Heat Recovery Steam Generator Research Articles

Effect of Exhaust Gas Flow Rate in Heat Recovery Steam Generator Duct Using Computational Fluid Dynamic Approach

Effect of Exhaust Gas Flow Rate in Heat Recovery Steam Generator Duct Using Computational Fluid Dynamic Approach

Energy and exergy analysis of a steam power plant to replace the boiler with a heat recovery steam generator

Energy and exergy analysis of a steam power plant to replace the boiler with a heat recovery steam generator

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.

Energy and exergy analysis of a steam power plant to replace the boiler with a heat recovery steam generator

Energy and exergy analysis of a steam power plant to replace the boiler with a heat recovery steam generator

Reliable AI models can reveal key processes of heat recovery steam generator operation in air pollutant emission

Artificial intelligence (AI) algorithms have been applied to air pollution prediction modeling, but assessment of their trustworthiness is lacking. This study aims to examine whether AI-based models can identify key operational processes of a Heat Recovery Steam Generator (HRSG) facility and predict the emission of target air pollutants, including nitrogen oxides (NOx), sulfur oxides (SOx), and total suspended particles (TSP). First, key operational variables are selected based on the feature importance of the Random Forest models (that is, data-driven input selection). Secondly, Bidirectional Long Short-Term Memory-based AutoEncoder (BiLSTM-AE) and Random Forest (RF) models with the data-driven input selection are trained and evaluated using multiple predictive performance metrics. Then, the BiLSTM-AE and RF models are trained and evaluated using the operational variables selected by experts. Results demonstrate that the data-driven and expertise-based methods select five common operational variables that are key factors to predict variations of target output variables. The results from the multi-metric evaluations show a skillful prediction of BiLSTM-AE and RF models for NOx and TSP, but not SOx. For TSP prediction, RF is more sensitive to the input selection method than BiLSTM-AE. This study underscores the dependency of the prediction skill of AI algorithm-based models on the target air pollutant and input selection method, and suggests the trustworthiness of selected key operational variables by RF's feature importance.

Comprehensive analysis of energy, exergy, economic, and environmental aspects in implementing the Kalina cycle for waste heat recovery from a gas turbine cycle coupled with a steam generator

This study introduces a transformative approach by integrating the Kalina Cycle System (KCS) within a cogeneration of heat and power (CHP) framework alongside a gas turbine (GT) cycle and a single-pressure heat recovery steam generator (HRSG). Through development of thermodynamic and thermo-economic models, a comprehensive assessment of the system's performance is conducted, emphasizing energy, exergy, and exergoeconomic considerations. The outcomes reveal a remarkable enhancement in both 1st and 2nd law efficiencies for the GT-HRSG/KCS-11 system compared to its conventional counterpart. Witnessing an ascent from 53.60 % to 54.31 % in efficiency and an increase from 50.59 % to 51.27 % in 2nd law efficiency underscores the profound impact of the proposed system. Furthermore, a parametric study scrutinizes the influence of diverse design parameters on critical objective functions, encompassing second law efficiencies and the total system cost rate. Findings spotlight the combustion chamber, heat recovery steam generator, and gas turbine as focal points of exergy destruction, revealing crucial insights for system optimization. The combustion chamber, heat recovery steam generator, and gas turbine emerge as pivotal contributors to the total cost rate, highlighting key areas for economic consideration. According to the results, the share of the environmental cost rates in the system cost rate is insignificant.

Determination of optimal total area of heat recovery steam generator

Heat recovery steam generator (HRSG) plays a critical role in recovering waste heat from exhaust gas in a combined cycle. The performance of the steam cycle in the combined cycle depends on total HRSG area. This paper presents a comprehensive study on the determination of the optimal total area of single-pressure HRSG considering various factors such as exhaust gas temperature, main steam temperature, main steam pressure, reheat steam pressure, and reheat steam temperature. The research methodology involves the development of a mathematical model of HRSG that considers the key parameters affecting the HRSG performance. It is shown that, for given exhaust gas temperature and total HRSG area, there exists the set of steam parameters that yields the maximum net power output of the steam cycle. Furthermore, the power output increases monotonically with total HRSG area. However, the power output increases at a decreasing rate as total HRSG area increases. The optimal total HRSG area is shown to depend on the unit selling price of electricity, the unit cost of heat exchanger, the capacity factor of the power plant, and the acceptable payback period for the investment in the installation cost of HRSG.

