US2768123A - Process and apparatus for treating hydrocarbon oils with immiscible reagents - Google Patents

Description

Oct. 23, 1956 R. 1.. TRUSTY ET AL 2,768,123

PROCESS AND APPARATUS FOR TREATING HYDROCARBON OILS WITH IMMISCIBLE REAGENTS Filed April 1, 1953 ROY L.TRUSTY lhventors ROY E. NYSTROM ayfi w Afforhey Unite tates 2,768,123 i- 'atented Oct. 23, 1956 PROCESS AND APPARATUS FOR TREATING gggggglON OILS WITH MMTSCIBLE RE- Roy Trusty and Roy E. Nystrom, Baton Rouge, La., assignors to EssoResearch and Engineering Company, a corporation of Delaware Application April 1, 19513, Serial No. 346,124 Claims. (Cl. 196-45 This invention relates to mixing of hydrocarbon oils or liquids with chemicals or aqueous liquids and more particularly relates to such mixing using an opposed flow mixer.

In the continuous chemical treatment of hydrocarbon oils such as petroleum distillates it is desirable to obtain intimate mixing of the chemical or aqueous and distillate streams. Following chemical treatment the distillate is mixed or washed with water to remove residual chemical. The cost of treating facilities is influenced by the pressure drop required to mix the distillate with chemicals or water through the contacting or mixing device. In addition, the capacity of existing treating units is often limited by the same pressure drop considerations.

Orifice mixers are known for mixing petroleum distillates with water to remove caustic but the amount of mixing energy is greatly in excess of that required in the present invention. Also orifice mixers are designed for one specific flow rate and when it becomes necessary to change the flow rate, the mixing energy resulting from the orifice mixer is no longer the optimum. The mixing energy of the opposed flow mixer of the present invention can be adjusted to obtain the optimum at any rate. Orifice mixers tend to plug easily, resulting in increased mixing beyond the desired range and finally in decreasing the throughput or shutting down the unit. Maintenance of orifice mixers, particularly cleaning, is time consuming and expensive. The opposed flow mixer of the present invention does not plug readily and if it does plug after long use, cleaning can be done quickly and inexpensively.

According to the present invention, mixing of hydrocarbon oils and aqueous liquids is obtained with negligible pressure loss in the distillate system by jetting or directing the flow of chemical or aqueous liquids against the flow of the hydrocarbon oil stream in a line as it passes from one drum to another in the process. More particularly the chemical or aqueous liquid is introduced through concentric pipes and the intensity of mixing can be varied as desired by changing the flow of chemical or aqueous liquid through the concentric pipes or lines.

In the drawing:

Fig. 1 represents a diagrammatic showing in side elevation of one form of apparatus having vertical pipes between certain tanks;

Fig. 2 represents a diagrammatic showing in plan of a similar apparatus having horizontal pipes between certain tanks; and,

Fig. 3 represents a vertical cross section of a detail showing the mixing means including concentric pipes or lines for introducing the chemical or aqueous liquid. I

The invention will now be specifically described in connection with caustic treating of kerosene and then Water Washing to remove as much caustic as possible, but the invention is not to be restricted thereto as it may be used for treating or purifying other hydrocarbon oil fractions such as naphtha, heating oil or the like with treating solutions or washing liquids. The present invention may be used for removing doctor solution (caustic solution of lead oxide) and lead sulfide from doctor treated naphthas and kerosenes. It may also be used for removing hypochlorite from treated naphthas.

Referring now to Fig. 1 of the drawing, the reference character 10 designates a line for conducting a petroleum distillate such as kerosene to a mixing means 12 such as an orifice mixer. Prior to going to the mixer 12, caustic solution or other treating liquid is introduced into line 10 through line 14. Mixing of the distillate and caustic is carried out in the mixer 12.

From mixer 12 the mixture then passes through line 16 into a settling drum 18 to allow separation of as much of the caustic solution as possible. More than one settling drum 18 may be used, if desired. A bottom drain 22 is provided for removing the settled caustic. The treated distillate containing emulsified water and some caustic is withdrawn from the top of the drum 3% through horizontally extending line 24 which is connected with a vertical U-bend 26 made up of a vertically extending line 23, a-horizontally extending bottom line 30 and a second vertically extending line 32. Means 34 are included for jetting or introducing water into the bottom portion of vertically extending line 28 against the flow of distillate which as shown in the drawing flows from line 28, through line 3% and then through line 32. The mixing means 34 is shown in detail in Fig. 3 and will presently be described in greater detail.

