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
  • B01D5/0078—Condensation of vapours; Recovering volatile solvents by condensation characterised by auxiliary systems or arrangements
  • B01D5/009—Collecting, removing and/or treatment of the condensate

Definitions

• the present invention concerns a procedure for removing a fraction from a condense, e.g. in a reduced pressure process, such as has been defined in the preamble to Claim 1.
• such an apparatus which comprises a cooler, in which the constituents of the gas mixture removed from the process are liquefied and/or separat ⁇ ed, and a liquid tank, in which the liquefied liquid mixture is collected to be returned to circulation and/or removed, and possibly a gas venting tube for removing the non-condensed gas obtained from the cooler.
• the gas mixture removed from the process con ⁇ sists of process gas and of pump circulating fluid ad ⁇ mixed thereto in the vacuum pump, which may ne present in the gas mixture in the form of finely divided drop- lets and/or gas.
• liquid mixture that is obtained usu ⁇ ally in addition to circulating fluid, e.g. a solvent, also contains liquefied process gas
• liquid mixture must be withdrawn from the tank to maintain equilibri- urn, in order to prevent overfilling of the tank.
• Liquid may be removed through a draining aperture in the bot ⁇ tom of the tank. In that case problems are caused e.g. by solvents when they get into the effluent.
• Endeavours are therefore directed on separating the liquefied gas from the circulating liquid and to remove it from the apparatus e.g. to be reused.- Separation of the gas and of the liquid that has formed and separation of- the constituents are difficult with existing means.
• the liquids used and circulated in liquid ring vacuum pumps are usually salt solutions.
• the drawback embarrassing salt solutions is that they tend to form emulsions with the, possibly liquefied, gases that are to be removed and with the impurities contained in them.-
• liquefied gas and/or impurities are therefore entrained into the pump circulation, and liquefied solvent escapes from the apparatus along with the circulating liquid, caus ⁇ ing effluent problems, for instance.
• Rhus the emulsions may cause soiling of apparatus and pump and/or distur ⁇ sayes of service and, likewise, effluent problems.
• the object of the present invention is to eliminate the afore-mentioned drawbacks.
• the inventive idea is that the desired layer of the liquid mixture in the condenser is remove with the aid of a draining pipe, adjusting the draining aperture of said pipe within the liquid tank to be at a corresponding height.
• the apparatus of the invention When disposed in conjunction with a process apparatus, e.g. with a liquid ring vacuum pump, the apparatus of the invention comprises a cooler in which the constituents of the gas mixture pumped out from-the process with a pump are condensed to liquids and sepa ⁇ rated by cooling.
• the apparatus further comprises a liquid tank in which the liquid mixture is collected the be conducted once again into the process, e.g. to the circulation of the pump, and/or to be removed.
• the apparatus of the invention comprises a draining pipe extending to the outside of the liquid tank and of which the draining aperture within the tank is adjustable to be located at desired height relative to the liquid level height, so that the surface layer, or any other layer, of the mixture contained in the tank can be removed from the tank.
• the advantage of the present invention over the state of art is that by the procedure and appara- tus of the invention it is possible to remove from the apparatus the constituents of the gas which in lique ⁇ fied state are lighter than the circulating liquid, the constituents of the gas which in liquefied state are heavier than the circulating liquid, and on the whole any desired constituents present in the liquid tank, and to convey them e.g. to be reused or removed.
• the impurities in the emissions which cause effluent problems can be elimi ⁇ nated better than heretofore.
• the procedure and apparatus of the invention may be used e.g. in various distilling, extracting, concentrating and drying processes of chemical indus ⁇ try, in which cases e.g. the solvent gas pumped out at reduced pressure can be liquefied and separated in re- usable form.
• the invention is described in the following in detail with the aid of an embodiment example, referring to the attached drawing, which presents the schematic drawing of an apparatus according to the invention.
• the apparatus has been disposed in con ⁇ junction with a liquid ring pump 3 connected to the process apparatus.
• the apparatus comprises an enclosed liquid tank 6 and a cooler 2.
• the cooler has been placed in conjunction with the liquid tank.
• the liquid tank is provided with a gas venting tube 13 , with an adjustable liquid removal pipe 9, and with a draining pipe 19 disposed in the bottom of the tank.
• the appara ⁇ tus communicates with a pump 3 by a gas mixture tube 15 carried from the pump to the top part of the cooler and by a circulating liquid tube 17 carried from the liquid tank to the pump.
• the liquid removal pipe 9 projects into the tank, and the draining aperture 23 of the pipe can be adjusted to be on desired height relative to the liquid level within the tank.
• the end 10 of the liquid removal pipe has been disposed to extend from outside the tank to its inside, through an aperture 24 in the tank wall. This installation has been carried out with the aid of an adaptor, known in itself in the art, permitting both rotation and/or lon ⁇ gitudinal displacement of the pipe.
• the liquid removal pipe os advantageously attached to the tank at about the height of the tank centre, but the pipe may equally be connected at any other height.
• the pipe has a curved shape within the tank, but it may equally be straight. Adjustment in height of the liquid removal pipe may be accomplished e.g. from outside the tank by turning the pipe in the aperture 24 about the longitudinal axis thereof in such manner that the position of the drairt- ing aperture 23 of the pipe changes in relation to the liquid level.
