GB2214517A - Carrier for additives for liquid hydrocarbons - Google Patents

Abstract

A composition suitable for addition to a liquid hydrocarbon and dissolution therein comprises either a solid or hollow mass of intimately mixed and bonded carrier material (e.g. naphthalene) and additive material (e.g. an ethylene/vinyl acetate flow improver) or an envelope, the walls of which comprise the carrier material and the enclosure of which is occupied by the additive material. The carrier material has to be relatively strong, relatively non-tacky and relatively quickly soluble in the liquid hydrocarbon.

Description

ADDITIVES FOR LIQUID HYDROCARBONS This invention relates to additives for liauid hydrocarbons, for example, fuel oils.

At the moment there are several liquid flow improvers which are sold at service stations for addition to diesel fuels for improving the cold flow properties of the diesel fuel.

Such flow improvers suffer from the disadvantages that it is not easy to control the exact amount of flow improver added to the diesel fuel oil as it is poured in and that it can be messy with wastage of liquid due to slopping down the sides of the filler pipe.

We have now devised a different way of addino flow improvers and other additives to liquid hydrocarbons such as fuel oils which overcomes the difficulties encountered by liquid additives.

According to this invention a composition suitable for addition to a liquid hydrocarbon and dissolution therein comprises either a solid or hollow mass of intimately mixed and bonded carrier material and additive material or an envelope, the walls of which comprise a carrier material and the enclosure of which is occupied by additive material. It is necessary for the carrier material to have hereinafter defined properties i.e. relative strength, relative non-tackiness and relative quick solubility in the liquid hydrocarbon to which the composition is added.

The compositions of this invention are mainly designed for addition to liquid hydrocarbons which are often stored in a tank, i.e.

liquid hydrocarbons such as distillate fuel oils, e.g. gasoline, diesel fuel, aviation fuel, kerosene, fuel oil, jet fuel, heating oil etc. Generally suitable distillate fuel oils are those boiling in the ranqe 1500C to 4000C, for example, those having a relatively high final boiling point (FBP) of above 3600C. Diesel fuel oils are the ones for which the compositions of this invention are particularly designed and a representative specification for a diesel fuel includes a minimum flash point of 380C and a 90 per cent distillation point of between 282"C and 3380C (ASTM Desiqnations 0-396 and D975).

The carrier material has to be relatively strong, i.e. the composition of the invention must be able to withstand a pressure of 250 gm/mm2 without collapsing. It also has to be relatively non-tacky i.e. the composition of the invention in the form of a sphere must be able to roll down a glass sheet inclined at 50 to the horizontal, freely leaving no trace of material on the sheet. It must however have sufficient tackiness so that the composition of the invention holds together. Also it has to dissolve relatively quickly in the liquid hydrocarbon to which it is added and this means that it dissolves completely in the liquid hydrocarbon in 24 hours and by at least 80 by weight in 10 hours.

The carrier material can be of various types, but hydrocarbon or halohydrocarbon materials, e.g. hydrocarbon wax, 1.4 dichlorobenzene, and especially naphthalene have been found to be suitable. Another suitable material is camphor.

The additive material can be solid or liquid, but if liquid it can only be used in an envelope. The purpose of the additive material can be manifold, e.g. anticorrosive, deteroent, anti-wear, anti-agglomerant, pour depressant, or algaecidal. However, it is as a flow improver that the compositions of this invention are particularly suitable.

Suitable additives can, for example, be a dialkyl fumarate/vinyl acetate copolymer; a dialkyl maleate/vinyl acetate copolymer; an ethylene/vinyl acetate copolymer; a maleic anhydride/styrene copolymer; a copolymer of maleic anhydride with a C10 to 30 olefin, such as dodecene; a dialkyl fumarate or maleate/maleic anhydride copolymer; a vinyl acetate/maleic anhydride copolymer; a dialkyl fumarate or maleate/maleic anhydride/vinyl acetate copolymer; a polyacrylic acid polymer or a polymethacrylic acid copolymer. Other suitable copolymers which can be used as the additive are as mentioned above but usinq a dialkyl itaconate or citraconate instead of a dialkyl fumarate.

The solid or hollow mass or the envelope can be of various shapes, for example cubic, cuboid, pyrimidal, polyhedral, cylindrical Preferably, however, they are ovate, elliosoidal or spherical since these three shapes are least likely to cause blockage when they are dropped into a filler pipe.

