Thermal and Economic Analysis of Gas Turbine Steam Injection Plant

Author(s):  
Sepehr Sanaye ◽  
Vahid Mahdikhani ◽  
Ziaeddin Khajeh Karimeddini ◽  
Gholamreza Sadri

Steam injection into gas turbine combustion chamber increases the power output and lowers the NOx emissions. Steam may be produced in a heat recovery steam generator (HRSG), using gas turbine exhaust gases. Steam which is usually injected with pressure of combustion chamber, increases the mass flow rate flowing through turbine and decreases the combustion temperature, hence, lowering the amount of NOx emissions. This power augmentation method is usually used for gas turbines with power outputs in range of 2–50 MW with one pressure level in HRSG. In this paper the optimum design parameters of the above mentioned system is obtained for the above range of gas turbine power output. For doing this task an objective function is introduced which contains the economic and thermal characteristics of the system. This objective function is minimized when gas turbine exhaust temperature, compressor pressure ratio, isentropic efficiency of compressor and turbine, fuel mass flow rate (natural gas), inlet air mass flow rate, and the amount of injected steam mass flow rate vary.

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1105 ◽  
Author(s):  
Carlo Carcasci ◽  
Lapo Cheli ◽  
Pietro Lubello ◽  
Lorenzo Winchler

This paper presents an off-design analysis of a gas turbine Organic Rankine Cycle (ORC) combined cycle. Combustion turbine performances are significantly affected by fluctuations in ambient conditions, leading to relevant variations in the exhaust gases’ mass flow rate and temperature. The effects of the variation of ambient air temperature have been considered in the simulation of the topper cycle and of the condenser in the bottomer one. Analyses have been performed for different working fluids (toluene, benzene and cyclopentane) and control systems have been introduced on critical parameters, such as oil temperature and air mass flow rate at the condenser fan. Results have highlighted similar power outputs for cycles based on benzene and toluene, while differences as high as 34% have been found for cyclopentane. The power output trend with ambient temperature has been found to be influenced by slope discontinuities in gas turbine exhaust mass flow rate and temperature and by the upper limit imposed on the air mass flow rate at the condenser as well, suggesting the importance of a correct sizing of the component in the design phase. Overall, benzene-based cycle power output has been found to vary between 4518 kW and 3346 kW in the ambient air temperature range considered.


Author(s):  
Mohsen Ghazikhani ◽  
Nima Manshoori ◽  
Davood Tafazoli

An industrial gas turbine has the characteristic that turbine output decreases on hot summer days when electricity demand peaks. For GE-F5 gas turbines of Mashad Power Plant when ambient temperature increases 1° C, compressor outlet temperature increases 1.13° C and turbine exhaust temperature increases 2.5° C. Also air mass flow rate decreases about 0.6 kg/sec when ambient temperature increases 1° C, so it is revealed that variations are more due to decreasing in the efficiency of compressor and less due to reduction in mass flow rate of air as ambient temperature increases in constant power output. The cycle efficiency of these GE-F5 gas turbines reduces 3 percent with increasing 50° C of ambient temperature, also the fuel consumption increases as ambient temperature increases for constant turbine work. These are also because of reducing in the compressor efficiency in high temperature ambient. Steam injection in gas turbines is a way to prevent a loss in performance of gas turbines caused by high ambient temperature and has been used for many years. VODOLEY system is a steam injection system, which is known as a self-sufficient one in steam production. The amount of water vapor in combustion products will become regenerated in a contact condenser and after passing through a heat recovery boiler is injected in the transition piece after combustion chamber. In this paper the influence of steam injection in Mashad Power Plant GE-F5 gas turbine parameters, applying VODOLEY system, is being observed. Results show that in this turbine, the turbine inlet temperature (T3) decreases in a range of 5 percent to 11 percent depending on ambient temperature, so the operating parameters in a gas turbine cycle equipped with VODOLEY system in 40° C of ambient temperature is the same as simple gas turbine cycle in 10° C of ambient temperature. Results show that the thermal efficiency increases up to 10 percent, but Back-Work ratio increases in a range of 15 percent to 30 percent. Also results show that although VODOLEY system has water treatment cost but by using this system the running cost will reduce up to 27 percent.


