Gas-steam Combined Cycle Power Research Articles

Gas turbine multi-working conditions identification and performance prediction based on deep learning and knowledge

Performance prediction is crucial for monitoring, controlling and optimizing gas turbine (GT) operations. Due to significant performance variation under different working conditions, a single model cannot adequately represent all scenarios. In this paper, we propose a novel multi-working conditions performance prediction framework for GT, leveraging deep learning and professional knowledge. The GT is used in gas-steam combined cycle power plants that utilize low calorific value gases. A unique multi-working condition identification model has been established, enabling accurate identification of the current operating status of GT. Additionally, a dynamic model has been developed to fully utilize the temporally varying data. The entire GT model, spanning from unstart to steady-state, is constructed through model fusion using a mathematical mechanism. Compared to the single working condition model, our approach demonstrates superior performance prediction results on the actual GT operating dataset. The mean square error (MSE), mean absolute error (MAE) and correlation coefficient (CORR) are 0.7501, 0.5872, and 0.9973, respectively. These results highlight a substantial improvement in prediction accuracy and robustness outperforming the single working condition model in same contexts, effectively capturing operational characteristics and offering valuable insights for optimizing GT operations. The findings may also contribute to advancing GT research.

Comparison of model-driven soft measurement methods for compressor air flow in gas-steam combined cycle power units

The determination of the air flowrate at the compressor inlet is meaningful for the performance diagnosis of heavy-duty gas turbine combined cycle (GTCC) power units, whereas the compressor air flow generally cannot be directly obtained from the field data. In this paper, the procedures of three model-driven methods for soft measurement of compressor air flow were presented, including energy balance of the coupled HRSG (M1), static pressure at the compressor manifold (M2) and gas turbine joint operation line method (M3). In the case of a M701F4 GTCC power unit, the methods M1 and M3 were validated by the field and testing data; while the method M2 was calibrated and the effective area at the air manifold was decided as 12.606 m2 using M1 at the full load of gas turbine. The compressor air mass flow at overall loads was computed with the various methods. The comparative investigation to these methods shows that, the compressor inlet air flow is determined as 682.75 kg/s by M1 and 664.07 kg/s by M3, respectively, at the full load and at the ambient temperature 29.912 °C. The air flow obtained by M1 and M2 appears relatively higher than that by M3 at typical various loads of gas turbine; however, the method M3 shows a good accordance with the actual value of the air flow for turbine rotor cooling. Both M2 and M3 agree in the theoretical demonstration that compressor air flow is strongly related to the gas turbine load at certain conditions. The method M1 can be deemed as a reference for another two methods in the case of the steady operating state at full load; whereas it is not recommendable for the real-time measurement of compressor air flow, because of the large amounts of required input variables and the fluctuation in the flow meters.

An improved performance diagnostic method for industrial gas turbines with consideration of intake and exhaust system

Industrial gas turbines, as core equipment for efficient and clean utilization of energy, have been widespreadly applied in gas-steam combined cycle power plants. To ensure safe, stable, green and efficient operation, it is essential to establish a reliable industrial gas turbine fault diagnosis system. Industrial gas turbines need more flexible operation, due to requirements for power plant frequent frequency regulation and peak regulation in grid-supported mode. It is difficult to filter out quasi-steady-state operation data segment from collected operating data of industrial gas turbine, which makes the applicable boundary of traditional diagnostic methods narrower. For the actual problems to be solved urgently during diagnosis of industrial gas turbines, this paper proposes an improved performance diagnostic method for industrial gas turbines. First, a high-precision thermodynamic modeling method for industrial gas turbines was proposed with consideration of the effect of variable geometry compressor, and the established gas turbine thermodynamic model is validated by actual industrial gas turbine operation data. Next, an improved performance diagnostic method is established, and the health parameters for intake system and exhaust system is proposed in fault diagnosis for the first time and compressor variable geometry is also considered in the diagnostic process. Finally, through actual industrial gas turbine operation test, the effectiveness and reliability of the proposed diagnostic method to diagnose component performance degradation and component abrupt performance damage are verified. The proposed diagnostic method realizes real-time online quantitative diagnosis of all gas-path components under full operating conditions from the minimum IGV opening load to the IGV fully open base load.

