Abstracts - VGB PowerTech Journal 10/2014

Steam turbine set Boxberg R – Experience gained during project execution and results

Udo Klauke, Marco Redieß and Jens Molsen

Vattenfall Europe Generation AG erected a 675 MW lignite-fired unit with supercritical steam parameters at the Boxberg power plant site in Saxony. The new unit with a net efficiency of more than 43.7 % at the design point is planned as efficient, secure and flexible base load supply and extension to the existing lignite-fired Boxberg power plant. Selected issues and events during the commissioning phase and experiences gained will be presented and statements will be made on the previous performance and optimisation.

Operation of power plants – Results and experiences in terms of maintenance intervals and strategies regarding high-pressure valves of the turbo group

Frank Biesinger, Kristian Enste and Johanna Steinbock

The Leininger 5 power station, operated by GDF SUEZ Energie Deutschland AG, a 472 MWnet power hard coal steam unit is located in Zolling. Crack-like indications were detected in 2011 at the inner surface of the live steam valves. To clarify the size of the indications, phased array inspections were conducted by the OEM. The indications were primarily located at the antiswirl ribs and at the fillet radii from the valve chest to the diffusor seat. Two re-examinations in 2011 and 2013 revealed no measureable change. The plant operator appointed the OEM to assess the cracks inside the valve bodies and TÜV SÜD Industrie Service GmbH, as an independent reviewer.

Dealing safely with varnish formation in turbine oil systems

Jens Steidtner

A common problem of modern turbines is varnish formation in lubricating and hydraulic oil systems. Varnish is the deposition of oil ageing and additive decomposition products with resin- or varnish-like consistency. The reasons are the efficiency optimised turbine design with an increased thermal stress of the oil filling and the specific ageing properties of modern turbine oils. Varnishes can cause malfunctions of valves and reduced cooling efficiency of heat exchangers. Turbines with high varnish potential require proactive turbine oil management, which helps to recognise unsafe operating conditions and to initiate counteractive measures.

WTA drying: Developments in the fields of coal preparation, fluidised bed drying and vapour utilisation and presentation of different process variants

Hans-Joachim Klutz, Ditmar Block and Reinhold Elsen

Preparation and dr ying are essential preconditions for using lignite in the industrial sector. In order to execute these process steps as efficiently as possible in terms of economy as well as energy consumption, RWE Power continued to develop the WTA process with a special focus on widening the range of possible lignite feed qualities. The article provides a general overview on developments during the last years focusing on coal preparation, fluidised bed drying and vapour utilisation for energy purposes. Furthermore different process variants are presented as examples for optimised integration of a WTA plant into industrial dry coal utilisation processes.

The project “Coal 2035”: Flue gas system renovation

Muriel Waret

The project entitled “Charbon 2035” is a renewal project of 3 x 600 MW coal units, i.e. Le Havre 4, Cordemais 4 and Cordemais 5. The project is aiming at improving their performances and extending their lifetime up to 2035. Thus the main equipment of the plants is restored and other systems are checked to ensure that they will meet future environmental regulations. The paper deals with air pre-heater (APH), electrostatic precipitator (ESP), gas gas heater (GGH) and flue gas desulphurisation (FGD). All works are to be terminated by 2016.

Eskom’s experience in wet flue gas desulphurisation (WFGD) design and construction

Keketsi Ramahali

The growth of the South African economy has led to an increased electricity demand. Eskom, the largest power utility in South Africa and Africa has embarked on a capacity expansion programme to increase its energy reser ve margin. Medupi and Kusile, Eskom’s two new coal-fired power stations are currently under construction. South African environmental authorities have introduced stringent gaseous emission legislation which has led to a need for SO₂ abatement technologies at Eskom’s new power stations. As a result, both stations will be fitted with wet flue gas desulphurisation (WFGD) plants to comply with the SO₂ emission limit. Medupi will be retrofitted with a WFGD while Kusile is being built with one installed.

Enhancing the range of future operation conditions by upgrading the HV power supply of electrostatic precipitators – A case study

Sebastian Kemper and Michael Kloeckner

In many cases increased ESP collecting efficiency is required due to changed operating conditions by more frequent boiler start/stop phases and load changes and the use of an increased number of different imported fuels or the aging process of the ESP. When the existing ESP configuration (mechanical and electrical) is already optimised and reaching the limit of ESP performance, the installation of newly available highvoltage power supplies based on IGBT semiconductor technology (switch mode power supplies SMPS) can provide further improvement as a low cost solution compared to the mechanical upgrade of the ESP.

Pilot plant studies of the CO₂ postcombustion process at the Dürnrohr power plant

Markus Rabensteiner, Gerald Kinger, Martin Koller and Christoph Hochenauer

In 2010 a PCC pilot plant (Post-combustion Capture) was put into operation at EVN´s coal fired power plant in Dürnrohr, Austria. Through the use of the power plant´s flue gas and the wellconceived dimensions of the test facility, industry-related conditions for full-scale applications can be provided. In addition to the benchmark solvent monoethanolamine (MEA), aqueous solutions of piperazine (PZ) and ethylenediamine (EDA) and aqueous blends of potassium carbonate and piperazine were tested.

Condition analysis and operating lifetime extension concepts for wind turbines

Thomas Korzeniewski

In Germany the basis for the expansion of wind energy was already laid at the beginning of the 1990s. Hence, the first wind turbines already started to reach the end of their permitted lifetime. At that time as today the different wind turbine types were engineered for an operational lifetime of 20 years. As reliable wind turbines types were already available in the 1990s, it is technically and commercially reasonable to consider the extension of their operational lifetime. Of particular interest is the lifetime extension of wind turbine types installed in the beginning of the 2000s. During that period many wind turbine types were launched which absolutely correspond to state-of-the-art technology.

Legal aspects of FGD plant erection contracts – Measures to minimise the projectrelated risks by drafting adapted contracts

Bettina Geisseler

Flue gas cleaning plant erection contracts are ver y complex. The paper outlines all the additional rights and obligations of the Parties, such as Employer’s obligation to cooperate or to provide information or Employer’s approval or inspection rights should be stipulated. Finally the paper deals with the acceptance procedure and Employer’s remedies in case of defects and Contractor’s possibility to limit its contractual liability.

Securing the future of the Lusatian lignite mining

Gert Klocek and Wolfgang Ketzmer

In the course of securing the future of the Lusatian lignite mining, the company has initiated several measures and activities. Thus with large-scale projects such as relocating the operating and surface facilities of the Welzow-Süd opencast mine uninterrupted long-term mining advance is ensured. The company´s lignitefired power plants with their project “FlexGen”, to further increased flexibility, enhances their position to master of the challenges of “Energiewende”. The political and societal framework for this complex development is in line with the climate and energy programmes or strategies of the Free State of Saxony and the federal state of Brandenburg.

The remediation of mines and water resources in the Central German coalfield

Eckhard Scholz

The LMBV informed about the state of rehabilitation of the former lignite mines and the latest challenges to maintaining public safety. Looking ahead, the assumption was that in both lignite mining regions remediation was being implemented to a high technical standard, that it had made good progress, and that it was continuing to have an important impact on local employment. The process of transforming the post-mining landscape is seen as engineering firms, administrations and authorities, institutions, mine remediation undertakings, building contractors, and the LMBV working together as a team. The core business is increasingly shifting in the direction of the water resources remediation.