JPS58214302A - Separation of multi-component liquid - 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 relates to a method for separating multicomponent liquids, particularly occipital crude oil, into a plurality of 7-lactones. In more detail,
The present invention relates to the separation of tailstock crude oil for the purpose of maximizing the production of useful distillate fractions and minimizing the production of worthless residual fractions.

In a typical refining operation, the crude oil is first topped to remove gasoline and, if necessary, other low boiling straight run materials. The overlying residue that remains as a bottom product is called occipital crude oil. Typically, topping of crude oil is carried out in a multi-stage fractionation column, producing a top product and multiple side extraction products. In this type of column,
The crude oil is flashed in the bottom flash zone of the column,
This flash vapor is then fractionated at the top of the column. The main feedstock for catalytic cranking is obtained from the occipital crude oil forming the bottoms product from this type of fractionation column.

The most common method for separating this catalytic cranking feed from tailstock crude oil is vacuum flashing.

Vacuum flashing is a process in which the crude oil is heated to cause partial vaporization of the crude oil, and the resulting mixture of vapor and residual liquid is then passed through a flash column operated at extremely low absolute pressures to separate the vapor from the liquid. be. The separated vapors are condensed to obtain one or more so-called flash distillates. This liquid leaves the Frudge 1 column as a bottom fraction and forms a short residue (sh
ort residue).

Steam is injected into the flash column at a level above the flash zone to strip the bottom fraction and transfer any non-residual hydrocarbons still present in the liquid stream to the gas phase. By stripping the bottom product, its flash point can be reached high enough to make it useful as, for example, petroleum asphalt.

Typically, reduced pressure in a flash tower is obtained by a steam jet connected to the top of the flash tower.

Because of the significant demand for lighter hydrocarbons, it is often highly desirable to increase the amount of distillate fraction produced in a flash column from a given crude oil feed. This requires flushing out more of the heavier distillate fraction in the feed, resulting in less bottoms product. The extent to which more of the heavier distillate fraction can be flashed depends in particular on the degree of vacuum applied to the flash zone of the flash column. The degree of pressure reduction obtained in J5 in the 7-Last Column zone of the flash column depends on the steam injection device used and the internal pressure drop in the flash column.

The object of the present invention is to improve the known separation method of multicomponent liquids in order to increase the production of distillate fractions from a given feed while consuming less energy compared to known methods. The method of separating multicomponent liquids according to the present invention is to heat a multicomponent liquid to form a mixture of a liquid phase and a gas phase at °C, and to pass this mixture through the lower part of a first column. A subatmospheric pressure is maintained in the first column to separate the components of the mixture into at least one distillate fraction and a bottoms fraction, the fractions are recovered from the first column and the bottoms fraction is separated into a bottoms fraction. The pressure in the second column is kept higher than the pressure in the first column while passing through the second column, and the bottom fraction is contacted with steam in the second column to form at least one heavy distillate fraction and a residual fraction. The method is characterized in that a reduced pressure of J31J is maintained in the first column by a steam injection device, and the driving steam of the steam injection device is used to contact the bottom fraction in the second column.

In the above method according to the invention, the residue of the first column or flash column is stripped with steam in a separate column. Since no water vapor is injected into the first column, the pressure in this first column is
Pressures can be maintained at lower levels compared to those associated with single column flash and steam stripping equipment. Lower pressures result in increased distillate yield. By using the driving steam of the steam injector of the Flood column for stripping the bottom fraction in the second column, the total amount of steam required can be kept relatively low and the cost of this process can be reduced.

The invention will now be described by way of specific examples with reference to the accompanying drawings.

The head crude introduced via path 1 is passed through a plurality of preheaters 2 ilj and a heating furnace 3, where the material is partially vaporized and heated to a transfer humidity of, for example, 425°C. Preferably, this transfer temperature is the highest temperature at which the residue will be heated without any significant racking, ie the initial cracking temperature. Depending on the composition of the head crude, this temperature generally ranges from 400 to 440°C.

The heated and partially vaporized crosshead crude oil is then fed via transfer path 4 to a first column 5, hereinafter referred to as the flash column. The pressure passing into the flash column 5 is maintained at a reduced pressure level by a steam injection device 6 connected to the flash column 5 via a line 7. A suitable pressure in the flash zone of flash column 5 may be of the order of about 20 mm HQ absolute. After reaching the flash column 5, the heated and partially vaporized crosshead crude oil is forced to flow through a vane type introduction device comprising a plurality of downwardly sloping vanes 8, which separate the liquid and vapor. and bring about the minute III. The separated liquid descends to the bottom 9 and is withdrawn from the flash column 5 by means of a pump 10 via a discharge path 11. The separated vapor flows upwardly into the upper part of the flash column, in which a demister mat 12 and a plurality of atomizing sections 13 are arranged one above the other.

