天然气现场制氢新工艺 的研究 学生 汪丛伟 导师 王树东 研究员 2018年11月15日

内容纲要 天然气现场制氢的意义及优势 天然气现场制氢的新工艺 总结与展望

研究背景 规模集中制氢 车载制氢 分散站制氢 设备投资大 氢气储运、分配困难 启动时间(10min) 启动能量(7MJ/50kw） FreedomCAR technical criteria in time to support the 2015 commercialization Current on-board fuel processing technology does not meet key 2005 performance targets, including start-up time and start-up energy. •无法满足各种燃料电池对分散氢能和现场制氢的需求。因此，必须发展新型分散制氢和现场制氢技术 军事电源应急电源 No clear path has been demonstrated to indicate that the ultimate performance targets are achievable by 2015. Even if successful, on-board fuel processing would not result in performance significantly better than that available from hybrid gasoline engine technology Lack of sufficient industry interest in pursuing the technology Acceleration of hydrogen technology through the Hydrogen Fuel Initiative 分散站制氢 ON-BOARD FUEL PROCESSING GO/NO-GO DECISION DOE DECISION TEAM COMMITTEE REPORT , August 2004

天然气现场制氢优势 原燃料比较充足（天然气水合物） 天然气清洁,能量密度大 供给方便(完善的输运管道) 制氢成本低，是目前最廉价的制氢方式之一 （如CH4）由于含氢量大、普通家庭及办公楼通过城市煤气管道即可供给天然气； 在煤气管网不完善的地方可以通过油罐车运送液化天然气 Alexei Milkov在《地质》上发表了关于水合物储层可捕获的天然气储量大约为3，000到5，000万亿立方米，这比先前广泛被引用的数据减少了4-7倍。相比之下，2000年美国地质调查全球石油评价中报道，全球常规天然气储量（目前储量和技术可行的情况下未发现的储量）大约为440万亿立方米。     尽管报道中指出天然气水合物储量巨大，最小的预测储量也比常规天然气储量多得多。但是，目前没有人预测从全球水合物储层中到底可以获取多少天然气。

现有天然气水蒸汽重整工艺用于现场制氢是极其昂贵的， 开发现场制氢新工艺与新技术已成为当务之急 ！！！ 目前天然气水蒸汽规模制氢与现场制氢的成本比较 高成本 高成本 天然气水蒸汽转化 CO高温变换 CO低温变换 CO甲烷化 CO2脱除 H2分离 现有天然气水蒸汽重整工艺用于现场制氢是极其昂贵的， 开发现场制氢新工艺与新技术已成为当务之急 ！！！ 重点：1. 产氢,纯化一体化,技术集成,缩短工艺流程; 2.装置投资小,生产成本低; 天然气水蒸汽重整制氢（大规模） 天然气水蒸汽重整制氢 (小规模) 天然气水蒸汽转化现有制氢需要昂贵的耐高温反应器和加热炉，另外尚需要深冷分离或变压吸附等昂贵的分离设备。 1. 强吸热反应，反应温度和能耗高，燃料成本占生产成本的52－68％； 2. 反应速度慢，装置规模大，投资高。 在加氢站建立小型现场制氢装置可以省去液化，储存和分配成本。然而，当SMR的规模降低到加氢站所需要的规模时，制氢成本将增加3－4倍。也就是现有天然气水蒸汽重整制氢无法满足现场制氢的需求。 将合成气生产，变换和氢分离高度集成在一个反应-分离装置是降低制氢成本的出路！ 若天然气重整制氢小型化得以成功运用，则在小型制氢市场上具有非常大的竞争优势。 在加氢站建立小型现场制氢装置可以省去液化，储存和分配成本。廉价合成气制备新工艺;廉价小规模氢分离技术 US$3.66~5/kg H2 US$ 12 /kg H2

