Where heat is applied to a process via a heat exchanger, the steam surrenders energy as latent heat as it condenses to hot water. This water is lost, or ( usually) collected and returned to the boiler. Re-using condensate has four objectives:
●re-using the energy contained in the hot condensate
●saving the cost of the (raw) top-up water
●saving the cost of boiler water treatment (the condensate has to be treated)
●saving the cost of waste water discharge (where applicable).
Condensate is collected at atmospheric and negative pressures. The condensate may originate from steam in appliances at a much higher pressure.
No data submitted.
The technique is not applicable in cases where the recovered condensate is polluted or if the condensate is not recoverable because the steam has been injected into a process.
With respect to new designs, a good practice is to segregate the condensates into potentially polluted and clean condensate streams. Clean condensates are those coming from sources which, in principle, will never be polluted ( for instance, coming from reboilers where steam pressure is higher than process pressure, so that in the case of leaking tubes, steam goes into the process rather than process components into the steam side). Potentially polluted condensates are condensates which could be polluted in the case of an incident (e.g. tube rupture on reboilers where process-side pressure is higher than steam-side pressure). Clean condensates can be recovered without further precautions. Potentially polluted condensates can be recovered except in the case of pollution (e.g. leak from a reboiler) which is detected by online monitoring, e.g. TOC meter.
The recovery of condensate has significant benefits and should be considered in all applicable cases ( see Applicability, above), except where the a mount of condensate is low ( e.g. where steam is added into the process).
Energy Efficiency (2009) 3.2.13