Self-suction liquid storage tank for self-degassing centrifugal pump

Abstract

The invention relates to the technical field of self-suction liquid storage tanks for centrifugal pumps, in particular to a self-suction liquid storage tank for a self-degassing centrifugal pump, which comprises a tank body and a communicating pipe group. A first through hole is formed in the upper wall face of the tank body, and a second through hole is formed in the lower wall face of the tank body. The communicating pipe set comprises a suction pipe, an output pipe and a drainage pipe, the suction pipe and the output pipe are both located outside the tank body, at least part of the drainage pipe is located in the tank body, one end of the suction pipe can suck liquid to be sucked through an external pipeline, the other end of the suction pipe is in butt joint communication with one end of the drainage pipe at the first through hole, and one end of the output pipe is communicated with a liquid inlet of the centrifugal pump. The other end of the drainage tube is connected to the outer wall surface of the lower part of the tank body, the output tube is communicated with the second through hole, the other end of the drainage tube extends into the output tube and is spaced from the output tube, and an air guide hole is formed in the tube wall of the upper part of the drainage tube. According to the self-absorption liquid storage tank for the self-degassing centrifugal pump, gas in the tank body can be automatically exhausted to restore the liquid level height, the operation reliability is improved, and the cost and the energy consumption are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of self-priming liquid storage tanks for centrifugal pumps, and particularly relates to a self-deaerating self-priming liquid storage tank for centrifugal pumps. BACKGROUND

[0002] As a rotating machine, a centrifugal pump relies on the kinetic energy of rotation to convert into pressure energy at the pump outlet to increase the pressure of the low-pressure liquid at the pump inlet and achieve delivery. If there is no liquid at the pump inlet in the initial state, no significant pressure difference will be generated, and the liquid cannot be pumped, such as when the pumped liquid is located below the pump. To achieve pumping, the liquid below must be guided into the centrifugal pump to rely on the work done by the impeller on the liquid to achieve continuous pumping. Currently used methods include: using a vacuum pumping method to guide liquid, using a water ring vacuum pump for pumping, using a jet pump to guide and pump liquid, using a submersible pump for pumping, using a self-priming pump with a gas-liquid mixing and discharge mechanism in the pump cavity, etc. Some of the above methods have high equipment investment and low reliability, some have low pumping efficiency, some have low service life, some have poor self-priming effect, low self-priming height, and long time. In addition, there is another way, which is to add a self-priming liquid storage tank at the pump inlet.

[0003] As shown in Figure 1 On the basis of a conventional centrifugal pump (including a seal-free magnetic drive centrifugal pump), a self-priming liquid storage tank 100' is added at the pump inlet. Like the aforementioned internal or external mixing self-priming pump, the tank body 1' is pre-filled with liquid, and the pump cavity is filled with liquid, and the centrifugal pump reaches the operating condition. After the pump is started and runs, the liquid in the self-priming liquid storage tank 100' is gradually pumped out, and the space left by the falling liquid level allows air in the suction pipe 2' to enter the self-priming liquid storage tank 100'. As the volume of air expands gradually with the decrease of the liquid level in the self-priming liquid storage tank 100', the gas pressure in the tank gradually decreases, and the atmospheric pressure gradually pushes the underground liquid up through the suction pipe 2'. When the liquid enters the tank body 1', it can supplement the liquid flowing from the tank body 1' to the pump cavity, achieve a balance between the inflow and outflow of the tank body 1', and the liquid level remains basically unchanged, achieving continuous pumping of the centrifugal pump.

[0004] The advantages of this scheme are that it can reduce equipment investment cost, improve pumping efficiency compared to other design methods, and has a faster response after starting. There is no gas-liquid mixing operation period in the conventional self-priming pump, and the medium is output after starting. However, the current self-priming liquid storage tank 100' also has some disadvantages. To prevent the liquid in the tank body 1' from flowing back due to siphoning during shutdown, and to initially prime, the suction pipe 2' of the tank body 1' and the output pipe 3' connected to the pump are disconnected, the pipe opening of the suction pipe 2' is located at a high position in the tank body 1', and the liquid falls from a high place into the tank body 1', like a waterfall, and collides with the liquid surface in the tank body 1', splashing everywhere. In this process, the following problems occur:

[0005] (1) Energy loss: the liquid has a certain flow rate when flowing out of the pipe opening of the suction pipe 2', has kinetic energy, and falls from the pipe opening to the liquid surface to impact the liquid, and the kinetic energy is lost; at the same time, the potential energy of the part of the pipe opening flowing out relative to the liquid level in the tank 1' is also consumed; due to the sudden expansion of the pipe opening of the suction pipe 2' into the peripheral cavity when flowing out of the pipe opening, and the sudden change in the flow area from the large space in the tank 1' to the output pipe 3', the local resistance coefficient is large, which also causes large local flow resistance loss. Therefore, compared with the suction pipe of a conventional centrifugal pump, the self-suction liquid storage tank 100' also produces a head loss of about 1m, and if the head of the centrifugal pump is 30m, the loss of the self-suction system is more than 3%, which is much lower than the loss of a special self-priming pump, but the efficiency is still lower than that of a conventional centrifugal pump without self-priming.

