The coal combustion process produces organic pollutants while generating conventional pollutants such as SO₂, NO_x and particulate matter. Due to the existence of a large number of pulverized coal combustion power plants, coal combustion accounts for about one-third of the total amount of anthropogenic non-methane volatile organic compound (NMVOC) emissions in China. However, previous studies on organic pollutants mainly focused on VOCs emissions from other sources, e.g. industrial sources and indoor environments. The formation and emission of organic pollutants during coal combustion is less discussed. The species emitted by coal combustion may be quite different from other non-combustion sources. The sampling and analysis methods also differ due to the complex composition of coal, the variable combustion conditions, and the harsh environment concerning the relatively high temperature, high humidity, and high dust-containing flue gas. In this paper, the organic compounds in raw coal, the formation and emission characteristics of organic compounds in the coal combustion process and the corresponding sampling and analysis methods were reviewed. The future work on coal-fired organic pollutants was also discussed.

Preparation of fuels and chemical materials through biomass chemical looping is an important direction in the field of engineering thermochemistry. How to effectively use chemical conversion to achieve efficient and clean utilization of biomass energy is a hot spot in industry and academia. This paper reviews the research progress from the aspects of chemical-looping combustion(CLC), chemical-looping gasification(CLG), chemical looping with oxygen uncoupling(CLOU), chemical-looping reforming (CLR), and chemical-looping hydrogen generation (CLHG), and focuses on the changes of physicochemical properties of oxygen carriers in the of biomass chemical looping conversion process (BCLP). The characteristics of reaction devices and systems were compared and analyzed. Based on the chemical characteristics of the main components of biomass, the influence mechanism of pretreatment and ash composition on the chemical looping conversion process should be investigated. The rational design and accurate construction of oxygen carrier based on electron and oxygen ion transport characteristics should be fully considered. The matching of reactor and intrinsic characteristics of the reaction on time scale and spatial scale, polygeneration system coupled with biomass chemical looping conversion technology and other engineering thermochemical technologies are several aspects that need to be addressed in further research.

This paper summarizes the research progress of waste tire pyrolysis technology in recent years, mainly discusses the pyrolysis technology of waste tires such as low temperature vacuum pyrolysis technology, co-pyrolysis technology and catalytic pyrolysis technology, and describes pyrolysis equipment, temperature, pressure and catalyst. Consequently, it is devoted to compare the influences of pyrolysis carbon black on pyrolysis reactors, temperature, pressure, catalysts, etc. In addition, the comparison of different modified upgrade methods are also investigated. Further recycle utilization of pyrolytic carbon black is also summarized.

Numerical simulation based on COMSOL Multiphysics was conducted to understand the heat transfer dynamics and reaction control mechanism over methanation catalyst particles in size of about 100 μm under conditions of transport bed. The high heat transfer efficiency in transport bed makes the catalyst particle into the bed quickly approach its steady state at about 0.1 s, a really very short transient period. For the catalyst particle at steady state there are temperatures sharing little difference among particle center, particle surface and gas flow bulk. However, it was clear that the temperature is still gradually lower from the center to surface of the particle, and on particle surface its temperature is higher than that in gas bulk. This clarifies that the exothermic heat of methanation reaction first heats catalyst particle, and the temperature-raised particle then reaches a balance of heat transfer with its surrounding gas. Calculating the radial profiles of temperature, gas components and reaction rate inside the catalyst particle clarified that for methanation at higher gas bulk temperature and elevated pressure (2 MPa here) the mass transfer into particles is quicker and the CO consumption rate becomes gradually lower from the center to surface of the particle. On the contrary, for atmospheric methanation at lower gas velocity, the reaction rate was conversely lower at the particle center. It demonstrates that the methanation reaction is subject to kinetic control for the former but to mass transfer for the latter.

Incomplete combustion of household coal is one of the major emission sources of particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs), which have caused serious harmful impacts on the atmospheric environment and human health. To evaluate the effects of coal types and their combustion methods on the PM and PAHs emissions, four different coals, namely bituminous chunk coal, bituminous coal briquette, anthracite coal briquette and semi-coke were respectively combusted in three typical household cooking and heating coal stoves (i.e. updraft stove, downdraft stove and decoupling combustion stove). Based on the experimental results, the toxicity equivalents (TEs) were calculated and compared with the data reported in the literature. With the decoupling combustion stove, the emission factors of particulate matter (EF_PM) and polycyclic aromatic hydrocarbons (EF_PHAs) were measured to be 0.50 g/kg and 403.2 μg/kg for the bituminous coal briquette, 3.65 g/kg and 989.6 μg/kg for the bituminous chunk coal, 1.08 g/kg and 622.3 μg/kg for the semi-coke and 2.10 g/kg and 148.3 μg/kg for the anthracite coal briquette. Clearly, the bituminous coal briquette combustion produced significantly lower PM and PAHs than combustion of other coal types, except for the EF_PAHs of the anthracite coal briquette. With the same bituminous chunk coal combusted, the EF_PM and EF_PHAs were determined as 3.65 g/kg, 989.6 μg/kg for the decoupling stove, 46.58 g/kg and 16182.3 μg/kg for the updraft stove, and 6.00 g/kg and 11749.4 μg/kg for the downdraft stove, strongly suggesting that the combustion methods have an even bigger impact than fuel type on the emissions of PM and PAHs. Furthermore, the experimental data showed that the decoupling stove burning the bituminous coal briquette produced the lowest PM and PAHs, with the EF_PM and EF_PHAs being 0.50 g/kg, 403.2 μg/kg, followed by the updraft stove burning the semi-coke (EF_PM 1.62 g/kg, EF_PHAs 1196.5 μg/kg) and the updraft stove burning the anthracite coal briquette ( EF_PM 1.32 g/kg, EP_PHAs 66.5 μg/kg). All of these were significantly lower than the data from the updraft stove burning bituminous chunk coals, which were 46.58 g/kg and 16182.3 μg/kg from this study and 0.68－24.3 g/kg and 680－137700 μg/kg reported in the literature. The results indicated that the emissions of PM and PAHs were affected by both the combustion methods and the coal quality characteristics, and the efficient combustion played a greater role in reducing the emissions. The “coal stove matching” technology can make rational, effective and clean utilization of China s huge reserves of bituminous coal resources.