Energetic and exergetic performances of a multi‐effect desalination unit driven by a gas turbine

AbstractDesalination can provide additional water resources in water‐stressed zones and also in zones suffering from water pollution or insufficient/overexploited groundwater. This study carried out the energy and exergy assessments of a multi‐effect desalination unit driven by a gas turbine based on the specific exergy cost (SPECO) approach. The chemical exergies of brine and seawater are explicitly considered (most studies consider the same specific heat for input seawater and output brine). In addition, the enthalpy of each flow of the desalination unit is considered according to its salt concentration (results are then compared to the constant specific heat model). The highest exergy rates of fuel and product are obtained at the combustion chamber, and its exergy efficiency is 67.83%. The lowest exergy efficiencies were obtained at the condenser, followed by the first effect of the desalination unit, and the heat recovery steam generator. The overall exergy efficiency of the multi‐effect distillation unit is 21.49%. Regarding exergy destruction, as expected, the highest rate was obtained at the combustion chamber, which contributed with 41% to the overall exergy destruction, followed by the regenerator and heat recovery steam generator, with contributions of 16% and 11%, respectively, to overall exergy destruction.

Analytical solution and its application for the dynamic characteristics of a heat recovery steam generator in gas–steam combined cycle

This paper presents a study from the perspective of analytical solutions to analyze the dynamic characteristics of a Heat Recovery Steam Generator (HRSG) and explore its practical applications. The study employs the lumped parameter method to simplify the metal heat storage and temperature changes within HRSGs. Differential equations, based on the principles of mass and energy conservation, are formulated to describe the heating surfaces within HRSGs. Analytical solutions are derived, and the essential parameters in these expressions are discussed for their physical significance. Using these analytical solutions, the dynamic heat transfer processes for heating surfaces in a typical HRSG under various starting conditions are investigated. The findings reveal that a larger heat transfer factor or a smaller heat capacity factor of HRSG metal (or a larger ratio of these factors) results in a faster thermal equilibrium during the heat transfer process. Additionally, a dynamic forecasting model is developed based on these analytical solutions. The Particle Swarm Optimization (PSO) algorithm is applied as a parameter identification technique to fine-tune the model's initial parameters, which may be incomplete in real start-up processes. To validate the model, real-time on-site measurement data from a cold start-up of a non-supplementary fired HRSG is used. The results demonstrate the model's strong predictive capabilities, with an average absolute error ranging from 0.5 °C to 2 ℃, highlighting its high accuracy. Comparing the model with a thermal equilibrium model, it is evident that during the cold start-up of an HRSG, the heating surfaces exhibit dynamic characteristics, transitioning from a non-steady state in the first 3000 s to a quasi-steady state between 3000 and 7000 s.

A state-of-the-art review of heat recovery steam generators and waste heat boilers

A state-of-the-art review of heat recovery steam generators and waste heat boilers

Performance enhancements and NOx emission reductions using novel exhaust-driven hybrid gas turbine inlet air-cooling techniques

For combined cycles, gas turbine inlet air-cooling (GTIAC) increases the mass flow rates of both air and the generated steam of the heat recovery steam generator and hence power output. The introduction of exhaust gas recirculation (EGR) to reduce NOx emissions necessitates the application of GTIAC to overcome the adverse effects of gas turbine (GT) inlet air heating that accompany EGR. For a hot-humid climate, the r5egular cooling methods consume a significant amount of energy while desiccant and inlet-fogging are not effective. The main purpose of this study is to introduce innovative exhaust-driven hybrid GTIAC techniques that can reduce effectively the inlet temperature of the combined cycle in a hot-humid climate without consuming a substantial amount of energy and examine the effects of applying such techniques on the performance and NOx emissions. In this paper, a thorough analysis for the effect of increasing ambient temperature ( To) and relative humidity ( RHo) on the performance and NOx emissions of the air-cooled GT combined cycle (ACGTCC) is presented and the novel exhaust-driven hybrid (NE-DH) GTIAC systems of desiccant-ejector, ejector-refrigeration, and desiccant-ejector-refrigeration are applied to ACGTCC and optimized for maximum power output. The 1-D model at the double choking was used to model the performance of the ejector GTIAC technique. The results indicate that applying NE-DH GTIAC techniques results in gains in power, which vary between 0.31% and 0.6% per °C rise in To and an efficiency improvement of up to about 0.5 percentage point and significant reductions in both capital and maintenance costs compared with applying the refrigeration GTIAC system. The introduction of ejector and desiccant cooling decreases NOx emissions further and adds no additional equipment cost if implemented together with EGR or some CO2 capture techniques. A suggested plan for GTIAC that reduces NOx emissions by up to 25% is presented.

