Low-Calorific Fuel Mix in a Large Size Combined Cycle Plant

2009 ◽  
Author(s):  
Klas Jonshagen ◽  
Magnus Genrup ◽  
Pontus Eriksson
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Pressure Ratio ◽  
Expansion Ratio ◽  
Combined Cycle ◽  
Cycle Performance ◽  
Exhaust Temperature ◽  
Large Size ◽  
Combined Cycle Plant ◽  
Reheat Steam

This paper will address the effects of mixing low-calorific fuel in to a natural gas fuelled large size combined cycle plant. Three different biofuels are tested namely; air blown gasification gas, indirect gasification gas and digestion gas. Simulations have been performed from 0–100% biofuel–natural gas mixtures. The biofuel impacts on the full cycle performance are discussed. Some more in-depth discussion about turbo-machinery components will be introduced when needed for the discussion. The compressors pressure ratio will increase in order to push the inert ballast of the low calorific fuels trough the turbine. Despite the increased expansion ratio in the gas turbine, the exhaust temperature raises slightly which derives from changed gas properties. The work is based on an in-house advanced off-design model within the software package IPSEPro. Sweden’s newest plant “O¨resundsverket”, which is a combined heat and power (CHP) plant, is used as a basis for the investigation. The plant is based on a GE Frame-9 gas turbine and has a triple-pressure reheat steam cycle.

The Reheat Gas Turbine With Steam-Blade Cooling—A Means of Increasing Reheat Pressure, Output, and Combined Cycle Efficiency

1982 ◽  
Vol 104 (1) ◽  
pp. 9-22 ◽  
Author(s):  
I. G. Rice
Keyword(s):  
Gas Turbine ◽  
Pressure Ratio ◽  
Pressure Rise ◽  
Expansion Ratio ◽  
Combined Cycle ◽  
Gas Generator ◽  
Exhaust Temperature ◽  
Blade Cooling ◽  
Cycle Efficiency ◽  
Turbine Blading

The reheat (RH) pressure can be appreciably increased by applying steam cooling to the gas-generator (GG) turbine blading which in turn allows a higher RH firing temperature for a fixed exhaust temperature. These factors increase gas turbine output and raise combined-cycle efficiency. The GG turbine blading will approach “uncooled expansion efficiency”. Eliminating cooling air increases the gas turbine RH pressure by 10.6 percent. When steam is used (injected) as the blade coolant, additional GG work is also developed which further increases the RH pressure by another 12.0 percent to yield a total increase of approximately 22.6 percent. The 38-cycle pressure ratio 2400° F (1316° C) TIT GG studied produces a respectable 6.5 power turbine expansion ratio. The higher pressure also noticeably reduces the physical size of the RH combustor. This paper presents an analysis of the RH pressure rise when applying steam to blade cooling.

Using Hydrogen as Gas Turbine Fuel

2003 ◽  
Author(s):  
Paolo Chiesa ◽  
Giovanni Lozza ◽  
Luigi Mazzocchi
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Volume Flow Rate ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Point Of View ◽  
Inert Gases ◽  
Detailed Model ◽  
Large Size ◽  
Heavy Duty Gas Turbine

This paper addresses the possibility to burn hydrogen in a large size, heavy–duty gas turbine designed to run on natural gas, as a possible short-term measure to reduce greenhouse emissions of the power industry. The process used to produce hydrogen is not discussed here: we mainly focus on the behavior of the gas turbine, by analyzing the main operational aspects related to switching from natural gas to hydrogen. We will consider the effects of variations of volume flow rate and of thermo-physical properties on the matching between turbine and compressor and on the blade cooling of the hot rows of the gas turbine. In the analysis we will keep into account that those effects are largely emphasized by the abundant dilution of the fuel by inert gases (steam or nitrogen), necessary to control the NOx emissions. Three strategies will be considered to adapt the original machine, designed to run on natural gas, to operate properly with diluted hydrogen (VGV operations, increased pressure ratio, re-engineered machine). The performance analysis, carried out by a calculation method including a detailed model the cooled gas turbine expansion, shows that moderate efficiency decays can be predicted with elevated dilution rates (nitrogen is preferable to steam under this point of view). The combined cycle power output substantially increases if not controlled by VGV operations. It represents an opportunity if some moderate re-design is accepted (turbine blade height modifications or HP compressor stages addition).

