HRP20010658A2

HRP20010658A2 - Acceleration of the phase separation of liquid phases which contain polymers

Info

Publication number: HRP20010658A2
Application number: HR20010658A
Authority: HR
Inventors: Gabriele Sadowski; Wolfgang Arlt; Matthias Seiler; Andreas Thiele
Original assignee: Der Gruene Punkt Duales Syst
Priority date: 1999-05-14
Filing date: 2001-09-07
Publication date: 2002-10-31
Also published as: HUP0201501A2; TR200103287T2; NO20015535D0; AU5208300A; CZ20014084A3; YU80701A; SK12742001A3; EP1181328A1; EA200101023A1; EP1181328B1; PL352023A1; CA2372121A1; ES2188548T3; KR20020005672A; DE50001053D1; ATE230774T1; MXPA01011554A; AU769019B2; DE19922944A1; EE200100590A

Abstract

The invention relates to the acceleration of the separation of liquid phases which contain polymers by using branched instead of linear solvents.

Description

Miješani polimeri se mogu odjeljivati pomoću faznog odjeljivanja tekućina-tekućina [1]. Uslijed toga, polimeri su prisutni u svim fazama, ali selektivno odijeljeni. Tekuće faze bez značajnog sadržaja polimera imaju visoke viskozitete. Pod polimerima se podrazumijeva, da su to tehnički ili biološki proizvedene makromolekule, koje imaju molarnu težinu od 1000 Daltona ili više. Pod polimerima različite vrste se podrazumijeva, da su to kemijski ili strukturalno različiti polimeri, kao što je HDPE, LDPE, PP ili PVC. Mixed polymers can be separated using liquid-liquid phase separation [1]. As a result, polymers are present in all phases, but selectively separated. Liquid phases without significant polymer content have high viscosities. By polymers it is understood that they are technically or biologically produced macromolecules, which have a molar weight of 1000 Daltons or more. By polymers of different types, it is understood that they are chemically or structurally different polymers, such as HDPE, LDPE, PP or PVC.

Radi ekonomičnosti takvog procesa termalnog odjeljivanja, vremena sedimentacije u stupnjevima odjeljivanja su presudna, budući da su iskorištenja u prostoru i vremenu time determinirana. Nadalje, dugačka rezidentna vremena doprinose, da dolazi do reakcija raspadanja. For the sake of the economy of such a thermal separation process, the sedimentation times in the stages of separation are crucial, since the utilization in space and time is thereby determined. Furthermore, long residence times contribute to the occurrence of decomposition reactions.

Tekući sustavi, koji imaju dvije ili više faza uključuju kontinuiranu fazu (KP) i jednu ili više diskontinuiranih faza (DP) u dispergiranom stanju. Literatura [2] dijeli koalescenciju i sedimentaciju diskontinuirane faze u nekoliko podstupnjeva: Liquid systems that have two or more phases include a continuous phase (KP) and one or more discontinuous phases (DP) in a dispersed state. Literature [2] divides the coalescence and sedimentation of the discontinuous phase into several sub-stages:

- koalescencija pojedinih kapljica, da se oblikuju veće kapi - coalescence of individual droplets to form larger drops

- povećavanje ili smanjivanje većih kapi kontrolirano pomoću gustoće - increase or decrease of larger drops controlled by density

- unifikacija većih kapi s već oblikovanom fazom. - unification of larger drops with an already formed phase.

U svim ovim procesima, posebno je važna brzina uspinjanja ili slijeganja pojedinih kapi. Usporedno jednostavno matematičko modeliranje se dobiva, kada se kapljice smatraju krutim kuglama u KP. In all these processes, the speed of ascent or descent of individual drops is particularly important. Comparatively simple mathematical modeling is obtained, when the droplets are considered as rigid spheres in KP.

Modeliranje gibanja kuglasto oblikovanih krutih čestica u kontinuiranoj fazi izvedeno je u skladu s Clift R. et al [3] i Brauer [2], koristeći jednadžbu gibanja. Jednadžba gibanja (jednadžba 1) predstavlja član za stacionarnu brzinu padanja kuglasto oblikovanih čestica. Modeling of the motion of spherically shaped solid particles in the continuous phase was performed in accordance with Clift R. et al [3] and Brauer [2], using the equation of motion. The equation of motion (equation 1) represents the term for the stationary fall velocity of spherically shaped particles.

