Physicochemical characterization of Baizhi particles by ultrafine pulverization

Baizhi, as a medicinal plant, has been demonstrated to be useful for the treatment of aches and pains in China. The physicochemical characterization of Baizhi particles is greatly influenced by ultrafine pulverization. To study the physicochemical characterization of Baizhi, the raw plant material of Baizhi was ground to 6 μm particles by a high speed centrifugal sheering （HSCS） pulverizer. The micron particles were characterized by optical microscopy and scanning electron microscopy （SEM）. Imperatorin is one of the active ingredients of Baizhi, and its extraction yield is determined to evaluate the chemical characterization of Baizhi powder. Imperatorin was analyzed by high performance liquid chromatography （HPLC）. The results show that after ultrafine pulverization, the plant cell walls are broken into pieces and the extraction yield of imperatorin is increased by 11.93% compared with the normal particles.

The Nano Pulverization of Traditional Chinese Medicine Liuwei Dihuang

The crude drug of Liuwei Dihuang was pulverized to nano particles to improve its bioavailability. The appropriate technique parameters were studied. Paeonol, typical marker of Liuwei Dihuang , was extracted with organic solveat in ultrasonic and its content was determined by HPLC. The appropriate techrdques parameters are as follows ： rotating speed control 1200 r/ min , grinding time control 50min and mass percent concentration control 3.8% . The experimental results show that the average particle diameter is 161.9 nm and the great majority of the plant cell wall is broken into pieces after nano pulverization. The extraction efficiency of paeonol is increased by 23.5% .

Combustion performance of pulverized coal and corresponding kinetics study after adding the additives of Fe_(2)O_(3) and CaO

Combustion performance of pulverized coal(PC)in blast furnace(BF)process is regarded as a criteria parameter to assess the prop-er injection dosage of PC.In this paper,effects of two kinds of additives,Fe_(2)O_(3) and CaO,on PC combustion were studied using the thermo-gravimetric method.The results demonstrate that both the Fe_(2)O_(3) and CaO can promote combustion performance index of PC including igni-tion index(C_(i)),burnout index(D_(b)),as well as comprehensive combustibility index(S_(n)).The S_(n) increases from 1.37×10^(−6) to 2.16×10^(−6)%2·min^(−2)·℃^(−3) as the Fe_(2)O_(3) proportion increases from 0 to 5.0wt%.Additionally,the combustion kinetics of PC was clarified using the Coats-Redfern method.The results show that the activation energy(E)of PC combustion decreases after adding the above additives.For instance,the E decreases from 56.54 to 35.75 kJ/mol when the Fe_(2)O_(3) proportion increases from 0 to 5.0wt%,which supports the improved combustion per-formance.Moreover,it is uneconomic to utilize pure Fe_(2)O_(3) and CaO in production.Based on economy analysis,we selected the iron-bearing dust(IBD)which contains much Fe_(2)O_(3) and CaO component to investigate,and got the same effects.Therefore,the IBD is a potential option for catalytic PC combustion in BF process.

HYDROGEN PULVERIZATION OF Nb_3Al AND NbCr_2 ALLOYS

Measurements of hydrogen absorption desorption behavior of Nb Al alloys, Nb ss (Nb solid sloution), Nb ss +Nb 3Al, Nb 3Al, Nb 3Al+Nb 2Al, were carried out under hydrogen pressure from 0 to 3.4 MPa at 353 and 357 K, along with mircostructural observation and X ray diffraction analysis. It was found that single phase alloys of Nb ss and Nb 3Al are not pulverized regardless of a considerable amount of hydrogen absorption, while two phase alloys of Nb ss +Nb 3Al and Nb 3Al+Nb 2Al are readily pulverized. X ray diffraction analysis indicated that no hydride with crystal structure different from constituent phases is formed by hydrogen absorption, but lattice parameters of Nb ss and Nb 3Al are increased. Pulverization of Nb Cr alloys was investigated under a hydrogen atmosphere of 0.1 MPa in an arc melting chamber without exposure to air after arc melting. Similarly, hydrogen pulverization occurs only in two phase alloys consisting of Nb ss and NbCr 2. Based on the measured lattice parameters of Nb ss and Nb 3Al(NbCr 2) in the hydrogenated two phase alloys and the microstructural observations, a mechanism for hydrogen pulverization is discussed.

