(12) Oversettelse av europeisk patentskrift

Transkript

1 (12) Oversettelse av europeisk patentskrift (11) NO/EP B1 (19) NO NORGE (1) Int Cl. F26B 3/084 (06.01) B29B 13/06 (06.01) C08F 6/00 (06.01) F26B 17/ (06.01) F26B 23/00 (06.01) F26B 23/ (06.01) Patentstyret (21) Oversettelse publisert (80) Dato for Den Europeiske Patentmyndighets publisering av det meddelte patentet (86) Europeisk søknadsnr (86) Europeisk innleveringsdag (87) Den europeiske søknadens Publiseringsdato () Prioritet , DE, (84) Utpekte stater AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR (73) Innehaver ThyssenKrupp Industrial Solutions AG, ThyssenKrupp Allee 1, 4143 Essen, DE- Tyskland Vinnolit GmbH & Co. KG, Industrieparkstrasse 1, 8408 Burgkirchen, DE-Tyskland (72) Oppfinner BENJE, Michael, Walter-Kollo-Str., 6812 Bad Soden, DE-Tyskland KAMMERHOFER, Peter, Ortlehner Strasse 48, 8408 Burgkirchen, DE-Tyskland (74) Fullmektig Tandbergs Patentkontor AS, Postboks 170 Vika, 0118 OSLO, Norge (4) Benevnelse METHOD FOR DRYING A HUMID POLYMER POWDER AND DEVICE SUITABLE FOR SAID METHOD (6) Anførte publikasjoner WO-A1-/ WO-A2-08/ DE-A DE-A FR-A

2 - 1 - EP Method for drying a humid polymer powder and device suitable for said method Description The invention relates to an apparatus and a method for drying moist polymer powder. In the preparation of polymers, moist polymer powders which are treated in subsequent drying stages are frequently obtained. The drying of polymer powders has been practiced for a long time. A wide variety of apparatuses, for example drum dryers, screw dryers or fluidized-bed dryers and also an apparatus for spray drying, are used for this purpose. 1 Thus, for example, DE T2 describes a method of dewatering and degassing polymer powders by use of an extruder. DE A1 discloses a method and an apparatus for purifying a resorbable polyester. Here, a moist polymer composition is dried using a fluidized-bed dryer. DE T2 describes a method and an apparatus for drying pulverized material, which is carried out on spiral tracks in a cylindrical tube. 2 DE A1 discloses a method of drying vinyl chloride polymers by convective cocurrent drying. The method uses a flow tube and a directly adjoining cyclone dryer unit without additional contact heating. DE A1 discloses a method of thermally after-treating polymers of vinyl chloride which can be converted into a paste. The polymer emulsions obtained are subjected to spray drying.

3 - 2 - EP Fluidized-bed granulating dryers in which part of the heat generated in the process is recovered in order to make the overall process more efficient have also been described. Such an apparatus is known from DE A1. Many chemical reactions, including polymerization reactions or processes for preparing monomers required therefor, are exothermic. Utilization of the heat of reaction evolved in the chemical reaction or else the waste heat from work-up processes in the preparation of such compounds would improve the energy efficiency of the production processes. However, there is often the problem that the waste heat is obtained at a temperature level which is too low for the use. 1 1,2-Dichloroethane (hereinafter DCE ) is used predominantly as intermediate in the preparation of monomeric vinyl chloride (hereinafter VC ) which is in turn used as intermediate for the preparation of polyvinyl chloride (hereinafter PVC ). Hydrogen chloride HCl is formed in the conversion of DCE into monomeric vinyl chloride. This hydrogen chloride is preferably used in the preparation of DCE by oxychlorination of ethene by means of HCl and oxygen. An alternative route for the preparation of DCE proceeds via the direct chlorination of ethene by means of chlorine. Both routes are employed in the industrial preparation of DCE, so that a good balance between the following reaction equations is achieved in respect of the hydrogen chloride produced and consumed: 2 Cl 2 + C 2 H 4 C 2 H 4 Cl kj/mol C 2 H 4 Cl 2 C 2 H 3 Cl + HCl - 71 kj/mol C 2 H HCl + ½ O 2 C 2 H 4 Cl 2 + H 2 O kj/mol The total balance of the DCE reaction is exothermic. DCE plants are frequently coupled with plants for the preparation of VC and for PVC production. The polymer obtained in PVC production is frequently moist, especially when the polymerization is carried out as emulsion or suspension polymerization. The polymer