Energy, exergy, and exergoeconomic analyses of plastic waste-to-energy integrated gasification combined cycles with and without heat recovery at a gasifier

Energy, exergy, and exergoeconomic analyses were performed for two plastic-integrated gasification combined cycle (plastic-IGCC) systems to evaluate the performance of the plastic waste-to-energy cycles. Plastic waste-to-energy is a promising plastic treatment method that can resolve both plastic waste and environmental issues. Thus, improving the efficiency and economy of plastic-IGCC has become crucial because energy is generated during plastic waste-to-energy treatment while treating waste. The difference between the two modeled cycles is the location of heat recovery from the high-temperature syngas. In Cases 1 and 2, heat from the syngas was recovered with a heat recovery steam generator and a gas heater, respectively, to increase the temperature of the air entering the gasifier. The maximum net efficiency for Case 2 increased by 8.2% (from 35.41% to 43.57%), unlike that of Case 1, without changing exergy destruction. To assess the economic value and market potential, the unit electricity cost was examined for the condition in which the highest efficiency was obtained. The unit exergoeconomic costs for Cases 1 and 2 were 0.141 and 0.108 $/kWh, respectively, which were within the range of those in other energy recovery combined cycles; in addition, using air heaters for heat recovery reduced costs. The use of the air heater for heat recovery benefited energy and economic aspects without significantly changing exergy destruction. These findings have important implications for understanding the impact of gasifier agent conditions and energy recovery methods on the optimum conditions for plastic-IGCC. This study aimed to provide insights into the optimal design and operation of plastic-IGCC systems, considering both energy and economic aspects.

Comparative Study on the Corrosion Behavior of Materials in Heat Recovery Steam Generators for Combined Cycle Power Plant, Based on Sulfuric Acid Concentrations: Carbon Steels vs. Duplex Stainless Steel (UNS S32205)

This study examined the effects of sulfuric acid concentrations on the corrosion behaviors of three types of commercial steels, conventional carbon steel (SA192), sulfuric acid dew resistant steel (S-TEN), and duplex stainless steel (S32205), considered to be potential materials for the heat recovery steam generator (HRSG) in combined cycle power plants. Based on the results of electrochemical polarization, immersion and wet-dry cycle tests, when exposed to a high sulfuric acid concentration (50%), SA192 and S-TEN exhibited higher corrosion resistance than S32205, which was due to the formation of a stable FeSO4 scale on the carbon steel materials. With prolonged exposure, S-TEN with slightly higher concentrations of Cu and Sb showed lower weight loss than SA192. Conversely, when subjected to low sulfuric acid concentrations (5 and 10%), S32205 exhibited passivation behavior, and showed significantly superior corrosion resistance (i.e., much smaller weight loss) than the other two steel samples. The examination of localized corrosion damages through cross-section observation using a scanning electron microscope revealed also that S32205 suffered less damages from the wet-dry cycling. The long-term superior corrosion resistance of duplex stainless steel in low sulfuric acid concentrations, compared to carbon steel and sulfuric acid due resistant steel, make it a promising candidate material for the HRSG in combined cycle power plants.

