FORM-2
THE PATENT ACT,1970
(39 OF 1970)
AND
THE PATENT RULES, 2003
(As Amended)
COMPLETE SPECIFICATION (See section 10;rule 13)
"A METHOD FOR MEASUREMENT OF SULPHUR IN PETCOKE FROM CRUDE OIL"
NAYARA ENERGY LIMITED, a corporation organized and existing under the laws of India, of 39 KM Jamnagar-Okha Highway, Vadinar, Dist Devbhoomi Dwarka, Gujarat, India.
The following specification particularly describes the invention and the manner in which it is to be performed:

Title: A method for measurement of sulphur in petcoke from crude oil.
Field of the invention:
The present invention relates to crude oil refining, more specifically to measurement of sulphur in petcoke, more specifically to measurement of sulphur in petcoke from crude oil, blend of crude oils, petroleum residues and blend of residues namely atmospheric residue, heavy heavy vacuum gas oil and vacuum residue samples.
Background of the invention:
Crude oil is fossil fuel extracted from earth. After exploration and cleaning process, crude oil mainly consists of a mixture of hydrocarbons and trace quantity of water and sediments. The mixture of hydrocarbons are broadly categorized into four groups of chemical components namely saturates, aromatics, resins and asphaltenes. The asphaltene molecules are mainly contribute to generate petcoke and remaining molecules generate liquid hydrocarbon yield. The petroleum refinery process different types of crude oils and produce valuable fuels namely Liquefied Petroleum Gas (LPG), Motor Spirit (MS), Aviation Turbine Fuel (ATF), Superior Kerosene Oil (SKO), Mineral Turpentine Oil (MTO), Diesel, Bitumen and Petroleum Coke.
The heavy heavy vacuum gas oil (HHVGO) and vacuum residue (VR) from crude distillation unit (CDU) feed to the delayed Coker unit (DCU) for further recovery of valuable distillate fuel by thermal cracking called delayed coking process. After thermal cracking solid residue remains in the coke drum is called Petcoke.
There are two grades of petcoke which are produced from crude oil namely fuel grade (high in sulphur and metal) and anode grade (low in sulphur and metal). Most of the petcoke specification demands for sulphur concentration is according to requirements of end use in each grade of petcoke. Generally, the sulphur concentration in petcoke product is estimated based on DCU feed sulphur concentration multiplied with a factor, which is derived based on experience. However, many a times sulphur concentration unable to control properly and cross the targeted concentration. Tthe sulphur in petcoke purely depends on individual crude chemical composition and it varies from crude to crude. Also, there is no perfect technique available to measure or predict sulphur in petcoke on the basis of crude oil or blend of crude oils or DCU feed. When sulphur concentration is found above specification limit in petcoke product, the crude oil refiner faces many problems (a) refiner cannot sell this off specification petcoke product to customers (b) it creates shortage of prime petcoke product against commitment to the customers (c) it needs extra storage facility and time to dispose the same. Hence to avoid high concentration of sulphur in petcoke product, refiner has to process low sulphur crude oils which ultimately leads to huge loss of profit. Above problems

of crude oil refiner could be avoided, if reliable technique or advance information of sulphur in petcoke is made available. The one-year trend of sulphur concertation in petcoke is presented in Figure 2, wherein many a times sulphur concentration crossed the target specification of seven percent. Also, many a time sulphur concentration is far below the targeted specification (less than 6.5 mass percent), this can be considered as quality give away which means that the refiner could have processed more quantity of sour crude oils. Also, sometimes sulphur concentration is observed to be less than five percent which means there is an opportunity to produce low sulphur grade of petcoke, which can give better price realization.
A literature survey was conducted, and no literature found that relates to the measurement of sulphur in petcoke produced from crude oil or DCU feed. Most of studies, till date, have been conducted to estimate or improve DCU liquid yields.
Therefore, need arises to develop reliable technique to measure or predict sulphur in petcoke from crude oil or DCU feed sample to address above problems of crude oil refiner.
Objectives of the invention:
The main object of this invention is to develop measurement method for sulphur in petcoke from crude oil or blend of crude oils or petroleum residue samples or blend of petroleum residue samples (DCU feed).
Another objective of the present invention is to develop correlation of sulphur content in petcoke produced from crude oil vs petcoke produced from petroleum residue vs DCU petcoke product sample, wherein the petcoke from different feed materials.
Another objective of the present invention is to develop prediction method to predict sulphur in petcoke from crude blend details.
Another objective of the present invention is to develop measurement method for sulphur in petcoke using any of standard technique.
Another objective of the present invention is to determine error in existing prediction method of sulphur in petcoke from DCU feed sulphur multiply with fix factor.
Another objective of the present invention is to generate advance information of sulphur content in petcoke (before processing of crude oil).
Another objective of the present invention is to reduce unplanned off specification petcoke production due to higher Sulphur concentration.

