Heat Recovery Steam Generator Research Articles

Energy and exergy analysis of a new solar hybrid system for hydrogen, power and superheated steam production

This study investigates the amalgamation of solar tower technology and thermal energy storage (TES) within the framework of a supercritical carbon dioxide (S-CO2) Brayton cycle, a copper-chlorine (Cu-Cl) hydrogen production cycle, and a heat recovery steam generator (HRSG) to generate superheated steam. The various subsystems have been merged to enhance overall energy efficiency significantly, ensure uninterrupted operation, and minimize exergy loss. Energy and exergy analyses have been carried out to assess the prerequisites and effectiveness of each subsystem, highlighting the thermodynamic benefits of integration. Engineering Equation Solving Software (EES) was employed to solve the integrated system model and assess the thermodynamic properties provided by the EES library. Results showed that in the basic design mode, exergy destruction in the solar tower, S-CO2 Brayton cycle, and Cu-Cl cycle are 9930 kW, 7111 kW, and 9735 kW, respectively. The system produces 4226 kW of power, 2697 kW of heat, and 0.04971 kg/s of hydrogen. The overall energy and exergy efficiency of the power plant are 17.48 % and 18.72 %, respectively. These findings demonstrate that this integrated system can address key gaps in the literature by presenting a novel combination of solar power-driven Cu-Cl hydrogen production and superheated steam generation. The proposed system contributes to advancing renewable, efficient, and uninterrupted energy production.

Simulation and Energy Analysis of Integrated Solar Combined Cycle Systems (ISCCS) Using Aspen Plus

The aim of this research is to simulate and analyze a combined power cycle (Steam turbine and gas turbine cycles) by studying the effect of changing the natural gas flow rate on the developed power. Therefore, reducing the amount of used natural gas in the combustion chamber of the gas turbine cycle from 9.2 to 4 kg/s showed a significant drop in the power produced by the gas turbine, i.e., from 123.7 to 57.7 MW. Additionally, this change in the combusted natural gas amount affected the heat recovered in both heat recovery steam generators (HRSGs), i.e., from 219.79 to 100.35 MW, respectively. Consequently, the amount of generated steam in the high pressure HRSGs and the power developed in the steam turbine changed from 60.88 to 27.79 kg/s and from 56.39 to 27.13 MW, respectively. A heat exchanger (HFHX) utilizing a heating fluid was used as an external source of energy to compensate the reduction in the generated heat and to increase the amount of generated steam up to 157.32 kg/s, which keeps the power plant capacity at 180 MW. Existing combined local plant data were used in this study and were simulated in Aspen Plus software V11. A sensitivity analysis was made to optimize the cycle operating conditions that use less natural gas and produce the same amount of power.

Performance Improvement of Industrial Gas Turbine for Power Augmentation in the Nigeria Oil and Gas Sector

This paper provides a comprehensive overview of the electricity supply situation in Nigeria, focusing specifically on enhancing the performance of industrial gas turbines, GE GT13E2 (Afam Power Plant owned by FIPL) in Port Harcourt. The study encompasses two primary aspects. Firstly, it involves an examination of the nominal operating conditions of a combined cycle system and explores their dynamic performance through advanced simulations. Secondly, the research introduces a supplementary burner into the combined system and conducts a comparative analysis, considering factors such as system efficiency and power output. The power plant configurations are simulated using Gasturb14. The analysis is carried out by establishing the maximum attainable temperature in the Heat Recovery Steam Generator (HRSG), which determines the number of stages of supplementary firing that can be implemented. The results presented in this paper unveil the substantial potential for power generation with the addition of supplementary burners, indicating a remarkable increase in power output, yielding approximately 187.444 MW. However, this significant boost in power generation comes with an associated trade-off, wherein the overall system efficiency experiences a reduction. From an economic perspective, the additional power generated by the afterburner translates directly into increased revenue from electricity sales. Considering the average residential electricity rate in the U.S. as of February 2023, the calculated additional revenue from the afterburner amounted to approximately $25,641.58 per hour.

