US4700771A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multi-zone boiling process and apparatus
Assignee: Air Products and Chemicals Inc
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Filing: 1987-01-13
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Granted: 1987-10-20
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Expires: 2007-01-13
Abstract
Abstract The invention relates to a process and apparatus for boiling flowing liquids such as liquefied gases in a heat exchanger in which a circulating flow is occurring, such as in reboiler-condensers in air separation and similar cryogenic plants or other applications where a high efficiency for boiling heat transfer is beneficial. The important feature of the process and apparatus is the use of two sequential heat transfer zones having different pressure drop and heat transfer characteristics in the same boiling channel, the first zone having an overall high-convective-heat-transfer characteristic and an overall higher pressure drop characteristic and comprising a plurality of sub-zones, each sub-zone sequentially having a lower pressure drop than the previous sub-zone and the second zone having a lower pressure drop and an enhanced nucleate boiling heat transfer characteristic.
Inventors
- 👤 Douglas L. Bennett
- 👤 Keith A. Ludwig
- 👤 Alexander Schwarz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 15:08
CPC Classifications
F; F28; F28F; F28F13/00; F28F13/18; F28F13/185; F28F13/187; F25; F25J; F25J3/00; F25J3/02; F25J3/04; F25J3/04406; F25J3/04412; F25J5/00; F25J5/002; F25J5/005; F25J2250/00; F25J2250/02; F25J2290/00; F25J2290/10; F25J2290/44; F28D; F28D21/00; F28D2021/0019; F28D2021/0033; Y; Y10; Y10S; Y10S165/00; Y10S165/911
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
123 words
In a process for boiling flowing liquids in a heat exchanger wherein a flowing liquid is heated to vaporize said liquid, the improvement of which comprises: (a) passing said flowing liquid through a first heat tranfer zone wherein said liquid is subjected to an overall high-convective heat transfer and an overall high pressure drop in a plurality of steps characterized in that each consecutive step in the direction of flow exposes the liquid to a lower pressure drop than the preceding step; and then (b) passing said flowing liquid through a second heat transfer zone to expose the liquid to an enhanced nucleate boiling heat transfer surface and a lower pressure drop than the overall pressure drop in the first heat transfer zone.
Claim 2
Dependent Claim
123 words
In a process for boiling flowing liquids in a heat exchanger wherein a flowing liquid is heated to vaporize said liquid, the improvement of which comprises: (a) passing said flowing liquid through a first heat tranfer zone wherein said liquid is subjected to an overall high-convective heat transfer and an overall high pressure drop in a plurality of steps characterized in that each consecutive step in the direction of flow exposes the liquid to a lower pressure drop than the preceding step; and then (b) passing said flowing liquid through a second heat transfer zone to expose the liquid to an enhanced nucleate boiling heat transfer surface and a lower pressure drop than the overall pressure drop in the first heat transfer zone.
Claim 3
Dependent Claim
120 words
In a heat exchanger for boiling flowing liquids, the improvement of which comprises the incorporation of two sequential heat transfer zones of different characteristics in a single exchanger, wherein said heat exchanger comprises: (a) a first heat transfer zone having means to create an overall high-convective-heat-transfer and an overall higher pressure drop, said means comprising a plurality of sub-zones arranged consecutively in the direction of flow of the boiling liquid wherein each of said consecutive sub-zones comprises in order a surface with a decreased pressure drop characteristic than the preceding sub-zone; and (b) a second essentially open channel heat transfer zone so constructed and arranged to provide an enhanced nucleate boiling heat transfer surface and a lower pressure drop characteristic.
Claim 4
Dependent Claim
120 words
In a heat exchanger for boiling flowing liquids, the improvement of which comprises the incorporation of two sequential heat transfer zones of different characteristics in a single exchanger, wherein said heat exchanger comprises: (a) a first heat transfer zone having means to create an overall high-convective-heat-transfer and an overall higher pressure drop, said means comprising a plurality of sub-zones arranged consecutively in the direction of flow of the boiling liquid wherein each of said consecutive sub-zones comprises in order a surface with a decreased pressure drop characteristic than the preceding sub-zone; and (b) a second essentially open channel heat transfer zone so constructed and arranged to provide an enhanced nucleate boiling heat transfer surface and a lower pressure drop characteristic.