[image] jednadžba (1) [image] equation (1)

U tome wp predstavlja brzinu slijeganja ili uspinjanja čestica, ρP i ρF gustoću diskontinuirane (indeks P) i kontinuirane (indeks F) faze, g ubrzanje zavisno o gravitaciji, dp promjer čestice i ξ koeficijent provlačenja (drag coefficient). In this, wp represents the speed of settling or ascent of particles, ρP and ρF the density of the discontinuous (index P) and continuous (index F) phase, g the acceleration depending on gravity, dp the diameter of the particle and ξ the drag coefficient.

Jednadžba (1) općenito vrijedi za krute čestice ili za fluide s česticama visokog viskoziteta. Posebne karakteristike fazne granične površine opisane su pomoću koeficijenta provlačenja, za kojeg vrijedi slijedeći međusobni odnos: Equation (1) is generally valid for solid particles or for fluids with high viscosity particles. The special characteristics of the phase boundary surface are described using the drag coefficient, for which the following relationship applies:

[image] jednadžba (2) [image] equation (2)

u kojoj where

[image] jednadžba (3) [image] equation (3)

U jednadžbi (3), vF predstavlja kinematički viskozitet kontinuirane faze, a Ar Arhimedov broj. Uvođenje bezdimenzionalnog Arhimedovog broja je korisno, budući da na temelju toga, brzina slijeganja wP čestica u jednadžbi 1 može biti predstavljena u eksplicitnom obliku. To je: In equation (3), vF represents the kinematic viscosity of the continuous phase, and Ar is the Archimedes number. The introduction of the dimensionless Archimedean number is useful, since based on it, the settling velocity wP of the particles in equation 1 can be represented in an explicit form. It is:

[image] jednadžba (4) [image] equation (4)

Jednadžba (4) tumači, da su samo viskozitet kontinuirane faze, promjer čestica diskontinuirane faze i razlika gustoće između kontinuirane i diskontinuirane faze važni za odjeljivanje. Kratka rezidentna vremena su povoljna radi uštede pogonskih i investicijskih troškova i da se obuzdaju kemijske reakcije. Equation (4) interprets that only the viscosity of the continuous phase, the particle diameter of the discontinuous phase and the density difference between the continuous and discontinuous phase are important for separation. Short residence times are advantageous in order to save operating and investment costs and to contain chemical reactions.

U skladu s tumačenjem iz literature, vrijeme faznog odjeljivanja može se poboljšati, osobito smanjivanjem viskoziteta kontinuirane faze (KP). Mogućnosti poznate iz literature su, povišenje temperature, ili promjena prirode otapala, koje stvara KP zajedno s polimerom, obje mjere s ciljem da se smanji viskozitet KP. Navedene mjere ne vode do cilja u odjeljivanju miješanih polimera kod faznog odjeljivanja tekućina-tekućina, budući da According to the interpretation from the literature, the phase separation time can be improved, especially by reducing the viscosity of the continuous phase (KP). Possibilities known from the literature are an increase in temperature, or a change in the nature of the solvent, which creates the KP together with the polymer, both measures with the aim of reducing the viscosity of the KP. The mentioned measures do not lead to the goal of separating mixed polymers in liquid-liquid phase separation, since

- Temperatura ne mijenja samo viskozitet, nego zbog termodinamike mijenja osobito čistoću/iskorištenje polimera, koje treba odijeliti. Time se poboljšanje vremena taloženja mora nadoknaditi pogoršanjem selektivnosti. - Temperature does not only change the viscosity, but due to thermodynamics it also changes especially the purity/utilization of the polymer, which needs to be separated. Thus, the improvement of the deposition time must be compensated by the deterioration of the selectivity.

- Promjena prirode otapala toliko jako mijenja termodinamiku, da se ili temperature odjeljivanja pomiču u neekonomična područja, ili odjeljivanje faza više ne postoji u području tehnički dostižnih temperatura. - Changing the nature of the solvent changes the thermodynamics so much, that either the separation temperatures move to uneconomic areas, or the phase separation no longer exists in the area of technically achievable temperatures.

Ovaj se problem postupkom prema zahtjevu 1 rješava na elegantan i novi način. This problem is solved by the method according to claim 1 in an elegant and novel way.

Pogodne izvedbe su predmet podzahtjeva. Suitable performances are subject to sub-claims.

Razmatra se primjerice termičko odjeljivanje poliolefinskih smjesa, kao polimera različite vrste s n-alkanima s 5 do 7 ugljikovih atoma u molekuli kao otapalima. Tehničko tumačenje patentne prijave primjenjivo je međutim na svaki drugi postupak odjeljivanja, koji sadrži odjeljivanje polimernih smjesa stvaranjem tekućih faza. For example, the thermal separation of polyolefin mixtures, as polymers of different types with n-alkanes with 5 to 7 carbon atoms in the molecule as solvents, is considered. The technical interpretation of the patent application is applicable, however, to any other separation process, which contains the separation of polymer mixtures by the formation of liquid phases.

