Combined Cycle Power Plant System Research Articles

Thermodynamic Analysis of Once-through Heat Recovery Steam Generator in a Combined Cycle Power Plants Fueled with Biogas

The working principle of the combined cycle in the combined cycle power plant (CCPP) is to utilize a certain amount of waste heat in the gas turbine, which reaches temperatures of 1650°C, to generate steam in the steam turbine. Due to the high temperature of the exhaust gas in the gas turbine, a device is needed to recover this waste heat, known as a Heat Recovery Steam Generator (HRSG). Compared to conventional HRSG, a once-through heat recovery steam generator (OTHRSG) offers the advantages of faster design time (25% faster than conventional) and lower design costs because it does not require a drum which contributes to an increase in thermal efficiency. This study aims to model and simulate the CCPP system with an OTHRSG to achieve maximum thermal efficiency by using biogas from the degradation of organic waste as the input fuel for CCPP using Cycle Tempo software. The thermal efficiency of the CCPP system was achieved at 57% by applying turbine inlet temperature (TIT) of 1500°C and compression ratio of 46. These results proved that the CCPP system by using biogas as fuel could increase the thermal efficiency of a single cycle power plant.

Performance Evaluation of the Afam VI Combined Cycle Power Plant System using Energy and Exergy Analysis Approach

Performance Evaluation of the Afam VI Combined Cycle Power Plant System using Energy and Exergy Analysis Approach

Power Generation Optimization of the Combined Cycle Power-Plant System Comprising Turbo Expander Generator and Trigen in Conjunction with the Reinforcement Learning Technique

In this paper, a method that utilizes the reinforcement learning (RL) technique is proposed to establish an optimal operation plan to obtain maximum power output from a trigen generator. Trigen is a type of combined heat and power system (CHP) that provides chilling, heating, and power generation, and the turbo expander generator (TEG) is a generator that uses the decompression energy of gas to generate electricity. If the two are combined to form a power source, a power generation system with higher efficiency can be created. However, it is very difficult to control the heat and power generation amount of TEG and trigen according to the flow rate of natural gas that changes every moment. Accordingly, a method is proposed to utilize the RL technique to determine the operation process to attain an even higher efficiency. When the TEG and trigen are configured using the RL technique, the power output can be maximized, and the power output variability can be reduced to obtain high-quality power. When using the RL technique, it was confirmed that the overall efficiency was improved by an additional 3%.

Comparison of steel manufacturing off-gas utilization methods via life cycle analysis

This study utilizes life cycle analysis to compare three steel manufacturing off-gas utilization systems: a status quo system, which produces electricity via a low-pressure steam turbine; a combined cycle power plant system, which produces electricity using gas and steam turbines; and a methanol production system, which converts coke oven gas and blast furnace gas into methanol. This research seeks to compare the environmental impacts of each system based on equivalent raw material inputs. Since the systems have different products, system expansion is used to ensure that they have the same outputs/functional units and are therefore comparable. The system boundary consists of a combination of cradle-to-gate and gate-to-gate boundaries. The environmental effects of each system are compared at five locations—Ontario, the USA, Finland, Mexico, and China—using TRACI, CML-IA baseline, ReCiPe2016, and IMPACT2002+ in SimaPro v9. The results show that due to different electricity carbon intensities, different natural gas supply chains, and different methanol supply chains, the Ontario, Finland, and China case studies had the lowest environmental impact when the steel refinery is retrofitted to include a methanol production system, while the USA and Mexico case studies had the lowest impact when retrofitting a combined cycle power plant system. The status quo system had the greatest environmental impact for all of the studied locations, except for the USA. This environmental assessment, combined with previous economic analysis, demonstrates that the methanol production system is the optimal choice in Ontario and China. In the USA, plants might be better off adopting combined cycle power plant systems when carbon taxes reach $50/tonne. For Mexico, the combined cycle power plant system is the most environmentally friendly choice, while the methanol production system is the most profitable. Finally, the results indicate that status quo systems are not recommended in Mexico or China in any foreseeable circumstance.