• the height adjustment of the end of the liquid removal pipe may also be implemented in other ways, e.g. by moving the pipe in the direction of its longi- tudinal axis.
• the wall of the liquid re ⁇ moval pipe may be provided with a plurality of aper ⁇ tures one after the other, which are separately open- able and closable in such a way that the aperture lo ⁇ cated at desired height can be opened e.g. with the aid of a special opening and closing mechanism.
• the cooler 2 is a cooler operating with cir ⁇ culating cooling liquid, known in itself in the art.
• cooling liquid water or another suitable refriger ⁇ ant solution may be used. Any other kind of cooling may be applied as well.
• the liquid tank is advantageously placed under the cooler.
• the tank may also carry other connectors, in addition to those mentioned.
• the tank may be provid ⁇ ed e,g, with an overflow aperture in order to prevent overfilling in the event of disturbance of service.
• the apparatus here depicted moreover comprises a gas venting tube 13 connecting with the top part of the liquid tank, this tube being provided with an after-cooler 14, which is likewise known in itself in the art, e.g. a cooler based on refrigerant circulation and wherein water or equivalent may be used for refrig- erant.
• the temperature of the after-cooler may be the same or appropriately lower than that of the cooler 2.
• the draining tube 19 in the bottom of the tank is opened and close as required with the aid of a valve 18 provided in the tube, this valve also enabling the draining rate to be controlled.
• the valve 16 inserted in the circulating li ⁇ quid tube 17 between the liquid tank 3 and the pump 3 may be used to control the circulating liquid flow from the liquid tank to the pump so as to maintain the li- quid quantity which is required for the liquid ring of the pump.
• the tube 17 is advantageously connected to the tank at about its centre height so that the end 20 of the tube 17 will remain below the draining aperture 23 of the liquid removal pipe 9. Furthermore, the tube may be made to extend into the tank up to a distance from the tank shell.
• measuring and control elements for monitoring and/or controlling the temperature of the circulating liquid, of the liquefied gases, of the uncondensed gas, of the cooler and/or the after-cooler, measuring and/or control elements for monitoring and/or controlling the liquid level in the tank and for monitoring and/or controlling the liquid flow in the tube between the liquid tank and the pump, etc. It is moreover possible to monitor and control the vacuum produced with the pump, and to cool the pump if required.
• the liquid tank 6 When starting the vacuum pumping, the liquid tank 6 is filled with circulating fluid, e.g. with water, so that the end 20 of the tube 17 between the tank and the pump 3 lies below the level of the circu ⁇ lating liquid.
• the liquid ring pump is operated to draw circulating liquid from the tank and gas from the pro- cess; the gas may for instance be harmful gas produced in the process, or gas that has been used in the pro ⁇ cess, solvent vapour that gas been formed in connection with distilling, concentrating or drying, or a mixture of these.
• the gas is conducted e.g. through a pipe 22 provided with a check valve 2.
• the gas mixture which in addition to the gas coming from the process contains circulating liquid that has been admixed thereto, is pumped through the tube 15 to the upper part of the cooler 2.
• the cooler may contain separate separators, e.g. baffles, for separating the gas from the liquid.
• the gas mixture is cooled so that the desired part of the gas is liquefied.
• the liquefied part of the gas mixture 5 is collected in the liquid tank 6.
• the uncondensed part of the gas is conducted to the gas venting tube 13, which is provided with an after-cooler 14.
• the gas is cooled in the after-cooler in order to recover part of the gas.
• the gas that-has been liquefied in the after-cooler, 12, is returned to the liquid tank, and the uncondensed gas is removed from the tank e.g. to removal, or to further handling.
• the liquid mixture that has accumulated in the tank 6 contains circulating liquid 11 and substances liquefied from the gas arriving from the process, e.g. solvents from distilling, concentrating or drying.
• the liquefied constituent part 8 of the liquid mixture which is lighter than the circulating liquid, e.g. sol- vent not miscible with the circulating liquid, forms a layer on top of the circulating liquid layer.
• the draining aperture 23 on the end 10 of the liquid remov ⁇ al pipe 9 is adjusted to ne at a suitable height above the circulating liquid level, so that the closed cir- culation of the circulating liquid in the pump and in the apparatus will not be deranged and so that separa ⁇ tion and stratification of liquefied gas and circulat ⁇ ing liquid has time to take place. If required, the position in height of the end of the liquid removal pipe is adjusted while removal is in progress.
• the draining aperture 23 of the removal pipe 9 may similarly be adjusted to lie under the circulating liquid level in order to remove circulating liquid if desired, or to be close to the bottom of the tank to remove heavier components, and/or above the liquid level to remove the gaseous component.
• Liquefied components heavier than the circu ⁇ lating liquid run down to the bottom of the tank 6 and may be removed by means of the draining tube 19.
• the liquid flow is controlled e.g. so that the level of the component heavier than the circulating liquid will not reach up to the level of the end 20 of the tube 17 bet ⁇ ween tank and pump, whereby this substance cannot be carried into the pump.
• the embodiment examples are merely meant to illustrate the invention, without restricting it in any way whatsoever.

Landscapes

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

Applications Claiming Priority (2)

Publications (1)

Family

ID=8526374

Family Applications (1)

Country Status (3)

Cited By (1)

Citations (2)

• 1988
  • 1988-04-29 FI FI882010A patent/FI79030C/sv not_active IP Right Cessation
• 1989
  • 1989-04-26 AU AU35367/89A patent/AU3536789A/en not_active Abandoned
  • 1989-04-26 WO PCT/FI1989/000080 patent/WO1989010174A1/en unknown

Patent Citations (2)

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