US 8,264,239 B2 · Guided wave cutoff spectroscopy using a cylindrical measurement cell

Abstract

A cylindrical waveguide (1) used for analyzing a flowing stream of corn masa (18) using a guided microwave spectroscopy (GMS) process. The waveguide (1) includes opposed spaced apart plates (2, 5) that each define a plane within the waveguide housing (3) that is parallel to the direction (47) of corn masa flow through the waveguide. The housing (1) includes two opposed frames (7, 19) that each surround an aperture (6) that permits access to the region between the waveguide plates (2, 5). A microwave probe assembly (81) is mounted at each frame (7, 19) to permit the radiation and reception of electromagnetic waves within the housing (1) as required to perform the GMS process. A temperature probe (51) is inserted into the interior of the housing (1) at a fitting (13). In an actual installation a y-shaped assembly (89) can be used to divide the corn masa flow into two separate paths with one path containing the waveguide (1). A diverter vane (93) within the y-shaped assembly permits flow to be equalized within the two separate flow paths.

A guided microwave spectroscopy system, comprising:

(A) a cylindrical measurement cell, the cylindrical measurement cell comprising:
(i) a first open end, the first open end being adapted to admit a product stream into the cylindrical measurement cell;
(ii) a second open end, the second open end being adapted to discharge a product stream from the cylindrical measurement cell;
(iii) a first plate, the first plate being substantially rigid and stationary, the first plate defining a first plane, the first plane being substantially parallel to a direction of product flow through the cylindrical measurement cell, the first plate further comprising:
(a) a leading edge, the leading edge being formed as a bevel, the leading edge being oriented so as to cause the bevel to encounter the product stream before the product stream encounters any other portion of the first plate, the leading edge being formed as at least one of (i) a straight line and (ii) a curved line;
and
(b) a trailing edge;
(iv) a second plate, the second plate being substantially rigid and stationary, the second plate defining a second plane, the second plane being substantially parallel to the first plane, wherein the first plate and the second plate have substantially identical dimensions, the first plate and the second plate being substantially parallel to a diameter of the cylindrical measurement cell, the first and second plate being positioned in an opposed relationship at a substantially equal distance from the diameter of the cylindrical measurement cell so as to define a waveguide region residing between the first and second plate;
(B) a first microwave probe for radiating electromagnetic energy into the cylindrical measurement cell;
(C) a second microwave probe for intercepting electromagnetic energy from within the cylindrical measurement cell;
and
(D) a path separator, the path separator causing a first portion of the product stream to pass completely through the cylindrical measurement cell and causing a second portion of the product stream to completely bypass the cylindrical measurement cell;
(E) a substantially cylindrical outer casing forming part of the cylindrical measurement cell, the cylindrical outer casing comprising at least one orifice, the orifice being formed in the outer casing at a location outside of the waveguide region;
(F) a telemetry sensor, the telemetry sensor being introduced into an interior region of the cylindrical measurement cell by extending through the orifice formed in the outer casing of the cylindrical measurement cell;
(G) a first probe port, the first probe port being formed in the outer casing, the first probe port residing between the first and second plate so as to permit the first microwave probe to launch electromagnetic energy into the waveguide region, the first probe port having a fixed width and defining a first substantially rectangular plane, the first probe port having a leading edge, the first substantially rectangular plane being substantially perpendicular to the first plate and to the second plate;
(H) a second probe port, the second probe port being formed in the outer casing, the second probe port residing between the first and second plate so as to permit the second microwave probe to intercept electromagnetic energy launched by the first microwave probe into the waveguide region, the second probe port having a trailing edge, the second probe port being longitudinally offset from the first probe port such that a distance between the leading edge of the first probe port and the trailing edge of the second probe port is at least twice as great as the fixed width of the first probe port.

13 more elements

Description4,927 words

Summary1,727 words

#1. Field of Invention

#This invention pertains generally to the field of guided microwave spectroscopy and more particularly to measurement cells used to implement such spectroscopy techniques.

#2. Description of Prior Art

Brief description of the drawings20 figures

#FIG. 1 is a perspective view of a prior art corn masa processing system;

#FIG. 2 is an isometric view of a prior art frequency sensitive measurement cell;

#FIG. 3 is a top plan schematic view of a first embodiment of a measurement cell constructed according to the principles of the present invention;

Detailed description2,807 words

#Referring to FIG. 5, a cylindrical measurement cell constructed according to the principles of the present invention is shown generally at 1. The cell 1 includes a first plate 2 which is mounted within a cylindrical housing 3. Mounted substantially parallel to the first plate 2 is a substantially identical second plate 5. One or both of the plates 2 and 5 may be formed to include a beveled leading edge 83 to reduce resistance to a flowing product stream, and one or both plates may be individually removed from the housing 3. The spacing between the plates 2 and 5 determines the cutoff frequency above which radiated microwave energy may not be usefully employed using the GMS analysis technique and is defined by the formula:

#f c = c ɛ ′ 2 ⁢ a where fc is the cutoff frequency, “a” is the distance between plates 2 and 5, “c” is equal to the velocity of light, and ∈′ is the dielectric constant of a material flowing between plates 2 and 5.

#The housing 3 is typically made of stainless steel and includes a handle 4 to facilitate manipulation of the waveguide during the performance of installation and maintenance procedures. Formed within the housing 3 is a first substantially rectangular aperture 6 that is defined and bordered by a frame 7. The rectangular aperture 6 permits electromagnetic energy to pass into an interior region of the housing 3.

Facts

Application

12/462,239Filed 30 Jul 2009

Published

US 2011/0025347 A13 Feb 2011

Granted

11 Sep 2012

Term ends

5 Sep 2030

Estimated · how

20 years from earliest known nonprovisional domestic filing plus recorded patent term adjustment, including 402 days of adjustment. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification4 codes

A21C 1/146
Controlling; Testing; Measuring: measuring properties of the dough, e.g. moisture, electrical conductivity, temperature
G01N 22/04
Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or…
A21C
Machines or equipment for making or processing doughs
G01N
Investigating or analysing materials by determining their chemical or physical properties

Timeline

30 Jul 2009Application filedUS 12/462,239
3 Feb 2011PublishedUS 2011/0025347 A1
21 Aug 2012Assigned to Thermo Fisher Scientificassignment of assignor's interest
11 Sep 2012GrantedUS 8,264,239 B2
4 Mar 2015Assigned to Thermo Ramsey Inc.assignment of assignor's interest
4 Mar 2015Assigned to Thermo Ramsey Inc.assignment of assignor's interest
12 Oct 2026TodayWithin its term
5 Sep 2030Term endsEstimated, includes 402 days of adjustment

Guided wave cutoff spectroscopy using a cylindrical measurement cell

Life of this patent

Guided wave cutoff spectroscopy using a cylindrical measurement cell

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims4

Description4,927 words

Drawings

Classification4 codes

Life of this patent

Description4,927 words