Simulation Research on Coal-Water Slurry Gasification of Oil-Based Drill Cuttings Based on Fluent

In this paper,based on Fluent software,a five-nozzle gasifier reactor was established to simulate the gasification process of oil-based drill cuttings coal-water slurry.The influence of concentration and oxygen/carbon atomic ratio on the gasification process of oil-based drill cuttings coal-water slurry was investigated.The results show that when the oxygen flow is constant,the outlet temperature of gasifier decreases,the content of effective gas increases,and the carbon conversion rate decreases with the increase of concentration;When the ratio of oxygen to carbon atoms is constant,the effective gas content rises and the temperature rises with the increase of the concentration,and the carbon conversion rate reaches the maximum value when the concentration of oil-based drill cuttings coal-water slurry is 65%;When the concentration is constant,the effective gas content decreases and the outlet temperature rises with the increase of the oxygen/carbon atom ratio,and the carbon conversion rate reaches 99.80%when the oxygen/carbon atom ratio is 1.03.It shows that this method can effectively decompose the organic matter in oilbased drill cuttings and realize the efficient and cooperative treatment of oil-based drill cuttings.

Progress on Heat Transfer in Fractures of Hot Dry Rock Enhanced Geothermal System

Hot Dry Rock(HDR)is the most potential renewable geothermal energy in the future.Enhanced Geothermal System(EGS)is the most effective method for the development and utilization of HDR resources,and fractures are the main flow channels and one of the most important conditions for studying heat transfer process of EGS.Therefore,the heat transfer process and the heat transfer mechanism in fractures of EGS have been the hot spots of research.Due to the particularity of the mathematical models of heat transfer,research in this field has been at an exploratory stage,and its methods are mainly experimental tests and numerical simulations.This paper introduces the progress on heat transfer in fractures of Hot Dry Rock EGS in detail,provides a comparative analysis of the research results and prospects for future research directions:It is suggested that relevant scholars should further study the mathematical equations which are applicable to engineering construction of seepage heat transfer in irregular fractures of the rock mass,the unsteady heat transfer process between multiple fractures of the rock mass and the heat transfer mechanism of the complex three-dimensional models of EGS.

Combustion mechanism of fluorinated organic compound-modified nano-aluminum composite particles:Towards experimental and theoretical investigations

Fluorinated Organic Compounds(FOCs)are commonly used as modifiers for Aluminum(Al)powder to improve its ignition,combustion,and agglomeration characteristics.However,the effects of FOCs on combustion and inhibition mechanisms of agglomeration of Al powder are not well understood.In this paper,based on the experimental study of Fluorinated Graphite(FG)-modified Al matrix composite particles,the combustion and aggregation inhibition mechanisms of FOCs on Al particles were studied by the quantum chemical calculation at B3LYP/6-311+G(d,P)and G3//B3LYP/6-311+G(d,p)levels.The flame behavior and single particle burning behavior of FG-modified samples were compared through ignition experiments,and the characteristic spectra of Al related oxides of different samples in the initial ignition stage were captured.It is found that FG increases the burning intensity of Al composite samples significantly,while it decreases the emission intensity of Al secondary oxides.Quantum chemical calculation results show that the thermal decomposition intermediates of FOCs,namely C_(2)F_(4),can react with AlO and Al_(2)O,which weakens the characteristic emission intensity of AlO and Al_(2)O in the sample,and thus inhibits the formation of Al_(2)O_(3)in the combustion process.These results contribute to enriching the combustion dynamics model of Al-FOCs reaction system.

Using polyvinylidene fluoride to improve ignition and combustion of micron-sized boron powder by fluorination reaction

Boron has a promising application in the field of propellants due to its high calorific value.However,the difficulty of ignition and the poor combustion efficiency of boron(B)have severely limited its efficient application.In response to this issue,this paper proposes to improve the ignition and combustion performance of micron-sized boron by the Polyvinylidene Fluoride(PVDF)coating.The effect of PVDF content on the B combustion performance was systematically studied using a Thermogravimetry-Differential Scanning Calorimetry(TG-DSC),a Transmission Electron Microscope(TEM),an X-Ray Diffractometer(XRD),a laser Particle Size Analyzer(PSA),and a high-speed camera.The results show that PVDF can significantly reduce the initial oxidation temperature of B powder and increase its reaction heat.When the PVDF content is 23wt%,the reaction heat and the combustion intensity of B powder reach the maximum and are significantly higher than those of the uncoated B powder.Moreover,the fluorination reaction that occurs during the combustion process not only can effectively shorten the combustion time of B powder,but also has a positive effect on its flame intensity and propagation speed,and it significantly reduces B particle agglomeration,which improves the combustion efficiency significantly.This study lays the foundation for the application of PVDF modified B in B-based solid propellants.

