DG type sub high pressure boiler feed pump

The DG type high-pressure boiler pump is a single suction, multi-stage segmental centrifugal pump. The pump casing can be disassembled axially at the axis. The DG85-80 × 8 pump has a vertical upward suction port and a vertical upward discharge port, perpendicular to the axis. From the direction of the drive end, the water pump rotates clockwise. According to user needs, it can also be produced to rotate counterclockwise. Users can specify this when placing an order.

　　boiler feed pumpThe pump body and pump cover form the working chamber of the impeller, and there are pipe screw holes for installing vacuum and pressure gauges on the inlet and outlet flanges. The lower part of the pump body has pipe screw holes for discharging residual water.

The impeller is a single suction closed type, equipped with a balance plate to balance the majority of axial forces, and a thrust bearing to withstand the possible residual small amount of axial thrust. The arrangement of the bearings keeps the shaft in a stable pulling rod state. Before assembly, the impeller must undergo strict static balance verification to ensure smooth operation.

The pump shaft is supported by two Babbitt alloy sliding bearings, which are installed in the bearing body of the pump suspension and lubricated with thin oil.

A sealing ring is installed on the pump body, which can improve the volumetric efficiency of the pump and prevent high-pressure water from flowing back into the suction chamber, disrupting the inlet flow field and ensuring the suction performance of the water pump.

The shaft seal is generally a soft packing seal. When the water pump is working, a small amount of medium can be introduced to the packing box, or external cooling and lubricating water can be connected to serve as a water seal and cooling and lubricating function. According to the user's needs, the packing seal can be changed to a mechanical seal.

Flow range: Q=100~580m3/h (DG high pressure)
Q=36~180m3/h (medium pressure, sub high pressure)
Head range: H=740-2150m (high pressure)
H=409~1056m (sub high voltage)
H=270-672m (medium pressure)
Transport temperature: -20-205 ℃ (please declare if above 150 ℃)
Inhalation pressure: 0-7.5MPa (please declare if higher than 0.5 MPa)
Sealing form: packing seal, mechanical seal

Model example: DG45-80 × 6

DG - Single suction multi-stage high pressure boiler feed pump

45- Pump design point flow rate

80- Pump single-stage head

6- Pump Stage

DG type sub high voltagemultistageStructure and performance of boiler feedwater pump:

　　Main component materials:

Inlet and outlet sections: ZG230-450Mid section: ZG230-450Guide vane: QT450Impeller: QT450

Spindle: 40CrSealing ring: QT450Shaft sleeve: HT250Balance disk: ZG2Cr13Balance ring: Tin bronze

Bearing balance: The rotor of the DG type high-pressure boiler pump is supported by rolling bearings at both ends of the pump shaft. Lubricated with thin oil and cooled with circulating water, the axial thrust of the rotor is automatically balanced by a balance plate. The balanced return water returns to the pump suction section through the balanced return water pipe.The rotor of the DG type sub high pressure pump is supported by sliding bearings at both ends of the pump shaft. Lubricated with thin oil and cooled with circulating water, the axial thrust of the rotor is balanced by a balance plate. There is a return pipe installed between the balance chamber and the front section.The rotor of the DG type high-pressure boiler pump is supported by sliding bearings at both ends of the pump. The bearings are lubricated by force, and the pump itself is equipped with an oil system. The axial thrust of the rotor is balanced by a balance plate. And it is equipped with thrust bearings to withstand residual axial forces caused by changes in working conditions, and a return pipe is installed between the balance chamber body and the suction pipe.

Transmission: medium voltage, sub high voltage typeMulti-stage pumpDriven by an electric motor through an elastic coupling. From the transmission direction, the pump rotates clockwise. The high-pressure pump is driven by an electric motor through an elastic coupling, or can be equipped with a toothed coupling, diaphragm coupling, or hydraulic coupling according to user needs. The prime mover can be driven by a small steam turbine or an electric motor. From the transmission direction, the pump rotates clockwise

DG type sub high voltagemultistagePerformance parameters of boiler feedwater pump:　　

Installation steps for water supply pump:

1.1 Preparation work

Before assembly, all pump parts, especially the precision machined surfaces that cooperate with each other, must be thoroughly cleaned.

1.1.2 Count all parts and classify and number them according to the assembly order.

1.2 Assembly of pump components

1.2.1 Pay attention to installing the middle sealing ring to prevent it from falling off.

1.2.2 Pay attention to the anti rotation pin of the guide vane.

1.2.3 Tighten the pump body through the rod nut proportionally to maintain appropriate tension. If it is too loose, it will cause leakage at the middle joint surface, and if it is too tight, it will cause deformation of the stator components. The torque of the wrench during assembly is about 5550 Nm. Tighten the cross bar according to the scale.

1.2.4 After the threaded rod is basically tightened, use a dial gauge to find that the front and rear sections are not parallel and should be ≤ 0.1mm. 1.3 Measure the total amount of rotor string, which should meet the requirements of the drawing.

1.4 Install the front cover and low-pressure end cover bearings and lower tiles, and lift the shaft to the center position.

1.5 Use specialized lifting tools and dial gauges to check the end face runout of the balance sleeve, which should meet the requirements of the final assembly drawing.

1.6 Assemble rotor components and tighten locking nuts. The measurement of the string after installing the balance plate should meet the requirements of the final assembly drawing.

1.7 Install the head and tail covers at both ends, the bearing body, and the top and side clearances of the bearing shell, which should meet the specified values for the quality requirements of the bearing shell.

