US3380784A

US3380784A - Process of transporting a slurry in a pipeline

Info

Publication number: US3380784A
Application number: US433049A
Authority: US
Inventors: Parke O Yingst; Thomas I Sharps
Original assignee: Northern Gas Products Co
Current assignee: Northern Gas Products Co
Priority date: 1965-02-16
Filing date: 1965-02-16
Publication date: 1968-04-30
Anticipated expiration: 1985-04-30

Description

United States Patent 3,380,784 PROCESS OF TRANSPORTING A SLURRY IN A PIPELINE Parke 0. Yingst, Golden, and Thomas I. Sharps, Boulder,

(3010., assignors to Northern Gas Products Company,

Omaha, Nelm, a corporation of Delaware Filed Feb. 16, 1965, Ser. No. 433,049 14 Claims. (Cl. 302-66) ABSTRACT OF THE DISCLOSURE Disclosed is a process of transporting in a pipeline a solid material, such as potash, suspended in a liquid petroleum product, such as crude oil. The solid material is suspended in the oil by means of a copolymer of methyl vinyl ether and maleic anhydride.

This invention relates to the simultaneous transportation by pipeline of a liquid petroleum product containing granules of one or more solid materials.

Since the cost of shipping solid materials by conventional means such as truck and rail is often excessive, investigation has previously been made as regards the feasible transporting of granular or particulate materials such as potash, soda ash, sulfur, sodium sulfate, phosphate rock, iron ore and coal suspended in a liquid petroleum product by means of a pipeline. The economics of such a transportation means is obvious in those localities where such solid materials are mined adjacent to areas from which petroleum products are recovered and shipped by pipeline. This transportation means is, of course, equally applicable where such solid materials and liquid petroleum products are reshipped from the same general depot areas.

Although the transportation of solid materials in liquid petroleum products has been studied quite extensively, a number of problems have been met and one of the greatest has been the normal tendency for the solid material to settle out of the suspending liquid medium with compaction that resists ready redispersion.

When solids of various particle sizes are dispersed in a liquid medium and permitted to settle in an unhindered manner the large particles settle out first, then the finer and finally the finest size particles settle in layers one upon the other. The resulting settled mass is compact and can only be redispersed with difficulty if at all.

In hindered settling the solids do not separate and settle according to size but instead settle as a mass.

One approach to reducing compaction where solids are unhindered is to pump the liquid slurry through the pipeline at a high velocity. This, however, results in increased cost because of the high pumping velocities required.

As shown in Cross U.S. Patent 2,610,900, various solid materials including potash (potassium chloride) require special means to obtain useful suspending capacity in liquid petroleum products when transported in a pipeline. Cross states that by regulating the viscosity and/or the particle size of the solid material, the velocity can be reduced and the solid materials maintained adequately in suspension to permit its transportation in the pipeline.

Cross states that the particles should be small enough to pass a 100 mesh screen. However, particles even of that size and smaller tend to stratify and compact upon settling. As a slurry is pumped through a pipeline, or when pumping stops, the larger particles settle more rapidly than the smaller particles. When the various size particles settle naturally, due to the different settling veloci- 'ice ties, they tend to stratify and compact quite densely in the bottom of the pipe. The denseness of the compaction can make is very difiicult, if not impossible, to start the stream moving again after the pipeline is shut down.

It is also known that particles settle more rapidly and with considerable compaction from slurries containing a lower percentage of solids. As the percentage of solids is increased, hindered settling results. It might be desirable, however, for economical reasons to employ slurries which contain a lower solids content, such as of about to solids, rather than the more concentrated slurries in the area of about solids or higher even though the higher concentrated slurries give a more hindered settling effect. The subject invention allows for such flexibility.

Cross also teaches in his patent that settling can be reduced by viscosity control by putting in various viscosity increasing materials. While the settling may be reduced, the viscosity regulating approach is not convenient, leads to increased operating costs in pumping the viscous material through the pipeline and does not solve the problem of starting the pipeline in operation after a shutdown period during which compaction of the settled solids has occurred.

It 'has been found according to the subject invention that a slurry mixture of particles of a solid material dispersed thoroughly in a normally liquid petroleum product, and which mixture contains a small amount of a polymer of methyl vinyl ether and maleic anhydride, gives a hindered slurry which can be forced through a pipeline to a collecting depot with high efficiency, comparatively low power consumption and compaction reduced to a low level which does not interfere with transportation in the pipeline or restarting flow of the slurry after stoppage. The inclusion in the slurry of a small amount of a polymer of methyl vinyl ether and maleic anhydride causes the particles of dispersed solid material to fiocculate and brings about a far greater hindered settling condition than could be achieved by increased concentration alone.

