Methods of mixing impeller sensing

Patent metadata

Field	Value
Publication number	US-10112162-B2
Application number	US-201615010317-A
Country	US
Kind code	B2
Filing date	Jan 29, 2016
Priority date	Jan 29, 2016
Publication date	Oct 30, 2018
Grant date	Oct 30, 2018

Abstract

A method is provided for monitoring a flow behavior of mixed components without requiring additional instrumentation or sampling. The method is carried out by determining ratios of the power required to rotate a mixing impeller at different rotational speeds and then comparing the ratios. Characteristics about the mixed components are determined based on differences between the ratios.

First claim

What is claimed is:

1. A method of monitoring a flow behaviour of mixed components, comprising:
rotating a mixing impeller at a first speed N 1 in a mixing vessel accommodating the components to be mixed;
determining a first quantity

P
1

N
1
3

at the first speed N 1 , wherein N 1 is the speed at which the mixing impeller rotates and P 1 is the power required to rotate the mixing impeller at the first speed N 1 ;
decreasing the speed of the mixing impeller to a speed N 2 ;
determining a second quantity

P
2

N
2
3

at the second speed N 2 , wherein N 2 is the speed at which the mixing impeller rotates and P 2 is the power required to rotate the mixing impeller at the second speed N 2 ;
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 N i 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, P 1 is the power required to turn the mixing impeller at the speed N i , N P,constant is the Power number for a used mixing system configuration, N i 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 N P,variable for at least one detected speed N j 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 P j is the power required to rotate the mixing impeller at the speed N j , ρ is the density previously determined based on N P,constant , N j 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, N j is the speed at which the mixing impeller rotates, D is the diameter of the mixing impeller, P j is the power required to rotate the mixing impeller at the speed N j and x T corresponds to a specified relationship between the Reynolds number for the used mixing system configuration and the determined Power number N P,variable .

2. The method of claim 1 , wherein the current speed N i is iteratively reduced to a speed N i+1 and the quantity

P

i
+
1

N

i
+
1

3

is iteratively determined at the respective speed N i+1 as long as a turbulent flow is determined when comparing the determined quantity

P

i
+
1

N

i
+
1

3

with the previously determined quantity

P
i

N
i
3

.

3. The method of claim 1 , wherein the average density ρ is calculated based on plural densities ρ i determined for plural speeds N i for which the flow is determined to be turbulent.

4. The method of claim 1 , wherein the speed N i of the mixing impeller is reduced in steps and the speed N i is maintained for a specified time t stab so that a flow pattern is able to stabilize at each speed.

5. The method of claim 1 , further comprising the step of outputting the determined density ρ and the dynamic viscosity μ.

Assignees

• Sartorius Stedim Biotech Gmbh
• Cutting Jonathan E

Inventors

• Boettcher Lars
• Cutting Jonathan E
• West Sharon D
• Oschwald Martin

Classifications

• G01N2011/0026

  Investigating specific flow properties of non-Newtonian fluids · CPC title

• B01F15/00285 Primary

  Operations & Transport · mapped topic

• B01F7/18

  Operations & Transport · mapped topic

• B01F15/00201

  Operations & Transport · mapped topic

• G01N2011/0006

  Calibrating, controlling or cleaning viscometers · CPC title