US5440667A
Expired / Lapsed
US
⏱️ 0.0 years remaining
OHMIC heater including electrodes arranged along a flow axis to reduce leakage current
Assignee: Capenhursttech Ltd
•
Filing: 1992-12-08
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Granted: 1995-08-08
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Expires: 2012-12-08
Abstract
Abstract An ohmic heater comprises at least two electrodes contained within a vessel such that the electrodes lie along the length of the vessel. The vessel has inlet and outlet ports in the top and bottom through which a fluid to be heated flows, passing through the vessel along the length of the vessel. The electrodes are equally spaced about the axis of the vessel and when in use, are each connected to a single phase of a power supply, such that the total voltage at any point in time at the electrodes is near or at a neutral potential of the electric power supply. Electrically conductive guard rings are positioned around the inner periphery of the inlet and outlet ports of the vessel and are connected to the neutral potential of the electric power supply by electrical connectors. A leakage current monitor is interposed between guard rings and the neutral potential to enable current leakage from said heater to be monitored. In use, a current passes perpendicular to the flow of the fluid, but the electric potential on the axis is near to neutral, and hence the leakage current from the ohmic heater is substantially reduced.
Inventors
- 👤 David P. Simpson
- 👤 Robert Stirling
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 15:42
CPC Classifications
F; F24; F24H; F24H1/00; F24H1/10; F24H1/101; F24H1/106
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
168 words
An ohmic heater for heating a fluid comprising a vessel having inlet and outlet ports at opposite ends thereof, on a common axis and between which said fluid flows when in use, along an axis; at least two electrodes arranged to be equally spaced about said axis of flow and contained within said vessel, such that the separation of said electrodes is substantially greater than the diameter of said inlet and outlet ports; means to supply a single phase of an electric power supply to each said electrode such that the electric potential at any time along said axis and at said inlet and outlet ports is substantially at a neutral potential of the electric power supply; an electrically conductive guard ring exposed to the flow of fluid positioned around the inner periphery of each said port; means to electrically connect said guard rings to a neutral point of the electric power supply; and means to monitor the leakage current between said guard rings and said neutral point.
Claim 2
Dependent Claim
168 words
An ohmic heater for heating a fluid comprising a vessel having inlet and outlet ports at opposite ends thereof, on a common axis and between which said fluid flows when in use, along an axis; at least two electrodes arranged to be equally spaced about said axis of flow and contained within said vessel, such that the separation of said electrodes is substantially greater than the diameter of said inlet and outlet ports; means to supply a single phase of an electric power supply to each said electrode such that the electric potential at any time along said axis and at said inlet and outlet ports is substantially at a neutral potential of the electric power supply; an electrically conductive guard ring exposed to the flow of fluid positioned around the inner periphery of each said port; means to electrically connect said guard rings to a neutral point of the electric power supply; and means to monitor the leakage current between said guard rings and said neutral point.
Claim 3
Dependent Claim
14 words
An ohmic heater as claimed in claim 1 wherein said vessel is electrically insulating.
Claim 4
Dependent Claim
23 words
An ohmic heater as claimed in claim 2 wherein each said electrode has a back surface adjacent to the wall of said vessel.
Claim 5
Dependent Claim
19 words
An ohmic heater as claimed in claim 1 wherein said electrodes are arranged to extend parallel to said axis.
Claim 6
Dependent Claim
33 words
An ohmic heater as claimed in claim 1 wherein said electrodes are arranged such that their separation transverse to said axis increases along said axis in the direction of flow of said fluid.
Claim 7
Dependent Claim
33 words
An ohmic heater as claimed in claim 1 comprising three said electrodes, wherein said means to supply is adapted to supply each of said electrodes with a single phase of a three-phase supply.
Claim 8
Dependent Claim
38 words
An ohmic heater as claimed in claim 1 wherein said means to supply is responsive to said means to monitor to disconnect the supply of power to said electrodes when the leakage current detected exceeds a predetermined threshold.
Claim 9
Dependent Claim
25 words
An ohmic heater as claimed in claim 1 wherein the surface of part of each of the electrodes is covered with a movable insulating material.
Claim 10
Dependent Claim
22 words
An ohmic heater as claimed in claim 1 wherein said vessel is arranged such that the flow of fluid is against gravity.
Claim 11
Dependent Claim
36 words
An ohmic heater as claimed in claim 1 comprising at least two said vessels co-axially coupled wherein the spacing of said electrodes is greater in successive said vessels along the direction of flow of said fluid.
Claim 12
Dependent Claim
22 words
An ohmic heater as claimed in claim 10 wherein electrodes in geometrically equivalent positions in each said vessel are electrically connected together.
Claim 13
Dependent Claim
22 words
An ohmic heater as claimed in claim 1 including means to electrically connect said guard rings and said neutral point to earth.
Claim 14
Dependent Claim
50 words
An ohmic heater as claimed in claim 1, further including a second electrically conductive guard ring positioned around the periphery of each of said ports at positions further from said electrodes than said electrically conductive guard rings; and means to electrically connect said second electrically conductive guard rings to earth.
