微通道内乙醇胺吸收CO2的过程特征（英文）

Process characteristics of CO2 absorption using aqueous monoethanolamine(MEA) in a microchannel reactor were investigated experimentally in this work.A T-type rectangular microchannel with a hydraulic diameter of 408 μm was used.Operating parameters,i.e.temperature,pressure and molar ratio of MEA to CO2 were studied.Under 3 MPa pressure,the mole fraction of CO2 in gas phase could decrease from 32.3% to 300×10?6 at least when gas hourly space velocity ranged from 14400 to 68600 h?1 and molar ratio of MEA to CO2 was kept at 2.2.In particular,the effects of temperature on CO2 absorption flux,mass transfer driving force,gas-liquid contact time and en-hancement factor were analyzed in detail and found that mass transfer enhancement by chemical reaction was a crucial factor for the process of CO2 absorption.     

Kinetic effects of nanosecond discharge on ignition delay time☆

The effects of nanosecond discharge on ignition characteristics of a stoichiometric methane–air mixture without inert diluent gas were studied by numerical simulation at 0.1 MPa and an initial temperature of 1300 K. A modified non-equilibrium plasma kinetic model was developed to simulate the temporal evolution of particles produced during nanosecond discharge and its afterglow. As important roles in ignition, path fluxes of O and H radicals were analyzed in detail. Different strength of E/N and different discharge duration were applied to the discharge process in this study. And the results presented that a deposited energy of 1–30 m J·cm~(-3) could dramatically reduce the ignition delay time. Furthermore, temperature and radicals analysis was conducted to investigate the effect of non-equilibrium plasma on production of intermediate radicals. Finally, sensitivity analysis was employed to have further understanding on ignition chemistries of the mixture under nanosecond discharge.     

甲烷部分氧化制乙炔过程研究

The partial oxidation of hydrocarbons is an important technical route to produce acetylene for chemical industry.The partial oxidation reactor is the key to high acetylene yields.This work is an experimental and numerical study on the use of a methane flame to produce acetylene.A lab scale partial oxidation reactor was used to produce ultra fuel-rich premixed jet flames.The axial temperature and species concentration profiles were measured for different equivalence ratios and preheating temperatures,and these were compared to numerical results from Computational Fluid Dynamics(CFD)simulations that used the Reynolds Averaged Navier-Stokes Probability Density Function(RANS-PDF)approach coupled with detailed chemical mechanisms.The Leeds 1.5,GRI 3.0 and San Diego mechanisms were used to investigate the effect of the detailed chemical mechanisms.The effects of equivalence ratio and preheating temperature on acetylene production were experimentally and numerically studied.The experimental validations indicated that the present numerical simulation provided reliable prediction on the partial oxidation of methane.Using this simulation method the optimal equivalence ratio for acetylene production was determined to be 3.6.Increasing preheating temperature improved acetylene production and shortened greatly the ignition delay time.So the increase of preheating temperature had to be limited to avoid uncontrolled ignition in the mixing chamber and the pyrolysis of methane in the preheater.     

介观尺度多孔介质燃烧室内火焰分布的电容层析成像(英文)

This study was conducted to investigate the characteristics of meso-scale combustion.The technique of electrical capacitance tomography(ECT) was used to locate flame position and monitor the effect corresponding to varied air/fuel ratio in a meso-scale combustor.Combustion phenomena including igniting,quenching and unsteady combustion have been visualized using ECT.The method of metallization protecting ECT sensor from high temperature damage and the novel calibration method adapted to ECT monitoring of unknown permittivity flame have been shown to be successful.At the same time,electrical nature of combustion and dielectric characteristics of hy-drocarbon flame were studied.The relationship between flame permittivity and state parameters of combustion gas was demonstrated preliminarily.     

秸秆固化成型燃料引火助燃剂的点火和烟气排放特性(英文)

Ignition-assisting agents for densified corn stover briquette fuel(DCBF) were developed,and their ignition and emission characteristics were investigated using type LLA-6 household cooking stove.Three waste liquid fuels,waste engine oil(E) ,diesel oil(D) ,and industrial alcohol(A) ,were used as raw materials to make 25 ignitionassisting agents by mixing at different ratios.Their ignition performance was evaluated in terms of ignition time and cost.It was found that ignition-assisting agents ED15(a mix of E and D at volume ratio of 1︰5) and DA51(a mix of D and A at volume ratio of 5︰1) presented better ignition results with shorter ignition time(40-53 s) and lower cost(6.1 and 5.3 cents) at the dosages of 9 ml and 8 ml,respectively.The emission of O2,CO,CO2,NOx,and SO2,the temperature in fume gas,and combustion efficiency were investigated for ED15 and DA51.The results show that the emission of ED15 with the dosage of 9 ml is lower than that of DA51 with the dosage of 8 ml in the ignition process.ED15 at the dosage of 9 ml achieves satisfactory combustion efficiency and emits less pollutant,so it is recommended for practical application.The study will provide a cost-effective and environmentally friendly approach to fast ignite DCBF and break the barrier to the practical application of DCBF.     

