BE1029920B1 - Method for emptying a solvent regeneration tank and device - Google Patents

Abstract

The present invention relates to a device for separating aromatics by means of extractive distillation, the device having an extractive distillation column, a downstream stripper column and a solvent regeneration tank 10, characterized in that the solvent regeneration tank 10 has a first valve 20 on the underside , wherein the first valve 20 is connected to a heated line 30 on the side remote from the solvent regeneration tank 10, the heated line 30 being connected to a plant 40 selected from the list comprising vacuum distillation plant, crude oil distillation plant, incinerator, storage facility, Loading facility, refinery.

Description

* BE2021/5878

Method of emptying a solvent regeneration tank and

contraption

The invention relates to a method for emptying a solvent regeneration

Container and a device therefor.

Aromatics, especially the simplest aromatic compounds benzene, toluene and

Xylene are of industrial importance as intermediates for chemical

Industry. Various technical processes are known for the extraction of aromatics. A type of process which achieves a particularly high purity of the aromatics product stream at comparatively low costs is recovery by

Extractive distillation from a feedstock stream containing hydrocarbons. As

Feedstock streams are, for example, crude petroleum, pyrolysis petrol, reformate petrol or coke oven light oil. Heavy components are preferred over the

Aromatics, for example by separating the C8 + fraction from the

Feed stream removed.

In the recovery of aromatics by extractive distillation, the feed stream is countercurrently contacted with an aromatics-selective solvent.

The solvent affects the volatility of the different components of the

Feedstock flow to varying degrees. The volatility of the aromatic components is reduced by the dilution, while that of the aliphatic components is significantly increased. In this way, a distillative separation into aromatics and

Allows non-aromatics/aliphatics. In a first step, the aromatics dissolved in the solvent are then separated from the aliphatic by means of extractive distillation

Components of the feed mixture separated, which are discharged as the top product of the distillation. In a second step, the aromatics are removed by stripping

Driven overhead from the solvent. The aromatic

Product stream are further separated into individual aromatic fractions. that on

Solvents depleted in aromatics are returned to the extractive distillation and reused. In this way, individual aromatics can be obtained in their pure form in a continuous process.

* BE2021/5878

Solvents for extractive distillation include sulfolane,

Methylsulfolane, N-methylpyrrolidone, N-formylmorpholine, ethylene glycol and their

Mixtures and mixtures of the solvents mentioned with water are known.

The solvents or solvent mixtures used are water-soluble.

EP 154677 A2 discloses a process for separating aromatics

Hydrocarbon mixtures of any aromatic content known.

Due to the permanent reuse of the same solvent in one

Solvent circuit accumulate impurities, which the process neither as

Top product of the distillative removal of the aliphatics still as a top product in the

Leave stripping of the aromatics in the solvent. Furthermore, by the

Processes preceding extractive distillation, such as hydrogenation or clay

Treatment, heavy components are introduced, which accumulate in the solvent. But also due to incorrect operation or malfunctions of the

Plant parts upstream of extractive distillation, which are used, for example, to remove higher-boiling components, can lead to increased contamination of the solvent circulating in the extractive distillation with high-boiling impurities.

Over time, the impurities cause the solvent to degrade

loses extraction power and needs to be replaced. To those with the exchange of

To reduce solvent-related costs, the possibility of purification of the solvent in the solvent circuit is desirable, through which the

impurities are removed. In this way, the cycle time up to

replacement of the solvent can be extended considerably.

To purify the solvent, it is known, for example from US 2010/0228072 A1, to subject a substream of the solvent cycle to a distillation, with the purified solvent leaving the distillation as the top product and as

Impurities remaining in the distillation residue are removed from the system.

In the solvent regeneration, a partial flow of the solvent is carried out in a bladder

Distilled overhead (batch or continuous) and leaving components that are in the

have a higher boiling point than the solvent. These are, for example, polymers, rust and solvent residues. This highly viscous residue 5 remains in the solvent regeneration tank

Solvent residues, long-chain hydrocarbons formed in the system,

rust particles and the like back. Nowadays, this is filled into barrels and then, for example, incinerated. In order to enable filling into barrels, an elevated temperature of usually 160 °C is necessary. This in turn means, in addition to the logistical effort, that there is an increased risk, especially from splashes during the filling process, which is why corresponding

Safety regulations and installations are necessary.