Each spray section 13 has a plurality of liquid nozzles 1
4 and an extraction tray 15, optionally with a layer of filler material 16 placed between the spray nozzle 14 and the additional extraction tray 15 to enhance the contact between the liquid and the rising vapor. . The extractors 1 to 15 are each provided with an opening for the passage of the ascending vapor and a lower part for collecting the descending liquid. Is the extraction tray, for example, a grid tray or a bubble bell tray? It can be formed by The rising vapor, after being separated from the liquid as it flows along the vanes 8, first receives a spray of liquid from a nozzle 14 which flows into the lowermost spray section 13. Upon contact with the liquid spray, any remaining liquid in the rising vapor is removed therefrom and entrained by the liquid spray.

The lowermost atomizing section 13 (the nozzles 14 are fed with liquid from the extraction tray in the adjacent upper atomizing section). Liquid from the upper spray section adjacent here is passed through an accumulator 16 and partially circulated via a pump 17 and a return path 18 to the lowermost spray nozzle 14. Bottom spray section 13
When passing through the demister mat 12 placed above the
Any entrained liquid is separated from the vapor, so that a vapor containing almost no liquid flows into the upper region of the flash column 5.

The vapor passing upwardly through the flash column 5 gradually comes into contact with a relatively cold liquid and is condensed to a plurality of boiling point fractions.

The liquid is then discharged from the top of the Fludge-J, 3255 at several levels, passed through a cooler 19 for cooling, and then reintroduced into the flash column 5 through the nozzle 14. The upward flow of vapor contacts a relatively cold liquid, which is cooled and partially condenses.

Upward steam flow and atomizing nozzle 14 of the atomizing section 13
The required heat transfer between the droplets introduced via C is approximately 1
was found to occur within a distance of m. This means that a spray section height of approximately 1 m is sufficient for the desired heat transfer between vapor and liquid. Until now, 1
It is normal practice to use atomization sections much higher than 111. Reducing the height of the atomization section has the advantage that more atomization sections can be installed at a given tower height, and thus a greater variety of side extraction product streams can be obtained. .

The illustrated flash column 5 is provided with four product side recovery paths 20. The higher the side recovery path 20 is placed in the flash column 5, the lower the boiling point in the recovered product. If there is residual steam, it is sent to the flash tower 5 via the path 7 by the action of the steam jet device 6.
Collect from the top of the vine. The motive steam from the steam injection device 6, together with the steam (if present) from the flash column 5, is fed directly via line 21 into a second column 22, hereinafter referred to as the stripping column. The reduced pressure is maintained higher than the pressure in the flash column 5.

In stripping column 22, driving steam is used to strip the bottom fraction from the flash column fed into stripping column 22 via line 11. Before introducing the bottom fraction into the stripping column 22, the bottom fraction is passed through the furnace 23.
The temperature of the residue is brought to or near its initial boiling point by the pressure in the stripping column 22.

The upwardly flowing bottom fraction introduced into the upper region of the stripping column 22 contacts and covers the upwardly flowing water vapor introduced into the lower region of the stripping column 22. In order to ensure close contact between the water vapor and the bottom fraction, the stripping column 22 is provided with a plurality of contact trays 24, which redistribute the water vapor over the entire cross-section of the stripping column. The contact tray can be formed, for example, by a grid tray, a sieve tray or a bubble bell tray.

In order to control the temperature at the bottom of the column, the stripping column 22 is equipped with a quenching device 25 equipped with heat exchange means to cool a portion of the residual fraction and to cool this cooling liquid. Collection level J: It is suitable to reintroduce into the lower part of #-1 at a higher level.

At the top of the stripping column 22, a spray section 26 is provided for reintroducing the recovered cooling liquid into the stripping column 22 and liquefying the vapor at the top of the column.
Steam is prevented from being entrained by the water vapor exiting the top of the stripping column 22 via path 27.

Furthermore, the illustrated stripping column 22 is provided with two product recovery channels 28 and 29 for collecting and covering a residual fraction and a heavy distillate fraction, respectively.