This effect is achieved even at low concentrations of solids such as below 30% and even down to 20%. Such a slurry stream can be pumped at a low velocity, thus requiring less power and furthermore, if the material does have occasion to settle to the bottom of the pipe, there is no significant stratification of the various size particles, the settled mass is more bulky and much less compact than has been obtained in the past and is much more readily redispersed. Although the solids settle faster from such a slurry than from a slurry containing no added polymer, the solids from the latter settle as beach sand while with the polymer they are somewhat gelatinous. This property makes the thickened solids more fluid, even at a high percentage of solids and reduces the problem of pumping, together with reduced friction head loss.

Because of the high stability of the dispersion obtained with the polymer it can be added at the intake end of a pipeline. The violent action in a pipeline will not break up the agglomerated particles or flocs in transit. The hindered condition of the slurry is thus maintained throughout transport in a pipeline.

While a large number of solid materials can be conveniently transported dispersed in a liquid petroleum product the invention is particularly useful for transporting water-soluble solid materials and particularly potash (potassium chloride).

The concentration of solid materials in the slurry can vary considerably but usually the slurry will contain about 25 to 50% by weight of solids, such as potash.

The particulate solid materials in the slurry should generally be quite small and advisably the diameter of the particles should be about 2.00 mm., which is the sieve opening of a mesh screen, or less. Because of the fiocculating capacity of the polymer used to agglomerate the particles, it is unnecessary to carefully classify the particles of the solid material into different sizes or grades based on average diameter range as is usually the case with prior art transporting processes. Since the suspending ability of the polymer maintains the solid particles in suspension for sufficient time and because upon settling the solids do not stratify or compact, it is unnecessary to carefully control particle size. Of course, particles should not be unduly large or unnecessarily small so as to negate the advantages that are obtainable by employment of the invention.

A commercially available copolyrner of methyl vinyl ether with maleic anhydride which can be used is Gantrez AN169. It contains a one to one molar ratio of methyl vinyl ether to maleic anhydride with repeating units of the formula It has a specific viscosity of about 2.6-3.5 as determined on a solution of 1 g. of the copolymer in 100 ml. of methylethylketone at C.

Only small amounts of the polymer of methyl vinyl ether with maleic anhydride need be included in the slurry to effect suitable agglomeration, concomitant suspension and hindered dispersion. The slurry may contain about 0.005 to about 0.50 pound of polymer per ton of solid materials, such as potash, in the slurry with a representative suitable optimum amount being about 0.02 pound per ton of solid materials.

In order to obtain thorough distribution of the polymer through the slurry, it is advisable to first dissolve the polymer in a solvent which is miscible with the liquid petroleum product to be employed in the transportation system. Although many solvents might be used, because of its availability and low cost, methanol is the solvent of choice. It dissolves not only the polymer but is totally miscible with the liquid petroleum product. Such solvent need only be used in an amount adequate to dissolve the polymer and thereby obtain its distribution throughout the liquid petroleum product. A 0.01% solution of the polymer in methanol added to give about 0.1 pound of polymer per 1,000 pounds of solids (potash) is particularly useful. Other solvents for the polymer which can be used are propanol, ethyl acetate, acetone, benzaldehyde, phenol, pyridine and cyclohexanone. The amount of polymer added will generally not exceed 1% of the solution because higher amounts dissolve slowly and make the solution undesirably thick.

The invention is useful with a wide variety of crude and refined hydrocarbon oils of various viscosities. The addition of more polymer to the less viscous oils than to the heavier oils is to be expected. Furthermore, in order to obtain optimum results the solids concentration should usually be greater in the lighter oils than in the more viscous oils.

Not only does the polymer of methyl vinyl ether and maleic anhydride facilitate transportation in a pipeline but the copolymer also facilitates separation of the solids from the oil whether the separation be by filtration, cycloning or other means. Even in cases where the polymer is not used in the slurry when transported by a pipeline it is advantageous to incorporate the polymer in the slurry when separation from the oil is to be effected.

Pipeline experimental tests have shown that at any specific velocity below the transitional velocity, the friction head loss is less for those slurries to which the polymer has been added. Higher velocities, but with lower friction head loss, are required to reach the critical and transitional velocities of the polymer-containing slurries than slurries containing the same concentration of potash but without the polymer.

