:: Boilers &Thermic Fluid Heaters --- ID :: 18921
THERMIC FLUID SYSTEM CLEANING AND FLUSHING
Thermic Fluid Systems cleaning additives and life enhancer

By Kiran Thakar // petrobazaar // 25th August , 2021.


THERMIC FLUID SYSTEM CLEANING AND FLUSHING


In the close loop indirect heat transfer system, heat transfer fluid degradation can lead to a  major problem or even sever or fatal fire hazard, if not attended immediately. The heat transfer  fluids (HTFs) are more commonly known as Thermic Fluids (TFs).  

Most of the time due to production pressures, this TF degradation problem is ignored & pushed  forward to be attended later during planned plant shut down.  

Thermic fluid degradation can happen in any fired heater system due to;  

1. Contamination during top up with degraded or other fluids.
  
2. Thermal cracking due to overheating - Low fluid flow conditions, Lower
TF velocities  through heaters/ Higher than max allowable film
temperatures of TF , Higher than rated  fuel firing rate /over loading, flame
impinging on heat transfer surface etc.  

3. Thermal Oxidation - Higher Thermic fluid temperature (> 65 deg C) of the
top most layer  of the fluid at the vented expansion tank.  

4. Thermal cracking due to aging-This is the desirable condition of TF after
many years of  use and is due to good system design, proper Operation &
maintenance practices.

5. Any of the above 1 to 3 conditions will lead to increased Thermicfluid viscosity, indicating  higher Total acid neutralization (TAN) value, Higher Insoluble (carbon) % associated with  lowering of the flash point , compared to the fresh or new fluid properties .  

Condition 4 is the ideal / desired condition for any TF system, where in the thermal cracking  takes place due to aging of TF after long duration (many many years) of use and will be  indicated by only flash point reduction & lowering of viscosity value of the system TF. This is  due to more % of low boilers presence in TF after a long use. Only by replacing some volume of 

old TF with the fresh TF (10 to 30 %, or as per the % low boilers the old TF) will replenish the  properties of the old TF for further continued use.  

Regular Thermic fluid analysis (quarterly) can indicate the health the system, in a much similar  way as our blood tests indicate health of our body.  

As stated above, the final result of the thermic fluid degradation (conditions 1 to 3) is generally  indicated by rise in viscosity & viscosity index (change in viscosity with change in temperature).  

So the degraded thermic fluid gets thicker, which results in to lower TF flow through the  heaters which in turn gets over heated (Carbon formation / Increase Of Insoluble % in  Benzene/hexane/Acetone >1 %) in the heater again, results into further degradation /lowering  of viscosity .This chain reaction is fast & makes the final stage to highly viscous, un flow able,  jelly or tar like appearance of TF at normal temperature. Such condition of TF requires  continued heating to keep it in flow able condition & can be partially drained out of the system  in hot condition only.  

Such TF condition demands immediate complete draining/flushing out & refilling the whole  system with new thermic fluid. But the system may have blockages and it is a very tedious, time  consuming task to clean the complete system. In spite of all efforts the internal surfaces of the  pipe lines, heat exchanger, heater tubes may retain the large quantities of old contaminated  fluid & its sticky layers deposited on all internal surfaces of the system, will again contaminate  new thermic fluid.  

A long forced system shut down may be required resulting into loss of production & financial  losses.  

As you know use of any water based cleaning agents are not at all recommended as these are  ineffective to remove hard carbon / sludge deposits. Moreover, the remaining traces of the  water in the system bound to get mixed with the new fluid. This happens in most of the cases  and creates havoc during system re commissioning. This leads to excessive TF overflows  through the expansion tank, build up of excessive pressure in TF system more than system  design pressure and may lead to busting or leakage through pipe/flange joints, causing sever  fire /burn injuries. Also severe vapour locks & resulting low flow conditions due to water vapour  in the system may over heat the new fluids & can contaminate the new TF.  

To tackle this conditions M/s Shreyas Petroleum Additives Ltd ,an Ahmadabad based company,  who are into manufacturing of a wide range of SigmaTHERM brand of premium thermic fluids &  additives , have developed a unique thermic fluid system 'Cleaning Additive & Life Enhancer  Fluid' SigmaTHERM FF 101.


Based on the condition of the existing contaminated thermic fluid (indicated by the latest  analysis report) SigmaTHERM FF 101 is added (max up to 20% of total system volume) into the  old degraded operating TF system, in cold or moderately hot flow able condition (for highly  viscous fluids)  

Only up to 20% of the total system volume of SigmaTHERM FF101 is added by draining our  same quantity of old fluid. The mix is circulated, heated & operated up to 240 deg C for at least  50 hours.  

It’s amazing & powerful action provides a dramatic reduction in the viscosity of the  contaminated fluids while solubilising any hydrocarbon oligomeric sludge and deposits in heat  transfer systems  

SigmaTHERM FF101 additive exhibits exceptional solvency for the hydrocarbon structures  found in most petroleum heat transfer oils and synthetic organic heat transfer fluids.  

Its low viscosity & pour point, relatively high boiling point and superior thermal stability makes  SigmaTHERM FF 101 ideal for the use with thermic fluids particularly when they are thermally &  oxidatively degraded .  

Unique Advantages of SigmaTHERM FF101 : 

1. Very economical solution requires only 20% maximum addition of the total system TF  volume.
  
2. It may avoid total replacement of the costly TF.  

3. It works while the system operates and the user may continue the plant
process to  operate the system up to 240-250 deg. C.
  
4. User can plan for the shut down for TF replacement & till then it can be
operated.
 
5. The degraded TF flows out quickly & easily with sludge / deposits, from
the drain points  which reduce down time & post discharge cleaning.  

6. Mechanical cleaning is avoided in most cases.
  
7. Cleans the whole TF system & improves the heat transfer from heat
exchangers &  utilities.
  
8. It does not contaminate the fresh fluid & is non corrosive to material of
construction.
 
9. It has high auto ignition temperatures & does not readily ignite  

10. It is strongly recommended to identify & eliminate the root cause of the TF degradation before  filling the new /fresh fluid in the system. 


If needed, our expert service person can guide the users. SigmaTHERM FF101 can be delivered  quickly to reduce any plant down time.  

Please log on to www.sigma-therm.com for more details or Contact: Mr Kiran Thakar, Cell Ph:  +91 9823049360, Email : kiran@shreyas.in 

Shreyas Petroleum Additives Ltd is a specialized company in the field of heat transfer fluids can  provide all the support & help in selecting the right fluid for the specific applications.  

sigma T H E R M® – World of Heat Transfer Fluids 

 Manufactured By  

  Shreyas Petroleum Additives Limited,  

Ahmadabad, India