Generalized Regeneration Theory and its Energy Saving and Emission Reduction Effects on Coal-Fired Power Generation

2016 ◽  
Author(s):  
Weizhong Feng
Keyword(s):  
Power Plants ◽  
High Efficiency ◽  
Steam Pressure ◽  
Combustion Efficiency ◽  
Operating Conditions ◽  
Low Oxygen ◽  
Material Technology ◽  
Boiler Operation ◽  
Combustion Technology ◽  
Reduce Emissions

Concerns related to global warming and environmental pollution concerns have pressured coal-fired power plants to improve efficiency and reduce emissions. However, the conventional efficiency improvement methods — increasing steam pressure and temperature and reducing condenser pressure are limited by material technology and the temperature of the available cooling medium. The next step for increasing efficiency would be to add additional reheat or regenerative cycles, but this is not feasible for existing plants. In addition, as the share of renewable energy and the grid’s demands on the coal-fired power plants increases, China’s coal-fired units are faced with more and tougher challenges, including large peak-valley gaps, frequent startups and shutdowns and cost pressures. As a result, the boiler combustion efficiency decreases and incidents such as furnace explosions, aggravation and collapsing of slag and burning of facilities located downstream of the economizer become more frequent. To address these problems, the generalized regeneration theory has been proposed and a series of related technologies have been developed, providing a new approach for not only improving the efficiency of coal-fired power plants, but also resulted in boiler operation that is cleaner and safer. These technologies which include anew boiler startup technology, the high efficiency combustion and low emission technology under low load and the low oxygen, and a low NOx and high efficiency combustion technology under high load have been implemented successfully in the Shanghai Waigaoqiao No. 3 power plant. By improving the utilization of turbine extraction and reducing the exhaust loss, these innovative technologies greatly improve the environmental performance, efficiency and safety of the units in various operating conditions. In addition, improvements have been made in the boilers ability to adapt to changing coal supplies, particularly for coal with high slagging tendencies and high moisture content.

scholarly journals Improvement of efficiency of detecting vacuum leakages by using combined methods

Vestnik IGEU ◽  
2021 ◽  
pp. 13-21
Author(s):  
A.D. Vodeniktov ◽  
V.G. Vlasenko ◽  
N.D. Chichirova
Keyword(s):  
Steam Turbine ◽  
Thermal Imaging ◽  
Power Plants ◽  
High Efficiency ◽  
Ultrasonic Method ◽  
Cost Effective ◽  
Steam Pressure ◽  
Operating Conditions ◽  
Vacuum System ◽  
Imaging Method

Trouble-free operation of the main equipment of heat power plants is determined by the performance reliability of condensing units. High air density of the vacuum system provides cost-effective and reliable operation. One of the reasons that causes an increase of the exhaust steam pressure compared to the standard pressure, in addition to contamination of the condensers cooling surface, is the high amount of air inflow through vacuum system leakiness. Exceeding the amount of atmospheric air inflow into the vacuum system above the standard value, both reduces the available heat energy and make worse the deaeration capacity of the condenser. This results in saturation of the full-flow condensate with oxygen and intensification of corrosion processes. Various methods varying in both cost and efficiency are used to find air inflow location. Nowadays, the issue of choosing a method to detect even the most insignificant air inflow location of the vacuum system of a steam turbine remains open. In the current study, the authors have used the thermal-imaging method to detect air inflow location due to local hypocooling, and the ultrasonic method, which is based on the detection of ultrasound created by gas flows. The authors have proved the necessity to use several different in concept methods to find leakage locations in a vacuum system. It is established that traditional methods to find vacuum system leaks do not allow to eliminate excess leaks. In-service monitoring confirms 87 % reduction of the amount of vacuum leaks. The studies show high efficiency of sharing both thermal imaging and ultrasonic methods to detect air inflow location in a vacuum system. According to the operating conditions of the available equipment, as well as the personnel qualifications, the results obtained make it possible to choose the most optimal way in terms of financial and time expenses to find vacuum leakage location in the vacuum system of a steam turbine.

