Conventional Steam Power Plant Research Articles

CFD modelling and analysis of a radial ORC turbine with backswept rotor blades

Abstract Global electricity demand has steadily risen over the past five decades due to increased industrialization and improved accessibility worldwide. Addressing this escalating demand requires expanding electricity production, achievable through adopting renewable energy sources or enhancing production efficiency. Organic Rankine Cycle (ORC) power systems offer a promising solution for efficient electricity generation by utilizing organic fluids with lower critical parameters. Unlike conventional steam power plants, ORC systems operate at lower temperatures, making them adaptable to various applications. The efficiency of ORC power systems heavily relies on the design and performance of their turbines. This study focuses on modelling and analyzing the ORC turbine using Computational Fluid Dynamics (CFD) techniques, specifically employing a radial-inflow design with backswept rotor blades. Geometric parameters were derived from a simplified zero-dimensional (0-D) turbine model developed in MATLAB. CFD modelling was conducted using ANSYS software, integrating the BladeGen module for turbine geometry generation and the TurboGrid toolbox for mesh creation. Comparative analysis with the 0-D design method validated the accuracy of the CFD turbine modelling and the achievement of desired operational parameters. This research underscores the potential of CFD techniques in optimizing ORC turbine design thus allowing to achieve efficient electricity generation, contributing to the advancement of sustainable energy technologies.

An assessment of renewable energy generation in a conventional steam power plant with geothermal feedwater preheating

Hybrid steam power plant with geothermal feedwater preheating enables conversion of low temperature geothermal resources into electricity. The paper presents results of calculation of some performance parameters for 200 MWe fossil power unit associated with geothermal well. The paper gives separation rule of renewable energy from conventional one at hybrid power plant output. An influence of geothermal fluid temperature on hybrid power plant performance is discussed in a study and illustrated in several charts.

Enhancing conventional steam power plant performance through feed water heating repowering

ABSTRACT Repowering of old steam power plants is a viable solution to increase power and improve efficiency. This study investigates the feasibility of feed water heating repowering for the Neka steam power plant by considering the influences of steam mass flow rate on the condenser performance and the heat rate of the new cycle. Energy and exergy analyses were conducted using the first and second laws of thermodynamics and heat transfer relations in each scheme. The effect of increasing the steam mass flow rate on the performance of the condenser and the cycle was also investigated. The repowered cycle was simulated using Thermoflow software, and the results were validated with small errors. The results showed that replacing low and high-pressure heaters with new heat exchangers increased the power of the steam unit and the repowered cycle, energy, and exergy efficiencies by 15.7%, 49.3%, 5.93%, and 2.17%, respectively. Although the condenser pressure increased by 19 millibars, leading to a 0.63% increase in the heat rate, the total heat rate of the repowered cycle improved by 4.62%. Overall, the findings demonstrate that feed water heating repowering can be an effective strategy to increase the efficiency and power of conventional steam power plants.

Performance assessment of a solar aided dual-fuel supercritical steam power plant for power boosting under different operating loads

Fuel supply due to political conflict and decarbonization is the most challenging standup for the energy sector and electricity generation. Therefore, the present study introduces a thermodynamic analysis for a modeled supercritical solar aided power plant (SAPP) using two types of fuel at different operating loads, i.e., 50%, 75%, and 100%. The proposed SAPP is investigated in terms of energy, exergy, and steam flow rates to verify the advantages of using SAPP over conventional power plants. In the SAPP, the condensate water passes into the heat exchangers using a working fluid of Therminol VP-1. Additionally, the turbine extraction steam at 100% load is minimized, and it is eliminated at 50% and 75% loads. The results show that the recovered amount of feed water extraction increases the mechanical power for SAPP-based natural gas in comparison with the conventional supercritical steam power plant by 16, 21, and 9.7% at an operating load of 50%, 75%, and 100%, respectively. Consequently, SAPP-based natural gas maintains an increase in the overall energy efficiency compared with the CPP of 13.7, 17, and 1.9% at an operating load of 50%, 75%, and 100%, respectively. As well, the mechanical power of the SAPP-based oil fuel increases compared with CPP by 25.7, 27.6, and 17.4% at 50%, 75%, and 100% loads, respectively. Whereas, the overall energy efficiency enhances due to using the SAPP-based oil fuel compared with that of the CPP by 20.6, 21.9, and 7% at a load of 50%, 75%, and 100%, respectively.