天然气现场制氢的技术路线 天然气水蒸汽重整 天然气自热重整 CH4+0.5O2=CO+2H2， △H298K=-36 kJ/mol CH4+H2O=CO+3H2， △H298K= 206kJ/mol CH4+2H2O=CO2+3H2， △H298K= 165kJ/mol CH4+2O2=CO2+2H2O，△H298K= -804 kJ/mol 天然气自热重整 CH4+0.5O2=CO+2H2， △H298K=-36 kJ/mol CH4+H2O=CO+3H2， △H298K=206kJ/mol CH4+2H2O=CO2+3H2， △H298K=165kJ/mol 产氢纯度高，分离相对易，但能效相对不高 能量效率高，但分离能耗相对较大

天然气现场制氢新工艺 集成换热式(反应耦合） 净化纯化式 循环利用热流：壁式反应器，两段式反应器，多层套筒式反应器 降低传热传质阻力：板式反应器，微通道反应器 净化纯化式 制备高纯度H2 ：膜反应器 降低CO排放：双层催化剂无CO反应器

壁式反应器 循环利用热流Ⅰ 反应器由陶瓷管组成，陶瓷管内表面沉积燃烧催化剂层，外表面沉积重整催化剂层 Department of Chemical Engineering, University of Patras, Patras GR-265 00, Greece 反应器由高导热、非渗透性陶瓷管组成，陶瓷管内表面沉积燃烧催化剂层，外表面沉积重整催化剂层，陶瓷管附着在另一个大的陶瓷管上。原料从里面的管子进入后被外层的出口气体预热，在反应区发生反应，放出的热量通过管壁传到外层，在那里发生吸热的重整反应，因此可控制燃烧区的温度，减少热点。试验结果显示:反应器可在很短的停留时间内操作，接近等温,甲烷的转化率和选择性都接近平衡。 反应器由陶瓷管组成，陶瓷管内表面沉积燃烧催化剂层，外表面沉积重整催化剂层 原料从里面的管子进入后被外层的出口气体预热，在反应区发生反应，放出的热量通过管壁传到外层，在那里发生吸热的重整反应。 Theophilos Ioannides, Xenophon E. Verykios, Development of a novel heat-integrated wall reactor for the partial oxidation of methane to synthesis gas, Catalysis Today 46 (1998) 71-81 University of Patras, Greece

Fraunhofer Institute ，Germany 循环利用热流Ⅱ 两段式重整反应器 甲烷和水作为冷料通入换热器中与燃烧尾气换热，被加热至450－600℃ 进入一次重整器中进行重整反应（热量来自燃烧尾气的对流换热） 进入二次重整，热量来自陶瓷燃烧器的直接热辐射 Vogel, B., G. Schaumberg, A. Schuler, 1998, .Hydrogen Generation Technologies for PEM Fuel Cells,. 1998 Fuel Cell Seminar Abstracts, November 16-19, 1998, Palm Springs, CA, pp. 364-367. Fraunhofer Institute for Solar Energy Systems ISE, Oltmannsstraße 5, Freiburg 79100, Germany 最后重整产品气分别进行高温和低温水汽变换反应 The outer wall of the second reforming section is directly heated by radiation of the ceramic type burner, while the hot flue gas heats the inner reactor convectively. the thermal efficiency of the gas processor (SR, HTS, and LTS) was over 70% at atmospheric pressure (HHV) 甲烷和水首先作为冷料通入换热器中，与燃烧尾气换热，被加热至450－600℃，接着进入一次重整器中进行重整反应（热量来自燃烧尾气的对流换热），然后进入二次重整，热量来自陶瓷燃烧器的直接热辐射。最后重整产品气进入两个分别装有商用高变催化剂和低变催化剂，进行水汽变换反应。 Fraunhofer Institute ，Germany

