Descaling of Boiler

[Kamran203]

Hello All,
I am Working in a petrochemical Industry ( Acetate Production plant). We have two fire boilers ( package type fire tube boilers) having capacity of 5 ton each for Saturated steam. We want to descale it. which Chemicals and Inhibitors are best for this in term of Efficiency ,cost and handling ? Please help me.

 

[MJCronin]

You may want to consider having this performed as a contracted service. As an alternate, you may want to consider rental of the equipment

Citric Acid is sometimes used along with a power flush using temporary pumps and filters. Other proprietary chemicals are available.

https://www.unitedlabsinc.com/content/pdf/label/417label.pdf

http://www.chemtexlimited.com/boiler-descaling.html

MJCronin
Sr. Process Engineer

 

[EdStainless]

This needs to be done by pros.
They need to take scale samples to determine what they are removing, and which chemicals to use.
Then they will set up to recirculate the cleaning mixture through the boiler.
They will need to be adding fresh chemicals to keep the concentrations correct, and monitor to determine when they reach the end point.
Then they will flush and neutralize.
And last but not least they will dispose of the hazardous waste generated.

The only people that I know of that do this themselves are the guys that make the cleaners.
It is usually a mixture of citric, phosphoric, hydrochloric acids, with surfactants, inhibitors, and sometimes chelating agents.

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P.E. Metallurgy, Plymouth Tube

 

[bimr]

Agree with EdStainless. Contact one of the major water treatment chemical program suppliers and obtain advice from them.

 

[crshears]

Hello Kamran,

I agree with the previous posts: hire the job done, but ask around to be sure you engage a reputable firm for the work...and have your business/legal people work with your engineers to embed work guarantees and so on right into the contract.

But even more basic than that...

We want to descale...

WHY do you want to descale? Has it been determined by your Operations Department that there is excessive heat loss and/or insufficient heat transfer occurring within these boilers?

What are the boilers fueled with? Could there be fouling inside the fire tubes?

Some operating engineers prefer to see a light coating of scale on the water side of a boiler rather than none at all, since the scale can act as a protectant to the base metal of the boiler itself.

It is always wise to conclusively ensure descaling is warranted before proceeding with it.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[macmet]

Agree with the statements above about how this should be done by specialists.

Aside from the obvious hazard of dealing with potentially dangerous chemicals, you also need to know what can be used for the type of scale. Some cleaning be done by flushing with good quality water while others are not soluble (sp?).

Have you had your scale analyzed to determine what it is?

 

[chicopee]

In the event that you do the chemical cleaning yourself per a prescribed descaling agent and assuming that the waterside of the fire tubes are heavily scaled, you must start the cleaning process slowing otherwise there is a change that the heavy scale will loosen and bridge between the tubes. The consequence will be overheated tubes as the water circulation around the tubes become restricted. A specialist would know that.