Abstracts - VGB PowerTech Journal 5/2015

Solutions for increasing flexibility requirement in power generation to achieve major cost savings

Markus von Zmuda

The natural fluctuations of renewables-based energy are very challenging. Thermal power plants need more flexibility to make up for these fluctuations. It is being debated which technologies are really flexible. Wärtsilä defines the true value of flexibility in power systems and proposes market mechanisms to support the implementation of SPG, the optimum route to renewables integration and thus security of supply.

Options for a flexible residual load generation – Could power-to-gas be as solution?

Klaus Görner

The so-called “Energiewende” in Germany brings about a substantial change in the energy supply portfolio. Even today the share of renewable energy has a considerable impact on stable electrical net operation. There are periods with more power gained by renewable energy than needed in the electrical net. This oversupply can e.g. be supplied abroad – occasionally even at a negative market value. Above all, this oversupply of power can be utilised by using electrolysis to produce hydrogen and/or to produce methane by using an additional process step. Hydrogen and methane can be fed in into the natural gas net. Both can be used at the “right” time and at the “right” place by re-electrification.

Human Tools in nuclear power plants – Introduction, implementation and experiences

Kai Dexheimer and Gerd Bassing

The basis of safe nuclear power plant operation (NPP) and a strong safety culture is the professional application of Human Performance Optimisation Tools (HPO). HPO trainings have been carried out by German NPPs for a number of years and recently also by Swiss NPPs. This article describes the origination, the bases, experiences and thereby the special features of the HPO training programme applied by German NPP operators. Moreover, this article provides an outlook on future developments – in particular when considering the requirements of the ongoing phase out of nuclear energy in Germany.

Chemical decontamination in BWR Philippsburg 1

Micael Jürgensen and Michael Bolz

After the accident in the Fukushima nuclear power plant, the Philippsburg nuclear power plant (KKP1) was shut down for good due to political decision on March 17, 2011. Following the shutdown, all power plant components must be dismantled. This includes also parts that had been radioactively contaminated during operation. In order to reduce the dose rate for personnel involved in decommissioning, it is necessary to remove active oxide layers that had been formed during passivation. The systems are decontaminated by treatment with oxidative and reductive reagents which chemically dissolve the oxide. A report is given on the experience made with the chemical decontamination system in KKP 1.

The use of reverse osmosis at nuclear power plants – Replacement of evaporator

Pavel Kus, Sarka Bartova, Katerina Kunesova, Vladena Smejdova and Katerina Vonkova

Evaporators are being used in nuclear power plants for the treatment of primary coolant containing H3BO3 for neutron absorption and other components for adjusting water chemistry. The aim is to achieve a concentrated H3BO3 solution, which is further purified by ion exchangers and then recycled into the primary cycle. Operation of evaporators is expensive, therefore reverse osmosis was proposed as one promising alternative. A pilot-plant RO unit was used for the experiments performed with feed solution. The successful technology is now being implemented at Temelín NPP.

CASTOR® and CONSTOR®: A well established system for the dry storage of spent fuel and high level waste

Hannes Wimmer, Jürgen Skrzyppek and Michael Köbl

The German company GNS Gesellschaft für Nuklear-Service mbH today looks back on more than 30 years of operational experience with dual-purpose casks for the transport and storage of spent nuclear fuel (SNF) from nuclear power plants and high level waste (HLW) from reprocessing. Following customer demands, GNS developed two different cask types for SNF. By now, almost 1,300 GNS-casks are in operation worldwide. This article gives an overview over several national and international projects and shows the bandwidth of customised solutions by GNS.

„Rückbau 2014“ – KWS Congress regarding decommissioning and dismantling at Zwentendorf nuclear training power plant

Herbert Maaßen

From September 24 to 25, 2014, KRAFTWERKS-SCHULE E.V. (KWS) held the congress “Rückbau 2014“.This first congress about nuclear power plant decommissioning was combined with an exhibition in the fully equipped Zwentendorf nuclear training power plant. The exhibitors had the opportunity to present and test their products in the ambience of a real nuclear power plant, close to original plant components. The visitors got a general overview of the on-site conditions. During the lectures the process of decommissioning and dismantling of a nuclear power plant were described, problems within this process were discussed, and possible solutions were recommended.

A new concept for the utilisation of waste heat: Siemens implements the flexible multi-stage steam turbine SST-111

Thomas Müller, Matthias Schleer and Udo Attermeyer

The newly developed SST-111 steam turbine from Siemens is especially well suited for distributed power generation in smaller biomass or waste processing plants. With the SST-111, the flexibility and controllability of a simple single-stage geared steam turbine have been combined with the efficiency of a multi-stage turbine – all at comparably low investment costs.

Experiences with the optimisation of waste-, substitute fuel and biomass power plants – Simple implementation with great efforts

Sascha Krüger and Jörg Krüger

Optimisation measures (for waste-, refuse derived fuel-, and biomass incineration plants) that can be applied easily can offer savings and operational benefits for the operator. The optimisation measures presented range from fuel feeding system (e.g. atmospheric water cooling at waste feed throat) to the firing and flue gas cleaning systems (direct lime injection to support flue gas cleaning during HCl and SO2 peaks), energy recovery (feedwater temperature drop, boiler pre-warming with MP steam) up to waste disposal from wet offline boiler cleaning.

High-temperature thermal energy storage for the decentralised energy sector

Andreas Dengel, Markus Seitz, Maike Johnson, Christoph Becker and Maximilian Zimmer

Combined generation of heat and power plays an increasingly important role in decentralised energy generation. Especially for the supply of large objects in local heat networks, but also in district heating, optimum use of primary energy sources is being pursued through cogeneration. When the energy is supplied by renewable energy plants in cogeneration, these systems naturally result in a heat-driven control system. This leads to a discrepancy between optimum marketing of electricity and provision of heat. This project investigates whether heat storage, especially high-temperature storage for storing exergetically high-quality heat, can result in flexible operation strategies of such energy converters.

Hetragon^TM: Chemically resistant heat transfer polygons for gas-gas heaters in FGD and SCR/SNCR applications

Michael Schlipf and Katja Widmann

Environmental regulations require modern coal- and oil-fired power plants to be equipped with flue gas desulphurisation (FGD) and denitrification (DENOX) plants to ensure cleaning of the flue gases. Gas-gas heaters (GGH) are employed in FGD and DENOX plants in order to remove sulphur and nitrogen emissions under temperature-optimised conditions. If the GGHs are of the Ljungström®-type, corrosion can be avoided if the heat exchanger is equipped with fully corrosion-resistant heat transfer polygons in those regions where the system is operated below the dew point of the chemical mix. The innovative heater elements made from PTFE may be the material of choice to make this cleaning operation more easily in the future.

Dissolved oxygen measurement at light speed

David Gray und Kirk Buecher

Dissolved oxygen is a critical parameter to monitor in power plant make up water, cycle chemistry and generator stator cooling systems. Newer technology optical dissolved oxygen sensors use the principle of fluorescence quenching and light detection for oxygen measurement. This technique, now well proven for in-line low-ppb measurement, offers an effective method for monitoring and controlling dissolved oxygen in power plant applications. The paper examines current optical sensor technology and its use in power plant applications including comparisons with electrochemical methods.

Operating experience with nuclear power plants 2014

The VGB Technical Committee “Nuclear Plant Operation” has been exchanging operating experience about nuclear power plants for more than 30 years. Plant operators from several European countries are participating in the exchange. A report is given on the operating results achieved in 2014, events important to plant safety, special and relevant repair, and retrofit measures from Belgium, Germany, Finland, the Netherlands, Switzerland, and Spain.