[0006] (2) The gas in the self-suction liquid storage tank 100' increases more and more, and needs to be supplemented with liquid from time to time. If the pumped liquid is sewage, there is a certain amount of dissolved air, and if it is a chemical mixed waste liquid, the mixed liquid often contains low-boiling components. The self-suction liquid storage tank 100' located at the inlet of the pump is in a negative pressure state when the tank 1' is in operation, and part of the air in the pumped liquid will be precipitated, and the low-boiling components in it will be partially vaporized, especially during the process of the liquid falling from the pipe opening of the suction pipe 2' to the liquid surface, due to the lack of constraints and the impact of the liquid surface, which further aggravates the precipitation of the gas phase. The precipitated gas cannot be dissolved into the pumped liquid again, resulting in an increase in the volume of gas in the tank 1', which makes the liquid level lower and lower, and eventually leads to the liquid in the tank 1' being basically pumped out and unable to continue pumping. At this time, the liquid needs to be supplemented again through the filling port of the tank 1' to continue the self-suction pumping function. The result of this is that the operation personnel need to be sent to the site frequently to supplement the liquid, increasing the consumption of manpower and liquid materials; if the liquid in the self-suction liquid storage tank 100' is always decreasing and is not discovered in time, it will eventually be pumped out, causing the centrifugal pump to run dry and causing serious equipment failure and major losses. In order to avoid being pumped out, additional online monitoring of the liquid level of the self-suction liquid storage tank 100' is required, which not only increases the investment in equipment, but also requires personnel to be sent to the site at irregular intervals to supplement the liquid. SUMMARY

[0007] The purpose of the present application is to provide a self-deaerating centrifugal pump self-suction liquid storage tank that can automatically discharge the gas in the tank body without relying on external equipment, restore the liquid level height, avoid the consumption of manpower and materials caused by frequent liquid supplementation, improve the operation reliability, prevent the centrifugal pump from being damaged due to being pumped out, and also reduce the equipment investment cost, improve the pumping efficiency, and reduce the energy loss.

[0008] To achieve this purpose, the present application adopts the following technical solutions:

[0009] Provided is a self-priming liquid storage tank for a self-deaerating centrifugal pump, comprising:

[0010] a tank body, a first through hole being formed in an upper wall surface of the tank body, and a second through hole being formed in a lower wall surface of the tank body;

[0011] a communication pipe set, comprising a suction pipe, an output pipe and a drainage pipe, the suction pipe and the output pipe being located outside the tank body, and the drainage pipe being at least partially located inside the tank body, one end of the suction pipe being capable of sucking a liquid to be pumped through an external pipeline, the other end of the suction pipe being in butt joint communication with one end of the drainage pipe at the first through hole, one end of the output pipe being in communication with a liquid inlet of a centrifugal pump, the other end of the output pipe being connected to an outer wall surface of a lower portion of the tank body, the output pipe being in communication with the second through hole, the other end of the drainage pipe being extended into the output pipe and being arranged in a spaced-apart manner with the output pipe, and a gas guide hole being formed in a pipe wall of an upper portion of the drainage pipe.

[0012] Optionally, the first through hole is located on a top surface of the tank body.

[0013] Optionally, the second through hole is located on a bottom surface of the tank body.

[0014] Optionally, the drainage pipe is arranged vertically.

[0015] Optionally, the gas guide hole comprises a first opening and a second opening, the first opening being located on an inner wall of the drainage pipe, and the second opening being located on an outer wall of the drainage pipe, a vertical height of the first opening being lower than a vertical height of the second opening.

[0016] Optionally, an included angle between a penetration direction of the gas guide hole and a vertical direction is in a range of 20°-50°.

[0017] Optionally, the gas guide hole is provided with N, a ratio of a sum of cross-sectional areas of the N gas guide holes to a cross-sectional area of the drainage pipe at a position where the gas guide hole is located is in a range of 0.05-0.1, and N is a positive integer.

[0018] Optionally, N is greater than or equal to 2, and the N gas guide holes are arranged in a spaced-apart manner along a circumferential direction of the drainage pipe.

[0019] Optionally, a liquid flow rate in the drainage pipe at the position where the gas guide hole is located is in a range of 1 m / s-4 m / s.

[0020] Optionally, the drainage pipe comprises a necked-down section, an inner diameter of the necked-down section being smaller than an inner diameter of the drainage pipe at other positions, and an opening of the gas guide hole at the inner wall of the drainage pipe is located in the necked-down section.

[0021] Optionally, the ratio of the minimum cross-sectional area of the annular space between the outer wall of the drainage tube and the inner wall of the output tube to the cross-sectional area of the inner cavity of the drainage tube ranges from 0.5 to 2.

[0022] Optionally, the output tube comprises a tapered tube segment and a second segment, the large-diameter end of the tapered tube segment is connected to the tank body, the small-diameter end of the tapered tube segment is connected to the second segment, and the second segment is connected to the centrifugal pump.

