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.

Performance of Regenerative Gas Turbine Power Plant

This study aims to investigate the effect of regeneration on the output power and the thermal efficiency of the gas turbine power plant. The effect of ambient air temperature, regeneration effectiveness, and compression ratio on the cycle thermal efficiency was also investigated. An existed gas turbine power plant of AL ZAWIA is used as a base in this study, and the calculations were carried out utilizing MATLAB code. This intensive parametric study was conducted based on the fundamental of thermodynamics and gas turbine relations considering the effect of the operation conditions (ambient air temperature, regeneration effectiveness and compression ratio). It was found that adding regeneration to the simple gas turbine cycle results in an increase in the thermal efficiency of cycle. It was also found that including regeneration in gas turbine cycle results in an increase in the output power of the cycle, and it results in a decrease in the exhaust gas temperature. The effect of the regeneration effectiveness was also predicted. It was found that increasing of regeneration effectiveness results in an increase in the output power of the cycle. It was also found that the cycle thermal efficiency increases with increasing of the regenerative effectiveness. The effect of ambient air temperature was also predicted. Increasing of the ambient air temperature results in a decrease in the thermal efficiency of the cycle.

Performance of a 270 MW Gas Power Plant Using Exergy and Heat Rate

The performance of a 270 MW (9 × 30 MW) AES Corporation barge mounted gas turbine power plant in Nigeria is evaluated using the heat rate and entropy generation by the components of the plant to characterize the irreversibility in each component when operating at different loads between 90% and 25%. The power plants have the peculiarity that three of the plants were supplied by three (3) different Original Equipment Manufacturers (OEM);A, B and C. This study is sequel to the fact that the gas turbines were the first independent power plants in the country and after more than fifteen years of operation, it is reasonable to evaluate the performance of the major components. By analyzing the thermodynamic performance of these components, the study demonstrates the utility value of exergy efficiency as an important parameter in the evaluation of major components in a gas power plant. Exergy efficiency is shown to be an important parameter in ranking the power plant components, identifying and quantifying the possible areas of reduction in thermodynamic losses and improvement in efficiencies. A new relationship is derived to demonstrate the correlation between the exergy efficiency and the heat rate of a 30 MW gas power plant. The prediction of the derived relationship correlates well with the observed operational performance of the 30 MW power plants. The combustion chamber in each of the plants provides the maximum exergy destruction during operation. Its exergy efficiency is shown to exhibit good correlation with its energy efficiency and the plant rational exergy. The implication is that from an operational and component selection viewpoint in the specifications of a gas power plant, knowledge of the Heat Rate which is usually provided by the OEM is adequate to make a reasonable inference on the performance of some critical components of the plant.

Power and efficiency optimizations for an open cycle two-shaft gas turbine power plant

In finite-time thermodynamic analyses for various gas turbine cycles,there are two common models:one is closed-cycle model with thermal conductance optimization of heat exchangers,and another is open-cycle model with optimization of pressure drop(PD)distributions.Both of optimization also with searching optimal compressor pressure ratio(PR).This paper focuses on an open-cycle model.A two-shaft open-cycle gas turbine power plant(OCGTPP)is modeled in this paper.Expressions of power output(PP)and thermal conversion efficiency(TCE)are deduced,and these performances are optimized by varying the relative PD and compressor PR.The results show that there exist the optimal values(0.32 and 14.0)of PD and PR which lead to double maximum dimensionless PP(1.75).There also exists an optimal value(0.38)of area allocation ratio which leads to maximum TCE(0.37).Moreover,the performances of three types of gas turbine cycles,such as one-shaft and two-shaft ones,are compared.When the relative pressure drop at the compressor inlet is small,the TCE of third cycle is the biggest one;when this pressure drop is large,the PP of second cycle is the biggest one.The results herein can be applied to guide the preliminary designs of OCGTPPs.

