Enhanced enclosures for acoustical gas concentration sensing and flow control

Patent metadata

Field	Value
Publication number	US-10099185-B2
Application number	US-201514822410-A
Country	US
Kind code	B2
Filing date	Aug 10, 2015
Priority date	Aug 11, 2014
Publication date	Oct 16, 2018
Grant date	Oct 16, 2018

Abstract

Mass-transfer rate control arrangement and method in which a process precursor mixture is produced containing carrier gas and a process precursor gas. A quantity of the process precursor present in the process precursor mixture is acoustically sensed to produce a sensor output. A dilution gas is provided and the process precursor mixture and the dilution gas are separately conveyed to a dilution point, at which a diluted mixture of the dilution gas and the process precursor mixture is achieved. A relative flow rate of the carrier gas and the dilution gas is automatically controlled in response to the sensor output such that the diluted mixture at the dilution point has a prescribed mass transfer rate of the precursor gas.

First claim

What is claimed is:

1. An apparatus for acoustically determining a property of a test medium, comprising:
an enclosure including a base and a cover, said base and said cover cooperating to define a chamber;
an acoustical sensor mounted to said base, said acoustical sensor including a first acoustical transducer defining a first exposed face and a second acoustical transducer defining a second exposed face, said first exposed face and said second exposed face being substantially parallel and adapted for contact with said test medium and defining a gap therebetween;
at least one heating element operatively coupled with said enclosure,
wherein a first portion of said enclosure is operatively coupled with said at least one heating element, said first portion extending along a height of a natural convection loop,
wherein a second portion of said enclosure is not operatively coupled with said at least one heating element, said second portion extending along the height of the natural convection loop, the second portion opposing said first portion of said enclosure to create the natural convection loop within the enclosure that mixes the gases and provides destratification.

2. The apparatus of claim 1 , wherein said second portion of said enclosure is operatively coupled to a cooling device, and wherein said cooling device includes a plurality of cooling fins.

3. The apparatus of claim 1 , wherein said first portion of said enclosure is said base.

4. The apparatus of claim 1 , wherein:
said enclosure substantially defines a rectangular box, said cover defining a top portion, a bottom portion, a first side portion, a second side portion and a third side portion, said second side portion being adjacent to and disposed between said first side portion and said third side portion;
said second portion of said enclosure is said second side portion.

5. The apparatus of claim 1 , wherein said acoustical sensor is oriented so that said first exposed face of said first acoustical transducer and said second exposed face of said second acoustical transducer face horizontally.

6. The apparatus of claim 1 , wherein said gap is greater than 12 mm and less than 50 mm.

7. The apparatus of claim 6 , wherein said gap is approximately 15 mm.

8. The apparatus of claim 6 , wherein said gap is approximately 30 mm.

9. An apparatus for acoustically determining a property of a test medium, comprising:
an enclosure including a base and a cover, said base and said cover cooperating to define a chamber;
an acoustical sensor mounted to said base, said acoustical sensor including a first acoustical transducer defining a first exposed face and a second acoustical transducer defining a second exposed face, said first exposed face and said second exposed face being parallel and adapted for contact with said test medium and defining a gap therebetween;
at least one heating element operatively coupled with said enclosure,
wherein a first portion of said enclosure is operatively coupled with said at least one heating element, said first portion being vertically oriented,
wherein a second portion of said enclosure is not operatively coupled with said at least one heating element, said second portion being vertically oriented and opposing said first portion of said enclosure,
wherein said at least one heating element substantially surrounds said acoustical sensor.

10. A method of maintaining an acoustical sensor at a substantially uniform temperature, comprising:
providing an acoustical sensor mounted within an enclosure, said acoustical sensor including first and second acoustical transducers that are substantially parallel to each other and adapted for contact with a test medium, said first and second acoustical transducers defining a gap therebetween;
providing a heating system adapted to apply heat to portions of said enclosure, said portions substantially surrounding said acoustical sensor; and
providing a set of instructions on a tangible medium, said instructions comprising:
heating portions of said enclosure that substantially surround said acoustical sensor;
cooling a substantially vertical portion of said enclosure to induce a recirculation of a gas within said enclosure, said recirculation causing destratification of said gas within said enclosure.

11. The method of claim 10 , wherein said destratification of said gas causes a spatial temperature variation of said gas within said enclosure to be within a predetermined value.

12. The method of claim 10 , wherein the step of cooling a substantially vertical portion of said enclosure includes free convection between said substantially vertical portion of said enclosure and ambient surroundings.

13. The method of claim 10 , wherein the step of heating portions of said enclosure include controlling the temperature of said portions to a set point that is at least 20° C. greater than an ambient temperature that surrounds said enclosure.

14. An apparatus for acoustically determining a property of a test medium, comprising:
an enclosure including a base and a cover, said base and said cover cooperating to define a chamber;
an acoustical sensor mounted to said base, said acoustical sensor including a first acoustical transducer defining a first exposed face and a second acoustical transducer defining a second exposed face, said first exposed face and said second exposed face situated in a facing arrangement with one another and being constructed to contact said test medium and define a gap therebetween;
said first acoustical transducer being electrically coupled with a transmitter circuit constructed to actuate said first acoustical transducer by a first generated signal having a frequency of between 2 and 3 MHz and a duration of between 15 and 50 cycles to produce a first acoustical signal directed to travel through said gap;
said second acoustical transducer being electrically coupled with a receiver circuit constructed to produce a first received signal from the first acoustical signal;
said receiver circuit being electrically coupled to a digitizing circuit configured to sample the first received signal at a sampling rate of between 20 and 100 samples per cycle to produce a first received digital signal;
said digitizing circuit being electrically coupled to a controller circuit that includes a processor and a non-transitory data storage medium containing instructions that, when executed, cause the processor to apply a maximum-likelihood function to the first received digital signal and to a reference digital signal, and to determine a time delay between a feature of the first received digital signal and a feature of the reference digital signal, said time delay between features being indicative of property of said test medium.

15. A mass-transfer rate control arrangement comprising:
a carrier gas source;
a carrier gas mass flow regulator arranged to regulate a rate of flow of carrier gas from the carrier gas source;
a process precursor source, including a precursor vessel having an inlet in fluid communication with the carrier gas source via the carrier gas mass flow regulator, and an outlet arranged to convey a mixture of the process precursor and the carrier gas;
an acoustical sensor in fluid communication with the outlet, the acoustical sensor comprising a chamber arranged to convey a flow of the mixture through the chamber, and further comprising an electrical signal generator constructed to generate an electrical signal representing a quantity of the process precursor present in the mixture flowing through the chamber;
a dilution gas source;
a dilution gas mass flow regulat

Assignees

• Veeco Instr Inc

Inventors

• Logue Ray
• Sirota Don
• Karkala Karthik
• Armour Eric
• Morath Christopher A
• Sinharoy Arindam

Classifications

• G01N2291/02809

  Concentration of a compound, e.g. measured by a surface mass change · CPC title

• G01N29/222 Primary

  Constructional or flow details for analysing fluids (optoacoustic fluid cells G01N29/2425) · CPC title

• G01N29/4436

  with a reference signal (amplitude comparison G01N29/48) · CPC title

• G01N29/024 Primary

  by measuring propagation velocity or propagation time of acoustic waves · CPC title

• G01N2291/021

  Gases · CPC title