Evaluation of Si Coating on Ferritic Steels by CVD-FBR Technology in Steam Oxidation

2009 ◽  
Vol 289-292 ◽  
pp. 413-420 ◽  
Author(s):  
F.J. Bolívar ◽  
L. Sánchez ◽  
M.P. Hierro ◽  
F.J. Pérez
Keyword(s):  
Power Plants ◽  
Protective Coatings ◽  
Steam Oxidation ◽  
Steam Turbines ◽  
X Ray Diffraction ◽  
Steam Power ◽  
Factors Affecting ◽  
Steam Power Plants ◽  
Temperature And Pressure ◽  
Major Factors

The development of new power generation plants firing fossil fuel is aiming at achieving higher thermal efficiencies of the energy conversion process. The major factors affecting the efficiency of the conventional steam power plants are the temperature and, to a lesser extent, the pressure of the steam entering the turbine. The increased operating temperature and pressure require new materials that have major oxidation resistance. Due to this problem, in the last years numerous studies have been conducted in order to develop new coatings to enhance the resistance of steels with chromium contents between 9 and 12% wt against steam oxidation in order to allow operation of steam turbines at 650 0C. In this study, Si protective coatings were deposited by CVD-FBR on ferritic steel P-91. These type of coatings have shown to be protective at 650 0C under steam for at least 3000 hours of laboratory steam exposure under atmospheric pressure. Morphology and composition of coatings were characterized by different techniques, such as scanning electron microscopy (SEM), electron probe microanalysis, and X-ray diffraction (XRD). The results show a substantial increase of steam oxidation protection afforded by Si coating by CVD-FBR process.

Evaluation of Al-Hf Coating on Ferritic Steels by CVD-FBR Technology in Steam Oxidation

2008 ◽  
Vol 595-598 ◽  
pp. 359-366
Author(s):  
F.J. Bolívar ◽  
L. Sánchez ◽  
M.P. Hierro ◽  
J.A. Trilleros ◽  
F.J. Pérez
Keyword(s):  
Atmospheric Pressure ◽  
Electron Probe ◽  
Ferritic Steel ◽  
Power Plants ◽  
Protective Coatings ◽  
Steam Oxidation ◽  
Ferritic Steels ◽  
Steam Turbines ◽  
Creep Properties ◽  
Good Oxidation Resistance

The steels with chromium contents between 9 and 12%wt are used for power plants with advanced steam conditions. These steels possess good creep properties similar to the 9% Cr steels as well as good creep and good oxidation resistance at temperatures between 500-600°C. In the last years efforts have been made to develop coatings for protection against oxidation in order to allow operation of steam turbines at 650°C. In this study, Al-Hf protective coatings were deposited by CVD-FBR on the ferritic steel HCM-12A followed by a diffusion heat treatment, and were shown to be protective at 650°C under steam for at least 3000 hours of laboratory steam exposure under atmospheric pressure. The morphology and composition of the coatings were characterized by techniques, including scanning electron microscopy (SEM), electron probe microanalysis, and Xray diffraction (XRD). The results showed a substantial increase of steam oxidation protection afforded by Al-Hf coating deposited by the CVD-FBR process.

An analysis of a thermal power plant working on a Rankine cycle: A theoretical investigation

2008 ◽  
Vol 19 (1) ◽  
pp. 77-83 ◽  
Author(s):  
R.K. Kapooria ◽  
S. Kumar ◽  
K.S. Kasana
Keyword(s):  
Power Plant ◽  
Power Plants ◽  
Thermal Power ◽  
Rankine Cycle ◽  
Carnot Cycle ◽  
Steam Power ◽  
Factors Affecting ◽  
Steam Power Plants ◽  
Effi Ciency ◽  
Cycle Efficiency

Today, most of the electricity produced throughout the world is from steam power plants. However, electricity is being produced by some other power generation sources such as hydropower, gas power, bio-gas power, solar cells, etc. One newly devel-oped method of electricity generation is the Magneto hydro dynamic power plant. This paper deals with steam cycles used in power plants. Thermodynamic analysis of the Rankine cycle has been undertaken to enhance the efficiency and reli-ability of steam power plants. The thermodynamic deviations resulting in non-ideal or irreversible func-tioning of various steam power plant components have been identified. A comparative study between the Carnot cycle and Rankine cycle efficiency has been analyzed resulting in the introduction of regen-eration in the Rankine cycle. Factors affecting effi-ciency of the Rankine cycle have been identified and analyzed for improved working of thermal power plants.

Comparative Thermoeconomic Analysis Between Combined Cycle Units Derived From Existing Steam Power Plants and a New Combined Cycle Plant

1998 ◽  
Author(s):  
G. Negri di Montenegro ◽  
A. Peretto ◽  
E. Mantino
Keyword(s):  
Power Plant ◽  
Power Plants ◽  
Pressure Level ◽  
Combined Cycle ◽  
Steam Turbines ◽  
Steam Power ◽  
Steam Power Plants ◽  
Combined Cycle Plant ◽  
Combined Cycles ◽  
The Cost

In this paper, a thermoeconomic analysis is carried out for two and three pressure level combined cycles derived from existing steam power plants. The considered steam power plants are among the most widespread in the Italian territory (70 MW, 160 MW, 320 MW power output). First of all, the gas turbine plants that best match the steam power plants’ requirements are selected among existing units. Subsequently, the thermodynamic analysis for the repowered plants is performed, taking into account the off-design working condition of some components such as, the steam turbines and the condenser. Then, the economic evaluation for the repowered plants is carried out by determining the cost per kWh, the pay back period and the internal rate of return. The analysis permits the most economic choice to be made. The thermoeconomic investigation was also performed for a new combined cycle power plant. The study has revealed that the repowering of the three existing steam power plants in two or three pressure level combined cycle plants is more convenient than building a new combined cycle with higher efficiency. It has also pointed out that the repowering of the 320 MW existing steam power plant in a three pressure level reheat combined cycle plant supplies the lowest cost per kWh among all the other repowered plants analyzed. The revamping and environment effect on the above mentioned existing steam power plants was also investigated and it resulted that this solution has a cost per kWh that is much higher than that of the repowered steam plants and the new combined cycle.

