible systems is determined primarily by the fact that even at significant water content the foamed emulsion preserves its combustibility. This paper is mainly focused on the analysis of emulsion preparation methods (mechanical agitation or ultrasonic emulsification) and their influence on the foamed emulsion combustion. It is obtained that ultrasonic emulsification favors decrease in total burning rate of the foam and narrowing in concentration limits of flame propagation. An important role in flame acceleration in the foam belongs to the processes related with explosive boiling of liquid phase of the foam wherein oil drops could play a role of heterogeneous centers of nucleation for vapor bubbles. It is shown that if ultrasonic emulsification causes decrease in the sizes of oil drops in the emulsion below a certain critical value then the conditions for successive flame acceleration will be degenerated. [ABSTRACT FROM AUTHOR]

Soot has harmful effects on the environment and human health. The formation process of soot includes six steps: fuel pyrolysis, soot nucleation, coalescence, surface growth, aggregation, and soot oxidation. However, the formation of soot is very complex and is influenced by factors such as fuel type, combustion conditions, and environmental temperature. Oxygenated fuels additives have a positive effect on reducing soot emissions, but recent studies have shown that oxygenated fuels can lead to an increase in the number of small particles of soot. In this paper, the effect of oxygenated fuel additives such as alcohol, ether, and esters on soot emissions is discussed in terms of the mechanism of soot formation. Subsequently, the role of after-treatment systems in reducing soot emissions is summarized. This work can update our understanding of the impact of oxygenated fuels on soot emissions. • The mechanisms of promotion and inhibition effects of oxygenated fuels (alcohol, ether, and ester) on the generation of soot are discussed. • The formation process of soot and the conditions affecting its formation are listed. • Methods to reduce soot emissions have been exemplified and discussed. [ABSTRACT FROM AUTHOR]

In liquid discharging furnace, crystallization can occur in slags during the cooling process. The presence of crystal changes the structure, flow, heat transfer, especially the viscosity with a sharp increase. A deep understanding of the crystal kinetics is significant to optimize the flow of liquid slag. Crystal kinetics varies significantly with different slags due to the complexity and variability of the multi components in slags. In this paper, a high-temperature microscopy with high-resolution is used to clearly observe the in situ precipitation of different crystals and the kinetic parameters of different crystals are analyzed. Microscopic structure analysis of both the melt and the precipitated crystal shows that the proportion of basic oxygen structure and the diffusion coefficient of the basic cation in the melt have a direct correlation with the growth of crystal. A structural parameter St of the melt is developed, which has a positive correlation with the crystal growth rate. This is a new discovery in bridging the gap between the melt and precipitated crystals and it provides a way to control the crystal growth during slag cooling. • In situ crystals precipitation from silicate melts are observed. • A structural bridge between the melt and precipitated crystal is built. • A new melt structural parameter is proposed for crystal growth prediction. [ABSTRACT FROM AUTHOR]

The use of water as a part of hydrocarbon fuel represents one of the perspective directions in elaborating new types of combustible systems. This paper considers issues of foamed emulsion combustion on the basis of experimental research. Combustible foamed emulsion is a mixture of oxygen bubbles and heptane drops dispersed in a water solution of stabilizer. Such foamed emulsions possess a set of unique properties and represent a vivid example of multiphase combustible system which could contain a significant amount of water. Thus a foam containing 83 wt% of water is still combustible. Here we consider issues of foamed emulsion stability and combustion depending on the influence of magnesium oxide particles, stabilizer and glycerol concentrations. In this paper for the first time we are presenting that by addition of magnesium oxide particles the total burning rate of the foam can be changed for more than an order of magnitude. The dependence of total burning rate of the foam on the stabilizer concentration is not monotonic with a maximum at certain stabilizer content. The use of glycerol favors the shrinkage of the foamed emulsion and as a result the flame quenching. [ABSTRACT FROM AUTHOR]