"Recent Patents on the Triboelectrostatic Separation of Fly Ash"

2019 ◽  
Vol 13 ◽  
Author(s):  
Haisheng Li ◽  
Wenping Wang ◽  
Yinghua Chen ◽  
Xinxi Zhang ◽  
Chaoyong Li
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
High Efficiency ◽  
Separation Efficiency ◽  
High Reliability ◽  
Operating Conditions ◽  
Security Requirements ◽  
Unburned Carbon ◽  
Efficient Operation ◽  
Triboelectrostatic Separation

Background: The fly ash produced by coal-fired power plants is an industrial waste. The environmental pollution problems caused by fly ash have been widely of public environmental concern. As a waste of recoverable resources, it can be used in the field of building materials, agricultural fertilizers, environmental materials, new materials, etc. Unburned carbon content in fly ash has an influence on the performance of resource reuse products. Therefore, it is the key to remove unburned carbon from fly ash. As a physical method, triboelectrostatic separation technology has been widely used because of obvious advantages, such as high-efficiency, simple process, high reliability, without water resources consumption and secondary pollution. Objective: The related patents of fly ash triboelectrostatic separation had been reviewed. The structural characteristics and working principle of these patents are analyzed in detail. The results can provide some meaningful references for the improvement of separation efficiency and optimal design. Methods: Based on the comparative analysis for the latest patents related to fly ash triboelectrostatic separation, the future development is presented. Results: The patents focused on the charging efficiency and separation efficiency. Studies show that remarkable improvements have been achieved for the fly ash triboelectrostatic separation. Some patents have been used in industrial production. Conclusion: According to the current technology status, the researches related to process optimization and anti-interference ability will be beneficial to overcome the influence of operating conditions and complex environment, and meet system security requirements. The intelligent control can not only ensure the process continuity and stability, but also realize the efficient operation and management automatically. Meanwhile, the researchers should pay more attention to the resource utilization of fly ash processed by triboelectrostatic separation.

Preliminary design and performance analysis of a low emission aero-derived gas turbine combustor

2013 ◽  
Vol 117 (1198) ◽  
pp. 1249-1271 ◽  
Author(s):  
B. Khandelwal ◽  
A. Karakurt ◽  
V. Sethi ◽  
R. Singh ◽  
Z. Quan
Keyword(s):  
Gas Turbine ◽  
Combustion Efficiency ◽  
Operating Conditions ◽  
Gas Turbine Combustor ◽  
Detailed Method ◽  
Low Emission ◽  
Heat Shields ◽  
Lean Fuel ◽  
Reduce Emissions ◽  
And Performance

Abstract Modern gas turbine combustor design is a complex task which includes both experimental and empirical knowledge. Numerous parameters have to be considered for combustor designs which include combustor size, combustion efficiency, emissions and so on. Several empirical correlations and experienced approaches have been developed and summarised in literature for designing conventional combustors. A large number of advanced technologies have been successfully employed to reduce emissions significantly in the last few decades. There is no literature in the public domain for providing detailed design methodologies of triple annular combustors. The objective of this study is to provide a detailed method designing a triple annular dry low emission industrial combustor and evaluate its performance, based on the operating conditions of an industrial engine. The design methodology employs semi-empirical and empirical models for designing different components of gas turbine combustors. Meanwhile, advanced DLE methods such as lean fuel combustion, premixed methods, staged combustion, triple annular, multi-passage diffusers, machined cooling rings, DACRS and heat shields are employed to cut down emissions. The design process is shown step by step for design and performance evaluation of the combustor. The performance of this combustor is predicted, it shows that NO x emissions could be reduced by 60%-90% as compared with conventional single annular combustors.

Improvement in Recuperative Gas Cycles by Means of a Heat Generator Partly By-Passing the Recuperator: Application to Open and Closed Cycles and to Various Kinds of Energy

1979 ◽  
Author(s):  
Z. P. Tilliette ◽  
B. Pierre
Keyword(s):  
Power Plants ◽  
High Efficiency ◽  
Primary Energy ◽  
Operating Conditions ◽  
Heat Output ◽  
Medium Temperature ◽  
Heat Generator ◽  
High Temperature Process ◽  
Temperature Heat ◽  
Operation Flexibility

A particular arrangement applicable to open or closed recuperative gas cycles, consisting of a heat generator partly by-passing the low pressure side of the recuperator, is proven to enhance the advantages of gas cycles for energy production. In this way, the cogeneration of both power with high efficiency owing to the recuperator and high temperature process heat becomes possible and economically attractive. Furthermore, additional possibilities appear for power generation by combined gas and steam or ammonia cycles. In any case, the overall utilitization coefficient of the primary energy is increased and the combined production of low or medium temperature heat can also be improved. The great operation flexibility of the system for combined energy generation is worth being emphasized: the by-pass arrangement involves no significant change in the operating conditions of the main turbocompressor as the heat output varies. Applications of this arrangement are made to open and closed gas cycle power plants using fossil, nuclear and solar energies. The overall heat conversion efficiency is tentatively estimated in order to appreciate the energy conversion capability of the investigated power plants.

