"BECOMING THE BEST, WE WANT TO BE NO. 1"

 

 

 

 

 

 

WHEN SHOULD WE CLEAN OUR SYSTEM?

Please check for following to get intimation on system cleaning:

i) Check oil for Viscosity - carbonization. In case of viscous oil - clean the system.

ii) If fuel consumption is increased unnaturally - clean the system.

iii) If you are unable to get the temperature - clean the system.

iv) When you are entirely changing the oil - clean the system. Normally we change oil when it has gone bad, carbonized. Low flash point, high level of high boilers, more ash content, acidity etc. is the indication of oil going bad. So we need to clean the system to avoid new oil going bad again.

v) If total ash content in the oil is @ 2-3 % - clean the system (Take sample of oil in a dish, increase oil temperature to convert it into ash & measure ash content.)

WHY SHOULD WE CLEAN OUR SYSTEM?

Ø Deterioration of Thermic Fluid: Thermic fluid when used continuously deteriorates & needs replacement. The main causes of deterioration are:

1) Contamination
2) Oxidation
3) Cracking

Let us look at these causes more closely:

I) Contamination: Contamination of thermic fluid can be due to:

a) With Process Products. It can occur with the material during processing. The process materials have different temperature characteristics compared to thermic fluids. When mixed with thermic fluid, these materials decompose or get burn out, having deposits on the heating surface. Such deposits cause overheating - create hot spots - thus further degrades thermic fluid.

b) Contamination with water is problematic on two grounds:

(i) It forms emulsions with oil. This not only reduces life of the oil but also induces corrosion of the system internals.

(ii) Water forms steam at normal system working temperature, thus pushing hot thermic fluid out of system.

c) Rust, dirt, pipe-seals: These infiltrate the system during construction, gets loosened during normal system run. Installation of side stream filter can solve this problem.

d) Contamination due to mixing of thermic fluids: Many thermic fluids are not chemically compatible with each other. Contamination can occur if the compatibility is in question. Any change in thermic fluid or top up with another thermic fluid should be avoided or thoroughly evaluated.

In short, contaminants can be listed as:

1) Leakages of process products through pipe lines, vessels etc.
2) Water
3) Corrosion products, seals, dirt, dust etc.
4) Mixing of different thermic fluids.

II) Oxidation: Thermic fluid at high temperatures, get oxidized & form carbonaceous, gummy deposits which impair system effectiveness & performance, by clogging pump filters, hamper heat transfer rate etc. Oxidation of thermic fluid produces acidic products, which are soluble in oil along with insoluble sludge and gummy deposits, which increases viscosity of oil. The acidity will increase rate of corrosion of internals. Hence properly designed expansion cum deaeration tank will be useful to remove low boilers or reaction of Thermic fluid with air.

III) Cracking: Cracking is the result of insufficient circulation of thermic fluid at optimum velocity resulting in overheating of thermic fluid. This results in breaking of long chains into smaller chain compounds, increases suspended solids such as ash, carbon percent etc. This induces hot spots on pipe internals, which increases localized heating of oil film, which is much above the cracking temperature. Cracking results in the release of higher inflammable hydrocarbons, reducing viscosity & flash point of thermic fluid. Unstable hydrocarbons will polymerize and form deposits. These deposits will reduce heat transfer rate of overall system, reduction of flash point thus serves as a warning indicating that cracking has started.

Following are the consequences when oil goes bad:

Ø CONSEQUENC ES OF CONTAMINATIONS ON SYSTEM ARE:

1) Reduction in heat transfer rate.
2) Lower fuel efficiency.
3) Difficulty in start up at low temperatures.
4) Flow restriction in small diameter pipelines or in low velocity areas; thus increases in Pumping cost. 5) Fouling of heat transfer surfaces.
6) Failure of heater coils.
7) More maintenance cost.
8) Reduction in overall system efficiency.
9) Reduction in life expectancy of thermic fluid, heater oil.
10) Pump cavitations.

Ø CONSEQUENCES OF CONTAMINATIO NS ON OIL ARE:

1) Increase in viscosity.
2) Reduction in flash point.
3) Darker colour.
4) Increase in acidity.
5) Formation of sludge.
6) Lowering of boiling point & increase in vapours pressure.
7) Overall reduction in life.

HOW TO CLEAN THERMIC FLUID SYSTEM?

We have seen that deteriorating of thermic fluid is due to contamination, oxidation or overheating, cracking. This can lead to partial or full choking of the thermic fluid system. This would call for cleaning, decarbonizing of thermic fluid system. Apart from this if you are changing the entire thermic fluid of the system then the cleaning & decarbonization of the system is recommended. Criticality in decarbonising is, carbon does not dissolve into any chemical. It needs to be broken into finer particles and brought into flowable condition. Baked carbon forms bond with the metal and is difficult to remove by ordinary chemicals / detergents. There are basically two methods for cleaning of system:

1) Water based 2) Oil based

WATER BASED CLEANING: The total time required for cleaning the system and put it into operation can vary between a few days to few weeks. In case of water based cleaning system the time is higher because entire quantity of water should be drained out of system otherwise that water will pose three problems: 1) It forms unstable emulsions with oil, which will reduce the life of oil. 2) It induces internal corrosion of the system. The corroded areas provide anchorage for depositions. 3) Once heated water changes to steam, overpaying more volume and pushing hot thermic fluid out of the system, which is a safety hazard.

OIL BASED CLEANING: Oil based chemicals like Thermclean-XL™ clean and decarbonise the entire system using old thermic fluid only. Even some other waste oils can be utilized as media such as transformer oil, vacuum pump oil etc. There is no time delay or safety hazard for start up of the system. Some traces of Thermclean-XL will not have any adverse effect on system. They will vent off once the system is commissioned. Let tabulate the merits & disadvantages of water based cleaning verses Thermclean-XL.

COMPARISON BETWEEN THERMCLEAN-XL AND WATER BASED COMPOUND

Material Thermclean – XL is a unique blend of chemicals comprising of a strong corrosion inhibitor, deposit penetrant and Maxi– Accelerator™ Material is strong industrial soap comprising of silicates, metasilicates and filling compounds.
Oil based, can be mixed with your old thermic fluid or any used hydrocarbon fluid. Water based. To increase the cleaning efficiency DM water has to be utilised.
No need to heat it separately. Being very slow process, the continuous heating of the system to 700 C during decarbonisation process is must.
The unique deposit penetrant quickly penetrates into resinous deposits and hard carbon scales. Maxi-Accelerator™ helps to accelerate the process for faster quicker results. Lengthy process. Only superficial thicker oil sludge