Two-Objective Optimization of a Cogeneration System Based on a Gas Turbine Integrated with Solar-Assisted Rankine and Absorption Refrigeration Cycles

The current study investigates a cogeneration system based on a gas turbine, integrated with a Rankine cycle and an absorption refrigeration cycle, considering energy and exergy perspectives. The fuel used in the gas turbine’s combustion chamber is obtained through biomass gasification, specifically using wood as the biomass fuel. To enhance the system’s performance, solar energy is utilized to preheat the working fluid in the Rankine cycle, reducing the energy required in the heat recovery steam generator. Additionally, an absorption refrigeration cycle is incorporated to recover waste heat from exhaust gases and improve the plant’s exergy efficiency. A two-objective optimization is conducted to determine the optimal operating conditions of the proposed system, considering exergy efficiency and carbon dioxide emission index as criteria. The case study reveals that the gasifier and combustion chamber contribute the most to system irreversibility, accounting for 46.7% and 22.9% of the total exergy destruction rate, respectively. A parametric study is performed to assess the impact of compression ratio, turbine bleed steam pressure, gas turbine inlet temperature, and solar share (the ratio of energy received by solar collectors to biomass fuel input energy) on system performance. The findings demonstrate that maximum energy and exergy efficiencies of the power generation system are achieved at a pressure ratio of 10. Furthermore, a 1% reduction in the gas turbine’s compression pressure ratio can be compensated by a 9.3% increase in the solar share within the steam Rankine cycle.

STUDY OF EXHAUST GAS RESIDUAL HEAT CONVERSION HRSG PLTGU KERAMASAN TO ELECTRICAL ENERGY WITH GENERATOR THERMOELECTRIC TECHNOLOGY

The Heat Recovery Steam Generator (HRSG) is a combination of a Gas Power Plant (PLTG) and a Steam Power Plant (PLTU), this plant utilizes exhaust gas from the PLTG to produce steam as the working fluid in the PLTU. The residual heat from the heating process at the HRSG is channeled into the chimney, and the remaining heat from the exhaust gas can be converted into electrical energy with the Thermoelectric Generator (TEG) module. This research was carried out by installing the TEG module in series on the surface of the HRSG chimney wall, using laboratory scale measurements. The heat source uses a heater with a total power of 2,000 W. The research results show that the TEG module can convert the residual heat energy of the exhaust gas from the HRSG chimney into electrical energy. Four TEG modules mounted on the chimney surface can generate a voltage of 0.83 V and a maximum power of 2.79 mW. These results indicate that the TEG module is an opportunity to convert heat energy into electrical energy for further development.

Simulation research on optimization of a 200 MW IGCC system

The integrated gasification combined cycle (IGCC) has increasingly attracted attention as a promising high-efficiency clean coal technology. The oxygen-to-carbon ratio (O/C), nitrogen reinjection coefficient (Xgn), and integration air separation coefficient (Xas) affect system performance greatly. Based on the selected coal type, this paper establishes a 200 MW IGCC system model with coal–water slurry gasification, matches the three-pressure reheating heat recovery steam generator and syngas coolers, simulates and calculates the system performance of O/C, Xas and Xgn using Thermo-flex software. From the perspective of the whole system, the optimal O/C of the system is obtained as 0.91 considering the syngas composition and gasification temperature. From the perspective of system efficiency, the Xgn is obtained as 60 % with the Xas of 20 %. The overall IGCC system model is optimized using the optimized O/C, Xgn, and Xas to obtain higher system power and efficiency, the system power generation efficiency can improve up to 51.52 %. A thermal balance diagram of the IGCC system is drawn using the calculation results and provides a reference for the future design and operation of IGCC systems.

Failure Analysis of Low-Pressure Evaporator in Heat Recovery Steam Generator with 200 ton/h of Capacity

A steam-gas power plant (SGPP) combines a gas power plant (GPP) and a steam power plant by using the exhaust gas from the GPP to produce steam in the heat steam recovery generator (HRSG). The SGPP, which has a 200 ton/h HRSG capacity, experienced cracks, ruptures, and fatigue at the connection of the low-pressure evaporator pipe. Fatigue is a common failure mechanism in mechanical components due to thermal stress. However, the exact cause of the failure was unknown; therefore, a root cause analysis was conducted. Analysis included the thickness, metallography, chemical composition, tensile testing, thermography, defect testing, and hardness testing. The research showed thermal stresses were the cause of the low-pressure evaporator HRSG pipe failure. In addition, inspection results revealed a decrease in tensile strength, material hardness, and thermal expansion that exceeded the allowed limit.