多层套筒式重整反应器 存在问题：传热阻力较大 系统较庞大 循环利用热流Ⅲ GE能源与环境研究公司2000年开发的用于为PEMFC提供氢源的天然气水蒸气重整制氢反应器 California 能源委员会提供催化剂（颗粒）及原型反应器制作材料 本项目的目的是研究催化剂和考察CO2吸收器材料使用寿命超过5000小时的性能。 Unmixed reforming is a cyclic process requiring at least two reactors for continuous hydrogen production. The reactor designed and used for testing of the selected catalyst consists of a packed catalyst bed in an axial flow reactor. The reforming and regeneration feeds flow downward along the axis of reactor. Reactants enter along the outer wall and flow downward and then back up the inside wall before entering the bed from above. After passing through the bed, the reformate gases flow up along the outer bed wall and then down, exiting from the bottom of the reactor. The multi-channel design accomplishes internal heat recuperation by preheating the reactants, and achieves a more uniform bed thermal profile. By reducing radial temperature gradients in the axial flow reactor, lower slip at the wall boundary can be achieved. 存在问题：传热阻力较大 系统较庞大 A novel steam reforming reactor for fuel cell distributed power generation, California Energy Commission, May 2000

板式反应器 存在问题：催化剂涂覆困难 降低传热传质阻力Ⅰ 催化剂层＆板的厚度很薄,大大提高了反应器的结构紧凑性,降低了传热与传质阻力 板式反应器的效率比传统水蒸汽重整器高一个数量级，而体积和催化剂重量低2个数量级 板式反应器的换热效率提高。壁面和气相截面温度分布更均匀 Department of Chemical Engineering, University College of London, UK 板的一侧涂有甲烷催化燃烧催化剂，另一侧涂甲烷水蒸汽重整催化剂，催化剂层的厚度为微米级，板的厚度为毫米级，从而把强放热的催化燃烧反应与强吸热的水蒸汽重整反应耦合起来，大大提高了反应器的结构紧凑性，降低了传热与传质阻力。 ，板的厚度在1-4mm以内对反应器的性能没有明显影响降低了传热与传质阻力。数值研究表明，在相同反应温度和入口组成情况下 影响因素: 流速,孔道高度,催化剂负载量及厚度 存在问题：催化剂涂覆困难 M. Zanir, A. Gavriilidis, Catalytic combustion assisted methane steam reforming in a catalytic plate reactor, Chemical Engineering Science 58 (2003) 3947 – 3960

微通道反应器 存在问题： 反应器加工成本高 通道阻力降大 降低传热传质阻力Ⅱ 微通道反应器 微通道可把传热传质速率提高1～2个数量级 由于过程强化降低了操作成本 均匀布氧，先部分氧化后完全燃烧为原料预热和重整供热 存在问题： 反应器加工成本高 通道阻力降大 Velocys, a spin-out company from Battelle Memorial Institute, is commercializing microchannel process technology for large-scale chemical processing. Pacific Northwest National Laboratory, Richland, WA 99352, USA a microchannel methane steam reforming reactor is presented with integrated catalytic partial oxidation of methane prior to catalytic combustion with low excess air (25%) to generate the required energy for endothermic methane steam reforming in adjacent channels. Heat transfer rates from the exothermic reactions exceed 18W/cm2 of interplanar heat transfer surface area and exceed 65W/cm3 of total reaction volume for a methane steam reforming contact time near 4 ms. The process intensity of the Velocys methane steam reformer well exceeds that of conventional steam reformers, which have a typical volumetric heat flux below 1W/cm3. The integration of multiple unit operations and improvements in process intensification result in significant capital and operating cost savings for commercial applications. Microchannel process technology advantages are based on the use of small diameter channels to improve both heat and mass transfer rates by one to two orders of magnitude. Critical channel dimensions typically range from 50 to 5000 m and flow regimes are usually laminar. Transport rates are inversely proportional to channel diameters. mid 1990s, challenge addressed in this paper surrounds the stable operation of combined reforming and combustion with low excess air in adjacent reaction microchannels. possible; in this work, combustion fuel is first partially oxidized to a synthesis gas mixture prior to complete combustion. The reactor further integrates preheat of reactant, fuel, and air into a single device by recuperating energy from the product and exhaust streams Picture of a Velocy’s manufacturing scale-up microchannel reactor (Pacific Northwest National Laboratory) A.Y. Tonkovicha, S. Perrya, W.A. Rogers, Microchannel process technology for compact methane steam reforming, Chemical Engineering Science 59 (2004) 4819 – 4824

