FR2545372A1 - PROCESS FOR VAPORIZING A DISSOLVED PRODUCT AND FOR RECOVERING A VERY VOLATILE PART OF THE SOLVENT - Google Patents

Abstract

IN THIS PROCEDURE, AT LEAST TWO EVAPORATORS IA, IB; IIA, IIB SUCCESSIVELY BROUGHT THROUGH PRODUCT IN A VAPORIZATION STAGE I; THEY ARE PARALLEL HEATED BY HOT VAPORS AND OR THE MIST OF THIS PRODUCT. THE HOT VAPORS FROM EVAPORATOR IA; IIA BROUGHT FIRST BY THE PRODUCT, WHICH ARE AT LEAST ENRICHED BY A VERY VOLATILE COMPONENT, ARE CONDENSED INSIDE A VAPORIZATION INSTALLATION IN ORDER TO RECOVER A FLOW OF LIQUID ENRICHED BY THIS VERY VOLATIL COMPONENT.

Description

PROCESS FOR VAPORIZING A DISSOLVED PRODUCT AND FOR RECOVERING

A VERY VOLATILE PART OF THE SOLVENT

  The present invention relates to a process for vaporizing a product dissolved in a solvent containing components of different volatilities and for recovering

  at least part of this solvent enriched with at least one compound

  very volatile, by means of a vaporization system

  tion comprising at least two stages of vaporization

  rus by hot vapors and / or fumes of the product, either by parallel flow, or against the current with respect to said product, as well as at least two evaporators collected in a vaporization stage and traversed by the dissolved product, preferably (but not necessarily)

directly one after the other.

  When vaporizing liquids consisting of

  at least one relatively low-volatility solvent (e.g.

  full of water), at least one relatively very volatile solvent (for example alcohol) in a lower concentration than that of said relatively low volatile solvent, as well as dissolved solids, the highly volatile solvent preferably passes in hot vapors

  of these solid substances In addition to the objective of vapori-

  sation proper, that is to say the concentration of solid substances, we generally seek to separate one from the other in the most economical way possible.

  two types of solvents, in order to recover them in the form

  me as pure as possible Therefore, the vaporization is for example supplemented by the rectification of the distillate

  formed in the evaporator however it is also possible

  ble to achieve the object of separation and concentration by rectifying the entire quantity of liquid,

  immediately followed by thickening or concentra-

  tion of the solid substances in the solution almost free of the highly volatile solvent The route followed in each individual case depends essentially on the sum of the energy and investment costs of the vaporization and of the subsequent separation process To solve the problems aforementioned, the following processes are known: a) Rectification of the entire quantity of liquid,

  the latter being broken down into a very volatile component

  til (top product) as concentrated as possible, and

  a less volatile component containing the solid substances

  (residues) The residues are then concentrated in

  a normal multi-stage spray system

  ges The latter can be heated by a source of

  independent heat, by a heat pump (condensa-

  mechanical vapors), or by hot vapors from the head of a column

rectification.

  This process has the disadvantage of high overall energy consumption, firstly because

  the large amount of liquid to be rectified.

  The same goes for investment costs.

  b) Separation of the highly volatile component from a

  solution containing only small parts of this compound

  very volatile, in a condensing vaporization stage

  clean station, heated directly and installed upstream of the multi-stage spraying installation

proper.

  In this case, in order to save steam, only the quantity necessary is vaporized in order to take, from the product admission stream, the highly volatile component, leaving there the desired residual content. Therefore, the amount of energy heating to be used corresponds substantially to the enthalpy of vaporization of the hot vapors generated The amount of heat contained by these hot vapors is no longer usable for the following

of the vaporization process.

  The type of evaporator used is chosen according to the given circumstances; when there is a low risk of deposit formation, an evaporator is preferred

  with flow running against the current.

  c) Separation of ethanol from kneaded mixtures low in alcohol in a multi-stage vaporization installation (comprising for example evaporators

  downdraft or recirculating evaporators

  forced lation), combined with the concentration of said mixtures

  Mixed ages After a single floor or a limited number

  of stages, the kneaded mixture is practically free of alcohol.

  The condensate of hot vapors charged with alcohol and coming from

  of these floors is evacuated individually and it is decomposed

  dried in a rectification installation which can be smaller and consume less energy than an installation

  treating the total amount of hot vapor condensate.

  When a partial flow of condensate enriched with a highly volatile component is withdrawn from a multi-stage installation, the profitability of the entire process

  which can be expected depends on the total number of floors or-

  the total vaporization power of the installation, in relation to the number of stages required or the power of

  vaporization required to evaporate the highly volatile component.