Studi Numerik Pengaruh Sudut Bukaan Damper dan Flue Gas Temperatur Terhadap Distribusi Temperatur Pada Heat Recovery Steam Generator (HRSG)

The Combined Cycle Gas Turbine Power Plant (PLTGU) utilizes the waste heat from the gas turbine to produce steam in a Heat Recovery Steam Generator (HRSG). The steam from the HRSG is then used to generate electricity in a steam turbine. In HRSG operation, several variables significantly impact its performance, including the damper angle and inlet temperature. At the Tanjung Uncang Power Plant in Batam, the manufacturer's standard operating procedure (SOP) requires that the exhaust gas temperature when the damper is open must be below 400°C. However, the gas turbine with an initial load of 5 MW has an exhaust gas temperature of 560°C - 580°C. Therefore, it is necessary to perform a gas turbine load release or FSNL (Full Speed No Load) to reduce the inlet temperature of the gas turbine. During FSNL, there are SOPs for diverter damper angles of 51°, 68°, and 90°. This leads to the need for analyzing the impact of diverter damper angles and inlet temperature on the flow pattern and temperature distribution. The analysis was conducted using CFD (Computational Fluid Dynamics) with ANSYS Fluent 2020 software. The variations used are diverter damper angles of 51°, 68°, and 90°, combined with inlet temperatures of 400°C and 580°C. The simulation outputs include velocity contours, temperature contours, and equivalent stress on the superheater tubes. The HRSG simulation results show that the flue gas is not distributed uniformly. The turbine exhaust gas only spreads along 4 – 11 meters, leading to slower steam production from the superheater. Additionally, when the superheater tubes are empty, the steady-state thermal and structural simulation results indicate that an inlet temperature of 580°C, whether at damper angles of 51°, 68°, or 90°, can cause a larger temperature difference between the inner and outer walls, ranging from 117.04°C to 125.5°C. This temperature difference can lead to thermal stress on the superheater tubes. This is shown in the S-N Curve for SA 213 T22 material, with a convection coefficient of 5 W/m² K (no steam), where the equivalent stress exceeds the endurance limit (infinite zone).

Studi Numerik Pengaruh Penambahan Turning Vane Terhadap Bentuk Aliran dan Distribusi Temperatur di Heat Recovery Steam Genertor (HRSG)

Tanjung Uncang Power Plant is one of the facilities in Indonesia that utilizes CCGT (Combined Cycle Gas Turbine). This cycle uses an HRSG (Heat Recovery Steam Generator) to heat steam using the exhaust gases from the gas turbine. At Tanjung Uncang's HRSG, the SOP requires that the gas turbine exhaust during cold start conditions must be below 400°C. Meanwhile, the gas turbine at Tanjung Uncang has a base load of 5 MW with a temperature range of 560°C - 580°C. Therefore, an asynchronous process is necessary to reach the FSNL (Full Speed No Load) condition for the gas turbine, with the damper angles set at 51°, 68°, and 90° for 45 minutes. Additionally, to achieve optimal conditions with the gas turbine running at 45 MW, a time span of 8 hours is required, which results in losses of up to 700 million. The extended time required can be due to uneven flue gas distribution, necessitating time for the HRSG to reach optimal conditions. This underscores the need to analyze the effects of adding turning vanes with angles of 35°, 53°, and 71°, and inlet temperatures of 400°C and 580°C on the characteristics of flue gas distribution. The analysis was conducted using CFD with ANSYS Fluent 2021 software. The simulation outputs include velocity vectors, velocity contours, and temperature distribution contours.

Exploring the role of hydrogen in decarbonizing energy-intensive industries: A techno-economic analysis of a solid oxide fuel cell cogeneration system

