Improved Design of a 25 MW Gas Turbine Plant Using Combined Cycle Application

This paper presents the improved design of a 25 MW gas turbine power plant at Omoku in the Niger Delta area of Nigeria, using combined cycle application. It entails retrofitting a steam bottoming plant to the existing 25 MW gas turbine plant by incorporating a heat recovery steam generator. The focus is to improve performance as well as reduction in total emission to the environment. Direct data collection was performed from the HMI monitoring screen, log books and manufacturer’s manual. Employing the application of MATLAB, the thermodynamics equations were modeled and appropriate parameters of the various components of the steam turbine power plant were determined. The results show that the combined cycle system had a total power output of 37.9 MW, made up of 25.0 MW from the gas turbine power plant and 12.9 MW (an increase of about 51%) from the steam turbine plant, having an HRSG, condenser and feed pump capacities of 42.46 MW, 29.61 MW and 1.76 MW respectively. The condenser cooling water parameters include a mass flow of 1180.42 kg/s, inlet and outlet temperatures of 29.8°C and 35.8°C respectively. The cycle efficiency of the dry mode gas turbine was 26.6% whereas, after modification, the combined cycle power plant overall efficiency is 48.8% (about 84% increases). Hence, SIEMENS steam turbine product of MODEL: SST-150 was recommended as the steam bottoming plant. Also the work reveals that a heat flow of about 42.46 MW which was otherwise being wasted in the exhaust gas of the 25 MW gas turbine power plant could be converted to 12.9 MW of electric power, thus reducing the total emission to the environment.

Thermodynamic Performance Analysis of E/F/H-Class Gas Turbine Combined Cycle with Exhaust Gas Recirculation and Inlet/Variable Guide Vane Adjustment under Part-Load Conditions

Exhaust gas recirculation control(EGRC),an inlet air heating technology,can be utilized in combination with inlet/variable guide vane control(IGV/VGVC) and fuel flow control(FFC) to regulate the load,thereby effectively improving the part-load(i.e.,off-design) performance of the gas turbine combined cycle(GTCC).In this study,the E-,F-,and H-Class EGR-GTCC design and off-design system models were established and validated to perform a comparative analysis of the part-load performance under the EGR-IGV-FFC and conventional IGV-FFC strategies in the E/F/H-Class GTCC.Results show that EGR-IGV-FFC has considerable potential for the part-load performance enhancement and can show a higher combined cycle efficiency than IGV-FFC in the E-,F-,and H-Class GTCCs.However,the part-load performance improvement in the corresponding GTCC was weakened for the higher class of the gas turbine because of the narrower load range of EGR action and the deterioration of the gas turbine performance.Furthermore,EGR-IGV-FFC was inferior to IGV-FFC in improving the performance at loads below 50% for the H-Class GTCC.The results obtained in this paper could help guide the application of EGR-IGV-FFC to enhance the part-load performance of various classes of GTCC systems.

Analysis of Using the M-cycle Regenerative-Humidification Process on a Gas Turbine

This investigation focused on the analysis of using the M-cycle （Maisotsenko cycle） to improve the efficiency of a gas turbine engine. By combining the M-cycle with an open Brayton cycle, a new cycle, is known as the MCTC （Maisotsenko combustion turbine cycle）, was formed. The MCTC used an indirect evaporative air cooler as a saturator with a gas turbine engine. The saturator was applied on the side of the turbine exhaust （M-cycle#2） in the analysis. The analysis included calculations and the development of an EES （engineering equation solver） code to model the MCTC system performance. The resulting performance curves were graphed to show the effects of several parameters on the thermal efficiency and net power output of the gas turbine engine. The models were also compared with actual experimental test that results from a gas turbine engine. Conclusions and discussions of results are also given.

