US2270412A - Process of dehydrating oils - Google Patents

Description

Jan. 20, 1942. s. E. CAMPBELL PROCESS OF DEHYDRATING OILS Filed Nov. s.' 1939 vm W n w+, m, mm. PSSOk 5mm.

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Patented Jan. 2.o, 1942 UNITED STATES PATENT OFFICE PROCESS 0F DEHYDRATING OILS Sumner E. Campbell, VLong Beach, Calif.

Application November 3, 1939, Serial No. 302,691

z claims.

This invention relates to a process for removing water from oils, and has for its principal object the removal of water in emulsifed petroleum oils.

Another object is to continuously treat oils, whether petroleum oils, tar oils, shale oils, or other oily materials, which tenaciously hold water so that aI difticultly breakable emulsion results, in a simple fashion without the use of electricity, expensive chemicals, or the like.

While the invention will be exemplified more particularly herein with reference to emulsied petroleum oils, especially as such produced from oil wells, it will be understood that the invention is not limited to this particular class of oily materials.

Crude petroleum oils coming from wells may contain 50% Water, more or less, which is mixed in the oil in macroscopic and microscopic globules. In order to make such oils of pipe line quality, the water or B. S. & W. must be reduced to 3% or less, depending on the requirements of the purchaser or refinery.

Settling by standing will, in time, permit the bulk of the large globules of water to stratify for removal, but this is impractical as it calls for immense and costly storage tanks or sumps. The small microscopic particles of water suspended in the oil do not respond to settling and remain indefinitely suspended in the oil in the form of an emulsion which is generally resistant to any but a specialized form of treatment to remove the water, and in most cases the water in such emulsions is far inexcess of the pipe line requirements of a maximum of 3% B. S. & W.

Further, it is highly desirable to substantially eliminate all water in the oil, because even 2% water in an oil is a great detriment to its treatment in the refinery, or even for burning. One reason for this is that practically all water in petroleum oils is of a saline nature. i. e., it contains in solution various corrosive salts which naturally accumulate in and on pipes, stills, etc., often causing extensive 'and expensive damage.

Such salts include sodium chloride, calcium chloride, magnesium chloride and others, magnesium chloride usually being largely responsible for the corrosion of equipment, sodium chloride being the most predominant in the oils from certain fields.

It is an object of this invention to remove both free and emulsied water from petroleum oils to leave a water content of not more than 0.5%, preferably of about 0.2%, by a single pass of the oil through the apparatus to be described.

Referring to the single sheet of drawings, which represents a diagrammatic flow sheet, partly sectionized, it will be seen that the Wet or emulsied petroleum oil in pipe I0 is passed by pump II through a heater I2, wherein its temperature is raised preferably to about 200 F. to 212 F. and thence into the lower portion of a contact tower I. Y

Tower I is substantially lled with a packing material I3, such as finely divided quartz, glass,y or other material which is so graded in particle size as to prevent the nest grade of packing from shifting. This is accomplished, for example, by using a layer of particles of about 1A, to E/ mesh on the bottom of the tower, completely covering a perforated plate or dome which protects the inlet lines. On this layer is placed a layer of slightly iiner material to the end that the bulk of the packing, which will preferably be about Ils to 15" mesh, will not materially penetrate the coarser layers supporting it. At the top of the tower this bed of fine packing is held by reversing the particle sizes used at the bottom so that the perforated cone is lled with the coarsest grade of packing employed to permit free egress of the oil and water from the packed zone. In order to avoid additional emulsiiication it is highly important that the area of the perforations in the fbumped" or hemispherical ,dome supporting the packing at the bottom of the tower be at least equal to the area of the voids in the packing. It is equally important that the area of the perforations in the cone at the top of the tower which confines the packing material should also be at least equal to the area of the voids in the packing.

The viscosity of the oil is another factor in the selection of particle size as well as the thickness of the grades, but the selection of the contact material offers no diiculties by simple tests when the raw material to be treated is known.

The upper part of tower I may terminate in a perforated cone-shaped top I5, lined, if desii-ed, with line meshed screen, the perforations of which are small enough to retain the packing material. On flowing through the perforations in tcp I5, the velocity of the cil and separated Water is reduced by passing into a launder I6 wherein the bulk of the saline water settles. A baie I 'I is provided to prevent the passage of any large globules of water tending to pass upward with the oil and to deflect the ow of oil and water toward the wall of the zone of low velocity.

l A vent I8 is provided at the top of tower I,

and th'e oil with any contained water passes oft through line I9 to the bottom of a similarly constructed tower 2 through which it passes to a pipe 20 and then to the bottom of tower 3 (also similarly constructed to towers I and 2) and, passing upwardly therethrough.. discharges through a pipe 2I to a cooling tower 22 from for use or storage.