Industry is nowadays one of the most energy-demanding sectors representing a major contributor of global greenhouse gas emissions. The simultaneous need for electricity and high-temperature heat is what makes some industrial processes difficult to decarbonize via current commercially available technologies. As the demand for materials and goods is expected to grow in the upcoming years, it is crucial to define which strategies and technologies will serve as the cornerstone of sustainable development. This study addresses the imperative need for emission reduction of energy-intensive sectors by proposing a novel hydrogen-based cogeneration system in the framework of the paper and pulp industry, with the aim of providing general insights relevant to a broader spectrum of similar applications. The comparative analysis presented in this work focuses on three cogeneration options aimed at satisfying the paper mill energy needs: a conventional natural gas-fuelled gas turbine, a Solid Oxide Fuel Cell (SOFC) fed with grey hydrogen produced via steam methane reforming, and a SOFC operating using green hydrogen produced on-site. The latter involves an integrated multi-energy system with photovoltaic panels, electrolyzers, compressors, and storage tanks. Indeed, the SOFC potential of supplying electricity and high-temperature heat in the form of pressurized steam for industrial applications has not been well investigated yet and represents one of the main objectives of this work. Building on the real consumption profiles of a paper mill facility, techno-economic analyses are carried out for many system configurations, varying components size and layout to assess their performance with respect to CO2 emissions and two key economic parameters, the Levelized Cost of Hydrogen (LCOH) and the net present cost. An in-house-developed flexible simulation framework is presented and expanded for the purposes of this study, including a detailed model that accounts for design and off-design performance of a SOFC cogeneration unit. Results demonstrate that integrating a SOFC with a heat recovery steam generator result in a 75% reduction in the mass flow of generable pressurized steam in comparison to a gas turbine. Additionally, in the cost-optimal scenario, CO2 emissions are 25% lower than the conventional gas turbine-based configuration, achieving complete independence from the electricity grid and an LCOH of 5.81€/kg without considering revenues from electricity sold.

Optimization of steam parameters in double-pressure heat recovery steam generators

Double-pressure heat recovery steam generators are installed in medium-size combined cycle power plants. For a fixed total heating surface area of heat recovery steam generator, the net power output of the power plant depends on steam pressures and temperatures. This paper presents a method of determining the optimal set of steam parameters in double-pressure heat recovery steam generators without reheating and with reheating. The mathematical models of both heat recovery steam generators are presented, and the optimization procedure is described. For given exhaust gas temperature and total heating surface area, the optimal steam parameters of both heat recovery steam generators that maximize net power output can be found subjected to the constraint that the steam quality at turbine outlet is not less than 88 %. Simulation results show that reheating increases optimal net power output by 2.4 % and exhaust gas temperature by about 80 °C.

Exergetic, economic and exergy-based sustainability analysis of a power generation system with CO2 capture and methanol production

This study proposes a new biomass-based Combined Heat and Power (CHP)/renewable methanol production through captured carbon dioxide. A liquid organic hydrogen carrier (LOHC) stores and releases hydrogen. Literature review shows that LOHC has been integrated into such a system for the first time. The exergetic, exergoeconomic, and economic performance are researched. On average, results show that the exergetic efficiency of the system is 6.6 %. Depletion ratio (DR) is the depletion rate of the exergy source given to the system, which is desired to have low values. The sustainability index (SI) is the DR's reverse, representing the required exergy source per exergy destruction (exergy depletion). High values of this index indicate less exergy source consumed in the system. Exergetic ecological index (EECI) compares the useful products or depleted exergy per consumed exergy source destruction. The negative value of EECI means that the depletion of the exergy source is more significant than the product exergy and vice versa. The exergy-based sustainability indices, including DR, SI, and EECI, are found as 0.934, 1.071, and −0.868, respectively. Exergoeconomic analysis reveals that the exergy destruction rate at the system's capital cost (REX) value is 0.087×102. Heat Recovery Steam Generator (HRSG), gasifier, and Heat Exchanger 1 (HE1) are obtained as 5.153×10−2 (kW/€), 1.707×10−2 (kW/€), 3.094×10−2 (kW/€) respectively. The payback period and the REX are 14.56 years and 0.087×10−2 (kW/€), respectively; it seems long for an engineering application, but these technologies are relatively new, and their costs might decrease soon. Exergy destruction or lost power per capita, which means depleted investment, costs much less than 1. Although the thermodynamic values of the system seem low because irreversibilities occurred in chemical reactions, CO2 saved and produced methanol and cannot be ignored in terms of its environmental and economic benefits, considering CO2 taxes and the methanol economy.