The Ni-Ce/Al₂O₃ catalyst was synthesized via mechanochemical method. The effects of steam on the cracking behavior of toluene and pyrene as coal tar model compounds were investigated in a fixed bed reactor. Based on the product distribution, the cracking mechanism of the conversion of pyrene to naphthalene was proposed and verified by D₂O as a tracer. The types and structural characteristics of carbon deposition on the spent catalysts were characterized by XRD, TG-DTG and Raman, etc. The results showed that the addition of steam obviously enhanced the cracking rate of pyrene, compared with the pure nitrogen atmosphere, and it increased first and then decreased with the increase of steam-carbon ratio (S/C) and reaching a maximum of 98.93% at S/C=0.15, increased by 32.09% in comparison with S/C=0. A downward trend was that the yield of carbon decomposition decreased from 10.04% to 5.39% with the increase of S/C ratio from 0 to 0.26. In addition, carbon analysis results show that the main type of carbon deposits were β-type and γ-type at S/C=0. On the contrary, in the presence of steam, the activity of higher α-type carbon content increased. Therefore, it indicated that the carbon elimination by steam inhibited the conversion of C_α to C_β and C_γ.

The ash fusion temperature of coal at high temperature is an important parameter for the efficient and safe operation of coal gasifiers. The equipment of ash fusion temperature was used to measure the ash fusion temperatures of the oxide components composed of SiO₂, Al₂O₃, Fe₂O₃, MgO, and CaO with different proportions. Five variables composed of Si/Al, Si+Al, Fe₂O_3, MgO, and CaO were selected to verify the effect of the change on the coal ash fusing characteristics and the range of variables cover most domestic coal ash. Factsage was used to calculate the liquidus temperature of coal ash components, and to obtain the solid phase ratios of each crystal in each slag system and the simulation results are verified by experiments. With the contents of CaO, Fe₂O₃ and Si/Al increase, the ash fusion temperature gradually decreases while with the content increasing of Si+Al and MgO, the ash fusion temperature of the coal ash gradually increases. The ash fusion temperature varied with the contents of the oxide components and was closely related to the corresponding liquidus temperature, which was always higher than the ash fusion temperature about 200℃. Factsage was also used to predict the crystal compositions of the slag system at different temperatures. It could be concluded that there was no necessary relationship between the transformation of different slag systems with the change of a certain variable, and further analysis was needed for the slag system dominated by a specific factor. In the crystal phase experiment, after the slag was fused, quenching could be performed quickly to maintain the original crystal form at the high temperature. When X-ray diffraction analysis was completed, the precipitation ratios of different crystals at various temperatures could be obtained, which was in good agreement with the simulation results. The differences between the simulation and experimental results were also explored. The effects of different oxide compositions on the slag solidification ratios were investigated. The conclusion of this paper lays a foundation for further analysis of the product and characteristics of the molten state of multi-oxide system, and is of great significance for the optimization design operation of gasifier.

To enhance the mass transfer efficiency of bio-oil inside the zeolite based catalyst and improve the catalytic selectivity of jet biofuel product, conventional Y zeolite was modified into hierarchical mesoporous Y (meso-Y) zeolite by desilication and loaded with Ni to catalyze the conversion of fatty acid methyl ester (FAME) into jet biofuel. Mesopores in the range of 2 to 10 nm were effectively generated by desilication with NaOH and a certain degree of crystal structure expansion was caused accordingly. When Ni was loaded on meso-Y zeolite treated with 0.4 mol/L NaOH for 1 h, BET surface area and specific pore volume were increased to 554.9 m²/g and 0.340 cm³/g, respectively. A maximum of jet biofuel product selectivity (65.8%) was hence obtained. Iso-alkanes and arenes took up 19.1% and 12.8% within jet biofuel product, guaranteeing the fuel characteristics. As by-products of both hydrodeoxygenation and hydrocracking, the selectivity of CH₄ in the gas phase product was up to 25.2%, and the CO₂ is stable at about 12%. Although the overall selectivity of jet biofuel product varied greatly with NaOH treatment duration, the proportion of each component remained stable. Desilication only modified the physical structure of meso-Y zeolite to enhance the mass transfer of reactants and products. Its chemical properties were preserved to maintain the catalytic activity.

The calcination reaction characteristics and reaction kinetics of magnesite powder in nitrogen and air atmosphere were studied by microfluidic bed reaction analyzer (MFBRA) and thermogravimetric analyzer (TGA). It was shown that the activation energy of magnesite calcination measured in nitrogen and air was quite similar, indicating that the oxygen in the air had little effect on the calcination of magnesite. The time for complete decomposition of magnesite in MFBRA was short as a few seconds in MFBRA at temperatures above 800℃, showing its reaction rate much quicker than that in TGA，which revealed the difference between TGA and MFBRA in measuring the reaction kinetics. Both activation energy and pre-exponential factor are significantly lower in MFBRA (about 125 kJ/mol, 10⁵ s^-1) than in TGA (about 200 kJ/mol，10¹⁵ s^-1). The gas product CO₂ produced by magnesite decomposition is difficult to fully flow out from the crucible of TGA and thus inhibits the decomposition reaction of magnesite. For MFBRA, it can effectively reduce the inhibition effect from the formed CO₂ that easily flows into the main gas flow surrounding the particles. It is also found that the magnesite decomposition reaction follows the nucleation and growth control model in both MFBRA and TGA. Overall, for the reaction in fluidized beds, the study verifies that MFBRA provides a reliable secure of the reaction rate and kinetic parameters for the gas-formation calcination or decomposition reactions like tested light calcination of magnesite.

