SE201615C1

SE201615C1 -

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Publication number: SE201615C1
Authority: SE

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Uppfinnare: I F McIntyre jr Prioritet beggird frail den 30 mars 1961 (USA) Uppfinningen avser ett nytt och forbattrat system fOr reglering av fraktioneringsdestillationstorn. Inventor: I F McIntyre jr Priority beggird frail March 30, 1961 (USA) The invention relates to a new and improved system for controlling fractionation distillation towers.

Narmare bestamt avses ett nytt satt att reglera fraktioneringstorn, som am avsedda for destillation av de mest lattflyktiga komponenterna ur Smnesblandningar, varvid topprodukten helt kondens eras. More specifically, it refers to a new method of controlling fractionation towers, which are intended for distilling the most volatile components from Smnes mixtures, whereby the top product is completely condensed.

Under de sista decennierna har det blivit alit mer viktigt att utvinna de mest lattflyktiga komponenterna ur kolvatefraktioner och bearbetningen av dessa material liar inneburit en viktig raffineringsprocess. Skalet till dessa materials betydelse är den senaste utvecklingen Mom petroleumindustrien. For det f5rsta har utveeklingen av polymerisationsoch alkyleringsprocesser underlattat omvandling av de lattare materialen till hogoktaniga komponenter. For det andra har anvandningen av till flytande form overford petroleum-gas, till overvagande del prapan och butan, kraftigt Rat. For det tredje ha latta olefiner, sasom eten, propen och buten blivit grundvalen for den snabbt expanderande petrokemiska industrien. In recent decades, it has become increasingly important to extract the most volatile components from hydrocarbon fractions, and the processing of these materials has involved an important refining process. The shell for the importance of these materials is the latest development Mom petroleum industry. First, the development of polymerization and alkylation processes has facilitated the conversion of the lighter materials to high octane components. Secondly, the use of liquefied petroleum gas, predominantly propane and butane, has a high ratios. Third, light olefins, such as ethylene, propylene and butene, have become the basis of the rapidly expanding petrochemical industry.

Ehuru det foreligger processer, som aro speciellt amnade .for framstallning av de mest lattflyktiga komponenterna, exempelvis angkrackning, framstfillas dessa komponenter mera allmant som biprodukter vid andra raffineringsfOrfaranden, exempelvis vid katalytisk krackning, fluidiserande hydroformig, katalytisk reforming och fluidiserande forkoksning. Although there are processes which are particularly well suited for the production of the most volatile components, for example steam cracking, these components are more generally prepared as by-products in other refining processes, for example in catalytic cracking, fluidizing hydroformic, catalytic reforming and fluidizing coking.

Vid bearbetning av dessa lattflyktiga komponenter Sr det nodvandigt att fraktionera Dupl. kl. 6 b: 25; 12 a: material med myeket nara varandra belagna kokpunktsintervall. Detta astadkommes genom s, k. syperfraktionering. Vid superfrakhollering anvandes ett torn med 50 eller fler bottnar och •ett inre aterflodesforhallan:de av minst 5: 1. I allmanhet Sr temperaturskillnaden mellan tornets ovre ande och dess nedre ande cirka 22 celsiusgrader eller mindre. When machining these volatile components, it is necessary to fractionate Dupl. at 6 b: 25; 12 a: materials with very closely spaced boiling range. This is achieved by so-called hyperfractionation. In super-fracturing, a tower with 50 or more bottoms and an internal return ratio of at least 5: 1 is used. In general, the temperature difference between the upper spirit of the tower and its lower spirit is about 22 degrees Celsius or less.

