Wing-shaped blade diffuser

Abstract

The invention provides a wing-shaped blade diffuser, relates to a diffuser, and solves the technical problems that an existing multi-blade diffuser is small in operation working condition range and cannot meet the requirements of industries such as petroleum, chemical engineering and steel on a wide working condition range of a centrifugal compressor. The sum of the included angles of the mean camber lines of the 7-11 blades accounts for 44%-65% of the angle of the diffuser ring, the number and the angle of the blades on the diffuser are limited, it is guaranteed that the diffuser improves the single-stage pressure ratio and the single-stage efficiency, meanwhile, limitation on the gas flow is avoided, and therefore it is guaranteed that the centrifugal compressor has the wide operation working condition. After CFD calculation, compared with an original vaneless diffuser and a conventional blade diffuser, the surge margin is widened by 2.38%, and the surge margin is reduced to 705.8 m < 3 > / min from the original 722.6 m < 3 > / min. At the maximum flow point, the total pressure of an outlet is increased to 1.8945 from the original 1.8743, and when the pressure of an inlet is 202.97 kPa, the total pressure loss is reduced by 4.1 kPa. Compared with a vaneless diffuser, the polytropic efficiency of the wing-shaped diffuser is improved by 1.918% to the maximum extent.

Description

Technical Field

[0001] The present invention relates to a diffuser, and more particularly to a diffuser with wing-shaped blades. Background Art

[0002] Centrifugal compressors are widely used in fields such as petroleum, chemical industry, and steel. With the continuous development of centrifugal compressor technology, while ensuring high performance and wide operating conditions of the compressor, there are new requirements for its small size and low energy consumption.

[0003] The diffuser in a centrifugal compressor is used to convert the kinetic energy of the high-speed movement of the gas into pressure energy, making full use of the relatively high flow velocity of the gas when it flows out of the impeller to increase the gas pressure. In the prior art, a vaneless diffuser or a multi-vane diffuser is usually adopted in a centrifugal compressor. Among them, the vaneless diffuser has the advantage of a wide operating condition range, but its working efficiency is low and it cannot better meet the existing design requirements. An ordinary multi-vane diffuser can increase the single-stage pressure ratio, thereby improving the stage efficiency and meeting the requirements of small-sized models. However, due to the narrowing of the flow channel of the multi-vane diffuser, the gas flow rate passing through the multi-vane diffuser is limited. Therefore, the operating condition range of the centrifugal compressor using the multi-vane diffuser will decrease sharply, and it cannot meet the requirements of the petroleum, chemical industry, steel and other industries for the wide operating condition range of the centrifugal compressor, severely restricting the application range of the centrifugal compressor. Therefore, neither the vaneless diffuser nor the ordinary multi-vane diffuser can simultaneously meet the requirements of high efficiency, high pressure ratio, small size and wide operating condition range. Summary of the Invention

[0004] The purpose of the present invention is to solve the deficiencies that the existing vaneless diffuser or multi-vane diffuser cannot simultaneously meet the requirements of high efficiency, high pressure ratio, small size and wide operating condition range for centrifugal compressors in industries such as petroleum, chemical industry, and steel, and to propose a diffuser with wing-shaped blades.

[0005] To solve the above technical problems, the technical solution provided by the present invention is as follows:

[0006] A diffuser with wing-shaped blades for a centrifugal compressor, comprising a diffuser ring and N blades provided on the diffuser ring; the special feature is that:

[0007] The blades are wing-shaped blades, and the total area occupied by the N wing-shaped blades on the side of the diffuser ring accounts for 2% - 5% of the area of the side of the diffuser ring where they are located;

[0008] The ratio of the inner circle diameter φc of the diffuser ring to the diameter φb of the circle where the center point of the leading edge of the wing-shaped blade is located is 0.8 - 0.9;

[0009] The ratio of the diameter φa of the circle where the center point of the trailing edge of the wing-shaped blade is located to the outer circle diameter φd of the diffuser ring is 0.7 - 0.8;

[0010] The sum N*e° of the central angles e° corresponding to the mean arcs of N wing-shaped blades accounts for 44% to 65% of the circular angle of the diffuser ring, where N is 7 to 11.

[0011] Further, N is 11.

[0012] Further, the leading edge of the wing-shaped blade is an arc structure, the trailing edge is a pointed structure, and both sides of the sharp angle are straight.

[0013] Further, the ratio of the diameter φc of the inner circle of the diffuser to the diameter φb of the circle where the center point of the leading edge of the wing-shaped blade is located is 0.845.

[0014] Further, the ratio of the diameter φa of the circle where the center point of the trailing edge of the wing-shaped blade is located to the diameter φd of the outer circle of the diffuser is 0.7094.

[0015] Further, the sum N*e° of the angles e° of the mean arcs of the N wing-shaped blades accounts for 44.53% of the entire circular angle.