  When, for example, it is necessary to withdraw 1/3 of the total quantity

  the condensate enriched by the highly volatile component and that the vaporization installation is of the 6-stage type, this quantity of condensate must be removed separately from the hot vapors of the first two stages situated on the side

  product, in order to achieve optimal profitability.

  The situation is more difficult when the installation

  spraying must be designed with 4 stages In -

  in this case, more than 1/3 of the total amount of condensate should be removed and treated, and no

optimal profitability.

  The circumstances are even more unfavorable when the quantity of condensate to be drawn off is 1/10 and when we are dealing with a two-stage installation

  of the type that can be envisaged in the case of mechanical condensation

  hot vapors, even in the presence of large

of powers.

  In condensing vaporization systems

  tion of hot vapors, which are increasingly used to save energy, it is obvious that a single-stage connection does not allow the removal of condensate enriched with a highly volatile component Two-stage installations would require the treatment of about half of the total amount of condensate, although the treatment of some 10% of the total amount of condensate would be sufficient to ensure enrichment with the highly volatile component However,

  the amount of condensate withdrawn and, conversely,

  at this quantity, its component content

  very volatile, are decisive for energy and

  vestissement of the subsequent rectification installation

  or a separation device exerting an analogous effect

  gue and operating for example on the basis of techniques

separation by membranes.

  The object of the invention is to propose a method

  of the aforementioned type, which allows thickening by evacuation

  most economical poration of the solution and in which, while largely eliminating the highly volatile component from the rest of the condensate and from the concentrated solution, it suffices to withdraw a smallest possible quantity of condensate with the greatest possible content of highly volatile component Such partial amount of condensate can then be separated by using relatively energy

  modest This results in a particular energy consumption

  weakly weak for the whole process, consisting of evaporation and rectification or a similar process. According to the invention, this object is achieved by the fact that the evaporators provided at least two in number and successively traversed by the product in the vaporization stage are heated in parallel by the hot vapors and / or the fumes of the product ; and by the fact that the hot vapors, at least enriched by a

  very volatile component, from the evaporator

  mier by the product in this vaporization stage are condensed inside the vaporization installation in order to recover a flow of liquid enriched by the

  very volatile component expected as a minimum.

  The hot vapors from the evaporator traveled in

  first place contain a large part of the very component -

  volatile expected to a minimum and they can therefore, after the heat they contain has been used by condensation in the vaporization system, be further separated to a large extent or directly used with relatively low energy consumption.

  The invention will now be described in more detail.

  tail by way of nonlimiting examples, with reference to the appended drawings in which

  Figures 1 to 10 are diagrammatic representations

  materials of vaporization installations or parts of these installations which lend themselves particularly well to the implementation of the method according to the invention, by putting

  highlight the respective advantages of these facilities

lations.

  The vaporization installation according to FIG. 1 has two vaporization stages I and II between which a successive communication is established by the product and which consist of two respective evaporators Ia, Ib and Ila, I Ib which the product also makes successively communicate .

  The product to be vaporized is delivered to the

  vaporizer Ia via a conduit 2, it is then directed through the evaporators Ib, lia and I Ib

  by conduits 4, 6 and 8, then it is evacuated from the evaporator

  tor I Ib via a conduit 10, in the form of concentrate.

  The evaporators Ia and Ib are heated

  by the hot vapors of the product from the evora-

  tor I Ib which, evacuated by a conduit 12, are condensed in a compressor 14 and are delivered in parallel to the heating chambers of the evaporators la and lb by conduits 16, 18 and 20 The condensate resulting from these hot vapors is evacuated from the chambers for heating the evaporators Ia and Ib by conduits 22 and 24, it is delivered by a

  common conduit 26 to the heating chamber of the evaporator

  I Ib, then he is evacuated from this room through the

middle of a duct 28.

  The evaporator 11a is heated, through

  of a conduit 30, by the hot vapors of product coming from

  from the evaporator Ia The condensate resulting from these hot vapors is evacuated via a conduit 32 The evaporator I Ib is heated by the hot vapors of product coming from the evaporator Ib, by means of a

conduit 34.

  Hot product vapors from

  the evaporator 11a are delivered to the conduit 12 in borrowed form.

both a conduit 36.

  The hot vapors present in the conduit 30 contain a high proportion of very volatile components and the same therefore applies to the condensate discharged

  via conduit 32 In certain circumstances

  tances, the quantity of this condensate can represent only-

  1/10 of the total vaporization power.

  The condensate discharged via the conduit 28 contains relatively few very volatile components. The condensate discharged through line 32 can be

  subject to further processing (e.g. in a dis-

  rectification), or be directly used

se.

