Abstracts - VGB PowerTech Journal 12/2014

Technologies and challenges from the viewpoint of the power plant operators

Bernhard Fischer

The energy markets are currently undergoing fundamental changes. Time-tested business models no longer work in their previous forms. New market mechanisms and models are being discussed. In order to continue to play an active role as an energy provider in an environmentally friendly, reliable and affordable energy system, it is necessary to adapt to the challenges of the market. Against this backdrop, energy suppliers must provide answers in the public and political debate.

Restructuring of power plant operator advanced training – Challenges and opportunities

Markus Bieder and Christian Umierski

Power plant operators and power plant shift supervisors are essential operating agents in our power plants. This also means that they make a vital contribution to the value chain. The amendment of the examination regulations for power plant operator advanced training envisage a shorter training period. The power industry is advised to work out an individual concept to accommodate the new general conditions because training and acquisition of theoretical knowledge are markedly harder without practical application. Educational institutions are required to adapt to the new situation and will amend their product range accordingly in 2015.

Application of optical diagnostics as an experimental tool for the development of combustors for stationary gas turbines

Benjamin Witzel, Michael Huth and Christof Schulz

Today’s energy market places high demands on the manufacturers of stationary gas turbine. Besides higher efficiency and lower emissions, increased flexibility (e.g. in terms of operation or fuels) and low operational costs play an increasingly important role. Achieving these goals requires the application of advanced experimental and numerical tools in the development process. Hence, fuel/air mixture imaging with acetone LIF was applied at selected Siemens gas-turbine burners. For this purpose, dedicated test rigs and a tracer-gas supply facility were developed and put into operation.

New system characteristics in converter-dominated grids

Carsten Heising, Roman Bartelt and Holger Wrede

Characteristics of grid systems are always dominated by the characteristics of the typical grid participants. In conventional grids, synchronous generators are the key components which offer highly dynamic overcurrent capability and directly connect relevant energy storages to the grid system (rotating masses). In contrast to this, power-electronic converters offer no relevant overcurrent capability (not even in the subtransient time scale) and do not couple an energy storage directly to the grid system (additionally, in general the storage capability is notably smaller). Related to these fundamental differences, in converter-dominated grids conventional approaches are not applicable without changes.

Wear investigation model for primary and secondary controlled thermal power plants of the ENTSO-E-grid

André Berndt, Maria Richter, Moritz Hübel, Patrick Mutschler, Harald Weber, Egon Hassel and Manuela Sander

The progressive development of renewable energies leads to changes in the use of conventional thermal power plants. To cover current load requirements, conventional power plants deliver positive as well as negative output reserve within seconds to a few minutes (primary and secondary control). The aim of this project is to determine the impact of the provided services on the lifetime of the power plant components. Therefore, dynamic models of different types of power plants are created and several load change scenarios are investigated in simulations.

Specific repair solutions for the continued operation of operationally stressed turbine components using the example of a valve casing

Christoph Zierow and Stefan Zahariev

When overhauling power plant turbo sets, longterm operationally conditioned faults on turbine components are found regularly. They call for individual and fast repair solutions within the small time frame of an outage. The following report covers Alstom Power‘s repair of a bypass valve casing with substantial crack damage. The repair solution required efficient and goal-oriented team working in engineering, NC programming, welding technology, NDT and production.

Preparation of a gas turbine start by considering European standards

Friedrich Hala, Reinhard Willinger, Rudolf Pichler and Franz Aschauer

A discussion about the starting process of gas turbines also concentrated on the initial steps preceding the ignition of the burners as well as on safety and operational measures in particular. Current operation manuals and above all the expired regulations in “Technische Regeln für Dampfkessel” (TRD; “Technical Regulations for Steam Boilers”) and the European Standard EN 12952-8, which has replaced TRD, served as a basis. The initial steps in starting a gas turbine are covered in EN 746-2.

Online monitoring Early detection and diagnosis of initiating damage in turbo generators

Martin Biesemann and Frank Ewert

The influence of renewable energy is increasing, resulting in increasingly required medium and peak load operation of fossil power plants for the stabilisation of the electrical grid. This leads to increased thermo-mechanical stress for the core components like the generator due to the increasing number of load cycles and accelerated aging. As preventive measure it is helpful to use online condition monitoring and diagnosis systems to receive information about the state of the machine during operation between the periods of regular inspections.

Operating experience with high-temperature superconducting fault-current limiters (HTS fault current limiter) in the auxiliary system of power plants

Thomas Krüger, Klaus Pfeiffer and Oliver Stenzel

In cooperation with Nexans Superconductor GmbH, the Vattenfall Europe Generation AG was running long-term field tests for a hightemperature superconducting fault current limiter used in the auxiliary system of power plants. The fault current limiter was used for feeding 10 kV switchgear. In the course of the field tests, important knowledge regarding operation and design of HTS fault current limiters could be gained. Especially the second fault current limiter, based on tape design, could convince due to its reduced cooling requirements and an even more dynamic reaction in the case of a short circuit. The cooling system is here an important factor for a reliable operation mode.

30 years refractory linings in fluidised bed combustion systems – Operating experiences lead to a new organisation-spanning standard

Matthias Trost

CFB boilers have potentials for burning or coburning revised derivate fuel, biomass and the energy recovery of other residual materials. Thus, at remaining plants it is necessary to pay the required attention to the refractory lining in order to avoid impacts on the availability of the currently “ambitious” fuels. The VGB Working Group “Fluidised Bed Firing” and the umbrella association of the refractory industry “Deutsche Gesellschaft Feuerfest und Schornsteinbau” (DGFS) are about to transform the VGB Instruction Sheet into a new VGB/DGFS Standard, in which numerous experience cases from planning, material procurement, installation and operation are considered.

Compliance of the boundary value for the acid conductivity of VGB guideline for power plants using amine containing corrosion inhibitors – Experiences of two power plants

Karsten Cramer, Johannes Münz and Christian Brief

Various chemicals are used to avoid corrosion processes in power plant water-steam cycles. In the past few years water treatment with organic corrosion inhibitors was further developed and a lot of scientific studies were published and discussed. In the recent past some research results were presented dealing with acid conductivity of feedwater upon the application of amines in the water-steam cycle. When selecting the proper amine products and correct dosing, the required limit value of < 0.2 µS/cm acid conductivity can be met as demonstrated by two examples.