Spiral Finned Tube Outside The Thermal State Of Gas-solid Flow Characteristics Of Pda-based Measurement Techniques

The coal is the mainly fuel of boiler in the power plant. There is a large amount of ash after coal's combustion, which results that the heat-exchanger is abraded in the tail flue of the boilers in the power plant, further more, results in a great deal of the safety problems and the economy loss. Engineering practice witnesses that the heat-exchangers used of spiral finned tubes instead of that used of smooth tubes is an effective method lightening abrasion. Some research about the concentration and velocity between two adjacent fins has been observed by researchers of Energy Source and Power Engeering School of Shandong University. On the basis of the former research, this research' purpose is observing the flow characteristic between two adjacent fins under the hot conditions and that of spiral finned tubes with different structures to find out the distribution of velocity, concentration and diameter of two-phase smoke.In order to find out the flow characteristics, gas-solid two-phase flow is a subject that should be studied. A single microcosmic granule's flow state is studied in this research. Between the fins a small ash gets gravitation, resistance Magnus force and Saffman force. Magnus force and Saffman force result that the granule kept away from the pins, which can reduce the opportunity of the granule and fins contact and is theory base of lightening abrasion.The most important parameters that influence the abration are the paticle velocity, concentration and diameter. Besides the theory study, experimental study under the hot condition is necessary, so there is the cold smoke circulating test unit with PDA system set up in the laboratory. With the particle dynamic analyzer (PDA), which is advanced laser instrument made of Dantec Company in Danmark, the paticle velocity, concentration and diameter are measured on 5 representational planes between the pins under the hot condition for the fist time.Experiment research shows that there are disciplinarian distributions about the paticle velocity, concentration, diameter and velocity vector, which are influenced by the temperature,...