In solid recovered fuel (SRF) production, type and nature of input waste stream influences the quality of fuel product. This paper presents the influence of input waste stream on SRF production in a mechanical treatment (MT) plant. The SRF was produced at industrial scale from three different types of waste streams: commercial and industrial waste (C&IW), construction and demolition waste (C&DW) and municipal solid waste (MSW). Here, the stream of MSW used for SRF production was energy waste collected from households. In the SRF production from MSW, higher yields of material were recovered in the form of SRF as compared with that of recovered from C&IW and C&DW. Of the input MSW to the MT plant, 72 wt% was recovered as SRF, equivalent to 86% energy recovery. The energy consumed to produce unit tonne of SRF from C&IW, C&DW and MSW was 1153 MJ, 1246 MJ and 1626 MJ, respectively. In the SRF production, removal of chlorine (Cl), lead (Pb) and mercury (Hg) from C&IW feedstock was worse than from C&DW and MSW feedstocks. In the SRF production from C&IW, of the input mass of chlorine, lead and mercury to the MT process 60%, 58% and 45%, respectively was found in the SRF. The SRF produced from C&DW contained the lowest mass fraction of the input chlorine, lead and mercury in comparison with the SRF produced from C&IW and MSW, namely 34%, 8% and 30%, respectively. Among the waste components rubber, plastic (hard) and textile (synthetic) were identified as potential sources of polluting and toxic elements, whereas wood, paper & cardboard and plastic (soft) were found to contain the lowest content of polluting and toxic elements. The pollutant and toxic elements investigated in this research work were chlorine, lead, cadmium, mercury and arsenic. [ABSTRACT FROM AUTHOR]

The continuous increase in industrialization has resulted in a high consumption of fossil fuels and increased concentration of pollutant gases. The unevenly high concentration of fossil fuel in some areas creates a supply disparity among the nations, with countries being forced to import fuel to keep up with their energy demands, burdening them economically. These rapidly exhausting conventional energy sources intensify the need for sustainable and renewable fuel, such as bioalcohols, to be produced globally. As the name suggests, alcohols produced from biological resources are called bioalcohols. This paper mainly focuses on methanol, ethanol, propanol, and butanol as alternate fuels for transportation, and their production through biomass using different thermochemical and biochemical paths. Properties of these alcohols such as octane number, cetane number, calorific value, flash point, cloud point, pour point, viscosity and density along with their effect on engine have also been examined. Alcohols in IC (internal combustion) engine are introduced by engine and/or fuel modification which includes techniques like dual fuel, fumigation, blending, emulsion and microemulsion. Addition of alcohols through these methods affect the performance characteristics and emissions profiles from the engine. It has been observed that upon the introduction of alcohol in the IC engine, the brake thermal efficiency and brake specific fuel consumption are generally increased while exhaust gas temperature, NO x and smoke emissions are reduced. Carbon monoxide and hydrocarbon emissions have shown mixed results according to the studies reviewed in this paper. The detailed review suggests that bioalcohols could potentially be used as an alternative fuel for transportation. [Display omitted] • Biochemical conversion of methanol and ethanol is relatively economical. • Bioalcohols have high octane number, and ability to improve cloud and pour points. • Fuel or engine modification influences performance and emission characteristics. • High enthalpy of vaporisation and low CV decrease NO x emissions but increase BSFC. • Alcohols help improve BTE and reduce emissions of smoke, HC, and CO. [ABSTRACT FROM AUTHOR]

This paper reports the use of piperazine promoted 2-amino-2-methyl-1-propanol (PZ + AMP) blended solution for the removal of high concentration CO 2 in natural gas (NG). The process behaviour was investigated by conducting the experiments in a bench-scale packed absorption column at high pressure conditions. The CO 2 concentration and temperature profiles along the column were presented in order to study the process behaviour in the column at various operating pressures, CO 2 concentration in NG, total gas flow rates, liquid flow rates, amine concentration and inlet liquid temperature. The temperature bulge was observed in the column and further discussed in this paper. [ABSTRACT FROM AUTHOR]

This paper introduces a novel process for the integration of pyrolysis and entrained-flow gasification for the as-mined Victorian brown coal containing 65 wt.% moisture. An initial mild pyrolysis of coal is proposed to reduce moisture content, and produce multiple products including char, tar and hydrogen-rich coal gas. Subsequently, the resulting water-free char is subjected to an entrained-flow gasifier, upon the blending of silica additive or high-ash bituminous coal. The resultant syngas passes through a cleaning unit and water gas shift reactor before mixing with the pyrolysis-derived gas to reach a target H 2 /CO molar ratio of 2.0 that is essential for the synthesis of a number of chemicals. In this paper, process simulation and exergy analysis were conducted to prove the advantages of the proposed process against the conventional drying–gasification combination. The results show that, the proposed pyrolysis–gasification integration process for Victorian brown coal possesses an exergy efficiency 4.5% higher than the drying–gasification process, and 1.5% higher than the drying case for another lignite containing 25 wt.% moisture. A prior removal of 20% of the inherent moisture can further improve the exergy efficiency by 4% for Victorian brown coal. The addition of 20% of black coal is the optimum ratio to improve the ash slagging propensity, as well as improve exergy efficiency compared to the conventional drying–gasification process. [ABSTRACT FROM AUTHOR]

