WO2009016650A1 - Échangeur de chaleur à film tombant perfectionné - Google Patents

Échangeur de chaleur à film tombant perfectionné Download PDF

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Publication number
WO2009016650A1
WO2009016650A1 PCT/IN2008/000300 IN2008000300W WO2009016650A1 WO 2009016650 A1 WO2009016650 A1 WO 2009016650A1 IN 2008000300 W IN2008000300 W IN 2008000300W WO 2009016650 A1 WO2009016650 A1 WO 2009016650A1
Authority
WO
WIPO (PCT)
Prior art keywords
tube
falling film
heat exchanger
tubes
film heat
Prior art date
Application number
PCT/IN2008/000300
Other languages
English (en)
Inventor
Deepak Kumar
Sarjinder Singh Sethi
Original Assignee
Spray Engineering Devices Limited
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
Application filed by Spray Engineering Devices Limited filed Critical Spray Engineering Devices Limited
Publication of WO2009016650A1 publication Critical patent/WO2009016650A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D3/00—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium flows in a continuous film, or trickles freely, over the conduits
    • F28D3/02—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium flows in a continuous film, or trickles freely, over the conduits with tubular conduits
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D1/00—Evaporating
    • B01D1/06—Evaporators with vertical tubes
    • B01D1/065—Evaporators with vertical tubes by film evaporating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D1/00—Evaporating
    • B01D1/30—Accessories for evaporators ; Constructional details thereof

