Membrane reformer system

Yasuda, I., T. Tsuneki, and S. Shiraski, Development of Membrane Reformer System for Highly-Efficient Hydrogen Production from Natural Gas, World Conference on Wind Energy, Renewable Energy, Fuel Cell (WCWRF 2005), Hamamatsu, Japan, June 2005. 

Y. Shirasaki, T. Tsuneki, Y. Ota, I. Yasuda, S. Tachibana, H. Nakajima and K. Kobayashi, Development of membrane reformer system for highly efficient hydrogen production from natural gas, Int. J. Hydrogen Energy, 2009, 34, 4482-4487. 

With a similar approach to decrease the distance between the wall or catalyst layer and the membrane surface drastically, all-metallic membrane modules with micromachined plates directly attached to the membrane have been fabricated by KIT [129]. Pd-alloy foils with different thicknesses ranging from 61 pm to 3 pm have been leak-tight integrated in the modules by laser welding (see Figure 7.11). This is considered a very practical approach and represents the first step towards the anticipated compact multi-layered microchannel membrane reformer system. 

Yakabe, H. (2012) Operations of a 40Nm /h-class Membrane Reformer System at Tokyo Gas, Presentation at the International Joint Workshop on Palladium Membrane Technology - Rome, Italy, 12-14 November. 

Tokyo Gas Co., Ltd. (TGC) has developed a 40 Nm /h-class membrane reformer system with the world s highest efficiency (a value of 81.4%). The company has demonstrated the use of the hydrogen produced to refuel fuel cell vehicles (FCV), together with CO2 capture at the hydrogen station. An advanced hydrogen separation membrane module consisting of a palladium alloy membrane on a structured porous catalyst, which can be used to produce a membrane reformer that is more compact and less expensive, has also been developed. This chapter introduces the development of these two membrane reformer technologies. 

The new concept of simultaneous generation and separation of hydrogen means that membrane reformer system can be configured more compactly and can provide higher effidenqr than conventional steam reformers. The simultaneous process of hydrogen generation and separation frees the reactions from the limitation of chemical equilibrium and thus can reduce the reaction temperature from the conventional 700-800°C to 500-550°C. This means that expensive heat-resistant metals need not be used for structural components and long-term durability increases as a result of the lower operation temperature. 

In addition to the above-mentioned features, another advantage of the membrane reformer system is the high concentration of COj in the off-gas, which enables easy capture of COj by direct liquefaction. 

In parallel with the development of the membrane reformer system, a new concept membrane module, which has a palladium alloy membrane coated on the porous support tube with catalytic activity has been developed (Nishii, 2009). This membrane module is expected to provide a more compact reactor because the reactor does not require a separate catalyst. It is also expected that this module can be manufactured at low cost by applying the industrially-established mass production process used to make oxygen sensors for combustion control in vehicles with internal combustion engines. 

External view of 40 Nm h-class membrane reformer system. 

Figure 12.7 shows a system flow diagram of the 40 Nm /h-class membrane reformer system. The reactor is started up by combusting natural gas, and... 

An energy efficiency rating of 76% had already been achieved in the production of hydrogen with the first 40 Nm /h-class membrane reformer system the second system was designed to improve on this. For this purpose, the 40 NmVh-class membrane reformer was operated at a higher methane conversion rate and reduced natural gas input, steam-to-carbon ratio, auxiliary power consumption and heat losses. These improvements were expected to increase the efficiency up to 80% on the system design basis. 

Flow diagram of 40 NmVh-class membrane reformer system with CO2 capture system. 

To prove the technical viability of CO2 liquefaction and separation from the off-gas, a CO2 capture apparatus was designed and assembled. The appearance of the membrane reformer system equipped with CO2 capture apparatus is shown in Fig. 12.11. The experimental apparatus was composed of the water removal equipment, a gas compressor, a chiller, gas-liquid separator and liquefied COj tank. In the preliminary operation test in connection with the 40 Nm%-class membrane reformer, it was demonstrated that over 90% of CO2 in the off-gas can be captured. The total CO2 emission in hydrogen production was decreased by 50% with only 3% energy loss This experimental result suggests that the membrane reformer has the potential to reduce its CO2 emission to half with a minor energy loss by applying the CO2 capture system. 

Appearance of membrane reformer system equipped with CO2 capture apparatus. 

Figure 8.7 Picture of an integrated portable membrane reformer system with inset showing the integration schemes. Reproduced from [37]. With permission from Elsevier.

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