This paper examines ignition features of coal–water slurry containing petrochemicals (CWSP). Fuel slurry composition is based on a filter cake (typical processing waste) of coal (grade K), water, scavenged turbine oil, and plasticizer. The novelty of this paper is that it indicates a joint influence of several droplets on the CWSP ignition characteristics in an oxidizer flow (air). Its temperature and velocity vary in the range of 400–1200 K and 0.5–5 m/s. These ranges are chosen so as to yield optimal results that can be used in various fuel technologies and waste recycling. The study examines the cases of two, three, four, and five droplets. It is considered that droplets are arranged differently relative to each other (in parallel, in series, and in rhomb) in the oxidizer flow. The distances between droplets are also different; here, they vary from 0.5 mm to 1.5 mm. The diameter of each droplet is about 1 mm. The study specifies the ignition delay time for CWSP. Special facilities, such as high-speed cameras, cross-correlation systems, a hollow glass cylinder (representing a combustion chamber), are used to monitor the basic parameters of ignition. Tema Automotive and Actual Flow software allow processing of the experimental results. Experiments demonstrate that the local sources of heterogeneous combustion are formed when CWSP droplets are burning. Such formation is characterized by some features, since droplets are spaced differently in the group relative to the oxidizer flow. Finally, the paper discusses the joint influence of neighboring droplets on the conditions and characteristics of their sustainable combustion. [ABSTRACT FROM AUTHOR]

This paper deals with the theoretical modeling of a high temperature reactor devoted to the thermal cracking of tars contained in a gas coming from a biomass gasifier. The aim of this paper is to give an insight into the chemical reactions that take part in this conversion but also into the reactions that may occur in such environment. The investigation is carried on using the simplest continuous reactor configuration that exists (completely stirred tank reactor), which allows to address the effects of chemical reactions without taking into account the mixing. This paper presents the complete set of reactions taken into account. It can also be noticed that this model also describes possible gasification of char particles entering the reactor. An in-depth analysis of the weight of the involved reactions is proposed for the nominal conditions of the reactor operation. The results of the model are also compared to the results of a previous one, highlighting the benefits of the actual model. These results are also compared to values obtained during operation of a pilot plant. Finally, the influence of five of the operating parameters of the reactor is theoretically investigated. It shows that these parameters can have an important impact on reactor operation, but also that conditions can be found that always lead to a conversion of at least 95% of the incoming tars. [ABSTRACT FROM AUTHOR]

This paper assesses the potential of plastics valorization by pyrolysis and in line catalytic dry reforming for syngas production. Previous studies showed the suitability of a continuous process made up of a conical spouted bed reactor for fast pyrolysis and a fluidized bed reactor for catalytic steam reforming. In order to step further in the application of this technology under dry reforming conditions, equilibrium simulation was approached to analyze process performance, as the development and optimization of this technology for the production of high-quality syngas requires understanding in detail the complex influence of process parameters. Thus, this study deals with the influence of main process parameters, namely, temperature, CO 2 /C ratio and the type of plastic, on the process performance. Furthermore, the role played by steam co-feeding in the dry reforming in order to adjust syngas H 2 /CO ratio was evaluated by varying the steam/carbon ratio. The obtained results clearly show that a strict control of process conditions is required to ensure high conversion to syngas and avoid undesired reactions, such as reverse WGS. Among the plastics studied, polyolefins are those of highest potential for syngas production, but polystyrene allows producing a high quality syngas through a combined reforming strategy. [Display omitted] • Pyrolysis-dry reforming process ensures the joint valorization of CO 2 and plastics. • Equilibrium simulation approach was used for the evaluation of plastics dry reforming. • The role of temperature, type of plastic, CO 2 /C and S/C ratios was evaluated. • H 2 productions higher than 11% can be obtained in the dry reforming of polyolefins. • Combined dry-steam reforming allows for tuning the syngas H 2 /CO ratio. [ABSTRACT FROM AUTHOR]