From CN 203976565 U is a device for recycling liquid

Lycopene waste known.

The object of the invention is to provide a method for disposing of the high-boiling

To provide residues and a suitable device, which is simpler and safer.

This object is achieved by the device specified in claim 1

Features and by the method with the features given in claim 7.

Advantageous developments result from the subclaims below

description and the drawing.

The inventive device for separating aromatics by means

Extractive distillation has an extractive distillation column, a downstream

Stripper column and a solvent regeneration tank.

Corresponding devices for separating aromatics by means of extractive distillation are known, for example, from DE 19849651 A1, DE 19958464 A1, DE 10019196 C1,

DE 10018434 A1 or DE 10038318 C1 and also known as the morphylane process.

A BE2021/5878

According to the invention, the solvent regeneration tank has a first valve on the underside. The first valve is on the solvent regeneration

Container opposite side connected to a heated line. The heated line is connected to a facility selected from the comprehensive list

Vacuum Distillation Plant, Crude Oil Distillation Plant, Incinerator,

Storage facility, loading facility, refinery.

While hitherto the accumulating in the solvent regeneration tank

After the residue was filled into drums and disposed of, this residue can now be sent for further processing without direct human interaction. As a result, on the one hand, the solvent regeneration tank can already be arranged lower, usually about 2m, since under the solvent

Regeneration tanks no space has to be provided for the arrangement of barrels. On the one hand, this reduces the effort involved in creating the device.

On the other hand, the lower arrangement also gives flexibility to others

Plant parts won.

Although it does not seem necessary at first to carry out a fixed pipework, especially since this consumes solvent and heating energy on the one hand and the

Residue typically rarely needs to be removed from the solvent regeneration tank. However, the benefit lies in the fact that the handling of the barrels and thus the direct involvement of people in this process with a hot, highly viscous liquid can be avoided and the safety of the device can thus be increased. In addition, it has been shown that the aromatic solvents and non-aromatic solvents required for this process can be recovered, at least to a large extent.

In a further embodiment of the invention, the heated line with a

Connected to non-aromatic solvent feed. Thus, the heated

Line flushed with the non-aromatic solvent. The use of non-aromatic solvent is preferred in order to avoid the more valuable aromatic

save solvent. In addition, introduction into a vacuum still or a crude still is preferred so that the non-aromatic

Solvent can be easily recovered.

> BE2021/5878

In another embodiment of the invention, the solvent regeneration

Container connected to an aromatic solvent supply. The

Solvent Regeneration Vessel is in the recovery circuit

Aromatics incorporated such that washing out the solvent regeneration vessel with non-aromatic solvents would contaminate the aromatics recovered in the overall process. The aromatic ones are preferred

Solvents from the overall process and are recycled through the preferred introduction into a vacuum distillation plant or a crude oil distillation plant

recovery fed back.

In another embodiment of the invention, the solvent regeneration

Container connected to a gas supply. Particularly preferred is the

Gas supply for charging with nitrogen. The gas supply is preferably used for

Applying a pressure of 1.5 bar to 5 bar, preferably 2 bar to 3 bar.

This allows the highly viscous residue to be removed more easily from the solvent

Regeneration tanks are discharged through the heated line.

In a further embodiment of the invention, the heated line has a length of 100 m to 2000 m, preferably 500 m to 1200 m. If the heated line becomes longer, the pressure drop across the heated line increases too much. Therefore, the heated line would then have to be heated more to reduce the viscosity, which in turn would significantly increase the operating costs.

In a further embodiment of the invention, the system is a

vacuum distillation plant or a crude oil distillation plant. This is an optimal recovery of the aromatic solvents and the non-aromatic

solvent possible.