Claim 5
Dependent Claim
15 words
The heat exchanger of claim 2 wherein said heat exchanger is a thermosyphon heat exchanger.
Claim 6
Dependent Claim
17 words
The heat exchanger of claim 2 wherein said heat exchanger is a shell and tube heat exchanger.
Claim 7
Dependent Claim
16 words
The heat exchanger of claim 2 wherein said heat exchanger is a plate-fin brazed heat exchanger.
Claim 8
Dependent Claim
32 words
The heat exchanger of claim 2 wherein said first heat transfer zone has a length in the range of 10 percent to 60 percent of the total length of said heat exchanger.
Claim 9
Dependent Claim
32 words
The heat exchanger of claim 2 wherein said first heat transfer zone has a length in the range of 20 percent to 40 percent of the total length of said heat exchanger.
Claim 10
Dependent Claim
20 words
The heat exchanger of claim 2 wherein said enhanced nucleate boiling heat transfer surface is a bonded high-porosity porous metal.
Claim 11
Dependent Claim
19 words
The heat exchanger of claim 2 wherein said enhanced nucleate boiling heat transfer surface is a mechanically formed surface.
Claim 12
Dependent Claim
33 words
The heat exchanger of claim 2 wherein said enhanced nucleate boiling heat transfer surface has a heat transfer coefficient greater than or equal to three times greater than for a corresponding flat plate.
Claim 13
Dependent Claim
19 words
The heat exchanger of claim 2 wherein the number of sub-zones in said first heat transfer zone is two.
Claim 14
Dependent Claim
63 words
The heat exchanger of claim 11 wherein the ratio of (fL/D H ) 1 /(fL/D H ) 2 , where L is the length of the sub-zone, D H is the hydraulic diameter, f is the friction factor, subscript 1 refers to the first sub-zone and subscript 2 refers to the second sub-zone of said first heat transfer zone, is greater than 5.
Claim 15
Dependent Claim
64 words
The heat exchanger of claim 11 wherein the ratio of (fL/D H ) 1 /(fL/D H ) 2 , where L is the length of the sub-zone, D H is the hydraulic diameter, f is the friction factor, subscript 1 refers to the first sub zone and subscript 2 refers to the second sub-zone of said first heat transfer zone, is greater than 10.
Claim 16
Dependent Claim
41 words
The heat exchanger of claim 11 wherein said heat exchanger is a plate-fin brazed heat exchanger and the surface of said first sub-zone is an easyway perforated fin, an easyway serrated fin, a hardway perforated fin or a hardway serrated fin.
Claim 17
Dependent Claim
36 words
The heat exchanger of claim 11 wherein said heat exchanger is a plate-fin brazed heat exchanger and the surface of said second sub-zone is a straight fin, an easyway perforated fin or an easyway serrated fin.
Claim 18
Dependent Claim
54 words
The heat exchanger of claim 11 wherein said heat exchanger is a plate-fin brazed heat exchanger and the surface of said first sub zone is a hardway perforated fin or a hardway serrated fin and the surface of said second sub-zone is a straight fin, an easyway perforated fin or an easyway serrated fin.
Claim 19
Dependent Claim
48 words
The heat exchanger of claim 11 wherein said heat exchanger is a shell and tube heat exchanger and the surface of said first sub-zone is a spiral fin, a series of perforated radial fins, a series of perforated disks mounted normal to flow or a series of baffles.
Claim 20
Dependent Claim
28 words
The heat exchanger of claim 11 wherein said heat exchanger is a shell and tube heat exchanger and the surface of said second sub-zone is a straight fin.
Claim 21
Dependent Claim
59 words
The heat exchanger of claim 11 wherein said heat exchanger is a shell and tube heat exchanger and the surface of said first sub-zone is a spiral fin, a series of perforated radial fins, a series of perforated disks mounted normal to flow or a series of baffles and the surface of said second sub-zone is a straight fin.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-10-19 | 1991-04-20 | 1991-10-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-10-19 | 1995-04-20 | 1995-10-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-10-19 | 1999-04-20 | 1999-10-20 | $7700.00 | Window Closed / Lapsed |