铝–油酸/正庚烷基纳米浆体燃料液滴着火燃烧特性

采用液滴悬挂法研究了正庚烷液滴、油酸/正庚烷混合燃料液滴、含20wt%纳米铝粉的铝–油酸/正庚烷基纳米浆体燃料液滴在不同温度下(600~800℃)的着火燃烧特性。用高速摄像机观测液滴进入管式电阻炉后的着火燃烧过程,使用热电偶记录液滴周围的气相温度变化,同时通过对应的温度曲线计算液滴的着火延迟时间。结果表明,纳米铝粉和油酸的添加均能降低正庚烷液滴的着火延迟时间。随温度升高,正庚烷、油酸/正庚烷混合燃料、铝–油酸/正庚烷基纳米浆体燃料液滴的着火延迟时间显著降低,但变化趋势逐渐趋于平缓。铝–油酸/正庚烷基纳米浆体燃料液滴的着火延迟时间与环境温度满足阿累尼乌斯方程。与纯正庚烷、油酸/正庚烷混合液滴的燃烧过程相比,铝–油酸/正庚烷基浆体燃料液滴的燃烧过程有显著差异,其燃烧经历3个阶段:正庚烷稳定燃烧阶段、正庚烷微爆炸阶段和表面活性剂微爆炸阶段。铝–油酸/正庚烷基浆体燃料液滴燃烧时间延长,火焰熄灭后又复燃,且燃烧过程中发生剧烈的火焰形变和铝颗粒溅射现象,大部分铝以团聚体形式在第三阶段完成氧化还原反应。

Fe2O3/AC催化剂的低温选择性催化还原脱硝性能

以活性焦（AC）为载体、Fe2O3为活性组分,采用等体积浸渍法制备Fe2O3/AC催化剂,研究了Fe含量对Fe2O3/AC催化剂低温脱硝性能的影响.结果表明,当Fe负载量为6wt%时能获得比其它负载量更佳的NOx转化率,尤其在240℃时NOx转化率达93.9%,当分别有120′10-6（vol）SO2和3.5vol H2O存在时,脱硝率分别稳定在约86%和74%;催化剂孔径≤4 nm,随Fe负载量增加,孔径呈增大趋势;催化剂较稳定;Fe主要以γ-Fe2O3分散在催化剂表面,负载适量Fe2O3使表面吸附氧Oβ和Fe3＋增多,为催化剂提供更多活性位,提高了Fe2O3/AC催化剂的低温选择性催化还原脱硝活性.

Ce改性Fe2O3/AC催化剂低温SCR脱硝性能

以活性焦（AC）为载体、Fe和Ce为活性组分,采用等体积浸渍法制备了Fe2O3/AC和Ce-Fe2O3/AC催化剂,研究了Fe含量及Ce掺杂对Fe2O3/AC催化剂低温脱硝性能的影响,并对催化剂进行了表征.结果表明,当Fe负载量为6wt%时,Fe2O3/AC催化剂的NOx转化率最高,240℃下达93.9%.掺杂Ce后Ce-Fe2O3/AC催化剂的催化效率明显提高,当质量比Ce：Fe=0.5：6时,NOx转化率较高,120～200℃下NOx转化率比负载6wt%Fe的催化剂提高了5%～20%,且抗硫性能较好,240℃下通入100×10^-6（vol）SO2,NOx转化率稳定在94.1%.掺杂少量Ce可使γ-Fe2O3均匀分散在催化剂表面,且表面吸附氧Oα比例增大,催化剂的还原性增强,促进了选择性催化还原反应进行.

