Abstracts - VGB PowerTech Journal 8/2015

Design, build and operation of the HWT II material test rig (HWT II) at Grosskraftwerk Mannheim

Klaus Metzger, Rolf Stork, Karl Maile and Jörg Bareiß

Research, qualification and development of new processes for low-emission, high-efficient power plants need an increase in operating parameters. Applied materials technology research is aiming at the provision of materials and components for such applications. For the investigation of the technical implementation of a high-efficient, flexible and modern power plant technology, a field test with a 725 °C test section was carried out in the Mannheim power plant (GKM). The test facility with the acronym HWT II (high-temperature material test rig II) was implemented into boiler 17 of unit 6 in GKM. Nickel alloys were used as structural materials, which had never been used in power plants for thick walled components.

Design, manufacture and operation of valves at the 725 °C HWT II test rig

Oliver Birkle, Peter Linier, Gregor Gierschner, Franz Hansknecht, Manfred Wirsum, Hailu Tadesse, Mario Hamberger, Christopher Lange, Dierk von Nordheim and Olaf Tebbenhoff

Elevated steam temperatures and increasing load cycles have are directly impacting on their design and construction. The high-temperature materials test section II at Grosskraftwerk Mannheim power plant (HWT GKM II) currently offers the only possibility worldwide to verify the reliable function of shut-off and control valves at an operating temperature of 725 °C and under cyclic load conditions. 2,600 cycles were run at temperatures between 725 °C and 400 °C over an operating period of more than 8,000 hours. The limits of the valves were to be determined at these extreme conditions.

Production and processing of nickel alloys for the field test section HWT II at Grosskraftwerk Mannheim GKM

Nicole de Boer, Karola Klenke, Bernhard Donth, Vida Knezevic, Jürgen Paal, Patrik Schraven and Fred Grimm

As part of the research project HWT II, thick-walled components of the nickel-based materials alloy 617B and alloy C-263 were manufactured for and tested in the test section HWT II at Grosskraftwerk Mannheim GKM. In this paper all material manufacturers summarise their successful production and processing of the nickel based alloys for the components of the HWT II test track in GKM: melting and remelting, forging of pre-materials and forgings/rods, hot extrusion and cold pilgering of boiler tubes, production of thick-walled pipes by extrusion as well as welding consumables for fusion welding of the nickel alloys.

Accompanying inspections during design, installation, commissioning and operation of the high-temperature test section HWT II at Grosskraftwerk Mannheim AG

Hans Christian Schröder, Claas Lehmkuhl, Jörg Schenkel and Helmut Nies

The research project HWT II has provided evidence that a pipe made of the material alloy 617 mod./alloy C-263 is able to be implemented as an integral part of a power plant running at temperatures higher than 700 °C in daily start and stop mode and additional forced load cycles. With a number of 2,680 load changes the designated number has been exceeded. The overall operation time at 720 °C was about 10,000 h. Findings that have been detected during scheduled periodical tests at several components had no impact on the project activities. Those findings lead to an amount of awareness and a potential of ongoing researches e.g. “Mechanism of crack initiation under thermocycling conditions in thick-walled components”. Furthermore the project provides the participants with a number of details for design optimisation of thick-walled components, particularly for fittings, valves and control devices.

High-temperature material test section HWT II – Experimental and numerical tests of material and components

D. Hüggenberg, M. Speicher, A. Klenk, S. Zickler, M. Schwienheer, Y. Wang, P. Schmitt, H. Oesterlin, G. Maier and B. Niewe

Thick-walled tubes made of the alloy 617B and alloy C263 were provided for the test section in GKM Mannheim and an accompanying investigation programme which was aiming at gaining a deeper understanding of these materials and their welded joints. The investigations comprise the determination and evaluation of material properties by mechanical material tests and microstructural investigations. For basic material qualification and qualification of manufactured components, an extensive experimental investigation programme as well as tests to ensure quality of materials, welds and repair welds was initiated. To support design optimisation material laws (constitutive equations and damage parameters) and to characterise deformation and damage, evolution has been developed and numerical simulations using these material laws were carried out in order to determine component loading and lifetime. With the accompanying investigations in combination with results from the test section, the general applicability of the materials for components operated at temperatures up to 725 °C could be proven. Compared to materials used yet (e.g. martensitic steels), the nickel alloys investigated show different properties, which have to be considered in design, operation and surveillance.