Dynamic process simulation of a 780 MW combined cycle power plant during shutdown procedure

The share of variable renewables in power generation is increasing due to the push to reduce emissions, and the flexibility of conventional power plants has become a major concern. There are many ways to increase the flexibility of existing power plants and implement a more flexible system for the future, such as a fast start-up procedure and higher load change rates. In this study, a 2D dynamic process simulation model of a reference combined cycle power plant is presented to increase the flexibility of cyclic operation by investigating, for the first time in the literature, the shutdown procedure using APROS software. The 780 MWel Tambak Lorok reference combined cycle power plant consists of the GE 9HA.02 heavy-duty gas turbine and a three-stage horizontal heat recovery steam generator with reheat. Several steps were considered to improve the accuracy of the developed dynamic process simulation model, including varying the steam leakage to the atmosphere to control how much thermal energy remains in the heat recovery steam generator, changing the shape loss coefficients of the tubes to achieve higher or lower recirculation, and decoupling the reheater and the intermediate pressure drum. The developed model is validated with real data from three different combined cycle power plants in different countries with various capacities. The comparison shows that the developed dynamic simulation model can accurately represent the real behaviour of natural convection in the heat recovery steam generator. The main outcome was to provide detailed information on the shutdown procedure of large-scale combined cycle power plants, addressing the aspect of the development of new start-up strategies to reduce the time required for the start-up procedure.

RETRACTED: Analysis and optimization of thermal power plants: Pinch and exergy methods

The increasing demand for electrical energy and the depletion of fossil fuel reserves have underscored the need for the analysis and optimization of thermal power plants. This research focuses on the analysis and optimization of a combined cycle power plant that utilizes natural gas as its primary fuel. The study employs exergy analysis, pinch analysis, and related concepts to analyze the energy flows and identify inefficiencies within the system. The aims of the research are to determine the overall losses, component efficiencies, and overall efficiency of the combined cycle power plant and to optimize its performance using the atomic orbital search algorithm. The optimization aims to reduce waste and increase the overall efficiency of the power plant. By using these methods and algorithms, the research aims to address the challenges associated with fossil fuel consumption and contribute to the sustainable and efficient production of electrical energy. The overall exergy efficiency of the power plant increased from 68.73% in the design mode to 70.56% after optimization, resulting in a significant improvement in energy utilization and a reduction in exergy losses across the cycle components. In the low-pressure section of the heat recovery steam generator, exergy losses decreased from 2791.3 kW to 1600.67 kW after optimization, while in the high-pressure section, exergy losses reduced from 45,013 kW to 42509.72 kW. These optimizations demonstrate the potential to minimize exergy waste and enhance the overall performance of the power plant.

Energy and exergy assessment of 750 MW combined cycle power plant: A case study

As global energy demand continues to rise, the imperative to explore and enhance energy generation from existing resources intensifies. Combined cycle power plants (CCPPs) have emerged as a promising solution to improve efficiency and electricity production. In this study, we present a comprehensive analysis of the thermodynamic performance of a 750 MW CCPP located in Assiut, Egypt, with a focus on its energy and exergy efficiency. Our investigation reveals critical insights into the CCPP's operational dynamics. Notably, the combustion chambers emerge as the primary contributors to exergy destruction, accounting for 53.3 % of the total exergy loss. Heat recovery steam generators (HRSGs) follow closely at 32 %, while compressors, steam turbines, gas turbines, and cooling systems contribute 5.3 %, 5 %, 2.3 %, and 1.7 %, respectively. These findings pinpoint specific areas where exergy losses are most significant, offering valuable guidance for targeted improvements in CCPP performance. Furthermore, we report that the overall energy efficiency of the entire plant stands at 34.6 %, with an exergy efficiency of 33.5 %. In summary, our study provides a comprehensive scientific assessment of the thermodynamic performance of a 750 MW CCPP. The specific insights into exergy destruction and efficiency metrics not only contribute to our understanding of CCPPs but also offer actionable recommendations for optimizing the operation of gas turbine based CCPPs. These findings hold significance in the broader context of energy sustainability and environmental considerations.