Gas Turbine Outlet Research Articles

Performance analyses of basic cogeneration basic cogeneration plants in agriculture and food production

Energy in agriculture and in food production have vital importance that affect directly the cost and the quality of the products. Micro cogeneration plants are widely used in the World to produce heat and electricity at the same time in a same plant. The aim of this study, to analyze the performance of the production of power and heat for the food production process and the agricultural needs. For that reason, a basic cogeneration plant is taken to analyze the performance by using 1st and 2nd laws of thermodynamics and exergy analysis method. The electric-heat exergy rates, the energy and exergy efficiencies, the combustion chamber and the gas turbine outlet temperatures, the total electric and heat energies and exergies, and the specific works were calculated for various ambient temperatures and for various excess air rates of the basic cogeneration plants fueled with methane. The effects of the various ambient temperatures and the various excess air rates on the performance of the basic cogeneration plants were obtained, discussed and analyzed. For the best performance and for the best working conditions of the basic cogeneration plants in agriculture and food production process and food industry recommendations were done. It was found that, lower ambient temperatures give higher electric efficiency, but lower heat efficiency. However, an optimum excess air rates for the best performance was found at the value 2.3 of the excess air rates of the basic cogeneration plants fueled with methane.

Exergetic analyses of air-fuel preheated cogeneration plants in food production

Lower emissions and better performances in food production also affect the cost, the environmental effects, and the quality of the products of the agriculture and food industry. The aim of this study is to investigate and to analyze the exergetic performance of the production of heat exergy and power, to reuse waste heat and to give optimum reaction and to adapt to changing demands of the food production process and agriculture. Because of those reasons, an air fuel preheated (recuperative) cogeneration plant is taken to analyze the exergetic performance and working conditions by using exergy analysis and 1st and 2nd laws of thermodynamics. Energy and exergy efficiencies, combustion chamber and gas-turbine outlet temperatures, electric-heat exergy rates, specific works, and total electric and heat energies and exergies are calculated by taking various environmental temperatures and various excess air coefficient. Effects of the environmental temperatures and the excess air coefficient on the exergetic performance of the recuperative cogeneration plants were calculated, obtained, and discussed. For the best exergetic performance and working conditions, some recommendations were done for agriculture and for the food production process. In that study, it is found that, the recuperative cogeneration plants can obtain and give the best solutions and can adapt to changing demands of heat and electric rates. Also, it was found that, lower ambient temperatures give better electric efficiency, but lower heat exergy and electric rates. However, higher excess air coefficient increases the performance of the recuperative (air fuel preheated) cogeneration plants.

New insight into Allam cycle combined with coal gasification in supercritical water

In this work, we proposed and investigated the power generation system where coal gasification in supercritical water is combined with Allam cycle (CAllam cycle). This CAllam cycle features zero pollutant emission, easy CO2 collection and no extra heating. Our simulations demonstrated the differences between the natural gas Allam cycle and our proposed CAllam cycle, and also elucidated the mechanisms underlying these differences. Results show that recycling CO2 not only reduces the temperature of gas turbine blades but also further improves the system efficiency. Results also show that the gas turbine outlet pressure corresponding to the maximum efficiency is smaller and away from the gas-liquid line. Furthermore, we graphically identified the combination of CO2 recycling ratio and gas turbine outlet pressure, that the CAllam cycle allowed. Built on these findings, our proposed CAllam cycle was optimized graphically. Taking 40 wt% Hongliulin coal as an example, the maximum system efficiency is 53.19% and the corresponding CO2 recycling ratio and gas turbine outlet pressure are 1.158 and 2.43 MPa, respectively.

Exergy analysis of a negative CO[formula omitted] emission gas power plant based on water oxy-combustion of syngas from sewage sludge gasification and CCS

A power cycle with water-injected oxy-combustion (water cycle) is investigated by exergy analysis. It is fueled with syngas (aka. producer gas) from gasification of sewage sludge. The cycle is equipped with a spray-ejector condenser (SEC). CO2 is separated and compressed for transportation and storage. The net delivered electric power is 31% of the fuel exergy. The task efficiency is 39% when the flue gas bleed to gasification and O2 penalty are subtracted from fuel, and CO2 capture is included in the useful product. The large part of exergy destruction, 80%, pertains to the combustor. Increasing the temperature or the pressure of the combustor outlet (turbine inlet) lead, as expected, to reduced exergy destruction and more power delivery. Reducing pressure of the gas turbine outlet (SEC inlet) also increases power production. Varying pressure and temperature of the SEC outlet affects the distribution of exergy destruction among units of the condenser, however scarcely the overall efficiency. Reducing the ambient temperature, including cooling water temperature, reduces the efficiency of the plant, contrary to the effect of conventional plants. The reason is that the low pressure of SEC relies on the pressure and mass flow of injected water, rather than the temperature.