存在问题：钯膜具有氢脆现象，如何增强稳定性？ 净化纯化式Ⅰ 集成化膜反应器 CH4 The hydrogen stream, or permeate, passes over a methanation catalyst to convert traces of carbon Oxides 该反应器以天然气或液化气为原料，最大产氢量约100多sml，可为最大可为8kW提供氢源。 由于采用膜纯化氢，所以启动很快。 优点：可以自供热；单位体积表面积大，弥补了填充床反应器换热性能差的缺点。 Another promising technology is the .membrane reactor., where the steam reforming, water gas shift and hydrogen purification steps all take place in a single reactor (Figure 7d). Methane and steam are fed into a catalyst-filled reactor under pressure. On one side of the reactor is a high selectivity palladium membrane that is selectively permeable to hydrogen. As the steam reforming reaction proceeds, the hydrogen is driven across the membrane by the pressure difference. Depending on the temperature, pressure and the reactor length, methane can be completely converted, and very pure hydrogen is produced. Very pure hydrogen is removed as the reaction proceeds. This allows lower temperature operation, and lower cost materials. A potential advantage of this system is simplification of the process design and capital cost reduction, because fewer process vessels will be needed. This concentric module included a supported palladium membrane tube located at the centre pos- ition and two stainless steel tubes separately assembled as double outer jackets. A copper-based catalyst was used for steam reforming reaction and was loaded adjacent to the outer surface of the membrane tube. At the outer surface of the ®rst jacket, a Pd/Al2O3 cat- alyst was used for oxidation of gases rejected from the membrane tube. The mixture of methanol and water was fed into the reforming catalyst bed in order to produce H2, CO and CO2. Under the driving e.ect of transmembrane pressure di.erence, the instantaneously produced H2 penetrated through the Pd-membrane tube and was directly removed as a high purity hydro- gen. The rejected gases, H2, CO, CO2 and/or trace amount of unreacted methanol, then entered the oxi- dation catalyst bed and were converted into CO2 and H2O as a result of total oxidation reaction with air. 存在问题：钯膜具有氢脆现象，如何增强稳定性？ Yu-Ming Lin, Min-Hon Rei, Process development for generating high purity hydrogen by using supported palladium membrane reactor as steam Reformer, International Journal of Hydrogen Energy 25 (2000) 211±219