In this work, ReaxFF molecular dynamics (MD) simulation was adopted to investigate the effect of superheated steam on the conversion of the kaolinite-associated Barkol kerogen (BLK) and reveal the corresponding mechanism. The ReaxFF simulated weight loss rate (DTG) and release tendency of H 2 O, H 2 and CO 2 for BLK and the kaolinite-associated BLK agreed well with the results of Py-MS experiments. H-rich rate, double bond equivalents (DBEs), and hydrocarbon content were adopted to assess the quality of C 5 -C 40 , and configurations of C 40+ were extracted to investigate the characteristics of residues. And the H 2 O steam - and kaolinite-involved (steam refers to the superheated steam) reactions were analyzed. The results indicate that B- and L-acid sites of kaolinite co-catalyzed decomposition of BLK into heavy oil and shale gas in the kaolinite-pyrolysis system, and in steam/kaolinite-pyrolysis system, H 2 O steam further promoted decomposition of BLK into higher quality shale oil, especially for C 5 -C 13 components, remaining higher aromatic and porous residues. And this enhanced effect of H 2 O steam is attributed to kaolinite and the induced decomposition of H 2 O steam molecules and their participation as reactants in reactions in two aspects: i) interaction between kaolinite and H 2 O steam , on one hand, inhibited formation of L-acids and facilitated generation of B-acids to catalyze carbocation ion reactions process, further weakened dehydrogenation of organics catalyzed by L-acid sites, and enhanced cracking of residues catalyzed by B-acaid sites, on the other hand, promoted decomposition of H 2 O steam molecules to form H-rich environment and further weakened dehydrogenation of organics; ii) attacking C ar directly, H 2 O steam promoted shedding of alkyl side chains and ring-opening of aromatics to increase the –CH 2 – content in shale oil. This paper provides theoretical guidance for further understanding mechanism of H 2 O steam on pyrolysis of kaolinite-associated kerogen and corresponding catalyst development and preparation. [Display omitted] • The enhanced effect of H 2 O steam on pyrolysis of kaolinite-associated BLK was studied. • Rationality of ReaxFF simulation was guaranteed by Py-MS and FT-IR results. • Kaolinite catalyzed BLK pyrolysis into C 14 -C 40 with low quality of C 5 -C 13. • Quality of C 5 -C 40 and properties of C 40+ were enhanced with H 2 O steam injection. • Steam enhanced BLK pyrolysis by affecting bonds breakage directly and acid sites formation. [ABSTRACT FROM AUTHOR]

In this paper, aiming at PM 1, namely submicron particles which are the most difficult to remove in traditional purification technologies, it tries to improve their removal efficiency depending on collision enhancement and agglomeration effect. The effect of electric field and plate structure on collision enhancement is studied. Besides, a novel structure of corrugated plate is put forward and its removal performance is compared with parallel plate. Results show that it confirms the key function of the external electric field on the enhancement of particle collision through the trajectory visualization of particle streams with different polarity charging types. The intense turbulence quickens the particle collision and agglomeration in corrugated plate, and the enhancement of electric field around the bend can bring a quick capture firstly, and then the nonuniformity of electric field also leads to the positive effect of particle collision. Corrugated plate can achieve a 12% improvement of removal efficiency for PM 1 compared with traditional parallel plate, under consideration of collision enhancement brought by the airflow arrangement and agglomeration effect under Coulomb force between positive and negative particles. [Display omitted] • Collision enhancement in external electric field is investigated through visualization and simulation. • Corrugated plate proves to achieve a 12% improvement of removal efficiency for submicron particles. • Collision model based on Coulomb force is developed to study agglomeration effect. [ABSTRACT FROM AUTHOR]

The oxidation reaction order (n) and activation energy (E a) are the primary parameters in the global carbon/oxygen reaction model. However, these parameters continue to be a subject of argument due to the problems of experimental technology and kinetic analysis methods. This paper used a micro fluidized bed reaction analysis system to study the reaction kinetics of bituminous coal char with a median particle size of 75 μm at 923–1223 K and 2%–21% oxygen concentration. The effects of temperature and oxygen concentration on the combustion characteristics of char were analyzed. The real n value and main kinetic parameters in the n th-order Arrhenius model were measured, and the transition temperatures of the combustion control zone were determined. Results showed that the position of the maximum combustion reactivity occurs in the range of 20–30% of carbon conversion, which decreased slightly with the increase of temperature and increased slightly with the increase of oxygen concentration. The intrinsic reaction zone is below 1023 K, the intrinsic reaction order is between 0.64 and 0.71, and the intrinsic activation energy is about 106 kJ/mol. This study contributes to improve the precision and practicality of the n th-order Arrhenius model. • Measured the real reaction order n and main kinetic parameters of coal char by a micro fluidized bed system • Determined the transition temperatures of the combustion control zone, and the intrinsic reaction zone I is below 1023 K • The n value at the same conversion in the same combustion control zone is almost the same • In zone I n =0.64–0.71, activation energy E a =97–117 kJ/mol, pre-exponential factor A 0 =130–836 mol/(s·m2·atm n) [ABSTRACT FROM AUTHOR]

