TECHNICAL FIELD

[0001] The present disclosure relates to the field of hydrocarbon refining. In particular, it pertains to antifouling formulations for reducing fouling in heat exchangers. The present disclosure further relates to a process for preparing the antifouling formulations and the method of inhibiting fouling in a hydrocarbon medium.

BACKGROUND

[0002] The accumulation of unwanted materials on heat transfer surfaces is called fouling. It is a dynamic phenomenon which changes with time and may have a significantly negative impact on the thermal and mechanical performance as well as the operational efficiency of units, such as crude preheat exchangers, furnaces, hydrotreater exchangers, reactor beds, fluid catalytic cracking unit (FCCU) slurry exchangers and thermal cracking process exchangers.

[0003] Multiple factors impact fouling including crude type, equipment design, flow rates, temperature, unit’s operational severity, and fluid characteristics. All these lead to energy loss and increasing maintenance cost, reduced equipment lifetime, throughput loss, and safety problems. Hence, modern refineries strive for reliability and processing flexibility, with longer run lengths and minimal equipment fouling.

[0004] The unwanted materials known as fouling deposits can be scale, suspended solids, and insoluble salts. Broadly, the fouling deposits can be categorized into two major types, inorganic and organic. In the case of inorganic fouling, corrosion of process equipment will form ferrous- based corrosion products such as iron sulfide or ferric oxide which will deposit in exchangers, mainly in areas with lower velocities. Solid inorganic contaminants such as sand and silt can also deposit in the exchanger and cause hydraulic or thermal obstructions. Organic fouling in a crude unit results from the precipitation of organic components, such as, asphaltenes, high molecular weight hydrocarbons which become insoluble in the system. The asphaltenes become unstable because of the blending of incompatible crudes and get precipitated out due to high heating temperatures of crudes. Further, the asphaltenes and other heavier organic molecules are known to thermally degrade to coke when exposed to high heater tube surface temperatures.

[0005] Organic fouling is usually caused by polymerization reactions initiated by fouling precursors that are present in crude. Two polymerization mechanisms have been identified, “free radical” and“non-free radical” reactions. The most common mechanism is“free radical” polymerization, where unsaturated components, such as olefins and diolefins, react to form longer chain molecules. The molecule chain length increases to the point that solubility is exceeded, and deposition occurs. Non-free radical polymerization mechanism occurs mainly as a result of condensation reactions involving components such as carboxylic acid and nitrogen compounds etc. To properly control fouling, the differences between these two categories must be thoroughly understood and accounted for when identifying the fouling mechanisms.

[0006] Fouling of refinery process equipment is a common problem resulting in severe economic penalties due to energy loss and has significant safety concerns. Several antifoulant formulations comprising antifouling formulations comprising of ionic surfactants based on alkylbenzene sulfonates are known in the literature, such as US 2976211, US 3080280, US 5110997, and WO 2017141077, etc. However, a single antifouling formulation working on all types of crudes, crude blends, short residue and other refinery streams and units (e. g., diesel hydrodesulfurization, i.e. DHDS unit) heat exchangers and, providing an efficient reduction in fouling is very scarce in the prior art. Therefore, in light of the huge losses due to fouling worldwide and scarce availability of antifouling formulations, efficient antifoulant formulations are direly required.

SUMMARY

[0007] In an aspect of the present disclosure there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid; (b) at least one aromatic hydrocarbon; (c) at least one diluent; (d) polyisobutylene succinic anhydride; and (e) at least one alkyl amine.

[0008] In another aspect of the present disclosure there is provided a process of preparing the antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid; (b) at least one aromatic hydrocarbon; (c) at least one diluent; (d) polyisobutylene succinic anhydride; and (e) at least one alkyl amine, the process comprising: (a) contacting at least one ammonium salt of linear alkyl benzene sulphonic acid, at least one aromatic hydrocarbon, at least one diluent, polyisobutylene succinic anhydride; and, at least one alkyl amine to obtain a first mixture; and (b) processing the first mixture to obtain the antifoulant formulation.

[0009] In yet another aspect of the present disclosure, there is provided a method of inhibiting fouling in a liquid hydrocarbon medium, the method comprising contacting the antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid; (b) at least one aromatic hydrocarbon; (c) at least one diluent; (d) polyisobutylene succinic anhydride; and (e) at least one alkyl amine, and the liquid hydrocarbon medium in the preheat exchangers of crude and short residue.

