In a boiler feedwater system, a BFP or boiler feed pump is used to raise the water pressure to a level where it can be pumped into the boiler drum. It aids in the proper operation of a boiler by ensuring a constant supply of feed water. For steam boilers, a continuous supply of feedwater is essential, as it prevents overheating and further damage to the boiler.
Parts of BFP:
- Shaft Sleeve
- Balance Chamber
- Wear Rings
- Mechanical Seal
The Functioning of a Boiler Feed Pump:
A boiler feed pump aims to transfer condensate boiler feed water from the hot well to the boiler drum. As the shaft and impeller rotate in the same direction as the surge, the hot feedwater is thrown outwards radially through the pump’s walls. As a consequence, the fluid’s velocity and pressure increase.
As it is directed to the following impeller blades along the flow line, the fluid is now accelerated and thrown radially outwards through the casing. After such a steady increase in flow rate and pressure with each impeller, we finally hit the pump outlet pressure. The pressure at the pump’s final outlet exceeds the boiler’s normal working pressure.
A multistage boiler feed pump with two or more impellers in series is used to produce such high pressure. Each impeller’s pressure is multiplied by the force provided by the others. The power of a pump is determined by the distance between each stage of the fluid passageway. The total pressure is calculated by the number of impellers in series, while the impeller size largely determines the pressure at each step.
As part of the feed pump’s operation, the temperature differential between the suction and discharge sides must be controlled. The temperature difference should never be greater than 60-70 degrees Celsius to avoid thermal shock damage. The feedwater system’s feed pump takes suction from the hot well through a strainer and discharges to the boiler through an orifice plate and feeds check valve. Also it is important to know how much a new boiler costs.
How to Start a Boiler Feed Pump:
To start the pump, we need to line up the machine and follow the steps below:-
- Make sure the hot well has at least a minimum feedwater level.
- The temperature difference between how well feed water and boiler water must be held between 0 and 60 degrees Celsius at all times.
- Check to see if the pump is ready, and if it isn’t, take the necessary steps to prime it.
- Activate the pump’s suction hand.
- Using the discharge valve, close the discharge side.
- Now open the air pipe outlet to let the trapped air out.
- Ascertain that the seals have an adequate supply of lubricant.
- Activate the pump.
- When all of the air inside the pump has escaped the pump mechanism, close the air pipe outlet.
- Keep an eye on the suction pressure of the pump.
- If the pump has reached its maximum rpm, slowly open the discharge valve.
- Now keep an eye on the discharge pressure for a while.
- Check the temperature of the bearings.
- Last but not least, check the pump flow rate.