  Figure 2 'illustrates an installation of vaporization

three-story.

  A detailed description is superfluous, because the

  symbols used are the same as in Figure 1.

  The hot vapors coming from the evaporator Ia, enriched in very volatile components, are delivered via a conduit 40 to the first evaporator 11a

  of the vaporization stage II in order to heat this evapo-

  erator, then they are evacuated in condensed form by

through a conduit 42.

  The vaporization installation according to FIG. 3 has three stages of vaporization The first stage of

  vaporization I consists of an evaporator The two evaporators

  rators lia and I Ib of the vaporization stage II, connected one behind the other on the side of the product, are heated by a duct 50 by the hot vapors of product coming from said evaporator I and containing one more

  large amount of highly volatile component Via

  diary of a conduit 52, a first evaporator II Ia of the third vaporization stage III is heated by the hot vapors which come from the evaporator I Ia and

  which contain an even greater amount of

  very volatile health The condensate containing the components

  highly volatile health is evacuated via a conduit 54 The condensates of hot vapors evacuated from the evaporators I Ia and I Ib via conduits 56

  and 58 also contain very volatile components.

  Correspondingly, the condensate of hot vapors evacuated from the evaporator II Ib by a conduit 60

  is relatively very poor in very volatile components.

  It can also be carried out according to FIG. 2 or 3 in the presence of four or more than four stages of

  vaporization Two respective successive stages are equal

  weighed at least two evaporators each time

  chement takes place so that we get with the most

  high accuracy possible the desired amount of conden-

  sat of hot vapors containing very vo-

  latils. In spraying systems according to

  Figures 1 to 3, the product and the heating fluid trans-

  pour the spray stages in the same direction.

  They are therefore connections of the equicou-

  Figure 4 illustrates an example of connection to

  against the current (we can also conceive in the same way

  era of partial circuits against the current).

  The vaporization installation according to FIG. 4 has a first vaporization stage I comprising the evaporators la and Ib between which the product establishes

  a successive communication, as well as a stage of vapori-

  sation II which communicates with the product with said stage I, is behind the latter and comprises only one

evaporator.

  The product is delivered to the evaporator la through a pipe 70, it then passes from this evaporator la to

  the evaporator Ib by borrowing a conduit 72, it is purchased

  mined by a conduit 74 from said evaporator Ib to the evaporator

  from stage II and then is evacuated from

  this stage II by a conduit 76, in the form of condensate.

  The evaporator of stage II is heated by a compressor 78 which is supplied on the one hand with fresh steam via a duct 80 and, on the other hand, receives via a duct 82 part of the hot product vapors coming from the evaporator of said stage II A duct 83 provides heating The condensate formed

  steam and hot vapors is evacuated via

  area of a duct 87 However, the evaporator of vaporization stage II can also be heated only with hot steam This hot steam is supplied to the

  evaporator heating chamber of stage II in par-

  running a conduit 89 illustrated in dotted lines.

  Thanks to conduits 84, 86 and 88, the evaporators Ia and Ib are heated in parallel by the hot vapors

  of product from the evaporator of the vaporization stage

sation II.

  The hot product vapors from the evaporator Ia are evacuated via a duct, they are condensed in a condenser A, then are evacuated in the form of condensate via a

  conduit 92 This condensate contains very volatile components

  The condenser A is cooled by a coolant.

  dissement which crosses this condenser while being admitted by a

  line 94 and rejected through line 96.

  The condensates of heating fluids coming from the evaporators Ia and Ib are evacuated by conduits 98 and 100 to be then conveyed jointly by a conduit 102 towards a condenser B The hot vapors of product discharged by the evaporator Ib arrive in the condenser B in using a conduit 104, then they are condensed in this condenser The conjugate condensate thus obtained, which does not contain high percentages of very volatile components, is evacuated by a conduit 105. Just like the condenser A, the condenser B is cooled by a coolant which arrives by

  a conduit 106 and exits through a conduit 108.

  In the embodiment according to FIG. 5, the product passes successively through the evaporators Ia, lb, l I Ta, II and II Ib It is delivered to the evaporator Ia by a conduit 120 and is evacuated from the evaporator II Ib, in the form of a concentrate, via a conduit 122 Evaporators

  La and Ib are heated in parallel by the hot vapors

  of product from II Ta and II Ib evaporators,

by means of a compressor 124.

  Evaporator II Ia is heated by hot vapors

  of product coming from the evaporator la The condensate evacuated from the heating chamber of this evaporator II Ia is expelled via a conduit 126 and it is

  enriched with very volatile components.

  Evaporator II is heated by hot vapors

  of product discharged by the evaporator Ib, then the

  hot product vapors from this evaporator

  tor II heat the evaporator II Ib.

