Abstracts - VGB PowerTech Journal 11/2004

Quality Assurance Concepts of Power Plants with Imported Coals

P. Struckmann, H. Prenzel, U. Wehmeyer and Th. Schäfer

The use of imported coal in German power plants has been considered common practise for more than ten years. The process of coal procurement has not changed much during this time. Frequently the combustion of "pure types of coal" is not feasible. The imported coals have to be fed into the furnace as blends.

The New HE Product Line - A Compact Steam Turbine for Highest Efficiency Levels in Combined-Cycle Power Plants

E.-W. Pfitzinger, M.-A. Schwarz and F. Hiss

Siemens has especially tailored the newly developed components of the HE steam turbine product line for deployment in advanced combined-cycle power plants in single-shaft configuration, and, in doing so, placed particular emphasis on fulfilment of the key market requirements: high availability, operational flexibility, low life-cycle costs, and short production and installation times. The article presents the basic concept behind the product line and explains selected features and strengths of the new design.

Highly Efficient Steam Turbine Technology for Fossil-Fuel Power Plants in Economically and Ecologically Driven Markets

A. Tremmel and D. Hartmann

Nowadays more and more high-temperature power plants are being planned and engineered in Europe and Germany today. In addition to the economical gas-fired combined-cycle power plants, European utilities nowadays also place their focus back on supercritical lignite-fired and hard-coal-fired steam power plants running at high efficiency levels and ensuring the usage of a wide fuel spectrum in the German power plant fleet. Relevant aspects of steam turbine technology, the potential of thermodynamic improvement and an optimized choice of materials, as well as the issue of CO2 reduction through the use of advanced high-temperature power plant applications are covered.

A New On-site Cleaning Procedure for Higher Efficiency of Steam Turbines

R. Bröske, Th. Hoppe, H. Ohme, C. Topp and M. Mümken

A new procedure for an efficient and sparing cleaning procedure of turbines was developed. The procedure uses cleaning and passivation chemicals that solve effectively and homogeneously salt and ferrous oxide coatings from turbines, avoiding attacks from corrosion, plugging and unbalances. In several high-pressure and condensation turbines the cleaning procedure has been already put into practice.

Hamborn CHP Station - Modern Combustion Technology for Blast-furnace, Coke-oven and Natural Gas

Ch. Götte, W. Sticher and K. Pflipsen

The new combined heat and power station in Duisburg-Hamborn is designed to burn blast-furnace gas from the Thyssen-Krupp-Stahl AG (TKS) pig-iron plant at Duisburg, along with coke-oven gas from the new coke-works in Duisburg-Schwelgern. The main fuels are blast-furnace gas and coke-oven gas, though natural gas can also be used for ignition and back-up. The report describes the combustion concept, the heat displacement system and DeNOx plant and initial operating results.

Elsam's Experience with Co-firing of Straw with Coal and Natural Gas

C. Ramsgaard-Nielsen

In 1993 the Danish Parliament decided to reduce the coal consumption at the central power plants by utilising 1.2 million tonnes of straw and 0.2 million tonnes of wood per year from the year 2000. Based on this decision Elsam converted the coal-fired Studstrup Unit 1 into co-firing of coal and straw for technology demonstration purposes in 1995. In 2000 it was decided to convert the coal-fired Studstrup Unit 4 into co- firing of coal and straw based on a new 10-year support mechanism decided by the Parliament.

Biomass gasification for CHP applications in a medium power range - process description and economic evaluation

M. Ising

A concept for highly efficient bioenergy plants based on gasification and IC-engine modules has been developed and successfully tested by Fraunhofer UMSICHT at a 0.5 MW-pilot-scale plant since 1994. The process is considered to be profitable for industrial heat and power production in the range of 5 to 20 MW fuel input capacity. A technical description of the process and its main features are given. Economic prospects of the concept are promising as it appears to be competitive compared with conventional technologies.

Modification of the Firing System at Bexbach Power Station - Experience and Development

A. Meiser and H. Brüggemann

The firing system of the Bexbach power plant located in the Saarland was modified with the aim of improving the steam generator efficiency, thus increasing the economic efficiency. At the same time, the fuel savings made an important contribution towards environmental protection. An unexpected evaporator damage occurred after the operating period of two years. In addition to the process-related objectives cause-and-effect analysis are presented.

Recladding of Tube Walls in the Waste to Energy Plant at Burgkirchen

L. Englmaier and Th. Herzog

Recladding of thinned claddings on boiler walls is more cost-effective and can be performed in less time (less down time) than an exchange of tube walls at the waste to energy plant at Burgkirchen. The extent of repairs of recladding tube walls is lower in comparison to cladded tube walls.

Investigations into the Composition of the Early Condensate in Steam (VGB Research Project Nr.182)

R. Svoboda, H Pflug, Th. Warneke and M. Koebel

Concentration effects in the first condensate can lead to a corrosive environment in steam turbines. This paper reports on investigations using an "Early Condensate sampler" to simulate first condensation. Superheat steam is taken from a suitable turbine extraction and subsequently partly condensed by appropriate cooling. The water phase can then be sampled and analysed. Based on this work it is e.g. possible to ship ultrapure water samples from anywhere in the world to a given analytical laboratory, confident that a measurement will yield a representative result of its ionic contents.

Numerical and Experimental Investigation of the Wetness in the Front Stages of a Low-pressure Steam Turbine

D. E. Bohn, J. Funcke, J. Ren, N. Sürken, M. Sell and Th. Osterhage

In order to achieve a significant increase of the total efficiency of the power stations, all incorporated groups included in the process should be optimized, in which the steam turbine is a key component with a central influence on the most power station's processes. Especially in the low-pressure steam turbines, considerable losses arise after crossing the saturation line due to thermodynamic and kinematic relaxation processes. The optimization potential of reducing the so called relaxation losses is considerable. The attained knowledge makes it possible to have a better understanding concerning the physical phenomenon for the nucleation and the distribution of the wetness in the real machines.

Analysis of Possible Occurrence of Flow Instability in a Once-through Steam Boiler

K. Wojs and P. Szulc

This work presents the theoretical and experimental results of research upon a flow of the mixture of water and steam water. The experiments were performed in the model of an evaporator and in the real evaporator of a once-through steam boiler BP-1150. The measurement results and the computer simulations show that the two-phase flow instability occurred both in the evaporator model and in the real steam boiler evaporator.