Parameter Matching Strategy and Practice of High Temperature Hot Oil Pump Power

As a special equipment for transporting high-temperature media, the power system parameters of high-temperature oil pumps directly affect their operational stability, energy efficiency level, and equipment lifespan. Under high temperature conditions, changes in medium viscosity, thermal expansion effects, and sealing requirements pose special challenges to the power system, requiring systematic matching from motor selection, transmission to control strategy.

1、 Principle of motor parameter matching

1. Power redundancy

The power of the high-temperature oil pump motor needs to balance the starting torque and operating margin. Due to the decrease in viscosity of high-temperature media with increasing temperature, the shaft power of the pump may decrease in the high-temperature range, but it is necessary to overcome the viscous resistance of the media at low temperatures during the start-up phase. When considering the temperature fluctuation range of the medium, the power value that can cover low viscosity working conditions should be selected. Due to the lack of reserved starting power margin, a certain petrochemical enterprise frequently overloaded and tripped the motor during low-temperature starting in winter. Later, the problem was solved by adding a frequency converter to achieve soft starting.

2. Speed adaptability matching

The motor speed needs to be coordinated with the pump body speed. Under high temperature conditions, thermal expansion of the pump body material may cause changes in the clearance between the impeller and the volute, and excessive speed can exacerbate clearance leakage. For pumps transporting heavy oil products, it is advisable to use medium low speed motors to reduce shear stress and prevent medium emulsification. After a certain refinery converted the original pump to low-speed high torque, the inlet and outlet temperatures of the medium decreased and heat loss decreased.

3. Protection level

Motor protection needs to meet the requirements of high temperature environment. The protection level of the shell should meet the standard of dust and water resistance to prevent hot oil splashing and entering; The insulation level should be made of high-temperature materials, which can maintain insulation performance even under the combination of ambient temperature and motor heating. Due to insufficient insulation level, the motor of a certain thermal power plant frequently experiences inter turn short circuits during high temperature periods in summer. After replacing it with a motor that is not afraid of higher temperature levels, it runs stably.

2、 Key points for matching the transmission system

1. Coupling stiffness balance

Couplings need to balance torque transmission and buffering performance. Rigid couplings are suitable for precise alignment scenarios, but the difference in thermal expansion between the pump shaft and motor shaft under high temperature conditions may lead to rigid connection failure; Elastic couplings can compensate for axial displacement, but torsional stiffness needs to be controlled to avoid transmission lag. After adopting membrane couplings in a certain chemical plant, the problem of thermal expansion was solved and vibration transmission was reduced.

2. Transmission ratio optimization

The variable speed transmission device needs to match the characteristic curve of the pump. For hot oil pumps operating under variable conditions, it is advisable to configure a frequency converter to achieve stepless speed regulation, so that the pump can operate in a good speed range; In the fixed speed scenario, the transmission ratio needs to be adjusted through a gearbox to ensure that the rated speed and value of the pump are consistent. A heating enterprise has implemented frequency conversion transformation, which enables the hot oil pump to automatically slow down at low loads, resulting in a significant increase in annual energy savings.

3. Thermal compensation

The transmission components need to reserve thermal expansion space. When driving with a long shaft, an expansion joint should be installed at the middle support; The belt drive needs to adjust the tension to prevent the belt from loosening and slipping under high temperature. A certain paper mill's hot oil pump experienced increased shaft seal leakage due to neglecting the thermal expansion of the transmission shaft. After adding an expansion joint, the problem was resolved.

3、 Collaborative strategy of control system

1. Temperature speed linkage control

Establish closed-loop control of medium temperature and pump speed. When the inlet and outlet temperatures deviate from the set value, the control system automatically adjusts the speed to maintain thermal balance and avoid sudden changes in medium viscosity caused by temperature fluctuations. After adopting this strategy, a certain fine chemical enterprise improved the stability of the hot oil pump operation and increased the product qualification rate.

2. Torque protection mechanism

Set up motor torque monitoring and limiting function. When the pump body experiences a sudden increase in load due to medium solidification or impurity blockage, the control system should be able to quickly reduce the speed or shut down to prevent motor burnout. A certain new energy enterprise successfully avoided multiple motor overload accidents by installing torque sensors.

3. Optimization of startup sequence

The established equipment startup process. The high-temperature hot oil pump system should follow the "; Preheat before starting; Principle: By circulating thermal oil, the pump body is uniformly heated to reduce thermal stress; Before starting the motor, it is necessary to confirm that the lubricating oil pressure is normal to prevent dry friction. A metallurgical enterprise failed to perform preheating procedures, resulting in thermal deformation of the pump body. After maintenance, a new start-up procedure was formulated, and similar failures did not occur again.

4、 Key points for implementing systematic matching

Multi condition simulation analysis: In the stage, fluid simulation software is used to simulate the pump performance under different temperatures and flow rates, providing theoretical basis for parameter matching.

Modular application: The power system is divided into modules such as motors, transmissions, and controls, making it easy to flexibly adjust configurations according to changes in operating conditions.

Whole life cycle management: Establish a power system parameter file, record operating data and maintenance records, and provide reference for subsequent modifications.

The parameter matching of high-temperature hot oil pump power system needs to break through conservative thinking and integrate thermodynamic characteristics with mechanical performance. Through the coordinated optimization of the motor, transmission, and control system, it is possible to achieve good and stable operation at high temperatures, creating significant economic benefits and stable value for the enterprise.