典型褐煤干燥技术比较

分析了国内外典型褐煤干燥技术的原理、关键参数、技术特点等,并从技术适应性、工艺条件、干燥效果、环境影响等方面进行综合评价比较。结果表明:美国K-Fuel工艺要求入炉粒度较其它技术大,适应性稍差;褐煤提质后均可作为锅炉燃料。干燥温度越高,褐煤干燥效果越好。德国泽玛克管式干燥成型技术、美国K-Fuel工艺为带压干燥,其他工艺为常压工艺。5种工艺可降低水分7.0%～25.0%,增加热值3.24～5.94kJ/g;澳大利亚BCB工艺、神华HPU-06工艺、德国泽玛克管式干燥成型技术产品为型煤,规格可调;其他工艺产品粒度变小。神州干燥-干选联合工艺回吸可能性大、自燃特性改善不明显,其余工艺深度脱水后可防止自燃,不易回吸。5种工艺污染物排放均较为简单,对环境影响较小。     

大尺度褐煤煤焦气化特性研究

煤层气化是将地下煤层进行有控制的燃烧来获取清洁燃气的技术。本文针对煤层气化过程的特点,利用自行设计的气化实验平台,研究气化剂流量、温度、原煤粒径对大尺度煤焦-水蒸气气化反应碳转化率和反应速率的影响。结果表明:在一定范围内,随水蒸气流量的增加,同一反应时间内煤焦碳转化率增加,气化反应速率也增大。原煤粒径对其气化反应性的影响显著,但无明显变化规律。随着气化温度的升高,煤焦固定碳达到相同碳转化率所需时间逐渐缩短。反应速率常数k随温度升高逐渐变大,反应级数随温度升高降低。实验结果为煤层气化现场实验工艺条件的优化提供了理论参考。     

高变质褐煤的干馏热解试验研究

分析了云南2种高变质褐煤的基本性质,确定干馏入炉褐煤粒度为6～25 mm。采用外热式干馏工艺,对试验褐煤进行热解改质加工研究。结果表明:煤样1和煤样2半焦、煤气、焦油和热解水的平均产率分别为49.42%,51.38%;13.20%,15.36%;8.56%,8.10%;24.18%,23.27%。随干馏终温的升高,干煤气产率增加较多,可燃成分CO和CH4降低,H2则反之,2个煤样的煤气热值基本保持在14～15 MJ/m3。干馏终温为800℃时,生产的半焦性能较好,且煤样1的热解性能指标明显优于煤样2。煤样1具有低硫、高发热量、高比电阻、气孔发达、反应活性大、灰分及含铝量低等特点,干馏产物可作为电炉冶炼的炭质还原剂;煤样2除灰分偏高外,其余质量指标均与煤样1相似,其半焦可用作水泥、制糖、烤烟等领域的烟煤替代燃料。     

不同参数对振动流化床分选细粒褐煤的影响

阐述了振动流化床的结构及作用机理。对6～3,3～1 mm褐煤分别进行了浮沉实验,说明当分选密度为1.7 kg/L时,褐煤属中等可选煤。在振动强度大于1的情况下,利用振动流化床模型机对6～3 mm和3～1 mm褐煤分别进行分选实验,研究流化气速、振动强度、床层高度、煤炭水分等对褐煤分选效果的影响。结果表明:当流化数N为0.3,振动强度为1.5时,褐煤分选效果最好。从上至下将床层按体积分数7∶3的比例分为精煤和矸石时,可能偏差E值分别为0.202(6～3 mm)和0.225(3～1 mm)。随着外水含量的增加,褐煤分选效果逐渐变差,当外水含量分别小于4.5%(6～3 mm)和2.0%(3～1 mm)时对褐煤分选几乎没有影响。当床层高度低于70 mm时,床层高度对褐煤分选影响甚微,当床层高度高于70 mm时,褐煤分选效果急剧变差,床层高度的选择应考虑分选效果与处理量2个因素。     

碱化甘蔗渣制备型煤黏结剂的研究

传统甘蔗渣利用率低,不仅浪费资源,还污染环境,因此研究甘蔗渣的再利用对于保护环境、创造经济增长点具有重要意义。试验以NaOH碱化甘蔗渣为型煤黏结剂,研究了NaOH质量分数、加热时间、加热温度对型煤抗压强度和跌落强度的影响。结果表明:利用甘蔗渣制备型煤黏结剂的最佳条件为:NaOH质量分数3%,加热时间2 h,加热温度85℃;此时制备的型煤抗压强度为440.5 N/个,跌落强度78.2%。因此,利用甘蔗渣制备型煤黏结剂是对甘蔗渣利用的新尝试,经NaOH碱化的甘蔗渣稳定性好,制得型煤的抗压强度和跌落强度均较高,改善和保护环境的同时,增加了经济效益。     

