Hydrogen - Important element for the realisation of climate neutrality

Hans-Wilhelm Schiffer and Stefan Ulreich

Hydrogen is becoming increasingly relevant on the path to climate neutrality. Two factors are decisive: hydrogen can be produced in a climate-neutral way. This is possible with renewable energies and nuclear energy, but also on the basis of fossil energies, as long as the CO₂ produced when using natural gas or coal is captured and used as a material or stored safely underground. Hydrogen can be used both energetically in the transport, building and industry sectors and as an industrial raw material. In a growing number of countries, hydrogen strategies have been drawn up by the respective governments. Depending on the availability of resources, the focus is on the opportunities associated with exporting hydrogen or the energy and climate policy goals pursued by importing it. Linking these different approaches makes it possible to create a global market for this product - comparable to the existing commodity markets for oil, natural gas and hard coal. The role granted to hydrogen as an important pillar of the desired energy transformation is also reflected in the currently presented projections of international institutions on the future of global energy supply. This applies in particular to scenarios that are geared towards meeting ambitious climate targets.

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Utilization of an online corrosion measurement system for membrane walls at the MHKW Berlin-Ruhleben

Andreas Müller, Adrian Marx, Bernd, Falk-Olaf Ewert and Jens Peitan

Waste incineration plants are strongly affected by fireside corrosion due to the high chlorine content of the incinerated waste. Since ash deposits forming on the boiler walls contain molten chlorides and sulfates it is possible to investigate such corrosion phenomena using electrochemical methods. This allows an immediate detection of corrosion-relevant operational changes such as air ratio and fuel changes. Therefore, an online corrosion sensor was developed by the Institute for Energy Systems and Technology of TU Darmstadt. In the course of a maintenance revision, six corrosion sensors were installed on the membrane walls of the waste-to-energy plant in Berlin-Ruhleben, whereby two sensors are placed in each of the three vertical passes. The results show clear differences in the corrosion behaviour of the different passes. The highest corrosion current occurs in the 1st pass, where short-term fluctuations of the evaporator wall and flue gas temperature cause strong fluctuations of the measured corrosion current. In the 2nd pass, the measured corrosion signal is characterized by the growth and detachment of the deposits and the spontaneous loosening of the deposits leads to a sudden increase in corrosion. A correlation analysis identifies the ratio between primary and secondary air as the most significant operational influence on the occurring corrosion. Higher secondary air leads to a lower flue gas temperature and lower amplitudes of temperature fluctuations in the 1st pass, reducing corrosion.

Flexibilisation - Analysis of the effects by evaluation of the VGB database KISSY

Jürgen Aydt, Mirko Bader, Jörg Bareiß, Ralf Mohrmann, Imo Pfaff, Stefan Prost, Ralf Uttich and Henk-C. Wels

The operating regime of fossil conventional thermal power plants has changed due to the increased use of renewable energies such as wind power and photovoltaics. The resulting increase in power generation capacity in the power grid also leads to increased downtimes and reduced operating times under full load for the conventional power plants. As a result, these power plants are subject to increased flexible operation.
Basically, the question must be asked whether the changed operating mode has also led to increased lifetime consumption of plant components. In terms of materials technology, the relationship between cyclic loading, such as that caused by start-ups and shutdowns, and increased service life consumption for thick-walled components is well known. It was unclear whether other unexpected damage had occurred in the plants in addition to the recorded service life consumption on selected components and whether this was clearly related to the change in operating mode. To clarify these issues, all relevant boiler, turbine, and generator components were considered.
For statistical data analysis, the data set of the VGB-KISSY database was used. The data originate from 132 hard coal and lignite-fired power plants as well as from 33 combined cycle and gas turbine power plants of VGB members over a period of 10 years (2010 to 2019). The data were anonymized before analysis and evaluated as an annual time series considering precise VGB definitions for planned and unplanned unavailability.

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