Thermodynamic simulation and economic analysis of combined cycle with inlet air cooling and fuel pre-heating: Performance enhancement and emission reduction

Gas-steam combined cycle power plant (CCPP) performance suffers from sensitivity to ambient condition, higher fuel consumption rate and greenhouse gas emission. Several solutions were adapted to resolve one or two problems with expense of other. In this study, a hybrid process for compressor inlet air cooling (CIAC) and fuel pre-heating (FPH) is proposed to enhance the CCPP performance with simultaneous reduction in fuel consumption and emission. Three simulation cases have been presented for CCPP design and off-design mode of operation at a site-specific condition. The result shows that, compared to conventional cases the influence of CIAC and FPH leads to capacity increment of 10.7% to 12.7 % with load variation from 40% to 100%. The associated overall efficiency enhancement is 2.2 – 0.58% when ambient air temperature Ta cooled from 35 °C to 15 °C operating at site condition Ta = 35 °C, RH = 65%. The sensitivity analysis is performed based on monthly mean weather data. The rate of fuel consumption and CO2 emitted are considered per unit of power generated. The CO2 emitted is maximum at low Ta in the range of 26 – 28 °C and lower RH. The CCPP at its full-load, for an operating period of 24 h the fuel consumption will reduce approximately to 12226 kg and this will lead to saving in operating cost of 4307 dollars per day.

Thermodynamic performance study on gas-steam cogeneration systems with different configurations based on condensed waste heat utilization

In view of the limited application of the traditional water-cooled GSPP (gas-steam combined cycle power plant) in water-deficient areas, an air-cooled GSPP is proposed based on AHP (absorption heat pump) to achieve conservation of energy and water in this paper. The thermodynamic performance is comprehensively compared with three other configurations from both the energy and exergy analysis perspectives. Four cogeneration systems are considered: traditional water-cooled GDES (GSPP with direct extraction steam for heating), water-cooled GAS (GSPP with AHP system), air-cooled GDES and air-cooled GAS. Compared with water-cooled GDES, net output power, energy and exergy efficiencies increase by 17,815 kW, 1.43% and 1.53% in air-cooled GAS with 384,382 kW heating capacity. The results demonstrate that the performance of an air-cooled GAS can surpass that of a traditional water-cooled GDES, which shows that the energy-saving effect of waste heat recovery can compensate for the performance reduction caused by air cooling modification. Therefore, the traditional water-cooled GDES can be modified into an air-cooled GAS to implement dual purposes of saving energy and water in water-starved regions. The water-cooled GAS achieves the best performance and should be selected in water-rich areas. This research can provide theoretical support for different energy- and water-saving modification needs.

Liquefied natural gas re-gasification cold energy hybrid system integration in gas-steam combined cycle power plant model: Enhancement in power generation and performance

• Hybrid system integration that uses a secondary chilled water circuit is proposed. • Significant enhancement of power output occurs at higher ambient temperature. • The hybrid system produces higher cooling duty. • The efficiency gain is at best marginal and depends on the integration approach. The liquefied natural gas (LNG) cold energy utilization for inlet air cooling (IAC) to augment combined cycle power output is widely recognized as a feasible and sustainable alternative. However, issues with flexible operation and hybrid system integration still remain in warm climate region. To take the edge off from such kind of issues and to enhance the power generation and the performance, few possible opportunities are explored for a gas-steam combined cycle power plant (CCPP) with thermal integration of LNG re-gasification cold energy. Three integration approaches, such as 1st gas turbine IAC, 2nd condenser water cooling (CWC) in steam turbine cycle and 3rd combined approach of both IAC and CWC are proposed. Thermodynamic modeling and simulation-based method is adapted for CCPP model identification and thermodynamic performance comparison. Moreover, the results are established as a function of relative humidity and ambient temperature along with off design power generation of the proposed system. The result shows that the CCPP relative power improved from 1.01% to18.48% (for third integration approach) and 0.17% to 0.217% (for second integration approach), in the ambient temperature range of 13–45 °C and relative humidity of 90–40% respectively, compared to that of non-integrated CCPP. In third integration approach the relative efficiency enhancement is observed in the range of 0.05–0.40%, particularly in higher range of ambient conditions. In second integration approach the CCPP efficiency enhanced from 0.17% to 0.22% in ambient temperature range of 13–45 °C and relative humidity 40–90%.

