The object of the invention is a process and equipment for implementation of 5 rectification.

One of the hopeful reseach sphere is thai of the up-to-date rectification processes, where the rectification is implemented by stage dependent pressure. In this kind of well-known processes is taking place the large part of the heat circulation in the single degrees, even the varying pressure serves the producing of the 0 temperature clillerence which is needed for the heat circulation. By the distribution of the large part of the heat circulation into the single degrees, the needed temperature difference is smaller, than in the case of the traditional processes. The consumption of the energy in a large degree depends on the loss of value of the circulated heat energy, but it depends on the needed temperature difference. 5 The process with varying pressure by degrees is, as it follows:

1. rectification, which applies gradual heal pump,

2. rectification, which applies secimdary reflux and reboiler (SKY), and

3. rectification, which is described in the U.S. Patent No. 4 575 405

From the essence of these processes is resulted the loss of value of the circulated heat 0 energy by degrees. The process can be imported by the ceasing of the heat circulation by degrees, through another kind of measure.

The rectification processes with stage dependent pressure, need new demands from the equipment.

These are as il follows: fι ^• very low pressure drop per theoretical stage (even in the case of large liquid loading, too);

^• the moderated rapt drop of the deprived sleam in order lo easier delivering to the compressor;

^• generally, a lot of possibility for the outlet and back-inlet of the sleam and liquid lo the connection of the pressure increasers or turbines which are placing on the level of the field;

^• besides, the well-known processes are needing a large specific heal-lransfer surface in each pinto or cqulibi iun. unit, nnd by this way, tlio loan vnhio of oiroulntod honl energy by degrees can be reduced, too. The application of plalc to plate boat integrated distillation is one of the very important research sphere of the up-to-date rectification process. These processes are marked by the abbreviaton of PPI11 in the international technical bibliography. This group involves that process too, which contains secondary rellux and reboiler (marked SRV in the international bibliography). A lot of research work have been carried out for realization of this process, but until now the methods were unsatisfactory. [ Chem.

Eng. Vol. 99(12). 1992. ] .

The PPIIID processes need, as a new demand, large specific heat-transfer surface to every theoretical stage for the rectification equipment. f AlCIIli. Journal Vol. 26(2). 1980. p. 266 ] . Λ simple, cheap equipment is needed, which has a suitable heat- transfer capacity.

However, the number of the theoretical stages is significant, the equipment may not be high, because two outlet for the vapour is neecssery lo crealc on Ihe top of it. It is important, that the pressure drop must be low.

The isobar adiabatic model 1 of the rectification is concerned as a basic mo ell. The adiabalic modell is realized by the rectification of the vapour compression heal pump, which is suitable to the comparison with the energy saving methods. The total efficiency of such a kind of separation of elhane-elhylenc is 23.2 % [ KL. 28. P. 123. 1973.]. The circulated heat energy, which is demanded in the feeding, in the case of adiabatic modell, will be the greatest, and as a result of the maximum temperature difference, which is between the head and the boiler, the value will be lossed.

The isobar reversible modell is conceplional: it is characterized by endless plate number,according to the varying relative volatility on each plate a different mass flow, and in compliance with it in the boiler section to each plate heat entering, in Ihe rectification section on eache plate heat withdrawal describes it. [Int. Chem. Eng. \. 15 p. 203. 1974. J;αt the end of the column the rellux, and tbo reboiling lias a limited value, respectively.

One method of the approach of the isobar reversible rectification modell is the rectification which is carried out by secondary reflux and reboiler - SRV. The essence of it the fact, that the rectification section will be placed beside the boiler section, and 1 0 the pressure of the earlier will he chosen so larger, that in the full length of the section the temperature should be larger than in the same height of the boiler section. The two column section are connected by heat-exchangers. The pressure clillerence is produced by the compression of the steam of the feeding plate. | AlChE Journal 26.2, p.265-27 1

] f. In the SRV rectification the value of the minimal reflux and the minimal reboiling at the end of the column is 2-5 limes smaller, than at the adiabatic modell. The heat quantity which is accordance with it the value will be lossed as a result of the maximal heat difference of the column. Moreover, by the maximal mass How have to master the pressure difference which is existing between the two sections of column at the passing 0 of the feeding plate. It is a balancing of the loss which is resulted by the same temperature difference as was the earlier, namely, by some degrees larger than the half of the temperature clillerence of the adiabatic column.

Essentially, the aplication of the gradual heal pump also approaches the isobar reversible modell. The principle of that: going on in the rectification section, moving 1; αwαy from the place of the feeding, steam will be led from more points, which is compressed, and in the boiler section, in the side-reboiler will be condensed, while, they are moving away with some reboilers from the feeding point in the same sequence, as it was in the case of the taking away of the sleam. This process is compleceted, for each taking away point is needed a compressor unit, which is

individually designed and controlled, as well as heat-exchanger, moreover, must be tolerated the disadvantages of the adiabatic-polylropic compression. The integrated value of the compression work is similar to the value of SRV rectification. According to the US. Patent No. 4 575 405 the reclification is carried out at Ihe pressure, which is uniformly altering in the same direction, and uniformly increasing or decreasing or unaltered from the boiler through the boiler section and Ihe rectification section until the condenser, namely so, that the condensing heat of the steam, which was taken away at the end of the rectification section will be utilized gradually in the boiler section, and al last in the reboiler; from Ihe condensed head product two parts will be fed back: one part as a reflux similar lo the vapour compression reclification, the other part will be evaporated at decreased pressure in the surface heat exchanger of the rectification section, then it will be condensed al increased pressure again in surface heat exchanger of boiler section, and will be kepi in circulation. The judgement of the process is made more difiicult, because there are serious mistakes in the figures, description and in llie claim points of the patent. For example, in the Figures No. 10., 11. and 17, and in the description which is belonging to them, there is shown a pressure reducing valve, where the increasing of the pressure is demanded logically; in the Figure No. 1 1., and in the description which is belonging to il is missing the feeding; in the Figure No. 19. and its description was not paid attention, that in the biner azeolropic mixture, the volatility of the components will be changed al the azeolropic composition; in the model example il was accounted for only one part of the compression work.

