The Energy Exchanger, a New Concept for High-Efficiency Gas Turbine Cycles

1967 ◽  
Vol 89 (2) ◽  
pp. 217-227 ◽  
Author(s):  
R. C. Weatherston ◽  
A. Hertzberg
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Energy Exchange ◽  
High Efficiency ◽  
Inlet Temperature ◽  
Viscous Effects ◽  
Isentropic Compression ◽  
Combustion Gas ◽  
Power Cycles ◽  
Compression Waves

A method of circumventing the turbine inlet temperature limitation of present-day gas turbines is presented. This method is based on a direct fluid-to-fluid energy exchanger whereby the available energy of expansion of the hot combustion gas in a gas turbine cycle is transferred directly to a colder gas. The aerodynamic wave processes in several possible modes of operation are examined to determine the inherent limitations in efficiency of direct fluid-to-fluid energy exchange processes. In particular, it is demonstrated that, by using a system of isentropic compression waves to avoid shock losses and by carefully choosing the molecular weights of the fluids utilized in the energy exchanger, perfect energy exchange is possible in principle. When allowances are made for losses due to mixing, leakage, and viscous effects, an energy exchanger utilizing heated combustion air at 3240 deg F to drive steam at 1500 deg F with a potential energy exchange efficiency of 85 percent is feasible. Applications of the air-steam energy exchanger operating in gas turbine cycles utilizing a conservative choice of component efficiencies indicate that thermal efficiencies of gas turbine power cycles of 50–60 percent may be possible.

Three Spool High Efficiency Small Scale Gas Turbine Concept

2017 ◽  
Author(s):  
Matti Malkamäki ◽  
Ahti Jaatinen-Värri ◽  
Antti Uusitalo ◽  
Aki Grönman ◽  
Juha Honkatukia ◽  
...  
Keyword(s):  
Power Generation ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Small Scale ◽  
Inlet Temperature ◽  
Substantial Impact ◽  
Electrical Efficiency ◽  
Partial Load ◽  
Reciprocating Engines

Decentralized electricity and heat production is a rising trend in small-scale industry. There is a tendency towards more distributed power generation. The decentralized power generation is also pushed forward by the policymakers. Reciprocating engines and gas turbines have an essential role in the global decentralized energy markets and improvements in their electrical efficiency have a substantial impact from the environmental and economic viewpoints. This paper introduces an intercooled and recuperated three stage, three-shaft gas turbine concept in 850 kW electric output range. The gas turbine is optimized for a realistic combination of the turbomachinery efficiencies, the turbine inlet temperature, the compressor specific speeds, the recuperation rate and the pressure ratio. The new gas turbine design is a natural development of the earlier two-spool gas turbine construction and it competes with the efficiencies achieved both with similar size reciprocating engines and large industrial gas turbines used in heat and power generation all over the world and manufactured in large production series. This paper presents a small-scale gas turbine process, which has a simulated electrical efficiency of 48% as well as thermal efficiency of 51% and can compete with reciprocating engines in terms of electrical efficiency at nominal and partial load conditions.

Comparison of Externally Fired and Internal Combustion Gas Turbines Using Biomass Fuel

2001 ◽  
Vol 123 (4) ◽  
pp. 291-296 ◽  
Author(s):  
Sandro B. Ferreira ◽  
Pericles Pilidis
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Internal Combustion ◽  
Combined Cycle ◽  
Maintenance Cost ◽  
Combustion Gas ◽  
Exhaust Temperature ◽  
Exergetic Analysis ◽  
Main Components

There is a difference of opinion regarding the relative merits of gas turbines using biomass fuels. Some engineers believe that the internal combustion gas turbine coupled to a gasifier will give a higher efficiency than the externally fired gas turbine using pretreated biomass that is not gasified. Others believe the opposite. In this paper, a comparison between these schemes is made, within the framework of the Brazilian perspective. The exergetic analysis of four cycles is described. The first cycle is externally fired (EFGT), the second uses gasified biomass as fuel (BIG/GT), each of them with a combined cycle as a variant (EFGT/CC and BIG/GTCC). These four are then compared to the natural gas turbine cycles (NGT and NGT/CC) in order to evaluate the thermodynamic cost of using biomass. The comparison is carried out in terms of thermal efficiency and in terms of exergetic efficiency and exergy destruction in the main components. The present analysis shows that the EFGT is quite promising. When compared to the NGT cycle, the EFGT gas turbine shows poor efficiency, though this parameter practically equals that of the BIG/GT cycle. The use of a bottoming steam cycle changes the figures, and the EFGT/CC—due to its higher exhaust temperature—results in high efficiency compared to the BIG/GTCC. Its lower initial and maintenance cost may be an important attraction.

