Intermediate Pressure Turbine Research Articles

4E analysis and parameter study of a solar-thermochemical energy storage CCHP system

The combination of calcium looping and concentrating solar power (CSP) is a promising energy conversion technology that can greatly increase the share of solar energy used in combined cooling, heating and power (CCHP) systems. This paper designs a CCHP system based on solar energy and thermochemical energy storage. The system runs all day through day and night modes. Under basic working conditions, the energy and exergy efficiencies of the system could reach 56.92 % and 35.94 %, respectively. The system is evaluated by multiple approaches including parametric sensitivity analysis and 4E (energy, exergy, economy and environment)) analyses. The results demonstrate that the system could produce 2618.09 MW of electricity, 305.56 MW of heat and 523.88 MW of cooling capacity per day, respectively. At the same time, the reductions of CO2 emissions and fossil fuel consumption could reach 2222.76 tons and 696.41 m3 per day, respectively. Furthermore, the increasing mass flow of main turbine inlet could increase both the system efficiency and the exergy efficiency. Thus, it is beneficial to reduce the environmental impact but with the increasing investment cost. In the meanwhile, the exergoeconomic factor and exergoenvironment factor of the system were 55.65 % and 0.139, respectively. Besides, as the extraction flow rate of the intermediate pressure turbine increases, the energy efficiency increases but the exergy efficiency descends. This is unfavorable to reducing the environmental impact, yet it could decrease the investment cost of the system. These results reveal that the hybrid system has the characteristics of high efficiency and emission reduction in energy storage, power generation, heating and cooling, and has great development potential.

Energy and exergy analysis of the 1220 MW natural gas-fired Hamitabat combined cycle power plant

In this study, the energy and exergy analysis of the 1220 MW Hamitabat combined cycle power plant (CCPP) that was renovated in 2017 with a 520 million € project is carried out. A thermodynamic model is built by applying the conservation of mass and energy principles and operating data are obtained from the plant operators. Exergy analysis is performed with the exergy balance equation to determine the exergy efficiencies and improvement potentials of all components. Also, parametric analyses are carried out to investigate the methods to enhance the performance of the plant. The plant has thermal and exergy efficiencies of 59.70% and 58.52%, respectively and these values are 13.70% and 13.52% higher than the thermal and exergy efficiencies of the original plant, respectively. Results showed that the combustion chamber (CC) has the highest rate of exergy destruction, and it is responsible for 77.61% of the total irreversibilities. The improvement potential of the CC is found to be 67.992 MW, and the prevention of heat loss from CC can increase the thermal and exergy efficiencies of the plant by 3.88% and 3.80%, respectively. Parametric analyses showed that the plant performance can be enhanced by increasing the inlet temperatures of high- and intermediate-pressure turbines, and decreasing the pressures of condenser and high-pressure turbine.

Effect of Diameter on Steam Pressure Sootblower to Eliminate Low Potential Slagging and Fouling

The combustion process in pulverized coal boilers utilizes coal fuel, which produces ash and heat. Ash from combustion process will be deposited and adhere to pipes, known as slagging and fouling. Cleaning of slagging and fouling is done using a sootblower by flowing pressurized fluid to generate a jet nozzle force, which can remove the slagging and fouling adhering to the pipes in the superheater. Based on testing of parameters, ash fusion temperature is 1415.42 oC, and silica ratio is 79.55%, indicating a low potential for slagging. For fouling testing yielded an index of 0.089, indicating a low potential for fouling. The existing retractable sootblower operates using superheated steam with a pressure of 70-75 bar. In the design of low-pressure sootblower, flow is derived from intermediate pressure turbine by modifying feed tube, lance tube, and sootblower nozzle. The design results in a feed tube diameter of 101.65 mm, a lance tube diameter of 114.3 mm, an inlet nozzle diameter of 21.1 mm, a throat nozzle diameter of 13.97 mm, and an outlet nozzle diameter of 41.02 mm, with a Mach number output of 2.09 and a total jet force of 2023.9 N.

