DESC:FIELD
The present disclosure relates to a composition for removal of solid deposits.
BACKGROUND
Hydroprocessing of crude oil fractions in petroleum refineries is a crucial process to convert crude oil into marketable products. Hydroprocessing is carried out in different types of reactors in the presence of a catalyst. Feed streams to these reactors come from various process equipments such as distillation columns, cold storage tanks, pipelines, and the like. The reactors can be a fixed bed system with a plurality of catalyst bed. The reactors comprise many internal parts like a distributor plate, a catalyst support, a quench box, and the like. The reactors are designed for a fixed range of allowable pressure drop across each catalyst bed. Over a period of time, the pressure drop across the reactor increases. The increase in the pressure drop is attributed to the formation of solid deposits like iron sulfides and iron sulfates on the catalyst bed during hydroprocessing of crude oil.
Following are the drawbacks associated with the deposition of solids in the reactor and on the catalyst bed:
• increased pressure drop across the reactor and the catalyst bed;
• reduced catalytic activity of the catalyst;
• reduced throughput; and
• shutdown of the entire operation.
There is, therefore, felt a need for an alternative for removal of solid deposits and to obviate the above mentioned drawbacks.

OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to remove solid deposits from a reactor.
Another object of the present disclosure is to remove solid deposits from a catalyst bed.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure relates to a composition for removing solid deposits from a location selected from at least one of the inner walls of a reactor, the inner walls of pipelines, the inner walls of heat exchangers and a catalyst bed. The composition comprises 2 wt% to 60 wt% of at least one dispersant salt and 40 wt% to 98 wt% of at least one hydrocarbon.
The Hydrocarbon can be atleast one selected from the group consisting of hydrocarbons with the carbon number range of C5 to C50.
The present disclosure also provides a method for preparing the dispersant.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
A composition for removal of solid deposits will now be described with the help of the accompanying drawing, in which:
Figure 1 illustrates a trickling bed system in accordance with the present disclosure.
DETAILED DESCRIPTION
In hydroprocessing units, the corrosive products from upstream of reactor and other gum forming compounds create solid deposits on the catalyst bed inside the reactor. The present disclosure, therefore, provides a composition for removal of solid deposits from a location, wherein the location is not limited to the inner walls of a reactor, the inner walls of pipelines, the inner walls of heat exchangers and a catalyst bed.
The composition of the present disclosure comprises at least one dispersant salt and at least one hydrocarbon.
The dispersant includes, but not limited to, ammonium salt.
The hydrocarbon includes, but not limited to, C5 to C50 carbon atoms per molecule. In accordance with one embodiment of the present disclosure, the hydrocarboncan be at least one selected from the group consisting of naphtha, gasoline, diesel, kerosene, benzene, xylene, mesitylene, and toluene.
Solids, such as, iron sulfide deposited in the reactor and on the catalyst bed during hydroprocessing of the crude oil fractions, results in fouling of the reactor and the catalyst bed as described herein above. Moreover, depending upon the porosity of the solids deposited in the reactor and on the catalyst bed, the flow-rates of the reactants entering in the reactor are affected, thereby increasing the pressure drop in the reactor.
The addition of the dispersant in the feed stream facilitates in improving the separation of solids from the deposited area (location), thereby inhibiting settling and clumping of the solids in the reactor and on the catalyst bed. Due to this, fouling of the reactor and the catalyst bed is inhibited, thereby obviating the above mentioned drawbacks.
Moreover, if a portion of the deposited solids is carried along with the hydrocarbon in different process equipments like heat exchangers and pipelines, and is deposited therein, then the composition of the present disclosure facilitates in removing the deposited solids therefrom.
The composition of the present disclosure can be used for the removal of solids from a location which can be at least one of the inner walls of heat exchangers, the inner walls of pipelines, the inner walls of a reactor and a catalyst bed.
The present disclosure also provides a method for preparing the dispersant. The method is carried out in the following step:
In the first step, an acid is cooled to a first pre-determined temperature to obtain a cooled acid. In the second step, a base is cooled to a second pre-determined temperature to obtain a cooled base. In the third step, the cooled base is added to the cooled acid at a pre-determined rate while stirring at a pre-determined speed, at a third pre-determined temperature and for a pre-determined time period to obtain the dispersant salt. In accordance with one embodiment of the present disclosure, the cooled base can also be added to the cooled acid in a drop wise manner.
The first pre-determined temperature can be in the range of -15 ºC to 25 ºC and the second pre-determined temperature can be in the range of -10 ºC to 25 ºC. The first pre-determined temperature and the second pre-determined temperature are not limited to the herein above mentioned ranges.
The pre-determined rate can be in the range of 1 ml/min to 100 ml/min, the pre-determined speed can be in the range of 500 rpm to 1000 rpm, the third pre-determined temperature can be in the range of -10 ºC to 25 ºC, and the pre-determined time period can be in the range of 2 hour to 8 hour.
After formation of the dispersant salt, stirring is continued further in the reactor, for a time period in the range of 2 hour to 4 hour, to ensure completion of the reaction.The acid can be at least one selected from the group consisting of linear alkyl benzene sulfonic acid, lactic acid, acetic acid, formic acid, oleic acid, linoleic acid, palmitic acid, citric acid, and uric acid.
In accordance with one embodiment of the present disclosure, the purity of the organic acid used in the process for preparing the dispersant ranges from 85% to 99%.
The base includes, but is not limited to, an organic compound containing nitrogen.
The base can be at least one selected from the group consisting of ethylamine, isopropylamine, butylamine, pentylamine, hexylamine, pyridine, pyrrolidine imidazole, piperidine, benzimidazole, pyrazine, alkyl pyrazine and morpholine.
In accordance with an exemplary embodiment of the present disclosure, isopropyl amine (IPA) is added to linear alkyl benzene sulfonic acid (LABSA) to obtain a linear alkylbenzene sulfonated isopropyl ammonium salt.
In accordance with another exemplary embodiment of the present disclosure, isopropyl amine (IPA) is added to dodecyl benzene sulfonic acid (DDBSA) to obtain a dodecyl benzene sulfonated isopropyl ammonium salt.
In accordance with still another exemplary embodiment of the present disclosure, isopropyl amine (IPA) is added to oleic acid to obtain a oleic acid isopropyl ammonium salt.
In accordance with one embodiment of the present disclosure, at least one inorganic acid can be used for preparing the dispersant.
The inorganic acid can be at least one selected from the group consisting of sulfuric acid, nitric acid, and carbonic acid.
In accordance with one embodiment of the present disclosure, the concentration of the inorganic acid can be in the range of 0.2 wt% to 6 wt% of the total composition.
Further, a mixture of ammonium salts can be added to the hydrocarbon to obtain the composition for removal of solid deposits effectively.
In accordance with one embodiment of the present disclosure, a mixture of dodecyl benzene sulfonated isopropyl ammonium salt and oleic acid - isopropyl ammonium salt can be added in 1:1 molar ratio in the hydrocarbon, for effectively removing solid deposits from the reactor, thereby obviating fouling of the reactor and the catalyst bed.
The present disclosure also provides a method for removing solid deposits from the location. The method is carried out by mixing a pre-determined concentration of the dispersant in the process stream at a temperature in the range of 15ºC to 460ºC and at a pressure in the range of 1 bar to 200 bar, is allowed to contact the location, thereby dispersing and reducing the solid deposits therefrom.
The pre-determined concentration of the dispersant salt can be in the range of 2 wt% to 60 wt% of the total composition.
The pre-determined concentration of the hydrocarbon can be in the range of 40 wt% to 98 wt% of the total composition.
The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale.
Experiment 1: Preparation of ammonium salts
A. Method for the preparation of dodecyl benzene sulfonated isopropyl ammonium salt (99.9%).
1 mmol of DDBSA of 99.9% purity was added and cooled to 15ºC in a first round bottom flask, which was kept in an ice bath, to form a cooled DDBSA. 1 mmol of IPA was added and cooled to 10ºC in a second round bottom flask, which was kept in an ice bath, to form a cooled IPA. The cooled IPA was then added to the first round bottom flask in a drop wise manner. The reaction between the cooled DDBSA and the cooled IPA was carried out at 15ºC under stirring for 2 hours to obtain the dodecyl benzene sulfonated isopropyl ammonium salt (99.9%). The reaction temperature was maintained below 20ºC to avoid loss of IPA. After formation of the dodecyl benzene sulfonated isopropyl ammonium salt (99.9%), stirring was continued in the first round bottom flask for 4 hour at room temperature to ensure completion of the reaction.
