EP0396868A1 - Heat exchanger for cooling cracking gases - Google Patents

Heat exchanger for cooling cracking gases Download PDF

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Publication number
EP0396868A1
EP0396868A1 EP19900104494 EP90104494A EP0396868A1 EP 0396868 A1 EP0396868 A1 EP 0396868A1 EP 19900104494 EP19900104494 EP 19900104494 EP 90104494 A EP90104494 A EP 90104494A EP 0396868 A1 EP0396868 A1 EP 0396868A1
Authority
EP
European Patent Office
Prior art keywords
heat exchanger
tube
cracked gas
gas
cooling
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.)
Granted
Application number
EP19900104494
Other languages
German (de)
French (fr)
Other versions
EP0396868B1 (en
Inventor
Wolfgang Kehrer
Thomas Schreck
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.)
Deutsche Babcock Borsig AG
Original Assignee
Deutsche Babcock Borsig AG
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 to DE19893913731 priority Critical patent/DE3913731A1/en
Priority to DE3913731 priority
Application filed by Deutsche Babcock Borsig AG filed Critical Deutsche Babcock Borsig AG
Publication of EP0396868A1 publication Critical patent/EP0396868A1/en
Application granted granted Critical
Publication of EP0396868B1 publication Critical patent/EP0396868B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D7/00Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
    • F28D7/16Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28FDETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F13/00Arrangements for modifying heat-transfer, e.g. increasing, decreasing
    • F28F13/06Arrangements for modifying heat-transfer, e.g. increasing, decreasing by affecting the pattern of flow of the heat-exchange media
    • F28F13/08Arrangements for modifying heat-transfer, e.g. increasing, decreasing by affecting the pattern of flow of the heat-exchange media by varying the cross-section of the flow channels
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D21/00Heat-exchange apparatus not covered by any of the groups F28D1/00 - F28D20/00
    • F28D2021/0019Other heat exchangers for particular applications; Heat exchange systems not otherwise provided for
    • F28D2021/0075Other heat exchangers for particular applications; Heat exchange systems not otherwise provided for for syngas or cracked gas cooling systems
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S165/00Heat exchange
    • Y10S165/903Convection
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S585/00Chemistry of hydrocarbon compounds
    • Y10S585/949Miscellaneous considerations
    • Y10S585/95Prevention or removal of corrosion or solid deposits

Abstract

A heat exchanger for cooling cracked gas is provided with a bundle of heat exchanger tubes (1). Each heat exchanger tube (1) has two tube sections (10, 11) of different diameters which merge into one another via a cone (12). The pipe section (11) with the larger diameter is provided at the gas outlet end of the heat exchanger pipe (1).