A Continuous Timed Petri Net Model and Control for a Gas Turbine

This work developed the modeling and supervisory control for gas turbine. A CTPN （continuous timed Petri Net） model of a gas turbine, using a first linear order approximation for every state of the Brayton cycle is obtained. The Brayton cycle rules the functioning of a gas turbine, and it is composed by four states： compression, combustion, expansion and cooling. The principle of the gas turbine is developed by the Brayton cycle, a thermodynamic process which intervenes in the gas turbine components. The steady-state behavior of the gas turbine has been widely investigated in engineering area. Moreover, the dynamic behavior has been studied using non-linear models of its components, leading to complicated mathematical representations. The methodology of the current work begins with a simplification of the dynamical relations in every state （excepting the cooling phase） of the Brayton cycle. Temperature and pressure are modeled as first order linear systems, therefore, every system is translated into a CTPN. Furthermore, to guarantee a safety operation, an SC （supervisory controller） is designed to ensure the combustion chamber temperature is lower than 1,000 ℃. Although the model presented is extremely simplified, it will be used as a starting point to develop more complex models.

Thermal-Economic Comparative Analysis and Optimization of the Maisotsenko Gas Turbine Cycle under Different Configurations

The widespread adoption of Maisotsenko gas turbine cycle(MGTC)is significantly constrained by the design and manufacturing complexity of the saturator.The proposition of innovative approaches to regulate the water carrying capacity and operational environment of the saturator,coupled with the performance and economic evaluation of systems under various configurations,can substantially facilitate its commercial implementation.Unlike the conventional two-stage MGTC system that solely comprises aftercooling and regenerative processes,this study proposes a three-stage MGTC system with an intercooling process(IMGTC),which considers the reuse of cooling water and energy recovery.The pricing allocation and energy depreciation characteristics of components are analyzed,and the impact of key variables is considered.Finally,economic optimization of the system is conducted using ISIGHT to identify the optimal parameter combination and results.The results indicate that the saturator price of IMGTC is lower and its exergy efficiency is higher than that of MGTC.The average water capacity of the IMGTC saturator is only 57.4%of that of the MGTC saturator,but the average exergy efficiency of IMGTC is 1.1%higher than that of MGTC.Moreover,external parameters all lead to the levelized cost of electricity(LCOE).Thermo-economic optimization shows that the optimal LCOE of IMGTC is 0.26%lower than that of MGTC.This study confirms the feasibility of IMGTC,as well as its thermodynamic and economic advantages over MGTC.

Machine learning-based multi-objective optimization and thermal assessment of supercritical CO_(2) Rankine cycles for gas turbine waste heat recovery

Technologies for utilizing waste heat for power generation have attracted significant attention in recent years due to their potential to enhance energy efficiency and reduce greenhouse gas emissions.This research focuses on the comparative and optimization analysis of three supercritical carbon dioxide(sCO_(2))Rankine cycles(simple,cascade,and split)for gas turbine waste heat recuperation.The study begins with parametric analysis,investigating the significant effects of key variables,including turbine inlet temperature,condenser inlet temperature,and pinch point temperature,on the thermal performance of advanced sCO_(2) power cycles.To identify the most efficient cycle configuration,a multi-objective optimization approach is employed.This approach combines a Genetic Algorithm with machine learning regression models(Random Forest,XGBoost,Artificial Neural Network,Ridge Regression,and K-Nearest Neighbors)to predict cycle performance using a dataset extracted from cycle simulations.The decision-making process for determining the optimal cycle configuration is facilitated by the TOPSIS(technique for order of preference by similarity to the ideal solution)method.The study's major findings reveal that the split cycle outperforms the simple and cascade configurations in terms of power generation across various operating conditions.The optimized split cycle not only demonstrates superior power output but also exhibits enhanced net power output,heat recovery,system and exergy efficiency of 7.99 MW,76.17%,26.86%and 57.96%,respectively,making it a promising choice for waste heat recovery applications.This research has the potential to contribute to the advancement and widespread adoption of waste heat recovery in energy technologies boosting system efficiency and economic feasibility.It provides a new perspective for future research,contributing to the improvement of energy generation infrastructure.

