Roland Peters

Pre-reforming of natural gas in solid oxide fuel-cell systems

Internal steam reforming is an attractive option offering a significant cost reduction and higher system efficiencies of a solid oxide fuel cell (SOFC) power plant. Furthermore, faster load response may characterise systems with internal reforming. However, complete internal reforming can lead to several problems, which can be avoided with partial pre-reforming of natural gas. For SOFC systems the ratio between internal and pre-reforming has to be optimised on the basis of experimental performance data. A detailed study concerning the pre-reforming in a reformer of considerable size (10 kW) is carried out. The influence of operating temperature and mass flow variations on conversion of methane and ethane is analysed. During internal reforming of methane with substrate anodes, large temperature gradients were detected. Substrate samples with low catalytic activity show large response times with respect to parameter variations.

Compact methanol reformer test for fuel-cell powered light-duty vehicles

Abstract On-board production of hydrogen from methanol based on a steam reformer in connection with the use of low-temperature fuel-cells (PEMFC) is an attractive option as energy conversion unit for light-duty vehicles. A steam reforming process at higher pressures with an external burner offers advantages in comparison to a steam reformer with integrated partial oxidation in terms of total efficiency for electricity production. The main aim of a common project carried out by the Forschungszentrum Julich (FZJ), Haldor Topsoe A/S (HTAS) and Siemens AG is to design, to construct and to test a steam reformer reactor concept (HTAS) with external catalytic burner (FZJ) as heat source as well as catalysts for heterogeneously catalyzed hydrogen production (HTAS), concepts for gas treatment (HTAS, FZJ) and a low-temperature fuel cell (Siemens). Based on the experimental results obtained so far concerning methanol reformers, catalytic burners and gas conditioning units, our report describes the total system, a test unit and preliminary test results related to a hydrogen production capacity of 50 kW (LHV) and dynamic operating conditions. This hydrogen production system is aimed at reducing the specific weight ( th or 4 kg/kW el ) combined with high efficiency for net electricity generation from methanol (about 50%) and low specific emissions. The application of Pd-membranes as gas cleaning unit fulfill the requirements with high hydrogen permeability and low cost of the noble metal.

Methanol steam reforming in a fuel cell drive system

Abstract Within the framework of the Joule III project a c ompact m ethanol r eformer (CMR) with a specific weight of 2 kg/kW (lower heating value of H 2 ) was developed. This CMR contains a methanol and water vaporizer, a steam reformer, a heat carrier circuit and a catalytic burner unit. A laboratory fixed-bed reactor consisting of four tubes which could be filled with different amounts of catalyst was used to investigate the catalyst performance and the ageing behaviour. A hydrogen yield of 10 m N 3 /(h l Cat ) can be achieved at 280°C. In this case, the methanol conversion rate is 95% and the dry product gas contains 0.9% CO. A linear decrease of the catalyst activity was observed which can be described by a loss of active catalyst mass of 5.5 mg/h. The catalyst was operated for more than 1000 h without having exhibited activity losses that made a catalyst change necessary. Besides, the stationary behaviour of the reforming reactor, the dynamic behaviour was studied. The time needed for start-up procedures has to be improved for reformers of a next generation. Moreover, the hydrogen production during reformer load changes will be discussed. Simulations of the power train in driving cycles show the different states of a reformer during dynamic operation.

Investigation of a methanol reformer concept considering the particular impact of dynamics and long-term stability for use in a fuel-cell-powered passenger car

Abstract A methanol reformer concept including a reformer, a catalytic burner, a gas cleaning unit, a PEMFC and an electric motor for use in fuel-cell-powered passenger cars was investigated. Special emphasis was placed on the dynamics and the long-term stability of the reformer. Experiments on a laboratory scale were performed in a methanol steam reformer consisting of four different reactor tubes, which were separately balanced. Due to the endothermy of the steam reforming reaction of methanol, a sharp drop in the reaction temperature of about 50 K occurs at the beginning of the catalyst bed. This agrees well with the high catalytic activity at the entrance of the catalyst bed. Forty-five percent of the methanol was converted within the first 10 cm of the catalyst bed where 12.6 g of the CuO/ZnO catalyst was located. Furthermore, CO formation during methanol steam reforming strongly depends on methanol conversion. Long-term measurements for more than 700 h show that the active reaction zone moved through the catalyst bed. Calculations, on the basis of these experiments, revealed that 63 g of reforming catalyst was necessary for mobile PEMFC applications, in this case for 400 W el at a system efficiency of 42% and a theoretical specific hydrogen production of 5.2 m 3 n /(h kg Cat ). This amount of catalyst was assumed to maintain a hydrogen production of at least 80% of the original amount over an operating range of 3864 h. Cycled start-up and shut-down processes of the methanol steam reformer under nitrogen and hydrogen atmospheres did not harm the catalytic activity. The simulation of the breakdown of the heating system, in which a liquid water/methanol mixture was in close contact with the catalyst, did not reveal any deactivation of the catalytic activity.