Impact of the new and more flexible grid code requirements on future operational behaviour of turbine generators

Stephan Wittner, Ana Joswig, Thorsten Krol und Jürgen R. Weidner

The integration of renewable energy sources (wind and PV) with power feeding preference into the high-voltage grid results in fundamental changes of load regime in European transmission system. The new European Network Code for generators ENTSO-E NC RfG specifies more flexibility in operation to maintain security of energy supply and grid stability. For generators above 75 MW these requirements would include an extended voltage-frequency range, a greater reactive power versus frequency spectrum and an increased load change gradient for higher power demand flexibility. The impacts of these new grid requirements to be met by existing and new generators will be outlined.

CHP expansion strategy in North Rhine-Westphalia – A blueprint for other regions

Dominik Holzapfel and Sabine Schneider

The North Rhine-Westphalian state government intends to increase the share of combined heat and power (CHP) generation to at least 25 % by 2020. Since 2013, the campaign “CHP.NRW – Power Meets Heat” (“KWK.NRW – Strom trifft Wärme”) of the EnergyAgency.NRW, is has been running on behalf of the NRW Climate Protection Ministry, to publicise this technology and to promote its expansion. The campaign accompanies the State Government’s CHP Stimulus Programme. The EnergyAgency.NRW has organised companies and research institutions, associations and interest groups under the umbrella of “CHP.NRW – Power Meets Heat”, aiming at co-ordinated and intensified activities in the field of combined heat and power generation. The target of the initial-project “roadmap|CHP.NRW” of the “Virtual Institute | CHP.NRW” is to develop a guideline for the application and optimisation of CHP-systems.

Lifetime-diagnosis of deteriorated natural draft cooling towers

Ulrich Eckstein, Daniel Jun, Winfried B. Krätzig, Ralf Wörman and Peter Blömeke

Natural draft cooling towers (NDCTs) with a height of around 100 m and above for thermal power plants in Europe presently have reached ages of up to 50 years. If their thermo-mechanical plant components are subject to lifetime extensions or changes of their service-modes, also safety and life duration may be questioned for the corresponding NDCTs In order to assess the structural safety, a diagnosis concept for lifetime extensions is inevitable. Cooling tower deterioration phenomena are being explained. The appearance and the extent of these phenomena serve as a basis for the assessment of the actual structural state of cooling towers. The applied diagnosis concept for lifetime extensions will be explained in the following and partly illustrated by three recent examples.

The wet ESP as enhancement for the FGD technology

Martin Mikl, Harald Reissner and Christian Weiß

In order to meet future requirements for raw gas treatment, concerning dust- and aerosol removal efficiencies, an integrated combination consisting of a wet ESP (electrostatic precipitator) and an FGD (flue gas desulphurisation) spray tower was designed to test its suitability for these requirements. Implementation of the wet ESP in the FGD spray tower concept promises high removal efficiencies for dust and for acid mists, which are of course much higher than the removal efficiencies which can be achieved by the FGD spray tower itself. During 16 months of pilot operation, the aspired removal efficiencies and the reliability concerning plant availability or fouling was proven.

Investigations of limiting mercury peaks in municipal waste incineration plants

Martin Mineur and Hartwig Söth

Municipal waste contains mercury in small amounts which is reliably removed in waste incineration plants under normal conditions. But sometimes waste is delivered in charges in which mercury is present with significantly higher levels without being declared. In such cases, the flue gas cleaning system can be overextended for a short time. Therefore, options were sought to increase the elimination capacity in such situations. It is of central importance to detect such an impact of mercury very early on in order to initiate effective measures. A continuous mercury measurement system was installed directly behind the boiler at the Borsigstraße incineration plant in Hamburg. In test situations, a specific amount of up to 2 kg of mercury was thrown into the boiler and measurements were recorded along the flue gas path for both ionic and elementary mercury. With an injection of impregnated activated carbon, the performance of the fabric filter is able to be raised significantly.