Cleaning External Surface of Gas Fired Heater Tubes

[saynick]

I have a gas fired heater on an LNG plant and I would like to clean the external surface of the tubes in the convectiona and radiation sections. Are there any chemicals than can be used to aid in removal of deposits? Also, what is the best method of cleaning to use?

 

[TubeTech]

Hi Saynick. Did you receive a reply to your query re convection and radiant section cleaning? Would be interested to hear as have only just joing the Eng Tips Forums. Cheers Simone

 

[ash9144]

Are cleaning the tubes in place or pulling them out of the heater?

Usually when done in place they are hydroblasted or CO2 blasted. It would be very difficult to clean for most arrangements. Most hydroblasters have surfactants and detergents they can add to the hyrdroblast solution to assist in cleaning.

Whatever method you choose needs to take into account the type of scale, condition of tubes, material tubes, and many other factors.

 

[unclesyd]

As posted by ash9144, the type and quantity of scale and design of your boiler will dictate your approach to cleaning the tubes.
We have a HGRS boiler (115,000 lbs/hr) @ 650 psig, 750F, in a thermal reduction (NOx)unit that requires periodic cleaning of the tubes due to feathers from refractory dust. These tubes are sand blasted using Al2O3 abrasive and a very good operator. One thing is we have hooked a vacuum system to help collect the residue. We tried water blasting, 15,000 psi, but it took too long and it took too long to dry the refractory. We still water blast the preheater section. This boiler has a Atemperator.
All our Therminol Vaporizers of D-Tube construction have been sand blasted several times in their 50 yr, operation.
We have partially abrasive blasted our power boiler due to having to burn high Vanadium fuel oil for short periods.


No matter which approach you undertake make sure you have experienced people to do the work.

 

[rmw]

I suspect that you are firing the same gas as your LNG which means that it has lots of stuff in it that normal fuel grade natural gas has had stripped out.

While unclesyd has listed several remedies, it would be better to know what is in your fuel and what types of deposits you have plus more information on how your convection section is constructed.

rmw