However, from the description is outlined the method of the limited approach of the isotherm and isobar reversible rectification modell. (See Ihe Figures No. 4. and 5. of the quoted description.) According to this modell in Ihe single "sections" - or rather plates - the inner mass circulation will be decreased moving away from the feeding point, the demanded heal circulation lor the altering mass circulation is provided by the heat pump system, which is connected to the boiler section is wanner than that, while connected is to the rectification section is colder than that.

From the quoted description the non-isotherm coses can not be known, because their description are defective, but with knowledge of the isotherm reversible modell, the intention of the inventor can be discovered: the pressure of Ihe heal bearing system has to produce a constant temperature difference, even in the case of the monotonous 5 pressure change oftbo separation system.

The described method of the isotherm rectification has a larger energy demand, than the SRV process, because of the double surface heat transfer. (About the isobar system can be supposed the same).

In the non-isotherm and non-isobar cases is demanded α compression work, which does L O not result savings in Ihe heal circulalion. and at the same time only partly can be recovered in the expansion turbine.

The energy consumption of the well-known, reclification processes with stage dependent pressure, serves the work of the separation through the heal circulalion. The large part of the heal circulation - according to the altering mass circulalion - is taking 5 place in the single stages. The loss value of the heal energy, which is Ihe consequence of the heat transfer through the surface, is the loss-factor of the well-known processes.

The aim of the invented process to cease the large part of the heal circulation of the well-known processes, and the large part of the consumed energy must be utilized directly for the separation work as a volumelrical work. 0 The main thesis of the basic idea of the invented process are the followings:

^■ the gas-mixtures differ from the pure materials - which are composed essentially from one component - in the volumelrical work, which is produced by the gases existing in the mixture, and which is corresponding to that volumelrical work, which could be produced during that expansion by the mixture-composing gases together, 5 in which the available space for the mixture would be occupied by them individually alone. J Szentgydrgyi - Book - Publisher, Budapest, 1986]. However, this statement refers lo ideal gases, by adequate corrections (liigacity, activity) can be explained for real gases and vapours,

^• to produce volumetrical work by heat transfer and heat deprival, namely, by loss value of heat, is possible only with low elllciency, according to Ihe 2. main-thesis of thermodynamics J Perry. .T.I I.: Vegγcs/.n.ern k k kezik nyve, Mtϊszaki konyvkiadό, Budapest, 1968, and J.II. Perry: Chemical Fngineers Handbook Me. Graw-Hill Book Co. New York, 1 84].

^• the minimal heat transfer and heat deprival is unavoidable during the rectification for the sake of phase contact.

The basic idea of the invented process is the following:

• the monotonous altering of the boiling point is not necessary during the separation by reclification, *** but enough *** if the difference of the partial vapour presure of the keycomponcnts is increasing in the direction of the taking away of the product, namely, the volumetrical work is transformed into separation work;

^• if pressure will be kept stage dependent and so the applied minimal reflux ratio in single stage of some rectification section, respectively, the applied minimal reboiling ratio in single stage of some boiler section will be kept at same value, or, inside the section(s) of rectification the reboiling enthalpy How will be kept at same value, than the large part of the volumetrical work, which was supplied into Ihe system by the varying of the pressure, will be allocated for the separation work.

In the invented process, all the reclification section(s) one by one will be divided into stages which are consisting of one or more plates, or packing layers, or contact surface for sleam and liquid, and the pressure will be chonged from stage to stage, by this way the pressure of one mass How which was flowed through the neighbouring stages will be increased, the pressure of the other mass How will be decreased in such a way, that on the rectification section, or inside of some rectification sections same minimal reflux ratio, and, on the boiler section, or inside of some boiler sections same minimal reboiler ratio will be kept, or in such a way, that on the reclification section, or inside of some reclificotion sections the reflux enthalpy flow, and on the boiler section, or inside of some boiler section the reboiling enthalpy How from stage lo stage will be kepi at constant value; and the inside steam flow by stage will be kepi suitably al a

value which 1,05- 1,2 limes is larger than the minimal value. (It is the 5-20 % tolerance which is usual).

The heot withdrawal and reflux is created by the condensation of one port of the deprived distillate, the heat transfer and the reboiling is created by the boiling of one 5 poll of the deprived botlomproducl; and for this purpose is suilnblo for example: coondenser, dellcgmalor, reboiler, heat pump heal transformer, vapour compression, or rest evaporation, heat integration by other operation unit; or we can introduce equilibrium composed agent from a serial connected reclification column ("foreign reflux"; "foreign back-steaming"). O The value of steam flow can be kept a constant value between the stages, if we create a series during the increasing of pressure, which has suitably a pressure ratio less than two, between the stages, during decreasing of the pressure we create a series where the pressure ratio is less than two, and these will be connected energetically, the instruments are for this purpose for example; ventilators with separated inlet and outlet 5 for the steam by each slage, blower or compressor, expansion turbine, respectively.

The essence of Ihe invented process is the realization of the approach for a non-isobar equimolecular reversible reclification modell.

According to the invented process, into the single stage arriving steam flow will be joined with the liquid flow which is coining from the next stage, before the pressure of 0 the sleam will be changed. In this case, the reclification section will be succeeded by countercurrenl many stages wel compression, and the boiler section by counlcrcurrent many stages expansion. By this way, we eliminate the Ihermodynamical losses of the pressure change and we can save also Ihe plate-construction of the phase contact. In the demonstration example we describe a method for the choice of the minimal f ^" , value of the reflux and the reboiling and for the pressure stages which are belonging to them.

For tile performance of requirement of the rectification with stage dependent pressure, the traditional plate constructions and columns with packings could be made suitable only by complicated supplementary elements, and by this way only in a limited degree

can be used. [R.S.H. Mali: Performance Evaluation of Distillation Systems CHEMICAL PROCESS DESIGN. 1980. p. 171 -202].

The U.S. Patent No. 4 15 770 describes a double colu n which is a arranged in concentric form, and heat transfer possible through Ihe wall of the circular overflow, but tbo boot transfer surface is only n IVnυlioi. of ilia demanded surfaoc, moreover, ibo possible pressure degree is few.

These are heat exchanger constructions which are suitable for the contact of steam and liquid.

The U.S. Patent No. 3983191 describes a heat transfer through the wall; on the one side sleam and liquid are going in crossflow, the steam bubbles through the liquid. By this way, and the help of leading frames can be provided a smooth flow. In Ihe equipment will be separated the heal transfer through the wall, and the mass transfer by the contact of the steam and the liquid. The disadvantage is of the equipment that as a consequence of the construction the gas has lo bubble through the liquid, which causes a significant pressure drop. In this equipment the heat transfer and the mass transfer is separated, therefore they can not strenghten each other, but even increase Ihe height of the equipment.