scholarly journals High Efficiency-Coal and Gas (HE-C&G): An Advanced Hybrid Power Plant Concept With Sequential Combustion Gas Turbines GT24/GT26

1997 ◽  
Author(s):  
Mircea Fetescu
Keyword(s):  
Power Plant ◽  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Combustion Gas ◽  
Hybrid Power ◽  
Wide Range ◽  
Hybrid Power Plant ◽  
Very High

The High Efficiency-Coal and Gas (HE-C&G) is a hybrid power plant concept integrating Conventional Steam Power Plants (CSPP) and gas turbine / combined cycle plants. The gas turbine exhaust gas energy is recovered in the HRSG providing partial condensate and feedwater preheating and generating steam corresponding to the main boiler live steam conditions (second steam source for the ST). The concept, exhibiting very high design flexibility, integrates the high performance Sequential Combustion gas turbines GT24/GT26 technology into a wide range of existing or new CSPP. Although HE-C&G refers to coal as the most abundant fossil fuel resource, oil or natural gas fired steam plants could be also designed or converted following the same principle. The HE-C&G provides very high marginal efficiencies on natural gas, up to and above 60%, very high operating and dispatching flexibility and on-line optimization of fuel and O&M costs at low capital investment. This paper emphasizes the operating flexibility and resulting benefits, recommending the HE-C&G as one of the most profitable options for generating power especially for conversion of existing CSPP with gas turbines.

Flameholding Tendencies of Natural Gas and Hydrogen Flames at Gas Turbine Premixer Conditions

2014 ◽  
Author(s):  
Elliot Sullivan-Lewis ◽  
Vincent McDonell
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
High Reliability ◽  
Elevated Pressure ◽  
Inlet Temperature ◽  
Increased Risk ◽  
Wide Range ◽  
Lean Premixed

Ground based gas turbines are responsible for generating a significant amount of electric power as well as providing mechanical power for a variety of applications. This is due to their high efficiency, high power density, high reliability, and ability to operate on a wide range of fuels. Due to increasingly stringent air quality requirements, stationary power gas turbines have moved to lean-premixed operation. Lean-premixed operation maintains low combustion temperatures for a given turbine inlet temperature, resulting in low NOx emissions while minimizing emissions of CO and hydrocarbons. In addition, to increase overall cycle efficiency, engines are being operated at higher pressure ratios and/or higher combustor inlet temperatures. Increasing combustor inlet temperatures and pressures in combination with lean-premixed operation leads to increased reactivity of the fuel/air mixture, leading to increased risk of potentially damaging flashback. Curtailing flashback on engines operated on hydrocarbon fuels requires care in design of the premixer. Curtailing flashback becomes more challenging when fuels with reactive components such as hydrogen are considered. Such fuels are gaining interest because they can be generated from both conventional and renewable sources and can be blended with natural gas as a means for storage of renewably generated hydrogen. The two main approaches for coping with flashback are either to design a combustor that is resistant to flashback, or to design one that will not anchor a flame if a flashback occurs. An experiment was constructed to determine the flameholding tendencies of various fuels on typical features found in premixer passage ways (spokes, steps, etc.) at conditions representative of a gas turbine premixer passage way. In the present work tests were conducted for natural gas and hydrogen between 3 and 9 atm, between 530 K and 650K, and free stream velocities from 40 to 100 m/s. Features considered in the present study include a spoke in the center of the channel and a step at the wall. The results are used in conjunction with existing blowoff correlations to evaluate flameholding propensity of these physical features over the range of conditions studied. The results illustrate that correlations that collapse data obtained at atmospheric pressure do not capture trends observed for spoke and wall step features at elevated pressure conditions. Also, a notable fuel compositional effect is observed.

scholarly journals Development of a High Pressure Ratio Centrifugal Compressor for 300kW-Class Ceramic Gas Turbine

1997 ◽  
Author(s):  
T. Sakai ◽  
Y. Tohbe ◽  
T. Fujii ◽  
T. Tatsumi
Keyword(s):  
Research And Development ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Pressure Ratio ◽  
Flow Distribution ◽  
Leading Edge ◽  
Inlet Temperature ◽  
Angle Distribution ◽  
Gas Generator