Vid separation av material med mycket nara varandra belfigna kokpunktsintervall ,genom fraktionerad destillation Sr det av vikt, att uppratthalla noggrann reglering av de olika processvariablerna for att erhalla hog och konstant produktrenhet. Pa grund av detta behov av noggrann reglering ha nagra allvarliga problem uppstatt. I synnerhet upptrada problem betraffande varmetillfOrseln p5 grund av de oundvikliga forandringarna betraffande temperatur eller tryek hos upphettningsmediet. Kylplatskondensorer ha dessutom fatt alltmer vidstraekt anvandning i fraktioneringstorn, enar de ge den dubbla ,fordelen av laga investerings- och underhallskostnader i jamforelse med de tidigare anvanda vattenkylningssystemen. Med de konventionella vattenkylningssystemen sker nagra 15. plOt sliga forandringar i kylvattnets temperatur. Kylplatssystem Oro emellertid utomordentligt kansliga for stOrningar orsakade av plotsliga temperaturandringar i kylmediet orsakade av andringar i den omgivande temperaturen, vilka ofta upptra.da, i synnerhet under ovader. When separating materials with very close boiling intervals, by fractional distillation, it is important to maintain careful control of the various process variables in order to obtain high and constant product purity. Due to this need for careful regulation, some serious problems have arisen. In particular, problems arose regarding the heat supply due to the inevitable changes regarding temperature or pressure of the heating medium. Cooling site condensers have also been used more and more widely in fractionation towers, they agree to give the double, advantage of low investment and maintenance costs in comparison with the previously used water cooling systems. With the conventional water cooling systems, some 15. sudden changes in the temperature of the cooling water occur. Cooling site systems However, concerns are extremely probable for disturbances caused by sudden temperature changes in the coolant caused by changes in the ambient temperature, which often occur, especially during storms.

Enligt uppfinningen har det visat sig att man kan uppna jamnare drift i fraktioneringstorn, i vilka de angformiga topprodukterna helt kondenseras, om man reglerar det 2201 6 yttre aterflodets hastighet i beroende av forandringar i torntrycket till foljd air variationer i varmetillforseln eller aterfloclets temperatur, varigenom tornet standigt halles i varmebalans. Variationer i torntryeket avkannas av ett tryckregleringsorgan, som direkt styr regleringsventileu for det yttre aterflodet s, att det yttre aterfloclets hastighet i overensstammelse darmed forandras, varigenom tornet a'terfores till ett forutbestamt tryck. According to the invention, it has been found that smoother operation can be achieved in fractionation towers, in which the angular top products are completely condensed, if one regulates the velocity of the external return flow due to changes in the tower pressure to follow air variations in the heat supply or return temperature, whereby the tower constantly kept in heat balance. Variations in the tower pressure are sensed by a pressure regulating means which directly controls the regulating valve for the external return flow so that the velocity of the external return flow is accordingly changed, whereby the tower is returned to a predetermined pressure.

Ett torn, som ar utrustat med detta system enligt uppfinningen, kan koras sã, att vilken som heist air de normalt reglerade variablerna halles, exempelvis temperaturen pa bottnarna, sammansattningen hos topprodukten och restflodet etc. Reglering av den utvalda variabeln astadkommes genoni variering av topproduktens stromningshastighet, antingen automatiskt eller manuellt. A tower equipped with this system according to the invention can be constructed so that any lift of the normally regulated variables is maintained, for example the temperature of the bottoms, the composition of the top product and the residual flow, etc. Regulation of the selected variable is achieved by varying the flow rate of the top product. , either automatically or manually.

Detta nya regleringssystem ger manga fordelar i jamforelse med hittills kanda regleringssystem. Man uppnar med kortare tillsyningstid stabilare funktion hos tornet och battre kvalitet och stabilare sammansattning hos produkten. Till foljd av att dessutom variationer i produktflodeshastigheten hallas vid ett minimum bli fluktuationer i behandlingsanordningarna pa nedstromssidan minimala. Salunda är det mojligt att kora ett antal fraktioneringstorn i serie utan regleringsproblem. Dessutom minskas avsevart i nykonstruerade torn kostnader for inventering, underhall och drift. Dena beror i forsta hand pa att system et icke erfordrar flagon aterflOdestrumma. En annan fordel av att aterflodestrumman dr eliminerad är att sammansattningen hos det yttre aterflodet standigt Overensstammer med den hos de vid kolonnens ovre ande avgaende angorna pa grund air eliminering av efterslapning. Eliminering av denna efterslapning mojliggor snabbare upptackande av forandringar i produktens sammansattning, sâ att lampliga korrigeringar bor kunna vidtagas omedelbart. Efterslapningen i aterflodestrumman mojliggor att en produkt, vars ,sanuriansattning icke Overensstammer med foreskriften, framstalles under rang tid innan detta upptickes. Pray ha visat, att det i ett konventionellt fraktioneringstorn med aterflodestrumsystem tar 1-2 timmar innan jamvikt ater installer sig, sedan en forandring gjorts. This new control system offers many advantages compared to hitherto known control systems. With a shorter inspection time, a more stable function of the tower is achieved and a better quality and more stable composition of the product. In addition, due to the fact that variations in the product flow rate are kept to a minimum, fluctuations in the treatment devices on the downstream side become minimal. Salunda, it is possible to run a number of fractionation towers in series without regulation problems. In addition, costs for inventory, maintenance and operation are significantly reduced in newly constructed towers. This is primarily due to the fact that the system does not require a flat flow stream. Another advantage of eliminating the backflow stream is that the composition of the outer backflow constantly corresponds to that of the vapors emanating at the upper end of the column due to air elimination of lag. Elimination of this lag allows for faster detection of changes in the composition of the product, so that appropriate corrections can be made immediately. The lag in the backflow stream makes it possible for a product, whose sanurian setting does not comply with the regulations, to be produced during the rank period before this is detected. Pray have shown that in a conventional fractionation tower with backflow system it takes 1-2 hours before equilibrium is re-established, after a change has been made.