Thermodynamic sensitivity analysis of SOFC integrated with blade cooled gas turbine hybrid cycle

In the area of clean energy production along with higher efficiency, integrated combine power system, specifically gas turbine (GT) cycle with solid oxide fuel (SOFC) system, is gaining the attention of researchers. Thermodynamic modeling for the SOFC-GT hybrid cycle has been presented in this paper. For the proposed hybrid cycle, a high-temperature SOFC has successfully integrated with the recuperated-blade cooled gas turbine cycle. The gas turbine outlet waste heat has perfectly utilized the recuperator to power the fuel cell system. However, to maintain the temperature of the gas turbine blade within the permissible limit, air–film blade cooling scheme has been used. The SOFC-GT hybrid cycle has been operated under steady-state conditions, and a developed MATLAB program has been used to solve the governing equations for the components of the hybrid cycle. The impact of main operating parameters such as the temperature intake turbine (TIT), compression ratio (rpc), fuel utilization ratio (UF), and recirculation ratio are examined. From the obtained result, it can be revealed that the integration of the SOFC has seen significant improves overall hybrid cycle efficiency. The performance of fuel cell (SOFC) increases notably as the level of recuperation increases. To check the influence of main operating parameters, a sensitivity analysis has been performed for the hybrid cycle, and the maximum efficiency of 73% has been achieved. Moreover, to extend this research, an exclusive performance map has been plotted for power plant designers.

An integrated system for producing electricity and fresh water from a new gas-fired power plant and a concentrated solar power plant – Case study – (Australia, Spain, South Korea, Iran)

In this study, a novel power plant configuration consisting of a concentrated solar power (CSP) plant integrated into a Brayton cycle prior to the combustion chamber was examined. In addition, at the gas turbine outlet, the coupled steam Rankine cycle (SRC) and organic Rankine cycle (ORC) were incorporated to enhance efficiency and power generation. Currently, gas-fired power plants generally use a single Brayton cycle to generate power, resulting in significant energy loss. In this study, a thermoelectric generator was employed to mitigate such energy losses. Thermoelectric generators are currently used to generate additional power, despite their higher costs. To optimize the use of the proposed system, the heat of the second gas turbine was exploited to desalinate saltwater in a multi-effect distillation (MED) unit. The proposed system is appropriate for hot coastal climates. The Brayton cycle was validated based on observational data from a power plant on the Persian Gulf shores (the Khorramshahr gas-fired power plant). Climatic parameters have a significant effect on power generation cycles. This study explores the effects of irradiance, wind speed, and ambient temperature on the proposed system in four hot coastal regions. These results could be very useful for investors and local governments in such regions. Among the most important effective and practical parameters in this study, we should mention gas turbine efficiency, inlet temperature to the organic turbine, inlet pressure to the steam turbine, and inlet temperature to the gas turbine. The exergy analysis of the system showed that the most exergy destruction is related to the combustion chamber, heliostat, solar receiver, multi-effect desalination, gas turbine 1, and thermoelectric respectively. The total production power in this system was 190.7 megawatts and the exergy loss of the entire system was reported as 47.73-megawatt hours. The economic analysis of the system showed that compressor and gas turbine 1 respectively have the highest cost rate in the proposed system, and the cost rate of electricity produced by the proposed system was $2288 per hour.The results showed that the best performance of the system is obtained in the weather conditions of Busan, Melbourne, Barcelona, and Bandar Abbas respectively.