The mixture flows from vertical line 32 through horizontally extending line 36 into a second settling drum 38 for separating water and washed-out caustic which is removed as a bottom stream through line 40. More than one settling drum 38 may be used, if desired. The purified distillate is withdrawn overhead through line 42 to a final separating zone such as a filter or the like for removing substantially all the remaining water in the distillate. Such filtering is well known in the art and is not shown in the drawing and need not be further described here. Horizontal line 24 is provided with a pressure gage or the like 44 and horizontal line 36 on the other side of U-bend 26 also has a pressure gage or the like 46. The pressure gages are used to measure the pressure drop across the mixing step carried out with an opposed flow mixer as above described.

In Fig. 3 is shown a detailed view of the mixing means 34. The section of pipe 23 is shown as having a closed bottom end 48 which may be a flanged head through which extend the unobstructed concentric tubes or sec-- tions of pipe 50 and 52. The diameter of pipe 50 is of course sufiiciently smaller than that of pipe 52 to provide an annular space therebetween, as shown, to permit flow of fluid out of pipe 52. For repair or cleaning flanged head 48 may be removed and concentric lines 50 and 52 removed quickly. Reassembly is also easy. The upper ends of the pipes 50 and 52 are open and terminate at the same level at 54. The ends at 54 are above the top of the point at which the continuation pipe section 30 joins the pipe section 23, the pipe section 30 constituting the bottom of U-bend 26. The inner smaller pipe 5d extends below outer pipe 52 and has an inlet line 56 for water or other treating or purifying liquid. Line 56 is provided with valve 5'8.

' The outer larger pipe 5'2 has a lower horizontal extension 66 with a valve 62 to provide an inlet for water or other treating or purifying liquid. Outer larger pipe 52 is concentric with and of smaller diameter than pipe 28 to provide an annular space 63 for the downward flow of the mixture resulting by injecting water from lines 50 and 52 into the distillate flowing down in pipe 28. As shown by arrow 64, the flow of distillate in vertical pipe 28 is down while the flow of liquid from concentric pipes 50 and 52 is up or in opposed flow to the flow of the distillate. Control of the degree of mixing is obtained by varying the flow of water or other treating liquid through either of the two concentric lines or pipes 50 and 52.

In this arrangement and jetting water through pipes 50 and 52 against the flow of the distillate in ver tical line 28 there is obtained exceedingly good mixing with little or no pressure drop or loss in the distillate system as indicated by pressure gages 40 and 46. While it is not known exactly what happens at the region of contact of the immiscible liquids, it is known that exceeding good mixing is obtained and it is believed that liquid from smaller line 50 of the opposed flow mixer moves more or less in a straight line outward from the mixer and that liquid from the larger concentric line 52 flares out and down toward the inner wall of line 28 in a manner to contact all the distillate stream passing down through line 28. The fiow pattern formed by the concentric lines 50 and 52 is largely responsible for the good mixing or intimate contacting obtained and may be said to resemble an inverted umbrella. However, the invention is not to be restricted to this theory of operation.

To obtain a further improvement another mixing means of the same construction as mixing means 34 may be added as shown at 66 to inject water or other liquid into the horizontal line 24 in a direction opposite to the flow of distillate therethrough.

Referring now to Fig. 2 there is shown a system similar to Fig. 1 wherein the same reference characters are used to designate the same parts with the exception of the U-bend 68 which in Fig. 2 is shown as arranged substantially in a horizontal plane. In Fig. 1 the U-bend 26 is arranged in a substantially vertical plane. U-bend 68 has a horizontal line 72 communicating at a right angle with horizontal line 74 and line 72 communicates with another horizontal line 76 which is substantially parallel to line 72. Mixing means 34 injects water or other treating liquid into line 72 against the flow of distillate in line 72. If desired, a second mixing means 66 may be installed for injecting treating liquid into horizontal line 24 as above described in connection with Fig. 1.