Effect of microstructure on the breakage of tin bronze machining chips during pulverization via jet milling

In this study, jet milling was used to recycle tin bronze machining chips into powder. The main purpose of this study was to assess the effect of the microstructure of tin bronze machining chips on their breakage behavior. An experimental target jet mill was used to pulverize machining chips of three different tin bronze alloys containing 7wt%, 10wt%, and 12wt% of tin. Optical and electron microscopy, as well as sieve analysis, were used to follow the trend of pulverization. Each alloy exhibited a distinct rate of size reduction, particle size distribution, and fracture surface appearance. The results showed that the degree of pulverization substantially increased with increasing tin content. This behavior was attributed to the higher number of machining cracks as well as the increased volume fraction of brittle δ phase in the alloys with higher tin contents. The δ phase was observed to strongly influence the creation of machining cracks as well as the nucleation and propagation of cracks during jet milling. In addition, a direct relationship was observed between the mean δ-phase spacing and the mean size of the jet-milled product; i.e., a decrease in the δ-phase spacing resulted in smaller particles.

An image segmentation method of pulverized coal for particle size analysis

An important index to evaluate the process efficiency of coal preparation is the mineral liberation degree of pulverized coal,which is greatly influenced by the particle size and shape distribution acquired by image segmentation.However,the agglomeration effect of fine powders and the edge effect of granular images caused by scanning electron microscopy greatly affect the precision of particle image segmentation.In this study,we propose a novel image segmentation method derived from mask regional convolutional neural network based on deep learning for recognizing fine coal powders.Firstly,an atrous convolution is introduced into our network to learn the image feature of multi-sized powders,which can reduce the missing segmentation of small-sized agglomerated particles.Then,a new mask loss function combing focal loss and dice coefficient is used to overcome the false segmentation caused by the edge effect.The final comparative experimental results show that our method achieves the best results of 94.43%and 91.44%on AP50 and AP75 respectively among the comparison algorithms.In addition,in order to provide an effective method for particle size analysis of coal particles,we study the particle size distribution of coal powders based on the proposed image segmentation method and obtain a good curve relationship between cumulative mass fraction and particle size.

大型燃煤锅炉中含Na/Cl/S组分的演变与受热面结渣倾向的数值模拟

提出了一种考虑煤中含Na/S/Cl组分多步释放、气相组分相互作用、气-固反应以及盐蒸气冷凝耦合灰颗粒黏附的结焦模型,以预测炉内受热面气态碱金属组分冷凝行为、受热面结焦风险以及炉膛出口Na/S/Cl组分分布特性。结果表明:炉膛出口气态含Na组分主要以NaO_(2)、NaCl、Na_(2)SO_(4)和NaOH形式存在;最上层燃烧器至分离燃尽风(SOFA)喷口区域、最下层燃烧器至冷灰斗转角区域的水冷壁结焦风险高;炉膛出口区域后屏过热器底部颗粒黏附位置相对集中,炉内辐射式过热器结焦速率远高于气态钠盐冷凝速率,对流受热面颗粒沉积速率约是钠盐蒸气冷凝速率的3~4倍。

包钢高炉喷吹煤粉利用率的测定

利用透射光偏光显微镜,对包钢高炉重力除尘灰、旋风除尘灰和布袋除尘灰中的碳素种类进行定性和定量分析,以测定高炉喷吹煤粉利用率。测定结果表明,3号高炉喷吹煤粉利用率上下限分别为89.03%和79.46%,4号高炉的喷吹煤粉利用率上下限分别为91.51%和84.14%。认为,3号高炉和4号高炉所使用喷吹煤粉来自同一系列,因此可以通过采取稳定煤粉粒度波动、优化富氧鼓风和提高入炉焦炭强度等措施,来提高喷吹煤粉利用率。