In a further aspect, the invention relates to a method for emptying a device according to the invention. The process has the following steps: a) feeding aromatic solvent into the solvent regeneration

container, b) opening the first valve,

8 BE2021/5878 c) transferring the residue dissolved in the aromatic solvent through the heated line to a plant selected from the list comprising

Vacuum Distillation Plant, Crude Oil Distillation Plant, Incinerator,

Storage facility, loading facility, refinery.

By adding an aromatic solvent, the residue is diluted and its viscosity reduced. At the same time, contamination with non-aromatic

Solvents avoided, which would otherwise be found in the aromatic product.

Since the first valve is located at the bottom of the solvent regeneration tank, opening the first valve thereof in step b) allows the residue diluted with aromatic solvents to be transferred to the heated line in step c). This can be done solely by gravity or by additional

pressure can be achieved.

Because the residue is removed directly through the heated line and does not have to be transferred to drums, it is impossible for hot material to be used as a

Splashes can escape and injure bystanders.

In a further embodiment of the invention, aromatics obtained in step a) in the device for separating aromatics by means of extractive distillation

solvent used.

In a further embodiment of the invention, a viscosity of from 5 cP to 500 cP, preferably from 10 cP to 100 cP, particularly preferably from 20 cP to 40 cP, is set at 80° C. (1 cP=103 Pa·s) in step a). The viscosity is with a

Viscometer determined according to EN ISO 3219. At this viscosity, a transport is the

Residues over a reasonable distance in a chemical plant network are possible without excessive pressure losses occurring over the entire route.

In a further embodiment of the invention, the transfer in step c) takes place by charging the solvent regeneration tank

7 BE2021/5878

Application of a gas, preferably nitrogen. The application is particularly preferably carried out with a pressure of 1.5 bar to 5 bar, more preferably with 2 bar to 3 bar.

In a further embodiment of the invention, the following steps are carried out after step c): d) closing the first valve, e) flushing the heated line with a non-aromatic solvent.

For the rinsing in step e), a second valve is preferably opened, which connects the supply line for non-aromatic solvents to the heated line. This prevents residue from the solvent regeneration tank from entering the non-aromatic solvent feed.

In a further embodiment of the invention, the feeding in step a) takes place in such a way that the volume of the aromatic solvent fed in corresponds to approximately one to two times the volume of the residue. As a result, a dilution can usually be achieved which has the required viscosity

solution.

In a further embodiment of the invention, the heated line on a

Temperature from 40 °C to 100 °C, preferably from 50 °C to 80 °C. This represents an optimum between high temperature and lowering of the viscosity and thus of the

pressure loss and low temperature to reduce the cost of the

heating. Temperatures below 100°C are preferred to avoid or at least minimize evaporation of the non-aromatic solvent.

In a further embodiment of the invention, in step a) as an aromatic

Solvent benzene, toluene, xylene or a mixture thereof used.

In a further embodiment of the invention, before step a), the solvent

Regeneration vessel is heated to about 160°C and is cooled to about 100°C by supplying the aromatic solvent in step a).

® BE2021/5878

The device according to the invention is explained in more detail below with reference to an exemplary embodiment illustrated in the drawing.

Figure 1 Schematic representation of the solvent regeneration tank

The representation is purely schematic and serves to illustrate the invention.

In particular, the illustration is not true to scale, which can already be seen from the lines shown as lines.

In Fig. 1, the solvent regeneration tank 10 according to the invention is illustrated by means of a sketch. During operation, the

Extraction solvent supply 80 extraction solvents, e.g. sulfolane,

Methylsulfolane, N-methylpyrrolidone, N-formylmorpholine, ethylene glycol and their

Mixtures, and mixtures of the solvents mentioned with water, supplied and by heating by means of the heater 100 through the

Extraction solvent discharge 90 removed. A residue accumulates in the solvent regeneration tank 10, which has to be removed at longer intervals. To this end, the supply of extraction solvent is stopped. About the supply for aromatic solvent 60 is aromatic solvent, such as benzene, toluene, xylene or mixtures thereof, supplied so that a

viscosity of the solution inside the solvent regeneration tank 10 of about 30 cP and a temperature of 100 °C. The first valve 20 is then opened and nitrogen is fed in at a pressure of 2.5 bar via the gas supply 70 . As a result, the dissolved residue through the heated line 30 to

Plant 40, for example a vacuum distillation plant supplied. The heated

In this case, line 30 is heated to 80° C., for example, by heating the heated line 32 . After emptying the solvent regeneration tank 10, the first valve 20 is closed. The second valve 110 is then opened and the heated line 30 is flushed with a non-aromatic solvent from the non-aromatic solvent supply line 50 . The second valve 110 is then closed again.

