Low temperature expander gas-liquid two-phase impeller

Abstract

The application solves the problem that the existing impeller is difficult to meet the requirement of long-term stable operation, and provides a low-temperature expander gas-liquid two-phase impeller, which comprises an impeller seat arranged in an expansion chamber of an expander, the impeller seat is fixedly connected with a main shaft of the expander, a plurality of blades are uniformly distributed on the circumference of the impeller seat, the impeller seat is provided with a plurality of guide holes, the inlet of the guide hole is arranged in a liquid forming area of the impeller and is connected with a high-pressure side and a low-pressure side of the expansion chamber, a temperature sensor is arranged in the liquid forming area of the impeller, and the surface of the impeller body is coated with a low-temperature wear-resistant coating. The low-temperature wear-resistant coating capable of resisting liquid wear is arranged, and the service life of the impeller is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cryogenic expanders, in particular to a cryogenic expander gas-liquid two-phase impeller. BACKGROUND

[0002] Cryogenic expanders are indispensable key equipment in modern industry, widely used in liquefied natural gas (LNG) and air separation fields. In the field of liquefied natural gas, cryogenic expanders use their high refrigeration capacity to liquefy and store natural gas, while providing power in the regasification process of LNG. In the field of air separation, cryogenic expanders liquefy air through deep freezing method, and then separate each component according to the difference in boiling point to produce high-purity oxygen, nitrogen and argon.

[0003] However, during the operation of the cryogenic expander, especially when dealing with gas-liquid two-phase working conditions, it faces many technical challenges. First, under gas-liquid two-phase working conditions, the impeller surface will be subjected to strong liquid impact, causing accelerated wear of the impeller surface and reducing the service life of the impeller. Second, the impeller works in a low-temperature environment, with uneven temperature distribution, which can cause icing or local overheating, affecting the performance and reliability of the impeller. In addition, the surface treatment technology of the existing impeller lacks wear resistance and corrosion resistance in low-temperature environments, making it difficult to meet the requirements of long-term stable operation. In summary, the structure and surface treatment method of the cryogenic expander impeller in the prior art have many shortcomings under gas-liquid two-phase working conditions, and need to be improved and optimized. SUMMARY

[0004] The present application solves the problem that the existing impeller cannot meet the requirements of long-term stable operation, and proposes a cryogenic expander gas-liquid two-phase impeller, which is provided with a low-temperature wear-resistant coating that can resist liquid wear, thereby prolonging the service life of the impeller.

[0005] To achieve the above-mentioned purpose, the following technical solutions are proposed:

[0006] A cryogenic expander gas-liquid two-phase impeller, comprising an impeller seat provided in an expansion chamber of the expander, the impeller seat being fixedly connected with a main shaft of the expander, a plurality of blades being circumferentially distributed on the impeller seat, the impeller seat being provided with a plurality of guide holes, the inlets of the guide holes being provided in a liquid formation area of the impeller and being connected with a high-pressure side and a low-pressure side of the expansion chamber, a temperature sensor being provided in the expansion chamber in the liquid formation area of the impeller, and a low-temperature wear-resistant coating being coated on the surface of the impeller body.

[0007] The flow guide hole of the application is arranged in the liquid forming area of the impeller body, the temperature sensor is embedded in the liquid forming area of the impeller body, and the low-temperature wear-resistant coating is coated on the surface of the impeller body, so that the effects of effectively guiding liquid flow, real-time monitoring of temperature and improving the wear resistance of the impeller are achieved. This is because the flow guide hole can guide the discharge of liquid droplets, avoid the accumulation of liquid film and reduce flow loss; the temperature sensor can obtain real-time temperature data of the liquid forming area so as to timely adjust the working state; the low-temperature wear-resistant coating can resist liquid wear and prolong the service life of the impeller. By connecting the high-pressure side and the low-pressure side of the impeller, the back pressure of the impeller is reduced, and the axial load of the bearing and the mechanical density is reduced.

