Dynamic Simulation of the Gravel Bed Combustor-Gas Turbine System

1991 ◽  
Author(s):  
Carl A. Palmer ◽  
Kenneth W. Ragland
Keyword(s):  
Gas Turbine ◽  
Flow Rate ◽  
Control Strategies ◽  
Control Variable ◽  
Load Level ◽  
Primary Control ◽  
Fuel Feed ◽  
Gravel Bed ◽  
Fuel Flow ◽  
Cogeneration System

A novel gravel bed, downdraft, woodchip combustor that directly-fires a gas turbine for use in a cogeneration system has been developed. In this combustor, the fuel burning rate is determined by pressure, temperature, air flow rate, and fuel moisture content, and not by the fuel feed rate. When the gravel bed combustor is connected to a gas turbine system, the operator loses the freedom to directly set the fuel flow rate, which is the primary control variable for conventional gas turbine systems. Other control problems introduced by the gravel bed include a large thermal lag and a sizable pressure drop. This paper presents a computer model that integrates the dynamic characteristics of an actual gas turbine with the characteristics of the gravel bed combustor. The program determines system behavior and helps evaluate possible control strategies. The system is controlled using the CO2 level leaving the gravel bed. The bypass valve setting determines the load level. Both the slow temperature dynamics and quick turbomachinery dynamics must be considered when operating the system.

Dynamic Simulation of a HRSG System for a Given Start-Up/Shut Down Curve

2011 ◽  
Author(s):  
Hun Cha ◽  
Yoo Seok Song ◽  
Kyu Jong Kim ◽  
Jung Rae Kim ◽  
Sung Min KIM
Keyword(s):  
Dynamic Analysis ◽  
Gas Turbine ◽  
Flow Rate ◽  
Exhaust Gas ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Start Up ◽  
Gas Turbine Exhaust ◽  
Main Steam ◽  
Duct Burner

An inappropriate design of HRSG (Heat Recovery Steam Generator) may lead to mechanical problems including the fatigue failure caused by rapid load change such as operating trip, start-up or shut down. The performance of HRSG with dynamic analysis should be investigated in case of start-up or shutdown. In this study, dynamic analysis for the HRSG system was carried out by commercial software. The HRSG system was modeled with HP, IP, LP evaporator, duct burner, superheater, reheater and economizer. The main variables for the analysis were the temperature and mass flow rate from gas turbine and fuel flow rate of duct burner for given start-up (cold/warm/hot) and shutdown curve. The results showed that the exhaust gas condition of gas turbine and fuel flow rate of duct burner were main factors controlling the performance of HRSG such as flow rate and temperature of main steam from final superheater and pressure of HP drum. The time delay at the change of steam temperature between gas turbine exhaust gas and HP steam was within 2 minutes at any analysis cases.

Model Analysis of Syngas Combustion and Emissions for a Micro Gas Turbine

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Chi-Rong Liu ◽  
Hsin-Yi Shih
Keyword(s):  
Gas Turbine ◽  
Flow Rate ◽  
Heat Input ◽  
Emission Characteristics ◽  
Nox Emissions ◽  
Fuel Flow Rate ◽  
Micro Gas Turbine ◽  
Fuel Flow ◽  
Temperature Distributions ◽  
Flame Structures

The purpose of this study is to investigate the combustion and emission characteristics of syngas fuels applied in a micro gas turbine, which is originally designed for a natural gas fired engine. The computation results were conducted by a numerical model, which consists of the three-dimension compressible k–ε model for turbulent flow and PPDF (presumed probability density function) model for combustion process. As the syngas is substituted for methane, the fuel flow rate and the total heat input to the combustor from the methane/syngas blended fuels are varied with syngas compositions and syngas substitution percentages. The computed results presented the syngas substitution effects on the combustion and emission characteristics at different syngas percentages (up to 90%) for three typical syngas compositions and the conditions where syngas applied at fixed fuel flow rate and at fixed heat input were examined. Results showed the flame structures varied with different syngas substitution percentages. The high temperature regions were dense and concentrated on the core of the primary zone for H2-rich syngas, and then shifted to the sides of the combustor when syngas percentages were high. The NOx emissions decreased with increasing syngas percentages, but NOx emissions are higher at higher hydrogen content at the same syngas percentage. The CO2 emissions decreased for 10% syngas substitution, but then increased as syngas percentage increased. Only using H2-rich syngas could produce less carbon dioxide. The detailed flame structures, temperature distributions, and gas emissions of the combustor were presented and compared. The exit temperature distributions and pattern factor (PF) were also discussed. Before syngas fuels are utilized as an alternative fuel for the micro gas turbine, further experimental testing is needed as the modeling results provide a guidance for the improved designs of the combustor.