  Evaporative heating fluid condensates

  rators Ia, Ib, II and II Ib are collected and evacuated via a conduit 128; they only contain

  a relatively small proportion of very volatile components.

  In a spraying installation according to FIG. 5, the product can also be conveyed, for example, by taking the path Ia, Ib, II, II Ia, II Ib, or else

Ia, II, II Ib, II Ia and Ib.

  In the installation according to FIG. 6, the hot vapors of product coming from the evaporator Ia are directed by a line 140 through a heater of the product delivered to said evaporator Ia, then they are evacuated from this heater, as condensate, via a pipe 142 The condensate is considerably enriched in very volatile components, the product is delivered to the heater through a pipe 144 and, from this heater, it

  gains the evaporator Ia by traversing a duct 146.

  Heating fluid condensates produced

  by the evaporators Ia, Ib and II are collected and evacuated

  cués by a conduit 148 They contain parts relative-

  low volatile components The concentrate is discharged from the product container of the evaporator II

passing through a conduit 150.

  In the embodiment of the installation according to FIG. 7, the evaporators Ia and Ib comprise a common heating chamber 160 which is supplied by hot concentrated product vapors coming from the evaporators I Ia and I Ib The product coming from the evaporators

  Ia and Ib flows into compartments 162 and 164 separated

  hermetically sealed from each other Conduits 166 and 168, coming from chambers 170 and 172 for separating the hot vapors of the product, also open into these compartments 162 and 164 Intake chambers 174 and 176 associated with the two evaporators are also separate

hermetically from each other.

  The product is delivered through a conduit 178 and it passes from the evaporator Ia to the evaporator Ib by borrowing a conduit 180, then traverses a conduit 182 to pass from said evaporator lb to the evaporators I Ia and I Ib of the vaporization stage II between which the product establishes a parallel communication These two evaporators 11a and Ib have in common a chamber 184 of product inlet,

  as well as a product collector chamber 186 The concen-

  trat is evacuated through a conduit 188 Via a conduit 190, the evaporator 11a is heated by the hot vapors of the evaporator Ia which contain the highly volatile components The evaporator I Ib is heated, through a conduit 192 , using hot vapors of product emerging from the evaporator Ib Heating in parallel

  evaporators Ia and Ib is provided by the hot vapors

  product evaporators I Ia and I Ib, thanks to a duct 194 in which a compressor 196 Ce is installed

  conduit 194 branches off from a chamber 198 for separating the

  hot fears provided jointly for the two evaporators Ila and I Ib This separating chamber 198 is in turn connected by a conduit 200 to the collecting chamber 186

of product.

  The condensate of the hot vapors, which contains the highly volatile components and is used to heat the evaporator 2 a, is evacuated via a conduit 202 By traversing a conduit 204, the condensate resulting from the hot vapors discharged from the floor vaporization I

  (evaporators 1a and 1b) is delivered to the heating chamber

  fage of the evaporator I Ib, it is mixed in this chamber with the condensate of the hot vapors admitted by the conduit 192,

  then it is evacuated by a conduit 206 This condensate contains-

  relatively few very volatile components.

  The embodiment according to Figure 7 is singular-

  Larise by a particularly compact construction, by

  low investment costs, through the possibility of isolation

  simple and low heat loss.

  The vaporization installation according to FIG. 8 is a counter-current installation corresponding to that of FIG. 4 Just like the evaporators la and Ib, the condensers A and B are assembled in a single respective structural block The evaporators la and Ib are joined together in the same way as in FIG. 7 The admission of the product is ensured by a conduit 220 and the concentrate of

  this product is discharged through a conduit 224.

  The evaporator of vaporization stage II is heated via a duct 226 The condensate

  is evacuated through a conduit 228.

  The condensers A and B are separated from each other only by a partition 230 Coolant is supplied to them by a conduit 232 and this fluid is evacuated by a conduit 234 The condensate enriched by very volatile components is evacuated from the condenser A by flowing through a pipe 236 The relatively low content condensate

  in highly volatile components is discharged through a conduit 238.

  The installation according to FIG. 8 has the same notable advantages as those mentioned opposite.

Figure 7.

  FIG. 9 illustrates an embodiment by

  particular of the evaporator Ia, in which the receptacle for

  product is subdivided into at least two compartments.

  The product is delivered to the first compartment of the evaporator Ia via a conduit 260, then to the compartment

neighbor by a conduit 262.

  The two compartments have a common heating chamber, to which a heating fluid is distributed through a conduit 264 The condensate of this fluid

  heating is evacuated through a duct 266 The hot vapors

  rejects from product collecting chambers 268 and 276 are highly enriched in very volatile components

  by comparison with an evaporator Ia which is not subdi-

aimed in several compartments.