Definitions

  • the field of invention pertains to mechanical engineering. More specifically it pertains to an improved heat exchanger.
  • Calandria Equipment consisting of closely spaced metal tubes for heat exchange.
  • Vertical tube type falling film heat exchangers e.g. evaporators, condensers, evaporative condensers, find application in large number of industries where heat exchange is required.
  • Vertical falling film tube heat exchangers typically include a heat exchanger chamber disposed between upper distribution chamber and a vapour separation chamber below.
  • the heat exchanger chamber has plurality of heat exchange tubes positioned therein which vertically extend between a top tube sheet and a bottom tube sheet.
  • the length of the tubes is 6-15 m, with 8-12 m being used most often. Evaporation occurs on the inner surfaces of tubes as the feed liquid falls as a film on their inner surfaces.
  • the bank of tubes is also referred to as calandria.
  • Feed material enters the upper distribution chamber through a feed inlet associated therewith and is directed downwardly through the vertical heat exchange tubes in the form of a falling film in a manner ensuring that the tubes receive approximately equal flows.
  • Vapour-liquid separation usually takes place at the bottom, although some evaporators of this type are arranged for vapour to rise through the tube counter-currently to the liquid.
  • the uniform distribution of the feed liquid is achieved by use of specially designed distribution devices whose proper functioning is decisive to the operational safety of the heat exchanger.
  • Numerous structures and devices are known for improving the distribution of the liquid, such devices generally being placed either on the top of tube bundle or inserted or screwed into the tubes.
  • the former type of distributors i.e. liquid feed distributor mounted on top of the tube bundle
  • the liquid falls on the tube sheet and then flows into the tubes (flush welded with the tube sheet) in the form of a film.
  • the feed liquid overflows over the upper edge of the protrusion which may be serrated or toothed.
  • the protrusion may also be slotted or provided with grooves or borings or depressions or the like.
  • the aim is to achieve the maximum performance in apparatus of minimum size.
  • One approach is to provide maximum heating surface in minimum possible area.
  • use of finned or fluted tubes has been the most common.
  • the design of the finned or fluted tubes is also adapted to increase the velocity of the descending liquid thereby increasing the heat transfer coefficient.
  • Another means to achieve the maximum heating surface in a given area is through the use of honeycomb calandria in which the calandria tubes are expanded to a hexagon at their ends and are welded directly to each other without the use of a tube plate in the form of a honey comb.
  • the honey comb calandria provides the following distinct advantages:
  • honey comb calandria has found wide application especially in calandria tube evaporators (Robert evaporators) and rising film tube evaporators (Kestner evaporators) especially in sugar industry since the feed enters at the bottom, there is no problem of uniform feed liquid distribution to all the tubes.
  • Robert evaporators are generally restricted to about 3000 m 2 each, as the diameter gets too large. Moreover, due to large liquid hold up, these evaporators cannot be used with heat sensitive materials.
  • the rising film unit requires a driving film force, typically a temperature difference of at least 14 deg. C across the heating surface.
  • the falling film unit does not have a driving force limitation-permitting a greater number of evaporator effects to be used within the same overall operating limits. In other words, the rising film evaporator requires a larger minimum delta T than a falling film unit.
  • the hydrostatic head may create problem with heat sensitive products. The pressure drop is higher than for falling film types and there is a tendency to scale.
  • honey comb calandria in vertical falling film tube heat exchangers is restricted mainly owing to: a) difficulty in all important uniform and adequate liquid distribution due to absence of intermediate space between the tubes, and - A - b) secondly, the tube length cannot be kept long due to difficulty in providing support to the unsupported length of the tubes.
  • honey comb calandria henceforth considered as limitations for their application in vertical tube falling film heat exchangers are overcome through the use of a simple but novel tube extension resulting in an improved vertical tube falling film heat exchanger.
  • the invention discloses a simple but novel tube extension for heat exchange tubes of a calandria having ends expanded in the form of a hexagon or any other angular form, which permits the use of honeycomb calandria (used widely in short tube calandria evaporators and rising film evaporators) in vertical falling film tube heat exchangers in a simple, efficient and inexpensive manner resulting in an improved vertical tube falling film heat exchanger.
  • the novel tube extension results in complete elimination of separate liquid distributor means always required to be interposed between the vertical tube bundles in superimposed configurations. This has been achieved through the use of a substantially inverted funnel shaped tube extension of the end of the heat exchange tube which in use is its upper end.
  • the said extension functions as an integral distribution device for vertical falling film tube heat exchanger. Alternatively, it can also function as a receptacle for distribution devices which are inserted or screwed into the tubes without any design modification.
  • the invention provides an improved vertical tube falling film heat exchanger, comprising: a single bank or multiple superimposed interspaced banks of vertical tubes within a housing, the said vertical tubes sealed at the hexagonally or other angularly expanded ends or regions and forming said tube bank; means for heating the said tube banks; liquid distribution means; means for removal and/or directional flow of vapours; means for removal and/or directional flow of condensate and non-condensed gases; means for liquid recirculation;
  • the improvement comprises of a substantially inverted funnel shaped extension at the upper ends of the vertical tubes, whereby the said extension permits the use of honeycomb calandria in the vertical tube falling film heat exchangers by ensuring uniform liquid distribution in the vertical tubes and completely eliminating the need of a separate distribution means interposed between superimposed banks of vertical tubes.
  • Fig. 1 is the schematic isometric representation of a bank or bundle of vertical tubes incorporating the novel tube extension of the invention.
  • Fig. 2 is the enlarged sectional view of the area shown in circle A in Fig. 1
  • Fig. 3 shows a schematic sectional elevation view of one embodiment of an apparatus constructed according to this invention.