Based on energy integration, the process of chemical absorption of CO₂ is coupled with the flue gas waste heat recovery unit, and is optimized by self-heat recuperation to minimize the exergy loss of the high energy-consuming unit in the capture process, and the process was modeled by using computer simulation software Aspen Plus. The optimized process uses the heat recovery of the reaction heat released from the capture process for the endothermic reaction in the desorption process, realizing the recovery of reaction heat in the capture process. Meanwhile, by compressing the waste steam to recuperate the heat, which is exchanged with the liquid vaporization heat; flue gas waste heat and lean amine energy are rationally utilized. Moreover, the recuperated heat results in the reduction of the energy consumption for the desorption process so that the additional heat requirements are reduced in the capture system. The simulation results show that the optimized energy consumption of the capture process is 1.46 GJ/(t CO₂) and the energy saving is about 41.36%. The economic evaluation of the process is performed by the investment cost with the operating cost. As a result, the total cost of the optimized capture process is 326.70 CNY/ (t CO₂), which is 12% less than the traditional chemical absorption method. It indicates that the self-heat recuperation has great energy saving potential and could solve the sharp contradiction between the energy supply and the demand for a practical process.

The effects of intrinsic minerals and three inorganic components (CaO, Fe₂O₃ and Al₂O₃) on the semi-coke combustion reactivity of maceral with different reducibility were investigated on a thermogravimetric analyzer. The results indicated that the combustion reactivity of maceral chars from the weakly reductive coal is better than that from the reductive coal. The inherent mineral matter of vitrinite reduces the ignition temperature of vitrinite chars, while the inherent mineral matter of inertinite shows obvious inhibition effect on their chars combustion reaction. Three added mineral matter inhibit the combustion reaction of maceral chars from the reductive coal, and the relative inhibiton sequence could be described as follows: Al₂O₃>CaO>Fe₂O₃, while CaO has a little catalytic effect on the combustion reaction of maceral chars from the weakly reductive coal, and the inhibition effect of Al₂O₃ and Fe₂O₃ on the combustion reaction of maceral chars from the weakly reductive coals is lower than that on the combustion reaction of maceral chars from the reductive coal.

The investigation of U-type nonmechanical recycling valve is carried out on a cold-circulating fluidized bed (CFB) test facility. The size of the cross section of the valve is used to study the influence of the structural characteristics of the cross section on the return characteristics of the U-type valve. The influence of horizontal opening of U-valve on solids circulating rate are also studied. When the fluidizing gas velocity is constant, the solid circulating rate increases linearly first and then reaches constant. At a given loosing gas rate, the maximal circulating rate of system depends mainly on the fluidizing gas velocity. The optimized opening ratio of the horizontal section is about 25% cross section area of the standpipe.

This study proposed to use a jet longitudinal vortex generator (JVG) to enhance heat transfer capability of fluid in the helical channel. Fluid flow characteristics in the helical channel with rectangular cross-section and installed with a JVG were measured by a 3D Laser Doppler Velocimeter (LDV). The curvature of helical channel is δ=0.134. The experimental results were in good agreement with the simulated results. The evolution process of the composite secondary vortices in the helical channel with a JVG and the attenuation process of the jet in the helical channel were obtained. The results show that the impact and entrainment of the jet changes the structure of the common-flow-up (CFU) vortices in the smooth helical channel. And a pair of common-flow-down (CFD) vortices is formed in the initial stage of jet. With the development of the flow in the helical channel, the CFD vortices undergo a process of rapidly producing, slowly decomposing and gradually dissipating. When the speed ratio of the jet stream to the main stream is between 1.48 and 4.02, the effect of jet can reach a distance of 40—74 times d _h along the mainstream direction in the helical channel. Here d _h is the equivalent diameter of helical channel. The effect of JVG improves the synergy between the velocity fields and the temperature fields in the helical channel, thus heat transfer enhancement can be achieved. Within the scope of the study, the average Nusselt number of the heat exchange wall is increased by 28% to 248% relative to the single spiral channel.

Low density polyethylene (LDPE) and paraffin wax (WAX) were used as model compounds for plastics and heavy oils respectively. HZSM-5 was used as the reaction catalyst. The pyrolysis characteristics and kinetic analysis were carried out by thermogravimetric experiments. In product distributions respect, the influence of the co-pyrolysis interaction was discussed by individual pyrolysis of feedstock and co-pyrolysis at different ratios using fixed bed reactor. The results showed that, there was a strong interaction between LDPE and WAX, which accelerated the rate of mass loss and decreased the characteristic degradation temperature and the apparent activation energy. For pyrolysis products, the selectivity of light oil (C_21-) and aromatics were increased, and the selectivity of heavy oil (C₂₁₊) and the yield of solid residues were reduced. Moreover, it was found that the interaction could be enhanced by the increase of WAX content. The results of material balance calculation based on model compounds preliminarily validated that there were practical feasibility and technological advantages to produce high-quality fuel oil by catalytic co-pyrolysis of plastic with its cracking heavy oil.

