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This research aims to develop a method to evaluate the deterioration of the tube material within a boiler, in order to reduce the failure of it. In this thesis, natural frequency measurement method and ultrasonic attenuation method are mainly applied, and it has reached to a conclusion that the ultrasonic attenuation method is more reliable. Traditionally, the inspectors used the ultrasonic thickness measurement machine to evaluate the thickness and track the condition of a boiler. However, besides the thickness, the inspectors could not have clear understanding of the material and situation within a boiler. To improve the inspection effectiveness, the researcher measures the natural frequencies of the tube material in the new and old boilers by using natural frequency measurement. They found that the used tube material has been altered due to the difference between the natural frequencies. The ultrasonic attenuation conditions of the tubes are also evaluated in this thesis. The echoes of the ultrasound propagating through the thickness of the tube can be analyzed by relative comparison and absolute comparison, respectively. The relative comparison compares the echoes of the multiple back reflections of the ultrasound between the tubes of old and new boilers. In addition, the absolute comparison analyzes the amplitude of the echoes of the ultrasonic multiple back reflection to calculate the ultrasonic attenuation of the tube. Besides the two major techniques, the material analysis, metallurgical analysis, internally scale analysis and mechanical property evaluation are also applied in this thesis to help developing a method to evaluate the deterioration of the tube material within a boiler. This research demonstrates that the ultrasonic attenuation measuring methods can offer reliable results to evaluate the quality of the boiler.

In this research a modified commercial boiler,which burns diesel oil,is used to study the combustion characterisics and the pollution of the exhausting products under various operating conditions.The controlling ranges of the various experimental parameters include equivalence ratio from 0.8to1.1,swirl number 0 and 0.6, the flue rate of the recirculated flue gas from 0% to 12%, and jet spray angle 80. The effect of the above various operating conditions on the combustion characteristics and the formation of pollutants are studied in this research. A photographic technology is used to study the combustion behaviors of the flame under various operating condition. Flame structures display that when the flow rate of the recirculated flue gas increase, the flame color in primary combustion zone will change gradually from high temperature white-yellow flame to low temperature orange-red flame. At plate angle 0 and 45, the primary combustion zone with plate angle 45 occurs near burner so that we cannot see too much white-yellow zone from quartz window. The flame outside of the primary combustion region exhibits the red color which is due to the radition of CO2 and water vapor. In addition, when the strength of the swirl increases the contour of the flame will change gradually from smooth shape to strongly distortion.

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Thesis (M.E.)--University of Wisconsin--Madison, 1914. / Typescript. Includes index. eContent provider-neutral record in process. Description based on print version record.

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The aim of this diploma thesis is to design a gas boiler for blast furnace gas combustion. At the beginning is performed stoichiometry of the used fuel to determine the optimal amount of combustion air and the actual amount of flue gas. Subsequently is determined the overall efficiency, together with heat and steam power of the boiler. The main part of the thesis is focused on the design of the combustion chamber and the dimensioning of heat exchange surfaces. At the end of the thesis are performed hydraulic and aerodynamic calculations to determine the pressure loss on the side of the working medium and flue gas. Drawing documentation can be found in attachments.

The main aim of this diploma thesis is to proceed a design of grate steam boiler for grain straw combustion with 15,6 MJ/kg of fuel efficiency. Steam power of boiler is 15 t/h, pressure of overheated steam is 5 MPa, temperature of overheated steam is 415 °C and temperature of inlet water is 125 °C. The estimation is based on proportioning of draughts and segments of boiler and on thermal computation. Verification of divergence of thermal balance is going to constate accuracy of boiler design.

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