Last time, I had an opportunity to participate in a free webinar held by Chemical Engineering Online. Topic of the webinar was how to sustained heat transfer performance.
I was eager to participate in this webinar because of three reasons. First, the webinar was practical. Second, speaker of webinar was from Therminol, which is one of heat transfer fluid. Third, I indirectly was heat transfer fluid user for two projects. So that, I need to understand about this topic if there is application opportunity in the future.
The first project I used heat transfer fluid was in Rosin Plant and Its Derivatives in Pemalang. The heat transfer fluid was used as heating medium in reactors. The second project was in Senoro Gas Development Project in Central Sulawesi. There are acid gas removal, dehydration unit, and stabilizer that need heat transfer fluid as heating medium.
Why Sustaining Heat Transfer Fluid Performance is Important?
Heat transfer fluids are a vital component in many processes that required high temperature. When the heat transfer fluid is not performing as expected, there can be detrimental effects to production rate, product quality, and equipment life time. Over time, heat transfer fluid can deviate from optimal performance. Reduction of heat transfer fluid performance can lead to increase in energy cost and unplanned downtime.
Due to degradation of heat transfer fluid, make-up is required. Make up is also important to accommodate fluid loss due to leaks, spill, and maintenance. Quantity of make up is usually 3% per year.
Key Threats to Heat Transfer Fluid
There are three key threats to heat transfer fluid:
- Changes in fluid quality. Fluid quality can change because of changes in composition or changes in physical properties. When heat transfer fluids degrade, composition of degradation composition is higher than composition of heat transfer fluid. And also, there will be change in physical properties, like density, viscosity, heat capacity, and acidity. Acidity is one of important parameter because high acidity can lead to corrosion.
- Changes in ability to meet process requirement. For example, when new unit operation is installed, there will be higher heating load than usual.
- Changes in heat transfer efficiency. This will impact heat transfer coefficient and system fouling potential.
Fluid Quality Indicators
Changes in heat transfer fluid quality can be checked from its composition, physical properties, color, and odor.
Composition
Composition of heat transfer fluid can change due to excessive thermal stresses and oxidation. Oxidation can cause formation of organic acids, while thermal degradation can cause accumulation of degradation component.
Composition can also be changed because venting capability (too much venting can lead to oxidation), fresh make-up fluid addition rates, and contamination (in-leakage, improper addition of make-up fluid).
Physical Properties
Like composition, physical properties of heat transfer fluid can change due to oxidation, thermal stress, and contamination.
Color
Color is indirect indicator of fluid quality. Color can be indicator of premature aging or contamination. However, to ensure this is required assessment to key parameters.
Dark fluid color can be a normal characteristics based on service conditions.
Odor
The chemistry of each heat transfer fluid can lead to distinctive odor. Change in fluid odor can be indication of contamination or thermal stress. However, fluid assessment is required to ensure if contamination or thermal stress occur.
How to Sustain Heat Transfer Fluid Performance
There are several way to sustain heat transfer fluid:
- Heat transfer fluid to meet process heat duty and temperature
- System design to support fluid quality maintenance
- Proper heat transfer fluid storage
- Proper reuse, removal, and disposal
In my experience, we select heat transfer fluid according to what is the highest and the lowest temperature demand for the operation. To sustain heat transfer fluid and to minimize degradation or thermal stress, the fluid must be operated within temperature demand.
The design of hot oil system or thermal oil system shall support fluid quality maintenance. For example, hot oil expansion tank shall be designed to be able to remove excess moisture, remove low-boiling degradation products, and add make-up fluid.
Low boiling degradation components can affect system in several ways.
- When present in significant quantities, it will lead to pump cavitation. In severe case, it may cause damage to pump seal and pump impeller
- When present in excessive quantities, the heat transfer flash point and viscosity may be lowered
- Low boiling degradation components can cause increase in vapor pressure which lead to premature and unexpected pressure relief and venting
- Excessive formation of low boiling degradation component can cause high make up cost, because removal of low boiling degradation components are replaced with fresh fluid.
To sustain heat transfer fluid, it is also important to store the fluid properly. If the fluid is stored in drums, it is better to store indoors or use drum covers. If the fluid is stored in bulk storage tank, the tanks shall be protected from oxidation and moisture condensation.
That’s all I want to share. If you want to listen to the webinar, please visit Chemical Engineering Online. If there is future Webinar, I recommend you to subscribe. Not only will you get more knowledge for free, you will also get e-certificate!
These are my previous posts about heat transfer fluids you might like:
- Thermal Oil Heater (https://missrifka.com/thermal-oil-heater/thermal-oil-heater.html)
- Sizing of Expansion Tank for Hot Oil System (https://missrifka.com/thermal-oil-heater/sizing-of-expansion-tank-for-hot-oil-system.html)
References:
[1] A Practical Guide to Sustain Heat Transfer Fluid Performance (https://www.chemengonline.com/webinars/)
[2] Optimizing Heat Transfer Fluid Performance – How to Avoid Costly Consequences (https://www.therminol.com)