Analysis and improvement of gas flow behaviour at the inlet duct of an industrial HRSG boiler through CFD modelling

This work analyses and improves the distribution of the flow of flue gases along the inlet duct of two industrial Heat Recovery Steam Generation (HRSG) boilers. The inlet duct connection with the boiler casing presents a special configuration, being axial for one boiler and radial for the other. The study was carried out using a 3D Computational Fluid Dynamics (CFD) modelling. The flow uniformity improvement is studied considering the introduction of baffles, perforated plates and the Part Elimination and Lattice Search (PELS) method. The Root Mean Square (RMS) axial velocity is used to determine uniform flow distribution. Its value must be equal to or below 0.2 m/s. Nevertheless, the pressure drop in the boiler must not increase by 1 mbar as compared to the standard case. After analysing the 3D CFD modelling results, our conclusion is that, in an axial configuration, the PELS method and a perforated plate (TAD44A65) located at the inlet of the recovery zone can improve the fluid flow uniformity to 40 %. For the radial configuration, only a perforated plate (TAD44A65) located at the inlet of the recovery zone improves fluid flow uniformity to 43 %.

A complete dynamic modeling of two-by-one gas-steam combined cycle unit for coordinated control design

The high penetration of renewable energy can potentially change the role of combined cycle gas turbines (CCGT) from load suppliers to flexible suppliers. However, the slow process in the dynamic modeling of the CCGT complete system restricts the design of its best flexible operation strategy. Therefore, this paper adopts the composite modeling method to establish a complete nonlinear dynamic model of a 2 × 1 CCGT including two gas turbines, two three-pressure heat recovery steam generators (HRSG), one steam turbine, and one heat exchanger. This model can reflect the dynamic characteristics of pressure and flow in the bottom cycle due to the changes in operating mode, which can guide the design of the flexible operation control strategy of the 2 × 1 CCGT. To verify the model’s accuracy, the simulated data were compared with the field data from a 900 MW cycle with the same configuration. The results show that the established model can accurately reflect the changing trend of variables during mode switching. The range errors of essential variables such as gas turbine (GT) power is 3.8 %, GT outlet temperature is 1.4 %, high-pressure drum pressure is 4.5 %, and the range errors of other variables are below 5 %, proving the fidelity of the established control model. The dynamic model established in this paper will be the basis for model-based controller design which can handle multi-objective optimization and constraints in flexible operations. Moreover, this model will be used to guide the design of multi-mode control and energy management strategies.

Power Augmentation of Gas Turbine Using Exhaust Flue Gas Operated Vapor Absorption Machine

Industrial gas turbines (GT) that operate at constant speed are constant-volume-flow combustion machines. As the specific volume of air is directly proportional to the temperature, an increase in air density results in a higher air mass flow rate at low air ambient temperatures. This results more mass of air is now passes through same volume gas turbine space. Consequently, the gas turbine power output increases proportionally with the increase in air mass flow rate. For geographic regions where warm and humid months are predominant throughout the year, significant power loss occurs during these months, and a higher rate of expensive fuel is fired at reduced power output. A gas turbine inlet air cooling technique is a useful option to enhance GT output. One of the innovative options for power augmentation of gas turbine is inlet air conditioning using a vapor absorption machine (VAM). Using VAM for GT intake air conditioning has the advantage over other systems in that it can be operated from waste heat. Many gas turbine machines, particularly natural gas pumping stations, are operated without heat recovery steam generator (HRSG) or heat recovery option. Valuable heat energy is escaped with exhaust flue gas in these systems. This paper demonstrates how GT exhaust waste heat can be utilized for its own power generation enhancement. In this study, a flue gas-based vapor absorption machine is selected for cooling the inlet air of a 26 MW gas turbine, which is used to drive the booster compressor of a natural gas pumping station. The capacity of the VAM for the required cooling effect has been calculated. The expected GT power enhancement from intake air gas conditioning has also been estimated in this paper.