[0008] As preferred, the main body of the impeller seat is cylindrical, the installation hole is coaxially arranged inside the impeller seat, the counterbore is arranged on the side of the wheel disc of the impeller close to the installation hole, the main shaft installation taper hole is arranged on the side of the wheel back of the impeller close to the installation hole, the taper is arranged on the end of the main shaft fixed to the impeller seat, the taper is matched with the main shaft installation taper hole, the screw hole is arranged in the taper, one end of the stud bolt is sequentially threaded through the counterbore, the installation hole and the screw hole, the other end of the stud bolt is threaded connected with the installation nut, and the installation nut is embedded into the counterbore.

[0009] As preferred, the installation hole and the main shaft installation taper hole are connected with the relief hole, and the diameter of the relief hole is greater than the diameter of the installation hole and the minimum diameter of the main shaft installation taper hole.

[0010] As preferred, the flow guide hole is arranged through the impeller seat along the radial direction of the impeller body, and the opening end of the flow guide hole faces the wheel disc side.

[0011] The flow guide holes of the application are independent of each other and uniformly distributed, and jointly guide the discharge of liquid droplets to the wheel disc side, reduce the liquid film on the surface of the blade, reduce the flow loss, and improve the efficiency of the impeller.

[0012] As preferred, the flow guide holes are circumferentially distributed on the impeller seat, and the distance between adjacent flow guide holes is less than twice the diameter of the flow guide hole.

[0013] In the embodiment, the impeller body is made of titanium alloy material, the diameter of the impeller is 240 mm, the flow guide hole is designed according to the position of the liquid forming area of the impeller, the diameter of the flow guide hole is 3-6 mm, the opening diameter is 5 mm, the number is 12, and the flow guide holes are distributed in the liquid forming area of the impeller.

[0014] As preferred, the impeller body is made of titanium alloy material, the low-temperature wear-resistant coating is formed by plasma electrolytic oxidation process, and the low-temperature wear-resistant coating includes TiO2, γ-Al2O3, Al2TiO5 phase and amorphous SiO2.

[0015] As preferred, the average thickness of the low-temperature wear-resistant coating is 1 mm, and the bonding force between the low-temperature wear-resistant coating and the impeller body is greater than 48 N.

[0016] The average bonding force between the oxide film and the substrate in the embodiment is 48.5 N or more, the film / substrate is well bonded, and the low-temperature wear-resistant coating in the embodiment can meet the design requirements with an average thickness of 1 mm. The film layer has good high-temperature stability and wear resistance, and can be well bonded with the substrate without cracking or falling off during low-temperature high-speed rotation.

[0017] Preferably, the microhardness of the low-temperature wear-resistant coating is 4 times or more than that of the impeller body, the microhardness of the oxide film is 800-1200 HV, and the surface roughness value of the low-temperature wear-resistant coating is between Ra3.2 and Ra1.6, which can meet the technical requirements and can be polished if special requirements are needed. The film layer coated on the surface of the impeller body can effectively resist the wear of the liquid on the surface of the impeller under low-temperature gas-liquid two-phase working conditions, and prolong the service life of the impeller.

[0018] Preferably, the temperature sensor is an embedded micro thin film temperature sensor, which can monitor the local temperature in real time.

[0019] The micro thin film temperature sensor, such as Pt100, is embedded in the impeller liquid forming area to monitor the local temperature in real time, and the temperature threshold alarm is combined, such as triggering protection when the temperature is lower than-150℃.

[0020] Preferably, the cross-sectional shape of the flow guide hole is conical, and the large end of the flow guide hole faces the back of the impeller.

[0021] The design of the flow guide hole of the present application is beneficial to the better discharge of liquid droplets, and alternatively, the cross-sectional shape of the flow guide hole can also be circular, elliptical, etc.

[0022] The present application has the following advantages:

[0023] 1. By designing the opening in the impeller liquid forming area, the liquid flow is effectively guided, the impact of the liquid on the surface of the impeller is reduced, the gas-liquid distribution inside the impeller is improved, and the efficiency of the impeller is improved.

[0024] 2. The temperature of the impeller liquid forming area is monitored in real time, the working state of the impeller is adjusted in time, the failure of the impeller due to temperature problems is prevented, and the reliability and service life of the impeller are improved.

[0025] 3. The low-temperature surface wear-resistant coating process is adopted, the prepared coating has good wear resistance and bonding strength with the substrate, can effectively resist the wear of the liquid on the surface of the impeller under low-temperature gas-liquid two-phase working conditions, and prolong the service life of the impeller. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The present application is a sectional view of the impeller structure.

