Numerical Analysis of a Fogging System in a Gas Turbine

Author(s):  
Freddy Jeanty ◽  
Jesús De Andrade ◽  
Sergio Croquer ◽  
Jorge Luis Clarembaux Correa ◽  
Miguel Asuaje

Air cooling via evaporation of water droplets injected at the compressor intake duct is the process known as Fogging System, which is among the most used technologies for increasing output power of gas turbines nowadays. The optimal design of this system must consider numerous variables, such as: air temperature (Ta), air relative humidity (RH), duct geometry, amount of water injected (mw), droplets size (Dd), and nozzles location. Since there are so many variables the flow under study is very complicated. In consequence the analytical determination of an optimal Fogging System design is not feasible. In this paper, a numerical model was developed in order to characterize the injection of water at the air intake duct of a Gas Turbine. First, the expressions characterizing the model were included in the CFD software ANSYS CFX v-11 and simulated in a simple geometry (rectangular duct). Validation of CFD results was carried out by comparison with experimental data. Good agreement between numerical results of a control case and experimental data was achieved (deviation < 2%). Then, the influence of key parameters such as: Ta, RH, Dd, mw over the performance of the air cooling system was investigated. Finally, the model was used to design a Fogging System for an existing 120 MW Gas Turbine. For this gas turbine operating under real conditions, the model predicts a net power increment of 2% [7].

Author(s):  
E. Kakaras ◽  
A. Doukelis ◽  
J. Scharfe

The operation of gas turbines at ambient air temperatures higher than the ISO standard conditions (15°C) causes performance penalties both in the generated power and the efficiency of the engine. At high inlet-air temperatures, there can be a power loss of more than 20% combined with a significant increase in specific fuel consumption, compared to the ISO standard conditions. Thus, over a long period of time, gas turbines have a lower power output and efficiency than the equipment could actually perform. It is the purpose of this work to present the possibilities and advantages from the integration of an innovative air-cooling system for reducing the gas turbine intake-air temperature. The advantages of this system are demonstrated by examining alternative scenarios of usage, representative of different countries and different climatic conditions.


Author(s):  
Hemant Gajjar

Inlet Air Cooling of gas turbine engines for power augmentation has seen increasing application over the past decade. Evaporative inlet air cooling has been particularly preferred by the Gas Turbine operators due to its low cost and ease of installation. Two of the important considerations for a GT operator are the proper selection of the EIAC and, after installation, its proper testing to assure required performance. This paper is based on the experience, as a user, of selecting a inlet air cooling system and then implementing a Fogging type Evaporative Cooling system. It highlights the important parameters related to evaporative cooling system and in particular fogging, and how the site testing can be handled to ensure proper performance. Concepts of ‘Conversion Effectiveness’ and ‘Evaporation Effectiveness’ have also been introduced in this paper.


Volume 1 ◽  
2004 ◽  
Author(s):  
Mohammad Ameri ◽  
Hamid Nabati ◽  
Alireza Keshtgar

Gas turbines are almost constant volume machines at a specific rotating speed, i.e., air intake is limited to a nearly fixed volume of air regardless of ambient air conditions. As air temperature rises, its density falls. Thus, although the volumetric flow rate remains constant, the mass flow rate is reduced as air temperature rises. Power output is also reduced as air temperature rises because power output is proportional to mass flow rate. This power output reduction is from 0.5% to 0.9% of the ISO output power for every 1°C rise in the ambient temperature. The solution of this problem is very important because the peak demand season also happens in the summer. One of the useful methods to overcome this problem is to apply the fog inlet air cooling system for the gas turbines. In this paper the Rey Power Plant site climate conditions in the summer have been studied. The design conditions regarding the dry bulb temperature and relative humidity have been selected. The different inlet air cooling systems have been studied and the Fog system has been chosen. The economical study has shown that this system is very cheap in comparison with the installation of the new gas turbines. The capital cost is estimated to be 40 $/KW. The pay back period is around 1.5 year. The testing of this system has shown that the average power capacity of the power plant is increased by 19 MW and prevented the installation of a new gas turbine.


Author(s):  
Maurizio De Lucia ◽  
Rinaldo Bronconi ◽  
Ennio Carnevale

Gas turbine air cooling systems serve to raise performance to peak power levels during the hot months when high atmospheric temperatures cause reductions in net power output. This work describes the technical and economic advantages of providing a compressor inlet air cooling system to increase the gas turbine’s power rating and reduce its heat rate. The pros and cons of state-of-the-art cooling technologies, i.e., absorption and compression refrigeration, with and without thermal energy storage, were examined in order to select the most suitable cooling solution. Heavy-duty gas turbine cogeneration systems with and without absorption units were modeled, as well as various industrial sectors, i.e., paper and pulp, pharmaceuticals, food processing, textiles, tanning, and building materials. The ambient temperature variations were modeled so the effects of climate could be accounted for in the simulation. The results validated the advantages of gas turbine cogeneration with absorption air cooling as compared to other systems without air cooling.


Author(s):  
Paul Shaw ◽  
Farshid Zabihian ◽  
Alan S. Fung

This paper presents results of the combined cycle power plant (CCPP) modeling when the ambient temperature is varying. The model of the CCPP was developed using a gas turbine and a heat recovery steam generator (HRSG) models that had been already developed and validated. The model of the components was developed based on an actual existing power plant and then the operational data of the power plant was used to validate the model. The results of running the model for various ambient temperatures demonstrated that the performance of the gas turbine part of the cycle was heavily affected by the changes in the ambient temperature, particularly the output power of the gas turbines. However, the performance of the steam cycle was almost untouched by the changes of ambient temperature. This suggests that operation of the CCPP is more stable than stand-alone gas turbine in hot summer days especially if the cycle is not equipped with an inlet air cooling system.