国内某高炉喷吹煤粉的性能评价

高炉喷吹煤粉的优点主要包括显著降低炼铁焦比及生产成本、有效调节高炉热制度、喷吹煤粉反应过程中提高煤气的穿透扩散能力和还原能力、缓解焦煤需求量、减少炼焦投资和环境污染等。为进一步优化高炉喷吹燃料结构和降低炼铁成本,文章对国内某高炉喷吹使用的煤粉的煤质特性进行了深入研究。结果表明:1#煤为烟煤,固定碳含量低、挥发分高,氢元素含量在所试验煤粉中最高,灰分中的CaO和MgO的含量之和最高,超过24%;其他煤种为无烟煤;4#煤的可磨性指数低于40;需要控制其在混煤中的配比。

德钢4号高炉烟气自循环制粉系统设计

对四川德胜集团钒钛有限公司应用不带脱水装置的烟气自循环制粉工艺进行了介绍和总结,该制粉工艺的烟气炉采用全烧高炉煤气、中速磨煤机制粉、一级大布袋收粉,磨制的烟煤挥发分为25%,在稳定生产期间系统末端氧含量控制在12%以内,粉尘排放浓度<10 mg/Nm^(3)。生产实践表明:不带脱水装置全烧高炉煤气的烟气自循环制粉工艺安全可靠,满足生产要求。

面向火电运行灵活性的钢球磨煤机制粉系统控制优化研究

针对双进双出钢球磨煤机制粉系统变出力过程风粉温度波动幅度大、瞬时磨煤出力偏差大等问题,提出考虑热一次风风温前馈和变出力过程料位差压设定值优化的控制策略。以BBD4360型钢球磨煤机为对象开展机理建模和瞬态扰动试验研究,建立并验证钢球磨煤机内料位差压、出口风粉温度等关键参数计算模型。基于磨煤机动态模型研究获得原有及优化后的控制策略对磨煤机出口风粉温度、磨煤出力和制粉单耗的影响规律。研究结果表明:在制粉系统变出力过程中,优化后的控制策略可降低磨煤机出口风粉温度偏差2℃以上,制粉系统磨煤出力累积偏差降低50%以上,制粉单耗降低5%以上,综合提升了制粉系统的关键参数控制效果。钢球磨煤机制粉系统优化控制策略有利于缓解机组调峰过程中由于燃料量供给偏差引起的气温、气压偏差大等问题,保障了燃煤发电机组的运行灵活性和高效性。

改性黄蒿型煤型焦的性状研究

采用2.5%NaOH改性的黄蒿为粘结剂,对六组不同粒级神木粉煤原料进行干法冷压制备改性黄蒿型煤,再经热解制备改性黄蒿型焦。借助扫描电镜(SEM)、红外光谱仪(FT-IR)对型煤和型焦进行表征,并测定其性能强度。结果表明,与型煤相比,型焦的红外特征峰强度明显减弱,谱峰数量减少,热解过程中主要发生脱水、裂解、缩聚反应,小分子及活性官能团被大量破坏,烃链结构缩合,型焦芳香度增加,其芳香度指数为4.34。型煤的性能强度随着神木煤粉粒度减小而减小。粒度较小的粉煤在成型压力作用下煤粒间隙越小,型煤脱模后受膨胀压力影响导致性能强度降低。粉煤粒度越大,煤粒间隙较大,可容纳较多粘结剂,并与煤粒产生一定的啮合力,保证了型煤的性能强度。型焦整体性能强度优于型煤。热解过程部分含氧官能团被C-C取代,并伴随挥发性物质逸出,产生的气孔分布均匀、壁厚较大,进而保证型焦性能强度。型焦强度随着神木煤粉粒度增大而增大,当神木粉煤粒级在(3~1.5)mm时,型焦抗压强度为3338.9 N/个,跌落强度为98.96%,抗碎强度为83.16%。

