PHOSPHATE/CHEMICAL ADDITION IN BFW

[ommuruga]

HI:

Can anyone give me a step by step procedure for injecting
phosphate or chemical in boiler water.
Please comment on the following procedure:

1. Add water in mixing tank.
2. Add tri-sodium phosphate solution to tank.
3. Start mixer (motor).
4. Open mixing tank outlet to dosing pump.
5. Start pump and line up phospate to boiler water.

Or should the pump be started on water first and the
phosphate to be added later??

Where can i accurate information on this, are there
any websites or handbooks??

 

[samuelliu]

The phosphate used for boiler can be fed directly to suction of BFP, but more commonly to the drum. Both require a pump to overcome the pressure.

 

[mur]

Ommuruga,

It looks like you are writing a procedure for others to use
step 5 - line out the valving before starting the pump.
the rest looks basically ok.

One suggestion, if possible run a small line from your BFW header into the chemical injection pump discharge header ( exit the pump discharge valve) this will decrease the time lag significantly between making changes to the pump stroke / chemical composition and changes to the boiler chemistry

 

[Bahrin]

The outlet of the dosing pump must be conected via a non-return valve to the inlet of the boiler feed water pumps. This non return valve is in the standard delivery of the dosing unit. It is very good to start the dosing pump at the start of one of the boiler feed water pumps (it is possible using two relays).One more thing:you need a loop for cooling between non-return valve of the dosing unit and the inlet of the boiler pumps.