Abstracts - VGB PowerTech Journal 4/2011

New fossil-fired power stations in Europe - Status and perspectives

Wolfgang A. Benesch and Sauro Pasini

The security of electricity supply in Europe can only be assured by a well-balanced energy mix. To ensure the increasing amount of stochastic renewable sources like e.g. wind and solar power, economically competitive coal- and gas-fired power stations are needed. Nevertheless, currently more and more projects are stopped and postponed. In that context questions like: What is the background? What is the current situation? What should be? What are the causes? What is needed? are discussed.

Pumped storage plants - Status and perspectives

Peter Vennemann, Karl Heinz Gruber, Jon Ulrik Haaheim, Andreas Kunsch, Hans-Peter Sistenich and Hans-Rudolf Thöni

Pumped storage plants (PSP) enable the storage of energy with rated capacities of order of GW at a single site. Reservoirs allow charging and discharging times of at least hours, sometimes days or even up to several weeks. Short ramp-up times permit the participation in the secondary reserve market as a standing reserve. For bulk energy storage, PSP reach the lowest, specific costs. In the EU27 countries, Norway and Switzerland, a total of 44 GW of pumped storage capacity is installed. The utilisation of PSP strongly correlates with the amount of conventional generation capacity, rather than with topographical options.

Analysis of a gearless medium-voltage variable speed gas turbine system

Florian Mura, Rik W. De Doncker, Bernhard Persigehl, Peter Jeschke and Kay Hameyer

The fluctuating energy generation from volatile sources, such as photovoltaics and wind may be compensated through flexible gas turbine systems. Furthermore, gas turbines in the megawatt range are used in small co-generation plants (combined heat and power) for industrial applications where process heat is required. A gearless gas turbine system was analysed that is coupled to the electrical grid using a medium-voltage frequency converter. Thus, generator speed and grid frequency are decoupled from each other, enabling gas turbine operation at optimum speed for highest efficiency.

"Zero liquid discharge" for combined cycle power plants by using closed loop recycling methods - An important step for the environment

Anke Söllner, Wolfgang Gück, Herbert Fahrnbauer and Oliver Rappich

To minimise the water consumption in arid areas the re-use of water has been common practice for many years. The "Zero Liquid Discharge Concept" (ZLD)has been applied in combined cycle power plants (CCPP). However, until now usually in the ZLD the water-steam cycle was considered. With the ZLD approximately 90 % of the water can be re-used. Now a complete approach for the whole power plant is applied. The goal is to avoid liquid discharge from the CCPP to the environment and consequently to reduce the consumption of raw water. The remaining single process wastewater streams are evaluated as well as the special treatment of these streams. Due to the application of ZLD about 98 % of water can be re-used.

Cycling operation: Improving HRSG chemistry through a change from AVT (R) to AVT (0) at the Sermide power plant

Aldo Azzoni and Roberto Ferraresi

Edipower is looking for ways to improve operation of the Sermide power plant. In 2009 Edipower started a monitoring programme for FAC issues based on visual inspection in HRSG drums, non-destructive testing and residual thickness on low pressure elements and membrane filtration on of feedwater. The first evidences of the inspections showed non-optimised conditioning in HRSG chemistry. Conrol and automation of the AVT operation can be achieved by reducing feedwater oxidation at operating temperature and -pressure.

Evoniks's long-term catalyst operating and management experience

Matthias Schneider and Hermann Brüggendick

The exchange of SCR-catalysts is the biggest operating expenditure at the plant component SCR reactor at Evonik STEAG. The longest possible lifetime is therefore desirable. To ensure this, Evonik STEAG has introduced a centralised management catalyst system for the entire power plant fleet. The scope and benefits of this instrument and the operating experience which could be obtained in the last years will be described.

SCR optimisation in Danish coal-fired plants

Jimmy Andersen, Soren Christensen and Jan Hvidberg

From 1 January 2010, a new Danish tax on NOx emissions (0.7 EUR/kg NOx) worked as an incentive for minimising NOx emissions from power plants. Previously, an emission limit of 200 mg NOx/Nm3 had to be complied with, which was easily achieved, since all major Danish coal-fired power plants are equipped with high dust SCR (Selective Catalytic Reduction of NOx) systems. With the new NOx tax, a number of initiatives have been taken in order to maximise the DENOX capacity of the SCR systems. All efforts have led to a significant decrease in NOx emissions from DONG Energy's coal-fired power plants.

