| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 107 === Regarding large boiler for power generation, in order to reduce gas discharge temperature of boiler and enhance efficiency of boiler, air preheater would always be installed to serve as a heat recycling device of boiler. The paper uses a set of innovative improvement process to carry out innovative improvement of the structure of air preheater, intending to increase the temperature of cold air outlet. This is because if the temperature of cold air outlet is increased, when air enters the boiler, the preheated energy of boiler can be decreased, and the temperature of hot air inlet can be made to reach the required temperature. In this way, consumption of energy can be decreased.
In the research process of improvement of the rotor structure of air preheater after combining modified TRIZ with computer-aided engineering analysis software, the paper firstly applies modified TRIZ method for screening of some suggested innovative invention rules and their explanations so as to think about the conceptual design way of structural improvement and produce a new structure for air preheater. Then the paper uses this new air preheater structure. After Fluent software is used to simulate distribution of its thermal and flow fields, the paper proves that the temperature of the thermal and flow fields of this new air preheater structure is improved.
The air preheater project of the paper uses modified TRIZ invention method to step by step design improvement of air preheater structure. First of all, the paper uses modified TRIZ method to find “a. Provide transition from a homogeneous structure of an object or outside environment (outside action) to a heterogeneous structure” under the invention rule “ 3. local quality”. Thus, the paper proposes changing the single-layered cylindrical rotor structure to be double-layered cylindrical rotor structure so as to increase the contact area between its cold air and hot air and increase the temperature of cold air outlet.
Furthermore, in order to increase the contact area between the cold air and hot air of the single-layered cylindrical rotor structure, the paper uses TRIZ invention rules again to find “c. Place each part of the object under conditions most favorable for its operationm” under “3. local quality”. Hence, it is determined to use hexagonal column-shaped rotor to replace cylindrical rotor. This is because the contact area between the cold air and hot air of hexagonal column-shaped rotor is greater than that of cylindrical rotor. Finally, the paper once again uses the same modified TRIZ invention rule to find the double-layered structure of the first improvement case. Therefore, the paper proposes again using the innovative air preheater structure with double-layered hexagonal column-shaped rotor structure.
Lastly, the paper uses the analysis software Fluent that can calculate thermal and flow fields to analyze the new temperature fields of the hot air inlet and outlet as well as the cold air inlet and outlet of the various air preheater structures produced by the above modified TRIZ method. The simulation results can prove that the innovative air preheater structure with double-layered hexagonal column-shaped rotor proposed by the paper can increase the temperature of cold air outlet, and further decrease the energy required for preheating of boiler.
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