Harmonic Method for Simulating Unsteady Multispool Interactions

Abstract Modern civil jet engines arrange components on spools with different rotational speeds in order to improve compressor stall margin, overall engine performance, etc. The unsteady interactions among these components can be significant and should be considered at an early design stage if possible. Unsteady Reynolds-averaged Navier–Stokes (URANS) is a common approach to simulate these unsteady effects, but the disparity in time scales in a multispool simulation can lead to expensive URANS simulations. Harmonic methods are effective and efficient approaches to simulate unsteady interactions among turbomachinery components, but their applications to multispool simulations remain a challenge. The objective of this paper is to address this challenge. This paper extends the Favre-averaged non-linear harmonic method to simulate multispool turbomachinery components using a unified bladerow interface which transfers disturbances through bladerows with arbitrary blade counts at any rotational speed. The regularization of non-reflective boundary condition is described for certain circumferential wave number of the zero-frequency mode. The capability of the proposed approach is demonstrated by simulating the transfer of hot streaks through full 3D high- and intermediate-pressure turbines in a three-shaft engine. The temperature distributions from the harmonic method show good agreement with direct unsteady simulation in terms of the mean flow and the instantaneous flow. The radial migration of the hot streaks towards the hub are captured very well by the proposed harmonic method. The required wall-clock time of the harmonic method is roughly 240 times smaller than the whole annulus URANS simulation. This demonstrates that the proposed method can be an efficient design tool to trace hot streaks in multispool turbines at the early design stage.

Instrumentation improvements for NGV aerodynamic characterization at high Mach numbers

One of the most important new engine concepts is the Geared turbofan. In these engines a gear box allows the decoupling between fan and turbine rotational speeds. As a consequence, the separate aerodynamic optimization of both components becomes possible leading to an increase in engine bypass ratios, higher propulsive efficiency and lower specific fuel consumption. The multi-stage intermediate pressure turbine (IPT) is one of the key parts of the thermodynamic cycle in geared turbofan architectures. During the characterization of a LPT NGV row, it is important to have detailed pressure losses measurements as accurate as possible. Because of the aerodynamic differences with conventional low pressure turbines (LPT), this becomes mandatory when the NGV is designed for an IPT. The main error sources are related to circumferential anisotropy, to repeatability of US and DS measurements, to effects of instrumentation in 2D losses and to static pressure measurement in the probe environment.

Optimization of combined heat and power cogeneration via modification of low-pressure regenerative system with absorption heat exchanger

The large exergy loss during heat transfer is a key problem for the combined heat and power cogeneration. Instead of the traditional heat source coming from high-grade extracted steam at the outlet of the intermediate-pressure turbine, a novel combined heat and power configuration is proposed for large heat demand by modifying the low-pressure regenerative system. By adding a new LP unit with sufficient extracted flow and heat exchange, a part of the heat source from high-grade extracted steam at the outlet of the intermediate-pressure turbine is replaced by low-grade extracted steam within the LP turbine, avoiding the off-design operation of the LP turbine in the traditional combined heat and power configuration. In addition, the new combined heat and power configuration is optimized by introducing an absorption heat exchanger. The absorption heat exchanger lowers the return temperature of the PHS, which further reduces the energy grade of the heat source. The thermodynamic results show that the electric efficiency of the novel combined heat and power configuration is increased by 4.24% in total at a given heat demand of 241.37 MW. Exergetic results reveal that the exergy loss of two heat exchange links is drastically reduced from 30.47 MW and 26.04 MW to 8.80 MW and 11.81 MW respectively. An economic analysis of the new CHP configuration indicates that the dynamic payback period counteracting the investment increment is only 2.15 years, and the net present value increment over a 25-year period can reach $55.818 million.

Repowering a Coal Power Plant Steam Cycle Using Modular Light-Water Reactor Technology

This article presents the results of a techno-economic analysis of repowering a coal-fired power plant’s steam turbine system to instead accept heat produced by a pressurized water reactor-type small modular nuclear system (PWR SMR). This type of repowering presents a challenge due to the significantly lower steam pressure and temperature produced by the nuclear system. A 460 MW supercritical power unit with steam parameters of 28 MPa/560 °C/580 °C, operated in the Łagisza Power Plant in Poland, was selected for the analysis. After repowering, the turbine system would be fed with saturated steam from the steam generators of the SMRs at a pressure of 7 MPa and a temperature of 285 °C. In total, four options for repowering were analyzed. In all cases, the existing high-pressure section of the turbine was disconnected, and the existing low-pressure stages of the turbine, as well as all auxiliary and outward components (feedwater heaters, pumps, generator, condenser, condenser cooling, etc.), are re-used in their existing configurations, except for a feedwater-heater pump that needs to be replaced. In three cases, the existing intermediate pressure turbine section acts as the high-pressure stage of the repowered system. These cases include repowering without an additional reheater (case A), with an added single-stage reheater (B) and with an added two-stage reheater (C). In the fourth case (D), the existing intermediate pressure section was replaced by a new high-pressure turbine stage suited to the SMR live steam conditions. While all four repowering options are technically possible and may represent an economic advantage compared to a complete greenfield SMR installation, option D with a new high-pressure stage is clearly the best option available, with significant cost savings, leading to a lower levelized cost of electricity (LCOE) and a higher net present value (NPV) and net present value ratio (NPVR) than the greenfield case and all other repowering. For relatively new coal power plants with equipment in good condition, this type of repowering may present a cost optimal near-term pathway.