The U.S. Patent No. 4 769 186 and No. 4 774 033 describe column constructions which have many passages, and heat transfer is possible through Ihe wall between Ihe passages, and in the single passages the contact can be realized for the steam and liquid. fhe contact of the steam and liquid is carried out by the whirl c moving of the steam in the widening passage of the equipment, the pressure drop is less than in the traditional constructions, and equalized dispersion of the steam and liquid can be realized. The large part of the column constructions are symmetrical, on bolh side of the heat transfer surface are always the same phase - sleam or liquid -therefore, the heat transfer does not help the mass transfer, the change of the phase. The non-symmetricαl constructions are non pressure-light, we can not take into consideration at the pressure change by grades.

The common disadvantage of the above mentioned methods, lhat the scale of the heal transfer is not enough great and therefore larger temperature difference will be occured αl the heat transfer surfaces, and larger is the loss value of the energy.

We aimed to work out the construction of an equipment which is suitable for the i plomonlαtion of llie rectification with stage dependent pressure and/or the realisation of plate to plate heat integrated rectification and free from the disαdvanloges of the above mentioned equipment.

The construction and operation or the invented equipment with stage dependent pressure has the following ideas: ^■ the first basic idea: we build up the equipment from stages, we divide each stage to passages by vertical sheets, in the passages and between the passages space keepers and liquid through leaders will be placed (sheets, nels or combs), the steam at the bottom, the liquid on the top will be supplied. The liquid will flow downwards on the sheet-pair, which border the passage, and the liquid thruogh leaders (sheets. nets, combs) make possible the minimal pressure drop of the steam stream, because the distribution of the liquid flow, the using of the potential energy of the supplied liquid, the cross-section of the flowing stream will remain essentially unchanged. By this method, low pressure drop, minimal drop snatch, and near lo the field level a connection by stages will be possible. For the sake of the good connection Ihe equipment can be consisted of more bodies.

^• the second basic idea: we realize the heat transfer and Ihe phase transfer together in each stage by such a way, that - according to the demand of the process - in each stage the work-agent (contact of steam-liquid) and the steam transfer agent (condensation or boiling), from them - according lo the demand - one of them in heat giving, the other in the heat receiving passages will be led, which are side by side, separated by vertical sheets, or, Ihe stages of the process will be divided lo passages by vertical sheets in such a way, that the passages of (he heat giving stage and the heat receiving stage will be placed altering side by side, and the liquid through leaders (sheets, nets or combs) will be placed in the same height and

direction in the passages which are side by side, and Ihe way of the liquid will be parallel in the passages which are side by side by the vertical sheets and through leaders (sheets, nets, or combs). By this arrangement, αl the application of the well- known processes, on both sides of the separating sheets, we lead wanner steam opposito to Ibo colder liquid and inversely. On one side the aloum- ublc coming out from the liquid, on the other side the liquid coming out of Ihe steam will increase the moss transfer. By this way increase of mass transfer in Ihe equipment can reach even the 80 % of the material circulalion of the reclification. This process is helped by the space keepers which are placed between the sheets, because they take parts in the heal transfer.

The invented rectification equipment with stage dependent pressure, according lo the invented process, consists, of adequate number of stage units, each stage consists of passages, which are separated by vertical, parallel sheets, and they are placed in one or more equipment body which are side by side, and equipped with covering sheet, each passage, and the sluge which comprises it, are connected to a common bottom steam inlet and liquid outlet, upper steam outlet and liquid inlet, through sleam distributor, sleam collector, liquid distributor and liquid collector, each stage and passage are fastened by the space keepers, which are placed in the passages and between the passages, in each passage are placed liquid through leaders, the liquid through leaders are placed in equal height, altering above and under each other, on the apposite separating sheet of the passage and Ihey occupy 15-35 % of the free cross section of the passage.

The invented reclification ond heat transfer equipment with stage dependent pressure, according to the well-known rectification with stage dependent pressure processes, or A/ consists of the heat giving passages of the heat giving stage and the heat receiving passages of the heal receiving stage, or

B/ consists of the chosen number stage units, and within that heat giving passages and heat receiving passages,

these passages are separated by vertical parallel sheets which are placed unbrokenly in the full height of the stages and slage units, they are placed in one or more equipment body which are side by side; each passage in own stage, respectively, inside of the slage unit apart the heat giving and apart the heal receiving passages are connected to u common bottom steom inlet ond liquid oullel, upper slcoin outlet ond liquid inlcl, through steam distributor, sleam collector, liquid distributor, liquid collector; each stage unit and passage are fastened by the space keepers which are placed in the passages and between the passages; in each passage are placed liquid through leader, the liquid through leaders are placed in equal height altering above and under each other, on the oposile separating sheel of the passage, and it h a s t h e c li a r a c I e r, that the passages of the beat giving and the heal receiving stages which are ordered to each other by the process, respectively, the heal giving and the heat receiving passages of some stage units which are determined by the process are placed altering side by side, and in the neighbouring passages, the liquid through leaders are placed in same height and direction, and the liquid through leaders occupy 15-35 % of the cross section of (he passage.

The liquid through leaders of the equipment are important elements. Nol only indispensable are they, but depending on the constmclion of them, Ihe efficiency of the steam-liquid contact can be increased, or to decrease more the pressure drop. The comb and additional net constmclion will serve the earlier, the turned edge of the sheel serve the latter.

The construction of the invented plate to plate heat integrated equipment, and the operation of the equipment has

^• fhe first basic idea: wc connect the heat-transfer and the contact of sleam and liquid in such a waj', that the plate-sheets of the boiler section are created as heat-transfer walls, therefore, over the heat-transfer wall liquid, and under of it steam will be flowed. By this way, the mass flow - the composition of which has changed during the change of phase - will increase the mass flow of steam-liquid contact, while both

_

Ihe heat-transfer, and the mass-transfer will be carried out dividly, according lo Ihe actual equilibrium state; ^• the second basic idea: in the plate spacing there are pipes (for liquid flowing down), or steam-turners and liquid-banks, and/or space keepers, which lake share in the increasing of both tho bool-transfor and llie masis-lranofor going on by the contact of steam-liquid, meantime, temperature difference will be created in the plate spacing. This reclification ond heal exchanger plate lo plate heat integrated equipment, according to the invention, may be in vertical or horizontal position, has a shell-plate covering, inlet and oullel stubs for the sleam, moreover, inlet ond oullel stubs for the liquid.