Another objective of the present invention is to reduce time of unplanned off specification petcoke production due to higher Sulphur concentration.
Another objective of the present invention is to have sharp control of sulphur concentration in petcoke to reduce quality give away.
Another objective of the present invention is to reduce requirement of extra storage space for off specification petcoke product.
Another objective of the present invention is to avoid short supply of prime petcoke product to regular customers.
Another objective of the present invention is to provide standard operating procedure (SOP) to the refining fraternity, research institutes, academic institute etc. for producing petcoke from crude oil, blend of crude oils, residue sample and blend of residue samples.
Summary of the invention
In order to achieve the aforementioned objectives, in an aspect the present invention provides a method of measurement of sulphur in petcoke comprising:
A. preparing petcoke from starting material comprising steps of:
• coking a weighed starting material under inert gas purging in a coking instrument;
• heating coking instrument to 500 ± 2°C for 60 to 90 minutes;
• cooling the coking instrument to less than 200°C;
• removal of coking container from the coking instrument to obtain sample;
• cooling the sample to room temperature to obtain petcoke which is weighed.
B. Determining petcoke yield in following manner:
% Petcoke Yield = Weight difference *100/Sample weight
C. Measuring sulphur content in obtained petcoke by ASTM D 4239 test method.
D. Prediction of sulphur in petcoke using crude blend details in following manner:
1) Find out the petcoke mass contribution of individual crude oil of crude blend in following
manner,
Crude oil petcoke mass contribution (A, B, C….) = (Crude oil % in blend X petcoke yield of crude oil)/100
2) Prediction of sulphur in petcoke of crude oil blend,
% sulfur in petcoke of crude oil blend = [A*AS + B*BS + C*CS…] / [A + B + C…]
where,
A, B, C …. are the petcoke mass contribution of individual crude oils in blend

AS, BS, CS …. are the sulphur in petcoke of individual crude oil
In an embodiment, the present invention provides a method wherein the starting material is crude oil or blend of crude oils or petroleum residue samples or blend of petroleum residue samples (DCU feed).
In an embodiment, the present invention provides a method wherein the coking is thermal coking equipment.
In an embodiment, the present invention provides a method wherein the coking container is stainless steel or metal or glass or any other suitable thermal coking vessel.
In an embodiment, the present invention provides a method wherein the inert gas is nitrogen and wherein the rate of purging is 550 to 650 ml/min flow.
In an embodiment, the present invention provides a method for prediction of sulphur in DCU petcoke product using crude blend details.
In an embodiment, the present invention provides a method wherein the method provides a
correlation of sulphur content in petcoke produced from crude oil vs petcoke produced from
petroleum residue vs DCU petcoke product sample, wherein the petcoke is from different feed
materials.
The performance of developed method was verified by using individual crude oil and blend of multiple crude oil prepared in laboratory. Also, correlation of sulphur in petcoke was established between crude oil vs vacuum residue (DCU Feed) vs DCU petcoke product. More than fifty different crude oils which are part of crude basket were tested and test results are included in crude oil assay report. The sulphur in petcoke of individual crude oil will be useful to prepare crude blend, predict sulphur in DCU petcoke product in advance from crude blend details and sharp control of petcoke sulphur, hence it will be helpful to avoid unplanned high sulphur in petcoke product, reduce quality give away of sulphur in petcoke and useful to produce low sulphur grade of petcoke. Since the invented technique is novel and applicable to global refining fraternity, it is envisaged that, the invented technique will be highly useful to sharp control of sulphur in petcoke by petroleum refinery. Test method will be also useful for crude oil quality control and research laboratories, and academic institutes.
Detailed description of the drawings:
The following drawings form part of the present specification and are included to further illustrate aspects of the present invention. The invention may be better understood by reference to the drawings in combination with the detailed description of the specific embodiments presented herein.

Figure 1: Block diagram of invented method
Figure 2: Trend of sulphur concentration in petcoke for one year.
Figure 3: Image of micro level petcoke generation equipment.
Figure 4: Image of M/s Alcor Make Micro Carbon Residue Tester (MCRT).
Figure 5: Image of micro level petcoke generated at Laboratory from crude oil or vacuum residue sample.
Figure 6: Image of M/s Leco make Sulphur analyzer.
It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter, and are therefore, not to be considered for limiting of its scope, for the subject matter may admit to other equally effective embodiments.
These and other features of the invention will become apparent from a consideration of the detailed description.
Detailed description of the invention:
The following description is provided to assist in a comprehensive understanding of exemplary embodiment of the invention. It includes various specific details to assist the understanding, but these are to be regarded as merely exemplary.
Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, description of well-known functions / constructions is omitted for clarity and consciousness.
Those skilled in the art will be aware that the invention described herein is subject to variations and modifications, other than those specifically described. It is to be understood that the invention described herein includes all such variations and modifications. The invention 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 two or more of said steps or features.
The present invention is not to be limited in scope by the specific embodiments described herein, which is intended for the purposes of exemplification only. Functionally equivalent products, compositions, and methods are clearly within the scope of the invention, as described herein.
For convenience, before further description of the present invention, certain terms employed in this specification, examples and appended claims are collected here. These definitions should be read

considering the remainder of the disclosure and understood as by a person of skill in the art. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by a person of ordinary skill in the art.
Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way or more other embodiment and/or in combination with or instead of the features of other embodiments.
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.
The terms “comprise” and “comprising” are used in the inclusive, open sense, meaning that additional elements may be included. It is not intended to be construed as “consists of only”.
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 element or steps but not the exclusion of any other element or step or group of element or steps.
The term “including” is used to mean “included but not limited to”. “Including” and “including but not limited to” are used interchangeably.
In an aspect, the present invention provides a method of measurement of sulphur in petcoke comprising:
A. preparing petcoke from starting material comprising steps of:
• coking a weighed starting material under inert gas purging in a coking instrument;
• heating coking instrument to 500 ± 2°C for 60 to 90 minutes;
• cooling the coking instrument to less than 200°C;
• removal of coking container from the coking instrument to obtain sample;
• cooling the sample to room temperature to obtain petcoke which is weighed.
B. Determining petcoke yield in following manner:
% Petcoke Yield = Weight difference *100/Sample weight
C. Measuring sulphur content in obtained petcoke by ASTM D 4239 test method.
D. Prediction of sulphur in petcoke using crude blend details in following manner:
1) Find out the petcoke mass contribution of individual crude oil of crude blend in following
manner, Crude oil petcoke mass contribution (A, B, C…..) = (Crude oil % in blend X petcoke yield of crude oil)/100

