Plate & Shell Heat Exchanger (PSHE): System for control condensate

 Control valve is installed on hot side outlet connection, i.e. condensate side. When valve is closed, unit is filled with condensate, heat transfer area is filled with condensate and heat load of unit is smaller.

When more heat load is required the valve is open, allowing the condensate to leave the exchanger, to secure more heat transfer area for incoming steam. In these systems, the condensate is sub-cooled because of the condensate level in PSHE; worth mentioning that a sufficient condensate level is required to achieve sub-cooling.

Amount of sub-cooling is result of water temperature and needed capacity.

Pressure difference between steam and liquid side must be measured: liquid side pressure has to be 0.5 bar higher than steam side pressure to avoid boiling and cavitation.

If this pressure difference decreases lower than 0.5 bar, steam inlet and condensate outlet flows have to be closed automatically or liquid pressure must be increased.

Advantages:

The condensate will be sub-cooled.

A smaller (and cheaper) control valve can be used

Credits 

Tomislav Marković tomislav@euroheat.co.rs

EUROHEAT office@euroheat.co.rs