[0023] The present application has the following advantages:

[0024] The present application provides a self-priming liquid storage tank for a self-deaerating centrifugal pump, comprising a tank body and a communication pipe group. The upper wall surface of the tank body is provided with a first through hole, and the lower wall surface of the tank body is provided with a second through hole. The communication pipe group comprises a suction pipe, an output pipe and a drainage pipe. The suction pipe and the output pipe are both located outside the tank body, and the drainage pipe is at least partially located inside the tank body. One end of the suction pipe can suck the liquid to be pumped through an external pipeline, and the other end of the suction pipe is connected to one end of the drainage pipe at the first through hole. One end of the output pipe is connected to the liquid inlet of the centrifugal pump, and the other end is connected to the outer wall surface of the lower part of the tank body. The output pipe is connected to the second through hole, and the other end of the drainage pipe extends into the output pipe and is spaced apart from the output pipe. The pipe wall of the upper part of the drainage pipe is provided with a gas guide hole.

[0025] 1. After the self-priming liquid storage tank for the self-deaerating centrifugal pump is initially filled with liquid, the centrifugal pump is started and runs. The liquid in the storage tank is sucked through the gap between the drainage pipe and the output pipe. As the volume of the liquid in the tank body decreases, the gas pressure in the tank body gradually decreases. The gas pressure at the liquid to be pumped pushes the liquid to be pumped up through the suction pipe. When the liquid enters the tank body, it directly flows to the output pipe through the drainage pipe hole and is pumped out. The output pipe no longer pumps liquid from the tank, so the liquid level in the tank remains basically unchanged, realizing the continuous pumping of the centrifugal pump. During operation, when the sucked liquid passes through the gas guide hole at the top of the drainage pipe, according to the Bernoulli equation for fluid relative motion, the pressure of the liquid at this position is lower than the static gas pressure in the tank outside the drainage pipe at the same position due to the effect of flow velocity. A small amount of gas at the gas-liquid interface in the gas guide hole of the drainage pipe is sucked into the liquid in the drainage pipe and is carried away with the liquid. The liquid is directly sent into the impeller of the centrifugal pump through the output pipe and is pumped out. After a period of operation, the gas in the upper part of the tank body is gradually pumped out, and the liquid reoccupies the entire tank body. The liquid level automatically returns to the initial state. In this way, except for the initial empty state of the tank body, liquid needs to be filled before self-priming. Subsequent start-up operation does not require liquid to be added to the tank body again. This can not only avoid the consumption of manpower and materials caused by liquid replenishment, but also prevent damage to the centrifugal pump caused by failure to replenish liquid in time, greatly improving the operation reliability of the self-priming system.

[0026] 2、The self-deaerating type centrifugal pump self-suction liquid storage tank can improve the liquid level in the tank body, reduce the residual air volume, and according to the gas state P1V1=P2V2, when the same vacuum degree (convertible into suction height) is generated, the required liquid volume is proportional to the air volume, the air volume is small, and the volume of the tank body can be reduced; even if the tank body is not reduced, the amount of liquid in the tank is small when self-suction is completed, a liquid surface with a high position can be left to ensure the reliability of self-suction.

[0027] 3、The liquid pumped up directly enters the output pipe through the drainage pipe, and there is no waterfall type emission process when the liquid falls from a high position, the gas and volatile components carried in the pumped liquid are pumped out together with the liquid, the situation that the gas gradually occupies the space in the tank body is avoided, and the liquid level is also avoided from continuously decreasing due to the increase of the gas, and finally the emptying phenomenon occurs.

[0028] 4、The liquid flows orderly and stably through the drainage pipe, and the along-the-way loss of the conventional liquid pipeline is similar, the local loss, kinetic energy and high potential energy loss caused by the liquid falling from a high position are avoided, the flow loss of the liquid flowing through the tank body is greatly reduced, the energy consumption is greatly reduced, the overall efficiency of the self-suction system is close to that of the conventional centrifugal pump, and energy saving and emission reduction are beneficial. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a structure schematic view of the self-suction liquid storage tank in the prior art;

[0030] Figure 2 is a structure schematic view of the self-suction liquid storage tank for the self-deaerating type centrifugal pump provided by the embodiment of the application;

[0031] Figure 3 is a structure schematic view of the necked section of the drainage pipe provided by the embodiment of the application.

[0032] Figure 1 in which:

[0033] 1', tank body; 2', suction pipe; 3', output pipe; 100', self-suction liquid storage tank;

[0034] Figures 2-3 in which:

[0035] 1, tank body; 11, top surface; 12, bottom surface; 13, liquid supplementing port; 2, suction pipe;

[0036] 3, output pipe; 31, straight pipe section; 32, tapered pipe section; 33, second section;

[0037] 4, drainage pipe; 41, gas guide hole; 411, first opening; 412, second opening; 42, necked section;

[0038] 5, annular space;

[0039] 100. Self-priming liquid storage tank for self-degassing centrifugal pumps. Detailed Implementation

[0040] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings, not all of them.

[0041] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0042] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0043] Centrifugal pumps, as rotating machinery, pump liquids by converting the kinetic energy of rotation into pressure energy at the pump outlet, thus increasing the pressure of the low-pressure liquid at the pump inlet for delivery. If there is no liquid at the pump inlet initially, no significant pressure difference will be generated, and liquid cannot be pumped, especially if the liquid is located at the bottom of the pump. To achieve pumping, the liquid at the bottom must be guided into the centrifugal pump, where the impeller performs work on the liquid to achieve continuous pumping. Currently used methods include:

[0044] (1) Vacuum method: This method relies on external equipment to create a vacuum for liquid priming, such as using a water ring vacuum pump or a jet pump. This method requires additional equipment investment, resulting in high equipment costs. Furthermore, its overall reliability is low due to the reliability of the vacuum pump system.