2) Prediction of sulphur in petcoke of crude oil blend :
% sulfur in petcoke of crude oil blend = [A*AS + B*BS + C*CS…] / [A + B + C…]
where,
A, B, C …. are the petcoke mass contribution of individual crude oils in blend
AS, BS, CS …. are the sulphur in petcoke of individual crude oil
In an embodiment, the present invention provides a method wherein the starting material is crude oil or blend of crude oils or petroleum residue samples or blend of petroleum residue samples (DCU feed).
In an embodiment, the present invention provides a method wherein the coking is by thermal coking.
In an embodiment, the present invention provides a method wherein the coking container is stainless steel or metal or glass or any other suitable thermal coking vessel.
In an embodiment, the present invention provides a method wherein the inert gas is nitrogen and wherein the rate of purging is 550 to 650 ml/min flow.
In an embodiment, the present invention provides a method for prediction of sulphur in DCU petcoke product using crude blend details.
In an embodiment, the present invention provides a method wherein the method provides a correlation of sulphur content in petcoke produced from crude oil vs petcoke produced from petroleum residue vs DCU petcoke product sample, wherein the petcoke is from different feed materials.
The detailed description of process is as mentioned below.
Step 1: To generate micro level petcoke from analysis sample at laboratory:
As per the Figure 2, micro level petcoke was generated at laboratory as mentioned below,
Preparation of Analysis Sample [1]:
Collect the analysis samples namely crude oil, blend of crude oil, vacuum residue or blend of residues (DCU feed) in a clean metal container and make it homogeneous at laboratory, if required. The individual analysis sample is processed through micro level petcoke generation equipment [2].
Petcoke Generation Equipment [2]:
The thermal coking equipment consist of SS coking vessel or quartz glass vials for sample, coking chamber, nitrogen purging and heating device to provide stable temperature of 500 ±2º C. Take

appropriate sample in pre weight coking vessel, record the sample weight, close the coking assembly and start the instrument. Stop the coking instrument and remove the coking vessel or vials from instrument after cooling. Cool the sample vessel further at room temperature and record the weight of vessel + solid residue called as micro level petcoke [3] generated. Alternately, Micro Carbon Residue Tester (MCRT) equipment comply to ASTM D 4530 test method requirement with 15 ml sample vials also can be used when sample is having above 10 mass percent petcoke. Calculate the % Petcoke Generation using formula, (Wt. of Petcoke X 100)/ Sample taken for coking. Figure 3 is image of micro level petcoke generation equipment and Figure 4 is Image of M/s Alcor Make Micro Carbon Residue Tester (MCRT) used for this experimental work.
Following detailed procedure was followed for petcoke generation:
• Weigh the empty and clean 200 ml steel sample container of coking instrument;
• Add sample amounts 18 to 20 gm to the nearest 0.01 gm into sample container;
• Close and tighten the sample container;
• Connect nitrogen inlet line and sample vapour line with sample container and tighten;
• Place the sample container in furnace;
• Connect nitrogen inlet line with nitrogen supply line and connect the sample vapour line with liquid receiver which is connected with condenser and exhaust line;
• Open nitrogen supply valve and set 550 to 650 ml/min flow;
• Start water supply in condenser;
• Set furnace temperature at 500 °C and run for 60 minutes;
• Stop the furnace heating and wait to cool down to less than 200°C;
• Disconnect nitrogen supply;
• Remove the sample container from furnace and allow to cool down at ambient temperature;
• Weight the sample container when it attends ambient temperature and calculate the petcoke yield using given formula;
% Petcoke Yield = Weight difference * 100/Sample weight
Micro Level Petcoke [3]:
The petcoke generated by coking equipment will be collected either from single run or multiple run is mixed thoroughly and used for measurement of sulphur. Approximately 250 mg of petcoke sample is required to test sulphur in duplicate or triplicate measurement. The petcoke generated through coking equipment is used for measurement of sulphur in petcoke of individual analysis sample. Figure 5 represent the image of micro level petcoke generated during this experimental work.
Step 2: To measure sulphur in petcoke generated at laboratory:
Measurement of petcoke sulphur using ASTM D 4239 test method [4]:

Test Method ASTM D 4239: Standard Test Method for Sulphur in the Analysis Sample of Coal and Coke Using High- Temperature Tube Furnace Combustion.
The sulphur measurement instrument consist of high temperature combustion furnace, oxygen gas arrangement, sulphur sensing detector, sample boat and automatic software control system. Prepare the sulphur measurement instrument as per standard operating procedure (SOP) and calibrate as per test procedure. Take appropriate weight of micro level petcoke [3] and feed to the sulphur measurement instrument comply with ASTM D 4239 [4] test method requirements. After completion of analysis instrument will generate automatic test report [5] for sulphur concentration in wt. %. Figure -6 is image of M/s Leco make Sulphur analyser used for this experimental work.
Analysis Report [5]:
After completion of analysis, the instrument software will automatically calculate sulphur concentration based on calibration graph & sample weight and display in software. Analyze all samples in duplicate and report average test results up to 0.1%.
The petcoke yield and sulphur in petcoke from individual crude oil are useful to develop prediction model for sulphur in petcoke at DCU of crude blend in following manner,
1) Find out the petcoke mass contribution of individual crude oil of crude blend using below
formula,
Crude oil petcoke mass contribution (A, B, C….) = (Crude oil % in blend X petcoke yield of crude oil)/100
2) Prediction of sulphur in petcoke of crude oil blend:
% sulfur in petcoke of crude oil blend = [A*AS + B*BS + C*CS…] / [A + B + C…]
where,
A, B, C …. are the petcoke mass contribution of individual crude oils in blend
AS, BS, CS …. are the sulphur in petcoke of individual crude oil
Experimental study work and test results:
Various laboratory scale experiments were conducted using samples namely crude oil, blend of crude oil, heavy heavy vacuum gas oil, vacuum residue and blend of residue (DCU Feed).
Following aspects were studied during this experimental work:
1) Development of method for measurement of sulphur in petcoke from analysis sample namely crude oil, blend of crude oil, heavy heavy vacuum gas oil, vacuum residue and blend of residue (DCU Feed).

2) Development of assembly to generate petcoke from analysis sample.
3) Generation of precision data for developed method.
4) Experimental work to check sulphur in petcoke from various crude oils.
5) Experimental work to check sulphur in petcoke from various blends of crude oil.
6) Experimental work to check sulphur in petcoke from various vacuum residue samples.
7) Experimental work to check sulphur in petcoke from various blend of vacuum residue.
8) Development of sulphur in petcoke correlation between crude oil vs vacuum residue (DCU Feed).
9) Development of sulphur in petcoke correlation between vacuum residue (DCU feed) vs actual petcoke produced at DCU.
10) Development of sulphur in petcoke correlation between crude oil vs actual petcoke produced at DCU.
11) Development of correlation between sulphur in petcoke from crude oil by MCRT instrument vs in-house developed thermal coking equipment.
12) Development of prediction model for sulphur in petcoke using crude blend details.
13) Development of sulphur correlation between vacuum residue and petcoke of crude oil.
14) Development of sulphur correlation between crude oil and petcoke of crude oil.
15) Determine the error in existing prediction model of sulphur in petcoke from DCU feed sulphur multiply with fix factor.
Details of Equipment and Materials Used for Experimental Work:
As per defined concept, micro level petcoke generation equipment set up done at laboratory for crude oil and petroleum residue samples, also test procedure established for measurement of Sulphur from micro level petcoke generated at laboratory. The equipment facility and measurement procedure are verified by experimental study work.
Analysis Samples: Different types of crude oils and residue samples were collected from M/s Nayara Energy petroleum refinery, Vadinar, Dist. Devbhoomi Dwarka, State - Gujarat, India.
Micro Level Petcoke Generation Equipment:

The micro level petcoke generation equipment set up done in the laboratory using muffle furnace as shown in figure-3, The equipment consist of SS coking vessel, coking chamber, nitrogen purging and heating device to provide stable temperature of 500 ±2º C. Alternately, Micro Carbon Residue Tester (MCRT) equipment comply to ASTM D 4530 test method requirement with 15 ml sample vials also can be used. The figure-4 represent the image of M/s Herzog make MCRT tester and figure-5 represent the image of micro level petcoke generated at laboratory.
Sulphur Measurement Instrument:
Sulphur measurement instrument comply to test method ASTM D 4239 “Standard Test Method for Sulphur in the Analysis Sample of Coal and Coke Using High- Temperature Tube Furnace Combustion “was used for measurement of sulphur in petcoke sample. The figure-5 represent the image of M/s Leco make sulphur analyser.
Other equipment used for experimental work are, analytical Balance capable to detect up to 0.01 mg weight, hot Plate to heat the residue samples, DCU petcoke grinding machine to prepare 250 micron sample for Sulphur test, sieve of different mesh / microns size, different types of sample containers etc.
Experimental Work:
Exp-1, Development of equipment for petcoke generation at laboratory:
Aim: To develop equipment for petcoke generation at laboratory for experimental work.
The petcoke generation equipment set up is done in the laboratory using muffle furnace as shown in Figure-3, The equipment consist of 200 ml capacity coking vessel make from stainless steel, coking chamber, nitrogen purging and heating device to provide stable temperature of 500±2ºC. Additionally, vapour cooling condenser provided to collect liquid fraction and gas routed to exhaust system. Total run time for each cycle was fixed for 60 minutes. Performance of developed system was verified using coker unit feed vacuum residue samples. DCU feed VR samples were collected on different date and tested in triplicate for petcoke yield using laboratory coking equipment. The petcoke yield found at laboratory was compared with simulated petcoke yield found at coker unit on same day. The observed test results of petcoke yield data are tabulated in below Table-1.
Table 1: Comparative petcoke yield data by simulation and lab thermal coking equipment

Simulated DCU Petcoke yield by
Sr. No. Sample Details Petcoke Yield, Lab Equipment,
Wt. % Wt. %
1 DCU- Feed VR -Dt.-08.04.21 33.7 28.38

