Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G9/00—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
  • C10G9/14—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils in pipes or coils with or without auxiliary means, e.g. digesters, soaking drums, expansion means
  • C10G9/16—Preventing or removing incrustation
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F14/00—Inhibiting incrustation in apparatus for heating liquids for physical or chemical purposes
  • C23F14/02—Inhibiting incrustation in apparatus for heating liquids for physical or chemical purposes by chemical means

Definitions

• the present invention relates to novel polyamides, and to compositions containing said additives alone or in combination with other active ingredients for reducing the tendency of a petroleum material (either crude oil or petroleum fractions) to foul heat exchange surfaces (eg heat exchange tubes) when the heated petroleum material is in contact with heat exchange surface.
• the present invention further relates to an improved process for exchanging heat with a hot petroleum material through a heat exchange surface. The process is particularly applicable to heating petroleum materials by contact with a heat exchange material.
• Heat transfer through heat exchangers is often reduced during operation due to the fouling of the tube walls by deposition from the process stream. Fouled exchangers then operate at lower. efficiencies and this often results in throughput reductions and frequent shutdowns for cleaning.
• the inorganic deposits are predominantly salts of iron (corrosion products), sodium (salt in the water associated with crude oil and from caustic soda injection) and calcium and magnesium (hardness salts in desalter water).
• a high proportion of these salts originate from the desalter where salt is extracted from the crude oil by washing with water.
• the crude oil leaving the desalter can contain as much as 0.3X wt dissolved water.
• Anti-foulants are usually blends of additives in an organic solvent with injection levels in the range 5 - 30 ppm on crude. Because fouling is so complex and covers several different types and mechanisms, the active ingredients of anti-foulants can be very varied. Examples of anti-foulant types include dispersants, detergents, metal co-ordinators, anti-oxidants, film formers, corrosion inhibitors and anti-polymerants.
• Our British Patent Specification 1564757 discloses and claims a method for evaluating the fouling tendency of a heated liquid crude oil or petroleum fraction which method comprises heating the liquid, adding to it a solution or suspension containing one or more inorganic and/or organic foulants to give an enhanced concentration of foulant in the liquid, passing the resulting liquid through a heated tubular test section and measuring over a period of time the increase in pressure drop across the test section and/or the decrease in temperature of the liquid at the outlet of the test section.
• the fouling produced in this method is similar to that produced in refinery heat exchangers, being a mixture of organic and inorganic deposits.
• JFTOT Jet Fuel Thermal Oxidation Test
• the present invention provides novel polyamides of the formula given below.
• liquid polyamide of general formula R CONH (CH 2 CH 2 NH) n OCR (I) wherein R is an alkyl or alkenyl group containing 10 to 22 carbon atoms, and n is an integer in the range 1 to 4.
• liquid polyamide we mean a polyamide which is liquid at 25°C and atmospheric pressure.
• Oil soluble compounds having the above formula are useful components of anti-fouling additives either alone as a solution in a solvent miscible with the petroleum material, or in admixture with other active materials.
• the oil soluble polyamides may have an anti- fouling action on their own in certain situations, which may be enhanced by the addition of other materials. In other situations the polyamides alone may increase fouling, but in combination with other additives will reduce fouling as explained below.
• n 2
• novel polyamides may be prepared by reacting together a carboxylic acid of formula RCOOH and a polyamine of formula NH 2 (CH 2 CH 2 NH) n H.
• carboxylic acids which are liquid at 25°C and atmospheric pressure.
• Suitable saturated carboxylic acids are dodecanoic acid (lauric acid), hexadecanoic acid (palmitic acid).
• Suitable polyamines include diethylene triamine, triethylene tetramine and tetraethylene pentamine.
• the polyamide may be prepared by heating the acid and the polyamine together in solution eg in a light aromatic solvent in a molar ratio in the range 1:1 to 3:1, preferably 1.8:1 to 2.2:1.
• suitable temperatures are those in the range 110° to 150°C.
• the reaction is preferably continued until the quantity of water released corresponds to that expected from the stoichiometry.
• the polyamide is suitable for use as anti-fouling additive where fouling is chiefly due to organic contaminants, e.g. in heat exchangers associated with visbreaking units.
• the polyamide is preferably employed in combination with an emulsifier.
• the polyamide alone may lead to an increase in fouling.
• an anti-fouling additive composition comprising a polyamide as hereinbefore defined and an oil soluble emulsifier.