With the accelerated process of industrial modernization, the continuous emission of CO 2 seriously disrupts the natural carbon balance and contributes to global warming. To reverse this effect, CO 2 photocatalytic reduction has received increasing attention. Among various value-added products converted from CO 2 , methanol has been regarded as an excellent fuel alternative and desired energy storage form. This review summarizes the different catalytic materials explored for CO 2 photocatalytic conversion to methanol, and briefly describes the primary designing strategies for photocatalysts. Meanwhile, the fundamentals and mechanism of CO 2 photocatalytic reduction to methanol are briefly discussed. And the development course of CO 2 photocatalytic reduction to methanol has been attempted to organize. Furthermore, the paper tries to sort out the basic types of photocatalytic reaction systems with methanol as the product, and compares photocatalysis with other technologies that target CO 2 conversion to methanol. Finally, this work ends with the conclusions of the CO 2 photocatalytic reduction to methanol, and makes prospects for future development. [Display omitted] • Recent progress of CO 2 photocatalytic reduction to methanol was reviewed. • Primary photocatalytic materials for methanol production were discussed. • Design strategies of photocatalysts for methanol production were summarized. • Various reactors of CO 2 photocatalytic reduction to methanol were described. • Future perspectives of CO 2 photocatalytic reduction to methanol were presented. [ABSTRACT FROM AUTHOR]

With the green and economic development of distributed power source, the medium temperature flat-chip SOFCs using hydrogen rich gases obtained from MSR as fuel are paying great attention. The power generation performance and durability of SOFC are affected by the fuel composition. In this paper, the actual composition of hydrogen rich gas obtained from methanol steam reforming (MSR) is imitated to study the fuel adaptability of flat-chip SOFC at 600– 700 °C by experiment. As shown in the results fuel utilization rate and power generation performance are most affected by CO concentration. The large temperature gradient variation caused by the flat-chip structure leads to methanation reaction, especially when the hydrogen rich gas contains CO 2. Overpotential has a greater impact on the stack which use hydrogen rich fuel containing CO 2 as fuel. As the overpotential increases, the fuel utilization rate increases and the methanation rate decreases. The uneven performance caused by flat-chip production is the main reason for the difference in power generation performance. CO and CO 2 have a significant impact on the resistance of electrolytes of flat-chips. The reactor can stably supply fuel to SOFC for a long-time. Using reforming gas for power generation, fuel utilization rate of SOFC reduces by 0.06%. • The effect of hydrogen rich gas on fuel adaptability of flat-chip SOFC is studied. • The hydrogen rich gas obtained from methanol steam reforming reactor. • Fuel utilization rate and power generation performance are most affected by CO. • The temperature gradient variation leads to methanation reaction in the flat-chip. • Using reactor directly supply fuel for flat-chip SOFCs is feasible. [ABSTRACT FROM AUTHOR]

Stable free radicals are the long-lived macromolecule radicals formed in pyrolysis, and their reactions play an essential role in biochar formation. The alkali and alkaline earth metals (AAEMs) in biomass might be involved in the radical reactions during pyrolysis. Figuring out the effect of AAEMs on the reactions of stable free radicals can further understand the radical reaction mechanism and the formation of biochar in pyrolysis. In this paper, the in-situ electron paramagnetic resonance (EPR) spectroscopy was used to detect the stable free radicals in cocoanut pyrolysis, and the effect of AAEMs was analysed by the comparative experiments. The results indicate that the stable free radicals in nascent chars, which are generated from the thermal decomposition of biomass, could react and couple with each other. The AAEMs in biomass improve the activity of stable free radicals and promote the radical-radical coupling during high-temperature pyrolysis above 400 °C, which inhibits the condensation of aromatic structure and generates more weak bonds in hot nascent char. After stopping the heating, the weak bonds will be broken by cooling stress, thus inducing radical reactions and further changing the char structure. • In-situ EPR detection was used to study stable radicals during biomass pyrolysis. • Effect of alkali and alkali earth metals on stable radical reactions was analysed. • Nascent char formed in pyrolysis has secondary reaction after volatiles releasing. • Alkali and alkali earth metals promote coupling of stable radicals during pyrolysis. • Unstable structures formed by stable radicals coupling can be broken during cooling. [ABSTRACT FROM AUTHOR]

