JPS60152595A - Improved dewaxing process for cooling slurry of solvent-oil and wax to wax filtering temperature with agitation heat exchanger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an improved process for dewaxing hydrocarbon oils, particularly petroleum oils, and most particularly lubricating oils, which comprises subjecting the waxy oil to a temperature above its cloud point in multiple stages. passing the waxy oil from stage to stage in the derrick zone, and introducing a cold dewaxed solvent into at least a portion of the stages to form a solvent-waxy oil mixture. and maintaining a high degree of agitation in at least a portion of the stage containing the solvent and waxy oil, thereby stirring the solvent-waxy oil mixture as it progresses through the direct derrick zone, preferably about 1 ~8
The solvent and the wax-containing oil are cooled at a rate of 0.5°F/min (0.6 to 4.4°C/min) to a temperature higher than the temperature at which the wax is separated from the oil, i.e., the wax separation temperature. substantially instantaneous mixing, whereby a majority of the wax is precipitated from the waxy oil under conditions of the high degree of agitation to form a solvent-oil mixture (slur IJI) containing precipitated wax; ,
The mixture containing the precipitated wax is extracted from the direct derrick zone and cooled in the indirect derrick zone to the wax separation temperature to further precipitate the wax portion from the wax-containing oil, and the precipitated wax is extracted from the wax oil in the same liquid separation means. - A dewaxing process for hydrocarbon oils separated from a solvent mixture, characterized in that an indirect heat exchanger means operated in a high-level agitation mode is used as an indirect derrick castle.The agitation increases the impeller Reynolds number. Expressed using approximately i, o o.

~1.000,000. Preferably 5.000-1.0
00,000, most preferably 10,000 to Iooo
, ooo.

The stepped agitated direct derrick zone is instead replaced entirely by high agitation indirect heat exchanger means. A multi-point solvent injection facility can be constructed arbitrarily, whereby any combination of indirect and direct derricks of the waxy oil feedstock can occur simultaneously.

In this way, the waxy oil feedstock is brought directly from a temperature above its cloud point to the wax separation temperature in the indirect heat exchanger unit or units.

By using this high agitation to avoid rapid temperature changes in the heat exchange derrick zone above 40°C (22°C) and by using a combination of direct and indirect derricks, increased feed filtration rates and dewaxed oil yields are achieved. improvement is achieved.

BACKGROUND OF THE INVENTION In the past, wax precipitation was carried out under conditions of low or no agitation. This process was continued because it was believed that precipitation under conditions of high agitation would form fine wax particles that would clog liquid-solid separators. A typical wax precipitation technique uses a 5-craped double chiller.
ce chiller) was used. In such units, the waxy oil and dewaxing solvent are premixed at a sufficient temperature to completely dissolve the oil and wax. If necessary, the opaque oil may be heated (either prior to or after the addition of the solvent) to ensure complete dissolution of the wax contained therein.

The solution is then stirred at a constant slow rate, e.g.
/min (0.6° to 2.8°C/min).

In indirectly cooled heat exchangers, wax adheres to the heat exchanger surface and stains the heat exchanger walls, so the wax is removed using a scraping device. However, by physically crushing the wax crystals formed on the chiller wall by the action of a scraping device, uneven crystal growth occurs, slowing down the filtration rate, and reducing the amount of oil trapped in the wax. The amount increases.

The DILCHILL (DILCHILL is a registered service mark of Exxon Research and Engineering, Inc.) process was developed to overcome the inherent limitations and disadvantages of scraped face derrick dewaxing. In the dilthill process, cooling is carried out in a staged column.
owner). Move the waxy oil through the tower,
The cold solvent is injected directly into the stages along the mold (either some of the stages or all of the stages have the cold solvent injected into them). Cold solvent injection is performed with high agitation in at least a portion of the stage containing the waxy oil and solvent to ensure substantially instantaneous mixing of the cold solvent and waxy oil.

The derrick is approximately 0°~50°l" (-18°~10°
℃). These conditions of cold solvent injection and high agitation allow most of the wax to settle out of the waxy oil. U.S. Patent No. 6.775.6 regarding the dilthill process
No. 50, X, A, which is incorporated herein by reference.

