Co-pyrolysis of soybean soapstock with iron slag/aluminum scrap,and characterization and analysis of their products

Soybean soapstock(SS) is one of the main solid wastes produced in the refinery of edible oil processing. In this study, the co-pyrolysis of SS with iron slag(IS) and aluminum scrap(AS) was carried out in a tubular furnace. The gas, liquid and solid products were characterized and the char yield decreased with increasing IS/AS ratio. IS and AS can improve the gas yield, and when the ratio of SS/IS was 1:0.25, the total pyrolysis gas and hydrogen contents were significantly increased. The content ...     

进口甲烷再燃烧对煤粉燃烧以及NOx生成影响的数值模拟

A full two-fluid model of reacting gas-particle flows and coal combustion is used to simulate coal combustion with and without inlet natural gas added in the inlet. The simulation results for the case without natural gas burning is in fair agreement with the experimental results reported in references. The simulation results of different natural gas adding positions indicate that the natural gas burning can form lean oxygen combustion enviroment at the combustor inlet region and the NOx concentration is reduced. The same result can be obtained from chemical equilibrium analysis.     

Carbon nanotubes loaded with vanadium oxide for reduction NO with NH3 at low temperature☆

The catalytic activity of carbon nanotubes-supported vanadium oxide (V2O5/CNTs) catalysts in the selective catalytic reduction (SCR) of NO with NH3 at low temperatures (≤250 °C) was investigated. The effects of V2O5 loading, reaction temperature, and presence of SO2 on the SCR activity were evaluated. The results show that V2O5/CNTs catalysts exhibit high activity for NO reduction with NH3 at low-temperatures. The catalysts also show very high stability in the presence of SO2. More interestingly, their activities are significantly promoted in-stead of being poisoned by SO2. The promoting effect of SO2 is distinctly associated with V2O5 loading, particularly maximized at low V2O5 loading, which indicated the role of CNTs support in this effect. The promoting effect of SO2 at low temperatures suggests that V2O5/CNTs catalysts are promising catalytic materials for low-temperature SCR reactions.     

Thermophoresis effects on gas-particle phases flow behaviors in entrained flow coal gasifier using Eulerian model

A numerical model based on the Eulerian–Eulerian two-fluid approach is used to simulate the gasification of coal char inside an entrained flow gasifier. In this model, effects of thermophoresis of coal char particles are thoroughly investigated. The thermophoresis is due to the gas temperature gradient caused by absorpted heat of coal char gasification. This work, firstly, calculates the gas temperature gradient and thermophoretic force at1100 °C,1200 °C,1300 °C and 1400 °C wall temperatures. Then, the changes of particle volume fraction and velocity in the gasifier are studied in the simulation with thermophoresis or not. The results indicate that considering the particle thermophoresis has some effects on the calculation of particle volume fraction in the gasifier, especially at wall temperature of 1400 °C, and the maximum particle volume fraction variance ratio reaches up to 1.38% on wall surface of the gasifier. These effects are mainly caused by large gas temperature gradient along the radial direction of the gasifier. For the particle velocity, the changes are small but can be observable along radial direction of the gasifier, which has good agreement with the distributions of radial gas temperature gradient and thermophoretic force. These changes above may have certain effects on gasification reaction rates in this Eulerian model. So the change of gasification reaction rates in the simulation with thermophoresis or not is studied finally.     

煤矸石盐酸浸溶出铝铁的动力学研究（英文）

The extraction of aluminum from coal mining waste (CMW) is an important industrial process. The two major problems in applications are low aluminum dissolution efficiency and high iron content in the raw material, which affect the quantity and quality of products. To improve the aluminum recovery process, the leaching kinet-ics of CMW with hydrochloric acid was studied. A shrinking core model was used to investigate aluminum and iron dissolution kinetics. Based on the kinetic characteristics, a process for recovering aluminum was proposed and tested experimental y. It is found that the aluminum leaching reaction is controlled by surface reaction at low temperatures (40–80 °C) and by diffusion process at higher temperatures (90–106 °C). The iron dissolution process is dominated by surface reaction at 40–100 °C. The results show that iron could be dissolved or separated by concentrated hydrochloric acid. Fine grinding wil improve aluminum dissolution significantly.     