With the more stringent requirements of atmospheric pollutant emission standards, medium and low temperature catalyst would have larger market and greater challenge. In order to further clarify the application characteristics of the low temperature denitration catalyst, the denitration activity of the industrialized honeycomb catalyst was systematically investigated under different temperatures, flue gas flow rate, catalyst length and water vapor content. The applicable temperature range and kinetic parameters of the catalyst under low temperature window were also determined. These results showed that theoretical denitrification rate of NH₃/NO can be achieved above 160℃ by adjustments of gas velocity and length of honeycomb catalyst. Moreover, it was found that NO conversion gradually decreased with the increase of steam content, and the negative impact become more severely below 180℃ with less than 70% DeNO _x efficiency at 160℃ and 35% steam content in flue gas. According to the relationship between denitrification rate and residence time (at 2－4 m/s gas velocity), the reaction activation energy was calculated to be 22.7 kJ/mol, suggesting that the reaction is limited by the external diffusion. The industrial DeNO _x demonstration of flue gas with 180000 m³/h over this catalyst exhibits more than 90% DeNO _x efficiency at 180℃ and promising industrialization prospect.

The nickel-based magnesium slag catalyst was prepared by excess impregnation method, and the catalytic reforming of pine pyrolysis volatiles was carried out on a small entrained flow gasifier. The effects of calcination/catalytic temperature, Ni content and steam to carbon (S/C) ratio on the catalytic performance were investigated. Moreover, the tar creaking capability of Ni/MS catalyst and Ni/γ-Al₂O₃ catalyst were explored under different calcination/catalytic temperatures. The catalysts were characterized by BET, XRD, SEM and TEM. The results indicated that the best tar conversion (95.69%) and the significant reduction in the relative content of heavy PAHs as well as the tar dew point of 40.2℃ were obtained over Ni/MS catalyst under the conditions of Ni content 3%, calcination/catalytic temperature 800℃, S/C = 0.5. Results from XRD showed that the interactions of Ni, Fe, Ca, and Mg formed multiple active centers to display synergistic catalytic effects, thereby jointly promoting catalyst activity.

A series of Fe _x MnCe₁-AC catalysts were prepared by ultrasonic-assisted impregnation method with activated carbon as carrier. The low-temperature NH₃-SCR denitrification activity of the catalysts was investigated, and the best activity catalyst was established. The effect of SO₂ on its denitration performance was also explored. The results showed that Fe_0.1MnCe₁-AC catalyst exhibited best denitration efficiency at low-temperature among prepared catalysts, the conversion rate of NO exceeded 90% with the temperature range from 120℃ to 220℃ (no SO₂). In addition, the catalyst could maintain NO conversion rate of approximately 77% under the atmosphere of 180℃ and SO₂ concentration of 429 mg/m³. The mechanism of SO₂ poisoning on the catalyst was characterized with BET, XRD, XPS, H₂-TPR NH₃-TPD, FT-IR and TGA. It was observed that SO₂ could form ammonium sulfate ( (NH₄)₂SO₄, (NH₄)₂SO₃ ), and MnSO₄ with NH₃ and the metal components in the catalyst, which changed the pore structure of the fresh catalyst and reduced the Br?nsted acid sites and Lewis acid sites on the catalyst surface. These variation made the inhibitory effect on the catalytic adsorption capacity of NH₃. Moreover, SO₂ also promoted a decrease in the number of Mn⁴⁺, Ce³⁺, Fe³⁺ and Fe³⁺—OH^- groups in the catalyst, and lessened the surface reducible species, thereby reducing the activity of the catalyst denitration.

The experimental data of the existing laminar flame velocity of methanol were collected and analyzed. The three typical chemical reaction mechanisms describing the oxidation of methanol (Li mechanism, USC Mech-Ⅱ and Burke mechanism) were compared to predict the propagation velocity of laminar flame. Laminar flame speed is an intrinsic property of a combustible mixture. In the present study, the validities and accuracies of three different chemical kinetic models (including Li scheme, USC Mech Ⅱ scheme and Burke scheme) on their predictions of laminar methanol-air flame speed were verified using newly-reported experimental data in the literature. The results show that the tested three kinetic schemes were able to qualitatively characterize the variation of the laminar flame speed of methanol-air mixtures. However, quantitatively, remarkable over-predictions were found between the computed laminar flame speed and experimental ones of fuel-rich mixtures. Consequently, reaction sensitivity analysis and reaction rate analysis were conducted in order to figure out the reason for the discrepancy. As per the kinetic analysis,the H-abstraction of methanol was found to be of great importance to the laminar flame speed. Consequently, the H-abstraction in Li scheme was updated using the newly-reported data, and the predictions of laminar flame speed using the modified Li scheme were greatly improved, especially on the fuel-rich side. In the engineering calculation, a quick estimation of the laminar flame speed with an acceptable accuracy is desired. Motivated by this demand, two empirical prediction correlations for methanol-air laminar flame speed were proposed. The predictions using the two correlations were in good agreement with the reported experimental data at different initial mixture temperatures and pressures. The calculation of the laminar flame speed of methanol-air mixtures using the proposed correlations is much faster than detailed modeling using full kinetic model so that it will save a large amount of computation resources in the engineering calculation.

Liquid-solid separation is a common operation unit in coal chemical wastewater treatment. The material to be treated is tangentially inserted into the separation device against the inner wall surface of the cylinder to form a three-dimensional concave wall tangential jet. In order to compare the influence of the jet inlet structures on discrete particles, the liquid-solid separation experiment and discrete phase model are used to calculate the trajectory and Reynolds number of the particles. The continuous phase turbulence characteristics are investigated under the influence of the particles, and the distribution of wall shear stress was analyzed. The results show that the fit length between inlet and wall are shortened for semi-circular, square and circular. The radial distribution range of particles is sequentially widened, and the distance of flow direction is sequentially shortened. The particle residence time is shortened in the order of circle, semi-circular, and square inlets. The reason is that the maximum tangential velocity of the semi-circular inlet is 16.0% higher than that of the square, and the circular shape is reduced by 15.3%. The average value of the centrifugal force of the semi-circular inlet is increased by 59.9% and the circle is reduced by 43.5% than the square in the near wall. 97% of the particles Reynolds number is in the range of 40—400, and the number of particles with Re = 80 is the highest for three inlets. The particles are affected by the concave-wall jet, the impact and rolling is formed between the discrete particles and the wall. The first impact is in the range of 10°—35° in the inlet circumferential direction, the maximum wall shear stress appears to be flat. The wall shear stress gradually approaches zero after the particles roll along the wall surface and the circumferential direction exceeds 90°. After calculations, the turbulence intensity increased 27.1%, 8.8%, and 62.7%, and the wall shear stress increased 23.7%, 13.5%, and 15.2% for square, semi-circular and circular inlet, respectively.

