DE2343515A1 - PROCESS FOR SOLVENT DEPARAFINATION OF MINERAL OILS - Google Patents

Description

Patent assessor

Dr. G. Schupfner Hamburg, August 3, 1973

Deutsche Texaco AG 726 / ik

2000 Hamburg 76

Sechslingspforte 2 T 73 065 (D 72.4-94-F)

TEXACO DEVELOPMENT CORPORATION 23 A 35 1 135 East 42nd Street New York, N.Y. 10017 U.S.A.

Process for the solvent dewaxing of mineral oils

The invention relates to the dewaxing of mineral oils, in particular lubricating oils, with the aid of solvents.

It is well known that many mineral oils contain paraffin or wax components that are used in the processing of the mineral oils must be removed. For the production of lubricating oils, e.g. from crude oils by distillation, usually by vacuum distillation, lube oil fractions are separated. Contain the crude lubricating oil distillates Paraffins, which give the lubricating oil a high cloud point and pour point. The solvent dewaxing process is a common way of working to separate the paraffin components of mineral oil that come from a Mineral oil / solvent mixture can be deposited in crystalline form at a low temperature. The solvent sets the viscosity of the supernatant liquid mixture so low that it crystallized from the Paraffin can be separated more completely and quickly. The solvents commonly used for this process include Ketones, such as acetone, methyl ethyl ketone, methyl isopropyl ketone, Methyl isobutyl ketone and mixtures thereof. The ketone solvent is also modified by adding aromatic hydrocarbons such as benzene or toluene ..

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In the previously known embodiments of the solvent dewaxing process the mixtures of solvent and mineral oil, in particular lubricating oil distillates, are either dewaxed in heat exchangers, in which the solution is cooled indirectly by a coolant, or in tanks in which the mineral oil solution from an evaporating coolant directly cooled, usually by flash evaporation of the refrigerant. Typical forms of this way of working are in U.S. Patents 2,067,128,216 * 773; 3 59 * and 3 55 * 896.

The previous solvent dewaxing processes are known to contain stages at very low temperature and other stages at elevated temperature be performed. The cooling capacity required to cool the system down can be significant, even if a evaporative refrigerant is used, and also that required to distill the various process streams The need for thermal energy can be considerable.

The invention has for its object the solvent dewaxing process to improve energy efficiency and to reduce the necessary system and operating costs.

The invention relates to a method for dewaxing mineral oil by mixing it with one ! solvent and a liquid refrigerant, cool down of the mixture by flash evaporation of the refrigerant, Separation of the slack wax from the cooled mineral oil solution as well as washing and de-oiling treatment of paraffin, characterized by the combination of the following features:

a) Mixing the paraffinic mineral oil with the dewaxing solvent and the refrigerant under an initial pressure at which the refrigerant is in liquid phase remains,

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b) Relaxation of the resulting mineral oil / solvent / refrigerant mixture -with obtaining a refrigerant vapor of high pressure and with cooling of the mixture to a temperature at which the Slack wax crystallized out and a first slurry in the remaining mineral oil / solvent mixture forms,

c) filtering this first slurry to form a first filter cake, the crystalline paraffin and includes mineral oil / solvent mixture entrapped therein, and a first Filtrate, which consists of dewaxed mineral oil and solvent,

d) Cooling the high pressure refrigerant vapor by indirect Heat exchange with the first filtrate,

e) condensing the cooled, high-pressure refrigerant vapor _t

f) recycling of the condensed, under high pressure standing refrigerant in the mixing stage a), and

g) Extraction of dewaxed mineral oil and de-oiled paraffin from the first filter cake.

The process of the invention can be used with wax or paraffin- containing oils of vegetable origin, such as so-bean oils, of animal origin, such as by-products of meat processing, or with mineral oils, typically lubricating oil fractions.

The oil used can contain paraffin or wax in proportions of typically 5 - 25 % . In the case of vegetable oils, the paraffin component can contain saturated acids and the oily component can contain unsaturated acids. In the case of animal oils, the paraffin

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constituent iriglycerides and the oily constituent mono- and di-glycerides. In the case of mineral oils, the Paraffin component high molecular weight paraffins and the oily component low molecular weight hydrocarbons, contain unsaturated compounds and aromatic compounds.

The preferred feed oil is a mineral oil, typically a Refined vacuum distillate that is suitable as a base oil for an SAE 20 engine oil. The paraffin-containing feed oil can have the following properties, for example:

Tabel

⁰ C More general Preference more typical characteristic Wt% area area way Density, ^α ΑΡΙ C. 28-34 30-31 30.6 ASTM breakpoint 37.8 ° C, cSt. 35-50 40-45 4-1 Paraffin content, 5-30 8-12 10.2 Cloud point, ° 4-5-60 50-55 50 Viscosity at 70-90 75-80 78

In the following, the term "parts" refers to parts by weight.

