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
  • F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
  • F28F13/06—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by affecting the pattern of flow of the heat-exchange media
  • F28F13/12—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by affecting the pattern of flow of the heat-exchange media by creating turbulence, e.g. by stirring, by increasing the force of circulation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
  • B01D5/0003—Condensation of vapours; Recovering volatile solvents by condensation by using heat-exchange surfaces for indirect contact between gases or vapours and the cooling medium
  • B01D5/0006—Coils or serpentines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
  • B01D5/0003—Condensation of vapours; Recovering volatile solvents by condensation by using heat-exchange surfaces for indirect contact between gases or vapours and the cooling medium
  • B01D5/0012—Vertical tubes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
  • B01D5/0003—Condensation of vapours; Recovering volatile solvents by condensation by using heat-exchange surfaces for indirect contact between gases or vapours and the cooling medium
  • B01D5/0015—Plates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
  • B01D5/0033—Other features
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
  • B01D5/0057—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes
  • B01D5/0072—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes with filtration
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B17/00—Sulfur; Compounds thereof
  • C01B17/69—Sulfur trioxide; Sulfuric acid
  • C01B17/74—Preparation
  • C01B17/76—Preparation by contact processes
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B17/00—Sulfur; Compounds thereof
  • C01B17/69—Sulfur trioxide; Sulfuric acid
  • C01B17/74—Preparation
  • C01B17/76—Preparation by contact processes
  • C01B17/775—Liquid phase contacting processes or wet catalysis processes
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B17/00—Sulfur; Compounds thereof
  • C01B17/69—Sulfur trioxide; Sulfuric acid
  • C01B17/74—Preparation
  • C01B17/76—Preparation by contact processes
  • C01B17/80—Apparatus
  • C01B17/806—Absorbers; Heat exchangers
• • 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
  • F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
  • F28D7/16—Heat-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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F21/00—Constructions of heat-exchange apparatus characterised by the selection of particular materials
  • F28F21/006—Constructions of heat-exchange apparatus characterised by the selection of particular materials of glass
• • 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
  • F28F9/22—Arrangements for directing heat-exchange media into successive compartments, e.g. arrangements of guide plates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/26—Drying gases or vapours
  • B01D53/265—Drying gases or vapours by refrigeration (condensation)

