Abstract - VGB PowerTech Journal 3/2019

Chemistry in power generation – challenges and opportunities

Christopher Weßelmann

Safe, environmentally friendly, failure-free and economical are the requirements for operation in power generation. To make a contribution to this is also an original objective and at the same time a claim of power plant chemistry. Power plant chemistry is one of the roots of the VGB. About 100 years ago, investigations to clarify corrosion phenomena – the interplay between medium and material – and cases of considerable steam generator corrosion led to the founding of the “Feed Water Committee”, the nucleus of today’s VGB PowerTech.[more...]

„Autonomous operation“ of the DI-plant Artificial Intelligence (AI) in DI-Production

Dieter Mauer

When planning a new DI-plant, the goal is more and more the deserted plant. At the same time, laboratory skills are reduced. This discrepancy can only be counteracted if the system itself is in a position to analyse itself, to recognise fault states itself, to specify the exact location and origin of the fault and, in the best-case scenario, to even provide the operator with suggested solutions and recommended actions. This is precisely the task of the new MionTec analysis system. It bases on methods of the Artificial Intelligence and can determine with very few measured data complex predictions of the system behaviour with regard to each individual stage of the DI-plant. It predicts conductivity and pH after each stage and shows them in a graphical form similar to the one the operator of its PCS is accustomed to. The objective is a system, which, together with the measurement data of the PCS, compares prediction and reality in detail and from this identifies aging, component errors and deviations as automatically as possible and announces them to the operator. The autonomous repair is probably still a vision, but the regular adjustment of the regenerant consumption on the actual needs is already possible!

A trial of film forming substances at Staythorpe power station

Andrew Mosley and Cheryl Tommons

A trial of film forming substances was carried out by RWE Generation UK at their 1,735 MW (4 x 435 MW) Staythorpe CCGT power plant. As part of the trial, extensive plant monitoring was carried out to allow the performance of the film forming substances to be assessed and compared. All data was reviewed and observations made on the impact of the use of film forming substances on key plant parameters such as steam conductivity and iron transport. The performance of the two units operating with a supplementary film forming conditioning programme was also compared against the two units operating with a baseline conditioning programme only. The trial presented some challenges in regards to the operation and control of the film forming substance programme, namely dose rate control and analysis of the products. The different analytical techniques used to determine product residual and breakdown products are recommended and the overall impact on iron transport and plant internal condition is given.

Turbidity measurement as trend monitor for particulate corrosion products

Lukas Staub, Michael Rziha and Marco Lendi

Corrosion product monitoring is essential to determine the effectiveness of the cycle chemistry treatment program. Nowadays the determination of trends for corrosion products in the various systems becomes even more crucial due to the countless numbers of cycling plants as a result from the increased use of regenerative energy sources in the grids. The correct and complete determination of corrosion products, which are almost present as undissolved particles, can be realized by complex and time-consuming analytical methods only. For modern cycling plants these manual, analytical methods are of minor benefit, since the short time and strong oscillating, spiking behavior cannot be followed up in a complete and satisfactory manner. Certainly, such processes cannot be replaced by online measuring systems completely. However, some available online parameters are already in use as helpful trend monitor. The technical possibilities and limits of turbidity measurement are discussed as trend monitor for particulate corrosion products.

Formation of nitrogen-based emissions in circulating fluidised bed combustion plants

Stefan Zeltner

The generation of nitrogen-based emissions is, adjacent to the well-known dependence on the combustion temperature, also linked to the supply of oxygen in the combustion zone. The empirical based assumptions could be proved for the large scale by measurements of the generated raw gas in circulating fluidised bed incinerators. While the emissions of NO2, N2O, HCN and NH3 decrease exponentially with decreasing concentrations of oxygen, the curve progression of the generation of NO is similar to an upwards opened parabola with a vertex at about 2.2 Vol.-%. Based on these interrelationships, an optimum working point for the minimization of nitrogen-based emissions can be defined at an oxygen concentration in the raw gas of about 4 Vol.-%. The adaption of this parameter leads among the reduction of the NOx-concentration to an improvement of the plant efficiency due to a reduction of the required power demand of blowers.

Audit according to § 8a BSI-act – obligation for operators of the wind industry?

Stefan Loubichi

The world of the renewables is completely different and not comparable to the “old” word. The wind industry is [according to structural particularities] as well not able to deal in a good way with the IT-security catalogue according to § 11 Ib EnWG, issued in December 2018. (Technical) Operators in the wind industry have to deal with § 8a BSI-act. This leads to structural consequences. While the main contact in the case for IT security catalogue is the “Bundesnetz­agentur”, the main contact for § 8a BSIG companies is the “Bundesamt für Sicherheit in der Informationstechnik”. As well the powerful German accreditation body DakkS is not involved in the § 8a BSIG processes. A big challenge for technical operators [dealing with more than 420 MW] is the fact, that they normally had to present the results of the § 8a BSIG audits to the BSI already in 2018, while classic energy producers dealing with the IT-security catalogue must be successfully audited until March 2021. In this essay we introduce to you who is allowed to do the audit. Audit teams doing the § 8a BSIG audits have to fulfill more/different requirements than auditors doing the IT-security catalogue audits. As well we will present to you the process of auditing. The § 8a BSIG processes can as well not be compared with the audits according to the IT-security catalogue. Furthermore, the auditing standard ISO 27006 is not applicable for technical

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Wind Energy in Germany and Europe Status, potentials and challenges for baseload application
Part 2: European Situation in 2017

Thomas Linnemann and Guido S. Vallana

One essential physical property of wind energy is its large spatiotemporal variation due to wind speed fluctuations. From a meteorological point of view, the electrical power output of wind turbines is determined by weather conditions with typical cor-relation lengths of several hundred kilometres. As a result, the total wind fleet output of 18 European countries extending over several thousand kilometres in north-south and east-west direction is highly volatile and exhibits a strong intermittent character. An intuitively expectable significant smoothing of this wind fleet output to an amount, which would allow a reduction of backup power plant capacity, however, does not occur. In contrast, a highly intermittent wind fleet power output showing significant peaks and minima is observed not only for a single country, but also for the whole of the 18 European countries. Between 2015 and 2017 the European wind fleet’s power utilisation factor resulted in annual mean values between 22 to 24 % and continuously available (secured) annual minima between theoretically 4 and 5 % of its nameplate capacity despite tens of thousands of wind turbines distributed throughout Europe. Wind energy therefore requires a practically 100 % backup as long as the wind fleet’s nameplate capacity has not exceeded the cumulative load of these 18 countries considered, plus reserves.

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Effects of lignite phase-out and energy system transformation on climate and national economy

Dietrich Böcker

The Coal Commission, officially known as the „Commission for Growth, Structural Change and Employment“, was commissioned by the German Federal Government to set the date of 2038, possibly 2035, as the date for the phasing-out of coal. The aim is to reduce CO2 emissions in order to stabilise the global climate and at the same time prove that a highly developed economy can be converted from a fossil-based to a regenerative-based economy as planned and thus be a role model and pioneer in climate issues. The German energy revolution ignores the fact that CO2 emissions worldwide have risen steadily over three decades and will continue to rise. The self-set national climate targets have so far been missed. The lignite phase-out will have no measurable effect on the climate and causes very high costs. As a result, the climate and energy strategy must be readjusted.