Description:FIELD OF THE INVENTION
[0001] The present disclosure generally relates to the technical field of crude oil distillation. Specifically, the present invention relates to the process of cracking of reduced crude oils. More specifically, the present invention relates to a process for reduction of cracking in the reduced crude oil vacuum heater using chemical additive.

BACKGROUND OF THE INVENTION
[0002] Reduced crude oil (RCO) from atmospheric distillation tower bottom is heated up in vacuum heater to around 390-410?C before it is introduced into the Vacuum distillation column. During the heating process, RCO is prone to cracking which can lead to issues such as high hot well off gases (HWOG) generation/poor vacuum, reduced distillate yield, high short residue (SR) yield & poor bitumen quality.
[0003] In a vacuum heater, cracking is majorly influenced by sulphur species present in the RCO leading to H2S generation, and in turn leading to high hot well off gases. Many a times, refinery HWOG analysis shows H2S content above the acceptable amine absorber inlet limit (10 vol%). In addition, the free radicals formed during cracking can further induce chain reactions increasing lighter components. This results in lower vacuum (-740 mm Hg to -720 mm Hg) resulting in slippage of vacuum gas oil (VGO) into short residue (SR) affecting bitumen quality. To mitigate these issues, furnace coil output temperature (COT) is sometimes lowered (by a couple of degrees) or turbulizing steam is adjusted which affects plant performance.
[0004] Therefore, there is an unmet need in the art to provide a process for the reduction of cracking/improve vacuum that increases distillate yield and quality, mitigates corrosion, and contributes reducing amine consumption in amine absorber for HWOG.

OBJECTIVES OF THE INVENTION
[0005] An objective of the present invention is to provide a process for the reduction of cracking in reduced crude oil vacuum heater.
[0006] Another objective of the present invention is to provide a process for the reduction of cracking in reduced crude oil vacuum heater using chemical additive.
[0007] Yet another objective of the present invention is to provide a process for the reduction of cracking in reduced crude oil vacuum heater that reduces cracking thereby increases distillate yield and quality, mitigates corrosion, and contributes reducing amine consumption in amine absorber for HWOG.

SUMMARY OF THE INVENTION
[0008] The present invention relates to the technical field of cracking of reduced crude oils. More specifically, the present invention relates to the process for reduction of cracking in reduced crude oil vacuum heater using chemical additive.
[0009] In one aspect, the present invention relates to a process for reducing cracking of reduced crude oil comprising the steps of:
(a) obtaining a reduced crude oil from crude atmospheric distillation unit;
(b) mixing chemical additive with the reduced crude oil in a chemical injection facility to obtain additive mixed reduced crude oil;
(c) cracking the additive mixed reduced crude oil in vacuum heater at a temperature in a range of a temperature of 350?C to 450?C at atmospheric pressure to obtain cracked reduced crude oil; and
(d) distilling the cracked reduced crude oil in vacuum distillation unit to obtain hot well gases, distillates, and short residue.
[0010] In another aspect of the present invention, the process optionally comprises mixing chemical additive in an intermediate storage tank of reduced crude oil.
[0011] In another aspect of the present invention, the chemical additive is selected from the group consisting of H2S Scavenger and radical quencher, solubilizing agent and diluent.
[0012] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments.

BRIEF DESCRIPTION OF THE INVENTION
[0013] Figure 1 is the flow diagram of existing process of reduced crude oil treatment.
[0014] Figure 2 is the flow diagram of the process of present invention for reducing cracking of reduced crude oil.
[0015] Figure 3 is the flow diagram of the process of present invention for reducing cracking of reduced crude oil.