Binary Vapor Cycle for Waste Heat Recovery from Marine Engine Exhaust

Abstract The considerable energy waste in maritime transport and the need to obtain alternatives to reduce emissions of polluting gases are factors that have motivated the study of waste heat recovery systems for marine engines. The system studied herein relies on a binary vapor cycle that uses water for the topping cycle while three organic fluids were investigated for the bottoming cycle: R601a, R134a, and R22. Each of these belongs to a different category of fluid, namely, dry fluid, isentropic fluid, and wet fluid, respectively. Two engines of different ratings and two different pressures of the heat recovery steam generator have been considered for each engine. Various outlet pressures for the topping turbine, which is the most liable to erosion and corrosion due to wet steam, have been investigated. The maximum efficiency achieved for the waste heat recovery system peaked at 21% while the maximum electric power accounted for 4.2% of engine brake power. Therefore, the employment of a waste heat recovery system based on a binary cycle seems a promising alternative to harnessing heat from the exhaust gases of marine engines.

Identification of acid phosphate corrosion in heat recovery piping of combined cycle power plants

Failure of heat recovery units in power plants is a serious problem that causes large economic losses. Accurate determination of the failure mechanism is critical to identify problems at an early stage and make recommendations to power plant operators to prevent equipment failures. These failures are due to tube breakage caused by various mechanisms such as acid corrosion (hydrogen attack), temperature damage, caustic corrosion, and acid phosphate corrosion. The present work aims to report a case study of four damaged tubes from a heat recovery steam generator from a unit of combined cycle power plants (HRSG). The techniques of simple and high-resolution transmission electron microscopy (TEM-HRTEM), scanning electron microscopy with elemental analysis (SEM-EDS) and X-ray diffraction (XRD) allowed to provide evidence of the presence of the acid phosphate corrosion mechanism in three of the four pipes analyzed.

Sensitivity and sustainability analysis of combined cycle plant with integrated LNG pressure energy recovery

Although combined cycle power plants (CCPPs) and liquefied natural gas (LNG) have arisen as solutions to the intermittent nature of renewable energy sources, they still need creative methods for performance enhancement and sustainability of the energy systems. Moreover, the energy efficiency of CCPPs is negatively impacted by environmental conditions, higher specific fuel consumption and a large quantity of waste heat released into the ambient. On the other hand, using seawater as a heating medium in LNG regasification circuits has a detrimental effect on the marine ecosystem. In this context, the LNG pressure energy recovery system through a direct expansion cycle (DEC) integrated with CCPP is proposed to improve sustainability, enhance exergetic performance and to reduce the heat recovery steam generator (HRSG) exhaust loss. To improve the cycle performance, low grade heat harnessed from CCPP is used as the heat source in the DEC rather than seawater. The system performance is analyzed by the energy and exergy method through a mathematical model. Moreover, the sensitivity analysis of the combined system is accomplished to examine the influence of LNG flow rate and ambient temperature on various performance indicators of the total system. It is observed that the integration of DEC boosts the HRSG performance by reducing the stack exergy loss and the efficiency is sensitive to LNG flow rate. The total integrated system energy efficiency ηtot, enhanced to 1.55% compared to the base case. Whereas, for ambient temperature in range of 15 – 45 °C, the system minimum and maximum exergetic efficiency ηex,tot is found to be 54.52 % and 55.94 %. Furthermore, the comparison of exergetic sustainability indicators is calculated and presented for three different simulation cases. The results demonstrate that increase in ηex,tot, affects the environment impact factor, ref and the sustainability index, θsi and improved 2.09 % compared to base case combined cycle.

Introducing and performance evaluation of a novel Multi-Generation process for producing Power, fresh Water, oxygen and nitrogen integrated with liquefied natural gas regasification and carbon dioxide removal process

