Title of Invention	"METHOD FOR CLEANING A REACTOR"
Abstract	The present invention relates to a method for cleaning a reactor having a tendency of fouling by deposition of solids, wherein a hot solvent, in which the solids are soluble and which has a temperature of at least about 75°C, is applied to the reactor, the solids being substantially dissolved and the dissolved solids being discharged from the reactor, wherein the method is carried out without opening the reactor to atmosphere.

Title of Invention

"METHOD FOR CLEANING A REACTOR"

Abstract

The present invention relates to a method for cleaning a reactor having a tendency of fouling by deposition of solids, wherein a hot solvent, in which the solids are soluble and which has a temperature of at least about 75°C, is applied to the reactor, the solids being substantially dissolved and the dissolved solids being discharged from the reactor, wherein the method is carried out without opening the reactor to atmosphere.

Full Text	The present invention relates to a method for cleaning a reactor having a tendency of fouling by deposition of solids. Reactor fouling is especially a problem related to polymer technologies, i.e. oligomerisation and polymerisation reactions, for example the polymerisation of polypropylene, polyethylene, poly-stvrene and the like. As a consequence of "fouling", the reactor has to be cleaned periodically, and, preferably, a spare reactor is required. For cleaning of the reactor having solids (e.g. high molecular weight oligomers/polymers) depos¬ited, the reactor has to be opened, and plant personnel has usually to enter the reactor for clean¬ing thereof mechanically. After cleaning, the reactor has usually to be inertised to be ready for a further oligomerisation or polymerisation reaction. A typical reactor downtime for cleaning is about 1 week. Thus, a cleaning operation adds to the costs of the product to be produced. Therefore, it is an object of the present invention to provide a method for cleaning a reactor hav¬ing a tendency of fouling by deposition of solids, which method overcomes the disadvantages of the prior art. Especially a method shall be provided which does not require mechanical cleaning, reduces the reactor down time, does not require purging/inertizing before/after cleaning and im¬proves plant safety. This object is achieved in that a hot solvent, in which the solids are soluble, and which has a temperature of at least about 75°C, is applied to the reactor, the solids being substantially dis- solved and the dissolved solids being discharged form the reactor, wherein the method is carried out without opening the reactor to atmosphere. Surprisingly, it was found that using the inventive method for cleaning a reactor, no mechanical cleaning is necessary and the reactor downtime for cleaning is significantly reduced. Further, no purging/inertizing of the reactor before/after cleaning is necessary any longer as the reactor has not to be opened. Also, an automatic cleaning procedure may be provided by a sequence control, and the need of a spare reactor is eliminated. Finally, the plant safety is improved, since no plant personnel has to enter the reactor for cleaning and the risk of hydrocarbon exposure to atmos¬phere is eliminated. The term "reactor", as used herein, is not only related to the reaction vessel as such, but encom¬passes all equipments connected to the reaction vessel, such as pipes, supply vessels, distillation columns and the like. Someone skilled in the art is therefore aware of the necessary equipments which are included in the term "reactor". The inventive method may be applied to all chemical reactors which have a tendency of fouling by deposition of solids, especially to polymer tech¬nologies, such as a polymerisation of polypropylene, polyethylene or polystyrene. It is preferred that the reactor is an oligomerisation or polymerisation reactor. Most preferably, the reactor is an oligomerisation reactor for the oligomerisation of ethylene to obtain linear alpha-olefins. Preferably, the solvent is an organic solvent, more preferably a hydrocarbon solvent. The solvent may be selected from toluene, xylenes, benzene or mixtures thereof. Toluene is the most preferred solvent. In one aspect the dissolved solids are transferred to a solvent recovery unit. In a further aspect the solvent may be recovered by distillation, crystallization, thin-film evapora¬tion, whiped-film evaporation and/or falling-film evaporation. In a preferred embodiment the solvent is heated by external heating and/or within the reactor by means of runaway of a reaction carried out therein. More preferably, the external heating is provided by a heat exchanger. The inventive method is preferably applied to the reactor immediately after the process regularly carried out in that reactor has been finished. Preferably, the inventive method may be utilized in an oligomerisation reactor for the oligomerisation of ethylene to obtain linear alpha-olefms. Af¬ter having finished the oligomerisation reaction, hot solvent, preferably hot toluene, having a temperature of about 100 to 130°C, is introduced into the reactor and its equipment. In an alter¬native the solvent may be heated after introduction into the reactor. The hot toluene is then dis¬tributed throughout the reactor and its equipment to dissolve the solid deposits, especially high molecular weight oligomeric/polymeric deposits on the reactor walls. As the deposits are soluble in hot toluene, they may be discharged from the reactor easily by discharging the toluene. The solids dissolved in hot toluene may be then transferred to a solvent recovery unit, such as a distil¬lation column, to separate the dissolved solid from the solvent. The solvent may then be recycled into the reactor for further cleaning thereof, or may be stored for further use. Due to its unique solubility for high molecular weight oligomers/polymers, toluene is the most preferred solvent for use in oligomerisation and polymerisation reactors. The features disclosed in the foregoing description or in the claims may, both separately and in any combination thereof, be material for realizing the invention in diverse forms thereof. Claim: 1. Method for cleaning a reactor having a tendency of fouling by deposition of solids, char- acterized in that a hot solvent, in which the solids are soluble and which has a tempera- ture of at least about 75°C, is applied to the reactor, the solids being substantially dis- solved and the dissolved solids being discharged from the reactor, wherein the method is carried out without opening the reactor to atmosphere. 2. Method according to claim 1, wherein the reactor is an oligomerisation or polymerisation reactor. 3. Method according to claim 2, wherein the reactor is an oligomerisation reactor for the oligomerisation of ethylene to obtain linear alpha-olefms. 4. Method according to any of the preceding claims, wherein the solvent is an organic sol- vent, preferably a hydrocarbon solvent. 5. Method according to claim 4, wherein the solvent is selected from toluene, xylenes, ben-zene or mixtures thereof. 6. Method according to claim 5, wherein the solvent is toluene. 7. Method according to any of the precedings claims, wherein the dissolved solids are trans- ferred to a solvent recovery unit. 8. Method according to claim 7, wherein the solvent is recovered by distillation, crystalliza- tion, thin-film evaporation, vvhiped-film evaporation and/or falling-film evaporation. 9. Method according to any of the precedings claims, wherein the solvent is heated by ex¬ternal heating and/or within the reactor by means of runaway of a reaction carried out therein. 10. Method according to claim 9, wherein the external heating is provided by a heat ex¬changer. 11. Method for cleaning a reactor having a tendency of fouling by deposition of solids substantially as herein described with reference to the foregoing description.

