Abstract: A method of determination and monitoring of a fuel mass stream supplied for partial oxidation of fine-grain up to pulverized fuels to a gasifier includes determining a total density .rho..sub.tot of a fuel stream conveyed by a fluidizing gas in an outlet conduit of a fuel bin with the aid of a radiometric density measurement, subsequently determining a total volume stream q.sub.v.sbsb.tot of said stream by a differential pressure measurement, determining a difference between volume streams of a fluidizing gas supplied to the fuel bin q.sub.v.sbsb.gas supplied and discharged from the latter q.sub.v.sbsb.gas discharged by differential pressure measurements, determining a volume stream of the fluidizing gas q.sub.v.sbsb.gas fuel in accordance with the following equation:q.sub.v.sbsb.gas =(q.sub.v.sbsb.gas supplied -q.sub.v.sbsb.gas discharged)-q'.sub.v.sbsb.gas',determining the volume stream of the gas part q'.sub.v.sbsb.gas in accordance with the following equation: ##EQU1## wherein .rho..sub.

Abstract: A Venturi tube which is especially suited for the differential pressure measurement of flowing gas/particulate material media with high dust loading at temperatures exceeding 100.degree. C. and at elevated pressures includes a pressure-resistant metallic jacket and an inner lining of wear-resistant porous material which is accommodated in the jacket and bounds a flow-through passage with the Venturi configuration. Respective annular chambers are situated at the inlet region and at the smallest-diameter region of the flow-through passage, there annular chambers being separated from the flow-through passage by respective layers of wear-resistant porous material and being connected by respective pulse conduit with a differential pressure measuring device.