RU2138690C1 - Self-priming centrifugal pump - Google Patents

Abstract

FIELD: mechanical engineering; pumps. SUBSTANCE: self-priming centrifugal pump has impeller 4, guide vane assembly 7, housing 1, pressure branch pipe 2 and suction branch pipe 3. Guide vane assembly 7, connected with housing 1 and suction branch pipe 3, is made in form of ring 8 with cover disk 9 to separate space of impeller 4 from pump pressure space 12. Pressure and suction branch pipes 2, 3, respectively, are arranged on housing 1 higher than impeller 4. Lower area of pressure space 12 is connected by channels 13 with space 10 formed by radial clearance between outer diameter of impeller 4 and inner diameter of ring 8 of guide vane assembly 7. Separating ring 17 is installed axially symmetrically between guide vane assembly 7 and housing 1. This ring separates part of lower area of pressure space 12 to which channels 13 are connected. Local radial clearance expansion zones between inner diameter of ring 8 and outer diameter of impeller 4 are made on inner surface of ring 8 of guide vane assembly 7 between transferred medium let out channels. Such design of pump improves conditions of air intake and building of liquid-air mixture by impeller, at suction only, by use of fixed members if simple design which do not required special control. EFFECT: enhanced reliability and improved performance characteristics of pump. 3 cl, 4 dwg

Description

 The invention relates to the field of mechanical engineering, namely to pump engineering, to the class of centrifugal impeller pumps.

 Centrifugal pumps are widely used because of their high efficiency, simplicity of design, low manufacturing cost compared to other classes of pumps. The only drawback of centrifugal pumps is that they do not have the property of self-priming. To start the centrifugal pump, it is necessary to completely fill the suction line and the internal cavity of the pump with pumped liquid. They are not able to remove air from the suction line, which leads to a breakdown in the pump when air plugs form in it and the pump cannot be resumed. However, when using special devices, centrifugal pumps gain self-priming ability, are designated as centrifugal self-priming pumps (hereinafter referred to as CSP) and are successfully used in areas where only reciprocating, rotary and vortex pumps were used.

CSN according to the principle of work is divided into three types:
1. CSN having an additional suction capacity.

 2. CSP with an additional volumetric self-priming device.

 3. SPC recirculation type.

 One centrifugal pump belongs to type 1 SPF, which includes an additional tank installed on the suction line, filled with the pumped medium, the volume of which exceeds the volume of the suction line.

 The disadvantages of such a pump are the direct dependence of the volume of the additional capacity on the length of the suction line, its dimensions exceed the dimensions of the pump itself, the need for a large amount of pumped medium for the initial filling of this capacity (see Gryanko L.P., Papira A.N. Vane pumps. - L .: Engineering, 1975).

CSNs with additional self-priming devices are known, which in addition to the main impeller include: an additional vacuum pump wheel mounted on one shaft with an impeller, working chambers of the vacuum pump, additional seal assemblies on the pump shaft, auxiliary pipelines, pump switching mechanisms from the suction mode to the normal pumping mode (see Gryanko L.P., Papira A.N. Vane pumps. - L .: Mashinostroyenie, 1975, 6MV ^* 2 pumps, NTSVS produced by the Moscow Pump Plant).

The disadvantages of these pumps are:
1. Deterioration in the reliability of the central cylinder due to the presence of a complex additional self-priming device compared to a simple centrifugal pump.

 2. The deterioration of the energy indicators of the central cylinder due to the presence of an additional impeller.

 3. Deterioration of the operating conditions due to the presence of a mechanism for switching the operation modes of the DSP.

 4. Decrease in the TsSN resource due to the short-term operation of the additional impeller, because it works in conditions of local cavitation and practically without the presence of end gaps with body parts.

 5. The increase in weight and size characteristics of the pump.

 6. The narrowing of the scope, because The impeller of the vacuum pump only reliably works in clean environments.

 Known recycle type SPPs containing an impeller, a spiral outlet, a housing and a recirculation channel that connects the pressure cavity of the pump housing to the suction pipe in the area of the impeller inlet, a device that restricts spurious overflows along the recirculation channel inside the pump during normal pumping operation (see Aut. St. USSR N 1267053, class F 04 D 9/02 of 04/04/84; Aut. St. N 1629615, class F 04 D 9/02 of 01/27/89).