Development of High Efficiency MCFC/GT Hybrid Power Generation System

2003 ◽  
Author(s):  
T. Watanabe ◽  
Y. Izaki ◽  
Y. Mugikura ◽  
M. Yoshikawa ◽  
H. Morita ◽  
...  
Keyword(s):  
Power Plants ◽  
High Efficiency ◽  
Low Voltage ◽  
Operating Conditions ◽  
Performance Estimation ◽  
Estimation Methods ◽  
Central Research ◽  
Molten Carbonate ◽  
Initial Development ◽  
Hybrid Power

A number of cycle simulations, which are applied by Molten Carbonate Fuel Cell (MCFC) power plants combined with gas/steam turbines, prove that it is possible to design very highly efficient power plants. However, the stack performance, the operation technology and the performance estimation technology have not yet been established during the initial development stages. The Central Research Institute of Electric Power Industry (CRIEPI) has performed many cell and stack tests and has evaluated the performance under various operating conditions. The operation, performance analysis and estimation methods have been developed for various pressure ranges. Therefore, the accuracy of the plant power estimation has been improved immensely. CRIEPI has also proposed the application of a Li/Na electrolyte instead of a Li/K to achieve higher voltages and a longer stack life. A 10 kW-class short stack consisting of ten 1-m2 cells with a Li/Na electrolyte was operated for more than 10,000 hours, and a very low voltage decay rate was measured during the governmental program. Based on these accomplishments, field tests on small MCFC/GT (gas turbine) hybrid power plants with capacities of several hundred kW will be initiated in Japan throughout the next years.

Experimental Study of Steam Pressure Suppression by Condensation in a Water Tank at Sub-Atmospheric Pressure

2016 ◽  
Author(s):  
Dahmane Mazed ◽  
Rosa Lo Frano ◽  
Donato Aquaro ◽  
Daniele Del Serra ◽  
Igor Sekachev ◽  
...  
Keyword(s):  
Experimental Study ◽  
Atmospheric Pressure ◽  
High Efficiency ◽  
Saturation Pressure ◽  
Steam Pressure ◽  
Operating Conditions ◽  
Water Tank ◽  
Vacuum Vessel ◽  
Steam Condensation ◽  
Suppression System

The Vacuum Vessel Pressure Suppression System (VVPSS), a key safety system of the ITER plant, is designed to protect the Vacuum Vessel (VV) from over pressure occurring in the case of LOCA (Loss Of Coolant Accident) or other pressurizing accidents such as LOVA (Loss Of Vacuum Accident). The steam condensation in the Suppression Tanks (main elements of the VVPSS system), occurs at sub-atmospheric pressure. The steam condensation, at pressures equal or greater than the atmospheric, has been numerically analyzed and experimentally investigated in the past in order to optimize the design of the pressure suppression system of boiling water nuclear reactors. However, very limited experimental data is available concerning the steam condensation in a water tank at sub-atmospheric pressure. In order to analyze the steam condensation in these operating conditions, an experimental study, funded by ITER Organization, is conducted at the Department of Civil and Industrial Engineering (DICI) of University of Pisa. The tests analyze the condensation of saturated or superheated steam at sub-atmospheric pressures (4.2 kPa and slightly above the water vapour saturation pressure), and pool temperature up to 50°C at several heights of water head. The experimental facility, to perform this study, has been set up with a significant scaling factor regarding the full size installation at ITER. In this paper the experimental rig, the conditions of the experiments, and the test matrix are presented. The temperature and pressure measurements with details of the data acquisition system are described. The tests were performed at different patterns of the sparger exit holes (1, 3 and 9) and for three steam mass flow rates per one hole. The results show very high efficiency of condensation for all examined conditions. Finally, a comparison between the condensation regimen at sub-atmospheric and at atmospheric pressure is discussed.

scholarly journals Efficiency of Off-Peak Electricity Conversion at Nuclear Power Plants Using Reversible Fuel Cells

2021 ◽  
Vol 2096 (1) ◽  
pp. 012193
Author(s):  
A N Egorov
Keyword(s):  
Fuel Cells ◽  
Nuclear Power ◽  
Peak Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
High Efficiency ◽  
Combustion Technology ◽  
Power Complex ◽  
Electrolysis Mode ◽  
Current Stage

Abstract The article provides a comparative analysis of the efficiency of off-peak electricity conversion at nuclear power plants (NPP) using reversible fuel cells (RFC). The RFC can ensure the NPP the baseline electrical load through hydrogen production by electrolysis of water, as well as an increase in its maneuverability due to generation of peak electricity. The calculations have shown that at the current stage of technological advancements, the use of RFCs in terms of achievable efficiency of off-peak electricity conversion has advantages over the hydrogen power complex which utilizes an additional steam turbine to generate peak electricity. The achievable advantage equals 2.84-4.25% and 7.72-11.58% at the RFC efficiency in the mode of peak power generation of 50% and 60%, respectively, which is 5.1-7.66 MW and 13.9-20.85 MW more than the generated peak electricity. It should be noted that an increase in the electrolysis mode efficiency facilitates the RFC advantages – from 24.44 to 36.65% and from 29.32 to 43.98% respectively. The use of the "cold" combustion technology for hydrogen fuel ensures not only high efficiency, but also reliability and safety of the hydrogen power complex operation

scholarly journals A Model-Based Coordinated Control Concept for Steam Power Plants