[0016] Further, the total area occupied by the wing-shaped blades on the side of the diffuser ring accounts for 4.24% of the area of the side of the diffuser ring where they are located.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] 1. In the present invention, the sum of the angles e° of the mean arcs of multiple blades accounts for 44% to 65% of the circular angle of the diffuser ring. The ratio of the diameter φa of the circle where the center point of the trailing edge of the blade is located to the outer diameter φd of the diffuser ring is 0.7 to 0.8, and the ratio of the inner diameter φc of the diffuser ring to the diameter φb of the circle where the center point of the leading edge of the blade is located is 0.8 to 0.9. After performing CFD calculations, the surge margin of a wing-shaped blade diffuser of the present invention is widened by 2.38% compared to the original vaneless diffuser and the conventional blade diffuser, decreasing from the original 722.6 m3 / min to 705.8 m3 / min. At the maximum flow rate point, the outlet total pressure ratio is increased from the original 1.8743 to 1.8945, and when the inlet pressure is 202.97 kPa, the total pressure loss is reduced by 4.1 kPa. The polytropic efficiency of the wing-shaped diffuser is increased by a maximum of 1.918% compared to the vaneless diffuser.

[0019] 2. The diffuser ring of the present invention is provided with 11 wing-shaped blades evenly distributed. When the number of blades is too large, it will limit the gas flow rate, thereby affecting the operating conditions of the centrifugal compressor; when the number of blades is small, the working efficiency of the diffuser is low. By restricting the number and angle of the blades, the present invention ensures that while improving the single-stage pressure ratio and stage efficiency of the diffuser, it avoids restricting the gas flow rate, thus ensuring that the centrifugal compressor has a relatively wide operating range.

[0020] 3. The sum of the included angles e° of the camber lines of the blades in the present invention, N*e°, accounts for 44.53% of the entire circular angle. When the included angle e° of the camber lines of the blades is too large, the gap between two adjacent blades becomes correspondingly smaller, that is, the channel of the diffuser becomes narrower, which restricts the gas flow rate passing through the diffuser, thereby affecting the pressure boosting efficiency of the diffuser. When the included angle e° of the camber lines of the blades is too small, the conversion efficiency of the diffuser for the gas kinetic energy is low, and the pressure boosting effect is poor. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of an embodiment of a wing-shaped blade diffuser of the present invention;

[0022] Figure 2 is a comparison diagram of the flow rate-pressure ratio curves of an embodiment of a wing-shaped blade diffuser of the present invention, an existing bladeless diffuser, and a conventional blade diffuser;

[0023] Figure 3 is a comparison diagram of the flow rate-polytropic efficiency curves of an embodiment of a wing-shaped blade diffuser of the present invention, an existing bladeless diffuser, and a conventional blade diffuser;

[0024] Figure 4 is a schematic structural diagram of the application of an embodiment of a wing-shaped blade diffuser of the present invention in a centrifugal compressor.

[0025] Description of the reference numerals:

[0026] 1-wing-shaped blade diffuser, 101-wing-shaped blade, 102-diffusion ring; 2-housing; 3-air inlet; 4-air outlet; 6-impeller; 9-baffle. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The present invention will be further described below with reference to the drawings and embodiments.

[0028] The present invention provides a wing-shaped blade diffuser 1, as Figure 1As shown in the figure, it includes a diffuser ring 102 and N wing-shaped blades 101 arranged on the diffuser ring 102. The range of N is 7 to 11, and in this embodiment, N is 11. The 11 wing-shaped blades 101 are evenly distributed on the diffuser ring 102 along the circumferential direction. The total area occupied by the 11 wing-shaped blades 101 on the side of the diffuser ring (102) accounts for 2% to 5% of the side area of the diffuser ring (102) where they are located. In this embodiment, the total area occupied by the 11 wing-shaped blades 101 on the side of the diffuser ring 102 accounts for 4.24% of the side area of the diffuser ring 102. When the number of wing-shaped blades 101 on the diffuser ring 102 is too large, the gap between the wing-shaped blades 101 is too small, which will limit the flow rate of the passing gas, and thus affect the operating conditions of the centrifugal compressor; when the number of wing-shaped blades 101 on the diffuser ring 102 is too small, the pressure-increasing effect of the diffuser is poor, affecting the working efficiency of the centrifugal compressor.

[0029] The inner diameter of the inner circle of the diffuser ring 102 is φc, and the outer diameter of the outer circle is φd. The leading edge of the wing-shaped blade 101 is arc-shaped, and the trailing edge is a pointed structure, with both sides of the sharp angle being straight. The diameter of the circle where the center point of the leading edge of the wing-shaped blade 101 is located is φb, and the diameter of the circle where the center point of the trailing edge is located is φa. The ratio of the inner diameter φc of the diffuser ring 102 to the diameter φb of the circle where the center point of the leading edge of the wing-shaped blade 101 is located is 0.845, and the ratio of the diameter φa of the circle where the center point of the trailing edge of the wing-shaped blade 101 is located to the outer diameter φd of the diffuser ring 102 is 0.7094. The sum of the central angles e° corresponding to the middle arcs of the 11 wing-shaped blades 101 accounts for 44.53% of the entire central angle of the diffuser ring 102. If the central angle e° corresponding to the middle arc of the wing-shaped blade 101 is too large, the gap between two adjacent wing-shaped blades 101 becomes correspondingly smaller, and the channel of the wing-shaped blade diffuser 1 becomes narrower, which will limit the gas flow rate passing through the wing-shaped blade diffuser 1, thus affecting the pressure-increasing efficiency of the wing-shaped blade diffuser 1. If the central angle e° corresponding to the middle arc of the wing-shaped blade 101 is too small, the conversion efficiency of the diffuser for the gas kinetic energy is low, and the pressure-increasing effect is poor.