DETAILED DESCRIPTION OF THE INVENTION
[0016] The following is a detailed description of embodiments of the disclosure. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0017] Unless the context requires otherwise, throughout the specification, which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”
[0018] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[0019] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0020] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0021] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable.
[0022] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.
[0023] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
[0024] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.
[0025] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0026] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description that follows, and the embodiments described herein, is provided by way of illustration of an example, or examples, of particular embodiments of the principles and aspects of the present disclosure. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the disclosure.
[0027] It should also be appreciated that the present invention can be implemented in numerous ways, including as a system, a method or a device. In this specification, these implementations, or any other form that the invention may take, may be referred to as processes. In general, the order of the steps of the disclosed processes may be altered within the scope of the invention.
[0028] The present disclosure generally relates to the technical field of crude oil distillation. Specifically, the present invention relates to the process of cracking of reduced crude oils. More specifically, the present invention relates to a process for reduction of cracking in the reduced crude oil vacuum heater using chemical additive.
[0029] In an embodiment, the present invention relates to a process for reducing cracking of reduced crude oil comprising the steps of:
(a) obtaining a reduced crude oil from crude atmospheric distillation unit;
(b) mixing chemical additive with the reduced crude oil in a chemical injection facility to obtain additive mixed reduced crude oil;
(c) cracking the additive mixed reduced crude oil in vacuum heater at a temperature in a range of a temperature of 350?C to 450?C at atmospheric pressure to obtain cracked reduced crude oil; and
(d) distilling the cracked reduced crude oil in vacuum distillation unit to obtain hot well gases, distillates, and short residue.
[0030] In another embodiment, the present invention relates to a process for reducing cracking of reduced crude oil comprising the steps of:
(a) obtaining a reduced crude oil from crude atmospheric distillation unit;
(b) storing the reduced crude oil in an intermediate storage tank;
(c) mixing chemical additive with the reduced crude oil through a chemical injection facility to obtain additive mixed reduced crude oil;
(d) cracking the additive mixed reduced crude oil in vacuum heater at a temperature in a range of a temperature of 350?C to 450?C at atmospheric pressure to obtain cracked reduced crude oil; and
(e) distilling the cracked reduced crude oil in vacuum distillation unit to obtain hot well gases, distillates, and short residue.
[0031] In another embodiment of the present invention, the chemical additive is selected from the group consisting of H2S scavenger, radical quencher, solubilizing agent and diluent.
[0032] In another embodiment of the present invention, the H2S scavenger is selected from the group consisting of metal carboxylate, triazine based scavengers, and aldehyde-based scavengers.
[0033] In another embodiment of the present invention, the H2S scavenger is metal carboxylate. The metal carboxylate is selected from zinc carboxylate, iron carboxylate, copper carboxylate, cobalt carboxylate, calcium carboxylate, and manganese carboxylate.
[0034] In another embodiment of the present invention, the radical quencher is butylated hydroxytoluene.
[0035] In another embodiment of the present invention, the solubilizing agent is xylene, triethylamine, tri-n-butylamine, benzyldimethylamine, quaternary ammonium hydroxides, such as tetraethylammonium hydroxide (EAH), tetra-n-butylammonium hydroxide, and trimethylbenzylammonium hydroxide, octanol, decyl alcohol and cresols.
[0036] In another embodiment of the present invention, the diluent is diesel.
[0037] In another embodiment of the present invention, the cracking is carried out at a temperature in a range of 350?C to 450?C. Preferably, at a temperature of 390?C to 410?C. More preferably, at a temperature of 400?C.
[0038] In another embodiment of the present invention, the mixing of chemical additive with RCO is carried out for a circulation time period in a range of 1-6 hours to become homogenous with RCO. Preferably, the circulation time is in a range of 3-4 hours.
[0039] According to the present invention, the dosing facility envisaged for adding an anti-cracking additive to RCO before it is heated to 390-410?C in a heater. The dosing facility is configured for directly dosing the anti-cracking additive in an RCO line from atmospheric column. The dosing facility is also configured for dosing the anti-cracking additive in intermediate storage tank of RCO. A circulation time of 3-4 hours may be given for the chemical to become homogenous with RCO. The RCO is further distilled under Vacuum for making range of distillates and Bitumen.
[0040] In another embodiment of the present invention, the process show excellent cracking mitigation in RCO vacuum heater.
[0041] While the foregoing describes various embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.
[0042] The present invention is further explained in the form of following examples. However, it is to be understood that the following examples are merely illustrative and are not to be taken as limitations upon the scope of the invention.
EXAMPLES
Materials:
[0043] Field trials were carried out at Vizag Refinery using the process as described above for improving the unit performance. The additive was dosed upstream of Vac Heater (RCO inlet to furnace) using a dosing pump (16 ppm on RCO). The novel process of adding chemical is targeted to mitigate RCO cracking, which in turn will reduce the Hot Well-Off Gases, improve distillate yields, reduce SR yields and improve SR properties w.r.t. bitumen specifications. Figure 1 depicts the flow diagram of the existing process whereas the figures 2 and 3 show the flow diagram of the current process of the present invention.
[0044] Experiment:
Process Steps:
• Field trials were carried out at HPCL Visakh Refinery.
• Reduced crude oil (RCO) was obtained @ 250 m3/h from crude atmospheric distillation unit.
• A chemical additive, consisting of H2S Scavenger (zinc carboxylate), radical quencher (Butylated hydroxytoluene), solubilizer (xylene) and diluent (diesel), was dosed upstream of Vac Heater (RCO inlet to furnace) at a dosing rate of 3.5 lph (10-300) ppm on RCO) on continuous basis.
• Average COT maintained during the period was 394.8 deg C. Vacuum was maintained at -760 mm Hg during the trial period.
• Hot Well Oil analysis and SR samples were collected and the following parameters were analyzed and compared with existing process to find out the effectiveness.
[0045] Penetration value of Short Residue:
Average PEN with existing process, 1/10 mm 44.4 18.9 % Improvement
Average PEN with new process of charging additive, 1/10 mm 36.0

