Compressor Inlet Air Temperature Research Articles

Study on the thermodynamic performance of a coupled compressed air energy storage system in a coal-fired power plant

Coupled energy storage can improve flexibility levels, increase renewable energy consumption, and alleviate the energy crisis of thermal power systems. In this article, 11 coupling schemes for the CAES and CFPP systems are proposed, and a mathematical model for the coupled system is established. An optimal coupling scheme is determined through simulation analysis and comparison by using the heat rate and energy utilization coefficient as evaluation indicators. In the energy release stage, the energy utilization coefficient of the coupled system increases by 2.842 %, and the heat rate in the energy storage stage decreases by 50.546 kJ · (kWh) −1, with a return water temperature of 120 °C. The effects of key parameters, such as compressor inlet air temperature, storage chamber pressure, and expander inlet temperature, on the thermodynamic performance of the coupled system are explored, and the NSGA-II multiobjective optimization algorithm and TOPSIS optimization algorithm are used to optimize the key parameters and obtain the optimal performance-related parameters of the system: a compressor inlet air temperature of 35 °C, expander inlet air temperature of 105.4 °C, and storage pressure of 9.105 MPa. At this time, the RTE of the system is 55.573 %, and the ηhe value is 1.59. The results indicate that the coupled CAES energy storage stage can assist the CFPP in absorbing renewable energy, and the energy release stage can alleviate the pressure of its high electricity load demand, effectively improving its flexibility.

Comparative analysis and optimization of thermodynamic behavior of combined gas-steam power plant using grey-taguchi and artificial neural network

In the published studies, to the best of the authors’ understanding, the grey Taguchi-based statistical technique has not been applied for the optimization of combined gas-steam power plants. In view of this, seven essential input parameters namely compressor inlet air temperature, pressure ratio, fuel temperature, volumetric flow rate of fuel, gas turbine maximum temperature, compressor efficiency, and turbine efficiency are chosen with the aim of determining the optimal combination of design variables that maximize the net power generation, thermal efficiency, exergetic effciency, and minimize the specific fuel consumption. Also, the impact weight of each parameter on output indicators has been evaluated. While the Taguchi approach helps to create an orthogonal array of L27 (3^7), the ANOVA method determines the contribution of each input argument on the objective function. Unlike the Taguchi and ANOVA optimization methodology, the grey relational analysis is performed to transform the multi-objective function into a single objective by way of estimating its grey relational grade. The most favorable combination of input parameters is determined as A1B1C1D1E3F3G3 and under this state, the optimum values of power generation, thermal efficiency, exergetic efficiency, and specific fuel consumption are found to be 259911 kW, 64.9 %, 66.27 %, and 0.1839 kg/kWh respectively. Moreover, the contribution ratio on the output characteristic of the combined cycle is found to be maximum for turbine efficiency (42.41 %) and minimum for fuel temperature (0.59 %). The effectiveness of the grey-Taguchi method is acknowledged and validated using an artificial neural network technique in MATLAB.

A novel water freezing desalination plant integrated into a combined gas power cycle plant

In this work, a freezing desalination unit is integrated into a conventional combined power plant to improve the plant performance and produce desalinated water. A mathematical model is developed to simulate the modified cycle. The effect of compressor inlet air temperature on thermal performance, desalinated water production capacity and specific fuel consumption is examined. Results of the modified cycle were compared to that of the conventional cycle. The results show that the proposed system is capable of producing up to 2.74 million m3of desalinated water annually from a brackish water source (TDS of 2000 mg/l) with an increase in the Energy Utilization Efficiency (EUE) by 15% as compared to the designed value under ISO standard conditions. Furthermore, operation cost for fresh water production is also examined, results show that the fuel cost of 1 m3 of desalinated water varies between (0.56–0.58) $/m3 compared with 0.66 $/m3 and 0.93 $/m3 for desalination technologies of R. O and MED, respectively.