Combustion kinetics is the basis for studying the combustion characteristics of oil shale semi-coke particles. Thermal gravimetric analyzer (TGA) was used to conduct isothermal combustion experiments of oil shale semi-coke. Effects of combustion temperature and oxygen concentration on kinetics of oil shale semi-coke combustion were analyzed. Higher combustion temperature and oxygen concentration would lead to faster combustion rate. A kinetic model considering oxygen concentration effects was developed. It was found that the combustion rate of oil shale semi-coke is proportional to oxygen concentration to the 0.97 power. The kinetic model yielded good agreements with the experiments results, and could provide a base for further investigation on the combustion of large oil shale semi-coke particles.

Catalytic steam gasification of coal was carried out in a pyrolysis, reforming and combustion separated decoupled triple bed gasification system. The olivine was used as the in-situ tar cracking catalytic bed material, and the coal catalytic gasification experiment was carried out. The effects of coal types, coal feeding rate, reformer temperature and steam to carbon mass ratio (S/C) on gasification performance were investigated. The results showed that the gas yield, carbon conversion, cold gas efficiency and H₂ content in the gas increased with the increasing volatile content of coal. The carbon conversion and cold gas efficiency is relatively low due to the char is not involved in gasification reaction. The gas yield and gas composition influenced by coal to catalyst ratio. The gas yield increased from 0.28 m³/kg to 0.46 m³/kg and the H₂ content increased from 28.4% to 50.5% with increasing coal feeding rate from 0.12 kg/h to 0.30 kg/h. Increasing reforming temperature and S/C were beneficial to promote the tar cracking and conversion, and thus increased the gas yield. A gas yield of 0.6 m³/kg tar content as low as 2.11 g/m³ has been achieved at the reformer temperature was 850℃ and S/C of 1.0. The addition of steam enhanced the steam reforming reaction of tar, and increased the gas yield. However the excessive steamcause shorter residence time of tar in reformer that results reduction degree of tar steam reforming reaction.

The self-sustained combustion of toluene on the Cu-Ce-Zr based catalysts with different activity has been carried out in a micro-tube with inner diameter of 4 mm. It was shown that the lean-combustion limits over CuCe_0.75Zr_0.25O_x-BC catalyst with the higher activity were less than that on CuCe_0.75Zr_0.25/TiO₂ catalyst at the same flow rate, and the minimum of equivalence ratio (?) was 0.024 under the flow rate of 200 ml/min. The residence time of the mixed gas on the catalyst surface declined with the increasing of flow rate, making the highest surface wall-temperature range shift to the back of catalyst bed. Toluene could maintain self-sustained combustion even when the heat loss was as high as 91.9%. Combined with the theoretical model, the heat transport of toluene self-sustained combustion in micro-tube was calculated. The self-sustained combustion in a fixed-bed reactor was realized with reducing the upper limit of temperature runaway s impacts for the reactor and catalysts.

The supercritical carbon dioxide (SCO₂) Brayton cycle system is a promising power generation energy conversion system in the future. The CO₂ physical property characterization model has a significant impact on the prediction accuracy of the power equipment shaft seal and bearing performance in the Brayton cycle system. On the basis of summarizing the experimental data of CO₂ physical properties under different temperatures and pressures in authoritative literature, the prediction accuracy of CO₂ density, viscosity and thermal conductivity prediction model in the classical physical property query software REFPROP software is compared and analyzed, and the physical prediction model with the highest prediction accuracy is obtained. The artificial neural network algorithm is used to obtain the prediction model of CO₂ physical property with higher precision in near critical region. The results show that the FEK model, VS1 model and TC1 model in REFPROP software have the highest prediction accuracy for CO₂ density, viscosity and thermal conductivity, respectively, but the maximum and average error predictions in the near critical region are still more than 40% and 8%, the CO₂ physical property prediction model obtained by the neural network algorithm can reduce the maximum and average error prediction of the near critical point area to 30% and 4%, respectively.

Three sets of industrial-scale dense phase CO₂ pipelines (length 258 m, inner diameter 233 mm) leaking experiments with different pore sizes (50, 100 and 233 mm) were carried out, and the time-history curves of CO₂ pressure and temperature at different positions in the tube were recorded. The change of CO₂ density, enthalpy value and Prandtl number (Pr) was obtained by using REFPROP software. The variation of thermodynamic characteristics of dense CO₂ pipeline leakage and pressure loss process was studied. The results show that after the pipeline leaks, the dense phase CO₂ is rapidly converted into gas-liquid two-phase. The gas-liquid two-phase is converted into the gas phase with the experiment, and the solid phase dry ice is formed. The phase change causes the median enthalpy value in the pipeline to increase, the density of the medium to drop sharply, and the smaller the diameter, the more obvious the parameter change. Since the medium in the pipeline forms a multi-phase flow fluid flow, the temperature change is closer to the top of the leak port, and the convective heat transfer intensity is greater. As the leakage diameter increases, the CO₂ phase changes significantly, Pr increases, and the heat transfer in the pipeline moves from the bottom of the pipeline to the top of the pipeline. The heat transfer effect inside the pipeline is the best at the critical point of the CO₂ phase transition.