基于FTIR分析的稻草热解机理

The pyrolysis mechanism of rice straw (RS) was investigated using a tube reactor with Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analyzer. The results show that the maximum pyrolysis rate increases with increasing heating rate and the corresponding temperature also increases. The three-pseudocomponent model could describe the pyrolysis behavior of rice straw accurately. The main pyrolysis gas products are H2O, CO2, CO, CH4, HCHO (formaldehyde), HCOOH (formic acid), CH3OH (methanol), C6H5OH (phenol), etc. The releasing of H2O, CO2, CO and CH4 mainly focuses at 220-400°C. The H2O formation process is separated into two stages corresponding to the evaporation of free water and the formation of primary volatiles. The release of CO2 first increases with increasing temperature and gets the maximum at 309°C. The releasing behavior of CO is similar to H2O and CO2 between 200 and 400°C. The production of CH4 happens, compared to CO2 and CO, at higher temperatures of 275-400°C with the maximum at 309°C. When the temperature exceeds 200°C, hydroxyl and aliphatic C H groups decrease significantly, while C O, olefinic C C bonds and ether structures increase first in the chars and then the aromatic structure develops with rising temperature. Above 500°C, the material becomes increasingly more aromatic and the ether groups decreases with an increase of temperature. The aromatization process starts at ≈350°C and continues to higher temperatures.     

Flux mechanism of compound flux on ash and slag of coal with high ash melting temperature

The melting temperature of Z coal ash was reduced by adding calcium–magnesium compound flux(W_(CaO)/W_(MgO)=1). In the process of simulated coal gasification, the coal ash and slag were prepared. The transformation of minerals in coal ash and slag upon the change of temperature was studied by using X-ray diffraction(XRD). With the increase of temperatures, forsterite in the ash disappears, while the diffraction peak strength of magnesium spinel increases,and the content of the calcium feldspar increases, then the content of the amorphous phase in the ash increases obviously. The species and evolution process of oxygen, silicon, aluminum, calcium, magnesium at different temperatures were analyzed by X-ray photoelectron spectroscopy(XPS). The decrease of the ash melting point mainly affects the structural changes of silicon, aluminum and oxygen. The coordination of aluminum and oxygen in the aluminum element structure, e.g., tetracoordinated aluminum oxide, was changed. Tetrahedral [AlO_4] and hexacoordinated aluminoxy octahedral [AlO_6] change with the temperature changing. The addition of Ca~(2+) and Mg~(2+) destroys silica chain, making bridge oxide silicon change into non-bridge oxysilicon; and bridge oxygen bond was broken and non-bridge oxygen bond was produced in the oxygen element structure. The addition of calcium and magnesium compound flux reacts with aluminum oxide tetrahedron, aluminum oxide octahedron and silicon tetrahedron to promote the breakage of the bridge oxygen bond. Ca~(2+) and Mg~(2+) are easily combined with silicon oxide and aluminum oxide tetrahedron and aluminum. Oxygen octahedrons combine with non-oxygen bonds to generate low-melting temperature feldspars and magnesite minerals, thereby reducing the coal ash melting temperatures. The structure of kaolinite and mullite was simulated by quantum chemistry calculation, and kaolinite molecule has a stable structure.     