Effect of Deaerator Parameters on Simple and Reheat Gas/Steam Combined Cycle With Different Cooling Medium

2019 ◽  
Author(s):  
Mayank Maheshwari ◽  
Onkar Singh
Keyword(s):  
Gas Turbine ◽  
Mass Fraction ◽  
Power Plants ◽  
Performance Enhancement ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Cycle Performance ◽  
Inlet Temperature ◽  
Operating Pressure ◽  
Cooling Medium

Abstract Performance of gas/steam combined cycle power plants relies upon the performance exhibited by both gas based topping cycle and steam based bottoming cycle. Therefore, the measures for improving the performance of the gas turbine cycle and steam bottoming cycle eventually result in overall combined cycle performance enhancement. Gas turbine cooling medium affects the cooling efficacy. Amongst different parameters in the steam bottoming cycle, the deaerator parameter also plays its role in cycle performance. The present study analyzes the effect of deaerator’s operating pressure being varied from 1.6 bar to 2.2 bar in different configurations of simple and reheat gas/steam combined cycle with different cooling medium for fixed cycle pressure ratio of 40, turbine inlet temperature of 2000 K and ambient temperature of 303 K with varying ammonia mass fraction from 0.6 to 0.9. Analysis of the results obtained for different combined cycle configuration shows that for the simple gas turbine and reheat gas turbine-based configurations, the maximum work output of 643.78 kJ/kg of air and 730.87 kJ/kg of air respectively for ammonia mass fraction of 0.6, cycle efficiency of 54.55% and 53.14% respectively at ammonia mass fraction of 0.7 and second law efficiency of 59.71% and 57.95% respectively at ammonia mass fraction of 0.7 is obtained for the configuration having triple pressure HRVG with ammonia-water turbine at high pressure and intermediate pressure and steam turbine operating at deaerator pressure of 1.6 bar.

Effect of Bottoming Cycle Alternatives on the Performance of Combined Cycle

2003 ◽  
Author(s):  
R. Yadav
Keyword(s):  
Gas Turbine ◽  
Pressure Ratio ◽  
Positive Influence ◽  
Combined Cycle ◽  
Exhaust Temperature ◽  
Compressor Pressure Ratio ◽  
Topping Cycle ◽  
Steam Parameters ◽  
Cycle Efficiency ◽  
Steam Cycle

The increase in efficiency of combined cycle has mainly been caused by the improvements in gas turbine cycle efficiency. With the increase in firing temperature the exhaust temperature is substantially high around 873 K for moderate compressor pressure ratio, which has positive influence on steam cycle efficiency. Minimizing the irreversibility within the heat recovery steam generator HRSG and choosing proper steam cycle configuration with optimized steam parameters improve the steam cycle efficiency and thus in turn the combined cycle efficiency. In this paper, LM9001H gas turbine, a state of art technology turbine with modified compressor pressure ratio has been chosen as a topping cycle. Various bottoming cycles alternatives (sub-critical) coupled with LM9001H topping cycle with and without recuperation such as dual and triple pressure steam cycles with and without reheat have been chosen to predict the performance of combined cycle.

On-Design and Off-Design Performance Analysis of a Gas Turbine Combined Cycle Using the Exergy Method

2000 ◽  
Author(s):  
Alcides Codeceira Neto ◽  
Pericles Pilidis
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Exergy Analysis ◽  
Pressure Ratio ◽  
Calorific Value ◽  
Combined Cycle ◽  
Exergy Destruction ◽  
Turbine Engine ◽  
Design Point