Performance assessment of supercritical power plant based oil fuel under sliding-pressure operation

Energetic and exergetic analyses of a 626 MWe supercritical power plant-based mazout oil-fired are carried out to assess the system's performance. The energy losses and exergy destruction are evaluated for each system component using real actual data. The results show that the boiler is the primary source of irreversibility with 88.62% of the total exergy destruction. The intermediate pressure turbine maintains an exergy efficiency of 97% at 100%-load. Moreover, the maximum thermal efficiency is achieved at 100%-full load by 44.85% whereas, the maximum overall exergy efficiency of 40% is acquired at the maximum continuous rate condition of 105%-load.

Parametric and heuristic optimization of multiple schemes with double-reheat ultra-supercritical steam power plants

Improvement of energy conversion efficiency in modern steam thermal power plants and minimization of the impact on the environment can be both achieved using ultra-supercritical (USC) parameters and schemes with double-reheat of steam. A methodology is proposed to analyze the energy conversion processes of the double-reheat steam cycles with USC parameters and determine their optimal design. Three types of thermodynamic cycles were considered: a single-reheat benchmark cycle and two double-reheat cycles with different positions of the deaerator. This model finds the best configuration of the preheating system and the optimum reheating steam parameters. Parametric and heuristic multi-objective optimization of energy processes were used for multi-thermodynamic cycles, a synthesis Pareto frontier being computed from the Pareto of the individual cycles to find the best overall solutions. The results prove the benefits of double-reheat cycles for USC parameters, except for low main steam temperatures, where single-reheat cycles are recommended. The solution with the deaerator supplied with steam from the intermediate pressure turbine is usually recommended. For the same specific investment, a 1.22% relative gain of net efficiency was obtained for the double-reheat cycle compared to the single reheat benchmark cycle.

Thermo-economic optimization of the thermal energy storage system extracting heat from the reheat steam for coal-fired power plants

• Thermal energy storage options with reheat steam as a heat source are introduced. • A energy-exergy-economic comparison of three heat storage options is investigated. • Minimum power load ratio of thermal power system can be reduced by 12%-points. • The largest round-trip efficiency is achieved at 67.54% by two-stage heat storage. • Sensible and latent hybrid heat storage has economic advantages than other options. The load cycling range enlargement of thermal power plants is essential to ensure the power grid stability, which can facilitate the penetration of large-scale renewable power. If a part of reheat steam is extracted from the intermediate pressure turbine inlet to the thermal energy storage system, the minimum power load of the coal-fired power plant can be decreased. Moreover, constructing a thermal energy storage system extracting heat from the reheat steam is relatively easy because no modification on the boiler system is required. The reheat steam carries some sensible heat and much latent heat, and how to store the heat efficiently and cost-effectively is investigated in this study. Three thermal energy storage configurations are introduced: configuration A, as a basic configuration, one-stage sensible heat storage; configuration B applied two-stage sensible heat storage; and configuration C applied sensible and latent hybrid heat storage. Thermodynamic and economic performance of three thermal energy storage systems is evaluated and compared. The results show that integrating the thermal energy storage allows the minimum power load to be reduced from 30% to 17.64% of the rated load. Configuration B achieves the largest equivalent round-trip efficiency (67.54%), which is higher 2.56% than that of configuration A, and configuration C exhibits the lowest total cost of the equipment and storage materials (14.75 million USD) and levelized cost of delivery (143.98 USD/MWh), which is 5.94 million USD and 12.69 USD/MWh lower than those of configuration A.

