EP0110545A1 - Wärmeübertragungsverfahren - Google Patents

Wärmeübertragungsverfahren Download PDF

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Publication number
EP0110545A1
EP0110545A1 EP83306441A EP83306441A EP0110545A1 EP 0110545 A1 EP0110545 A1 EP 0110545A1 EP 83306441 A EP83306441 A EP 83306441A EP 83306441 A EP83306441 A EP 83306441A EP 0110545 A1 EP0110545 A1 EP 0110545A1
Authority
EP
European Patent Office
Prior art keywords
tubes
vapour
tube
fluid
heat transfer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP83306441A
Other languages
English (en)
French (fr)
Inventor
Charles David Cotchin
Ian Douglas Raffan Grant
John Alexander Richardson Henry
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
UK Secretary of State for Trade and Industry
Original Assignee
UK Secretary of State for Trade and Industry
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB838307569A external-priority patent/GB8307569D0/en
Application filed by UK Secretary of State for Trade and Industry filed Critical UK Secretary of State for Trade and Industry
Publication of EP0110545A1 publication Critical patent/EP0110545A1/de
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/02—Header boxes; End plates
    • F28F9/026—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits
    • F28F9/0282—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits by varying the geometry of conduit ends, e.g. by using inserts or attachments for modifying the pattern of flow at the conduit inlet or outlet
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28B—STEAM OR VAPOUR CONDENSERS
    • F28B9/00—Auxiliary systems, arrangements, or devices
    • F28B9/04—Auxiliary systems, arrangements, or devices for feeding, collecting, and storing cooling water or other cooling liquid