[0027] Figure 2 A front view of the impeller of the present application.

[0028] Wherein: 1, impeller seat; 2, blade; 3, flow guide hole; 4, main shaft; 5, mounting hole; 6, counterbore; 7, main shaft mounting taper hole; 8, mounting nut; 9, stud bolt. DETAILED DESCRIPTION EMBODIMENT

[0029] The embodiment provides a low-temperature expander gas-liquid two-phase impeller, referring to Figure 1 and Figure 2 , comprising an impeller seat 1 arranged in an expansion chamber of an expander, the impeller seat 1 is fixedly connected with a main shaft 4 of the expander, a plurality of blades 2 are uniformly distributed on the impeller seat 1 in a circumferential direction, the impeller seat 1 is provided with a plurality of flow guide holes 3, the inlet of the flow guide hole 3 is arranged in a liquid formation area of the impeller and is connected with a high-pressure side and a low-pressure side of the expansion chamber, a temperature sensor is arranged in the liquid formation area of the impeller, and the surface of the impeller body is coated with a low-temperature wear-resistant coating.

[0030] The flow guide hole of the present application is arranged in the liquid formation area of the impeller body, the temperature sensor is embedded in the liquid formation area of the impeller body, and the low-temperature wear-resistant coating is coated on the surface of the impeller body, so that the effects of effectively guiding liquid flow, real-time monitoring of temperature and improving the wear resistance of the impeller are achieved. This is because the flow guide hole can guide the discharge of liquid droplets, avoid the accumulation of liquid film, and reduce flow loss; the temperature sensor can obtain temperature data of the liquid formation area in real time, so as to timely adjust the working state; the low-temperature wear-resistant coating can resist liquid wear and prolong the service life of the impeller. By connecting the high-pressure side and the low-pressure side of the impeller, the back pressure of the impeller is reduced, and the axial load of the bearing and the mechanical density is reduced.

[0031] The main body of the impeller seat 1 is in a cylindrical shape, the mounting hole 5 is coaxially arranged in the impeller seat 1, the counterbore 6 is arranged on the side of the impeller disc of the mounting hole 5, the main shaft mounting taper hole 7 is arranged on the side of the back of the impeller of the mounting hole 5, the taper table is arranged on the fixed end of the main shaft 4 and the impeller seat 1, the taper table is matched with the main shaft mounting taper hole 7, the taper table is provided with a threaded hole, one end of the stud bolt 9 is sequentially threaded through the counterbore 6 and the mounting hole 5 and is screwed with the threaded hole, the other end of the stud bolt 9 is screwed with the mounting nut 8, and the mounting nut 8 is embedded in the counterbore 6. The connecting part of the mounting hole 5 and the main shaft mounting taper hole 7 is provided with a clearance hole, the diameter of the clearance hole is greater than the diameter of the mounting hole 5 and the minimum diameter of the main shaft mounting taper hole 7. The impeller body is made of titanium alloy material, the low-temperature wear-resistant coating is formed by a plasma electrolytic oxidation process, and the low-temperature wear-resistant coating comprises TiO2, γ-Al2O3, Al2TiO5 phase and amorphous SiO2.

[0032] The titanium alloy used in the impeller in this embodiment is, for example, TC4. After plasma electrolytic oxidation treatment, the average thickness of the oxide film reaches 2 mm at most, and the obtained oxide film layer is dense, and the main phases are TiO2, γ-Al2O3 and Al2TiO5, and there is also a small amount of amorphous SiO2. The ceramic properties of the alloy surface make it have excellent high-temperature stability. The self-corrosion current density of the plasma electrolytic oxidation film is reduced by 3 orders of magnitude compared with the titanium alloy substrate, and the self-corrosion potential is positively shifted by 599 mV. The corrosion tendency and corrosion rate of the oxide film are significantly reduced.

[0033] The average thickness of the low-temperature wear-resistant coating is 1 mm, and the bonding force of the low-temperature wear-resistant coating to the impeller body is greater than 48 N.

