This article focuses on boiler feed pumps in power plants, exploring their key roles and structural traits. Feed pumps, condensate pumps, and circulating water pumps each play vital roles in water supply and cooling within power systems. It then details the DG-type multi-stage boiler feed pump's structure, from stator and rotor components to balance mechanisms, offering insights into its design and functionality.
1.Functions of boiler feed pumps in power plants:
1) The function of the feed pump is to increase the pressure of the deoxygenated feed water with a certain temperature in the deaerator storage tank and then deliver it to the boiler to meet the water demand of the boiler.
2) The function of the condensate pump is to boost the pressure of the condensate in the hot well of the condenser and send it to the regenerative system.
3) The function of the circulating water pump is to supply cooling water to the condenser of the steam turbine for condensing the exhaust steam of the steam turbine. In power plants, the circulating water pump also provides cooling water to oil coolers, water coolers, air coolers of generators, etc.
2.Structural characteristics of boiler feed pumps in power plants:
The DG-type multi-stage boiler feed pump in power plants is a horizontal multi-stage single-suction segmental centrifugal pump, with a single-shell, single-suction, multi-stage horizontal segmental centrifugal pump structure. The inlet of the multi-stage pump is vertical, and the outlet is vertically upward. The specific structure is as follows:
Stator part: It is mainly composed of the front section, middle section, guide vane, rear section, bearing frame, balance chamber cover and other parts, which are connected into one body with through rods and nuts. The side shoulders of the front section and rear section are fixed on the pump base with bolts and nuts.
Rotor components: They are mainly composed of impellers, impeller sleeves, balance sleeves, balance discs and shaft sleeves, which are fastened with small round nuts and fixed on the shaft, and flat keys are used for anti-rotation. The entire rotor is supported on the bearings at both ends. The rotor is directly connected to the motor with an elastic pin coupling. A toothed gasket is installed between the last stage and the balance sleeve to compensate for expansion, and this part should be replaced during pump maintenance.
Balance mechanism: This pump adopts a balance disc hydraulic balance device that can completely and automatically balance the axial force, which consists of four parts: balance plate, balance disc, balance sleeve and balance sleeve.
Rotation direction: Viewed from the motor end, the pump rotates clockwise.
Material of main parts: Except that the flow-through parts of DG85-80 and 200DG43 pumps are made of cast steel, the rest are made of cast iron.
Complete set scope: The complete set includes pumps, motors, check valves, gate valves, common bases or their own bases.