A variation of the dilthill process is U.S. Patent No. 3,775,28.
No. 8, which is also incorporated herein by reference. In the modified dilthill process,
Cooling is provided by cold solvent injection and high agitation to the temperature at which the wax is separated from the oil, i.e., above the wax separation temperature, usually about 406F (22°C), preferably about 35°L above the separation temperature: ( 19° C.), thereby precipitating at least a portion of the wax from the waxy oil. The oil-solvent-wax slurry is then withdrawn from the derrick zone and introduced into a second derrick zone where it is cooled to the wax separation temperature to further precipitate the wax portion from the waxy oil. The cooling rate within this range is 5-20″F/min (
2,8~b This modification is carried out to avoid the use of a large amount of cold solvent, and when this modification is performed at no temperature (°C), the temperature of the household oil-solvent-wax slurry is maintained at the wax separation temperature throughout the entire process. It would require a large amount of cold solvent to bring the temperature down to . Although this embodiment may incorporate any conventional cooling process, such as a double-sided derrick in the second derrick area, self-cooling, a double-sided derrick is preferred. The partially cooled oil-solvent-wax slurry is indirectly cooled to the wax separation temperature in a double-sided chiller without adding any more solvent. Remove all wax adhering to the walls of the chiller using a scraping device. The disadvantages of the double stirrer chiller in this embodiment are the same as those encountered when using the double stirrer chiller as a single cooling unit. The scraping device physically crushes the wax crystals that have formed on the chiller wall.
This reduces the wax filtration rate and increases the amount of oil encapsulated in the wax.

U.S. Pat. No. 4,140,620 for Bowlet discloses that a lubricating oil stock at a temperature above the cloud point is cooled to a temperature below the cloud point with vigorous agitation in a cooling zone, then minimally agitated and After cooling to the final temperature with incremental addition of solvent, the wax is removed by filtration. Provide rapid agitation during the initial cooling period. The cooling zone is described as being a conventional double wall heat exchanger with means for stirring the oil while cooling it by more rapid rotation of the scraper. The basestock stock is diluted with solvent during the initial stirring derrick. The bulk of the solvent is added to the system after the first wax crystals have formed, i.e. after the temperature of the diluted or undiluted oil-based feed reaches a temperature slightly below the cloud point of the waxy petroleum fraction. .

From the diagram in the patent, the cooling zone consists of a double-walled chiller, the waxy oil feedstock is introduced into the inner zone, the cold filtrate is fed to the outer jacket of the chiller, and the agitation is achieved by increasing the rotational speed of the scraper. I can see that it is increasing.

It is clear that after the initial high agitation cooling, large amounts of solvent are added before or during the final cooling step with low or no agitation.

DESCRIPTION OF THE INVENTION High-speed agitated indirect cooling, optionally combined with multi-point solvent injection, can be used as a single dewaxing process or with dilthill dewaxing in place of a double-pump derrick to effectively dewax from waxy oils. I found out that it can be removed.

In the method of the invention, the wax-containing oil, prediluted or not, preferably not prediluted, is heated to ensure complete dissolution of the wax in the oil.

The waxy oil then enters a zone of high speed agitation and indirect heat exchange where it is heated to avoid rapid temperature drops above 40°F (22°C) and to provide the necessary dilution at the wax separation temperature. 1 to 20"l" in a single step (using either single or multiple high agitation in a direct chilling unit) with simultaneous addition of dewaxing solvent from multiple points if necessary
7 minutes (α6~b). The final oil-solvent ratio is in the range of 1 = 2 to 1:5 depending on the raw material oil. Since the derrick is performed using an indirect heat exchanger, the solvent does not need to be at a cold temperature, but A novel feature of this embodiment of the invention is that high agitation is used throughout to reach the wax separation temperature. The precipitated wax is separated from the wax oil-solvent slurry by liquid-solid separation means.