[0034] In this embodiment, the average bonding force between the oxide film and the substrate is 48.5 N or more, and the film / substrate is well bonded, which ensures that it will not crack or fall off during low-temperature high-speed rotation. The average thickness of the low-temperature wear-resistant coating in this embodiment is 1 mm, which meets the design requirements. This film layer has good high-temperature stability and wear resistance, and can ensure good bonding with the substrate during low-temperature high-speed rotation, without cracking or falling off.

[0035] The microhardness of the low-temperature wear-resistant coating is more than 4 times that of the impeller body, and the microhardness of the oxide film reaches 800-1200 HV. The surface roughness value of the low-temperature wear-resistant coating is between Ra3.2 and Ra1.6, which can meet the technical requirements, and can be polished if special requirements are required. The film layer coated on the surface of the impeller body can effectively resist the wear of the liquid on the surface of the impeller under low-temperature gas-liquid two-phase working conditions, and prolong the service life of the impeller.

[0036] The temperature sensor is an embedded micro thin film temperature sensor, which can monitor the local temperature in real time.

[0037] The micro thin film temperature sensor, such as Pt100, is embedded in the liquid forming area of the impeller to monitor the local temperature in real time, and the temperature threshold alarm is combined, such as triggering protection when the temperature is lower than-150℃. According to the temperature sensor data, the phase change intensity of the liquid forming area is judged; if low-temperature anomaly is detected, the opening degree or rotating speed of the expander inlet valve is adjusted to prevent the impeller from freezing due to too low temperature or affecting the performance due to too high temperature. Other types of micro temperature sensors can also be used in this embodiment, but they must be able to accurately monitor the temperature in real time, and the sensing component is embedded in the area communicating between the high-pressure side and the low-pressure side of the impeller body. In this way, the phase change intensity of the liquid forming area can be judged according to the temperature data. Embodiment

[0038] This embodiment limits the flow guide hole based on embodiment 1 and proposes a low-temperature expander gas-liquid two-phase impeller, which refers to Figure 1 and Figure 2The turbine body is coated with a low-temperature wear-resistant coating.

[0039] The flow guide hole is arranged in the liquid forming area of the turbine body, the temperature sensor is embedded in the liquid forming area of the turbine body, and the low-temperature wear-resistant coating is coated on the surface of the turbine body, so that the liquid flow is effectively guided, the temperature is monitored in real time, and the wear resistance of the turbine is improved. This is because the flow guide hole can guide the liquid droplets to be discharged, avoid the accumulation of liquid film, and reduce the flow loss; the temperature sensor can obtain the temperature data of the liquid forming area in real time, so as to timely adjust the working state; the low-temperature wear-resistant coating can resist liquid wear and prolong the service life of the turbine. By connecting the high-pressure side and the low-pressure side of the turbine, the back pressure of the turbine is reduced, and the axial load of the bearing and the mechanical density is reduced.

[0040] The flow guide hole 3 is arranged through the turbine seat 1 along the radial direction of the turbine body, and the opening end of the flow guide hole 3 faces the turbine disc side.

[0041] The flow guide holes of the present application are independent of each other and uniformly distributed, and jointly guide the liquid droplets to be discharged to the turbine disc side, reduce the liquid film on the surface of the blade, reduce the flow loss, and improve the efficiency of the turbine.

[0042] The flow guide holes are circumferentially distributed on the turbine seat 1, and the distance between adjacent flow guide holes 3 is less than twice the diameter of the flow guide hole 3.

[0043] In the embodiment, the turbine body is made of titanium alloy material, the turbine diameter is 240mm, the flow guide hole 3 is designed according to the position of the liquid forming area of the turbine, the diameter of the flow guide hole 3 is 3-6mm, the opening diameter is 5mm, the number is 12, and the flow guide hole 3 is distributed in the liquid forming area of the turbine.

[0044] The cross-sectional shape of the flow guide hole 3 is conical, and the large end of the flow guide hole 3 faces the turbine back.

[0045] The design of the flow guide hole is beneficial to the better discharge of the liquid droplets, and the cross-sectional shape of the flow guide hole can also be circular, elliptical, etc.