The MnO_x modified activated carbon (MnO_x/AC) was prepared by impregnation method to simulate the removal of elemental mercury in coal combustion flue gas. The effects of Mn loading on sorbent, sorption temperature and flue gas composition on removal performance of elemental mercury in simulated flue gas were investigated. Mechanism of SO₂ inhibition on mercury removal was revealed. The average Hg⁰ removal efficiency on MnO_x/AC is 97.0% at 150℃ in 3 hours when Mn loading is 14% (mass) with 5% (vol) O₂ in simulated flue gas. A small amount of O₂ and trace amounts of HCl and NO promoted the removal of mercury in gas phase, while trace amount of SO₂ inhibited it. TG/DTG, XPS and Hg-TPD analyses of spent MnO_x modified activated carbon indicated that the inhibition of SO₂ on Hg⁰ removal of modified activated carbon is due to the consumption of lattice oxygen in MnO_x by formation of sulfate that occupies active sites on the surface of 14Mn/AC. This inhibition of SO₂ on removal of elemental mercury could be effectively reduced by adding trace amount of NO.

Attrition characteristics of limestone has a significant effect on material balance and SO₂ capture efficiency in circulating fluidized beds. A bubbling reactor system, equipped with a particle separation apparatus and mass spectrum analyzer, was used to investigate the mutual influence between the calcination and sulfation reactions and the limestone attrition under different conditions. The results showed that sulfation reaction would be significantly reduced the attrition rate, delaying the time for reaching to the stable attrition rate. As the sulfation reaction progressed, the outer surface layer of a CaO particle was gradually covered by CaSO₄. After the initial fast reaction finished, the attrition rates of limestone tended to be stable. Attrition would remove the impervious sulfate layers and enhance the sulfation conversion. Besides, the attrition rate decreased with the increasing sulfation conversion at the same reaction condition. Finally, using the existing literature data to analyze and verify the limestone attrition model, it can better reflect the difference in attrition rate of limestone with different particle sizes.

The structural characteristics of high iron coal ash melt and the variation of structure with temperature were studied by thermodynamic calculation and molecular dynamics simulation. The contents of Fe³⁺ and Fe²⁺ at different temperatures were calculated, and the radial distribution function, coordination number, bond angle, coordination state of oxygen and Q ⁿ structural units were analyzed. The results of thermodynamic calculations show that the increase of temperature is beneficial to the conversion of Fe³⁺ to Fe²⁺, and the change of Fe³⁺/Fe²⁺ with temperature is obtained. Based on the BMH potential function, molecular dynamics simulations show that the melt has short-range order and long-range disordered structural features. As the temperature increases, the height and sharpness of the radial distribution function curve of each ion pair decrease, the higher coordination state of each ion decreases and the lower coordination state increases, the height and sharpness of the bond angle curve decrease and the first peak moves in a smaller direction. These phenomena all indicate that the degree of aggregation of ions is weakened, and the degree of disorder inside the melt is enhanced. The coordination state of oxygen and the change of Q ⁿ are a direct reflection of the change of melt polymerization degree. The increase of temperature leads to the decrease of tri-coordinate oxygen and bridge oxygen, and the increase of non-bridge oxygen and free oxygen. Q⁴ structural unit disintegrated to generate Q³, Q², Q¹ and Q⁰ structural units with lower degree of polymerization.

To further improve the quality of the waste pyrolysis products and increase the yield of the target product, a reactor from the source semi-coke reforming volatiles is disposed downstream of the waste pyrolysis reactor, and dolomite (D) and activity are mixed in the self-source semi-coke. Dolomite (D) and activated sewage sludge char (ASSC) were added into the char to improve the catalytic effect and to obtain higher gas yield and oil of better quality. The research results showed that, when the volatiles generated from MSW pyrolysis (550℃) were isothermally reformed by the MSW char from the same pyrolysis process the gas yield increased by 44.29% and the pyrolytic liquid yield decreased by 41.33%. In this process the aliphatics in pyrolytic liquid decreased, while monoaromatics increased. As dolomite was added as a catalyst modifier, the pyrolytic oil and its oxygenates content were further reduced. When ASSC was used as catalyst modifier, it enhanced the conversion of the pyrolytic liquid into gas. Especially for the scenario of Char∶ASSC=1∶1 by mass ratio, the pyrolytic liquid yield decreased from 30.44% to 11.25%, and its moisture content was reduced to 35.64% from 57.23%. In general, the char from MSW pyrolysis had the effect of promoting the formation of monoaromatics and decomposition of aliphatics in liquid products, while both dolomites and ASSC, especially the later, increased the aliphatics concentration in the pyrolytic liquid. The addition of dolomite promoted the yields of CH₄, H₂ and CO in the gas product, while the addition of ASSC greatly facilitated the production of H₂ and CO based on the higher level consumption of H₂O vapor in the volatiles, but inhibited the production of CH₄. When syngas is the target product, char and ASSC mixture can be recommended with the blending ratio of char∶ASSC=1∶1, for which the gas yield reaches 45.5% or 0.50 m³/(kg MSW), and the volume percentage of the syngas (H₂+CO) achieves 53.87%.