Suppressing secondary reactions of coal pyrolysis by reducing pressure and mounting internals in fixed-bed reactor

Pyrolysis of Shenmu coal was performed in fixed-bed reactors indirectly heated by reducing operating pressure and mounting internals in the reactor to explore their synergetic effects on coal pyrolysis. Mounting internals particularly designed greatly improved the heat transfer inside coal bed and raised the yield of tar production.Reducing pressure further facilitated the production of tar through its suppression of secondary reactions occurring in the reactor. The absolute increase in tar yield reached 3.33 wt% in comparison with the pyrolysis in the reactor without internals under atmospheric pressure. The obtained tar yield in the reactor with internals under reduced pressure was even higher than the yield of Gray–King assay. Through experiments in a laboratory fixed bed reactor, it was also clarified that the effect of reducing pressure is related to volatile release rate in pyrolysis. It did not obviously vary tar yield at pyrolysis temperatures below 600 °C, while the effect was evident at 650 and 700 °C but became limited again above 800 °C. Under reduced pressure the produced tar contained more aliphatics and phenols but less aromatics.     

Absorption of Low Concentration Sulfur Dioxide Using Liquid-containing Microporous Membrane

The absorption of low concentration SO2 in flue gas by using the module of liquid-containing microporous membrane which is made up of hollow fiber and citric acid-sodium citrate buffer solution was investigated. The absorption efficiency of hydrophilic and hydrophobic membranes by using the concept of dynamic contact angle was mainly studied. The influences on absorption efficiency from absorption time, flowrate of gas phase, SO2 concentration of gas phase, air pressure, citrate concentration, pH value of solution as well as the generation of sulfate radical in absorption solution were examined. The results indicate that the hydrophobic hollow fiber membrane is better than hydrophilic membrane, the absorption efficiency decreases with increasing absorption time, gas phase flowrate, gas phase SO2 concentration and air pressure, the absorption rate and capacity of SO2 can be improved by increasing the citrate concentration, the absorption efficiency can be improved by increasing the pH value of citrate solution, the concentration of SO42- in absorption solution increases linearly with the absorption time at a rate around 0.192 g/(L×h).     

Evolvement behavior of microstructure and H2O adsorption of lignite pyrolysis☆

The effect of pyrolysis on the microstructure and moisture adsorption of lignite was investigated with low field nuclear magnetic resonance spectroscopy. Changes in oxygen-containing groups were analyzed by Fourier transform infrared spectroscopy(FTIR), and H2 O adsorption mechanism on the surface of lignite pyrolysis was inferred. Two major changes in the pore structure of lignite char were observed as temperature increased in 105–200 °C and500–700 °C. Pyrolysis temperature is a significant factor in removing carboxyl and phenolic hydroxyl from lignite.Variation of ether bond content can be divided into three stages; the content initially increased, then decreased,and finally increased. The equilibrium adsorption ratio, content of oxygen-containing groups, and variation of pore volume below 700° were closely correlated with each other. The amount of adsorbed water on char pyrolyzed at700 °C increased. Moreover, the adsorption capacity of the lignite decreased, and the adsorption state changed.     

Pyrolysis of coal and iron oxides mixtures. 2. Reduction of iron oxides

The reduction of iron oxides during the pyrolysis of blends of coal and iron oxides on a laboratory scale, has been studied. The pyrolysis of blends of bituminous coal and 30 wt% of magnetite or hematite has been studied by thermogravimetry and analysis of gases, using a heating rate of 3.2 K min^?1. The state of iron in ferrocoke has been established by X-ray diffraction. A primary reduction by hydrogen and carbon monoxide of the hematite has been observed at between 400 °C and 500 °C, but hidden in thermogravimetric measurements by primary volatilization of the coal. At ≈600 °C magnetite is progressively reduced to wustite and then to iron. This reduction starts a little earlier if the heating rate is slow and the coal rank is low and progresses more rapidly when using hematite. Except for higher heating rates in the coal-magnetite blends, the reduction is complete at 1000 °C. The reductants are H₂ and CO, with production of H₂O and CO₂. When the temperature is increased the reduction by CO becomes of increasing importance, being mainly produced from the coke by the Boudouard reaction. The consumption of coke for the reduction of iron oxides is therefore more important at higher temperatures. Lignite is clearly a better reducing agent than the other coals, because of larger quantities of CO produced from the start of its pyrolysis, and the good reactivity of its char towards CO₂ and H₂O.     

