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The market value of a crude stream reflects its quality characteristics. The market value of an individual crude stream reflects its quality characteristics which is either characterized as sweet or sour. Crude oils that are sweet (low sulfur content) are usually priced higher than sour crude oils. This study analyzed of PNA, Assay-Data Cut-Yield, True boiling-point curve and sulfur content in selected sour crude oil in the world. A 2-stage Claus Process unit was used to determine the amount of sulfur left in the crude oil and ascertain if it will meet up to the market requirement standard (≤0.5%). Assay-Data Cut-Yield and True boiling-point analysis shows that the result from this study is in the range of the FSC 432: Petroleum Data. After the simulation the following results were achieved; Maralago—2012 (0.233%), Kearl—2014 (0.247%), Soroosh—2006 (0.271%), Basrah light—2014 (0.218%), Kuwait—2015 (0.201%), Maya—2015 (0.362%), and Ratawi—2010 (0.301%).
Department of Construction and Drilling, Saudi Petroleum Services Polytechnic (SPSS), Dammam, Saudi Arabia
*Address all correspondence to: abiodunadeyemi88@gmail.com
1. Introduction
Desulfurization is one of the most important crude oil treatments that should be carried out before crude oil processing as sulfur is considered an undesirable contaminant. The presence of sulfur in the crude oil leads to reduction of combustion efficiency and high level of pollution emission in the oil and gas activities [1]. Crude oil classified by the New York Mercantile Exchange as sweet when they contain less than 0.5% sulfur and sour when they include more sulfur. Sulfur or sulfur components are component that must be removed from oil through refining operations in order for it to be classified as sweet. Most oil and gas reservoirs contain between 1 and 5% sulfur [2].
There are various standard methods use measuring sulfur; wet chemistry, X-ray flouresence, atomic spectroscopy and various thermal combustion methods, the most common measurement method is the ASTM test methods which includes the following D 2622, D 5453 and D 7039 [3]. Hydrodesulphurization method is also one of the methods that has shown effective removal of sulfur from light fuels such as diesel, Figure 1 shows the process flow diagram of the hydrodesulphurization process [1].
Figure 1.
Process flow diagram of the hydrodesulphurization process [1].
Environmental Protection Agency made it mandatory for removal of sulfur from crude oil/petroleum products due to the effect it causes in the environment, effects on human skin, eyes as well as causing breathing problems [4]. High percentage of refineries uses the Claus Process as a process for the removal of sulfur from crude oil, it is also a popular engineering process of retrieving sulfur and energy from gases [4]. The schematic shown in Figure 2 is the process flow Claus Process from Aspen Plus.
Figure 2.
Aspen plus process flow diagram of a Claus Process [4].
Numerous research has been carried out for the removal of sulfur from light fuels, heavy fuels, and gases using the Claus Process; [4, 5, 6] and using the hydrodesulphurization process; [1, 7, 8, 9].
Sulfur content and density are two of the most significant quality factors. Density might be light or heavy, and the flavor of the sulfur can be either sweet or sour. The crude oils shown in the graph are selection of some of the crude oils sold around the world. Some crude oils fall inside and outside of the charted range of API gravities [10].
The price of light, sweet, low-sulfur crude oils is typically greater than the price of heavy, sour crude oils due to their higher degrees of API gravity and lower density. This is partially due to the fact that light sweet crude oil can normally be processed more quickly and inexpensively to generate gasoline and diesel fuel, which typically sell at a large premium to residual fuel oil and other “bottom of the barrel” items. Because they may be processed using significantly less sophisticated and energy-intensive processes/refineries, the light sweet grades are preferred. Select crude varieties from around the world are represented in the figure along with their respective sulfur content and density properties [10] (Figure 3).
Figure 3.
Quality of selected crude oil in the world [10].
There are 3 major types of crude oil in the world [2];
WTI—it is classified as sweet and light crude with sulfur content of 0.24%, API gravity of 39.6 and produced in the United States.
BRENT—it is classified as sweet and light crude with sulfur content of 0.37%, API gravity of 38.3 and it is extracted from the North Sea.
OPEC—this tends to be heavier and sour than WTI and Brent Crude.
According to research, there have been tremendous advancements in sulfur contents of crude oil in recent and past times. In this report, selected sour crude oil samples was analyzed to determine the amount of sulfur content in sour crude oil that was recovered from a desulfurization simulation that was carried out in Aspen Hysys V11.
This study covers the analysis of selected sour crude oil samples; Maralago—2012, Kearl—2014, Soroosh (Cyrus)—2006, Basrah light—2014, Kuwait—2015, Maya—2015, and Ratawi—2010 which are gotten from Aspen Hysys petroleum Assay as presented in Table 1. The analysis was carried out from a 2 stage Claus Process unit already simulated in Aspen Hysys V11/examples in order to determine the amount of sulfur left in the crude oil and ascertain if it will meet up to the market requirement standard (less than or equal to 0.5%) as presented in Figure 4. The PNA (P—paraffin, N—naphthenes and A—aromatic) analysis was carried out on the selected sour crude oil.
