Water Tube Boiler: Surface Condition of Outer Tube

If it is the metal of your water tubes that is glowing then you have a serious boiler circulation problem. It is more likely that you have a build up of ash or clinker that is doing the glowing.

To reduce the heat loss to atmosphere you should apply insulation. This comes in many forms and the type that you should use depends on the temperature of the surface you need to insulate and the reduction of heat loss you want to achieve.

There are a lot more details required to answer this question properly.

BAB

You have got a problem here and you should fix it as soon as possible. There are several things that could cause this and they are nearly associated with bad water circulation or improper heat exchange thru the tube wall. Water tubes have two main purposes IMO. They pre heat the water and they contain the heat of the boiler by keeping the the furnace walls from over heating. One thing that you should know is that if you do not fix this problem the tubes will "burn up" so to speak and have to be replaced. I am listing a few of the reasons that could be causing the problem.

1. You have a plug in a tube or several tubes.

2. Low feed water pressure.

3. Bad water chemistry that is depositing a scale on the inside of the tube that prohibits proper heat exchange cooling of the tube material by the water. This could be from a leaking air temperater(sweet water condenser) or improper water treatment. I just went through this on one of our WT boilers and this can carry over into your turbine and other equipment causing even more major problems. If this proves to be the problem the boiler should have a chemical cleaning by a company that specializes in this kind of work (we chemical clean our boilers every 4-5 years).

4.On some water tube boilers the lower part of the water walls and floor is covered with refractory because the tubes just can't take all of the heat in these areas. Does your boiler have refractory in the lower furnace and is it in good shape?

pipewelder

You are scarring me. If you have the position of running this boiler, and you do not know what you are looking at, hire someone that is licensed and does!

I don't mean to be harsh, but lives are at risk here.

When you look at this boiler, envision a bomb that that may explode and level your building at any minute. There should be someone in charge of making sure the bomb does not explode!

Good luck.

If what you see glowing is actually slag, ash or refractory, this probably isn't of big concern. refractory will glow and is supposed to be where it is. Ash can be cleaned out next outage. If it is in fact the tube metal.... YIKES. I would shut the unit down immediately and investigate. Depending on the pressure of the boiler (probably significant if it is a water tube boiler), you have a great deal of potential energy stored within severly compromised metal container. For an appreciation of the power involved, check out the mythbusters segment on water heater rockets.

http://www.youtube.com/watch?v=JmJoyuUJj2Q

Please do your best to stop working of boiler now, then you can make the inspection work required with help of specialists.

When you have calcium buildup on the inside of water tubes this creates an insulation and the tubes get a condition as you describe. shut it down ASAP and perform an Inspection You may have to retube the boiler.

The boiler is closed for the Maintenance and scale cleaning. Thanks for your wise suggestions.

dear sir

the sooner you stop the boiler and go for inspection is better and safer for you and the boiler. you have to give full details like coal or gas or oil fired boiler. insulation and refractory arrangement etc etc. almosst all countries have their inspection and repair procedures and pls follow yours and consult someone who is an authorised inspector.

pkmohapatra

Dear Mr.aQamamiad,

Your posting conveys a message that heating at the lower region beyond permissible limit. This means the water circulation, with in the tubes is seriously affected or the Heat Release in the Furnace has increased, resulting in Excessive Heat Radiation, or the absorption/heat transfer in to the water is affected seriosuly.

Immediately the Boiler to be stopped and thoroughly examine and remedial action to be taken.

Pl. post the information what was the problem and what solution was implemented.

Regarding coating for reducing radiation loss - INSULATION is the proper methd to be adopted.

DHAYANANDHAN.S