Data modelling and simulation control of steam heat circulation system in coal-fired power plant

To make up for the lack of domestic research on the dynamic model of the unit in a gas-steam combined cycle power plant, the thesis researched and established a real-time digital simulation model of the combined cycle power plant unit. Firstly, the theory found a non-real-time digital simulation model in MATLAB/SIMULINK environment. Then the paper converts it into C language code and uses the C Builder tool to encapsulate it into a simulation model that can run in real-time. Finally, the thesis conducted a simulation test on the model on real-time digital simulation and compared it with the field test results. The simulation results show that the combined cycle power plant unit model we have established can meet the real-time simulation requirements of the power system in terms of computational efficiency and model accuracy.

A new perspective of thermoeconomic analysis on a gas-steam combined cycle power plant

In this study, we have applied the H&S model to a gas-steam combined cycle power plant (CCPP) and further explore its advantages for thermoeconomic evaluation. We introduce how E&S model irrationally assesses the performance of both productive and dissipative components from the viewpoint of fuel-product model. Then, we build the thermoeconomic model of a typical gas-steam CCPP based on H&S theory and show the potential of improvement for each component. For a CCPP, the results indicate that reducing non-energy cost of the steam turbine (ST) and the irreversibility of the combustion chamber (CC) can significantly lower the thermoeconomic cost of electrical power. For the condenser (CND) and stack (STA), the dissipative cost is responsible for the most of their thermoeconomic cost. It is concluded that thermoeconomic performance evaluation based H&S model gives a more reasonable result and can support the research on thermoeconomic optimisation.

A new perspective of thermoeconomic analysis on a gas-steam combined cycle power plant

A new perspective of thermoeconomic analysis on a gas-steam combined cycle power plant

Optimization Potentials for the Waste Heat Recovery of a Gas-Steam Combined Cycle Power Plant Based on Absorption Heat Pump

A new waste heat recovery system is presented to recover exhausted steam waste heat from the steam turbine by absorption heat pump (AHP) in a gas-steam combined cycle (GSCC) power plant. The system can decrease energy consumption and further improve the energy utilization. The performance evaluation criteria are calculated, and exergy analysis for key components are implemented in terms of the energy and exergy analysis theory. Besides, the change of these criteria is also revealed before and after modification. The net power output approximately increases by 21738 kW, and equivalent coal consumption decreases by 5.58 g/kWh. A 1.81% and 1.92% increase in the thermal and exergy efficiency is respectively obtained in the new integrated system as the heating load is 401095 kJ at 100% condition. Meanwhile, the appropriate extraction parameters for heating have been also analyzed in the two systems. The proposed scheme can not only save energy consumption but also reduce emission and gain great economic benefit, which is proven to be a huge potential for practical application.

Upgrading existing gas-steam combined cycle power plants through steam injection and methane steam reforming

The growth in worldwide energy demand currently faces the difficulty of installing new power generation facilities due to limited funding and the strengthening of environmental regulations. Owing to the increasing role of natural gas combined cycles (NGCCs) in the power generation infrastructure, it is important to assess the energy and economic feasibility of upgrading their capacity to cope with future energy requirements.This study aims to investigate a new concept for upgrading existing NGCCs by integrating an additional unit based on gas turbine. The additional unit allows the production of steam to be injected into the NGCC combustor (Option A) or syngas from methane steam reforming to be fed into the existing power plant (Option B) or even into the additional gas turbine (Option C). The power output augmentation arises from the capacity of the additional gas turbine and the increase in power production of both gas cycle and bottoming steam section of the NGCC. A preliminary sensitivity analysis assesses the influence of operating conditions of the additional unit on the energy and economic performances of marginal power production. Considering commercial gas turbines, further investigations address the design of upgrading options and the comparison of their techno-economic performances referred to the additional or the overall power productions. Finally, focusing on Option A, the part-load operation of the additional gas turbine is examined to evaluate penalties on marginal efficiency and marginal cost of electricity.Simulation results revealed that for a power augmentation lower than 50%, Option A provides the best economic performance combined with the highest operational simplicity, while Option C is the preferred technical solution for a greater increase in plant capacity.

