Abstracts - VGB PowerTech Journal 7/2015

Experience with dry lignite-fired unit Kof Niederaußem power plant

Rainer Hesse, Bernhard Röper and Daniel Sommer

In 2009, RWE Power erected an industrial-scale prototype plant for drying lignite and since then RWE has been operating the plant at the Niederaußem site. The design is based on fluidised bed drying with internal waste heat recovery and is a 1 : 1 scale prototype. It is connected to the adjacent 1,000 MW unit K in order to substitute up to a maximum of 25 % of raw lignite. A report is given on operating behaviour with dry lignite firing.

Operation results with flow optimised ESPs at the Gemeinschaftskraftwerk Hannover GmbH

Karl Burmann and Dieter Neumann

In the power plant Gemeinschaftskraftwerk Hannover GmbH, electrostatic precipitators (ESP) from Lurgi are used in two units. The ESPs are located directly behind the FGD (flue gas desulphurisation, niro atomiser) and connected to the FGD outlet by a short horizontal duct. Because of the very high flow velocity in this duct, the flow pattern in the ESP is very much determined by a velocity peak in the middle of the duct. This velocity peak creates heavy wear at the gas distribution walls. In the outer area of the cross section heavy deposits were found, which adversely affect function and power consumption of the ESP. Based on computational fluid dynamics (CFD) the plant was optimised and a new flow control concept was developed to distribute both the flue gases and the dust particles substantially homogeneously across the filter cross-section. After some months of operation, the new design could prove that both the deposits and wear were almost completely eliminated

Electrostatic sensors on a lignite-fired boiler for continuously monitoring distribution and velocity of pulverised coal

Igor Kustrin und Joze Lenart

This study deals with the industrial application of a measurement system consisting of a grid of intrusive electrostatic sensors. The system is installed on a lignite-fired steam boiler with a thermal output of 1,100 MW and its primary use is to continuously monitor distribution and velocity of pulverised coal inside the ducts connecting coal mills and burner nozzles. In this way, boiler operators and control system can take appropriate actions to either redistribute pulverised coal or adjust fresh-air distribution, according to the measured distribution of pulverized coal thus optimising combustion.

Spray absorber or cooling tower – A component to distress

Rudi Karpf, Yannick Conrad und Rüdiger Siebert

In a typical waste-to-energy plant, acid gas emission is controlled by a spray dry absorber (SDA) or by a dry sorbent injection system using hydrated lime as scrubbing reagent. In SDAs, hydrated lime is injected into flue gas as lime slurry. Different requirements have to be met by the injection of liquid/suspension and system dimensioning. One example, which is discussed in detail, is the experience made with the retrofit, i.e. converting an SDA into a DSI system at the Wuppertal waste incineration plant.

Increase process safety by current data and information management in waste incineration plants

Hans Karl Preuss and Erich Böhm

Waste incineration plants and power stations face challenges like less staff and steadily increasing documentation requirements as regards data and information management. It is not only about conserving the manufacturer/handover documentation from existing information in detail, but also the preservation and validation of knowledge within the company. With the development of software technology information and data can be structured and can be made available.

Condition monitoring of wind turbines: State of the art, user experience and recommendations – VGB Research Project 383

Katharina Fischer and Diego Coronade

Condition monitoring of technical assets aims at detecting developing faults at an early stage. Condition-monitoring systems (CMS), in case of structural components also termed structural-health monitoring (SHM) systems, are therefore facilitators for implementing a condition-based preventive maintenance strategy, which allows optimal utilisation of component lifetime while avoiding unforeseen failures and costly advanced-stage damages. The by far most developed and widely applied condition-monitoring technique for wind turbines is vibration-based monitoring of the drivetrain components. Gearbox-oil based CMS, rotor-blade SHM and condition monitoring of support structures are partly still being developed.

