Classifications

• • 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
  • B01D5/0027—Condensation of vapours; Recovering volatile solvents by condensation by direct contact between vapours or gases and the cooling medium
  • B01D5/003—Condensation of vapours; Recovering volatile solvents by condensation by direct contact between vapours or gases and the cooling medium within column(s)

Definitions

• the proven apparatus for the liquefaction of pure vapors or steam mixtures is the indirect heat exchanger, in which the heat of condensation is transferred to a cooling medium. If the condensation temperatures of the steam are so low that no suitable cooling medium is available, the vapors are first compressed and then condensed or liquefied at a higher temperature level by means of an existing cooling medium.
• the naturally occurring and therefore degradable vapors should be economical in a higher temperature, pressure and application area can be used.
• Exhaust gas scrubbers are at least partially a large-scale solution and thus an indication of another way of liquefying vapors.
• the vaporous pollutants HC1, SO2, SO3 .. are condensed out of the exhaust gas by dissolving them in a washing liquid.
• the mass transfer between gas and liquid takes place through the different partial pressures of the vapors to be separated in the gas and in the liquid phase, which among other things. are determined by Raoult's law.
• An exhaust air with high vaporous pollutant contents is treated here, gasoline being used as washing liquid for the light boilers in the air, such as butane.
• the clean gas values depend on the partial pressures above the scrubbing liquid. With falling temperatures, the partial pressures decrease and the clean gas values improve; because the washing liquid is also measured as an impurity according to its partial pressure in the exhaust air. Ie Nitsche achieved
• the good results for condensation of the vaporous pollutants are achieved by operating the scrubber at temperatures as low as possible and using the washing liquid at temperatures well below its boiling point. From an energetic point of view, this operation of the scrubber has the disadvantage that the heat of condensation of the vaporous pollutants is largely dissipated via a complex refrigeration system at - 50 ° C.
• a substance is selected as the heat transfer medium which can be mixed as ideally as possible with the vaporous substance in the liquid phase,
• washing liquid applied is close to its boiling state in terms of pressure and temperature or is already partially evaporated
• washing liquid is evaporated by the heat of condensation and only a partial amount is drawn off together with the condensate of the vaporous substance.
• Fig. 1 shows a flow diagram for direct
• the washing condenser / reactor on Fig.l for carrying out the method is formed by its housing 1 with various nozzles and internals.
• the vaporous substance 10 is supplied via the horizontal connection piece 2 into a free space 3 of the reactor.
• the escaping condensate is drawn off via the nozzle 4.
• the condensate of the second substance 11 is supplied as a washing liquid via the nozzle 5 and the vapor formed is drawn off via the discharge nozzle 6 at the head of the reactor 1.
• a further cavity 9 is located above the liquid distribution.
• the liquid 11 applied passes through the nozzle 5 to a liquid distribution 7.
• This can be designed as a gravity distribution or as a spray distribution. It is crucial that the liquid has the same pressure as the vapors entering at 2 and is preferably at or above the boiling point.
• the liquid distributor 7 distributes the washing liquid on the exchange body 8 and flows in counterflow to the vapors 10 entering and liquefying from below at 3.
• the liquid 11 is largely evaporated and the vapors 10 liquefied. in the
• the exchange body 8 forms the surface for the desired exchange processes. It can be designed as an ordered packing, for example Mellapak 500Y from Sulzer, but other packing such as pall ring fillings or the general design of the reactor as a bottom column are also possible.
• the pack can be divided several times in the direction of the liquid in order to distribute the liquid evenly over the pack below by installing a liquid collector and distributor.
• the nozzles for the feed and discharge of the material flows from 10 and 11 can be changed with regard to their horizontal and vertical arrangement in the area of the head or foot of the reactor. If the liquid is drawn off horizontally, it is also necessary to install a liquid collector under the packing 8, such as that built by Sulzer.
• the scrubber 1 is at least partially insulated on the outside.
• a washing condenser / reactor to condense a vapor mixture containing bitumen is described in DE-PS 384 642.
• the heat of condensation is removed outside the reactor to the washing liquid which has been fed in cooled.
• the amount of washing liquid is therefore relatively large compared to the method of the invention.
• R. Billet describes ammonia as an inert gas to water.
• the operating conditions of the present invention are based on operating the washing condenser with an ideal pair of substances.
• the physical basis for the invention is from the Diagram shown in Fig. 2.
• the diagram is described with regard to the boiling process at KH Näser, Physikalische Chemie, page 111, VEB Deutscher Verlag, 11th edition, für 1969.
• the diagram applies to ideal blends and is based on the laws of Dalton and Raoult. It shows the equilibrium curves which arise at constant pressure as a function of the temperature during the condensation or evaporation of an ideal mixture of substances A and B. If a parameter is specified: temperature, liquid composition or vapor composition, the 2 other associated values can be read from the diagram.