Alternatively, by replacing the oyster chiller described herein with the present high speed agitator indirect heat exchanger, US Pat.
．． 775.288 can be modified. In this embodiment, the partially cooled and partially dewaxed oil from the dilthill column is heated above the wax separation temperature and below the separation temperature, either with or without the addition of additional solvent. Derrick to a high speed stirrer indirect heat exchanger at a temperature still below about 50°F (28°C) to the final wax separation temperature. The derrick to wax separation temperature in an agitated chiller is 1-20"F/min (0
, 6-b High speed agitation helps ensure uniform crystal growth and induces high slurry velocity at the heat exchanger surface. The high agitation prevents wax from adhering to the exchanger derrick surface and provides a heat transfer coefficient similar to that of a double-screw derrick. High agitation in indirect heat exchangers can be obtained in any number of ways: by high-speed rotating turbines, propellers or paddle-type vanes; vibrating or reciprocating shafts with plate collars, donuts, paddles, etc.; high-frequency sonic vibrations, etc. Can be done. A preferred method is a rotating turbine, propeller or paddle blade or one
Either a vibrating shaft fitted with one or more plates is used. There are no restrictions on the type, number, or shape of propellers, turbines, paddles, or plates used in the high-speed stirring device.

A clearly preferred high speed stirrer-heat exchanger is presented in the accompanying figure. The agitator-heat exchanger unit is an indirect double wall heat exchanger 1 with derrick fluid (cooling fluid) introduced through an inlet 2 and a passage (P) defined between an inner wall 3 and an outer wall 4 of the unit. and the material to be chilled (slurry) is introduced into the unit through the inlet 6 and passed into the central passage (CP). Additional solvent can be added through line B (controlled by Pulp B) as necessary to avoid sudden temperature drops or to achieve the desired dilution at the wax separation temperature.

High agitation is provided by a supported shaft of articulated members with a plurality of vanes radially attached to each member. A shirt (S) comprising a plurality of articulated members fitted with a plurality of vanes is placed in the central passage of the double wall heat exchanger to provide a high level of agitation to the material passing therethrough.

The blades 7 may be paddles, propeller blades or turbine blades, but are preferably propeller blades mounted on the shaft to increase agitation and flow in the direction of the slurry passing through the central passage. The articulated shaft consists of two or more rigid members (8A-82, although four members are shown in the figure, it is understood that the articulated shaft can include any number of members). ), one end of one member (PA) is connected to drive means 9 to provide axial rotation of the shaft. The other end of the shaft member 8A is supported by a fixed bearing 10 and is connected to an articulated or deformable joint or universal joint 1.
1 to a second shaft member 8B, each shaft member being connected in turn to the next shaft member (such as sY) by a similar articulation or deformable joint or universal joint 11, each shaft member also having two It is supported and retained within the central passage of the heavy wall heat exchanger by a fixed bearing located within the central passage. Preferably, the fixed bearing is at the end of the shaft opposite the articulation or deformable joint or universal joint. These fixed bearings attached to the shaft slide into the central passage and remain self-stationary within the passage without the need for welding, bolting, or any other method of tying to the inner wall of the central passage. Preferably, it is mechanized. The partitioned feature of the stirring unit allows stirring devices of any desired length to be fabricated and installed into existing double wall heat exchangers. This design, which combines a universal joint and a fixed bearing with a shaft member having propeller blades, prevents vibrations and shaft misalignment from being transmitted down the length of the shaft, and allows the shaft to contain sag or slight curvature. It becomes a unit that matches the tube.

Agitation is known as the impeller Reynolds number, NRe (Berry, Chemical Engineers Handbook, 5th ed., pp. 19-6, McGraw-Hill, New York (1999).
973)) A dimensionless number greater than 10,000 is described as high or turbulent. The impeller Reynolds number is defined by the following formula: where L is the impeller diameter, n is the rotational speed, ■ is the fluid density, and μ is the fluid viscosity (units are the group dimensionless )).

Values of NRe between 10 and 10,000 form a transition region in which the flow is turbulent in the impeller and flows in layers (1arninar) (smooth and be).

The waxy oil is diluted with a waxy solvent as described above.

This solvent can be selected from any known and readily available solvents. Typical examples of the solvent are acetone,
Aliphatic ketones with 3 to 6 carbon atoms such as methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIB'K); low molecular weight hydrocarbons such as ethane, propane, butane, and propylene, and the above-mentioned ketones and C6 such as benzene and toluene. ~C1o A mixture with aromatics. In addition, C2~
C4 chlorinated hydrocarbons, such as halogenated low molecular weight hydrocarbons such as dichloromethane, dichloroethane, and mixtures thereof can be used as solvents. Specific examples of suitable solvent mixtures are methyl ethyl ketone and methyl isobutyl ketone, methyl ethyl ketone and toluene, dichloromethane and dichloroethane, propylene and acetone.