High alkali coal generally has a high alkali metal content, which is the main precursor for the formation of submicron particulate matter PM₁ during coal combustion. However, the alkali and alkaline earth metals (AAEMs), especially Na, result in a large amount of fine particulate matter (PM₁) formation during coal combustion. In this work, two kinds of typical Zhundong coal are selected, namely, ZD-1 and ZD-2. The pulverized coal is burned in an electrical heated drop-tube furnace with different temperature (1273 K, 1373 K, and 1473 K). The mass size distribution and concentration of the particulates are analyzed by low pressure impactor (LPI), and compositions are determined by energy dispersive spectrometry (EDS). The results indicate that the amounts of PM₁ produced by the submicron particles gradually decreases with increasing the reaction temperature. The size of PM₁ shifts to a smaller size. The formation of PM₁ is mainly affected by mineral elements such as Na and S. As the temperature increased, the relative contents of Na and S decreases in PM₁, and the relative contents of Ca, Fe and Si increase. The mass concentrations of Na and S in the collected particles depend upon the particle size, which are proportional to \mathrm{1} / D_{\mathrm{p}}^{\mathrm{0}} for the particle sizes less than 0.4 μm. The PM₁ formation characteristics are mainly affected by the homogeneous nucleation and heterogeneous condensation of high concentrations of mineral elements, and the interaction between mineral elements with intermediate products during combustion. Active sites of oxygen formed by silicon-aluminum oxides at high temperature can efficiently capture Na vapor, thereby inhibiting PM₁ formation. This is one of the main reasons for the reduction of PM₁ at higher temperature.

The main pollutants of natural gas-fired boilers are NO and NO₂. The emission data of two natural gas-fired boilers were reported in the present paper and NO₂ emission was found to be high. To understand the high NO₂ emission in these natural gas-fired boilers, pilot-scale experiments were conducted and detailed chemical kinetic studies were carried out numerically using Chemkin-Pro software. The results showed that the NO₂ emission would be high if the low NO _x strategy “burner staged-combustion + flue gas recirculation” was applied and the mixing of the co-flow air with the staged fuel was delayed. In this situation, the amount of NO₂ emission even exceeded 50% of the amount of the total NO _x emission. When the air and fuel were well mixed, NO₂ emission was suppressed. NO₂ mainly formed near the contact surface of the hot burned product flow and cold air flow. A narrow temperature window, 800—900 K, was found for NO₂ formation. The dominating pathway for NO₂ formation was the reaction between NO and HO₂. When NO₂ decomposed, NO formed. Therefore, the formation of NO₂ would not significantly affect the total NO _x emission of the natural gas-fired boiler.

The resource utilization of sludge has always been the focus of research by scholars. And their conversion into high quality solid fuels (hydrochars) via hydrothermal carbonization (HTC) is proved to be a promising potential technology. In this work, Co-HTC of sludge (sewage sludge, SS; deinking sludge, DS) and lignite (LC) was investigated to obtain a better preparation technology of sludge-derived hydrochars. The synergetic effect of mixing ratio (3∶7, 5∶5, 7∶3) on the HTC upgrading of sludge/LC mixtures was explored. And the combustion performance of hydrochars was also analyzed. The results have demonstrated that sludge/LC mixtures at a mixing ratio of 5∶5 have exhibited an optimal performance of hydrochar products. Specifically, the hydrochar yields can reach up to 81.08% and 86.00% for LC/SS and LC/DS, respectively. And high synergistic coefficients are observed in hydrochar yield (LC/SS-1.69%, LC/DS-0.18%), organics retention (LC/SS-11.90%, LC/DS-2.64%) and carbon retention (LC/SS-4.08%, LC/DS-0.77%), indicating a more remarkable synergetic effect of LC/SS than LC/DS. Besides, the higher heating value (HHV) and coalification degree of hydrochars can be enhanced by the increasing proportion of LC, which not only improves the fuel characteristics of hydrochars, but also makes it more stable and sufficient in the combustion process. These findings indicate that higher quality fuels can be obtained by Co-HTC pretreatment, thereby realizing the effective utilization of sludge/lignite.

After the torrefied traditional Chinese medicine waste (TCMW) is baked, it is a solid fuel with potential application. However, little is known about the thermal decomposition of torrefied TCMW. In this study, the effects of torrefaction on the pyrolysis and combustion characteristics of torrefied TCMW were investigated and the kinetic parameters were evaluated. The indexes of combustible, burnout characteristic and integrated combustion performance were also evaluated. It was found that the pyrolysis of torrefied TCMW can be divided into two distinct stages, which is governed by two different reaction mechanisms. The pyrolysis of torrefied TCMW was mainly concentrated between 250—500℃ with mass loss of 57%—65%. The two DTG peaks of the torrefied TCMW are superimposed by four peaks: 265.8℃, 318℃, 364.2℃ and 412.3℃. The first three peaks were due to the thermal decomposition of hemicellulose, cellulose and lignin, respectively. The decomposition of lignin and the carbonization of solid residues gave rise to the peak at 412.3℃. The apparent activation energy of the first stage is 76.1—94.0 kJ/mol, while that is 26.8—38.8 kJ/mol for the second stage. The torrefied TCMW was easy to ignite and burnout. The ignition temperature of torrefied TCMW is in the range of 280.3—294.8℃. In general, the torrefied TCMW in 10% O₂ shows the best combustion performance. The combustion of torrefied TCMW can be divided into three stages. The first stage is mainly due to the release and combust of volatiles with the activation energy of 80.5—97.3 kJ/mol. However, the TCMW under CO₂ and 10% O₂ torrefaction has higher activation energy (99—97 kJ/mol). The second stage is attributed to the combustion of volatiles and residue char with the activation energy of 18.3—28.5 kJ/mol. The main reaction of the third stage reaction is the combustion of the char, and the activation energy is 41.8—50.6 kJ/mol. The results of this paper are helpful to understand the pyrolysis and combustion of torrefied TCMW under different conditions and develop an effective utilization process.

Tibet Autonomous Region has special geographical conditions and a fragile ecological environment. The yield of Tibetan municipal solid waste (MSW) and sewage sludge (SS) has been increasing rapidly due to the development of urbanization and tourism. At present, the main treatment method of MSW/SS is landfill, while incineration is still at trial operation stage, and generally lack of advanced disposal technology. In this study, the characteristics of MSW and SS in the Tibet were investigated. The differences during the incineration process between wastes from Tibet and Tianjin were analyzed in a grate furnace. Also, the incineration characteristics of Tibetan MSW and SS under different mixing ratios was studied. The optimum blending ratio was preliminarily determined to be 4∶1 which reduced the emissions of CO by 23.06%, HCl by 45.51%, and PM by 30.73%. Considering the irreversibility of the ecological environment in Tibet and its strategic role as a national ecological safety barrier, this study provides guidance for pollutant control in the waste incineration process and reference for the engineering application of MSW and SS co-incineration in Tibet.

