Abstracts - VGB PowerTech Journal 10/2017

From the sideline to the action.
Analytical instrumentation in power cycle chemistry.

Ruedi Germann

I first visited the then called “feedwater conference” of the VGB in the early nineties. Instrument manufacturers had their booths in the outer hall. Although we had our instruments on display we rarely ventured into the conference hall. Instruments for on-line measurements such as conductivity, pH and dissolved oxygen were used in many industries. As manufacturers we did not normally have any knowledge of the specific requirements of cycle chemistry. The power industry did not challenge that status.[more...]

Certification centres for management systems in the energy industry: Principles, normative specifications, DAkkS specifications, formalita using the example of ISO 27001

Stefan Loubichi

The IT security law forced the energy industry to implement system certifications for the first time in history. In contrast to most companies in the energy industry, which often only knew about product certifications, the energy industry now has to enter new territory. Certification companies receive their legitimation in Germany through DAkkS. The DAkkS is embedded in the context of European Union law. Through various multilateral agreements of the DAkkS, the certification decisions of DAkkS accredited certification companies are valid worldwide. National laws, EU regulations as well as normative guidelines are the foundations and the legitimacy for the work of DAkkS. The work of the certification companies is determined by the specifications of the DAkkS as well as by the requirements of the ISO/IEC standards. These regulations should in any case be known to a certification customer so that he knows what a certification company does or does not do. In addition, a certification customer must also know which evidence must be presented in the sense of a reference standard against the certification company. The concrete evidence in this essay is based on an ISO/IEC 27001 certification in conjunction with the IT Security Catalog of the Bundesnetzagentur. With all this knowledge, the cooperation with the certification company will not be a problem for system certification.

IT safety in power plants

Benjamin Kahler and Alexander Rieger

An almost full connected world leads the networks of critical infrastructures to a point of insecurity. The control technology in power plants faces new requirements for data exchange with the management networks of the company. Furthermore, regulatory bodies and administrative agencies define legal requirements for data exchange and data disclosure acts. System developers for industrial control systems and SCADA-software use more often standard technologies like TCP/IP-networks and Windows or Linux/Unix operating systems. This implies, that attackers only need minor special knowledge about serial or proprietary protocols and products. Therefore, attackers can break with less effort into the control system of power plants to create serious damage to the process. This report shows how the already in-use malware Win32/Industroyer operates while infecting power generation and distribution networks. Subsequent, we discuss potential solutions for defending the networks of critical infrastructures and give a view on the future development on IT-security issues for industrial control systems in critical infrastructures.

Investigation of the effects on stress corrosion cracking of the material T24 in high-temperature water

C. Ullrich, H.-G. Rademacher, W. Tillmann, R. Zielke and P. Körner

The effort to increase plant efficiency in new fossil power plants leads to increased steam temperature and pressures. In order to face these challenge, new materials were developed. The material T24 (7CrMoVTiB10-10) was for the first time used for membrane walls on a large scale. Commissioning of some plants, numerous cracks in the area of T24 welds were identified, which only appeared in the membrane walls used as evaporators. The cracks were initiated inside the tube and clearly showed characteristics of stress corrosion cracking (SCC). To identify the conditions resulting in SCC, experi-ments in high-temperature water, which simulate the conditions of the commissioning phase, are necessary. Tensile and bending tests, which are car-ried out slowly in controlled high-temperature water, are perfectly suited to identify the crack-initiating conditions. With these instrumented tests the sample behaviour is recorded in direct correlation with the particular load. This type of tests was carried varying the conditions of the exposure to finally study the root cause in more detail.

