Abstracts - VGB PowerTech Journal 3/2011

Commissioning of a 350 tonnes lignite unit with an extraction condenser turbine

Peter Herzig

The company "eins Energie in sachsen GmbH & Co. KG" operates three units with 800 MW total thermal output and 220 MW electrical power at the Nord co-generation plant in Chemnitz. The measures aiming at increasing the efficiency comprise a new 100 MW extraction turbine, decrease of flue gas emissions and grouping of control rooms as well as automation of the most important plant processes.

Methodical approach to furnace optimisation of power plants

Tobias Kühnle, Bertram Haas, Thomas Sabel and Martin Käß

The furnace modernisation of coal-fired power plants which focus on the reduction of primary NOx emissions and decreasing the air ratio is an interesting optimisation measure to increase efficiency. Since such measures always change the stoichiometric distribution in the furnace, the risk of operational problems like corrosive wall atmosphere or an increased loss of ignition is high. EnBW Kraftwerke AG has developed an optimisation method based on holistic simulation which allows a detailed and well-founded assessment of the technical risks at an early stage before realising any modification. The hard coal-fired units of the co-generation plant 1 and Rheinhafen-dampfkraftwerk unit 7 are taken as examples to show the optimisation potentials for two existing EnBW plants.

Regulation of combustion performance and process control - Application of pusher-grate firing in industrial process control

Bernhard Beyer and Frank Oellers

In recent years, the demand for transparent and open process control systems, which are also implemented consistently, has emerged more strongly. An increasing specialisation in the individual technical areas is causing process suppliers to assign the automation of their facilities to specialist companies. A special challenge in the process is the provision of information relevant for the partner. A functional interface between the two "worlds" has to be set up. The paper will explain the implementation of successful project management applied in joint projects of Thyssen-Krupp Xervon Energy and Cegelec.

Experience with the retrofit of a 350 t/h steam generator and the performance of furnace modelling tools

Benedetto Risio and Andreas Schultheiß

Unexpectedly high NOx emissions at acceptable CO burnout levels were observed during commissioning of the firing system of Chemnitz Nord B20. Apart from the findings from experimental investigations, the technique of 3D furnace modelling with the RECOM-AIOLOS simulation software was used to identify the relevant mechanisms that led to these increased NOx emissions. This software proved to be a reliable tool for computer-aided optimisation of operation parameters and for the assessment of design changes in the combustion equipment of power stations.

SOFCOM - Self-optimising strategy for control of the combustion process

Jonas Funkquist, Volker Stephan, Erik Schaffernicht, Claus Rosner and Magnus Berg

Continuous variations in coal type, fuel feed and feed distribution between several burners are often responsible for non-optimum combustion in large-scale power plants. Within the scope of the SOFCOM project a self-organising approach was developed for nearly full integration and evaluation of high-speed camera data. The self-organising and adaptive control structure using this extracted information is able to automatically adapt to changes of the combustion process.

Increase of overall combined heat and power (CHP) efficiency through mathematical modelling

Patrick Bangert and Jörg-Andreas Czernitzky

The entire process of a combined heat and power (CHP) coal-fired power plant from coal delivery to electricity and heat generation can be modelled using machine learning methods that generate a single set of equations that describe the entire plant. This model is used to compute the optimal operational point at any moment in time, taking into account the current status of the plant as well as relevant external and internal factors. The criterion for optimality is the overall equipment efficiency over the entire plant. With the aid of the system it is possible to improve efficiency by some percentage. This has been demonstrated in the Reuter-West CHP plant of Vattenfall in Berlin.

Continuous boiler cleaning with explosion generators - The alternative to soot blowers

Christian Steiner, Hans Ruegg and Arno Pajarskas

The explosion generator was recently developed by Explosion Power GmbH. With explosion generators, the boiler is cleaned by pressure waves, which are created by controlled gas explosions of natural gas and oxygen. The experience of 22 months of operation in the WtE plant in Lucerne shows that the cleaning efficiency of the explosion generators is much higher than that of soot blowers. Explosion generators are installed Europe-wide in more than 13 different boiler lines.