  Before the hot vapors leave the evaporator

  tor Ia by a pipe 270, for example to heat the evaporator I Ia of FIG. 1 or 2, they pass through a separator 272 whose content is poured out, by a pipe

  274, in the first product collecting chamber 268.

  The collecting chambers 268 and 276 are separated from each other so that the hot vapors leaving

  of these collecting chambers can reach the sepa-

  common rector 272, but that product flows can

be taken individually.

  The product is discharged from the collecting chamber 276 through a conduit 278 to be directed, for example, to

  the evaporator Ib of FIG. 1 or 2.

  Thanks to the embodiment according to FIG. 9, the conduit 278 can deliver a product which contains quantities

  relatively very low volatile components of the solvent.

  In a corresponding manner, the hot vapors evacuated through the conduit 270 contain a very large part of the compound.

* very volatile health.

  The embodiment of the installation according to the

  figure 10 corresponds to that of figure 1, but its evapo-

  rator Ia is capped by a rectification column 280

  and it is made in the form of a trickle evaporator

  counter-current operation (flow evaporator

  downwardly guided against the current of the product and the hot vapors) Via a duct 282, the product is delivered to the upper bottom of the rectification column as a return flow in this column Prior to vaporization of the produced in the evaporator Ia, the hot product vapors generated in this evaporator Ia take parts of the highly volatile components of the solvent of the said product delivered by the

  conduit 282 This results in increased enrichment in compound

  very volatile health of hot vapors discharged through the

middle of conduit 284.

  The condensate containing the predominantly very volatile components is discharged through a conduit 286; the condensate containing relatively few highly volatile components is discharged through a line 288; and product concentrate

is delivered through a conduit 290.

  It goes without saying that many modifications can

  can be made to the process described and shown, -without

depart from the scope of the invention.

Claims (7)

  1 Process for vaporizing a product dissolved in   a solvent containing components of different volatilities   and to recover at least part of this solvent   chie by at least one very volatile component, by means of a vaporization installation comprising at least two stages   of vaporization traversed by hot vapors and possible-   Lement, or alternatively, by the fumes of the product, either by parallel flow, or against the current with respect to said product, as well as at least two evaporators collected in a vaporization stage and traversed by the product   dissolved, preferably (but not necessarily) direct-   one after the other, a process characterized by the fact that   the evaporators (Ia, lb; I Ia, I Ib) provided at least for the nom-   bre of two and successively traversed by the product in the vaporization stage (I; II) are heated in parallel by the hot vapors and optionally, or alternatively, by the fumes of said product; and by the fact that the hot vapors, at least enriched with a very volatile component,   of the evaporator (la; lia) traveled first by the pro-   products in this vaporization stage are condensed indi-   inside the spraying plant for recovery   a flow of liquid enriched by the highly volatile component expected at minimum.   2 Method according to claim 1, characterized in that the condensation is ensured by heating at least one evaporator (Ila; II Ia) in a vaporization stage (II; III) of the vaporization installation located downstream.   3 Method according to claim 1, characterized in that the condensation takes place in a condenser   (A) of the spraying installation.   4 Method according to claim 1, characterized in that the condensation is ensured by heating   a product heater to be sprayed into the ins vaporization plant.   Method according to claim 1, characterized in that the vaporization stage SI) comprises at least two evaporators (Ta, Ib) which are located in a common heating chamber and have separate product receptacles. 6 Method according to claim 2, characterized in that the vaporization stage (II) located downstream comprises at least two evaporators (I Ia, I Ib) which are housed in compartments of a hermetically subdivided heating chamber. 7 Method according to claim 3, characterized in that the condenser (A) is combined with at least one other condenser (B) in an apparatus O 8 Method according to claim 1, characterized   by the fact that the evaporator (la) delivering the hot vapors   enriched with at least one highly volatile component is   produced in the form of a functional trickle evaporator   working against the current and capped with a column of rec- tification.   9 Method according to any one of claims   1 to 8, characterized in that, with a view to increasing its   separation effect, -the first evaporator (la) is subdi-   aimed several times on the product side and therefore comprises several product receptacles separated from each other so that mixing of the product between the individual receptacles is prevented, but that the hot vapors of product coming from the various receptacles can mix.   Process according to any one of the claims   1 to 9, characterized in that the content of the soil-   Vant in highly volatile components is low compared to   its content of less volatile components.   11 Process according to any one of the claims   1 to 10, characterized in that the dissolved product   in the solvent is a solid in the undissolved state.