The development and utilization of bifunctional catalysts facilitated hydrogen-rich gas production from biomass pyrolysis to achieve high-value biomass conversion. The effects of different secondary metals (Fe, Mo, Ce) doping and Mo addition ratios on the performance of biomass catalytic pyrolysis for hydrogen production were investigated. The results showed that the Mo 0.5 Ni 1 Ca 7 catalyst had the best catalytic activity, where the H 2 percentage was 69.59 vol%, and the yield reached 617.57 mL g biomass − 1. The CO 2 concentration of the Mo 0.5 Ni 1 Ca 7 catalyst was reduced by 10.6% compared to the Ni 1 Ca 7 catalyst, which enhanced the adsorption performance of the catalyst. The intense interaction between Mo and Ca formed CaMoO 4 , which inhibited the formation of CaCO 3 and promoted the dispersion of the active phase. The Mo 0.5 Ni 1 Ca 7 catalyst had the largest NiO/Ni (OH) 2 ratio and Mo6+/Mo5+ ratio, further enhancing the catalyst's stability and catalytic activity. Considering the effect of pyrolysis temperature on H 2 concentration and yield, it was found that 600 °C was a relatively suitable catalytic pyrolysis temperature. This paper explored using Mo-modified catalysts in biomass catalytic pyrolysis for the first time, providing new ideas for developing bifunctional adsorption catalysts. Eventually, it provided a new way for biomass pyrolysis for hydrogen production technology. [Display omitted] • Corn cob pyrolysis for hydrogen-rich gas realizes high value utilization of biomass. • The Mo 0.5 Ni 1 Ca 7 catalyst has the largest NiO/Ni(OH) 2 and Mo6+/Mo5+ ratios. • The CaMoO 4 alloy enhances the catalytic activity and stability of the catalyst. • The CO 2 concentration of the Mo 0.5 Ni 1 Ca 7 catalyst was reduced by 10.6%. • The highest H 2 yield and conversion were 617.57 mL/g and 69.59 wt%, respectively. [ABSTRACT FROM AUTHOR]

In order to resolve the global warming problem, Ammonia-Diesel Dual-Fuel (ADDF) combustion has been a feasible strategy for burning ammonia to reduce carbon emissions from internal combustion engines. In the research of this paper, an ADDF engine experimental platform was developed and established. Premixed-Charge Compression Ignition (PCCI) combustion and diesel-piloted combustion modes under different operating conditions were investigated to achieve the goals of high thermal efficiency and low emissions. Moreover, the influence of diesel injection strategy and intake pressure on combustion, gaseous and particle emissions were explored. The results indicate that high thermal efficiency can be obtained using PCCI mode with early injected diesel, which forms a homogeneous mixture with ammonia under the low load condition. Under medium and high load conditions, less diesel was injected early, and ignition was delivered by a pilot injection of diesel close to the top dead centre. Under all operating conditions, the gross indicated thermal efficiency (ITEg) exceeded 48%, and the maximum ITEg was 51.5%, which was comparable to the diesel-only mode. Meantime, the emission of ammonia, NO and N 2 O were normally below 6 g/kWh, 7 g/kWh, and 1 g/kWh, respectively. With increasing ammonia energy substitution ratio, the particle emission changed from accumulation-mode particles to nucleation-mode particles, but the mass of accumulation-mode particles dominated. • As the load increased, the optimal combustion mode changed from PPCI mode to diesel-pilot mode. • The gross indicated thermal efficiency under different operating conditions exceeded 48%. • Nitrogen-containing emissions were controlled at a low level. • With increasing R AE , the particle emission changed from accumulation-mode particles to nucleation-mode particles. [ABSTRACT FROM AUTHOR]

Finding suitable alternative fuels and reducing carbon emissions are important development directions for future engines. Many carbon-neutral fuels, such as alcohol fuels are widely used, and they are more volatile than traditional diesel fuel. Therefore, exploring the development characteristics of spray flames and near-wall flames of different volatile fuels has important theoretical significance and application value for the optimization of fuel characteristics and the development of efficient and clean combustion technology. In this paper, the flame structure, flame development characteristics and soot evolution of three fuels, including n-hexane, 74% v n-heptane mixed 26% v isooctane (PRF26) and 53% v n-dodecane mixed 47% v isooctane (D53) were tested, that the cetane number of three fuels is essentially same. High speed self-luminous imaging and RGB two-color method were used to investigated the effect of fuel volatility on combustion. Results can be seen as following. Firstly, during the early stages of n-hexane combustion, a blue premixed flame can be found, and there is a pale-yellow flame in the later stage. As the boiling point increases, the area of the blue flame in the first stage gradually decreases, the area of the yellow flame in the later stage gradually increases, and the spatially integrated natural luminosity (SINL) of flame gradually increases. In addition, as the boiling point increases, the initial spontaneous combustion ignition point is away from the nozzle, the ignition delay time reduces and flame area becomes larger. Furthermore, the flame of high boiling fuels result in higher soot emissions. Secondly, in the event of flame wall-impingement, the near-wall flame of the three fuels has higher flame SINL and more soot formation in comparison to the free spray flame. The flame development of the three fuels is similar. However, there are some differences in the flame brightness distribution. The bright flame areas in n-hexane and PRF26 are concentrated near the wall, while the bright flame area in the D53 flame is concentrated on the wall and the flame head area rolled up with a larger distribution area. The flame near the wall is impacted by the wall temperature that the lower wall temperature leads to prolonged fuel evaporation and mixing time, which increases the ignition delay time. In conclusion, fuel volatility has less influence on flame structure and development, but a significant impact on ignition delay time and emissions. Regardless of whether wall impingement occurs, higher volatile fuels can extend the ignition delay time, increase the flame area and decrease soot emissions from combustion. • Fuel volatility has less influence on flame structure and development. • Fuel volatility has a large effect on ignition delay time and emissions. • As volatility decreases, the ignition delay time is shorter. • The flame of the high boiling fuels result in higher soot emissions. • The near-wall flame of the three fuels has more soot compared with free spray flame. [ABSTRACT FROM AUTHOR]