胜利褐煤快速热解特性

为考察热解温度对热解产物品质及挥发分残留的影响,在10 kg/h自制褐煤快速热解提质试验设备上,以胜利褐煤为试验原料,考察了400~900℃热解提质温度对热解产物产率、气体产物组成、半焦微观结构以及残余挥发分的影响。结果表明,随着热解温度的升高,半焦产率逐渐降低,气体产率升高,焦油的产率先升高后降低,700℃时焦油产率最大;热解气体中的CO_2随着热解温度的升高逐渐降低,H_2和CO含量随着热解温度的升高而增加;随着热解温度的升高,挥发分不断释放导致半焦含氧官能团以及高活性的小的缩合芳环减少;热解温度≥700℃,半焦残留的挥发分较低,固定碳较多,基本满足电石用焦的要求。     

煤快速热解固相和气相产物生成规律

利用能有效避免二次转化反应的高频炉热解装置对3种不同变质程度的煤进行了600～1200℃条件下的快速热解,考察了在煤热解最初阶段焦产率、焦-C产率、热解气产率、热解气4种主要组分H₂、CO、CH₄和CO₂的比例以及热解气热值随煤阶和热解温度的变化规律。结果表明,焦的产率和焦-C的产率均随煤阶的升高而升高,热解气的产率随煤阶的升高而降低;热解温度的提高能显著降低煤焦和焦-C的产率并提高热解气的产率。热解气组分以H₂相似文献   

Catalytic liquefaction of coal with supercritical water/CO/solvent media

This paper describes studies of the catalytic activity of cobalt molybdenum sulphide, cobalt molybdenum oxide, iron sulphate, iron acetate dibasic and H₂S during the reaction between supercritical CO and water, and during liquefaction of coal using supercritical CO-water-solvent mixtures. The kinetics of the water gas shift reaction was studied first and was found to be first order in all the catalysts studied. The activity of the catalysts decreased in the following order: cobalt molybdenum sulphide > cobalt molybdenum oxide > iron salts. The presence of toluene, tetralin, and THQ decreased the CO conversion on the cobalt catalysts but increased CO conversion in the presence of iron salts catalysts. Moderate coal conversion of toluene soluble products (25%–35%) were obtained in the presence of supercritical water and water/CO mixtures. Addition of organic solvents to a supercritical water/CO medium increased conversion of toluene soluble products to 70–80% for THQ, to 50–60% for tetralin, and to 35–40% for toluene. Addition of H₂S to the solvent/water/CO medium increased conversion to toluene soluble products even further. In the presence of H₂S/solvent/water/CO, the presence of catalysts had only a minor effect on coal conversion and were not required to achieve high coal conversions. The optimum operating conditions for an Illinois No. 6 coal were obtained using a H₂S/THQ/CO/water medium at 3600 psi, and 400 °C. Higher conversions were attained with a subbituminous Wyodak coal. These studies clearly demonstrate that high conversions to soluble products can be attained using a supercritical water/Co/solvent medium.     