Adjust the center of the bearing shells on both sides and tighten the adjusting nuts after adjustment.

1.9 Assembly of thrust bearings

1.9.1 The assembly of thrust bearing components should be scraped and ground according to the requirements of the bearing components, and the thrust pad should rotate flexibly during assembly. 1.9.2 After installing the thrust bearing, the axial clearance between the balance plate and the balance sleeve should be 0.04-0.08mm according to the requirements of the final assembly drawing, and the adjustment of the clearance should be achieved using an adjusting ring.

After adjusting the clearance, install the thrust bearing and thrust disc, and tighten the locking nut.

Adjust the gap cushion between the thrust bearing seat and the thrust plate to ensure that the final assembly drawing meets the requirements for the clearance of the thrust bearing.

Instructions for use:

1、 Start up

Before starting the pump, the pump rotor should be rotated to check if it is flexible;

Check if the motor direction is consistent with the pump direction;

Open the suction valve of the pump, close the gate valve and pressure gauge plug of the pump outlet pipeline, fill the pump with liquid, or use a vacuum system to remove the suction pipe and air inside the pump;

Check the tightness of the connecting bolts between the pump and motor, as well as the safety situation around the pump, to prepare the pump for start-up;

Start the motor and wait for the pump to operate normally. Open the pressure gauge plug and slowly open the pump outlet gate valve until the pressure gauge pointer reaches the desired pressure (control the pump's given head according to the outlet pressure gauge reading).

2、 Run

The pump relies on the balance mechanism inside the pump to balance the axial force. There is balance liquid flowing out of the balance device, which is connected to the inlet section through the balance water pipe, or a short pipe is designed outside the balance room. The balance liquid flows out of the pump through the short pipe. To ensure the normal operation of the pump, the balance water pipe must not be blocked;

During driving and operation, attention must be paid to observing instrument readings, bearing heating, packing leakage and heating, as well as pump vibration and sound to ensure that they are normal. If any abnormal situations are found, they should be dealt with in a timely manner;

The temperature rise of the bearing reflects the assembly quality of the pump. The temperature rise of the bearing shall not exceed 35 ℃ above the ambient temperature, and the maximum temperature of the bearing shall not exceed 75 ℃;

There is a certain axial displacement of the pump rotor during operation, which should be within the allowable range, and the clearance value between the end faces of the motor and water pump couplings should be ensured;

During the operation of the pump, the wear of the impeller, sealing ring, guide vane sleeve, shaft sleeve, balance disc and other parts should be regularly checked. If the wear is too large, it should be replaced in a timely manner.

3、 Shutdown

Before stopping the machine, the pressure gauge plug should be closed first, and the outlet gate valve should be slowly closed. After the outlet valve is closed, the motor should be stopped. After the pump has stopped steadily, the suction valve of the pump should be closed; If the water in the pump is released and it is not used for a long time, the pump should be disassembled, cleaned, oiled, packaged and stored.

Assembly and disassembly:

1、 Precautions for pump disassembly

Park in the order of parking;

The liquid inside the pump casing (including cooling water) should be drained; When the bearing components are lubricated with thin oil, the lubricating oil should be drained;

Remove the auxiliary pipelines that hinder disassembly, such as balance pipes, water seal pipes, and lead wires;

The manufacturing accuracy of the parts should be strictly protected during disassembly to prevent damage. At the same time as disassembling the through rod, each middle section should be cushioned with blocks to prevent the loosening and sinking of the middle section joints from bending the shaft.

2、 The disassembly sequence of the pump

Unscrew the bolts on the discharge side bearing end cover and the connecting bolts between the water outlet section, tail cover, and bearing body, and remove the bearing end cover, bearing body, and other bearing components;

After unscrewing the round nut on the shaft and sequentially removing the bearing inner ring, bearing cover, and retaining ring, remove the packing body (including packing cover, packing ring, packing, etc.);

After sequentially removing the O-ring seal, shaft sleeve, balance disk, and key on the shaft, remove the water outlet section, final guide vanes, balance ring sleeve, etc;

After removing the last stage impeller and key, remove the middle section and guide vanes; Remove each stage of impeller, middle section, and guide vanes in this order until the front stage impeller is removed;

After removing the pump coupling, unscrew the connecting nuts between the inlet section and the bearing body, as well as the bolts on the bearing cover, and then remove the bearing components on the inlet section side;

Extract the shaft from the inlet section, unscrew the fixing nut on the shaft, and remove the bearing inner ring, O-ring seal, shaft sleeve, etc. in sequence;

The disassembly sequence of pumps using sliding bearings is basically the same, with only slight differences when disassembling bearing components.

3、 Pump assembly

The assembly sequence of the pump is generally carried out in the opposite direction of the disassembly sequence. The quality of assembly directly affects the normal operation of the pump, as well as its service life and performance parameters. Attention should be paid to the following points during assembly:

The machining accuracy and surface roughness of the parts should be protected, and there should be no scratches or dents. Molybdenum disulfide used for sealing should be clean, and the fastening screws and bolts should be evenly stressed;

The alignment between the impeller outlet channel and the guide vane inlet channel is ensured based on the axial dimensions of each component. The quality of the alignment directly affects the performance of the pump, so the size of the pump cannot be adjusted arbitrarily;

After the pump assembly is completed, before filling, rotate the pump rotor by hand to check whether the rotor rotates flexibly in the pump and whether the axial displacement meets the specified requirements;

After passing the inspection, press in the packing and pay attention to the relative position of the packing ring in the packing chamber.