  • Fig. 4 is an enlarged schematic sectional elevation view of the top two stages of the apparatus shown in Fig. 3.
  • the invention provides a novel tube extension of a calandria tube having its ends expanded in the form of a hexagon or any other angular form, characterized by the fact that the end of the said calandria tube which in use is its upper end comprises of a substantially inverted funnel shaped extension with a predetermined length and diameter of the tubular portion of the said extension.
  • the said extension functions as an integral distribution device for each bank of vertical tubes in a falling film heat exchanger by permitting the liquid to accumulate around it, reach a certain level and then enter each tube individually and uniformly.
  • the upper edges of the tubular portion of the said extension may be serrated or toothed. It may also be slotted or provided with grooves or borings or depressions or the like or of any other desired configuration. Alternatively, it can also function as a receptacle for distribution devices which are fitted into the tubes without any design modification.
  • such modified tube design being simple is easy to manufacture and allows negligible wastage of raw material in its manufacture.
  • Fig. 1 is the schematic isometric representation of a bank or bundle 1 of vertical tubes 2 incorporating the novel tube extension 3 of the invention.
  • Fig. 2 is the enlarged sectional view of the area of the tube bundle shown in dotted circle A in Fig. 1 clearly showing the novel tube extension 3 in detail.
  • the said tube extension 3 of a calandria tube 2 having its ends expanded in the form of a hexagon or any other angular form is characterized by the fact that the end of the said heat exchanger tube 2 which in use is its upper end is comprised of a substantially inverted funnel shaped extension 3.
  • the said extension 3 has a lower substantially conical portion 4 and an upper tubular portion 5 at the top end of each calandria tube 2.
  • the said extension 3 functions as an integral distributing device for a vertical tube falling film heat exchanger.
  • the ends of the tubular portion 5 of the said extension 3 may be serrated or toothed or of any other desired configuration. Alternatively, it can serve as a receptacle for fitting a distribution device for vertical tube falling film heat exchangers.
  • the tubes 2 are sealed directly to each other without the use of tube plate at the hexagonally 6 or other angularly expanded zones.
  • the height and diameter of the tubular portion 5 of the substantially inverted funnel shaped extension 3 is determined according to the operational requirements.
  • the diameter of the said tubular region 5 is the same as the diameter of the heat exchanger tube 2 in the section between the expanded hexagonal zones 6.
  • ⁇ dimensions of the intermediate region 7 between the novel tube extensions 2 of the invention depend upon the dimensions of both the substantially conical section 4 and the tubular portion 5 of the said novel extension 3.
  • This intermediate region 7 functions as a ' collector or reservoir for the liquid.
  • the length of the tubular region 5 is determined by the head of the liquid required to be maintained thereon to regulate liquid flow and distribute the liquid.
  • Fig. 3 shows a schematic sectional elevation view of an embodiment of an apparatus constructed according to this invention.
  • Fig. 4 is an enlarged view of the top portion of the apparatus shown in Fig. 3 showing upper two stages. It highlights the advantages of the invention in superimposed configurations.
  • a multiplicity of super-imposed banks 1 of vertical tubes 2 or stages is arranged in a cylindrical housing 8. The said stages may be operated in a single-effect as shown in Fig. 3 or in a multi-effect mode.
  • the means of heating comprise a common steam conduit 9 interconnecting the steam-side 10 of the said multiplicity of superimposed banks 1 of vertical tubes 2 or stages in parallel. More of such single-effect units may also be applied in a multiple-effect arrangement.
  • the tube bundles 1 may or may not have a casing depending upon the arrangement and design of the apparatus. Many such designs and arrangements are known in the prior art.
  • a vapour space 11 vertically separates from one another said multiplicity of vertically stacked bundles 1 of vertical tubes 2 mounted within a single vessel 8 without any further distributor means interposed between them. If operated as a single effect the said vapour space 11 is connected to condenser means 12 for condensing the said vapour.
  • a common entrainment separator (not shown) may also be provided in the passage of vapours from the vapour space to condensing means.
  • known means may be used for connecting the effects whereby in use vapour produced in one effect can flow into the next above or below it for condensation therein.
  • Known means may also be used for removal or to facilitate directional flow of the condensate 13 and non-condensed gases 14.
  • the liquid to be treated may be once distributed through any conventional distributor means 15 over the topmost tube bundle 1.
  • the liquid flows over the periphery of the said novel tube extension 3 forming a film on the inner surface of the tubes 2.
  • the operational problems associated with conventionally interposed distributors are also thus totally avoided.
  • Means may also be provided for addition of feed liquid at any stage (when operated as a single effect) or in any effect (when operated in multi-effect mode).
  • the advantage of addition of feed liquid at multiple stages or effects in comparison to single distribution once at the top is that a lower flow rate is required. This prevents the formation of a thick liquid film in the upper portions of the tubes ensuring high heat transfer coefficient.
  • removal of condensate 13 in intermediate stages prevents formation of thick condensate layer as is formed in case of a conventional single long tube again benefiting the heat transfer characteristics.
  • the removal of vapours also becomes easy and with a lesser energy expenditure. All these benefits have become economically viable owing to 5 the use of novel tube extension 3 of the invention resulting in the elimination of separate liquid distributor means always required to be interposed between the vertically stacked tube bundles 1.
  • Liquid recirculation means 16 may also be provided.
  • liquid lanes are provided. These liquid lanes correspond to and overlie the steam lanes which are provided for even distribution of the steam or vapours especially in honeycomb calandria. While being advantageous for initial liquid distribution in the uppermost stage, the said liquid distribution lanes aid in uniform distribution of the feed liquid added in the lower stages or effects.
  • the collector or reservoir formed by the 5 intermediate spaces 7 between the novel tube extensions 3 is also provided with a level controlling means.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