[0010] These and other features, aspects, and advantages of the present subject matter will be better understood concerning the following description and appended claims. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to be used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF DRAWINGS

[0011] The detailed description is described concerning the accompanying figure. In the figure, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and components.

[0012] Figure 1 illustrates the graphical representation of the evaluation of Crude- 1 against antifoulant formulation, in accordance with an implementation of the present disclosure.

DETAILED DESCRIPTION

[0013] Those skilled in the art will be aware that the present disclosure is subject to variations and modifications other than those specifically described. It is to be understood that the present disclosure includes all such variations and modifications. The disclosure also includes all such steps, features, compositions, and compounds referred to or indicated in this specification, individually or collectively and any and all combinations of any or more of such steps or features.

Definitions

[0014] For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are collected here. These definitions should be read in the light of the remainder of the disclosure and understood as by a person of skill in the art. The terms used herein have the meanings recognized and known to those of skill in the art, however, for convenience and completeness, particular terms and their meanings are set forth below.

[0015] The articles“a,”“an” and“the” are used to refer to one or more than one (i.e., to at least one) of the grammatical object of the article.

[0016] The terms“comprise” and“comprising” are used in the inclusive, open sense, meaning that additional elements may be included. Throughout this specification, unless the context requires otherwise the word“comprise”, and variations, such as“comprises” and“comprising”, will be understood to imply the inclusion of a stated element or step or group of elements or steps but not the exclusion of any other element or step or group of elements or steps.

[0017] The term“including” is used to mean“including but not limited to”.“Including” and “including but not limited to” are used interchangeably.

[0018] The term“between” should be understood as being inclusive of the limits.

[0019] The term“API” is a commonly used index of the density of crude oil or refined products. API stands for the American Petroleum Institute, which is the industry organization that created this measure.

[0020] The term“ambient” in the present disclosure refers to a temperature in the range of 25 °C to 37 °C.

[0021] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the preferred methods, and materials are now described. All publications mentioned herein are incorporated herein by reference.

[0022] Molar equivalent ratios of components may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a temperature range of about 40°C to about 50°C should be interpreted to include not only the explicitly recited limits of about 40°C to about 50°C, but also to include sub-ranges, such as 45°C to 48°C, and so forth, as well as individual amounts, including fractional amounts, within the specified ranges, such as 42.2°C, 40.6°C, and 49.3°C, for example.

[0023] The present disclosure is not to be limited in scope by the specific embodiments described herein, which are intended for the purposes of exemplification only. Functionally equivalent products, compositions, and methods are clearly within the scope of the disclosure, as described herein.

[0024] As discussed in the background section, there are multiple factors impacting fouling, which lead to energy loss and increased maintenance cost, reduced equipment lifetime, throughput loss, and safety problems. Hence, in modem refineries, efficient antifoulant formulations with longer run length are required. In order to combat the above-mentioned issues, the present disclosure provides antifouling formulations comprising (a) at least one ammonium salt of linear alkyl benzene sulphonic acid; (b) at least one aromatic hydrocarbon; (c) at least one diluent; (d) polyisobutylene succinic anhydride; and (e) at least one alkyl amine. The present antifoulant formulations, when evaluated for a series of crudes and vacuum residue using refinery fouling process simulator (RFPS) showed excellent results compared to control experiments without the antifoulant formulation.

[0025] In an embodiment of the present disclosure, there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid; (b) at least one aromatic hydrocarbon; (c) at least one diluent; (d) polyisobutylene succinic anhydride; and (e) at least one alkyl amine.

[0026] In an embodiment of the present disclosure, there is provided an antifoulant formulation as described herein, wherein the at least one ammonium salt of linear alkyl benzene sulphonic acid to the at least one aromatic hydrocarbon weight ratio is in the range of 1: 1 - 10: 1.

[0027] In an embodiment of the present disclosure, there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid; (b) at least one aromatic hydrocarbon; (c) at least one diluent; (d) polyisobutylene succinic anhydride; and (e) at least one alkyl amine, wherein the at least one ammonium salt of linear alkyl benzene sulphonic acid to the at least one aromatic hydrocarbon weight ratio is in the range of 1: 1 - 10: 1.

