Online monitoring and characterization of dense phase pneumatically conveyed coal particles on a pilot gasifier by electrostatic-capacitance-integrated instrumentation system

The transportation of pulverized coal in gasification system needs to be carefully monitored and regulated with respect to the operation stability, gas quality and energy efficiency. In this paper, an integrated instrumentation system is developed to continuously monitor the pulverized coal flow within a 30 mm horizontal pneumatic pipe on a pilot coal gasifier at low pressure. The instrumentation system calculates the mass flow rate of pulverized coal by measuring the particle mean velocity with two ring-shaped electrostatic sensors and particle concentration with a helical capacitance sensor. The system is calibrated and optimized before the field experiments, especially the optimal structure of the helical capacitance sensor with a homogeneous sensitivity distribution is achieved by static tests to minimize the influence of the uneven particle concentration distribution on the particle concentration measurement accuracy. Experiments are carried out under various operation conditions to characterize the flow of pulverized coal particles using the integrated instrumentation system. The regulating effects of the operation parameters of the pneumatic conveying system (the angle valve opening, the fluidized gas and supplement gas flow rates, the pressure within the feeding tank) on the particle velocity, concentration and mass flow rate are experimentally studied. Results demonstrate that the integrated instrumentation system can effectively monitor the dense phase pneumatically conveyed coal particles flow on the pilot coal gasifier. Both the angle valve and the pressure within the feeding tank are effective to control the mass flow rate via regulating the particle concentration. The supplement gas can regulate the particle velocity and concentration simultaneously.