Uneven distribution of sulfurs and their transformation during coal pyrolysis

Two Chinese coals, Liuzhi high pyrite coal with high ash content (LZ) and Zunyi high organic sulfur coal (ZY), were pyrolyzed in a fixed-bed reactor under nitrogen and hydrogen at temperature ranging from 400 to 700 °C. The effects of heat rate, temperature and gas atmosphere on sulfur transformation and sulfur uneven distribution were examined by XPS combined with traditional sulfur analysis method. The ratio of surface S to bulk S is used to describe the uneven distribution of sulfurs. It is found that oxygen is rich on the surface, while S in the bulk. The increasing ratio of surface S to bulk S with increasing temperature clearly indicates the sulfur transfer from the bulk to the char surface during pyrolysis. The ratios are higher at all temperatures studied for ZY coal than for LZ coal, which may be related to the higher ash content in LZ coal. The ratio of surface S to bulk S increases with increasing heating rate for LZ coal, while it decreases for ZY coal. In the presence of H₂, the S on the surface is much lower than that under N₂ and surface S in sulfidic, thiophenic and sulfoxide forms is totally disappeared for LZ coal at various temperatures and heating rates, while the surface S in thiophenic and sulfoxide forms is not totally disappeared for ZY coal, which may be related to the high rank of ZY coal. The ratio of surface S to bulk S decreases before 600 °C with increasing temperature for both coals in the presence of H₂, showing that gaseous H₂ can easily react with the surface S to form H₂S, while above 600 °C it increases because the supply of H₂ cannot match the rate of formation of HS free radicals at high temperature.     

平朔煤的热解试验研究

对平朔煤在不同温度下进行了热解研究,考察了热解温度对煤热解产物产率和热解气性质的影响规律。研究表明,对上述煤样,随煤的热解温度升高,半焦产率下降,干馏气产率增加;液体率在一定温度范围内先增后降,在600℃左右达到最高。热解温度升高,热解气中H2的含量就越高,热解气中CH4的含量在热解温度550～650℃左右达到最高。随热解温度的升高,CO2的含量显著降低,烃类组分随温度升高是先升后降,峰值出现在600℃左右。     

钙基添加剂对煤慢速和快速热解行为的影响

在固定床反应器上对淮北煤(Hub)进行热解实验,测定了气体、焦油和焦炭的产率、主要气体的累积释放量以及苯、甲苯和二甲苯(BTX)产率,旨在考察2种常见钙基添加剂CaCO3和Ca(OH)2对煤慢速和快速热解的影响。在慢速热解情况下,无论CaCO3还是Ca(OH)2都使焦炭产率明显降低,气体产率上升,焦油产率有所下降,BTX产率增大,但Ca(OH)2的作用较强。在快速热解情况下,钙基添加剂使焦油产率略有下降,气体和焦炭产率略有增大,但增加不明显。由此表明,钙基添加剂在慢速热解时对焦油二次裂解及对煤焦分解的作用较大。     

温度对循环流化床双床气化中热解炉产物的影响

在循环流化床双床煤高温热解气化试验台上,以神木烟煤为燃料在不同温度下进行了热解气化试验,该试验台利用上下返料器将热解炉和气化炉耦合在一起,其中热解炉为N2气氛,气化炉通入空气作为气化剂,试验主要研究热解炉底部温度对热解煤气及热解炉底渣的影响。试验结果表明:随热解炉底部温度升高,热解煤气中H2体积分数升高,CH4,CO2体积分数降低,CO体积分数先降低后升高,热解煤气主要组分气体的收率增加。试验所取热解炉底渣样品的孔比表面积分布和孔比体积分布主要集中于中小孔(0—50 nm),其总比表面积和总孔体积大小顺序为在817℃最大,844℃次之,766℃最小,在N2气氛、1 200℃条件下,CO2反应的活性大小顺序为817℃最大,766℃次之,844℃最小。     

煤的微波热解研究进展

煤炭是我国的主要能源,煤的清洁高效利用是我国能源安全和生态环境建设的重要保障。热解是在温和条件下将煤转化为洁净的气体、液体和固体燃料,是改善煤炭利用、加工转化成清洁高效的二次能源的重要手段之一。微波作为一种新的加热方式在煤的热解方面的应用的优势越来越明显。本文概述了微波热解的机理与优点、微波吸收剂的应用以及国内外微波热解研究进展,得出了低阶煤介电常数较小,需要添加一定量的微波吸收剂才能达到热解温度;和常规热解相比,微波热解改变了物质的加热方式,改善了热解产物的品质,热解气中CO、H₂含量增加,焦油品质较好,提高了煤的热解效率。作为一种新型加热方式,微波技术为煤热解效率的提高提供了新的解决方案和思路。