• the diagram describes the equilibrium states of the mixture with the concentration C during evaporation or condensation in a closed system.
• components A and B endeavor to keep an equilibrium above the reactor height or to regain equilibrium. Due to the countercurrent movement of substances A and B, the equilibrium is constantly disturbed and, according to the idea of the invention, constraints for equilibrium act as a driving force for the mass transfer processes.
• the validity of the diagram extends from the concentration of the vaporous substance at the steam inlet to the concentration of the washing liquid at the washer head. A certain concentration in the liquid phase and in the vapor phase can thus be assigned to each cross section via the height of the packing 8.
• the mode of operation according to the invention initially only enables the liquefaction of the steam and is particularly suitable for the liquefaction of contaminated vapors.
• the heat of condensation is nevertheless stored at a lower level and can be transferred, for example, with NH3 as a heat transfer medium over long distances to another location without heat loss, in order to be available there again by washing with H2O, as shown in the following case 2.
• This vapor maintains its equilibrium and thus the driving force for a mass exchange over a liquid of the centering J.
• This equilibrium is achieved by evaporating component A (11) in this example from H2O with a simultaneous decrease in temperature or by condensing component B as the opposite and desired mass transfer from the gas side into the liquid.
• evaporating component A (11) in this example from H2O with a simultaneous decrease in temperature or by condensing component B as the opposite and desired mass transfer from the gas side into the liquid.
• this results in a continuous temperature profile which is established under the same principles. However, the temperature rises from the cold side at the steam inlet 3 to the boiling or evaporation temperature at the steam outlet 9.
• This mode of operation is the typical case for a heat pump.
• the NH refrigerant is first evaporated here and the waste heat can be used at the boiling level of water.
• case 2 The mode of operation of case 2 is also conceivable for the liquefaction of methane, for example by washing with a higher-boiling n-paraffin such as butane.
• the process can also be used to treat several vaporous substances as long as the boiling conditions of the washing liquid are above or below the boiling temperatures of all individual components.
• the known designs of columns can also be used in the structural design of the scrubber.
• the dimensioning depends on the choice of internals.
• the pack manufacturers give the appropriate information about the dependencies of gas velocity, pressure loss, pack type, diameter ... eg Julius Montz GmbH in Hilden in the brochure for MONTZ-PAK TYPE Bl.
• Another size is the washer height. This depends on the number of separation stages.
• the efficiency of the process depends, among other things, on the amount of washing liquid supplied.
• the amount of liquid In the case of heat recovery, the amount of liquid is just so large that the entire heat of condensation can be drawn off with the steam of the washing liquid at the washing head and only a partial stream leaves the washing condenser as an impurity in the condensate of the vaporous substance.
• the vaporous substance should first be liquefied and, additionally, the washing liquid should be evaporated simultaneously.
• the use of the products produced by the process, namely the condensate of the vaporous substance and the steam of the washing liquid, depends on the process in which the process is integrated. If the former is refrigerant and the latter is heat transfer medium, both must be at least partially separated from the impurities in the starting components A and B in accordance with FIG. 2 before being put back into the washing condenser by means of distillation or rectification.
• the operating pressure in the washing process depends on the condition of the vaporous substance. At operating conditions in the range of ambient temperature and for the material pairings NH ⁇ and H2O, the system pressure is between 1 and 10 bar. In the washer, on the other hand, when using Montz-Pak type Bl-300, there is a pressure loss of 1 - 2 mbar / m packing height. A pressure loss of 40 mbar can occur via the packing. With regard to the total pressure, it can still be said that both substances, the vapor and the washing liquid, are fed in at the same pressure level. With regard to the temperature, the washing liquid can also be applied with less than boiling temperature, but this has no advantages in terms of heat recovery.
• the steam can liquefy one or more substances and, depending on the choice of washing liquid, at least partially remove the heat of condensation via the steam of a higher or lower boiling substance of the same pressure.
• the condensate to be discharged essentially consists of the condensate of the steam or steams supplied and only a part of the washing liquid supplied.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

Applications Claiming Priority (4)

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Citations (4)

• 1989
  • 1989-05-17 DE DE19893916073 patent/DE3916073C1/de not_active Expired - Lifetime
• 1990
  • 1990-04-09 WO PCT/DE1990/000281 patent/WO1990012631A1/de unknown
  • 1990-04-09 AU AU54133/90A patent/AU5413390A/en not_active Abandoned

Patent Citations (4)

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