[0028] In an embodiment of the present disclosure, there is provided an antifoulant formulation as described herein, wherein the at least one ammonium salt of linear alkyl benzene sulphonic acid to the polyisobutylene succinic anhydride weight ratio is in the range of 0.25: 1 - 10: 1. In another embodiment of the present disclosure, the at least one ammonium salt of linear alkyl benzene sulphonic acid to the polyisobutylene succinic anhydride weight ratio is in the range of 0.25 : 1 - 4: 1. In yet another embodiment of the present disclosure, the at least one ammonium salt of linear alkyl benzene sulphonic acid to the polyisobutylene succinic anhydride weight ratio is in the range of 0.25: 1 - 2.5: 1.

[0029] In an embodiment of the present disclosure, there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid; (b) at least one aromatic hydrocarbon; (c) at least one diluent; (d) polyisobutylene succinic anhydride; and (e) at least one alkylamine, wherein the at least one ammonium salt of linear alkyl benzene sulphonic acid to the polyisobutylene succinic anhydride weight ratio is in the range of 0.25: 1 - 10: 1.

[0030] In an embodiment of the present disclosure, there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid; (b) at least one aromatic hydrocarbon; (c) at least one diluent; (d) polyisobutylene succinic anhydride; and (e) at least one alkylamine, wherein the at least one ammonium salt of linear alkyl benzene sulphonic acid to the polyisobutylene succinic anhydride weight ratio is in the range of 0.25: 1 - 4: 1.

[0031] In an embodiment of the present disclosure, there is provided an antifoulant formulation as described herein, wherein the at least one ammonium salt of linear alkyl benzene sulphonic acid to the at least one alkyl amine weight ratio is in the range of 1 : 1 - 20: 1.

[0032] In an embodiment of the present disclosure, there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid; (b) at least one aromatic hydrocarbon; (c) at least one diluent; (d) polyisobutylene succinic anhydride; and (e) at least one alkylamine, wherein the at least one ammonium salt of linear alkyl benzene sulphonic acid to the at least one alkyl amine weight ratio is in the range of 1: 1 - 20: 1.

[0033] In an embodiment of the present disclosure, there is provided an antifoulant formulation as described herein, wherein the at least one ammonium salt of linear alkyl benzene sulphonic acid to the at least one diluent weight ratio is in the range of 0.05: 1 - 0.4: 1.

[0034] In an embodiment of the present disclosure, there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid; (b) at least one aromatic hydrocarbon; (c) at least one diluent; (d) polyisobutylene succinic anhydride; and (e) at least one alkylamine, wherein the at least one ammonium salt of linear alkyl benzene sulphonic acid to the at least one diluent weight ratio is in the range of 0.05:1 - 0.4: 1.

[0035] In an embodiment of the present disclosure, there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid; (b) at least one aromatic hydrocarbon; (c) at least one diluent; (d) polyisobutylene succinic anhydride; and (e) at least one alkylamine, wherein the at least one ammonium salt of linear alkyl benzene sulphonic acid to the at least one aromatic hydrocarbon weight ratio is in the range of 1 : 1 - 10: 1, the at least one ammonium salt of linear alkyl benzene sulphonic acid to the polyisobutylene succinic anhydride weight ratio is in the range of 0.25: 1 - 10: 1, the at least one ammonium salt of linear alkyl benzene sulphonic acid to the at least one alkyl amine weight ratio is in the range of 1: 1 - 20: 1, and the at least one ammonium salt of linear alkyl benzene sulphonic acid to the at least one diluent weight ratio is in the range of 0.05:1 - 0.4: 1.

[0036] In an embodiment of the present disclosure, there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid; (b) at least one aromatic hydrocarbon; (c) at least one diluent; (d) polyisobutylene succinic anhydride; and (e) at least one alkylamine, wherein the at least one ammonium salt of linear alkyl benzene sulphonic acid to the at least one aromatic hydrocarbon weight ratio is in the range of 1: 1 - 10: 1, the at least one ammonium salt of linear alkyl benzene sulphonic acid to the polyisobutylene succinic anhydride weight ratio is in the range of 0.25: 1 - 4: 1, the at least one ammonium salt of linear alkyl benzene sulphonic acid to the at least one alkyl amine weight ratio is in the range of 1: 1 - 20: 1, and the at least one ammonium salt of linear alkyl benzene sulphonic acid to the at least one diluent weight ratio is in the range of 0.05:1 - 0.4: 1.

[0037] In another embodiment of present disclosure, there is provided an antifoulant formulation as described herein, wherein the at least one ammonium salt of linear alkyl benzene sulphonic acid has a weight percentage in the range of 5-20 % with respect to the formulation; the at least one aromatic hydrocarbon has a weight percentage in the range of 2-5 % with respect to the formulation; the at least one diluent has a weight percentage in the range of SO BS % with respect to the formulation; the polyisobutylene succinic anhydride has a weight percentage in the range of 5-20 % with respect to the formulation; the at least one alkyl amine has a weight percentage in the range of 1-5 % with respect to the formulation.