EXAMPLE 1 Percent Accumulative Percent +35 mesh 9. 6 9. 6 35 +48 mesh 16. 9 2'"). 5 -4S +65 mesh 20. 9 47. 4 -+i5 mesh 19.9 07. 3 100 +200 mesh 22. 4 S9. 7 200 mesh" 10. 3 100. 0

Settling tests were conducted by adding the slurries to the graduate. The slurry was added up to the 1.000 ml. mark of the graduate to give a slurry column about 265 mm. or 10.4 inches high. The results showed a clear effluent-slurry interface that was pronounced and readily followed. To facilitate recording the settling data a grad uated (inches) strip of paper was attached to the outside surface of the graduate with the zero graduation indexed at the meniscus of the slurry. The descending clear efiiuent-slurry interface was illuminated by a spotlight directed toward the graduate from the front. Prior to taking measurements the graduate containing the slurry was agitated vigorously for several minutes to disperse the potash particles. Immediately thereafter the descent of the clear efiiuent-slurry interface was observed and followed downward in inches per minute. The runs were made without added polymer. The settling of the solids was unhindered, the sediment was stratified and compacted.

FIGURES 1, 3 and 5 give the pertinent data in graph form from these control runs.

EXAMPLE 2 Additional settling tests were performed with the additional use of Leduc oil besides the oils used in Example 1. The No. 1 special standard potash was used to make slurries containing 30%, 40% and 50% by weight of potash solids. The settling characteristics of the slurries were measured with and without the addition of a polymer of methyl vinyl ether and maleic anhydride (commercially available as Gantrez AN 169). The polymer was incorporated in methyl alcohol to give a 0.1% solution which was added to the oil so that the slurry contained 0.02 pound of polymer per ton of dry solids.

Pertinent data from the runs follows:

Weyburn Oil 30% 40% 50% Solids Solids Solids Specific gravity, oil, g./cm.'- 0. 878 0.878 0.878 Specific gravity, slurry, g./cm." 1. 055 1.132 1. 221 Oil viscosity 19.6 at 22 C. Slurry viscosity without polymer..- 28. 5 39. 6 111. Slurry viscosity with added polymer 120.0 Average particle size, mm- 0. 218 0.218 0.218 Maximum particle size, mm. 0. 420 0. 420 0. 420 Average settling velocity of slurry without polymer, tt./sec 0. 00161 0.00050 0.00035 Average settling velocity of slurry with added polymer, it./sec 0.0023 0.0012 0.00017 Lloydminster No. 1 Oil 30% 40% 50% Solids Solids Solids Specific gravity, oil, g./cm.- 1.064 1. 064 1. 064 Specific gravity, slurry, g./cm.- 1. 237 1. 308 1.390 Oil viscosity 13.3 at 22 C. Slurry viscosity without polymer... 17. 0 52. 129.0 Slurry viscosity with added polymer 136. 0 Average particle size, mm 0.218 0.218 0. 218 Maximum particle size, mm 0. 420 0. 420 0. 420 Average settling velocity of slurry without polymer, it./sec 0.0011 0.00052 0. 00016 Average settling velocity of slurry with added polymer, ft./sec 0. 00208 0. 00046 0. 00018 Lloydminster No. 2 Oil 30% 40% 50% Solids Solids Solids Specific gravity, oil, g./cm.'- 0.910 0.910 0.910 Specific gravity, slurry, g./cm.- 1.088 1.164 1.251 Oil viscosity 86.5 at 22 C. Slurry viscosity without polymer... 328.0 450. 0 Average particle size, mm 0.218 0.218 0 218 Maximum particle size, mm 0. 420 0. 420 0 420 Average settling velocity of slurry without polymer, it./sec. .0004 0.00021 0. 000051 Average settling velocity of slurry with added polymer, it./sec 0.00016 This data shows that the slurries containing the polymer settled about as fast as the slurries containing no polymer. However, the slurries containing the polymer did not give stratified layers of potash upon settling, as did the slurries containing no polymer, and the potash in the polymer-containing slurries did not compact upon settling.

EXAMPLE 3 Percent +100 +200 16.6 200 83.4

This material had been run through a high speed hammer mill and had a large percentage of solids in the 1 to 74 micron range.

The screen analysis of the final potash mixture (90% No. 1 special standard potash and of l00 mesh potash fines) was:

Mesh Percent The 10% of fines was incorporated into the slurry to simulate the accrued fines of attrition which would nor mally be found after transportation in a pipeline.

A polymer of methyl vinyl ether and maleic anhydride (commercially available as Gantrez AN 169) was incorporated in methyl alcohol to give a 0.1% solution which was added to the oil so that the resulting slurries contained 0.02 pound of polymer per ton of dry solids.

Settling tests were conducted by adding the slurries to a graduate as in Example 1 and the procedure therein followed. The settling of the solids was hindered, the sediment was unstratified and free of compaction. Graphs of the data obtained are shown in FIGURES 2, 4 and 6. By comparing FIGURE 1 with FIGURE 2, FIGURE 3 with FIGURE 4, and FIGURE 5 with FIGURE 6 it will be seen that the potash compacts far more when the polymer is not used than when it is included in the slurries. The vastly different settling characteristics of the slurries with and without the polymer are best appreciated by actual observation of the materials in a settling test. Words and figures are not fully capable of adequately communicating this difference. Full comprehension requires observation of the settling slurries.