2 DCU- Feed VR -Dt.-08.04.21 32.23
3 DCU- Feed VR -Dt.-08.04.21
29.8
4 DCU-Feed VR- Dt.-25.08.21 34.1 31.73
5 DCU-Feed VR- Dt.-25.08.21
31.85
6 DCU-Feed VR- Dt.-25.08.21
31.54
7 DCU-Feed VR- Dt.-08.09.21 32.6 32.83
8 DCU-Feed VR- Dt.-08.09.21
31.13
9 DCU-Feed VR- Dt.-08.09.21
31.24
Observation: From the Table-1 test results, it is observed that, petcoke yield using laboratory coking equipment is found very close to simulated petcoke yield of Delayed coker unit, hence equipment performance found to be satisfactory for petcoke generation at laboratory scale for experimental work.
Exp-2, Measurement of total sulphur in petcoke generated at laboratory:
Aim: To measure total sulphur in petcoke samples as per Test Method ASTM D 4239 and comparison of sulphur concentration in petcoke produced by MCRT instrument & by thermal coking equipment.
The test Method ASTM D 4239 (Standard Test Method for Sulphur in the Analysis Sample of Coal and Coke Using High- Temperature Tube Furnace Combustion) and instrument complying the requirements of test method is used for measurement of sulphur concentration. The petcoke generated at laboratory from different analysis samples by using in-house developed thermal coking equipment and by MCRT instrument were tested. The observed test results are tabulated in below Table-2.
Table 2: Test results of sulphur in lab petcoke generated by MCRT instrument and by Thermal Coking equipment.

Sample Details Sulphur in Petcoke Produced by MCRT Instrument Sulphur in Petcoke Produced by Thermal Coking Equipment
Llanos Crude Oil 3.84 3.78
Basrah Heavy Crude Oil 10.20 10.30
Napo Crude oil 3.83 3.82
DCU-Vacuum Residue 5.70 5.69
Ras Gharib Crude oil 5.96 6.01
Observation: From the table-2 test results, it is observed that, sulphur concentration can be easily measured by ASTM D 4239 for petcoke generated at laboratory either by MCRT instrument or by

thermal coking equipment developed in-house, also sulphur concentration found very close by both techniques hence both petcoke generation technique at laboratory scale is acceptable for further experimental work.
Exp-3, Precision data for developed test method
Aim: To generate precision (repeatability) data of developed test method.
The developed test method having two main steps viz petcoke generation and sulphur measurement by ASTM D 4239, hence various crude oil blend and vacuum residue samples were collected and tested in duplicate for both the steps. The observed test results with difference of results are tabulated in below Table-3.
Table 3: Precision data of developed test method.

Sr. No Sample Name Date & Time Petcoke Yield % Sulphur % in Petcoke

Test-1 Test-2 Diff. Test-1 Test-2 Diff.
1 DCU Feed-VR 07.12.20 24.5 24.6 -0.1 7.0 7.0 0.0
2
09.12.20 25.1 25.3 -0.2 7.0 7.0 0.0
3
10.12.20 24.8 24.9 -0.1 7.4 7.1 0.3
4
11.12.20 25.3 25.5 -0.2 7.5 7.2 0.3
5
12.12.20 26.0 26.2 -0.2 7.7 7.4 0.3
6
13.12.20 25.7 25.8 -0.1 7.9 7.6 0.3
7
17.12.20 23.8 23.7 0.1 7.4 7.3 0.1
8
19.12.20 23.2 23.4 -0.2 7.8 7.6 0.2
9
22.12.20 22.2 22.4 -0.2 7.2 7.0 0.2
11 Crude Blend from De-salter O/L-CDU-1 10.12.20 7.1 7.2 -0.1 6.9 6.6 0.3
12
11.12.20 7.5 7.5 0.0 7.8 7.5 0.3
13
12.12.20 7.8 7.8 0.0 7.8 7.5 0.3
14
13.12.20 8.6 8.5 0.1 8.2 7.8 0.4
15
14.12.20 7.9 7.8 0.1 8.2 7.9 0.3
16
16.12.20 7.7 7.8 -0.1 8.4 8.2 0.2
17
17.12.20 8.0 8.0 0.0 7.9 7.6 0.3
18
18.12.20 7.9 7.8 0.1 8.0 7.7 0.3
19
19.12.20 7.5 7.5 0.0 7.8 7.6 0.2
20
21.12.20 7.3 7.2 0.1 7.6 7.3 0.3
21
22.12.20 7.2 7.4 -0.2 7.6 7.3 0.3
22
23.12.20 7.5 7.8 -0.3 7.1 7.0 0.1

Observation: From the Table-3 test results, it is observed that, petcoke mass generation and sulphur measurement are quite repeatable and difference in test results are within precision limit of test method ASTM D 4239. Hence precision of developed method is considered to be same as standard test method ASTM D 4239.
Exp-4, Correlation of sulphur in petcoke between Delayed Coker Unit Feed (Vacuum Residue) and DCU petcoke product
Aim: To establish correlation of sulphur in petcoke between DCU Feed and petcoke product.
The DCU feed to petcoke product cycle time is approximately 16 hours. The correlation data will provide advance information of sulphur in DCU petcoke, hence it will be highly useful to control sulphur in DCU petcoke product as well as to minimize off specification petcoke production. To establish correlation of sulphur concentration between DCU feed (mixture of vacuum residue) and DCU petcoke product, both samples were collected on same dates. The DCU feed samples were processed at laboratory to produce petcoke and then tested for sulphur. The petcoke product samples collected from DCU were grinded at laboratory to prepare powder form and then tested for sulphur concentration using ASTM D 4239 test method. The observed test results are tabulated in below Table 4.
Table 4: Sulphur concentration in petcoke generated at lab from DCU Feed VR and Petcoke product sample from DCU.

