Methods of Marine Boiler Water Dosing
The chemical manufacturers recommend the methods of adding the chemicals to the boiler and boiler feed water lines, along with the required doses following boiler water testing. However, standard chemical injection is carried out by using a high pressure metering pump, supplied by a mixing tank usually located above the pump.
It is important to use the lid of the tank not only to prevent any spillages, but also to prevent the dilution of the oxygen scavenging chemical by over-exposure to air.
The pump can be operated continuously, pulsed, or for a specific period. Chemicals for different purposes are injected to the boiler, the feed pipes, or auxiliary equipment as recommended by manufacturer.
Boiler feed softening chemicals should be fed into the feedwater supply just before the check valve, or into the water drum to enable reactions to take place outside the steam generating areas.
Chemicals used to combat dissolved gases, scale formation, and corrosion should be injected into the feed water system.
If the optimum purity of the boiler feed water is obtained, the metering pumps can be adjusted to a continuous supply of chemicals. I personally never achieved this state of euphoria on the old steamships I sailed on, in what now must seem like the dark ages to today’s seagoing engineers.
Reference Web: scribd - injection of chemicals