The equipment is characterized as it follows:

A/ the equipment in vertical position has plates in the reclification section which consist of plate-sheet and plale spacing moreover plates in Ihe boiler section which consist of plate-sheet and plate spacing they are arranged allcrn from below upwards by pairs, furthennore, the equipment is furnished with tubes which are airanged symmetrically in the reclification and boiler section, these tubes serve for transport of the mass and lo keep the distance, the tubes from the rectification section extend over through the plate spacing of the boiler section and is ended in the plate spacing of the next rectification section, while, the tubes from the boiler section extend over the plate spacing of the reclification and ended in the plate spacing of the boiler section;

or

B/ Ihe equipment in horizontal position has plates in the rectification section which consist of plate-sheet and plale spacing, moreover, plates in Ihe boiler section which consist of plate-sheet and plate spacing and Ihe plates which are in the same section are airanged in one branch, or in more paralell branches, side by side in each branch, as the continuation of each other, while, the plates which are in different section, the plates of Ihe rectification section and boiler section are airanged altern from below upwards; above the rectification section is the boiler section which is ordered lo it by

Ihe heat integration of plale to plate; moreover, between the plate-sheets of some rectification and boiler section are liquid banks, steam turners, and in some cases distance-keepers are placed, and the slope of Ihe plate-sheets can be 1 % as maximum. The theπnodynamical losses of the invented process are smaller than that of the well- known processes, by this way about 25-40 % energy conservation can be reached comparing to the traditional vapour compression processes.

Advantage of the invented equipment with stage dependent pressure is, that by application of it, the special demands of the reclification with stage dependent pressure process will be satisfied, by Ibis may, Ihe heat circulation of the well-known processes can be realized with smaller temperature difference, with smaller degree of value losses of heat energy, ond therefore the thermodynαmical losses will be decreased. The invented plate to plale heat integrated *** equipment has the advantage, that by the application of it, 1he special demands of the plate lo plate heal integrated rectification will be fulfilled:

- to every theoretical stage which realized in the equipment an extremely great specific heat-transfer surface is belonged,

• the height demand of the equipment is modest, the construction is simple, cheap,

^• the mass flow capability is high, Ihe pressure drop is low.

These advantageous faelures can be realized in a wide range of load.

The invented process and ils variation is shown in the Figures N. 1-3., the invented equipment equipment with stage dependent pressure and Ihe elements of it can be seen in the Figures No. 4-6.

The invented plate to plale heal integrated equipment and the elements of it are shown in the Figures No. 7 - 1 1.

Figure No.1. block flow-sheet of the realized for of the invented process Figure No.2. one enhanced part from the flow-sheet of the invented process Figure No.3. other enhanced part from the flow-sheet of the invented proces Figure No.4. perspective drawing of the invented equipment

Figure No.5. drawing view from above of the two stage of Figure No.4. alter removing of the cover plate

Figure No.6. one part of Λ-Λ cross from Figure No.5. which overlaps two passages. In the figure No. 7. can be seen the vertical section of the equipment which is airanged in vertical position (elevation "A").

In the Figure No. 8. is shown a section of the equipment in vertical position, where is represented Ihe dividing of the down-f low-tube.

We show the horizontal section of the equipment in the Figure No. 9.

In the Figui e No. 10. can be seen the axonomelric projection of the steam turners ad liquid banks which are placed between the plate-sheets.

We show the space-keeper in the Figure No. 1 1. which are placed between the plate sheets.

The Figuie No.1. shows the block flow-sheet of the realized form of the invention process. The meaning of the forms is equipment or equipment-element, the lines with airows mean mass-flows.

The 1 mixture which will be separated is led into B feeding section, 'fhe B feeding section will be operated by traditional method, aflcr contact of steam-liquid, as the pressure of the steam is gradually changed by the Cι-C _n steam-pressure increasers, the steam will be led through the l- n rectification sections: al the same lime, the 2 reflux stream will be led through V _r reflux pressure rednclor and V _n -Vj pressure reductors, the pressure will be changed by stages, and through Ihe stages of the Rn- i rectification sections the steam will be led into the B feeding setion. This will be realized in such a way, that in every stage the same minimal seflux ratio will be held, and the steam stream will be held at the same value in all stages, it is 1,05-1 ,2 times more that the minimal value.

The liquid will be led from the B feeding section through the stages of the Kι-K _m boiler sections, while its pressure will be changed by the Pi -I'm liquid pressure

increasers in each slage, at the same time the 3 reboiling will be led through the stages of the K _m -Kl boiler sections, and its pressure will be changed by the T _m -T] steam pressure reductors in each stage, finally, it will be led into the B feeding section. This will be realized in such a way, lhat in every stage the same minimal reboiling ratio will

5 be bold, and tbc sleam slroom will bo bold at Ibo same value in oac stage, it is 1 ,05-

1 ,2 times more than the minimal value. The steam-liquid contact will be realized similar to the traditional processes in the stages of the R ι - _π rectification sections, ond in the stages of the K]-K _nl boiler sections. The 4 head-product steam, which is going out from the last grade of the R _n

1 0 rectification section will be led into the II heat eachanger, and in case of need the pressure will be increased by the Cp vopour compressor, similarly, into the II heat exchanger, into the other space of it will be led one part of the 5 boiler rest from Ihe lαsl stage of the K _nl boiler section. By this way the 4 head-product steam will be liquified, and the rest part, alter giving back the 2 reflux, as a 6 more volatile product

15 will be given out, and from the 5 boiler rest - as we have token out from it, and we have given out the 7 less volatile product - wc realize the 3 reboiling. Al other realized form, instead of one pail of the pressure increaser we apply exceptionally pressure reductor and opposite instead of one part of the pressure increaser, always according to the constant value keeping of the minimal inner

20 circulation.

In the steom pressure reductors, for example in the turbines recovered energy, we use in Hie pressure increaser, for example in the compressors, by the direct shall coupling. At the pressure change we apply a pressure ratio between 0.5-2, by this woy the pressure change will Hearing to the isotherm circumstances and the efficiency of the

_,_ 5 energy consumption will be further improved.