Full Text

The present invention relates to a method for cleaning a reactor having a tendency of fouling by deposition of solids.
Reactor fouling is especially a problem related to polymer technologies, i.e. oligomerisation and polymerisation reactions, for example the polymerisation of polypropylene, polyethylene, poly-stvrene and the like.
As a consequence of "fouling", the reactor has to be cleaned periodically, and, preferably, a spare reactor is required.
For cleaning of the reactor having solids (e.g. high molecular weight oligomers/polymers) depos¬ited, the reactor has to be opened, and plant personnel has usually to enter the reactor for clean¬ing thereof mechanically. After cleaning, the reactor has usually to be inertised to be ready for a further oligomerisation or polymerisation reaction.
A typical reactor downtime for cleaning is about 1 week. Thus, a cleaning operation adds to the costs of the product to be produced.
Therefore, it is an object of the present invention to provide a method for cleaning a reactor hav¬ing a tendency of fouling by deposition of solids, which method overcomes the disadvantages of the prior art. Especially a method shall be provided which does not require mechanical cleaning, reduces the reactor down time, does not require purging/inertizing before/after cleaning and im¬proves plant safety.
This object is achieved in that a hot solvent, in which the solids are soluble, and which has a temperature of at least about 75°C, is applied to the reactor, the solids being substantially dis-
solved and the dissolved solids being discharged form the reactor, wherein the method is carried out without opening the reactor to atmosphere.
Surprisingly, it was found that using the inventive method for cleaning a reactor, no mechanical cleaning is necessary and the reactor downtime for cleaning is significantly reduced. Further, no purging/inertizing of the reactor before/after cleaning is necessary any longer as the reactor has not to be opened. Also, an automatic cleaning procedure may be provided by a sequence control, and the need of a spare reactor is eliminated. Finally, the plant safety is improved, since no plant personnel has to enter the reactor for cleaning and the risk of hydrocarbon exposure to atmos¬phere is eliminated.
The term "reactor", as used herein, is not only related to the reaction vessel as such, but encom¬passes all equipments connected to the reaction vessel, such as pipes, supply vessels, distillation columns and the like. Someone skilled in the art is therefore aware of the necessary equipments which are included in the term "reactor". The inventive method may be applied to all chemical reactors which have a tendency of fouling by deposition of solids, especially to polymer tech¬nologies, such as a polymerisation of polypropylene, polyethylene or polystyrene.
It is preferred that the reactor is an oligomerisation or polymerisation reactor.
Most preferably, the reactor is an oligomerisation reactor for the oligomerisation of ethylene to obtain linear alpha-olefins.
Preferably, the solvent is an organic solvent, more preferably a hydrocarbon solvent.
The solvent may be selected from toluene, xylenes, benzene or mixtures thereof. Toluene is the most preferred solvent.
In one aspect the dissolved solids are transferred to a solvent recovery unit.
In a further aspect the solvent may be recovered by distillation, crystallization, thin-film evapora¬tion, whiped-film evaporation and/or falling-film evaporation.
In a preferred embodiment the solvent is heated by external heating and/or within the reactor by means of runaway of a reaction carried out therein.
More preferably, the external heating is provided by a heat exchanger.
The inventive method is preferably applied to the reactor immediately after the process regularly carried out in that reactor has been finished. Preferably, the inventive method may be utilized in an oligomerisation reactor for the oligomerisation of ethylene to obtain linear alpha-olefms. Af¬ter having finished the oligomerisation reaction, hot solvent, preferably hot toluene, having a temperature of about 100 to 130°C, is introduced into the reactor and its equipment. In an alter¬native the solvent may be heated after introduction into the reactor. The hot toluene is then dis¬tributed throughout the reactor and its equipment to dissolve the solid deposits, especially high molecular weight oligomeric/polymeric deposits on the reactor walls. As the deposits are soluble in hot toluene, they may be discharged from the reactor easily by discharging the toluene. The solids dissolved in hot toluene may be then transferred to a solvent recovery unit, such as a distil¬lation column, to separate the dissolved solid from the solvent. The solvent may then be recycled into the reactor for further cleaning thereof, or may be stored for further use.
Due to its unique solubility for high molecular weight oligomers/polymers, toluene is the most preferred solvent for use in oligomerisation and polymerisation reactors.
The features disclosed in the foregoing description or in the claims may, both separately and in any combination thereof, be material for realizing the invention in diverse forms thereof.

