Condensate pumps that ensure safe operation of the unit during deep peak shaving

Abstract

This utility model relates to the field of condensate pump technology, specifically a condensate pump for ensuring the safe operation of a unit during deep peak shaving. It includes a primary impeller and secondary impellers. The primary impeller is rotatably mounted inside a primary spiral casing, and the secondary impeller is rotatably mounted inside a guide shell. Multiple secondary impellers are provided, and the primary impeller and multiple secondary impellers are all sleeved and mounted on the outer side of the lower shaft. One end of the primary spiral casing is fixedly connected to one end of the guide shell. This pump, by employing a primary double-suction impeller, optimized blade inlet, and an ultra-low specific speed hydraulic model, significantly reduces the required net positive suction head (NPSH), effectively solving the cavitation problem under low-speed conditions during deep peak shaving. Simultaneously, its key flow components use high-strength, cavitation-resistant materials, and through rigid structure optimization and rotor dynamics design, the critical speed is completely avoided from the low-load operating range, thereby completely avoiding resonance risks and ensuring the long-term safe and stable operation of the unit under ultra-low load conditions.

Description

Technical Field

[0001] This utility model relates to the field of condensate pump technology, specifically to a condensate pump that ensures the safe operation of a unit during deep peak shaving. Background Technology

[0002] With economic development and social progress, energy conservation has become an inevitability and a social consensus. Various equipment are increasingly developing towards features such as energy saving, ease of use, space saving, safety, and high efficiency.

[0003] The demand for deep peak shaving of condensate pumps: With deep peak shaving (low load to 20% or even lower) of thermal power units becoming the norm, the severe challenges it poses to auxiliary equipment (especially condensate pumps) are highlighted.

[0004] For conventional thermal power units, condensate pumps use a 4-pole motor with a rated speed of 1480 r / min. When the unit is operating at or near full load, the rated speed of the condensate pump is close to 1480 r / min, allowing for stable operation. For a slender shaft pump like this 1480 r / min condensate pump, analysis and calculations show that the first-order resonant speed is around 900 r / min. However, with the changing landscape of thermal power units in recent years, power plants are requiring deep frequency conversion operation of feedwater pumps. At low loads, the speed of some condensate pumps reaches 700, 800 r / min, or even lower. This forces the condensate pump to operate at speeds exceeding the first-order limit, leading to resonance and severely impacting the safe and stable operation of the unit. Therefore, a condensate pump designed to ensure safe operation during deep peak shaving of the unit is proposed. Utility Model Content

[0005] The main purpose of this utility model is to provide a condensate pump that ensures the safe operation of the unit during deep peak shaving, which can effectively solve the problems in the background art.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows: The condensate pump that ensures the safe operation of the unit during deep peak shaving includes a primary impeller and a secondary impeller. The primary impeller is rotatably installed inside the primary spiral casing, and the secondary impeller is rotatably installed inside the guide casing. The secondary impeller has multiple locations. The primary impeller and the multiple locations of the secondary impeller are all sleeved and installed on the outside of the lower shaft. One end of the primary spiral casing is fixedly connected to one end of the guide casing.

[0007] Specifically, one end of the lower shaft is fixedly connected to one end of the upper shaft, and the end of the guide shell away from the first-stage spiral shell is fixedly connected to one end of the intermediate pipe.

[0008] Specifically, the end of the intermediate connecting pipe away from the guide shell is fixedly connected to the end of the dispensing seat, and a water outlet pipe is provided on the outside of the dispensing seat.

[0009] Specifically, the end of the ejector seat away from the intermediate pipe is fixedly connected to one end of the bearing bracket, and the bearing bracket is provided with a balancing mechanism inside, which is sleeved on the outside of the upper shaft.

[0010] Specifically, the end of the bearing bracket away from the ejector seat is fixedly connected to one end of the motor bracket, and the motor bracket is equipped with a thrust bearing device inside, which is sleeved on the outside of the upper shaft.

[0011] Specifically, the upper shaft is located inside the intermediate connecting pipe, the ejector seat, the bearing bracket, and the motor bracket.

[0012] The beneficial effects of this utility model are: The condensate pump described in this utility model, which ensures the safe operation of the unit during deep peak shaving, significantly reduces the required net positive suction head (NPSH) by adopting a first-stage double-suction impeller, optimizing the blade inlet, and using an ultra-low specific speed hydraulic model. This effectively solves the cavitation problem under low-speed conditions during deep peak shaving. At the same time, its key flow components are made of high-strength cavitation-resistant materials, and through rigid structure optimization and rotor dynamics design, the critical speed is completely avoided from the low-load operating range, thereby completely avoiding the risk of resonance and ensuring the long-term safe and stable operation of the unit under ultra-low load conditions. Attached Figure Description

[0013] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0014] Figure 1 This is a schematic diagram of the planar structure of the present invention; Figure 2 For the present utility model Figure 1 Enlarged structural diagram at point A in the middle; In the diagram: 1. First-stage impeller; 2. First-stage spiral casing; 3. Lower shaft; 4. Second-stage impeller; 5. Guide casing; 6. Upper shaft; 7. Intermediate connecting pipe; 8. Discharge seat; 9. Balancing mechanism; 10. Bearing bracket; 11. Thrust bearing device; 12. Motor bracket; 13. Water outlet pipe. Detailed Implementation

[0015] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the present utility model will be further described below in conjunction with specific embodiments.

