Abstracts - VGB PowerTech Journal 6/2013
Biomass logistics and sustainability criteria for large-scale power generation in Europe
Emmanouil Karampinis, Panagiotis Grammelis and Emmanuel Kakaras
Biomass co-firing and, lately, dedicated biomass combustion in large-scale power plants is considered as one of the easily deployed ways for mitigating CO2 emissions from the power sector. Due to the large thermal capacity of most coal-fired power plants, the adoption of co-firing, even at relatively low thermal shares, requires the organisation of a biomass supply chain for large bulk quantities; in some cases the supply chain may even span the globe. The organisation of such a supply chain requires extensive planning and organisation involving all parties: plant operators, fuel suppliers, and policy makers. The increased utilisation of biomass in the power sector has also raised concern among several groups regarding sustainability issues.
Technical specifications and sustainability criteria for the trade of solid biomass for power generation
Yves Ryckmans
The Initiative Wood Pellets Buyers (IWPB) was set up in 2010 in order to harmonise the trade between large users of wood pellets through the creation of one common contract by taking into account quality specifications and sustainability principles which were mainly developed by Laborelec. The final common contract form was put under the European Federation of Energy Traders (EFET) in June 2012. Since then the IWPB is to develop a joint system for evidencing sustainability of solid biomass.
RDF co-firing demonstration project at the Enel Fusina power plant
Silvia Gasperetti, Paolo Leoni, Nicola Rossi, Angelo di Giovanni, Fausto Bassi, Stefano Pavanetto, Vincenzo Fantini and Angelo Cavaliere
ENEL carried out demonstration activities at the Fusina power plant aimed at proving the feasibility of RDF (Refuse Derived Fuel)/coal co-firing. Since 2004, smaller amounts of RDF have been co-fired with coal in two 320 MWe boilers. Since February 2009, the average RDF share has been increased up to 5 % on thermal input for each unit at full load. Between 2008 to 2012, the Fusina power plant was involved in the EU-funded DEBCO (Demonstration of Biomass Co-firing) project, which focused on the demonstration of large-scale biomass or RDF co-firing and supply chain integration.
Combustion behaviour and deposition characteristics of cynara cardunculus/Greek lignite co-firing under various thermal shares in a thermal pilot-scale facility
Aaron D. Fuller, Jörg Maier, Halina Kruczek, Emmanouil Karampinis, Günter Scheffknecht, Panagiotis Grammelis and Emmanuel Kakaras
The combustion of herbaceous biomass in industrial boilers, either as co-firing fuel or in dedicated combustion units, possess significant operating challenges due to increased risks for corrosion and slagging/fouling. The present work aims at investigating the combustion behaviour of Cynara Cardunculus (cardoon) in a range of thermal shares (0 to 100 %) with a Greek lignite. Combustion tests were performed in a 0.5 MW thermal input pulverised fuel pilot-scale test facility. Deposits were characterised in terms of morphological and ash fusion behaviour, and slagging/fouling tendencies were determined.
Fouling tendency and ash deposition evaluations in large-scale pulverised fuel power plants
Jana Kalivodova, Aaron D. Fuller, Emmanouil Karampinis, Michiel Carbo, Jörg Maier, S Lattanzi and Patrick Savat
Biomass for heat and power generation holds a large potential as renewable source of energy and for reducing greenhouse gas emission. However, this may result in altering the combustion conditions and ash behaviour, which could lead to an increase in slagging/fouling of the heat exchange surfaces. The objective of this study was to focus on the boiler performance monitoring in three large-scale demonstration plants in order to assess ash deposition, fouling, and burn-out under co-firing operating condition at different biomass shares. The results proved that the characterisation methodology can provide valuable information related to fouling and ash deposition monitoring in large-scale power plant boilers.
Change of the ash melting behaviour of biomass-mix-pellets by addition of kaolin
Uta Kappler, Volker Wenghoefer and Ralf Pude
In the last few years, the design of solid biofuels for small combustion plants < 50 kW has become an important topic of biomass research. The European Union, for example, is sponsoring the European ”MixBioPells” project that is mainly supported by the German Biomass Research Center (DBFZ) in Leipzig. From 2010 until late 2012, the Agency of Renewable Resources (FNR) sponsored the “C4-Kompakt“ project in Germany. The aim of the project, which was executed by the University of Bonn/Center for Renewable Resources, was the development of mixed pellets with a minimum miscanthus content of 50%wt. First combustion tests showed increased fouling and slagging of pellet combustion. This problem, however, can be overcome by deliberate adding of inorganic additives (kaolin).
