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|Title: ||Design of heat exchanger for a biomass externally fired gas turbine of 30-100kw|
|Authors: ||Olwa, Joseph|
|Keywords: ||Gas turbine|
|Issue Date: ||7-Dec-2008 |
|Abstract: ||The need for affordable, environmentally clean and suitable fuel incited the idea of using biomass for electricity. Biomass is first gasified into fuel gas before it is used in turbine engines, which is
usable in turbine engines. Biomass when used as fuel has probrems of ash particles and alkali salts deposition on moving parts of the turbines engine and heat exchanger conduits. This results in to fouling and clogging of conduits and turbines blades with consequent development of vibrations.
The difficulty of cleaning products of combustion from the gasifier for combustion in the turbine prompted a need for integrating a heat exchanger unit to allow utilization of clean working fluid
(air). In the externally Fired Gas Turbine (EFGT) system compressed air is heated through a heat exchanger by using fired biomass fuel gas and it is expanded in the turbine engine. The heat exchanger became a primary unit in EFGT system since system efficiecy bears heavily on its performance and what was of concern was the design of the heat exchanger that would operate a turbine of about 30-l00kw power output. In this case the heat exchanger would allow for better way to handle the clogging and fouling substances from the gasification process, and at the same
time utilization of a clean working fluid. The general objective was to design and discuss the accuracy of design parameters for the heat exchanger that would be integrated into the EFGT system.
This approach involved :
a) Developing a mathematical model for the EFGT system in comporting a gasifier unit
b) Carry out a simulation of the system modeiled.
c) Designing a compatible heat exchanger unit for the proposed system.
d) Carrying out specification for the exchanger and request for a quotation for construction cost from a vendor.
The available heat exchangers off-shelve could not be adapted to the operating conditions (i.e. high temperature operations) of the new system, which prompted the idea for a new design. The heat exchanger was designed for thermal load of about 488 kw power, operating at maximum temperature 8150 c. Due to fouling and variation in heat transfer coefficients, there is some considerable uncertainty in the number of heat exchanger design calculations. The major of unceftainty parameters are fouling factors and heat transfer coefficient values. This requires separate experimentation especially to have good of fouling factor. This research therefore was carried out in order to develop one of the units required for the EFGT system, viz the heat exchanger, which could not be found in the market. Further work recommended was to determine the nature of fouling by carrying out experiments on a laboratory
sized model in order to determine the heat transfer coefficient in the heat exchanger fluid streams and make a good design. This will be done under a different research topic.|
|Appears in Collections:||Theses & Dissertations (Tech)|
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