Sample Details Sample Collection Date & Time % Sulphur in Petcoke Generated at Lab from DCU Feed VR % Sulphur in Petcoke from DCU
DCU Feed-VR 12.08.20 @ 13.00 hrs 6.6 6.4
DCU Feed-VR 14.08.20 @ 13.00 hrs 6.7 6.5
DCU Feed-VR 15.08.20 @ 13.00 hrs 6.8 6.9
DCU Feed-VR 18.08.20 @ 13.00 hrs 7.1 6.9
DCU Feed-VR 22.08.20 @ 13.00 hrs 7.0 6.8
DCU Feed-VR 24.08.20 @ 13.00 hrs 7.0 6.9
DCU Feed-VR 26.08.20 @ 13.00 hrs 7.0 6.9
DCU Feed-VR 02.09.20 @ 13.00 hrs 7.1 7.0
DCU Feed-VR 05.09.20 @ 13.00 hrs 7.1 6.9
DCU Feed-VR 09.09.20 @ 13.00 hrs 6.9 6.8

Observation: Form the Table 4 test results, it is observed that, sulphur concentration in petcoke produced from DCU feed VR at laboratory and petcoke product sample collected from DCU plant on same day are found very close. The difference of results is within precision limit of ASTM D 4239 test method. The test results of sulphur in petcoke produced from DCU feed is closely correlate with sulphur in actual DCU petcoke product, hence test results of sulphur in petcoke produced from DCU feed at lab can be useful to predict sulphur concentration of DCU petcoke in advance. This advance information of sulphur concentration can be highly useful to control sulphur concentration in actual petcoke.
Exp-5, Correlation of sulphur in petcoke produced from Crude Oil and Vacuum Residue
Aim: To establish correlation of sulphur in petcoke produced from crude oil and vacuum residue.
The crude oil is processed at atmospheric and vacuum distillation unit up to 560 °C to produce high value distillate products namely LPG, Naphtha, Kerosene, Diesel and vacuum gas oil. The HHVGO and VR is feed to the DCU for further production of distillates by thermal cracking. The crude oils blend preparation to VR generation time is approximately 14 hours hence total cycle time from crude oil blend preparation to DCU petcoke is approximately 30 hours.
To establish correlation of sulphur in petcoke produced from crude oil and vacuum residue samples, individual crude oil samples were collected from tank farm and processed to generated petcoke at laboratory and then petcoke tested for sulphur concentration, also the individual crude oils sample were processed first through true boiling point (TBP) instrument to produce vacuum residue samples above 560°C temperature, then VR samples were processed to generated petcoke at laboratory and then petcoke tested for sulphur concentration. The observed petcoke mass and sulphur in petcoke produced from individual crude oil and vacuum residue of same crude oil samples are tabulated in below Table-5.
Table 5: Test results of Petcoke mass and Sulphur in Petcoke produced from Crude Oil and VR samples.

Sample Name Crude Oil Vacuum Residue (> 560 °C)

Petcoke Yield % % Sulphur in Petcoke Petcoke Yield % % Sulphur in Petcoke
CL Crude Oil (R-598) 10.30 6.86 28.00 6.80
MA Crude Oil (R-603) 5.80 5.63 22.00 5.83
KB Crude Oil 9.00 6.90 24.00 6.80

(R-602)
Observation: From the Table 5 test results, it is observed that, petcoke mass in VR samples is found higher than crude oil due to recovery of distillates however sulphur concentration in petcoke produced from crude oil as well as vacuum residue sample found very close. The difference of results is within precision limit of ASTM D 4239 test method. The test results of sulphur in petcoke produced from crude oil and VR sample are closely correlate in all the three samples, hence test results of sulphur in petcoke produced at lab from crude oil or vacuum residue ( DCU Feed) can be useful to predict sulphur in petcoke product at DCU in advance. This advance information of sulphur concentration in petcoke will be highly useful to proper planning and control of sulphur in actual petcoke and to avoid 30 hours down time. Sulphur in petcoke of individual crude oil will be also useful to procurement of sour crude oil, preparation of crude blend, control of sulphur concentration in petcoke product and planning to produce low sulphur petcoke product to earn more profits.
EXp-6, Correlation of sulphur in petcoke produced from individual and blend of Crude Oil
Aim: To establish correlation of sulphur in petcoke produced from individual crude oil and blend of crude oil.
Most of recent crude oil refineries process blend of crude oils to earn more profit hence sulphur in petcoke correlation between individual crude oil and blend of crude oil is very important. For this experimental work, various blends of crude oils were prepared at laboratory. The individual crude oils and crude blends were tested for petcoke yield and sulphur in petcoke. The sulphur in petcoke of crude blend were theoretically calculated using mass percent of crude oil in blend, mass percent of petcoke yield of individual crude oil and sulphur in petcoke of individual crude oils as per developed prediction method. All the observed and calculated test results are tabulated in below Table-6.
Table 6: Test results of sulphur in petcoke from crude blend

Observed
Petcoke Sulphur Petcoke Calculated Sulphur
Yield of in Yield of Sulphur in in
Crude Blend Detail Crude Petcoke Crude Petcoke Petcoke
Oil [A] of Crude Blend of Crude of Crude
Oil [B] [C] Blend [D]
Blend [E]
Sr. Crude Oil
% wt. % wt. % wt. % wt. % wt. % wt.
No. Name