Acoustic Pyrometry Robustness to Time-of-Flight Estimation Errors

Abstract Acoustic pyrometry is a widely used technique for contactless temperature measurement. It may be used in several applications, especially when high temperatures and harsh environments are involved. For instance, it has been applied to measure the temperature distribution at gas turbine outlet. This technique is based on the measurement of the time of flight of an acoustic wave through a medium. If multiple emitter-receiver couples are used, using a computational procedure a reconstruction of a temperature map is possible. On the other hand, a full assessment of the robustness of this technique to potential errors in TOF estimation is still missing. In this study, the impact of an inaccuracy in TOF estimation on the reconstruction of a correct temperature map is investigated by means of a statistical approach. As a general result, it was found that when the TOF was measured without inaccuracies, temperature estimation errors may be lowered by simply increasing the number of cells in which the estimation is performed. However, when the estimation of the TOF is affected by errors, an optimal configuration exists that minimize the temperature estimation errors.

Simulation and optimization of a combined cycle power plant with low heating value fuel gas

Combined cycle power plant (CCPP) usually plays an important role in balancing byproduct gas generation and consumption in integrated iron and steel plant. The low heat value fuel gases, such as blast furnace gas (BFG) or mixed gas with Coke oven gas (COG) and BFG, are preferred to be used in high-efficient CCPP for power generation. In practice, the general heat value of mixed gas can be set in the range of 3500–4400[Formula: see text]kJ/Nm3. This paper presents a methodology to simulate operating parameters of CCPP with BFG. A generic model of gas turbine with open loop stage cooling employing air is used to simulate the performance of gas turbines cycle under different compressor pressure ratios and turbine inlet temperatures (TIT). The isentropic efficiencies for gas compressor and gas turbine are supposed to be constants and set corresponding to published industrial experience. The steam cycle is composed of classical double-pressure heat recovery steam generator (HRSG) and steam turbines according to gas turbine outlet temperature. Specific work, gas turbine cycle efficiency, cogeneration thermal efficiency and coolant air flow requirements are evaluated to find the optimal compressor pressure ratio and TIT. The research results are useful to select the optimum operating parameters of CCPP with BFG. Performance features were estimated with the help of compression ratios 12.5–20 and combustor exit temperature 1150–1350[Formula: see text]C.

Simulation of a new biomass integrated gasification combined cycle (BIGCC) power generation system using Aspen Plus: Performance analysis and energetic assessment

A new biomass integrated gasification combined cycle (BIGCC), which featured an innovative two-stage enriched air gasification system coupling a fluidized bed with a swirl-melting furnace, was proposed and built for clean and efficient biomass utilization. The performance of biomass gasification and power generation under various operating conditions was assessed using a comprehensive Aspen Plus model for system optimization. The model was validated by pilot-scale experimental data and gas turbine regulations, showing good agreement. Parameters including oxygen percentage of enriched air (OP), gasification temperature, excess air ratio and compressor pressure ratio were studied for BIGCC optimization. Results showed that increase OP could effectively improve syngas quality and two-stage gasification efficiency, enhancing the gas turbine inlet and outlet temperature. The maximum BIGCC fuel utilization efficiency could be obtained at OP of 40%. Increasing gasification temperature showed a negative effect on the two-stage gasification performance. For efficient BIGCC operation, the excess air ratio should be below 3.5 to maintain a designed gas turbine inlet temperature. Modest increase of compressor pressure ratio favored the power generation. Finally, the BIGCC energy analysis further proved the rationality of system design and sufficient utilization of biomass energy.

Exergy loss characteristics of a recuperated gas turbine and Kalina combined cycle system using different inlet guide vanes regulation approaches

This study proposes a novel two-step compressor inlet guide vanes (IGV) method to exploit performance enhancement potential for recuperated gas turbine and Kalina combined cycle (RGT-KCC). The off-design simulation model for RGT-KCC using compressor IGV regulation is constructed on the basis of energy and exergy analysis. The novel two-step IGV method is implemented by decreasing IGV opening to maintain gas turbine inlet temperature constant firstly and then maintain gas turbine outlet temperature (GTOT) at allowable maximum. The effects of novel two-step IGV and two conventional one-step IGV methods on RGT-KCC performance are compared in search for the superiority of novel method. The exergy loss distribution, component exergy efficiency, system exergy efficiency of RGT-KCC under different compressor IGV methods are evaluated with the change of RGT-KCC load. The results indicate that the novel two-step IGV method with the highest GTOT leads to the highest combustion chamber exergy efficiency and topping cycle exergy efficiency. Compared with the conventional one-step IGV methods, the novel method shows 1.37% more combined cycle exergy efficiency at most in RGT-KCC load range of 100–29.3%. As the RGT-KCC load decreases, the component exergy efficiencies of combustion chamber and KCS evaporator go up, while that of compressor and turbine drop. It is interesting to find that exergy loss proportion of combustion chamber drops obviously from 46.79% to 22.31% under novel method, while that of compressor, gas turbine and KCS increase. The novel two-step IGV method with high GTOT is the optimal method to enhance RGT-KCC part-load exergy efficiency in a wide load range.