For att ytterligare belysa uppfinningen hanvisas till bifogade ritningar. To further illustrate the invention, reference is made to the accompanying drawings.

Fig. 1 illustrerar schematiskt systemet utrustad med aterflodessystemet. Fig. 1 schematically illustrates the system equipped with the backwater system.

Fig. 2 visar en fraktioneringsanlaggning for reglering av aterflodet. Fig. 2 shows a fractionation plant for regulating the return flow.

I fig. 3 jamfores grafiskt den .enligt uppfinningen erhallna stabiliserade topprodukten och kvaliteten med de resultat, som erhallas med konventionella system vid isopent anavskilj ning. In Fig. 3, the stabilized top product obtained and the quality obtained according to the invention are graphically compared with the results obtained with conventional systems in isopent separation.

I fig. 4 visas de forbattrade resultaten vid butanseparation. Fig. 4 shows the improved results of butane separation.

Tornet 1 i fig. 1 ar utrustat med en led-fling 2 for den yid kolonnens ovre 5.nde airgdende angan. Denna anga kondenseras helt i kylplatskondensorn 3. Det flytande kondensatet lamnar kondensorn 3 via kondensatledningen 4 och en. del darav gar genom aterflodesledningen 5 och ventilen 6, som reglerar aterflodet, tillbaka till tornets 1 Sir-re ande som aterflode. Ventilen 6 styres av ett tryekkansligt organ 7. rDetta sistnamnda avkanner eventuella tryckandringar i tornet. Om trycket 1 tornet stiger, oppnas aterflodesventilen 6 ytterligare, varigenom kondensatnivan i kondensorn 3 sjunker, sa att ytterligare kondensytor exponeras. Harigenom sjunker trycket i tornet tillbaka till kontrollpunkten och jamvikt uppratthalles Om caremot trycket i tornet sjunker sker motsatsen for att aterfora tornets tryck till kontrollpunkten. The tower 1 in Fig. 1 is equipped with a hinge flap 2 for the upper 5th end of the yid column. This unit is completely condensed in the cooling space condenser 3. The liquid condensate leaves the condenser 3 via the condensate line 4 and a. part of it goes through the backflow line 5 and the valve 6, which regulates the backflow, back to the Sir 1 re spirit of the tower 1 as backflow. The valve 6 is controlled by a pressure sensing member 7. The latter detects any pressure changes in the tower. If the pressure in the tower rises, the backflow valve 6 is further opened, whereby the condensate level in the condenser 3 decreases, so that further condensate surfaces are exposed. As a result, the pressure in the tower drops back to the control point and equilibrium is maintained. If the caremot pressure in the tower drops, the opposite occurs to return the tower's pressure to the control point.