[0046] The main body of the impeller seat 1 is cylindrical, and the installation hole 5 is coaxially arranged inside the impeller seat 1, the counterbore 6 is arranged near the disc side of the impeller, the main shaft installation taper hole 7 is arranged near the back side of the impeller, the taper is arranged at the fixed end of the main shaft 4 and the impeller seat 1, the taper is matched with the main shaft installation taper hole 7, the taper is internally provided with a threaded hole, one end of the stud bolt 9 is sequentially threaded through the counterbore 6 and the installation hole 5 and is threadedly connected with the threaded hole, the other end of the stud bolt 9 is threadedly connected with the installation nut 8, and the installation nut 8 is embedded into the counterbore 6.

[0047] The installation hole 5 and the main shaft installation taper hole 7 are provided with a clearance hole, and the diameter of the clearance hole is greater than the diameter of the installation hole 5 and the minimum diameter of the main shaft installation taper hole 7.

[0048] The impeller body is made of titanium alloy, the low-temperature wear-resistant coating is formed by a plasma electrolytic oxidation process, and the low-temperature wear-resistant coating includes TiO2, γ-Al2O3, Al2TiO5 phases and amorphous SiO2.

[0049] In the embodiment, the titanium alloy adopted by the impeller is, for example, TC4, after the plasma electrolytic oxidation treatment, the average thickness of the oxide film reaches 2 mm at most, the obtained oxide film layer is dense, the main phases are TiO2, γ-Al2O3 and Al2TiO5, and a small amount of amorphous SiO2, the ceramic characteristics of the alloy surface make it have excellent high-temperature stability. The self-corrosion current density of the plasma electrolytic oxidation film is reduced by 3 orders of magnitude compared with the titanium alloy substrate, the self-corrosion potential is positively shifted by 599 mV, and the corrosion tendency and corrosion rate of the oxide film are significantly reduced.

[0050] The average thickness of the low-temperature wear-resistant coating is 1 mm, and the bonding force between the low-temperature wear-resistant coating and the impeller body is greater than 48 N.

[0051] In the embodiment, the average bonding force between the oxide film and the substrate is 48.5 N or more, the film / substrate is well combined, and it is ensured that the oxide film will not crack or fall off during low-temperature high-speed rotation. The average thickness of the low-temperature wear-resistant coating in the embodiment is 1 mm, which can meet the design requirements. The film layer has good high-temperature stability and wear resistance, and can ensure good combination with the substrate during low-temperature high-speed rotation, and will not crack or fall off.

[0052] The microhardness of the low-temperature wear-resistant coating is more than 4 times that of the impeller body, the microhardness of the oxide film reaches 800-1200 HV, and the surface roughness value of the low-temperature wear-resistant coating is between Ra3.2 and Ra1.6, which can meet the technical requirements, and can be polished if special requirements are required. The film layer coated on the surface of the impeller body can effectively resist the wear of the liquid on the surface of the impeller under the low-temperature gas-liquid two-phase working condition, and prolong the service life of the impeller.

[0053] The temperature sensor is an embedded micro thin film temperature sensor, which monitors the local temperature in real time.

[0054] The impeller liquid forming area is embedded with a micro thin film temperature sensor, such as Pt100, which monitors the local temperature in real time and triggers a protection alarm when the temperature is lower than -150℃. According to the temperature sensor data, the phase change strength of the liquid forming area is determined; if low temperature anomalies are detected, the expansion machine inlet valve opening or speed is adjusted to prevent the impeller from freezing due to too low temperature or affecting performance due to too high temperature. Other types of micro temperature sensors can also be used in this embodiment, but they must be able to accurately monitor the temperature in real time, and the sensing component is embedded in the area where the high pressure side of the impeller body communicates with the low pressure side. In this way, the phase change strength of the liquid forming area can be determined according to the temperature data. Embodiment

[0055] In this embodiment, the low-temperature wear-resistant coating of Embodiment 1 is replaced with a nickel-graphite wear-resistant coating, which exhibits higher stability in a wear system composed of titanium alloy. The oxidation layer of the impeller in this embodiment is subjected to high-temperature performance testing:

[0056] 1. High-temperature resistance: heated to 350℃ and 425℃ respectively for 10 hours, and then detected. The oxidation layer and the substrate are in good bonding state, and the performance remains stable;

[0057] 2. Thermal shock resistance: according to ASTM B571 standard, the sample with oxidation layer is heated to 500℃ in the furnace for half an hour, then taken out and put into room temperature water, completely cooled, then taken out and observed, and this process is repeated 50 times. The results show that the surface oxidation layer has stable performance; no bubbling, cracking or peeling phenomenon occurs, indicating that the oxidation film and the substrate are well combined. The test results are shown in Table 1.

