Ni-P-PTFE复合镀层对颗粒污垢沉积特性影响研究

为探究Ni-P-PTFE复合镀层对颗粒污垢沉积特性的影响,利用化学镀工艺在碳钢表面制备Ni-P-PTFE复合镀层,以TiO₂纳米颗粒为研究对象,通过实验和理论分析的方式研究了不同表面能（PTFE浓度）下Ni-P-PTFE复合镀层在TiO₂悬浮液中的颗粒污垢沉积特性。结果表明：相比于碳钢试样,Ni-P-PTFE复合镀层对于TiO₂颗粒沉积具有较好的抑制效果。随着PTFE浓度的增加,复合镀层的表面能降低,污垢沉积量呈下降趋势,在表面能为26.8 mJ/m²（PTFE=12 ml/L）时,TiO₂颗粒污垢在Ni-P-PTFE复合镀层的沉积量最小。实验结果与应用扩展的DLVO理论计算出的最佳表面能结果相一致,也为针对不同类型颗粒在换热表面的沉积的抑垢提供了指导施镀的依据。     

Ni-P-PTFE复合镀层对颗粒污垢沉积特性影响研究

为探究Ni-P-PTFE复合镀层对颗粒污垢沉积特性的影响,利用化学镀工艺在碳钢表面制备Ni-P-PTFE复合镀层,以TiO₂纳米颗粒为研究对象,通过实验和理论分析的方式研究了不同表面能（PTFE浓度）下Ni-P-PTFE复合镀层在TiO₂悬浮液中的颗粒污垢沉积特性。结果表明：相比于碳钢试样,Ni-P-PTFE复合镀层对于TiO₂颗粒沉积具有较好的抑制效果。随着PTFE浓度的增加,复合镀层的表面能降低,污垢沉积量呈下降趋势,在表面能为26.8 mJ/m²（PTFE=12 ml/L）时,TiO₂颗粒污垢在Ni-P-PTFE复合镀层的沉积量最小。实验结果与应用扩展的DLVO理论计算出的最佳表面能结果相一致,也为针对不同类型颗粒在换热表面的沉积的抑垢提供了指导施镀的依据。     

The formation of calcium sulfoaluminate hydrate compounds: Part I

The formation of ettringite (3CaO · Al₂O₃ · 3CaSO₄ · 32H₂O) and monosulfate (3CaO · Al₂O₃ · CaSO₄ · 12H₂O) from tricalcium aluminate (3CaO · Al₂O₃) and gypsum (CaSO₄ · 2H₂O) in sodium hydroxide (NaOH) solutions was investigated by isothermal calorimetry and X-ray diffraction analyses. Tricalcium aluminate/gypsum mixtures with a molar aluminate-to-sulfate ratio of 1:3 were hydrated at constant temperatures from 40 to 80°C in deionized water and 200 and 500 mM of NaOH solutions. Ettringite was the only crystalline phase ultimately formed between 40 and 80°C, regardless of whether hydration was carried out in deionized water or sodium hydroxide solutions. The rates of ettringite formation were retarded in sodium hydroxide solutions at all temperatures when compared to hydration in deionized water. The apparent activation energy for the conversion of the tricalcium aluminate/gypsum mixture to ettringite was observed to depend on the concentration of sodium hydroxide.     

DECOMPOSITION BEHAVIOR AND MECHANISM OF CALCIUM SULFATE UNDER THE CONDITION OF O2/CO2 PULVERIZED COAL COMBUSTION

The decomposition behavior and mechanism of calcium sulfate in O₂/CO₂ pulverized coal combustion were studied in an entrained flow reactor. A reaction rate expression correlating the influence of various factors was proposed for CaS0₄ decomposition and it is able to predict CaS0₄ decomposition satisfactorily. Under the conditions investigated, the decomposition of CaS0₄ was found to be a regime of chemically controlled shrinking core reaction. A CO₂-rich atmosphere enhances CaSO₄ decomposition in absence of oxygen. CaSO₄ particles have catalytic effect on formation of CO from CO₂. A high SO₂ concentration inhibits CaSO₄ decomposition. The kinetics of CaSO₄decomposition has obvious dependence on experimental facilities and conditions, whereas the activation energy has much lower dependence. The kinetics derived in this work is more appropriate for investigating desulfurization in O₂/CO₂ pulverized coal combustion because an entrained flow reactor has a much closer condition to that in O₂/CO₂ pulverized coal combustion than a TGA.     