合成气制芳烃研究进展

根据工艺路线不同,对合成气一步法、合成气两段法、合成气联产芳烃3种工艺进行分析。发现合成气一步法采用复合催化剂,由F-T合成催化剂与芳构化催化剂复合而成,或甲醇合成催化剂与芳构化催化剂复合而成,将合成气直接转化为芳烃,芳烃选择性较低,为50%左右;合成气两段法是在2个反应器中,分别采用甲醇脱水催化剂,芳构化催化剂,一段将合成气转化为二甲醚,二段将二甲醚转化为芳烃,芳烃选择性可达80%。合成气联产芳烃是在生产各类油品的同时富产芳烃,是目前较易实现工业化的一条路线。最后对合成气制芳烃发展提出了一些建议。     

煤炭采制样常见问题分析及对策

煤炭采制样过程中常见问题主要有对采制样岗位的重视程度低,未按标准采制样,人工采制样工具及设备规格不统一,机械化采制样有混样现象等。针对上述问题,从采样和制样两方面提出了相应的对策。煤堆采样的子样点应按煤堆顶、腰、底分布,一般可按1∶3∶5的比例布点;火车顶部和汽车采样时,尽量采用机械化采样,按照"均匀布点,使每一部分煤均有机会被采出"的原则布置子样点;煤流采样时一般根据煤流量大小,以1次或分2～3次横截煤流断面采取一个子样,输送带采样应尽可能安装输送带机械化采样器。制备分析煤样时,对全水分超过10%以上的煤样,要进行初干燥;制备全水分煤样时首选水分损失最小的方法;制好的煤样应装入密闭玻璃瓶保存。加强采制化管理,规范采制样操作对于提高煤质分析准确性,保障优质原料煤供应具有重要意义。     

顾桥选煤厂商品煤质量动态控制研究

分析了顾桥选煤厂动力煤生产流程和末煤分流调节系统功能,提出对末煤分流调节系统进行组合优化的必要性。在充分考虑生产工艺和厂房空间的基础上,设计了可对末煤入选量进行预测的动力煤选煤厂商品煤质量动态控制系统,研制了可实现入选量自动控制的新型分流装置。运用动力煤选煤厂商品煤质量动态控制系统后,顾桥选煤厂产品灰分和要求灰分最大误差由0.67%降至0.37%,最小误差也由0.09%降为0,完全符合±0.5%的误差调整要求。控制系统的运用使末煤入选量实现了自动加减,入选量控制波动范围由原来的±80t减少至现在的±30t;减少了现场职工的劳动强度,末煤入选量控制更加合理,提高了系统的稳定性;商品煤质量可根据用户要求灵活调节,实现无极调灰。     

费托合成催化剂还原技术研究

费托合成工艺能否成功运行的关键因素之一为催化剂及其还原工艺的选择。本文简要介绍了费托合成催化的种类及其应用领域。详细介绍了催化剂还原过程,包括催化助剂的影响、还原过程的晶态结构演化、还原动力学以及还原工艺。最后重点介绍了还原气氛、还原空速、还原温度以及还原压力等还原参数对费托催化剂合成性能的影响。结果表明:催化剂的还原过程呈现明显的多相还原复杂行为,合理的助剂添加和还原参数选择有利于提高催化剂的还原性、活性和产品选择性。     

泉店选煤厂工艺系统的改造

针对泉店选煤厂精煤产率低,介耗高,浮选效果差、药耗高及循环水浓度高等问题,通过增加粗煤泥分选系统,将脱泥筛筛网孔径由0.75 mm改为1.00 mm,采用干扰床分选机(TBS)和德瑞克高频细筛分别替换高频筛和高频振动脱水筛;用浮选机替换浮选床,增加NFH系列电磁式药液定量注入泵自动添加浮选药剂;采用新型有机凝聚剂TLT8840配合有机絮凝剂TLT8623替换原普通絮凝剂,设计自动加药系统等措施对选煤厂进行了改造。改造后选煤厂粗精煤脱水效果明显改善,缓解了浮选系统分选压力,解决了煤泥水跑粗问题;精煤总产率提高了1.20%,尾煤灰分高达55.18%,浮选药耗由0.86 kg/t降至0.64 kg/t;尾煤浓缩药剂降低了10 g/t,循环水质量浓度降低了22 g/L,介耗降低了20%。同时选煤厂每年可增收3056.4万元,经济效益显著。     

粉末注射成型新技术

通过代替传统的生产工艺，粉末注射成型的应用范围得到大大的提高，近年来，已能生产重量最大为300g，壁厚较大的复杂金属制件。     

Development of the powder reaction moulding process

BACKGROUND: The powder reaction moulding process uses a reactive monomer as carrier and binder for the moulding of metal or ceramic powders. De‐binding is achieved using thermal depolymerisation which is followed by sintering to give the finished component. Binder can be recovered for re‐use. RESULTS: Moulding compounds, with various powder volume fractions, have been prepared using stainless steel, silicon nitride and alumina with n‐butyl cyanoacrylate as binder, and the stability of the compounds established. Rheological properties of the compounds have been measured using both pressure flow and drag flow methods. Compounds are strongly pseudoplastic. Comparison of experimental results with theoretical models, describing suspension flow behaviour shows that experimental maximum volume fractions are close to the theoretical volume fraction of 0.42 for silicon nitride, 0.68 for alumina and 0.7 for stainless steel. Differential scanning calorimetry and thermogravimetry have been used to simulate de‐binding and show a rapid loss of binder through depolymerisation. Post‐sintering porosity of the ceramic materials is high but this is thought to arise from the low pressure moulding techniques used. Porosity of the stainless steel mouldings is much lower. CONCLUSIONS: The results validate the powder reaction moulding idea and demonstrate applicability to three widely different powder materials. Copyright © 2008 Society of Chemical Industry     