Claim 15
Dependent Claim
114 words
An ohmic heater for heating a fluid, comprising: a vessel having an inlet port and an outlet port between which said fluid flows when in use, along an axis; three electrodes equally spaced about said axis and contained within said vessel; means to supply a single phase of a three phase power supply to each electrode; an electrically conductive guard ring exposed to the flow of fluid positioned around the inner periphery of each of said inlet port and said outlet port; means to electrically connect said guard rings to a neutral point of the three phase power supply; and means to monitor the leakage current between said guard rings and said neutral point.
Claim 16
Dependent Claim
114 words
An ohmic heater for heating a fluid, comprising: a vessel having an inlet port and an outlet port between which said fluid flows when in use, along an axis; three electrodes equally spaced about said axis and contained within said vessel; means to supply a single phase of a three phase power supply to each electrode; an electrically conductive guard ring exposed to the flow of fluid positioned around the inner periphery of each of said inlet port and said outlet port; means to electrically connect said guard rings to a neutral point of the three phase power supply; and means to monitor the leakage current between said guard rings and said neutral point.
Claim 17
Dependent Claim
143 words
An ohmic heater for heating a fluid, comprising: a vessel having an inlet port and an outlet port at opposite ends of said vessel; said ports being arranged on a common axis extending longitudinally through said vessel and the interior of said vessel tapering in diameter to said ports; three electrodes equally spaced about said axis and contained within said vessel at positions remote from said axis; means to supply a single phase of a three phase power supply to each said electrode; an electrically conductive guard ring exposed to the flow of fluid positioned around the inner periphery of each of said ports; means to electrically connect said guard rings to a neutral point of the three phase supply; and means to monitor the current between said guard rings and said neutral point to provide a measure of the heater leakage current.
Claim 18
Dependent Claim
143 words
An ohmic heater for heating a fluid, comprising: a vessel having an inlet port and an outlet port at opposite ends of said vessel; said ports being arranged on a common axis extending longitudinally through said vessel and the interior of said vessel tapering in diameter to said ports; three electrodes equally spaced about said axis and contained within said vessel at positions remote from said axis; means to supply a single phase of a three phase power supply to each said electrode; an electrically conductive guard ring exposed to the flow of fluid positioned around the inner periphery of each of said ports; means to electrically connect said guard rings to a neutral point of the three phase supply; and means to monitor the current between said guard rings and said neutral point to provide a measure of the heater leakage current.
Claim 19
Independent Claim
163 words
A method of operating an ohmic heater, comprising the steps of: a) passing a fluid to be heated through an inlet port of a vessel, along a flow axis through said vessel and out of an outlet port, said inlet port and said outlet port being arranged at opposite ends of said vessel and on said flow axis; b) energising each of a plurality of electrodes spaced about said flow axis using a single phase of an electric power supply such that the electric potential at any time on said axis and at the inlet port and the outlet port is substantially at the neutral potential of the electric power supply; c) connecting an electrically conductive guard ring to the neutral potential of the electric power supply, which electrically conductive guard ring is exposed to the flow of said fluid and positioned around the periphery of each of said ports; and d) monitoring the current to and from said electrically conductive guard rings.
Claim 20
Independent Claim
163 words
A method of operating an ohmic heater, comprising the steps of: a) passing a fluid to be heated through an inlet port of a vessel, along a flow axis through said vessel and out of an outlet port, said inlet port and said outlet port being arranged at opposite ends of said vessel and on said flow axis; b) energising each of a plurality of electrodes spaced about said flow axis using a single phase of an electric power supply such that the electric potential at any time on said axis and at the inlet port and the outlet port is substantially at the neutral potential of the electric power supply; c) connecting an electrically conductive guard ring to the neutral potential of the electric power supply, which electrically conductive guard ring is exposed to the flow of said fluid and positioned around the periphery of each of said ports; and d) monitoring the current to and from said electrically conductive guard rings.
Claim 21
Dependent Claim
47 words
A method of operating an ohmic heater as claimed in claim 16, further including the step of connecting to earth a second electrically conductive guard ring positioned around the inner periphery of each of said ports at a position further from said electrodes than said guard rings.
Claim 22
Dependent Claim
34 words
A method of operating an ohmic heater as claimed in claim 16, wherein current between said electrodes is varied by adjusting the position of an insulating material partially covering the surface of said electrodes.
Claim 23
Dependent Claim
34 words
A method as claimed in claim 16 including the step of disconnecting the supply of power to said electrodes when the current detected flowing to or from said guard rings exceeds a predetermined threshold.
Claim 24
Dependent Claim
18 words
A method as claimed in claim 16 including the step of electrically connecting said guard rings to earth.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-08-07 | 1999-02-06 | 1999-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-08-07 | 2003-02-06 | 2003-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-08-07 | 2007-02-06 | 2007-08-08 | $7700.00 | Window Closed / Lapsed |