Gas turbine outlets: test results

Object and purpose of research. The object of this work is gas turbine outlet consisting of axial-radial diffuser with the struts and the volute. The purpose is to create a methodology for engineering calculations, taking into account the mutual influence of the diffuser and the volute.
 Materials and methods. Experimental study of the flow in the models of outlets by measuring total and static pressure in characteristic sections. Calculation of integral and averaged flow parameters in measurement sections. Visualization of boundary flows. Based on the experimental results, development of regression models for the correction factors to be applied in the theoretical model, with selection of relevant factors.
 Main results. An experimental study of 23 variants of models with a total volume of 112 experimental points (modes) was carried out. On the basis of the experiment, methodology and program for engineering calculation of total pressure losses in the outlets were developed. It was found that the installation of guide blades and radial ribs in the diffuser in order to reduce local expansion angles with the ultimate purpose of mitigating total pressure losses actually does not lead to this result due to the because the flow in the diffuser becomes asymmetric due to its interaction with the volute. Visualization of boundary flows in the diffusers and the volutes has been performed, which makes it possible to identify the locations of separations causing increased pressure losses.
 Conclusion. An engineering method for calculating the total pressure loss in gas turbine outlet has been developed.
 The technique makes it possible, taking size restrictions into account, to select the geometry of the flow section that ensures
 minimum total pressure loss.

4E analyses of an innovative polygeneration system based on SOFC

An innovative multigeneration plant driven by a solid oxide fuel cell unit is regarded in this meticulous examination. The plausibility of the expressed plant is substantiated with regarding economic, thermodynamic and environmental concepts as the utmost efficacious equipment for operating evaluation of the thermal systems. An ejector refrigeration system beside a PEM electrolyzer are employed for cooling and hydrogen production. Furthermore, a heat recovery heat exchanger is employed for heating purposes. All subsystems are cautiously investigated and validated considering the reliable reports. The findings portrayed that the introduced multigeneration system can generate cooling load, heating capacity, net output power, and H21 rate of 84.421kW, 2771kW, 184.21kW, and 1.4331kg/h, respectively. In this occasion, the first-law efficiency, exergetic efficiency, product overall cost, and environmental penalty cost are calculated 79.57%, 33.92%, 897.7$/GJ, and 0.3527$/h, respectively. Also, among all constituents, the superior portion of exergy destruction attributed to the solid oxide fuel cell module by 783.31kW, approximately 35.6% of the overall exergy destruction rate. Meantime, a thoroughgoing parametric evaluation of the set-up is established and it is illustrated that the suggested multigeneration plant’s exergetic efficiency can be maximized according to the inlet temperature of the solid oxide fuel cell unit, compression ratio, and solid oxide fuel cell current density. Moreover, the product cost rate of the plant can be minimized with ejector motive fluid pressure, solid oxide fuel cell inlet temperature, and gas turbine outlet pressure.

Thermodynamic analysis of turboexpander and gas turbine hybrid system for gas pressure reduction station of a power plant

In this study, the feasibility of using a turboexpander instead of an expanding valve in a natural gas pressure reduction station was investigated. The aim of the study is to retrieve the energy of gas pressure reduction station of a power plant gas turbine cycle in order to set a refrigeration cycle and cooling the inlet air of gas turbine compressor in a hybrid system of turboexpander, gas turbine and compression refrigeration cycle. The thermal energy of the gas turbine outlet was also used for preheating of the turboexpander inlet gas. The station meteorology data, gas consumption rate and inlet pressure of considered station were extracted from May to September 2018. The results have demonstrated the capacity of the proposed system for the production of cooling power and the system efficiency augmentation in the warm months. Besides, using the wasted thermal power of gas turbine outlet gas and turboexpander has helped to recover energy and preventing energy loss. The results were illustrated for the turboexpander preheating power saving with more than 1200 kW, the turboexpander produced mechanical power more than 950 kW, electrical efficiency and cooling produced power between 2700 and 5300 kW for the warm months of the year.