同时煅烧硫化反应中石灰石微观孔结构演变特性

采用自制恒温热重实验装置,测试了石灰石同时煅烧硫化反应的煅烧动力学特性和颗粒孔结构演变特性,探讨了孔结构演变机理。当煅烧环境中存在SO₂时,石灰石颗粒煅烧的同时发生硫化反应。煅烧环境中SO₂的存在降低了石灰石煅烧速率。与纯煅烧相比,同时煅烧硫化反应的比表面积和比孔容增长均较慢,比表面积和比孔容分布曲线均较低,且在反应后期直径2～8 nm内小孔的比表面积和比孔容随时间降低。提出了描述石灰石同时煅烧硫化反应过程中微观孔结构演变的模型：石灰石颗粒的煅烧由颗粒的表面向内进行,在煅烧前期（0～75 s）,少量CaSO₄在CaO表面生成,小部分孔隙被CaSO₄堵塞,CaSO₄对煅烧速率和孔结构的影响较小;在煅烧中期（75～225 s）,CaSO₄厚度和覆盖面积不断增加,堵塞孔体积增加,CO₂的扩散阻力增加,导致石灰石的煅烧速率下降;煅烧后期（225～300 s）,由于CaSO₄的不断积累,孔隙堵塞加剧,且堵塞主要发生在小孔上。对煅烧过程堵塞孔体积的计算表明,在煅烧前期和中期孔堵塞现象已经发生,在反应后期孔堵塞体积快速增加。     

用于选择性激光烧结成型的聚酰胺6/硫酸钙复合粉体的制备及性能研究

采用溶液沉淀法制备了聚酰胺6/硫酸钙（PA6/CaSO₄）复合粉体,通过扫描电子显微镜（SEM）、差示扫描量热仪（DSC）、激光粒度分布仪和Ｘ射线衍射仪（XRD）对复合粉体的微观形貌、热性能、粒度分布、晶体结构和流动性进行了表征。结果表明,随着CaSO₄的加入,PA6/CaSO₄复合粉体由松散的球形结构转变为密实的球形结构;CaSO₄的加入能够提高PA6/CaSO₄复合粉体的结晶度并拓宽其烧结温度窗口,在CaSO₄含量为5 %（质量分数,下同）时,结晶度和烧结温度窗口均达到最大值,分别为61.84 %和18.95 ℃;PA6/CaSO₄复合粉体的粒径随CaSO₄含量的增加呈现先减后增的趋势,休止角先减后增,堆积密度先增后减;当CaSO₄含量为3 %~5 %时,PA6/CaSO₄复合粉体的流动性能最佳,最适用于选择性激光烧结。     

磷石膏快速干法稳定化的矿物特征研究

新鲜磷石膏中的主要污染物种类为氟化物和磷化物,添加石灰能有效降低氟和磷的浸出水平,并且添加状态和比例对稳定化效果影响较大。通过添加不同石灰比例来稳定磷石膏的处理方式,研究其污染物的浸出水平,并采用扫描电镜及能谱对其进行表征。研究发现石灰与磷石膏拌混比例是污染物浸出水平的重要影响因素,在m（生石灰）∶m（新鲜磷石膏）为1∶50~1∶100时稳定化效果最好。由扫描电镜和能谱表征发现新鲜磷石膏为片层状结构堆叠,随着石灰添加量增多,表面微观结构也相应增多。在m（生石灰）∶m（新鲜磷石膏）为1∶100时,磷石膏的片层状结构表面会形成棒状结构,棒状间隙存在微球状颗粒。根据表征结果推测片层状结构除CaSO₄外,还含有一定量的Ca₃（PO₄）₂,棒状结构为Al₂O₃和AlPO₄,微球颗粒为CaF₂。在新鲜磷石膏表面形成的这类微观结构,使得含氟和磷的污染物稳定化从而降低了浸出水平。     

