Conventional Steam Power Plant Research Articles

Materials for high performance light water reactors

A state-of-the-art study was performed to investigate the operational conditions for in-core and out-of-core materials in a high performance light water reactor (HPLWR) and to evaluate the potential of existing structural materials for application in fuel elements, core structures and out-of-core components. In the conventional parts of a HPLWR-plant the approved materials of supercritical fossil power plants (SCFPP) can be used for given temperatures (⩽600 °C) and pressures (≈250 bar). These are either commercial ferritic/martensitic or austenitic stainless steels. Taking the conditions of existing light water reactors (LWR) into account an assessment of potential cladding materials was made, based on existing creep-rupture data, an extensive analysis of the corrosion in conventional steam power plants and available information on material behaviour under irradiation. As a major result it is shown that for an assumed maximum temperature of 650 °C not only Ni-alloys, but also austenitic stainless steels can be used as cladding materials.

Proposed System for Hydrogen Production from Methane Hydrate with Sequestering of Carbon Dioxide Hydrate

Methane hydrate exists in huge amounts in certain locations, in sea sediments and the geological structures below them, at low temperature and high pressure. Production methods are in development to produce the methane to a floating platform. There it can be reformed to produce hydrogen and carbon dioxide, in an endothermic process. Some of the methane can be burned to provide heat energy to develop all needed power on the platform and to support the reforming process. After separation, the hydrogen is the valuable and transportable product. All carbon dioxide produced on the platform can be separated from other gases and then sequestered in the sea as carbon dioxide hydrate. In this way, hydrogen is made available without the release of carbon dioxide to the atmosphere, and the hydrogen could be an enabling step toward a world hydrogen economy.

Energy aspects in paper mills utilising future technology

Developments in paper machinery have produced or are producing solutions to enhance water removal and improve paper properties. These include impingement drying and impulse technology. However, both methods also use energy in some other form than steam to bring about drying. On paper machines, where a large share of conventional drying is replaced with new technologies, the energy system should be reconstructed to achieve the increased power-to-heat ratio with better efficiency than with the conventional steam power plant. CHP-solutions based on diesel and gas turbine processes were compared against the steam boiler based process to assess their potential for increasing thermal efficiency in combined power and heat production. The calculated results confirm that the efficiency of heat and power production can be significantly increased in the selected cases by utilising either diesel or gas turbine technology.

Repowering — The option to improve the economy of aging steam power plants

The electrical power producing market has changed dramatically in the last few years. In order to meet the new requirements of the electricity producing market, ABB is proud to be able to present a repowering concept as a cost effective solution for the market which allows the power plant owners to extend the lifetime of their existing steam power plants by using the installed assets. The ABB repowering conceept takes advantage of ABB’s heavy duty gas turbines, and in particular of the sequential combustion gas turbines GT 24/GT 26. The repowering solutions, with their unique design, operation and dispatching flexibility, provide the owner with the benefits of competitive power generation: the owner can optimize the plant fuel and O & M costs, increase the availability, extend economic life and lower the environmental impact of the power plant. This paper describes the feasibility of combining conventional steam power plants with gas turbine technology and recommends the ABB repowering concept as one of the competitive alternatives for power generation, especially for the re-evaluation of existing assets and positioning in the competitive environment.

98/02246 Fireside corrosion testing of candidate superheater tube alloys, coatings, and claddings—Phase II

A state-of-the-art study was performed to investigate the operational conditions for in-core and out-of-core materials in a high performance light water reactor (HPLWR) and to evaluate the potential of existing structural materials for application in fuel elements, core structures and out-of-core components. In the conventional parts of a HPLWR-plant the approved materials of supercritical fossil power plants (SCFPP) can be used for given temperatures (⩽600 °C) and pressures (≈250 bar). These are either commercial ferritic/martensitic or austenitic stainless steels. Taking the conditions of existing light water reactors (LWR) into account an assessment of potential cladding materials was made, based on existing creep-rupture data, an extensive analysis of the corrosion in conventional steam power plants and available information on material behaviour under irradiation. As a major result it is shown that for an assumed maximum temperature of 650 °C not only Ni-alloys, but also austenitic stainless steels can be used as cladding materials.

