基于微通道技术的制氢微反应器的研制

Development of Microreactors for Hydrogen

Production Based on Microchannel Technology

压缩或液氢作为主要燃料有许多缺点：沸点低，容易燃烧和爆炸，难以压缩和液化。氢气的储存和运输也占用了很大的空间。此外，将氢气注入密封容器也是危险和困难的。

解决这些问题的最佳解决方案是通过微反应器从含氢液体燃料中产生用于燃料电池的氢气。氢气可以通过由碳氢化合物（如甲醇、乙醇、甲烷、丙烷和汽油）重整直接或间接产生。微通道反应器具有结构紧凑、效率高、成本低的优点，不仅可以立即从碳氢化合物中生产氢气，而且可以与燃料电池集成设计，连续供应氢气。

如图1所示，制氢燃料处理器原理如下液态烃燃料（如甲醇或乙醇）经过重整后，产生的富氢气流主要由低含量的氢气和高含量的一氧化碳组成。这种气体混合物并不适合直接用于燃料电池，因为高含量的一氧化碳可能导致燃料电池阳极的失效。为了解决这个问题，需要在制氢过程中加入额外的转化单元，即燃料处理器，以降低一氧化碳的含量，使其用于燃料电池。

Compressed or liquid hydrogen as main fuel has many disadvantages: low boiling point, easily burned and exploded, difficultly compressed and liquefied. Hydrogen storage and transportation also take up large room. Moreover, it is dangerous and difficult to inject hydrogen into sealed vessel.

The best solution to deal with these problems is generating hydrogen for fuel cell from hydrogen bearing liquid fuels by microreactors. Hydrogen can be directly or indirectly produced by reforming from hydrocarbons, such as methanol, ethanol, methane, propane and gasoline. As the advantages of compact, high efficiency and low cost, microchannel reactors not only can instantly produce hydrogen from hydrocarbons, but also integral design with fuel cells and supply hydrogen continuously

As shown in Fig 1, the principle of a hydrogen fuel processor is as follows: after reforming liquid hydrocarbon fuels (such as methanol or ethanol), the hydrogen rich airflow generated is mainly composed of low hydrogen content and high carbon monoxide content. This gas mixture is not suitable for direct use in fuel cells, as high levels of carbon monoxide may lead to the failure of the fuel cell anode. To solve this problem, it is necessary to add an additional conversion unit, namely a fuel processor, in the hydrogen production process to reduce the content of carbon monoxide for use in fuel cells.

图1 制氢燃料处理器原理

Fig 1. Principle of Fuel processors for hydrogen production

微通道结构

Microchannel structure

1.单面微通道结构

微反应器由两个盖板和四个微通道板构成（图2.a）。利用化学蚀刻在厚度为0.34mm的不锈钢板（图2.b）上加工48个微通道，每个微通道的尺寸为30×0.5×0.17mm，微通道之间的肋条宽度为0.5mm（图2.c）。微反应器的总体积为22px3。Rh-K/Al2O3催化剂涂覆在微通道内。结果表明，微通道反应器比其他反应器具有优势，Rh-K/Al2O3催化剂能改善CO的优先氧化。

1.Single-sided microchannel structure

The microreactor was constructed by two cover plates and four microchannel plates (Fig2.a). Chemical etching was utilized to machine 48 microchannels on the stainless steel plate(Fig2.b) with 0.34mm in thickness, the dimension of each microchannel is 30×0.5×0.17mm，the width of rib between the microchannels is 0.5mm(Fig2.c).The whole volume of microreactor is 22px3 . Rh-K/Al2O3 catalyst was coated inside the microchannel. The result showed that the microchannel reactors were predominant than other reactors, Rh-K/Al2O3 catalyst could improve the CO preferential oxidation.