The Figure No.2. shows one enhanced part from the flow-sheet of the invented process. In the optional "i" stage of the rectification section we join in the Mj mixer the steam which is arriving from the Frj-] steam-liquid separator of the former stage, and that liquid which is arriving from the FRj+i steam-liquid seporator of the next stage

through the Vj-i- i pressure reductor. The joined stream will be led into the Cj compression stage which is belonging to the rectification slage i; by this way, we realize the pressure change together with the contact of steam-liquid. The separation of the steam and liquid can be achieved by simple instruments, for example in empty vessel. Tboroforc, tbc mass flow will bo tod from C[ compression stage into Ibo l ⁷ ] . _} steam-liquid separator, from where the steam will be led into the Mi 1 1 mixer of the next slage, and the liquid through the Vj pressure rednclor into the Mj_ι mixer of the previous stage. The Figure No. . shows other enhanced part from the flow-sheet of the invented process. In the optional "j" stage of the boiler section we join in Ihe Mj mixer the steam hich is arriving from the EKj . l steam-liquid separator and the liquid which is ing from the FKj.] steam-liquid separator of the previous stage through Ihe Pj_ι pressure increaser. The joined stream will be led into the Tj expansion stage which is belonging to the "j" boiler slage, by this way we realise the pressure change together with the contact of steam-liquid. The mas-flow will be led from the Tj exponsion stage into the Fkj steam-liquid separator, from where we supply Ihe steam into Mj.j mixer of the next stage, and the liquid into the j+i mixer of the previous stage, through Ihe Pj liquid pressure increaser. By the wet pressure change - by means of high level instruments, which will be recovered by the leaving of plate constmclion - the operation can be realized without thermodynamicαl losses, and the contact of the phases will be improved. The Figure No.4. shows the perspective drawing of the invented equipment with slage dependent pressure. The equipment consist of the 15 stage units, which are equipment bodies covered with shell, and airanged side by side. The equipment is fastened into side direction by 10 spoce keepers, on the side of the equipment is placed the 1 1 steom inlet stub of the heat giving agent, the 12 steam inlet stub of the heat receiving agent, the 13 liquid inlet stub of the heat giving agent, the 14 liquid inlet stub of Ihe heal receiving agent, the 1 1 a steam outlet stub of the heal giving agent, the 12a steam

outlet stub of the heat receiving agent, the 13a liquid oullel stub of the heat giving agent, and the 1 a liquid outlet stub of the heat receiving agent.

The Figure No 5. shows the drawing view from above of the two slage of Figure No.4. aHer removing of the cover plate. The 15 slage units are divided by the 16 separating b sbools to tbo beat giving 21 pasagos and the boul receiving 22 passages. The boat giving 21 passages and the heat receiving 22 passages are placed altering side by side. The heat giving and the heal receiving agent the 1 I - 14, respectively, the l l«-14a steam and liquid inlet stub, respectively, outlet stub are going on along Ihe equipment body, and the all passages of the 1 stage units. I 0 The Figure No.6, is one part of A-A cross from Figure No. . which overlaps two passages. The heat giving 21 passage and the neighbouring heal receiving 22 passage are bordered by the vertical placed 16 separating sheets.

The 17 steom distributors connect the heat giving 21 passage with the 1 1 steam inlet stub, and the heat receiving 22 passage wilh the 12 sleam inlet stub; the 18 steam 5 collectors connect the heot giving 21 pαssuge with the 11a steam outlet stub, the 19 liquid distributors connect the heat giving 21 passage wilh Ihe 13 liquid inlet stub and the heat receiving 22 passage with the 14 liquid inlet stub, the 20 liquid collectors connect the heat giving 21 passage with 13a liquid outlet stub and Ihe 22 heat receiving passage with the 14a liquid outlet stub. In the heal giving and heal receiving 21 and 22 passages are placed the 23 liquid Ihrough leader, in equal heights altering above and under each other on the oposite 16 separating sheets of the passage, and they occupy 1 -35 % of Ihe cross section of the passage. In the heot giving and heat receiving 21 and 22 passages, which ore side by side, there are placed the 23 liquid through leaders in the same height and direction. 5 The form of 23 liquid tltrough leaders can be sheet, net or comb.

The number of inlet and outlet stub can be less with 1/4-1 /8 part in that case, if the whole quantity of the working-agent which is led into the stage, will be liquified or evaporated.

_ ,

In the case of SRV process enough to use a one-body equipment, because the heat giving passages create the rectification sections - with larger pressure degree - and the heat receiving passages create the boiler section - with lower pressure degree. In the case of the invented process the number of the stubs of the equipment decreased to tho half, bccouso inside of tho each stugo unit each passage has Ihe same purpose.

In the Figure No. 7. we show the horizontal section of the equipment which is airanged in vertical position.

The 31 rectification section or sections are placed alternately wilh 32 boiler section or sections where each of the section is arranged under the other.

The equipment is covered by the 47 shell-sheet.

The 31 reclification section is consisted of 31 a plates which include the 31b plate- sheet and the 31 c plate spacing. The 32 boiler section is completed of 32a plates which are consisted of 32b plate-sheet and the 32c plate spacing.

The 31a plates of rectification section and the 32a plates of boiler section are arranged alternately in pairs.

Among Hie plates which are belonging to the same section is flowing the steam upwards and the liquid downwards in the 41 tube.

In this equipment-version, the 41 tube for liquid, flowing down, is existed simultaneously as space-keeper too. The 41 tube for liquid, flowing down, which is placed in the 31 reclification section, is extending over through the 32c plate spacing of the 32 boiler section is ended in the downwards next 31 c plate spacing of the 31 reclification section. The 41 tube of the 32 boiler section is extending over through the 31 c plate spacing of the 1 reclification section and is ended in the downwards next 32c plale spacing of the 32 boiler section.

The equipment is furnished wilh 33 steam inlet stub in the rectification section and with 37 steam outlet stub in the reclification section, moreover, with 34 steam inlet stub in the boiler section and with 38 steam outlet stub in the boiler section. The

equipment is furnished with 39 reflux inlet stub and with 35 liquid outlet stub in the rectification section, moreover, with 40 liquid inlet stub in the boiler section and with 36 liquid outlet stub in the boiler section.

In the Figuie No. 6. can be seen Ihe 41 lubes for liquid transportation downwards, which are airanged symmetrically.