[0038] In an embodiment of the present disclosure, there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid having a weight percentage in the range of 5-20 % with respect to the formulation; (b) at least one aromatic hydrocarbon having a weight percentage in the range of 2-5 % with respect to the formulation; (c) at least one diluent having a weight percentage in the range of 50-85 % with respect to the formulation; (d) polyisobutylene succinic anhydride having a weight percentage in the range of 5-20 % with respect to the formulation; and (e) at least one alkyl amine having a weight percentage in the range of 1-5 % with respect to the formulation.

[0039] In another embodiment of present disclosure, there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid having a weight percentage in the range of 10-20 % with respect to the formulation; (b) at least one aromatic hydrocarbon having a weight percentage in the range of 2.5-3.5 % with respect to the formulation; (c) at least one diluent having a weight percentage in the range of 60-85 % with respect to the formulation; (d) polyisobutylene succinic anhydride having a weight percentage in the range of 5-15 % with respect to the formulation; and (e) at least one alkyl amine having a weight percentage in the range of 1-3 % with respect to the formulation.

[0040] In another embodiment of present disclosure, there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid having a weight percentage in the range of 10 % with respect to the formulation; (b) at least one aromatic hydrocarbon having a weight percentage in the range of 3 % with respect to the formulation; (c) at least one diluent having a weight percentage in the range of 75 % with respect to the formulation; (d) polyisobutylene succinic anhydride having a weight percentage of 5 % with respect to the formulation; and (e) at least one alkyl amine having a weight percentage in the range of 3 % with respect to the formulation.

[0041] In another embodiment of present disclosure, there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid having a weight percentage in the range of 10 % with respect to the formulation; (b) at least one aromatic hydrocarbon having a weight percentage in the range of 3 % with respect to the formulation; (c) at least one diluent having a weight percentage in the range of 75 % with respect to the formulation; (d) polyisobutylene succinic anhydride having a weight percentage of 10 % with respect to the formulation; and (e) at least one alkyl amine having a weight percentage in the range of 3 % with respect to the formulation.

[0042] In another embodiment of present disclosure, there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid having a weight percentage in the range of 20 % with respect to the formulation; (b) at least one aromatic hydrocarbon having a weight percentage in the range of 3 % with respect to the formulation; (c) at least one diluent having a weight percentage in the range of 65 % with respect to the formulation; (d) polyisobutylene succinic anhydride having a weight percentage of 10 % with respect to the formulation; and (e) at least one alkyl amine having a weight percentage in the range of 2 % with respect to the formulation.

[0043] In another embodiment of present disclosure, there is provided an antifoulant formulation as described herein, wherein the at least one aromatic hydrocarbon is naphthalene, wherein naphthalene may be optionally substituted with Ci- ₆ alkyl, Ci- ₆ haloalkyl, C2-6 alkenyl, C2-6 alkynyl, Ci- ₆ alkoxy, C3-6 cycloalkyl, or C5-6 aryl. In yet another embodiment of the present disclosure, the at least one aromatic hydrocarbon is naphthalene.

[0044] In another embodiment of present disclosure, there is provided an antifoulant formulation as described herein, wherein the at least one diluent is selected from the group consisting of light cycle oil, kerosene, aromatic-rich hydrocarbon diluents, diesel, mineral turpentine oil (MTO), and combinations thereof. In another embodiment of the present disclosure, the at least one diluent is light cycle oil. In yet another embodiment, the at least one diluent is kerosene.

[0045] In another embodiment of present disclosure, there is provided an antifoulant formulation as described herein, wherein the at least one alkylamine is selected from the group consisting of C12 amine, Cs amine, C9 amine, C10 amine, C11 amine, C13 amine, C14 amine, Ci ₆ amine, C17 amine, Cis amine, and combinations thereof. In another embodiment of the present disclosure, the at least one alkylamine is C ₁₂ amine. In yet another embodiment of the present disclosure, the at least one alkylamine is lauryl amine.