The four valves shown in FIG. 1 can be operated manually. Alternatively and preferably, it is control valves, ie valves that are controlled by a central

9 BE2021/5878

Control system electronically controlled, in particular can be opened and closed.

Reference sign

Solvent regeneration tank 20 first valve 30 heated line 32 heated line heater 40 system 10 50 - non-aromatic solvent feed 60 aromatic solvent feed 70 gas feed 80 extraction solvent feed 90 extraction solvent discharge 100 heater 110 second valve

Claims (16)

patent claims 1. Device for separating aromatics by means of extractive distillation, the device having an = extractive distillation column, a =— downstream stripper column and a solvent regeneration tank (10), characterized in that the solvent regeneration tank (10) on the underside a first valve (20), the first valve (20) being connected to a heated line (30) on the side remote from the solvent regeneration tank (10), the heated line (30) being connected to an installation (40 ) is selected from the list including vacuum still, crude still, incinerator, storage facility, loading facility, refinery. 2. Device according to claim 1, characterized in that the heated line (30) is connected to a supply for non-aromatic solvents (50). 3. Device according to one of the preceding claims, characterized in that the solvent regeneration tank (10) is connected to a supply for aromatic solvents (60). 4. Device according to one of the preceding claims, characterized in that the solvent regeneration tank (10) is connected to a gas supply (70). 5. Device according to one of the preceding claims, characterized in that the heated line (30) has a length of 100 m to 2000 m, preferably 500 m to 1200 m. 6. Device according to one of the preceding claims, characterized in that the plant (40) is a vacuum distillation plant or a crude oil distillation plant. 7. A method for emptying a device according to any one of the preceding claims, wherein the method comprises the following steps: a) feeding aromatic solvent into the solvent regeneration tank (10), b) opening the first valve (20), c) transferring the residue dissolved in the aromatic solvent through the heated line (30) to a plant (40) selected from the list including vacuum distillation plant, crude oil distillation plant, incinerator, storage facility, loading facility, refinery. 8. Process according to claim 7, characterized in that in step a) aromatic solvent obtained in the device for separating aromatics by means of extractive distillation is used. 9. The method according to any one of claims 7 to 8, characterized in that in step a) a viscosity of 5 cP to 500 cP, preferably from 10 cP to 100 cP, particularly preferably from 20 cP to 40 cP, at 80 ° C adjusted becomes. 10. The method according to any one of claims 7 to 9, characterized in that the transfer in step c) is carried out by subjecting the solvent regeneration container (10) to subjection to a gas, preferably nitrogen. 11. The method according to claim 10, characterized in that the pressurization is carried out with a pressure of 1.5 bar to 5 bar, preferably with 2 bar to 3 bar. 12. The method according to any one of claims 7 to 11, characterized in that after step c) the following steps are carried out: d) closing the first valve (20), e) flushing the heated line (30) with a non-aromatic Solvent. 13. The method according to any one of claims 7 to 12, characterized in that the feeding in step a) takes place in such a way that the volume of the aromatic solvent fed corresponds to approximately one to two times the volume of the residue. 14. The method according to any one of claims 7 to 13, characterized in that the heated line (30) is heated to a temperature of 40 °C to 100 °C, preferably from 50 °C to 80 °C. 15. The method according to any one of claims 7 to 14, characterized in that the aromatic solvent used in step a) is benzene, toluene, xylene or a mixture thereof. 16. The method according to any one of claims 7 to 15, characterized in that before step a) the solvent regeneration tank (10) is heated to about 160 ° C and by supplying the aromatic solvent in step a) to about 100 ° C is cooled.