Brief Study on Installation of Floating Solar Power Plant for Sustainable Energy Generation at Ladakh

The need for sustainable power generation is well understood by human kind, which has encouraged several initiatives across government, private, community and individual level to move towards a clean-renewable energy based sustainable environment. As compared to urban and semi urban region, rural and remote areas exhibit high levels of pollution from individual power generation systems like diesel generators for agriculture and other day to day activities. Particularly, electricity supply to some remote locations have always remained a challenge owing to various factors such as connectivity, transmission losses and weather conditions. Installation of local power generation systems has several advantages in providing electricity supply to these locations. Renewable energy harnessing systems using solar, wind, and geothermal energy sources may have higher chance of ease of installation and efficient operation at remote locations compared to conventional steam or thermal power plants. Leh, Ladakh is one such remote region, highly dependent on small hydro power stations and diesel generators for its energy demand. The low temperature climatic conditions, increasing tourism and recreational activities in this region demands high energy, exerting pressure on the common electricity supply chain. This article aims to conduct a preliminary study on the potential sites available for installing floating solar power plants and estimation of energy generation capability at Ladakh region.

Exergoeconomic and environmental performance assessment of the solar-assisted thermal power plant

At a time when global climate change is imposing a mounting challenge to the economy of the world, conventional coal-fired steam power plants are under tremendous pressure to meet severe climatic protocols for achieving the set sustainable development goals. Therefore, this research work investigates the energetic, exergetic, economical and environmental performance of a 330 MWe sub-critical coal-fired thermal power plant integrated with solar thermal energy. The results of energetic and exergetic analyses show that the highest energy efficiency of 38.04% and the highest exergy efficiency of 36.22% are attained for Option 3. The environmental analysis performed using the fuel-saving approach shows that the maximum reduction in coal consumption and CO2 emissions also corresponds to Option 3. The economic analysis showed that for all three replacement options, the levelised cost of electricity is 4.52, 4.47, and 4.63 (Cents/kWh) and the simple payback period is 3.4, 3.3 and 3.6 (years), respectively.

Full repowering of existing fuel-oil fired power plant: Modeling and performance evaluation

Increasing electricity demand as a result of industrial development brings with it the need for larger installed power generation capacity. However, existing regulations, capital costs of new equipment, time-dependent constraints, and public opposition against building new power plants pose a strong challenge for greenfield power generation projects. These compelling factors have caused the repowering concept to gain importance again in recent years. Ambarli Repowering Project is a “Full Repowering by Conversion to Combined Cycle Power Plant” project that is the first of its kind in Turkey and is equaled in magnitude and complexity by only a handful of worldwide examples. In this context existing heavy fuel–oil fired steam power plant was repowered by conversion to natural gas fired combined cycle power plant. Here, in this paper, initial performance calculations of the existing steam turbine and achievable power output after rehabilitation are presented. Parameters such as inlet temperature, pressure, and steam mass flow are defined as boundary conditions for the model of the repowered Ambarli Power Plant that allows a comprehensive evaluation of the performance of the combined cycle power plant. An in-depth real case study is conducted to validate the outputs of the developed model by comparing them with the official performance test results. Results show that the total capacity of a conventional steam power plant can be increased by 203%, while the increase in heat rejection from the condenser is only 25%. Moreover, it is found that repowering has significant positive environmental effects such as reduction of NOX, SOX, and CO2 emissions in addition to economic benefits. Therefore, it is expected that this unique study, which has been validated with official performance tests, will shed light on similar projects to be made in the future.

Emission control exploring the energy and exergy analysis for turbines of a 500 MW coal-based conventional power plant

This work considers an analysis using energy and exergy of turbines for a coal-based conventional steam power plant of 500 MW under the Damodar Valley Corporation (DVC), India to optimize its operating conditions. An effort has also been made to control the environmental emission of different gases from the plant. Hence, a control volume is assumed consisting of a high-pressure turbine (HPT), an intermediate turbine (IPT), and a low-pressure turbine (LPT) of the plant. A thermodynamic-based model is considered in determining the performance of turbines in the power cycle under various unit loads (60%, 80%, and 100%). This analysis includes a prediction of energy, then exergy, and related irreversibility of flow stream to and from said control volume under the unit load conditions. The improvement in heat rate of the turbine with an increase in load is also estimated. As found, the heat rate reaches a minimum when the plant operates at higher unit loads (80% and 100%), which is an economical condition of operation. With the basis of the improved heat rate, a reduction in coal consumption, plant ash generation, also SO2 and CO2 emissions by the plant are estimated.