Fuel cell drive system with hydrogen generation in test

In the future, drive systems for vehicles with polymer electrolyte membrane fuel cells (PEMFC) may be the environmentally more acceptable alternative to conventional drives with internal combustion engines. The energy carrier may not be gasoline or diesel, as in combustion engines today, but methanol, which is converted on-board into a hydrogen-rich synthesis gas in a reforming reaction with water. After removal of carbon monoxide in a gas-cleaning step, the conditioned synthesis gas is converted into electricity in a fuel cell using air as the oxidant. The electric energy thus generated serves to supply a vehicles electric drive system. Based on the process design for a test drive system, a test facility was prepared and assembled at Forschungszentrum Julich (FZJ). Final function tests with the PEMFC and the integrated compact methanol reformer (CMR) were carried out to determine the performance and the dynamic behaviour. With regard to the 50-kW(H2)-compact methanol reformer, a special design of catalytic burner was constructed. The burner units, with a total power output of 16 kW, were built and tested under different states of constant and alternating load. If selecting a specific catalyst loading of 40 g Pt/m2, the burner emissions are below the super ultra low emission vehicle (SULEV) standard. The stationary performance test of the CMR shows a specific hydrogen production of 6.7 mN3/(kgcat h) for a methanol conversion rate of 95% at 280°C. Measurements of the transient behaviour of the CMR clearly show a response time of about 20 s, reaching 99% of the hydrogen flow demand due to the limited performance of the test facility control system. Simulations have been carried out in order to develop a control strategy for hydrogen production by the CMR during the New European Driving Cycle (NEDC). Based on the NEDC, an optimized energy management for the total drive system was evaluated and the characteristic data for different peak load storage systems are described.

Operational experience with the fuel processing system for fuel cell drives

Abstract Electric motor vehicle drive systems with polymer electrolyte fuel cells (PEFCs) for the conversion of chemical into electrical energy offer great advantages over internal combustion engines with respect to the emission of hydrocarbons, carbon monoxide and nitrogen oxides. Since the storage systems available for hydrogen, the “fuel” of the fuel cell, are insufficient, it is meaningful to produce the hydrogen on board the vehicle from a liquid energy carrier, such as methanol. At the Research Center Julich such a drive system has been developed, which produces a hydrogen-rich gas from methanol and water, cleans this gas and converts it into electricity in a PEFC. This system and the operational experience on the basis of simulated and experimental results are presented here.

Scouting Study About the Use of Microreactors for Gas Supply in a PEM Fuel Cell System for Traction

An electric propulsion system with a methanol reformer, a catalytic burner, a gas cleaning unit and Proton-Exchange Membrane Fuel Cells (PEMFC) is described. Based on experimental data for methanol steam reforming criteria are developed for a microreactor system.

FUEL CELLS – SOLID OXIDE FUEL CELLS | Internal and External Reformation

Three basic concepts of solid oxide fuel cell (SOFC) systems operating on hydrocarbon fuels, with external, internal, and partial prereforming, respectively, are presented and discussed. Internal reforming of methane is advantageously used for additional cooling of the SOFC stack, thus increasing system efficiency. Basic thermodynamics, catalysis, and kinetics of the methane steam reforming process are presented. Examples of SOFC stacks operating on internal reforming of methane and simulated partial prereforming of mine gas and natural gas are discussed. The latter is used to illustrate the effect of internal methane reforming on heat management in SOFC stacks.

Highly integrated catalytic burner with laser-additive manufactured manifolds

This paper describes a highly integrated catalytic burner for auxiliary power units based on PEM-fuel cells. The generated heat is used by an integrated heat-exchanger system. The feasibility is verified by fluid-dynamic calculations. An innovative approach to develop complex reactors for demanding requirements defined by the application is presented.

Fuel cell — Battery hybrid systems for auxiliary power units

This work deals with the development of a fuel cell-battery hybrid system for auxiliary power supply for long-haul sleeper trucks. After the introduction of the special application, the theory of hybridization was briefly explained. A system model was developed to optimize hybrid system architectures for different load profiles. Finally, exemplary results were presented using the developed system model.