Performance analysis of a gas turbine combined cycle power plant with waste heat recovery in Organic Rankine Cycle

Abstract Gas-steam combined cycle power systems currently are the most advanced power systems operating with fossil fuels since offer the highest efficiency level and lowest pollution. Even so, amount of waste heat released with flue gas into the atmosphere is still significant. A typical way to recover it is heat production but this solution is not viable when there is no heat demand. The interest in this case is for production of additional power. A possible solution is to add an organic Rankine cycle unit downstream the gas-steam combined cycle power plant, which thus is converted into a gas-steam-organic combined cycle power plant. The performance of such a power system, based on Orenda OGT15000 gas turbine with 16.5 MW output in simple cycle, is analyzed in the paper. Besides, the fuel savings and their cost are assessed. Two organic working fluid were considered, namely R134a and R123. The study shows that efficiency of the power plant increases by roughly 1.1 % when the ORC unit is added. Taking into account the current concerns regarding the fossil fuel depletion, the estimated fuel savings could be considered significant.

Exergetic evaluation of gas-turbine based combined cycle system with vapor absorption inlet cooling

The aim of this study is to perform an exergetic evaluation of a gas-steam combined cycle power utility that is integrated with vapor absorption inlet air cooling system. Effect of several thermodynamic parameters on component-level and total exergy destruction are discussed. A detailed breakdown of exergy destruction in the cycle has been presented along with useful recommendations to improve exergy based cycle performance. The integration of inlet air cooling has been observed to increase exergy efficiency of combined cycle beyond a turbine inlet temperature of 1650 K. The combustor has been identified as the greatest source of irreversibility with highest exergetic improvement potential. The total exergy destruction for the cycle has been observed to reduce with increase in turbine inlet temperature (TIT) and decrease in compressor inlet temperature (TIC). At higher compressor pressure ratio (βcomp), except combustor all other components of topping cycle has been observed to suffer an increase in exergy destruction where as exergy destruction has been observed to reduce for all bottoming cycle components except the stack. The summation of exergy destruction of all cycle components is observed to be reduced at lower ambient relative humidity and lower ambient temperature.

Comparative study on off-design characteristics of CHP based on GTCC under alternative operating strategy for gas turbine

As the rising proportion of natural gas in China energy structure, gas-steam combined cycle based CHP (combined heating and power) systems are expected to have wider applications. To study the performance of CHP systems under two different operating strategies, i.e., IGV (inlet guide vanes) strategy and TIT (turbine inlet temperature) strategy, a stage-stacking method was used for axial-flow compressor characteristics, a stage-by-stage model including blade cooling was adopted for the turbine, and analytical method was employed to solve HRSG (heat recovery steam generator) part-load performance. The model was validated by the field data from an existing MPCP1-M701F3 gas-steam combined cycle power unit. Maximum and minimum steam extraction lines for heating supply were obtained. The selection of operating point between the two lines to meet the same heating demand was discussed from the views of economic benefit and energy utilization efficiency. The results show that, compared to TIT strategy, CHP system with IGV strategy shows advantages in PES (primary energy saving) and total energy utilization efficiency whereas disadvantages in heat to power ratio under part-load conditions. Otherwise, for the same operating range of TIT, CHP system with IGV strategy can reach broader performance at the same steam extraction ratio.

Thermodynamic analysis and optimization of a two-stage organic Rankine cycle for liquefied natural gas cryogenic exergy recovery

A two-stage ORC (organic Rankine cycle) is proposed, by which low-grade heat of exhaust flue gas of a 123.5 MW gas-steam combined cycle power generating unit, as well as the cryogenic energy of LNG (liquefied natural gas) can be effectively recovered and utilized. R227ea and R116 are selected as working fluids for the system. Based on the thermodynamic mathematical models, the effects of key design parameters, including that of turbine inlet pressures, mass flow rates of working fluids and outlet steam fractions of evaporators on the system performance are investigated from the view of both thermodynamics and economics with CPP (cost per net power output) as the objective function. The results obtained the optimal inlet pressure of turbines, under which, the CPP has the minimum value. It is found that the CPP also decreases with the mass flow rate of R227ea and R116. The rate of absorbed heat in top cycle to that in bottom cycle has a positive impact on CPP, but very weak. The optimized two-stage ORC system can output net work with 1776.44 kW with the thermal efficiency of 25.64% and exergy efficiency of 31.02%. Cost per net power output is 6.3$/W, while the LNG temperature can be raised to 283.15 K.

