Enhancing Reactor Safety: Leveraging the MPT Dashboard for Shutdowns

Modified on Tue, 11 Jun at 9:33 AM

Introduction

What is the Reactor?

Hydroprocessing reactors play a pivotal role in the oil and gas industry, serving as crucial units in refining processes that improve the quality of hydrocarbon products by removing contaminants.

Figure 1: A representation of a Reactor asset.

These reactors operate under stringent high pressure and temperature conditions to catalyze the desired chemical reactions. The operation of these reactors requires precise control, especially during the heat-up and cool-down processes, to maintain safety and efficiency.

What can go wrong?

During the heating and cooling processes in hydroprocessing reactors, a variety of technical challenges related to temperature and pressure can emerge, necessitating precise control to prevent operational disruptions and ensure safety.

Figure 2: Failure mechanism caused by hydrogen embrittlement.

MPT: Minimum Pressurization Temperature. It will be discussed in the next section.

These problems can include:

Differential Thermal Expansion: Components within the reactor expand and contract at different rates due to variations in material properties and exposure to temperature gradients. This differential expansion can induce localized stresses, particularly at skirts and welds, leading to potential failure modes such as cracking or warping.
Thermal Shock: Rapid changes in temperature can cause thermal shock, characterized by the sudden imposition of stress within the material matrix. This phenomenon can lead to the initiation and propagation of microcracks, especially in materials that exhibit significant thermal expansion coefficients or possess low thermal shock resistance.
Pressure Imbalance: Heating increases the pressure inside a closed system as the fluids (gasses and liquids) expand. If the heating is too rapid, the pressure increase can exceed the design limits of the reactor or tank, risking structural failure. Conversely, rapid cooling can create negative pressure (vacuum conditions), pulling the tank walls inward, which can also lead to structural failure if the tank is not designed to withstand such forces.
Embrittlement Risks: In the context of hydroprocessing, the absorption of hydrogen by metal components is exacerbated at high temperatures and pressures. This absorbed hydrogen can significantly reduce the ductility and toughness of the metal, leading to embrittlement and the increased likelihood of crack formation under mechanical stress.

What is the solution?

Why does MPT Assessment matter for Hydroprocessing Reactor?

The Minimum Pressurization Temperature (MPT) is defined as the lowest temperature at which a reactor can be safely pressurized after a shutdown, without risking brittle fracture. It ensures the material maintains sufficient toughness to prevent cracking.

Figure 3: MPT Curves of different locations.

The normal flow of this assessment requires an engineer to obtain the stress and temperature value at the location where the MPT assessment must be performed. Then this temperature value is then plotted on an MPT Curve to determine the maximum allowable stress. Lastly, the stress value at the location is compared to the maximum allowable stress to gather the utilization factor. 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 to compare with the MPT curve data, in order to calculate the Utilization factors (Um) at different locations of the model. This process automatically starts as soon as new sensor data is uploaded.

Depending on the requirements from customers, the assessment applet (a tool deployed on Akselos Dashboard) can be implemented to run for historical data or live-monitoring data.

With the MPT 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].

Hydroprocessing Live monitoring dashboard

As mentioned above, we built a custom dashboard specifically for Akselos' MPT 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.

Hydroprocessing assessment implementation flow

Types of MPT assessment

The MPT 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 Hydroprocessing reactor.

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 Minimum Pressurization Temperature (MPT) analysis throughout both scheduled and unforeseen startup and shutdown phases.
Monitor the structural health (stress utilization factor) against operating conditions (pressure and temperature) of the entire equipment. Changes are reflected on the dashboard every 5 minutes.
Automated alerts will be generated to notify relevant stakeholders of any unsafe conditions of the asset.

Historical Analysis:

Having insights into past operations by performing MPT analysis on historical operating data is crucial. We will utilize historical data included in the package and analyze three weeks' worth of operational data, recommended to be recorded at 5-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.

Hydroprocessor Reactor MPT assessment flow

MPT assessments are not one-time evaluations. Over time, the material properties of the pressure vessel can change due to ongoing operation. Therefore, it's crucial to periodically re-evaluate the MPT to ensure continued safe operation.

So, engineering assessment is constantly run with the current temperature and inlet pressure sensor data as the input parameters. Ensuring the most up-to-date stress distribution result is used for the MPT assessment.

Figure 4: MPT 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 MPT assessment.

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

Input MPT Curve: The pre-determined MPT that is created based on the properties of the alloys used. This curve contains the maximum allowable stress at each temperature level for this particular material.

Calculate Utilization Factor: The extracted temperature is used to find the maximum allowable stress at that location. Then the stress results are compared to the maximum allowable stress, if this value is exceeded, a problem will be reported. This process is repeated until all the location on the model is covered.

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 Hydroprocessing Reactor 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 MPT Assessment of a Reactor asset, these indicators are uneven temperatures, abnormally high pressure, or uneven cooling and heating of the asset. With these consideration, the Dashboard is designed so that all the key figures are accessible immidiately on the landing page.

Figure 5: MPT Dashboard under normal operation.

Above is the Dashboard during normal operation with no abnormalities detected. The status indicator on the top of the page is showing green, meaning there is no cause for concern. But operators can still check any parameters such as:

Last Update.
Location of max utilization value.
Current max utilization.

Above are the most important information, as such it is place on top, as it can tell you how recent is the data, the location of the point of concern, and how close to the limit the asset is. Additional supporting information populates the rest of the dashboard, such as:

Utilization factors of other areas.
Trend graphs for Inlet Pressure and Temperature sensor data.
Trend graph for Temperature rate of change.

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 Hydroprocessing Reactor asset?

Abnormality Detected

Figure 6: MPT Dashboard with an abnormality detected.

Above 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.

The figure above shows a Dashboard that is reporting an issue. Completed with highlights on where to look to start troubleshooting the problem. We will walk through this process together.

What's wrong?

The first thing to notice is the red indicator on the top of the Dashboard page. This is the first sign of a problem rearing its head. Now that it has played its part by grabbing your attention, we will start troubleshooting.

Next course of action

Next, we must identify what is causing this warning. When we move to the next row, it can be clearly seen that the Max Utilization Factor is over 1, which means the Stress at a location is exceeding its allowable levels. To the left of the Max Utilization value, we can identify where this problem is, it is at the Skirt of the model. However, there are can be many causes of this, from uneven heating, to a broken temperature sensor. Therefore, to identify the core issue, we must investigate further.

Further investigation

Now, in order to identify the root cause of this issue, we can take a look at the bottom of the Dashboard where there are 3 supporting graphs. There is an obvious oddity in two of the graphs, where a temperature sensor is showing much lower values than the other, which can be caused by uneven heating of the asset. The other graph confirms this by showing a clear difference in the heat-up rate of that area.

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 MPT assessment 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.