The invention will now be described in connection with the treating of kerosene to remove caustic therefrom. The mixing energy (foot pounds per pound of kerosene) has been determined by tests for the maximum percent caustic reduction and for maximum percent water reduction with diiferent amounts of wash water on distillate feed. The amounts of wash water used may be varied between about 5 and 20% by volume on the distillate feed being treated. For larger units wash water amounts greater than 20% by volume of distillate may be used. The amounts of wash water used were 5, and by volume on the distillate feed being treated. For the particular design which will be presently described in greater detail it was discovered that improved mixing and separation of the caustic and water were obtained when about 10% by volume of wash water on the distillate feed was used and when about 40 to 80%, preferably 55%, of the total water used as the treating liquid introduced through mixing means 34 was introduced through outer line 52 as an annular stream and the rest of the treating liquid water was introduced through inner line 50 as a single stream. The pressure drop or loss through the distillate system as indicated by pressure gages 44 and 46 was negligible. If all the wash water is passed through outer line 52 and none through inner line 50, fair reduction of caustic and poor removal of water is efiected. The same is true if all the water is passed through inner line 50 and none through outer line 52.

In a unit for treating kerosene where the feed rate of kerosene is 20,900 barrels per day and the feed rate of caustic solution is 204 barrels per day of 1 Baum caustic, the kerosene and caustic are mixed in an orifice mixer 12 comprising a vertical vessel of about 20 feet long, 10 inches in diameter and provided with 6 orifice plates spaced 24 inches apart by spacers which are 10 inches in diameter. Each plate is provided with an orifice of 4% inches in diameter. Line 10 leading to mixer 12 is 8 inches in diameter and flares out 10 inches where it connects to mixer 12. The treated kerosene leaving settling drum 18 through line 24 has a caustic content of about 20 parts per million and a water content of 0.4 wt. percent. The treated kerosene leaving drum 38 has a caustic content of 3.8 parts per million which is a reduction of 82%. The treated kerosene leaving drum 38 has a water content of about 0.1% by weight which is a reduction of 70%.

The total amount of wash water introduced through mixing device 34 through lines 56 and 60 was 2170 barrels per day and about 55% of the total water was passed through outer pipe 52. The amount of water passing through concentric pipes 50 and 52 is regulated by valves 58 and 62. The water introduced through line 56 was under a pressure of about 21 p. s. i. g. and the water introduced into line 60 was under a pressure of about 19 p. s. i. g. The treated kerosene passing through line 36 was well mixed and it separated into two phases readily in settling drum 38. The treated kerosene leaving drum 38 through line 42 has a caustic content of 3.8 parts per million and a water content of 0.13 wt. percent. When this treated kerosene from line 42 was filtered to remove the remaining entrained water a water white kerosene substantially free of caustic and water was obtained.

The pressure at pressure gages 46 and 44 read 11.5 and 10.0 p. s. i. g., respectively, which shows that the pressure drop or loss is negligible.

In the above treating unit the line 28 has a diameter of 8 inches, outer pipe 52 has a diameter of 3 inches and inner pipe 50 has a diameter of 1 inch. Line 28 should be at least 10 feet long to realize the full beneficial effects of the opposed flow mixer and in the present unit was 20 feet long. If a second opposed flow mixer is used at 66, line 24 should be at least 10 feet long also. The upper end 54 of pipes 50 and 52 extends 16 inches above the center line of horizontal pipe 30.

For larger treating units the concentric pipes 50 and 52 are made of larger diameters.

By adding a second mixing means 66 like mixing means 34 in series with it and arranging it as shown in Fig. 1 to be jetted against the flow of liquid distillate in line 24 it is possible to obtain further caustic removal with little or no increase in pressure loss in the distillate system.

In the above specific example with the unit described the distillate feed rate may be increased to about 24,000 barrels per day with the same good results. At this greater feed it is desirable to increase the percentage of water passing through outer pipe or line 52 above that given in the specific example.

