Abstracts - VGB PowerTech Journal 3/2012

Flexibility increase with latest technologies

Michael Fübi, Florian Felix Krull and Michael Ladwig

Flexibility demands on conventional power plants rise to ensure grid stability within a power generation mix with drastically increasing capacities of renewable power generation sources such as wind farms and photovoltaics. In this paper flexibility requirements for a power plant portfolio are discussed. Through selected examples of projects from RWE’s current investment programme, comprising around 13 GW of efficient and flexible power plant capacity in Germany, the Netherlands, Turkey and the UK, application of the latest technologies to fulfil flexibility requirements is presented. Further, the potential of smart retrofits in terms of combined flexibility and efficiency gains is illustrated by means of an existing power plant unit retrofit project.

Powering Europe in the 21st century

David J. Powell and Brian S. Hunt

Nuclear power has provided sustainable, clean, and affordable electricity generation in Europe for over 50 years and will continue to play a critical role in the years ahead. This paper discusses the likely trends in Europe’s evolving energy situation and the positive role nuclear power can play. The benefits that nuclear power brings will be discussed as well as the need for the diversification of Europe’s energy supply. The keys to a successful nuclear new build are safe and simplified plant designs, predictable construction cost, reliable and safe operation of both new plants and the current fleet. The primary nuclear power technologies, PWR and BWR, will be described and compared in the areas of safety, operation, and economics with particular emphasis on the latest BWR designs. Lastly, an option to close the nuclear fuel cycle will be examined.

EU network codes: Implications for the operation of power plants

Jens Paetzold

ENTSO-E published on March 22, 2011 “ENT­SO-E Draft Requirements for Grid Connection Applicable to all Generators“[1]. These requirements are part of a European regulation of network codes. The requirements are in line with the ACER Framework Guidelines on Electricity Grid Connections. This Network Code defines a common set of requirements for Power Generating Facilities, including Synchronous Generating Units, Power Park Modules and Offshore Generation Facilities and sets up a common framework for grid connection of Power Generating Facilities. A new version was published on January 24, 2012. This document is issued for formal public consultation of stakeholders. This paper contains same critical comments to different requirements.

Worldwide top values achieved in the Ulrich Hartman CCGT power plant

Peter Maagh and Willibald Fischer

Between September 2006 and January 2011, the gas-fired unit 4 of the power plant operated by E.ON was built at the Irsching site near Ingolstadt. A prerequisite for this was development of the new Siemens Energy 8000H gas turbine, which was initially tested in Irsching in simple cycle mode. By adding a Benson HRSG and a high-temperature steam turbine the unit was later extended for combined cycle duty. For the very first time a plant efficiency of over 60 % was achieved The combined cycle plant is characterised not only by its specific power but above all by its efficiency and operating flexibility.

The EPRTR and possible implications regarding coal-fired and natural gas-fired power stations

Frans van Dijen

With the introduction of the European Pollutant Release and Transfer Register (EPRTR) new emissions must be reported, when these are relevant. So, from the compounds listed, the relevant emissions must be separated from the non-relevant emissions. The goal of the different projects was to present arguments on this separation of compounds. Especially with the construction of new power stations, emissions to air and water can be further and relatively easily reduced.

Change from neutral treatment to oxygen treatment at the waste incineration and combined heat and power plant Stuttgart Münster of EnBW Kraftwerke AG

Harry Rösemann, Sabine Kappler-Amft and Dagmar Pöchmann

The waste incineration and combined heat and power plant Stuttgart Münster includes three waste incinerators. Additionally three coal-fired boilers are operated as back up for the district heating system. Electricity is produced by two condensing turbines and one backpressure turbine.
In 2007 two new waste incinerators were erected and the feedwater tank of the remaining third incinerator K26 was refurbished. After start-up of the new waste incinerators and the new feedwater tank of K26, an anomalous unsteady increase of iron in the feedwater of K26 has been detected. The reasons why could not be explained. It was concluded that the new feedwater tank of K26 is fulfilling the tasks of degasifying more perfectly than before thus creating a lack of oxygen in the system proved by oxygen measurements in the feedwater upstream the boiler. Consequently it was decided to change the chemical treatment and moved to oxygen treatment for the waste incineration system starting in November 2010 with satisfying results.