Definitions

  • This invention relates to a heat transfer process of the kind in which a vapour is condensed within a series of tubes, and in so doing gives up heat to a fluid in contact with the outer surface of the tubes.
  • vapour tubes are all of substantially the same length and cross-sectional area
  • the tubes are all immersed in a ⁇ boiling liquid during use, and so the external temperature of the tubes is the same at all points. Equally, no variation resulting from uneven flow conditions externally of the tubes can be expected. If the tubes are of the same length and cross-sectional area, no maldistribution resulting from varying pipe friction can be anticipated.
  • the invention is also concerned with a heat transfer process in shell and tube heat exchangers in which a vapour condensing within a set of tubes through which it flows in parallel, gives up heat to a fluid flowing longitudinally along the external surface of the tubes.
  • the fluid and vapour most usually flow in countercurrent; arrangements are also common in which baffles within the shell cause the fluid to flow back and forth across the shell whilst its general progression is longitudinally along the tubes.
  • baffles within the shell cause the fluid to flow back and forth across the shell whilst its general progression is longitudinally along the tubes.
  • each tube offers the same restriction in the path of the vapour flow, and each tube is subject to the same external pattern of thermal distribution, and external fluid flow.
  • the conditions are such that every tube would be expected to sustain the same thermal load, and hence to condense the same amount of vapour. This would not be regarded as a situation likely to lead to maldistribution of vapour among the tubes.
  • the present invention seeks to provide an improved heat transfer process for use in heat exchangers comprising tubes through which a condensing vapour flows in parallel, particularly for those instances where no reason would previously have been foreseen to expect an imbalance of the vapour flow distribution among the tubes.
  • the present invention provides a heat transfer process comprising the steps of
  • a balanced flow of fluid through the tubes can thus be obtained in which the quality of fluid leaving each tube has substantially the same value.
  • the arrangement is such that the quality of fluid leaving each tube is zero.
  • quality is defined herein as the ratio m v /m t where mv is the mass flow rate of vapour in the fluid, and m is the mass flow rate of the total fluid comprising liquid and vapour.
  • mv is the mass flow rate of vapour in the fluid
  • m is the mass flow rate of the total fluid comprising liquid and vapour.
  • the inventor's have found that a particularly effective way of obtaining the desired balanced flow condition, is by the provision in each vapour tube of a fluid flow restrictor.
  • the invention thus resides primarily in the surprising discovery that the performance of in-tube condensing heat exchangers can be improved by providing a fluid flow restrictor in each vapour tube, irrespective of whether there is any apparent cause for maldistribution of vapour.
  • the invention finds application in those cases where the vapour tubes are all such as to offer the same flow resistance under the same conditions of fluid flow therein, and the arrangement is such that each tube is of the same length and subject to the same flow conditions and temperature in the external fluid.
  • vapour When vapour is condensing as it flows along a tube, the pressure drop along the tube may be very small indeed, because the frictional pressure loss is offset by a recovery produced by the deceleration of the flow. Hence the distribution of vapour within the tube bundle will be very sensitve to minor variations in pressure upstream or downstream of the bundle. Thus slight variations of pressure resulting from the upstream pipework, or from variations in the kinetic head of vapour within the inlet header to the tubes can possibly cause significant differences in the flowrates between different tubes. By providing even a mild restriction to the fluid flow in each tube, the total pressure drop in the tube is considerably increased. It is thought probable that the success of the invention results from the fact that the vapour flow distribution is thus rendered far less sensitive to the slight variations inevitably present.
  • the restrictors then advantageously each have the same cross-sectional area for fluid flow.
  • the restrictors are provided in the form of removable inserts.
  • the restrictors are normally most advantageously positioned one at the entry to each vapour tube. Their design is thus simplified in that they will carry vapour only.
  • FIG. 1 there is shown a kettle reboiler comprising an array of vapour tubes 1 within a vessel 2 for containing a liquid to be boiled.
  • a single row of vapour tubes 1 is shown in the plane of the drawing, but the reboiler can include several such rows, eg in parallel planes. All of the vapour tubes are of the same length and cross-sectional area.
  • the vapour tubes can be supplied with vapour through common inlet header 3 having an inlet 4. Fluid leaving the tubes is collected in an outlet header 5 and can flow through an outlet 6.
  • the vessel 2 is provided with an inlet 7 for liquid and an outlet 8 for vapour which can first collect in a vapour space 9.
  • every tube 1 Provided in the inlet end of every tube 1 is a flow restrictor 10, in the form of a removable insert.
  • liquid to be evaporated is supplied to the vessel 2 via the inlet 7, at an appropriate rate to keep all of the tubes 1 immersed therein.
  • Vapour is supplied via the inlet 4 and the'header 5 so as to flow in parallel through the tubes 1.
  • the vapour gives up heat to the liquid through the tube walls, so that the liquid boils in the vessel 2 and the vapour condenses in the tubes 1.
  • the flow of vapour through each tube 1 is virtually the same.
  • the fluid issuing from the downstream ends of the tube consists almost entirely of condensate (quality of about zero), ie little or no vapour issues from the downstream ends of the tubes 1 but vapour is condensing along virtually their entire length so as to maximise the heat transfer to the boiling liquid.
  • the heat transfer rate in a given kettle reboiler has thus been shown in practice to be capable of considerable improvement, resulting from the provision of restrictors 10.
  • the restrictors 10 are readily removed to allow cleaning of the tubes, and can subsequently be replaced without difficulty.
  • FIG 3 there is shown a baffled shell-and-tube heat exchanger comprising an array of vapour tubes 11 within a shell 12.
  • a single row of tubes 11 is shown in the plane of the drawing, but the heat exchanger can include several such rows, eg in parallel planes.
  • Each tube is of the same length and cross-sectional area.
  • the tubes 11 define a number of flow paths through which vapour can flow in parallel from an inlet header 13 having an inlet 14 to an outlet header 15 having an outlet 16.
  • vapour tubes are of the same length and cross-sectional area.
  • Each tube 11 is provided at its inlet with a removable restrictor 10 of the kind shown in Fig 2.
  • the shell is provided with an inlet 17 and an outlet 18. Spaced longitudinally of the shell 12 and extending alternately from its top and bottom are a number of baffles 20. Each baffle extends only partway across the shell, so as to define between inlet and outlet a tortuous flow path whose general direction is longitudinally along the length of the tubes 11.
  • cool liquid to be heated enters the shell 12 via the inlet 17 and leaves via the outlet 18.
  • Vapour such as steam flows via the inlet 14 and the header 15, through restrictors 10, to flow along the tubes 11 in parallel paths, countercurrent to the liquid in the shell.
  • Vapour flows via the inlet 14 and the header 15, through restrictors 10, to flow along the tubes 11 in parallel paths, countercurrent to the liquid in the shell.
  • the vapour flows along the tubes it gives up heat to the cooler liquid in the shell, and condenses.
  • the liquid flows back and forth across the shell its general progression is longitudinally along the tubes, and hence each tube is subject to substantially the same external flow conditions including velocity and temperature distribution.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Geometry (AREA)
  • Thermal Sciences (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
EP83306441A 1982-11-04 1983-10-24 Wärmeübertragungsverfahren Withdrawn EP0110545A1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB8231583 1982-11-04
GB8231583 1982-11-04
GB838307569A GB8307569D0 (en) 1983-03-18 1983-03-18 In-tube condensers
GB8307569 1983-03-18

