Plant Boiler Enhanced Heat Transfer Tube Contamination Experimental Study

With the development of manufacturing techniques, helically finned tubes are widely used in coal fired boiler. When gas passing through helically finned tube banks, ash would deposit on its surface and affect heat transfer characteristic, so Contamination factor e and thermal effective coefficientΨ are used to represent the effects. It is very important to determine the two parameters because they would affect the inner surface area greatly.Based on the simulating experiment, the quasi-industrial experimental investigation for contamination characteristics of two helically finned tube banks with different transversal and longitudinal pitches were carried out. The quasi-industrial experimental system and investigation method were introduced. Formulas and curves for calculating contamination factor and thermal effective coefficient of the two types of researched helically finned tube banks are obtained according to this investigation, the experiments shows under the same gas velocity, the contamination factor of helically finned tube banks with large transversal and longitudinal pitches is larger than that of the helically finned tube banks with small transversal and longitudinal pitches; while things of thermal effective coefficient is on the contrary. The contamination factor decrease and the thermal effective coefficient increase with the increasement of gas velocity. The order of magnitude of contamination factor obtained from our experiment is smaller than that of the thermal dynamical calculation standard method of the boiler unit. Universal formals to calculate the contamination factor and thermal effective coefficient are obtained.