How to select a suitable vertical long shaft multi-stage cylindrical bag turbine pump for application in the power industry?

When selecting a vertical long shaft multi-stage drum bag turbine pump in the power industry, it is necessary to consider the core scenario requirements such as condensate water transportation and boiler feedwater, and comprehensively select from five dimensions: flow head, cavitation performance, material temperature and pressure resistance, structural reliability, and energy efficiency standards. The specific details are as follows:
1、 Clarify the core application scenarios and requirements
Typical scenarios for the application of vertical long shaft multi-stage cylindrical bag turbine pumps in the power industry include:
Condensed water transportation: The condenser of thermal power plants/nuclear power plants pumps condensed water, which needs to be treated with low-temperature and low cavitation allowance media.
Boiler feedwater: Supercritical units require high-pressure pumps to transport desalinated water, which requires high temperature and pressure resistance.
Circulating water system: The circulating water of the cooling tower needs to be treated for media containing impurities.
Key requirements:
Flow head: The flow range is determined based on the size of the unit (such as 50-800m ³/h), and the head needs to cover the system resistance (such as 48-360m).
Cavitation performance: The condensate pump needs to be designed with low NPSH (required cavitation allowance) to avoid cavitation damage.
Temperature and pressure resistance: Boiler feedwater pumps need to withstand high temperatures (such as 180 ℃) and high pressures (such as 10MPa).
Material reliability: The overcurrent components should be made of corrosion-resistant materials (such as duplex steel and super duplex steel).
Energy efficiency standards: comply with international standards such as API 610 and ASME to ensure efficient and stable operation.
2、 Core parameters and standards for selection
Flow and head matching:
Calculate the required head based on system resistance and reserve a margin of 10% -15%.
Example: The flow rate of the condensate pump for a 1000MW unit is about 800m ³/h, and the head needs to be ≥ 360m.
NPSH calculation:
Ensure that the effective cavitation head (NPSHa) is greater than the required cavitation head (NPSHr)+safety margin (0.5-1m).
The vertical drum bag pump is designed with a first stage impeller sinking (such as sinking 3 meters below the ground) to increase NPSHa and avoid cavitation.
Material selection:
Condensed water pump: The overcurrent components are made of duplex steel (such as 2205) or super duplex steel (such as 2507), which are resistant to seawater corrosion.
Boiler feedwater pump: heat-resistant steel (such as 9Cr18Mo) is used in the high-temperature section to ensure long-term stability.
Structural reliability:
Multi stage design: High head is achieved through step-by-step pressurization, with a single stage head typically ranging from 30-60m.
Axial force balance: Use a balance drum or centripetal thrust ball bearing to balance axial force and reduce vibration.
Bearing lubrication: Equipped with an independent lubrication system to ensure the stability of the long shaft support.
Energy Efficiency and Standards:
Priority should be given to pump types that comply with API 610 12th edition standards, with efficiency typically 2% -5% higher than regular pumps.
Motor matching with high-efficiency motors (such as IE3/IE4) to reduce operating energy consumption.
3、 Typical product selection reference
LDTN type vertical long shaft multi-stage cylindrical bag turbine pump:
Application: Condensed water transportation for 50-1000MW thermal power units.
Parameters: Flow rate 85-870m ³/h, head 48-360m, temperature ≤ 80 ℃ (special requirements can reach 120 ℃).
Advantages: The first stage impeller sinking design has excellent cavitation performance; Dual suction structure is optional to further reduce NPSHr.
VS6 vertical long shaft multi-stage drum bag turbine pump:
Application: High temperature and high pressure working conditions in the power, coal chemical, and petrochemical industries.
Parameters: flow rate of 5-800m ³/h, head of 5-800m, pressure of 10MPa, temperature of -180~+180 ℃.
Advantages: Compliant with API 610 standard, axial force is borne by centripetal thrust ball bearings, equipped with an oil separator, high reliability.
4、 Selection precautions
System calculation accuracy:
Accurately calculate system resistance to avoid deviation in head estimation, which may lead to excessive or insufficient selection of vertical long shaft multi-stage drum bag turbine pumps.
Consider future expansion needs and reserve a flow head margin.
Installation and maintenance:
The vertical long shaft multi-stage drum bag turbine pump needs to be installed underground and sufficient maintenance space needs to be reserved.
Configure an intelligent monitoring system to monitor bearing temperature and vibration data in real-time to prevent malfunctions.