Author(s):  
J. P. Yadav ◽  
Bharat Raj Singh ◽  
Onkar Singh

Although gas turbines are known as constant volume machines, but its performance considerably depends upon the ambient air temperature and mass flow rate. During summer season the density of the air decreases which affects the mass flow rate and ultimately the power output of a gas turbine is reduced. In order to overcome this situation several techniques are already in the practice and one of the most effective and economical is adopting the inlet fog cooling, and this technique basically enhances the power output of the machine. The cooling of ambient air by fog cooling up to wet bulb temperature increases the mass flow rate on account of increase in air density, as a result it ultimately increases the power output of a gas turbine. Fogging is applied with consideration of relative humidity of ambient air not only during summer season but also during dry days of summer season in order to increase the power output of gas turbine. This paper describes the effect on percentage enhancement of power out adopting various fuel options with low and high humidity ambient conditions. The result indicates the potential increase in the power output up to 14%. It is also observed that the total cost of power production increases due to increase in fuel consumption on account of enhanced power output. Thus the best suitable selling cost of power should be selected to compensate the increased investment on fuel cost.


Author(s):  
Massimiliano Renzi ◽  
Carlo Caligiuri ◽  
Mosè Rossi

In this work, the performances of a 100 kW Micro Gas Turbine (MGT) fed by Natural Gas (NG) and three different biomass-derived Synthesis Gases (SGs) have been assessed using a MATLAB® simulation algorithm. The set of equations in the algorithm includes the thermodynamic transformations of the working fluid in each component, the performance maps that describe the turbomachines’ isentropic efficiencies and pressure ratios as a function of the reduced mass flow rate and the reduced rotational speed, the performance and the pressure losses in each component, as well as the consumption of the other auxiliary devices. The electric power output, achieved using SGs, turns out to be lower or higher with respect to the one produced with the NG, depending on the fuel Lower Heating Value (LHV) but also largely on the variation of the working fluid composition. In this work, the effect of the steam injection on the MGT performance characteristics has been also investigated. Steam injection allows to obtain higher power and efficiencies using both NG and SGs at the rated rotational speed, mainly thanks to the increase of the turbine enthalpy drop and the reduction of the compressor consumption. Attention must be paid to the risk of the compressor stall, especially when using SGs, as the mass flow rate processed by the compressor decreases significantly. Moreover, another advantage of adopting the steam injection technique lies in the increased flexibility of the system: according to the users’ needs, the discharged heat can be exploited to generate steam, thus to enhance the electric performances, or to supply thermal power.


Author(s):  
Mohamad Modrek ◽  
Ali Al-Alili

Photovoltaic thermal collectors (PVT) combines technologies of photovoltaic panels and solar thermal collectors into a hybrid system by attaching an absorber to the back surface of a PV panel. PVT collectors have gained a lot of attention recently due to the high energy output per unit area compared to a standalone system of PV panels and solar thermal collectors. In this study, performance of a liquid cooled flat PVT collector under the climatic conditions of Abu Dhabi, United Arab Emirates was experimentally investigated. The electrical performances of the PVT collector was compared to that of a standalone PV panel. Moreover, effect of sand accumulation on performance of PVT collectors was examined. Additionally, effect of mass flow rate on thermal and electrical output of PVT collector was studied. Electrical power output is slightly affected by changes in mass flow rate. However, thermal energy increased by 22% with increasing flow rate. Electrical power output of a PV panel was found to be 38% lower compared to electrical output of PVT collectors. Dust accumulation on PVT surface reduced electrical power output up to 7% compared with a reference PVT collector.


2019 ◽  
Vol 82 ◽  
pp. 01007
Author(s):  
Katarzyna Kaczyńska ◽  
Konrad Kaczyński ◽  
Piotr Pełka

In the herein paper, research on the mass loss of biomass pellets is presented. The research was carried out on a specially constructed test stand. In the research three types of pellet fuels were used, which were made of oak sawdust, sunflower husk and straw. The research was carried out at three different temperatures of the combustion chamber: 850°C, 750°C and 650°C. The research was carried out without inert material and mass rate flow Gs=2,5kg/m2s and Gs=5kg/m2s. Quartz sand was the inert material. It was expected that an increase in the temperature prevailing in the combustion chamber would accelerate the process of mass loss of the biomass pellet combustion. However, the results of the experiment indicated that this is not the case in every analyzed case. The mass flow rate of inert material intensifies the combustion process and accelerates the biomass pellets made of oak sawdust mass loss, but increasing the temperature in the combustion chamber accelerates the process of biomass pellets mass loss more than the mass flow rate of inert material. Based on the experimental tests carried out, it was found that biomass can be combusted in circulating fluidized bed boilers, albeit due to the diversified chemical composition of the biomass (alkali content), the boiler should be operated in such a way as to prevent the softening and melting temperature of the ash being exceeded.


