Anti-surge structure for small-flow working condition and centrifugal supercharger

Abstract

The invention provides an anti-surge structure for a small-flow working condition and a centrifugal supercharger, the anti-surge structure is arranged in the centrifugal supercharger and used for replacing a traditional impeller structure, and the anti-surge structure adopts a limited flow channel structure and is composed of a plurality of fixed-width flow channels which are radially arranged around a rotating axis. The flow channel is used for guiding gas to axially enter and be stably discharged in the radial direction in the rotating state, so that the rotating separation phenomenon of the gas in the flow channel under the small-flow working condition is effectively restrained, and the surge occurrence probability is reduced. The centrifugal supercharger adopting the anti-surge structure comprises a casing front cover, a casing rear cover, a supercharger inlet arranged on the front cover, a limited flow channel structure arranged in the casing, a supercharger outlet arranged on the periphery of the casing, and a shaft penetrating through the rear cover and used for driving the flow channel structure to rotate. The device is compact in structure and stable in operation, is particularly suitable for application requirements on stable pressurization and surge prevention of gas in a small-flow working condition scene, and has a good popularization prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of centrifugal supercharging, and particularly to an anti-surge structure and a centrifugal supercharger for small flow conditions. Background Art

[0002] In fluid machinery, a gas supercharger, as a key energy conversion device, plays an important role in maintaining the medium transmission efficiency and system stability. Its basic principle is to increase the gas pressure through mechanical work, and it is widely used in fields such as energy transportation, chemical production, and industrial manufacturing, such as in scenarios like long-distance pipeline transportation, reactor medium pressurization, and thermal cycle systems.

[0003] Gas superchargers can be classified into two categories according to the working principle: positive displacement type and dynamic type. Positive displacement superchargers (such as reciprocating compressors and screw compressors) directly compress the gas by periodically changing the volume of a closed space; dynamic superchargers convert the kinetic energy of the gas into pressure energy through high-speed rotating components. At the same flow rate, dynamic superchargers have less mechanical friction loss and lower overall energy consumption because there is no reciprocating motion or periodic volume change. The dynamic supercharger has a simple and compact structure, usually consisting of a single rotating impeller and a diffuser, without complex gas valves or sealing components and wearing parts (such as piston rings and gas valves), and has low maintenance costs. According to the different gas flow directions, dynamic superchargers can be further divided into two categories: centrifugal type (gas flowing radially) and axial flow type (gas flowing axially). Centrifugal superchargers rely on centrifugal force to do work on the gas. Common centrifugal fans and centrifugal compressors convert the kinetic energy of the gas into pressure energy by the centrifugal force generated when the impeller rotates. Axial flow superchargers generate aerodynamic lift through the rotation of the blades to push the gas to flow axially, and generally use multiple stages of blades for step-by-step supercharging. Compared with axial flow superchargers, centrifugal superchargers are applicable to smaller flow rates, but have stronger supercharging capabilities and stronger tolerance to trace impurities or corrosive gases. Centrifugal superchargers such as centrifugal fans and centrifugal compressors have become widely used power equipment in the industrial field.

[0004] However, centrifugal fans and centrifugal compressors both have the common problem of rotating machinery: the surge phenomenon. When the processed flow rate is less than the critical flow rate, the internal flow field of the impeller deteriorates, and the air flow that should flow continuously generates rotational separation in the flow channel, forming intermittent asymmetric vortex clusters that rush towards the outlet. Centrifugal fans and centrifugal compressors always work in combination with the pipeline network system. These vortex clusters cause instantaneous high pressure at the outlet and induce backflow, forming periodic repeated oscillations, seriously interfering with the normal operation of the supercharger. Surge not only significantly reduces the supercharging efficiency and system stability, but may also cause strong vibrations, structural resonances, seal failures, component fatigue, and even damage to the entire machine, posing a great safety hazard.

[0005] To mitigate the surge risk, in the prior art, a bypass return pipeline or a surge control valve is usually provided to guide part of the gas to return under a small flow rate condition; or a diffuser is provided or the impeller design is improved to broaden the stable operation region. However, these methods still have significant deficiencies when dealing with small flow rate conditions. For example, the return structure occupies a large space, the control system is complex, and the response speed is difficult to match the rapid load change, and the occurrence of surge is still difficult to avoid.