In the Figure No. 9. is shown the equipment in horizontal pozition.

In Ihe equipment, both the 31 a plates of the 31 rectification seclion(s), and tho 32a plates of the 32 boiler seclion(s), are placed side by side, following continuously each other; at the same time, the 32 boiler section is placed above the 31 rectification section, which is ordered to it. The described equipment consists of two parallel 31 reclifialion sections and vo 32 boiler sections which ordered to them. Between these section pairs is arranged the 45 insulation which is 46 insulation supporting sheet.

The 31 rectification section consists of Ihe 31 a plates which are completed of 31b plate-sheet and the 31c plale spacing. The 32 boiler section built up from the 32a plates. These are consisting of Ihe 32b plate-sheet and Ihe 32c plate spacing. The 31 a plates of the reclification section and the 32a plates of boiler section are allern airanged in the equipment, in pair. Going from above downwards, each of the 32a plates in boiler section is followed by the 3 lo plates of the rectification section.

The equipment is furnished with 33 steam inlet stub in the reclification section and with 37 steam outlet stub in the rectification section, moreover, with 34 steam inlet stub in the boiler section and wilh 38 steam outlet stub in the boiler section. The 33 steam inlet stub in the rectification section and Ihe 34 sleam inlet stub in the boiler section can work at the same time as a steam distributor.

On the equipment can be found the 39 inlet stub of reflux and the 35 liquid outlet stub in the rectification section, moreover, 40 liquid inlet stub in the boiler section and the 36 liquid outlet stub in the boiler section. The 39 reflux inlet and the 40 liquid inlet stub in the boiler section can work al the same lime as a liquid distributor.

2 Q 1

The 35 liquid outlet stub in the rectification section and the 36 liquid outlet stub in the boiler section can work at the same time as a liquid collector, loo, moreover, the 37 steom outlet stub in Ihe rectification section and the 38 liquid oullel stub in the boiler section can work at the same lime as a sleam collector, too.

5 In the 31c plate spaces of Ihe rectification section and the 32c plate spaces of the boiler section 42 steam turners and 43 liquid banks are placed.

According lo the desire, it is possible to place 44 space keepers between the 31b plate- sheets and the 47 shell-sheet, and/or between the 31c plate space of rectification and the 32c plate-sheets of boiler section too.

1 0 The 31b plate sheets of the rectification section and the 32b plate sheets of Ihe boiler section has a slope, but the value of the slope could be only 1 % as a maximum.

There is shown in the Figure No. 10. the 42 steam turner which is placed between the 31b and 32b plate sheets, and above the 32b plate sheets the 43 liquid bank.

The 42 steam turner can be a net or sheet, and in the latter case as il is desired will be 5 48 openings, or perforated sheel, comb-form, respectively.

The profile of 48 openings on the 42 steam turner-sheet can be advisably triangular or quadrangular. The 2 steam turner, which is placed in the 32c plate space of the boiler section is connected to the sheet, which covers the 32c plate space from above. This sheel can be the 31 b plate sheet of the 31 rectification section or the sheel which is

20 supporting the 46 insulation or the 47 shell sheet.

The 43 liquid bank is connected to the 1b or 32b plate sheet and it is extendig over into the 3 lc or 32c plate space.

In the Figure No. 11. con be seen the AA spoce keeper, which can be placed, for example, between the 32b plate sheet and the 47 shell sheet. The 44 space keeper can

- - «J be mode by spirals, which are placed very closely lo each other, or by cables, which are directed diagonally, or by sheets, which are opened and/or inclined.

The invented equipment with stage dependent pressure can be applied for realization of such rectification processes, where the pressure will be changed in two or more degree from the boiler to the head-product condenser.

The equipment can consist of one or more bodies, and each equipment body contains 5 more vertical 21 , 22 passages.

'fhe repeated steam-liquid contact and separation which is demanded for the rectification is going on in the 21, 22 vertical passages of the equipment. At the realization of the invented process the inner steam-flow - alter the external pressure change - through the 1 1 or 12 steam inlet stub ond the 17 steam distributor 0 will be entered in the 21 and 22 passages at the bottom, alter it llie sleam is going upwards vertically, meanwhile will contact wilh the liquid, which is flowing down on the 16 separating sheet and the 23 liquid through leader, then through the 1 steam collector and the I l a or 12a steam outlet stub is gone out and go into the next stage. The liquid flow of the rectification - after the external pressure change - through the 15 13 or 14 liquid inlet stub and 19 liquid distributor will be stepped into the 21 or 22 passages at the top, the liquid on the 1 separating sheets flowing down on the altering sides by the influence of the 23 liquid through leader, meanwhile it will contact in such a way wilh the steam which is flowing counter current and at the leading through the steam will How through the liquid, that the pressure of it will be dropped only by the 20 fraction which is usual in the column of plates, and the pressure drop is also more less than which is experienced in the column with packing.

This advantageous character is the conseguence of the fact, that the steam is not forced to make significant direction change, and essential speed change. At the realization of SRV distillation the steam-flow of the rectification section is a

^• "> 5 r. heat giving agent, therefore il is led through the 1 1 sleam inlet stub into the heal giving 21 passages, the reflux will be led into the same passages, Ihe sleam of the boiler section and the beat receiving liquid will be led into the heat receiving 22 passages, Ihe heot transfer by stoges will also be realized. It is possible, because Ihe liquid of the heat giving 21 passage is flowing always on Ihe opposite side 16 separating sheet as the

liquid of the heal receiving 22 passage. In the heal giving 21 passage the pressure is larger than in the heat receiving 22 passage, therefore , the boiling and liquefaction temperatures are higher than int the heat receiving 22 passages. At the same time, on Ihe both side of the 16 separating sheel will always be streamed

5 steam in opposite of the liquid. In the heat giving 21 passage - in the rectification section - the steam phase of it will partly be condensed, while in the heat receiving 22 passage - in the boiler section - the liquid of il will partly be evaporated. The large specific heat transfer surface of the equipment makes il possible, thai the temperature difference in the heat transfer and so the pressure difference between the rectification

_l 0 section and the boiler section can decrease, by this means, the energy demand of the separation can decrease, too.