[0045] (2) Put the pumping part below the liquid level: such as using submersible pump or submersible pump to pump. The submersible pump of long shaft is easy to be damaged due to rotation and bearing part, has low reliability, and is inconvenient to maintain, and tends to be eliminated in petrochemical industry; the motor of submersible pump is submerged in the liquid level, which is affected by corrosion, electrical insulation, mechanical seal and other factors, and has low reliability.

[0046] (3) Special self-priming pump with gas-liquid mixed exhaust: special self-priming centrifugal pump with gas-liquid mixing and exhaust mechanism in the pump cavity, etc. Such self-priming pump has low efficiency, high energy consumption, long self-priming time, and cannot respond to the demand of process device in time, and leads to low service life of seal due to long time of no flushing and cooling operation.

[0047] In addition, there is another way, which is to add a self-priming liquid storage tank at the pump inlet.

[0048] As shown in Figure 1 , on the basis of conventional centrifugal pump (including non-sealed magnetic drive centrifugal pump), a self-priming liquid storage tank 100' is added at the pump inlet, and like the aforementioned internal mixing type or external mixing type self-priming pump, the tank body 1' is filled with liquid in advance, and at the same time, the pump cavity is filled with liquid, and the centrifugal pump reaches the operating condition. After starting the pump, the liquid in the self-priming liquid storage tank 100' is gradually pumped out, the space left by the falling liquid level allows the air in the suction pipe 2' to enter the self-priming liquid storage tank 100', and as the liquid level in the self-priming liquid storage tank 100' falls, the air volume gradually expands, the pressure in the tank gradually decreases, and the atmospheric pressure pushes the underground liquid up through the suction pipe 2'; when the liquid enters the tank body 1', it can compensate for the liquid flowing out of the tank body 1' to the pump cavity, achieve the balance of liquid flow in and out of the tank body 1', and keep the liquid level basically unchanged, realizing the continuous pumping of the centrifugal pump.

[0049] The advantages of this scheme are that it can reduce the equipment investment cost, improve the pumping efficiency compared with the above-mentioned other design methods, and has faster start-up response. There is no gas-liquid mixing operation period of conventional self-priming pump, and the medium is output after starting. However, the current self-priming liquid storage tank 100' also has some disadvantages in use. In order to prevent the liquid in the tank body 1' from flowing back due to siphoning during shutdown, and to pump the liquid in the tank body 1' first during initial self-priming, the suction pipe 2' of the tank body 1' and the output pipe 3' connected with the pump are disconnected, the pipe opening of the suction pipe 2' is located at a high position of the tank body 1', and the liquid falls from the high position to the tank body 1', like a waterfall, and collides with the liquid surface in the tank body 1', splashing everywhere. The following problems are caused in this process:

[0050] (1) Energy loss: the liquid has a certain flow rate when flowing out of the pipe orifice of the suction pipe 2', and has kinetic energy. When the liquid falls from the pipe orifice to the liquid surface and collides with the liquid, the kinetic energy is lost. At the same time, the potential energy of the part of the liquid flowing out of the pipe orifice relative to the liquid surface in the tank 1' is also consumed. Because the pipe orifice suddenly expands into the surrounding cavity when the liquid flows out of the pipe orifice of the suction pipe 2', and the flow area suddenly changes when the liquid flows from the large space in the tank 1' to the output pipe 3', the local resistance coefficient is large, which also causes large local flow resistance loss. Therefore, compared with the suction pipe of a conventional centrifugal pump, the self-suction liquid storage tank 100' will also produce a head loss of about 1m. If the head of the centrifugal pump is 30m, the loss of the self-suction system is more than 3%. Although the loss is much lower than that of a special self-priming pump, the efficiency is still lower than that of a conventional centrifugal pump without self-priming.

[0051] (2) The gas in the self-suction liquid storage tank 100' increases more and more, and needs to be supplemented with liquid from time to time. If the pumped liquid is sewage, there is a certain amount of dissolved air. If it is a chemical mixed waste liquid, the mixed liquid often contains low-boiling components. When the self-suction liquid storage tank 100' at the pump inlet is running, the inner cavity of the tank 1' is in a negative pressure state. Part of the air contained in the pumped liquid will be precipitated, and the low-boiling components in it will be partially vaporized. Especially in the process of liquid falling from the pipe orifice of the suction pipe 2' to the liquid surface, the liquid is unconstrained and collides with the liquid surface, which further aggravates the precipitation of the gas phase. The precipitated gas cannot be dissolved into the pumped liquid again, resulting in an increase in the volume of gas in the tank 1', which makes the liquid level lower and lower, and eventually leads to the liquid in the tank 1' being basically pumped out and unable to continue pumping. At this time, the liquid needs to be supplemented again through the filling port of the tank 1' to continue the self-suction pumping function. As a result, it is necessary to frequently send operators to the site to operate and supplement the liquid, which increases the consumption of manpower and liquid materials. If the liquid in the self-suction liquid storage tank 100' is always decreasing and is not discovered in time, it will eventually be pumped out, which will cause the centrifugal pump to run dry and cause serious equipment failure and heavy losses. In order to avoid pumping out, it is necessary to additionally increase the online monitoring of the liquid level of the self-suction liquid storage tank 100', which not only increases the investment in equipment, but also requires personnel to go to the site to supplement the liquid at irregular intervals.