B. Method for the preparation of linear alkyl benzene sulfonated isopropyl ammonium salt (90%).
1 mmol of LABSA of 90% purity was added and cooled to 15ºC in a first round bottom flask, which was kept in an ice bath, to form a cooled LABSA. 1 mmol of IPA was added and cooled to 20ºC in a second round bottom flask, which was kept in an ice bath, to form a cooled IPA. The cooled IPA was then added to the first round bottom flask in a drop wise manner. The reaction between the cooled LABSA and the cooled IPA was carried out at 15ºC under stirring for 2 hours to obtain the linear alkyl benzene sulfonated isopropyl ammonium salt (90%). The reaction temperature was maintained below 20ºC to avoid loss of IPA. After formation of the linear alkyl benzene sulfonated isopropyl ammonium salt (90%), stirring was continued in the first round bottom flask for 4 hour at room temperature to ensure completion of the reaction.
C. Method for the preparation of linear alkyl benzene sulfonated isopropyl ammonium salt (96%).
1 mmol of LABSA of 96% purity was added and cooled to 15ºC in a first round bottom flask, which was kept in an ice bath, to form a cooled LABSA. 1 mmol of IPA was added and cooled to 20ºC in a second round bottom flask, which was kept in an ice bath, to form a cooled IPA. The cooled IPA was then added to the first round bottom flask in a drop wise manner. The reaction between the cooled LABSA and the cooled IPA was carried out at 15ºC under stirring for 2 hours to obtain the linear alkyl benzene sulfonated isopropyl ammonium salt (96%). The reaction temperature was maintained below 20ºC to avoid loss of IPA. After formation of the linear alkyl benzene sulfonated isopropyl ammonium salt (96%), stirring was continued in the first round bottom flask for 4 hour at room temperature to ensure completion of the reaction.
D. Method for the preparation of oleic acid-isopropyl ammonium salt (65%).
1 mmol of oleic acid of 65% purity was added and cooled to 25ºC in a first round bottom flask, which was kept in an ice bath, to form a cooled oleic acid. 1.5 mmol of IPA was added and cooled to 10ºC in a second round bottom flask, which was kept in an ice bath, to form a cooled IPA. The cooled IPA was then added to the first round bottom flask in a drop wise manner. The reaction between the cooled oleic acid and the cooled IPA was carried out at 15ºC under stirring for 2 hours to obtain the oleic acid sulfonated isopropyl ammonium salt (65%). The reaction temperature was maintained below 20ºC to avoid loss of IPA. After formation of the linear alkyl benzene sulfonated isopropyl ammonium salt (65%), stirring was continued in the first round bottom flask for 4 hour at room temperature to ensure completion of the reaction.
E. Method for the preparation of oleic acid - isopropyl ammonium salt (99%).
1 mmol of oleic acid of 99% purity was added and cooled to 25ºC in a first round bottom flask, which was kept in an ice bath, to form a cooled oleic acid. 1.5 mmol of IPA was added and cooled to 10ºC in a second round bottom flask, which was kept in an ice bath, to form a cooled IPA. The cooled IPA was then added to the first round bottom flask in a drop wise manner. The reaction between the cooled oleic acid and the cooled IPA was carried out at 15ºC under stirring for 2 hours to obtain the oleic acid sulfonated isopropyl ammonium salt (99%). The reaction temperature was maintained below 20ºC to avoid loss of IPA. After formation of the linear alkyl benzene sulfonated isopropyl ammonium salt (99%), stirring was continued in the first round bottom flask for 4 hour at room temperature to ensure completion of the reaction.
Experiment 2: Effect of addition of the dodecyl benzene sulfonated isopropyl ammonium salt in Diesel.
The dodecyl benzene sulfonated isopropyl ammonium salt was added in diesel to determine the change in properties of diesel such as initial boiling point (IBP), T5 (the temperature at which 5 wt% of the diesel is vaporized), T50 (the temperature at which 50 wt% of the diesel is vaporized), T95 distillation temperatures (the temperature at which 95 wt% of the diesel is vaporized), final boiling point (FBP), density, sulfur content, and cetane index (CI). Diesel along with the dodecyl benzene sulfonated isopropyl ammonium salt were hydrotreated to determine the change in properties of the hydrotreated diesel. The comparison of the change in properties of diesel on addition of 2wt% and 5wt% of the dodecyl benzene sulfonated isopropyl ammonium salt in diesel with standard properties (0 wt% salt) of diesel is tabulated in Table-1.
Table-1:
Hydrotreated Diesel Ammonium salt in Diesel in wt%
0% 2% 5%
IBP 158 214.9 220.9
T5 197.6 235.9 238.3
T50 287.6 290.2 291.7
T95 363.2 361.6 363.7
FBP 369.4 368.7 374.4
Density, g/cc 0.8215 0.8251 0.8265
Sulphur, ppm 210 215 169
Cetane Index 61.11 60.22 59.99