Influence of a Synchronized Self-Shifting Clutch in a Single-Shaft Plant on the Torsional Behaviour of the Shaft Train in Case of Electrical Faults

2001 ◽  
Author(s):  
Meinolf Klocke ◽  
Stefan Verstege
Keyword(s):  
Power Plants ◽  
Torsional Stiffness ◽  
Steam Turbines ◽  
Steam Power ◽  
Steam Power Plants ◽  
Electrical Faults ◽  
Engagement And Disengagement

Abstract Synchro-self-shifting clutches allow the construction of combined gas- and steam power plants as single-shaft systems, which are economically advantageous due to enhanced efficiency and the use of only one generator for gas- and steam turbines. However, problems occur concerning the question, how to calculate torsional stresses and take into account the operation of the clutch in case of electrical faults. The article presents calculations of shaft and coupling torques as functions of time carried out by different methods in one exemplary case of faulty operation for a 351MW/228MW combined gas and steam single-shaft plant The clutch is modelled by a nonlinear torsional stiffness. The calculations show extremely strong impacts of torque inside the clutch due to intermittend engagement and disengagement processes. However, taking additionally into account damping influences inside the clutch one obtains no significant deviations from the results of a calculation for rigid couplings instead of the clutch.

U.S. Program on Materials Technology for Ultrasupercritical Coal-Fired Steam Power Plants

2007 ◽  
Author(s):  
R. Viswanathan ◽  
Robert Purgert
Keyword(s):  
Power Plants ◽  
Department Of Energy ◽  
Fireside Corrosion ◽  
Steam Power ◽  
Steam Power Plants ◽  
Percentage Points ◽  
Corrosion Studies ◽  
The Us ◽  
Temperature And Pressure ◽  
Reduction Of Co2

One of the pathways for achieving the goal of utilizing the available large quantities of indigenous coal, at the same time reducing emissions, is by increasing the efficiency of power plants by utilizing much higher steam conditions. The US Ultra-Supercritical Steam (USC) Project funded by US Department of Energy (DOE) and the Ohio Coal Development Office (OCDO) promises to increase the efficiency of pulverized coal-fired power plants by as much as nine percentage points, with an associated reduction of CO2 emissions by about 22% compared to current subcritical steam power plants, by increasing the operating temperature and pressure to 760°C (1400°F) and 35 MPa (5000 psi), respectively. Preliminary analysis has shown such a plant to be economically viable. The current project primarily focuses on developing the materials technology needed to achieve these conditions in the boiler. The scope of the materials evaluation includes mechanical properties, steam-side oxidation and fireside corrosion studies, weldability and fabricability evaluations, and review of applicable design codes and standards. These evaluations are nearly completed and are providing the confidence that currently-available materials can meet the challenge.

Numerical and Experimental Investigations of the Transient Thermal Behavior of a Steam By-Pass Valve at Steam Temperatures Beyond 700 °C

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Anis Haj Ayed ◽  
Martin Kemper ◽  
Karsten Kusterer ◽  
Hailu Tadesse ◽  
Manfred Wirsum ◽  
...  
Keyword(s):  
Thermal Behavior ◽  
Power Plants ◽  
Numerical Approach ◽  
Life Assessment ◽  
Experimental Investigations ◽  
Steam Power ◽  
Steam Power Plants ◽  
Cyclic Operation ◽  
Measurement Results ◽  
Transient Thermal

Increasing the efficiency of steam power plants is important to reduce their CO2 emissions and can be achieved by increasing steam temperatures beyond 700 °C. Within the present study, the thermal behavior of a steam by-pass valve subject to cyclic operation with 700 °C steam is investigated experimentally and numerically. An innovative numerical approach was applied to predict the valve’s thermal behavior during cyclic operation, which is essential for fatigue life assessment of such a component. Validation of the applied numerical approach has shown good agreement with measurement results, indicating the potential of its application for the valve design process.

Energy Storage Using Low-Pressure Feedwater

1985 ◽  
Vol 107 (3) ◽  
pp. 569-573 ◽  
Author(s):  
C. M. Harman ◽  
S. Loesch
Keyword(s):  
Energy Storage ◽  
Power Plants ◽  
Storage System ◽  
Energy Storage System ◽  
Low Pressure ◽  
Steam Power ◽  
Low Pressure Turbine ◽  
Availability Analysis ◽  
Steam Power Plants ◽  
And Storage

A method for increasing the peak output of steam power plants through use of a low-pressure feedwater storage system is presented. The generalized availability analysis involves only the low-pressure turbine, low-pressure feedwater heaters, and the storage system. With daily cycling and storage charging at near base load conditions, the turnaround efficiency of the energy storage system was found to approach 100 percent. Storage system turnaround efficiency is decreased when the energy is stored during plant part-load operation.

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