Efficiency-Focused Maintenance Model to Recover the Performance of a Gas Turbine with Inlet Air Cooling and Affected by Fouling

Efficiency-Centered Maintenance (ECM) models are vital in the industry since they increase the overall efficiency of the system and the availability of assets, considerably reducing polluting emissions and operating costs. Because of this, it has been tried to quantify the potential of ECM models in improving power generation systems. This paper presents an ECM model to recover the performance of a gas turbine that has suffered performance degradation due to exposure to fouling and variations in the compressor inlet air temperature. A strategy has been designed and implemented in order to define and schedule activities that, economically and energetically justified, have restored the performance of a simple Brayton cycle power generation facility. The net power output and the Heat Rate have been the performance indicators selected for monitoring the energetic condition of the gas turbine. Similarly, the availability and the mean time between interventions have been maintenance indicators. The results indicate that net power and availability have increased by 5%, the Heat Rate has decreased by 2%, and the mean time between interventions has increased by 5.7 times. The power degradation rate has been reduced from 9% to 1%, ending with an annual degradation of 7.4%. With the results obtained, it has been confirmed that the ECM applied to power cycles increases the system's operational efficiency, reducing costs and polluting emissions.

Inlet air fogging strategy using natural gas fuel cooling potential for gas turbine power plants

Fogging is an effective cooling system used for gas turbine (GT) inlet air cooling. In this study, three fogging strategies were tested: direct fogging, fogging with a natural gas (NG) heat exchanger (FNGE), and FNGE using a storage tank (FNGET). The discrete phase model (DPM) with the standard k-ω turbulence model was used. A computational parametric study was conducted using the standard k-ω turbulence model on a GT compressor inlet duct to optimize the effect of the FNGET cooling strategy. The effects of duct length, number of nozzles, uniform droplet diameter, and nozzle angle on the compressor inlet air temperature and relative humidity (RH) were examined in this parametric study. A duct with 15 m length, 48 nozzles in each half, 100 μm droplet diameter, and 60° nozzle angle exhibited the maximum decrease in the temperature of the compressor inlet air. The minimum (maximum) reduction in temperature was 5.54 °C (15.77 °C), which was observed at 30 °C (40 °C) ambient dry-bulb temperature (DBT) and 60% (15%) RH. The minimum (maximum) increase in the GT output power was 8.99 MW (26.44 MW), or 3.87% (11.15%), which was under the ambient conditions of 34 °C (30 °C) and 60% (15%) RH. The maximum enhancement in GT thermal efficiency was 1.47%, which occurred under the ambient conditions of 30 °C DBT and 15% RH. The maximum decrease in GT specific fuel consumption (SFC) was 4.30%, which was seen under the ambient conditions of 30 °C and 15% RH. FNGET was the most effective cooling strategy in terms of GT output power, thermal efficiency, and SFC. This novel cooling strategy can be applied to various GT models.

THE EFFECT OF BEND ANGLE ON THE EVAPORATIVE COOLING OF AIR FLOW THROUGH BENT DUCT

One remediation to output power drop of a gas turbine generating units during hot climates is reducing compressor inlet air temperature using fogging technique incorporating water injection into the airstream. The inlet air ductworks often include a bend or curved duct before the compressor comprising the secondary flow utilized to enhance the mixing between air and water droplets. This study investigates the effect of changing the bend angle on the resultant evaporative cooling of steadily flowing airstream. The experiments were conducted with an average air velocity range from (2.5 to 5 m/s) through (50) cm square duct. The study considered three bend angles of (45°, 90° and 135°) along with three sets of nozzle tilt angles of (- 45o, 0° and 45° ) to the axial flow direction. The results reveal that best evaporative cooling was achieved at a bend angle of (135°) when the water is axially injected, i.e., at (0o) to flow direction. These conditions were obtained at the velocity of (2.5 m/s), giving enough residence time for the injected droplets to evaporate and cool the airstream.