亚硫酸钙两步法制备高浓度亚硫酸氢钠溶液

利用湿法烟气脱硫中间产物亚硫酸钙（CaSO₃）和氯碱工业副产物芒硝和废硫酸制备高浓度亚硫酸氢钠（NaHSO₃）溶液,以简化亚硫酸氢钠溶液的后续处理工序并降低能耗。以亚硫酸氢钠溶液质量浓度为考察指标,采用两步法制备高浓度的亚硫酸氢钠。首先考察亚硫酸钙加入量、反应温度、反应时间、亚硫酸钙悬浮液质量分数等因素对第一步制备的低浓度亚硫酸氢钠溶液质量浓度的影响。其次考察第一步制备的低浓度亚硫酸氢钠溶液质量浓度对第二步制备的高浓度亚硫酸氢钠溶液质量浓度的影响。研究结果表明,实验中当亚硫酸钙加入量为0.068 mol、反应温度为13 ℃、反应时间为30 min、亚硫酸钙悬浮液质量分数为25%时,第一步制备的低浓度亚硫酸氢钠溶液质量浓度达到198.2 g/L;当第一步制备的低浓度亚硫酸氢钠溶液质量浓度为170 g/L时,第二步制备的高浓度亚硫酸氢钠溶液质量浓度达到264.2 g/L。采用两步法制备高浓度的亚硫酸氢钠溶液,节省了蒸发能源,具有显著的经济效益,为亚硫酸钙的利用提供了一条可行的路径。     

Aquifer composition and the tendency toward scale-deposit formation during reverse osmosis desalination — examples from saline ground water in New Mexico, USA

Desalination is expected to make a substantial contribution to water supply in the United States by 2020. Currently, reverse osmosis is one of the most cost effective and widely used desalination technologies. The tendency to form scale deposits during reverse osmosis is an important factor in determining the suitability of input waters for use in desalination. The tendency toward scale formation of samples of saline ground water from selected geologic units in New Mexico was assessed using simulated evaporation. All saline water samples showed a strong tendency to form CaCO₃ scale deposits. Saline ground water samples from the Yeso Formation and the San Andres Limestone showed relatively stronger tendencies to form CaSO₄·2H₂O scale deposits and relatively weaker tendencies to form SiO_2(a) scale deposits than saline ground water samples from the Rio Grande alluvium. Tendencies toward scale formation in saline ground water samples from the Dockum Group were highly variable. The tendencies toward scale formation of saline waters from the Yeso Formation, San Andres Limestone, and Rio Grande alluvium appear to correlate with the mineralogical composition of the geologic units, suggesting that scale-forming tendencies are governed by aquifer composition and water-rock interaction.     

熟石膏陈化过程的研究进展

探讨了熟石膏陈化过程中无水石膏（AⅢ-CaSO₄）与水蒸气的反应机理以及二水石膏（CaSO₄·2H₂O）的脱水机理。首先介绍了熟石膏陈化过程的基本原理,然后讲解了熟石膏陈化过程中水蒸气在AⅢ-CaSO₄上的物理吸附与化学吸附,其后描述了熟石膏陈化过程中CaSO₄·2H₂O晶体的脱水行为与脱水动力学,最后提到了CaSO₄·2H₂O、CaSO₄·0.5H₂O、AⅢ-CaSO₄的晶体结构。     