Two-dimensional Simulation for Hydrogen/Air Combustion in a Monolith Reactor

Recent studies on hydrogen combustion were reviewed briefly. The laminar flow and combustion of premixed hydrogen/air mixture in a cylindrical channel of a monolith reactor with and without catalytic wall was numerically modeled by solving two-dimensional (2-D) Navier Stokes (N S) equations, energy equation, and species equations. Eight gas species and twenty reversible gas reactions were considered. The control volume technique and the SIMPLE algorithm were used to solve the partial differential equations. The streamlines of the flow field, temperature contours, the entrance length, and the concentration fields were computed. It is found that the entrance zone plays an important role on flow and temperature as well as species distribution. Therefore, the flow cannot be assumed either as fully developed or as plug flow. There is a small but strong thermal expansion zone between the wall and the entrance. Both diffusion and convection affect the heat and mass transfer processes in the expansion zone. Thus the equations of momentum, energy and species conservations should be used to describe hydrogen/air combustion in the monolith reactor. The hot-spot location and concentration field of the homogeneous combustion is strongly influenced by the inlet velocity and temperature, and the equivalence ratio. The catalytic combustion of premixed hydrogen/air mixture over platinum catalyst-coated wall in a cylindrical channel was also simulated.     

Chemical Effects of CO2 Concentration on Soot Formation in Jet-stirred/Plug-flow Reactor

Soot formation was investigated numerically with CO2 addition in a jet-stirred/plug-flow reactor （JSR/PFR） C2H4/OJN2 reactor （C/O ratio of 2.2） at atmospheric pressure. An updated Kazakov mechanism empha- sizes the effect of the O2/CO2 atmosphere instead of an O2/N2 one in the premixed flame. The soot formation was taken into account in the JSR/PFR for C2H4/O2/N2. The effects of CO2 addition on soot formation in different C2H4/O2/CO2/N2 atmospheres were studied, with special emphasis on the chemical effect. The simulation shows that the endothermic reaction CO2 ＋ H - CO ＋ OH is responsible of the reduction of hydrocarbon intermediates in the CO2 added combustion through the supplementary formation of hydroxyl radicals. The competition of CO2 for H radical through the above forward reaction with the single most important chain branching reaction H ＋ O2, ＇ O ＋ OH reduces significantly the fuel burning rate. The chemical effects of CO2 cause a significant increase in residence time and mole fractions of CO and OH, significant decreases in some intermediates （H, C2H2）, polycyclic aromatic hydrocarbons （PAHs, C6H6 and CI6H10, etc.） and soot volume fraction. The CO2 addition will leads to a decrease by only about 5% to 20% of the maximum mole fractions of some C3 to Clo hydrocarbon intermediates. The sensitivity analysis and reaction-path analysis results show that C2H4 reaction path and products are altered due to the CO2 addition.     

An Experimental Investigation of Hydrogen Production from Biomass

In gaseous products of biomass steam gasification, there exist a lot of CO, CH4 and other hydrocarbons that can be converted to hydrogen through steam reforming reactions. There exists potential hydrogen production from the raw gas of biomass steam gasification. In the present work, the characteristics of hydrogen production from biomass steam gasification were investigated in a small-scale fluidized bed. In these experiments, the gasifying agent (air) was supplied into the reactor from the bottom of the reactor and the steam was added into the reactor above biomass feeding location. The effects of reaction temperature, steam to biomass ratio, equivalence ratio (ER) and biomass particle size on hydrogen yield and hydrogen yield potential were investigated. The experimental results showed that higher reactor temperature, proper ER, proper steam to biomass ratio and smaller biomass particle size will contribute to more hydrogen and potential hydrogen yield.     

An Experimental Study on Thermal Characteristics of Laurie Acid as a Latent Heat Storage Material during Melting Process

The objective of this study was to establish the thermal characteristics of the lauric acid (95% purity) as a latent heat storage material filled in the annulus of vertical concentric double pipe during its melting process. The temperature data were used to determine the thermal characteristics, including the temporal temperature variations and the effects of the mass flow rate and the inlet temperature of the heat transfer fluid on the heat transfer coefficient and the heat charging fraction during the melting process. The results indicated that the time to reach to heat charging fraction of 1.0 could be altered by changing the mass flow rate and the inlet temperature of the heat transfer fluid.     