Stromningsregleringsanordningen 9 och ventilen 8 anvandes for att reglera stromningshastigheten hos topprodukten.. Topprodukten lamnar systemet genom produktledningen 10. Genom forandring av stromningshastigh.eten installes topproduktens sammansattning. Om exempelvis tillflodet till ett torn är sammansatt av tva komponenter A och B, varav A ãr den mera lattflyktiga och her tendens att avga som topprodukt, skall for erhallande av separation mellan A och B toppproduktens stromningshastighet sa inregleras av regleringsanordningen 9 och ventilen 8, att den blir lika stor som den hastighet, varmed komponenten A infores i tornet. Om alltfor stora mangder av den icke onskade komponenten B upptrada i topprodukten, san.kes topproduktens stromningshastighet, varigenom den mindre flyktiga komponenten B tvingas in i restflOdet. Om daremot restfl8det innehaller alltfor stora mangder av komponenten A kan detta justeras rgenom stegring av topproduktens strOmningshastighet, varigenom denna ytterligare mangd ay komponenten A tillates m.edfolja topprodukten. The flow control device 9 and the valve 8 are used to control the flow rate of the top product. The top product leaves the system through the product line 10. By changing the flow rate, the composition of the top product is installed. If, for example, the inlet to a tower is composed of two components A and B, of which A is the more volatile and tends to emit as a top product, in order to obtain separation between A and B the flow rate of the top product must be regulated by the control device 9 and the valve 8, it becomes equal to the speed at which component A is introduced into the tower. If excessive amounts of the undesired component B appear in the overhead product, the flow rate of the overhead product is reduced, whereby the less volatile component B is forced into the residual flow. If, on the other hand, the residual flow contains excessive amounts of component A, this can be adjusted by increasing the flow rate of the top product, whereby this additional amount of component A is allowed to accompany the top product.

I fig. 2 visas den totala driften av en Iraktioneringsanordning enligt uppfinningen. Aterfl5dessystemets bestandsdelar 11-20 motsvara direkt de, som i fig. 1 betecknas med 1-10 och driften hos dessa forstnamnda overensstamma med driften hos de sistnamnda. Dessutom an en strOmningsregistra- 20163 tor 21 anordnad att mata det yttre aterflodesforhallandet och en kromatografisk analysator 22 dr anordnad att bestamma toppproduktens renhet. Aterflodespumpen 23 ãr anordnad att cirkulera det flytande kondensatet. Fig. 2 shows the total operation of an irradiation device according to the invention. The components 11-20 of the return system directly correspond to those indicated in Figs. 1 by 1-10 and the operation of the former corresponds to the operation of the latter. In addition, a flow recorder 213 is arranged to supply the external reflux ratio and a chromatographic analyzer 22 is arranged to determine the purity of the top product. The backflow pump 23 is arranged to circulate the liquid condensate.

TillfMet infares i tornet 11 genom ledningen 24. Vattenanga infores i kokaren 25 genom ledningen 26. Den hastighet, varmed vattenanga inkommer beror pa den onskade varmetillforseln och regleras med hjalp av en strtimningsregulator, som i sin. fur styres av tryckskillnadsregulatorn 28, som genom att plata tryckfallet over ett antal bottnar anger tornets belastningsgrad. Normalt är tryckskillnadsregulatorn installd far uppratthallande av maximal belastning i tornet och maximera aterflode och fraktionering. Givet- irisdetta fOrandringar av varmetill- flodet till tornet. Forandringarna av varmetillforseln medfor forandringar av angmangden, som avgar vid tornets ovre dude. Stiger topproduktens stromningshastighet, hajer tor-nets tryckregulator 17 emellertid automatiskt det yttre aterflodets hastighet och bibehaller claimed standigt varmebalans i tornet. Det framgar, att temperaturforandringar i varmetillforsels- eller kylmediet ieke paverkar produktens fraktioneringspunkt (cut point), enar det yttre aterflodets hastighet alltid halles i jamvikt med varmetillforseln. Tornets fraktioneringspunkt regleras av regulatorn 19 far topproduktens stromningshastighet. Vdtskenivaregulatorn 29 styr yentilen 30, som i sin fur reglerar stromningshastigheten hos bottenprodukten genom ledningen 31. De enda yttre forandringarna, som ha flagon inverkan pa tornet dro salunda tillflodets hastighet .och sammansattning. Dessa forandringar kunna hallas vid ett minimum, orn man anordnar (joke visade) tryckutjamningsbehallare (surge tanks) i• tillflodet. The supply is introduced into the tower 11 through the line 24. Water vapor is introduced into the boiler 25 through the line 26. The speed at which water vapor enters depends on the desired heat supply and is regulated by means of a flow regulator, as in its. fur is controlled by the pressure difference regulator 28, which by plating the pressure drop over a number of bottoms indicates the degree of load of the tower. Normally, the pressure difference regulator is installed to maintain maximum load in the tower and maximize backflow and fractionation. Given this change in the heat supply to the tower. The changes in the heat supply lead to changes in the amount of steam, which emits at the tower's upper dude. However, as the flow rate of the top product increases, the tower pressure regulator 17 automatically shifts the velocity of the external return and maintains the claimed constant heat balance in the tower. It can be seen that temperature changes in the heat supply or coolant do not affect the cut point of the product, but the velocity of the external return flow is always kept in balance with the heat supply. The fractionation point of the tower is regulated by the regulator 19 at the flow rate of the top product. The water level regulator 29 controls the valve 30, which in turn regulates the flow rate of the bottom product through the line 31. The only external changes which have a flawed effect on the tower thus reduce the velocity and composition of the inflow. These changes can be kept to a minimum, as you arrange (joke shown) pressure equalization tanks (surge tanks) in the • inflow.