1 2 Maya 20.31 13.8 7.9 8.60 6.97 6.75

Oman 29.81 4.6 5.65

Merey-16 20.00 11.17 4.79

Basrah light 29.88 6.2 9.15

South Ratqa 18.18 11.6 10.52 7.40 7.81 7.4

Murban 15.84 1.5 4.52

Dubai 17.24 4.47 5.22

Basrah Heavy 18.51 9.4 10.5

Ras Gharib 14.77 10 5.96

Mangala 15.46 4.21 0.32

Observation: Form the Table 6 test results, it is observed that, sulphur in petcoke from crude blends [E] is closely matching with theoretically calculated Sulphur in petcoke [D] from crude blend details and the difference of results are within precision limit of ASTM D 4239 test method, hence these test results of sulphur in petcoke produced from crude blend can be useful to predict sulphur in petcoke at DCU petcoke product in advance. This advance information of sulphur concentration in petcoke will be highly useful for preparation of crude blend, control of sulphur in actual petcoke product and to avoid 30 hours off specification petcoke product with respect to high sulphur. The thirty hours’ time duration is calculated basis starting of crude blend processing to generation of petcoke product at DCU.
Exp-7, Correlation of sulphur content between vacuum residue and petcoke
Aim: To establish correlation of sulphur content between vacuum residue and petcoke of crude oils.
Currently, many of crude oil refiner are predicting sulphur in petcoke product by using sulphur concentration of DCU feed and multiply with fix factor in the range of 1.3 to 1.5 which is derived based on experience. For this experimental work, the part of selected crude oils are processed at laboratory to generate vacuum residue above 530°C using true boiling point (TBP) system and then vacuum residue samples were tested for Sulphur content [A], also the part of selected crude oils are processed to generate petcoke at laboratory and then petcoke tested for Sulphur content [B]. The observed test results of sulphur in vacuum residue samples and sulphur in petcoke produced from crude oils are tabulated in below table. Also the ratio of sulphur in vacuum residue and petcoke was calculated and presented in below Table-7.
Table 7: Sulphur in vacuum residue of crude oil and petcoke of crude oil and ratio.

Name of Crude Oil % Sulphur in Vac. Residue of Crude oil [A] % Sulphur in Petcoke of Crude oil [B] Ratio
Sulphur
[B]/[A] of =
AEL 2.6 5.0 1.92
CAS 3.0 3.9 1.30
CPB 1.7 4.7 2.76
QAL 3.7 7.1 1.92
RAG 4.7 6.0 1.28
RO1 1.0 0.7 0.70
DAS 3.1 6.5 2.10
RA1 3.8 5.1 1.34
RAT 6.4 9.6 1.50
MAN 0.1 0.2 2.0
Observation: From the test results of Table 7, it is observed that, ratio of % sulphur in petcoke of crude oil to vacuum residue of crude oil is widely vary and found 0.70 minimum in RO1 crude oil and 2.76 maximum in CPB crude oil. The RAG is having higher sulphur in vacuum residue compared to QAL but QAL is having very high sulphur in petcoke. This will miss guide operator to control high sulphur in petcoke. Hence it is proved that, prediction of sulphur using vacuum residue sulphur data is incorrect and not advisable.
Exp-8, Correlation of sulphur content between crude oil and petcoke of crude oil
Aim: To establish correlation of sulphur content between crude oil and petcoke of crude oil.
This experimental work is conducted to support above experiment-7. For this experimental work, various crude oils used in experiment-7 are tested for sulphur concentration. The observed test results of sulphur in crude oil and sulphur in petcoke produced from same crude oils are tabulated in below table. Also the ratio of sulphur in petcoke and Sulphur in crude oil was calculated and presented in below Table 8.
Table 8: Sulphur in crude oil and petcoke produced from crude oil and ratio.

Crude Name % Sulphur in Crude Oil [A] % Sulphur in
Petcoke of Crude
Oil [B] Ratio of Sulphur = [B]/[A]
AEL 0.81 5.0 6.17
CAS 1.89 3.9 2.06
CPB 0.60 4.7 7.83

QAL 1.28 7.1 5.54
RAG 3.36 6.0 1.79
RO1 0.6 0.7 1.17
DAS 1.13 6.5 5.75
RA1 2.35 5.1 2.17
RAT 3.65 9.6 2.63
MAN 0.08 0.2 2.50
Observation: Form the test results of Table 8, it is observed that, ratio of sulphur of petcoke to
crude oil is widely vary and found 1.17 minimum in RO1 crude oil and 7.83 maximum in CPB crude
oil. Hence above data are also not useful to predict Sulphur in petcoke from crude oil Sulphur
content.
Conclusion:
Following conclusions can be drawn from the test results and observations of above experimental work:
1) Experiments-1: performance of thermal coking equipment developed for petcoke generation from crude oil and vacuum residue sample is found satisfactory and useful for experimental work.
2) Experiment-2: Petcoke generated from crude oil or vacuum residue sample using thermal coking equipment or MCRT instrument is easily possible to test by ASTM D 4239 test method.
3) Experiments 1, 2 and 3: developed test method for measurement of sulphur in petcoke from crude oil, blend of crude oil and vacuum residue sample is found quite accurate and precision (repeatability) found close to the precision of standard method ASTM D 4239.
4) Experiments 4, 5 and 6: sulphur in petcoke generated from crude oil and vacuum residue is closely matching with DCU petcoke sample, hence sulphur in petcoke test results of vacuum residue and crude oil are highly useful to prepare crude blend and control the sulphur concentration in petcoke product at DCU.
5) Test results of sulphur in petcoke from crude oil and petcoke yield of crude oil is useful to develop sulphur in petcoke prediction model from crude oil blend.
6) Experiment 7: sulphur ratio of petcoke to vacuum residue is widely varying from 0.75 to 2.8 in different crude oils, which looks to be inherent property of crude oils. Hence prediction of petcoke sulphur using fix factor multiply with vacuum residue sulphur is incorrect method.