The disadvantages of these pumps are:
1. The presence of parasitic overflows inside the pump from the pressure cavity of the pump to the inlet of the impeller during normal pumping operation leads to an overestimated power consumption and lower pump efficiency.

 2. Devices or automatic mechanisms that limit parasitic overflows inside the pump during normal pumping operation complicate the design and reduce the reliability of the central cylinder.

 3. The housing of the central cylinder, covering the housing of the spiral outlet from the impeller, increases its overall dimensions.

 Known TSS type 50-3TS7.1-20 brand G2-OPD production PO "Vostok" Biysk, containing a closed impeller, an annular tap, a housing with a pressure pipe, nozzle, gas separator housing and a suction pipe. The nozzle is located freely inside the discharge pipe, the lower end covers the impeller with a small gap, and the upper one extends into the gas separator body (see Catalog, “Machines, Equipment, Devices and Automation Means for Processing Agro-Industrial Complexes”, Volume 1, Part 3, Dairy Industry , AgroNIITEIIITO, 1990; Krasnokutsky Yu.V., Panchenko Yu.B. Machines and equipment for whole milk products .-- M .: Rosagropromizdat, 1990; ed. St. USSR N 1084490, F 04 D 9/02 of 12.29.82) .

The disadvantages of the pump are:
1. The presence of a nozzle in the discharge pipe violates the geometry of the discharge of the pumped fluid from the impeller, which leads to a decrease in the hydraulic and overall efficiency of the pump.

 2. Relatively low to 5 m Art. water self-priming height.

 3. The presence of cavitation at the entrance to the nozzle increases its wear, increases the load on the pump rotor and reduces its resource.

 4. The need to equip the pump with a device that regulates the position of the nozzle to eliminate cavitation processes.

 5. An additional gas separator housing and a suction pipe raised to its level increase the weight and size characteristics of the pump.

 The objective of the invention is the creation of a central injection pump with high self-priming efficiency, not inferior to a simple centrifugal pump in the normal mode of pumping in efficiency, weight and dimensions, ease of maintenance, resource and practically the cost of manufacturing costs, as well as devoid of the disadvantages mentioned above that are characteristic of existing existing central injection pumps.

 The solution to this problem is achieved by the fact that in a centrifugal pump containing an impeller, a guide apparatus, a housing with a pressure and suction nozzles connected to the housing and a suction nozzle, the guide apparatus is made in the form of a ring with a cover disk and separates the impeller cavity from the pressure cavity of the pump housing , the pressure and suction nozzles are located on the pump casing above the impeller, while the lower region of the pressure cavity of the pump casing is connected by channels with a cavity formed by a radial azor between the outer diameter of the impeller and the inner diameter of the ring of the guide apparatus.

 Between the inner walls of the pump casing and the outer diameter of the ring of the guide vane, a spacer ring is mounted axisymmetrically to the latter, and the connecting channels are connected to a part of the lower region of the pump casing located between the inner walls of the pump casing and the outer diameter of the spacer ring.

 On the inner surface of the ring of the guide vane between the channels of the discharge of the pumped medium, local zones of expansion of the radial clearance are made between the inner diameter of the ring of the vane and the outer diameter of the impeller.

The invention is illustrated by drawings, which depict:
in FIG. 1 is a general view of the proposed SPP;
in FIG. 2 is a section AA in FIG. 1;
in FIG. 3 - a general view of the centralized testing center of horizontal design;
in FIG. 4 is a general view of a vertical composite cylinder with a top arrangement of an electric motor.

 CSN contains a housing 1 (Fig. 1) with a pressure head 2 and a suction pipe 3. The impeller 4 is open without a cover disk (shown on the left) or closed with a cover disk 5 (shown on the right) connected to an electric motor 6. At the outlet of the impeller 4 a guide apparatus 7 is installed, made in the form of a ring 8 with a cover disk 9, which is connected to the suction pipe 3 and the pump housing 1 and separates the cavity 10 of the impeller 4 and the suction cavity 11 from the pressure cavity 12 of the pump housing 1. The cavity 12 is connected to the cavity by 10 channels 13. On the pump housing 1 there is a filler neck 14 with a cover 15 and a drain hole 16. In the pump housing 1 there is a spacer ring 17 mounted axisymmetrically to the ring 8 of the guiding apparatus 7. On the inner surface of the ring 8 of the guiding apparatus 7 ( Fig. 2) between the channels 18 of the discharge of the pumped medium, local expansion zones 19 are made.