The present paper describes an on-design and an off-design performance study of gas turbine combined cycle based power plants. The exergy analysis has been carried out along with the performance assessment, considering the overall plant exergetic efficiency and the exergy destruction in the various components of the plant. The exergy method highlights irreversibility within the plant components, and it is of particular interest in this investigation. A computational analysis has been carried out to investigate the effects of compressor pressure ratio and gas turbine entry temperature on the thermodynamic performance of combined gas / steam power cycles. The exergy analysis has been performed for on-design point calculations, considering single shaft gas turbines with different compressor pressure ratios and turbine entry temperatures. Nearly 100 MW shaft power gas turbine engines burning natural gas fuel have been selected in this study. The off-design calculations have been performed for one of the gas turbines selected from the on-design point studies. For this particular gas turbine engine, fuel has been changed from natural gas to a low calorific value fuel gas originated from the gasification of wood. The exergy analysis indicates that maximum exergy is destroyed in the combustor, in the case of combined gas / steam cycles burning natural gas. For these studies on-design point, the exergy destruction in the combustor is found to decrease with increasing compressor pressure ratio to an optimum value and with increasing turbine entry temperature. In the off-design case the gas turbine engine is burning low calorific value fuel originated from the gasification of wood. The maximum exergy destruction occurs in the gasification process, followed by the combustion process in the gas turbine.

Thermodynamics Analysis of a Combined Cycle Power Plant

2007 ◽  
Author(s):  
Feliciano Pava´n ◽  
Marco Romo ◽  
Juan Prince
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Work Output ◽  
Turbine Inlet Temperature ◽  
Combined Cycle Power Plant ◽  
Turbine Inlet ◽  
Combined Cycle Plant

The present paper is a thermodynamics analysis, i.e. both energy and exergy analyses for a natural gas based combined cycle power plant. The analysis was performed for an existing 240 MW plant, where the steam cycle reduces the irreversibilities during heat transfer from gas to water/steam. The effect of operating variables such as pressure ratio, gas turbine inlet temperature on the performance of combined cycle power plant has been investigated. The pressure ratio and maximum temperature (gas turbine inlet temperature) are identified as the dominant parameters having impact on the combined cycle plant performance. The work output of the topping cycle is found to increase with pressure ratio, while for the bottoming cycle it decreases. However, for the same gas turbine inlet temperature the overall work output of the combined cycle plant increases up to a certain pressure ratio, and thereafter not much increase is observed. The exergy losses of the individual components in the plant are evaluated based on second law of thermodynamics. The present results form a basis on which further work can be conducted to improve the performance of these units.

Using Hydrogen as Gas Turbine Fuel

2005 ◽  
Vol 127 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Paolo Chiesa ◽  
Giovanni Lozza ◽  
Luigi Mazzocchi
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Guide Vane ◽  
Volume Flow Rate ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Point Of View ◽  
Inert Gases ◽  
Detailed Model ◽  
Heavy Duty Gas Turbine

This paper addresses the possibility to burn hydrogen in a large size, heavy-duty gas turbine designed to run on natural gas as a possible short-term measure to reduce greenhouse emissions of the power industry. The process used to produce hydrogen is not discussed here: we mainly focus on the behavior of the gas turbine by analyzing the main operational aspects related to switching from natural gas to hydrogen. We will consider the effects of variations of volume flow rate and of thermophysical properties on the matching between turbine and compressor and on the blade cooling of the hot rows of the gas turbine. In the analysis we will take into account that those effects are largely emphasized by the abundant dilution of the fuel by inert gases (steam or nitrogen), necessary to control the NOx emissions. Three strategies will be considered to adapt the original machine, designed to run on natural gas, to operate properly with diluted hydrogen: variable guide vane (VGV) operations, increased pressure ratio, re-engineered machine. The performance analysis, carried out by a calculation method including a detailed model of the cooled gas turbine expansion, shows that moderate efficiency decays can be predicted with elevated dilution rates (nitrogen is preferable to steam under this point of view). The combined cycle power output substantially increases if not controlled by VGV operations. It represents an opportunity if some moderate re-design is accepted (turbine blade height modifications or high-pressure compressor stages addition).

