US3380909A - Anti-foulant for hydrocarbon feed streams - Google Patents

Description

United States Patent 3,380,909 ANTI-FOULANT FOR HYDROCARBON FEED STREAMS Richard J. Lee, Park Forest, 11]., assignor to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing. Filed Apr. 19, 1966, Ser. No. 543,510 Claims. (Cl. 208-48) ABSTRACT OF THE DESCLOSURE A method for inhibiting the deposition of fouling materials on equipment surfaces caused by liquid hydrocarbons passing through the equipment at elevated temperatures, which method includes incorporating into the liquid hydrocarbons a small amount of an alkenylsuccinimide derivative of polyamino urea. An anti-foulant material of this invention is conveniently formed by first reacting a polyalkylene amine (polyamine) with urea to form polyarnino urea and then reacting the resulting polyamino urea with a mono-alkenyl substituted succinic anhydride.

This invention relates to the treatment of refinery feed stream hydrocarbons and more particularly pertains to the treatment of hydrocarbon feed streams which have a tendency to form equipment-fouling deposits when heated to a temperature above about 300 F. before subjecting the feed streams to refinery processes including separation processes, upgrading processes and hydrocarbon conversion processes. More specifically, the invention relates to a method for inhibiting, to a substantial extent, the propensity of said hydrocarbon feed streams to form fouling materials such as gums, sediment and similar deposit formers during and after preheating.

In many refinery processes hydrocarbon streams both unrefined and pantially refined hydrocarbons are preheated before being subjected to liquid and/or vapor phase processing. For example, crude petroleum is preheated by indirect heat exchange With product stream and then subjected to final preheating in a furnace before charging to a pipe still for the separation and recovery of various petroleum fractions. Likewise, topped crude is preheated before being subjected to vacuum distillation for the separation and recovery of hydrocarbon fractions of said topped crude. Other unrefined liquid hydrocarbon streams such as natural gas liquids are also preheated before being subjected to refinery processes. Partially refined liquid hydrocarbons such as virgin gas oil, gas oil from vis-breaking, gas oil from coking, light gas oil, virgin naphtha, light and heavy naphtha fractions from pipe still distillation, paraffin distillates, cycle oil from catalytic cracking, coker naphtha, and other such partially refined liquid hydrocarbons are preheated before being subjected to such hydrocarbon conversion processes as thermal cracking, catalytic cracking, thermal reforming, catalytic reforming and other conversion processes. In addition, preheating is employed before liquid hydrocarbon feed streams are subjected to hydrocarbon enrichment or upgrading processes as absorption enrichment of lean oil and/ or stripping processes. For these hydrocarbon separation processes, hydrocarbon enrichment processes and hydrocarbon conversion processes, the unrefined and partially refined liquid hydrocarbon feeds are preheated to temperatures over a Wide range depending on the temperature requirements of further processing and depending upon the physical phase involved in the further processing such as liquid phase, vapor phase or a combination of liquid and vapor phases. In general, the various preheating temperatures are within the range of 300 to 1500 F.

It is recognized in petroleum refining that the various "ice refinery feed streams would present fewer problems with respect to fouling of heating surfaces and fouling of process stream filters, generally iu-line filters, provided that these feed streams had not been contacted with oxygen, especially air. Contact with air might be avoided when petroleum fractions and process hydrocarbon fractions are immediately charged to further separation; upgrading and/or conversion processes. To do so would require all refinery operations to be conducted on a totally continuous basis. Such total continuous refining is not feasible and various liquid hydrocarbon streams must be held in storage before they are further used in other refinery processes. Even continuous refinery operation would not prevent air contact with crude petroleum or other crude hydrocarbons such as natural gas liquids, for these crude hydrocarbons cannot be produced and transported to refineries without contact with air. Since these air contacted sources of crude hydrocarbons do have the tendency to form gums and/ or sediments upon preheating for use in refinery processes and use even in a totally continuous refinery operation, would still present the problems of fouling heating surfaces and in-line filters.