[0052] To solve the above problems, the embodiment provides a self-deaerating centrifugal pump self-suction liquid storage tank 100, which can automatically discharge the gas in the tank 1, restore the liquid level, avoid frequent liquid supplementing, reduce the consumption of manpower and materials, improve the operation reliability, prevent the centrifugal pump from being damaged due to pumping out, and also reduce the equipment investment cost, improve the pumping efficiency, and reduce the energy loss.

[0053] As Figure 2As shown, the self-priming liquid storage tank 100 for the self-deaerating centrifugal pump of the embodiment comprises a tank body 1 and a communication pipe group. The upper wall surface of the tank body 1 is provided with a first through hole, and the lower wall surface of the tank body 1 is provided with a second through hole. The communication pipe group comprises a suction pipe 2, an output pipe 3 and a drainage pipe 4. The suction pipe 2 and the output pipe 3 are both located outside the tank body 1, and the drainage pipe 4 is at least partially located inside the tank body 1. One end of the suction pipe 2 can suck the liquid to be pumped through an external pipeline, and the other end of the suction pipe 2 is connected to one end of the drainage pipe 4 at the first through hole. One end of the output pipe 3 is connected to the liquid inlet of the centrifugal pump, and the other end of the output pipe 3 is connected to the outer wall surface of the lower part of the tank body 1. The output pipe 3 is connected to the second through hole, and the other end of the drainage pipe 4 is inserted into the output pipe 3 and is spaced apart from the output pipe 3. The pipe wall of the upper part of the drainage pipe 4 is provided with a gas guide hole 41.

[0054] The self-priming liquid storage tank 100 for the self-deaerating centrifugal pump has at least the following advantages:

[0055] 1. After the self-priming liquid storage tank 100 is initially filled with liquid, the centrifugal pump is started to run. The liquid in the storage tank is sucked through the gap between the drainage pipe 4 and the output pipe 3. As the volume of the liquid in the tank body 1 decreases, the gas pressure in the tank body 1 gradually decreases. The gas pressure at the liquid to be pumped pushes the liquid to be pumped up through the suction pipe 2. Until the liquid enters the tank body 1 and directly flows to the output pipe 3 through the drainage pipe 4 hole for pumping out, the output pipe 3 no longer pumps the liquid from the tank, so that the liquid level in the tank remains basically unchanged, realizing the continuous pumping of the centrifugal pump. During operation, when the sucked liquid passes through the gas guide hole 41 at the top of the drainage pipe 4, according to the Bernoulli equation of fluid relative motion, due to the effect of flow velocity, the pressure of the liquid at this position is lower than the static gas pressure in the tank outside the drainage pipe 4 at the same position. A small amount of gas at the gas-liquid interface in the gas guide hole 41 of the drainage pipe 4 is sucked into the liquid in the drainage pipe 4 and is taken away together with the liquid. The liquid is directly sent into the impeller of the centrifugal pump through the output pipe 3 and is pumped out. After a period of operation, the gas in the upper part of the tank body 1 is gradually pumped out, and the liquid reoccupies the entire tank body 1, and the liquid level automatically returns to the initial state. In this way, except for the initial empty state of the tank body 1, the tank body 1 needs to be filled with liquid before self-priming, and the tank body 1 does not need to be filled with liquid again when the centrifugal pump is started again. This can not only avoid the consumption of manpower and materials caused by liquid supplementing, but also prevent the damage of the centrifugal pump caused by not timely liquid supplementing, greatly improving the operation reliability of the self-priming system.

[0056] 2. The self-priming storage tank 100 used in this self-degassing centrifugal pump can raise the liquid level in the tank 1 and reduce the residual air volume. According to the gas state P1V1=P2V2, when the same vacuum degree (which can be converted into suction height) is generated, the required liquid volume is proportional to the air volume. If the air volume is smaller, the volume of the tank 1 can be reduced. Even if the tank 1 is not reduced, the amount of liquid pumped out when self-priming is completed is less, and a higher liquid level can be maintained to ensure the reliability of self-priming.

[0057] 3. The pumped liquid enters the output pipe 3 directly through the drainage pipe 4, eliminating the waterfall-like dispersion process that occurs when liquid falls from a high position. The gas and volatile components entrained in the pumped liquid are pumped out along with the liquid, preventing the gas escaping from the pumped liquid from gradually occupying the inner cavity of the tank 1. This also prevents the liquid level from continuously dropping due to the increase of gas, which could eventually lead to cavitation.

[0058] 4. The liquid flows in an orderly and stable manner through the diversion pipe 4, which is similar to the friction loss of conventional liquid pipelines. This avoids the local loss, kinetic energy loss and high potential energy loss caused by the liquid falling from a high position. The flow loss of the liquid through the tank 1 is greatly reduced, which greatly reduces energy consumption. The overall efficiency of the self-priming system is close to that of a conventional centrifugal pump, which is conducive to energy conservation and emission reduction.