Description

  • The invention relates to a heat exchanger for cooling cracked gas with the features of the preamble of claim 1.
  • The cracked gas generated by thermal cracking of hydrocarbons with the addition of water vapor is a mixture of hydrocarbons of different molecular weights and partial pressures. This fission gas must be cooled very quickly from about 800 to 900 degrees C to 600 to 650 degrees C to stabilize its molecular composition. The cracked gas is cooled by indirect heat transfer from the cracked gas to the evaporating water serving as the heat-absorbing medium. In order to maintain the high cooling rate, the cracked gas must flow through the heat exchanger tubes at high speed. The further cooling of the cracked gas from 600 to 650 degrees C to 450 to 380 degrees C depending on the starting material is carried out for heat recovery and has only a minor influence on the quality of the cracked gas. This subsequent cooling can be carried out at lower flow rates.
  • In addition to a sufficiently high cooling rate, the gas-side pressure in the tubes of the cracking gas furnace and the cracking gas cooler also has an influence on the quality of the cracked gas generated. A low pressure drop in the cracked gas cooler leads to a lower pressure in the cracked gas furnace, which increases the yield of ethylene. In practice, therefore, an optimization between flow velocity and pressure loss in the flowing cracked gas is sought.
  • Shell and tube heat exchangers are used as cracked gas coolers, which cool the gas in one go from 800 degrees C to 400 degrees C. A correspondingly low flow rate is maintained in the heat exchanger tubes. Such a heat exchanger is simple in construction, but the cooling rate, at least in the inlet part, could be too slow with regard to the stabilization of the desired fission gas composition.
  • Two-stage heat exchanger systems are also known, which are usually designed as single-tube coolers and which cool the cracked gas at a higher flow rate from 800 ° C to 500 ° C. A separate heat exchanger is installed downstream of these coolers, in which the cracked gas is cooled to 400 degrees C at a lower flow rate. Such a heat exchanger system increases the outlay on equipment considerably.
  • Finally, the tendency of the heat exchanger tubes to become dirty must be taken into account, which is dependent on pressure and temperature. Such contamination occurs when, in the region of the lower temperatures, the condensation temperature of individual cracked gas components, which is dependent on the partial pressure, leads to their deposition on the inner wall of the pipe. A so-called coke layer builds up, which increases the flow resistance and thus the pressure. The gas temperature at the end of the gas outlet rises and the steam generation decreases. After a certain operating time, the cracked gas cooler must be taken out of operation to remove the coke layer.
  • In order to slow down the build-up of a coke layer, it is known not to let the pipe wall temperature drop below the condensation temperature of the cracked gas components. This is done, for example, by a two-stage cooling, in which water evaporating in the inlet part and steam in the outlet part or in a separate apparatus is used as the heat exchange medium (DE-PS 36 43 801). It is also known to reduce the cooling effect in the outlet part of the cracked gas cooler in that the heat exchanger tubes are surrounded at the gas outlet end by a sleeve through which a limited amount of evaporating water flows (DE-PS 37 15 713).
  • The invention has for its object to design the generic heat exchanger for cooling cracked gas in such a way that on the one hand the apparatus simplicity of a single-stage cooling is maintained and that on the other hand the advantages of a two-stage cooling with variable flow rates can be exploited.
  • This object is achieved in a generic heat exchanger according to the invention by the characterizing features of claim 1. Advantageous embodiments of the invention are specified in the subclaims.
  • With this heat exchanger, a high flow rate necessary for the rapid cooling of the cracked gas can be set in the input part due to the smaller pipe diameter. The build-up of a coke layer is permitted in the part on the gas outlet side, but this affects the operation of the cracked gas cooler less due to the larger pipe diameter. Because of the larger pipe diameter, the flow resistance and the gas outlet temperature increase less compared to a narrower pipe. As a desired side effect, the slowing of the flow velocity in the conical pipe section recovers part of the static pressure of the cracked gas.
  • An embodiment of the invention is shown in the drawing and is explained in more detail below. The drawing shows schematically the longitudinal section through a heat exchanger.
  • The heat exchanger shown is connected to a cracked gas furnace and is used to cool the cracked gas generated. The heat exchanger contains a bundle of heat exchanger tubes 1, of which only two are shown for reasons of clarity. The heat exchanger tubes 1 are inserted at the ends in a tube sheet 2, 3. The tube sheets 2, 3 are connected to a jacket 4, which encloses the bundle of heat exchanger tubes 1. The jacket 4 is provided with a feed connector 5 and a discharge connector 6, via which a heat exchange medium is fed into the interior of the jacket 4 and is removed therefrom. Evaporating water serves as the heat exchange medium.
  • The heat exchanger tubes 1 connect a gas inlet chamber 7 to a gas outlet chamber 8, which are delimited by a hood 9 and in each case one of the tube plates 2, 3. The cracked gas generated in the cracked gas furnace is fed to the gas inlet chamber 7.
  • Each heat exchanger tube 1 has two tube sections 10, 11 which are connected to one another by a cone 12. The cone angle is preferably 6 to 8 degrees. The diameter of the pipe section 10 facing the gas inlet chamber 7 is smaller than the diameter of the pipe section 11 on the gas outlet side. The diameter of the pipe section 10 can for example be 31 or 38 mm and the diameter of the pipe section 11 can be 42 or 48 or 51 mm. With a wall thickness of the heat exchanger tubes 1 of 3 or 5 mm, the selected example results in an increase in the area of the clear tube cross section from 1 to 1.6 to 1.8. In general, the cross-sectional enlargement should be between 1 to 1.5 to 2.0.

Claims (3)

1. Heat exchanger for cooling cracked gas with a bundle of heat exchanger tubes (1) through which the cracked gas flows, held at their ends in tube plates (2, 3) and surrounded by a jacket (4) which together with the tube plates (2 , 3) encloses an interior space filled with evaporating water, characterized in that each heat exchanger tube (1) has two tube sections (10, 11) of different diameters which merge into one another via a cone (12), and in that the tube section (11) with the Larger diameter is provided at the gas outlet end of the heat exchanger tube (1).
2. Heat exchanger according to claim 1, characterized in that the ratio of the cross-sectional areas of the pipe sections (10, 11) is 1 to 1.5 to 2.0, preferably 1 to 1.6 to 1.8.
3. Heat exchanger according to claim 1 and 2, characterized in that the cone angle of the cone (12) is 6 to 8 degrees.
EP19900104494 1989-04-26 1990-03-09 Heat exchanger for cooling cracking gases Expired - Lifetime EP0396868B1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE19893913731 DE3913731A1 (en) 1989-04-26 1989-04-26 Heat exchanger for cooling fuse gas
DE3913731 1989-04-26

