Abstract: The study investigates the use of an isokinetic sampling probe to measure flow velocity and local solids concentration in cyclones, focusing on high mass concentration gas-solid suspensions and vortex flows. The probe facilitates chemical and grain size analyses without calibration, characterizing inlet conditions and vortex flow, with efficiency quantified through solids concentration measurements.

Introduction: Traditional methods for measuring gas-solid suspension flows are costly and unsuitable for industrial scales. This study introduces an isokinetic sampling probe that evaluates local concentration and suspension velocity simultaneously without calibration. Details on the probe's design and measurement procedure are provided.

Measurement Method: The method isolates gas-solid flow without disturbing the main stream, ensuring isokinetism. The probe includes a tip, filter element, nozzle, and jet vacuum pump. The procedure involves balancing the probe, extracting the flow, and measuring material and gas flow rates to determine local concentration and suspension velocity.

Measurements in Cyclone: The study characterizes inlet conditions and vortex in a cyclone with an 835 mm diameter using silica material. Inlet conditions show a concentration gradient due to pipe geometry. Vortex characterization reveals material circulation confined to the cyclone's bottom and direct escape from inlet to outlet. Efficiency curves show higher inlet solids concentration reduces material in suspension subjected to centrifugation.

Conclusion: The isokinetic sampling probe effectively measures local concentration and suspension velocity in cyclones. While less accurate than pressure probe methods for velocity, it provides valuable concentration data and can be used in hot conditions with precautions. Future on-site measurements in large cyclones at high temperatures are planned.

Specifications and Procedures: The document emphasizes selecting the appropriate tip for a microcyclone to maintain inlet velocity between 15 and 30 m/s for optimal efficiency. Microcyclone dimensions and separating unit depend on measuring conditions such as suspension velocity, solids concentration, gas temperature, and the nature of the gas and material.

Conclusions: The isokinetic sampling probe is effective for measuring concentrations up to 2 kg of material per kg of gas without prior calibration. The FCB isokinetic sampling probe demonstrates the suspension-type flow structure in a cyclone. Observations include non-uniform solids concentration and grain size discrimination with inlet height, direct material escape from inlet to outlet, and a dense phase of material moving down the wall in a spiral flux. These phenomena are quantifiable from the efficiency curve, and samples allow for grain size or chemical analysis.

List of Symbols: The document provides a list of symbols used, including local solids concentration (C), cyclone inlet mean concentration (C0), cyclone diameter (D), cyclone inlet vertical position (h), inlet height (H), external and internal flow static pressures (P1, P2), radial position (r), tangential velocity (Vt), and maximum tangential velocity in pure air (Vt max).

References: The document cites various studies and theses related to powder technology and fluidized bed technology, indicating a well-researched foundation for the findings presented.

Keywords: Isokinetic sampling probe, concentration measurement, air-solid flow, cyclone.