A condensate trap is a PHASE separator – usually a liquid phase is separated from a co-mingled vapor phase. The objective is to obtain a separation of phases to enable the subsequent handling of each in a separate and independent manner.
The basic difference between a steam trap and a condensate trap is the mechanical design of each. The process design of separating both the steam and the steam condensate is identical in scope. The mechanical design addresses the need(s) to remove the liquid condensate manually or automatically – and if automatically, in what manner. The conventional steam trap design is approached in basically two different manners:
1) a displacer float to regulate the draining of the condensate while maintaining a liquid seal between the steam system and the external drain target;
2) a thermal sensor device that allows drainage of cooler condensate that collects in the trap;
There are also "thermodynamic" traps that drain in response to velocity changes between compressible steam and incompressible condensate fluids.
A condensate trap only works as a positive liquid draining apparatus. It usually employs a chamber where the condensate collects and is measured in volume or height by a level transmitting device that activates a drain valve in accordance with a pre-set condensate level. In this respect, it works much like the first type of steam trap mentioned above.
In all above cases, the basic idea is the same: remove condensed steam within the system as fast as it is being formed in order to ensure a steady live steam supply within the system.