Study of possible optimisation criteria for geothermal power plants

The possibility of exploiting low temperature liquid-dominated geothermal sources can considerably increase the use of this kind of renewable energy. Improvements in the performance of geothermal cycles are possible by using closed Rankine and Kalina cycles, whose working fluid may be a pure substance or a two-component mixture. In this paper three configurations of the Rankine cycle are examined and compared to conventional single and dual flash steam power plants. The Kalina cycle system no. 12 has also been studied. Results showed that there is a potential for optimisation of the performance, by modifying the main parameters, such as turbine inlet pressure and type of fluid.

Modelling and Simulation of Thermal Stress Dynamics in a Steam Generator

Enormous price increases and limited reserves of fossil fuels have resulted in increased use of nuclear power plants for the base load of electricity supply. Consequently, conventional steam power plants have been used in variable and peak load ranges in the dailly load curves of electricity neneration. Economical control of non-stationary operations (start-up, shut-down, fast and large load changes) is possible only by approachinn and maintaining the maximum allowable material stresses at the critical points of power plants. These points occur during the steam generator operation, on the inside surface of the insulated thick wall components containing high temperature and hinh pressure steam. The rate of load change of a steam generator is mainly limited by thermal stresses occuring in the thick wall elements in which the working fluid flows. The appropriate design and effective application of a new control system for the nonstationary operating conditions require knowledqe of the dynamic behaviour of the thermal stresses at the critical points in the system. Thermal stress dynamics in steam generator components depend on the dynamics of the working fluid as well as on the design data of the component concerned. Extension of the working fluid dynamics to the thermal stress dynamics in steam generators is investigated in this study. The study comprises modeling and simulation of working fluid dynamics and their extension to thermal stress dynamics of an actual once-through steam generator. The mathematical model developed for the thermal stress dynamics can be used for developing and optimization of new control and measurement systems used for the control of power plants under nonstationary operating conditions.

Dynamic behaviour of material states in steam power plant control

The enormous price increase in petroleum and the limited reserves of other fossil fuels have resulted in the increased use of nuclear power plants for the basic load of electricity supply. Consequently, conventional steam power plants have been used to meet the variable and peak loads in electricity generation. The control of fast and large load changes is becoming more and more important for conventional power plant operations. An economical control of the nonstationary operation (start-up, shut-down and large load changes) is possible only by approaching and maintaining the maximum allowable values of the material state variables (temperature θ, strain ϵ and stress σ) at the critical points of the power plant components. To achieve this primary control goal, the dynamic behaviour of material states must be well understood. A direct measurement of the changes in material states especially due to thermal stresses, caused by temperature gradients, is not possible. The material states can be calculated, however, by means of mathematical models describing the nonstationary temperature distribution. The working fluid temperature, pressure and mass flow rate are the input variables for these mathematical models. This paper presents a linear mathematical model for the investigation of the dynamic behaviour of material states. Another mathematical model is also developed for calculating the thermal stresses for large temperature and load changes. Thus, the steam generator models so far describing only the states of the working fluid can be extended to the material states. The basic idea is demonstrated for an insulated thick wall tube containing a working fluid. The simulation of the mathematical models is performed.

Investigation of the Dynamic Behaviour of Material States in Steam Power Plant Control

The enormous price increase in petroleum and the limited reserves of other fossil fuels have resulted in the increased use of nuclear power plants for the basic load of electricity supply. Consequently, conventional steam power plants have been used to meet the variable and peak loads in electricity generation. The control of fast and large load changes is becoming more and more important for conventional power plant operations. An economical control of the nonstationary operation (start-up, shut-down, and large load changes) is possible only by approaching and maintaining the maximum allowable values of the material state variables (temperature θ, strain ε, and stress σ) at the critical points of the power plant components. To achieve this primary control goal, the dynamic behaviour of material states must be well understood. A direct measurement of the changes in material states especially due to thermal stresses, caused by temperature gradients, is not possible. The material states can be calculated, however, by means of mathematical models describing the nonstationary temperature distribution. The working fluid temperature, pressure and mass flow rate are the input variables for these mathematical models. This paper presents a linear mathematical model for the investigation of the dynamic behaviour of material states. Another mathematical model is also developed for calculating the thermal stresses for large temperature and load changes. Thus, the steam generator models so far describing only the states of the working fluid can be extended to the material states. The basic idea is demonstrated for an insulated thick wall tube containing a working fluid. The simulation of the mathematical models is performed. It is shown that these mathematical models are useful for studying the economic guidance of nonstationary steam gnerator operation, as well as for selecting the best locations of the temperature measurement to determine the thermal stresses.