The challenge
A leading electricity producer needed new clean-water heating for the washrooms of a site building, supplied with steam from a central heating plant. The water had always been heated in large storage tanks with steam lances. At the same time, the condensate collecting vessel sent its flash steam into the open air through the roof, all day.
The solution
The site moved its clean-water supply to steam-to-hot-water heating stations with condensate back-up control, and put a Jetomat® (Baelz 590) upstream of them:
- Motive steam at 8 barg drives the Jetomat.
- It draws about 260 kg/h of flash steam at around 102 °C from the condensate collecting vessel: vapour compression.
- The mixture leaves at 4 barg, about 1,170 kg/h, and feeds the heating stations, which hold the water at 60 °C.
The results
- About 260 kg/h of flash steam that used to vent through the roof now heats water
- About 22% of the steam the heating stations use is recovered flash (260 of 1,170 kg/h)
- About 2 tonnes of flash steam a day reused, with the heating running 8 hours a day
- The visible plume from the roof is considerably reduced
Why it works
The Jetomat is a steam jet thermocompressor: high-pressure motive steam expands through its nozzle, draws in the low-pressure flash steam and recompresses the mixture in the diffuser to a pressure a consumer can use. The variable nozzle lets the motive-steam flow follow the heating load.
Takeaway
Wherever a condensate vessel vents flash steam and a steam consumer sits nearby, a Jetomat can lift the flash back into service. On this site it supplies more than a fifth of the steam for the clean-water heating.
