Powder flow measurement

Claim 3

A method according to claim 1, wherein the disturbances are variations in the concentration of the particulate material in said fluid.

Claim 4

A method according to claim 2, including the step of measuring the mass loading of the particulate material per unit length of the path for flow of the material.

Claim 5

A method according to claim 1 wherein the particulate material is a powdered solid and said path for flow of the particulate material is provided by a pneumatic conveyor.

Claim 6

Apparatus for measuring the flow of a particulate material conveyed hydrodynamically by a flowing fluid along a give path, said apparatus comprising a first sensing element operative to generate a first signal corresponding to small random changes in the quantity of the particulate material flowing past a first point in said given path, a second sensing element operative to generate a second signal corresponding to small random changes in the quantity of the particulate material flowing past a second point in said given path, said first and second points being separated by a known distance along said path, and means for ascertaining that value of the time delay between said first and second signals for which the cross-correlation function of said first and second signals has its maximum value.

Claim 7

Apparatus for measuring the flow of a particulate material conveyed hydrodynamically by a flowing fluid along a give path, said apparatus comprising a first sensing element operative to generate a first signal corresponding to small random changes in the quantity of the particulate material flowing past a first point in said given path, a second sensing element operative to generate a second signal corresponding to small random changes in the quantity of the particulate material flowing past a second point in said given path, said first and second points being separated by a known distance along said path, and means for ascertaining that value of the time delay between said first and second signals for which the cross-correlation function of said first and second signals has its maximum value.

Claim 8

Apparatus according to claim 5, wherein said path is provided by a pneumatic conveyor.

Claim 9

Apparatus according to claim 5, wherein each of said sensing elements includes an electrode, disposed so that variations in the quantity of said material flowing past the electrode causes corresponding changes in the capacitance of the electrode.

Claim 10

Apparatus according to claim 7, wherein said electrodes form part of a wall of a pneumatic conveyor.

Claim 11

Apparatus according to claim 5, including means for measuring the mass loading of material per unit length of said path.

Claim 12

Apparatus for measuring the flow of a particulate material conveyed hydrodynamically by a flowing fluid along a given path, said apparatus comprising a first electrode disposed at a first point in said given path so that small random changes in the quantity of the particulate material flowing past said first point cause corresponding changes in the capacitance of the first electrode, a second electrode disposed at a second point in said given path so that small random changes in the quantity of the particulate material flowing past said second pOint cause corresponding changes in the capacitance of the second electrode, said first and second points being separated by a known distance along said path, a first transducer means for producing a first electrical signal related to the changes in capacitance of said first electrode, a second transducer means for producing a second electrical signal related to the changes in capacitance of said second electrode, and means for ascertaining that value of the time delay between first and second signals for which the cross-correlation function of said first and second signals has its maximum value.

Claim 13

Apparatus for measuring the flow of a particulate material conveyed hydrodynamically by a flowing fluid along a given path, said apparatus comprising a first electrode disposed at a first point in said given path so that small random changes in the quantity of the particulate material flowing past said first point cause corresponding changes in the capacitance of the first electrode, a second electrode disposed at a second point in said given path so that small random changes in the quantity of the particulate material flowing past said second pOint cause corresponding changes in the capacitance of the second electrode, said first and second points being separated by a known distance along said path, a first transducer means for producing a first electrical signal related to the changes in capacitance of said first electrode, a second transducer means for producing a second electrical signal related to the changes in capacitance of said second electrode, and means for ascertaining that value of the time delay between first and second signals for which the cross-correlation function of said first and second signals has its maximum value.

Claim 14

Apparatus according to claim 9, wherein said means for measuring the mass loading per unit length of said path comprises a source of radiation situated on one side of said path and detecting means situated on the opposite side of said path.