Blanketing of unrefined and partially refined liquid hydrocarbons with inert gas such as nitrogen has been proposed to partially alleviate the problems encountered by fouling of heating surfaces of heat exchangers during preheating steps and the after-fouling by preheated liquid hydrocarbons of filtering devices installed to prevent undesirable suspended gurns, sediments, etc. from entering refinery processes. Certain chemical compounds and mixtures of chemical compounds have been proposed as additives for the unrefined and partially refined liquid hydrocarbons as anti-foulant additives to reduce the tendency for gum and/or sediment formation during preheating in heat exchangers beyond that fouling reduction achieved by inert gas blanketing of stored liquid hydrocarbons. Most of the commercially available anti-foulants are propriety compositions sold under various trade names, trademarks and grade marks. Consequently, their precise chemical composition cannot be readily ascertained.

A class of new anti-foulants has been discovered which can be used in small amounts as additives for unrefined and partially refined liquid hydrocarbons which have a propensity for depositing fouling materials such as gums and/or sediments upon being heated to a temperature above 300 F., in the range of 300 to 1500 R, which anti-foulant additives inhibit and prevent, to a substantial extent, the fouling of heat exchange surfaces, piping, valves, process stream filters etc., by the gum and/0r sediments which would normally be formed. The class of anti-foulants for use in the method of this invention in said unrefined and partially refined liquid hydrocarbons to be preheated are reaction products obtained by reacting a polyalkylene amine with urea employing these reactants in the ratio of about two moles of polyalkylene amine for each mole of urea to form a polyamino urea which is then reacted with alkenylsuccinic anhydride as described hereinafter. By polyalkylene amine is meant those polyamines having the formula wherein x is an integer of from 2 to about 10, R is hydrogen or a lower alkyl hydrocarbon substituent and alkylene is a lower alkylene, i.e. divalent, open chain, hydrocarbon group having from 1 to 8 carbon atoms. Individual polyalkylene amine compounds may be used or mixtures of various such polyalkylene amines may be employed. Such polyalkylene amines include methylene amine, ethylene amines, propylene amines, butylene amines, pentylene amines, hexylene amines, heptylene amines octylene amines, and other polymethylene amines 3 which contain from 2 to alkylene groups and 3 to 11 nitrogens.

Specific examples of such polyalkylene amines include diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine, heptaethylene octamine, dipropylene triamine, tripropylene tetramine, tetrapropylene pentamine, dibutylene triamine, tributylene tetramine, tetrabutylene pentamine, dimethylene triamine, trimethylene tetramine, tetramethylene pentamine, pentamethylene hexamine, di(heptamethylene) triamine, di (trimethylene) triamine, decaethylene hendecarnine, decamethylene hendecamine, N ,N -dimethyl diethylene triamine, N ,N -dimethyl tetraethylene pentamine, N ,N diethyl tetraethylene pentamine, dipentylene triamine, trihexylene tetramine, tetraheptylene pentamine, trioctylene tetramine, and tetrapentylene pentamine among others.

The foregoing polyalkylene amines where R is hydrogen are generally prepared by reacting an alkylene dihalide such as methylene dichloride, ethylene dichloride, propylene dichlorides, butylene dichlorides, pentylene dichlorides; hexylene dichlorides, heptylene dichlorides and octylene dichlorides with ammonia. Where R is lower alkyl i.e. methyl, ethyl, propyl butyl, the alkylene dichloride-ammonia reaction product can be further reacted with the appropriate lower alkyl chloride.

The polyamino ureas of this invention are formed according to the following reaction equation where tetraethylene pentarnine, illustrative of the polyalkylene amine reactant, and urea react in a 2:1 mole ratio.

The resulting polyamino urea has the ten amino groups and the eight ethylene groups. There are also present in the polyamino urea product other polyamino ureas similar to that illustrated wherein the carbamide groups are from secondary amino nitrogens other than those shown and polyamino urea such as illustrated by the following:

For the purpose of discussion of this invention the class of polyamino urea is defined as reaction product of two moles of polyalkylene amine with one mole urea.

The polyamino urea reaction product of two moles polyalkylamine with one mole urea is prepared by conducting the reaction with or without a reaction diluent, preferably without, at a temperature in the range of 200 to 500 F. As hereinhefore indicated the reaction is complex not only because of the different types of polyamino urea products which form at one time but also because of additional side reactions, for example polymerization of monosubstituted urea and biuret formation. The complexity of the condensation reaction between two moles of polyalkylene amine with one urea can be illustrated by the following data in Table I obtained from the reaction of two moles tetraethylene pentamine with one mole urea at the designated temperatures for two hours.