Prime Energy Challenges for Operating Power Plants in the GCC

There is a false notion of existing available, abundant, and long lasting fuel energy in the Gulf Cooperation Council (GCC) Countries;with continual income return from its exports. This is not true as the sustainability of this income is questionable. Energy problems started to appear, and can be intensified in coming years due to continuous growth of energy demands and consumptions. The demands already consume all produced Natural Gas (NG) in all GCC, except Qatar;and the NG is the needed fuel for Electric Power (EP) production. These countries have to import NG to run their EP plants. Fuel oil production can be locally consumed within two to three decades if the current rate of consumed energy prevails. The returns from selling the oil and natural gas are the main income to most of the GCC. While NG and oil can be used in EP plants, NG is cheaper, cleaner, and has less negative effects on the environment than fuel oil. Moreover, oil has much better usage than being burned in steam generators of steam power plants or combustion chambers of gas turbines. Introducing renewable energy or nuclear energy may be a necessity for the GCC to keep the flow of their main income from exporting oil. This paper reviews the GCC productions and consumptions of the prime energy (fuel oil and NG) and their role in electric power production. The paper shows that, NG should be the only fossil fuel used to run the power plants in the GCC. It also shows that the all GCC except Qatar, have to import NG. They should diversify the prime energy used in power plants;and consider alternative energy such as nuclear and renewable energy, (solar and wind) energy.

Performance characterization of different configurations of gas turbine engines

This paper investigates the performance of different configurations of gas turbine engines.A full numerical model for the engine is built.This model takes into account the variations in specific heat and the effects of turbine cooling flow.A lso,the model considers the efficiencies of all component,effectiveness of heat exchangers and the pressure drop in relevant components.The model is employed to compare the engine performances in cases of employing intercooler,recuperation and reheat on a single spool gas turbine engine.A comparison is made between single-spool engine and two-spool engine with free power turbine.Also,the performance of the eng ine with inter-stage turbine burner is investigated and compared with engine employing the nominal reheat concept.The engine employing inter-stage turbine bumers produces superior improvements in both net work and efficiency over all other configurations.The effects of ignoring the variations on specific heat of gases and turbine cooling flow on engine performance are estimated.Ignoring the variation in specific heat can cause up to 30%difference in net specific work.The optimum locations of the intercooler and the reheat combustor are detemined using the numerical model of the engine.The maximum net specific work is obtained if the reheat combustor is placed at 40%of the expansion section.On the other hand,to get maximum efficiency the reheat combustor has to be placed at nearly 10%-20%of the expansion section.The optimum location of the intercooler is almost at 50%of the compression section for both maximum net specific work and efficiency.

Identifying Critical Components of Combined Cycle Power Plants for Implementation of Reliability-centered Maintenance

Maintenance scheduling and asset management practices play an important role in power systems,specifically in power generating plants.This paper presents a novel riskbased framework for a criticality assessment of plant components as a means to conduct more focused maintenance activities.Critical components in power plants that influence overall system performance are identified by quantifying their failure impact on system reliability,electric safety,cost,and the environment.Prioritization of plant components according to the proposed risk-based method ensures that the most effective and techno-economic investment decisions are implemented.This,in turn,helps to initiate modern maintenance approaches,such as reliability-centered maintenance(RCM).The proposed method is applied to a real combined cycle power plant(CCPP)in Iran,composed of two gas turbine power plants(GTPP)and one steam turbine power plant(STPP).The results demonstrate the practicality and applicability of the presented approach in real world practices.

基于AMESim的燃燃联合动力装置并车仿真研究

针对燃燃联合动力装置(COGAG)建立仿真试验系统,以燃燃联合动力装置为研究对象,仿真平台采用仿真软件AMESim,对动力装置的各个部件进行建模采用的是模块化的建模方法,建立了燃燃联合动力装置系统的仿真模型,利用该模型对单台燃机的动态过程、两台燃机的并车过程进行了仿真和验证。此外,将AMESim中的仿真模型与MATLAB/SIMULINK中的仿真模型相对比,表明AMESim软件能够较好地完成物理模拟,并使研究者从繁杂的数学模型中解脱出来。