In the apparatus shown in the drawing the opposed flow mixer of this invention, such as shown in Fig. 3, may be used instead of orifice mixer 12, being arranged in a manner similar to that shown in Figs. 1 and 2 so that the caustic solution is passed through concentric lines 50 and 52 against the flow of distillate. In this case another opposed fiow mixer 34 will be used for the introduction of the wash water. The opposed flow mixer of this invention may also be used instead of an orifice mixer to mix naphtha with a hypochlorite sweetening solution and in this case another opposed flow mixer such as shown at 34 and Fig. 3 is used to remove hypochlorite solution from the treated naptha. The opposed flow mixer of this invention may also be used to mix two miscible liquids such as heating oil and diesel oil or the addition of tetra ethyl lead fluid, inhibitor solution, or dye solution to hydrocarbon streams.

While specific details have been given as to one unit it is to be understood that these are by way of illustration only and changes and modifications may be made without departing from the spirit of the invention.

What is claimed is:

1. In a process for contacting a hydrocarbon liquid with another liquid immiscible therewith, a first of said liquids being transferred from one zone to another zone as a confined stream, the improvement for obtaining intimate contact between said two liquids which comprises injecting the second of said liquids as a plurality of separate concentric confined streams into said confined stream of said first liquid against the flow of said first liquid in an unobstructed space with negligible pressure drop in the stream of said first liquid, all of said streams of said second liquid bein concentric with said stream of said first liquid, and then flowing the resultant mixture in the direction of flow of said first liquid past the region of injection of said second liquid.

2. In a process for removing chemical treating agents from a hydrocarbon oil that is being transferred as a confined flowing stream from a treating zone to a settling zone, the improvement which comprises injecting Water as a plurality of separate confined concentric streams into the said confined stream of hydrocarbon oil against the flow of the hydrocarbon oil in an unobstructed space with negligible pressure drop in the flowing stream of hydrocarbon oil, all of said streams of water being concentric with said hydrocarbon oil stream, and then flowing the resulting mixture of hydrocarbon oil and water into said settling zone.

3. A process as defined by claim 2 wherein the direction of fiow of the mixture of hydrocarbon oil and water is changed 90 after injection of the confined streams of water.

4. A process as defined by claim 2 wherein said hydrocarbon oil comprises a petroleum distillate that has been treated with caustic in said treating zone, wherein the amount of water that is injected into the confined stream of said distillate is about by volume of the distillate, and wherein about 55% of the water that is injected passes through the outermost of the concentric streams of water.

5. A process for treating a hydrocarbon liquid which comprises mixing the said hydrocarbon liquid with an aqueous treating liquid, passing the mixture into a first settling zone to separate treating liquid and impurities, removing the so-treated hydrocarbon liquid from said settling zone as a confined stream, injecting water as a plurality of separate confined concentric streams into the said confined stream of hydrocarbon liquid against the flow of the hydrocarbon liquid in an unobstructed space with negligible pressure drop in the flowing stream of hydrocarbon liquid, all of said streams of water being concentric with said hydrocarbon liquid stream, continuing the flow of the resulting mixture of water and hydrocarbon liquid into a second settling zone to separate water from the hydrocarbon liquid, and removing treated hydrocarbon liquid from said second settling zone.

6. An apparatus of the character described which includes a first unobstructed section of pipe for conducting liquids therethrough, a plurality of concentric pipe sections of smaller diameter the .1 said first pipe section having unobstructed portions extending a short distance into and concentric with said first pipe section, and separate valve means attached to each of said smaller pipe sections for controlling the amounts of fluids introduced through said smaller pipe sections into said first pipe section, the relative diameters of all of said pipe sections being such as to provide annular spaces between each pipe section and e ch next smaller section whereby fluid may be introduced into said first pipe section through each of said other pipe sections in a direction opposite to that of fluid flow in said first pipe section and fluid flow may continue in the first pipe section through the largest of said annular spaces.

7. An apparatus as defined by claim 6 including closure means at one end of said first pipe section and a continuation pipe section joining said first pipe section at right angles thereto adjacent said end, said smaller diameter pipe sections entering said first pipe section through said closure means and terminating in said first pipe section beyond the point of junction with said continuation pipe section.