To make the solid mass of carrier and additive materials, the two materials in finely divided form e.g. particulate, are thoroughly mixed in the desired quantities and then may be compacted into moulds to produce the desired shape e.g. ellipsoid or sphere Usually the spheres will be 1 to 5 cm in diameter. However, if the desired shape is cylindrical, cubic or cuboidal the mixed materials may be extruded into long lengths and thereafter cut into pieces of the desired length.It is clear that the carrier material andicr additive material should have some tackiness so that the two materials can bind toqether. However, there should not be too much tackiness on the surface, otherwise the mass might stick to the sides of a filler pipe rather than enter the container housing the liquid hydrocarbon.If the two materials are not tacky enough to bind together, then a binding agent could be added.

Where the composition is added to a liquid hydrocarbon, e.g.

diesel fuel, housed in a mobile tank, e.g. a diesel driver vehicle, rather than use a solid mass it is preferable to use a hollow mass in which the buoyancy is sufficient for the mass to float on the surface of the liquid hydrocarbon. This is desirable because the slight pitching and rolling of the liquid hydrocarbon will make dissolution of the additive quicker with a floating mass than with a sunken mass.

The hollow masses can be made by pressina together two moulded halves of the intimately mixed and bonded additive and carrier materials so as to enclose an air pocket preferably of sufficient size to result in a buoyant mass when introduced into a liquid hydrocarbon.

Optionally, some heatina is applied when bonding together the two halves.

When the composition is in the form of an envelope, the envelope is usually a mixture of carrier and additive materials. However, the possibility of the envelope being formed only of carrier material is not excluded.

As with solid or hollow masses, the preferred shapes for the envelopes are ovate, ellipsoid or spherical and it is convenient to make the envelope in two halves, e.g. two hemispherical shells, and bond them together after inserting the desired amount of additive material into the enclosure. Alternatively, for example, the envelope could be made in the shape of a bottle, preferably substantially spherical, additive material inserted into the neck which could be quite short and the aperture in the neck sealed thus enclosing additive material in the bottle. As another alternative the envelope could be made with an aperture in the surface thereof i.e.

substantially as a neckless bottle, additive material inserted through the aperture and the aperture thereafter sealed.

The most convenient way of forming the solid or hollow masses or envelopes is by means of a mould. For solid masses the intimate mixture of carrier and additive is introduced into the mould and the solid mass, e.g. a sphere, is formed usually by the application of pressure and heat. Thereafter the solid mass is removed from the mould, which conveniently will be in two halves.

For hollow masses and envelopes, the mould is conveniently made in two halves, e.a. as two shells, which are thereafter welded together optionally with the application of heat, after inclusion of the additive. Alternatively, as mentioned above the two halves can be welded together first and the additive inserted through a neck or aperture in the hollow mass or envelope, and the neck or aperture thereafter sealed.

For solid or hollow masses or for envelopes the relative amounts of carrier and additive preferably lie between 60 to 90 -wt t carrier and 40 to 10 wt 0 additive, preferably 75 to 85 wt t carrier and 25 to 15 wt < additive.

Usually with the compositions of this invention storage stability is achieved under all normal ambient conditions and in addition complete dissolution in a liquid hydrocarbon occurs within 24 hours and often much quicker, e.g. within 10 hours.

Example 1 In this Example a series of solid balls and hollow outer shells (subseauently welded together) of various materials was prepared.

500 ml beakers each containing 40 m of a diesel fuel oil fuel were placed in a cold box and allowed to stabilise at OOC. Each ball was weighed, its volume estimated and one ball was placed in each of the beakers and the test commenced.

The temperature of fuel in a vehicle tank can easily rise 20 C after one hour's running and substantially more in certain specific fuel systems. Since in the United Kingdom the Cold Filter Plugging Point (CFPP) target temperature is -9 C a realistic test was therefore insertion of the balls and hollow shells (for convenience referred to as flow balls) into the fuel at a cycle of 0 C to +10 C over half an hour and then a cycle of between +10 C and -10 C. During the hiaher temperature cycles the beakers were gently rocked to simulate fuel movement in an actual vehicle tank.

The condition of the balls and shells was inspected at 10.5 hours 'representing the time the truck would be parked for the night) and also at 24 hours (by which time all the material should have dissolved).

The results obtained are shown in Table I, from which it can be seen that naphthalene is probably the best carrier material.

TABLE I Approx.

Flow Ball Vol. in Wt of undissolved Approx. treat Construction Wt in grams ml prior Condition of ball Condition after material after (ppm ai) dis Material Solid Hollow prior to test to test prior to test 10.5 hours 24 hours solved material C.F.P.P.