4 - 3 - EP powder therefore has to be dried after production and removal of excess liquid. Fluidized-bed dryers are often used for this purpose. It has now been found that the thermal energy obtained in the preparation and work-up of 1,2-dichloroethane is well suited to the operation of drying apparatuses for polymer powders. 1 FR A describes a process for drying a moist polymer powder, wherein the dryer used for the purpose contains at least one heating element which is heated with low-pressure steam. This document discloses the heating of these heating elements with low-pressure steam, with accomplishment of the setting of the low temperatures required for a mode of operation of the drying apparatus that is gentle on the product, and of the corresponding vapour pressures in the vacuum range, by means of an apparatus which is very complex in itself and in terms of closed-loop control technology. 2 It is an object of the present invention to provide an improved drying method for polymer powders and an apparatus suitable therefor, which have a particularly high energy efficiency. The invention provides a method of drying polymer powders in a drying apparatus (1), which comprises the steps: i) treatment of a polymer powder with a heated gas (6a) in a drying apparatus (1) equipped with inlet (2) and outlet (3) for the polymer powder and with heat registers () installed in the interior space (4), ii) introduction of heated gas (6a) through lines (7) into the interior space (4) of the drying apparatus (1), iii) heating of gas (6) in heat exchangers (9) for producing heated gas (6a), wherein iv) the heating of the heat exchangers (9) is effected by means of a hot fluid (a,, 19) which has been heated by means of thermal energy which originates from a plant for the preparation of 1,2-dichloroethane

5 - 4 - EP (1) and/or for the preparation of vinyl chloride from 1,2- dichloroethane, and v) hot water as hot fluid (a) which has been heated by means of thermal energy which originates from a plant for the preparation of 1,2- dichloroethane (1) and/or for the preparation of vinyl chloride from 1,2-dichloroethane flows through the heat register (). 1 Preferred embodiments of the method of the invention can be derived from the dependent claims. As can be seen from figures 1 to 3 described below, the fluidized-bed dryer which is preferably used as drying apparatus is firstly heated by means of heat registers through which hot water flows. Secondly, the fluidizing gas, in particular air, is itself preheated by means of a hot fluid, preferably by means of hot water. Drying takes place at moderate temperatures. Thus, the admission temperature of the hot water used for the heat registers is typically in the range from 80 to C, preferably about 96 C. The fluidizing gas is likewise typically preheated to temperatures in the range from 80 to 1 C, preferably to about 96 C. 2 The temperature level of these heat sinks is very well suited to being heated by means of the heat of reaction of one or both exothermic reactions of the DCE/VC process. The direct chlorination is particularly suitable here. However, the heat of reaction of the oxychlorination can also be used. Naturally, the plants for the direct chlorination or for the oxychlorination do not have to be integrated with a plant for the preparation of vinyl chloride but can also be stand-alone plants.

6 - - EP Particular preference is given to a mode of operation in which a heat transfer medium circuit whose admission temperature is set to values suitable for the fluidized-bed drying of PVC is heated by means of the heat of reaction of the direct chlorination or the oxychlorination. In the method of the invention, heating of the heat exchangers (9) is effected by means of a hot fluid (a,, 19) which has in turn been heated by means of thermal energy from a plant for the preparation of 1,2-dichloroethane (1) and/or for the preparation of vinyl chloride from 1,2-dichloroethane. This can be a hot reaction component or another heated fluid component from the plant for the preparation of 1,2- dichloroethane or for the preparation of vinyl chloride, for example hot 1,2- dichloroethane, or is a fluid which has been heated by means of thermal energy from the plant for the preparation of 1,2-dichloroethane or for the preparation of vinyl chloride and is preferably circulated in order to transport thermal energy from the plant to the drying apparatus. Particular preference is given to using water, in particular water which has been heated by heat exchange with hot 1,2-dichloroethane, for example with hot liquid 1,2-dichloroethane or with hot, condensing, gaseous 1,2- dichloroethane, as fluid. Preferably, liquid EDC from the distillation columns of the plant for the preparation of 1,2-dichloroethane (1) is introduced into the heat exchangers (9) so that the waste heat of the liquid 1,2-dichloroethane is utilized for heating the air (6). 2 Particular preference is given to a method in which the circulated heat transfer medium is water. In a further preferred variant of the method, the heat transfer medium circuit is heated by means of the waste heat from distillation columns. The heat transfer medium then flows through the coolant side of the overhead condenser of a column. Particular preference is given to a method in which the column is itself heated by means of the heat of reaction of the direct chlorination or the oxychlorination.