Abstract

L'invention concerne un échangeur de chaleur à film tombant et à tubes verticaux, perfectionné, le perfectionnement consistant en une extension de tube (3), simple mais nouvelle, d'une configuration en forme d'entonnoir sensiblement inversé au niveau des extrémités supérieures des tubes verticaux (2). Ladite extension (3) permet l'utilisation d'une calendre en nid d'abeilles dans les échangeurs de chaleur à film tombant et à tubes verticaux en garantissant une distribution de liquide uniforme dans les tubes verticaux (2), et élimine totalement le besoin de moyens de distribution séparés interposés entre des séries superposées de tubes verticaux.
PCT/IN2008/000300 2007-08-02 2008-05-14 Échangeur de chaleur à film tombant perfectionné WO2009016650A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IN1641DE2007 2007-08-02
IN1641/DEL/2007 2007-08-02

Publications (1)

Publication Number Publication Date
WO2009016650A1 true WO2009016650A1 (fr) 2009-02-05

Family

ID=40303926

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IN2008/000300 WO2009016650A1 (fr) 2007-08-02 2008-05-14 Échangeur de chaleur à film tombant perfectionné

Country Status (1)

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WO (1) WO2009016650A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3112793A1 (fr) 2015-06-24 2017-01-04 Commissariat à l'énergie atomique et aux énergies alternatives Dispositif de distribution de film tombant sur un échangeur à plaques comprenant des premier et deuxième étages de distribution
CN113545660A (zh) * 2021-06-21 2021-10-26 广东美的厨房电器制造有限公司 一种烹饪装置

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2033960A1 (de) * 1970-07-08 1972-01-20 Teledyne Industries, Ine , Los Ange les,Cahf (VStA) Mehrstufiges geschichtetes Dampfkuhl system mit geschlossenem Kreislauf fur Brennkraftmaschinen
DE4325171A1 (de) * 1993-07-27 1995-02-02 Bayerische Motoren Werke Ag Dampf-/Luftwärmetauscher

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2033960A1 (de) * 1970-07-08 1972-01-20 Teledyne Industries, Ine , Los Ange les,Cahf (VStA) Mehrstufiges geschichtetes Dampfkuhl system mit geschlossenem Kreislauf fur Brennkraftmaschinen
DE4325171A1 (de) * 1993-07-27 1995-02-02 Bayerische Motoren Werke Ag Dampf-/Luftwärmetauscher

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3112793A1 (fr) 2015-06-24 2017-01-04 Commissariat à l'énergie atomique et aux énergies alternatives Dispositif de distribution de film tombant sur un échangeur à plaques comprenant des premier et deuxième étages de distribution
CN113545660A (zh) * 2021-06-21 2021-10-26 广东美的厨房电器制造有限公司 一种烹饪装置

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