Wear and corrosion protection in waste incineration plants with thermal spraying

Wolfgang Satke

Increase in productivity and performance of technical plants and equipment imply of course an inevitable raise of stress at segments and components. Highly-stressed and exposed surfaces have to be protected or modified in such a way to resist the constantly increasing strains. This can be ensured by the procedure of thermal spraying either when producing new parts or in the process of maintenance and repair. The procedure of two-wire-arc-spraying using cored wires will be introduced, which has been successfully implemented in various applications for many years.

Corrosion protection on superheaters of waste to energy plants - Experience with material and application

Werner Schmidl, Thomas Herzog, Gabi Magel, Wolfgang Müller and Wolfgang Spiegel

Corrosion induced by chlorine at high temperatures and corrosion by salt melts sometimes cause severe risk and loss of operational availability in waste- and biomass-fired power plants. This corrosion very often affects the superheater. Due to high maintenance needs, several approaches to anti-corrosion coating have been developed. Nickel-based alloys such as alloy 625 are chosen to be applied as cladding or by thermal spraying. Operation periods have been considerably increased by these methods. But still there are some shortcomings in corrosion protection due to application and/or material.

From Stignæs to Asnæs - DONG Energy's second Chiyoda desulphurisation plant

Jens Peter Christensen, Anders Nimgard Schultz, Bo Schlaegelberger and Ole Skovby

In 2008 DONG Energy decided to purchase and install the second Chiyoda desulphurisation plant at the Asnæs power plant unit 2. The Chiyoda process is based on the "jet bubbling reactor" system where the raw gas is in direct contact with the limestone slurry. The new plant is, of course, with an improved design in several areas based on the experience from the first installation. Commissioning of the installation went very smoothly and the plant has now successfully been in operation for more than 5000 hours fulfilling the emission requirements and producing gypsum in wall board quality.

Installation and operation of flue gas desulphurisation systems for Maritsa East II

Takumi Endo, Kyohito Ohtsubo and Hiroo Inoue

At the Maritsa East 2 power station which is the largest capacity coal-fired power plant in Bulgaria, the flue gas desulphurisation (FGD) system for unit 1 to unit 4 has been installed and commissioned between 2009 and 2010. The contract for the FGD installation has been awarded on full turn-key basis between Maritsa East 2 TPP EAD and MITSUI & CO, LTD in October 2004. The SO2 emissins were reduced by 94 %. The key data of the FGD plant will be presented in the paper.

Technical and economical optimisation potential for FGD plants in coal-fired power stations

Christian Hensel and Hermann Brüggendick

Evonik Steag´s flue gas desulphurisation plants (FGD) are being operated differently in the Ruhr area and Saarland. While the Ruhrgebiet FGDs run with quicklime, the Saar plants use limestone. The higher CO2 emissions caused by quicklime might have to be taken into economic consideration if the lime industry will be involved into the European CO2 emission trading scheme as of 2013. Therefore, it is asked whether it was worth for the Ruhrgebiet plants to switch from quicklime to limestone as sorbent in FGD and whether such a step would be technically feasible.

Multi-scale experiments and simulation tools for optimisation of wet FGD plants

Sören Kiil and Brian Brun Hansen

In the Combustion and Harmful Emission Control (CHEC) group at the Technical University of Denmark, research in flue gas desulphurisation technologies, in particular wet flue gas desulphurisation, has been one of many important activities. One aim of research into flue gas desulphurisation has been to obtain a quantitative understanding of the chemistry and mass transport phenomena taking place in the industrial plants and use of that information in optimisation procedures. The quantitative approach requires experimental facilities at both laboratory and pilot-scale and a continuous development of detailed mathematical models describing the processes. Currently, the influence of oxyfuel combustion on the wet FGD plant performance is also of high priority.