From Table-1, it can be concluded that, the properties of diesel on addition of 2 wt% and 5 wt% of the dodecyl benzene sulfonated isopropyl ammonium salt in diesel does not change significantly when compared with the standard properties of diesel.
Experiment 3: Evaluation of the performance of the composition
The performance of the composition containing the ammonium salt prepared in experiment 1 was evaluated in two approaches, viz., studying the settling rate of iron sulfide in diesel, and studying the flow-rate of diesel in a fixed bed covered with a scale of iron sulphide.
First approach: Settling rate of iron sulfide
Iron sulfide was prepared by reacting 0.25 molar solution of iron sulfate in water with 0.25 molar solution of sodium sulphide in water. The precipitated iron sulfide was then filtered and dried for 1 hour. About 1 gm of iron sulfide was added in a glass beaker filled with 200 ml of diesel. The ammonium salt was added to the glass beaker and mixed with diesel by a stirrer for 5 minutes and then allowed to settle down. The time taken by the iron sulfide to settle down in diesel was noted.
Second approach: Simulated Trickling Bed System
As shown in Figure 1, the trickling bed system (100) includes:
• a set of columns (B1 and B2) connected with a tubing arrangement (T) to make a U-Tube configuration; and
• a packed bed
The U-tube configuration was used for studying the effectiveness of the sample compositions (tabulated in Table-2). One of the columns (B1) was filled with different layers of solids (1 to 6), viz., a layer of sand grits (1), a layer of alumina balls (2 and 4), a layer of glass wool (3), a layer of silicon carbide (5) and a layer of iron sulfide (6), to form the packed bed reactor. Particularly, the layer of iron sulfide (6) was placed on the layer of silicon carbide (5).
This type of packing was repeated over several beds depending upon the density, viscosity and other physical properties of the samples (tabulated in Table-2) to be tested in the experiment. The size of the alumina balls in the packed bed reactor can be varied depending upon the sample(s) (tabulated in Table-2) to be tested in the experiment. The length of the tubing (T) between the set of columns (B1 and B2) depends upon the density, viscosity and other physical properties of the samples (tabulated in Table-2) to be tested in the experiment.
The column (B1) (as shown in Figure 1) was filled in such a way that the sample to be tested does not overflow from the column (B2), during the experiment. The time required by the sample to disperse the layer of iron sulfide (6) and trickle down the packed bed reactor was recorded, to measure the trickling rate. In this experiment, the sample to be tested was dosed in kerosene at a concentration of 2000 ppmw. The experiment was repeated for all the samples tabulated in Table-2.
Table-2:
Sr. No Sample Name Composition of the Samples Trickling rate (ml/min)
1 A DDBSA Salt dissolved in diesel. 0.69
2 B DDBSA Salt dissolved in diesel. 0.72
3 S1 Acidic LABSA isopropylamine salt (90%) in diesel 0.922
4 S2 Basic LABSA isopropylamine salt (90%) in diesel 1.6
5 S3 S2 stripped off excess amine at 60°C and filtered 1.45
6 S4 LABSA isopropylamine salt (90%) heated at 60°C for 3 hour and flushed with N2 to remove excess amine, and dissolved in diesel 2.08
7 S5 dodecylbenzene isopropylamine salt (99.9%) dissolved in diesel 1.94
8 S7 S5 salt heated at 60°C for 4 hour and dissolved in diesel 2.18
9 S8 LABSA isopropylamine salt (95%) in diesel 2.09
10 S9
LABSA (96%) reacted with mono-iso-propylamine in diesel 1.12
11 S10 LABSA isopropylamine salt (96%) and diesel in the ratio of 30:70 2.14
12 S11 LABSA isopropylamine salt (90%) in diesel 0.81
13 S12 LABSA isopropylamine salt (96%) dissolved in diesel 0.99
14 S14 LABSA isopropylamine salt (96%) in diesel 2.42
15 S15 LABSA isopropylamine salt (95%) in diesel 1.99
16 S19 LABSA-Pyrrolidine salt in Diesel 1.7
17 S20 4-DBSA-Pyrrolidine salt in Diesel 1.71
18 S21 OLEIC ACID- Pyrrolidine salt in Diesel 1.72
19 S22 OLEIC ACID- aniline salt in Diesel 1.74
20 S23 OLEIC ACID- t-Butyl amine salt in Diesel 1.72
21 S25 Oleic Acid-morpholine salt in Diesel 1.69

