Advancing Cooking Safety: Insights from the Fatigue Dashboard

Modified on Fri, 7 Jun at 11:56 AM

Introduction

What is a Coke Drum?

The Coke Drum, a central component of the Delayed Coking Unit, plays a crucial role in the oil and gas industry by transforming heavy crude oil residues into higher-value products like gasoline and diesel. This process involves extreme thermal cycling, which subjects the drum to severe operational stress, making it a critical piece of equipment in refining operations.

Figure 1: A representation of a Coke Drum asset.

What can go wrong?

In the oil and gas industry, coke drums face significant challenges due to fatigue, which severely impacts their operational longevity and safety. This is due to the channeling during a quenching procedure of the Coke Drum. This helps the asset cool down, but it also create localized hotspots for stress, if left uncheck this can cause fatigue over time.

This fatigue is primarily driven by thermal and mechanical stress cycles, including extreme thermal fluctuations and varying operational pressures, which can lead to stress accumulations and the initiation of cracks. The cumulative effect of these conditions poses a critical risk to the structural integrity of coke drums, necessitating thorough assessment and management strategies to prevent failures.

Figure 2: Coking challenges.

The problems plaguing the structure includes:

Thermal Fatigue: Repeated thermal cycling from the coking process induces thermal fatigue, where variations in temperature cause expansion and contraction of the drum material, leading to stress accumulations and crack initiation.
Mechanical Fatigue: The fluctuating operational pressures within the coke drum, coupled with mechanical loading and unloading of coke, contribute to mechanical fatigue, further exacerbating the risk of material failure.
Stress Corrosion Cracking (SCC): The presence of corrosive substances in the feedstock, combined with the operational stress cycles, can lead to SCC, where cracks propagate much faster due to the synergistic effects of corrosion and mechanical stress.

What is the solution?

Why does Fatigue Assessment matters for a Coke Drum?

By performing Fatigue Analysis, this risk can be mitigated by identifying areas vulnerable to Fatigue Damage, predicting remaining fatigue life, and proactively plan maintenance or derating the operation.

In summary, fatigue assessment is essential for ensuring the safe, reliable, and efficient operation of coke drums by preventing catastrophic failures, minimizing production disruptions, and mitigating environmental risks.

Akselos Fatigue assessment can help mitigate these issues in several ways:

Life Cycle Analysis
Operational Adjustments
Monitoring and Inspecting Regimes
Material Upgrades

The process involves defining the loading conditions (static, dynamic, frequency), characterizing the material's fatigue strength (endurance limit), and performing stress analysis (analytical or FEA) to identify critical locations with high stress concentrations. Utilizing fatigue theories (S-N curves) and material data, engineers estimate the fatigue life (number of cycles to failure) of the component. Based on this prediction, design modifications or alternative materials with higher fatigue strength might be recommended. This long and repetitive process must be repeated for every point of interest, so this could drag on and on if this is performed manually.

How did Akselos upgrade this?

Akselos automates the process of running multiple structural analyses at different time steps and extracting stress values and determining the fatigue level of the material.

Depending on the requirements from customers, the assessment applet can be implemented to run for historical data or live monitoring data.

Figure 3: Data flow of Result.

With the Fatigue Assessment taken care of, now we need a place to consolidate the findings and make it presentable to all the stakeholders involved. That is why in conjunction with this custom assessment flow, Akselos also developed a specialized Dashboard to showcase these results tailored to the customer's key concerns regarding the asset.

Before we start

This article targets individuals with a foundational understanding of the Akselos platforms and access to the Akselos Customer Dashboard. If you're unfamiliar with these, the following articles may be beneficial:

Please note: To access any sample collections within our Library on the Akselos Dashboard, please reach out to our support team at [email protected].

Coke Drum Live monitoring dashboard

As mentioned above, we built a custom dashboard specifically for Akselos' Fatigue assessment process. This user interface (UI) presents the analysis results in a clear and concise way, with room to integrate additional assessments for the asset in the future. More details will be covered below.

Fatigue assessment implementation flow

Types of Fatigue assessment

The Fatigue Assessment is designed for monitoring the asset in nearly real time using collected data directly uploaded as input parameters. But we’ve also built a tool to upload a different sensor data set for custom analysis, we call this Historical data, it is mainly used to run analysis on a large set of previously recorded data to identify any trends or behavior that could streamline the operational cycle of the Coke Drum.