7) Experiment 8: sulphur ratio of petcoke to crude oil is also widely varying from 1.2 to 7.8 in different crude oils, which is in line with experiment -7, hence it is also not useful to predict petcoke sulphur.
8) Experiment 7 and 8 confirm the incorrectness of existing practice is being used to predict sulphur in petcoke product from DCU feed sulphur concentration and data is supporting to the problems facing by refiner.
Advantages of the invention:
The present invention is globally applicable to crude oil petroleum refining industries for measurement of sulphur in petcoke from crude oil and vacuum residue samples. Furthermore, present invention useful to prepare crude oil blend, predict and control the sulphur in delayed cocker petcoke product. Present invention also useful to evaluate, procure and process sour crude oils to earn more profits, hence present invention has many benefits to crude oil refining industries. Based on various experimental test results and observations, following benefits are envisaged:
1) Invented method is capable to measure sulphur in petcoke from crude oil, blend of crude oils and residue samples viz atmospheric residue, vacuum residue and blend of residue (DCU feed) samples.
2) Invented method is providing prediction method for sulphur in petcoke from crude oil blend details.
3) Invented method has very good correlation between sulphur in petcoke measured from crude oil, vacuum residue (Delayed Coker unit feed) and actual petcoke produced at DCU.
4) Invented method is capable to measure petcoke production from crude oil, blend of crude oils and vacuum residue samples.
5) Invented method is capable to produce accurate test results and has precision level very close to standard test method.
6) Invented method is technically sound and easy to implement.
7) Invented method is capable to provide advance information of sulphur concentration in petcoke (before processing of crude oil).
8) The advance information of sulphur in petcoke of crude oil blend will be useful to control sulphur concentration in delayed coker petcoke product and reduce 30 hours of unplanned off specification petcoke product.

9) The advance information of sulphur in petcoke of crude oil blend will be useful to reduce quality give away.
10) The advance information of sulphur in petcoke of individual crude oil will be useful for selection, procurement and processing of sour crude oil which are cheaper hence help to earn more profit margin.
11) The advance information of sulphur in petcoke of individual crude oil will be useful to plan and produce low sulphur grade petcoke for better price realization.
12) Invented method will reduce off specification petcoke production hence will reduce product evacuation problem and reduce requirement of extra storage space for off specification petcoke.
13) Invented method will reduce off specification petcoke production hence will reduce chance of short supply of prime petcoke product to the regular customers.
14) Invented test has been implemented at Nayara Energy Ltd for internal use. More than fifty different crude oils which are part of refining crude baskets were tested for sulphur in petcoke and test results were included in TBP crude assay report for further use for crude blend preparation. Also prepared prediction model for sulphur in petcoke from crude oil blend details.
Looking to the above multiple benefits of invented method, it is envisaged that the method of present invention will be highly useful for petroleum refining fraternity, research laboratories, academic institutes, crude oil trading agencies etc.
Although the invention has been described with reference to specific 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 invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore, contemplated that such modifications can be made without departing from the spirit or scope of the present invention as defined.

We claim
1. A method of measurement of sulphur in petcoke from crude oil comprising:
A. Preparing petcoke from starting material comprising steps of:
• coking a weighed starting material under inert gas purging in a coking instrument;
• heating coking instrument to 500 ± 2°C for 60 to 90 minutes;
• cooling the coking instrument to less than 200°C;
• removal of coking container from the coking instrument to obtain sample;
• cooling the sample to room temperature to obtain petcoke which is weighed.
B. Determining petcoke yield in following manner:
% Petcoke Yield = Weight difference *100/Sample weight
C. Measuring sulphur content in obtained petcoke by ASTM D 4239 test method.
D. Prediction of sulphur in petcoke using crude blend details in following manner:
1) Find out the petcoke mass contribution of individual crude oil of crude blend in
following manner,
Crude oil petcoke mass contribution (A, B, C…) = (Crude oil % in blend X petcoke yield of crude oil)/100
2) Prediction of sulphur in petcoke of crude oil blend :
% sulfur in petcoke of crude of blend = [A*AS + B*BS + C*CS…] / [A + B + C…]
where,
A, B, C …. are the petcoke mass contribution of individual crude oils in blend
AS, BS, CS …. are the sulphur in petcoke of individual crude oil
2. The method as claimed in claim 1, wherein the starting material is crude oil or blend of crude oils or petroleum residue samples or blend of petroleum residue samples (DCU feed).
3. The method as claimed in claim 1, wherein the coking is thermal coking.
4. The method as claimed in claim 1, wherein the coking container is stainless steel or metal or glass or any other suitable thermal coking vessel.
5. The method as claimed in claim 1, wherein the inert gas is nitrogen and wherein the rate of purging is 550 to 650 ml/min flow.
6. The method as claimed in claim 1, wherein the method is prediction method for sulphur in DCU petcoke product using crude blend details.

7. The method as claimed in claim 1, wherein the method provides a correlation of sulphur content in petcoke produced from crude oil vs petcoke produced from petroleum residue vs DCU petcoke product sample, wherein the petcoke is from different feed materials.