excess condensate down the drain?

stopgogo

Steam heating a building without domestic hot water... Got tons of hot condensate being drained down the sewer with an cold water injection. Is there something that can be done with all the excess condensate in a commercial building?
Just hate to see $$$ and energy being thrown down the drain , literally bye the LITER lol.

nicholas bonham-carter

Is this one-pipe, or two-pipe steam?
I assume this system has a condensate tank, which may be overfilling, and then overflowing down the drain. Did the system ever work properly? What sort of pressure is the system attaining, as verified by a low pressure gauge, (0-3 psi)?
How long has this been going on, and has any maintenance been performed to stop this? What controls the introduction of fresh feed water into the system-the tank?--NBC

Jamie Hall

No condensate should go down the drain. Not in a heating system. How is this system set up and controlled? Size of condensate tank, controls on condensate tank, is it a boiler feed pump or a condensate return pump? Etc.

JUGHNE

Define your "cold water injection" and/or post pictures of what you are referring to. Actually pictures of the entire boiler room system would explain a lot.

stopgogo

So here is how it usually goes:
For domestic hot water setups you have steam inc to heat exchanger to preheat cold water to sewer.

Heating: steam inc to heat exchanger to flashtank w/cold water injection to sewer.

Some buildings only use steam for heating while having electric boilers for domestic hot water. For those particular systems there is lots of condensate that gets dumped just wondering if there is something that can be done with all that energy.

EBEBRATT-Ed

Is this a district steam system and the condensate is being dumped rather than return it to the heating plant?? That's what it sounds like.

Unless you have a use for the hot condensate (you could preheat domestic hot water with it with a heat exchanger) there is nothing you can do. City codes require the condensate to be cooled before dumping it. Hence the cold water injection to cool it.

stopgogo

yes i know this. just thought maybe there was something we could do. also would the sewer department let a utility plant install condensate return lines vs digging up a street with way too many utility lines etc?

ratio

Where's the steam plant located as regards to the sewage plant? It may be that the sewers are the returns...

EBEBRATT-Ed

District steam always dumps the condensate as far as I am aware. I am suprised others don't seem to know this. But the only district steam I have seen around here is in Boston 90 miles from here.

Springfield used to have district steam years ago but it's long gone. Holyoke had district steam up to about 4-5 years ago. Everyone there had to install boilers when Holyoke Gas & electric shut down the district steam.

Hartford Steam Boiler (the Hartford loop inventors) still run a plant in Hartford as far as I know for district steam

JUGHNE

That is really enlightening....had no idea of that many BTU's going down the drain.....for maybe a century or so. Let alone the cooling water lost in addition to condensate water.
Just another nail of inefficiency in the coffin towards steam heat, district steam anyway.

Heat exchanger for pre heating DWH are probably common in these situations?? Still a lot of temp left over I imagine. Some creative water to water heat pump design might milk more out after the HX. Just a thought.

So the Empire State Building after their super green upgrade, I believe they are on district steam, are they milking the condensate before it heads to the sewer?

So how do they meter the customer usage of steam BTU?

stopgogo

I am technically not allowed to disclose any information about the work place and all.. but the plant has been built some 100 years ago so back then water was cheap and plentiful, no need for returns. Lots of our customers just end up dumping, and I'd love to find a solution to do something with this water. some have their own little boilers on each floor for dhw so we can't even preheat the cold in. its ok sometimes you just got to let it go i guess.... thanks for the help.

I do wonder if the city would let us use their sewer lines to install return piping back to the plant...but knowing bureaucracy that will never happen.

stopgogo

"So how do they meter the customer usage of steam BTU?"
incoming steam flow meters and or condensate meters are used to measure flow/usage.

EBEBRATT-Ed

They have steam flow recorders like they use in a power plant . You pipe a special orfice between a couple of flanges. On either side of the flanges are pressure taps. By measuring the differential pressure between the taps their control calculates steam flow.

I am sure they can measure condensate flow with a water meter and get it that way too. a pound of steam is a pound of water (assuming no leaks)

Google: Hartford Steam

Also

http://www.fluidcontrolsinstitute.org/pdf/resource/steam/ST108CondensateLineSizing.pdf

Mark Eatherton

Look at a reverse indirect for preheating DHW. Turbo2000.com will get you some information. The other things that could be done are snow melting (year round) to reject heat and save cooling water.

Restaurants and food processing plants have lots of hot water demand, and oddly waste a huge amount of heat.

A GreenFoX drain waste heat exchanger could extract additional BTU's, and then there is the Sewer Sharc. You can have it send the water into the sewer colder than it came in from the street.

Lot's of things you can do with waste heat recovery, when the base price of the fuel is ju$t right. With all the cheap natural gas, now is not a good time to justify it with $ $aving$.

It's about doing "the right thing"... Waste not want not.

ME

stopgogo

For steam flow for larger operations its best to use a magnetic flow meter, expensive but digital. Drilling orfices?
As far as recovery a plate hx is better for volume then a greenfox and has more surface contact for better recovery.

ME

jumper

Boiling hot condensate is good stuff.But you need a method to pump it. Otherwise can't use a plate heat exchanger.
If you can pump it, and nobody is looking, you can save water as well as energy by injecting it into DHW.

stopgogo

no