Method and device for measuring fat in milk

Patent metadata

Field	Value
Publication number	US-11579060-B2
Application number	US-201816956940-A
Country	US
Kind code	B2
Filing date	Dec 10, 2018
Priority date	Dec 22, 2017
Publication date	Feb 14, 2023
Grant date	Feb 14, 2023

Abstract

Disclosed is a method for determining of fat content of milk having variable solids fractions and flowing with variable gas content in a pipeline. The method includes ascertaining a velocity of sound and an average density value for the milk based on eigenfrequencies of at least two bending oscillation wanted modes of measuring tubes of a densimeter arranged in the pipeline. The method further includes ascertaining a static pressure in the pipeline; a gas volume fraction based on the velocity of sound; the average density; the pressure; a density of the milk without gas content based on the average density and the gas volume fraction; and a permittivity of the milk based on a propagation velocity and/or an absorption of microwaves in the milk. The fat fraction is calculated based on the density of the milk without gas content and on the effective permittivity.

First claim

The invention claimed is:

1. A method for determining a fat content of milk, wherein the milk has variable solids fractions and flows with a variable gas content in a pipeline, the method comprising:
arranging a densimeter in the pipeline and flowing the milk through the densimeter;
determining a first eigenfrequency of a first bending oscillation mode of the densimeter and a second eigenfrequency of a second bending oscillation mode of the densimeter;
calculating a velocity of sound in the milk and calculating an average density for the milk based on the first and second eigenfrequencies;
measuring a static pressure in the pipeline using a pressure sensor connected to the pipeline;
calculating a gas volume fraction of the milk based on the velocity of sound in the milk, the average density, and the static pressure;
calculating a density of the milk without gas content based on the average density and based on the gas volume fraction;
measuring a propagation velocity and/or an absorption of microwaves in the milk using a microwave sensor arranged in the pipeline and calculating an effective permittivity of the milk from the propagation velocity and/or the absorption; and
calculating a fat fraction of the milk based on the density of the milk without gas content and on the effective permittivity of the milk.

2. The method as claimed in claim 1 , further comprising:
modeling the milk as a three component system of fat, water, and fat-free solids.

3. The method as claimed in claim 2 , wherein the fat-free solids include proteins and carbohydrates.

4. The method as claimed in claim 3 , further comprising:
calculating a concentration of each of the three components of fat, water, and fat-free solids:
modeling the density of the milk without gas content as a function of the concentration of each of the components of fat, water, and fat-free solids using density values of the respective component as weighting factors;
modeling the effective permittivity of the milk using the gas volume fraction of the milk, the concentration of each of the components of fat, water, and fat-free solids, and permittivity values of the respective components.

5. The method as claimed in claim 4 , further comprising:
measuring a temperature of the milk; and
calculating temperature dependent values for density and/or permittivity of the components contained in the milk.

6. The method as claimed in claim 4 , wherein the densimeter includes a Coriolis mass flowmeter, the method further comprising:
calculating at least one of the following: a mass flow of the milk, a volume flow of the milk, a fat flow of the milk, a fat-free solids flow of the milk, and a water flow of the milk in the pipeline.

7. The method as claimed in claim 1 , wherein the microwaves include at least one frequency above 1 GHz.

8. A measuring arrangement for determining a fat content of milk in a pipeline, comprising:
a densimeter having at least one oscillatable measuring tube and configured to determine a first eigenfrequency of a first bending oscillation mode and a second eigenfrequency of a second bending oscillation mode;
a pressure sensor for measuring a static pressure in the pipeline;
a microwave sensor for ascertaining a propagation velocity and/or an absorption of microwave signals in the milk; and
a computer unit for calculating the fat content of the milk, wherein the computer unit is configured to:
calculate a velocity of sound in the milk and calculate an average density for the milk based on the first and second eigenfrequencies;
read the static pressure in the pipeline using the pressure sensor;
calculate a gas volume fraction of the milk based on the velocity of sound in the milk, the average density, and the static pressure;
calculate a density of the milk without gas content based on the average density and based on the gas volume fraction;
measure the propagation velocity and/or the absorption of microwaves in the milk using the microwave sensor;
calculate an effective permittivity of the milk from the propagation velocity and/or absorption; and
calculate a fat fraction of the milk based on the density of the milk without gas content and on the effective permittivity.

9. The measuring arrangement as claimed in claim 8 , wherein the densimeter, the pressure sensor, and the microwave sensor are installed in the pipeline.

10. The measuring arrangement as claimed in claim 8 , wherein the densimeter includes a Coriolis mass flowmeter.

Assignees

• Flowtec Ag

Inventors

• Pflüger Stefan
• Drahm Wolfgang
• Zhu Hao

Classifications

• G01N22/00

  Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more (G01N3/00 - G01N17/00, G01N24/00 take precedence) · CPC title

• G01F1/8436

  signal processing · CPC title

• G01N9/26

  by measuring pressure differences · CPC title

• G01N33/06 Primary

  Determining fat content, e.g. by butyrometer · CPC title

• G01F15/02

  Compensating or correcting for variations in pressure, density or temperature · CPC title