Conversion of steam power plant into cogeneration unit - Case study

One of possible solutions leading to the increase of steam power plant thermal efficiency is its conversion into a cogeneration unit. However, it requires the heat recipient to be on-site and, if so, it may be done by implementation of absorption heat pump (AHP) technology with low temperature waste heat recovery and utilization. The paper presents results of an analysis of benefits resulting from implementation of absorption heat pump into the steam power plant for recovery of low temperature waste heat, due to additional demand for heat delivery to dedicated recipient (DHR). The demand for heat along the whole year was assumed and the calculations were performed for two cases. In the first case, which was called the reference case, the heat was produced by dedicated heat exchanger (DHX) fed with steam taken from the pipeline between the medium and low-pressure turbine sections (MPLPP). In the second case, absorption heat pump (AHP) as the main unit for heat production and recovery was assumed. However, due to insufficient heat production in some conditions, peak heat exchanger (PHX) placed directly behind the heat pump was considered. Both heat pump and pick heat exchanger were fed with steam taken from MPLPP, however, due to the AHP requirements the stem was mixed with hot water taken from hot water tank to achieve the steam saturation state. Results of calculations performed show that implementation of a heat recuperation by absorption heat pump implemented to conventional steam power plant increases the overall efficiency of cogeneration system, but at the same time it causes the electricity production to decrease. Moreover, the production of heat by absorption heat pump has lower impact on the electricity generation compared to generation of heat by conventional heat exchanger. If reference power plant without heat production is considered, due to the heat pump implementation the electricity production decreases of about 1.32% for heat production with dedicated heat exchanger, and of about 0.89% for absorption heat pump with peek heat exchanger respectively. It means that, owing to implementation of AHP instead of DHX with the same heat production, the power plant may generate more than 0.4% of total electricity produced.

Steam Turbine—Quo Vadis?

In this article, a close look is taken at the state-of-the-art in steam turbine and steam (Rankine) cycle technology within the framework of conventional steam and gas turbine combined cycle power plants, specifically, the bottoming steam (Rankine) cycle of the latter. Using the second law of thermodynamics and the concept of exergy as a guide, cycle and technology factors are calculated to provide a simple but precise (and unassailable) yardstick to assess where the technology was, where it is at present, and how much farther it can go. In addition, the study takes a critical look at an emerging technology, supercritical CO2 cycle, that is being touted as a serious contender for steam turbine’s place in the fossil fuel-fired electric power generation portfolio—as a standalone system or as a waste heat recovery capacity (i.e., combined cycle).

A comparison between a natural gas power plant and a municipal solid waste incineration power plant based on an emergy analysis

This paper performs an emergy analysis (EmA) to compare two real power plants include a conventional natural gas steam power plant (NGPP) with one that burns municipal solid waste (MSWPP). For this purpose, the EmA is used to investigate the sustainability, renewability, environmental impacts, and economic issues. The capacity of the NGPP and MSWPP are 247.5 and 3 MW, respectively. Results from this study show that the percent of renewability (PR) and emergy sustainability index (ESI) of the MSWPP are much more than those of the NGPP. The PR and ESI of the MSWPP are 46.81 and 1.65, while for the NGPP are 5.01 and 0.05, respectively. It is proved that the MSWPP is more efficient and has the better environmental impacts compared to the NGPP. Moreover, a hypothetical MSWPP with the same electricity output of the NGPP is studied using the EmA. A more efficient system with the higher PR and ESI is observed compared to the other case studies. Beside of these advantages, use of the MSW has other benefits such as reducing the greenhouse gases released in the atmosphere, saving fossil fuels, low land area required compared to the landfill, speed and ease of disposal, and production of clean and useful ash.

Solar-assisted steam power plant retrofitted with regenerative system using Parabolic Trough Solar Collectors

This work investigates the performance of a conventional steam power plant retrofitted with a solar-assisted regenerative system using Parabolic Trough Solar Collectors (PTC). The solar collectors were used to compensate for the effect of removing Low-Pressure (LP) turbine extractions without changing other elements of a 300 MW power plant unit during peak load operations. The steam power plant, located in Kuwait, receives high levels of solar irradiation. Modeling of the solar-assisted regenerative system using PTC is simulated for Kuwait’s weather conditions. Results of the system analysis show that removing the LP turbine extractions enhanced the performance of the steam power plant by 9.8 MW, with an optimum PTC aperture area equal to 25,850 m2. A techno-economic analysis was used to estimate the Levelized Cost of Energy (LCOE). Compared to an equivalent photovoltaic solar plant, the optimum aperture area and LCOE for the PTC solar plant were found to be less by 45% and 44%, respectively. When compared to an equivalent conventional steam turbine, the solar-assisted steam power plant decreased cost by 56% over the lifecycle of 25-years.