• the preferred emulsifiers are those of general formula: R'COOCH 2 (CHOH) m CH 2 0H wherein R' is an alkyl or alkenyl group containing 10 - 22 carbon atoms and m is an integer in the range 1 to 4 inclusive.
• the emulsifiers are partial esters of polyhydric alcohols and carboxylic acids.
• Suitable polyhydric alcohols include mannitol, xylitol and erythritol and, preferably, sorbitol.
• the preferred emulsifier is sorbitan monooleate. Any other emulsifier used is preferably as oil soluble as sorbitan monooleate.
• the polyamide and the emulsifier are suitably present in a weight ratio in the range 20:1 to 1:1, preferably 7:1 to 11:1 for optimum properties.
• the polyamide is preferably employed in combination with an anti-oxidant.
• an anti-fouling additive composition comprising a polyamide and a hindered phenolic anti-oxidant.
• Suitable hindered phenolic anti-oxidants include 2,6-di-tert. butyl phenol, 2,6-di-tert.butyl-4-methyl phenol and 4,4'-methylene bis (2,6-di-tert.butyl phenol).
• the polyamide and the anti-oxidant are suitably present in a weight ratio in the range 4:1 to 1:4, preferably 0.5 to 1.5, eg 1:1.
• the film-forming agent used in the present invention is a material which acts as a corrosion inhibitor by forming an impermeable film on a metal surface, thereby preventing corrosive substances from reacting the metal itself.
• Such film-forming agents are well-known materials.
• Suitable film-forming agents include amines eg long chain amines and amine carboxylates.
• the preferred agent is morpholine.
• the relative proportions may be the same as for polyamide/ antioxidant mixtures.
• a process for exchanging heat with a hot petroleum material containing an anti-fouling additive through a heat exchange surface characterised in that the anti-fouling additive comprises a polyamide of formula (I).
• the antifouling additive may consist only of the polyamide in certain cases, while where inorganic fouling is present the addition of emulsifier may be necessary. Based on the disclosure of this specification however the skilled person will be easily able to produce a suitable anti-fouling additive containing polyamide.
• the process is particularly applicable to heating petroleum materials.
• the anti-fouling additive is preferably stored and used in the form of a solution in a hydrocarbon solvent eg an aromatic hydrocarbon solvent such as toluene or xylene.
• a hydrocarbon solvent eg an aromatic hydrocarbon solvent such as toluene or xylene.
• concentration of the. polyamide in the solution may for example be in the range 20-60% by weight.
• methanol a minor proportion of methanol into the solution for example 0.1 to 0.4 parts by weight of methanol per part by weight of hydrocarbon solvent.
• the optimum concentration will depend on the process to which the petroleum material is subjected. In crude oil distillation concentrations of additive solution of 20-30 ppm are usually used, typically corresponding to 8-12 ppm of polyamide. In visbreaking concentrations of additive solution of 50 ppm are more usual, typically corresponding to over 20 ppm of polyamide.
• the product was a yellowish brown liquid containing 40% by weight polyamide.
• Example 1 The polyamide made in Example 1 was tested for crude distillation unit duty in the Sunbury Fouling Rig (SFR) as described in GB 1564757 on a temperature basis and the JFTOT as described in ASTM Test D-3241-74T.
• SFR Sunbury Fouling Rig
• Example 2 was repeated using as antifoulant a mixture of the polyamide made in Example 1 and sorbitan monooleate (an oil soluble emulsifier sold under the trade name Span 80) in the weight ratio (polyamide:emulsifier) of 4:1. The results are given in Table 1.
• Example 2 was repeated but using sorbitan monooleate alone as anti-foulant (Test A), or various commercially available anti-foulants (identified as AF1 to AF4 respectively (Tests B - E).
• the polyamide of Example 1 was mixed with an antioxidant (2,6-di-tert-butyl phenol) in a weight ratio of 1:1 and was tested in the JFTOT rig to determine its suitability for use with a desulphuriser feedstock and compared with several commercially available additives.
• Example 4 was repeated using a mixture of the polyamide of Example 1 and morpholine (a film forming agent) in the weight ratio 1:1.
• Example 3 was repeated using various commercially available anti-fouling additives identified respectively as AF4, AF2, AF5, AF6 and AF1. The results are given in Table 2.
• Example 1 The polyamide of Example 1 was tested in a visbreaking pilot plant to determine its suitability in reducing visbreaking coking.
• Example 6 was repeated using commercially available antifouling additives identified as AF2, AF7 and AF4 respectively. The results are given in Table 3.
• the polyamide was the most effective.

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• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Thermal Sciences (AREA)
• Physics & Mathematics (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Polyamides (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

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Citations (6)

• 1983
  • 1983-02-15 AU AU11436/83A patent/AU1143683A/en not_active Abandoned
  • 1983-02-18 EP EP83300826A patent/EP0087277A3/fr not_active Ceased

Patent Citations (6)

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