Simulation Modelling and Techno-Economics of Supercritical Carbon Dioxide Recompression Closed Brayton Cycle

In recent years, there has been global interest in meeting targets relating to energy affordability and security while taking into account greenhouse gas emissions. This has heightened major interest in potential investigations into the use of supercritical carbon dioxide (sCO2) power cycles. Climate change mitigation is the ultimate driver for this increased interest;other relevant issues include the potential for high cycle efficiency and a circular economy. In this study, a 25 MWe recompression closed Brayton cycle (RCBC) has been assessed, and sCO2 has been proposed as the working fluid for the power plant. The methodology used in this research work comprises thermodynamic and techno-economic analysis for the prospective commercialization of this sCO2 power cycle. An evaluated estimation of capital expenditure, operational expenditure, and cost of electricity has been considered in this study. The ASPEN Plus simulation results have been compared with theoretical and mathematical calculations to assess the performance of the compressors, turbine, and heat exchangers. The results thus reveal that the cycle efficiency for this prospective sCO2 recompression closed Brayton cycle increases (39% - 53.6%) as the temperature progressively increases from 550˚C to 900˚C. Data from the Aspen simulation model was used to aid the cost function calculations to estimate the total capital investment cost of the plant. Also, the techno-economic results have shown less cost for purchasing equipment due to fewer components being required for the cycle configuration as compared to the conventional steam power plant.

Application of Supercritical CO2 Gas Turbine for the Fossil Fired Thermal Plant

A supercritical CO2 gas turbine cycle can produce power at high efficiency and the gas turbine is compact compared with the steam turbine. Therefore, it is very advantageous power cycle for the medium temperature range less than 650 ℃. The purpose of this paper is to show how it can be effectively applied not only to the nuclear power but also to the fossil fired power plant. A design of 300 MWe plant has been carried out, where thermal energy of flue gas leaving a CO2 heater is utilized effectively by means of economizer and a high cycle thermal efficiency of 43.4 % has been achieved. Since the temperature and the pressure difference of the CO2 heater are very high, the structural design becomes very difficult. It is revealed that this problem can be effectively solved by introducing a double expansion turbine cycle. The component designs of the CO2 heater, the economizer, supercritical CO2 turbines, compressors and the recuperators are given and it is shown that these components have good performances and compact sizes.

Performance Assessment of a Novel Polygeneration System Based on the Integration of Waste Plasma Gasification,Tire Pyrolysis,Gas Turbine,Supercritical CO_(2)Cycle and Organic Rankine Cycle

In this paper,a novel polygeneration system involving plasma gasifier,pyrolysis reactor,gas turbine(GT),supercritical CO_(2)(S-CO_(2))cycle,and organic Rankine cycle(ORC)has been developed.In the proposed scheme,the syngas is obtained by the gasification and the pyrolysis is first burned and drives the gas turbine for power generation,and then the resulting hot exhaust gas is applied to heat the working fluid for the supercritical CO_(2)cycle and the working fluid for the bottom organic Rankine cycle.In addition to the electrical output,the pyrolysis subsystem also produces pyrolysis oil and char.Accordingly,energy recovery is achieved while treating waste in a non-hazardous manner.The performance of the new scheme was examined by numerous methods,containing energy analysis,exergy analysis,and economic analysis.It is found that the net total energy output of the polygeneration system could attain 19.89 MW with a net total energy efficiency of 52.77%,and the total exergy efficiency of 50.14%.Besides,the dynamic payback period for the restoration of the proposed project is only 3.31 years,and the relative net present value of 77552640 USD can be achieved during its 20-year lifetime.

