Purpose

1.1 D-type and DC type pumps are horizontal multi-stage centrifugal pumps. It is suitable for transporting clean water (with impurities less than 1% and particle size less than 0.1 mm) and other liquids with physical and chemical properties similar to clean water.
The temperature of the medium transported by the D-type pump is not greater than 80 ℃, and it is suitable for mining drainage, factories, urban water supply and other occasions.
The temperature of the medium transported by the DG type pump is not greater than 105 ℃, and it is suitable for small boiler feed pumps or similar hot water transportation occasions.
1.2 Performance range of this series (according to specified points):
Flow rate: 6.3 to 450 meters per hour
Lift: 50-650 meters
1.3 Explanation of Model Meaning

D(DG)155-67x9

D--Multi stage centrifugal water pump

(DG)--Multi stage boiler feedwater pump

155--Flow rate (m/h)

67--Single stage head (meters)

9--Series

Structural description

This type of pump mainly consists of a housing part, a rotor part, a balancing mechanism, a bearing part, and sealing components.
1. Shell part
The shell part is mainly composed of the suction section, middle section, discharge section, guide vanes, bearing body, etc., which are connected by bolts. The rotation direction of the pump is clockwise when viewed from the drive end.
2. Rotor section
The rotor part is mainly composed of a shaft and components such as impellers, shaft sleeves, and balance disks mounted on the shaft. The components on the shaft are fastened with flat joints and shaft sleeve nuts to integrate with the shaft, and the entire rotor is supported in the pump housing by bearings at both ends. The number of blades in the rotor component is determined based on the number of pump stages.
When using this model of pump, the shaft seal must be connected to the water seal. There are two types of water seals used: one is to use the effluent from the first stage impeller, and the other is to draw in external water. All items in Table 2 that indicate water seal connection are referenced from external water seal, while those that do not indicate water seal connection are used as water seal connection using the effluent from the first stage impeller. The tightness of the packing of the shaft seal must be appropriate, when the liquid can leak out drop by drop. When the temperature of the medium being transported is higher than 80 ℃, it is necessary to fill the water-cooled packing cover and shaft seal cooling chamber with coolant. The cooling water and the external water seal water are both room temperature clean water, with a cooling water pressure of 1.5-3 kg/cm and a water seal water pressure 0.5-1 kg/cm higher than the sealing chamber. The water seal and shaft seal cooling chamber of each type of pump have different positions for the water pipeline interface. The position of the pipeline interface along the axial direction is shown in the pump structure diagram.
3. Balance mechanism
The balance mechanism consists of a balance ring, a balance sleeve, a balance plate, and a balance pipeline.
4. Bearing section
The bearing part is mainly composed of a bearing body and bearings. This type of pump has two types of bearings: sliding bearings and circulating bearings. The bearings do not bear axial force. During the operation of the pump, the rotor part should be able to freely move axially in the pump housing, and radial ball bearings cannot be used. The bearings used in various types of pumps are shown in Table 1.
5. Sealing and cooling of pumps
The joint surfaces of the suction section, middle section, discharge section, and guide vanes in the shell are sealed with molybdenum disulfide grease.
The rotor and fixed parts are sealed with sealing rings, guide vanes, packing, etc. When the wear of the sealing ring and guide vane sleeve has affected the operation and performance of the pump, they should be replaced in a timely manner. When using this model, the position of the packing ring should be placed correctly. The distribution of packing and packing rings for each type of pump is shown in Table 2.

Figure 1 D-type pump structure diagram

1. Pump coupling 2, shaft 3, rolling bearing components 4, packing gland 5, suction section 6, sealing ring

7. Middle section 8, impeller 9, guide vane 10, guide vane sleeve 11, tightening bolt 12, discharge section

13. Balance sleeve (ring) 14, balance disk 15, packing box 16, bearing

Figure 2 DG pump structure diagram

1. Bearing body 2, suction section 3, balance pipe 4, guide vane sleeve 5, impeller 6, guide vane 7, sealing ring

8. Mid section 9, Discharge section 10, Balance disk 11, Tail cover 12, Packing 13, O-ring 14, Bearing components

15. Water cooled packing cover

Assembly and disassembly of pumps

1. Pump assembly

The quality of the assembly of this type of pump directly affects whether the pump can work normally, the service life and performance of the pump, and the vibration and noise of the unit. The following points should be noted during assembly.

a. The concentricity of the assembled parts of the fixed part is ensured by the manufacturing accuracy and assembly quality of the parts. The machining accuracy and surface roughness of the parts should be protected, and no collisions or scratches are allowed. The disulfide keys used as sealants should be clean, and the screws and bolts used for fastening should be evenly stressed.

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

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

Set. d. After passing the above inspection, press the packing into the packing chambers at both ends of the pump, paying attention to the relative position of the packing rings in the packing chambers

Disassemble both pumps

Injury. a. The disassembly of the pump should be carried out in the reverse order of assembly, and the manufacturing accuracy of each part on the pump should be strictly protected during disassembly from being damaged

b. At the same time as disassembling the through rod, each middle section should be cushioned to prevent the loosening and sinking of the middle section stopper from bending the shaft.

Pump installation

In addition to general installation requirements, the following two points should be noted when installing this type of pump:

1. There should be a certain gap between the motor and the pump coupling, which should be close to the displacement of the pump shaft, generally 3-5mm.

2. The axis lines of the motor and pump must be in the same plane as a straight line. The uniformity of the clearance between the end faces of the two couplings can be measured with a feeler gauge. The maximum and minimum clearance differences in all directions around the circumference should not exceed 0.2 millimeters, and the difference between the center lines of the two end faces should not exceed 0.1 millimeters.

Starting, running, and stopping of the pump

Start: Before starting the pump, the rotor should be turned to check if it is flexible.

2. Check if the motor direction is consistent with the pump direction.

3. Close the outlet gate valve. Pressure gauge plug, used to remove air from the suction pipe and pump through the conveyed liquid or vacuum system.

4. Check the tightness of the bolts connecting the pump and motor, as well as the safety situation around the pump, to prepare the pump for starting.

5. Start the pump and wait for it to operate normally. Open the pressure gauge plug and slowly open the pump outlet valve. Control the given head of the pump according to the reading on the outlet pressure gauge.

Operation: 1. This type of pump relies on the balance structure inside the pump to balance the axial force, and there is balance liquid flowing out from the balance device. The balancing fluid is connected to the suction section through a balancing water pipe. To ensure the normal operation of the pump, the balance water pipe must not be blocked.

2. The rolling bearings of this type of pump do not have cooling devices, and the temperature rise of the bearings 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 ℃.

3. There is a certain axial movement of the rotor of this pump during operation, and the clearance value between the end faces of the motor and pump couplings should be ensured.

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

5. Develop detailed operating procedures for pumps based on specific situations during use.

Parking: Before parking, the pressure gauge plug should be closed first, and the outlet gate valve should be slowly closed. After the outlet gate valve is closed, the motor should be stopped.

 Possible pump malfunctions and their solutions

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