急冷处理对CFB锅炉底渣脱硫特性的影响

针对循环流化床（CFB）锅炉底渣综合利用率低的问题提出将高温CFB底渣在水中进行急冷的处理方法,搭建CFB锅炉底渣急冷实验台和脱硫实验台,对急冷前后的底渣进行f-CaO含量分析、微观结构特性和脱硫特性研究,通过理论分析提出了急冷有利于破坏颗粒CaSO₄外壳的理论,并通过实验进行了验证。利用扫描式电子显微镜/射线能谱仪（SEM/EDX）和热重分析仪对急冷前后的底渣进行分析,结果表明急冷后底渣颗粒表面钙含量明显升高,急冷后底渣的钙利用率提高了30%左右,底渣急冷前温度越高,底渣的脱硫效率越高,这说明急冷条件有利于提高CFB锅炉底渣的脱硫效率,为CFB锅炉底渣的再生利用提出了一种新的方法,对于实际的工程应用具有一定的指导意义。     

垃圾焚烧炉对流受热面烧结积灰生长特性

使用扫描电子显微镜、X射线荧光光谱仪、激光粒度分析仪等分析手段,对流化床垃圾焚烧炉对流受热面的松散性浮灰和烧结性积灰的微观结构和组成成分等进行研究。结果表明,省煤器浮灰中大部分颗粒保持着独立的形态,而对流管束浮灰存在烧结现象;绝大部分的浮灰粒径位于0～100μm;省煤器浮灰的灰熔点低于对流管束浮灰熔点80℃左右;对流管束浮灰和省煤器浮灰在成分组成上差别不大,浮灰中的主要元素均为Ca、Si、Al和S,但对流管束浮灰中Ca和S的含量高于省煤器浮灰。各层积灰中Ca和S的含量较高,主要物相为CaSO₄。对流管束积灰中Ca和S含量高于省煤器积灰;对流管束和省煤器积灰中Al和Si的含量远低于浮灰中的相应含量。从积灰内层到外层Ca和S的含量逐渐减少,而Al和Si的含量逐渐增加;积灰内层K、Na、Fe和Cl的含量高于其他层。     

阳极氧化二氧化钛纳米管涂层地热水腐蚀和沉积特性

拟采用金属二次阳极氧化等表面工程技术抑制地热水的腐蚀和结垢现象。在纯钛和钛合金(Ti-6Al-4V)板基底上采用二次阳极氧化法制备了二氧化钛微纳米管阵列涂层,探讨了制备工艺参数对涂层结构的影响,并进一步采用浸渍法对涂层进行了超疏水化处理。通过场发射环境扫描电镜表征了涂层的微观结构形貌。应用视频光学接触角测量仪检测了涂层表面的静态接触角,估算了表面自由能。对涂层的粗糙度也进行了测量。采用静态浸渍法评估了涂层的防垢性能。采用电化学线性极化曲线法研究了涂层在地热水中的耐腐蚀效果。结果表明,在钛及钛合金基底上,采用二次阳极氧化和浸渍工艺,可以制得具有规整二氧化钛微纳米管阵列结构和较低表面能的功能涂层;该涂层与基底相比,在地热水中的耐腐蚀性能得以提高;在碳酸钙饱和溶液中的污垢沉积速率降低约15%。同时,涂层与基底有较好的结合性能,疏水涂层经历多次胶带剥离和砂纸磨损实验后,依然保持着较高的疏水性。     

Thermochemical decomposition of phosphogypsum with Fe-P slag via a solid-state reaction

Phosphogypsum is a solid waste sourced from the wet-process phosphoric acid industry, which causes severe environmental damages. Its utilization was limited by its high decomposition temperature and high energy consumption. Herein, an Fe-P slag, which is a solid waste that mainly comprises iron phosphide(FeP) and diiron phosphide(Fe₂ P), can dramatically decrease the decomposition temperature of phosphogypsum. It was found that the Fe-P slag and CaSO₄ can react as shown in ...     

