Metal Plating Plant- Welded Header Repair and Fuel Savings Update

Steamhead

This plant does government work exclusively so we won't post its name or precise location. It has a row of tanks into which the work is dipped from an overhead gondola. The tanks contain various chemicals and those requiring heat have steam coils in their bottoms. The first pic is a view of their tank line.



The original installation consisted of an overhead steam main and overhead dry return running from the boiler room to the end of the tank line. Air and water left the coils through bucket traps mounted at about the rim level of the tanks (4 feet above ground), then lifted past check valves via steam pressure another 8 feet to the dry return.



Not only did they have to maintain 10-12 PSI in the boiler to accomplish this, but the check valves would close if vacuum formed in a coil. In one case, a coil developed a leak and the vacuum pulled some of the solution from the tank into the coil. This made for an interesting service call. 



Our solution was to run a new 2-inch dry return below the tank rims, with the trap discharges draining by gravity into the new line. Check valves were no longer needed. The new line terminates in a small Hoffman condensate transfer pump which lifts the water into the original overhead return. From there it flows to the boiler-feed pump. We did this work last year and hadn't been back until yesterday



The second two pics show the overhead piping. Note all the plugged tees in the overhead return- these were where the coils originally discharged.



We repiped the end-of-main trap also, so it would drain to the transfer pump rather than up into the overhead return.

Steamhead

Behind the Tanks

we see the new piping and transfer pump. The traps discharge down into the new return.



Each coil has a solenoid valve that turns the steam on or off. The valves are controlled by a programmable-logic controller (PLC) which gets its info from a thermocouple in each tank.



The system now maxes out at 4 PSI, using a 4-PSI Vaporstat so no one can crank the pressure up higher. The owner says they've saved about 23% on their gas consumption with the new setup. And the additional tank lines they're planning will now be heated with steam rather than electric-resistance. This will make them safer to operate.



Steam is king in this plant.

Steamhead

Today's repair

was a leaking 3-inch riser from the boiler. The riser was welded except for the joint at the boiler, and the threads failed at that point- not sure if it was an expansion or pH problem. Regardless, we had a welder install a thread-o-let on the header, and rebuilt the riser with nipples and threaded fittings. It can expand in two planes the way we installed it.



We also changed the brass gauge/pressure control piping to stainless steel, which will survive better in this harsh environment, added blowdown lines from the new stainless piping so they could verify that the pigtails weren't plugged, and fixed a few other minor things.



The boiler is a Smith 19A-7, with a PowerFlame gas burner. Gordo is in his classic big-wrench pose ;-)

Steamhead

Gordo found the "Before" pics

so here they are. You can see the old piping details as well as the shape the boiler was in. 

gerry gill

thats really cool.

i bet it was fun to do something a bit out of the ordinary! It always amazes me to see an engineer design something that requires the boiler pressure to lift the condensate..good fix..are they going to keep you updated on the dollars saved?

Steamhead

I hope so

the system is in pretty good tune now so there might not be much more low-hanging fruit. It will be interesting to see how much the new lines affect gas consumption.



And of course, the engineer doesn't have to pay the fuel bill, does he?