Uppfinningen är lampad for vilket som heist torn, i vilket man onskar uppratthalla skarp reglering av fraktioneringen och eliminera den inverkan, som forandringar av varmetillforseln eller -avledningen liar pa produktens fraktioneringspunkt. Uppfinningen är speciellt lampad for foljande anvandningar: Torn med kilplitskondensorer. The invention is illustrated for any tower in which it is desired to maintain sharp control of the fractionation and to eliminate the effect which changes in the heat supply or dissipation have on the fractionation point of the product. The invention is particularly suitable for the following applications: Towers with wedge split capacitors.

Detta pa grund av att varmebalansen standigt uppratthalles, varigenom storningar orsakade am kylning, exempelvis pa grund air ovader elimineras. This is due to the fact that the heat balance is constantly maintained, thereby eliminating disturbances caused during cooling, for example due to air storms.

Oisolerade torn. Uninsulated towers.

Aven har ha ovader tendens att stegra avledningen av varme fran tornet. Genom upp finningen uppratthalles emellertid tornets varmebalans och produktens sammansattning konstant. Aven also tends to increase the dissipation of heat from the tower. Through the invention, however, the heat balance of the tower and the composition of the product are constantly maintained.

Torn med hoga inre aterflodesforhallanden (> 4/1). Tower with high internal river conditions (> 4/1).

I sadana torn med aterflodesreglering i be- roende av stromningshastigheten medfora mycket sma procentuella forandringar i varmetillforseln stora forandringar av produktens renhet, varigenom det Si svart att reglera tornets drift. Med exempelvis ett torn med ett inre aterfladesforhallanden 4: 1 medfor en 2-procentig andring ay varmetillforseln (dvs. ungefar den basta reglering, som kan uppratthallas med forefintliga regulatorer) % andring av produktflodet. Med hjalp av uppfinningen kan topprodukten regleras till 2 %, vilket ar fern ganger stabilare. In such towers with backflow control depending on the flow rate, very small percentage changes in the heat supply entail large changes in the purity of the product, whereby it is difficult to regulate the operation of the tower. With, for example, a tower with an internal surface ratio of 4: 1, a 2% change in the heat supply (ie approximately the best control, which can be maintained with existing regulators) entails a change in the product flow. With the help of the invention, the top product can be regulated to 2%, which is four times more stable.

I serie •arbetande torn. In series • working towers.

Delta regleringssystem jnedfOr i huvudsak konstant hastighet och renhet hos tornprodukten, varfor storningar i tornens pa nedstromssidan minskas till ett minimum. Delta control systems consist mainly of constant speed and purity of the tower product, so that disturbances in the towers on the downstream side are reduced to a minimum.

Ehuru uppfinningen lampligen anvandes i superfraktioneringsanordningar, kan den lined seras, exempelvis torn for upprepad destillationstorn, i vilket topprodukten helt kondenseras, exempelvis torn for upprepad destilla tion och andra torn for destillation av de mest lattflyktiga komponenterna, vilka icke falla mr10111 .kategori en ,superfraktioneringsanordningar. Although the invention is suitably used in superfractionation devices, it can be lined, for example, repeat distillation towers in which the overhead product is completely condensed, for example, repeated distillation towers and other towers for distillation of the most volatile components, which do not fall into category one, superfractionation devices. .