With the rapid development of industry, the diesel engine as a power source has brought many benefits in promoting economic growth and industrial automation. However, the diesel engine cannot underestimate the harm to air pollution and human health. Therefore, the requirements for the improvement of diesel engine emission standards are higher and higher. Since the introduction of emission regulations to limit the emission of harmful emissions from diesel engines to the environment, the diesel oxidation catalyst (DOC) has been an essential part of the diesel exhaust system. The DOC is one of the most significant catalysts for diesel engine aftertreatment catalysts. Its primary function is to oxidize unburned hydrocarbon (HC) and carbon monoxide (CO) produced in the combustion process into harmless water (H 2 O) and carbon dioxide (CO 2). At the same time, it can also convert nitric oxide (NO) in engine exhaust into nitrogen dioxide (NO 2) for passive regeneration of downstream diesel particulate filter (DPF) and improve the nitrogen oxide (NO x) conversion efficiency of selective catalytic reduction (SCR). This review covers the status, preparation methods, the influence and measures of sulfur dioxide (SO 2) on catalysts, and the methods of developing anti-SO 2 catalysts in the future of DOC. Firstly, the working principle and composition of DOC were discussed. Secondly, the preparation method and process of DOC were introduced. Thirdly, the development trend of DOC was analyzed. Then this paper focused on the impact of SO 2 on DOC and the measures to alleviate SO 2 poisoning. Finally, the possible methods of anti-SO 2 DOC design in the future were prospected. The work in this paper can effectively promote the application of DOC. Based on the work done in this paper, the researchers can efficiently select appropriate DOC according to the future research situation. [Display omitted] • Processes of preparation method and develop are listed. • Optimization applications in diesel engine are investigated. • The future trend of anti SO 2 catalysts is discussed. • Improvement suggestions for performance enhancement of diesel oxidation catalysts are proposed. [ABSTRACT FROM AUTHOR]

A promising way of upgrading bitumen is de-asphalting with the subsequent partial oxidation of asphaltene. Sulfur, metals (V, Ni), and other minerals concentrated in the asphaltene are subjected to reactions at elevated temperatures in both oxidizing and reducing atmospheres. Upon the cooling of the raw syngas, some of the particulate and condensable material deposit surfaces and ages. This paper discusses the subsequent deposition of layers on syngas cooler tubes. The deposit consists of a corrosion layer of FeS, a condensation layer of Ni 3 S 2, and subsequent fouling layers composed of V 2 O 3 and Ni 3 S 2 . Firstly, the base metal is corroded by the H 2 S electrochemical attack with the simultaneous Ni 3 S 2 condensation on the cold surface. With the increasing fouling thickness of the Ni 3 S 2 layer, the surface temperature at the process side increases, causing the condensation process to come to a gradual stop. Then infusible nanometer size V 2 O 3 particles with Ni 3 S 2 are deposited upon this sticky and rough surface, forming an extremely thick composite fouling layer. A high resolution inspection of this layer shows three sub-layers with distinct morphologies: (i) a fully molten liquid dense layer of Ni 3 S 2 with V 2 O 3 particles soaked below solidified into the smooth surface, (ii) very fine-grained (average particle size of 140 nm) spherical V 2 O 3 particles embedded within a melting Ni 3 S 2 sheet along with scale, where the spaces between the V 2 O 3 particles are filled with Ni 3 S 2 , and (iii) a fire side sub-layer consisting primarily of spherical V 2 O 3 particles wrapped by the condensed Ni 3 S 2 glue and keeping the original morphology of the particles in the syngas. The paper discusses the mechanism in detail. [ABSTRACT FROM AUTHOR]