Publications (2)

Publication Number Publication Date
EP0396868A1 true EP0396868A1 (en) 1990-11-14
EP0396868B1 EP0396868B1 (en) 1992-12-23

Family

ID=6379493

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900104494 Expired - Lifetime EP0396868B1 (en) 1989-04-26 1990-03-09 Heat exchanger for cooling cracking gases

Country Status (5)

Country Link
US (1) US5031692A (en)
EP (1) EP0396868B1 (en)
JP (1) JPH031092A (en)
DE (1) DE3913731A1 (en)
ES (1) ES2038008T3 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2968388A1 (en) * 2010-12-07 2012-06-08 Valeo Systemes Thermiques Heat exchanger, in particular for a motor vehicle
EP2063207B1 (en) * 2007-10-10 2014-02-19 Bomat Heiztechnik GmbH Combustion plat with heat exchanger

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5464057A (en) * 1994-05-24 1995-11-07 Albano; John V. Quench cooler
DK173540B1 (en) * 1994-06-29 2001-02-05 Topsoe Haldor As Waste heat boiler
DE4431135C2 (en) * 1994-09-01 2003-02-13 Johann Himmelsbach Shell and tube heat exchangers for heat exchange with a pulsating flow medium
EP1350560A1 (en) * 2002-04-05 2003-10-08 Methanol Casale S.A. Plate-type heat exchange unit for catalytic bed reactors
DE102006003317B4 (en) * 2006-01-23 2008-10-02 Alstom Technology Ltd. Tube bundle heat exchanger
DE102006055973A1 (en) * 2006-11-24 2008-05-29 Borsig Gmbh Heat exchanger for cooling cracked gas
AT525618T (en) * 2007-07-05 2011-10-15 Ib Ntec Thermodynamic system with a device for generating heat through the hills of a fluid under pressure through several pipes
US7802985B2 (en) * 2007-10-25 2010-09-28 Alan Cross Direct fired heater utilizing particulates as a heat transfer medium

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1501484A1 (en) * 1966-04-29 1969-10-23 Christian Carl Fa Durchlaufkuehler
DE1929474A1 (en) * 1969-02-27 1970-09-17 Stone & Webster Eng Corp Apparatus for Heat exchanging or for cooling hot, flowing substance and Kuehlverfahren
EP0002687A1 (en) * 1977-12-24 1979-07-11 Küppersbusch Aktiengesellschaft Apparatus using heat exchange

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1948541A (en) * 1929-12-16 1934-02-27 Bbc Brown Boveri & Cie Heater system
US2740803A (en) * 1950-01-19 1956-04-03 Ruhrchemie Ag Catalytic hydrogenation of carbon monoxide with indirect heat exchange cooling
US4248834A (en) * 1979-05-07 1981-02-03 Idemitsu Petrochemical Co. Ltd. Apparatus for quenching pyrolysis gas
US4279734A (en) * 1979-12-21 1981-07-21 Shell Oil Company Quench Process
US4405440A (en) * 1982-11-22 1983-09-20 Shell Oil Company Process for maintaining the temperature of a steam-making effluent above the dew point

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1501484A1 (en) * 1966-04-29 1969-10-23 Christian Carl Fa Durchlaufkuehler
DE1929474A1 (en) * 1969-02-27 1970-09-17 Stone & Webster Eng Corp Apparatus for Heat exchanging or for cooling hot, flowing substance and Kuehlverfahren
EP0002687A1 (en) * 1977-12-24 1979-07-11 Küppersbusch Aktiengesellschaft Apparatus using heat exchange

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2063207B1 (en) * 2007-10-10 2014-02-19 Bomat Heiztechnik GmbH Combustion plat with heat exchanger
FR2968388A1 (en) * 2010-12-07 2012-06-08 Valeo Systemes Thermiques Heat exchanger, in particular for a motor vehicle
EP2463610A1 (en) * 2010-12-07 2012-06-13 Valeo Systemes Thermiques Heat exchanger, in particular for an automobile

Also Published As

Publication number Publication date
JPH031092A (en) 1991-01-07
EP0396868B1 (en) 1992-12-23
DE3913731A1 (en) 1990-10-31
US5031692A (en) 1991-07-16
ES2038008T3 (en) 1993-07-01

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