[0046] In an embodiment of the present disclosure, there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid; (b) at least one aromatic hydrocarbon is naphthalene, wherein naphthalene may be optionally substituted with Ci- ₆ alkyl, Ci- ₆ haloalkyl, C _2-6 alkenyl, C _2-6 alkynyl, Ci- ₆ alkoxy, C _3-6 cycloalkyl, or C _5-6 aryl; (c) at least one diluent selected from the group consisting of light cycle oil, kerosene, aromatic-rich hydrocarbon diluents, diesel, mineral turpentine oil (MTO), and combinations thereof; (d) polyisobutylene succinic anhydride; and (e) at least one alkyl amine selected from the group consisting of C ₁₂ amine, Cs amine, C ₉ amine, C ₁₀ amine, Cn amine, C ₁₃ amine, C ₁₄ amine, Ci ₆ amine, C ₁₇ amine, Cis amine, and combinations thereof.

[0047] In an embodiment of the present disclosure, there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid; (b) at least one aromatic hydrocarbon is naphthalene; (c) at least one diluent selected from light cycle oil, or kerosene; (d) polyisobutylene succinic anhydride; and (e) at least one alkyl amine is C ₁₂ amine.

[0048] In an embodiment of the present disclosure, there is provided an antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid having a weight percentage in the range of 5-20 % with respect to the formulation; (b) at least one aromatic hydrocarbon is naphthalene, wherein naphthalene may be optionally substituted with Ci- ₆ alkyl, Ci- ₆ haloalkyl, C _2-6 alkenyl, C _2-6 alkynyl, Ci- ₆ alkoxy, C _3-6 cycloalkyl, or C _5-6 aryl, and having a weight percentage in the range of 2-5 % with respect to the formulation; (c) at least one diluent selected from the group consisting of light cycle oil, kerosene, aromatic -rich hydrocarbon diluents, diesel, mineral turpentine oil (MTO), and combinations thereof, and having a weight percentage in the range of 50-85 % with respect to the formulation; (d) polyisobutylene succinic anhydride having a weight percentage in the range of 5-20 % with respect to the formulation; and (e) at least one alkyl amine selected from the group consisting of C ₁₂ amine, Cs amine, C ₉ amine, C ₁₀ amine, Cn amine, C ₁₃ amine, C ₁₄ amine, Ci ₆ amine, C ₁₇ amine, Cis amine, and combinations thereof, and having a weight percentage in the range of 1- 5 % with respect to the formulation.

[0049] In another embodiment of present disclosure, there is provided a process of preparing the antifoulant formulation as described herein, said process comprising: (a) contacting at least one ammonium salt of linear alkyl benzene sulphonic acid, at least one aromatic hydrocarbon, at least one diluent, polyisobutylene succinic anhydride; and, at least one alkyl amine to obtain a first mixture; and (b) processing the first mixture to obtain the antifoulant formulation.

[0050] In another embodiment of present disclosure, of preparing the antifoulant formulation as described herein, wherein processing the first mixture is carried out a temperature in the range of 40 - 50 °C for a period in the range of 2-4 hours at a stirring speed in the range of 50

- 200 rpm to obtain the antifoulant formulation.

[0051] In another embodiment of present disclosure, there is provided a process of preparing the antifoulant formulation as described herein, wherein said process comprising: (a) contacting at least one ammonium salt of linear alkyl benzene sulphonic acid, at least one aromatic hydrocarbon, at least one diluent, polyisobutylene succinic anhydride; and, at least one alkyl amine to obtain a first mixture; and (b) processing the first mixture at a temperature in the range of 40 - 50 °C for a period in the range of 2-4 hours at a stirring speed in the range of 50 - 200 rpm to obtain the antifoulant formulation.

[0052] In an embodiment of the present disclosure, there is provided a method of inhibiting fouling in a liquid hydrocarbon medium, the method comprising contacting the antifoulant formulation as described herein and the liquid hydrocarbon medium in the preheat exchangers of crude and short residue.

[0053] In an embodiment of the present disclosure, there is provided a method of inhibiting fouling in a liquid hydrocarbon medium, the method comprising contacting the antifoulant formulation as described herein and the liquid hydrocarbon medium, wherein the antifoulant formulation and the liquid hydrocarbon medium weight ratio is in the range of 1:500 - 1:200000. In another embodiment of the present disclosure, the antifoulant formulation and the liquid hydrocarbon medium weight ratio is in the range of 1:500 - 1:20000. In yet another embodiment of the present disclosure, the antifoulant formulation and the liquid hydrocarbon medium weight ratio is in the range of 1:500 - 1:2000. In a further embodiment of the present disclosure, the antifoulant formulation and the liquid hydrocarbon medium weight ratio is in the range of 1:500 - 1:1500. In a yet further embodiment of the present disclosure, the antifoulant formulation and the liquid hydrocarbon medium weight ratio is in the range of 1 :500

- 1:1000.