[0006] Therefore, how to effectively suppress or delay the occurrence of surge under small flow rate conditions on the premise of a compact structure and timely response, and achieve stable operation and efficient supercharging has become an important direction in the current research on surge prevention technology for centrifugal superchargers. Summary of the Invention

[0007] In view of the above-mentioned technical problems, a surge prevention structure and a centrifugal supercharger for small flow rate conditions are provided. The present invention uses a restricted flow channel structure to replace the vane type impeller structure in a traditional centrifugal supercharger. By controlling the width and arrangement of the flow channels, the air flow is guided to form a stable flow field during rotation, effectively suppressing the rotational separation phenomenon in the flow channels, and thereby reducing the possibility of surge occurrence.

[0008] The technical means adopted by the present invention are as follows:

[0009] A surge prevention structure for small flow rate conditions, wherein the surge prevention structure is a restricted flow channel structure provided in the centrifugal supercharger to replace the impeller. The restricted flow channel structure has a plurality of flow channel structures with a fixed width arranged radially around the rotation axis. The flow channel structure is used to guide the gas to axially enter and stably discharge radially in a rotating state, thereby suppressing the rotational separation phenomenon of the gas in the flow channel and reducing the occurrence of surge under small flow rate conditions.

[0010] Further, the restricted flow channel structure is a flow channel disk structure, including a suction inlet section I, a rear disk, a front disk, and a hub I, and a plurality of equally spaced flow channel structures are machined on the main body of the flow channel disk.

[0011] Further, the restricted flow channel structure is a tube bundle type structure, and a plurality of formed pipes form the flow channel structure, including a suction inlet section II, a tubular flow channel, and a hub II. The cross-sectional shape of the tubular flow channel is circular, elliptical, or rectangular.

[0012] Further, the flow channel structure is a straight flow channel, a forward curved flow channel, or a backward curved flow channel. Each flow channel is arranged at equal intervals along the circumferential direction around the rotation axis and is uniformly arranged in a fan shape. The number and size of the flow channels are determined according to the actual working conditions.

[0013] Further, the suction inlet section of the restricted flow channel structure is connected to the supercharger inlet. The gas enters the flow channel structure from the supercharger inlet, is thrown out from the outer edge of the flow channel structure after high-speed rotation, and then is discharged from the supercharger outlet.

[0014] The present invention also provides a centrifugal supercharger adopting the above anti-surge structure for small flow conditions, which includes a front cover and a rear cover of the casing, a supercharger inlet provided on the front cover of the casing, a restricted flow channel structure installed inside the casing and connected to a rotating shaft, a supercharger outlet provided on the outer peripheral part of the casing and communicating with the outer edge of the flow channel structure, and a shaft passing through the rear cover of the casing for driving the restricted flow channel structure to rotate. A seal is provided between the shaft and the rear cover of the casing.

[0015] Further, the motor drive assembly is directly fixed to the casing by bolt connection and directly connected to the centrifugal supercharger, or is connected to the shaft through a coupling or a pulley.

[0016] Further, the supercharger inlet is an axial air inlet and is connected to the suction inlet section of the restricted flow channel structure; the supercharger outlet is a radial air outlet and communicates with the outer edge of the flow channel of the restricted flow channel structure.

[0017] Further, the seal is a mechanical seal and is installed at the mating part between the rear cover of the casing and the shaft. The moving ring of the seal is rotatably connected to the shaft, and the stationary ring is fixed inside the rear cover of the casing.

[0018] Further, the restricted flow channel structure is a modular component, which is convenient for disassembly and replacement and adapts to the supercharging requirements under different working conditions.

[0019] The present invention has the following advantages:

[0020] 1. The restricted flow channel structure provided by the present invention suppresses the separation of gas during rotation by fixing the channel width and optimizing the flow path design, reducing the occurrence of backflow and pressure fluctuations at the source. Compared with the traditional impeller, its supercharging characteristic curve is smoother, showing a monotonically decreasing trend, without the interference of a hump section, and intersects with the pipeline characteristic curve within the stable operation range, effectively expanding the stable working condition range and improving the overall supercharging efficiency.

[0021] 2. The restricted flow channel structure provided by the present invention has various implementation methods. It can either form a closed flow channel by means of disk machining or construct a radial flow channel by means of a formed tube bundle; the number of flow channels, the width of the flow channels, the bending form of the flow channels (such as a straight channel, a front bend or a rear bend), and the channel cross-section (circular, elliptical, rectangular, etc.) can all be flexibly configured according to different working condition requirements, adapting to various pressure grades and gas characteristics, and having wide engineering applicability.

