Experimental study on flow characteristics and pressure drop of gas–coal mixture through venturi

• The gas–solid flow through venturi is studied under high pressure and concentration.
• The flow characteristics of single-phase and gas–solid through venturi are compared.
• The influencing factors of pressure drop for the gas–solid flow are researched.
• The pressure drop models of gas–solid flow are established adopting Farber's method.

The present work details the flow characteristics and pressure drop of the gas–coal mixture through venturi under high pressure and concentration. A series of experiments of both single-phase gas and gas–coal mixture flows through the venturi were carried out, and the distribution of pressure, volumetric loading ratio and superficial gas velocity were obtained and compared. The results show that a sharp decrease in static pressure and volumetric loading ratio was observed inside the venturi. The degree of the decrease of pressure in the diffuser section is the lowest (≤ 20%). When keeping the average throat gas velocity same, the inlet gas velocity of gas–coal mixture flows is lower than that of single-phase gas flow, while the outlet gas velocity is higher. In addition, the variation of throat gas velocity is more remarkable. It may indicate a greater energy transfer with the presence of particles. The pressure drop of the gas–coal mixture increases with the increase of superficial gas velocity, volumetric loading ratio and gas density. Further, the pressure drop models of single-phase gas flow and gas–solid flows through the venturi have been established by adopting the Farbar's approach based on the mathematical regression analysis. The models contribute to predict the pressure drop of venturi with deviations below 25%.

The experimental program was undertaken on the facility of dense phase pneumatic conveying of pulverized coal, where the venturi was installed on the vertical pipeline. The schematic diagram was illustrated in Fig. 1. The whole system consisted of a gas supply system, feeding and receiving vessels, pipelines, a venturi, a measuring system, a filter unit, and a data acquisition system.Figure optionsDownload as PowerPoint slide