Biomass Pyrolysis and Gasification Comprehensive Modeling for Effective Power Generation at Combined Cycle Power Plant

Thermogravimetric experiments were carried out for a few types of wood with determination of the kinetic parameters characterizing the pyrolysis process. In the present work the various kinetic models used for this purpose are suggested. Analyzing software tool for calculation of thermal conversion products and reactor balance is developed. The optimal temperature range for biomass pyrolysis is identified using this tool. The influence of steam and air flow rates on the gasification products is represented. The impact of operating parameters on the synthesis gas composition was evaluated. Comparison of the computational model and the results obtained during experimental studies on the existing gasifier were carried out. The combined cycle power plant involving the biomass gasification process has been numerically simulated in the Aspen Plus. Calculations of the optimal operating parameters of different thermal process components and of the entire combined cycle power plant system were performed.

Parametric-Based Thermodynamic Analysis of Organic Rankine Cycle as Bottoming Cycle for Combined-Cycle Power Plant

In Pakistan, the thermal efficiency of the power plants is low because of a huge share of fuel energy is dumped into the atmosphere as waste heat. The ORC (Organic Rankine Cycle) has been revealed as one of the promising technologies to recover waste heat to enhance the thermal efficiency of the power plant. In current work, ORC is proposed as a second bottoming cycle for existing CCPP (Combined Cycle Power Plant). In order to assess the efficiency of the plant, a thermodynamic model is developed in the ESS (Engineering Equation Solver) software. The developed model is used for parametric analysis to assess the effects of various operating parameters on the system performance. The analysis of results shows that the integration of ORC system with existing CCPP system enhances the overall power output in the range of 150.5-154.58 MW with 0.24-5% enhancement in the efficiency depending on the operating conditions. During the parametric analysis of ORC, it is observed that inlet pressure of the turbine shows a significant effect on the performance of the system as compared to other operating parameters.

Life cycle assessment and optimization of an iron making system with a combined cycle power plant: a case study from China

In the steel industry, the iron making system deals with large quantities of materials and energy and so it can play a critical role in reducing emissions and production costs. More specifically, excess by-product gases should be used for electricity generation; otherwise, they lead to pollution. A life cycle analysis is performed to compare the environmental impact of an iron making system with a combined cycle power plant (CCPP), to a system producing the same amount of electricity in a coal power plant. The results for a Chinese steel plant show a 33% reduction in the energy conservation and emission reduction potential for the CCPP system, which is thus more environmentally friendly. A mathematical programming formulation is then proposed for optimal scheduling. It incorporates key technological constraints and is sensitive to hourly changing electricity prices. The outcome is a 19% increase in revenue from electricity sales compared to a schedule that does not dynamically adjust to the price profile. The results also show that emissions from by-product gases can be avoided completely. The paper ends with a sensitivity analysis to evaluate the impact of changes in product demand, gas storage and CCPP capacity, and emission cost.

Thermodynamic analysis of solar energy integrated underground coal gasification in the context of cleaner fossil power generation

Underground coal gasification (UCG) is an in-situ physico-chemical process for the conversion of deep coal resources into useful product gas. The UCG process is inherently a clean coal technology avoiding several difficulties of conventional coal mining process. However, it is a complex in-situ phenomenon depending on site-specific geological parameters. Energy loss occurs in a UCG process due to water influx, underground cavity pressure drop, gas loss to the surrounding strata and high temperature gasifying medium, which are major challenges of UCG operation. These losses can be compensated if UCG is integrated with solar energy, which is a renewable and a cleaner source of energy. In the present study, two types of low pressure UCG based power plants are conceptualised using solar energy – (i) a conventional steam turbine cycle consisting of a high pressure, a medium pressure and a low pressure turbine and (ii) a gas turbine cycle with supercritical carbon dioxide (sCO2) as a working fluid operating in a combined cycle power plant system. The scope of integration of solar power on the UCG based power plant systems is discussed for cleaner energy production. A detailed thermodynamic analysis is carried out to estimate the thermal efficiency of both cycles for cases with and without the integration of solar energy. A net thermal efficiency of the solar-UCG based steam turbine cycle is found as 28.2% with carbon capture and storage (CCS). The solar-UCG based sCO2 gas turbine cycle shows a high net thermal efficiency of 32.9% with CCS, which is 4% higher than the respective system without having solar energy utilization.

