الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
This thesis presents an experimental study of cleaning heat transfer surfaces of a fire tube steam boiler pipes by using hydro blasting within pressure range from 10 to 35 bar in the presence of 1 mm diameter sand granules ejection in addition to devising a new way to evaluate the performance of the cleaning process.
Firstly the following factors were examined vs. the depth of cleaning (jet pressure, cleaning time, water spray diameter, standoff distance and the angle of the sprayer on the surface of the sample).
Secondly, the design and implementation of a new method to evaluate the performance of the cleaning process, a device to measure the heat transfer rate through the surfaces of samples that have been cleaned which means a new addition in studying the cleaning process because the previous studies which examined the impact of different factors on the depth of cleaning did not address the effect of cleaning on thermal properties of heat transfer surfaces due to the difference of requirements between the samples used in cleaning process and those used in the thermal properties determination.
The results of the practical model used cleaning study led to more detailed understanding of sediment layers due to the use of low pressure which led to gradual removal of these layers. The sediments formed on the water side of fire tube boiler are composed from three layers; the upper layer of thickness up to 1 mm, the main component of this layer are the turbidity molecules, which can be avoided by using 5μm permeable fiber filters instead of traditional sand filters ,the use of pressure starting from 10 bar and without sand grains ejection penetrated this layer doing gaps of nearly 20mm diameter; The middle layer which is mainly composed of silicate has thickness up to 0.5 mm is more stable and was removed by using pressure of 30 bar with sand grains ejection, , and the bottom layer thickness of about 0.1 mm and adjacent to the surface of the pipes and caused by iron oxide, this layer was removed using the same conditions used for the removal of the middle layer. The results of cleaning experiments indicated that the pressure of the cleaning system is dependent on spray diameter.
The pressure of the cleaning system increased from 15 bar to 35 bar by reducing the diameter of the water spray from 4 mm to 3 mm. The results showed that the pressure is the most effective factor on the depth of the cleaning and ejection of the sand particles of 1 mm diameter increased the ability of the cleaning system to remove the sediment as a result of increasing the collision force caused by the mass of sand grains without causing the erosion of samples surfaces. In addition to that, the new measuring method results showed that the increase in heat transfer rate after cleaning was about 17 % and the device was highly sensitive to about 300 Joule per each degree celsius of temperature raise.