TECHNICAL ADVANCES AND ECONOMICAL SIGNIFICANCE
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a composition that:
• reduces the pressure drop across the reactor and the catalyst bed;
• increases the catalytic activity of the catalyst;
• increases the throughput, by removing the solid deposits, particularly iron sulfide, efficiently from the reactor and the catalyst bed; and
• requires less time for removing the solid deposits.
The disclosure has been described with reference to the accompanying embodiments which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein.
The foregoing description of the specific embodiments so fully revealed the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the invention as it existed anywhere before the priority date of this application.
In view of the wide variety of embodiments to which the principles of the present invention can be applied, it should be understood that the illustrated embodiments are exemplary only. While considerable emphasis has been placed herein on the particular features of this invention, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principle of the invention. These and other modifications in the nature of the invention or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation. ,CLAIMS:1. A composition for removing solid deposits from a location selected from at least one of the inner walls of a reactor, the inner walls of pipelines, the inner walls of heat exchangers and a catalyst bed, said composition comprising:
• at least one dispersant salt in the range of 2 wt% to 60 wt%; and
• at least one hydrocarbon selected from the group consisting of C1 to C50 carbon atom(s) per molecule, wherein said at least one hydrocarbon is in the range of 40 wt% to 98 wt%.

2. The composition as claimed in claim 1, wherein said solid deposits comprise iron sulfide particles.

3. A method for preparing the dispersant as claimed in claim 1, wherein said method comprises the following steps:
• cooling an acid to a first pre-determined temperature to obtain a cooled acid;
• cooling a base to a second pre-determined temperature to obtain a cooled base; and
• adding said cooled base to said cooled acid at a pre-determined rate while stirring at a pre-determined speed, at a third pre-determined temperature, and for a pre-determined time period to obtain said dispersant.

4. The method as claimed in claim 3, wherein said acid is at least one selected from the group consisting of alkyl aryl sulfonic acid, lactic acid, acetic acid, formic acid, oleic acid, linoleic acid, palmitic acid, citric acid, and uric acid.
5. The method as claimed in claim 3, wherein said base is at least one selected from the group consisting of ethylamine, isopropylamine, butylamine, pentylamine, hexylamine, pyridine, pyrrolidine imidazole, piperidine, benzimidazole, pyrazine, alkyl pyrazine and morpholine.

6. The method as claimed in claim 3, wherein said:
• first pre-determined temperature is in the range of -15ºC to 25ºC;
• second pre-determined temperature is in the range of -10ºC to 25ºC; and
• third pre-determined temperature is in the range of -10ºC to 25ºC.

7. The method as claimed in claim 3, wherein said:
• pre-determined rate is in the range of 1 ml/min to 100 ml/min;
• pre-determined speed is in the range of 500 rpm to 1000 rpm; and
• pre-determined time period is in the range of 2 hour to 8 hour.

8. The method as claimed in claim 3, wherein the molar ratio of said cooled acid and said cooled base is 1:1.

9. A method for reducing solid deposits from a location selected from at least one of the inner walls of a reactor, the inner walls of pipelines, the inner walls of heat exchangers and a catalyst bed, said method comprising the following steps:
• mixing a pre-determined amount of at least one dispersant in a pre-determined amount of at least one hydrocarbon, at a temperature in the range of 15ºC to 460ºC and at a pressure in the range of 1 bar to 200 bar, to form a composition; and
• allowing said pre-determined amount of said at least one dispersant to contact said location to disperse and reduced said solid deposits from said location.

10. The method as claimed in claim 9, wherein said pre-determined amount of said at least dispersant is in the range of 2 wt% to 60 wt%.