TABLE I Reaction Product Properties Example Reaction No. Tempcra- Percent Percent Basic SSU Visture N -I0tal N-B asic N/Total cosity at 1 250 31. 78 22. 7 72 93 300 31 43 20. 4 67 3 350 29. 83 18. ll (i1 96 4 400 29. 61 17. 5 59 106 1 Ratio Percent N-Basic/Percent: N-Total X 100.

TABLE II.RELATIVE DENSITIES OF CHARACTERISTIC POLYAIWINO UREA ABSORPTION Product of IR Frequencies (em.-

The increasing absorbance of frequencies 1695, 1492, and 1270 cm.- are due to uramine concentration buildup as the reaction temperature is increased. Similarly, the decreasing absorbance of frequencies 1607, 1560 and 1330 cm. are due to the disappearance of reactants. Only two of the six frequencies are not known: 1492 cm.- and 1330 cm. The assignment of 1695 cm. and '1270 cm.- as secondary amide bonds C=O of Amide I and Amide III bonds respectively) and that of 1607 cm.- and 1560 cm. as primary amide bonds (NI-I of Amide II) are conventional.

Viscosity might be used to determine the extent of completion of the condensation reaction producing the poly amino urea. However, as indicated in Table III, viscosity of reaction product does not depend on length of time of reaction. The four reactions (Examples 5, 6, 7 and 8) all used two moles tetraethylene pentamine and one mole urea and the reactions were carried out at 300 F. for the length of time indicated.

ON TIME Example No. Reaction Time, Hours SSU Viseg sity at 210 However, more constant viscosity values (SSU at 210 F.) are obtained when the reactants are combined at an elevated temperature. This is shown in Table IV for Examples 9, 10, 11 and 12 wherein the reactants are combined at two different temperatures: 180 F. and 300 F. and then reacted at 400 F. In these examples the size of the reaction mixture is indicated as one mole batch and five mole batch which mean that 2 moles of tetraethylene pentamine and one mole of urea are reacted in a one mole batch and ten moles of tetraethylene pentamine and five moles of urea are reacted in a five mole batch.

TABLE IV.-EFFECT OF CHARGE TEMPERATURE Charge Example No. SSU Viscosity Temperature Size at 210 F. 7

One mole batch 76 Five mole hatch. 77 300 One rnole batch 81 300 Five mole batch 80 Thorough mixing of urea with the polyalkylene amine to prevent agglomeration of urea and gradual heating of the mixture from 180 to 220 F. to reaction temperature, preferably in the range of 375 to 425 F., produces polyamino ureas of higher viscosity and higher nitrogen content. This is illustrated by the data in Table V from Examples 13, 14, 15, 16, and 17 wherein tetraethylene pentamine (TEPA) and urea are the reactants in a 2:1 mole ratio, the reactants are combined at 180 F. in all but Example 17 where the reactants are combined at ambient temperature (about 7578 F.), different orders of combining the reactants, ditferent degrees of mixing the combined reactants and different periods of heating up to reaction temperature of 400 F. were employed.

tion of solid or semi-solid sediment, and/or gums in process equipment.

The following example illustrates the preparation of the alkenyl succinic anhydride derivative of the poly amino urea for use in the method of this invention.

Example 18 TABLE V.MIXING EFFECT Time, hours Product Example No. Order of Addition Degree of Mixing Heat-up Reaction PercentN SSU Viscosity at 210 F.