Investigation of a combined cycle power plant coupled with a parabolic trough solar field and high temperature energy storage system

This study was aimed at exergetically investigating a combined cycle power plant coupled with a parabolic trough solar field and high temperature energy storage system. Thermodynamic modeling of the combined cycle was conducted by ASPEN HYSYS simulation software, while the modeling of solar and energy storage section was carried out using MATLAB software. The main goal of the present research work was to reveal the reasons and sources of the thermodynamic losses occurring in the power plant based on the thermodynamic outcomes obtained from modeling. After writing the exergy balance equations for all the subunits of the power plant, their exergetic performance parameters were measured individually. Moreover, the effect of different influential parameters such as gas turbine inlet temperature and outlet pressure, and the R113 working fluid mass flow rate on the exergy and electrical efficiencies of the whole system was also investigated and scrutinized. The exergetic value of the net electric power was found to be 93,580 kW. The overall exergy destruction of the system stood at 216,710 kW. The contribution of solar and energy storage combination, as the main subunit wasting exergy, to the overall exergy destruction of the system was determined at 43%. Moreover, combustion chamber subunit stood in the next rank in terms of exergy destruction, contributing 15.7% of the overall exergy destruction of the power plant. The overall exergy efficiency and electrical efficiency of the power cycle was determined at 38.2% and 47%, respectively.

Comparative Analysis of Thermodynamic Cycles of Selected Nuclear Ship Power Plants With High-Temperature Helium-Cooled Nuclear Reactor

Abstract This paper presents a comparative analysis of thermodynamic cycles of two ship power plant systems with a high-temperature helium-cooled nuclear reactor. The first of them is a gas system with recuperator, in which classical gas chamber is substituted for a HTGR reactor (High Temperature Gas-cooled Reactor). The second of the considered cycles is a combined gas-steam system where working medium flux from gas turbine outlet is directed into waste heat boiler and its heat is utilized for production of superheated steam to drive steam turbine. Preliminary calculations of the combine cycles showed that it is necessary to expand the system by adding to its steam part an inter-stage overheat for secondary steam, owing to that a required degree of steam dryness at outlet from the turbine can be reached, ensuring its correct operational conditions. The analyzed power systems were compared to each other with regard to efficiency of their thermodynamic cycles. Also, efficiency of particular cycles were subjected to optimization in respect to such parameters as : working gas temperature at outlet from reactor in gas system as well as steam pressure at outlet from waste heat boiler and partition pressure in steam part of combined system. Advantages of nuclear power plants compared with the classical power systems dominating currently in sea transport were also discussed.

Gas turbine power calculation method of turboshaft based on simulation and performance model

Gas turbine power of turboshaft engine cannot be measured, a total of five typical steady state point test data from the ground slow state to the maximum state were selected according to the factory acceptance test drive of a certain type of carrier-based helicopter turboshaft engine. Combustion chamber three-dimensional simulation model was established to carry on simulation analysis of different typical steady state combustion process. The simulated combustion chamber exit section parameters are input into the established gas turbine isentropic adiabatic aerodynamic calculation model to obtain the gas turbine power and outlet temperature. Select five typical steady state points of five sets of turboshaft engines on the same type to repeat the above calculation process, and compare the calculated value of gas turbine outlet temperature with the acceptance test values, it is found that the error values are all within 5%, and the effectiveness and accuracy of the gas turbine power calculation method are verified.