[0046] Absolute Viscosity of Short Residue
Average Abs. Visc. with existing process, poise 3696.8 32.8 % Improvement
Average Abs. Visc. with new process of charging additive, poise 4910.1

[0047] Hot Well Oil Analysis
Hot well oil samples were analyzed on weekly basis received from refinery to assess the effectiveness of the process w.r.t mitigating olefins/free radicals formed as a result of cracking.
Date Bromine No (g/100g) Average
With Existing process 19-01-2023 40 34.25
21-01-2023 34
22-01-2023 31
24-01-2023 32
With new process of charging additive 09-02-2023 32 24.6
16-02-2023 26
20-02-2023 21
09-03-2023 27
25-03-2023 17

[0048] Average reduction in bromine No is ~28% with new process for adding chemical. This indicates that the proposed process for charging chemical is effective in mitigation of cracking.
[0049] SR Density & Distillation
SR Density:
Average Density @ 15°C (g/cc)
With Existing process 1.0547
With new process of charging additive 1.0568

SR Distillation:
With Existing process With new process of charging additive
IBP 399.8 417.0
5% 498.7 500
10% 529.6 528.9
20% 567.6 564.5
30% 594.6 593.8
40% 621.9 622.0
50% 650.2 652.0
60% 682.7 687.2
70% 716.5 721.3
80% 750 @ 77.8 %
750 @ 73.8 %

ADVANTGAES OF THE INVENTION:
• The present invention provides process for reducing cracking of reduced crude oil that shows excellent cracking mitigation in RCO vacuum heater.
• The present invention provides process for reducing cracking of reduced crude oil that increases distillate yield and quality, and contributes reducing amine consumption in amine absorber for HWOG.
, Claims:1. A process for reducing cracking of reduced crude oil, wherein the process comprising the steps of:
(a) obtaining a reduced crude oil from crude atmospheric distillation unit;
(b) mixing chemical additive with the reduced crude oil using a chemical injection facility to obtain additive mixed reduced crude oil;
(c) cracking the additive mixed reduced crude oil in vacuum heater at a temperature in a range of a temperature of 350?C to 450?C at atmospheric pressure to obtain cracked reduced crude oil; and
(d) distilling the cracked reduced crude oil in vacuum distillation unit to obtain hot well gases, distillates, and short residue.

2. The process as claimed in claim 1, wherein the chemical additive is selected from the group consisting of H2S scavenger, radical quencher, solubilizing agent and diluent.

3. The process as claimed in claim 1, wherein the step of mixing chemical additive is carried out directly in a RCO line from the atmospheric distillation unit.

4. The process as claimed in claim 1, wherein the step of mixing chemical additive is carried out in an intermediate storage tank of RCO.

5. The process as claimed in claim 1, wherein the step of mixing chemical additive is carried out for a time period in a range of 1-6 hours.

6. The process as claimed in claim 1, wherein the temperature in step (c) is in a range of 390?C to 410?C.

7. The process as claimed in claim 1, wherein the H2S scavenger is metal carboxylate, triazine based scavengers, and aldehyde-based scavengers.

8. The process as claimed in claim 1, wherein the H2S scavenger is metal carboxylate.

9. The process as claimed in claim 1, wherein the radical quencher is butylated hydroxytoluene.

10. The process as claimed in claim 1, wherein the solubilizing agent is xylene and diluent is diesel.