           （a）整体形状              （b）微通道板                          （c）微通道

                                  (a) Holistic shape          (b) Microchannel plates                  (c) Microchannel

图2:用于CO优先氧化的微通道反应器

Fig2. Microchannel reactor for CO preferential oxidation

2. 双侧微通道结构

如图3.a所示是一种用于甲烷部分氧化的新型微通道反应器。该微反应器由九块层压不锈钢板组成（图3.b），它们具有不同的微观结构，具有不同的功能，如燃烧、反应、预热、淬火和间隔。反应板的两侧包括37个直微通道，其尺寸为深度1500µm，宽度254µm，长度87.5px，通过放电加工（EDM）制成。微通道之间的肋条宽度为254µm。微通道的一侧涂有用于甲烷部分氧化的催化剂，另一侧用于热交换气体的流动（图3.c）。不锈钢板的尺寸为70mm×38mm×4mm。Rh催化剂可以防止内表面积聚物质。

2. Double-sided microchannel structure

As Fig3 showed that is a new type microchannel reactor for partial oxidation of methane. The microreactor was constituted of nine laminated stainless steel plates(Fig3.b), which have different microstructures serving different functions, such as combustion, reaction, preheat, quench and spacer. Both sides of the reaction plate comprise 37 straight microchannels whose dimension is 1500 µ m in depth, 254 µ m in width and 87.5px in length were fabricated by electrodischarge machining (EDM). The width of the ribs between the microchannels is 254µm. One side of the microchannels was coated with catalysts for partial oxidation of methane, and the other side was used for the flow of the heat exchange gas (Fig3.c). The dimension of the stainless steel plates is 70mm×38mm×4 mm. Rh catalysts could prevent the inner surface from accumulating matter.

        （a）部分氧化微反应器                                         （b）片层结构

                           (a) Partial oxidation microreactor                      (b) Sheet lamination structure

                             Reactants input           products output                                 Back face (exchange heat area)

                               反应物输入                  产物输出                                             背面（换热区域）

      正面  （反应区）                                                产品输出            热流体输入

                            Front face (reaction zone)                                      products output      Heat fluids input

(c)微通道板的前后和表面

(c)Front back and face of microchannel plates

图3 甲烷部分氧化原理

Fig 3. The principle of partial oxidation of methane

3.可穿透微通道结构

图4是一种可穿透的微通道换热器。通过冲压技术切割出方形材料，然后形成可穿透的微通道结构。通道的顶部和底部覆盖了许多粗糙的微观结构板。两个微结构板之间的角度为90度。交错式换热器采用扩散连接技术，由多个叠片组成。选用水作为换热器中的介质，在流速为6L/h、热水温度为78度、冷水温度为17度的条件下，换热器的功率可达220W。

3.Penetrable microchannel structure

Fig4 is a penetrable microchannel heat exchange.Researchers cut off quadrate material by punch technology, and then formed penetrable microchannel structure. Many crude microstructure plates were covered in the top and bottom of channel. The angle was 90 degree between two microstructure plates. The interleaving heat exchanger was composed of many lamination plates by diffusion connect technology. Researchers choose water as medium in the exchanger, in the condition of velocity of flow is 6L/h, the temperature of hot water is 78 degree and cold water is 17 degree, the power of exchanger can up to 220W.Nowadays more and more researchers are interested in microreactors with penetrable microchannel structure.

图4 具有可穿透微通道的交错换热器

Fig 4. The interleaving heat exchanger with penetrable microchannel

微通道流动通道的分布

The distribute of microchannel flow channels

图5是使用氨分解法开发的两种类型的微反应器，该反应器由99%的铝制成。第一个微反应器，如图5.a所示。通过放电加工（EDM）制造基板中的方形柱阵列，每个通道的空间形成微通道，每个柱的高度为300µm。另一个微型反应器由14个微通道构成（图5.b）。该反应器可以在600ºC下将99%的氨转化为相当于60W的氢气。

Figure 5 shows two types of microreactors developed using ammonia decomposition method, which was made from 99 percent aluminum. The first microreactor, as shown in Figue5.a.The square array of column in the base plate were fabricated by electrodischarge machining (EDM), the space of each channel formed the microchannel, each column was 300µm in height. The other microreactor was structured by 14 microchannels (Fig5.b).The reactor can convert 99% of ammonia at 600 ºC into the equivalent of 60W of hydrogen.

