自热制氢反应器研究进展

介绍了同心圆式反应器、板式反应器、壁反应器、微通道反应器在自热重整反应制氢中的特点。同心圆式反应器的传热是控制步骤,为强化传热而开发了空间形状不同和流体经过反应器不同腔体的先后顺序不同的反应器;板式反应器易于组装、拆卸和放大,而且热效率也比较高,是目前十分活跃的研究领域,重点在于操作参数和设计的优化及其高效壁载制氢催化剂的研制;壁反应器的反应表面和换热表面不分离,具有较高的热量耦合效果;微通道反应器具有优越的传热性能,但对加工和流体的性质有比较苛刻的要求。另外,不同燃料制氢机理的研究及其过程参数的稳态、瞬态模拟,为反应器的设计提供了理论依据。而制氢过程并行单元的研究为系统的集成奠定了基础。最后,指出开发板式壁反应器以及开展其在CO变换、净化方面的研究有较好的发展前景。     

富甲烷气自热转化催化剂及工艺条件研究

在固定床反应器中,对适合富甲烷气自热转化要求的Ni/α-Al2O3催化剂进行了一系列的工艺条件试验,考察了温度、压力、空速、水碳比和氧碳比对甲烷转化率、氢收率和CO选择性的影响,并进行了120h的寿命试验。结果显示,在甲烷空速GHSV=2000h-1,nH2O/nCH4=1.0,nO2/nCH4=0.6,P=0.5MPa,T=1073K的条件下,甲烷转化率、氢收率和CO选择性分别一直保持在96.7%、70.8%和62.4%左右,以上结果表明该催化剂具有很好的稳定性和较高的活性。     

微反应器内自热结晶法制备磷酸二氢铵

为制备高纯固体磷酸二氢铵(MAP)并降低过程能耗,本工作提出一种基于微反应器的新工艺——自热结晶法。通过对该过程中放热、汽化、通道内结晶等现象的研究,更清楚地认识了微反应器内自热结晶法制备MAP的过程规律,为微反应器的设计及最佳工艺的选择提供了基础参数与理论支持。在酸碱物质的量比为1:1,MAP预设质量浓度为33.2%~55.0%时,获得了约40%的结晶收率,且所得样品晶粒小、纯度较高。实验证明,该方法在有效降低能耗的同时保证了较高的产率,具有良好的工业应用价值。     

低品位钼精矿热压碱浸—浮选工艺回收钼试验

针对非标钼精矿,利用热压碱浸过程中硫剧烈氧化释放热量进行自热反应,在碱用量为钼精矿质量的1.2%、液固比7、搅拌强度750r/min、充氧气、总压1.6MPa、温度160℃条件下浸出2h,钼浸出率为96.94%,氧化渣含钼可降到5%左右。自热氧化渣经一次粗选一次扫选两次精选后,可获得产率15.30%、钼品位36.30%、回收率89.18%的钼精矿,浮选尾矿钼品位可降到0.40%。氧化渣浮选精矿按50%比例返回自热浸出,钼浸出率可达96.17%。自热浸出—浮选联合工艺可将钼精矿中钼的回收率提高到99.48%以上。     

气态烃自热转化炉冷态实验研究与数值模拟

采用恒温式热线风速仪测自热转化炉内速度分布,用Realizable κ-ε湍流模型对流场进行模拟,其模拟结果和实验结果比较吻合.轴距小于21d0(喷嘴直径)时,轴线速度的衰减规律不受催化剂床层高度和气速的影响.转化炉内回流量随着轴距的增加,先增大后减小;随着催化剂床层高度的增高,回流比分布曲线变窄,回流量最大值为进口流量的6～7倍;轴距小于20d0,催化剂床层高度对回流比大小的影响不大.在实验条件范围内,改变气速,回流比的大小不变.     

Simulation of autothermal reforming in a staged‐separation membrane reactor for pure hydrogen production

Steam methane reforming with oxygen input is simulated in staged‐separation membrane reactors. The configuration retains the advantage of regular membrane reactors for achieving super‐equilibrium conversion, but reaction and membrane separation are carried out in two separate units. Equilibrium is assumed in the models given the excess of catalyst. The optimal pure hydrogen yield is obtained with 55% of the total membrane area allocated to the first of two modules. The performance of the process with pure oxygen input is only marginally better than with air. Oxygen must be added in split mode to reach autothermal operation for both reformer modules, and the oxygen input to each module depends on the process conditions. The effects of temperature, steam‐to‐carbon ratio and pressure of the reformer and the area of the membrane modules are investigated for various conditions. Compared with a traditional reformer with an ex situ membrane purifier downstream, the staged reactor is capable of much better pure hydrogen yield for the same autothermal reforming operating conditions.     