Publications (1)

Publication Number Publication Date
EP0110545A1 true EP0110545A1 (de) 1984-06-13

Family

ID=26284317

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83306441A Withdrawn EP0110545A1 (de) 1982-11-04 1983-10-24 Wärmeübertragungsverfahren

Country Status (1)

Country Link
EP (1) EP0110545A1 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0489136A1 (de) * 1990-06-25 1992-06-10 Aftec Inc Vorrichtung zur erwärmung und abkühlung von nahrungsmittelartikeln.
WO1996032998A1 (en) * 1995-04-18 1996-10-24 Kvaerner Pulping Ab Falling-film evaporator for spent liquor from chemical pulping, and process for manufacturing tube lamellae in the evaporator
US9562722B2 (en) 2009-03-13 2017-02-07 Carrier Corporation Manifold assembly for distributing a fluid to a heat exchanger

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3229761A (en) * 1963-07-05 1966-01-18 Trane Co Spur tube with alternate oppositely directed orifices
GB1263254A (en) * 1968-08-08 1972-02-09 Foster Wheeler Brown Boilers Improvements in tube and shell heat exchangers
GB1344812A (en) * 1972-09-15 1974-01-23 Banner A Protective inserts for condenser tubes
GB2051596A (en) * 1979-05-23 1981-01-21 Deeg Artur Gas-to-liquid condenser

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3229761A (en) * 1963-07-05 1966-01-18 Trane Co Spur tube with alternate oppositely directed orifices
GB1263254A (en) * 1968-08-08 1972-02-09 Foster Wheeler Brown Boilers Improvements in tube and shell heat exchangers
GB1344812A (en) * 1972-09-15 1974-01-23 Banner A Protective inserts for condenser tubes
GB2051596A (en) * 1979-05-23 1981-01-21 Deeg Artur Gas-to-liquid condenser

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0489136A1 (de) * 1990-06-25 1992-06-10 Aftec Inc Vorrichtung zur erwärmung und abkühlung von nahrungsmittelartikeln.
EP0489136A4 (en) * 1990-06-25 1992-12-09 Aftec, Inc. Apparatus for heating and cooling food articles
WO1996032998A1 (en) * 1995-04-18 1996-10-24 Kvaerner Pulping Ab Falling-film evaporator for spent liquor from chemical pulping, and process for manufacturing tube lamellae in the evaporator
US9562722B2 (en) 2009-03-13 2017-02-07 Carrier Corporation Manifold assembly for distributing a fluid to a heat exchanger

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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AK Designated contracting states

Designated state(s): DE FR GB IT NL SE

17P Request for examination filed

Effective date: 19841205

STAA Information on the status of an ep patent application or granted ep patent

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18W Application withdrawn

Withdrawal date: 19860305

RIN1 Information on inventor provided before grant (corrected)

Inventor name: GRANT, IAN DOUGLAS RAFFAN

Inventor name: HENRY, JOHN ALEXANDER RICHARDSON

Inventor name: COTCHIN, CHARLES DAVID