Thermoeconomic cost analysis on operation strategies of gas turbine combined cycle under off-design conditions

In this paper, the thermoeconomic cost model of a typical gas turbine combined cycle (GTCC) system is established based on the structure theory of thermoeconomics. Because the operation strategy is the basis of the research on the design/off-design condition of GTCC unit. Therefore, the GTCC thermoeconomic performances with different strategies using the inlet guided valve (IGV) control are compared based on the GTCC cost model to analysis the influence of the main parameters on the unit thermoeconomic cost of each component. The variation rules of the thermoeconomic performances of the GTCC unit under design/off-design operating conditions influenced by the operating strategy and ambient temperature are revealed. The results show that the GTCC with the IGV T3-650-F operation strategy has the lowest thermoeconomic cost. Changing the operation strategy of gas turbine (GT) can reduce the generator (GEN) unit thermoeconomic cost. And higher GT inlet/outlet temperature is helpful to reduce the thermoeconomic cost of combined cycle under off-design conditions. The investment on the steam turbine (ST) and the irreversibility of the combustion chamber (CC) have the important influence on the thermoeconomic cost of GTCC system. Reducing the air compressor (AC) inlet air temperature can reduce the thermoeconomic cost of GTCC system.

Load-regulation characteristics of gas turbine combined cycle power system controlled with compressor inlet air heating

Enhancing the peak-regulation performance of gas turbine combined cycle power units is significant in renewable energy accommodation. To improve the peak-regulation efficiency of the power units, the performance of the retrofitted system with compressor inlet air heating under alternative load-regulation strategies was comprehensively investigated. Three strategies were adopted, including inlet guide vane (IGV) control with constant turbine inlet temperature, IGV control with constant turbine exhaust temperature, and fuel flow control (FFC) to perform a comparative analysis of the system performance using a physical model, which was validated using a mathematical model. Operating charts of the retrofitted system were obtained and the effects of the compressor inlet air temperature on the power load rate were further investigated. The analysis indicates that FFC is preferred for gas turbines owing to the lowest exhaust temperature, and IGV control strategies are advantageous to the combined cycle power system owing to the performance improvement of the bottoming cycle. When the compressor inlet air is heated from 15 to 35 °C at the specific gross output of 320 MW, the gas turbine load rate increases by 4.16 and 3.01% under IGV control with constant turbine exhaust temperature and FFC, respectively, and the relative combined cycle power efficiency increases by 0.015 and 0.023, respectively. For a load power of 360 MW at the ambient temperatures of 5, 15 and 25 °C, the optimum outlet air temperature of the recuperator decreases from 32.0, 31.6 to 28.8 °C, respectively for IGV control with constant turbine exhaust temperature.

Improvement of part-load performance of gas turbine by adjusting compressor inlet air temperature and IGV opening

Improvement of part-load performance of gas turbine by adjusting compressor inlet air temperature and IGV opening

Energy Analysis of A Retrofitted Regenerative Gas Turbine Organic Cycle in Ihovbor Power Plant

Gas turbines have gained popularity in power generation application because of its ease in operation, fuel flexibility and low emission of greenhouse gases. When in use as a simple gas turbine (SGT), it has the challenge of low thermal efficiency, which needs improvement to enhance its thermal efficiency and other thermal performances. This paper presents the energy analysis of incorporating a retrofitted combined regenerative gas turbine organic Rankine cycle (CRGTORC) to utilize the exhaust heat from the existing Ihovbor Power plant in Nigeria. The working fluid used in the Organic Rankine Cycle (ORC) section was cyclopentane and the analysis was carried out with the aid of ASPEN HYSYS and REFPROP. The performance of the proposed CRGTORC was compared with the existing SGT. The results obtained revealed that the CRGTORC model increases the net power output, thermal efficiency, overall cycle efficiency and work ratio of the system by 23.53%, 62.24%, 54.60%, and 10.21% respectively. Also, the flue gas losses, specific fuel consumption, and heat rate were reduced by 89.21%, 36.26%, and 36.26% respectively. Furthermore, it was observed that rise in compressor inlet air temperature lead to increase in specific fuel consumption and heat rate and decrease with net power out, thermal efficiency, cycle efficiency, flue gas losses, and work ratio. Thus, from the simulation results, the existing Ihovbor Power plant performance will be improved by integrating the CRGTORC system and its performance is significantly affected by the ambient inlet air temperature.