[0022] In summary, by adopting a restricted flow channel structure to replace the impeller structure in a traditional centrifugal supercharger, the present invention significantly improves the operating stability and anti-surge ability under small flow conditions. The structure is simple, the manufacturing process is diverse, and it is suitable for connecting to a standard motor shaft, with convenient installation and low maintenance costs. It is particularly suitable for scenarios with high requirements for surge control, such as low load, variable working conditions, and small flow, and has significant industrial application value and promotion prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 It is a schematic structural diagram of a centrifugal supercharger for small flow conditions of the present invention.

[0025] Figure 2 It is Figure 1 a side view of

[0026] Figure 3 It is a structural diagram of a restricted flow channel structure being a flow channel disk structure.

[0027] Figure 4 It is a cross-sectional view of a restricted flow channel structure being a flow channel disk structure.

[0028] Figure 5 It is a structural diagram of a restricted flow channel structure being a tube bundle structure.

[0029] Figure 6 It is a structural diagram of a flow channel on the rear disk of a flow channel disk structure being a forward curved flow channel.

[0030] Figure 7 It is a structural diagram of a flow channel on the rear disk of a flow channel disk structure being a backward curved flow channel.

[0031] Figure 8 It is a structural diagram of a flow channel on the rear disk of a flow channel disk structure being a straight flow channel.

[0032] Figure 9 It is a structural diagram of a flow channel of a tube bundle structure being a forward curved flow channel.

[0033] Figure 10 It is a structural diagram of a flow channel of a tube bundle structure being a backward curved flow channel.

[0034] Figure 11 It is a structural diagram of a flow channel of a tube bundle structure being a straight flow channel.

[0035] Figure 12 Schematic diagram of a circular cross-section of a tubular flow channel.

[0036] Figure 13 Schematic diagram of a rectangular cross-section of a tubular flow channel.

[0037] Figure 14 Schematic diagram of an elliptical cross-section of a tubular flow channel.

[0038] Figure 15 Boost pressure flow curve of Example 1.

[0039] Figure 16 Boost pressure flow curve of Example 2.

[0040] In the figure: 1. Supercharger inlet; 2. Front cover of the housing; 3. Flow channel disc structure; 3-1. Hub Ⅰ; 3-2. Rear disc; 3-3. Front disc; 3-4. Suction inlet section Ⅰ; 4. Supercharger outlet; 5. Rear cover of the housing; 6. Sealing element; 7. Shaft; 8. Tube bundle structure; 8-1. Suction inlet section Ⅱ; 8-2. Tubular flow channel; 8-3. Hub Ⅱ. Detailed implementation mode

[0041] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0042] As Figure 1 、 Figure 2 shown, it is a centrifugal supercharger with an anti-surge structure for small flow conditions, including a front cover 2 of the housing, a supercharger inlet 1, a restricted flow channel structure, a supercharger outlet 4, a rear cover 5 of the housing, a shaft 7, a sealing element 6, and a motor. The connection relationship is as follows:

[0043] The front cover 2 of the housing is connected to the rear cover 5 of the housing to jointly form the outer housing of the supercharger, and a closed cavity for accommodating the restricted flow channel structure and the shaft is formed inside.

[0044] The supercharger inlet 1 is arranged at the central position of the front cover 2 of the housing to guide the gas to enter the inside of the housing along the axis.

[0045] The restricted flow channel structure is installed inside the housing and fixed on the rotating shaft, and is radially divergingly arranged around the axis center and rotates with the shaft. The gas enters the flow channel from the axial suction inlet, obtains kinetic energy during the rotation process, and is discharged radially, thereby suppressing the rotational separation phenomenon of the gas in the flow channel and reducing the occurrence of surge under small flow conditions.

[0046] The supercharger outlet 4 is arranged in the outer peripheral area of the housing and is connected to the outer edge of the restricted flow channel for discharging the pressurized gas.

[0047] The shaft 7 penetrates through the rear cover 5 of the housing and is coaxially connected to the restricted flow channel structure to drive the flow channel structure to rotate.