[0059] Optionally, the first through hole is located on the top surface 11 of the tank 1, that is, the junction of the suction pipe 2 and the drainage pipe 4 is located at the top of the tank 1. Figure 1 As shown, in the prior art, the first through hole of the self-priming storage tank 100' is located on the upper side wall of the tank body 1'. During initial storage, the tank body 1' cannot be completely filled; the liquid level is only filled to the center of the suction pipe 2' (when there is a baffle on the side), leaving residual air above the center. This affects the utilization rate of the tank body 1', and the residual air reduces the maximum negative pressure generated during self-priming, thus lowering the self-priming height. Therefore, in this embodiment, the self-priming storage tank 100 for the self-degassing centrifugal pump has the first through hole located on the top surface 11 of the tank body 1. This effectively eliminates residual air in the tank body 1, ensuring that the tank body 1 can be filled with liquid, increasing the self-priming height, and correspondingly reducing the volume of the tank body 1.

[0060] Optionally, the second through hole is located on the bottom surface 12 of the tank body 1. For example... Figure 1As shown, the second through hole of the self-priming liquid storage tank 100' in the prior art is arranged on the side wall of the lower part of the tank body 1', when the liquid level in the tank body 1' is lower than the upper edge of the output pipe 3', a large amount of air will be sent into the centrifugal pump, the centrifugal pump does not allow too much air to directly enter the impeller, which will cause damage to the impeller. The second through hole of the self-priming liquid storage tank 100 of the self-deaerating centrifugal pump in the embodiment is arranged on the bottom surface 12, which reduces the minimum liquid level allowed in the tank body 1 when the centrifugal pump is running, reduces the demand for the volume of the tank body 1, and improves the utilization rate of the tank body 1.

[0061] Optionally, the drainage pipe 4 is vertically arranged, when the height of the tank body 1 is constant, the vertical arrangement of the drainage pipe 4 can shorten the length of the drainage pipe 4 to the maximum extent, and can reduce the resistance of the pipe wall of the drainage pipe 4 to the flow of the liquid to the maximum extent. Optionally, the first through hole and the second through hole are arranged in the axial direction of the tank body 1, that is, the axial direction of the drainage pipe 4 coincides with the axial direction of the tank body 1.

[0062] Optionally, as shown, Figure 3 The air guide hole 41 includes a first opening 411 and a second opening 412, the first opening 411 is located on the inner wall of the drainage pipe 4, and the second opening 412 is located on the outer wall of the drainage pipe 4, the vertical height of the first opening 411 is lower than that of the second opening 412. The second opening 412 is arranged at a higher height, which is conducive to the suction of air from a high place into the drainage pipe 4, that is, the liquid level can be as high as possible. The air guide hole 41 extends upwardly and obliquely, so that when the air enters the drainage pipe 4 from the upper part of the inner cavity of the drainage pipe 4 through the air guide hole 41, the flow direction of the gas tends to be close to the flow direction of the liquid in the drainage pipe 4, which helps the gas to be quickly carried by the liquid vertically downward into the output pipe 3 and then into the centrifugal pump.

[0063] Optionally, the included angle between the penetration direction of the air guide hole 41 and the vertical direction is in the range of 20°-50°, that is, Figure 3 The included angle between the penetration direction of the air guide hole 41 and the vertical direction is in the range of 20°-50°. When the included angle is less than 20°, the axial direction of the air guide hole 41 is too close to the vertical direction, which is not conducive to processing, and the length of the air guide hole 41 will also increase accordingly, which is not conducive to the suction of the gas into the drainage pipe 4. When the included angle is greater than 50°, the axial direction of the air guide hole 41 is too close to the horizontal direction, and the movement direction of the gas changes too much when it enters the drainage pipe 4, which is not conducive to the suction and mixing of the gas. Therefore, in order to make the air guide hole 41 easy to process and conducive to the suction of the gas into the drainage pipe 4, the included angle between the penetration direction of the air guide hole 41 and the vertical direction is in the range of 20°-50°.

[0064] Optionally, the inner diameter of the drainage pipe 4 is related to the rated flow of the centrifugal pump, in the embodiment, the inner diameter of the drainage pipe 4 is designed according to the flow velocity of 1 meter per second-4 meters per second.

[0065] Optionally, the gas guiding holes 41 are provided in N number, N being a positive integer. Optionally, N is greater than or equal to 2, and the N gas guiding holes 41 are spaced apart along the circumference of the drainage tube 4. Optionally, in this embodiment, N ranges from 2 to 12, and the N gas guiding holes 41 are evenly spaced apart along the circumference of the drainage tube 4. Optionally, in this embodiment, N is 6, and of course in other embodiments, N can also be 1, 2, 3, 4, 5, 7, 8, 9 or a larger positive integer.

[0066] Optionally, the ratio of the sum of the cross-sectional areas of the N gas guiding holes 41 to the cross-sectional area of the drainage tube 4 at the location of the gas guiding holes 41 ranges from 0.05 to 0.1. When the ratio is less than 0.05, the sum of the cross-sectional areas of the gas guiding holes 41 is too small, which is not conducive to the smooth intake of gas into the drainage tube 4, and the speed of gas intake is also too slow. When the ratio is greater than 0.1, the gas-liquid ratio of the gas-liquid mixture in the drainage tube 4 exceeds the range that the centrifugal pump can adapt, which is not conducive to prolonging the service life of the centrifugal pump.