（a）柱状微通道                                                         （b）平行微通道

(a) Columniation microchannel                                       (b) Parallel microchannel

图5 氨分解法微型反应器

Fig 5. Microreactors using ammonia decomposition method

图6是一种微混合器，其中流体必须通过交叉微通道结构的倾斜表面。通道宽度为25µm或40µm。研究人员设计的这种微通道结构不仅可以增加界面面积，还可以提高分离壁的稳定性。

Fig.6 is a micromixer (Fig.6), in which fluid must pass the sloping surface of crossed microchannel structure. The width of channel was 25 µ m or 40 µ m.This kind of microchannel structure designed by researcher could not only add interface area, but also improve the stability of separate wall.

图6 微通道微混合器

Fig 6. microchannel micromixer

图7是一种多层结构的甲醇重整微反应器。它们将两个蒸发器、一个带催化燃烧器的重整装置和一个CO去除器集成在一起。整个系统可分为两个流动通道，燃烧过程如下：在一个流动通道中，甲醇首先在蒸发器2中预热2，然后在催化燃烧器中燃烧，为重整器提供热量。而在另一个流动通道内，甲醇和水的混合物在蒸发器1中被预热，然后反应在重整器中发生，富氢气流出来，最后，CO在CO去除器中被优先氧化。

Fig 7  the methanol reforming microreactor with multi-laminated structure (Fig7). They integrated two vaporizers, one reforming unit with catalytic combustor, and one CO remover together. The entire system could be divided into two flow channels, the combustions happen as follows: in one flow channel, methanol is first preheated in vaporizer2, and then it burns in catalytic combustor and provides the heat for the reformer. While inside the other flow channel, the mixture of methanol and water is being preheated in vaporizer1, then the reaction takes place in the reformer and the hydrogen-rich gas stream come out, and lastly, the CO is preferentially oxidized in the CO remover.

图7 多层微反应器中的流动通道

Fig 7. Flow channels in the multi- laminated microreactor

板材层压技术

Sheet lamination technology

板材层压技术是指先层压多种板材，然后通过扩散焊接得到的。

图8中将板材层压技术的概念应用于微通道反应器制氢。通过微加工技术形成图案的多个金属片首先堆叠起来，然后在高温和高压下通过扩散焊接进行焊接，以产生整体密封的固体金属部件，在该部件中形成反应物和产物所需的微通道流动通道。

Plate lamination technology refers to the process of first laminating multiple types of plates and then obtaining them through diffusion welding.

The concept of plate lamination technology is applied to hydrogen production in microchannel reactors in Figure 8.Pacific Multiple metal sheets, patterned by micro machining technology, are firstly piled up and then welded by diffusion welding under high temperature and pressure to yield a monolithic leak-tight solid metal component, in which forms the desired microchannel flow channels for reactants and products.

图8 薄板层压结构

Fig 8. Sheet laminated structure

图9.a是一种多层不锈钢板结构的甲醇重整微反应器。该微反应器由两块盖板构成，长70mm，宽40mm，高30mm，三个分配片和三个带微通道的不锈钢板（图9.b）。盖板上有四个孔作为流道的一部分，分配片上有两个孔和两个三角形通道，这两种结构都可以提高流道的均匀性。

Fig9.a is a methanol reforming microreactor with the multi-laminated structure of stainless plates (Fig9.a). The microreactor whose dimension is 70mm in length, 40mm in width and 30mm in height, was structured by two cover plate, three distribution sheets and three stainless plates with microchannel (Fig9.b).There were four holes as part of flow channel in the cover plate, two hole and two triangle channel in the distribution sheets, both of structure could improve the uniform performance of flow channel.