Field experience with advanced condition monitoring of wind turbines

Olivier le Fevere de ten Hove

Condition monitoring for wind turbines must combine early warning of deviating operating behaviour, reliable fault detection, accurate fault diagnosis and the ability to handle versatile data inputs, and all this at an economically acceptable cost. Pattern recognition and intelligent data mining are a way forward to transfer the large amount of data that is continuously generated by a wind farm into actionable information, assisting the wind farm operator in the optimisation of the operation and maintenance process and in the assessment of the impact of events and actions on the remaining lifetime of the assets.

Rotor hub: Potential for improvementsNew battery management optimises wind turbine output, battery lifecycle and working capital

Heiko Jungermann and Ingo Wahlers

One of the most important functions of a pitch system is to ensure that the rotor blades of a wind turbine can be immediately set to feather position in the event of an emergency stop situation. This safety function must be fully functional, even if no mains power is available to drive the pitch motors. For this reason, many wind turbines with electrical pitch systems are fitted with re-chargeable batteries, able to deliver the necessary energy supply needed for rapid turbine shutdown at any time. An effective battery management strategy can considerably lengthen the life cycle of rechargeable batteries and increase the economic efficiency of wind power plants.

Assembling of the new bearing generation of the FL 2500

Jan Philipp Krämer and Walter Sucrow

The technical design of the FL2500 wind turbine is affected by the main bearing as a central component within the powertrain. In one of the highest wind farms in Europe, in central Bulgaria, 29 wind turbines of this type are being operated. Two turbines of this wind farm had technical problems at the main bearing. The maintenance provider developed the technical concept for the unscheduled maintenance, supported the technical adjustment between turbine developer, manufacturer of the bearing and operator and took over the responsibility for quality management.

Torrefied biomass: The perfect CO₂ neutral coal substitute is maturing

Michael Wild

Biomass upgrading to a coal-like fuel is long a topic of R&D. Today, the torrefaction technology is mature allowing industrial-scale production and cost competitive large-scale supply of CO₂ neutral fuel. Torrefaction exposes lingo-cellulosic biomass to 250 to 350 °C. Approximately 30 % increase in energy density, improved combustion particulars, 1/10 of milling energy requirement and improved water resistance are achieved results. Various torrefaction technologies are available. Pelleting or briquetting is obligatory for torrefied product transport. Numerous plants of app 1t/h are in operation; industrial-scale torrefaction lines are under construction.

Anaerobic digestion of lawn

Saskia Oldenburg, Ole Heins and Kerstin Kuchta

The energetic utilisation of lawn requires detailed analysis of biomass to determine its characteristics and energetic potential. Biomass yield and the potentials of lawn were determined. According to literature, the most important factors determining lawn are its use, care and lawn age. Biogas potentials from two test series amount to 340 to 700 l/kg dry substance. The results are well in line with known data from literature. The test results obtained are important factors which explain the yield of biomass and biogas potential.

EnNa – A project for sustainable harvesting wooden biomass

Klaus von Wilpert, Christian Vonderach and Dietmar Zirlewagen

Currently the demand in biomass harvest increases. Nutrient export will be predominantly high for fuel-wood harvest. Thus, sustainability becomes a crucial question. However, nutrient export with harvest is not the only threat for nutrient sustainability. The results of a study in Baden-Württemberg in SW-Germany with 1.4 m ha forests as part of the German-wide EnNa project will be presented. The study revealed that under given environmental conditions even the comparably low nutrient export with timber harvest contributes to further deterioration of the soil quality.

Biomass silo fire fighting

Thomas Wündrich and Jörg Kayser

Fires in bulk material stored in silos or bunkers are a very rare fire scenario compared to the mass of fire incidents in Germany. Under special circumstances, silo and/or bunker fires can cause long-lasting fire fighting actions of days or even weeks. Depending on the interactions of the affected facility with associated processes, significant adverse effects can occur in the operating procedure. In this paper, preventive measures will be described as well as intervention actions and experiences from previous silo fire events.