基于详细反应机理的富燃多孔燃烧制氢的计算流体力学模拟

Computational fluid dynamics （CFD） combined with detailed chemical kinetics was employed to model the filtration combustion of a mixture of methane/air in a packed bed of uniform 3 mm diameter alumina spherical particles. The standard k-ε turbulence model and a methane oxidation mechanism with 23 species and 39 elemental reactions were used. Various equivalence ratios （1.47, 1.88, 2.12 and 2.35） were studied. The numerical results showed good agreement with the experimental data. For ultra-rich mixtures, the combustion temperature exceeds the adiabatic value by hundreds of centigrade degrees. Syngas （hydrogen and carbon monoxide） can be obtained up to a mole fraction of 23%. The numerical results also showed that the combination of CFD with detailed chemical kinetics gives good performance for modeling the pseudo-homogeneous flames of methane in porous media.     

催化部分氧化甲烷制合成气的平衡热力学研究

The catalytic partial oxidation of methane to syngas (CO H2) has been simulated thermodynamically with the advanced process simulator PRO/Ⅱ. The influences of temperature,pressure,CH4/O2 ratio and steam addition in feed gas on the conversion of CH4 selectively to syngas and heat duty required were investigated, and their effects on carbon formation were also discussed. The simulation results were in good agreement with the literature data taken from a spouted bed reactor.     

融化过程中作为潜能储存材料的月桂酸的热特性的实验研究

The objective of this study was to establish the thermal characteristics of the lauric acid (95% purity) as a latent heat storage material filled in the annulus of vertical concentric double pipe during its melting process,The temperature data were used to determine the thermal characteristics,including the temporal temperature variations and the effects of the mass flow rate and the inlet temperature of the heat transfer fluid on the heat transfer coefficient and the heat charging fraction during the melting process,The results indicated that the time to reach to heat charging fraction of 1.0 could be altered by changing the mass flow rate and the inlet temperature of the heat transfer fluid.     

使用加热空气的预混天然气催化燃烧的实验研究

In this paper the premixed catalytic combustion emissions such as CO, unburned hydrocarbon （UHC）, NOx and the temperature distribution in the catalytic monolith with ultra low concentration of Pd were studied. Three types of monoliths were used for experiments and the temperature of preheated air was respectively 50℃, 100℃ and 200℃. The results showed that preheated air made radial temperature in the catalytic monolith uniform which helped to avoid local hot spots so as to decrease NOx emission. The experiment also proved that the shorter monolith showed much better catalytic combustion performance than longer one and the temperature at the exit of the shorter monolith was relatively lower. On the contrary, the temperature was higher in the longer monolith and the lethal NOx emission was slightly increased.     

Effect of CO Combustion Promoters on Combustion Air Partition in FCC under Nearly Complete Combustion

With CO combustion promoters, the role of combustion air flow rate for concerns of economics and control is important. The combustion air is conceptually divided to three parts：the air consumed by coke burning, the air consumed by CO combustion and the air unreacted. A mathematical model of a fluid catalytic cracking （FCC） unit, which includes a quantitative correlation of CO heterogeneous combustion and the amount of CO combustion promoters, is introduced to investigate the effects of promoters on the three parts of combustion air. The results show that the air consumed by coke burning is almost linear to combustion air flow rate, while the air consumed by CO combustion promoters tends to saturate as combustion air flow rate increases, indicating that higher air flow rate can only be used as a manipulated variable to control the oxygen content for an economic concern.     

甲烷空气部分氧化制合成气喷动床反应器的研究

On the basis of hydrodynamic and scaling-up studies, a pilot-plant-scale thermal spouted bed reactor (50 mm in ID and 1500 mm in height) was designed and fabricated by scaling-down cold simulators. It was tested for making syngas via catalytic partial oxidation (CPO) of methane by air. The effects of various operating conditions such as operating pressure and temperature, feed composition, and gas flowrate etc. on the CPO process were investigated. CH4 conversion of 92.20％ and selectivity of 92.3% and 83.30/0 to CO and H2, respectively, were achieved at the pressure of 2.1 MPa. It was found that when the spouted bed reactor was operated within the stable spouting flow regime, the temperature profiles along the bed axis were much more uniform than those operated within the fixed-bed regime. The CH4 conversion and syngas selectivity were found to be close to thermodynamic equilibrium limits. The results of the present investigation showed that spouted bed could be considered as a potential type of chemical reactor for the CPO process of methane.     