The revised VGB standard for water-steam-cycle chemistry

Frank Udo Leidich

The existing VGB Guideline VGB-R 450 Le “Guidelines for Feed Water, Boiler Water and Steam Quality for Power Plants/Industrial Plants”, 2006 was revised and updated. In comparison to the prevision version, it contains a number of important additions. Proven chapters have also been updated, e.g. better definitions in respect of necessity, response time and extended scope of diagnostic analysis campaigns.

Influencing factors on the emission of mercury from wet flue gas desulfurisation slurries

Barna Heidel, Silvio Farr, Kevin Brechtel, Günter Scheffknecht and Harald Thorwarth

In this study, the chemical reduction and reemission of absorbed HgCl2 from slurries of a lab-scale wet FGD system was investigated. The ambivalent effect of SO32- concentration on Hg chemistry was revealed. Low concentrations of SO32- below 0.1 mol/m3 increase stability of Hg2+ by formation of Hg2+ complexes with SO32- ligands. At elevated concentrations of SO32-, their potential as reducing agent surpasses their favourable complexing function, thus leading to increased formation and reemission of HgO. The effect of operational pH on complex stability depends on the concentration of the dominating ligand in the slurry.

Strategies for enhancing the co-removal of mercury in FGD-scrubbers of power plants- operating parameters and additives

Jan Schütze and Heinz Köser

Co-combustion of waste fuels, coals with variable mercury content and lower regulatory emission limits are drivers for the optimisation of the co-removal of mercury in flue gas desulphurisation (FGD) scrubbers. The paper explains some new features of the system performance of FGD scrubbers for the co-removal of mercury in coal-fired power plants. Results on their efficiency under standardised laboratory conditions are presented. The effect of these measures on the quality of the FGD by-product gypsum will be covered as well.

Alternative insulating liquids compared to classic mineral oil

Ernst Pagger, Michael Muhr and Georg Pukel

Alternative insulating liquids such as natural and synthetic esters and silicone oil are used more and more because of their special properties like significant higher flash and fire point compared to mineral oil improved biodegradability of natural and synthetic esters compared to mineral oil. Especially in critical areas such as small transformers in residential districts and underground power stations as well as for wind power plants the use of alternative insulating liquids will increase. As long time experience compared to the classic mineral oil is not available, the use of these liquids is afflicted with a number of uncertainties. Using higher temperature for the attempts should help to extrapolate the results.

Influence of temperature on electrical conductivity of diluted aqueous solution

Heinz Wagner

Electrical conductivity of a dilute aqueous solution is a measure of the total amount of ionic solutes that are present. As a sum parameter it provides the evaluation of the quality of boiler feedwater, purity of the steam and the condensate. As conductivity values are dependent on temperature, the measured values are converted to the reference temperature of 25 °C according to the physical-chemical laws of electric conductivity. Conductivity diagrams for different chemical components illustrate this characteristic property.

FGD gypsum as a raw material used in the gypsum industry - Variations in quality and quality problems, impact on the product, elimination of malfunction in the Flue gas desulphurisation System (FGD)

Harald Schmitt

The major quantity of the FGD gypsum produced is used today as raw material in the gypsum industry for the production of gypsum-based building materials for interior partitioning. The common basis of the European gypsum industry and the coal-fired power stations is the FGD gypsum quality standards commonly developed. The compliance with the quality parameters plays an important role both as for the acceptance of FGD gypsum as product and for the downstream production processes as well. This paper describes the variations in and problems with the observation of the quality parameters, their impacts on the downstream production processes of the gypsum products as well as the remediation of the malfunctions in the FGD.

Qualifying materials for the 700/720 °C Power Plant - Results from MARCKO 700 Part II: Components Test and Simulation

Kay Schmidt, Andreas Klenk and Eberhard Roos

The boiler of a future highly-efficient power plant with steam parameters of 700 °C and 350 bar is to employ nickel base alloys as well as a low-alloy 2.5 % Cr steel. In this paper a test rig, developed at Materialprüfungsanstalt MPA Universität Stuttgart, will be introduced which has the ability to test water wall-like specimen under almost realistic steam conditions. With the help of a modern constitutive creep equation, based on a modified formulation of Graham and Walles, the stress relaxation and deformation behaviour of the components were simulated and compared with the experimental results.