CCQTA Chlorides in Crude Oil

Summary

This video explores the complexities of measuring inorganic and organic chlorides in crude oil, emphasizing the challenges faced in refinery operations. It covers the sources of chlorides, including cross-contamination and slop treatment practices, and highlights the difficulties in accurately detecting chlorides using traditional methods. The script also discusses a postulated link between organic chlorides and refinery corrosion, cautioning against assumptions in chloride data interpretation. With case studies and insights on test method limitations, the video provides a thorough understanding of chloride analysis in crude oil and its impact on refinery operations.

Takeaways

• 😀 The presence of chlorides, both inorganic and organic, in crude oil can significantly affect refinery operations and cause corrosion issues in crude units.
• 😀 The D4929 test method for measuring chlorides can sometimes produce false positives, especially when Napa content is low, making interpretation difficult.
• 😀 Organic chlorides, while suggested to contribute to crude unit corrosion, have not been directly identified or measured in crude oils, with most correlations made by inference.
• 😀 The challenge in detecting chlorides lies in the complex crude oil matrix, where salts like 'Smarties' (oil-coated solids) can evade detection and cause measurement discrepancies.
• 😀 Some salts in crude oils, especially crystalline salts, are resistant to water extraction and may not be detectable with traditional test methods, requiring alternative approaches like refluxing with toluene and water.
• 😀 A significant amount of chloride contamination comes from inorganic salts such as sodium, calcium, and magnesium chlorides, which are common in crude oil and contribute to corrosion.
• 😀 Corrosion in refineries can sometimes be attributed to chloride contamination, but accurate identification of the chloride source is crucial to resolving such issues.
• 😀 There is a need for more advanced sampling and testing methods to accurately detect both inorganic and organic chlorides, including the use of X-ray diffraction (XRD) for crystallized salts.
• 😀 Modeling chloride content in crude overheads is challenging due to the variability in factors like salt distribution, wash water effectiveness, and crude oil composition, which complicates predictive accuracy.
• 😀 Despite theories about hydrolyzable organic chlorides being a potential source of corrosion, inorganic chloride sources, such as those from salt hydrolysis, remain more likely explanations for chloride-induced issues in crude towers.

Q & A

What is the main focus of the video?

The video discusses the challenges and methods of measuring chlorides in crude oil, with a particular emphasis on the differences between inorganic and organic chlorides, their impact on refining processes, and the complexities of chloride detection and analysis.

What are the two types of chlorides discussed in the video?

The video covers inorganic and organic chlorides, explaining their different behaviors, measurement methods, and impact on crude oil refining.

How does the conductivity test method work in measuring chlorides in crude oil?

The conductivity test method measures the salt content in crude oil based on the ability of the sample to conduct electricity, which correlates with the concentration of dissolved salts, typically inorganic chlorides.

What was the discrepancy observed between the salt content at refineries and production sites in the case study from the early 1990s?

In the 1990s case study, salt content at refineries was consistently higher than at the production sites, even though both used the same conductivity test method. This was later attributed to undetected oil-coated solids (Smarties) that dissolved partially during transport, complicating chloride measurement.

What role do organic chlorides play in crude unit corrosion?

Some studies have postulated that hydrolyzable organic chlorides in crude oil contribute to crude unit corrosion, although no direct identification or measurement of these chlorides has been made. The connection is often inferred from discrepancies between chloride levels in crude oil and overhead boot water.

What are the challenges associated with measuring inorganic chlorides in crude oil?

Inorganic chlorides in crude oil can be difficult to measure because they often exist as salts that are not soluble in water, such as asphaltene-coated salts. This makes them resistant to extraction and challenging to detect using traditional methods.

What methods are used to detect and measure chlorides in crude oil?

Common methods include the D4929 test for chloride content, which measures inorganic chlorides, and techniques like XRF analysis and water washing to detect and quantify chloride presence. Additionally, sample preparation methods like refluxing with toluene and water are used to improve detection accuracy.

Why is there a need for caution when interpreting chloride data in crude oil?

Caution is necessary because the detection of chlorides can be influenced by various factors, such as the presence of undetected salts, the effectiveness of extraction methods, and the assumptions used in modeling chloride content. False positives are possible, especially when chloride levels are low, but false negatives are unlikely.

What are the limitations of models used to predict chloride content in crude oil?

Models used to predict chloride content often rely on assumptions about salt distribution, the effectiveness of desalting, and the impact of factors like acid content. These assumptions can lead to inaccuracies, making the models less reliable for real-world scenarios.

What is the primary takeaway regarding the presence of organic chlorides in crude oil?

While organic chlorides have been linked to corrosion in some studies, no specific hydrolyzable organic chlorides have been identified in crude oils. The presence of such chlorides is often inferred from discrepancies in chloride levels, rather than directly measured, which makes conclusions about their impact on corrosion uncertain.