Optimization of fog inlet air cooling system for combined cycle power plants using genetic algorithm

In this research paper, a comprehensive thermodynamic modeling of a combined cycle power plant is first conducted and the effects of gas turbine inlet fogging system on the first and second law efficiencies and net power outputs of combined cycle power plants are investigated. The combined cycle power plant (CCPP) considered for this study consist of a double pressure heat recovery steam generator (HRSG) to utilize the energy of exhaust leaving the gas turbine and produce superheated steam to generate electricity in the Rankine cycle. In order to enhance understanding of this research and come up with optimum performance assessment of the plant, a complete optimization is using a genetic algorithm conducted. In order to achieve this goal, a new objective function is defined for the system optimization including social cost of air pollution for the power generation systems. The objective function is based on the first law efficiency, energy cost and the external social cost of air pollution for an operational system. It is concluded that using inlet air cooling system for the CCPP system and its optimization results in an increase in the average output power, first and second law efficiencies by 17.24%, 3.6% and 3.5%, respectively, for three warm months of year.

Safety System Analysis on Gas-Steam Combined Cycle Power Plant

Risk factor in gas-steam combined cycle power plant (CCPP) was identified by application of safety system engineering principles and techniques. The CCPP system was divided into gas transmission subsystem, gas turbine subsystem, waste heat boiler subsystem, steam turbine subsystem and generation & transformation subsystem. The accident-proneness areas in each subsystem were studied, and various accident-causation modes were clarified. The bursting leakage accident caused by failure of steam-water pipelines was analyzed, and evaluated with Fault Tree method. The targeted countermeasures of safe operation and management were proposed.

Development of reliability index for combined cycle power plant using graph theoretic approach

A systematic approach based on graph theory and matrix method is developed ingeniously for the evaluation of reliability index for a Combined Cycle Power Plant (CCPP). In present work CCPP system is divided into six subsystems. Consideration of all these subsystems and their interrelations are rudiment in evaluating the index. Reliability of CCPP is modeled in terms of a Reliability Attributes Digraph. Nodes in digraph represent system reliability and reliability of interrelations is represented by edges. The digraph is converted into one-to-one matrix called as Variable System Reliability Permanent Matrix (VPM-r). A procedure is defined to develop variable permanent function for reliability (VPF-r) from VPM-r. Reliability index of CCPP system is obtained from the permanent of the matrix by substituting numerical values of the attributes and their interrelations. A higher value of index implies better reliability of the system. The proposed methodology is illustrated step-by-step with the help of two examples.

Coal Gas Dehydration Equipment in Combined Cycle Power Plant

To reduce the moisture content of coal gas in combined cycle power plant, a new type dehydration equipment is introduced. The curved plate dehydration equipment is composed of many pieces of stainless plate which has some collection hooks at every corner. Meanwhile, a new method on measuring moisture in gas by using superfine fibreglass is introduced.The gas-water separation efficiency was calculated by the difference of moisture content before and after the curved plate dehydration equipment. The dehydration efficiency of curved plate in combined cycle power plant system was tested under different operating load, the results show that gas velocity and gas/liquid ratio have a great influence on the coal gas dehydration efficiency. If the washing water flow rate and pressure are changed, the efficiency will change at the same time. The moisture content is low when the spraying nozle works at a high water pressure. The operation water pressure and working voltage of electrostatic precipitator have been proposed by testing and analysis. It will have great advantage to the safe operation of turbine.

ガスタービン用実規模触媒燃焼器によるメタン燃焼

The methane combustion test at atmospheric pressure was carried out by using a full scale catalytic combustor with an improved Pd catalyst for 100MW gas tur-bine. The objective is to clarify the feasibility on application of high temperature catalytic combustion to gas turbines for the LNG combined cycle power plant system. The results can be summerized as follows:1) The manufactured full scale catalytic combustor consists of a reverse annular pre-burner, an annular mixer and Pd catalyst. The dimensions of combustor is 450mm in dia-meter and 800mm in length.2) Pd catalyst showed high activity in methane catalytic combustion and the combustion reaction proceeded enough at even lower temperatures corresponded to the compressed air temperature in gas turbine systems.3) The catalytic combustor showed excellent performance in methane combustion at atmospheric pressure. The NOx emission was extremely low and the combustion efficiency was approximately 100% in wide range conditions. As a result, catalytic combustion is ex-pected to be applied to gas turbine combustors.