Condensate management

Wherever steam is used for indirect heating in heat exchangers condensate also forms and should whenever possible be returned to the steam boiler circuit or used for some other purpose.

Reusing accumulated condensate is one of the key measures which can be taken to ensure cost-effective energy-efficient operation of a boiler system.

Condensate has two characteristics that make it particularly valuable:

• High temperatures
  The condensate downstream of the heat exchanger is normally only slightly undercooled, i.e. it is at a high temperature. By recirculating the condensate, this energy content remains in the system and does not have to be expended again.
• Treated water
  Condensate is already treated hardness-free water with a low conductivity. Returning condensate to the steam circuit therefore saves make-up water. This means that less softening or demineralisation of water is required which reduces the amount of energy and chemicals used and these treatment systems can be sized smaller from the outset.

The condensate can be reused in different ways:

• As preheated boiler feed water
  by returning it to the feed water vessel via condensate pipes and tanks or by feeding it directly into the boiler.
• As hot water
  for heating of processes at a low temperature level, e.g. for cleaning.
• As steam
  by using the expansion steam in a secondary low-pressure steam network for consumers requiring lower temperatures.

Before the condensate can be reused, it must first of all be checked for contamination and collected in a tank. This can be done either in an open or closed condensate collection system.

Info on Water quality monitoring

The differences between the two systems are highlighted in the following table:

Comparison of different condensate collection systems