The realization of the other well-known rectification process with stage dependent pressure in the invlentioned equipment is occured similarly to the SRV distillation, wilh the difference, that beside the heat giving 21 passages - reclification section - in 5 the heat receiving 22 passages the evaporation of the heal bearing agent; and beside the heat receiving 22 passages - boiler section - in the heal giving 21 passages the condensation of the heal bearing agent will be occured. (The heat bearing agent generally is the circulated part of Ihe more volatile product.) This equipment will be expediently placed by pressure degree as stage unit, in separated equipment body. 0 The plate lo plate heat integrated equipment according to the invention, is applicable for such a reclification process, in which to any 31 rectification seclion(s) will be 32 boiler section(s) belonged and from the la tiers heat will be transferee! lo the formers, inside of it the 32a plates of the boiler section will be ordered lo the 31a plates of the rectification section: il is Ihe plale lo plate heal integrated rectification (PPII1I) 5 )process.

In the equipment, according lo the invention, there is a determining role of Ihe heat- transfer, which is realized through the 32b plate sheet.

In the PPI1ID process, generally is not any feeding through the middle plate; the steam-phase supply of the rectification is fed through the 3 steam inlet stub of the rectification section into the equipment. Of course, il is possible to kcύ through any plate, or to take away the product.

5 Through the 33 sleam inlet stub of the rectification section will be partly liquefied on the coldei surface of the above existing 32b plate sheet in the boiler section, and il will repeat itself in every 3 la plate of the rectification section, until the not condensed fragmentary quantity of the steam will leave the equipment through the 37 steam outlet stub The reflux, which generated by the well-known methods from this steam I 0 will be back-feeding through the 39 reflux inlel stub into the equipment, and Ihe other part will be collected as a head product. The back fed reflux is going through the 1 a plates of the 31 rectification section and ils quantity will be constantly increased, and will go out through the 35 liquid outlet stub of the rectification section from the equipment.

5 The connection of the steam and liquid stream with the own boiler section of the 31 rectification section - which is not nesessarily is identical with the belonging 32 boiler section - is going on by the 33 sleam inlcl stub and Ihe 35 liquid outlet stub.

The liquid is fed through the AQ liquid inlet stub of the boiler section and it will be partly evaporated by the heal which is transferred through the 32e plate sheet; the heot- 0 transfer and the evaporation will be repealed on every 32a plate of the boiler section. This will be continued until the rest part of the liquid will leave the equipment through the 36 liquid outlet stub of the boiler section. From one part of the rest will be generated reboiler by the well-known methods (e.g. by vapour compression heatpumping), and il will be fed back through the 34 steam inlet stub of the boiler section. The steam stream is flowing through the 32 boiler section and is continuously increased, and finally leaves through the 38 sleam oullel stub.

The connection of the sleam and liquid stream wilh the own rectification section of the 32 boiler section is going on by the 38 sleam inlet stub and the 40 liquid inlet stub.

On each of the plates (both on the 1 a plates of the rectification section and on the 32a plates of the boiler section), (he counter-current steam-liquid contact will go together with exchange of the component according lo the rectification; it will be increased by the movement which is going together with the change of the volume and Ihe density, inside of the phases which lake part in the heat-transfer. This movement will be continued in the opposite phase, too, and the mass-transfer there also will be improved.

The invented process and the invented equipment will be shown by the following examples.

1. Example

1 kg/s quantity mixture, which contains 50 % iso-bulhane, as a light keycomponent, 50 % normal-buthane, as a heavy keycomponenl, at atmospheric pressure Ihe half part is in steam-phase, and it λvill be separated to normal-bulhane with a purity degree of 96 %, and to iso-buthane wilh a purity degree of 98 .

Before we disclose the result, we report the process of the calculation. For the calculation of the rectification are known numerous methods. By the applied methods generally will be determined the needed theoretical plate number, the demanded reflux ratio and the needed ratio of reboiling. For this purpose is used - at least - the equilibrium constants of the keycomponenls, which will be calculated with knowledge of the pressure which is determined in advance for each plate and the supposed liquid composition.

According lo the invented process we choose such a pressure, both in the rectification for each stage, in which the minimal reflux ratio is always the same. This ratio is calculated on the base of the steam-liquid equilibrium constant of the light key- component. Respectively, the minimal reboiling ratio by slage is always the same, and

„ ,- /HU96/00031

this ratio k calculated on ihe base of Ihe steam-liquid equilibrium conslant of Ihe heavy keycoinpononl.

Al first we examine, how huge could be Ihc largest or the smallest operating pressure. W, for Ihc sake of the realization, Ihe upper limit of Ihe pressure is the delei ininanl, then we calculate, Mini al Ibis pressure, supposed Ihc side-rclluxoa, bow largo is the minimal hcad-iellux . and supposed the side-boilers, how large is the minimal botloni- reboiling.

If the nuclei limit of the piessure is the delerniinanl, then we calculate al this pressuie Hie needed minimal i ollux ratio in Ihe feeding section and the minimal reboiling rαlio. 1 0 Wo choose Ihe larger li om Ihe allernalivc iiiinimal reflux ratio and icboiling ratio, which wcie dclei mined eai lier, and we [ κ Ihc inner steam and liquid stream, apart to Ihe rectification section and apart lo the boiling section.

On Ihe base of Ihc inner steam stream and Ihe composition the equilibrium constant can be calculated, |Timmcrs, A.C.: Proc. of the Int. Syinp. on Distillation, 1969. 15 Brighton, according lo Ihe page 5.57. |

20 _f ^iiM .

V = { 1 - } M (2) κ _n -ι ^

_ __.: 5 where

V steam slreani in Ihc rectification scclion

D distillate xk|j inolfracliou of the leighl keycoinpononl in the distillate

„ ,

Z. o

xk molfrαclion of the leighl keycomponenl in the liquid of the investigated stage

Kfc equilibrium constant of the leighl keycomponenl in the investigated stage V steom stream in the boiler section

M rest of the boiler

XnM molfruction of the heavy keycomponent in the rest x _n molfraction of the heavy keycomponent in the liquid of the investigated stage Kn equilibrium constant of the heavy keycomponenl in the investigated stage

In the above described formulas every constant is determined in our ease, except the demanded equilibrium constants of the keycomponents. The latters can be calculated by the help of the above mentioned foπnulas for the demanded numbers of stages.

In the applied pressure and supposed liquid-composition interval we make up a collection of data - by some of the well-known methods - for the equilibrium constants which are belonging to the bubble-point, then for the liquid composition by which the stage is determined and for the demanded equilibrium constant of the keycomponent we seek the suitable pressure value from the data-collection.