In the method of the invention, 1 part paraffin-containing oil can be mixed with 1-7 parts, preferably 2-4 parts, about 3 parts solvent and 0-8, preferably 2-4, about 3 parts of the liquid coolant. Further liquid coolant should preferably be added during the cooling treatment described below so that the desired final temperature of the mixture is reached. Preferably about 75 % of the coolant should be introduced with the feed oil and 25 % of the coolant added to the cooling vessel after the cooling treatment has started.

The solvent can be methyl ethyl ketone, methyl isopropyl ketone, Contain methyl isobutyl ketone and their mixtures. This ketone solvent is preferably modified

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with an aromatic solvent such as benzene or toluene. The preferred solvent is a mixture of equal parts of methyl ethyl ketone and toluene.

Hydrocarbons such as ethane, Ethylene, propane, butene and the like., Halogenated hydrocarbons such as Dichloro- or difluoromethane or ammonia and the like can be used. One is preferred Hydrocarbons, especially propane.

This mixture employed having a temperature of 10 80, preferably 25 - 17.6 ata, preferably from 16.2 17.6, so about 16 - possess 35 ⁰ C, or about 30 ⁰ C, and under a pressure of 1.05 , 9 ata (holding the refrigerant in liquid phase) can stand, is at 25-100, preferably 45 - 55 ⁰ C, or about 50 ⁰ C., and dadurch- complete dissolution of the constituents of the feed mixture reached. Then, the feed mixture, the total of from 2 - is 16, preferably 5-9 »or about 7 parts, 20 - 95, preferably 40 - 50 ⁰ C, or about 45 ° C under a pressure from 4.57 to 17» 6, preferably 16.2-17.6 ata, i.e. about 16.9 ata, cooled; under these conditions the feed mixture is above the temperature at which paraffin precipitation begins.

The oil / solvent / coolant mixture cooled in this way is fed to an evaporative cooling, which typically takes place in a vertically arranged cooling container. There the mixture is exposed to a reduced pressure in a first cooling stage for 3-100, preferably 25-75 minutes, that is to say about 55 minutes. The cooling rate can be regulated by a suitable setting of a high pressure control valve at the outlet of the cooling container. During the cooling process, additional coolant (typically 25 % of the total amount of coolant) can be introduced directly into the cooling container, where it generates further cooling through evaporation.

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If the pressure exerted on the mixture obtained is reduced, evaporation of the coolant takes place at the same time causes the mixture to cool down to a temperature at which the paraffin crystallizes out and a first slurry of paraffin in the remaining oil / solvent mixture and the one under high pressure Generates coolant vapor.

With the help of a throttle valve, the cooling rate is set to 0.25 - 8.5, preferably 0.4 - 0.7 ° C / min, so set about 0.55 ° C / min. During this cooling period of 3-100, preferably 25-75 minutes, that is about 55 minutes, the temperature can drop to -5-16, preferably 14-16 ° C, i.e. about 15 ° C, if the Pressure drops to around 3 »5 - 8.1, preferably 6.7 - 8.1 ata, i.e. around 7.4 ata. 50 - 80, preferably 66 - 70%, that is about 65% »of the liquid coolant evaporate than under high pressure coolant vapor stream, the amount of which is about 1.5-2.4, preferably 1.8-2.1 parts, i.e. 2 parts, amounts to. After completion of this first cooling stage, the high-pressure control valve is closed.

When the pressure prevailing in the cooling container has fallen to the above values, the high-pressure regulating valve is preferably closed and the evaporating liquid coolant is fed into a low-pressure system. The mixture consisting of oil, solvent and coolant can be further cooled during this second cooling stage via a low-pressure control valve. With the aid of the low-pressure control valve, the pressure can be reduced to about 1.05-3.9, preferably 2.1-2.8 ata, ie about 2.45 ata will be reduced. This is to the mixture at a rate from 0.25 to 8.5, preferably 0,4 - 0,7 ° C / min, or about O, 55 ° C / min up to a temperature .of -40 to-7, preferably ~ 20 to -15 ° C, i.e. about -18 ⁰ C cooled.

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During this second cooling stage, 45 - 75, preferably 55 - 65% that is about 50% of the liquid Evaporate solvent ("based on the amount of coolant originally used in the first cooling stage), and 1 - A-, preferably 1.4-3 parts, i.e. about 2 parts, of the low-pressure refrigerant vapor can be withdrawn from the cooling tank.