Malfunction Diagnosis of the GTCC System under All Operating Conditions Based on Exergy Analysis

After long-term operation,the performance of components in the GTCC system deteriorates and requires timely maintenance.Due to the inability to directly measure the degree of component malfunction,it is necessary to use advanced exergy analysis diagnosis methods to characterize the components’health condition(degree of malfunction)through operation data of the GTCC system.The dissipative temperature is used to describe the degree of malfunction of different components in the GTCC system,and an advanced exergy analysis diagnostic method is used to establish a database of overall operating condition component malfunctions in theGTCC system.Ebsilon software is used to simulate the critical parameters of the malfunctions of the GTCC system components and to obtain the changes in the dissipative temperature of different components.Meanwhile,the fuel consumption and economic changes of the GTCC system on a characteristic power supply day under health and malfunction conditions are analyzed.Finally,the effects of maintenance costs,electricity,and gas prices on maintenance expenses and profits are analyzed.The results show that the GTCC system maintenance profit is 6.07$/MWh,while the GTCC system maintenance expense is 5.83$/MWh.Compared with the planned maintenancemode,the malfunction maintenance mode saves 0.24$/MWh.Simultaneously,the maintenance coefficient of GTCC should be adjusted under different malfunctions to obtain a more accurate maintenance period.

Economics and Performance Forecast of Gas Turbine Combined Cycle

Forecasts of the various types of gas turbines economics and performance of gas turbine combined cycle （GTCC） with will help power plant designers to select the best type of gas turbine for future Chinese powerplants. The cost and performance of various designs were estimated using the commercial software GT PRO. Improved GTCC output will increase the system efficiency which may induce total investment and will certainly increase the cumulative cash which then will induce the cost and the payback period. The relative annual fuel output increases almost in proportion to the relative GTCC output. China should select the gas turbine that provides the most economical output according to its specific conditions. The analysis shows that a GTCC power plant with a medium-sized 100 to 200 MW output gas turbine is the most suitable for Chinese investors.

Performance assessment of simple and modified cycle turboshaft gas turbines

This paper focuses on investigations encompassing comparative assessment of gasturbine cycle options.More specifically,investigation was caried out of technical performanceof turboshaft engine cycles based on existing simple cycle(SC)and its projected modifiedcycles for civil helicopter application.Technically,thermal efficiency,specific fuel consump-tion,and power output are of paramount importance to the overall performance of gas urbineengines.In course of carrying out this research,turbomatch software established at CranfieldUniversity based on gas turbine theory was applied to conduct simulation of a simple cycle(baseline)two-spool helicopter turboshaft engine model with free power turbine.Similarly,some modified gas urbine cycle configurations incoporating unconventional components,such as engine cycle with low pressure compressor(LPC)zero-staged,recuperated enginecycle,and intercooled/recuperated(ICR)engine cycle,were also simulated.In doing so,designpoint(DP)and off-design point(OD)performances of the engine models were established.Thepercentage changes in performance parameters of the modified cycle engines over the simplecycle were evaluated and it was found that to a large extent,the modified engine cycles withunconventional components exhibit better performances in terms of thermal efficiency andspecific fuel consumption than the traditional simple cycle engine.This research made use ofpublic domain open source references.

Performance analysis of cogeneration systems based on micro gas turbine(MGT),organic Rankine cycle and ejector refrigeration cycle

In this paper,the operation perfonnance of three novel kinds of cogeneration systems under design and off-design condition was investigated.The systems are MGT(micro gas turbine)+ORC(organic Rankine cycle)for electricity demand,MGT+ERC(ejector refrigeration cycle)for electricity and cooling demand,and MGT+ORC+ERC for electricity and cooling demand.The effect of 5 different working fluids on cogeneration systems was studied.The results show that under the design condition,when using R600 in the bottoming cycle,the MGT+ORC system has the lowest total output of 117.1 kW with a thermal efficiency of 0.334,and the MGT+ERC system has the largest total output of 142.6 kW with a thermal efficiency of 0.408.For the MGT+ORC+ERC system,the total output is between the other two systems,which is 129.3 kW with a thermal efficiency of 0.370.For the effect of different working fluids,R123 is the most suitable working fluid for MGT+ORC with the maximum electricity output power and R600 is the most suitable working fluid for MGT+ERC with the maximum cooling capacity,while both R600 and R123 can make MGT+ORC+ERC achieve a good comprehensive performance of refrigeration and electricity.The thermal efficiency of three cogeneration systems can be effectively improved under oredesign condition because the bottoming cycle can compensate for the power decrease of MGT.The results obtained in this paper can provide a reference for the design and operation of the cogeneration system for distributed energy systems(DES).