Synthesis and catalytic activity of SBA-15 supported catalysts for styrene oxidation

Cu(II) and Mn(II) metals embedded on mesoporous SBA-15 were synthesized by co-precipitation technique.The support and catalysts were characterized by SEM–EDX,TEM,BET,XRD and ICP-AES methods.The catalytic activity of these catalysts was evaluated for styrene oxidation at various reaction conditions such as styrene to TBHP mole ratio,temperature,catalyst amount by using TBHP as an oxidizing agent.Major reaction products were styrene oxide and benzaldehyde and highest styrene conversion(97.3%) was observed at styrene to TBHP mole ratio of 1:4,temperature at 80 °C and 20 mg of catalyst.Further,the recyclability of the catalysts was observed and found that they can be recycled three times without major loss in their activity and selectivity.     

A comprehensive fractal char combustion model☆

The char combustion mechanisms were analyzed and a comprehensive fractal char combustion model was developed to give a better understanding and better predictions of the char combustion characteristics. Most of the complex factors affecting the char combustion were included, such as the coupling effects between the pore diffusion and the chemical reactions, the evolution of the char pore structures and the variation of the apparent reaction order during combustion, the CO/CO2 ratio in the combustion products and the correction for oxy-char combustion. Eleven different chars were then combusted in two drop tube furnaces with the conversions of the partly burned char samples measured by thermogravimetric analysis. The combustion processes of these chars were simulated with the predicted char conversions matching very well with the measured data which shows that this char combustion model has good accuracy. The apparent reaction order of the char combustion decreases, stabilizes and then increases during the combustion process. The combustion rates in the oxy-mode are general y slower than in the air-mode and the effect of the char-CO2 gasification reac-tion becomes obvious only when the temperature is relatively high and the O2 concentration is relatively low.     

甲烷/乙烷/空气预混火焰层流燃烧速度与火焰稳定性的数值研究(英文)

A numerical study on premixed methane/ethylene/air flames with various ethylene fractions and equivalence ratios was conducted at room temperature and atmospheric pressure. The effects of ethylene addition on laminar burning velocity, flame structure and flame stability under the condition of lean burning were investigated. The results show that the laminar burning velocity increases with ethylene fraction, especially at a large equivalence ratio. More ethylene addition gives rise to higher concentrations of H, O and OH radicals in the flame, which significantly promotes chemical reactions, and a linear correlation exists between the laminar burning velocity and the maximum H + OH concentration in the reaction zone. With the increase of ethylene fraction, the adiabatic flame temperature is raised, while the inner layer temperature becomes lower, contributing to the enhancement of combustion. Markstein length and Markstein number, representative of the flame stability, increase as more ethylene is added, indicating the tendency of flame stability to improve with ethylene addition.     

Comparison of steam-gasification characteristics of coal char and petroleum coke char in drop tube furnace

The steam-gasification reaction characteristics of coal and petroleum coke (PC) were studied in the drop tube fur-nace (DTF). The effects of various factors such as types of carbonaceous material, gasification temperature (1100–1400 °C) and mass ratio of steam to char (0.4:1, 0.6:1 and 1:1 separately) on gasification gas or solid products were investigated. The results showed that for al carbonaceous materials studied, H2 content exhibited the larg-est part of gasification gaseous products and CH4 had the smal est part. For the two petroleum cokes, CO2 content was higher than CO, which was similar to Zun-yi char. When the steam/char ratio was constant, the carbon con-version of both Shen-fu and PC chars increased with increasing temperature. When the gasification temperature was constant, the carbon conversions of al char samples increased with increasing steam/char ratio. For al the steam/char ratios, compared to water gas shift reaction, char-H2O and char-CO2 reaction were further from the thermodynamic equilibrium due to a much lower char gasification rate than that of water gas shift reaction rate. Therefore, kinetic effects may play a more important role in a char gasification step than thermodynamic ef-fects when the gasification reaction of char was held in DTF. The calculating method for the equilibrium shift in this study wil be a worth reference for analysis of the gaseous components in industrial gasifier. The reactivity of residual cokes decreased and the crystal layer (L002/d002) numbers of residual cokes increased with increasing gasification temperature. Therefore, L002/d002, the carbon crystallite structure parameter, can be used to evaluate the reactivity of residual cokes.     

STEADY STATE MULTIPLICITY FEATURES OF ETHYLENE OXIDATION ON PLATINUM FOIL

The catalytic oxidation of ethylene to carbon dioxide in excess air has been studied atsteady state.The catalyst temperature was measured for various feed temperature and concentration.The bifurcation diagrams Which describe the dependence of the catalyst temperature on the feed gastemperature were obtained for different ethylene concentrations in the feed gas.The ignition and ex-tinction temperatures were found out and the unique and multiple steady state regions could bedetermined from these diagrams.The experimental results can be satisfactorily explained by thecatastrophe theory and singularity theory.According to the steady state multiplicity features an at-tempt to discriminate the competitive kinetic models was made for the reaction.