燃机快速并车过程的冲击载荷特性分析及实验研究

[目的]为了获取燃燃联合动力(COGAG)装置在快速并车解列过程中的冲击载荷及轴系动态响应,提出一种理论计算方法。[方法]根据同步自动换挡(SSS)离合器啮合过程中各部件的力学关系,建立离合器的动力学分析模型,并开展燃燃联合动力装置并车过程的动力学仿真和台架实验。[结果]仿真结果表明:在阻尼油腔作用的时刻,离合器螺旋花键上产生了明显的扭矩冲击,同时使离合器两端轴系产生了很强的扭矩动态响应;离合器棘轮棘爪位置的随机性将导致扭矩冲击峰值和轴系动态响应在一定范围内波动。台架实验验证了并车冲击载荷计算方法的正确性,其最大和最小扭矩的响应幅值与理论计算偏差分别为3.56%和8.86%。[结论]对于燃机快速并车过程中的扭矩冲击影响,研究成果可为燃燃联合动力装置的运行安全性评估提供参考。

Improving Prediction Accuracy of a Rate-Based Model of an MEA-BasedCarbon Capture Process for Large-Scale Commercial Deployment

Carbon capture and storage （CCS） technology will play a critical role in reducing anthropogenic carbondioxide （CO2） emission from fossil-fired power plants and other energy-intensive processes. However, theincrement of energy cost caused by equipping a carbon capture process is the main barrier to its commer-cial deployment. To reduce the capital and operating costs of carbon capture, great efforts have been madeto achieve optimal design and operation through process modeling, simulation, and optimization. Accuratemodels form an essential foundation for this purpose. This paper presents a study on developing a moreaccurate rate-based model in Aspen Plus for the monoethanolamine （MEA）-based carbon capture processby multistage model validations. The modeling framework for this process was established first. The steady-state process model was then developed and validated at three stages, which included a thermodynamicmodel, physical properties calculations, and a process model at the pilot plant scale, covering a wide rangeof pressures, temperatures, and CO2 loadings. The calculation correlations of liquid density and interfacialarea were updated by coding Fortran subroutines in Aspen Plus. The validation results show that the cor-relation combination for the thermodynamic model used in this study has higher accuracy than those ofthree other key publications and the model prediction of the process model has a good agreement with thepilot plant experimental data. A case study was carried out for carbon capture from a 250 MWe combinedcycle gas turbine （CCGT） power plant. Shorter packing height and lower specific duty were achieved usingthis accurate model.

Exergy-energy analysis of full repowering of a steam power plant

A 320 MW old steam power plant has been chosen for repowering in this paper. Considering the technical conditions and working life of the power plant, the full repowering method has been selected from different repowering methods. The power plant repower- ing has been analyzed for three different feed water flow rates： a flow rate equal to the flow rate at the condenser exit in the original plant when it works at nominal load, a flow rate at maximum load, and a flow rate when all the extractions are blocked. For each flow rates, two types of gas turbines have been examined： V94.2 and V94.3A. The effect of a duct burner has then been investigated in each of the above six cases. Steam is produced by a double- pressure heat recovery steam generator （HRSG） with reheat which obtains its required heat from the exhaust gases coming from the gas turbines. The results obtained from modeling and analyzing the energy-exergy of the original steam power plant and the repowered power plant indicate that the maximum efficiency of the repowered power plant is 52.04%. This maximum efficiency occurs when utilizing two V94.3A gas turbines without duct burner in the steam flow rate of the nominal load.

Towards Energy Conservation in Qatar

Qatar energy consumptions are among the highest in the world, and can easily serve double the present population. Energy conservation is a must, as the energy resources are finite, and their consumptions are increasing at alarming rates. The country depends on desalted seawater, which consumes extensive amounts of energy, and is produced by using the least energy efficient desalting system. The desalination process is vulnerable to many factors, and strategic water storage needs to be built. The high energy consumptions are ruining the air and marine environments. Several suggestions are introduced to conserve energy in the Cogeneration Power Desalting Plants (CPDP), by moving to replace the Multi Stage Flash (MSF) desalting system by the energy efficient Seawater Reverse Osmosis System (SWRO);fully utilizing the installed power capacity to desalt water in winter, when electric power load is low, and during summer non-peak hours for strategic water storage;and modifying the simple Gas Turbines (GT) Power cycle plants to GT combined cycle to raise the Electric Power (EP) generation efficiency (to about 50%).