7 - 6 - EP The present invention also provides an apparatus (1) for drying polymer powders, which has an inlet (2) and an outlet (3) for the polymer powder and heat registers () installed in the interior space (4) and lines (7) for a heated gas (6a) for drying the polymer powder, which lines open into the interior space (4), wherein the lines (7) are connected to heat exchangers (9) for heating a gas (6) and the heat exchangers (9) are also connected via lines to a plant for the preparation of 1,2-dichloroethane (1) and/or for the preparation of vinyl chloride from 1,2-dichloroethane so that thermal energy from the plant for the preparation of 1,2-dichloroethane (1) and/or for the preparation of vinyl chloride can be utilized for heating the gas (6), and heat registers () through which hot water flows as hot fluid (a) are connected to a heat exchanger (13, ) for heating the fluid (b) flowing through the heat register () and the heat exchanger (13, ) is additionally connected via lines (11, 14) to the plant for the preparation of 1,2- dichloroethane (1) and/or for the preparation of vinyl chloride from 1,2- dichloroethane, in which a hot fluid for heating the fluid (b) is introduced and discharged. As dryers, it is possible to use any apparatuses in which the polymer powder to be dried is treated with a hot gas and which additionally have heat registers in the interior, as is the case for fluidized-bed dryers. Very particular preference is given to using fluidized-bed dryers as dryers. 2 As heat exchangers, it is possible to use any apparatuses suitable for this purpose in the apparatus of the invention. Examples are shell-and-tube heat exchangers and very particularly preferably plate heat exchangers. The invention is directed in particular to the heating of an apparatus for drying moist PVC powder by means of the heat of reaction of an exothermic reaction and/or by means of the heat generated in the work-up of the process product originating from a process for the preparation of vinyl chloride and/or for the preparation of 1,2- dichloroethane.

8 - 7 - EP However, the apparatus of the invention can also be used for drying other polymer powders. The invention is very particularly preferably directed to the heating of a fluidized-bed dryer for drying moist PVC by means of the heat evolved in the direct chlorination of ethylene to 1,2-dichloroethane or by means of the heat evolved in the oxychlorination of ethylene by means of hydrogen chloride and oxygen. Particular embodiments of the apparatus of the invention are set forth in the dependent claims. The invention is illustrated by way of example below with the aid of three figures, without any restriction being implied thereby. The figures show: 1 fig. 1: invention sketch of an apparatus according to the invention and of the method of the fig. 2: plant sketch of an apparatus according to the invention integrated into an EDC fig. 3: EDC plant. sketch of a further apparatus according to the invention integrated into an 2 Figure 1 depicts a variant of the dryer of the invention and the method of the invention. The figure shows a fluidized-bed dryer (1) having an inlet (2) for moist polymer powder and an outlet (3) for dried polymer powder which is discharged from the dryer via a star feeder (3a). Likewise shown is an outlet for the air used in the fluidized-bed dryer (1). This comprises a cyclone (22) with a downstream blower (23) and a star feeder (24) for recirculating the polymer powder precipitated in the cyclone (22) to the fluidized-bed dryer (1). In the interior, the fluidized-bed dryer (1) is heated by means of hot water (a). The heat for heating the water (a) originates at least partly from the