 The present invention can be applied in horizontal pumps (figure 3) and vertical with an electric motor on top (figure 4).

 CSP works as follows.

 Before the first start-up, the pump housing 1, through the filler neck 14, is filled with the pumped medium or water until the impeller 4 is completely immersed in it. The suction pipe (not shown in the drawings) is hermetically connected to the suction pipe 3 and the lower end is immersed in the pumped liquid, the level of which can be below the impeller 4 to 8 m, and the pumped medium is not filled. When starting, the pump automatically starts to work in the "suction" mode. On the periphery of the impeller 4 in the cavity 10, a liquid ring is formed, which is a water seal and separates the suction cavity 11 from the pressure cavity 12 of the pump. The stability of the formation of the liquid ring is ensured by the fact that the liquid level in the cavity 12, which is poured into the pump before starting, is installed above the impeller, and the cavities 10 and 12 are connected by channels 13. The impeller 4, interacting with air from the suction pipe 3, mixes it with water liquid ring and throws through the channels 18 of the discharge of the pumped medium into the pressure cavity 12 of the pump. In the cavity 12, air, as a lighter fraction, rises up and is freely removed through the discharge pipe 2. Thus, there is a constant suction of air from the suction pipe 3 and, when sufficient vacuum is reached in it, the pumped liquid is sucked. All internal cavities of the pump are filled with liquid and the pump automatically switches to the normal mode of pumping a simple centrifugal pump. Spurious flow inside the pump through the channels 13 from the cavity 12 to the cavity 10 does not occur, because no pressure differential is formed between these cavities.

 To increase the stability of the formation of a liquid ring, the channels 13 in the housing 1 are located in its lower part, separated from the guide apparatus 7 by a separation ring 17, in which the liquid layers are the most dense and do not contain air.

 To enhance the efficiency of air capture by the impeller from the suction cavity 11 and to create a liquid-air mixture on the inner surface of the ring 8 of the guiding apparatus 7, local expansion zones 19 are made that provide fluid turbulence in the inter-blade space inside the impeller 4, which contributes to their air capture, and the channels 13 can be brought directly into these expansion zones.

 When the pump is stopped, to prevent liquid suction from the working cavities of the pump, the cover 15 of the filler neck 14 opens with a liquid column in the suction pipe. This ensures that a sufficient amount of liquid is retained in the pump and it is ready for subsequent starts. The liquid is drained from the pump through the drain hole 16.

Thus, the present invention solves the problems due to the use of simple in design, fixed elements that do not require control and do not reduce the technical parameters of the central cylinder in comparison with a simple centrifugal pump. Also, the present invention allows to create a SPP that meets all the requirements for this type of pumps, namely:
1. Provides high self-priming efficiency up to 8 m of water. pillar.

 2. Provides a low cavitation reserve of up to 1 m of water. pillar.

 3. Does not require special management. The transition from the suction mode to the normal pumping operation mode and vice versa occurs automatically.

 4. Automatically resumes flow when air enters the suction pipe and pump cavities.

 5. When stopped, it ensures readiness for operation in the suction mode during subsequent starts.

 6. Does not limit the scope of centrifugal pumps.

Claims (3)

 1. A centrifugal self-priming pump containing an impeller, a guiding apparatus, a housing with a pressure and suction nozzles, characterized in that the guiding apparatus connected to the housing and the suction nozzle is made in the form of a ring with a cover disk and separates the impeller cavity from the pressure cavity of the pump housing, discharge and suction nozzles are located on the pump casing above the impeller, while the lower region of the pressure cavity of the pump casing is connected by channels to the cavity formed by the radial clearance m forward impeller outside diameter and the inside diameter of guide vane ring.  2. The pump according to claim 1, characterized in that between the inner walls of the pump casing and the outer diameter of the ring of the guide vane is mounted axisymmetrically to the last dividing ring, and the connecting channels are connected to the part of the lower region of the pressure cavity of the pump casing located between the inner walls of the pump casing and outer diameter of the spacer ring.  3. The pump according to claim 1 or 2, characterized in that on the inner surface of the ring of the guide vane between the channels of the pumped-over medium, local zones of expansion of the radial clearance are made between the inner diameter of the rings of the vane and the outer diameter of the impeller.

Images