Fuel quality is one of the most critical variables in determining the heat rate, efficiency, and performance of power plants. The drive to leverage fuel switching and/or blending to meet more stringent SO 2 and NO x emission requirements has, in many cases, led to both a reduction in power station efficiency and a poorer net plant heat rate (NPHR). In addition, fuel switching and/or blending can lead to a significant reduction in operating margins and increase the risk of unit derates. To maintain boiler efficiency and performance, there is a strong incentive to manage or mitigate this risk. A first step in evaluating fuel options is using the spreadsheet-based Fuel Quality Advisor . The Advisor incorporates fuel quality information, furnace operating conditions, as well as some basic furnace design information to estimate the maximum boiler load potential, fuel cost/MWh, deposition tendency, mercury compliance, ash resistivity, corrosion potential, and backpass erosion potential. The basics of the Fuel Quality Advisor have been presented earlier; this paper presents results from a major US utility who used the Advisor to evaluate over 70 fuels and fuel blends for 10 of their larger coal-fired boilers. Combining the estimated performance from the Fuel Quality Advisor with actual operating experience using the new fuels or fuel blends has permitted the Advisor to be tailored to each specific unit — thus increasing the reliability of the estimations. This paper discusses the use of the Fuel Quality Advisor by the utility as well as several of the resulting estimations and comparisons to actual operations. [ABSTRACT FROM AUTHOR]

The Heatpipe Reformer provides an allothermal gasification process for the generation of a hydrogen-rich synthesis gas. Heat pipes transport the heat from a fluidized bed furnace to the steam-blown fluidized bed gasification reactor. The goal of our institute is the generation of hydrogen from the synthesis gas by means of membrane separation in the fluidized bed reactor. The major requirement to ensure a high cold gas efficiency of the Heatpipe Reformer is a high efficiency of the combustor, which is determined by the used heat exchanger and the air–fuel ratio of the combustion. State-of-the-art is a cold gas efficiency of 70% with a combustor efficiency of 60–70%. For that reason the combustion chamber developed at our institute comprises of an efficient heat exchanger to internally recuperate the heat from the flue gas and ensure a high temperature of the primary and secondary air. Another consideration is the design of the secondary air inlet in order to allow a complete combustion of the fuel and low CO emissions. The paper describes the impact of the combustion chamber on the efficiency of the gasifiers cold gas efficiencies. It presents the current state-of-the-art of the heat pipe reformer as well as the current state of the construction of the 100 kW pilot at the Institute of energy process engineering (FAU-EVT). The paper shows experiments on the combustor discussing CO emissions and combustor efficiency in order to calculate a prospected cold gas efficiency of the whole system. Both, biomass and coal can be used as feedstock for the gasification system and results from combustor operation using lignite and wood pellets are shown. The combustion chamber provided CO emissions below 30 mg/m 3 . The internal air-preheater achieved temperatures of more than 500 °C. An analysis of heat losses finally indicates potentials for optimization of the Heatpipe Reformers cold gas efficiencies in the commercial scale. [ABSTRACT FROM AUTHOR]

Since sulfur release and capture processes during solid fuel combustion in circulating fluidized bed (CFB), especially in oxy-fuel conditions are very complex, the development of a simple SO 2 emissions model for a wide range of operating conditions both for large- and pilot-scale boilers is of practical significance. Previously established and validated [16-1-6-1] ANN model, which was published in the Part 1 of this paper was employed to predict SO 2 emissions from coal combustion in a large-scale 261 MW e CFB COMPACT-type boiler as well as in a pilot-scale 0.1 MW th OxyFuel–CFB test rig. The simulations are carried out using artificial neural network approach for different combustion environments, both in atmospheric and pressurized conditions. The study is conducted for air-firing, oxygen-enriched and oxy-fired combustion conditions. Therefore, four different combustion atmospheres are considered in the paper, where combustion runs in air and air enriched with oxygen (O 2 /N 2 mode) as well as in oxycombustion (oxygen-fired combustion) conditions, which mean the mixture of oxygen with CO 2 or recycled flue gas (RFG) with various fractions of oxygen (O 2 /CO 2 mode and O 2 /RFG mode, respectively). The obtained results show that the ANN model makes it possible to predict the SO 2 emissions from coal combustion in CFB boilers of different sizes and in different combustion environments. [ABSTRACT FROM AUTHOR]