9 - 8 - EP waste heat from a plant for the preparation of 1,2-dichloroethane (not shown). This is passed through heat registers () installed in the interior space (4); the cooled water (b) is discharged from the heat register (). The fluidized bed is produced by means of heated air (6a). This is fed in through lines (7) at the underside of the fluidized-bed dryer. Blowers (8) ensure a sufficient pressure of the air (6a); air filters (2) are in each case installed upstream of the blowers (8). The air (6) is heated by means of heat exchangers (9) which are heated by means of hot fluid () which has been heated by means of thermal energy from a plant (not shown) for the preparation of 1,2- dichloroethane and/or a plant for the preparation of vinyl chloride. The cooled fluid (11) from the heat exchangers (9) is preferably recirculated in order to take up thermal energy from the plant for the preparation of 1,2-dichloroethane or from the plant for the preparation of vinyl chloride again. 1 2 Figure 2 depicts a connection of the variant of the dryer of the invention and the method of the invention shown in figure 1 with a DCE plant. Fluidized-bed dryer (1) with inlet (2), cyclone (22), blowers (23), star feeder (24), outlet (3), star feeder (3a) and heat register () in the interior space (4) are supplied with heated air (6a) as shown in figure 1. This air is introduced into the interior space (4) through lines (7) at the underside of the fluidized-bed dryer (1) by means of blowers (8). The heat registers () are heated by means of hot water (a) which is heated by means of heat exchangers (13) and leaves the heat register as cooled water (b), so that water is circulated between heat registers () and heat exchangers (13). Pump (17) is used for this purpose. The heat for heating the hot water originates from DCE vapor (14) from a DCE plant (1) (here: a DCE direct chlorination plant) which after heat exchange is temporarily stored as DCE condensate (16) in the collection tank (26) and is recirculated to the DCE plant (1) or partly discharged as DCE product (16a) from the DCE plant (1). Pump (18) is used for this purpose. The air (6) is heated by means of heat exchangers (9) which are heated by means of liquid DCE (19) from the DCE plant (1). The air (6) is passed through air filters (2) and fed to the heat exchangers (9) by means of blowers (8). The liquid DCE (19) is fed to the heat exchangers (9) via pump (). The cooled DCE (11) from the heat exchangers (9) is recirculated to the DCE plant (1).

10 - 9 - EP Figure 3 depicts a further, particularly preferred connection of the variant of the dryer of the invention and the method of the invention shown in figure 1 with a DCE plant. The structure corresponds to that of the plant of figure 2 with the modification that heat exchangers (9) for heating the air (6) and heat exchangers () for generating hot water (a) are operated using hot DCE (19) from the DCE plant (1). The dryer (1) is thus heated here by means of hot water which has in turn been heated by means of thermal energy originating from the DCE plant (1). The streams of the hot water (a) and the cooled water (b) are circulated.

11 1/3 EP NO/EP

12 2/3 EP NO/EP

13 3/3 EP NO/EP

14 1 Patentkrav EP Fremgangsmåte for tørking av polymer-pulver i et tørkeapparat (1), som omfatter følgende trinn: 1 i) behandling av et polymerpulver med en oppvarmet gass (6a) i et tørkeapparat (1) som er utstyrt med innløp (2) og utløp (3) for polymerpulveret og med varmeelementer () som er installert i det indre rom (4), ii) innføring av oppvarmet gass (6a) gjennom ledninger (7) inn i det indre rom (4) av tørkeapparatet (1), iii) oppvarming av gass (6) i varmevekslere (9) for fremstilling av oppvarmet gass (6a), der iv) oppvarming av varmevekslerne (9) tilveiebringes ved hjelp av en varm væske (a,, 19) som er blitt oppvarmet ved hjelp av termisk energi som kommer fra et anlegg for fremstilling av 1,2-dikloretan (1) og/eller for fremstilling av vinylklorid fra 1,2-dikloretan, og v) varmt vann idet varm fluid (a) som er blitt oppvarmet ved hjelp av termisk energi som kommer fra et anlegg for fremstilling av 1,2-dikloretan (1) og/eller for fremstilling av vinylklorid fra 1,2-dikloretan strømmer gjennom varmeregisteret (). 2. Fremgangsmåte ifølge krav 1, karakterisert ved at gassen (6) er luft Fremgangsmåte ifølge enten krav 1 eller 2, karakterisert ved at anlegget for fremstilling av 1,2-dikloretan (1) er et direkte kloreringsanlegg eller et oksykloreringsanlegg. 4. Fremgangsmåte ifølge hvilket som helst av kravene 1 til 3, karakterisert ved at tørkeapparatet er en virvelsjikttørker. 3. Fremgangsmåte ifølge hvilket som helst av kravene 1 til 4, karakterisert ved at det varme fluidet (a) har blitt varmet opp i en varmeveksler (13, ) ved bruk av en ytterligere varm fluid, der det ytterligere varme fluidet kommer fra anlegget for fremstillingen av 1,2-dikloretan (1). 6. Fremgangsmåte ifølge krav, karakterisert ved at oppvarmet luft (6a) blir innført i det indre rom (4) via luftledninger (7) på undersiden av virvelsjikttørkeren (1), som resulterer i fluidisering av polymerpulveret, og varmeregisterne () er oppvarmet ved