小麦秸秆制备热解型煤黏结剂的实验研究

以生物质和低阶粉煤为原料制备热解型煤是实现低阶粉煤高效清洁分质利用的重要技术之一。该研究以小麦秸秆水解残渣(WSR)为黏结剂主要成分,分别复配3种无机黏结剂成分和5种有机黏结剂成分,考察了黏结剂组成对型煤落下强度、热强度和热稳定性的影响规律,优选了膨润土、碱性淀粉、腐植酸钠(HA-Na)等3种黏结剂成分,采用正交试验对复合黏结剂的组成进行了优化。在最优复合黏结剂配比(WSR 12.5%,膨润土3%,HA-Na 3%,碱性淀粉1%)条件下,制备的型煤落下强度为98%,冷压强度3 161 N/个,热强度1 231 N/个,热稳定性99%。

纳米粉碎对3种食用菌风味特征及减盐增鲜效果的影响

目的:优化食用菌的加工工艺,评估其作为风味剂在食品工业中的应用潜力。方法:使用离子色谱仪和高效液相色谱仪对样品的非挥发性滋味成分含量进行测定,并通过等鲜浓度值来评估样品的鲜味;运用GC-MS、电子鼻和电子舌来检测样本中的挥发性香气成分,观察纳米粉碎前后的微观结构,并进行增鲜减盐试验。结果:纳米粉碎后,大球盖菇和双孢蘑菇的鲜味氨基酸、呈味核苷酸和有机酸含量显著增加,挥发性化合物的种类和数量显著增加,而纳米粉碎对草菇的风味成分影响较小;电子舌结果表明,经纳米粉碎的样品在鲜味和咸味方面均有明显提升,加入0.5%纳米粉碎双孢蘑菇后能够增加0.28%的盐浓度,同时其鲜味值提高了145%。结论:纳米粉碎技术能够提高食品的口感,在食品制造业中可以将纳米粉碎后的食用菌粉作为替代盐和风味增强剂的有效选择。

煤粉炉掺烧造纸污泥的污染物排放

燃煤锅炉掺烧是一种经济可行的污泥处置方式,由于造纸污泥有机质含量较高,采用造纸厂内已建成的燃煤供热锅炉掺烧造纸污泥,既可以减少造纸厂处理污泥的成本,又能利用污泥热能。掺烧造纸污泥可能会使锅炉产生的烟气和灰渣等固体废物中的污染物有所变化。利用造纸厂2×300 MW机组锅炉进行掺烧造纸污泥试验,检测产生污染物的变化情况。掺烧试验共掺烧造纸污泥755 t,燃煤与掺烧污泥的掺混比为22∶1,混合燃料相比燃煤热值稍下降。掺烧试验持续3 d,对烟气、干化污泥、炉渣和粉煤灰进行样品采集,共采集掺烧前3个烟气样品、3个干化污泥样品,各采集1个炉渣粉煤灰的空白样品,共采集掺烧后6个烟气样品、16个炉渣样品及50个粉煤灰样品。检测结果显示,烟气中常规性气体污染物如NOx增加1.5倍,SO2浓度略增加,检测出重金属Ni、Zn、Ba、Se、Cr、Mn、Sb、Pb、Cu,其中重金属Ba和Zn浓度较高,空白组烟气未检测出二噁英,掺烧组二噁英类平均质量浓度为1.20 pg/m^(3)(以TEQ计)。相比空白组,掺烧后炉渣中Pb浓度增加最明显,增长2.5倍;而Cu、Ni、Co、Al、Ti重金属浓度下降,空白组炉渣中二噁英质量分数为2.10 pg/g,掺烧组炉渣中二噁英质量分数为2.00 pg/g;相比空白组,粉煤灰中重金属元素Ba、Mn、As浓度增加明显,增长1.5~2.0倍,而Cu、Zn、Ni、Pb、Co、Ti、Al浓度下降,空白组粉煤灰中未检出二噁英,掺烧组粉煤灰中二噁英质量分数为2.00 pg/g。本次掺烧试验产生的污染物均未超过国家标准限值。