During the cooling, which is preferably carried out in 2 stages, the oil / solvent mixture is cooled to a point in which the paraffin crystallizes and separates out of the mixture in the form of a first slurry. The composition of this first paraffin slurry, in terms of parts, can be approximately as follows be:

Tabel

General typical ingredient range range preferred

Paraffin 0.05-0.25 0.10-0.15 0.12

oil 0.95-0.75 0.90-0.85 0.88

Solvent 1.00-7.00 2.00-4.00 3.00

2.00-8.00 3.00-5.00 4.00 in total

When the cooling and crystallization has ended and the low-pressure control valve has been closed, the first slurry withdrawn from the cooling tank and passed to a first filter. In the first filter stage the paraffin can be separated from the oil / solvent mixture as fiohparaffin. Typically one obtains 0.15-0.50, preferably 0.20-0.30 parts, i.e. about 0.25 parts, raw paraffin, the 0.03-0.38, preferably 0.08-0.18 Parts, i.e. about 0.13 parts included oil. The first filtrate is obtained at -4Ö to -7, preferably -2O to -15 ° C, i.e. about -18 ° C under a pressure of 1.05-3.52, preferably 1.05-1.41 ata, i.e. about 1.05 ata, in a total amount of 2.0-6.0, preferably 4.0-4.5 parts, i.e. about 4.25 parts. The first filtrate can

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0.50-0.85, preferably 0.70-0.80 parts, i.e. about 0.75 parts, oil, 0.5-6.5, preferably 5.0-5.0 parts, so about 3 »5 parts solvent (including 1-2, preferably 1.25-1.75 »ie about 1.5 parts washing solvent) and less than 0.05, preferably 0.01-0.03 Parts, i.e. about 0.01 part paraffin.

A feature of the method according to the invention is that the high pressure coolant vapor is cooled and at least partially condensed by indirect heat exchange with the first filtrate. Typically 1.5-2.4, preferably 1.8-2.1 parts, i.e. about 2 parts, of the high-pressure coolant vapor, which has a temperature of 10-50, preferably 20-40, that is about 30 ⁰ C "and is under a pressure of 4.57-17.6, preferably 16.2-17.6 ata, i.e. about 16.9 ata, to -5-16, preferably 14-16 ^° C, that is cooled about 15 ° C. A part, namely 5-85, preferably 70-80%, that is about 75%, of this coolant vapor flow is used. through, the first filtrate condenses.

The raw paraffin obtained in the first filter stage can contain 0.2-2.0, preferably 0.5-1.5 parts, i.e. about 1.0 parts, of solvent at -40 to -7, preferably -20 to -15 ° C, that is to say about -18 ⁰ C, are mixed to a second slurry, which is fed to a second filter stage. Here it is filtered at -37 to -4, preferably -18 to ~ 12 ^o C, ^{i.e. about -15 0} C, and results in a second filter cake which is 0.15-0.2, preferably 0.15-0.18 parts , i.e. about 0.18 part of de-oiled paraffin. The second filtrate is obtained at these temperatures in an amount of 0.5-1.5, preferably 0.75-1.25 parts, i.e. about 1.0 part (including 0.3-0.7, preferably 0.4 0.6 parts, i.e. about 0.5 part washing solvent).

It is "another feature of the process of the invention that the second filtrate has an indirect heat exchange the cooled, partially condensed, under high pressure

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standing coolant (or with the still vaporous part of the high pressure coolant) · Typically the cooled, partially condensed, high pressure coolant is used in amounts of 1.5 2.4, preferably 1.8-2.1 Parts, so about 2 parts (which is 60-80, preferably 70-80%, so about 75 % in the liquid phase) at -5-16, preferably 14-16 ° C, so about 15 ⁰ C and 4, 57-17.6, preferably 16.2-17.6 ata, further condensed, so that almost 100 % of the coolant condenses (ie including the portion liquefied with the first filtrate). This condensate should preferably be undercooled at its boiling point (bubble point) and as little as possible.

*) about 16.9 ata

It is a further feature of the process according to the invention that the recirculated coolant under high pressure is used in an amount of 1.5-2.4, preferably 1.8-2.1 parts, i.e. about 2 parts, with -5-16, preferably 14-16 ° or about 15 ⁰ C at 4.57 C - 17.6, preferably 16.2 to 17.6 ata so about 16.9 ata, is shared ,,; a partial flow, typically 1 *, 0 part, is mixed with the second piltrate, which is passed into the coolant collecting vessel, and a second partial flow, typically 1.0 part, is returned to the cooling container, preferably in the second cooling stage to effect further cooling.