Det Sr joke heller nadvandigt att begransa uppfinningen till anvandning tillsammans med anordningar far destillation av de mest lattflyktiga komponenterna. Salunda kan den effektivt anvandas i destillationsprocesser eller kemiska anldggningar, ddr hog och konstant produktrenhet erfordras. It is also a joke to limit the invention to use with devices for distillation of the most volatile components. Thus, it can be effectively used in distillation processes or chemical plants, where high and constant product purity is required.

For att ytterligare pavisa fardelarna med uppfinningen i jamforelse med hittills kanda processer lamnas foljande exempel. In order to further demonstrate the components of the invention in comparison with hitherto known processes, the following examples are omitted.

Exempel 1. Regleringssystemet enligt uppfinningen anvandes for stabilisering ay isopentanseparation i en superfraktioneringsanordning med det nya och gamla regleringssystem. Kurvorna i fig. 3 visa isopentanprodukterna och kvaliteten som funktion ay tiden i de hada systemen. Det framgar ay dessa diagram att stabiliteten hos bade produkten och kvaliteten ãr avsevart battre med det nya regleringssystemet. Example 1. The control system according to the invention was used for stabilization of isopentane separation in a superfractionation device with the new and old control system. The curves in Fig. 3 show the isopentane products and the quality as a function of time in the hated systems. These diagrams show that the stability of both the product and the quality are considerably better with the new control system.

I det konventionella systemet reglerades torntryeket med en baktrycksregulator (back pressure controller) i ledningen for den frail kolonnens ovre ande avgaende angan. Det yttre aterflOdet halls konstant med en stromningshastighetsregulator. Bade toppro- 4201 6 duktens och bottenproduktens stromoingshastigheter reglerades i beroende av vatskeniva.. In the conventional system, the tower pressure was regulated with a back pressure controller in the line for the upper end of the frail column outgoing. The external return flow is kept constant with a flow rate regulator. Both the flow rates of both the top product and the bottom product were regulated depending on the water level.

Fraktioneringspunkten (cut point) mellan topprodukten och bottenprodukten regleras genom anpassning av varmetillforseln till tornet genom variation av mangden i kokaren inmatad vattenanga. The cut point between the top product and the bottom product is regulated by adjusting the heat supply to the tower by varying the amount of water vapor fed into the boiler.

Exempel 2. I fig. 4 jamforas det nya och det gamla systemet, nar de anvandas i en anordning for separation av butan, dvs. en annan superfraktioneringsanordning. Den Orbattrade stabiliseringseffekten framgar klart av figuren som mindre fluktuationer av isobutanhalten i bottenprodukten. Ett planerat kontrollkort anvancles i detta torn for att kontrollera tornet vid olika nivher av isobutanforluster frail bottenprodukterna beroende pa isobutanbalansen mellan alkylerings- och isomeriseringsanlaggningarna. Statistiska berakningar av fluktuationerna under de hada kontrollsystemen visade att variationer, som uttryckas som sigma-begransningar minskades till halften av dess ursprungliga varde med systemet enligt uppfinningen. Detta bestamdes i overensstammelse med statistiska forfaranden, som beskrivas i ASTM Manual on Quality Control of Materials, januari 1951. Example 2. In Fig. 4 the new and the old system are compared when used in a device for separation of butane, i.e. another superfractionating device. The Orbattrade stabilizing effect is clearly shown in the figure as minor fluctuations of the isobutane content in the bottom product. A planned control card is used in this tower to control the tower at different levels of isobutane losses from the bottom products depending on the isobutane balance between the alkylation and isomerization plants. Statistical calculations of the fluctuations under the control systems showed that variations, expressed as sigma constraints, were reduced to half of their original value with the system according to the invention. This was determined in accordance with statistical procedures described in the ASTM Manual on Quality Control of Materials, January 1951.