Field name
Location
Sulfur content (%)
Maralago—2012
Venezuela
3.174
Kearl—2014
Canada
3.382
Soroosh (Cyrus)—2006
Iran
3.521
Basrah light—2014
Iraq
3.070
Kuwait—2015
Kuwait
2.702
Maya—2015
Mexico
5.091
Ratawi—2010
Saudi—Kuwait Neutral Zone
4.104
Table 1.
Sour crude oil samples.
Figure 4.
PFD of 2 stage Claus Process (Aspen Hysys V11/examples).
Figure 5 consist of the various selected sour crude feed from Aspen Hysys petroleum Assay.
Figure 5.
Selected sour crude feed.
The simulation above utilizes one thermal stage (furnace, waste heat exchanger, & condenser) and 2 catalytic stages (reheater, converter, and condenser) to remove elemental sulfur from the various sour crude as presented in Table 1.
The reaction furnace is utilizing the “Straight Through Amine Acid Gas” model and is operating at 114°C with an air supply rate set to achieve 0% air demand (2:1 ratio of H2S:SO2 after last condenser). After the catalytic stages, a cumulative conversion of 97.0% was achieved (96.8% recovered).
This section provides an analysis of the results of the selected crude oil samples from the hysys simulation. The analysis are presented as follows:
3.1 Venezuela—Maralago—2012
Maralago—2012 crude contains high sulfur content of 3.174% and a density of 923.4224 kg/m3. Figure 6 represent the PNA analysis (weight against temperature) of Maralago—2012 crude. It shows that the paraffin experienced a stable decrease in weight at a temperature range of 0–500°C, naphthenes experienced an increase in weight at a temperature range 0f °C to 270°C and at a weight of 44% the temperature increase uniformly at a range of 450–1050°C, Aromatics experienced an increase in weight at a temperature range of 0–450°C and at a weight of 55% the temperature increase uniformly at a range of 500–1050°C.
Figure 6.
Maralago 2012 PNA graph.
3.2 Canada—Kearl—2014
Kearl—2014 crude contains high sulfur content of 3.382% and a density of 914.9311 kg/m3. Figure 7 represent the PNA analysis (weight against temperature) of Kearl—2014 crude. It shows that the paraffin experienced a stable decrease in weight at a temperature range of 0–620°C, naphthenes experienced an increase in weight at a temperature range of 0–300°C and at a weight of 60–15% it experienced a decrease in temperature at a range of 300–680°C and at a constant weight of 15% the temperature increase uniformly at range of 800–1000°C, aromatics experienced an increase in weight at a temperature range of 0–680°C and at a weight of 87% the temperature increase uniformly at 780–1000°C.
Figure 7.
Kearl—2014 PNA graph.
3.3 Iran—Soroosh (Cyrus)—2006
Soroosh (Cyrus)—2006 crude contains high sulfur content of 3.521% and a density of 939.3213 kg/m3. Figure 8 represent the PNA analysis (weight against temperature) of Soroosh (Cyrus)—2006 crude. It shows that the paraffin experienced a stable decrease in weight at a temperature range of 0–470°C, naphthenes experienced an increase in weight at a temperature range of 0–150°C and at a constant weight of 40% the temperature increase uniformly at a range of 580–1200°C, aromatics experienced an increase in weight at a temperature range of 0–520°C and at a weight of 60% it experienced a stable temperature at 520–1200°C.
Figure 8.
Soroosh (Cyrus)—2006 PNA Graph.
3.4 Iraq—Basrah light—2014
Basrah light—2014 crude contains high sulfur content of 3.070% and a density of 876.2441 kg/m3. Figure 9 represent the PNA analysis (weight against temperature) of Basrah light—2014 crude. It shows that the paraffin experienced a stable decrease in weight at a temperature range of 0–498°C, naphthenes experienced an increase in weight at a temperature range of 0–300°C, and aromatics experienced an increase in weight at a temperature range of 0–500°C.
Figure 9.
Basrah light—2006 PNA graph.
3.5 Kuwait—Kuwait—2015
Kuwait—2015 crude contains high sulfur content of 2.702% and a density of 876.2441 kg/m3. Figure 10 represent the PNA analysis (weight against temperature) of Kuwait—2015 crude. It shows that the paraffin experienced a stable decrease in weight at a temperature range of 0–550°C, naphthenes experienced an increase in weight at a temperature range of 0–300°C, and aromatics experienced an increase in weight at a temperature range of 0–1200°C.
Figure 10.
Kuwait—2015 PNA graph.
3.6 Mexico—Maya—2015
Maya—2015 crude contains high sulfur content of 3.379% and a density of 919.8750 kg/m3. Figure 11 represent the PNA analysis (weight against temperature) of Maya—2015 crude. It shows that the paraffin experienced a stable decrease in weight at a temperature range of 0–480°C, naphthenes experienced an increase in weight at a temperature range of 0–500°C and aromatics experienced an increase in weight at a temperature range of 0–500°C.
Figure 11.
Maya—2015 PNA graph.