[0048] The seal 6 is installed at the mating part between the rear cover 5 of the housing and the shaft 7 to prevent gas leakage; the seal 6 is a mechanical seal and is installed at the mating part between the rear cover 5 of the housing and the shaft 7. The moving ring of the seal 6 is rotatably connected to the shaft 7, and the stationary ring is fixed inside the rear cover 5 of the housing. The moving ring and the stationary ring form an end face seal pair to prevent gas leakage inside the supercharger and external air from entering the supercharger through other than the supercharger inlet 1. The motor (not shown in the figure) is connected to the shaft 7 to drive the restricted flow channel structure to rotate, and the motor can be connected to the shaft through bolts, couplings or pulleys.

[0049] Through the above connection structure, the restricted flow channel structure replaces the impeller structure. The gas enters the centrifugal supercharger axially through the inlet, obtains energy in the rotating restricted flow channel structure, and is stably discharged radially from the outlet, forming a stable pressurization path from axial intake to radial outlet. The restricted flow channel structure provided by the present invention is a modular component, which is convenient for disassembly and replacement and adapts to the pressurization requirements under different working conditions.

[0050] Specifically, as Figure 3 and Figure 4 shown, the restricted flow channel structure is a flow channel disk structure 3, including a suction inlet section Ⅰ 3-4, a rear disk 3-2, a front disk 3-3 and a hub Ⅰ 3-1. A plurality of equally spaced flow channel structures are machined on the main body of the flow channel disk. The front disk 3-3 and the rear disk 3-2 can be connected by bolts or rivets; the suction inlet section Ⅰ 3-4 is connected to the supercharger inlet 1. The gas enters the flow channel structure from the supercharger inlet 1, is thrown out from the outer edge of the flow channel structure after high-speed rotation, and then is discharged from the supercharger outlet 4. As Figure 6 shown, the flow channel structure is a forward-curved flow channel; as Figure 7 shown, it is a backward-curved flow channel; as Figure 8 shown, it is a straight-through flow channel. Each flow channel is arranged at equal intervals along the circumferential direction around the rotation axis and is evenly arranged in a fan shape. The number and size of the flow channels are determined according to the actual working conditions.

[0051] As Figure 5 shown, the restricted flow channel structure is a tube bundle structure 8, which consists of a plurality of formed pipes to form the flow channel structure, including a suction inlet section Ⅱ 8-1, a tubular flow channel 8-2 and a hub Ⅱ 8-3. As Figure 9 shown, the flow channel structure is a forward-curved flow channel; as Figure 10 shown, it is a backward-curved flow channel; as Figure 11 shown, it is a straight-through flow channel; the cross-sectional shape of the tubular flow channel 8-2 is circular (asFigure 12 as shown), oval (such as Figure 14 shown), or rectangular (such as Figure 13 shown). The materials that can be used for the tube bundle flow channels are diverse and are selected according to different application scenarios, including but not limited to metals, rubbers, resins, etc.

[0052] The working process of the centrifugal supercharger with a restricted flow channel structure of the present invention is as follows:

[0053] Driven by an electric motor, the present invention rotates at a high speed. The gas with a certain pressure is transported through a pipeline to the inlet 1 of the supercharger and is sucked into the flow channel by the high-speed rotating restricted flow channel. The restricted flow channel rotates at a high speed to generate centrifugal force, and the gas is transported through the flow channel to the outer edge of the restricted flow channel and enters the diffuser area in the casing to continue rotating to complete the deceleration process, converting the velocity energy into pressure energy. After the flow becomes stable, the gas finally exits from the outlet 4 of the supercharger and enters the next section of the pipeline. The process of converting mechanical energy into the energy of the gas (kinetic energy, pressure energy, potential energy, etc.) is completed, and at the same time, the purpose of pressurizing the gas and long-distance transportation is achieved.

[0054] The present invention has the advantages of high supercharging efficiency, stable operation, simple structure, convenient maintenance, and cost saving, meets the requirements of energy conservation and environmental protection, and can be applied to multiple fields such as high-pressure natural gas transportation, long-distance pipeline transportation, reactor medium pressurization, and thermal cycle systems, providing an effective solution for the efficient, safe, and stable operation of supercharging equipment under small flow conditions.

[0055] Example 1

[0056] A centrifugal supercharger with an anti-surge structure for small flow conditions provided by the present invention has a restricted flow channel structure as Figure 7 shown, with an inner diameter of 150 mm, an outer diameter of 800 mm, a restricted flow channel width of 30 mm, a number of flow channels of 6, a flow channel form of a backward-curved flow channel, a flow channel inlet angle of 45°, a flow channel outlet angle of 20°, and a flow channel depth of 30 mm. Using air as the medium, experiments are carried out at a rotational speed of 3000 r / min under an inlet pressure of 0.2 MPa and a mass flow rate of 0.2 - 0.7 kg / s.