Urea to TEPA 5 2 65.8 TEPA to urea V 5 8 29 61.0 is do 1.25 6 27.6 58.0 is do ilrl 5 8 28 56.0 17 S1351? TEPA and urea Very vigorous 5 5 32 105 It is preferred to first slurry the urea in a portion of anhydride dissolved in a mixture of 860 molecular weight the polyalkylene amine and add this slurry to the repolybutene and solvent extracted SAE 5W oil. Thus mainder of the polyalkylene amine heated to 180 to 220 5.4 moles of the polybutenyl succinic anhydride are F. with vigorous mixing and maintain vigorous mixing charged. Also charged to the kettle are 339 gallons of at least during heat-up to reaction temperature which 30 additional solvent extracted SAE 5W oil. The resulting heat-up period is preferably 3 to 5 hours. mixture is heated to 250-260 F. while blanketed with Although in all of the foregoing seventeen illustrated an inert gas such as nitrogen. Thereafter 122 gallons examples tetraethylene pentamine and urea were the re- (1095 pounds or 2.7 pound moles) of a polyamino urea actants employed, other specific polyalkylene amines of obtained by reacting two moles tetraethylene pentamine the types hereinbefore specifically named or mixtures 35 with one of urea are pumped in over 60 minutes. This thereof, can be used in the same reactions. Useful polydi(pentamino) urea has a nitrogen content of about 30.5, amino ureas include those obtained from diethylene tria total base number (MgKOI-l/ gram) of about 815, a amine, triethylene tetramine, trimethylene tetramine, SSU viscosity at 210 F. of about 72, a gravity of about tetramethylene pentamine, dipropylene triamine and tri- 9.0 and a 365 F. flash point. The reaction mixtures is Propylene tetramine, heated to 300 F. and held at this temperature for about The polyamino ureas, reaction product of two moles 2 hours while sparging nitrogen through the reaction mixpolyalkylene amine and one mole urea, is employed for ture to aid in the removal of by-product water, about the formation of succinimides through reaction with a 97 pounds. The resulting reaction mixture contains about mono-alkenyl substituted succinic anhydride having as 49 weight percent di(polybutenylsuccinimide) of the diits alkenyl substituent a hydrocarbon group derived from 4.5 (pentamino) urea. Filtration of the reaction mixture genpolyolefin of 30 or more carbon atoms especially polyerally provides a brighter (clearer) product. propylenes and polybutenes of 30 or more carbon atoms. When tetraethylene pentamine is reacted with C and The useful polypropylenes and polybutenes, and hence higher alkenyl substituted succinic acids and/or anhythe alkenyl substituent, have a carbon content in the dride lower temperatures of combining these reactants range of 30 to 200 carbons. The alkenyl substituent of 50 are employed as well as lower initial reaction temperathe monoalkenyl succinic anhydride has a molecular tures and slower rates of addition than are used in Exweight in the range of from 400 to 100,000. The preparaample 18. The lower addition and reaction temperatures tion of such monoalkenylsuccinic anhydrides by reacting and slower addition rates are necessary to prevent exmaleic anhydride and a polypropylene or polybutene of cessive losses of tetraethylene pentamine. said 400 to 100,000 molecular weight range is known.

The alkenylsuccinimide derivatives of the polyamino Example 19 ureas are obtained by reacting, for each mole of monoalkenyl substituted succinic anhydride, 0.4 to 0.7 mole is gi g g p16 i Is g z g 1 3 pound of polyamino urea at 200 to 450 F., preferably 300 to 1 1 1 fi g i b 3 n e avmg a 400 F., and aiding removal of by-product water by the p ar F o a out pound moles the ipentammo urea and 11,825 pounds of SAE SW 011 as use of an inert gas, e.g. nitrogen purge or by passing the reaction diluent The resultin fine d d t inert gas through the reaction mixture. This reaction beclear lioht cololled solufon was a tween monoalkenylsuccinic anhydride and polyamino b a f th .3 l on Percent urea is advantageously carried out in an inert diluent y 61g 0 e lsucclmml e oft e dlpentammo urea such as xylene or preferably a light hydrocarbon lubri- 65 Example 20 eating oil such as solvent extracted SAE 5W oil or white mineral oil or mixtures of these hydrocarbon oils with There are combined 2.7 pound moles of the dipentpolybutene or polypropylenes of the 500 to 100,000 molecamino urea described in Example 18 and 5.4 moles of ular weight range. It is desirable to conduct said suca polybutenyl succinic anhydride having a molecular cinimide reaction with proportions of reactants which will weight of about 3100 as a 50 weight percent solution in provide the succinimide product in concentrations of about equal parts by weight of SAE 5W oil and 3000 from 40 to 60 weight percent when a light hydrocarbon molecular weight polybutene. After about 97 pounds of diluent is used. Such compositions are excellent concenby-product water had been removed at 300 C, and trates for incorporating into unrefined and/or partially sparging with inert gas, e.g., nitrogen, the reaction mixrefined liquid hydrocarbon streams to inhibit the depositure is diluted further with SAE 5W oil, about 1000 pounds, to provide a 50 weight percent solution of the disuccinimide of the dipentamino urea.