[0067] Optionally, the flow rate of the liquid in the drainage tube 4 at the location of the gas guiding holes 41 ranges from 1 m / s to 4 m / s. When the flow rate of the liquid in the drainage tube 4 at the location of the gas guiding holes 41 is less than 1 m / s, the pressure in the drainage tube 4 is not low enough, and the speed at which the gas outside the drainage tube 4 is sucked into the drainage tube 4 through the gas guiding holes 41 is very slow, and the degassing effect is poor. When the flow rate of the liquid in the drainage tube 4 at the location of the gas guiding holes 41 is greater than 4 m / s, the flow resistance is large and the energy consumption is too large, which is not conducive to energy saving and emission reduction.

[0068] Optionally, in this embodiment, the drainage tube 4 includes a necked-down section 42, the inner diameter of the necked-down section 42 is smaller than the inner diameter of the rest of the drainage tube 4, and the flow rate of the liquid flowing through the necked-down section 42 will increase, and the openings of the gas guiding holes 41 on the inner wall of the drainage tube 4 are located in the necked-down section 42. The provision of the necked-down section 42 is conducive to increasing the gas pressure difference at the two openings of the gas guiding holes 41, and ensuring that the gas outside the drainage tube 4 can be quickly sucked into the drainage tube 4.

[0069] Of course, in other embodiments, when the flow rate of the liquid is already large enough to quickly suck the gas outside the drainage tube 4 into the drainage tube 4, the necked-down section 42 can also not be provided.

[0070] Optionally, the ratio of the minimum cross-sectional area of the annular space 5 between the outer wall of the drainage pipe 4 and the inner wall of the output pipe 3 to the cross-sectional area of the inner cavity of the drainage pipe 4 is in the range of 0.5-2. During the initial self-suction process, the liquid outside the drainage pipe 4 in the tank 1 enters the output pipe 3 from the annular space 5. If the ratio of the minimum cross-sectional area of the annular space 5 to the cross-sectional area of the inner cavity of the drainage pipe 4 is less than 0.5, the annular space 5 is too small, the resistance is too large, and it is not conducive to the liquid outside the drainage pipe 4 in the tank 1 to quickly enter the output pipe 3, the self-suction time is prolonged, and at this time the centrifugal pump is prone to cavitation and emptying. If the ratio of the minimum cross-sectional area of the annular space 5 to the cross-sectional area of the inner cavity of the drainage pipe 4 is greater than 2, the drainage pipe 4 flows out of the liquid into a larger area of space during normal pumping, increasing the flow resistance, which is not conducive to energy saving.

[0071] Optionally, the output pipe 3 includes a tapered pipe section 32 and a second section 33, the large-diameter end of the tapered pipe section 32 is connected to the tank 1, the small-diameter end of the tapered pipe section 32 is connected to the second section 33, and the second section 33 is connected to the centrifugal pump.

[0072] Optionally, the drainage pipe 4 is partially inserted into the tapered pipe section 32, and the minimum pipe diameter of the tapered pipe section 32 is 1 to 3 grades larger than the pipe diameter specification of the drainage pipe 4. The provision of the tapered pipe section 32 can gradually reduce the cross-sectional area of the annular space 5, which is conducive to reducing the resistance of the liquid flowing in the annular space 5, and further reducing the dissipation of flow energy.

[0073] Optionally, since the centrifugal pump is located beside the tank 1, the second section 33 is in the form of a bent pipe to facilitate connection and communication with the liquid inlet of the centrifugal pump. Optionally, the output pipe 3 further includes a straight pipe section 31, and the second section 33 is connected to the centrifugal pump through the straight pipe section 31.

[0074] After the self-deaerated centrifugal pump with self-suction liquid storage tank 100 is assembled and connected, liquid is first injected into the tank 1 through the liquid supplementing port 13 at the top surface 11 of the tank 1 until the tank 1 is filled, and then the liquid supplementing port 13 is closed. At this time, the liquid cavity of the centrifugal pump is also filled due to the lower liquid level of the centrifugal pump than that of the tank 1. The centrifugal pump is started, and the centrifugal pump generates hydraulic power after operation. The liquid in the tank 1 is continuously pumped out by the centrifugal pump. At this time, the liquid level in the tank 1 is continuously lowered, and the cavity is continuously enlarged. According to the principle that the PV value of the gas is basically unchanged, the increase in the volume of the gas causes the pressure in the tank 1 to continuously decrease. The liquid to be pumped under atmospheric pressure continuously rises through the suction pipe 2 and flows to the tank 1. When the liquid level in the tank 1 is lowered to a certain extent, i.e., the cavity is enlarged to a certain extent, the liquid to be pumped flows into the tank 1, supplements the initial filled liquid pumped away by the centrifugal pump, and the tank 1 reaches a liquid in-out balance. The liquid to be pumped is directly pumped away by the centrifugal pump through the drainage pipe 4, and thereafter the centrifugal pump is in a normal pumping state.

[0075] As the upper part of the inner cavity of the tank 1 is gas at this time, when the liquid continuously flows through the necked section 42 of the drainage pipe 4, a certain amount of gas will continuously mix at the gas-liquid interface depending on the flow rate, and the gas will be continuously sucked away with the liquid by the centrifugal pump. In this way, as the gas in the tank 1 gradually decreases, the liquid level will slowly rise until the gas at the air guide hole 41 is completely sucked away, and the liquid level in the tank 1 will return to the initial state, and the centrifugal pump does not need to be refilled with liquid when it is continuously operated or started next time.

