Study On The Characteristics Of Water Jet Under High Back Pressure And High Temperature

The third generation coal gasification technology is widely applied,due to its advantages of stable performance and high efficiency.In order to improve the high pressure dry pulverized coal gasification upstream synthesis gas chill technology,water chilling becomes the first choice of the development of the technology because of the potential fast,low cost and stable performance.The influence of water jet parameters such as water temperature,jet pressure and flow on the shape,flow coefficient,expansion angle,distance and atomization particle size of water jet under high temperature and high back pressure conditions is also lack of research.And related research work has important theoretical and practical value.Flow coefficient is an important design parameter determining nozzle performance.This article selects the typical cone inlet plain nozzle to carry experiment,study the inner nozzle flow state and flow coefficient on the different back pressure,temperature,injection pressure,and flow.And then Re number,cavity number,degree of superheat is analyzed on the basis of the influence of flow coefficient.The results show that the greater the back pressure the less prone to cavitation;Increase the degree of superheat and injection pressure can increase the number of cavitation,but increase the degree of superheat is more apparent,can even produce “super cavitation”,When cavitation occurs,the discharge coefficient of nozzle will drop sharply,after can remain the same.High temperature water jet structure under high back pressure for the actual chilling application has important value.This paper use clever line design,guarantee the transparency of the environment of pressure tank,so as to obtain a clear image.To image analysis are: when jet at high temperature,due to the heat transfer with air the jet will appear oval in the process of development;In the outer layer of the jet will appear blue aperture;The higher the back pressure,jet atomization effect is bad;The higher the temperature,the more powerful jet expansion,the better the atomization effect.Flashing jet due to its rapid evaporation can effectively improve the jet atomization effect.This article through the flash method to obtain the images of the flashing jet,then the image is analyzed.At the same time also we use laser particle size analyzer to measure the atomized particle size.The experimental results show that the outline of the flashing jet in nozzle exit would be bent;Jet expansion angle increases with the rising of temperature,the jet distance,the SMD decreases with the increase of temperature.When the flashing jet steam flow rate is too high,the laser particle size analyzer can not measure the SMD.