An Indirectly Fired Gas Turbine Cogeneration Plant Utilizing Sawdust as a Fuel

Author(s):  
R. L. Evans ◽  
M. S. Sinclair ◽  
G. A. Constable ◽  
T. Halewood

A technical and economic assessment of an indirectly fired gas turbine cogeneration system is presented. The plant is designed for use in a sawmill, burning sawdust to generate both electricity and process heat to dry the lumber. After being dried, the sawdust is burned in a specially designed combustor which incorporates both radiant and convective heat transfer sections to generate a supply of air heated to 760 C (1400). This hot air drives the gas turbine and then the exhaust stream is utilized as a heat source for drying lumber in the dry-kilns. A materials and energy balance is presented which shows that there is more than enough sawdust available in a typical sawmill to supply all of the process heat requirements and to generate most of the electricity required to operate the mill machinery. This site-specific feasibility study indicates that an indirectly-fired gas turbine cogeneration system should be both technically and economically viable for application in a sawmill producing dried softwood lumber.

Author(s):  
Farshid Zabihian ◽  
Alan S. Fung ◽  
Fabio Schuler

Gas turbine-based power plants generate a significant portion of world’s electricity. This paper presents the modeling of a gas turbine-based cogeneration cycle. One of the reasons for the relatively low efficiency of a single gas turbine cycle is the waste of high-grade energy at its exhaust stream. In order to recover this wasted energy, steam and/or hot water can be cogenerated to improve the cycle efficiency. In this work, a cogeneration power plant is introduced to use this wasted energy to produce superheated steam for industrial processes. The cogeneration system model was developed based on the data from the Whitby cogeneration power plant in ASPEN PLUS®. The model was validated against the operational data of the existing power plant. The electrical and total (both electrical and thermal) efficiencies were around 40% and 70% (LHV), respectively. It is shown that cogenerating electricity and steam not only significantly improve the general efficiency of the cycle but it can also recover the output and efficiency losses of the gas turbine as a result of high ambient temperature by generating more superheated steam. Furthermore, this work shows that the model could capture the operation of the systems with an acceptable accuracy.


Author(s):  
Jose´ C. F. Teixeira ◽  
Senhorinha F. C. F. Teixeira ◽  
Aˆngela M. E. Silva

Amongst the various alternatives for the combined production of heat and power, the systems based on a gas turbine are becoming increasingly attractive. In addition to the high thermal efficiency, they can also operate on a wide variety of fuels. The basic configuration of a simple cogeneration system consisting of a gas turbine and a heat recovery steam generator has been used to illustrate the application of nonlinear optimization numerical methods as a tool to evaluate and optimize complex energy systems. The problem was formulated as the minimization of costs as the objective function, subject to the constraints imposed by the physical and thermodynamic quantities. Two numerical nonlinear optimization methods with constraints have been tested using a Fortran code and the MATLAB® environment. The model has been evaluated on a real cogeneration plant consisting of a gas turbine heat recovery system of a local textile factory.


Author(s):  
R. L. Evans

This paper describes two gas turbine related research projects in the department of Mechanical Engineering at the University of British Columbia. Of the two projects described, one involves fundamental turbomachinery research while the second is a more applied project concerned with gas turbine based cogeneration systems in process industries. In the fundamental research area, both an experimental and computational study of unsteady boundary layer development on turbomachinery blading is described. The applied research program involves an engineering and economic assessment of a gas turbine based cogeneration system for sawmills. The system is designed to use wood-waste generated during the saw-milling process as a source of heat for an indirectly fired gas turbine. Studies to date indicate that such a system could result in many sawmills becoming completely energy self-sufficient.


Author(s):  
B Law ◽  
B. V. Reddy

Combined cycle power plants with a gas turbine topping cycle and a steam turbine bottoming cycle are widely used due to their high efficiencies. Combined cycle cogeneration has the possibility to produce power and process heat more efficiently, leading to higher performance and reduced green house gas emissions. The objective of the present work is to analyze and simulate a natural gas fired combined cycle cogeneration unit with multiple process heaters and to investigate 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. It is also identified that extracting process steam at lower pressures improves the power generation and cogeneration efficiencies. The process heat load influences combined cycle efficiency and combined cycle cogeneration efficiency in opposite ways. It is also observed that using multiple process heaters with different process steam pressures, rather than a single process heater, improves the combined cycle cogeneration plant efficiency.


Author(s):  
B. Law ◽  
B. V. Reddy

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.


Author(s):  
I. S. Ondryas

This paper describes the engineering effort involved in the selection of the topping cogeneration cycle for an industrial cogeneration plant. Fuel profitability of a cogeneration plant is defined and analyzed, and used as a tool for the selection of the cogeneration cycle. The conceptual design of a gas turbine cogeneration plant is described, which includes selection of a gas turbine generator and other major plant components, equipment sizing and the typical control system layout. The paper provides tools to the industrial plant manager/engineer for the selection of the most profitable alternative of the cogeneration system.


Author(s):  
Steve Ingistov ◽  
Michael Milos ◽  
Rakesh K. Bhargava

A suitable inlet air filter system is required for a gas turbine, depending on installation site and its environmental conditions, to minimize contaminants entering the compressor section in order to maintain gas turbine performance. This paper describes evolution of inlet air filter systems utilized at the 420 MW Watson Cogeneration Plant consisting of four GE 7EA gas turbines since commissioning of the plant in November 1987. Changes to the inlet air filtration system became necessary due to system limitations, a desire to reduce operational and maintenance costs, and enhance overall plant performance. Based on approximately 2 years of operational data with the latest filtration system combined with other operational experiences of more than 25 years, it is shown that implementation of the high efficiency particulate air filter system provides reduced number of crank washes, gas turbine performance improvement and significant economic benefits compared to the traditional synthetic media type filters. Reasons for improved gas turbine performance and associated economic benefits, observed via actual operational data, with use of the latest filter system are discussed in this paper.


Author(s):  
Maurizio De Lucia ◽  
Carlo Lanfranchi ◽  
Antonio Matucci

A cogeneration plant with a small gas turbine was installed in a pharmaceutical factory and instrumented for acquiring all the values necessary to appraise both its energetic and cost advantages. The plant was designed and built as a demonstrative project under a program for energy use improvement in industry, partially financed by the European Union. The system comprises as its main components: 1) a gas turbine cogeneration plant for production of power and thermal energy under the form of hot water, superheated water, and steam; 2) a two-stage absorption unit, fueled by the steam produced in the cogeneration plant, for production of cooling thermal energy. The plant was provided with an automatized control system for the acquisition of plant operating parameters. The large amount of data thus provided made it possible to compare the new plant, under actual operating conditions, with the previously existing cooling power station with compression units, and with a traditional power plant. This comparative analysis was based on measurements of the plant operating parameters over nine months, and made it possible to compare actual plant performance with that expected and ISO values. The analysis results reveal that gas turbine performance is greatly affected by part-load as well as ambient temperature conditions. Two-stage absorber performance, moreover, turned out to decrease sharply and more than expected in off-design operating conditions.


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