Abstracts - VGB PowerTech Journal 11/2011

ZEP cost report on CO2 capture, transport and storage

Lars Strömberg and Heinz Bergmann

The companies, scientists and NGOs that together make up the Zero Emissions Platform ZEP have undertaken a groundbreaking study into the costs of CO2 Capture, Transport and Storage (CCS) based on new data provided exclusively by ZEP’s member organisations on existing pilot and planned demonstration projects. Based on optimised cost estimations for full-size CCS power plants, start-up mid 2020s, base-load operation, middle fuel costs, 180 km onshore CO2 transport and medium storage costs for an onshore saline aquifer (SA), the break-even-point compared to power plants without CCS is expected at a CO2 price level of about 35 €/t CO2 for coal and 90 €/t CO2 for natural gas.

Solar thermal power plants - Hybrid and stand alone solutions

Christoph Guder and Dirk-Uwe Neumann

CSP (Concentrating Solar Power) technology will contribute to the utilisation of renewable energies for electricity generation. In the course of this, both CSP hybrid- and stand alone solutions will play a role. Stand alone CSP power plants have the advantage of allowing a free choice of site according to direct normal irradiation, land availability and land quality. Without a storage system, electricity generation is directly dependent on current direct normal irradiation. Even with a storage system, continuous electricity generation cannot be guaranteed. CSP hybrid solutions, consisting of CSP equipment and fossil-fired power plants, allow predictable operation. By the joint use of the highly efficient power plant components, the solar levelised electricity costs can be reduced significantly.

T24: Experiences from a power plant operators‘ view related to RWE projects

Ralf Nowack

As a result of changing market demands for greater efficiency and flexibility in power stations, plant operators are faced with one of their biggest challenges of recent decades. Particular attention is required in choosing suitable materials for performing much more efficiently, while maintaining flexibility. RWE Technology has made prompt organisational adjustments to meet this challenge by making the executive management of the company directly responsible for quality management in order to tackle quality-related issues with a structured approach to quality planning, assurance and monitoring. This is illustrated in the paper based on the quality deficiencies in connection with the T24 diaphragm pipe material which is currently used in the hard coal- and lignite-fired power plants being erected in Europe.

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Steam-side oxidation behaviour of austenitic boiler tubes

Gereon Lüdenbach and Peter Körner

Austenitic chromium nickel steels will be used for boiler tubes (superheater and reheater tubes) to realise higher steam parameters because these steels display high creep rupture strength as well as good resistance against steam-side oxidation. However, steam-side problems occurred at tubes that had been initially employed. These tubes had to be replaced by tubes made of modified material. Positive results have been obtained in first operating phases and research projects. Further laboratory tests are recommended as well as regular checks at operation exposed tube bundles.   

Requirements on structural maintenance in power plants

Dieter Lehnen and Martin Demmer

Measures of structural maintenance frequently are not taken until damage has occurred which affects power plant operation. This kind of disruptions can be avoided by predictive structural maintenance to the greatest possible extend. Because of the great importance in terms of safety and economics, requirements on structural maintenance are presented as well as main features of life-cycle management.

Inspection of a boiler assembly prior to commissioning - Current experiences of an accredited inspection body (ZÜS)

Uwe Rechtien, Michael Schuknecht and Gerhard Dreier

The inspections according to § 14 of the German plant safety ordinance (Betriebssicherheitsverordnung) to be performed by an accredited inspection body (ZÜS) are an important milestone within the commissioning phase of a power plant. In the commissioning phase of unit D of the Lingen CCGT plant, the corresponding actions of the manufacturer with its notified body on the one hand and the plant operator with its ZÜS on the other hand were in interaction. The relevant interfaces and scopes of work have been defined through early coordination.