The objective of this paper is to develop and evaluate a new integrated multigenerational system comprised of cryogenic air separation, hydrate-based desalination, combined cycle and oxyfuel power plants, carbon dioxide amine absorption, and transcritical carbon dioxide power cycle, employing liquefied natural gas cold energy. This integrated multi-generation system, applicable for liquefied natural gas importer terminals with access to seawater, produces approximately 2,533 MW net output power and 1,985 kg/h fresh water. In addition, this integrated multi-generation process produces 16,735,861 kg/h high-purity liquid oxygen (100 mol%), 4,773,633 kg/h liquid nitrogen with 99.71 mol% purity, more than 31,724,465 kg/h high-purity gaseous nitrogen (99.9 mol%), and 90,903,230 kg/h low-purity gaseous nitrogen (83.38 mol%). About 5907.3 MW of produced power is generated by liquefied natural gas expander. The performance of this system is evaluated by energetic methods. The results of energy analysis show the specific energy consumptions of the air separation products are 0.551 kW/kg and 1.93 kW/kg for liquid oxygen and nitrogen, respectively. Moreover, in the hydrate-based desalination subsystem, the specific energy consumption is 0.5 kW/m3 for produced pure water. The combined cycle power plant includes two gas turbines, three steam turbines, and a three-pressure level heat recovery steam generation. The thermal efficiencies of gas turbine cycles (Bryton), steam turbine cycles (Rankine) and combined power cycles are 26.3 %, 29.6 %, and 36.2 %, respectively. The flue gases from power plants enter the carbon dioxide amine absorption subsystem. The separated carbon dioxide is used as a working fluid to produce 372.1 MW power in transcritical carbon dioxide cycle. The results of energy analysis for carbon dioxide amine absorption subsystem show that the specific energy consumption, the ratio of captured carbon dioxide per unit mass of liquefied natural gas and the carbon dioxide removal efficiency are 6.60 kW/kg, 33.91 kg/tone, and 90.06 %, respectively. Approximately 2,905,000 kg/h of liquid carbon dioxide is obtained as the byproduct of this multi-generation process. Additionally, sensitivity analysis is conducted to determine key parameters influencing the main energetic indexes. Finally, the amount of attainable regasified natural gas reaches 257,523 tone/h by applying this multi-generation system with total 86 % energy efficiency.

Proposal and thermodynamic investigation of pressurized calcium looping integrated with chemical looping combustion for tail-end CO2 capture in a retrofitted natural gas combined cycle power plant

The integration of tail-end calcium looping into an existing natural gas combined cycle (NGCC) power plant has minimal impact on CO2 capture retrofits. However, a high volume of flue gas needs to be preheated before entering the carbonator, and the relatively high energy consumption of oxygen production exacerbates the energy penalty of the NGCC system with tail-end CO2 capture. This paper proposes the method of pressurized calcium looping integrated with chemical looping combustion (PCaL-CLC). It employs the PCaL-CLC method to reduce the energy penalty and energy consumption of the NGCC system with tail-end CO2 capture. Results show that the proposed system using the PCaL-CLC method achieves a 3.0% reduction in energy penalty, decreasing from 9.1% in the reference system employing the calcium looping method to 6.1% in the proposed system. Besides, the specific energy consumption for CO2 avoided (SPECCA) declines from 4.43 MJLHV/kg CO2 to 2.76 MJLHV/kg CO2. Exergy analysis and energy utilization diagrams reveal the underlying reason for improving system performance. Furthermore, by optimizing the operating parameters of the gas turbine and equipping it with advanced heat recovery steam generation, an energy penalty of 2.9% and a SPECCA of 1.21 MJLHV/kg CO2 are achieved without CO2 compression, which is superior to those of amine scrubbing and hot-end calcium looping CO2 capture technologies. The proposed PCaL-CLC method offers an alternative approach to reducing the energy consumption of tail-end CO2 capture in existing natural gas combined cycle power plants.

Thermal analysis of an integrated solar combined cycle power plant and its application in southern Iraq

Recently, simple cycle play a significant role in electric power production in Iraq. However, those units suffer from low thermal efficiency and low power output. In the present work, theoretical study is carried out aiming to improve the performance of (AL-Amara station 125MW). The present work includes three parts: the first part focus on the effect of ambient temperature on the performance of simple cycle including mass flow rate, power output, thermal efficiency and other parameters. In the second parts, a modification to simple cycle is implanted to be a combined cycle. The third part is studied the benefit of using solar unit for producing more steam to be supplied to the heat recovery steam generator wishing to produce more power and low emissing. Regarding, to simple gas turbine unit, the obtained results show that the mass flow rate is decreased nearly (10.8%) when the ambient temperature increased from (15-50) ºC. However, this reduction in mass flow rate of air is led to significant reduction in power output and thermal efficiency nearly (22.6%,13.2%) respectively. In the second parts, applying combine mode show a significant increase in power output and thermal efficiency nearly (32.5% and 32.3%) respectively. while the specific fuel consumption is decrease nearly (32.19%). Finally, the third parts when solar units are used, the gathered results show an acceptable increase for the amount of steam produced via solar units (21.02kg/s). The overall performance of the integrated cycle shows that the power output and the thermal efficiency increased nearly (11.28%and10%).