The second piltrate, the amount of which is 0.5-1.5, preferably 0.75-1.25 parts, i.e. about 1.0 part, forms when added to the cooled stream of the high-pressure coolant Mixture containing 0.1-0.5, preferably 0.2-0.4 parts, i.e. about 0.29 parts, of oil; 0.001-0.05, preferably 0.005-0.02 part, i.e. 0.01 part, paraffin; 0.5 - 1.5, preferably 0.6 - 0.8 parts, i.e. 0.7 parts, solvent and 0.05 - 1.5, preferably 0.75 - 1.25 parts, i.e. 1.0 part, Solvent at -15 20, preferably 5-15 ° C, so 10 ⁰ C, contains.

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It is another feature of the method of the invention, the low-pressure refrigerant vapor from -25 - 10, preferably -5 - ⁰ ° C, that is -1.5 ° C and from 1.05 to 3.87, preferably 2.11 to 2 , 81 ata, i.e. 2.46 ata, to be mixed with 5-15, preferably 8-12 parts, i.e. 10 parts, of the circulating refrigerant from -10-10, preferably -5-5 ° C, i.e. O ⁰ C and the same pressure.

The mixed refrigerant streams are then, preferably 16.2 1.05 19.3 - 18.3 ata, so 17.6 ata, and 20-80, preferably 60 - 7O ⁰ C, so compacted 65 ° C and then, if necessary, cooled and condensed to 40-70 ^° C., that is to say about 45 ^° C.

1-4, preferably 1.4-3 parts, i.e. 2 parts, of the cooled Coolant is the compressed, high-pressure coolant flow that enters the coolant sump is passed, added. 5-15 »preferably 8-12 parts, i.e. 10 parts, of a withdrawn secondary flow of the cooled coolant can be put into a solvent cooler be passed, in which they cool the solvent. If it goes through the solvent cooler, warmed up it is -40 - 0, preferably -40 to -15 ° C, about -35 ° C, if it is 1.05 - 2.11, preferably 1.05 1.41 ata, about 1.05 ata, is evaporated.

The vaporized refrigerant branch current is compression to 1.05 - 2.81 ata, about 2.46 ata, and -10 - - 3.87, preferably 2.11 10, preferably -5 - 5 ⁰ C, or about 0 C, and then mixed with the ^ stream of lower pressure refrigerant vapor coming from the cooling tanks.

In practicing the method of the invention, the first Piltrat after it has dropped to -5 - 4-5 » preferably -15 - 20 ° C, i.e. about 17 ° C, was heated by heat exchange against the high-pressure refrigerant vapor, further heated up to about 150 ° C and in a plant for

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Stripping the dewaxed oil passed. Stripping solvent from the dewaxed oil yon may be about 1.05 - 1.41 ata, or about 1.30 ata, be carried out in a stripping column, and produces as an overhead (product at 90 - 120, preferably 100 to 110 ⁰ C, ie 104 ° C) 0.5-6.5, preferably 1.5-3.5 parts, ie about 3 »5 parts, solvent that condenses with water and can be passed into a solvent container.

From the stripping column, 0.55-0.9, preferably 0.7-0.8 part, about 0.75 part, of the stripped dewaxed oil was drawn off. This dewaxed oil can have the following properties:

Tabel

General more preferred more typical area area value 28-34 30-31 30.4 -40- 0 -20 to-10 -15 0 , 005-1.0 0.01-0.03 • 0.01 -35- 5 -15 to-5 -10 cSt . 65-85 70-75 75

characteristic
Density, ⁰ API
ASiEM stack point, ⁰ C
Paraf fingehalt, wt.
Cloud point, ⁰ C

The second filtrate, which is 0.25-1.5, preferably 0.5-1.0 parts, i.e. about 0.7 parts, solvent and 0.1-0.5, preferably 0.2-0.4 parts, thus contains about 0.3 parts of oil; and a temperature of -18 to -12 ⁰ O, i.e. about -15 ° 0, can be down to -10-15, preferably 0-10 ° C, i.e. about 5 ° C, by heat exchange with the cooled, high-pressure refrigerant heated and then combined with the cooled stream of the high pressure Kälteuitfcels.

The paraffin that is used as the second filter cake in the second filtration stage (in an amount of 0.1-2, preferably 1.0 - 1.5 parts, i.e. about 1.25 parts and 0.5 2, O, preferably 0.8-1.2 parts, i.e. containing about 1.0 part of solvent, is 0.5-2.0, preferably 0.75-1.5 parts, so about 1.25 parts, one

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Paraffin / solvent mixture from 75-175, preferably 100-15O ° C, so about 120 ⁰ C, washed. The wash mixture, the total amount of 1.0 - 4.0, preferably 2-3 parts, or about 2.5 parts, by weight, can be applied to 75-175 ⁰ C, preferably 100 - 15O ⁰ C, or about 120 ⁰ C, heated and 30-70, preferably 40-60%, i.e. about 50 %, of this hot mixture can be used as washing liquid.