The water vapor flowing out from the top of the stripping column 22 is introduced into a plurality of condensers 30 (only one of which is shown), and the water vapor is condensed at approximately atmospheric pressure.

The heat obtained from the products recovered from flash column 5 and stripping column 22 can be used to preheat the tail crude that is introduced into flash column 5.

Since the steam from the steam injector 6 has a pressure peak substantially higher than the pressure at the flash tower 5, the pressure passing into the stripping column 22 will also be substantially higher than the pressure in the flash column. Dew.

the maximum possible amount of the more valuable heavy distillate fraction;
In order to maintain the minimum possible amount of the less valuable residual fraction, the pressure in the stripping column 22 must be kept at a low vacuum. The minimum pressure in the stripping column 22 is determined by the minimum condensation pressure of the steam exiting the stripping column 22.

In the illustrated flash tower, a so-called dry fractionation system,
That is, by using a system without steam injection, the pressure entering the flash column can be reduced considerably compared to a wet fractionation system in which steam is introduced into the flash column. Generally, lower pressure means more valuable product for production and less bottom product.

The present invention is not limited to obtaining an initial separation between the liquid and vapor entering the flash column 5 by flowing the trailing crude oil along a plurality of vanes 8. Alternatively, e.g. The crude oil can also be passed through a centrifugal separator installed in the flash tower 5.Furthermore,
The invention is not limited to the particular spray sections, filler materials and demister mats shown. For example, fillers and demister pine] are also suitable to be replaced by rough spray sections. The number of spray sections is
The choice is made in relation to the number of by-products produced in the processed crude oil having a given composition.

[Brief explanation of the drawing]

The drawing is an illustration of an apparatus suitable for carrying out the method according to the invention. 2... Heater, 3... Heating furnace, 5... Flash tower, 6... Blowout device, 8... Vane, 9... Bottom, 10... Pump, 12... Demister mat, 13.
... Spray section, 14... Spray nozzle, 15...
・Extraction tray, 16... Aki 1 mulator, 17...
Pump, 19... Cooler, 22... Stripping tower, 23... Furnace, 24... Contact tray, 25...
Rapid cooling, 26... spray section, 30... condenser. Procedure person If j-F book Showa 5. July 7th Patent Office Commissioner Kazuo Wakasugi1, Indication of case: Patent Application No. 93306 of 19822, Title of invention: Method for separating multi-component liquids 3, Relationship with the case of the person making the amendment Patent Applicant Name Shell International Research
Mar 1-Suhatsupai B.V 1-4, Agent 1-1-14 Shinjuku, Shinjuku-ku, Tokyo
No. Yamada Building 5, date of amendment order E 1 Voluntary 6, number of inventions to be increased and overturned by amendment (no change in content)

Claims (1)

[Scope of Claims] (1) heating a multicomponent liquid to produce a mixture of liquid and gas phases, and passing this mixture through the bottom of a first column while maintaining a reduced pressure within the first column; separating the components of the mixture to produce at least one distillate fraction and a bottoms fraction; collecting these fractions from the column; and passing the bottoms fraction through a second column while reducing the pressure in the second column to the first column. The pressure in the column J is also maintained high, the bottom fraction is contacted with steam in the second column to produce at least one heavy distillate fraction and a residual fraction, and the C in the first column is maintained high.
1. A process for the separation of multicomponent liquids, characterized in that a subatmospheric pressure is maintained by a steam injection device, and the driving steam of this steam injection device is used in a second column to contact the -C bottom fraction. (2) Passing the steam from the steam injection device through the lower region of the second column and passing the bottom fraction through the upper region of the second column to create countercurrent flow between the steam and the bottom fraction. The method described in. (3) The method according to claim 1 or 2, wherein the pressure passing into the second column is maintained at a level below atmospheric pressure J,. 4. A method according to any one of claims 1 to 3, in which a portion of the residual fraction from the second column is reintroduced into the column after cooling at a level higher than the recovery level. (5) A plurality of spray sections are arranged above and below each other in the upper part of the first column, and each spray section is arranged at the oldest 1m.
The method according to any one of claims 1 to 4, having a height of . (6) The method according to any one of claims 1 to 5, wherein the bottom fraction is heated before passing through the second column. (7) The bottom fraction is passed through the second column. (8) After introducing the cold NJ liquid into the second column to separate the product vapor from the water vapor, A method according to any one of claims 1 to 7, wherein water vapor is recovered from the second column.