The returned condensate quality should be periodically checked to safeguard the boiler health.
Contamination in feedwater can enter from two sources, the fresh feedwater or the returned condensate. Common feedwater contaminants include:
- Excessive boiler treatment chemicals
- Miscellaneous metals and chemical compounds
Returned condensate ideally will not be a source of contamination to the feedwater system. However, in circumstances such as a leak in the steam coil of a heat exchanger or failure of a valve in a multi-utility coil can lead to contamination entering the condensate lines. Corrosion of the steam system including, the condensate return lines is yet another source of condensate contamination.
Contaminants in the condensate can vary from metals such as copper and iron to oils and process chemicals. Heavy metal contamination is usually originates from the construction materials of the process equipment and the condensate system. Oils and process chemicals are generally introduced into the condensate system due to process equipment failures or corrosion-caused leaks in equipment such as heat exchangers, pump and gland seals, etc. This results in the introduction of significant quantities of undesirable chemicals or compounds into the boiler. These contaminants lead to scaling of the boiler tubes and in some cases also corrosion of the tubes.
To safeguard the boiler against contamination from the condensate, boiler operators should periodically monitor the quality of the condensate returning to the feedtank. Alternately, modern condensate contamination detection system can also be used to automate the process of monitoring the condensate quality. These monitoring system continuously monitor the condensate quality and divert the condensate away from the boiler feed system in case it detects a drop in condensate quality.
Undetected, this contamination through condensate can lead to severe damage to the boiler health and poses a safety hazard. Consistent boiler water and feedwater quality monitoring and testing will provide the operating personnel not only with historical data, but also with timely warning any time feedwater quality changes dramatically.