The modern high pressure boiler feed pump is a kind of complex equipment with high parameter and large capacity. It is the medium of high pressure near the saturation temperature of the water, often required to be able to adapt to a wide range of changes in the flow of the work, it's head, suction pressure and water temperature will change accordingly. It is pure water, but when there is foreign particles into the system, the integrity of the seal gap is destroyed.
In order to adapt to the increase of the capacity of the modern high pressure boiler feed water pump, it is necessary to study the characteristics of the feed water pump, such as flow rate, head, suction pressure, speed and drive mode, as well as the structure and precision.
1. Modern high-pressure boiler feed pump has two drive modes: one is the water pump driven by steam turbine special, its speed up to 5000 ~ 6000 rpm; the other is by the motor through gear speed after the feed pump driven by variable speed hydraulic coupling, it is as high as 5000 ~ 6500 rpm. In order to obtain high flow and pressure, it is one of the most effective measures to improve the speed of the pump. On the contrary, if the impeller diameter increases, the efficiency of the pump will be reduced, this is because the disc friction loss and impeller diameter of the five proportional.
2. In the new modern thermal power plant, most of the thermal system is open cycle. In the deaerator feedwater pump by vaporization under the pressure of the water intake. The working condition of the water supply system determines the suction condition of the boiler feed water pump. With the increase of the unit capacity and high speed pump, it is necessary to increase investment to improve the deaerator to a higher altitude, in addition, is added to a low speed booster pump (also called forepump), to improve the suction pressure of the boiler feed water pump to prevent the occurrence of cavitation.