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Ali Chaibakhsh ◽  
Ali Ghaffari
Keyword(s):  
Control System ◽  
Power Plants ◽  
Electrical Power ◽  
Coordinated Control ◽  
Steam Pressure ◽  
Operating Conditions ◽  
Output Pressure ◽  
Model Based ◽  
Neuro Fuzzy ◽  
Control Concept

An application of model-based coordinated control concept for improving the performance and maneuverability of once-through power plants is presented. In this structure, neuro-fuzzy-based Hammerstein models are employed as the core of feedforward (FF) controller to generate the reference trajectories for the plant’s subsystems. The setpoints for fuel, electrical power, and steam pressure are provided by FF controller with respect to load demands. In order to diminish the effect of disturbances and to compensate deviations between variables and corresponding feedforward setpoints, feedback controllers are considered. The error signal defined by the deviation of desired boiler output pressure from its actual value is used to compensate the demand signals for turbine and boiler. The performance of the proposed control system is compared with that of a conventional turbine-follower and also turbine-follower coordinated control modes during load changes. The results indicate the effectiveness and load tracking capability of the proposed control system at different operating conditions.

scholarly journals Influence of Wood Fly Ash on Concrete Properties through Filling Effect Mechanism

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7164
Author(s):  
Ivan Gabrijel ◽  
Marija Jelčić Rukavina ◽  
Nina Štirmer
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Power Plants ◽  
Heat Liberation ◽  
Heat Of Hydration ◽  
Operating Conditions ◽  
Capillary Absorption ◽  
Cement Replacement ◽  
Combustion Technology ◽  
Compressive Strength Of Concrete

This paper presents the results of an experimental study aimed at determining the influence of wood fly ash (WFA) from three Croatian power plants on the properties of concrete. First, the chemical and physical properties of WFA’s were determined. It was found that these properties are highly influenced by combustion technology, the type and parts of wood used as fuel, and the local operating conditions. Subsequently, workability, heat of hydration, stiffness development, 28-day compressive strength, apparent porosity, and capillary absorption were determined on concrete mixes prepared with WFA as cement replacement from 5–45% by weight. Cement replacement up to 15% with the finest WFA accelerated hydration, stiffness development, and increased compressive strength of concrete up to 18%, while replacement with coarser WFA’s led to a decrease in compressive strength of up to 5% and had more gradual heat liberation. The dominant effect that could explain these findings is attributed to the filler and filling effect mechanisms. At the same time replacement content of up to 45% had very little effect on capillary absorption and could give concrete with sufficiently high compressive strength to be suitable for construction purposes.

PF-fired supercritical power plant

2003 ◽  
Vol 217 (1) ◽  
pp. 35-43 ◽  
Author(s):  
P. E. Chew
Keyword(s):  
Steam Pressure ◽  
The State ◽  
Operating Conditions ◽  
Steam Turbines ◽  
Pulverized Fuel ◽  
Furnace Tube ◽  
Combustion Technology ◽  
Under Construction ◽  
Main Steam ◽  
Plant Efficiency

Pulverized fuel firing is the dominant application of supercritical steam cycles. This has been driven by the aims of efficiency improvement and reduction in environmental emissions. The sensitivity of supercritical steam plant to operating conditions is reviewed and the improvements in operating plant efficiency achieved through increase in steam pressure and temperatures and other factors such as auxiliary power demand is illustrated. Steam temperatures have increased by about 40°C during the 1990s and this, together with an increase in main steam pressure and cycle improvement, have led to a net efficiency of 45 per cent (reduced to UK conditions) for the state-of-the-art plant at present. Plants with still more advanced conditions are under construction or are planned, with the prospect of plant efficiency of 50 per cent in the future. This will rely on continued improvement in materials and is supported by a number of European programmes. Some main difficulties in the design of boilers with advanced temperatures, in particular steam temperature at the furnace outlet, furnace tube arrangement, and materials for superheater and reheater outlet sections, are discussed and the state of advanced steam turbines is reviewed. The operational availability of the supercritical plant, at least in Europe, has improved such that it is little different to the subcritical plant. Similarly, significant improvements have been made in controlling emissions by refinement of flue gas clean-up systems and combustion technology.

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