Definitions

• the present invention relates to a condenser for sulphuric acid having an increased gas flow capacity.
• the WSA process has proven its value in industries like oil refining, metallurgy, petrochemicals production, coking, coal gasification, non-ferrous roasters and smelters, power plants and production of viscose fibers.
• Oleum may be produced from a gas with a deficit of water compared to sulphur trioxide (less than one mole of water per mole of sulphur trioxide) or by subsequently absorbing sulphur trioxide in the produced sulphuric acid.
• the capacity of a condenser was considered a function of the number of tubes provided in the condenser. With twice the number of tubes, the flow area will be doubled, and thus the associ ⁇ ated flow capacity will be doubled.
• the limiting factor for the glass tube condenser capacity is the heat exchange capacity - i.e. how much gas that ef ⁇ fectively may be cooled in the condenser.
• the tube length has been evaluated according to whether the removal of sulphur trioxide and sulphuric acid was suffi ⁇ cient .
• the tube length can be used also to increase the flow capa ⁇ city of a tube, since an increase in tube length will also increase the tube surface area, and thus the heat transfer area. The same heat transfer contact time can therefore be obtained with a higher flow rate, and therefore an in- creased process gas capacity per tube proportional to the tube length was expected.
• challenges relating to production and handling of the glass tubes are also increased, and there- fore glass tubes for sulphuric acid condensers have only been produced in 6 m and 7 m lengths corresponding to an active cooling zone of 5.45 m or 6.45 m.
• gas flow capacity of a condenser tube shall be understood as the mass flow rate of process gas in a tube, which allows sufficient cooling of the process gas.
• process gas is to be understood as a gas comprising sulphur trioxide and water.
• cooling medium is to be understood as a me ⁇ dium used for heat transfer without significant chemical reaction such as air.
• a cooling medium may in a different position in the process also be involved in chemical reac ⁇ tions .
• cooling zone shall be understood as a sec- tion of tube which is configured for having its outer surface contacted with a cooling medium during operation.
• concentrations of sulphur trioxide in gas form are stated as mole% under the assumption that all hexavalent sulphur is present as sulphur trioxide, and therefore it includes sulphur trioxide as well as sulphur trioxide hydrated to gaseous sulphuric acid.
• the present invention provides a condenser for condensing vapours of sulphuric acid contained in a process gas com ⁇ prising a tube of an acid resistant material configured for having a process gas inlet proximate to one end, a process gas outlet proximate to the other end and an acid outlet proximate to the bottom end, said tubes configured for ex- tending through a cooling zone and said cooling zone configured for having a cooling medium inlet and a cooling medium outlet, for a gaseous cooling medium being passed counter-currently to the process gas, characterized in that the tube has a length of 7.5 m to 12 m, a tube of an acid resistant material, configured for having a process gas inlet proximate to one end, a process gas outlet proximate to the other end and an acid outlet proximate to the bottom end, said tubes configured for extending through a cooling zone and said cooling zone configured for having a cooling medium inlet and a cooling medium outlet for a gaseous cooling medium being passed counter-
• ⁇ ing a high velocity aerosol filter mounted in substantially tight connection with the condenser tube in the end of the cooling zone proximate to the process gas outlet, said fil ⁇ ter comprising fibres or filaments with a diameter of 0.05 to 0.5 mm, the fibres or filaments so being present in an amount, a layer thickness and a configuration such as to ensure that the pressure drop through the filter at a gas velocity of 1-7 m/sec will be between 2 and 20 mbar with the associated benefit that acid mist is condensed as drop ⁇ lets by contact with the aerosol filter.
• the present disclosure further comprises a turbulence generation means inside the tube, such as a spiral, glass indents or glass protrusions with the associated benefit that increased turbulence increases the heat transfer at the inner tube surface.
• a turbulence generation means inside the tube such as a spiral, glass indents or glass protrusions with the associated benefit that increased turbulence increases the heat transfer at the inner tube surface.
• the present disclosure is further configured for having a re-heating zone proximate to the process gas outlet with the associated benefit of providing a process gas downstream the condenser, having a temperature above the sulphuric acid dew point, and thus substan ⁇ tially without presence of corrosive liquid sulphuric acid.
• the present disclosure is further configured for the condensed sulphuric acid flowing
• the present disclosure is config- ured for the condensed sulphuric acid flowing co-currently with the process gas in the condenser by configuring the process gas inlet to be proximate to the top end of the tube with the associated benefit of reducing the risk of flooding in the condenser tube and in the demister.
• the con ⁇ denser comprises multiple condenser tubes having a distance between tubes of at least 1/3 of the tube diameter with the associated benefit of a lower pressure drop on the cooling medium side of the condenser.
• the present disclosure relates to a process with two sulphuric acid condensers in series with an intermediate sulphur dioxide oxidation step with the as ⁇ sociated benefit of treating process gases with an extra high concentration of sulphur trioxide or with an extra low sulphur dioxide emission.