[0076] When the centrifugal pump is stopped, if the centrifugal pump is not provided with a check valve, due to the height difference between the tank 1 and the liquid to be pumped, the liquid will flow back to the tank with the liquid to be pumped which is lower than the tank 1. If the liquid in the centrifugal pump is completely drained, air will enter the tank 1 through the centrifugal pump. At this time, the gas enters the drainage pipe 4 through the air guide hole 41, breaks the siphon effect, and the liquid level in the tank 1 will stop falling. The liquid level is at the position of the air guide hole 41, and the tank 1 is basically in a full tank state, and there is no need to refill the liquid for the next self-suction, which prepares for the next self-suction operation.

[0077] The self-deaerating centrifugal pump self-suction liquid storage tank 100 of the embodiment does not need to rely on external equipment and control instrument system to guarantee, and can have the functions of self-recovery of liquid level and anti-backflow, which essentially guarantees the reliable operation of the centrifugal pump system which needs to be self-suction, and has the advantages of small self-suction operation loss, which is beneficial to energy saving and emission reduction.

[0078] Obviously, the above embodiments of the application are only examples for clearly illustrating the application, and are not intended to limit the implementation modes of the application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the implementation modes are not enumerated. Any modification, equivalent replacement and improvement made within the spirit and principle of the application should be included in the protection scope of the claims of the application.

Claims

1. A self-priming liquid storage tank for a self-degassing centrifugal pump, characterized in that, include: The tank (1) has a first through hole on its upper wall and a second through hole on its lower wall. The connecting pipe assembly includes a suction pipe (2), an output pipe (3), and a drainage pipe (4). The suction pipe (2) and the output pipe (3) are both located outside the tank body (1). The drainage pipe (4) is at least partially located inside the tank body (1). One end of the suction pipe (2) can suck in the liquid to be pumped through an external pipe. The other end of the suction pipe (2) is connected to one end of the drainage pipe (4) at the first through hole. One end of the output pipe (3) is connected to the inlet of the centrifugal pump, and the other end is connected to the lower outer wall of the tank body (1). The output pipe (3) is connected to the second through hole. The other end of the drainage pipe (4) extends into the output pipe (3) and is spaced apart from the output pipe (3). The upper part of the drainage pipe (4) has an air guide hole (41).

2. The self-priming liquid storage tank for a self-degassing centrifugal pump according to claim 1, characterized in that, The first through hole is located on the top surface (11) of the tank body (1); And / or, the second through hole is located on the bottom surface (12) of the tank body (1).

3. The self-priming liquid storage tank for a self-degassing centrifugal pump according to claim 1, characterized in that, The drainage tube (4) is set vertically.

4. The self-priming liquid storage tank for a self-degassing centrifugal pump according to claim 3, characterized in that, The air guide hole (41) includes a first opening (411) and a second opening (412). The first opening (411) is located on the inner wall of the drainage tube (4), and the second opening (412) is located on the outer wall of the drainage tube (4). The vertical height of the first opening (411) is lower than the vertical height of the second opening (412).

5. The self-priming liquid storage tank for a self-degassing centrifugal pump according to claim 4, characterized in that, The angle between the through-hole (41) and the vertical direction is in the range of 20°-50°.

6. The self-priming liquid storage tank for a self-degassing centrifugal pump according to any one of claims 1-5, characterized in that, The air guide hole (41) is provided with N, and the ratio of the sum of the cross-sectional areas of the N air guide holes (41) to the cross-sectional area of ​​the drainage pipe (4) at the location of the air guide hole (41) is in the range of 0.05-0.1, where N is a positive integer.

7. The self-priming liquid storage tank for a self-degassing centrifugal pump according to claim 6, characterized in that, N is greater than or equal to 2, and N air guide holes (41) are opened at circumferential intervals along the drainage pipe (4).

8. The self-priming liquid storage tank for a self-degassing centrifugal pump according to any one of claims 1-5, characterized in that, The range of liquid flow velocity in the drainage pipe (4) at the location of the air guide hole (41) is 1m / s-4m / s; And / or, the drainage tube (4) includes a constricted section (42) with an inner diameter smaller than the inner diameter of the rest of the drainage tube (4), and the opening of the air guide hole (41) at the inner wall of the drainage tube (4) is located in the constricted section (42).

9. The self-priming liquid storage tank for a self-degassing centrifugal pump according to any one of claims 1-5, characterized in that, The ratio of the minimum cross-sectional area of ​​the annular space (5) between the outer wall of the drainage tube (4) and the inner wall of the output tube (3) to the cross-sectional area of ​​the inner cavity of the drainage tube (4) is in the range of 0.5-2.

10. The self-priming liquid storage tank for a self-degassing centrifugal pump according to any one of claims 1-5, characterized in that, The output pipe (3) includes a conical section (32) and a second section (33). The large-diameter end of the conical section (32) is connected to the tank (1), and the small-diameter end of the conical section (32) is connected to the second section (33). The second section (33) is connected to the centrifugal pump.

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