An impeller design method for expanding the head range of a centrifugal sludge pump

Abstract

The present invention provides an impeller design method for expanding the head range of a centrifugal mud pump. The design key points include: the flow-through part of the impeller includes a guide cap, blades, a hub, a rear cover plate, and a front cover plate, which is a cantilever closed centrifugal impeller; condition setting; the blade profile equation for restricting each condition; lofting and manufacturing. The mud pump with the series of impellers designed can achieve a head range of 65% - 130% of the rated head, expanding the head range of the mud pump, simplifying the blade design process. The blade profile adopts a logarithmic spiral, which conforms to the movement law of solid particles and reduces impeller wear; for the impeller, only the number of blades needs to be determined, and the corresponding blade profile can be obtained according to the profile equation. Moreover, the outer diameters of the impellers with four different numbers of blades are the same, ensuring the universality of impeller interchangeability and improving the applicability of the dredger at different construction discharge distances by replacing the impeller.

Description

Technical Field

[0001] The present invention relates to the field of hydraulic design of dredging mud pumps, belonging to cross-technical fields such as dredging mud pumps and fluid mechanics. Background Art

[0002] The mud pump is a key device of a dredger. When the length of the mud discharge pipeline (discharge distance) of the dredger changes, it is required that the head of the mud pump be adapted to the pipeline, that is, the head is low under the short discharge distance condition and high under the long discharge distance condition. At present, most of the mud pumps of dredgers are directly driven by diesel engines, and the speed regulation is restricted, and the head regulation range of the mud pump is relatively narrow.

[0003] At present, the head of the mud pump of the dredger is generally about 80m, and the number of blades is 3, which is suitable for construction in silty sand soil. Summary of the Invention

[0004] The problem-solving idea of the present invention: If the head of the mud pump is adjusted by replacing the impeller with different blades, the head matching of the mud pump under different discharge distances can be improved, and the dredging construction efficiency of the dredger can be effectively improved.

[0005] Countermeasure: When constructing in silty sand soil, due to the small solid particle size, by appropriately reducing the passing ability of the impeller, the number of alternative blades is increased to 4-6, and at the same time, the blade wrap angle is appropriately reduced, and the blade profile is designed as a logarithmic spiral profile and the blade profile equation is given. The entire technical solution of the present invention can significantly increase the head of the mud pump and improve the conveying capacity of the dredger at long discharge distances.

[0006] The technical solution to be protected by the present invention is:

[0007] An impeller design method for expanding the head range of a centrifugal mud pump, comprising the following design key points:

[0008] Key point 1: The flow-through part of the impeller includes a guide cap, blades, a hub, a rear cover plate, and a front cover plate (the structure of this part involving the components, positional relationship, and connection relationship all belongs to the prior art), and it is a cantilever closed centrifugal impeller.

[0009] Key point 2, condition setting: The blades are logarithmic spiral blades, the number of blades z is 3, 4, 5, or 6, evenly distributed in a circle, the blade thickness is taken as 60-90mm, the blade outlet width is 40% of the impeller suction diameter, and the maximum sphere diameters passing through the impeller flow channels are 40%, 32%, 27%, and 25% of the impeller suction diameter respectively, and the blade wrap angle is taken as That is, the number of blades 3, 4, 5, 6 corresponds to 160°, 140°, 120°, 100°.

[0010] Key point 3: The blade profile equation restricting the above various conditions is constructed as

[0011]

[0012]

[0013] Among them, r1 is the impeller suction port radius, with the unit of mm; θ is the angle of the blade in the circumferential direction. The starting point of the blade profile inlet is 0°, and the end point is the blade outlet. is the blade wrap angle (for example, not limited, Figure 1 in this case is 140°), and r(θ) is the distance from any point on the profile line to the impeller center, with the unit of mm.

[0014] Key point four, lofting and manufacturing: The final blade is obtained by lofting the profile line onto the front cover plate and the rear cover plate and then thickening it.

[0015] In the method of the present invention, the number of blades z configured for the dredge pump is controlled within four impeller selection ranges of 3, 4, 5, and 6 blades, which broadens the head range of the dredge pump to match different conveying distances and improves the construction discharge distance range of the dredger.

[0016] Significance of the technical solution of the present invention: A method for designing an impeller to expand the head range of a centrifugal dredge pump. The head range of the dredge pump designed with this series of impellers can reach 65%-130% of the rated head, which broadens the head range of the dredge pump, simplifies the blade design process, and the blade profile adopts a logarithmic spiral, which conforms to the movement law of solid particles and reduces impeller wear; for the impeller, only the number of blades needs to be determined, and the corresponding blade profile can be obtained according to the profile equation, and the outer diameters of the impeller blades with four different numbers of blades are the same, ensuring the universality of impeller interchangeability, and improving the applicability of the dredger at different construction discharge distances by replacing the impeller.

[0017] Application of the technical solution of the present invention: The four dredge pump impellers obtained by the above design method are applied to the construction of different discharge distances of the dredger. During implementation, only by replacing the four cantilevered closed centrifugal impellers of the present invention can the head range of the dredge pump be expanded. The inner cavity of the dredge pump consists of the cantilevered closed centrifugal impeller of the present invention and a single-channel pump casing, and both the internal impeller and the external pump casing are cast from high-chromium cast iron.