Postupak opisan u [1] odjeljuje poliolefine time, što u n-heksanu kod 180oC nastaju dvije tekuće faze, kod čega gornja, lakša faza uz stanovite rubne uvjete, sadrži polietilen iz sinteze pod visokim pritiskom (LDPE), a donja sadrži polietilen iz sinteze s niskim pritiskom (HDPE). Manje viskozna, gornja faza radi količine tvori u dispergiranom sustavu kontinuiranu fazu (KP), a vrlo viskozna, donja faza tvori diskontinuiranu fazu (DP). Mali viskozitet gornje faze ne vodi međutim do tehnički prihvatljivih vremena taloženja, tako da dolazi do gore navedenih nedostataka (troškovi, reakcije). The process described in [1] separates polyolefins by the fact that two liquid phases are formed in n-hexane at 180oC, where the upper, lighter phase, with certain boundary conditions, contains polyethylene from high pressure synthesis (LDPE), and the lower one contains polyethylene from synthesis with low pressure (HDPE). The less viscous, upper phase forms the continuous phase (KP) in the dispersed system, and the highly viscous, lower phase forms the discontinuous phase (DP). The low viscosity of the upper phase does not, however, lead to technically acceptable deposition times, so that the aforementioned disadvantages (costs, reactions) occur.

Nizom pokusa se međutim iznenađujuće pokazalo, da primjena razgrananih otapala istog broja ugljika, značajno povoljno mijenja vremena taloženja. Pritom je viskozitet od KP za nerazgranano i razgranano otapalo otprilike jednak, tako da se učinak ne može odmah objasniti. A series of experiments, however, surprisingly showed that the application of branched solvents with the same number of carbons significantly favorably changes the deposition times. At the same time, the viscosity of KP for unbranched and branched solvent is approximately the same, so the effect cannot be immediately explained.

Pod razgrananim otapalima podrazumijevaju se takve alifatske tvari, u kojima najmanje jedan ugljikov atom ima više od dva susjedna ugljikova atoma i koji, pored daljnjih atoma C i H, mogu također nositi funkcionalne skupine. Branched solvents mean such aliphatic substances, in which at least one carbon atom has more than two neighboring carbon atoms and which, in addition to further C and H atoms, can also carry functional groups.

Za predočenje načina postupka u skladu s izumom, treba se usporediti razgranano otapalo 2,3-dimetilbutan s nerazgrananim otapalom n-heksanom. To demonstrate the method of the process according to the invention, the branched solvent 2,3-dimethylbutane should be compared with the non-branched solvent n-hexane.

Primjer 1 Example 1

Provedena se dva niza ispitivanja, koja su za cilj imala odjeljivanje smjese polietilena i polipropilena. Kao poliolefini, HDPE (polietilen visoke gustoće), LDPE (polietilen niske gustoće) i polipropilen PP su dobavljeni u odnosu 15/43/42, u čemu je ukupni sadržaj poliolefina u otopini bio 20 težinskih %. Two series of tests were carried out, the aim of which was to separate the mixture of polyethylene and polypropylene. As polyolefins, HDPE (high-density polyethylene), LDPE (low-density polyethylene) and polypropylene PP were supplied in a 15/43/42 ratio, in which the total polyolefin content in the solution was 20% by weight.

U prvom nizu ispitivanja V_1 upotrebljen je n-heksan kao otapalo, a u drugom, V_2 nizu ispitivanja, 2,3-dimetilbutan. Promatrala su se vremena faznog odjeljivanja i isto tako viskoziteti otopine. Oni su predstavljeni u tablici 1. Može se zapaziti, da se s nerazgrananim otapalom ne mogu ostvariti periodi od 300 min, ili se mogu ostvariti samo na težak način. In the first series of tests V_1, n-hexane was used as a solvent, and in the second, V_2 series of tests, 2,3-dimethylbutane. Phase separation times and solution viscosities were also observed. They are presented in table 1. It can be noticed that periods of 300 min cannot be achieved with unbranched solvent, or they can be achieved only in a difficult way.

Čistoće različitih polimera su kod obe faze u oba niza bile praktično identične, budući da se priroda otapala nije mijenjala (u oba slučaja, tiče se heksana). Purities of different polymers were practically identical in both phases in both series, since the nature of the solvent did not change (in both cases, it concerns hexane).