COGAS Propulsion for LNG Ships

Propulsion of liquefied natural gas (LNG) ships is undergoing significant change. The traditional steam plant is losing favor because of its low cycle efficiency. Medium-speed diesel-electric and slow-speed diesel-mechanical drive ships are in service, and more are being built. Another attractive alternative is combined gas and steam turbine (COGAS) drive. This approach offers significant advantages over steam and diesel propulsion. This paper presents the case for the COGAS cycle.

Preliminary Design, Drive-Cycle Simulation and Energy Analysis of a Hybrid Transit Bus

Modern metropolises are increasingly affected by air quality problems. Transportation is one of the largest sources of several pollutants emissions, such as nitrogen oxides (NOx) and carbon monoxide (CO). Today in the EU, vehicles' emissions are strictly limited by Euro 6 norm-Euro VI for heavy-duty vehicles-which is periodically upgraded. To match such limits, manufacturers are forced in developing new technologies to perform new sustainable vehicles design strategies, such as EVs and HEVs. Present work's aim is to provide the design of series-hybrid urban transportation bus, equipped with a novel thermal power unit, namely a small gas turbine, to exploit its cleaner combustion process in comparison with an ICE. The control logic is described, while the main drivetrain components are chosen, and suitable models from suppliers are selected as well. Then, some simulations of the resulting vehicle are performed on opportune drive cycles, using Advisor, a free software based on Matlab-Simulink environment, published by US' National Renewable Energy Laboratory (NREL). Two different final configurations are environmentally and economically analysed, with the thermal power unit being respectively fuelled by compressed natural gas (CNG) and liquefied petroleum gas (LPG). Both satisfy the Euro VI norms, showing a substantial emission reduction (-89% and -43% in CO and THC releases respectively) in comparison to pollutants' threshold values.

Process Flow Model of Combined High Temperature Fuel Cell Operated with Mixture of Methane and Hydrogen

One of the main challenges of biogas and syngas use as fuel in hybrid solid oxide fuel cell （SOFC） cycles is the variable nature of their composition, which may cause significant changes in plant performance. On the other hand, hydrogen is one of the main components in some types of gasified biomass and syngas. Therefore, it is vital to investigate the influences of hydrogen fraction in inlet fuel on the cycle performance. In this work, a steady-state simulation of a hybrid tubular SOFC-gas turbine （GT） cycle is first presented with two configurations： system with and without anode exhaust recirculation. Then, the results of the model when fueled by syngas, biofuel, and gasified biomass are analyzed, and significant dependency of system operational parameters on the inlet fuel composition are investigated. The analysis of impacts of hydrogen concentration in the inlet fuel on the performance of a hybrid tubular SOFC and gas turbine cycle was carried out. The simulation results were considered when the system was fueled by pure methane as a reference case. Then, the performance of the hybrid SOFC-GT system when methane was partially replaced by H2 from a concentration of 0% to 95% with an increment of 5% at each step was investigated. The system performance was monitored by investigating parameters like temperature and flow rate of streams in different locations of the cycle; SOFC and system thermal efficiency; SOFC, GT, and cycle net and specific work; air to fuel ratio; as well as air and fuel mass flow rate. The results of the sensitivity analysis demonstrate that hydrogen concentration has significant effects on the system operational parameters, such as efficiency and specific work.