scholarly journals Simulation of a Steam Injected Gas Turbine Plant Control System

1997 ◽  
Author(s):  
Shusheng Zang ◽  
Jaqiang Pan
Keyword(s):  
Gas Turbine ◽  
Flow Rate ◽  
Controller Design ◽  
Dynamic Performance ◽  
Linear Quadratic Regulator ◽  
Linear Quadratic ◽  
Turbine Plant ◽  
Fuel Flow ◽  
Lqr Controller ◽  
Gas Turbine Plant

The design of a modern Linear Quadratic Regulator (LQR) is described for a test steam injected gas turbine (STIG) unit. The LQR controller is obtained by using the fuel flow rate and the injected steam flow rate as the output parameters. To meet the goal of the shaft speed control, a classical Proportional Differential (PD) controller is compared to the LQR controller design. The control performance of the dynamic response of the STIG plant in the case of rejection of load is evaluated. The results of the computer simulation show a remarkable improvement on the dynamic performance of the STIG unit.

Performance Evaluation of Solid Oxide Fuel Cell Engines Integrated With Single/Dual-Spool Turbochargers

2011 ◽  
Vol 8 (6) ◽  
Author(s):  
So-Ryeok Oh ◽  
Jing Sun ◽  
Herb Dobbs ◽  
Joel King
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Control Strategies ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Operating Characteristics ◽  
Load Following ◽  
Fuel Flow

This study investigates the performance and operating characteristics of 5kW-class solid oxide fuel cell and gas turbine (SOFC/GT) hybrid systems for two different configurations, namely single- and dual- spool gas turbines. Both single and dual spool turbo-chargers are widely used in the gas turbine industry. Even though their operation is based on the same physical principles, their performance characteristics and operation parameters vary considerably due to different designs. The implications of the differences on the performance of the hybrid SOFC/GT have not been discussed in literature, and will be the topic of this paper. Operating envelops of single and dual shaft systems are identified and compared. Performance in terms of system efficiency and load following is analyzed. Sensitivities of key variables such as power, SOFC temperature, and GT shaft speed to the control inputs (namely, fuel flow, SOFC current, generator load) are characterized, all in an attempt to gain insights on the design implication for the single and dual shaft SOFC/GT systems. Dynamic analysis are also performed for part load operation and load transitions, which shed lights for the development of safe and optimal control strategies.

SOFC Stack Model for Integration Into a Hybrid System: Stack Response to Control Variables

2015 ◽  
Vol 12 (3) ◽  
Author(s):  
Michael M. Whiston ◽  
Melissa M. Bilec ◽  
Laura A. Schaefer
Keyword(s):  
Flow Rate ◽  
Current Density ◽  
Cell Model ◽  
Control Strategies ◽  
Negative Electrode ◽  
Open Loop ◽  
Fuel Utilization ◽  
Tight Coupling ◽  
Fuel Flow ◽  
Energy And Momentum