1994 ◽  
Vol 116 (2) ◽  
pp. 360-365 ◽  
Author(s):  
M. De Lucia ◽  
R. Bronconi ◽  
E. Carnevale

Gas turbine air cooling systems serve to raise performance to peak power levels during the hot months when high atmospheric temperatures cause reductions in net power output. This work describes the technical and economic advantages of providing a compressor inlet air cooling system to increase the gas turbine’s power rating and reduce its heat rate. The pros and cons of state-of-the-art cooling technologies, i.e., absorption and compression refrigeration, with and without thermal energy storage, were examined in order to select the most suitable cooling solution. Heavy-duty gas turbine cogeneration systems with and without absorption units were modeled, as well as various industrial sectors, i.e., paper and pulp, pharmaceuticals, food processing, textiles, tanning, and building materials. The ambient temperature variations were modeled so the effects of climate could be accounted for in the simulation. The results validated the advantages of gas turbine cogeneration with absorption air cooling as compared to other systems without air cooling.


Author(s):  
John Confurius

The profits that can be gained by use of inlet air cooling on gas turbines has been recognised for quite some time now and the systems installed throughout the world have shown the users in the gas turbine field that cooling indeed can be used to boost power at times when the ambient temperature reaches or exceeds the ISO rating temperature of the gas turbine. Drawback however being that the initial investment asked of the gas turbine user is rather large thus only justifying a cooling system in regions where the outdoor temperatures exceed the ISO rating time and again due to the climate in that region. Lately gas turbine users in colder climates have become interested in power augmentation during their short summer, however there is no justification for an investment like necessary when installing one of the presently available systems on the market. As the question reached us from more and more of our clients it stimulated us to go out and search for a low-investment solution to this problem. This resulted in the world’s first low pressure gas turbine inlet cooling system.


2018 ◽  
Vol 225 ◽  
pp. 01020
Author(s):  
Thamir K. Ibrahim ◽  
Mohammed K. Mohammed ◽  
Omar I. Awad ◽  
Rizalman Mamat ◽  
M. Kh Abdolbaqi

A basic goal of operation management is to successfully complete the life cycle of power systems, with optimum output against minimal input. This document intends calculating both, the performance and the life cycle cost of a gas turbine fitted with an inlet air cooling mechanism. Correspondingly, both a thermodynamic and an economic model are drawn up, to present options towards computing the cooling loads and the life cycle costs. The primary observations indicate that around 120MWh of power is derived from gas turbine power plants incorporating the cooling mechanism, compared to 96.6 MWh for units without the mechanism, while the life cycle cost is lower for units incorporating the cooling process. This indicates benefits in having the mechanism incorporated in the architecture of a gas turbine.


Author(s):  
Carlo M. Bartolini ◽  
Danilo Salvi

The steam generated through the use of waste heat recovered from a steam injection gas turbine generally exceeds the maximum mass of steam which can be injected into steam injection gas turbine. The ratio between the steam and air flowing into the engine is not more than 10–15%, as an increase in the pressure ratio can cause the compressor to stall. Naturally, the surplus steam can be utilized for a variety of alternative applications. During the warmer months, the ambient temperature increases and results in reduced thermal efficiency and electrical capacity. An inlet air cooling system for the compressor on a steam injection gas turbine would increase the rating and efficiency of power plants which use this type of equipment. In order to improve the performance of steam injection gas turbines, the authors investigated the option of cooling the intake air to the compressor by harnessing the thermal energy not used to produce the maximum quantity of steam that can be injected into the engine. This alternative use of waste energy makes it possible to reach maximum efficiency in terms of waste recovery. This study examined absorption refrigeration technology, which is one of the various systems adopted to increase efficiency and power rating. The system itself consists of a steam injection gas turbine and a heat recovery and absorption unit, while a computer model was utilized to evaluate the off design performance of the system. The input data required for the model were the following: an operating point, the turbine and compressor curves, the heat recovery and chiller specifications. The performance of an Allison 501 KH steam injection gas plant was analyzed by taking into consideration representative ambient temperature and humidity ranges, the optimal location of the chiller in light of all the factors involved, and which of three possible air cooling systems was the most economically suitable. In order to verify the technical feasibility of the hypothetical model, an economic study was performed on the costs for upgrading the existing steam injection gas cogeneration unit. The results indicate that the estimated pay back period for the project would be four years. In light of these findings, there are clear technical advantages to using gas turbine cogeneration with absorption air cooling in terms of investment.


Author(s):  
Hiroyuki Yamazaki ◽  
Yoshiaki Nishimura ◽  
Masahiro Abe ◽  
Kazumasa Takata ◽  
Satoshi Hada ◽  
...  

Tohoku Electric Power Company, Inc. (Tohoku-EPCO) has been adopting cutting-edge gas turbines for gas turbine combined cycle (GTCC) power plants to contribute for reduction of energy consumption, and making a continuous effort to study the next generation gas turbines to further improve GTCC power plants efficiency and flexibility. Tohoku-EPCO and Mitsubishi Hitachi Power Systems, Ltd (MHPS) developed “forced air cooling system” as a brand-new combustor cooling system for the next generation GTCC system in a collaborative project. The forced air cooling system can be applied to gas turbines with a turbine inlet temperature (TIT) of 1600deg.C or more by controlling the cooling air temperature and the amount of cooling air. Recently, the forced air cooling system verification test has been completed successfully at a demonstration power plant located within MHPS Takasago Works (T-point). Since the forced air cooling system has been verified, the 1650deg.C class next generation GTCC power plant with the forced air cooling system is now being developed. Final confirmation test of 1650deg.C class next generation GTCC system will be carried out in 2020.


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