酸改性复合氧载体CaSO4-CaO的反应性能

将CaO添加到经不同酸改性后的CaSO₄氧载体中来制备CaSO₄-CaO复合氧载体。采用XRD、H₂-TPR、CO小型卧式管式炉开展恒温反应和循环实验,对氧载体进行表征和评价。主要研究了酸的种类对CO₂生成、气体硫化物的释放及复合氧载体循环反应性能的影响。结果表明：酸化的复合氧载体的氢气还原活性均明显优于未经改性过的CaSO₄,相比无酸化处理的CaSO₄氧载体,酸化后的CaSO₄-CaO复合氧载体,特别是HCl酸化,主要是提高了CaSO₄竞争还原副反应的选择性,导致主要气体硫化物SO₂释放显著增加,而COS释放略有降低。以CaCO₃煅烧得到的CaO与经HNO₃改性的CaSO₄进行机械混合制得的复合氧载体具有较好的反应活性,但是经过6次循环反应后,还原反应活性下降;循环反应中,气体硫化物主要来自于CaSO₄在还原阶段释放出的SO₂。     

Reaction characteristics investigation of CeO2-enhanced CaSO4 oxygen carrier with lignite

Calcium sulfate (CaSO₄) has been verified as a promising oxygen carrier (OC) in the chemical looping combustion (CLC) for its high oxygen capacity, abundant reserve and low cost, but its low reactivity and deleterious sulfur species emission from the side reactions of CaSO₄ should be well considered for its wide application in CLC. In order to promote the reactivity of CaSO₄ and increase its potential to inhibit the gaseous sulfur emission, a CeO₂-enhanced CaSO₄ OC mixed OC of core-shell structure was prepared using the combined template synthesis method. Reaction characteristics of the prepared CaSO₄-CeO₂ mixed OC with a typical lignite was first conducted and systematically investigated, and an improved reactivity of the prepared CaSO₄-CeO₂ mixed OC was demonstrated than its single component CaSO₄ or CeO₂ due to the fast transfer and exchange of oxygen from the CaSO₄ substrate to coal via the doped CeO₂. Furthermore, the solid products formed from the mixed CaSO₄-CeO₂ OC with the selected coal were collected and analyzed. Especially, evolution and redistribution of the sulfur species of different forms were focused. At the latter reaction stage of YN reaction with the CaSO₄-CeO₂ mixed OC, the SO₂ emitted from the side reactions of CaSO₄ was greatly diminished and the doped CeO₂ was proven effective to directionally fix the SO₂ released to turn into different solid sulfur compounds, which were determined as Ce₂O₂S, Ce₂S₃ and Ce₂(SO₄)₃·5H₂O and formed through the different pathways. In addition, good regeneration of the reduced CaSO₄-CeO₂ mixed OC could be reached in spite of the unavoidable interaction between the included minerals in coal and the reduced mixed OC. Overall, the combined template method-made CaSO₄-CeO₂ mixed OC reported herein was not only endowed with enhanced reactivity for coal conversion, but also owned the potential to directionally fix the gaseous sulfur emission, which is quite applicable as OC for simultaneous decarbonatization and desulfurization in the real CLC process.     

Effect of Carbon Precursors on the Microstructure and Bonding State of a Boron–Carbon Compound Grown by LPCVD

Methane (CH₄) and propylene (C₃H₆) were used to fabricate a boron–carbon coating by a low-pressure chemical vapor deposition (LPCVD) technique. The effects of carbon precursors on the phase, microstructure, and bonding state of the deposits have been investigated. X-ray diffraction results show that the 2θ value of the deposit from the C₃H₆ precursor shifts to 25.78° when the coating is deposited at 1223 K, and shifts to 26.1° when deposited at 1273 K, compared with the 2θ value of the pyrocarbon (PyC) peak deposited by LPCVD, which is 25.42°, and no boron–carbon (B–C) compound peak exists. However, the phases of coating deposited from CH₄ include B₂₅C, B₁₃C₂, elemental carbon, and boron. X-ray photoelectron spectroscopy (XPS) results show that the percent contents of boron atom in the coatings from the CH₄ precursor are 61.18% and 67.78% when deposited at 1223 and 1273 K, respectively, much higher than that from the C₃H₆ precursor, 10.85% and 15.30%, respectively. Scanning electron microscopy (SEM) results show that the coatings deposited from CH₄ have a coarse crystal-like morphology; however, the coatings deposited from the C₃H₆ precursor are smooth. The formation of PyC from C₃H₆ is more facile than that from CH₄, which leads to differences in the phase, atom content, and microstructure of coatings from CH₄ and C₃H₆ precursors.     