De ovansthende exemplen visa klart den forbattrade tornstabiliteten, som .erhalles vid anvandning av farevarande system. Forutom inbesparingen genom eliminering av en Lerflodestrumma aro andra fordelar patagliga. Salunda minskas den for kondensering av topprodukten erforderliga kondensationsytan till ett minimum pa grund av att kondensorerna arbeta vid Inuit torntryck. Nar kondensorerna koras vid fullt torntryck, ar temperaturdifferensen mellan den kondenserande angan och kylmediet maximal. Derma h8ga temperaturskillnad mojliggor overfOring av maximal varmemangd per ytenhet kondensoryta, varigenom den had& erforderliga ytan minskas. The above examples clearly show the improved tower stability obtained when using hazardous systems. In addition to the savings through the elimination of a clay river drum, other benefits are palpable. Thus, the condensing surface required for condensing the top product is reduced to a minimum due to the fact that the condensers operate at Inuit tower pressure. When the condensers are run at full tower pressure, the temperature difference between the condensing inlet and the coolant is maximum. This high temperature difference makes it possible to transfer the maximum amount of heat per unit area of condenser surface, thereby reducing the required surface area.

Mindre inbesparingar astadkommas ocksa genom minskad instrumentutrustning. Systemet underlattar ocksa installering av kondensorer for topprodukten pa markytan, endr aterflodestrumman fir eliminerad. Salunda kunna kondensorerna placeras sa. nara markytan som medgives genom NPSH-kraven for hterflodespumparna. Dessutom lampar sig tornet mycket vOl for kalkulatorreglering genom att antalet regleringsvariabler minskats till ett minimum. Salunda aro exempelvis med en kromatograf bade renheten och strainningshastigheten hos topprodukten och bottenprodukten ka.nda. En kalkulator kan berakna fororeningsmangden i topprodukten och forlusterna i bottenprodukten. Harav kan kalkulatorn bestamma den .exakta storleken hos forandringen i topprodukten, som erfordras for aterinstallning av fraktioneringspunkten pO. ekonomiskt optimum. Smaller savings are also achieved through reduced instrumentation. The system also facilitates the installation of condensers for the top product on the ground surface, changing the backflow stream to be eliminated. Thus, the capacitors can be placed said. near the ground surface permitted by the NPSH requirements for the backflow pumps. In addition, the tower is very light for calculator control by reducing the number of control variables to a minimum. For example, with a chromatograph, both the purity and the straining rate of the top product and the bottom product are known. A calculator can calculate the amount of contamination in the top product and the losses in the bottom product. From this, the calculator can determine the exact magnitude of the change in the overhead product required to reinstall the fractionation point pO. economic optimum.

Claims

Patent claim:

A method of fractionating amnesic mixtures in a fractionation apparatus with a fractionation tower and condenser under control of the quality of the fractionated products and while maintaining a predetermined temperature in the fractionation tower, the top product obtained from the fractionation tower being completely condensed in the condenser and at least a part of the condenser being , i.e. without intermediate accumulation steps, is returned to the fractionation tower as Aterflode, characterized by tendencies to pressure changes The mud tower is sensed and the returned amount of return flow is adjusted directly depending on said tendencies in such a way that the predetermined temperature is maintained in the tower.

Fractionation device for carrying out the set according to claim 1, comprising a fractionation tower (1; 11) with a line (2; 12) emanating from its outer part, as a top product from the tower extending to a condenser (3; 13) for complete condensation of the overhead product and a line (5; 15) emanating from the condenser for returning at least a portion of the output from the condenser back to the fractionation tower, which return line (5; 15) is a direct line between the condenser and the fractionation tower, without. interconnected accumulator devices for the condensate, can be drawn (Bray, that a valve (6; 16) for regulating the backflow, which Or arranged inside the direct line itself (5; 15) for the backflow, Or controlled by a pressure control means directly connected to said valve and the valve (7; 17), which is likely to cause pressure changes in the fractionation tower (1; 11) and arranged to actuate the backflow control valve (6; 16) to control the amount of backflow so that a predetermined temperature is maintained in the fractionation tower.

Device according to claim 2, characterized by a product line (10; 20) arranged to divert at least a part of the condensate from the system.

Device according to patent claim 3, characterized by means (8, 9; 18, 19) for regulating 110 it in said product line (10; 20). 201 6

Device according to any one of the patent claims 24, characterized in that the condenser (3; 13) is a cooling space condenser.

Device according to any one of claims 2-5, characterized in that the fractionation tower (1; 11) is a tower for superfractionation with a backflow slope greater than 4: 1. Request publications: Patent Specifications Iran Germany 1,039,033; USA 2 386 778, 2302 187 2 976 234.