The melted filter cake can be ^{heated up to about 150 o} C and then wiped off at 0.35-3.52, preferably 1.05-1.41 ata, i.e. about 1.3 ata. At the bottom of the stripping column, 0.15-0.20, preferably 0.15-0.18 parts, i.e. about 0.15 parts, of de-oiled paraffin, which can be drawn off at a temperature of 190-200 ° C. about 195 ° C., are obtained . The stripped solvent is used in an amount of 0,5 - 1,5, preferably 0.8 to 1.2 parts, or about 1.0 parts, at 90-120, preferably 100-110 ° C, or about 104 ⁰ C , withdrawn as overhead product, condensed in indirect heat exchange with water and passed into a solvent container.

For diluting the paraffin-containing material used 0.5 - 50, preferably 1-3 parts, alfeo about 2 parts, Solvent the solvent container with 10 - 60, in front of ^ preferably 20 - 50 ° C, i.e. about 45 ° C. 1.0-5.0, preferably 2.0-3.0 parts, i.e. about 2.5 parts, solvent taken from the solvent container at this temperature and cooled by indirect heat exchange with the partial flow branched off from the low-pressure refrigerant el flow of the cooled refrigerant. The solvent can be down to -40 to -7, preferably -20 to -15 ° C, so about 18 ° C.

A first partial stream of the cooled solvent (1.0 3.0, preferably 1.5-2.0 parts, i.e. about 1.5 parts) is used as the washing solvent in the first filtration stage passed, a second substream (0.1-1.0, preferably

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3 - 0.7 parts, i.e. approx. 0.5 parts) is used to slurry the raw paraffin in the first piIter stage and a third portion (0.1-1.0, preferably 0.3-0.7 parts, i.e. about 0.5 parts) is used as the washing liquid led to the second piIter level.

From the above general description of the invention Process shows that it leads to significant advances. It is particularly noteworthy that the improved heat exchange in the refrigerant circuit leads to a reduction in cooling capacity of 50% or more leads. This reduces the compaction effort by half, and you can either use fewer or smaller compressors. Through this diminution of the plant · * · - and operating costs can be deparaffinized Manufacture oil with significant savings.

Furthermore, the method according to the invention makes it possible the complex compressors for the refrigerant vapors too replace with liquid pumps, and the savings associated with this replacement lower the cost of capital to 0.03 - 0.1%, based on the cost of the compressors for refrigerant vapors.

The method of the invention will be explained in more detail using a preferred embodiment. As far as nothing otherwise stated, all listed "parts" are Parts by weight.

The following detailed description of the method of the invention is made in conjunction with the drawing, which depicts a flow sheet of the process of the invention.

In this embodiment, a paraffin-containing mineral oil was used, which is a solvent-refined one Vacuum distillate was suitable as a base oil for the production of an SAE 20 engine oil. It had a density

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of 30.6 ⁰ API, an ASTM pour point of 41 ⁰ C, a cloud point of 50 ⁰ C, a viscosity at 37.8 ° C of 78 cSt. and contained 10.2% paraffin.

This paraffinic mineral oil was supplied in an amount of 1 part at 3O ° C through line 10, introduced in line and mixed with two parts of solvent of 3O ⁰ C. The solvent used for dewaxing contained 50 % methyl ethyl ketone and 50 % toluene. This feed mixture went with 30 ⁰ C and 17.6 ata in the heat exchanger 13 (which was heated with steam from line 14), where it was brought to 55 ° C and 17.2 ata? intimate mixing and complete dissolution were achieved. The feed mixture was passed into the heat exchanger, which was cooled by cooling water from line 16. The feed mixture leaving the heat exchanger 15 to 43 ° C and 16.5 ata 17 by line into the line were 4.1 parts by line 12 propane refrigerant and second Piltrat 6 ⁰ C and 16.5 ata eingeleitet5 is under this pressure the propane refrigerant is kept in the liquid phase. The mixing of the propane coolant and the oil solution takes place at the junction of the lines 12 and 17 and in the distribution line 18.