[0054] In an embodiment of the present disclosure, there is provided a method of inhibiting fouling in a liquid hydrocarbon medium, the method comprising contacting the antifoulant formulation comprising: (a) at least one ammonium salt of linear alkyl benzene sulphonic acid; (b) at least one aromatic hydrocarbon; (c) at least one diluent; (d) polyisobutylene succinic anhydride; and (e) at least one alkylamine, and the liquid hydrocarbon medium at a temperature in the range of 350 °C to 550 °C and a pressure in the range of 250 psi to 550 psi, wherein the temperature of the liquid hydrocarbon medium is in the range of 25 °C to 160 °C and the flow rate of the liquid hydrocarbon medium is in the range of 1-3 ml/min.

[0055] In an embodiment of the present disclosure, there is provided a method of inhibiting fouling in a liquid hydrocarbon medium, the method comprising contacting the antifoulant formulation and the liquid hydrocarbon medium in the preheat exchangers of crude and/or short residue as described herein, wherein the antifoulant formulation and the liquid hydrocarbon medium weight ratio is in the range of 1:500 - 1:200000.

[0056] In an embodiment of the present disclosure, there is provided a method of inhibiting fouling in a liquid hydrocarbon medium, the method comprising contacting the antifoulant formulation and the liquid hydrocarbon medium in the preheat exchangers of crude and/or short residue as described herein, wherein the antifoulant formulation and the liquid hydrocarbon medium weight ratio is in the range of 1:500 - 1:200000.

EXAMPLES

[0057] The following examples are given by way of illustration of the present invention and should not be construed to limit the scope of the present disclosure. It is to be understood that both the preceding general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the claimed subject matter.

Example 1: Analysis of the fouling scales:

[0058] Fouling scales obtained from heat exchangers were studied, and the study showed that fouling scales contain both inorganic species and organic species. Therefore, the possibilities wherein a formulation could work on quenching the organic and inorganic fouling species were explored.

[0059] Fouling in heat exchangers are also affected by the type of crude and its constituents. Therefore, different crudes were analyzed for sulfur (wt%), total basic number (TBN) and saturates, aromatics, resins, asphaltenes (SARA) for asphaltene content. These factors were taken into consideration while developing the antifoulant formulations. The analysis of the different crudes concerning its content is displayed in Table 1 below.

Table 1. Analysis of Crude-1, Crude-2, Crude-3, Crude-4, and Blend-1, Blend-2

[0060] The analysis of the short residue blend, which is Blend-3 concerning its properties is displayed in Table 2 below.

Table 2. Properties of Short Residue (having a boiling point of 540 and above)

Example 2: Preparation of the linear alkyl benzene sulfonic acid (LABSA) and alkyl amine salts:

Method of preparing Morpholine salt of Linear alkylbenzene sulfonic acid

[0061] Linear alkyl benzene sulfonic acid (LABSA) (1 mmol) was added to 2-neck round bottom flask with the condenser. The flask was cooled to 15 °C. Morpholine (1.5 mmol) was added slowly while stirring the reaction contents. During the morpholine addition, care was taken so that the temperature inside the flask did not exceed 50 °C. After completion of the morpholine addition, the resulting mixture was continued stirring for 30 minutes to afford LABSA-Morpholine salt.

Method of preparing isopropylamine salt of Linear alkylbenzene sulfonic acid

[0062] Linear alkyl benzene sulfonic acid (LABSA) (1 mmol) was added to 2-neck round bottom flask with the condenser. The flask was cooled to 15 °C. Isopropylamine (IP A) (1.5 mmol) was added slowly while stirring the reaction contents. During the IPA addition, care was taken so that the temperature inside the flask did not exceed 25 °C. This avoids vaporization of IPA. After completion of the IPA addition, the resulting reaction mixture was continued stirring for 30 minutes to afford LABSA-IPA salt.