Preferred solvents are ketones, with methyl ethyl ketone, methyl isobutyl ketone and mixtures thereof being particularly preferred.

The method of the present invention comprises seven lashings (flashin) of the solvent.
g) at sufficient pressure to prevent. Atmospheric pressure is sufficient when using ketones, ketone/aromatic mixtures, or norocarbons, but when using low molecular weight hydrocarbons such as propane, excessive pressure may be necessary to avoid autocooling effects associated with loss of diluent solvent. pressure
pressure) is required.

Any waxy hydrocarbon oil, petroleum,
Lubricating oils or other distillate fractions can be dewaxed. Typically, the boiling range of these waxy oil feedstocks is approximately s o
o,'F ~ approx. 1300'F (approximately 60°C ~ approx. 704°
C) covers a wide range of areas. Preferred oil stocks are lubricating oils and specialty oil fractions having boiling points in the range of 550'F to 12006F (288C to 649C). These fractions may originate from any source, such as paraffinic crude oils obtained from Aramco, Kuwait, Panhandle, North Louisoana, Western Canada, Tiashuana, and the like.

Hydrocarbon oil feedstocks also include coal liquefaction, synthetic fuels (5ynf
It may be obtained from any of the synthetic route processes currently practiced or contemplated in the future, such as tar sands extraction, shale oil recovery, etc.

Example 1 Western Canadian Crude 60ON oil was heated to 134°F (57°C) 5'l' (2.8°C) above its cloud point.
°C) to a diluted crystallizer.

Solvent (methyl ethyl ketone 2
5% and methyl isobutyl ketone (75%) were added incrementally to the dilutel crystallizer stage under conditions of high agitation, and the wax-solvent-oil slurry (I) leaving the crystallizer was 3.
911'' (4°C).

Slurry (I) was first scraped with a 4-inch (10 cm) inner diameter, 5-fee length rotating at 24 RPM.
Flow A) passing through a conventional oyster solidification chiller (15m)
, then a diameter 2, finch (6
High-speed agitating indirect chiller (4 inch (10 cm) inside diameter, 8 feet long (4 inch (10 cm)) equipped with a
(Flow B) (impeller Reynolds number = 33,000, slurry density 0.85 /i /c
c, slurry viscosity 2.0 centipoise).

Streams A and B are stirred in a solidification chiller or a high-speed stirring indirect chiller, respectively, to a wax separation temperature of -10'F (-23°C).
Slurry samples (TI) were collected from each chiller stream and the filtration properties were measured. The results are presented below.

Table I Raw material filtration rate (m3/m2 day), 4.76 5.61
Liquid/Solid 6.68 4.76 Dewaxed Oil Yield (%) After Washing, 67.5 74.5 High-speed stirred indirect chillers have lower liquid/solids values compared to the slurry exiting the stirred chiller. The lower oil retention in the wax cake caused by the similar Resulting in the final slurry shown.

Example 2 In order to determine the general applicability of the present invention, a number of different waxy oil feedstocks were used in a comparison of Dilthill/Scratch Chiller and Dilthill/High Speed Stir Indirect Chiller. The procedure adopted is that of Example 1. The impeller Reynolds number in this example was 50,000. The results are presented below.

Table■ 6'0ON 1500 5.28 4.58 74.3
A - 24 rpm speed is directed to the double-sided derrick;
1500 rpm is directed into the stirring derrick.

Example 3 Dill chill/Oyster-defined chiller train and Dilthill/
Heat transfer coefficient comparison data were obtained using a high-speed stirring indirect chiller train. In the dilthill/dual stirrer chiller train and the dilthill/high-speed agitation indirect chiller train, the initial diameter is 4 inches (10 cm) and the length is 5 feet (1,
A 5 m) two-wheel stirrer was operated as-is, and its internals were then replaced with high-speed stirring internals. The results are presented below.

It is clear that the significant advantage of a high speed stirred indirect derrick over a double stirred indirect derrick is improved liquid/solids and deloxization yields.