The cooled mixture of oil, solvent and coolant obtained passes through this distribution line 18 the cooling section of the system. This cooling section exists in the embodiment of the invention explained by way of example from a group of 4 cooling containers 22,22 a - c, which are arranged in parallel. Belongs to every cooling container a feed line 19 or 19 a - c, an inlet valve 20 (or 20 a - c) and a feed line 21 (or 21 a - c). Each cooling tank 22 is provided with a line 23 for the high pressure coolant vapor as well as provided with a high pressure non-return valve 24 / A high pressure outlet line 25 (or 25 a - c) leads from these valves 2.4 into a high pressure collecting line 26, which is provided with a check valve 27.

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Each of the cooling containers 22 is also provided with a line 28 (or 28 a - c) for the low-pressure coolant vapor and a (check) outlet valve 29 (or 29 a - c) is provided, which allows the passage of the low-pressure refrigerant vapor to Manifold 30 regulates. In the manifold 30 is a Low-pressure (non-return) control valve 31 is arranged.

With each of the cooling containers 22 is an outlet conduit 32 (or a - c) for the paraffin slurry as well as outlet valves 33 (or 33 a - c) connected to the flow of the Slurry to collector. 34 taxes. A collecting line 35 egj ^ hJuUb * further coolant valves 36 (or 36 a - c), which control the passage of coolant through line 37 (or 37 a - c) during the cooling process.

The cooling containers 22 and 22 a - c are operated with the following sequence of stages: a) filling, b) first cooling stage with Development of high pressure refrigerant vapor c) second cooling stage with development of low pressure refrigerant vapor and d) emptying. Each cooling container is at one time in one Stage of this program sequence, and the inlet and outlet valves (i.e., valves 20, 24, 29 and 33) become corresponding opened or closed in this program sequence to allow the materials to pass through.

*) - certain

The cooled oil / solvent / refrigerant mixture in Line 18 (the partially paraffin-containing feed oil, contains three parts propane coolant, 1.1 parts second filtrate and two parts solvent), goes with 43 C and 16,5 ^ ta via the distributor 18, the inlet line 19, the opened inlet valve 20 and the inlet line 21 in the cooling container 22. In this filling stage of the periodic Valves 36, 33, 24 and 29 are closed during the working process. It goes without saying that the cooling container 22a, 22b and 22c or possibly others can be operated in a different manner during the filling of the cooling container 22 can ^ So, for example, the cooling container 22a in the first cooling stage, the container 22b in the second

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Cooling stage are located and the container 22c are emptied. For the sake of simplicity, the description will be of this Working sequence limited to the cooling container 22.

When the cooling vessel 22 is full, valve 20 is closed, valve 24 is opened, and the propane refrigerant is allowed to evaporate until the pressure in cooling vessel 22 has dropped from the initial pressure of 16.2 ata to the final pressure of 7.38 ata. The temperature in the container 22 drops to 15 ° C. and 50 % of the paraffin contained in the feed oil precipitates and forms a slurry.

By controlled opening of the high pressure non-return valve 27, the cooling rate in the cooling container is set to preferably about 0.55 ° C./min. While escape this first or high pressure cooling stage 2 parts propane under high pressure through valve 27.

At the end of the first cooling stage, the pressure in the cooling container 22 is 7.38 ata and the temperature is 15 ° C .; this State is reached after about 55 minutes. Part 1 ″, G of further refrigerant is now discharged into the cooling container 22 Collector 35 via line 37 and valve 36 (which is now open is) let in.

Then valve 24 is closed. The low-pressure outlet valve 29 is then opened and the second cooling stage begins under the control of the low-pressure check valve 31. The cooling rate is regulated to about 0.55 ° C./min and within about 60 minutes the pressure drops to 7.38 2.46 ata and the temperature of 15 C to -18 ⁰ C. In this period are deposited a further 50% of the wax from, and the first slurry contains 0.25 parts of paraffin and 3.85 parts liquid.

After completing the cooling stages, the first Slurry was drained from vessel 22 through valve 33 in 30 minutes. fzii. this time are the

Valves 20, 24, 29 and 36 are closed and valve 33 is open) and goes through the collector 34- to the first filter 38. The filtration at -18 ⁰ C and 1.05 ata yields 4.25 parts first filtrate through line 39 is discharged and contains 0.75 parts of dewaxed oil and 3.5 parts of solvent. The first filter cake, discharged through line 40, consists of raw paraffin.

The two parts of the high-pressure refrigerant vapor, which ^{leave valve 27 with an average temperature of 30 °} C. and 7.38 ata, go through line 41 to collector 42 and from there via line 43, valve 44 and line 45 to the first high-pressure cooler and condenser 46 ', where they are cooled by heat exchange with the first filtrate of -18 ° C and 17 »6 ata. During this heat exchange, the first filtrate, which is fed in via line 39, pump 63 and line 64, is heated to 17 ° C. and the coolant is cooled to 15 ° C. at 6.68 ata and partially (75%) condensed.