Chromosome-level Genomes Reveal the Genetic Basis of Descending Dysploidy and Sex Determination in Morus Plants

Multiple plant lineages have independently evolved sex chromosomes and variable karyotypes to maintain their sessile lifestyles through constant biological innovation.Morus notabilis,a dioecious mulberry species,has the fewest chromosomes among Morus spp.,but the genetic basis of sex determination and karyotype evolution in this species has not been identified.In this study,three high-quality genome assemblies were generated for Morus spp.[including dioecious M.notabilis(male and female)and Morus yunnanensis(female)]with genome sizes of 301–329 Mb and were grouped into six pseudochromosomes.Using a combination of genomic approaches,we found that the putative ancestral karyotype of Morus species was close to 14 protochromosomes,and that several chromosome fusion events resulted in descending dysploidy(2n=2x=12).We also characterized a~6.2-Mb sex-determining region on chromosome 3.Four potential male-specific genes,a partially duplicated DNA helicase gene(named MSDH)and three Ty3_Gypsy long terminal repeat retrotransposons(named MSTG1/2/3),were identified in the Y-linked area and considered to be strong candidate genes for sex determination or differentiation.Population genomic analysis showed that Guangdong accessions in China were genetically similar to Japanese accessions of mulberry.In addition,genomic areas containing selective sweeps that distinguish domesticated mulberry from wild populations in terms of flowering and disease resistance were identified.Our study provides an important genetic resource for sex identification research and molecular breeding in mulberry.

Promotional effect of silica on the combustion of nano-sized aluminum powder in carbon dioxide

This paper presents how the combustion performance of nano-sized aluminum(nAl)powder in carbon dioxide are affected by silica. The ignition and combustion performance of nAl powder with silica addition were studied by a high-temperature tube furnace. An s-type thermocouple and a high-speed motion acquisition instrument were performed to evaluate the ignition temperature, maximum combustion temperature, maximum change of rate of temperature, and combustion propagation speed. The combustion efficiency and combustion products were measured and analyzed by a gas-volumetric method and an X-ray diffraction. The results show that silica added into nAl powder can enhance its maximum combustion temperature and maximum change of rate of temperature, while its ignition temperature increases slightly. The nAl powders with addition of 6.00 wt.% and 12.00 wt.% silica present high combustion propagation speeds, especially for the latter, it has high combustion efficiency. The effect mechanism of silica on the combustion of nAl powder in carbon dioxide was discussed.

KF对微米铝粉在水蒸气中着火燃烧特性的影响

为改善微米铝粉在水蒸气中的着火特性和燃烧效率,采用自行设计的管式炉实验平台研究了KF对30mm铝粉在1000℃水蒸气中着火燃烧特性的影响。用高速摄影系统记录了样品着火燃烧过程,并通过X射线衍射、扫描电镜技术和化学分析方法分析了产物组分、形貌和燃烧效率。结果表明,加入KF可显著降低30mm铝粉的点火延迟时间,与加入5wt%(0.003 g)KF相比,加入15wt%(0.009 g)KF后,样品的点火延迟时间减少了47.58 s;微米铝粉在1000℃水蒸气中不能着火,加入KF后能着火,这是因为KF与水蒸气反应生成KOH,KOH与Al2O3反应会破坏铝粉的氧化壳,加快铝与水蒸气的反应,促进铝粉着火。随KF加入量提高,样品的燃烧效率显著上升,最高为82.24%,比未添加KF样品的燃烧效率提升了38.75%。提高KF加入量,可产生更多的KOH,对氧化壳的破坏效果更显著,进一步促进铝与水蒸气反应,提高铝粉燃烧效率。

高氯酸铵含量对高铝富燃料推进剂中重要组分高氯酸铵/铝一次燃烧性能和铝粉团聚的影响

采用CO2激光点火装置联合高速摄影系统及扫描电子显微镜等凝聚相燃烧产物分析技术,研究了高氯酸铵(AP)含量对高Al富燃料推进剂中重要组分AP/Al一次燃烧过程中燃烧现象、引燃时间、燃烧扩散时间、燃尽时间、燃烧效率、颗粒团聚及凝聚相燃烧产物的表面形貌、粒径及其分布的影响。结果表明,各AP/Al混合粉体的燃烧过程均可分为表面引燃、燃烧扩散和火焰熄灭3个阶段,但各样品在不同燃烧阶段的燃烧现象存在明显差异。AP含量由10wt%增至30wt%,样品燃烧剧烈程度增强,燃烧过程中固相颗粒的溅射现象越加明显;在火焰熄灭阶段,各样品燃烧由以停留在样品燃面处的燃烧为主逐渐变为以溅射颗粒的燃烧为主,且随反应进行,燃面已燃固相颗粒最先熄灭,各样品表面引燃时间、燃烧扩散时间、燃烧持续时间均缩短,即燃烧反应速率逐渐加快。在AP/Al混合物中,铝粉的燃烧效率、凝聚相燃烧产物粒度及其团聚程度随AP含量增加而增加。