US3714070A - Non-corrosive sulfur-liquid hydrocarbon slurry containing a corrosion inhibiting amount of a polar-containing solvent - Google Patents

Abstract

An improved non-corrosive sulfur-liquid hydrocarbon slurry composition and a method for the preparation and corrosive inhibition of such a slurry, particularly for subsequent transportation through pipelines or vehicles and conduits without causing plugging and corrosion.

Description

nite States- Patent [191 Vondrak [11] 3,714,070 1 1 d Jan. 30, 1973 [54] NON-CORROSIVE SULFUR-LIQUID HYDROCARBON SLURRY CONTAINING A CORROSION INHIBITING AMOUNT OF A POLAR- CONTAINING SOLVENT [75] Inventor: Mary Frances Vondrak, Houston,

Tex.

[73] Assignee: Shell Oil Company, New York, N.Y.

[22] Filed: Feb. 19, 1971 [21] Appl. No.: 117,151

Related U.S. Application Data [63] Continuation-impart of Ser. Nov 774,218, Oct. 30,

1968, Pat. No. 3,606,482.

[52] U.S. Cl. ..252/396, 252/309, 302/66 [51] Int. Cl. ..C09k 3/00 Primary Examiner-John D. Welsh Attorney-George G. Pritzker and Harold L. Denkler [57] ABSTRACT An improved non-corrosive sulfur-liquid hydrocarbon slurry composition and a method for the preparation and corrosive inhibition of such a slurry, particularly for subsequent transportation through pipelinesor vehicles and conduits without causing plugging and corrosion.

3 Claims, No Drawings NON-CORROSIVE SULFUR-LIQUID HYDROCARBON SLURRY CONTAINING A CORROSION INHIBITING AMOUNT OF A POLAR- CONTAINING SOLVENT CROSS-REFERENCE This is a continuation-in-part of copending patent application Ser. No. 774,218, filed Oct. 30, 1968, now US. Pat. No. 3,606,482.

FIELD OF THE INVENTION The invention relates to a new, improved and novel non-corrosive, non-plugging sulfur-liquid hydrocarbon slurry composition containing therein a small amount of an aqueous solution containing a polar-containing organic solvent such as an alkanol, said slurry composition being particularly designed for transportation through conduits such as pipelines or vehicles such as tankers, etc.

BACKGROUND OF THE INVENTION The transportation of sulfur neat or as a water or oil slurry in pipelines is well known in the art as noted by reference to US. Pats. Nos. 2,798,772; 2,917,345 or 2,947,578 or as described in Pipeline Industry, June, 1967, pages 58-60 or Chem. Eng. Prog., Vol. 61, N0. 2, page 72, 1965. In forming a sulfur-hydrocarbon slurry, the sulfur is generally sprayed in molten form into either water or a hydrocarbon in an amount sufficient to form a slurry. Formation of a stable non-corrosive sulfur-containing slurry wherein the sulfur does not undergo any undesirable change or the slurry does not exhibit a tendency to wide variation in viscosity is essential to the process in addition to other problems which may be encountered during and after transportation of the slurry through a pipeline or a vehicle. Thus, separation of the sulfur from the carrier fluid, results in plating or coating of the sulfur on vessel walls e.g., pipeline walls causing corrosion and plugging of the pipeline. Viscosity changes in the slurry due to pressure and temperature variations encountered under such conditions results in increases in pumping power which increases operation costs, etc. These are few of the problems normally encountered and which must be avoided in transporting sulfur-liquid hydrocarbon slurries through pipelines or other vehicles. However, a most troublesome one is that of corrosion encountered in the preparation, transportation and recovery of such slurry systems for if excessive corrosion is encountered in any of these three phases then the slurry system cannot be put into operation.

Although the above are serious problems for consideration in the preparation and transportation and receiving of sulfur therefrom, if the economically attractive means of preparing and transporting such slurries particularly since sulfur is normally recovered or obtained from isolated, remote and inaccessible areas, and must be transported to desired accessible areas. As noted above, a number of methods have been proposed for pipeline transportation of sulfur slurries such as by injecting molten sulfur into water or a liquid hydrocarbon thereby forming a sulfur slurry suitable for pipeline transportation. Such means for preparing and transporting sulfur do not overcome corrosion, coating or plugging problems described above.

An object of the present invention is to prepare for vehicle transportation e.g., pipeline, tanker, etc. a sulfur-liquid hydrocarbon slurry composition which is non-corrosive stable and flowable.

Another object of the present invention is to transport through a pipeline sulfur-liquid hydrocarbon slurries without causing sulfur coating or sulfur deposition or plugging or corrosion of the pipeline.

Still another object of this invention is to form a slur ry of sulfur in a liquid hydrocarbon medium, which when formed is stable, non-corrosive, does not tend to cause pipeline plugging when said slurry is transported through a pipeline and from which the sulfur can be readily recovered as essentially pure sulfur at the terminal end of the line.