EXAMPLE 4 Western Canadian Crude 60ON waxy oil was prediluted with 0.2 volumes of 45% MEK, 55% MIBK solvent to produce 1 5'F above cloud point.
It was fed to a -row commercial oyster defined chiller (total row length of 2700 feet (820 m)) at 376F (58C). The solvent is premixed with above cloud point feedstock before entering the oyster definition chiller. The slurry is gradually cooled as it passes through each row of scraped surface exchangers, and additional solvent (MEK4sX
, MIBKss%) is added from the point of introduction at the flow temperature to the slurry or final filtration chiller at the filtration temperature (146
F (-10°C)) containing 2.5 volumes of solvent. The inner diameter of the oyster defined chiller is 12 inches (50 cm)
)Met. The scraper was operated at 3 ORPM and the derrick was heated at 16 to 196 F/min (0.9 to 0.9 b). Supplied to chiller (train operation).60°
)' (16°C) was added to the waxy oil feed in the first chiller unit.

This mixture was passed through all three stirring hulls, each containing a propeller. Two rotational speeds were tested: 1000 and 1500 RPM.

The high-speed stirring chiller has an inner diameter of 4 inches (10 crrL), a length of 8 feet (2.4 m), and a diameter of 2. Finch (6,9
A propeller from Makoto was used. Impeller Reynolds number is 1
53.000.1500RP M at 1000RP
It was 50,000. The stirring device used in this example was of the interlocking design previously described and shown in the accompanying drawings.

The oil flow rate in the pilot stirred chiller was selected to provide the same derrick speed and residence time as the two-wheeled chiller used in the commercial unit. The stirring derrick speed is 2.
8-5.8°F/min (t6-z, 1°C/min) (residence time 40 minutes) and the derrick speed for an oyster-defined chiller is 16-! L9'F/min (0,9~b. As is clear, the stirring chiller (total 24 feet) (
The superficial cross-sectional velocity of the fluid through the 2700 ft (820 m) total was much lower than that through the oyster defined chiller (2700 ft (820 m) total) to make the residence times approximately equal.

The slurry passes through these trains at wax filtration temperature (14'F).
-1oC)). The data obtained from this comparison is presented below.

Table 1 ■ Raw material filtration rate (m'/m2 days) 4.87 6.23
5.67 Liquid/Solid 6.55 5,95 5.00 Dewaxed oil yield after washing 76.7 B Q, 6 85.0
The increase in filtration rate using the stirred chiller is 28% at 1000 rpm and 16X at 1500 rpm. Liquid/solid drop is 9% at 1000 rpm, 1500 rpm
rpm reaches 24%, and has the same moldability. This result makes cleaning use even more effective, resulting in 1100
Allows an increase in dewaxed oil yield of 6.3X at 1500 rpm to 39 min at 0 rpm.

Example 5 Western Canadian Crude 60ON oil was heated to 137'F (58C) 5"F (286C) above its cloud point.
°C) to a pilot plant dilthill crystallizer. An increasing volume of 2.6 volumes of solvent (methyl ethyl ketone 45%, methyl imbutyl ketone 55 The exiting wax-solvent-oil slurry was sq'p (s, q°C). The slurry was then dashpot cooled to a filtration temperature of 20'F (-7C) to measure filtration performance. Next, the same oil raw material was added to 157
2.7 volumes of solvent (MEK45X, MIBK 55%) at 80'F'' (27°C)
In addition to the waxy oil feedstock in the chiller unit, the slurry was cooled to the wax separation temperature at a cooling rate of 5 to 86 F/min (2.8 to 4.5 C/min). , the results are presented in Table V.

Table V Dirtill results do not have the effect of SS (old style) derricks or stirrer derricks. A sample of the slurry was taken at the outlet of the dilthill tower and dashpot cooled to filtration temperature in the laboratory. The slurry does not contain defects due to SS derricks. The stirred derrick results show that dilthill performance can be matched and the shortcomings of the SS derrick can be eliminated over a wide range of filtration temperatures.

Illustrate a converter.

