Why use a Condenser?Ejector systems can be divided into condensing units and non-condensing units. The usual method of staging is to use a vapour condenser between the stages.
Condensers are used to condense out motivating steam plus the suction vapour from the upstream stage, allowing only saturated non-condensables to pass on to the following stages.
The size and type of condenser used is a function of the air-vapour ratios, cooling water temperatures available, steam and water costs and contaminants in the first stage suction vapour.
The term non-condensing is used where a stage discharges directly into the following stage. Steam consumption in this type of system is higher because the second stage must handle the motivating steam plus the suction capacity from the first stage.
Non-condensing units are used where the interstage pressure is lower than could be obtained with the temperature of cooling water available.
Single Stage Vacuum Package with Pre and After Condensers (for Chlorine Plant)
Condenser functionsA condenser is used to reduce a vapour to its liquid state by removal of latent heat from the vapour. Its function as part of a steam jet vacuum system is to remove condensable vapour ahead of a given ejector stage, thus reducing the size of the ejector and the amount of steam required.
Condenser fuction may be defined as follows:
- Precondensers - Used for direct condensing of vapours from the process. Non-condensables removed from precondenser by one or more ejctor stages. The pressure of process must be sufficiently high to allow condensation with the available water supply.
- Intercondenser - Used between the ejector stages where two or more stages are required to compress non-condensables from a process or condenser pressure to atmospheric pressure, eliminating the handling of motive steam from a preceding stage.
- Aftercondenser - Used to condensate steam discharging from the last stage ejector at atmospheric pressure (near atmospheric). Non-condensables are vented into atmosphere.