Sumitomo’s R&D activities for advanced USC boilers

Hidenori Ogawa, Hirokazu Okada, Hiroyuki Hirata, Hiroyuki Semba, Masaaki Igarashi and Hiroshi Matsuo

Advanced Ni-base super alloys are strongly required for the advanced ultra-super critical (A-USC) power plants operated at steam temperatures above 700 °C. The developed Ni base alloy HR6W with 23Cr-45Ni-7W, which is strengthened by Fe2W-type Laves phase and M23C6, is one of the candidate materials for thick wall pipe application. The stability of long-term creep strength and superior creep rupture ductility have been proved by creep rupture tests. A newly developed Ni-base alloy HR35 with 30r-50Ni-W alloy has been also proposed for thick wall piping application.

V&M’s innovative contribution to the challenges of present and future conventional power plants

Alain Dieulin, Carine Lanier, Marco Subanovic, Vida Knezevic, Emmanuel Cini and Andre Schneider

Vallourec & Mannesmann Tubes (V&M) is dedicating important R&D and industrial efforts for developing ferritic and austenitic steels for the future power plants. The improvement of ferritic steels is illustrated by the example of VM12-SHC, a new 12 % Cr ferritic/martensitic grade presenting good creep properties and excellent oxidation resistance. New routes for future improvements of ferritic/martensitic grades are identified. New technologies developed by V&M for alloy and steel design are presented as accelerators for development cycles.

System solution in valve component maintenance and redesign

Meik Brinkmann

Power station overhauls are usually run to a tight schedule. This is why repair processes have to be short and spare parts sourced very quickly. Moreover, advances in power station design require new technologies and materials to be used. For low- and high-pressure valves such as block valves, control valves and safety valves, this may lead to long delivery times and high costs if a particular component is not in stock. Control valves tend to be custom-made components designed and built for a particular application. New materials, if required with additional surface treatment to improve wear characteristics, are to be used when new valves have to be manufactured.

The effectiveness of blade superalloy reheat treatment

Mike Wood

The effect of multiple thermal degradation and reheat treatment cycles on the stress rupture properties of the nickel based superalloy IN738 has been determined. These treatments simulate normal degradation in blades in service and typical commercial refurbishment practices. Whilst reheat treatment did bring about property recovery, the effect was not long lasting: the properties of material which had only been degraded, and material which had been reheat treated and degraded, were indistinguishable. The long-term durability of the property recovery has been discussed with reference to the stability and nature of the reformed microstructure. The implications for life extension of blades and the development of modified reheat treatment schedules are also reviewed.

Life cycle cost reduction through high efficiency membrane based air intake filters

Helmut Krah

The use of highly efficient, membrane-based air intake filters means that massive savings can be made in the operation of gas turbines: on the one hand, a higher degree of efficiency can be achieved, which leads to lower fuel consumption and better turbine performance, and on the other, maintenance costs can be reduced thanks to the avoidance of erosion and corrosion. EPA (Efficient Particulate Air) filters based on fibreglass have the disadvantage that they exhibit a relatively high differential pressure, and they can frequently only be used by converting the filter house. This is where the tremendous advantage of membrane-based EPA filters comes in. Its core, a micro-porous PTFE membrane with excellent air permeability.

Studies of coal ash sintering in lignite combustion

Markus Neuroth, Thomas Schreck, Ralf Simmat, Georg Nover, Michael Müller, Muhammad Muhammadieh and Bernhard Bonn

In a coordinated action of several specialised laboratories a number of different experimental and calculation methods were employed in order to evaluate the sintering temperature of ash from lignites and lignite blends on identical samples. Some of the tested methods have not been employed so far for this purpose and are not yet optimised for measurement on ash samples. In some cases consistent results were obtained which correspond fairly well with experience from boiler operation.

Registration of coal combustion by-products according to REACh

Hans-Dieter Kehrmann

A huge amount of coal combustion by-products - CCPs - are not waste but commodities to be placed on the market. Substances on their own, in preparations or in products shall not be manufactured in the European Community or placed on the market unless they have been registered according to the REACH Regulations. The paper describes roughly the essential features of the REACH process, in particular pre-registration and the registration of FGD gypsum and ashes from dry and wet bottom boilers. The information according to article 32 of the REACh Regulation can be communicated without safety data sheets down the supply chain.