Vacuum systems with Direct Contact Condensers

Staging of ejectors becomes necessary for economical operation as the required absolute suction pressure decreases.Based on the use of auxiliry equipment, two and three stage ejector can be either condensing or noncondensing types. Considering type ejectors have an intercondenser between ejectors that reduces steam consumption in later stages by condensing first stage operation steam and condensable vapors and cooling the air and other noncondensables. The inter condencer may be direct contact or surface contact types, arranged barometric or low level. Nearly unlimited applications as well as high operational reliability. The customised SANADID vacuum systems with direct contact condensers are approved and demanded solutions in the process industry. On the following pages you can find more information about the various application options.

The figure illustrated on the right achieves a suction pressure of 1 mbar. The temperature of the available cooling water determines which pressure can be reached in the first direct contact condenser. In this example, two ejector stages are series-connected to achieve a suction pressure of 1 mbar with the lowest possible amount of motive flow. Two further ejector stages compress the non-condensable components of the suction flow of the first direct contact condenser up to atmospheric pressure. When the condenser is mounted at barometric elevation,drainage is by gravity through a sealed tail leg so condenser and suction lines will not flood if steam service is interrupted or loss of vacuum occurs.

Advantages

• operation-free, robust operation
• approved operation for decades
• nearly unlimited application options

Disadvantages

• mixing of process and cooling medium in the direct contact condenser (can be keep balance by means ofvacuum system with surface condenser)