Due to the tight coupling of physical processes inside solid oxide fuel cells (SOFCs), efficient control of these devices depends largely on the proper pairing of controlled and manipulated variables. The present study investigates the uncontrolled, dynamic behavior of an SOFC stack that is intended for use in a hybrid SOFC-gas turbine (GT) system. A numerical fuel cell model is developed based on charge, species mass, energy, and momentum balances, and an equivalent circuit is used to combine the fuel cell's irreversibilities. The model is then verified on electrochemical, mass, and thermal timescales. The open-loop response of the average positive electrode-electrolyte-negative electrode (PEN) temperature, fuel utilization, and SOFC power to step changes in the inlet fuel flow rate, current density, and inlet air flow rate is simulated on different timescales. Results indicate that manipulating the current density is the quickest and most efficient way to change the SOFC power. Meanwhile, manipulating the fuel flow is found to be the most efficient way to change the fuel utilization. In future work, it is recommended that such control strategies be further analyzed and compared in the context of a complete SOFC-GT system model.

Influence of Disturbances on Transients of a Gas Turbine Ship Propulsion System — Preliminary Investigations

2000 ◽  
Author(s):  
Marek Dzida ◽  
Zygfryd Domachowski
Keyword(s):  
Angular Velocity ◽  
Gas Turbine ◽  
Flow Rate ◽  
Temperature Response ◽  
Outlet Temperature ◽  
Propeller Shaft ◽  
Fuel Flow Rate ◽  
Ship Propulsion ◽  
Fuel Flow ◽  
Ship Propeller

A gas turbine ship propulsion control system transients have been investigated. On the basis of a mathematical model composed of blocks modelling a two-shaft gas turbine, a gear (mechanical or electric), and a coupling shaft, some preliminary simulations have been carried out. Ship propeller shaft angular velocity, fuel flow rate, and gas turbine combustion chamber outlet temperature response to the ship propeller shaft angular velocity set point, and fuel flow rate, changes have been analyzed. Influences of limiters in the controller action on analyzed transients have been compared.

Simulation of Maneuvering Characteristics of a Destroyer Study Ship Using a Modified Nonlinear Model

1975 ◽  
Vol 19 (04) ◽  
pp. 254-265
Author(s):  
Samuel H. Brown ◽  
Reidar Alvestad
Keyword(s):  
Mathematical Model ◽  
Gas Turbine ◽  
Flow Rate ◽  
Equations Of Motion ◽  
Analog Computer ◽  
Fuel Flow Rate ◽  
Turbine Engine ◽  
Engine Torque ◽  
Ship Propulsion ◽  
Fuel Flow

This paper describes an analog computer maneuvering simulation of a destroyer study ship. The mathematical model used includes the ship propulsion machinery dynamics and the ship equations of motion. The model couples the ship propulsion dynamics equations with nonlinear maneuvering equations. The power plant representation consists of a simplified mathematical model of a General Electric LM2500 gas turbine engine and is primarily an engine mapping of engine torque versus engine speed using fuel flow. rate as a parameter. The simulation is used to accurately predict slow transients in ship speed during maneuvers resulting from slow increases in the fuel flow rate to the gas turbine. The advantage of the modified model presented in this paper over those not including propulsion dynamics is that it permits simulations of the effects of maneuvering on the propulsion plant.

A Comparison of the Predicted and Measured Thermodynamic Performance of a Gas Turbine Cogeneration System

1987 ◽  
Vol 109 (1) ◽  
pp. 32-38 ◽  
Author(s):  
J. W. Baughn ◽  
R. A. Kerwin
Keyword(s):  
Electric Power ◽  
Gas Turbine ◽  
Computer Model ◽  
Measurement Techniques ◽  
Actual Performance ◽  
Fuel Flow ◽  
Savings Rate ◽  
Thermodynamic Performance ◽  
Cogeneration System ◽  
Steam Production

The thermodynamic performance of a gas turbine cogeneration system is predicted using a computer model. The predicted performance is compared to the actual performance, determined by measurements, in terms of various thermodynamic performance parameters which are defined and discussed in this paper. These parameters include the electric power output, fuel flow rate, steam production, electrical efficiency, steam efficiency, and total plant efficiency. Other derived parameters are the net heat rate, the power-to-heat ratio, and the fuel savings rate. This paper describes the cogeneration plant, the computer model, and the measurement techniques used to determine each of the necessary measurands. The predicted and the measured electric power compare well. The predicted fuel flow and steam production are less than measured. The results demonstrate that this type of comparison is needed if computer models are to be used successfully in the design and selection of cogeneration systems.

