Experimental investigation on flow characteristics of fluidized bed cone valve

The cone valve is a kind of excellent ash-control valve,whose regulation performance is of great importance to the stable operation of external heat exchanger.At present,the research on the flow characteristics of cone valves is still in its infancy stage.Most industrial designs and ultilization of cone valve are based on experience,lack of reliable theoretical basis.A small fluidized bed experimental bench was designed and built to understand the relationship between the flow rate and the valve opening x,flow rate u,initial height of bed material h and nominal valve size D.To keep the stability of bed inventory and bed pressure,the realtionship of feeder flow and frequency is calibrated,the feeder frequency is adjusted to keep the dynamic equilibrium of feeder flow and valve flow.The particle distribution,bulk density and true density is obtained with measurement.The experiment result shows that with the increase of valve opening,the flow rate increases linearly to the saturation point and then maintains constant,which matches well with previous study and the linearly relationship between the valve flow area and valve opening.The inner particle flow of cone valve is analysed to give an explanation to the saturation point.The cone valve is considered as orifice system,and it is found that the flow rate is determined by valve feeding flow and processing flow.The fluidized velocity has little influence on the flow rate comparing to other influence factors,the flow rate increases about 2% when fluizied velocity increases from 2.5 u mf to 5 u mf,and the bed pressure does not change with the fluidized velocity.The initial height of bed material has a positive effect on the bed pressure,the saturation flow and full openning have a slight increase with the increase of the initial height of bed material.The relationship between saturation flow and nominal valve size presents a power of 2.1 and the discharge variation of valve flow is similar under different nominal valve sizes,the experimental results could be used in the industrial design and operation of cone valve.