Patent ID: 8512513

Claim:
A method of controlling the height of a material column in a vessel upstream of a pump comprising: a) material is conveyed into an upper portion of the vessel; b) electrical signals are provided on the basis of the presence of material at predetermined measuring levels of the vessel by using a first sensor set disposed at a first measuring level at an upper portion of the vessel and a second sensor set disposed at a second measuring level at a lower portion of the vessel; and c) material is discharged at a controlled flow speed from the lower portion of the vessel by the pump, wherein the electrical signals provided in step (b) are used to infer weighting factors of measuring level presence functions describing the presence of material at the respective measuring level, with the weighing factors having a range of values including a value respectively for full presence and absence of material and intermediate values in between, wherein the weighting factors of measuring level presence functions are corrected to neglect the effect of bridging of material in the vessel, wherein the material comprises medium consistency pulp stock, and wherein in step (c) the flow speed is controlled on the basis of the weighting factors of the measuring level presence functions.