• the present disclosure relates to a process with two sulphuric acid condensers in series with the first condenser operating with a deficit of water compared to the sulphur trioxide (less than one mole of water per mole of sulphur trioxide) and the second downstream condenser operating with a surplus of water compared to sulphur trioxide (more than one mole of water per mole of sulphur trioxide) with the associated benefit that oleum can be produced in the first upstream condenser.
• the diameter of the condenser tube may range from 20 to 70 mm, preferably between 25 and 60 mm and even more preferably between 30 and 50 mm.
• the process gas contains less than 2.0 % sulphur trioxide, and preferably less than 1.0 % sulphur trioxide with the associated benefit of an even increased super proportional effect of tube length with low concentrations of sulphur trioxide.
• FIG. 1 shows a condenser according to the present disclo ⁇ sure .
• the present disclosure relates to a condenser 2, in which a process gas 20 flows inside tubes 4 and a cooling medium 22 flows outside the tubes 4.
• the inside of the condenser tubes 4 can be equipped with a spiral 8 or other turbu ⁇ lence-enhancing element.
• the tubes 4 can be made from glass, such as borosilicate glass, and are connected to the process gas inlet of the condenser by means of a bottom plate 10 having substantially airtight contact with the outside of the tubes 4 and their position is stabilised by baffle plates 12 across the condenser on the cooling medium side.
• baffle plates 12 At the process gas outlet 16 from the condenser, the tubes 4 are fixed and sealed against a top plate 14.
• the cooling medium can be at a slightly higher pressure than the process gas to avoid leaks of corrosive process gas to the cooling medium side.
• an op ⁇ tional aerosol filter 30 may also be present.
• the typical length of the cool ⁇ ing section of the tubes has been 4 to 6.5 m with the corresponding length of the tubes being 5 to 7 m.
• the tubes are 7.5 m or longer.
• the increased flow rate of cooling medium also increases the heat trans ⁇ fers on the outside of the tubes and thus contributes fur ⁇ ther to the super-proportional effect with respect to the tube length, while maintaining the ratio between the mass flows of process gas and cooling medium. Therefore, with increased tube length a surprising super-proportional in ⁇ crease of the heat transfer due to an increased flow rate of process gas and cooling medium is observed.
• the flooding limit in the demister may be increased by increasing the demister diameter or by using a more open demister material with a higher void fraction. It is also preferred to balance the flow rate, the tube diameter of the demister section and the void fraction of the demister such that the linear flow rate is in the range 1-7 m/sec, and the associated demister pressure drop is less than 20 mbar.
• An upper limit of the increased flow rate inside the tubes exists due to potential flooding in the condenser tube i.e. the effect that with an increasing flow rate of gas, the condensed sulphuric acid may be drawn upwards and out of the glass tubes by the gas flow.
• the flooding limit inside the tubes may be increased by increasing the tube diameter or altering the shape or size of any turbulence generation means installed inside the tubes.
• the pressure drop over the condenser on the cooling medium side will also increase.
• the distance between condenser tubes may be increased.
• an optional demister may be posi ⁇ tioned at the exit of the cooling section of the condenser tube to prevent acid mist from leaving the condenser.
• This demister may preferably be positioned in a zone of the con ⁇ denser tube having a larger diameter to provide a demister zone with minimal pressure drop, which otherwise may be an increasing problem with increased gas flow rate.
• a further embodiment involves a condenser in which the process gas is re-heated in the last part of the condenser, such that corrosive liquid sulphuric acid not captured in the condenser is evaporated, and the risk of corrosion is reduced in the downstream equipment.
• the heat exchange was evaluated for compositions with 12% 0 2 , 2% C0 2 , 7-10% H 2 0, 1.0%-5.5% S0 3 and N 2 as balance.
• the flow was adjusted to obtain the same cooling medium outlet tempera ⁇ ture.
• the cooling medium outlet temperature varied slightly between the three investigated SO 3 concentrations. From Table 1 it is clearly seen that with increased tube length the flow may be increased to a higher extent than that expected from an assumption of proportionality.
• the pressure drop is 16-200 mbar and it is as ⁇ sumed that a pressure drop below 100 mbar is acceptable, but for higher pressure drops there may be a need for coun- teracting the pressure drop by increasing the pitch, i.e. the distance between tubes in the condenser.
• the pressure drop in the tube ranges from 5 to 200 mbar.
• the pressure drop may be problematic already from values around 60 mbar, and there ⁇ fore the tube diameter may have to be increased already with flows around 30 Nm 3 /h per tube.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Inorganic Chemistry (AREA)
• Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
• Drying Of Gases (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

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Citations (10)

• 2012
  • 2012-06-04 WO PCT/EP2012/060514 patent/WO2012171824A1/en active Application Filing
  • 2012-06-04 EA EA201490001A patent/EA027599B1/ru not_active IP Right Cessation
  • 2012-06-15 CN CN201220282614XU patent/CN202945060U/zh not_active Expired - Lifetime
  • 2012-06-15 CN CN2012101977433A patent/CN102826517A/zh active Pending
  • 2012-06-15 CN CN201410760508.1A patent/CN104591101A/zh active Pending
• 2013
  • 2013-10-23 ZA ZA2013/07913A patent/ZA201307913B/en unknown

Patent Citations (10)

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