Life cycle evaluation of an intercooled gas turbine plant used in conjunction with renewable energy

The life cycle estimation of power plants is important for gas turbine operators.With the introduction of wind energy into the grid,gas turbine operators now operate their plants in Load–Following modes as back-ups to the renewable energy sources which include wind,solar,etc.The motive behind this study is to look at how much life is consumed when an intercooled power plant with 100 MW power output is used in conjunction with wind energy.This operation causes fluctuations because the wind energy is unpredictable and overtime causes adverse effects on the life of the plant–The High Pressure Turbine Blades.Such fluctuations give rise to low cycle fatigue and creep failure of the blades depending on the operating regime used.A performance based model that is capable of estimating the life consumed of an intercooled power plant has been developed.The model has the capability of estimating the life consumed based on seasonal power demands and operations.An in-depth comparison was undertaken on the life consumed during the seasons of operation and arrives at the conclusion that during summer,the creep and low cycle life is consumed higher than the rest periods.A comparison was also made to determine the life consumed between Load–Following and stop/start operating scenarios.It was also observed that daily creep life consumption in summer was higher than the winter period in-spite of having lower average daily operating hours in a Start–Stop operating scenario.

Resource and waste quantification scenarios for wind turbine decommissioning in the United Kingdom

Wind power produces more electricity than any other form of renewable energy in the United Kingdom(UK)and plays a key role in decarbonisation of the grid.Although wind energy is seen as a sustainable alternative to fossil fuels,there are still several environmental impacts associated with all stages of the lifecycle of a wind farm.This study determined the material composition for wind turbines for various sizes and designs and the prevalence of such turbines over time,to accurately quantify waste generation following wind turbine decommissioning in the UK.The end of life stage is becoming increasingly important as a rapid rise in installation rates suggests an equally rapid rise in decommissioning rates can be expected as wind turbines reach the end of their 20-25-year operational lifetime.Waste data analytics were applied in this study for the UK in 5-year intervals,stemming from 2000 to 2039.Current practices for end of life waste management procedures have been analysed to create baseline scenarios.These scenarios have been used to explore potential waste management mitigation options for various materials and components such as reuse,remanufacture,recycling,and heat recovery from incineration.Six scenarios were then developed based on these waste management options,which have demonstrated the significant environmental benefits of such practices through quantification of waste reduction and greenhouse gas(GHG)emissions savings.For the 2015-2019 time period,over 35 kilotonnes of waste are expected to be generated annually.Overall waste is expected to increase over time to more than 1200 kilotonnes annually by 2039.Concrete is expected to account for the majority of waste associated with wind turbine decommissioning initially due to foundations for onshore turbines accounting for approximately 80%of their total weight.By 2035-2039,steel waste is expected to account for almost 50%of overall waste due to the emergence of offshore turbines,the foundations of which are predominantly made of steel.

燃气-蒸汽联合循环发电机组轴系配置的思考

燃气-蒸汽联合循环发电机组因高效、节能、环保而越来越受到重视, 为此, 从我国当前大力发展燃气-蒸汽联合循环发电机组的实际情况出发, 全面分析联合循环机组轴系的配置型式及其影响, 重点比较了单轴和多轴“2拖1”机组在设备投资、占地面积、建设周期、起动停机、功率和效率、检修和控制系统方面的优缺点, 为燃气-蒸汽联合循环发电新机组建设的轴系配置提供参考。

大型联合钢铁企业低中热值煤气发电综合利用的优化分析

大型联合钢企的副产品低、中热值煤气不是洁净高能燃料,由此建成的煤气蒸汽联合循环机组要比天然气机组效率低8%-10%,排放特性与BTG型机组类似,且有较高投入、较高维护成本、较低可用率及不能适应变负荷运行等,难以满足电网AGC的要求。分析了可燃用低中热值的各种常规容量下的BTG类型与GTCC类型发电机组的经济特性与技术特性,根据东南沿海燃料价格高昂的实际情况,认为对低热值煤气BFG,以350 MW以上大型混烧BTG方式发电是较优的,高炉煤气放散可以接近零、安全可靠、成本较低、排放较少、对各种波动的煤气流量适应性更强,有利于投资方与当地电网。对COREX工艺大型联合钢企,以GTCC为主力是较好的方案。对天然气价格较低、COG/LDG富余较多的地方,结果不同。建议大型联合钢企副产品低、中热值煤气发电,要因地置宜,要根据煤气富余量、燃料价格、用电需求、环境与气候、投资与维护、综合实际供电成本等诸方面综合论证,以得出理性的优化方案。