Analysis and performance assessment of coal-fired based integrated energy system for multigeneration

ABSTRACT The performance analysis of a multigeneration (MG) energy system integrated into a conventional coal-fired power plant was evaluated and discussed according to the data measured in the existing steam power plant. The multigeneration energy system in the present work consists of four subsystems, namely Organic Rankine Cycle (ORC), Vapor Compression Refrigeration (VCR) System, Thermal Vapor Compression Desalination Plant (TVCDP) and Greenhouse Heating (GH) System. The thermodynamic analysis was performed through energy and exergy analyses associated with the efficiencies of the subsystem as well as the multigeneration plant. In addition, environmental impact analysis was carried out to calculate CO2 emission of the overall system to evaluate the effect of emissions caused by the energy systems. The results revealed that when the conventional steam power plant became multigeneration, the exergy efficiency increased from 39.1% to 39.84% and energy efficiency increased from 41.5% to 42.29%. Four subsystems were integrated into the existing steam power plant to reduce CO2 emissions from 230 kg/MWh to 225 kg/MWh.

Energy, Exergy and Economic Feasibility Analyses of a 60 MW Conventional Steam Power Plant Integrated with Parabolic Trough Solar Collectors Using Nanofluids

The present study focuses on the detailed technical and cost-effective feasibility analyses of a 60 MWe steam power plant integrated with parabolic trough solar collectors. Aluminum oxide (Al2O3) nanoparticles are mixed with thermal oil to be used as a heat transfer fluid in the collector loops. The electric power is generated using steam Rankine cycle. For this purpose, the steam turbine of 60 MWe production capability of Teknecik power plant located in Northern Cyprus has been analyzed and an integrated solar steam turbine system is presented which generates electric power. Detailed energy and exergy assessment of the solar thermal plant is carried out. The important parameters are examined including overall energy and exergy efficiencies, exergy destruction rate and system performance by varying direct normal irradiation (DNI), mass flow rate of the collector, ambient and inlet temperatures. Furthermore, thermal power available from the solar field at various solar multiples is assessed, and levelized energy cost has been calculated. Results show that turbines are the main source of exergy destruction (63855 kW) followed by feedwater heaters and boiler. Overall energetic and exergetic efficiencies of the system are observed to be 22.64 and 23.83%, respectively. The integration of PTC system with conventional plant results in a reduction in fuel consumption which significantly brings down the CO2 emissions by almost 33%.

Thermodynamic investigation of organic Rankine cycle energy recovery system and recent studies

Recently, new environment-friendly energy conversion technologies are required for using energy resources valid to power generation. Accordingly, low-grade heat sources as solar heat, geothermal energy, and waste heat, which have available temperatures ranging between 60 and 200?C, are supposed as applicants for recent new generation energy resources. As an alternative energy source, such low-grade heat sources usage generating electricity with the help of power turbine cycles was examined through this study. Such systems have existing technologies applicable at low temperatures and a compact structure at low cost, however, these systems have a low thermal efficiency of the Rankine cycles operated at low temperatures. An organic Rankine cycle is alike to a conventional steam power plant, except the working fluid, which is an organic, high molecular mass fluid with a liquid-vapor phase change, or boiling point, at a lower temperature than the water-steam phase change. The efficiency of an organic Rankine cycle is about between 10% and 20%, depending on temperature levels and availability of a valid fluid.

Use of hot supercritical CO2 produced from a geothermal reservoir to generate electric power in a gas turbine power generation system

CO2 capture and sequestration in deep saline aquifers is widely considered to be a leading option for controlling greenhouse gas emissions. One such possibility involves injection of supercritical carbon dioxide into a high-permeability geothermal reservoir. In addition to the benefit of sequestering the CO2 in the reservoir, the CO2 can be used to mine geothermal heat for utilization above ground. This paper describes one of the options for generating power from hot supercritical CO2 obtained from CO2 production wells connected to a geothermal reservoir, where the original source of the CO2 is CO2 captured from fossil-fired power plants or industrial processes. The cost of power generated using CO2 produced from a geothermal reservoir with a gas turbine generation system is compared to the cost of generating power from a conventional geothermal steam power plant.