Thermo-Economic Assessment of a Gas Microturbine-Absorption Chiller Trigeneration System under Different Compressor Inlet Air Temperatures

This manuscript presents a thermo-economic analysis for a trigeneration system integrated by an absorption refrigeration chiller, a gas microturbine, and the heat recovery steam generation subsystem. The effect of the compressor inlet air temperature on the thermo-economic performance of the trigeneration system was studied and analyzed in detail based on a validated model. Then, we determined the critical operating conditions for which the trigeneration system presents the greatest exergy destruction, producing an increase in the costs associated with loss of exergy, relative costs, and operation and maintenance costs. The results also show that the combustion chamber of the gas microturbine is the component with the greatest exergy destruction (29.24%), followed by the generator of the absorption refrigeration chiller (26.25%). In addition, the compressor inlet air temperature increases from 305.15 K to 315.15 K, causing a decrease in the relative cost difference of the evaporator (21.63%). Likewise, the exergo-economic factor in the heat exchanger and generator presented an increase of 6.53% and 2.84%, respectively.

Thermo-Economic Optimization of a Cogeneration System Fueled by Syngas Produced from Gasification of Palm Biomass

This study presents the economic and the thematic optimization of a cogeneration system using syngas as fuel from palm biomass gasification. An energetic, exergetic, and thermo-economical model of each one of the components of the system is proposed to study the energetic and exergetic performance of the system. In addition, the unit costs of the products of the system are determined to calculate thermo-economic indicators, and thus to propose a multivariable optimization of the system in order to minimize the costs and to maximize the generated power. The results show that the most significant losses per destroyed exergy are found in the combustion chamber, reaching almost seventy percent of the total operating with Syngas, with higher destroyed exergy costs. The multi-objective optimization has allowed obtaining both the higher energy power and the generation cost. In addition, the compressor inlet air temperature increases, causing a decrease in the energy generated by the cogeneration system using syngas as fuel. It has been verified that when operating with syngas, there is a reduction in energy and exergy efficiency of the system.

Performance improvement of power plants using absorption cooling system

In the present paper, an integration of a (Lithium Bromide–Water) absorption inlet air cooling scheme to a cooled gas turbine-based combined cycle was analyzed. The waste heat energy of the exhaust gas prior to the exit of the waste heat recovery steam generator was chosen to power the cooling system. Nubaria Power Station, 120 km South East of Alexandria has been selected as a reference plant for the present study. It includes 3 generation modules, each including 2 * 250 MW gas turbine and 250 MW Steam turbine. A thermodynamic model of the overall integrated scheme of the cooling and power cycles is introduced. A parametric study of the effect of different operational conditions, namely; ambient temperature, relative humidity, compressor inlet air temperature, and part load on performance parameters was carried out. The model shows an increase of 11% in the produced electricity when the inlet air was cooled from 30 °C to 10 °C, Also, harvesting of condensed fresh water at a rate of 3.5 gm per kg of inlet air at ambient relative humidity of 60%. The model results have been verified by observing the real performance of the plant at various ambient conditions to ensure the accuracy of the model predictions.

Energy, Exergy, Economic, and Environmental analysis for various inlet air cooling methods on Shahid Hashemi-Nezhad gas turbines refinery

In this paper, the effects of various compressor inlet air cooling methods to increase the performance of Shahid Hashemi-Nezhad gas turbines refinery were investigated. These methods included media, fogging, and absorption chillers as common inlet air cooling methods and pressure drop station as novel cooling method. By using the exergy, environmental, and economic analysis, the best method for compressor inlet air cooling was selected. Based on the results, the absorption chiller system had the highest compressor inlet air temperature drop and increased the thermal and exergy efficiencies of cycle by about 2.5 and 3%, respectively, in hot season. Using absorption chiller, pressure drop station, fogging, and media had further reduction in CO2 and CO than simple gas turbine, respectively. Finally based on the net present value and internal rate of return coefficients, the pressure drop station method is the most economically feasible option.

