Changing Heating Thermal Oil 1

[KelvinTay]

Dear all

I have a question regarding heating thermal oil which would appreciate your experience and advice.

My plant had been utilizing thermal oil to provide various heating purposes over the past 20 years (but was partially replaced with some new thermal oil around 8 years ago). The fluid heating temperature was designed to provide heat up to 280degC, but over time the temperature achievable has dropped substantially to below 200degC. One of the contributing factors that we suspected was due to thermal oil deterioration, hence we had a well-known thermal fluid provider to test a sample of our thermal oil.

Coming to my questions,

1. Does thermal oil deterioration contributes towards such a drastic degradation in heating temperature? What other factors, in your experience that may have caused this issue?

2. I have attached the test report if you are kind enough to read. The color is Dark Brown which to me indicates fouling in the piping and accumulation of dirty hydrocarbons and possibly coke. The metals are in ppm levels. The viscosity is 31cst @40degC. Would you consider these as (extremely poor / very poor / poor but usable) thermal oil quality?

3. Are there methods for on/off-line cleaning of the thermal oil and pipings?

My bottom line is I am trying to understand the 'real' reason for the degradation in temperature driving force and assess the long-term economics of replacing the thermal oil.

Thank you and happy festive season!


Best regards
Kelvin

 

[Compositepro]

What is your heat source? You very likely have coked heaters and this will rapidly lead to heater failure. Once coking starts it is self-accelerating.

 

[chicopee]

The temperature drop is not from thermal oil deterioration but from heating filaments or surfaces coated with "coked" oil as suggested above. Also present test results to oil supplier for their assessment.

 

[SNORGY]

The "comments" section at the top of the analysis page appears to have captured the "partial replacement" of oil that was done eight years ago. We're the analysts advised of this prior to performing their analysis? Reading between the lines from their report, apart frm picking up some water and trace iron, they don't find too much out of the ordinary with the sample.

In addition to the fouling and coking issues alluded to above, you might want to see if you have cross-contamination (e.g. exchanger leaks) elsewhere in the system if you are picking up things like water in your sample, although the amounts being picked up do not signal that as your main problem.