Claim:
1. Method for cleaning a reactor having a tendency of fouling by deposition of solids, char-
acterized in that a hot solvent, in which the solids are soluble and which has a tempera-
ture of at least about 75°C, is applied to the reactor, the solids being substantially dis-
solved and the dissolved solids being discharged from the reactor, wherein the method is
carried out without opening the reactor to atmosphere.
2. Method according to claim 1, wherein the reactor is an oligomerisation or polymerisation
reactor.

3. Method according to claim 2, wherein the reactor is an oligomerisation reactor for the
oligomerisation of ethylene to obtain linear alpha-olefms.
4. Method according to any of the preceding claims, wherein the solvent is an organic sol-
vent, preferably a hydrocarbon solvent.
5. Method according to claim 4, wherein the solvent is selected from toluene, xylenes, ben-zene or mixtures thereof.
6. Method according to claim 5, wherein the solvent is toluene.
7. Method according to any of the precedings claims, wherein the dissolved solids are trans-
ferred to a solvent recovery unit.
8. Method according to claim 7, wherein the solvent is recovered by distillation, crystalliza-
tion, thin-film evaporation, vvhiped-film evaporation and/or falling-film evaporation.
9. Method according to any of the precedings claims, wherein the solvent is heated by ex¬ternal heating and/or within the reactor by means of runaway of a reaction carried out therein.
10. Method according to claim 9, wherein the external heating is provided by a heat ex¬changer.
11. Method for cleaning a reactor having a tendency of fouling by deposition of solids substantially as herein described with reference to the foregoing description.

Documents:

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Patent Number

270602

Indian Patent Application Number

1379/DELNP/2008

PG Journal Number

02/2016

Publication Date

08-Jan-2016

Grant Date

01-Jan-2016

Date of Filing

18-Feb-2008

Name of Patentee

LINDE AG

Applicant Address

LEOPOLDSTR. 252, 80807 MUNICH, GERMANY.

Inventors:

#	Inventor's Name	Inventor's Address
1	BOLT, HEINZ	SCHIESSSTATTSTRASSE 12B, 82515 WOLFRATSHAUSEN, GERMANY.
2	MOSA, FUAD	C/O SAUDI BASIC INDUSTRIES CORPORATION, P.O. BOX 5101, 11422 RIYADH, SAUDI ARABIA.
3	ALI,TALAL	SAUDI BASIC INDUSTRIES CORPORATION, P.O. BOX 42503, 11551 RIYADH, SAUDI ARABIA.
4	AL DUGAITHER, ABDULLAH	C/O SAUDI BASIC INDUSTRIES CORPORATION, P.O. BOX 5101, 11422 RIYADH, SAUDI ARABIA.
5	FRITZ, PETER	TRUDERINGER STRASSE 21, 82008 UNTERHACHING, GERMANY.

PCT International Classification Number

B01J 19/00

PCT International Application Number

PCT/EP2006/005644

PCT International Filing date

2006-06-13

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	05017338.4	2005-08-10	EPO