Reforming Equipment

Fig. 4. Structure of stream reformer equipped with palladium membranes...

Hydrocarbons such as natural gas or methane can be reformed internally in the SOFC, which means that these fuels can be fed to the cells directly. Other types of fuel cells require external reforming. The reforming equipment is size-dependent which reduces the modularity. 

Steam reformers equipped with the Pd membranes were developed and have been tested in Japan to produce pure hydrogen from city gas.3 Because of the working principle of the membrane reactor, the performance of this type of steam reformer directly depends on hydrogen permeability of the membranes. This has led us to develop membranes with higher hydrogen permeability. 

A membrane reformer equipped with palladium membrane modules for in situ hydrogen separation is a compact, simple and highly efficient hydrogen production system, and an improvement in these respects on the conventional steam methane reformer. In addition, CO2 in the off-gas of a membrane reformer can be easily separated and captured by direct liquefaction, owing to the high concentration of COj. 

Palladium or its alloys are the most practical membrane materials, due to their high hydrogen permeability and stability at high temperatures. The membrane reformer is composed of a steam reformer equipped with palladium-based alloy modules in its catalyst bed, and can perform steam reforming reaction and hydrogen separation processes concurrently with no help from shift converter and PSA, as shown in Fig. 12.1. 

Borup et al. [193] demonstrated that it is possible to heat up an autothermal methanol reformer equipped with a precious metal based catalyst from room temperature, when the O/C ratio of the feed exceeds 1.45. The S/C ratio was set to 1.0 for these investigations. The exothermic oxidation reactions clearly started even at ambient temperature and caused light-off of the reformer. 

Selection of the high pressure steam conditions is an economic optimisation based on energy savings and equipment costs. Heat recovery iato the high pressure system is usually available from the process ia the secondary reformer and ammonia converter effluents, and the flue gas ia the reformer convection section. Recovery is ia the form of latent, superheat, or high pressure boiler feedwater sensible heat. Low level heat recovery is limited by the operating conditions of the deaerator. 

Alloy 800 (32% nickel, 20% chromium and 46% iron) is used for furnace equipment such as muffles, trays and radiant tubes and in oil and petrochemical plants as furnace coils for the reforming and pyrolysis of... 

The catalytic reforming of CH4 by CO2 was carried out in a conventional fixed bed reactor system. Flow rates of reactants were controlled by mass flow controllers [Bronkhorst HI-TEC Co.]. The reactor, with an inner diameter of 0.007 m, was heated in an electric furnace. The reaction temperatoe was controlled by a PID temperature controller and was monitored by a separated thermocouple placed in the catalyst bed. The effluent gases were analyzed by an online GC [Hewlett Packard Co., HP-6890 Series II] equipped with a thermal conductivity detector (TCD) and carbosphere column (0.0032 m O.D. and 2.5 m length, 80/100 meshes), and identified by a GC/MS [Hewlett Packard Co., 5890/5971] equipped with an HP-1 capillary column (0.0002 m O.D. and 50 m length). 

Fig. 4 shows the evolution of temperature in the methanol steam reformer combined with a combustion plate equipped with a gas distributor. In this case hydrogen was used as a fuel for start-up at room temperature. As the reformer temperature reached near 300°C in about 5 min, methanol/water vapor was introduced to the reformer. It can be clearly seen that temperature within the reformer became relatively uniform after 25 min of operation. 

For the n-Cq reforming and n-C[2 isomerization reactions the catalysts were run in a fixed bed micro reactor equipped with on-line GC analysis. The catalyst, together with a quartz powder diluent, was added to a 6 inch reactor bed. A thermocouple was inserted into the center of the bed. The catalysts were calcined at 350-500°C immediately prior to use and reduced in H2 at 350-500°C for 1 hour. n-Heptane or dodecane (Fluka, puriss grade) were introduced via a liquid feed pump. The mns were made at 100-175 psi with a H2/n-heptane (or n-Ci2) feed ratio of 7 and a weight hourly space velocity of 6-11. 

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