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High-temperature behaviour under variable loads – FVWHT Working Groups W9 and W10

Alfred Scholz, Torsten-Ulf Kern, Martin Reigl, Henning Almstedt and Matthias Oechsner

Practical methods for material characterization are needed for the design and service life assessment of the high-temperature components typically found in the power plant industry. Thus, for almost four decades now, material behaviour under variable loads has been studied in two areas of research focus within the scope of Working Groups W9 and W10 of the Forschungsvereinigung Warmfeste Stähle und Hochtemperaturwerkstoffe (FVWHT). In predominantly visco-elastic deformation, variable creep rupture behaviour forms the basis for the approach to these aims and the development of corresponding concepts, pursued by Working Group W9. If plastic cyclic deformation is also relevant, then creep-fatigue behaviour will be a definitive issue, which comprises the second point of research focus, dealt with by Working Group W10. In both cases, experiments with cyclic loading times of up to tens of thousands of hours’ have formed the foundation for the development of concepts in creep-fatigue behaviour to evaluate the service life of components under high thermal and mechanical loads. The concepts relating to variable creep rupture behaviour base on the modified life fraction rule and an experimentally supported factor concept of relative service life. The concepts in creep-fatigue behaviour arose based on the generalized damage accumulation hypothesis. Software application tools offer various possibilities in service life assessment under consideration of multi-stage load sequences. They are also applicable in cases of near-surface biaxial and anisothermal loading.

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A mechanical seal applied in an oxygenated treated (OT) feed water application travels 130-times around the earth

Gerard van Loenhout and Klaus Enders

Use of contemporary mechanical seals on high speed boiler feed water pumps have proven to be a reliable and cost effective sealing method. However, since the introduction of the oxygenated feed water chemistry (part of the Combined Water Treatment or Kombi-Betrieb) used in modern fossil power stations, keeping mechanical seal reliability on an acceptable level, became a challenge. In some cases even after a short number of operating hours, rotating seal faces made from very hard and durable silicon carbide material would show damages in the form of edge chipping and significant pitting. The opposing carbon graphite stationary seal face would reveal loss of carbon binder material, weakening the overall structural integrity of this crucial component leading to excessive seal leakages triggering unplanned pump shutdowns. A new phenomenon within the power generation industry referred to as ‘seal face generated electro-corrosion’. A sealing solution resisting this particular problem was first presented in the September 2012 edition of VGB PowerTech magazine. This article ex-plained the background of the problem and discussed potential root causes. It also presented a verifiable, combined academic and practical approach, which was applied in order to develop the new resilient sealing solution.

BioEnergy Carbon Capture – An approach to industrial carbon capture plants?

Jürgen H. Peterseim and Trina Dreher

Considering the recent Paris Agreement and its target to limit global warming to below 2°C it is crucial to decarbonise power and heat production as well as industrial energy demand, which contributed respectively 25% and 21% of global carbon emissions in 2010. Multiple options exist to realise this limit, ranging from energy efficiency measures to renewable energy technologies. Another option is carbon capture from utility scale fossil fuel power plants however, the development of carbon capture plants has been slow with limited references in operation to date. This can be attributed to not only the high investment costs of new technologies but also the scale and risk associated with large coal and gas fired power projects. In addition, there are also concerns about long term CO2 storage. To push carbon capture technologies along the technical and commercial learning curve it makes sense to apply the technology to small, industrial type power plants where CO2 utilization options may be available.

This paper presents a 20 MWe bioenergy carbon capture plant based on a post combustion process using amine solvents. The results show that such a facility can capture 670 t of CO2 per day or 6.7 million tonnes of CO2 over its 30 year lifetime for an additional plant investment of 20 million Euros. It also demonstrates that the use of the captured CO2 in industrial process is preferred to storage, which incurs significant cycle efficiency losses due to the compression required, e.g. 25.1% for 2 bar CO2 supply compared to 20.6% for 200 bar CO2 supply.

Consequences for a completely decarbonised energy supply for Germany

Friedrich Wagner

This paper examines the consequences of the transformation of Germany’s energy supply into electricity from wind power and photovoltaics. The consequences result from the two most important properties – low energy density and volatile production. The analysis is carried out by extrapolating real production data from the period 2010 to 2016, with the first step focusing on the technology change for pure electricity production, and the second on the presentation of the total final energy within the framework of so-called sector coupling. The main results are that renewable energies alone do not allow a strongly reduced final energy consumption to be achieved and that storage facilities have a low system relevance. The recommendation of this work is that Germany should develop and implement a further CO2-free supply.