Optimization of wet compression effect on the performance of V94.2 gas turbine

Wet compression has been widely used in recent years for power augmentation and gas turbine efficiency improvement. In order to explore this issue, the paper first focuses on the effects of wet compression, an analytical method based on droplet evaporation. Matching compressor-turbine or typically matching component has been added to this model for the compatibility of mass flow, rotational speed and power. Since this essay advances the idea of optimization, one of the metaheuristic algorithms Cuckoo Search (CS) has been considered. Three variables including droplet diameter, amount of overspray and droplet size have been taken into account. The objective function is turbine output work where compressor will work out of surge and choke domain. The numerical results indicate degradation in compressor inlet air temperature and noticeable power increments.

4E modeling and multi-criteria optimization of CCHPW gas turbine plant with inlet air cooling and steam injection

An integrated plant for production of combined cooling, heating, power and water (CCHPW) has been investigated here. The plant included a gas turbine (with steam injection in combustion chamber), an HRSG producing steam (with reheat and dual drum pressures) and absorption refrigeration system (for both space and inlet air cooling). Four E (Energy, Exergy, Environmental, and Economic) modeling and optimization of an integrated CCHPW plant was performed to evaluate the optimum values of nine design parameters. Multi-objective optimization of CCHPW plant using genetic algorithm method with exergy efficiency and total annual cost (TAC) of system as two objective functions was applied. Results showed that at the optimum design point, compressor inlet air temperature was 18.5 °C and steam injection into combustion chamber of gas turbine was 1.8%. The exergetic efficiency and TAC of integrated CCHPW plant at the selected optimum point was 30.7% and 28.545 million dollars, respectively. The payback period of about 4.38 years was estimated for the analyzed plant at the optimum design point. Finally, the sensitivity analysis of change in capital investment and fuel costs on the optimal values of design parameters was also performed and presented.

Performance enhancement of combined cycle power plant using inlet air cooling by exhaust heat operated ammonia-water absorption refrigeration system

Studies conducted on Brayton-Rankine combined cycle power plants have shown that the performance of its gas turbine unit and hence the overall performance of the plant can be improved by decreasing the compressor inlet air temperature. In these plants, a lot of low grade heat goes waste along with the exhaust gases. Absorption refrigeration systems always attract the users to utilize the low grade waste heat wherever it is available Therefore, in this work, a simulation model of an Indian combined cycle power plant coupled with exhaust heat operated ammonia-water absorption refrigeration system has been developed to investigate the performance of the combined system according to Indian atmospheric conditions which vary throughout the year. Energy and exergy analysis reveals that by having this arrangement, in summer season, an additional net power of 9440kW is developed thereby increasing the thermal efficiency of the plant by 1.193% and the exergy efficiency by 1.133%. But, in winter, it would further increase the power output by 400kW. As the North Indian atmospheric temperature varies from about 45°C in summer to about 3°C in winter, the variation of plant performance with the variation of ammonia condenser temperature has also been studied.

An applicable method for gas turbine efficiency improvement. Case study: Montazar Ghaem power plant, Iran

Compressor inlet air cooling is one of the most well-known methods to improve gas turbine power plant performance. In this study, pressure reduction valve in natural gas pressure reduction station is replaced by a turbo-expander to use the potential energy of the compressed gas. The turbo-expander shaft is connected to a mechanical chiller to produce refrigeration; the produced refrigeration is used to decrease the compressor inlet air temperature. Moreover, thermodynamic and exergetic analyses are carried out and the effect of compressor air cooling on the performance of the plant is studied. To do so, Montazer Ghaem power plant is considered as the case study. Results showed that using cooling system causes 3.2% temperature drop which leads to 1.138% increment in both thermal efficiency and net output power in the warmest month. Exergetic analysis reveals that using the cooling system leads to a higher exergy efficiency and hence lower exergy destruction. Also combustion chamber with 81.26 MW has the highest amount of exergy destruction which decreases to 77.36 MW after implementation of the cooling system. In January, exergetic efficiency of total plant has 1.86% enhancement and exergy destruction reduces about 3.8 MW.