EFFECTS OF DUCT BURNER ON BOTTOMING CYCLE IN A COMBINED CYCLE POWER PLANT

In this study, thermodynamic modeling and exergoeconomic assessment of a Combined Cycle Power Plant (CCPP) with a Duct Burner (DB) was performed. Obtaining an optimum condition for the performance of a CCPP, using a DB after gas turbine was investigated by various researchers. DB is installed between gas turbine cycle and Rankine cycle of a CCPP to connect the gas turbine outlet to the Heat Recovery Steam Generator (HRSG) in order to produce steam for bottoming cycle. To find the irreversibility effect in each component of the bottoming cycle, a comprehensive parametric study is performed. In this regard, the effect of DB fuel flow rate on cost efficiency and economic of the bottoming cycle are investigated. To obtain a reasonable result, all the design parameters are kept constant while the DB fuel flow rate is varied. The results indicate that by increasing DB fuel flow rate, the investment cost and the efficiency of CCPP are increased. T-S diagram reveals that by using a DB, higher pressures steam in heat recovery steam generator has higher temperature while the low pressure is decreased. In addition, the exergy of flow gases in heat recovery steam generator increases. So, the exergy efficiency of the whole cycle was increased to around 6 percent, while the cost of the plant reduced by one percent.

Thermal performance of gas turbine power plant based on exergy analysis

This study is about energy and exergy analysis of gas turbine power plant. Energy analysis is more quantitatively while exergy analysis is about the same but with the addition of qualitatively. The lack quality of the thermodynamic process in the system leads to waste of potential energy, also known as exergy destruction which affects the efficiency of the power plant. By using the first and second law of thermodynamics, the model for the gas turbine power plant is built. Each component in the thermal system which is an air compressor, combustion chamber and gas turbine play roles in affecting the efficiency of the gas turbine power plant. The exergy flow rate for the compressor (AC), the combustion chamber (CC) and the gas turbine (GT) inlet and outlet are calculated based on the physical exergy and chemical exergy. The exergy destruction calculation based on the difference between the exergy flow in and exergy flow out of the component. The combustion chamber has the highest exergy destruction. The air compressor has 94.9% and 92% of exergy and energy efficiency respectively. The combustion chamber has 67.5% and 61.8% of exergy and energy efficiency respectively while gas turbine has 92% and 82% of exergy and energy efficiency respectively. For the overall efficiency, the plant has 32.4% and 34.3% exergy and energy efficiency respectively. To enhance the efficiency, the intake air temperature should be reduced, modify the combustion chamber to have the better air-fuel ratio and increase the capability of the gas turbine to receive high inlet temperature.

Thermo-economic optimization of heat recovery steam generator for a range of gas turbine exhaust temperatures

This paper illustrates the effect of selling price on the optimum design parameters of a heat recovery steam generator (HRSG) and the selection of its ideal configuration for an outlet temperature range of 350–650°C. The Particle Swarm Optimization (PSO) method was used, considering the steam cycle specific work as an objective to be maximized, the net present value as another objective to be maximized for the economic optimization and a combination of both. Three configurations of heat recovery steam generators are considered with one, two and three pressure levels and a reheat. The results show that, the three pressure level system is the best configuration from a thermodynamic point of view, but with respect to the economical aspect the two pressure levels is the best configuration for the low and medium selling prices (0.04$/kWh, 0.08$/kWh and 0.2$/kWh), whereas the three pressure level configuration would only be interesting for a high selling price of 0.3$/kWh and a temperature range 450–600°C. For a temperature of 650°C, the high cost of the three level system leads to a decrease in the net present value. As the selling price increases the optimized design parameters of the three pressure level HRSG based on economic or thermodynamic optimization are similar. The obtained results are used to elaborate a new correlation relating the net present value with the gas turbine outlet temperature, gas mass flow rate, number of levels of HRSG and selling price.

Energetic approach of biomass hydrolysis in supercritical water

Cellulose hydrolysis can be performed in supercritical water with a high selectivity of soluble sugars. The process produces high-pressure steam that can be integrated, from an energy point of view, with the whole biomass treating process. This work investigates the integration of biomass hydrolysis reactors with commercial combined heat and power (CHP) schemes, with special attention to reactor outlet streams. The innovation developed in this work allows adequate energy integration possibilities for heating and compression by using high temperature of the flue gases and direct shaft work from the turbine. The integration of biomass hydrolysis with a CHP process allows the selective conversion of biomass into sugars with low heat requirements. Integrating these two processes, the CHP scheme yield is enhanced around 10% by injecting water in the gas turbine. Furthermore, the hydrolysis reactor can be held at 400°C and 23MPa using only the gas turbine outlet streams.