Live monitoring:

Live monitoring is a powerful tool in engineering assessments, providing a continuous stream of data and insights that enable engineers to make informed decisions, optimize performance, and ensure the safety and reliability of infrastructure and equipment.

Continuous live monitoring of Fatigue Assessment throughout its scheduled operation cycles and unforeseen events.
Monitor the structural health against operating conditions on the entire equipment. Changes reflected on the dashboard every set period (depending on the data feeding interval provided by customers).
Automated alerts will be generated to notify relevant stakeholders of any unsafe conditions of the asset.

Historical Analysis:

Having insights into the past operations by performing Fatigue Assessment for the historical operating data. We include in the package an analysis of three weeks' worth of operational data, recommended to be recorded at five-minute intervals.

Identify trends to track the performance of the asset over time to detect patterns in the asset's behavior that could develop into problematic issues.
Adapt to changing conditions by analyzing how the asset responds during various operational conditions.
Compare data over time to adjust maintenance and operational strategies and optimize the operation of the assets.

Fatigue assessment flow

Fatigue analysis is a crucial engineering assessment tool that predicts the lifespan and potential failure points of components under repeated stress. The process involves defining the loading conditions (static, dynamic, frequency), characterizing the material's fatigue strength (endurance limit), and performing stress analysis (analytical or FEA) to identify critical locations with high stress concentrations. Utilizing fatigue theories (S-N curves) and material data, engineers estimate the fatigue life (number of cycles to failure) of the component.

Figure 4: Fatigue Assessment work flow.

Run Engineering Analysis: This step is performed automatically as soon as new sensor data is made available. This is essential to obtain the stress distribution to be used for the Fatigue Assessment.

Obtain Temperature Distribution: The stress of each location on the model is extracted from the engineering analysis result.

Fatigue Theory: Based on the chosen fatigue theory (e.g., S-N curves, Miner's rule), engineers utilize the stress information and material fatigue data to predict the number of cycles the component can withstand before failure.

Life Estimation: Fatigue life prediction tools or software might be used to calculate the estimated number of cycles to failure or the safe operating life of the component under the expected loading conditions.

This workflow can be implemented with both Live Data and Historical Data, and we provide 2 different tabs for this purpose. Therefore your Historical Analysis will not interrupt the Live Monitoring Dashboard.

Live monitoring with Coke Drum Dashboard

Taking the common failure modes for this asset in mind, these indicators can be used by operators to monitor and predict the probability of a failure mode. For a Fatigue Assessment of a Coke Drum asset, these indicators are abnormally high pressure, structure deformation, or uneven cooling and heating of the asset. With these consideration, the Dashboard is designed so that all the key figures are accessible immediately on the landing page.

Figure 5: Coke Drum Dashboard under normal operation.

The dashboard is organized with information that can help monitor the assets such as Utilization Values for key areas that are updated live, along with:

Graphs of all Temperature sensors and Inlet Pressure.
Figure visualizing Global Temperature Distribution.
Figure showing Global Pressure Distribution.
Steam Rate graph

These key parameters will provide users with the earliest signs of problems regarding the monitored asset.

If a user requires more data and analysis specific to a parameter, then they can navigate to that specific tab.

What value it brings to the Coke Drum asset

Abnormality Detected

Below is an example of how a failure mode can present itself, we will go through the troubleshooting process together utilizing information presented to us on the Dashboard.

Figure 6: Coke Drum Dashboard with an abnormality detected.

The figure above displays a Dashboard that is reporting an issue, with highlights indicating where to start troubleshooting. We will walk through this process together.

What's wrong?

Here we can see a sudden peak in Stress that does not align with the previous operation cycle. This calls for immediate further investigation.

Next course of action

Next we can identify on the figure that Node 7 has a Utilization Factor over 1, which means the Stress at a location is exceeding its allowable levels.

Further Investigation

Following the label to locate where Node 7 is on the model, this will help operators quickly locate the problematic region. This could be due to a fatigued area, or a bad sensor.

Action Items

Just by having a quick look at the Dashboard, we’ve been able to identify the root cause of an issue plaguing the asset, and where it is happing, allowing for swift action to be taken to minimize downtime, damage to the asset, or even prevented a catastrophic failure. The exact action taken is up to the operator based on the detailed information provided by the Akselos Dashboard.

Conclusion

The decision is up to engineers, but in conclusion, the Coke Drum Fatigue dashboard will help to:

Present data in an organized and coherent way for operators.
Provide live data-based analysis in a timely manner.
Enable operators to react early to any arising issues.