Another object is to prepare for pipeline transportation of sulfur as a liquid hydrocarbon slurry, said slurry being pipeline transported at reduced pumping and handling costs.

Other objects will be apparent from the following description.

SUMMARY OF THE INVENTION The present invention is directed to an improved, novel and'new technique for preparing for vehicle transportation such as pipeline transportation of a sulfur-liquid hydrocarbon slurry over great distances without causing corrosion, coating, deposition or plugging due to the tendency of sulfur under such conditions to coat or adhere to pipeline or vessel walls because of temperature, pressure, and other variable conditions which might be encountered; by admixing or adding or injecting prior to or after injection of a sulfur-liquid hydrocarbon slurry, a small amount of from 0.l percent by weight to 10 percent by weight, preferably between about 0.5 percent by weight to about 5 percent by weight basis total slurry, of an aqueous solution and from about 0.01 percent by weight to about 50 percent by weight of a polar-containing organic solvent basis oil phase preferably selected from the group consisting of mutual soluble alcohol, ketone and/or aldehyde. The aqueous liquid in an amount preferably not exceeding 5 percent by weight basis total slurry and the polar-containing organic mutual liquid solvent can be preferably present in an amount not exceeding 50 percent by weight basis oil phase and each liquid can be injected alternately or simultaneously when necessary in various places along the pipeline or carrying vessel where indications are that corrosion or plugging might take place. Any corrosion and plugging detection means known in the art can be used for this purpose. It has been noted that by injection of l-5 percent by weight basis total slurry of an aqueous solution and 0.01-50 percent by weight of a polar-containing organic solvent basis oil phase such as an alkanol, e.g., methanol or propanol, into a pipeline transporting a sulfur-liquid hydrocarbon slurry in which the sulfur content of the slurry can vary from about 10 percent by weight to about 75 percent by weight or higher, preferably between 40 and percent by weight sulfur, not only inhibits corrosion but prevents plugging of the line due to sulfur agglomeration and deposition on the walls of the pipeline resulting in improved flow of the slurry at reduced pumping cost. A preferred plugging and corrosion preventing composition for sulfur-liquid hydrocarbon slurries being pipeline transported is the addition to such slurries of from 1 to 5 percent by weight water basis total slurry and from 0.01 to 25 percent by weight methanol basis oil phase.

The sulfur-liquid hydrocarbon slurry can be made by any suitable means such as described in U.S. Pats. Nos. 2,798,772 or 3,443,837. It is preferred that methods for making the sulfur-liquid hydrocarbon slurry be used in which the sulfur is produced in spherical form since this facilitates the stable dispersion and suspension of the sulfur in the liquid hydrocarbon carrier and inhibits attrition. The phase transfer method for making the sulfur slurry as described in U.S. Pat. No. 3,443,837 comprises first forming a sulfur-aqueous liquid (water) slurry and thereafter phase transferring the sulfur particles from the aqueous liquid into a liquid hydrocarbon. In this process the phase transformation to form the sulfur-hydrocarbon slurry can be so controlled that a small amount of (1-5 percent by weight) water basis total slurry is transferred with the sulfur-water phase into the hydrocarbon phase and thereafter water-alcohol can be added to accomplish the desired ends of the present invention. Slurries thus prepared contain sulfur in particle of dimensions of 5-5000 microns, preferably 30-350 microns and are essentially spherical in shape.

The hydrocarbon carrier for the sulfur can be any liquid hydrocarbon ranging from a light petroleum fraction such as liquefied petroleum gas (LPG), fuel oil, gasoline, kerosene, petroleum distillates, condensates, crude oil and mixtures thereof. Preferred are liquid hydrocarbons containing at least percent by weight or higher of aromatics, preferably about -50 percent by weight aromatic enriched kerosene or crude oil or crude oil condensate fractions containing 15-20 percent by weight aromatics which include mono and polyaromatic hydrocarbons.

At the terminal end of the line the aqueous solution can be readily separated from the sulfur-hydrocarbon system by suitable phase separation, distillation or the like.

PREFERRED EMBODIMENT OF THE INVENTION A 40-60 percent by weight sulfur-crude oil slurry was prepared by phase transfer by first injecting molten sulfur into an aqueous liquid such as water and thereafter contacting the slurry thus formed with the aromatic enriched kerosene to effect phase transfer of the sulfur particles into the aromatic enriched kerosene, and injecting this slurry into a pipeline followed by injection of 1-5 percent by weight water basis total slurry and 0.01- percent by weight methanol basis oil phase. Sulfur-hydrocarbon slurries thus formed in the presence of the water-alcohol mixture do not corrode or plug the pipeline. Instead of using the phase transfer technique for making the slurry, the molten sulfur can be injected in an oil, e.g., crude oil, directly and thereafter admixed with the water-alcohol mixture.

