Drip Leg on Steam Mains

Unless you hung around long enough to catch that trap belching, the first thing to do is check it for blow-by. I can see that you're not developing a water column in this particular drop or it is condensing continually. What are your op specs. Temp, press, chemicals, loop, process?

Of great concern is the risk of personnel coming into contact with uninsulated steam pipes, and incurring burns!

With all due respect, I think that your priorities are a bit "off". You're worried about a bit of heat loss at the legs?? That's nothing compared to the enormous amount of money that's being lost because you're dumping the condensate to ground . Think about it:

• additional chemicals,
  
• make-up water,
  
• energy to pre-heat the make-up water

With a properly designed condensate return system you'd be saving a bundle. Furthermore, you might even be able to generate additional free low-pressure steam with a flash recovery system.

Corrosion under insulation is a major problem with steam(p) trap lines, so be wary of doing it where lines are below about 120 degC, but please install personnel protection around lines, valves and traps.

Then contact your local steam trap manufacturer of choice (here is just one of many)and get him to do a survey and make a proposal for a design and maintenance contract for all your steam traps and condensate return needs. It will save you money in the long run.

I think the term is Drop leg.

Thank you for your comments they are all helpfull in a different way.

RDGRNR I don't know the exact design and I am trying to understand it. Sat'd Steam at 3,5 bar(g), semi open loop for steam and this is a fertilizer complex.

PWSlack You are right there is a risk of burns but my point is energy loss.

BoltIntegrity You are absolutely right the condensate return loop is on our schedule but what I wonder is are we condensing steam unintentionally just because the legs are not insulated.

Kaisan Your recommendations are all valuable

Abdel Halim Galala Heat loss via condensation of steam was my point actually. Your comments strengthened my idea about it.

Ideally, all of the steam's latent heat should be used in the intended process application. Inevitably, there will be losses in the distribution system. The more effective the insulation, the less the loss of energy. Of course your lines should be insulated .

Expanding on somebody else's comment: Certain types of steam traps only discharge when the upstream condensate is sub-cooled. These include bimetallic and liquid/solid expansion (thermostatic). Therefore, a certain uninsulated upstream run is a good idea lest condensate backs up into the main. Usually, a properly designed drip pocket (same size as the steam main) is sufficient. This should also be insulated since any pooled condensate will sub-cool in the pocket. Your photo doesn't suggest any drip pockets. It seems that the smaller-sized drip legs come directly out of the main. This is not very effective at all since there is no effective collection point for the upstream condensate. As a result, you're likely experiencing downstream erosion of the lines and control valves. Additionally, with wet steam, your process will require more energy.

As I had mentioned, the energy loss from the uninsulated drip legs is absolutely puny compared to the costs arising from the inefficiency of your system in general. I suggest that you get some help from a competent steam trap supplier. The good ones are usually well-versed in system analysis and should be able to provide you with suggestions. Some may charge for a "survey" while others will do it for free. Choose one based on the team's competency rather than cost. Otherwise you'll only end up with lots of shiny new traps slapped onto a poor system .

Can you zoom into the area where there appears to be a cross (about a meter square) and post it? Also, RDGRNR is correct asking for specs, etc. Does all of your steam go to the process with a large % makeup?

How many traps are in your system, what size and style. Plus, do you have a cost of fuel per BTU? We can perhaps walk you through a survey to estimate your losses.

I have been out of the action for over 20 years now, but back in the 1980's a single 1/2 inch line, at 150 psi cost $50,000 per year in lost energy and chemicals for make up water.Install a trap and condensate return system.Some are available that use steam pressure to return steam to the boiler,so no electrical supply is needed to run a return pump.

HTRN

I think the legs are uninsulated to allow the condensate to subcool to alow Thermostatic traps to work effectively.

The real advantage of recircing the condensate is that it is already 'clean'. Boilers last longer on clean water. An RO system will greatly extend operating life and are pretty much automatic. A service contract with some one like Watercare International, there are many others, will cover installation and rental of the plant, servicing and regenrating the RO and Demin Vessels, etc. There are two ways of getting water out of steam lines. A 'Float' valve or a 'Thermal' valve. Wrap up the thermal valve and the drip leg may flood then water is carried on and into other equipment. Changing to 'Float', lagging well, and maybe increasing the drip leg volume will improve performance. Condensate recovery can be by a vacuum system but this introduces air which increases corrosion in the system. Otherwise take what you can to a closed sump and use (steam) pressure to drive it back to the source. (Frost Protection?).