[0018] The pump shaft is connected to the impeller hub by threads. The impeller suction port has an anti-wear ring, and there is an anti-wear bushing at the suction port. There is an anti-wear lining plate between the impeller and the pump cover.

[0019] The pump casing is supported and fixed by the lining plate and the pump cover. The cross-section of the pump casing flow channel is a fillet rectangle. The width value of the pump casing flow channel is the sum of the width of the impeller flow channel, the thickness values of the front and rear cover plates of the impeller, and the clearance value between the impeller cover plate and the wear-resistant lining plate. The thickness values of the front and rear cover plates of the impeller are taken as 50-60 mm, and the total clearance value between the impeller cover plate and the two-sided wear-resistant lining plates is taken as 5 mm. The inner and outer edges of the pump casing are both spiral lines.

[0020] The impeller blades of the dredge pump of the present invention are designed as logarithmic spiral blades, which conform to the movement law of solid particles, reduce the wear of the impeller; the blade design is simple, expanding the head range of the dredge pump. The impeller of the dredge pump of the present invention can solve the problem of flow regulation of the dredge pump under different discharge distance conditions.

[0021] The dredge pump of the present invention is equipped with four impellers, which are characterized by wear resistance and a wide head range; under different discharge distance conditions, the head of the dredge pump is 65%-130% of the rated head of the dredge pump, improving the construction applicability of the dredger. Description of the Drawings

[0022] Figure 1 It is the axial projection drawing of the impeller and the schematic diagram of the blade profile for the embodiment.

[0023] Figure 2 It is the 3D impeller part drawing of "4 blades" for Embodiment 2.

[0024] Figure 3 It is the coordinate diagram of the blade profiles of the four embodiments in the X-Y plane.

[0025] Figure 4 It is the 3D assembly drawing of the double-shell dredge pump.

[0026] Figure 5 It is the head curve of the clear water performance of the dredge pump with four impellers configured in the embodiment.

[0027] 1 - Guide cap, 2 - Blade, 3 - Hub, 4 - Rear cover plate, 5 - Front cover plate, 6 - Pump casing, 7 - Wear-resistant lining plate, 8 - Large cover, 9 - Front cover, 10 - Impeller, 11 - Wear-resistant ring at the impeller suction port, 12 - Outer shell, 13 - Bearing housing assembly, 14 - Pump shaft, 15 - Bearing seat. Detailed Embodiments

[0028] The technical solutions provided by the present application will be further described below in conjunction with specific embodiments and their accompanying drawings. In combination with the following description, the advantages and features of the present application will become clearer.

[0029] It should be noted that the embodiments of the present application have good implementability and are not any form of limitation to the present application. The technical features described in the embodiments of the present application or the combination of technical features should not be considered isolated, and they can be combined with each other to achieve better technical effects. The scope of the preferred implementation manner of the present application may also include other implementations, and this should be understood by those skilled in the art to which the embodiments of the present application belong.

[0030] Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies, methods, and devices shall be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific values should be construed as merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values.

[0031] The drawings of this application are all in a very simplified form and use non-precise scales, solely for the purpose of conveniently and clearly assisting in explaining the purpose of the embodiments of this application, and are not intended to limit the conditions under which this application can be implemented. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects that this application can produce and the purposes that can be achieved, should fall within the scope covered by the technical content disclosed in this application. And the same reference numerals appearing in the drawings of this application represent the same features or components, which can be applied to different embodiments.

[0032] Under the framework of the technical solution of the present invention, four embodiments are given: Embodiment 1, Embodiment 2, Embodiment 3, and Embodiment 4, corresponding to the number of blades z = 3, z = 4, z = 5, and z = 6 respectively. According to Equation (2), the corresponding blade included angles are obtained. Take 160°, 140°, 120°, and 100°.

[0033] Figure 1 As shown, the axial projection of the impeller passage and the blade profile, the suction diameter D1 of the impeller is 1000 mm; according to Equation (1), when When That is, the outer diameter of the impeller D2 is 2.6 times that of D1, that is, D2 is 2600 mm; the outlet width B2 of the impeller passage is 40% of the suction diameter D1 of the impeller, that is, the outlet width B2 of the impeller passage is 400 mm; the blade profile coordinates are calculated according to Equation (1) as shown in the following table. After the blade is lofted from the blade profile r(θ) to the front and rear covers, it is thickened by 70 mm in the direction of the outer edge of the impeller.

[0034]

[0035] Figure 2 As shown, the flow-through part of the impeller is surrounded by an impeller guide cap 1, blades 2, a hub 3, a rear cover 4, and a front cover 5, and the above five parts are integrally cast. The impeller is a closed impeller. To show the blades, Figure 2 The front cover is hidden in the left figure. The blade 2 is a logarithmic spiral blade. In Embodiment 2, the number of blades z is 4, and the maximum sphere diameter passing through the impeller passage corresponds to 32% of the suction diameter of the impeller.