镍基非对称中空纤维膜用于乙醇自热重整制氢

采用纺丝-烧结技术制备了具有内表面致密皮层的外支撑式金属镍非对称中空纤维膜,并用于乙醇自热重整（EATR）制氢,研究了温度、进料流速、吹扫气流速、水醇比（S/C）以及氧醇比（O₂/C）等操作条件对膜制氢性能的影响。结果表明,金属镍非对称中空纤维膜既具有优异的EATR催化活性,又有良好的透氢性能。在500～1000℃、S/C=4、O₂/C=0.8的条件下乙醇可完全转化,H₂产率和H₂渗透通量可分别达到81.59%和13.99 mmol/（m²·s）,增加进料中氧气含量可显著抑制膜表面积炭,但同时也会降低氢气产率和一氧化碳选择性。     

用于PEMFC的丙烷自热重整制氢操作条件优化研究

Autothermal reforming （ATR） is one of the leading methods for hydrogen production from hydrocarbons. Liquefied petroleum gas, with propane as the main component, is a promising fuel for on-board hydrogen producing systems in fuel cell vehicles and for domestic fuel cell power generation devices. In this article, propane ATR process is studied and operation conditions are optimized with PRO/Ⅱ from SIMSCI for proton exchange membrane fuel cell application. In the ATR system including water gas shift and preferential oxidation, heat in the hot streams and cold streams is controlled to be in balance. Different operation conditions are studied and drawn in contour plots. The region for ATR reforming with the highest efficiency can thus be identified. One operation point was chosen with the following process parameters： feed temperature for the ATR reactor is 425℃, steam to carbon ratio S/C is 2.08, air stoichiometry is 0.256. Thermal efficiency for the integrated system is calculated to be as high as 84.0 % with 38.27 % H2 and 3.2μl·L^-1 CO in the product gas.     

Study on hydrogen-rich syngas production by dry autothermal reforming from biomass derived gas

In this study, the H₂-rich syngas (H₂ + CO) production from biomass derived gas (BDG) by dry autothermal reforming (DATR) is investigated. Methane and carbon dioxide is the major composition of biomass derived gas. DATR reaction combined benefits of partial oxidation (POX) and dry reforming (DR) reaction was carried out in this study. The reforming parameters on the conversion of methane and syngas selectivity were explored. The reforming parameters included the fuel feeding rate, CO₂/CH₄ and O₂/CH₄ molar ratios. The experimental results demonstrated that it not only supplied the energy required for self-sustained reaction, but also avoided the coke formation by dry autothermal reforming. It has a wide operation region to maintain the moderate production of the syngas. During the reforming process, the reformate gas temperature was between 650 and 900 °C, and energy loss percentage in reforming process was between 15 and 30%. Further, high CO₂ concentration in the reactant had a considerable influence on the heat release of oxidation, and thereby decreased the reformate gas temperature. It caused the reduction of synthesis gas concentration and assisting/impeding combustion composition (A/I) ratio. However, it was favorable to CO selectivity because of the reverse water-gas shifting reaction. The H₂/CO molar ratio between 1 and 2 was achieved by varying CO₂/CH₄ molar ratio. However, the syngas concentrations were affected by CO₂/CH₄ and O₂/CH₄ molar ratio.     

Transformation of CH4 and liquid fuels into syngas on monolithic catalysts

Active components comprised of fluorite-like Ln_x(Ce_0.5Zr_0.5)_1−xO_2−y (Ln = La, Pr, Sm) and perovskite-like La_0.8Pr_0.2Mn_0.2Cr_0.8O₃ mixed oxides and their composites with yttria-doped zirconia (YSZ) promoted by precious metals (Pt, Ru) and/or Ni were supported on several types of heat-conducting substrates (compressed Ni-Al foam, Fecralloy foil or gauze protected by corundum layer, Cr-Al-O microchannel cermets, titanium platelets protected by oxidic layer) as well as on honeycomb corundum monolithic substrate. These structured catalysts were tested in pilot-scale reactors in the reactions of steam reforming of methane, selective oxidation of decane and gasoline and steam/autothermal reforming of biofuels (ethanol, acetone, anisole, sunflower oil). Applied procedures of supporting nanocomposite active components on monolithic/structured substrates did not deteriorate their coking stability in real feeds with a small excess of oxidants, which was reflected in good middle-term (up to 200 h) performance stability promising for further up-scaling and long-term tests. Equilibrium yield of syngas at short contact times was achieved by partial oxidation of decane and gasoline without addition of steam usually required to prevent coking. For the first time possibility of successive transformation of biofuels (ethanol, acetone, anisole, sunflower oil) into syngas at short contact times on monolithic catalysts was demonstrated. This was provided by a proper combination of active component, thermal conducting monolithic substrates and unique evaporation/mixing unit used in this research.