The foregoing alkenylsuccinimide derivatives of polyamino ureas have been disclosed as being useful deter- For the investigation of the hydrocarbon feed preheat exchanger fouling problem, a tube temperature of 400 F. and a filter temperature of 500 F. were used for all runs. This approximates typical preheat exchanger temthe tube heats the liquid hydrocarbon to a controlled predetermined temperature. Hot liquid hydrocarbon from the preheater annulus can be further heated to a higher temperature before the hydrocarbon is passed through gent additives for lubricating oils and detergent additives per-atures for many hydrocarbon feed streams. A flow rate for internal combustion engine fuels. The discovery of of 6 pounds per hour was used while maintaining an the use of small amounts of these acylated nitrogenoperating pressure of 150 p.s.i.g. During our investigacontaining derivatives as anti-foulants for unrefined and tion of the fouling problems it was found that tube departially refined liquid hydrocarbons, which have the proposits were not significant and it was not practical to use pensity upon heating at a temperature above 300 F. to 10 tube appearance as a method of evaluation. Accordingly, form gum and/0r sediment formations in the absence the filter pressure drop was used as the most important of the alkenylsuccinic anhydride-polyamino urea addifactor in evaluating these tests. tive, is based on the unusual effect of these compounds During these tests the filter pressure drop was recorded in small amounts, i.e., from 1 to 100 parts per million at 10-minute intervals. It was found that the pressure of the liquid hydrocarbons. The observed unusual effect drop varies exponentially with time and a plot of the log by the use of such small amounts of these compounds is of the filter pressure drop against time gives a straight achieved preferably by the use of such compounds deline. This relationship is expected since plugging of the rived from a substantially aliphatic hydrocarbon substifilter increases velocity, and pressure drop varies with the tuted succinic anhydride wherein the aliphatic hydrocarsquare of the velocity. Thus, high temperature degradabon substituent has been derived from a polyisobutylene tion product accumulation (fouling tendency) may be having an average molecular weight in the range of from compared by :a comparison of the slope of the resulting about 560 to about 5000 and where the amine reactant straight lines. The slope of the straight line is, of course, is tetraethylene pentamine or a mixture of polyalkyl p01ycalculated as (log AP -log AP (T T where AP amines having a nitrogen content corresponding to tetraand T represent filter pressure drop and time respectively ethylene pentamine. The latter mixture of polyethylene for two different time AP measurements during the run. polyamines is an excellent low cost source of the pOly- Comparison of the slope of the various lines can be amine reactant and when used herein in the specification made easier by assigning an arbitrary fouling index claims, tetraethylene pentamine" is intended to include of 1 to the slope of one line and comparing all other both the tetraethylene pentarnine per se and the c mIn6rslopes to it. To best illustrate the anti-fouling effect of cially available polyethylene polyamino having a nitrothe additives tested, the slope of the hydrocarbon having gen Content Corresponding to the tetfaethylene PentamiHB- had no previous air contact is chosen as a base with foul- To illustrate the unusual effect of a small amount of ing ind x of 1, Thus a li ith fouling inde of 2 mean anti-foulant according to this invention, the results Of the slope of the straight line plotted as hereinbefore decomparative screening tests with and without anti-foulant V ribed i twi a g e t a f th hydrocarbon with no additive are employed. These screening tests Were run in air contact, or in other words, the fouling index is twice an Erdco Coker which is normally used for testing coka g t, ing tendencies of distillate fuels. For these screening E i I 21 tests an Erdco Coker Model OZFC is used. This lappa- Xamp e ratus consists essentially of acontinuous flow system with Various oils were subjected to the above coker test two heated sections (preheater tube and heated sintered with and without anti-foulant additive incorporated metal test filter) which associated equipment for contherein. The anti-foulant additive used during these comtrolling and measuring temperature, pressure and flow parative tests was prepared as described in Example 18 rate. A detailed description of the apparatus is given in above. The anti-foulant additive concentrations given are ASTM designation: D-l660-61T. the concentrations of a mixture of the alkenylsuccinimid The experimental screen procedure is conducted by prederivative of polyamino urea and about an equal volume filtering about 10 gallons of the liquid hydrocarbon to of oil as in Examples 18-20 above. The data obtained be used. The liquid hydrocarbon is then pumped conduring these tests are shown in Table VI.