Optimised Thallium precipitation in a waste water treatment system of the flue gas desulphurisation

Günter Ritzerfeld, Ingolf Birngruber and Thomas Mülder

When co-combusting substitute fuels in power plants, the element Thallium should be checked in the drain of the waste water treatment system of flue gas desulphurisation. In 2005 Thallium-concentrations exceeding the limit value were determined for the first time as a consequence of the modified analysis of the supervisory authority. The previous lower Thallium concentrations with graphite tube-atomic absorption spectrometry were caused by the high chloride concentration in RAA waste water. The RAA operating mode was checked and changed. Equipment-related weak spots were detected and corrected.

Multi-pollutant control capabilities of double contact flow scrubber (DCFS)

Tatsuto Nagayasu, Hiroshi Nakashoij and Nobuo Imai

The paper highlights the achievements of SO2 outlet concentration (< 50 mg/Nm3-d), SO2 removal efficiencies (≥ 99 %) on various sulphur coals without buffer additives, and particulate matter outlet concentration (< 5 mg/Nm3-d) in recent operating experience. The Limestone Injection System (LIS) is a technology to inject pulverised limestone into the flue gas before GGH and neutralise SO3 mist. The mercury removal technology consists of SCR and FGD process control. Either HCl or NH4Cl is injected upstream of SCR catalyst to oxidise elemental mercury and DCFS removes oxidised mercury. Re-emission of mercury from DCFS is minimised by Oxidation-Reduction Potential control. This paper presents results from the operation of 5 MW-scale Mercury Research Centre and mobile 2 MW-scale DCFS at generating plant, showing that this system can control Hg emissions (1 µg/Nm3-d) or removal rate (> 90 %).

High performance dust collection - Precondition for undisturbed CO2 scrubbing

Jochen Lerche and Helmut Dreuscher

Discussions about climate change intensified research and development of procedures for CO2 capture and storage. Some complex technologies for capturing and liquefying CO2 also require further reduction of the limit values for SO2, SO3 and NOx. According to the state of the art, dust is precipitated by ESP or fabric filters downstream of coal-fired large steam generators. Fabric filters with pulse-jet-cleaning are able to achieve dust values of clearly below 5 mg/Nm3 dry.

Numerical modelling as a tool in effect-evaluation of chlorination by-products via cooling water discharges

Maarten Bruijs, Harry Polman and Rudie Heling

Chlorination is globally still the most applied method to mitigate biofouling in coastal power stations. It has proven its efficiency and the environmental effects are low when applied correctly. With new European legislation it is increasingly important to assess the potential environmental impacts of chlorine by-products. The application of the THREETOX model, which allows simulating transport and mixing of cooling water, in both the freshwater and the marine environment, is discussed.

Monitoring of lubricating and hydraulic oil in turbine plants

Jens Steidtner and Dieter Aschenbrenner

In recent years the demands on lubricating oils and governor fluids in turbine plants were constantly increased due to efficiency-optimised turbine designs. Respective standards and OEM specifications have taken these developments into account by raising the minimum requirements for the ageing stability of turbine oils. Oil producers have reacted by creating new formulations that are more resistant to thermal and oxidative stress. The new generation of turbine oils exhibits an ageing behaviour, which is different from classically formulated products and results in an increased tendency towards the formation of sludge and deposits. In order to recognize unsafe operating conditions early enough despite the altered properties of turbine oils, an adaptation of the in-service condition monitoring strategy is necessary.

Considerable failure of the 320 MW gas turbine of a compressed air storage gas turbine power plant

Manfred Freimark, Bastian Schreyer, Uwe Krueger, Bernd Meixner and Udo Gampe

A report is given on a considerable failure of the 320 MW gas turbine of the Huntorf air-storage gas turbine power plant which took place in 2009 during test runs as part of the re-commissioning work. This gas turbine with sequential combustion is a tailor-made design to the particular needs of this unique power plant. Shortcomings in the design of individual sub-systems and components that were not discovered before and their interaction caused a considerable failure of the turbine due to significant overheating of the high pressure turbine.

The revised VGB Guidelines for condenser tubes from copper alloys, stainless steels and titanium

Hans-Günter Seipp and Frank Udo Leidich

At the end of the 1970s application-related codes for material and semi-finished goods have been terminated in the German codes, therefore VGB took initiative to set-up the first revision of the guidelines for condenser tubes, especially suited for power plant application. Substantial transfer of requirements from the old German codes to the European Standards was a basic request and motivation for the revision. The guidelines for the three material families (copper alloys, stainless steels, titanium), that have been set-up almost independently, are now attuned to a maximum and strongly referenced to other relevant VGB guidelines, like the coming new guideline for cooling systems. The need of users for further explanations is satisfied by assignment to cited codes as well as by literature references including their abstracts, which is firstly used here. This might help users to decide more economically for literature relevant for a specific field of interest. Finally a table with likewise sorted materials opens and expands the possibilities for global sourcing of tubes.