[0036] In Embodiment 1, Embodiment 3, and Embodiment 4, the number of blades z is 3, 5, and 6 respectively, and the maximum sphere diameters passing through the flow channels are 40%, 27%, and 25% respectively.

[0037] Figure 3 As shown, the plane coordinate diagrams (unit: m) of the profiles of the impellers in the four embodiments, with the coordinate (0, 0) being the center of the impeller.

[0038] Figure 4 As shown, the pump shaft 14 is connected to the impeller 10 through trapezoidal threads, the impeller 10 is connected to the wear-resistant ring at the impeller suction port 11 through hexagon socket head cap screws. The impeller 10 is located in the cavity jointly formed by the pump casing 6 and the wear-resistant lining plate 7. The pump casing 6 is fixed to the outer shell 12 through bolts. The cavity between the pump casing 6 and the outer shell 12 is filled with high-pressure water to balance the pressure in the mud pump flow channel. There is a wear-resistant lining plate 7 between the impeller 10 and the front cover 9 and the outer shell 12. The wear-resistant lining plate 7 is connected to the front cover 9 and the outer shell 12 through bolts. The front cover 9 is connected to the large cover 8 through bolts, and the large cover 8 is connected to the outer shell 12 through bolts. The pump shaft 14 is located inside the bearing housing 13, and the bearing housing 13 is fixed to the bearing seat 15, and the bearing seat 15 is connected to the outer shell 7 through bolts. The bearing seat 15 and the outer shell 12 are fixed to the ship's deck through bolts.

[0039] The width value of the pump casing flow channel is the sum of the width of the impeller flow channel, the thickness values of the front and rear covers of the impeller, and the clearance values between the impeller cover and the wear-resistant lining plate. The thickness values of the front and rear covers of the impeller are taken as 60 mm, and the total clearance value between the front and rear covers of the impeller and the wear-resistant lining plates on both sides is taken as 5 mm. That is, the width value of the pump casing flow channel is taken as 525 mm.

[0040] Figure 5 As shown, through numerical simulation and simulation, the performance curves of the mud pumps in the four embodiments of the present invention are obtained. The rated flow is 16000 m 3 / h, and the head of the "3-blade", "4-blade", "5-blade", and "6-blade" impellers are 80 m, 100 m, 120 m, and 130 m respectively. Through numerical simulation prediction, at a rotational speed of 320 rpm, the head of the "4-blade" impeller at 100% rotational speed is 100 m, which is the rated head. The mud pump heads of the four impellers designed according to the present invention reach 65% - 130% of the rated head within the rated flow range, expanding the mud pump head range.

[0041] In the field, for the adjustment of the head range of centrifugal mud pumps, the common methods mainly include cutting the impeller, reducing the diesel engine speed, etc., and the common methods can only reduce the head; as is well known in the field, they can usually change the head range by 80% - 100%. The four interchangeable impellers in the embodiments of the present invention can achieve a head adjustment range of 65% - 130%, greatly expanding the construction discharge distance range of the dredger, which is rare in the field.

[0042] The above description is only a description of the preferred embodiments of the present application and does not limit the scope of the present application in any way. Any change or modification made by any person skilled in the art according to the technical content disclosed above shall be regarded as an equivalent effective embodiment and fall within the scope of protection of the technical solution of the present application.

Claims

1. A method for designing an impeller to expand the head range of a centrifugal sludge pump, characterized in that, It includes the following design points: Point 1: The flow-through part of the impeller includes a fairing, blades, a hub, a rear cover plate, and a front cover plate, and it is a cantilever closed centrifugal impeller; Point 2, condition setting: The blade is a logarithmic spiral blade, and there are four types of blade numbers z, which are evenly distributed in the circumferential direction. The outlet width of the blade is 40% of the impeller suction diameter, and the blade wrap angle is taken as φ = 20(11 - z); Point 3: The blade profile equation that restricts the above various conditions is constructed as （1） （2） Among them, r 1 is the impeller suction radius, in mm; θ is the angle of the blade in the circumferential direction. The inlet of the blade profile starts from 0°, and the outlet of the blade is the end point φ , φ is the blade wrap angle, r ( θ ) are the distances from any point on the profile line to the impeller center, in mm; Point 4, lofting and manufacturing: The final blade is obtained by lofting the profile to the front cover plate and the rear cover plate and then thickening it.

2. The impeller design method for expanding the head range of a centrifugal sludge pump according to claim 1, characterized in that The blade thickness is taken as 60 - 90 mm.

3. The impeller design method for expanding the head range of a centrifugal sludge pump as claimed in claim 1, wherein When the number of blades is 3, 4, 5, and 6, the maximum sphere diameters passing through the impeller flow channels correspond to 40%, 32%, 27%, and 25% of the impeller suction diameter respectively.

4. The impeller design method for expanding the head range of a centrifugal sludge pump according to claim 1, characterized in that, The number of blades 3, 4, 5, 6 corresponds to φ 160°, 140°, 120°, 100°.

5. For the impeller design method for expanding the head range of a centrifugal dredge pump as described in claim 1, the four dredge pump impellers obtained are applied to dredging operations with different discharge distances.

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