The ChlorOut concept - A method to reduce alkali-related problems during combustion
Hakan Kassman, Lothar Wollner and Magnus Berg
Combustion of biomass with a high content of alkali and chlorine (Cl) can result in operational problems including deposit formation and superheater corrosion. The strategies applied to reduce such problems include co-combustion and the use of additives. Ammonium sulphate is a part of the ChlorOut concept which is applied in a range of commercial boilers. This concept is based on dosing of sulphate-containing additives to the flue gases and a unique measurement device for on-line measurement of gaseous alkali chlorides called IACM (in-situ alkali chloride monitor). The focus of the present paper is on evaluation of long-term experiences from two full-scale boilers. The operational problems with deposit formation and superheater corrosion decreased in these boilers after installing the ChlorOut concept.
Optimisation and process control of steam and cooling cycles by use of online TOC analytics
Jens-Uwe Schröter
Online monitoring of organic pollution is of great importance in processes with steam, condensate and boiler feedwater due to the influence of impurities on corrosion as well as the formation of biofilms, and deposits. Today, the recommended TOC limit value is set between 0.1 to 0.2 mg/l C. Plants can be optimised when monitoring the TOC values. Only some online- OC analysers that are available on the market meet the measurement requirements.
Corrosivity of flue gas: Online sensors in steam generators
Gabriele Magel, Wolfgang Müller, Wolfgang Spiegel, Werner Schmidl, Thomas Herzog and Hans-Peter Aleßio
Steam generators have to be regarded as chemical reactors to understand the causes of corrosion. As for the complex situation in an incineration plant in terms of basic conditions, firing, and chemical processes, the ongoing phenomena can be recorded reliably only during operation by special sensors and probes. In the paper several possibilities of online sensors are outlined to determine the processes and causes of corrosion and fouling during operation. Against the background of increasing co-combustion of new fuels, it is also sensible to assess their fouling and corrosion potential as well as damage behaviour.
Field test of carbon dioxide removal from flue gasses using polymer membranes
Ludwin Daal, Linda Claassen, Ralf Bruns, Bernd Schallert, Giuseppe Barbieri, Adele Brunetti and Kitty Nijmeijer
For the capture of CO2 from flue gas, asymmetric hollow fibre poly phenylene oxide membranes are coated with sulphonated polyether etherketon. The membranes were integrated in an open and closed module and tested. The test results are presented. Since they are very promising, additional research is going to be supported in order to use the modules in a larger scale and over a longer period of time.
Simulation of the reacting fuel bed on grates in waste incineration plants
Siegmar Wirtz, Florian Sudbrock, Björn Brosch and Viktor Scherer
For the design and optimisation of utility boilers, numerical simulations have become a valuable tool to complement or even to replace experimental investigations. However, only strongly simplified numerical models exist for the simulation of the firing equipment for lumpy solids fuels like biomass or municipal waste. The objective of the work presented is to demonstrate the application of a three-dimensional, particle-based numerical tool, which allows a well-founded simulation of moving and reacting fuel beds in grate firing systems tightly coupled with the three-dimensional simulation of the furnace.
Control and safety instrumented system as a joint solution for safe operation of a power plant
Sven Lohmann, Kai Henkel and Franz Jörling
The priority of renewables over other forms of energy results in market conditions that require frequent load changes, steep power gradients and frequent start-up and shutdown procedures of the remaining control capacity of fossil-fuelled power plants. In short, the operation of a coal-fired power plant has never been more challenging. Meeting these new challenges requires the integration of different systems used to operate the plant. The paper illustrates a concept for improved operation and control using the Wilhelmshaven utility power plant as an example.
Varnish in turbine oils
Ralf Ertelt and Andreas Busch
Varnish in turbine oil can lead to hydraulic malfunctions and to increased bearing temperatures. The consequences are unplanned downtimes and high costs. Varnishes are oil aging products that form gel- or resin-like deposits or solid varnish-like deposits in the fluid system. The cause of these deposits is among other things the limited capacity for the dissolution of varnish in modern turbine oils. Furthermore, these oils also have low electrical conductivity, which causes electrostatic discharges in the system. This results in accelerated oil aging, and damage to sensors and filter elements. Early recognition of the risk of deposits and the use of adapted fluid care will increase the safety of operations and reduce operating costs.