分离器转速对中速磨煤机风粉分配的影响

针对磨煤机内部流场复杂且不均匀的问题,通过建立完整的中速磨煤机模型,采用CFD软件求解磨煤机内部流动方程,利用DPM迭代获取颗粒流动参数,探究了不同动态分离器转速下中速磨煤机内部流动情况和出口风粉分配特性。研究结果表明:一次风在磨煤机出口4根出粉管处分配特性较好且与试验结果相吻合;煤粉粒径较小时,4根出粉管的煤粉质量流量偏差较小,且随动态分离器转速提高变化不明显;随着粒径的增加,煤粉颗粒运动轨迹呈现为贴壁运动,4根出粉管的煤粉质量流量偏差逐渐增大;同时对于大粒径煤粉颗粒,随着动态分离器转速提高,4根出粉管煤粉质量流量偏差逐渐降低。

干煤粉气化炉烧嘴偏置角度变化下的烧嘴罩性能优化研究

介绍了华能公司IGCC机组干煤粉气化工艺,针对干煤粉气化炉一段烧嘴水平偏置改造后,产渣量大幅提升,导致烧嘴罩发生漫渣、泄漏的问题,通过采取提高烧嘴罩探入深度、优化配煤方式控制气化炉产渣量、改造粉煤给料罐底锥稳定煤线波动等措施,进一步提升了烧嘴罩运行的稳定性,基本避免了烧嘴罩发生漫渣、泄漏现象。

超微粉碎联合超声波辅助提取鸭屎香单枞茶多糖工艺及活性研究

[目的]提高茶多糖的提取得率。[方法]采用超微粉碎技术对鸭屎香单枞茶进行前处理,利用超声波辅助结合正交试验对其多糖提取工艺进行优化,并考察鸭屎香单枞茶多糖的抗氧化和抑菌活性。[结果]最优提取条件为提取时间150 min、提取温度70℃、提取2次和料液比(g/mL)1∶30,在该提取条件下,鸭屎香单枞茶多糖的平均提取得率达到6.72%。体外抗氧化结果得出,鸭屎香单枞茶多糖对ABTS+和DPPH自由基均具有较强的清除作用,其清除率变化趋势与茶多糖浓度呈正相关;体外抑菌活性研究表明,茶多糖对4种菌株均具有抑制作用,且对大肠杆菌表现出较好的抑制效果,其最低抑菌浓度为3.125 mg/mL。[结论]茶多糖的提取工艺简单,得率高,抗氧化活性好,为鸭屎香单枞茶多糖的进一步研究及新产品开发提供理论依据和重要参考。

多元热流体发生器不同燃料燃烧工况优化

对稠油多元热流体发生器典型燃烧组分进行分析是注入能力评价、采收率预测、多次吞吐优化的关键。研究利用Fluent软件对多元热流体发生器进行三维仿真建模,模拟发生器不同工况下温度场和流场的分布。结果表明,不同的多元热流体发生器需要根据不同的燃料设计相应的燃料喷嘴,以促进燃料充分燃烧,提高热效率。当柴油作为燃料时,燃油喷嘴需要与空气喷嘴相匹配,以加强其雾化效果。天然气是多元热流体发生器的首选燃料,但在燃料供应条件有限的情况下,液态柴油和气相天然气可以相互替代,作为燃料在同一发生器中使用。当煤粉作为燃料时,即使有过量氧气,也难以充分燃烧。但是,在综合考虑成本或缺乏其他燃料时,可通过优化燃料喷嘴设计,最终实现煤粉在多元热流体发生器中的高效燃烧。

扬矿过程中多金属结核破碎粉化特性试验研究

对扬矿过程中多金属结核破碎粉化特性进行了试验研究。结果表明,扬矿过程中结核破碎程度明显,体积浓度6.5%时,粒径大于50 mm的多金属结核质量占比从75.58%降至23.78%;体积浓度15%时,粒径大于50 mm的多金属结核质量占比从51.51%降至10.08%。试验中结核存在粉化现象,体积浓度6.5%时,粒径小于0.1 mm的多金属结核粉末质量占比为1.79%,粉末中值粒径为10.07μm;体积浓度15%时,粒径小于0.1 mm的多金属结核粉末质量占比为1.99%,粉末中值粒径为9.47μm。基于试验数据估算,采矿1 000万吨多金属结核,粉末排放会造成上万吨Fe、Mn和上百吨Co、Ni、Cu金属损失,其形成的羽流扩散沉降后的最大再沉积厚度大于3 mm,会对环境造成显著影响。