（a） 整体形状                               （b）多层结构

(a) Holistic shape                        (b) multi-laminated structure

图9 甲醇重整微通道反应器

Figure 9. Methanol reforming microchannel reactor

图10是一种基于片层技术的CO优先氧化微通道反应器。与换热器集成的微通道反应器可用于甲醇重整微反应器的CO优先氧化。蒸发器可以利用燃料电池的废气来加热燃料。蒸汽重整反应所需的能量主要来自燃料电池阳极排出的残余氢气的燃烧。来自燃料电池阳极的气体可以吸收来自优先氧化反应器的能量。这种优先氧化反应器的设计性能约为35%。

Fig10 is a kind of microchannel reactor for CO preferential oxidation based on the sheet lamination technology (Fig10).The microchannel reactor which integrates with heat exchanger can be used in CO preferential oxidation for methanol reforming microreactor.Vaporizer could use the exhaust gas from fuel cell to heat fuel. The energy required by steam reforming reaction mainly was from combustion of residual hydrogen production which expel from the anode of fuel cells. The gas from the anode of fuel cells could absorb the energy from the preferential oxidation reactor. This kind of preferential oxidation reactor the design performance was about 35 percent.

图10 用于CO优先氧化的微通道反应器

Fig 10. Microchannel reactor for CO preferential oxidation

图11是一种适用于大规模生产的高通量微混合器。混合器的设计基于板材中具有颗粒孔的多层结构。整个混合器由400张不锈钢板组成；每片的厚度在20µm到50µm之间。对该混合机的混合质量进行了测试，结果表明，该混合机比单T型和实验室釜型混合机的效率高。

Fig11 is a type of high flux micromixer which is suitable to manufacture on a large scale. The design of mixer based on the multi-laminated structure with particle hole in the sheet (Fig11). The whole mixer was composed of 400 stainless sheets; the thickness of each sheet is between 20µm and 50µm. After testing the mix quality of this mixer, the result shows that the efficiency is better than single T shape and laboratory kettle shape mixer.

图11 带颗粒孔的微通道混合器

Fig 11. Microchannel mixer with particle hole

如图12.a所示，反应器是基于不锈钢片层压技术制作的，包括燃料蒸发器、蒸汽重整器、热交换器和催化燃烧器。通过湿法化学蚀刻，在500µm厚的不锈钢片上形成直微通道。有两种类型的板具有对称图案（图12.b）。所有不锈钢板被分为几组，然后分别堆叠并通过钎焊进行焊接，形成不同的单元反应器，如燃料蒸发器、蒸汽重整器、热交换器和催化燃烧器（图12.c）。

As shown in Figure 12. a, the reactor is made based on stainless steel sheet lamination technology, including fuel vaporizer, steam reformer, heat exchanger and catalytic combustor, as shown in Fig12.a. Straight microchannels were patterned on a stainless steel sheet with 500µm in thickness by wet chemical etching. There were two types of sheets with symmetry pattern (Fig12.b). All stainless steel sheets were classified into several groups, and then are separately piled and welded by braze welding to form different unit reactors, such as fuel vaporizer, steam reformer, heat exchanger and catalytic combustor (Fig12.c).

（a）整体形状

(a) Holistic shape

（b） 微通道板                                      （c）堆叠单元

(b) Microchannel plates                                  (c) Stacking unit

图12 集成甲醇燃料处理器

Fig 12. Integrated methanol fuel processor

所有单元反应器由两个端板组装并拧紧，形成具有蒸汽重整器和催化燃烧器两个流道的燃料处理器。在不同的反应条件下对该燃料处理器的性能进行了优化。结果表明，燃料处理器的最佳尺寸为60mm×40mm×30mm。

All unit reactors were assembled and tightened by two end-plates to form the fuel processor with two flow passages of steam reformer and catalytic combustor. The performance of this fuel processor was optimized under different reaction conditions. Results showed that the optimal dimension of the fuel processor is 60mm×40mm×30mm.

本公司采用先进的微通道反应器技术，专注于甲醇重整制氢领域，高效生产压缩氢气与液氢。该技术不仅提升了制氢效率，还确保了生产过程的安全性。我们的产品为氢能产业提供了可靠的解决方案，推动了清洁能源的广泛应用。无论是压缩氢气还是液氢，我们均能满足多样化的市场需求，为氢能未来贡献力量。