The Eohparaffin (1.35 parts) obtained in the first filter 38 is supplied with 0.5 parts of solvent from -18 ⁰ C, via line 46, is mixed to a slurry or mash which via line 40 to the second filter 47 goes. Filtration of the suspended slack wax in the second filter 47 gives 1.25 parts of de-oiled paraffin filter cake which still contains solvent and 1.1 parts of a second filtrate at -15 ° C. which also contains solvent. The second filtrate is conveyed from the pump 49 via line 48 ^X -15 ⁰ C in the heat exchanger 50 where a ^v heat exchange with the cooled high pressure refrigerant vapor exiting the heat exchanger 46 via line 51, takes place.

The second filtrate at -15 ° C from line 52 is heated as it passes through the heat exchanger 50 and leaves him via line 53 at 5 ° C in the liquid phase under 17.6 ata. The remaining high pressure refrigerant vapor is at

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his passage through. Heat exchanger 50 to a liquid (in line 54) ″ and goes into line 56 via pump 55 and from there to the collector 57- ♦) condenses

1 part of the liquid refrigerant at 15 ° C. is conveyed from line 56 through line 58 into line 55 and then to the cooling container 22, into which it is introduced before the start of the second cooling stage. . 1 part of the liquid in line 56 passes through the collector 57 and is mixed with the second filtrate of 5 ° C from line 53 to a mixture of 12 ⁰ C.

Another embodiment provides for the coolant in line 51 to be brought into direct contact with the flow from line 52, thereby omitting line 53 and replacing heat exchanger 50 with an absorption vessel and conveying away all of the liquid through line 54-. The mixture of the second filtrate and the condensed high-pressure coolant vapor is combined in the collector 57 with the returned liquid low-pressure coolant, which flows in from line 99 in an amount of 2 parts at 43 ° C and 17 »6 ata, and the mixture obtained ( Total amount 4.1 parts) at 16 ^° C. and 17.6 ata is sent via collector 57 into the solvent return tank 59, with the solvent from tank 59 via line 60 into the heat exchanger 61, in which it is raised by means of steam from line 62 43 C is heated, and finally in line 12 sent üie 2 parts of low-pressure refrigerant vapor of -1.5 ° C and 2.46 ata, which are withdrawn from the cooling container 22 via line 28, valve 29 and collecting line 30 under the control of valve 31 are combined with 10 parts of refrigerant from line 65 at a point downstream of the low-pressure valve 31, the mixture is brought to 55 ° C and 18.3 ata in the compressor 66 and goes via line 67 into the condenser 68, which is through Kü hlwasser from line 69 is cooled. The condensed low-pressure refrigerant is discharged at 43 ° C and 17.6 ata through line 70 and divided into two parts, which are through.

409810/0973

Line 99 go into collector 57 and into 10 parts that go via line 71 into the heat exchanger 72.

In the heat exchanger 72 of the second portion of the low-pressure refrigerant with 43 ⁰ C and 17.6 ata from line 71 is vaporized and brought to -40 ° C and 1.05 ata, by cooling the solvent stream from conduit 73 to -18 ⁰ C. and discharged with 17.6 ata in line 74. The evaporated refrigerant in line 75 is brought to ⁰ ° C. and 2.46 ata in compressor 76 and conveyed through line 65 to the inlet of compressor 66 at collector 30. The compressed refrigerant can pass into the header 57 through line 65.

2.5 parts of the solvent from line 74 go to collector 77 and 1.5 parts of this amount are fed via line 78 as washing liquid for the filter cake of the first filter 38. 0.5 parts go from the collector via line 46 to the slurry of the raw paraffin and a third partial stream (0.5 parts) reaches the second filter 47 via line as a washing agent for the filter cake.

The first filtrate, which is brought into heat exchange with the high-pressure refrigerant vapor in heat exchanger 46 * through line 39, pump 63 and line 64, then passes through in an amount of 4.25 parts and at 17 ° C. and 16.9 ata Line 80 to heat exchanger 81, which is heated by steam from line 82, and passes into stripper 83 for the dewaxed oil. The overhead product, which contains 1.75 parts of toluene and 1.75 parts of methyl ethyl ketone, goes at 104 ° C. and 1.30 ata via line 84 to condenser 85, which is cooled with water from line 86, and finally on to solvent container 87.