8. An apparatus of the character described which includes a first settling drum and a second settling drum, conduit means for conducting treated liquid from the top of said first drum to said second drum, said conduit means including a tubular U-bend, and mixing means for introducing liquid into one leg of said U-bend, said mixing means comprising a plurality of concentric unobstructed pipe sections extending a short distance into said U-bend leg and concentric therewith and separate valve means attached to each of said pipe sections for controlling the amounts of liquid passing through said pipe sections, the relative diameters of said U-bend leg and of each of said pipe sections being such as to provide annular spaces between each of said pipe sections and between the largest of said pipe sections and said U-bend leg whereby liquid may be introduced into said U-bend leg through each of said pipe sections in a direction opposite to that of liquid flow in said U-bend leg and fluid flow may continue in the U-bend leg through the largest annular space.

9. An apparatus according to claim 8 wherein said U-oend is arranged in a vertical plane.

10. An apparatus according to claim 8 wherein said U-bend is arranged in a horizontal plane.

References Cited in the file of this patent UNITED STATES PATENTS 1,305,870 Blyth et al. June 3, 1919 1,319,274 Foster Oct. 21, 1919 1,639,988 Dickey et al Aug. 23, 1927 2,082,034 Smith June 1, 1937 2,132,151 Fenske et a1. Oct. 4, 1938 2,215,359 Livingston et a1. Sept. 17, 1940 2,228,434 Belden Jan. 14, 1941

Claims (2)

1. IN A PROCESS FOR CONTACTING A HYDROCARBON LIQUID WITH ANOTHER LIQUID IMMISCIBLE THEREWITH, A FIRST OF SAID LIQUID BEING TRANSFERRED FROM ONE ZONE TO ANOTHER ZONE AS A CONFINED STREAM, THE IMPROVEMENT FOR OBTAINING INTIMATE CONTACT BETWEEN SAID TWO LIQUIDS WHICH COMPRISES INJECTING THE SECOND OF SAID LIQUIDS AS A PLURALITY OF SEPARATE CONCENTRIC CONFINED STREAMS INTO SAID CONFINED STREAM OF SAID FIRST LIQUID AGAINST THE FLOW OF SAID FIRST LIQUID IN AN UNOBSTRUCTED SPACE WITH NEGLEGIBLE PRESSURE DROP IN THE STREAM OF SAID FIRST LIQUID, ALL OF SAID STREAMS OF SAID SECOND LIQUID BEING CONCENTRIC WITH SAID STREAM OF SAID FIRST LIQUID, AND THEN FLOWING THE RESULTANT MIXTURE IN THE DIRECTION OF FLOW OF SAID FIRST LIQUID PAST THE REGION OF INJECTION OF SAID SECOND LIQUID.

6. AN APPARTUS OF THE CHARACTER DESCRIBED WITH INCLUDES A FIRST UNOBSTRUCTED SECTION OF PIPE FOR CONDUCTING LIQUIDS THERETHROUGH, A PLURALITY OF CONCENTRIC PIPE SECTIONS OF SMALLER DIAMETER THAN SAID FIRST PIPE SECTION HAVING UNOBSTRUCTED PORTIONS EXTENDING A SHORT DISTANCLE INTO AND CONCENTRIC WITH SAID FIRST PIPE SECTION, AND SEPARATE VALVE MEANS ATTACHED TO EACH OF SAID SMALLER PIPE SECTIONS FOR CONTROLLING THE AMOUNTS OF FLUIDS INTRODUCED THROUGH SAID SMALLER PIPE SECTIONS INTO SAID FIRST PIPE SECTION, THE RELATIVE DIAMETERS OF ALL OF SAID PIPE SECTIONS BEING SUCH AS TO PROVIDE ANNULAR SPACE BETWEEN EACH PIPE SECTION AND EACH NEXT SMALLER SECTION WHEREBY FLUID MAY BE INTRODUCED INTO SAID FIRST PIPE SECTION THROUGH EACH OF SAID OTHER PIPE SECTIONS IN A DIRECTION OPPOSITE TO THAT OF FLUID FLOW IN SAID FIRST PIPE SECTION AND FLUID FLOW MAY CONTINUE IN THE FIRST PIPE SECTION THROUGH THE LARGEST OF SAID ANNULAR SPACES.

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