Flownex Video: Crude Oil Network in Flownex – Part 2

Hello everyone, this is Mohsen Seraj. I'm an application engineer at the Ozen Engineering Technical Team. In the previous part of this video, I discussed how to model a pipeline for crude oil that is schematically shown in the bottom of this slide.

The oil is delivered from tankers to a marine terminal floating on the sea level and then sent out through the pipeline at a depth of 35 meters below sea level toward the booster station on land. From there, it is transported to the salt facility.

As a maintenance engineer for this pipeline, it is crucial to understand the effect of ambient temperature on crude oil properties that could affect the mass flow rate along the pipeline. So, let's begin with the first question.

I previously explained how to create a new fluid material to model crude oil properties based on the properties given in this table at the bottom of the slide. I also discussed the effects of adding heat transfer elements to the system to model heat conduction and thermal inertia of the pipe walls.

Now, the question is: how do heat transfer elements affect the pipeline delivery? In this video, I will work on the last part: what happens if the offloading crude oil temperature changes from 20 to 60 degrees Celsius? Can I model this variation within the Flownex environment?

This is the pipeline network I adapted for this project. It consists of three main parts: the single point mooring, the floating terminal, booster pump stations, and salt facilities, including salt dome storage facilities. I am considering three heat transfer elements in this model.

I previously solved this problem with a deployed oil temperature of 60 degrees Celsius, which I referred to as a warm oil scenario. The temperature distribution along the pipeline showed a cooling effect, particularly in the overland pipeline sections.

For example, at this pipe, the temperature dropped from 60 degrees Celsius to around 30-31 degrees Celsius. Now, let's change the boundary conditions for the cold oil scenario. I will modify the temperature from 60 to 20 degrees Celsius and solve this new boundary condition for 20 degrees Celsius.

We can now observe the temperature distribution. As you can see, the temperature at the parts of the pipeline that overlap has decreased significantly, from around 20 degrees Celsius to approximately 17-18 degrees Celsius.

After adding heat transfer to the pipe, the temperature increases to about 19.4 and 20 degrees Celsius.

So far, we have results for two cases: one with a crude oil temperature of 20 degrees Celsius (which I referred to as the cold oil scenario) and another with a temperature of 60 degrees Celsius (the warm oil scenario).

In the last part of this problem, I want to see how the temperature changes from 20 to 60 degrees Celsius and its impact on the temperature distribution and mass flow rate in the network. Previously, we had a mass flow rate of approximately 30,000 kilograms per second for the mass flow rate.

Now, for the temperature of 20 degrees Celsius, the mass flow rate is about 2850 kilograms per second, a decrease of approximately 5%. Now, let's change the temperature from 20 to 60 degrees Celsius for transient or dynamic stimulation in Flownex.

First, we need to set a scheduler to specify the mass flow rate and then observe the changes in mass flow rate and sugar application as the oil temperature changes. When setting up the scheduler, we need to be cautious about rapid actions, ensuring the machine does not send any major energy output.

We also need to consider memory usage, humidity, and gravity, as well as print temperature. To save the simulation results at a specified time, we can create a snapshot and reload it if necessary.

Now, let's consider what happens if the oil temperature suddenly increases from 20 to 60 degrees Celsius. We will set up the scheduler, specify the simulation duration, and create a scenario for the warm oil offloaded.

We will then define the new action for the temperature of the oil at the start point of the network and monitor the temperature, terminal inlet, and reservoir. By setting up the graph, we can observe the temperature changes over time.

The y-axis is time-based, and we will display the temperature in Celsius. The maximum display length is set to 25,000 seconds. Now, let's solve the steady state and run the transient simulation. We can observe the temperature changes in real-time for the first node, terminal inlet, and reservoir.

As you can see, the temperature at the terminal inlet is increasing, reaching 55 degrees Celsius. The mass flow rate is also changing, approaching 30,000 kilograms per second, the value we had for the 60-degree Celsius scenario.

The temperature distribution along the pipeline is also changing, with a larger portion of the pipeline experiencing higher temperatures. Now, we are at 12,000 seconds, about 25% of the solution.

The temperature is fixed for the inlet terminal at 55 degrees Celsius, and the reservoir temperature remains constant at 20.4 degrees Celsius. The mass flow rate is increasing, approaching 30,000 kilograms per second. At 25,000 seconds, we have completed the solution.

The temperature distribution and mass flow rate have reached the desired values. The effect of seawater can be seen in the temperature reduction at around 18,000 seconds.

In summary, we started by setting up the transient simulation, defining the action setup, and creating a graph to monitor temperature changes. We then ran the steady state and transient simulations, observing the temperature and mass flow rate changes in real-time.

The results show that the temperature and mass flow rate have reached the desired values after the transient simulation.