3.7 Saudi—Kuwait Neutral Zone—Ratawi—2010
Ratawi—2010 crude contains high sulfur content of 4.104% and a density of 905.0673 kg/m3. Figure 12 represent the PNA analysis (weight against temperature) of Ratawi—2010 crude. It shows that the paraffin experienced a stable decrease in weight at a temperature variation of 0–480°C, naphthenes experienced an increase in weight at a temperature range of 0–140°C and aromatics experienced an increase in weight at a temperature range of 0–490°C.
Figure 12.
Ratawi—2010 PNA graph.
The comparison of the selected sour crude of this study is shown in Figure 13. Aromatic base crude of Ratawi—2010 crude oil attained the highest weight percentage, and the Naphthalene Base Crude Oil Of Ratawi—2010 crude oil has the lowest weight percentage at a low temperature. At a high temperature range of 600–1200°C, the selected sour crude of this study experienced a various constant weight (%) of the paraffin, naphthalene and aromatic base crude at different temperature range except Kuwait—2015 crude which has the lowest sulfur content of 2.702%.
Figure 13.
PNA graph of selected sour crude.
Data on the characteristics and composition of crude oils are gathered in a crude oil assay. The cut yield against assay data details on whether crude oil is suitable for a specific refinery and estimates the necessary product yields and quality. Additionally, it suggests how thoroughly a specific crude oil should be processed in a refinery to provide fuels that adhere to environmental requirements. Figure 14 shows the cut points of the various selected sour crude of this study, the simulation from this study cut points is in the range of the FSC 432: Petroleum Data as presented in the Table 2.
Cut points of selected sour crude oil distillates fractions.
The first process in the refinery, separates the crude oil into fractions based on boiling points, which is basically the distillation process. Figure 15 shows the boiling point temperature points against weight of the various selected sour crude oil. As per the FSC 432: Petroleum Data [11], the lower boiling point Ta has a percentage weight of 10%, upper boiling point that Tb has a weight % range from 20 to 60% and the end point Te has weight of 100%. The initial boiling point Ti which is at the range of 70–110°C as shown in table, the middle and final boiling point of this study which is in weight range of 5–95% and at a temperature range of 110–1000°C and the end boiling point of 1200°C and a weight of 100% which is In accordance with the FSC 432: Petroleum Data [11].
Figure 15.
True boiling point curve analysis.
After the complete simulation of the 2 stage Claus Process with aim of recovering the sulfur content from the system and also determining amount left in crude. Table 3 contains the amount of sulfur left in the various selected crude in this study, which shows that the amount of sulfur left is various selected crude are below 0.5% as per standard.
This study focus on the analysis of selected sour crude oil in the world; Maralago—2012, Kearl—2014, Soroosh (Cyrus)—2006, Basrah light—2014, Kuwait—2015, Maya—2015, and Ratawi—2010 which are gotten from Aspen Hysys petroleum Assay as presented. The analysis was carried out from a 2 stage Claus Process unit already simulated in Aspen Hysys V11/examples in order to determine the amount of sulfur left in the crude oil and ascertain if it will meet up to the market requirement standard (less than or equal to 0.5%). Furthermore, the following analysis was carried out; PNA, Assay Data Cut Yield, True boiling point curve.
PNA (paraffin, naphthenes and aromatic) analysis shows that aromatic base crude of Ratawi—2010 crude oil attained the highest weight percentage, and the Naphthalene base crude oil of Ratawi—2010 crude oil has the lowest weight percentage at low temperature. At a high temperature range of 600–1200°C, the selected sour crude of this study experienced a various constant weight (%) of the paraffin, naphthalene and aromatic base crude at different temperature range except Kuwait—2015 crude which has the lowest sulfur content of 2.702%.
Assay Data Cut Yield analysis shows that the cut points of the various selected sour crude of this study is in the range of the FSC 432: Petroleum Data.
True boiling point analysis shows that the initial boiling point Ti which is at the range of 70–110°C, the middle and final boiling point of this study is in weight range of 5–95% and at a temperature range of 110–1000°C and the end boiling point is at a temperature 1200°C and a weight of 100% which is in accordance with the FSC 432: Petroleum Data.
Each of the selected crude oil was used as a feed in the 2 stage Claus Process simulation with aim of recovering the sulfur content from the system and also determining amount left in crude. After the simulation the following results were achieved; Maralago—2012 (0.233%), Kearl—2014 (0.247%), Soroosh—2006 (0.271%), Basrah light—2014 (0.218%), Kuwait—2015 (0.201%), Maya—2015 (0.362%), and Ratawi—2010 (0.301%). The selected crude are below required standard.
Adeyemi, MA, contributed to the final version of this manuscript, formal analysis, wrote the first draft, reviewed and edited the first and final manuscript drafts and did research conceptualization, theoretical framework, and supervision.
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Written By
Majid Abiodun Adeyemi
Submitted: 10 September 2023Reviewed: 16 October 2023Published: 10 May 2024
Open access peer-reviewed chapter - ONLINE FIRST