15 2 hjelp av varmt vann (a), der det varme vannet (a) blir oppvarmet ved hjelp av varmevekslere (13, ) og etterlater varmeregisterne () med avkjølt vann (b) og gjeninnføres i varmevekslerne (13, ), slik at vannet sirkulerer mellom varmeregisterne () og varmevekslerne (13, ) Fremgangsmåte ifølge krav 6, karakterisert ved at det flytende EDC fra destillasjonskolonnene til anlegget for fremstillingen av 1,2-dikloretan (1) innføres i varmevekslere (9), slik at spillvarmen fra den flytende 1,2-dikloretan blir benyttet for oppvarming av luft (6). 8. Apparat (1) for tørking av polymerpulver, som har et innløp (2) og et utløp (3) for polymerpulver og varmeregistere () som er installert i det indre rom (4) og ledninger (7) for en oppvarmet gass (6a) for tørking av polymerpulver, der ledningene er åpne inn i det indre rom (4), der ledningene (7) er forbundet til varmevekslere (9) for oppvarming av gass (6), der varmevekslerne (9) er koblet til et anlegg for fremstilling av 1,2-dikloretan (1) og/eller for fremstilling av vinylklorid fra 1,2-dikloretan, slik at termisk energi fra anlegget for fremstilling av 1,2-dikloretan (1) og/eller for fremstilling av vinylklorid kan anvendes for oppvarming av gassen (6), og varmevekslere () som det strømmer varmt vann gjennom, idet den varme fluid (a) er forbundet med en varmeveksler (13, ) for å oppvarme fluidet (b) som strømmer gjennom varmeregisteret (), og der varmeveksleren (13, ) i tillegg er forbundet via ledninger (11, 14) til anlegget for fremstilling av 1,2-dikloretan (1) og/eller for fremstilling av vinylklorid fra 1,2-dikloretan, i hvilket en varm fluid for oppvarming av fluidet (b) er innført og fjernet. 9. Apparat ifølge krav 8, karakterisert ved at anlegget for fremstilling av 1,2- dikloretan (1) er et direkte kloreringsanlegg eller en oksy-kloreringsanlegg.. Anordning ifølge hvilket som helst av kravene 8 til 9, karakterisert ved at apparatet er en virvelsjikttørker Apparat ifølge krav, karakterisert ved at luftledninger (7) via hvilken den oppvarmede luft (6a) innføres inn i det indre rom (4) som er anbrakt på undersiden av virvelsjikttørkeren (1), og at oppvarming av varme registre () utføres ved hjelp av varmt vann (a) som er oppvarmet ved hjelp av varmevekslere (13, ) og forlater varmeregisteret () som avkjølt vann (b) og gjeninnføres i varmevekselerne (13, ), slik at vann sirkuleres mellom varmeregistere () og varmevekslere (13, ).

16 3 12. Apparat ifølge krav 11, karakterisert ved at varmevekseleren (9) er forbundet til destillasjonskolonner fra anlegg for fremstilling av 1,2-dikloretan (1), slik at spillvarmen til den flytende 1,2-dikloretan fra destillasjonskolonnene kan utnyttes for oppvarming av luft (6).