Ultrasonic fluid densitometer for process control

• US 6,082,180 A
• Filed: 10/21/1998
• Issued: 07/04/2000
• Est. Priority Date: 10/21/1998
• Status: Expired due to Fees

• Current Assignee: Battelle Memorial Institute
• Original Assignee: Battelle Memorial Institute
• Inventors: Greenwood, Margaret S.
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US09/178,030
• Time in Patent Office: 622 Days
• Field of Search: 73/32 A, 73/30.01, 73/30.04, 73/54.41, 73/64.53
• US Class Current: 73/32.00A
• CPC Class Codes: G01N 2291/02809 Concentration of a compound, e.g. measured by a surface mass change
• CPC Class Codes: G01N 2291/02818 Density, viscosity
• CPC Class Codes: G01N 2291/02881 Temperature
• CPC Class Codes: G01N 2291/045 External reflections, e.g. on reflectors
• CPC Class Codes: G01N 2291/102 one emitter, one receiver
• CPC Class Codes: G01N 29/032 by measuring attenuation of acoustic waves
• CPC Class Codes: G01N 29/222 Constructional or flow details for analysing fluids optoacoustic fluid cells G01N29/2425
• CPC Class Codes: G01N 9/24 by observing the transmission of wave or particle radiation through the material

Abstract

The present invention is an ultrasonic fluid densitometer that uses at least one pair of transducers for transmitting and receiving ultrasonic signals internally reflected within a material wedge. A temperature sensor is provided to monitor the temperature of the wedge material. Density of a fluid is determined by immersing the wedge into the fluid and measuring reflection of ultrasound at the wedge-fluid interface and comparing a transducer voltage and wedge material temperature to a tabulation as a function of density.

Claims

1. An ultrasonic densitometer for process control of a density of a fluid, said ultrasonic densitometer having a wedge material, said wedge material having at least two sides substantially non-parallel, a first non-parallel side having a first ultrasonic transducer mounted thereon and a second non-parallel side immersible into said fluid whereby an ultrasonic signal emanating from said first ultrasonic transducer strikes said second non-parallel side and reflects a reflected ultrasonic signal;

the improvement comprising;

said wedge material having a third non-parallel side with a second transducer for receiving the reflected ultrasonic signal, said wedge material further having an angle of internal reflection about equal to the zero reflection coefficient angle; and

a temperature sensor attached to said wedge material for combining a wedge material temperature with a transducer voltage to confirm temperature uniformity of said wedge material for process control.

2. The ultrasonic densitometer as recited in claim 1 wherein the angle of internal reflection is within about 5°

of the zero reflection coefficient angle.

3. The ultrasonic densitometer as recited in claim 2, wherein said angle of internal reflection is about 40°

.

4. A method of process control of a density of a fluid using an ultrasonic densitometer having a wedge material, said wedge material having at least two sides substantially non-parallel, a first non-parallel side having a first ultrasonic transducer mounted thereon and a second non-parallel side immersed into said fluid, the method having the steps of:

(a) emanating a first ultrasonic signal from said first ultrasonic transducer and striking said second non-parallel side and reflecting a reflected ultrasonic signal;

the improvement comprising the steps of;

receiving the reflected ultrasonic signal with a second transducer mounted on a third non-parallel side on said wedge material; and

measuring a temperature of said wedge material for combining said temperature with a transducer voltage for process control.

5. The method as recited in claim 4 wherein an angle of internal reflection in the wedge material is within about 5°

of the zero reflection coefficient angle.

6. The method as recited in claim 5, wherein said angle of internal reflection is about 40°

.