scholarly journals Development of Controls for Dynamic Operation of Carbonate Fuel Cell-Gas Turbine Hybrid Systems

2005 ◽  
Author(s):  
Rory A. Roberts ◽  
Jack Brouwer ◽  
Eric Liese ◽  
Randall S. Gemmen
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Control Strategies ◽  
Cell Voltage ◽  
Modeling Tools ◽  
Dynamic Operation ◽  
Fuel Flow ◽  
Low Emission ◽  
Hybrid Power Plant ◽  
Demand Fluctuations

Hybrid fuel cell/gas turbine (FC/GT) systems have been shown through experiment and simulation to be highly efficient technologies with low emissions. Maintaining efficient, low emission, and safe operation, whether during disturbances or regular operational transients, is a challenge to both understand and address. Some likely disturbances can arise from changes in ambient temperature, fuel flow variations induced by supply pressure disturbances, fuel composition variability, and power demand fluctuations. To gain insight into the dynamic operation of such cycles and address operating challenges, dynamic modeling tools have been developed at two different laboratories. In this paper these models are used to simulate the dynamic operation of an integrated MCFC/GT hybrid system and to subsequently develop and test control strategies for the hybrid power plant. Two control strategies are developed and tested for their ability to control the system during various perturbations. Predicted fuel cell operating temperature, fuel utilization, fuel cell and GT power, shaft speed, compressor mass flow and temperatures throughout the FC/GT system are presented for the controlled response to a fuel cell voltage increase in order to show the effect of a load decrease.

Gas Turbine Engine Emissions—Part I: Volatile Organic Compounds and Nitrogen Oxides

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Michael T. Timko ◽  
Scott C. Herndon ◽  
Ezra C. Wood ◽  
Timothy B. Onasch ◽  
Megan J. Northway ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Gas Turbine ◽  
Gas Phase ◽  
Organic Compounds ◽  
Flow Rate ◽  
Fuel Flow Rate ◽  
Engine Emissions ◽  
Turbine Engine ◽  
Fuel Flow ◽  
Volatile Organic

The potential human health and environmental impacts of aircraft gas turbine engine emissions during normal airport operation are issues of growing concern. During the JETS/Aircraft Particle Emissions eXperiment(APEX)-2 and APEX-3 field campaigns, we performed an extensive series of gas phase and particulate emissions measurements of on-wing gas turbine engines. In all, nine different CFM56 style engines (including both CFM56-3B1 and -7B22 models) and seven additional engines (two RB211-535E4-B engines, three AE3007 engines, one PW4158, and one CJ6108A) were studied to evaluate engine-to-engine variability. Specific gas-phase measurements include NO2, NO, and total NOx, HCHO, C2H4, CO, and a range of volatile organic compounds (e.g., benzene, styrene, toluene, naphthalene). A number of broad conclusions can be made based on the gas-phase data set: (1) field measurements of gas-phase emission indices (EIs) are generally consistent with ICAO certification values; (2) speciation of gas phase NOx between NO and NO2 is reproducible for different engine types and favors NO2 at low power (and low fuel flow rate) and NO at high power (high fuel flow rate); (3) emission indices of gas-phase organic compounds and CO decrease rapidly with increasing fuel flow rate; (4) plotting EI-CO or volatile organic compound EIs against fuel flow rate collapses much of the variability between the different engines, with one exception (AE3007); (5) HCHO, ethylene, acetaldehyde, and propene are the most abundant volatile organic compounds present in the exhaust gases that we can detect, independent of engine technology differences. Empirical correlations accurate to within 30% and based on the publicly available engine parameters are presented for estimating EI-NOx and EI-NO2. Engine-to-engine variability, unavailability of combustor input conditions, changing ambient temperatures, and complex reaction dynamics limit the accuracy of global correlations for CO or volatile organic compound EIs.

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