Additive A / 1.128 1.15 Strong not tacky Wavy strands Mush 37.5 -7 -9 spreading out 1.113 Additive A / 0.886 0.4 Rigid not tacky Swollen up but Mush 190 -9 -6 still floating 0.809 50 : 50 / 1.082 1.15 Strong but moist No change Mush 1085 -4 -5 Add.B/N aph- to touch 0.648 thalene 50 : 50 / / 0.727 0.45 Moderately strong No change Mush 1177.5 -4 -6 Naphthalene moist to touch 0.256 Additive C / 1.106 1.15 Strong not tacky No change Unchanged 0 -5 -7 1.135 Additive / 0.684 0.45 Moderately rigid No change Unchanged 7.5 -6 -3 not tacky 0.681 Hydrocarbon / 1.147 1.15 Solid not tacky No change Unchanged 55 -4 -6 wax 1.125 Hydrocarbon / 0.541 0.45 Very rigid not No change Unchanged 10 -6 -4 wax tacky 0.537 Naphthalene / 1.350 1.15 Very hard strong Brocken up some Nearly all 3035 -4 -6 small bits left dissolved 0.136 Naphthalene / 0.860 0.45 Very hard strong Almost totally All dissolved 2150 -5 -5 dissolved slight 0 residue TABLE I Cont'd Approx.

ow Ball Vol. in Wt of undissolved Approx. treat nstruction Wt in grams ml prior Condition of ball Condition after material after (ppm ai) disterial Solid Hollow prior to test to test prior to test 10.5 hours 24 hours solved material C.F.P.P.

ditive D / 1.003 1.15 Rigid not tacky Split apart Mush breaking up into 0.932 177.5 -6 -5 wavy strands ditive / 0.563 0.45 Low/moderate Split apart Mush rigid not breaking up 0.786 0 -5 -9 tacky :50 1.024 1.15 Moderately strong No change 1.004 50 -8 -8 ditive E/ / not tacky drocarbon Wax :50 0.614 0.45 Moderately strong No change 0.574 100 -6 -9 ditive E/ a little crumbly drocarbon / :50 / 1.141 1.15 Strong moist to No change 1.149 0 -5 -4 ditive B/ touch drocarbon Wax :50 ditive B/ / 0.654 0.45 Fragile moist to No change 0.686 0 -4 -7 drocarbon touch ditive A is an ethylene-vinylacetate copolymer with a content of 16.5 wt % vinylacetate.

ditive B is the reaction product of phthalic with a diamine R2NH where R is C16/C18 hydrogenated tallow in a 2:1 mole ratio producing the N dialkylamide, N dialkylammonium salt of phathalic acid.

ditive C is polyethylene glycol dibehenate, the glycol portion having a molecular weight of about 600.

ditive D an ethylene-vinyl acetate copolymer with a content of 13.5 wt % vinyl acetate.

ditive E a mixed [C12/C14 n alkyl-monomethyl polyethylene glycol (MW ~ 750)] dialkyl fumarate.

Details of the Cold Filter Plugging Point Test (CFPPT) are as follows: The cold flow properties of the blend were determined by the Cold Filter Plugging Point Test (CFPPT). This test is carried out by the procedure described in detail in "Journal of the Institute of Petroleum", Vol. 52, No.510, June 1966 pp.173-185. In brief, a 40 ml.

sample of the oil to be tested is cooled by a bath maintained at about 340. Periodically (at each one degree Centigrade drop in temperature startling from 20C above the cloud point) the cooled oil is tested for its ability to flow through a fine screen in a time period.

This cold property is tested with a device consisting of a pipette to whose lower end is attached an inverted funnel positioned below the surface of the oil to be tested. Stretched across the mouth of the funnel is a 350 mesh screen having an area of about 0.45 square inch.

The periodic tests are each initiated by applying a vacuum to the upper end of the pipette whereby oil is drawn through the screen up into the pipette to a mark indicating 20 my. of oil. The test is repeated with each one degree drop in temperature until the oil fails to fill the pipette to a mark indications 20 ml of oil. The test is repeated with each one degree drop in temperature until the oil fails to fill the pipette within 60 seconds. The results of the test are quoted as A CFPPT (OC) which is the difference between the fail temperature of the untreated fuel (CFPPo) and the fuel treated with the flow improver (CFPP1) i.e. # CFPP = CFPPo- CFPP1.

Example 2 Several variations of solid and hollow flow balls were made comprising 100% 1,4 dichloro benzene, 100E naphthalene and 77.5 wt < carrier medium (naphthalene) and 22.5 wt % of an ethylene-vinyl acetate copolymer mixture.

