cleaning out a boiler

[wsmcycle]

I had lots of gunky oily clumps in my hot well (misnomer? mine is not hot at all). It needs to get cleaned out. I am going to heat the full/flooded boiler and then blow it out the 1.25 inch drain up and out of the boat in solid plumbing. Question, I would like to put detergent in it to break down the gunk. Has anyone ever cleaned their boiler this way? I expect the keel condenser to Worse than the boiler. It has a 1/4 drain plug in it and I am definitely going to push hot soapy water through it.

Does the term blow down mean full open to atmosphere the lower bung in the boiler? I have read the term but I cannot imagine really wide open discharge.

Thanks for helping me
Wendell

[Lopez Mike]

One thing to remember is that you can open up a rather large valve and do it suddenly without blowing up anything except the good will of your neighbors. It might be possible to have a large enough opening to develop some thrust but the old wives tale of boiler explosions due to sudden release of pressure are just that, wives tales.

On enormous steam locomotives the blowdown valve is quite quick acting. Now the noise and general commotion from a blowdown to atmospheric pressure from being on the edge of the safety popping is impressive, but as long as the fire is out, you won't hurt a steel boiler with steel tubes.

Organic solvents and TSP are both fairly effective at cleaning out oily deposits. The trick is how to agitate the cleaning solutions and how to get them out when you are done.

If it were my boiler I would fill the boiler to near the top of the gauge and add plenty of TSP. Then heat it up a bit (enough to show some pressure) and blow down hard. Repeat as needed. Water and TSP are cheap.

I'll bet there are other good ways to do this. Others will chime in.

[wsmcycle]

OK! thanks Mike What does tsp do to promote dissolving an oily mess and help cleaning? Is it a cleaner
I had considered surging (on/off repeat) the boiler with our large 120 lbs compressed air system here in the plant.

[jschoenly]

Some would say that using the compressed air introduces oxygen in the boiler and you don't want that for corrosion. I second the TSP and pressure treatments. Solvents, suds, and various other things will make a boiler prime a lot and can some times take a good number of blowdowns to tame. TSP shouldn't get it too excited.

For the condensor and hotwell, you might want to just disconnect and run live steam from the boiler thought to clean. If the hotwell isn't hot at all, you might consider shortening the condensor. You vacuum and no steam at the air pump exit, but cooling the condensed exhaust too far is just wasting energy. Not that it really hurts, but it may steam a little better with warmer feedwater. My last hotwell came to me fairly grimy. I just washed it all out with simple green and put a few layers of pig mat under the float to soak up the new water once I got back to running.

[Lopez Mike]

I dunno about surging it with air. I'm not sure it would do anything but make noise and blow loose stuff around the shop.

TSP is the working ingredient in most detergents. No perfume and hard on your hands.

I have the same problem with a cold 'hot well'. I have thought about cutting down the size of it but it is about right for full throttle steaming. I'm gong to wait until I make some other additions like an exhaust feed water heater and an economizer before messing with my condenser.

Great idea to use the boiler as a steam cleaner. I had never thought of that! Lookout truck!!!

[DetroiTug]

Quote "Does the term blow down mean full open to atmosphere the lower bung in the boiler? I have read the term but I cannot imagine really wide open discharge."

The blow down should be high velocity with a wide open valve. It increases the speed of the water along the bottom of the boiler and top of the crown sheet above the firebox, faster moving water moves the solids more directly towards the opening. I have my blow downs plumbed thru the hull and blow down periodically throughout the day and then at the end of the day blow down completely while the boat is on the trailer still in the water. Nobody knows it even happened. It's quick momentary full open and then close.

Oil in the boiler: Yes it should be avoided by just about all opinion in firetube types and other boilers with a substantial reservoir. Although, according to Abner Doble, it wasn't that big of a deal in monotube or mostly tube type boiler. The oil even though on the internal surfaces of the tubes will thin when heated and be carried over in the steam. Of course there has been much debate on that claim.

Abner Doble was the MIT genius that just about revolutionized the automobile industry and made steam a viable competitor with the internal combustion engine.

-Ron

[fredrosse]

Blowdown Issues - Getting the most from blowdown procedures has some tricks that we can be using:

When blowing down a boiler drum, the internal water inventory is at saturation temperature. When steam/water is released, pressure (and saturation temperature) goes down. Some of the water "flashes" to steam the while this is happening, and turbulent bubbles are formed throughout the boiler. Also some residual heat in the boiler metal transfers heat to the water mass, generating additional steam bubbles.

One can optimize the process of stirring up the water, thus getting more crud and internal deposits mixed into the water, where it is blown out of the boiler. If you blowdown at 150 PSI boiler pressure, the volume of the steam bubbles is small, and if you blowdown at 15 PSI boiler pressure, the bubble volume is more than 5 times larger for the same quantity of "flash" steam, so there is much better turbulence available to mix up the crud into the water.

So, at the end of the day's steaming, the best way to clear deposits out of the boiler is to let steam pressure fall to about 15 PSIG, then release large quantities of steam (open the safety valve or dump steam thru another valve), while simultaneously opening the bottom blow valves. Bottom blow valves should be "quick opening", there are specific blowdown valves for this service, but a much less expensive full port ball valve (steam rated) does the job very well. This method generates lots of turbulent mixing, and is more likely to get the bad stuff out of the boiler. If you are emptying the boiler completely, this should be done with no fire. If you are not emptying the boiler, just blowing down while keeping the water level within the sight glass, then firing can be in action.

The pressure and temperature rating of the piping, or hoses, carrying the blowdown needs to be correct for safety. If you blowdown with 150 PSI, then the piping (or discharge hose) will see very nearly 150 PSI, and 365F, requiring expensive steam hose. If you wait till you only have 15 PSI in the boiler, then the piping/hose will only see 15 PSI, at 250F. I recently purchased washing machine hose that is rated for 2500 PSI and 250F (at Home Depot), ideal for my blowdown conditions. I can mount a small (3/8 inch diameter) lance to the blowdown hose, and clean anything with ease. Steam/water blowdown cleans off machinery far better than my 3000 PSI pressure washer.

Blowdown at either condition can cause serious burns, so be aware of where the blowdown is going to go, and that everything is in proper condition.

[DetroiTug]

Fred,

Those are good things to know. I understood it was supposed to be wide open and fast, but had not considered the sudden drop in volume, sudden drop in pressure without temperature drop causing violent bubbling.

-Ron

[Lopez Mike]

On my little VFT30 I can feel the turbulence increase as the pressure drops from 130 to much lower pressures. Just a giant roar to start and then a much lower rumble and vibration as the gauge drops past 20-30 p.s.i.

Next time I will let it cool down to 15-20 before blowing it down.

It is interesting that the first blast on opening produces the dirtiest mess. Perhaps, as Fred suggests, tells me that to get rid of most of the gunk I don't need to blow down all the way. I blow down dry before trailering to save weight and before storage for obvious reasons.

[DetroiTug]

On the Ofeldt car boiler which only runs city water, the first bit looks like black paint, must be the mill shale turning loose on the inside. Of course, this is Detroit so who knows what it is

-Ron