Međutim, iznenađujuća su značajno kraća vremena odjeljivanja kod niza ispitivanja V_2, korištenjem razgrananog otapala. Premda se viskozitet kontinuirane faze (KP) i razlika gustoće ρP-ρF nisu značajno promijenili u oba niza, začuđujuće je otkriveno, da je sustav s razgrananim otapalom odijeljen 150 puta brže od sustava s n-alkanom kao otapalom. However, the significantly shorter separation times of the V_2 test series, using the branched solvent, are surprising. Although the viscosity of the continuous phase (KP) and the density difference ρP-ρF did not change significantly in both series, surprisingly it was found that the branched solvent system separated 150 times faster than the n-alkane solvent system.

[image] [image]

Tablica 1: Nizovi ispitivanja da se odijeli poliolefin s razgrananim (niz ispitivanja V_2) i nerazgrananim otapalom (niz ispitivanja V_1). Table 1: Test series to separate polyolefin with branched (test series V_2) and unbranched solvent (test series V_1).

U skladu s tumačenjem iz literature, ova smanjena vremena odjeljivanja vode prema manjim spremnicima za odjeljivanje, i zbog toga do smanjivanja investicijskih troškova i rezidentnih vremena pri nužnim visokim temperaturama. In accordance with the interpretation from the literature, these reduced separation times lead to smaller separation tanks, and therefore to a reduction in investment costs and residence times at the necessary high temperatures.

Tumačenje ovog patenta može se primijeniti na sva odjeljivanja tekućih faza, koje sadrže polimere i otapala, od kojih postoje razgranani i nerazgranani oblici. The interpretation of this patent can be applied to all liquid phase separations, containing polymers and solvents, of which there are branched and unbranched forms.

Citati Read

[1] DE 199 05 029 A, objavljeno nakon dana prava prvenstva ove prijave. [1] DE 199 05 029 A, published after the priority date of this application.

[2] Brauer, H.: Grundlagen der Einphasen- und Mehrphasenströmungen; [2] Brauer, H.: Grundlagen der Einphasen- und Mehrphasenströmungen;

Verlag Sauerländer, Aarau, 1971. Verlag Sauerländer, Aarau, 1971.

[3] Clift, R.; Grace, J.R.; Weber, M.E.: Bubbles, Drops and Particles, [3] Clift, R.; Grace, J.R.; Weber, M.E.: Bubbles, Drops and Particles,

Academic Press, New York, 1978. Academic Press, New York, 1978.

Claims

1. Postupak za ubrzanje odjeljivanja faza, koje sadrže različite polimere, naznačen time, da se a) polimeri otapaju u razgrananom otapalu ili smjesi otapala i b) nastajuće faze otapala, koje sadrže otopljene polimere različite vrste u različitoj koncentraciji, odjeljuju nakon taloženja.1. Process for accelerating the separation of phases, which contain different polymers, characterized by the fact that a) polymers dissolve in a branched solvent or solvent mixture i b) the resulting solvent phases, which contain dissolved polymers of different types in different concentrations, are separated after deposition.

2. Postupak prema zahtjevu 1, naznačen time, da su otapala tako izabrana, da su vremena taloženja faza u razgrananom otapalu ili smjesi otapala kraća, nego ona u nerazgrananom otapalu ili smjesi otapala.2. The method according to claim 1, indicated by the fact that the solvents are chosen in such a way that the deposition times of the phases in the branched solvent or solvent mixture are shorter than those in the non-branched solvent or solvent mixture.

3. Postupak prema zahtjevu 1 ili 2, naznačen time, da su polimeri različite vrste smjese poliolefina, a da je otapalo razgranani alkan s brojem ugljika između 4 i 16.3. The method according to claim 1 or 2, characterized in that the polymers are different types of polyolefin mixtures, and that the solvent is a branched alkane with a carbon number between 4 and 16.

4. Postupak prema zahtjevu 3, naznačen time, da je otapalo razgranani alkan s brojem ugljika između 4 i 10.4. The method according to claim 3, characterized in that the solvent is a branched alkane with a carbon number between 4 and 10.

5. Postupak prema zahtjevu 3, naznačen time, da je otapalo razgranani alkan s brojem ugljika između 6 i 8.5. The method according to claim 3, characterized in that the solvent is a branched alkane with a carbon number between 6 and 8.

6. Postupak prema jednom od zahtjeva 1 do 5, naznačen time, da je otapalo dimetilbutan ili metilpentan.6. The method according to one of claims 1 to 5, characterized in that the solvent is dimethylbutane or methylpentane.

7. Postupak prema jednom od zahtjeva 1 do 6, naznačen time, da primijenjeni poliolefini potječu iz otpada za iskorištavanje.7. The method according to one of claims 1 to 6, characterized in that the applied polyolefins come from waste for recovery.