Design and Testing of a Multi-Stage Intermediate Pressure Turbine for Future Geared Turbofans

Abstract The multi-stage intermediate pressure turbine (IPT) is a key enabler of the thermodynamic cycle in geared turbofan engine architectures, where fan and turbine rotational speeds become decoupled by using a power gearbox (PGB) between them. This allows for the separate aerodynamic optimization of both components, an increase in engine bypass ratios, higher propulsive efficiency, and lower specific fuel consumption (SFC). Due to significant aerodynamic differences with conventional low pressure turbines (LPTs), multi-stage IPT designs present new aerodynamic, mechanical, and acoustic trade-offs. This work describes the aerodynamic design and experimental validation of a fully featured three-stage IP turbine, including a final row of outlet guide vanes (OGVs). Experiments have been conducted in a highly engine-representative transonic rotating wind tunnel at the CTA (Centro de Tecnologías Aeronáuticas, Spain), in which Mach and Reynolds numbers were matched to engine conditions. The design intent is shown to be fully validated. Efficiency levels are discussed in the context of a previous state-of-the-art LPT, tested in the same facility. It is argued that the efficiency gains of IPTs are due to higher pitch-to-chord ratios, which lead to a reduction in overall profile losses, and higher velocity ratios and lower turning angles, which reduce airfoil secondary flows and three-dimensional losses.

Study on Losses in the Intermediate-Pressure Steam Turbine Inlet Chamber

Know-how about energy and pressure losses in all steam turbine parts is crucial to guarantee enhanced operational reliability and efficiency. This paper focuses on studying pressure losses in the intermediate-pressure turbine inlet chamber. Measurements were performed on a complex model consisting of the turbine inlet chamber, a compact valve assembly situated upstream, and nozzles located downstream. These intermediate-pressure turbine parts are larger due to the greater volumetric mass flow than the high-pressure turbine parts. However, their inner parts are proportionately smaller, which causes greater pressure losses. Measurements were carried out in the Aerodynamic laboratory of the Institute of Thermomechanics of the Czech Academy of Sciences, where the model was installed in an in-draft wind tunnel. The results were complemented by numerical simulations performed in the Doosan Skoda Power company using ANSYS software tools. Pressure losses were evaluated using the total pressure loss coefficient and, as a result, can be predicted in similar turbine inlet chambers with the required accuracy.

Pressure losses reduction in a steam turbine compact valve

Valves are integral parts of modern steam turbines. They provide flexible operations and fast load changes which have become more often due to the increasing share of renewable energy. Along with this, the low pressure loss is required for guaranteed operation conditions. This paper is concerned with investigation of pressure losses in the compact valve, which is used as a valve for the intermediate-pressure turbine part, and its geometry modification to lower overall pressure losses. The investigation is based on results of numerical simulations which were carried out in the Doosan Skoda Power Company using a package of ANSYS software tools. Source of increased pressure losses in the compact valve is identified and a way of its reduction is proposed based on the comparison of the current results with data from a typical control valve model. Data analysis is provided in the paper.

Safety and thermal efficiency performance assessment of solar aided coal-fired power plant based on turbine steam double reheat

A novel system of solar double reheat hybrid with coal-fired power plant is proposed in this study. Solar energy is employed to reheat the exhaust steam from intermediate-pressure turbine for raising inlet steam temperature of low-pressure turbine. Solar double reheat hybrid with a N600–24.2/566/566 supercritical coal-fired power plant is investigated. An all-condition mechanism model of the hybrid system is proposed and simulated by MATLAB/Simulink in both power-boosting mode and fuel-saving mode. The heat-resistant temperature limit and maximum permissible steam velocity of the low-pressure turbine are discussed in view of turbine safety. According to the simulation results, the maximum solar energy input for safe operation of the turbine is determined as 24,952 kW and 23,486 kW in the power-boosting mode and fuel-saving mode, respectively. Both the solar-to-electricity efficiency and the standard coal saving rate increase with the increase of solar energy input, but decrease with the increase of unit load. Moreover, the solar-to-electricity efficiency of the hybrid system in the fuel-saving mode is generally 2–3% higher than that in the power-boosting mode. In the fuel-saving mode, the highest solar-to-electricity efficiency of 35.17% and standard coal saving of 19.14 g/kWh are obtained with solar energy input of 23,486 kW under 40%THA for the hybrid system. Finally, operation suggestions of the hybrid system are proposed for a higher solar-to-electricity efficiency of solar energy.