TABLE VI Fouling Index Anti-fouling Fouling Inde Test Test Oil of Test Oil Cone, p.p.m. with Antifoulant A Desulfurizer feed naphtha 0.2 10 0 B Blend: 10% Gas oil. 90% 5.5 40 0.8

kerosene. C Blend: 10% crude oil (de- 4.3 20 2.3

salted), 90% kerosene. D Naphtha 3.9 2.5 1.7 E Kerosene a 2.1 2.5 0.6 F. Distillate 3. 5 5.0 0. 4 G. Kerosene b" 2.9 10 0.4 H Reformer desulfurizer teed 3.0 2.5 0.3

naphtha.

secutively through an in-line filter, a rotameter and 2. Example 22 preheater. In the preheater the test hydrocarbon flows through an annulus enclosing a polished aluminum or This example shows that polyalkylene polyamines carbon steel tube. An electrical heating element inside 65 other t an te rae hylene pentamine may be used in preparing the anti-foulant.

An anti-foulant additive was produced as in Example 18 except that halfof the tetraethylene pentamine (TEPA) was replaced with an equivalent number of moles of pentaethylene hexamine (PEI-IA). A heavy virgin naphthe was subjected to the above coker test. Without additive the naphtha had a fouling index of 5.0. With 2 ppm. of the anti-foulant used in Example 21 the naphtha had a fouling index of 1.1, and also with 2 p.p.m. of the anti-foulant additive described above in this example 9 made from half TEPA and half PEHA the fouling index was 1.1.

Although the present invention has been described with reference to specific examples and specific preferred embodiments thereof, the invention is not to be considered as limited thereto but includes within its scope such modifications and variations as come Within the spirit of the claims.

Having disclosed the invention and exemplified it With respect to the use of typical anti-foulant additive in typical hydrocarbon feed streams, what is claimed is:

1. A method of inhibiting the deposition of fouling materials on the surfaces of equipment by liquid hydrocarbon having a propensity for depositing such materials while being passed through such equipment at temperatures of from 300 to 1500 E, which method comprises incorporating in said liquid hydrocarbon a small amount of an alkenylsuccinimid derivative of polyamino urea.

2. The method of claim 1 wherein said amount is in the range of about 1 to 100 p.p.m. by weight based on said hydrocarbon.

3. The method of claim 1 wherein said liquid hydrocarbon is a petroleum hydrocarbon fraction from catalytic cracking to be subjected to hydrocarbon conversion for gasoline blending stock.

4. The method of claim 1 wherein said liquid hydrocarbon is a partially refined distillate fuel feed for hydrodesulf-urization.

5. The method of claim 1 wherein said liquid hydrocarbon is a naphtha feed for catalytic reforming.

6. The method of claim 1 wherein said liquid hydrocarbon is a gas oil feed for catalytic cracking.

7. The method of claim 1 wherein said liquid hydrocarbon is desalted crude petroleum.

8. The method of claim 1 wherein said liquid hydrocarbon is produced during coking of a heavy petroleum fraction.

9. The method of claim 1 wherein said alkenylsuc cinimid derivative is formed by reacting a polyalkylene amine, said amine having the general formula H 1 (alkyIene ITI)H wherein x is an integer of from 2 to 10, R is selected from the group consisting of hydrogen and lower alkyl hydrocarbon substituents having up to about 8 carbon atoms and alkylene is a divalent open chain hydrocarbon group having from 1 to 8 carbon atoms, with urea in a ratio of about two moles of said amine per mole of urea to form polyamino urea and then reacting said polyamino urea with mono-alkenyl substituted succinic anhydride having as the alkenyl substit-uent a hydrocarbon group derived from polyolefin having at least 30 carbon atoms per molecule.

19. The method of claim 9 wherein said polyalkylene amine reaction with urea is carried out at a temperature in the range of about 200 to 500 F. and said reaction of said polyamino urea with mono-alkenyl substituted succinic anhydride is carried out at a temperature in the range of about 200 to 450 F.

References Cited UNITED STATES PATENTS ABRAHAM RIMENS, Primary Examiner.