Efficient Steam Recovery with Vahterus Vent Condenser

At the end of 2009, technicians at DONG’s combined heat and power plant (acquired by VEKS in May 2012), in Köge, Denmark, contacted one of our distributors about the replacement of an existing heat exchanger.

Together, they found great potential for energy saving. For years, DONG and Junckers, to whom the former supplies steam, had lived with high flash-steam leakage from various return pipes. By utilising this heat, significant energy savings could be made. Junckers’ press facility uses steam, which is condensed and returned at 3 bar (g). Condensate, which comes from the presses, is collected in two large flash vessels that separate flash steam and condensate from each other. When the condensate is pumped back to common flash vessels at VEKS’ CHP plant, the flash steam is reused in Junckers’ other steam applications.

Moreover, a significant amount of hot condensate (3 bar g, 143°C) is pumped back to the CHP plant. Because the flash vessel is open (vented over the top) and the condensate can only exist at 100°C at atmospheric pressure, the condensate of 143°C creates a large amount of flash steam (8.3%), which is released through two vent pipes over the roof.

It was Vahterus’ Vent Condenser that provided a solution for this energy leakage. In order to condense the excess steam, the condenser requires cold water. At VEKS, cold condensate from another condensate vessel located close by could be used. The cold condensate is circulated in the plate pack and the flash steam is condensed in the shell. The condensed steam is returned to the flash vessel, saving a lot of excess water, which otherwise would have evaporated through the flash steam. All this is on top of the energy savings gained by the recovered heat.

Since the new heat recycling installation, VEKS (formerly DONG) has found several warm condense pipes containing flash steam from which heat can be recovered in the Vahterus Vent condenser. The particular heat exchanger is a Vahterus PSHE 4HH-128/1/1 recovering 1.3 MW.