A SYSTEMATIC APPROACH IN POWER PLANT PERFORMANCE IMPROVEMENT THROUGH EXERGY ANALYSIS - A CASE STUDY OF TAMNAR, CHHATTISGARH, INDIA

A component-based energy and exergy evaluation was performed on a 600-MW thermal power plant located at Tamnar, Chhattisgarh, India. The main objectives of the current study are first and second law assessment of the power plant's main components and it was observed that the boiler is the main source of energy and exergy destruction followed by the condenser, turbine, and other components at full load conditions. The exergy−energy analysis was utilized for obtaining the exact magnitude of exergy destruction and efficiency in each component separately but for analysis of either major or trivial effects of environment condition variations on plant components. In the current investigations, it is observed that the plant is losing 1025.734 MW of total energy (including all the components) and 1261.413 MW of exergy destruction takes place. A high-pressure heater-5 is found to be the most efficient component with an efficiency of 99.83%. The energy and exergy efficiencies of the boiler are 73.42 and 39.69%, respectively. In the case of turbines, a high-pressure turbine is found to be more efficient as compared to the intermediate pressure turbine and low-pressure turbine. The energy efficiency of low-pressure heater-1, low-pressure heater-2, and low-pressure heater-3 was found to be 99.8, 89.37, and 99.79%, respectively. From the exergy analysis, the exergy efficiency of low-pressure heater-1, low-pressure heater-2, and low-pressure heater-3 was found to be 11.70, 77.70, and 80.6%, respectively. The deaerator is 97.01% efficient and the high-pressure heater-5 and high-pressure heater-6 are observed to have a higher efficiency of 99.83 and 92.02%, respectively. The energy and exergy efficiencies of the condensate extraction pump are found to be 99.48 and 9.56%, respectively.

Pressure losses and oscillations in a compact valve of a steam turbine

Characteristics of a new compact valve design for steam turbines are analysed by measuring pressure losses and oscillations on the valve model. It is the model of an intercept valve of the intermediate-pressure turbine part. This valve is relatively smaller hence cheaper than usual control and intercept valves. Besides, four different valve seat angles were tested in order to investigate the valve seat angle influence. In order to further clarify measured phenomena, the wide range of numerical simulations were also carried out. Measurements were performed in the Aerodynamic laboratory of the Institute of Thermomechanics of the Czech Academy of Sciences in an air test rig installed in a modular aerodynamic tunnel. Numerical simulations were performed in the Doosan Skoda Power Company using a package of ANSYS software tools. Measurement results are compared with numerical and generalized in the form of valve characteristics and pressure oscillation maps. As a result of the pressure loss analysis, pressure losses in similar valve assemblies can be predicted with required accuracy for each new turbine where modern compact valves are used. As a result of the pressure oscillation analysis, operating conditions at which dangerous flow instabilities can occur were identified. Thanks to this, the areas of safe and dangerous operating conditions can be predicted so that the operational reliability of the valve can be guaranteed.

Exergy and exergo-environmental analysis of a 660 MW supercritical coal-fired power plant

This paper presents the exergy and exergo-environmental analysis of the 660 MW supercritical coal-fired unit situated in western India. The study is based upon the SPECO approach, which is followed in the case of exergoeconomic analysis. The proposed research includes evaluating values of exergy of each stream, using F and P principal to find out exergy of fuel, the product of each component, and its exegetic efficiency. It further includes allocation of Eco-indicator 99 assessment grading values to perform life cycle assessment of each component, solving simultaneous equations by suitable solver formed from the environmental impact of components to calculate the exergo-environmental factor of each stream. The exergy efficiency obtained for the supercritical unit is 35.54%. The effect of variation of exergetic efficiency with an inlet pressure of high-pressure turbine for major components is studied. The major components such as steam generator, high-pressure turbine, intermediate-pressure turbine, low-pressure turbine, condensate extraction pump, and boiler feed pump exhibit higher exergetic efficiency at 247 bar. An increase in environmental impact in the exergy flows has been identified for components with having heat, work or fuel at the inlet. The cooling water used in condenser and flues gases exhausted from the supercritical power plant represent the environmental impact rate per unit electricity generated of 2.89 and 3.689 mPts kWh−1. The electricity generated had an environmental impact rate of 39.71 mPts kWh−1. The environmental impact per unit of electricity generated for 660 MW supercritical power plant is evaluated as 46.29 mPts kWh−1. The result obtained from semi-empirical model for environmental impact per unit of electricity is validated by comparing with subcritical and ultra-critical coal-fired power plant. The supercritical coal-fired power plant is proved to be better technology as compared with subcritical coal-fired power plant. The exergo-environmental variable for the steam generator offers high potential to reduce environmental impact by introducing an exhaust gas treatment unit.