Example 3: Preparation of the Antifoulant formulations:

[0063] To a flask containing LABSA-amine salt [5-20 wt%], naphthalene [2-5 wt%], polyisobutylene succinic anhydride (PIBSA) [5-20 wt%], lauryl amine [2-5 wt%] and diluent (light cycle oil for AF-15, AF-18, AF-19, AF-20, AF-21 and AF-24 (or) kerosene for AF-29, AF-30 and AF-36) [50-85 wt%] were blended while stirring between 40-50 °C. The resulting reaction contents were stirred to obtain a homogeneous formulation (first mixture). To stabilize the first mixture, diethanolamine or monoethanolamine (0.1-2 wt%) were added, if required, at temperature in the range of 40 - 50 °C for a period in the range of 2-4 hours at a stirring speed in the range of 50 - 200 rpm to obtain the antifoulant formulation. Several formulations were made with varying quantities of chemical constituents and diluents to evaluate various crudes, crude blends and vacuum residue/short residue.

Example 4: Method of inhibiting fouling of hydrocarbon medium involving the antifoulant formulations and evaluation thereof

[0064] A method comprising contacting the antifoulant formulation, wherein the antifoulant formulation (having a weight percentage in the range of 0.1 to 0.15% corresponding to 1000- 1500 ppm) and the liquid hydrocarbon medium (Crudes 1-4 and Blend 1-3) weight ratio is in the range of 1:600 - 1:1000 was performed in the laboratory. The operating conditions and parameters applied to evaluate fouling inhibition of a hydrocarbon medium by the antifoulant formulation of the present disclosure have been provided in Table 3 below.

[0065] The evaluation of antifoulant formulations was performed using Refinery Process Fouling Simulator (RPFS).

Table 3. Operating conditions of Antifoulant formulations

[0066] The performance monitoring of the antifoulant formulations of the present disclosure was performed for different crudes and blends in terms of DT (difference of temperature). The DT values evaluated for various crudes (Crude-1 to Crude-3) and blends (Blend-1 to Blend-3) 5 are given below.

Table 4. Evaluation results for Crude- 1

[0067] The evaluation results for Crude- 1 is tabulated in Table 4 above. The graphical representation is provided in Figure 1 of the present disclosure.

10 [0068] It is to be noted that fouling is caused due to number of factors via different mechanisms, therefore for an effective antifouling, a formulation is required which can arrest all types of fouling. The antifoulant formulation of the present disclosure effectively arrests fouling for Crude- 1, quenching both the organic and inorganic fouling species. This is evident from the results described in Table 4.

[0069] Light Cycle Oil (LCO), or kerosene and/or highly aromatic-rich hydrocarbon having up to 55% aromatics were used as the diluents in the antifoulant formulations of the present disclosure.

[0070] Various antifoulant formulations, such as, AF-15, AF-18, AF-19, AF-20, and AF-21 were mixed with crude 1 to evaluate the antifoulant efficacy. The AF-15 formulation contained 15% by weight of ammonium salt of linear alkyl benzene sulphonic acid, 2% by weight of alkyl amine, and 83% by weight of the diluent. The aromatic hydrocarbon and polyisobutylene succinic anhydride were absent in the formulation AF-15. The formulation AF-18 contained 10% by weight of ammonium salt of linear alkyl benzene sulphonic acid, 5% by weight of polyisobutylene succinic anhydride, and 85% by weight of the diluent. The aromatic hydrocarbon and alkyl amine were absent in the formulation AF-18. Thus, two out of the five constituents mentioned in the present disclosure were absent in the Formulations AF-15 and AF-18.

[0071] The formulation AF-19 consisted of 10% by weight of ammonium salt of linear alkyl benzene sulphonic acid, 5% by weight of polyisobutylene succinic anhydride, 2% by weight of alkyl amine, and 83% by weight of the diluent. The aromatic hydrocarbon was absent in AF- 19. The formulation AF-20 comprised of 10% by weight of polyisobutylene succinic anhydride, 3% by weight of aromatic hydrocarbon, 2% by weight of alkyl amine, and 85% by weight of the diluent, linear alkyl benzene sulphonic acid is absent. Thus, one out of the five constituents mentioned in the present disclosure were absent in the Formulations AF-19 and AF-20. Further, the polyisobutylene succinic anhydride is out of the specified range (5-20 wt%) in the formulations AF-18 and AF-19.

[0072] The antifoulant formulation AF-21 has all the five components described in the present disclosure. The formulation comprised 10% by weight of ammonium salt of linear alkyl benzene sulphonic acid, 10% by weight of polyisobutylene succinic anhydride, 3% by weight of aromatic hydrocarbon, 2% by weight of alkyl amine, and 75% by weight of the diluent. The antifoulant formulation containing all the five constituents in specific weight percentages, i.e., AF-21, was found to be more effective than other formulations described in Table 4.