1: Heat exchanger 2: Coolant inlet 3: Inner wall 4: Exterior wall 5: Coolant outlet 6: Slurry inlet A: Multiple blades 8: Shift member 9: Drive means 10: Fixed bearing 11: Universal joint i,:”;g;

Claims (1)

[Claims] 1. Introducing waxy hydrocarbon oil at a temperature higher than its cloud point into a direct derrick zone divided into a plurality of stages, and passing the waxy oil from stage to stage in the cooling zone. , a cold dewaxing solvent is introduced into at least a portion of the stage to form a solvent-waxy oil mixture, maintaining a high degree of agitation in at least a portion of the stage containing the solvent and the waxy oil, thereby the temperature at which the solvent-waxy oil mixture separates from the oil as it progresses through the direct derrick zone, i.e., above the wax separation temperature and about 50'F (28C) above the separation temperature; Substantially instantaneous mixing of the solvent and the waxy oil occurs while cooling to a moderate temperature, whereby most of the wax is precipitated from the waxy oil under conditions of high agitation. to form a wax oil-solvent slurry, which is withdrawn from the direct derrick zone and cooled in an indirect heat exchanger zone to a four-part separation temperature to further precipitate the wax portion from the slurry, forming a wax oil-solvent slurry. A process for dewaxing waxy hydrocarbon oils in which the precipitated wax is separated from a solvent slurry by solid-liquid separation means, characterized in that the indirect heat exchanger is operated in a high-level agitation mode. 2 A high level of agitation is expressed using an impeller Reynolds number of approximately 1. o o o~1.000.000
The method of claim 1 within the scope of. 6. A patent claim in which dewaxing is selected from the group consisting of C3-C6 aliphatic ketones, low molecular weight hydrocarbons, mixtures of C3-C6 aliphatic ketones and 06-C4 aromatic compounds, and C4-C6 halogenated hydrocarbons. The method according to item 1 or 2. 4. Dilute the waxy oil with a dewaxing solvent to obtain an oil-solvent ratio of 1:
Claim 1.2 or 3 in the range of 2 to 1:5
The method described in section. 5. The waxy oil is diluted with a regular solvent and the oil-solvent mixture is introduced into an indirect heat exchanger operated in a high-level agitation mode to cool the oil-solvent mixture to the wax separation temperature, resulting in A method for dewaxing hydrocarbon oils comprising separating precipitates from a wax oil solvent slurry using liquid-solid separation means. 6. The method of claim 5, wherein the high level of agitation is in the range of about 1,00 DEG to 1,000,000 DEG expressed in terms of impeller Reynolds number. Z dewaxing is carried out by selecting from the group consisting of C5-C6 aliphatic ketones, low molecular weight hydrocarbons, mixtures of C3-C6 aliphatic ketones and C6-C1o aromatic compounds, and C7-C6 halogenated hydrocarbons. The method described in item 5 or 6. & Dilute the auspicious oil with a dewaxing solvent to make an oil-solvent ratio of 1:2.
The method according to claim 5.6 or 7, wherein the ratio is in the range of 1:5 to 1:5. 9. A waxy oil is introduced into an indirect heat exchanger operated at a high level of agitation, while increasing volumes of additional solvent are added at multiple points along the length of the indirect heat exchanger to indirectly mix the oil-solvent mixture. The process consists of cooling the wax to the wax separation temperature and separating the precipitated wax from the resulting wax oil-solvent slurry using liquid-solid separation means. A method for dewaxing waxy hydrocarbon oil. 10. The method of claim 9, wherein the high level of agitation is in the range of about 1.000 to 1.000.000 expressed using an impeller Reynolds number. 1t Claims selected from the group consisting of C3-C6 aliphatic ketones, low molecular weight hydrocarbons, mixtures of C6-C6 aliphatic ketones and C6-C4 aromatic compounds, and C4-C6 halogenated hydrocarbons. The method according to item 9 or 10. 12 Dilute the waxy oil with a dewaxing solvent to obtain an oil-solvent ratio of 1:
12. A method according to claim 9.10 or 11 in which the ratio is in the range 2 to 1:5. 15. A high-level agitation device consisting of a shaft in which a plurality of members are indirectly connected, each member of the shaft being supported by a fixed bearing, and each member having a plurality of blades attached in the radial direction. 14. The device according to claim 13, wherein the plurality of blades are propeller blades.