2019 ◽  
Vol 16 (3) ◽  
pp. 368-376
Author(s):  
Dipak Sudam Patil ◽  
Rachayya R. Arakerimath ◽  
Pramod V. Walke

Purpose This paper aims to present an experimental investigation and optimization of a low-temperature thermoelectric module to examine the influence of the main operating conditions. Design/methodology/approach In this work, a comparison was made by varying the various operating parameters such as heat source temperature, the flow rate of the cold fluid and the external load resistance. A Taguchi method was applied to optimize the parameters of the system. Three factors, including the external load resistance, mass flow rate of water (at the heat sink side) and heater temperature (at the heat source side) along with different levels were taken into account. Analysis of variance was used to determine the significance and percentage contribution of each parameter. Findings The experimental results show that the maximum power output 8.22W and the maximum conversion efficiency 1.11 per cent were obtained at the heater temperature of 240°C, the cold fluid mass flow rate of 0.017 kg/s, module temperature difference of 45°C and the load resistance of 5 O. It was observed that the optimum parameter levels for maximum power output determined as 5 O external load resistance, 0.17 kg/s mass flow rate of water and 240°C heater temperature (A1B3C3). It reflects that these parameters influence on the optimum conditions. The heater temperature is the most significant parameter on the power output of the thermoelectric module. Originality/value It is clear from the confirmation test that experimental values and the predicted values are in good agreement.


Author(s):  
Chihiro Myoren ◽  
Yasuo Takahashi ◽  
Manabu Yagi ◽  
Takanori Shibata ◽  
Tadaharu Kishibe

An axial compressor was developed for an industrial gas turbine equipped with a water atomization cooling (WAC) system, which is a kind of inlet fogging technique with overspray. The compressor performance was evaluated using a 40MW-class test facility for the advanced humid air turbine system. A prediction method to estimate the effect of WAC was developed for the design of the compressor. The method was based on a streamline curvature (SLC) method implementing a droplet evaporation model. Four test runs with WAC have been conducted since February 2012. The maximum water mass flow rate was 1.2% of the inlet mass flow rate at the 4th test run, while the design value was 2.0%. The results showed that the WAC decreased the inlet and outlet temperatures compared with the DRY (no fogging) case. These decreases changed the matching point of the gas turbine, and increased the mass flow rate and the pressure ratio by 1.8% and 1.1%, respectively. Since prediction results agreed with the results of the test run qualitatively, the compressor performance improvement by WAC was confirmed both experimentally and analytically. The test run with the design water mass flow rate is going to be conducted in the near future.


Author(s):  
B. Facchini ◽  
M. Surace ◽  
S. Zecchi

Significant improvements in gas turbine cooling technology are becoming harder as progress goes over and over. Several impingement cooling solutions have been extensively studied in past literature. An accurate and extensive numerical 1D simulation on a new concept of sequential impingement was performed, showing good results. Instead of having a single impingement plate, we used several perforated plates, connecting the inlet of each one with the outlet of the previous one. Main advantages are: absence of the negative interaction between transverse flow and last rows impinging jets (reduced deflection); better distribution of pressure losses and heat transfer coefficients among the different plates, especially when pressure drops are significant and available coolant mass flow rate is low (lean premixed combustion chamber and LP turbine stages). Practical applications can have a positive influence on both cooled nozzles and combustion chambers, in terms of increased cooling efficiency and coolant mass flow rate reduction. Calculated effects are used to analyze main influences of such a cooling system on global performances of power plants.


Author(s):  
Ryo Kubo ◽  
Fumio Otomo ◽  
Yoshitaka Fukuyama ◽  
Yuhji Nakata

A CFD investigation was conducted on the total pressure loss variation for a linear nozzle guide vane cascade of a gas turbine, due to the individual film injections from the leading edge shower head, the suction surface, the pressure surface and the trailing edge slot. The results were compared with those of low speed wind tunnel experiments. A 2-D Navier-Stokes procedure for a 2-D slot injection, which approximated a row of discrete film holes, was performed to clarify the applicable limitation in the pressure loss prediction during an aerodynamic design stage, instead of a costly 3-D procedure for the row of discrete holes. In mass flow rate ratios of injection to main flow from 0% to 1%, the losses computed by the 2-D procedure agreed well with the experimental losses except for the pressure side injection cases. However, as the mass flow rate ratio was increased to 2.5%, the agreement became insufficient. The same tendency was observed in additional 3-D computations more closely modeling the injection hole shapes. The summations of both experimental and computed loss increases due to individual row injections were compared with both experimental and computed loss increases due to all-row injection with the mass flow rate ratio ranging from 0% to 7%. Each summation agreed well with each all-row injection result. Agreement between experimental and calculated results was acceptable. Therefore, the loss due to all-row injections in the design stage can be obtained by the correlations of 2-D calculated losses from individual row injections. To improve more precisely the summation prediction for the losses due to the present all-row injections, extensive research on the prediction for the losses due to the pressure side injection should be carried out.


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