Research and development of ceramic gas turbines (CGT), which is promoted by the Japanese Ministry of International Trade and Industry (MITI), was started in 1988. The target of the CGT project is development of a 300kW-class ceramic gas turbine with a 42 % thermal efficiency and a turbine inlet temperature (TIT) of 1350°C. Two types of CGT engines are developed in this project. One of the CGT engines, which is called CGT302, is a recuperated two-shaft gas turbine with a compressor, a gas-generator turbine, and a power turbine for cogeneration. In this paper, we describe the research and development of a compressor for the CGT302. Specification of this compressor is 0.89 kg/sec air flow rate and 8:1 pressure ratio. The intermediary target efficiency is 78% and the final target efficiency is 82%, which is the highest level in email centrifugal compressors like this one. We measured impeller inlet and exit flow distribution using three-hole yaw probes which were traversed from the shroud to the hub. Based on the measurement of the impeller exit flow, diffusers with a leading edge angle distribution adjusted to the inflow angle were designed and manufactured. Using this diffuser, we were able to attain a high efficiency (8:1 pressure ratio and 78% adiabatic efficiency).

High Efficiency Gas Turbine Based Power Cycles—A Study of the Most Promising Solutions: Part 1—A Review of the Technology

2008 ◽  
Author(s):  
Rakesh K. Bhargava ◽  
Michele Bianchi ◽  
Stefano Campanari ◽  
Andrea De Pascale ◽  
Giorgio Negri di Montenegro ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Performance ◽  
High Efficiency ◽  
Water Injection ◽  
Thermodynamic Cycle ◽  
Brayton Cycle ◽  
Molten Carbonate ◽  
Power Cycles

Commercially available gas turbines have been mostly designed based on the simple Brayton cycle and despite the enormous advancements made in their components design, materials technology, blade cooling methods, etc., thermodynamic performance achievable for this simple cycle is limited. Numerous variants to the basic Brayton cycle viz., Recuperated (REC), Inter-Cooled (IC), Re-Heat (RH), steam injected (STIG) and their combinations have been proposed, extensively discussed in the literature since the early stages of gas turbine development and few of them have been successfully implemented. New variants not yet implemented in commercial engines and still in various stages of the development with potential for additional performance improvement are: advanced Steam Injected cycle and its variants (such as Inter-cooled Steam Injected, (ISTIG)), Recuperated Water Injection cycle (RWI), Humidified Air Turbine (HAT) cycle and Cascaded Humidified Advanced Turbine (CHAT) cycle, Brayton cycle with high temperature fuel cells (Molten Carbonate Fuel Cells (MCFC) and Solid Oxide Fuel Cells (SOFC)) and their combinations with the available modified Brayton cycles. The main objective of this paper (Part 1 of the two-part paper) is to provide a comprehensive review of high performance (with most promising solutions) complex gas turbine cycles, describing their main characteristics, benefits and drawbacks in comparison with the simple Brayton cycle. Detailed parametric thermodynamic cycle analyses for the selected high efficiency cycles under development are presented in Part 2 of this paper.

scholarly journals Advantages of Air Conditioning and Supercharging an LM6000 Gas Turbine Inlet

1994 ◽  
Author(s):  
Donald A. Kolp ◽  
Harold A. Guidotti ◽  
William M. Flye
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Performance Enhancement ◽  
Heat Rate ◽  
Inlet Temperature ◽  
Factors Affecting ◽  
Subsequent Performance ◽  
Turbine Inlet ◽  
New Generation

Of all the external factors affecting a gas turbine, inlet pressure and temperature have the greatest impact on performance. The effect of inlet temperature variations is especially pronounced in the new generation of high-efficiency gas turbines typified by the 40 MW GE LM6000. A reduction of 50 F (28 C) in inlet temperature can result in a 30% increase in power and a 4.5% improvement in heat rate. An elevation increase to 5000 feet (1524 meters) above sea level decreases turbine output 17%; conversely supercharging can increase output more than 20%. This paper addresses various means of heating, cooling and supercharging LM6000 inlet air. An economic model is developed and sample cases are cited to illustrate the optimization of gas turbine inlet systems, taking into account site conditions, incremental equipment cost and subsequent performance enhancement.

Advantages of Air Conditioning and Supercharging an LM6000 Gas Turbine Inlet

1995 ◽  
Vol 117 (3) ◽  
pp. 513-527 ◽  
Author(s):  
D. A. Kolp ◽  
W. M. Flye ◽  
H. A. Guidotti
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Performance Enhancement ◽  
Heat Rate ◽  
Inlet Temperature ◽  
Factors Affecting ◽  
Subsequent Performance ◽  
Turbine Inlet ◽  
Percent Improvement

Of all the external factors affecting a gas turbine, inlet pressure and temperature have the greatest impact on performance. The effect of inlet temperature variations is especially pronounced in the new generation of high-efficiency gas turbines typified by the 40 MW GE LM6000. A reduction of 50°F (28°C) in inlet temperature can result in a 30 percent increase in power and a 4.5 percent improvement in heat rate. An elevation increase to 5000 ft (1524 m) above sea level decreases turbine output 17 percent; conversely supercharging can increase output more than 20 percent. This paper addresses various means of heating, cooling and supercharging LM6000 inlet air. An economic model is developed and sample cases are cited to illustrate the optimization of gas turbine inlet systems, taking into account site conditions, incremental equipment cost and subsequent performance enhancement.