Exergy analysis and parametric optimization of three power and fresh water cogeneration systems using refrigeration chillers

Three power and fresh water cogeneration systems that combine a GT (gas turbine) power plant and a RO (reverse osmosis) desalination system were compared based on the exergy viewpoint. In the first system, the GT and RO systems were coupled mechanically to form a base system. In the second and third systems, a VCR (vapor-compression refrigeration) cycle and a single-effect ACWater–LiBr (water/lithium bromide absorption chiller) were used, respectively, to cool the compressor inlet air and preheat the RO intake seawater via waste heat recovery in the VCR condenser and ACWater–LiBr absorber. A parametric analysis-based exergy was conducted to evaluate the effects of the key thermodynamic parameters including the compressor inlet air temperature and the fuel-mass flow rate on the system exergy efficiency. Parameter optimization was achieved using a GA (genetic algorithm) to reach the maximum exergy efficiency, where the thermodynamic improvement potentials of the systems were identified. The optimum values of performance for the three cogeneration systems were compared under the same conditions. The results showed that the cogeneration system with the AC is the best system among the three systems, since it can increase exergy and energy efficiencies as well as net power generation by 3.79%, 4.21%, and 38%, respectively, compared to the base system.

Gas turbine efficiency enhancement using waste heat powered absorption chillers in the oil and gas industry

In hot climates, the efficiency of energy-intensive industrial facilities utilizing gas turbines for power generation, such as oil refineries and natural gas processing plants (NGPPs), can be enhanced by reducing gas turbine compressor inlet air temperature. This is typically achieved using either evaporative media coolers or electrically-driven mechanical vapor-compression chillers. However, the performance of evaporative media coolers is constrained in high relative humidity (RH) conditions, such as encountered in the Middle East and tropical regions, and such coolers require demineralized water supply, while electrically-driven mechanical vapor-compression chillers consume a significant amount of electric power. In this study, the use of gas turbine exhaust gas waste-heat powered, single-effect water–lithium bromide (H2O–LiBr) absorption chillers is thermo-economically evaluated for gas turbine compressor inlet air cooling scheme, with particular applicability to Middle East NGPPs. The thermodynamic performance of the proposed scheme, integrated in a NGPP, is compared with that of conventional evaporative coolers and mechanical vapor-compression chillers, in terms of key operating parameters, and either demineralized water or electricity consumption, respectively. The results show that in extreme ambient conditions representative of summer in the Persian Gulf (i.e., 55 °C, 80% RH), three steam-fired, single-effect H2O–LiBr absorption chillers utilizing 17 MW of gas turbine exhaust heat, could provide 12.3 MW of cooling to cool compressor inlet air to 10 °C. In the same ambient conditions, evaporative coolers would only provide 2.3 MW cooling capacity, and necessitate consumption of approximately 0.8 kg/s of demineralized water to be vaporized. In addition, mechanical vapor-compression chillers would require an additional 2.7 MW of electric energy to provide the same amount of cooling as H2O–LiBr absorption chillers. The additional electricity generated through gas turbine compressor inlet air cooling using the waste heat powered absorption refrigeration scheme is of approximately 5264 MWh per year, compared to 1774 MWh for evaporative cooling. When integrated with other plant process cooling applications, the proposed scheme would not only permit to both meet gas turbine compressor inlet air cooling loads throughout the year, including peak summer loads, but also provide other process cooling during off-peaks time periods. The economic paypack period of the waste heat recovery scheme is estimated to range from 1.3 to 3.4 years for a three-chiller system based on present and project utility prices for NGPPs in the United Arab Emirates. This study suggests that waste heat absorption refrigeration is an attractive solution to enhance electrical power generation in Middle East NGPPs through gas turbine inlet air cooling, both in terms of thermodynamic and economic feasibility. This strategy would also reduce plant natural gas consumption for power generation, hence production costs and emissions.