An integrated de-carbonization supercritical coal-fired power plant incorporating a supplementary steam turbine, process heat recovery and a modified boiler structure

Monoethanolamine (MEA) based CO2 capture in coal-fired power plants would consume a huge amount of the steam bleed from the steam turbines for the solvent regeneration. The unmatched steam bleed parameters for the solvent regeneration, as well as the huge amount of the process waste heat within the CO2 capture process, inevitably bringing about a significant efficiency penalty. In this study, a novel de-carbonization supercritical coal-fired power plant, which encompasses a supplementary steam turbine (SST), process heat recovery and a modified boiler heating exchangers configuration was proposed. In the proposed system, the steam bleeds for the reboiler and part of the regenerative heaters are coming from the SST, which is located in the upstream of the reheater (steam side), instead of the high and intermediate-pressure turbines (IPT), making the parameters of the steam bleed more matched with the solvent regeneration and feed water heating. In addition, part of the process heat within the CO2 capture/compression unit was efficiently recovered and beneficially used to heat the ambient air before its entering the air pre-heater. The saved flue gas can then be used to heat the feed/condensed water in the low-temperature economizer (LTE), saving part of the steam bleed from the turbines. The configuration of the superheaters/reheaters, as well as the air preheaters were also modified. The mass and energy balance as well as the system thermodynamic performance were determined by the developed models and process simulation. The economic performance of the proposed system was assessed by the cost of electricity (COE) and the cost of CO2 avoided (COA). Finally, the off-design performance of the proposed system was determined. Results showed that the energy efficiency penalty of the proposed system could decrease by 3.86%-points as compared to the reference system. The COE and COA of the proposed system without considering the CO2 transportation and storage cost were $86.11/MWh and $36.92/ton CO2, respectively, both less than those of the reference plant. The off-design operation analysis indicated that the proposed plant also featured a thermodynamics superiority in a wide range of power load variation.

Energy-Exergy Analysis of Combined Reheating-Regenerative Rankine Cycle using Entropy Generation Principle

The growing attention towards the exergy analysis of thermal systems is identifying the cause of losses, to scale the process, and rectifying the components. In this paper, the thermodynamic (energy-exergy) analysis of combined reheating and regeneration based Rankine Cycle is carried out. The energy-exergy analysis has been established for the boiler, turbines, Feed heaters, condenser and pump majorly. The result of thermodynamic analysis is estimeted in terms of 42% of plant thermal efficiency, 70 % of steam generation unit efficiency (Economizer. Super heater), Maximum heat absorbed by economizer of plant as 39% is achieved, with 40TPH of coal consumption. Boiler, High Pressure Turbine, Intermediate Pressure Turbine, Super Heater have found best performance in analysis and Reheating-Regenerative rankine method improves 6-8% in thermal efficiency also. This analysis concluded that energy efficiency is greater than exergy efficiency which identifies the power plant utilities and further improvement for efficient power generation opportunities like waste heat recovery technology employment.

Thermodynamic and Economic Analyses of Reformative Design for High Back-Pressure Heating in Coal-Fueled Cogeneration Units.

High back-pressure (HBP) heating technology has been identified as an effective approach to improve the efficiency of combined heat and power (CHP). In this study, the novel concept of a HBP heating system with energy cascade utilization is developed and its probability examined. In the reformative design, the extracted heating steam from the intermediate-pressure turbine (IPT) is first drawn to an additional turbine where its excess pressure can be converted into electricity, then steam with a lower pressure can be employed to heat the supply water. As a consequence, the exergy destruction in the supply water heating process can be reduced and the efficiency of the cogeneration unit raised. A detailed thermodynamic investigation was performed based on a typical coal-fired HBP–CHP unit incorporating the proposed configuration. The results show that the artificial thermal efficiency (ATE) promotion was as much as 2.01 percentage points, with an additional net power output of 8.4 MW compared to the reference unit. This was attributed to a 14.65 percentage-point increment in the exergy efficiency of the supply water heating process caused by the suggested retrofitting. The influences of the unit power output, unit heat output, supply water and return water temperatures and turbine back pressure on the thermal performance of the modified system are discussed as well. In addition, the economic performance of the new design is assessed, indicating that the proposed concept is financially feasible.