Initially, an open top tank 23 is provided with any suitable heating means and holds a weak, or dilute, hot solution of sodium chloride, having a salinity substantially the same as the salinity of the water in the emulsifed cil which may be of the order of a 3% saline solution more or less. A portion of this saline solution is taken by pump 25 and passed through line 24 into thebottom of packed tower I to pass upwardly therethrough concurrently with the hot emulsified oil from line I0.

Prior to the passage of any oil through line I0, it is preferred .to pump hot Saline solution at a temperature of from about 200 F. to 212 F. from tank 23 into previously heated tower I until the same is filled a desired depth with hot dilute saline solution which, for instance, may be to the lowest perforations in cone I5 or any other level which provides a substantial depth of saline solution in the interstices of the contact material.

effect of assuring coalescence of even minute which it may be drawn as substantially 4dry oil The hot emulsiedoil is then pumped into tower I and in passing up through the bed of contact material the action is such that the contact material forces the larger globules to coalesce with the body of dilute saline solution, thereby largely separating the bulk of the water from the oil.

In operation the tower thus becomes lled with oil and saline solution, the latter consisting of added saline solution from tank 23, together with coalescedsalt water from the crude. The mixture of oil and separated water then passes into launder I6 wherein the water settles to a predetermined level X-X from which it may be withdrawn by pipe 26 'to be received in tank 23, any excess passing to waste through pipe 21.

The action of tower I is one which greatly reduces the quantity of so-called free water in the oil. For instance, if the oil originally contained 15% to 20% of water, tower I will reduce this to about 4%' to 5% of water which remains largely in the form of a. tight emulsion. This step is accomplished at practically no cost for salt solution as the same may be provided at the right salinity from the oil itself.

The emulsifed water remaining in the oil reouires more drastic treatment to assure separation. Therefore, the hot emulsion is passed into the bottom of tower 2 which has previously been filled to a desired depth, as before, with a hot saline solutionV of much greater salinity than that of the water remaining in the oil.

For instance, where the salinity of the water in the oil is of the order of 3%, the salinity of the solution in tower 2 should be about 20% to concentration, initially and as maintained. Such solution is initially supplied from tank 28, heated in any desired manner to a temperature of 200 F. up to theboiling point of the 'solution, being taken thence by a pump 29 and forced through line 30 to the bottom of tower 2 to initially ll the same.

Thereafter, when the stream of oil from tower I is owing, the concentrated saline solution in the presence of the contact material has the water globules with the concentrated salt solu tion so that, when separation of the water and oil streams takes place in launder 3i, naturally there will be a drop in salinity in tower 2 unless provision is made to avoid the same. To this end, the saline solution collecting in launder 3I is withdrawn by pipe 32 to pass to tank 28 wherein the heat may be applied in any wellknown manner to maintain a desired salinity, any excess being drawn off through pipe 33.

'Ihe thus treated oil will then not have a water content of more than 0.5% but the same is generally lower.v Under certain conditions, however, it is desirable to further treat the oil not only to remove the last trace vof salt water, but also to remove certain salt particles which remain suspended in the oil apparently encased in a tough iilm of some oily material and which causes much damage to equipment in reilning or using the oil.

The practically dehydrated oil .is therefore passed through pipe, 20 into the bottom of tower 3, similarly constructed and operating as before described, which is lled with hot fresh water supplied from tank .34 'through pump 35 and pipe 36.

'I'he effect of the contact material on the salt suspended in globules of oily material is the same as before described. i. e., thevcontinued distortion by passage through the interstices of the contact material continually exposes the solid salt to the action of the fresh water so that the same is finally dissolved and the solution will collect in launder 31. y

This solution may be so dilute as to be effective for several passes by recycling through pipe 38,

otherwise -all, or a portion, may be discarded A through pipe 39 and the volume maintained from tank 34.

I claim as my invention:

1. The process of dehydrating oils which comprises: owing a continuous stream of emulsifled oil containing saline water through a mass of contact material submerged in a saline solution of about the same salinity as that of said water to effect coalescence of some of said water with said solution, removing some of said coa1escedsolution from said stream, then passing said stream while still containing some emulsion through' further contact material submerged in a saline solution of greater salinity than that of the solution remaining in the oil to eilect coalescence of said solutions, lremoving substantially all of the coalesced solutions from the oil, then passing the oil through further contact material submerged in fresh water to remove any remaining small percentages of said solutions and to effect solution of, any contained solid salts,.a .nd removing the thus contaminated fresh water from the oil.

In a process of dehydrating oil in which an emulsiiied oil containing saline. water and solid salt is first contacted with a saline solution of about the same salinity as said water and the major portion of said water and solution is removed, the oil is then contacted with further saline solution of greater salinity than said first solution and said further solution with a minor portion of said water is removed, and then the remaining water an-d solid salt is removed to leave a substantially dry salt-free oil, that step which comprises: contacting the oil with fresh water after contact with said second solution and removing thc water with its contained salt.

v SUMNER E. CAMPBELL.

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