[0016] As one embodiment of this utility model, such as Figures 1-2As shown, the condensate pump for ensuring the safe operation of the unit during deep peak shaving according to this utility model includes a primary impeller 1 and a secondary impeller 4. The primary impeller 1 is rotatably installed inside the primary spiral shell 2, and the secondary impeller 4 is rotatably installed inside the guide shell 5. The secondary impeller 4 has multiple locations. The primary impeller 1 and the multiple locations of the secondary impeller 4 are all sleeved and installed on the outside of the lower shaft 3. One end of the primary spiral shell 2 is fixedly connected to one end of the guide shell 5.

[0017] During operation, condensate first enters the primary spiral casing 2, where it is powered by the primary impeller 1. This primary impeller 1 employs a double-suction structure and optimized hydraulic design, specifically designed for efficient medium intake and significantly reduced required net positive suction head (NPSH) under low speed and low flow conditions, thereby effectively preventing cavitation during deep peak shaving. The pressurized liquid is then guided into the guide casing 5, which is fixedly connected to it, and the pressure is progressively increased by multiple secondary impellers 4 connected in series. These impellers are all mounted on the lower shaft 3 and driven by the same power source, ensuring continuous and stable power transmission between stages.

[0018] This utility model also includes that one end of the lower shaft 3 is fixedly connected to one end of the upper shaft 6, and the end of the guide shell 5 away from the first-stage spiral shell 2 is fixedly connected to one end of the intermediate pipe 7.

[0019] In use, the lower shaft 3 transmits the torque from the first-stage impeller 1 and the secondary impeller 4 to the upper shaft 6, which is fixedly connected to it, forming a complete rotor system. This system is driven by a variable frequency motor and can operate safely in the low-speed range, accurately avoiding the first-order critical speed of the pump. At the same time, the guide shell 5, which collects the liquid after multi-stage pressurization, smoothly delivers the water flow to the fixedly connected intermediate pipe 7. This pipe, as part of the flow channel, is responsible for guiding the water flow to the pump's outlet area.

[0020] The present invention also includes that the end of the intermediate pipe 7 away from the flow guide shell 5 is fixedly connected to one end of the discharge seat 8, and the discharge seat 8 is provided with a water outlet pipe 13 on the outside.

[0021] During use, the high-pressure condensate from the intermediate pipe 7 eventually enters the chamber of the discharge seat 8. The discharge seat 8 serves as the outlet pressure collection chamber of the pump, and its structure is rigidly reinforced to withstand internal pressure and suppress vibration. Finally, the pressurized water is discharged through the outlet pipe 13, which is fixedly connected to the outside of the discharge seat 8.

[0022] The present invention also includes that the end of the ejector seat 8 away from the intermediate tube 7 is fixedly connected to one end of the bearing bracket 10, and the bearing bracket 10 is provided with a balancing mechanism 9 inside, and the balancing mechanism 9 is sleeved on the outside of the upper shaft 6.

[0023] During use, the ejector seat 8 provides a stable support base for the bearing bracket 10; the balancing mechanism 9 installed inside the bearing bracket 10 dynamically balances most of the axial force generated by the rotor during pump operation by being sleeved on the upper shaft 6, which greatly reduces the load on the end thrust bearing. This is the key to ensuring stable operation of the pump under varying operating conditions and extending the bearing life.

[0024] The present invention also includes that one end of the bearing bracket 10 away from the ejector seat 8 is fixedly connected to one end of the motor bracket 12, and the motor bracket 12 is provided with a thrust bearing device 11 inside, and the thrust bearing device 11 is sleeved on the outside of the upper shaft 6.

[0025] During use, the bearing bracket 10 is fixedly connected to the motor bracket 12, forming a rigid support frame for the pump. The thrust bearing device 11 installed inside the motor bracket 12 is sleeved on the end of the upper shaft 6 to bear the remaining axial force after being balanced by the balancing mechanism 9 and the weight of the rotor, ensuring accurate axial positioning of the rotor. The entire support system is robustly designed and can effectively control shaft deflection and reduce vibration.

[0026] This utility model also includes that the upper shaft 6 is disposed inside the intermediate pipe 7, the ejector seat 8, the bearing bracket 10, and the motor bracket 12.