Characterisation of micro gears produced by micro powder injection moulding

The paper describes the fabrication of micro gears of diameter and height 1 mm by micro powder injection moulding. 316L stainless steel powder of 2.4 µm (d₅₀) is mixed with a multi-component wax-based binder system. The feedstock is then injection-moulded into micro gears followed by debinding and sintering. The microstructure of the micro gear at its tooth and hub is studied by electron backscattered diffraction. The average grain size at the hub is ~ 5 µm. However, a high content of annealing twin and a significant grain growth is found at the tooth.     

国外汽车构件特殊成型技术

本文就汽车工业应用塑料特殊成型技术生产构件的状况作一概述。论述了各种特殊注射成型工艺生产的塑料构件在汽车设计制造方面的应用，指出其优点及发展趋势。     

褐煤资源洁净高效转化中的脱水技术

介绍了褐煤性质、世界及我国褐煤资源储量和综合利用,其中重点介绍了褐煤的提质干燥成型技术,最后对我国褐煤资源综合利用提出了建议和展望。     

Influence of powder morphology on properties of ceramic injection moulding feedstocks

The powder-binder-mixture is the most critical aspect in the injection moulding processing chain, because the feedstock properties determine the success of the following steps, i.e. excellent flowability in the injecting phase and high green strength during debinding. Therefore, nearly spherical particles which pass each other easily in the feedstock stream are advantageous. The applicable particle size is limited in order to reach high solids loadings which are connected with the specific powder surface. According to this, in this study a very unfavourable powder was introduced into a feedstock. The investigated β-alumina powder consists of plate-like primary particles and has a specific surface of 25 m²/g. During mould filling the particles orient in the feedstock stream which affects the debinding and sintering behaviour and is the source of defects. The influence of the plate-like shape on defect formation is demonstrated in comparison to spherical-shaped particles having the same specific surfaces.     

Micro powder injection moulding of alumina micro-channel part

A feedstock consisting of submicron alumina powder and a formulated binder, was developed to fabricate alumina micro-channel part by micro powder injection moulding. During small scale-mixing, the mixing torques of feedstocks with four different powder loadings were used to establish a suitable powder loading. The thermal and rheological properties of the selected feedstock were examined and used to establish conditions for large scale mixing, debinding and injection moulding. The micro-channel parts were pressureless sintered at different temperatures. The results showed that the moulded, debound and sintered micro-channel parts had good shape retention. The dimensions of the micro-channel part changed with the different processing steps. High densification of the micro-channel parts was achieved at sintering temperatures of 1350 °C and above. Above 1350 °C, the grain grew significantly with increasing the sintering temperatures and thus it led to a decrease in the microhardness.     

Particle design for dry powder inhalation via binderless powder coating by pressure swing granulation

Novel formulation for dry powder inhalation (DPI) particularly appropriate for very dilute drug concentration was developed based on the pressure swing granulation (PSG) technology. PSG was applied to the granulation of excipient lactose particles and to the coating/dusting of lactose granules with fine model drug particles. Size distribution and granule strength as well as the dispersibility of the drug particles for DPI were found to be successful for practical use. The drug particles dispersed into the respirable aerodynamic size range of 1-7 μm from the E-haler® was 53.9% for 1% coating/dusting (i.e. 1% drug in product granules) and 46.3% for 2%. E-haler® was capable of emitting 89.8% and 83.2% of drug particles charged for cases for 1% and 2% coatings, respectively.     

Effects of oxidation on the strength of debound SiC parts by powder injection moulding

In order to increase the production efficiency of powder injection moulding for SiC parts, thermal debinding was performed in air furnace without gas shield. Bending tests were performed to evaluate the strength of samples debound under different temperatures. The effects of oxidation on debinding process were also analyzed. Analysis indicates that air could accelerate the debinding rate of green parts without defects occurring. The bending strength of debound samples increases from 6.55 MPa to 11.58 MPa as the pre-sintering temperature increases from 550 °C to 850 °C. On the other hand, the bending strength of the samples pre-sintered at 1200 °C in argon atmosphere is only 11.52 MPa. It was found that, blanks have enough strength for transport after being pre-sintered in air atmosphere at 850 °C. The technology could reduce the requirement for heating equipment and enhance the efficiency of debinding for SiC parts.     

褐煤干燥技术综述

褐煤在我国储量巨大,但由于褐煤含水量大,一直阻碍着褐煤的高效利用。本文介绍了褐煤干燥技术的概况,同时,重点介绍了适用于高含水褐煤的干燥技术。褐煤干燥技术对于我国清洁煤的利用是一个重要的研究领域,合适的褐煤干燥在煤化工行业有很好的前景。