Methods of mixing impeller sensing

A method of monitoring a flow behaviour of mixed components, comprising:

• rotating a mixing impeller at a first speed N1 in a mixing vessel accommodating the components to be mixed;
• determining a first quantity
• P
• 1
• N
• 1
• 3
• at the first speed N1, wherein N1 is the speed at which the mixing impeller rotates and P1 is the power required to rotate the mixing impeller at the first speed N1;
• decreasing the speed of the mixing impeller to a speed N2;
• determining a second quantity
• P
• 2
• N
• 2
• 3
• at the second speed N2, wherein N2 is the speed at which the mixing impeller rotates and P2 is the power required to rotate the mixing impeller at the second speed N2;
• comparing the first quantity
• P
• 1
• N
• 1
• 3
• and the second quantity
• P
• 2
• N
• 2
• 3
• and detecting whether the difference between the first and second quantities is within a specified range to determine whether the flow of the components in the mixing vessel is a turbulent flow;
• determining the density ρ of the mixed components based on at least one speed Ni for which the flow is determined to be turbulent by the following formula:
• ρ
• =
• P
• i
• N
• P
• ,
• constant
• ⁢
• N
• i
• 3
• ⁢
• D
• 5
• wherein ρ is the density, P1 is the power required to turn the mixing impeller at the speed Ni, NP,constant is the Power number for a used mixing system configuration, Ni is the speed at which the mixing impeller rotates and D is the diameter of the mixing impeller;
• further decreasing the speed of the mixing impeller;
• determining the Power number NP,variable for at least one detected speed Nj at which the flow is determined to be non-turbulent by the following formula:
• N
• P
• ,
• variable
• =
• P
• j
• ρ
• ⁢
• ⁢
• N
• j
• 3
• ⁢
• D
• 5
• wherein Pj is the power required to rotate the mixing impeller at the speed Nj, ρ is the density previously determined based on NP,constant, Nj is the speed at which the mixing impeller rotates, and D is the diameter of the mixing impeller;
• and
• determining the dynamic viscosity μ of the mixed components by the following formula:
• μ
• =
• ρ
• 2
• ⁢
• N
• j
• 5
• ⁢
• D
• 6
• x
• T
• ⁢
• P
• j
• wherein ρ is the calculated density, Nj is the speed at which the mixing impeller rotates, D is the diameter of the mixing impeller, Pj is the power required to rotate the mixing impeller at the speed Nj and xT corresponds to a specified relationship between the Reynolds number for the used mixing system configuration and the determined Power number NP,variable.