EXAMPLE 4 A slurry containing 50% No. 1 special standard potash as described in Example 1 in Leduc oil having a viscosity of 5.0 at 22 C. and 0.02 pound of Gantrez AN 169 per ton of dry solids was prepared. The slurry was tumbled in a laboratory size ball mill with only lifters in the mill for approximately 48 hours. At normal speeds of 10 feet per second, this would be equivalent to transporting the slurry about 340 miles in a pipeline. After this treatment the slurry was transferred to a settling cylinder and the settling observed. Visual observation showed there was no change or breaking up of the floc from the tumbling action, indicating that the dispersion will not be destroyed during transportation in a pipeline.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

What is claimed is:

1. The method which comprises mixing particles of solid potash, a normally liquid petroleum product and a copolymer of methyl vinyl ether and maleic anhydride to form a slurry, said copolymer being present in an amount sufiicient to maintain said potash particles in suspension in said petroleum product forcing the slurry through a pipeline to a collecting depot and separating the solid material from the petroleum product.

2. The method of claim 1 in which the copolymer incorporated in the mixture is dissolved in a petroleum miscible solvent.

3. The method of claim 1 in which the slurry contains 25 to 50% by weight of potash.

4. The method of claim 1 in which the slurry contains about 0.005 to about 0.50 pound of copolymer ton of potash.

5. The method of claim 1 in which the potash particles average no more than 1.65 mm. in diameter.

6. The method which comprises thoroughly mixing together (l) potash particles, (2) a normally liquid petroleum product and (3) a solution of a copolymer of methyl vinyl ether and maleic anhydride dissolved in a petroleum product miscible solvent to form a slurry, said copolymer being present in an amount sufiicient to maintain said potash particles in suspension in said petroleum product forcing the slurry through a pipeline to a collecting depot and thereafter separating the potash from the petroleum product.

7. The method which comprises thoroughly mixing together (1) potash particles, (2) a normally liquid petroleum product and (3) a solution of a copolymer of methyl vinyl ether and male-ic anhydride dissolved in a petroleum product miscible solvent to form a slurry containing 25 to 50% by weight of potash and about 0.005 to about 0.50 pound of polymer per ton of potash, forcing the slurry through a. pipeline to a collecting depot and thereafter separating the potash from the petroleum product, said copolymer having a specific viscosity of about 2.6-3.5 as determined on a solution of 1 g. of the copolymer in 100 ml. of methylethylketone at 25 C.

8. The method of claim '7 in which the miscible solvent is methanol.

9. A slurry consisting essentially of a mixture of potash particles, a normally liquid petroleum product and a copolymer of methyl vinyl ether and maleic anhydride said copolymer being present in an amount sufficient to maintain said potash particles in suspension in said petroleum product.

10. A slurry consisting essentially of a mixture of potash particles, a normally liquid petroleum product and a solution of a copolymer of methyl vinyl ether and maleic anhydride dissolved in a petroleum product miscible solvent said copolymer being present in an amount sufficient to maintain said potash particles in suspension in said petroleum product.

11. A slurry according to claim 10 containing 25 to 50% by weight of potash and about 0.005 to about 0.50 pound of copolymer per ton of potash.

12. A slurry according to claim 11 in which the potash particles average no more than 1.65 mm. in diameter.

113. A slurry consisting essentially of a mixture of 25 to 5 0% by weight of particles of potash, a normally liquid petroleum product and a solution of a copolymer of methyl vinyl ether and maleic anhydride dissolved in a petroleum product miscible solvent, the amount of copolymer in the slurry being about 0.005 to about 0.50 pound per ton of potash, and the copolymer having a specific viscosity of about 2.63.5 as determined on a solution of 1 g. of the copolymer in 100 ml. of methylethylketone at 25 C.

14. A slurry according to claim 13 in which the potash particles average less than 1.65 mm. in diameter.

References Cited UNITED STATES PATENTS 9/1952 Cross 302-66 12/1962 Scott 252--8.5

* UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,380 784 April 30, 1968 Parke O. Yingst et :11.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

' Column 2, line 3, "is" should read it Column 4, line 10 "1 .000" should read l ,000 Column 5 line 72 "-65+65' should read -48+65 Column 6, line 58, "copolymer" should read copolymer per Signed and sealed this 28th day of October 1969.

(SEAL) Attest:

1 2mm M. Fletcher, Jr. WILLIAM E. SCHUYLER, JR.

At testing Officer Commissioner of Patents