Thermal power stations could become more efficient and economic
New reformate gas engine technology increases electrical efficiency by at least 10%
Small combined heat and power (CHP) plants in the power range of 50kW electric could be driven more economically in the future. This is possible due to the reformer technology, which produces energetically higher quality fuel gas from natural gas and steam, in parallel to the combustion engine’s operation. The created fuel gas (reformate) consists of hydrogen, methane, carbon dioxide and carbon monoxide and is fed directly into the engine. By that, less fuel is needed and the system’s electrical overall efficiency increases significantly.
The highlight of the reformate gas engine is, that no additional external power is necessary, because the required heat for the reforming process is taken from the hot engine exhaust. The principle origins from the steam reforming of diesel fuel and was transferred to the reformate gas engine.
The ECC Automotive GmbH and the OWI Oel-Waerme-Institut GmbH have shown by the end of their common research project that the linked system using the example of an innovative gas engine and a steam reformer is working. On the engine test bench, the thermal exhaust gas energy has been used directly for the reforming and evaporation. Within tests with an engine optimized for high exhaust gas temperatures, more than 10 % of the energy contained in the fuel could have been recuperated by the reforming. Due to the increase of electricity generation the profitability of CHP plants could rise if the power is fed into the grid. At the same time savings in fossil resources or in CO2-emissions are expected compared to conventional systems. Furthermore, an in the reformer integrated exhaust gas treatment can clearly reduce environmentally unfriendly emissions of hydrocarbons (formaldehyde, methane), as well as carbon monoxide.
The overall system consists of a natural gas combustion engine for electricity production with an output of 20 to 40 kW electric, a steam reformer with a catalytically coated plate heat exchanger and the needed auxiliary units. At OWI the reformer was already successfully taken into operation for the reforming of diesel fuel into hydrogen for the use in fuel cells. To achieve maximum efficiency increase in coupled operation, the combustion engine (ECC) and reformer (OWI) were coordinated. The operation under conditions in the high temperature range above 700 °C required new developments of components. For the operation of the engine with the higher energetic “reformate” and to use the reformate gas production with high hydrogenous fuel gases safely, the development of a specific suction pipe was necessary. Moreover, the engine was optimized with regard to the heat loss, so that an as high as possible exhaust gas temperature was available for the reforming. The long-term goal is to transfer this technology onto mobile fields of application as well as alternative fuels.
The project was funded by the German state of North Rhine Westphalia and the European Union (EU) within the “Goal 2-Programme 2007-2013 (EFRE)”.
Weitere Informationen:
http://www.owi-aachen.de
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