[0030] The angles of the wing-shaped blades 101 on the wing-shaped blade diffuser 1 are matched with the impeller of the centrifugal compressor. By limiting the position, size, and number of the wing-shaped blades 101, while the efficiency of the gas passing through the wing-shaped blade diffuser 1 is improved, it is ensured that the passing gas flow rate is not restricted, and the centrifugal compressor can maintain a relatively wide operating condition. Such as Figure 2 、 Figure 3As shown, after the CFD calculation of the present invention, the surge margin is widened by 2.38% compared with the original vaneless diffuser and the conventional multi-vane diffuser, decreasing from the original 722.6 m3 / min to 705.8 m3 / min. At the maximum flow rate point, the outlet total pressure ratio is increased from the original 1.8743 to 1.8945, and when the inlet pressure is 202.97 kPa, the total pressure loss is reduced by 4.1 kPa. The polytropic efficiency of the airfoil diffuser is increased by a maximum of 1.918% compared with the vaneless diffuser.

[0031] As Figure 4 shown, the airfoil vane diffuser 1 is located in the diffuser flow passage of the centrifugal compressor. In the centrifugal compressor of this embodiment, a total of three stages of impellers 6 and the airfoil vane diffuser 1 are provided. Three partitions 9 are provided on the casing 2 of the centrifugal compressor, and the three airfoil vane diffusers 1 are respectively fixed on the partitions 9. The airfoil vanes 101 face the side where the impeller 6 is located, and the impeller 6 is close to the inlet of the flow passage. Gas enters the centrifugal compressor through the air inlet 3, enters the airfoil vane diffuser 1 through the high-speed rotation of the impeller 6, and is diffused. After passing through multiple stages of impellers 6 and the airfoil vane diffuser 1, the gas is finally discharged from the centrifugal compressor through the air outlet 4. The present invention can be applied to the product design and technical solutions in other large-flow engineering application fields such as large-scale air separation fields, propane dehydrogenation product gas, nitric oxide compressors, and multi-axis compressors.

Claims

1. A wing-shaped vane diffuser for a centrifugal compressor, comprising a diffuser ring (102) and N vanes arranged on the diffuser ring (102); characterized in that: The vanes are wing-shaped vanes (101), and the total area occupied by the N wing-shaped vanes (101) on the side of the diffuser ring (102) accounts for 2% - 5% of the side area of the diffuser ring (102) where they are located; The ratio of the inner circle diameter φc of the diffuser ring (102) to the diameter φb of the circle where the center point of the leading edge of the wing-shaped vane (101) is located is 0.8 - 0.9; The ratio of the diameter φa of the circle where the center point of the trailing edge of the wing-shaped vane (101) is located to the outer circle diameter φd of the diffuser ring (102) is 0.7 - 0.8; The sum N*e° of the central angles e° corresponding to the mean camber lines of the N wing-shaped vanes (101) accounts for 44% - 65% of the circular angle of the diffuser ring (102), and N is 7 - 11.

2. A wing-shaped vane diffuser according to claim 1, characterized in that: N is 11.

3. A wing-shaped vane diffuser according to claim 2, characterized in that: The leading edge of the wing-shaped vane (101) is an arc structure, the trailing edge is a pointed structure, and both sides of the sharp angle are straight.

4. A wing-shaped vane diffuser according to claim 1 or 2 or 3, characterized in that: The ratio of the inner circle diameter φc of the diffuser (1) to the diameter φb of the circle where the center point of the leading edge of the wing-shaped vane (101) is located is 0.

845.

5. A wing-shaped vane diffuser according to claim 4, characterized in that: The ratio of the diameter φa of the circle where the center point of the trailing edge of the wing-shaped vane (101) is located to the outer circle diameter φd of the diffuser (1) is 0.7094.

6. A wing-shaped vane diffuser according to claim 5, characterized in that: The sum N*e° of the central angles e° corresponding to the mean camber lines of the N wing-shaped vanes (101) accounts for 44.53% of the entire circular angle.

7. A wing-shaped vane diffuser according to claim 6, characterized in that: The total area occupied by the wing-shaped vanes (101) on the side of the diffuser ring (102) accounts for 4.24% of the side area of the diffuser ring (102) where they are located.

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