Tracing the carbon capture energy distribution in a natural gas combined cycle power plant under variable operating conditions

A thermodynamic analysis method with a new criterion was introduced to reveal and dynamic track the internal energy consumption distribution of natural gas combined cycle power plants with CO2 capture. The new method decomposes the capture energy consumption into separation energy consumption and system integration energy consumption caused by gas turbines, steam turbines, heat recovery steam generators and steam extraction. The results indicate that load variation has little effect on the energy penalty of the separation process, which accounts for over 50 % of the total capture energy consumption and is stable at around 0.8 MJe/kg CO2 for MEA-based cases, while the integration performance becomes better with load decreasing, since the superior matching between extraction steam and reboiler parameters. Besides, exhaust gas recirculation technology reduces energy consumption caused by steam extraction by around 67 %∼85 % and brings an additional penalty of 0.1–6 MW on the gas turbine under 40–100 % load conditions. Therefore, exploring new absorbents and optimizing the matching between extraction steam and reboiler parameters are the critical points for capture system without exhaust gas recirculation. In contrast, for capture system with exhaust gas recirculation, energy consumption caused by the deterioration performance of gas turbines is crucial under high operation load, while absorbent innovation is dominant at low load. With the aid of the thermodynamic analysis method introduced in this paper, a better understanding of CO2 capture systems under variable load conditions can be obtained, which may be helpful for reducing energy consumption in CO2 capture technologies.

Conventional and advanced exergy-based analyses and comparisons of two novel tri-generation systems based on solid oxide fuel cells and gas turbines

This study conducts conventional and advanced exergy, exergo-economic, and exergo-environmental analyses and comparisons of two tri-generation systems driven by solid oxide fuel cells (SOFCs) and gas turbines (GTs). The proposed systems mainly consist of SOFC, GT, heat recovery steam generator (HRSG), (organic) Rankine cycle, and heat exchanger. The analysis results indicate that the biggest cost rates of exergy destruction and component in both systems appear in SOFCs being 4.4333 $/h and 4.2760 $/h, while the highest environmental impact rates combined with exergy destruction and component in systems 1 and 2 are found in afterburner and HRSG, which are 645.9569 mPts/h and 849.2659 mPts/h. Compared to the conventional analyses, the advanced analyses demonstrate that air compressors own the largest avoidable-endogenous parts of cost rates, while HRSG of system 1 and steam turbine (ST) of system 2 own the highest avoidable-endogenous parts of environmental impact rates being 165.8482 mPts/h and 115.2299 mPts/h.

Zero carbon emission CCGT power plant with integrated solid fuel gasification

The development of a high-capacity power plant with zero CO2 emissions is an urgent task that will curb the increase in atmospheric temperature. It should have an efficiency comparable with existing TPPs, a low metal consumption rate, a high fuel versatility, and high flexibility. To meet these conditions, oxygen combustion is conducted in an environment of inert CO2, and most of the condensation heat from the combustion products is usefully utilized. This work presents a combined cycle gas turbine (CCGT) power plant with solid fuel gasification, oxy-fuel combustion, and a pressurized heat recovery steam generator (PHRSG). The two plant options are compared with the natural gas plant previously proposed. In the PHRSG, the low metal intensity is achieved by high average temperature differences, the pinch point value at 8–12 °C, and the intensification of heat transfer caused by the high pressure of combustion products and the condensation of water vapor in the tail surfaces. The developed plants are highly efficient when using coal, 51%, and 57.3% when using peat, and have acceptable CO2 avoidance costs of 72.7 €/t and 60.4 €/t. By combining these factors, and using well-developed materials, it will take less time to develop and implement this plant widely.