[0058] Table 1 Oxidation film test results

[0059] AlSi / polyphenyl resin AlSi / graphite Ni / graphite NiCuSi / graphite Ni / kieselguhr metal / BN Ni / Cr kieselguhr spraying process plasma plasma plasma flame plasma flame plasma flame plasma plasma flame coating hardness HR15y 50-80 40-50 40-70 40-70 60-85 60 30-70 maximum service temperature / °C 350 450 480 650 750-800 800 850

[0060] As can be seen, the nickel-graphite wear-resistant coating can withstand a maximum temperature of 480 / ℃, and it can operate stably at 387℃. This type of coating has good bonding force, and when it is scratched, it falls off in the form of fine powder, rather than in the form of bulk peeling.

Claims

1. A low temperature expander gas-liquid two-phase impeller, characterized by, The application relates to a turbine seat (1) provided with a plurality of blades (2) and a plurality of guide holes (3) on the turbine seat (1), wherein the turbine seat (1) is fixedly connected with a main shaft (4) of an expander, the inlet of the guide hole (3) is arranged in a liquid forming area of the turbine and is connected with a high-pressure side and a low-pressure side of the expansion chamber, a temperature sensor is arranged in the liquid forming area of the turbine, and a low-temperature wear-resistant coating is coated on the surface of the turbine body; the low-temperature wear-resistant coating is formed through a plasma electrolytic oxidation process, the low-temperature wear-resistant coating comprises TiO2, gamma-Al2O3 and Al2TiO5 phases and amorphous SiO2; the average thickness of the low-temperature wear-resistant coating is 1 mm, the bonding force between the low-temperature wear-resistant coating and the turbine body is greater than 48 N, the microhardness of the low-temperature wear-resistant coating is more than 4 times that of the turbine body, and the surface roughness value of the low-temperature wear-resistant coating is between Ra3.2 and Ra1.

6.

2. A gas-liquid two-phase impeller for a cryogenic expander according to claim 1, wherein The main body of the turbine seat (1) is in a cylindrical shape, a mounting hole (5) is coaxially arranged in the turbine seat (1), a counterbore (6) is arranged on the side of the turbine disc of the mounting hole (5), a main shaft mounting taper hole (7) is arranged on the side of the turbine back of the mounting hole (5), a taper table is arranged on the fixed end of the main shaft (4) and the main shaft mounting taper hole (7), a threaded hole is arranged in the taper table, one end of a double-headed bolt (9) is sequentially threaded through the counterbore (6) and the mounting hole (5) and is screwed with the threaded hole, the other end of the double-headed bolt (9) is screwed with a mounting nut (8), and the mounting nut (8) is embedded into the counterbore (6).

3. A gas-liquid two-phase impeller for a cryogenic expander according to claim 2, wherein A relief hole is arranged at the connection between the mounting hole (5) and the main shaft mounting taper hole (7), and the diameter of the relief hole is greater than the diameter of the mounting hole (5) and the minimum diameter of the main shaft mounting taper hole (7).

4. A gas-liquid two-phase impeller for a cryogenic expander according to claim 1, wherein The guide hole (3) is arranged through the turbine seat (1) along the radial direction of the turbine body, and the opening end of the guide hole (3) faces the turbine disc side.

5. A gas-liquid two-phase impeller for a cryogenic expander according to claim 1, wherein The guide holes are circumferentially distributed on the turbine seat (1), and the spacing between adjacent guide holes (3) is less than twice the diameter of the guide hole (3).

6. A gas-liquid two-phase impeller for a cryogenic expander according to claim 1, wherein The temperature sensor is an embedded micro thin film temperature sensor, which can monitor the local temperature in real time.

7. A gas-liquid two-phase impeller for a cryogenic expander according to claim 1, wherein The cross-sectional shape of the guide hole (3) is conical, and the large end of the guide hole (3) faces the turbine back.

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