An advantage of the present process for transporting through pipelines sulfur-liquid hydrocarbon slurries is that the slurry can be also prepared by directed injection of molten sulfur into a suitable liquid hydrocarbon as described in US. Pat. No. 2,798,772 and injecting therein a small amount of water-alcohol mixture so as to prevent corrosion and plugging of the line. Either process as well as other processes can be used to make the sulfur-liquid hydrocarbon slurry depending on the availability of the liquid carriers. Thus, where water is available the first process can be used and if not the second one can be used.

The corrosive effect of added or adventitious water on sulfur-liquid hydrocarbon slurries is evident from the data presented in Table l and the selectiveness of water-alcohol mixture as a corrosion preventive agent is shown in Table 2.

The slurry tested comprised 40 percent by weight sulfur and 60 percent hydrocarbon. The conditions for the corrosion test were as follows:

CORROSION BY SULFUR SLURRIES Conditions:

150 ml magnesia bottles rotated at 10 rpm in EPR bottle rotator.

grams of slurry added to each bottle.

Slurry concentration 40 percent by weight sulfur.

Sulfur particle size: Waterton sulfur 82 percent greater than 45 microns.

Jumping Pound sulfur 81 percent greater than 45 microns.

Oil phase: Aromatic hydrocarbon, Kerosene with 17%x aromatics.

Water additions are percent by weight of the oil fraction.

g X (Sis-inch specimens of 20 gauge mild steel sheet with sandblasted surface.

Specimens wedged into bottles to reduce mechanical damage.

Room temperature (72), atmospheric pressure, 48

hours exposure.

TABLE l SULFUR SLURRY CORROSION AS A FUNCTION OF WATER CONCENTRATION Conditions: As Above. 40%w Waterton sulfur/kerosene with 17%w aromatics.

Water Concentration, %w' Corrosion Rate, mils/yr 0 l 0.28 50 1.12 120 2.2 230 4.4 250 5.0 280 a. Concentration of added water, basis oil. b. From weight loss and exposure time. Corrosion rate has not been corrected for weight loss due to cleaning.

TABLE 2 Sulfur Slurry Corrosion Conditions: As above. 40% Jumping Pound sulfur/liquid phase as given.

Corrosion Rate Liquid Phase (mpy)" 2% Methanol in aromatic hydrocarbon 15 oil 5% Methanol in aromatic hydrocarbon 10 oil 10% Methanol in aromatic hydrocarbon 6 oil a. Liquid phase as indicated plus 2% by weight H,0 basis liquid phase.

b. From weight loss and exposure time. Corrosion rate has not been corrected for weight loss due to cleaning.

At the terminal end of the line the water-polar-containing organic compound mixture can be readily removed by phase separation and the sulfur can be removed from the liquid hydrocarbon by suitable means such as described in U.S. Pat. No. 2,798,772 and the sulfur purified by methods as described in US. Pat. No. 2,809,885 or No. 3,489,677 which comprises treating oil contaminated sulfur with an aqueous solution containing a mixture of alkali hydrosulfide and corresponding hydroxide, e.g., ammonium hydrosulfide and ammonium hydroxide, or by other suitable means such as sulfur can be recovered from the oil slurry by filtration of molten sulfur and liquid-liquid extraction with a hydrocarbon solvent containing -50 percent by weight aromatic. Thus, at the receiving terminal the sulfur slurry can be filtered and washed. The recovered sulfur is then melted and purified by liquid-liquid extraction with an aromatic hydrocarbon such as cumene. Also, if desired, the filtered sulfur can be steam stripped to recover bright yellow sulfur.

The foregoing description of the invention is merely intended to be explanatory thereof. Various changes in the details of the described method may be made within the scope of the appended claims without departing from the spirit of the invention.

1 claim as my invention:

1. A method of reducing the corrosiveness of a sulfur-liquid hydrocarbon slurry composition to a pipeline comprising providing therein about 1 percent to about 5 percent basis total slurry of an aqueous solution containing from about 0.01 percent to about 50 percent of an oxygen-containing polar organic compound selected from the group consisting of alcohols, ketones and aldehydes.

2. A method of reducing the corrosiveness of a sulfur-liquid petroleum slurry composition to a pipeline comprising providing therein about 1 percent to about 5 percent basis total slurry of an aqueous solution containing from about 0.01 percent to about 50 percent of an alkanol.

3. A method of reducing the corrosiveness of a sulfur-liquid crude oil slurry composition to a pipeline comprising providing therein about 1 percent to about 5 percent basis total slurry of an aqueous solution containing from about 0.01 percent to about 50 percent of methanol.

Claims (2)

1. A method of reducing the corrosiveness of a sulfur-liquid hydrocarbon slurry composition to a pipeline comprising providing therein about 1 percent to about 5 percent basis total slurry of an aqueous solution containing from about 0.01 percent to about 50 percent of an oxygen-containing polar organic compound selected from the group consisting of alcohols, ketones and aldehydes.

2. A method of reducing the corrosiveness of a sulfur-liquid petroleum slurry composition to a pipeline comprising providing therein about 1 percent to about 5 percent basis total slurry of an aqueous solution containing from about 0.01 percent to about 50 percent of an alkanol.