Construction of the Decision Method Based on Energy Saving and Reduction of Greenhouse Gas Emissions

This paper intends to improve the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method in view of the traditional TOPSIS method and combines with the current development of Chinese enterprises. By determining the index weights and attributes, it also constructs a new enterprise decision-making method which based on energy saving and greenhouse gas emissions. According to the survey's raw data, this paper not only calculates the energy levels of conventional coal-fired power plant in North China and an integrated gasification gas-steam combined cycle (IGCC) power plant, but also computes their carbon dioxide emissions. The results show that under the same circumstances, the energy consumption of IGCC power plant is lower than that of the conventional coal-fired power plants, has less carbon dioxide emissions, lower carbon intensity and higher carbon productivity. On the basis, using the improved TOPSIS method, the paper calculates the numerical superiority of two schemes and sorts of them, verified the correctness of this construction method.

A Feasibility Urban Power Network Black-Start Scheme Based on Gas-Steam CCPP

This paper designs and discusses black-start scheme based on a gas-steam combined cycle power plant (CCPP) in Tianjin power grid of China. First, considering the structure characteristics and station service power connection mode of the gas-steam unit, the diesel generator is chosen as fast self-starting unit. Also two self-starting schemes of direct starting and variable frequency starting are designed. Second, the technical feasibility of two schemes is determined through first loading capability test and bus voltage level test. After investment estimation comparison, the scheme II is chosen as recommended scheme. The research process proposed in this paper has certain reference significance to power grid black-start.

Risk Analysis and Safety Evaluation on Combustion System of Gas-Steam Combined Cycle Power Plant

Under the general policy of the national energy-saving emission reduction and sustainable development, the domestic iron and steel enterprises surge in the by-product gas power generation project. There exist many dangerous and harmful factors in by-product steel gas power generation process and which easily caused casualties and the pollution of the environment. The study on risk analysis and evaluation are still relatively dearth about the by-product gas generating process of domestic steel enterprises. The boiler system on a Combined Cycle Power Plant was analyzed and evaluation by ICI/MOND fire and explosion toxicity index method and the method of fault tree analysis, which combined with the actual situation of steel plant Combined Cycle Power Plant. The results show that the combustion system is more dangerous, and the hazard index levels are reduced to lower level after safety compensatory measures except the unit toxicity index higher. The shielding device or gas alarm failure was the main cause of gas poisoning. According to the analysis some feasible measures was put forward. The study has positive guiding significance for risk management and safety administration decision of the Combined Cycle Power Plant.

Application Research of Intake-Air Cooling Technologies in Gas-Steam Combined Cycle Power Plants in China

The generated power and efficiency of gas-steam combined cycle (GSCC) power plants depend on the temperature of the inlet air greatly. Based on the analysis of basic theory of inlet air cooling technologies, the application of evaporative cooling system and the absorption cooling system in GSCC power plants are discussed in this paper. Moreover, in China with high temperature and humidity, applied research and simulation analysis of the above two different cooling systems are conducted separately, the research results of which can provide certain reference for optimal design and economic operation of inlet air cooling system for GSCC power enterprises in China.

Analysis of Inlet Air Cooling for IGCC Power Augmentation

Integrated Gasification Combined Cycles are energy systems mainly composed of a gasifier and a combined cycle power plant. Since the gasification process usually requires oxygen as an oxidant, an air separation unit is also part of the plant. Moreover, a producer gas cleaner unit is always present between the gasifier and the gas turbine.With respect to Natural Gas Combined Cycles, IGCCs are characterized by a consistent loss in the overall plant efficiency due to the conversion of the raw fuel in the gasifier and the electrical power parasitized for fuel production which considerably reduce the plant net electric power. Moreover, since these plants are based on gas-steam combined cycle power plants they suffer from a reduction in performance (a further net power decrease) when ambient temperature increases. Regarding this latter topic, different systems are currently used in gas turbine and combined cycle power plants in order to reduce gas turbine inlet air temperature, and, therefore, the impact of ambient conditions on performances.In this paper, a review of these systems is presented. Both systems based on water evaporative cooling and on refrigeration by means of absorption or mechanical/electrical chillers are described.Thermodynamic models of the systems are built within the framework of a commercial code for the simulation of energy conversion systems. A sensitivity analysis on the main parameters is presented. Finally, the models are applied to study the capabilities of the different systems by imposing the real temperature profiles of different sites for a whole year.