15.59 of the carrier medium (naphthalene)were weighed into a beaker and to this 3.375 9 of an ethylene-vinyl acetate copolymer (Additive G) and 1.125 g of another ethylene-vinyl acetate copolymer (Additive A) were added. This mixture was then heated, stirred until homogeneous and then poured into moulds to give the desired solid and hollow flow balls.

From the results shown in Table II it can be seen that naphthalene appears to be the best carrier. Both 1.4 dichlorobenzene and camphor or their own and as carrier media show very good solubility but they tend either to sublime or go musky under storage at 40 C.

TABLE II Weight of Condition of Flow Ball undissolved After Strorage in 40 C position Wt of Ball Condition after material Oven for X days flow Balls Hollow Solid (grams) 10.5 hours after 24 hours 1 2 3 4 5 6 7 8 9 10 15 @ 1.4 @lorobenzene # 1.310 Mostly dissolved 0 # # # # x @ Camphor # 0.457 Mostly dissolved 0 # # # # # # @ Camphor # 0.998 Mostly dissolved 0 # # # # x @% Naphthalene # 0.592 Mostly dissolved 0.160 # # # # # # @% Additive F @% Naphthalene # 1.142 Mostly dissolved 0.860 # # # # # # @% Additive F tive F a mixture of 25 wt % Additive A and 75 wt % Additive G where G is an ethylene-vinyl acetate copolymer having a content of about 37 wt % vinyl acetate Example 3 Four hollow flow balls were made usina different ratios of ethylene-vinyl acetate (Additive F) copolymer and naphthalene.

From the results shown in Table III it can be seen that various ratios dissolve almost completely in the 24 hour test period. Both the storage and CFPP results are good with 80 wt t naphthalene, 20 wt Additive F hollow ball test.

Although for testing purposes a temperature of 40"C was used, in practice this is a much higher temperature than is likely to be encountered and a maximum temperature of 250C is more likely in practice.

TABLE III Weight of Weight of Weight of Condition Undissolved Approx treat Condition of flowball after Composition Case in Full in After Material after of Dissolved CFPP Storage in 40 Oven for X Days of Flowball Grams Grams 10.5 Hrs. 24 Hrs in Grams Material in PPM al C 1 2 3 4 5 6 7 8 9 90% Naphtha- Broken into 1449 / / lene 0.680 two pieces 0.036 Naphthalene -2 -2 10% Additive F mostly (5.29%) 161 Add.F dissolved 85% Naphthalene 0.128 1300 / / 15% Additive F 0.740 " (17.29%) Naphthalene 229 Add.F 85% Naphthalene 0.128 1300 / / 20% Additive F 0.677 " (2.21%) Naphthalene 331 Add.F -6 -9 90% Naphthalene) 0.927 Partially 1987 10% Additive F ) -0.666 dissolved Naphthalene -2 -1 / / 90% Naphthalene 0.666 0.261 0.44 221 Add.F 10% Additive F (4.75%) Powdered Fill

Claims (10)

CLAIMS:

1. A composition suitable for addition to a liquid hydrocarbon and dissolution therein comprising either a solic or hollow mass of intimately mixed and bonded carrier material and additive material or an envelope, the walls of which comprise a carrier material and the enclosure of which is occupied by additive material; said carrier material having hereinbefore defined properties of relative strength, relative non-tackiness and relative quick solubility in said liquid.

2. A composition according to claim 1 wherein the carrier material is a hydrocarbon, preferably naphthalene.

3. A composition according to either of claims 1 and 2 wherein the additive material is a flow improver, preferably an ethylene/vinyl acetate copolymer.

4. A composition according to any one of the preceding claims wherein the solid or hollow mass or envelope is substantially ovate, ellipsoidal or spherical.

5. A composition according to any one of the precedina claims wherein the amounts of carrier and additive material lie between 60 and 90 wt S carrier and 40 and 10 wt t additive.

6. The use as an additive to a liquid hydrocarbon and subsequent dissolution therein of either a solid or hollow mass of intimately mixed and bonded carrier material and additive material or an envelope, the walls of which comprise a carrier material and the enclosure of which is occupied by additive material wherein said carrier material has hereinbefore defined properties of relative strength, relative non-tackiness and relative quick solubility in said liquid.

7. The use according to claim 6 wherein the carrier material is a hydrocarbon, preferably naphthalene.

8. The use according to either of claims 6 and 7 wherein the additive material is a flow improver, preferably an ethylene/vinyl acetate copolymer.

9. The use according to any one of claims 6 to 8 wherein the solid or hollow mass or envelope is substantially ovate, ellipsoidal or spherical.

10. The use according to any one of claims 6 to 9 wherein the amount of carrier and additive material lie between 60 and 90 wt X carrier and 40 and 10 wt % additive.