Gas Dynamic Simulation of Shockless Explosion Combustion for Gas Turbine Power Cycles

2017 ◽  
Author(s):  
T. S. Rähse ◽  
C. O. Paschereit ◽  
P. Stathopoulos ◽  
P. Berndt ◽  
R. Klein
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Inlet Temperature ◽  
Power Cycles ◽  
Total Enthalpy ◽  
Gas Dynamic ◽  
Turbine Inlet ◽  
Homogeneous Combustion

With the ongoing stagnation of the progress towards higher efficiency gas turbines, alternative approaches in combustion receive more attention than ever before. Besides, increasing efficiency and reducing emissions at the same time has become a first priority of the industry in the last few decades. Constant volume combustion is considered a technology capable of achieving a significant increase in thermal efficiency when applied in gas turbines. In this work, models of gas turbine cycles with two different combustion methods, being a shockless explosion combustion and an isobaric homogeneous combustion, will be simulated and compared. A code based on the one dimensional Euler equations is utilized to calculate the exhaust gas outlet parameters of the shockless explosion combustion chamber, while taking into account all the gas dynamic phenomena in it. The efficiency of the turbine is computed by steady state operational maps. The simulations provide numerous detailed results with a focus on the dependency of the SEC cycle’s thermal efficiency to the compressor pressure ratio and the turbine inlet temperature. Evaluating the kinetic energy in the total enthalpy of the turbine inlet flow is also an essential investigation.

Gas Turbine Fouling: A Comparison Among 100 Heavy-Duty Frames

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Nicola Aldi ◽  
Nicola Casari ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
Pier Ruggero Spina ◽  
...  
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Efficiency ◽  
Particle Deposition ◽  
High Efficiency ◽  
Inlet Temperature ◽  
Low Grade ◽  
Outlet Temperature ◽  
Heavy Duty

Over recent decades, the variability and high costs of the traditional gas turbine fuels (e.g., natural gas) have pushed operators to consider low-grade fuels for running heavy-duty frames. Synfuels, obtained from coal, petroleum, or biomass gasification, could represent valid alternatives in this sense. Although these alternatives match the reduction of costs and, in the case of biomass sources, would potentially provide a CO2 emission benefit (reduction of the CO2 capture and sequestration costs), these low-grade fuels have a higher content of contaminants. Synfuels are filtered before the combustor stage, but the contaminants are not removed completely. This fact leads to a considerable amount of deposition on the nozzle vanes due to the high temperature value. In addition to this, the continuous demand for increasing gas turbine efficiency determines a higher combustor outlet temperature. Current advanced gas turbine engines operate at a turbine inlet temperature (TIT) of (1400–1500) °C, which is high enough to melt a high proportion of the contaminants introduced by low-grade fuels. Particle deposition can increase surface roughness, modify the airfoil shape, and clog the coolant passages. At the same time, land-based power units experience compressor fouling, due to the air contaminants able to pass through the filtration barriers. Hot sections and compressor fouling work together to determine performance degradation. This paper proposes an analysis of the contaminant deposition on hot gas turbine sections based on machine nameplate data. Hot section and compressor fouling are estimated using a fouling susceptibility criterion. The combination of gas turbine net power, efficiency, and TIT with different types of synfuel contaminants highlights how each gas turbine is subjected to particle deposition. The simulation of particle deposition on 100 gas turbines ranging from 1.2 MW to 420 MW was conducted following the fouling susceptibility criterion. Using a simplified particle deposition calculation based on TIT and contaminant viscosity estimation, the analysis shows how the correlation between type of contaminant and gas turbine performance plays a key role. The results allow the choice of the best heavy-duty frame as a function of the fuel. Low-efficiency frames (characterized by lower values of TIT) show the best compromise in order to reduce the effects of particle deposition in the presence of high-temperature melting contaminants. A high-efficiency frame is suitable when the contaminants are characterized by a low-melting point thanks to their lower fuel consumption.

Sign in / Sign up

Export Citation Format

Share Document