Ⅱ型无水磷石膏凝结硬化过程调控技术

为改善Ⅱ型无水磷石膏水化活性低、凝结硬化缓慢的问题,研制了一种复合助剂(β-半水石膏6%、改性钢渣3%、K₂SO₄ 2%、铝酸钙水泥0.5%)。研究表明,掺入复合助剂后Ⅱ型无水磷石膏初凝时间由744min (空白样)缩短至76min (改性样)。在此基础上添加25%的高炉矿渣微粉改善力学性能和耐水性,改性后的胶凝材料绝干抗压强度达到15.4MPa,软化系数达到0.83。研究了胶凝体系的水化率、液相离子浓度随时间的变化规律,结合X射线衍射(XRD)和扫描电子显微镜(SEM)对水化产物和水化硬化机理进行了分析。复合助剂加速了Ⅱ型无水磷石膏的溶解及二水石膏晶核的生成和长大,提高了Ⅱ型无水磷石膏的水化率,与矿渣协同作用促进生成3CaO·Al₂O₃·3CaSO₄·32H₂O、3CaO·Fe₂O₃·3CaSO₄·32H₂O等多种低溶度积复盐,改善了胶凝材料的凝结硬化性能和耐水性。     

L-赖氨酸改性聚天冬氨酸的阻垢缓蚀性能与生物降解性

L-赖氨酸经过氨解反应合成一种改性聚天冬氨酸衍生物（Lys-PASP）,用FTIR红外谱图证明了Lys-PASP分子中同时含有羧基和酰胺基等基团。扫描电子显微镜（SEM）的分析结果可知：Lys-PASP的加入使溶液中CaCO₃和CaSO₄的钙垢晶体的生长过程和形态发生变化,使得钙垢疏松、细小,抑制了它们长成致密结构的钙垢,从而达到很好的阻垢效果;Lys-PASP的加入使钙垢晶型变化,减缓了试片表面点蚀的发生;另外通过化学和物理的吸附作用在试片表面形成一层吸附膜而达到较好的缓蚀效果。探讨了Lys-PASP接枝聚合物对CaCO₃和CaSO₄垢的阻垢能力与Lys-PASP的投加量、Ca²⁺的浓度和测试体系的温度之间的密切联系。当Lys-PASP的投加量为10 mg·L^-1时,对CaCO₃的阻垢率为98.7%,对CaSO₄阻垢率接近于100%,而在温度达到80℃、Ca²⁺分别达到500 mg·L^-1和7000 mg·L^-1的浓度时,Lys-PASP也表现出很好的阻垢效果。另外,用失重法研究了当Lys-PASP和PASP均为150 mg·L^-1时,Lys-PASP的缓蚀率比PASP高13%;用摇床实验法证明了Lys-PASP属于易生物降解的物质。     

聚乙烯/纳米硫酸钙粉体复合软包装应用性能研究

采用含有51 %的纳米硫酸钙（CaSO₄）与聚乙烯（PE）为主要原料,通过熔融共挤制备了一种绿色低碳可降解的新型环保复合薄膜,并与同等碳酸钙（CaCO₃）含量的PE/CaCO₃复合薄膜比较,研究高填充无机纳米聚烯烃复合软包装材料的应用性能。采用拉力试验机、高温凝胶色谱仪、氙灯日晒老化试验箱、总有机碳（TOC）分析仪等设备对其物理性能、卫生性能、降解性能、碳含量进行测试分析。结果表明,PE/CaSO₄复合薄膜的拉伸强度、断裂伸长率优于同等含量的PE/CaCO₃复合薄膜,总迁移量（水、4 %乙酸、20 %乙醇、95 %乙醇、异辛烷）、高锰酸钾消耗量、重金属未超出国家标准的限量要求,在加速老化条件下,其拉伸性能和重均分子量均能达到光降解塑料的要求,且其碳含量远较其他塑料薄膜要低。