It will be the chosen pressure value of the slage.

The further process of the calculation con be continued by the traditional method.

Characteristic data:

[Designation is according to the marking which was given at he (1) and (2) formulas, moreover:

Kmin ' minimal reflux ratio

IV nun minimal reboiling ratio.]

Feeding section:

pressure k „ ^ι mιn 'r mm (MPa)

0,1 1,218 0,7773,4044,12

precooling by ammonia - 1 /25°C 18 kW Λi

Rectification section:

Xk

0,55

0,6

0,7

0,8

0,9

0,95

condenser pressure 0,63 MPa, temperature 47°C demanded compression work 284 kW li

Boiler section:

[The plate number of rectification: 951

By the traditional process

(Vapour compression rectification)

pressure R mm reflux ratio

0,6 MPa 5,21 5,47

compression work 108 kWh/h precompression 70 kWh/h

External energy consumption: l 7 kWh/h

[The plale number of rectification: 72[ The energy savins by the invented process: 40 %.

The energy consumption of the invented process is lower for the same prupose than that of the well-known processes, because the inner moss circulation is only a fraction - for example 50 % or 20 % - comparing lo Ihe well-known processes, both in the total 5 rectification section and in the boiler section. However, the lolal soulo of the demanded compression degrees - the ratio of the largest and smallest pressure - can exceed it of the method of isobar vapour compression, but the significant part of the compression work can be recovered in the form of expansion work.

Both the pressure increasing and the pressure decreasing will be realized under small 1 0 pressure ratio, which can significantly decrease the thennodynamical losses comparing to other processes, so thus compared wilh SRV process, too.

Both the pressure increasing stages, and Ihe pressure decreasing stages put into circulation some quantity of sleam. This can make the process more simple, cheaper and easier lo control, comparing to both the heat pump method wilh more steps, and

1 5 the isothermal rectification.

The heatexchanger demand of the invented process is only a fraction compared with the well-known processes.

The sleam quantity which takes part in the expansion and the compression can be put into forced connection, and the machines can be connected by shull coupling, without

20 any further transfer energy losses.

A significant advantage of the invented process, that the preparation of Ihe feeding needs less energy consumption than Ihe well-known processes. For example, in the case of Ihe separation of gases we can save compression work.

In the variation of the invented proces (Figure No.2. and No.3.) the thermodynamical

___ -j losses of the pressure change can theoratically be eliminated completely (as adiabatic reversible transformation) and the plale construction can be left. too.

We con compare the invented process with such u kind of traditional rectification in which the pressure is through out the same as the pressure in the feeding section of Ihe invented process.

In Ibis case, partly, significantly lower head-temperalure will be created through the traditional method, than according to the invented process, partly the inner irreversibility of the traditional column is also larges than that of the invented process, which will increase the inner steam circulalion, loo.

2. Example

We build up such a kind of equipment body of rectification wilh stage dependent presstire, in which the distance between the parallel arranged 1 separator sheets is 30 mm.

In the 21 and 22 passages altering upper and under each other equally 15 - 15 pieces of comb-form 23 liquid through leader will be placed.

The equipment, which is built in this way, can be loaded with 1-8 (kg/m) ^" Is steam

3 ° and with 10-80 m /m ^* 7h liquid, beside a pressure drop of 60-400 Pα/m, which will scarcely change if the liquid load will be changed. The drop snatching by the sleam is less than 5 % of the mass.

The above mentioned data are valid equally for the heat giving 21 passages - for the rectification section - and the heal receiving 22 passages - for Ihe boiler section. The

2 3 heat transfer surface of the equipment is 32 m Im .

The advantages of the invented equipment of rectification with stage dependent pressure are as il follows:

^■ a very low steam pressure loss; while at the plate-constructions 400 Pa/plate and the packing constructions 100 Pa/theoritical plate can be reached, here 60 Pa/plate can be reached even ol large liquid load, too;

^■ small drop snatching in the steam, only a fraction or the usual quantity;

^• the equipment is furnished with inlet and outlet for both the steam and the liquid by stages, and these do not occupy together the height of one plate;

further advantage, that to every Iheoralical plale belongs a 1 arge specific heal 3 transfer surface ol 32 m~/nf .

This latter does il possible also the expected improvement of the thennodynamical efficiency of the well-known reclification processes with stage dependent pressure.

3.Examplc

We build up such an equipment in horizontal position, in which of the 1b and 32b plate-sheets we place 1 -15 pieces alte from upwards.

We place 42 steam turners an 43 liquid banks into the 31c and 32c plate spacing.

The distance of the 1 c and 32c plate spacing is 30 mm.

The eciuipment, which is built up in such a way, can be loaded by 1 - 8 (kg/in) Is steam, and 10 - 160 ml/m / liquid beside 50 - 400 Pa/m pressure drop.

The specific heat transfer surface of the equipment is 32 m. /ml.

The above mentioned data are concerned both to the 31 reclification section and the 32 boiler section.

The invented plate lo plate heal integrated eciuipment has the following advantages:

- in the equipment realized each theoretical stage is connected with a unique large specific heal surface. Comparing lo Ihe usual values which are published in the Hiechnical bibliography [ΛIChE Journal Vol. 26(2), 1980. p. 266 - 27 1 this value is significantly higher: 8 (kg/in) /s sleam loading can be reached, ^• the construction of equipment is simple, cheap; ^• the horizontal version of the equipment needs a height wich is not more than 3 m; the demand of llie vertical version is 0,1 m per each plate;

Ihere is a further advantage: it can operate beside a low pressure drop: 50 - 400 Pa per plate, and this will hardly change by Ihe changing of the liquid loading.

LIST OF THE MARKING

B feeding section

C steam pressure increaser (e.g. compression slage) FK steam-liquid separator (boiler section) FR steαm-liquid seporotor (rectification section) II heat exchanger K stage (of boiler section) M (steam-liquid) mixer P liquid pressure increaser R stage (of rectification section)

T steam pressure reductor (. expansion lurbine stage) V liquid presure reductor i serial number of the optional stage in the rectification section j serial number of the optional slage in the boiler section p vapour compression r reflux

1-m serial number of the stages in the boiler section beginning from the feeding l-n serial number of the stages in the rectification section beginning from the feeding