[0027] During use, the upper shaft 6, as the main transmission component of the entire rotor system, runs through the center of the intermediate pipe 7, discharge seat 8, bearing bracket 10, and motor bracket 12. Its rotational power is transmitted to all impellers by the motor. This through-type design ensures the concentricity of power transmission, while the entire flow channel and support components together provide a continuous and stable support environment for the long shaft, effectively improving the rotor dynamics performance and ensuring that the pump can avoid the critical speed even in the low-speed operating range, achieving smooth and resonance-free operation.

[0028] In use, when the pump is working, condensate enters the first-stage spiral casing 2 through the inlet, and is drawn in and pressurized by the rotating first-stage impeller 1. The first-stage impeller 1 adopts a double-suction structure design to reduce the net positive suction head (NPSH), and improves the inflow conditions by optimizing the blade inlet shape, such as increasing the inlet angle of attack and special leading edge shaping. The pressurized water flows through the guide shell 5 and is guided to multiple secondary impellers 4. The secondary impellers 4 also adopt a hydraulic model design with a wide high-efficiency range, such as ultra-low specific speed, twisted blades, or long and short blades, to maintain high efficiency and high cavitation resistance at low flow rates. All impellers are sleeved and installed on the outside of the lower shaft 3, which is fixedly connected to the upper shaft 6 and driven to rotate by a motor. The speed can be reduced to a safe range by frequency conversion. Key flow components such as the first-stage impeller 1 and the secondary impellers 4 are made of cavitation-resistant and fatigue-resistant reinforced materials, such as ZG1Cr13Ni or RWA350 stainless steel, to resist cavitation damage and wear at low flow rates. The water flow eventually enters the intermediate pipe 7 through the guide shell 5, then reaches the discharge seat 8 and is discharged from the outlet pipe 13. The axial force of the pump is balanced by the balancing mechanism 9 mounted on the outside of the upper shaft 6. The thrust bearing device 11 is installed inside the motor bracket 12 to bear the remaining axial force. If an angular contact ball bearing is used, the radial support relies on the AC-3 water-lubricated guide bearing inside the bearing bracket 10. The sealing system adopts a double-end face cartridge mechanical seal to optimize leakage control. At the same time, the structural rigidity is improved by strengthening the design of the pump body, bearing bracket 10, discharge seat 8, motor bracket 12, etc., and the rotor dynamics are optimized to keep the critical speed away from the operating range and reduce vibration. The intelligent monitoring system tracks parameters such as flow rate, pressure, and temperature and bearing temperature in real time. The data is transmitted to the power plant's DCS / SIS system to realize active reliability management and ensure the safe and efficient operation of the pump under deep peak shaving conditions.

[0029] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The descriptions of the above embodiments and specifications are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by this utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A condensate pump for ensuring safe operation of a generating unit during deep peak shaving, comprising a primary impeller (1) and a secondary impeller (4), characterized in that, The first-stage impeller (1) is rotatably installed inside the first-stage spiral shell (2), and the second-stage impeller (4) is rotatably installed inside the guide shell (5). The second-stage impeller (4) is provided in multiple locations. The first-stage impeller (1) and the multiple locations of the second-stage impeller (4) are all sleeved and installed on the outside of the lower shaft (3). One end of the first-stage spiral shell (2) is fixedly connected to one end of the guide shell (5).

2. The condensate pump for ensuring safe operation of the unit during deep peak shaving as described in claim 1, characterized in that, One end of the lower shaft (3) is fixedly connected to one end of the upper shaft (6), and the end of the guide shell (5) away from the first-stage spiral shell (2) is fixedly connected to one end of the intermediate pipe (7).

3. The condensate pump for ensuring safe operation of the unit during deep peak shaving as described in claim 2, characterized in that, The end of the intermediate connecting pipe (7) away from the flow guide shell (5) is fixedly connected to one end of the discharge seat (8), and the outside of the discharge seat (8) is provided with a water outlet pipe (13).

4. The condensate pump for ensuring safe operation of the unit during deep peak shaving as described in claim 3, characterized in that, The end of the ejector seat (8) away from the intermediate pipe (7) is fixedly connected to one end of the bearing bracket (10). The bearing bracket (10) is provided with a balancing mechanism (9) inside, and the balancing mechanism (9) is sleeved on the outside of the upper shaft (6).

5. The condensate pump for ensuring safe operation of the unit during deep peak shaving as described in claim 4, characterized in that, The bearing bracket (10) is fixedly connected to one end of the motor bracket (12) at the end away from the ejector seat (8). The motor bracket (12) is provided with a thrust bearing device (11) inside, which is sleeved on the outside of the upper shaft (6).

6. The condensate pump for ensuring safe operation of the unit during deep peak shaving as described in claim 2, characterized in that, The upper shaft (6) is located inside the intermediate pipe (7), the ejector seat (8), the bearing bracket (10), and the motor bracket (12).

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