what is the use of circulation pump in boilers?
It is a waste of energy to try to move the condensate back to the boiler using the steam's pressure. Makes the heating loop extremely inefficient
A boiler circulating pump is often used to pump water from the boiler through a heat exchanger - for instance an exhaust gas economiser located in a ship's exhaust uptake or a heat exchanger in a nuclear power plant. The allows the boiler to be used as a steam / water drum while the heat necessary to produce steam is provided by an external source. In some cases circulating pumps might be used especially in a tank type boiler, e.g., a Lancashire or Scotch boiler to prevent dead spots in the boiler where there is little or no movement of the water a consequent cold or hot spot. It helps keep the temperature constant throughout the boiler keeps the water moving around the heat transfer surfaces. If an isolated part of the boiler becomes overheated it can weaken it there is a possibility of failure. If part of the boiler is colder than the rest of it, it can cause mechanical stress of the boiler structure.