The Mo/ZSM-5 catalyst was prepared by an equal volume impregnation method and applied to the rapid pyrolysis of biomass to prepare bio-oil. The effects of Mo loadings, reaction temperature, reaction time and catalyst/biomass mass ratio on the yields and composition of bio-oils were researched. Compared to the pyrolysis of sawdust, the yields of bio-oils were greatly increased by ZSM-5 and Mo/ZSM-5 catalysts. Under the reaction condition of T=600℃, t=25 s, catalyst/biomass mass ratio=10/1, the yields and amounts of aromatic hydrocarbons in bio-oil reached the maximum by 10Mo/ZSM-5 catalysts. According to the variations of products in bio-oils, Mo/ZSM-5 catalysts promoted the conversion of oxygenated compounds, such as acids, aldehydes and ketones, into aromatic hydrocarbons, which could effectively upgrade the bio-oils.

A three-dimensional full-loop simulation of biomass gasification in an industry-scale dual fluidized bed is conducted based on the MP-PIC (multi-phase particle-in-cell) method. In this method, the parcel motion is descript under Lagrangian framework while the gas turbulence is solved by large-eddy simulation (LES), meanwhile, the complex gas-solid interaction, pyrolysis, gasification and homogeneous/heterogeneous reactions are considered simultaneously. Firstly, the independence of grids and particles per parcel (PPP) is conducted, and the numerical results agree well with the experimental data. Secondly, the gas-solid flow characteristics and syngas distributions in dual fluidized bed are revealed and the effects of bed temperature, biomass particle number and drag force correlation on syngas production are analyzed. The results show that the temperature increases, the CO mole fraction at the outlet increases, and the remaining components decrease; the gasification effect of the smaller biomass particle size is better than the larger biomass particle size. The drag model has a negligible effect on the syngas production.

In this paper, the pilot-scale sintering cup test and the comprehensive sintering model were combined to analyze the effects of mixture characteristics (sintering alkalinity, coke and moisture addition) on flame kneading properties and sintering properties. Previously developed and validated sintering sub-models have been integrated in this work. Simulations were carried out based on 125 cases simulating a wide range of sintering conditions. Thermochemical modelling using FactSage provided useful information to improve the melting and solidification sub-model and provide greater insights into the state of the material in the flame front. Modelling studies showed that the maximum or minimum values of flame front speed, yield, coke rate and productivity appear when the basicity and coke addition change continuously. Under the sintering conditions of present work, the condition for maximum productivity is basicity 2.0, moisture level 7.7%, coke level 6.4%. The condition for minimum coke rate is basicity 2.0, moisture level 6.5%, coke level 6.4%. Obviously, the optimum productivity and coke rate conditions are different. The actual operating conditions will depend on the objective of a sinter plant.

To understand the limestone desulfuration process in the water-coal-slurry fired circulating fluidized bed (CFB) boiler, in which the steam concentration in the furnace is much higher than the conventional CFB boiler, calcination and sulfuration processes of the limestone desulfuration were respectively studied at a rather wide range of steam concentration using a fixed-bed reactor. The pore structure and apparent morphology of the calcined product and the sulfurized product were analyzed by a true densitometer and a scanning electron microscope. The results show that the presence of water vapor (H₂O(g) ) promotes the sintering of calcination product. The porosity and specific surface area of calcination product are lower than those of the calcination product at H₂O(g) free condition. With the presence of H₂O(g), the macropore portion of calcination product increases, reducing the reactivity of the calcium oxide (CaO) and thereby retards sulfation reaction. With the increase of the H₂O(g) concentration, the presence of H₂O(g) promotes first and then inhibites sulfuration reaction. At an optimal H₂O(g) concentration around 10%, the conversion of calcium is the highest. The reason for the non-monotonic variation is due to that on the one hand, H₂O(g) promotes the solid-state diffusion of sulfuration product, and on the other hand, H₂O(g) promotes the sintering of unreacted CaO.

The physicochemical properties of heavy bio-oil were characterized by NMR and GC/MS, and thermogravimetric analyzer (TG-DTG) and pyrolysis instrument-gas chromatography/mass spectrometry (Py-GC/MS) was used to study the pyrolysis characteristics of heavy bio-oil. The results indicate that the heavy bio-oil consists of aromatic compounds and saccharides. The first stage is the volatilization of light compounds from ambient temperature to 300℃. The second stage is the pyrolysis, oxidation and polymerization of the heavy compounds at higher temperature (300—520℃). The last stage is the formation of coke (520—800℃). When the pyrolysis temperature is lower than 500℃, the species of products gradually increases with increasing temperature. When the temperature is higher than 500℃, the species of products tends to be stable with increasing temperature.

Photocatalysis, asymmetric synthesis and molecular oxygen oxidation are combined with continuous reaction. Using a glass microreactor, a continuous reaction for asymmetric α-hydroxylation of β-keto ester compound is oxidized by ¹O₂ under visible light. The reaction is catalyzed by cinchona alkaloid phase transfer catalyst in gas-liquid-liquid heterogeneous system. The desired product is obtained in high yield (95%) and good enantio selectivity (87.0%) in microreactor. Compared with the batch reaction, continuous reaction greatly reduces reaction residence time from 30 min to 1.08 min and maintains high stereo selectivity. The method has the advantages of fast, low energy consumption, continuous and high efficiency, and has good industrialization prospects.