Solar feed water heating feasibility for a conventional steam power plant

Technical and economic feasibility of heating feed water through parabolic trough solar collectors has been discussed in this paper. This integration of solar energy with steam plants saves extraction steam, thus increasing turbine output. The study is based on a 210 MW Heavy fuel oil (HFO) fired power plant for Karachi weather conditions. Pressurized hot water storage system is used as heat storage medium. TRNSYS software is used to find out useful energy collected through parabolic trough collectors and heat storage in pressurized hot water storage system. Life cycle savings (LCS) using HFO prices of two different periods i.e. May, 2014 (higher HFO price) and Feb., 2016 (lower HFO price) are calculated and compared. Effect of change in HFO price on LCS is also presented. Integration of higher pressure FWH with solar energy is found more feasible in terms of LCS as compared to lower pressure FWH. Same methodology can be deployed on other plants around the globe to determine LCS and economic feasibility.

District Heating and Power Generation Based Flue Gas Waste Heat Recovery

In this study, integration of appropriate renewable methods are going to be applied on conventional coal fired steam power plant which has 660 MW full load capacity and including 4 Turbines (1 HP,1 IP and 2 LP), one Benson type boiler and having multi pre heater stages for each unit. Steam parameters are 177 Bar and 541 o C super-heater section and 50 bar 539 o C for re-heater section. Primary fuel is coal except for startup and shut down operations. It is aimed by retrofitting some renewable energy methods on existing power plant, thus eliminating conventional type power plants adverse effects on thermodynamically, environmental and economic issues. One of the most important issue of conventional steam power plant operation is waste heat recovery management. A widespread techniques has been developed on this topic. It's possible to handle low grade heat by considering thermodynamic and environmental facts and also dealing with restrictions and opportunities after fulfilled feasibility study. In this study, it is being proposed waste heat recovery by combining Organic-Rankine Cycle (ORC) with steam-Rankine cycle at available section. Brief summary of operation is ORC takes place after regenerative air preheater section and the target is to utilize waste heat of flue gas either via district heating or power generation up to few MW values. Depending upon the calculation and results additional modifications can further be needed as well.

THERMODYNAMICAL ANALYSIS OF HIGH-PRESSURE FEED WATER HEATER IN STEAM PROPULSION SYSTEM DURING EXPLOITATION

Nowadays diesel engines prevail as ship propulsion. However, steam propulsion is still primary drive for LNG carriers. In the presented paper high-pressure feed water heater was analyzed, as one of the essential components in LNG carrier steam propulsion system. Measurements of all operating parameters (fluid streams) at the analyzed heat exchanger inlets and outlets were performed. Change of the operating parameters was measured at different steam system loads, not at full load as usual. Through these measurements was enabled the insight into the behaviour of the heat exchanger operating parameters during the whole exploitation. The numerical analysis was performed, based on the measured data. The changes in energy and exergy efficiency of the heat exchanger were analyzed. Energetic and exergetic power inputs and outputs were also calculated, which enabled an insight into the change of energetic and exergetic power losses of the heat exchanger at different steam system loads. Change in energetic and exergetic power losses and operating parameters, which have the strongest influence on the high-pressure feed water heater losses, were described. Analyzed heat exchanger was compared with similar heat exchangers in the base loaded conventional steam power plants. From the conducted analysis, it is concluded that the adjustment and control modes of these high- pressure heat exchangers are equal, regardless of whether they were mounted in the base loaded conventional steam power plants or marine steam systems, while their operating parameters and behaviour patterns differ greatly.

Modeling and analysis of process configurations for hybrid concentrated solar power and conventional steam power plants

Availability and flexibility of variable renewable energy production can be increased without thermal energy storages by integrating intermittent energy production with load following energy production. This paper focuses on modeling, analysis and comparison of three hybrid configurations for concentrated solar power and conventional steam power plants. The configurations include feedwater preheating, cold reheat line and high pressure turbine concepts, in which linear Fresnel collector solar field with direct steam generation is applied to generate steam parallel with the steam boiler. The modeling is conducted using dynamic simulation software Apros®, which enables investigation of the system operation under varying process conditions. In particular, the focus is on the comparison of thermal load balance and interdependencies of the subsystems. In addition, the focus is on increasing the solar contribution, as the solar share is low in current commercial concepts. As a main conclusion, the more solar steam is fed to the system, the more different turbine sections and heat surfaces of the steam boiler are imbalanced, which leads to challenging system design. In addition, the maximum fuel and emission savings are not only determined by the achievable solar share, but also by the hybrid process design. The design of the hybrid system has to be optimized and modified according to the configuration in order to achieve higher peak solar share and fuel and emission savings than 20% achieved in this study.