[0057] Driven by an electric motor, the centrifugal supercharger operates at a rotational speed of 3000 r / min. The inlet pressure is controlled at the set value by adjusting the valve, and the mass flow rate is adjusted to 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7 kg / s respectively. During the adjustment process, the supercharging situation of the centrifugal supercharger is recorded, and the occurrence of surge phenomenon is detected.

[0058] As Figure 15 shown, it can be seen from the supercharging situation of the centrifugal supercharger that the supercharging curve basically conforms to the trend of monotonically decreasing, no unstable operation interval appears, and no surge phenomenon is detected during the operation process.

[0059] Example 2

[0060] On the basis of Example 1, the detection conditions are as follows: using air as the medium, conducting experiments at a rotational speed of 3000 r / min with an intake pressure of 0.4 MPa and a mass flow rate of 0.2 - 0.7 kg / s.

[0061] As Figure 16 shown, from the supercharging situation of the centrifugal supercharger, it can be seen that the supercharging curve basically conforms to the trend of monotonically decreasing, no unstable operation interval appears, and no surge phenomenon is detected during the operation.

[0062] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the present invention; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An anti-surge structure for small flow conditions, characterized in that: The anti-surge structure is a restricted flow channel structure arranged in the centrifugal supercharger instead of the impeller. The restricted flow channel structure has a plurality of fixed-width flow channel structures radially arranged around the rotation axis. The flow channel structure is used to guide the gas to enter axially and be discharged stably radially under a rotating state, thereby suppressing the rotational detachment of the gas in the flow channel and reducing the occurrence of surge under low flow conditions.

2. The anti-surge structure according to claim 1, characterized in that: The restricted flow channel structure is a flow channel disc structure, including an inlet section I, a rear disc, a front disc and a hub I, and a plurality of equidistant flow channel structures are processed on the flow channel disc body.

3. The anti-surge structure according to claim 1, characterized in that: The restricted flow channel structure is a tube bundle structure, which is composed of a plurality of formed pipes and includes a suction port section II, a tubular flow channel and a hub II. The cross-sectional shape of the tubular flow channel is circular, elliptical or rectangular.

4. The anti-surge structure according to claim 2 or 3, characterized in that: The flow channel structure is a straight flow channel, a front curved flow channel or a rear curved flow channel. The flow channels are arranged at equal intervals in the circumferential direction around the rotation axis and are evenly arranged in a fan shape. The number and size of the flow channels are determined according to actual working conditions.

5. The anti-surge structure according to claim 4, characterized in that: The suction port section of the restricted flow channel structure is connected to the supercharger inlet, and the gas enters the flow channel structure from the supercharger inlet, is thrown out from the outer edge of the flow channel structure after high-speed rotation, and is discharged from the supercharger outlet.

6. A centrifugal supercharger using the anti-surge structure for low flow conditions as claimed in claim 5, characterized in that: The invention comprises a casing front cover and a casing rear cover, a supercharger inlet arranged on the casing front cover, a restricted flow channel structure installed inside the casing and connected to the rotating shaft, a supercharger outlet arranged at the outer peripheral part of the casing and connected to the outer edge of the flow channel structure, and a shaft penetrating the casing rear cover for driving the restricted flow channel structure to rotate, and a sealing member is arranged between the shaft and the casing rear cover.

7. The centrifugal supercharger according to claim 6, characterized in that: The motor drive assembly is directly fixed on the casing through bolt connection and is directly connected to the centrifugal supercharger, or is connected to the shaft through a coupling or a pulley.

8. The centrifugal supercharger according to claim 7, characterized in that: The inlet of the supercharger is an axial air inlet connected to the suction port section of the restricted flow channel structure; the outlet of the supercharger is a radial air outlet connected to the outer edge of the flow channel of the restricted flow channel structure.

9. The centrifugal supercharger according to claim 6, characterized in that: The seal is a mechanical seal installed at the matching position between the housing rear cover and the shaft. The dynamic ring of the seal is rotatably connected to the shaft, and the static ring is fixed in the housing rear cover.

10. The centrifugal supercharger according to claim 6, characterized in that: The restricted flow channel structure is a modular component, which is easy to disassemble and replace and adapt to the boost requirements under different working conditions.

Images