[0073] The efficacy of all the antifoulant formulations were tested in terms of the AT values for Crude 1. The lower the value of AT, the better was the performance. The AT values for the formulations AF-15, AF-18, AF-19 and AF-20 which do not have all the five components were found to have a high DT value when compared with the antifoulant formulation AF-21 which had all the five components. The DT value attained for AF-21 was -14.6 °C, which was the lowest when compared the control crude- 1 without antifoulant formulation of the present disclosure (AF-21).

[0074] It is therefore concluded that the components in the specified weight percentage were essential to obtain an effective antifoulant formulation. Any deviation in the weight percentage or the absence of any component compromised the efficacy.

[0075] Additional set of antifoulant formulations were prepared, such as, AF-24, AF-29, AF- 30, and AF-36, and evaluated for their antifoulant efficacy against Blend-3. The efficacy results of the various antifoulant formulation against Blend-3 containing short residue (SR) is further tabulated in Table 5 below.

[0076] The AF-24 (composition provided below in Table 5) formulation contained only two components out of five, namely, 20% by weight of ammonium salt of linear alkyl and 80% by weight of the diluent (light cycle oil). The components alkyl amine, aromatic hydrocarbon, and polyisobutylene succinic anhydride were absent. Similarly, AF-30 comprised only three out of five components, i.e., 20% by weight of ammonium salt of linear alkyl, 5% by weight of polyisobutylene succinic anhydride and 75% by weight of the diluent. The components alkylamine, and aromatic hydrocarbon were absent.

[0077] The antifoulant formulation AF-29 contained all the five components, i.e., 20% by weight of ammonium salt of linear alkyl benzene sulphonic acid, 5% by weight of polyisobutylene succinic anhydride, 3% by weight of aromatic hydrocarbon, 2% by weight of alkyl amine and 70% by weight of the diluent. Similarly, AF-36 contained all the five components, viz., 20% by weight of ammonium salt of linear alkyl benzene sulphonic acid, 10% by weight of polyisobutylene succinic anhydride, 3% by weight of aromatic hydrocarbon, 2% by weight of alkylamine and 65% by weight of the diluent.

[0078] From Table 5 it is inferred that the antifoulant formulations of the present disclosure, i.e., AF-36 and AF-29, which had all the components in specified ranges were found to be more effective than other formulations.

Table 5. Evaluation results of Blend-3

[0079] The present disclosure further illustrates the evaluation of the antifoulant formulation of the present disclosure against other crudes (Crude-2 and Crude-3) and blends (Blend- 1 and Blend-2) concerning their DT values.

Table 6. Evaluation results of Crude-2, Crude-3, Blend-1, and Blend-2.

[0080] The evaluation results for Crude-2, and Crude-3 along with Blend- 1, and Blend-2 are tabulated in Table 6 above. The evaluation was carried out similarly as stated above for Crude- 1. AF-29 (composition provided above in Table 5) proved to be the best antifoulant formulation for Crude 2 and Blend 2 on the basis of DT values as illustrated in Table 6. Similarly, for Crude 3, and Blend 1 antifoulant formulation AF-21 provided best results with respect to the AT values.

[0081] In view of the above, it is observed that the antifouling formulation of the present disclosure is able to arrest almost all types of fouling to merit as effective antifouling formulationwhich has been validated by testing various crudes and blends. Therefore, the antifoulant formulation of the present disclosure is technically advanced over the antifoulant formulations known in the art.

[0082] Although the subject matter has been described in considerable details with reference to certain examples and embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the subject matter, will become apparent to persons skilled in the art upon reference to the description of the subject matter. It is therefore contemplated that such modifications can be made without departing from the present subject matter as defined.

Advantages of the antifoulant formulations.

[0083] The present disclosure provides a high-performance antifoulant formulation comprising ionic surfactants based on alkylbenzene sulfonates and amines, polyisobutylene succinic anhydride, naphthalene, and aromatic-rich diluents, for reducing fouling, including particulate- induced fouling, in heat exchangers of crude and vacuum residue in the hydrocarbon refining process.

[0084] The antifoulant formulation of the present disclosure when evaluated for a series of crudes and vacuum residue using refinery process fouling simulator (RPFS) showed excellent results compared to corresponding runs without antifoulant formulations. The evaluation studies are not only limited to the heat exchangers of crudes, blends and short residue but can also be used in the heat exchangers of DHDS unit, vis-breaker units, and other refinery applications.