At the bottom of stripper 83, dewaxed oil with 2O5 ° C and 15.5 ata is obtained and discharged via line 88 in an amount of 0.75 parts. The dewaxed oil has a density of 30.4 ⁰ API, an ASTM pour point of

409810/0973

a cloud point of -10 ⁰ C, an ity at 37 »<
content of 0.01 %.

Viscosity at 37.8 ° C of 75 cSt. as well as a paraffin

The paraffin (0.15 part) obtained on the second filter in an amount of 1.25 parts is mixed with 1.25 parts of recycled paraffin / solvent mixture from
120 ° washed and forms a washing mixture of 60 ⁰ C, the 0.30 parts of paraffin and 2.2 parts of solvent contains, enters a heat exchanger 90 via line 89 and there with steam from line 91 to 120 ⁰ C at 7.03 ata is brought. 1.25 parts of this hot mixture are drawn off and go via line 92 into the washing stage of the second filter 4-7. 1 »25 parts of the hot mixture pass over
Line 94- in. The paraffin scraper 93 ·

At the top of the stripper 93 1.0 part of the solvent having 104 ⁰ C and 1.30 ata removed via line 95 and heat exchanger 96 which is cooled by water from line 97, condensed. The condensate is in the
Solvent container 87 out. The de-oiled paraffin
is withdrawn via line 98 in an amount of 0.15 parts at 195 ° ^{C and 1.4-1 ata.}

The method of the invention makes it possible to use the
Significantly reduce the operating and capital costs of a dewaxing plant. In the preferred embodiment described, the saving in compression costs (for compressing the high-pressure refrigerant vapor) amounts to about 50%, so that the number of compressors is increased
can reduce by half. This reduces the investment costs of a dewaxing plant by 20%.

- 21 -

40981 0/0973

Claims (7)

T 73 065 claims 1) Method of dewaxing mineral oil by mixing it with a solvent and a liquid refrigerant, cooling the mixture by flash evaporation of the refrigerant, Separation of the slack wax that separates out from the cooled back oil solution as well as washing and de-oiling treatment of paraffin by combining the following features: a) Mixing the paraffin-containing mineral oil with the dewaxing solvent and the Refrigerant under an initial pressure at which the refrigerant remains in the liquid phase, b) Relaxation of the resulting mineral oil / solvent / refrigerant mixture with the production of refrigerant vapor of high pressure and with cooling of the mixture to a temperature at which the slack wax crystallizes out and a first slurry in the remaining mineral oil / solvent mixture forms, c) filtering this first slurry to form a first filter cake that is crystalline Contains slack wax and mineral oil / solvent mixture enclosed therein, and a first Jfiltrate, which consists of dewaxed mineral oil and solvent, d) cooling the high-pressure refrigerant vapor by indirect heat exchange with the first filtrate, e) condensation of the cooled, high-pressure refrigerant vapor, -22 - 409810/0973 f) returning the condensed, high-pressure refrigerant to the mixing stage a), and g) Extraction of dewaxed mineral oil and de-oiled paraffin from the first filter cake. 2) Method according to claim 1, characterized in that that a part, especially about 5 85% »of the high pressure refrigerant vapor after d) and e) is condensed with the first filtrate. 3) Method according to one of claims 1 or 2, d a characterized in that the first filter cake with another Solvent mixed into a second slurry and separated them into deoiled paraffin and a second filtrate containing mineral oil and solvent and the high pressure refrigerant vapor after being cooled with the first filtrate is further cooled and condensed by indirect heat exchange with the second filtrate. 4) Method according to claim 3i, characterized in that that the second filtrate, which is used for condensation of the precooled with the first filtrate High pressure refrigerant vapor was used, with the condensed, high pressure refrigerant is united. 5) Method according to one of claims 1-4, d a characterized in that at least part of the refrigerant liquefied under high pressure is used directly to cool the refrigerant to be dewaxed Mixture is returned. - 23 409810/0973 6) Method according to one of claims 1-5, d a through marked that the pressure on the mineral oil / solvent / refrigerant mixture is reduced in this way in two stages becomes that one In the 1st stage, part of the refrigerant evaporates at high pressure and the remainder of the mixture cools down until crystalline raw paraffin separates, in the 2nd stage this mixture is relaxed down to a low pressure and thereby up to renewed The precipitation of crystalline raw paraffin continues to cool, separating the slack wax portion of the first slurry obtained, and having the low pressure Refrigerant vapor is compressed, condensed and partly for mixing with fresh mineral oil and Recirculates solvent. 7) Method according to claim 6, characterized in that g e mark e i chnet that a · second part of the condensate obtained from medium pressure refrigerant vapor in indirect heat exchange with the solvent introduced into the filter stage as a washing agent is brought. 409810/0973 Le e rs e We