CH4 ＋2H2O → CO2 ＋4H2 , ΔH298K=177 kJ/mol 净化纯化式Ⅱ 两层催化剂无CO水蒸气制氢反应器 Step 1:Reduction Pt-CeO2-ZrO2 Fe3O4-CeO2-ZrO2 CH4 CO+H2 H2O+CO2 H2O+H2 H2 Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstrasse 1, D-39106 Magdeburg, Germany 原理：通过氧化铁与甲烷、水的氧化还原反应制取纯氢 CH4＋Fe3O4 → CO2 ＋2H2O ＋ 3Fe (1) 4H2O ＋ 3Fe → 4H2 ＋Fe3O4 (2) (1)与(2)合并，则 CH4 ＋2H2O → CO2 ＋4H2 , ΔH298K=177 kJ/mol Step 1:Reduction CH4＋2CeO2 → Ce2O3 ＋CO+2H2 (1) 4CO ＋ 3 Fe3O4 → 4CO2 ＋3Fe (2) 4H2 ＋ 3 Fe3O4 → 4H2O ＋3Fe (3) Step 2:Re-oxidation H2O ＋ Ce2O3 → 2CeO2 ＋H2 (4) 4H2O ＋ 3Fe → 4H2 ＋Fe3O4 (5) (i) saving of investment costs for purification units by periodic operation of one single reactor; (ii) saving of investment and operational costs by using iron oxides as a cheap material; (iii) high quality of the produced hydrogen gas. 为进一步提高甲烷的氧化速率，采用两层活性组分不同的催化剂固定床反应器，采用的催化剂分别是Pt-CeO2-ZrO2和Fe3O4-CeO2-ZrO2。 制氢过程取决于氧化铁还原成铁这一慢过程，为提高产氢率必须再还原铁的过程中提高甲烷的氧化速率，为防止铁催化剂烧结还必须再较低温度下进行。综合考虑，铁的氧化还原过程中不超过800℃环境中进行。 H2O Pt-Ce2O3-ZrO2 Fe-Ce2O3-ZrO2 Step 2:Re-oxidation 存在问题：催化剂表面沉积碳，实际应用? Vladimir Galvita a, Kai Sundmacher, Hydrogen production from methane by steam reforming in a periodically operated two-layer catalytic reactor, Applied Catalysis A: General 289 (2005) 121–127 Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany

总结与展望 将重整制氢,供热,纯化一体化,实现过程强化、系统高度集成是降低制氢成本的出路 集成换热式(热量耦合） 净化纯化式（降低成本） 现场制氢新工艺要真正走向实际应用，还需切实解决自身的关键技术，扬长避短 反应过程的偶合（反应器） 高活性高稳定性催化剂 氢分离纯化技术（深冷分离、PSA、膜分离及变换＋PROX等） ,缩短工艺流程; 装置投资小,生产成本低

谢谢大家!

参考文献 1.ON-BOARD FUEL PROCESSING GO/NO-GO DECISION, DOE DECISION TEAM COMMITTEE REPORT , August 2004 2.Theophilos I, Xenophon E. Verykios, Development of a novel heat-integrated wall reactor for the partial oxidation of methane to synthesis gas, Catalysis Today 46 (1998) 71-81 3.M. Zanir, A. Gavriilidis, Catalytic combustion assisted methane steam reforming in a catalytic plate reactor, Chemical Engineering Science 58 (2003) 3947 – 3960 4.Vogel, B., G. Schaumberg, A. Schuler, and A. Henizel, 1998, .Hydrogen Generation Technologies for PEM Fuel Cells,. 1998 Fuel Cell Seminar Abstracts, November 16-19, 1998, Palm Springs, CA, pp. 364-367. 5. A.Y. Tonkovicha, S. Perrya,W.A. Rogersa, Microchannel process technology for compact methane steam reforming, Chemical Engineering Science 59 (2004) 4819 – 4824 6. Vladimir G, Kai S, Hydrogen production from methane by steam reforming in a periodically operated two-layer catalytic reactor, Applied Catalysis A: General 289 (2005) 121–127 7.A novel steam reforming reactor for fuel cell distributed power generation, California Energy Commission, May 2000

参考文献(续) 8. Yu M L, Min H R, Process development for generating high purity hydrogen by using supported palladium membrane reactor as steam Reformer, International Journal of Hydrogen Energy 25 (2000) 211-219 9. S Lin, Y Chen, C Lee, Dynamic modeling and control structure design of an experimental fuel processor, International Journal of Hydrogen Energy (in press) 10.Sheldon Lee,, Daniel V. A, Shabbir A, Hydrogen from natural gas: part I—autothermal reforming in an integrated fuel processor, International Journal of Hydrogen Energy 30 (2005) 829 – 842 11. A.Siddle, K.D. Pointon, R.W. Judd and S.L. Jones,FUEL PROCESSING FOR FUEL CELLS – A STATUS REVIEW AND ASSESSMENT OF PROSPECTS

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