Exergy Analysis of Gas-Turbine Combined Cycle With CO2 Capture Using Pre-Combustion Decarbonization of Natural Gas

2002 ◽  
Author(s):  
Hanne M. Kvamsdal ◽  
Ivar S. Ertesva˚g ◽  
Olav Bolland ◽  
Tor Tolstad
Keyword(s):  
Natural Gas ◽  
Electric Power ◽  
Gas Turbine ◽  
Co2 Capture ◽  
Exergy Analysis ◽  
Pressure Ratio ◽  
Power Production ◽  
Combined Cycle ◽  
Electric Power Production ◽  
Chemical Exergy

A concept for natural-gas fired power plants with CO2 capture has been investigated using exergy analysis. The present approach involves decarbonization of the natural gas by authothermal reforming prior to combustion, producing a hydrogen-rich fuel. An important aspect of this type of process is the integration between the combined cycle and the reforming process. The net electric power production was 47.7% of the Lower Heating Value (LHV) or 45.8% of the chemical exergy of the supplied natural-gas. In addition, the chemical exergy of the captured CO2 and the compression of this CO2 to 80 bar represented 2.1% and 2.7%, respectively, of the natural-gas chemical exergy. For a corresponding conventional combined cycle without CO2 capture, the net electric power production was 58.4% of the LHV or 56.1% of the fuel chemical exergy. A detailed breakdown of irreversibility is presented. In the decarbonized natural-gas power plant, the effect of varying supplementary firing (SF) for reformer-feed preheating was investigated. This showed that SF increased the total irreversibility and decreased the net output of the plant. Next, the effects of increased gas-turbine inlet temperature and of gas-turbine pressure ratio were studied. For the conventional plant, higher pressure led to increased efficiency for some cases. In the decarbonized natural-gas process, however, higher pressure ratio led to higher irreversibility and reduced thermal-plant efficiency.

Energy and Exergy Analyses of a Natural Gas Fired Combined Cycle Cogeneration System

2007 ◽  
Author(s):  
B. Law ◽  
B. V. Reddy
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Operating Variables ◽  
Energy And Exergy ◽  
Cogeneration System ◽  
Multiple Process ◽  
Process Heat

Combined cycle cogeneration systems have the ability to produce power and process heat more efficiently, leading to higher performance and reduced green house gas emissions. In the present work the performance of a natural gas fired combined cycle cogeneration unit with multiple process heaters is investigated to study the effect of operating variables on the performance. The operating conditions investigated include, gas turbine pressure ratio, process heat loads and process steam extraction pressure. The gas turbine pressure ratio significantly influences the performance of the combined cycle cogeneration system. The process heat load influences combined cycle efficiency and combined cycle cogeneration efficiency in opposite ways. The exergy analysis is conducted to identify the exergy destruction and losses in different components of the combined cycle cogeneration unit.

A Study of Cycle Performance of Ceramic Gas Turbines

1997 ◽  
Author(s):  
H. Sugishita ◽  
H. Mori ◽  
R. Chikami ◽  
Y. Tsukuda ◽  
S. Yoshino ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Performance Improvement ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Cycle Performance ◽  
Gas Temperature ◽  
Blade Cooling ◽  
Combined Cycles ◽  
Cooling Air

A study has been carried out to assess the performance improvement of a combined cycle used for an industrial power plant when ceramic turbine components are employed. This paper presents the details of this study. Performance improvement is obtained as a result of reduced blade cooling air. In this study four different kinds of combined cycles were investigated and these are listed below: A. Combined cycle with a simple gas turbine. B. Combined cycle with an inter-cooled gas turbine. C. Combined cycle with a reheat gas turbine. D. Combined cycle with an inter-cooled reheat gas turbine. Results of this study indicate that the combined cycle with a simple gas turbine is the most practical of the four cycles studied with an efficiency of higher than 60%. The combined cycle with reheat gas turbine has the highest efficiency if a higher compressor exit air temperature and a high gas temperature (over 1000°C) to reheat the combustion system are used. A higher pressure ratio is required to optimize the cycle performance of the combined cycle with the ceramic turbine components than that with the metal turbine components because of reduced blade cooling air. To minimize leakage air for these higher pressure ratios, advanced seal technology should be applied to the gas turbines.

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