WO2024146369A1 - Negative-pressure balance tank - Google Patents

Abstract

The present application relates to a negative-pressure balance tank. The negative-pressure balance tank comprises a tank body; a feed pipe and a discharging pipe are provided on the tank body, a discharging pump being provided on the discharging pipe or a pipe connected to the discharging pipe; a negative-pressure interface connected to a negative-pressure source is provided on the tank body, a first valve part being provided at the negative-pressure interface or a pipe connected to the negative-pressure interface; when a material is fed into the tank body via the feed pipe, the first valve part is switched on; when the material in the tank body is discharged via the discharging pipe, the discharging pump is started and the first valve part is switched off.

Description

Negative pressure balance tank

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No. 202320028155.0 filed in China on January 3, 2023, the entire contents of which are incorporated herein by reference.

Technical Field

The present application relates to the field of material processing, and in particular to a negative pressure balance tank.

Background technique

In the process of liquid material processing, the balance tank is a necessary equipment to balance the system pressure and flow. At the same time, the balance tank also has the function of exhausting bubbles and providing the initial pressure head for the subsequent pump, so as to ensure the continuous operation of the pump and avoid cavitation. However, when conveying materials that are easy to foam, such as skim milk and soy milk, a large amount of foam often occurs inside the balance tank. The foam will float above the surface of the liquid in the balance tank, and as the production process continues, the amount of foam will gradually increase. As the production time increases, the microorganisms in the foam will gradually increase, and eventually contaminate the entire system of the balance tank, resulting in the acidity and pH of the subsequent products not meeting the product quality requirements. At the same time, the production time will be shortened, which will have an adverse effect on product quality, production efficiency and production cost.

There is currently no effective solution to the problem in the related art that foam easily accumulates in the balancing tank, which has an adverse effect on product quality, production efficiency and production costs.

Therefore, the inventor, relying on many years of experience and practice in related industries, proposes a negative pressure balance tank to overcome the defects of related technologies.

Summary of the invention

The purpose of the present application is to provide a negative pressure balancing tank, which can minimize the foaming effect of the material by controlling the feeding method and feeding flow rate of the balancing tank, and at the same time keep the balancing tank in a slightly negative pressure environment at all times, and can eliminate the bubbles after the foam is generated.

The purpose of this application can be achieved by the following scheme:

The present application provides a negative pressure balance tank, which includes a tank body, on which a feed pipe and a discharge pipe are arranged, and a discharge pump is arranged on the discharge pipe or on a pipeline connected to the discharge pipe;

The tank body is provided with a negative pressure interface connected to a negative pressure source, and the negative pressure interface or the negative pressure interface connected to the negative pressure interface A first valve member is arranged on the pipeline;

When the material is fed into the tank through the feed pipe, the first valve member is turned on;

When the material in the tank is delivered through the discharge pipe, the discharge pump is started and the first valve member is closed.

In a preferred embodiment of the present application, a feed port is provided in the lower middle portion of the tank body, one end of the feed pipe is connected to the feed port, the axial direction of the feed pipe is tangent to the outer wall of the tank body, and the axis of the feed pipe gradually tilts upward from close to the tank body to away from the tank body.

In a preferred embodiment of the present application, the angle between the axis of the feed pipe and the horizontal plane is 5° to 45°.

In a preferred embodiment of the present application, a bottom cover is provided at the bottom of the tank body, and the bottom cover is an inverted cone structure that gradually tapers from top to bottom. A discharge port is provided at the central contraction position of the bottom cover, and one end of the discharge pipe is connected to the discharge port.

In a preferred embodiment of the present application, a guide plate is provided inside the tank body and above the discharge port, and a plurality of guide holes are opened on the guide plate. The material passes through the plurality of guide holes and is delivered from the discharge port.

In a preferred embodiment of the present application, the angle between the bottom cover and the horizontal plane is 15° to 60°.

In a preferred embodiment of the present application, a top cover is provided on the top of the tank body, and the top cover is a conical structure that tapers from bottom to top, and the angle between the top cover and the horizontal plane is 10° to 30°.

In a preferred embodiment of the present application, a first pressure detection element is disposed on the top of the tank body, and/or a second pressure detection element is disposed on the bottom of the tank body.

In a preferred embodiment of the present application, a first liquid level detection element and a second pressure detection element are respectively provided on the top and the bottom of the tank body.

In a preferred embodiment of the present application, a manhole is provided on the tank body, a manhole cover is provided at the manhole, and an electronic lock is provided on the manhole cover.

In a preferred embodiment of the present application, at least one spray device is disposed inside the tank body, and a second valve member is disposed on the spray device or on a pipeline connected to the spray device.

In a preferred embodiment of the present application, the discharge pipe and the spray device are respectively connected to the first pipeline and the second pipeline, the first pipeline is connected to the second pipeline, and the second valve member is located on the discharge pipe or on the first pipeline or on the second pipeline or on the spray device.

In a preferred embodiment of the present application, the feed pipe and the spray device are respectively connected to the third pipeline and the fourth pipeline, the third pipeline is connected to the fourth pipeline, a third valve component is arranged on the feed pipe or on the third pipeline, and the second valve component is located on the fourth pipeline or on the spray device.

As described above, the characteristics and advantages of the negative pressure balance tank of the present application are: a feed The invention relates to a tank body having a negative pressure source and a discharge pipe, and a negative pressure interface connected to a negative pressure source is provided on the tank body, and a first valve member is provided at the negative pressure interface or on a pipeline connected to the negative pressure interface; when materials are fed into the tank body by the feed pipe, the first valve member is controlled to be in a conducting state to avoid a positive pressure environment in the tank body due to the feeding of materials; when materials in the tank body are fed out by the discharge pipe, the discharge pump is controlled to start while the first valve member is controlled to be in a closed state, so that the tank body is in a closed state, and as the materials are fed out, the interior of the tank body is in a micro-negative pressure environment, and then the bubbles are broken due to the pressure difference between the bubbles and the internal environment of the tank body, so as to achieve the effect of eliminating bubbles. The present application cyclically controls the on-off of the first valve member and the start-stop of the discharge pump, so that a micro-negative pressure environment can always be maintained in the tank body, which can achieve the effect of minimizing the generation of foam in the material, and can eliminate bubbles after the foam is generated.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are only intended to illustrate and explain the present application, and do not limit the scope of the present application.

Figure 1: is a front view of the negative pressure balance tank of this application.

Figure 2: A top view of the negative pressure balance tank of this application.

Figure 3: is one of the structural schematic diagrams of the negative pressure balance tank of this application.

Figure 4: is the second structural schematic diagram of the negative pressure balance tank of this application.

The reference numerals in this application are:
1. Tank body; 101. Feed pipe;
102. Discharge pipe; 103. Spraying device;
104. Manhole; 1041. Electronic lock;
105. bottom cover; 106. top cover;
2. a first valve member; 3. a first pressure detection element;
4. Second pressure detection element; 5. First liquid level detection element;
6. Second liquid level detection element; 7. Drainage plate;
8. Support leg; 9. Second valve member;
10. Discharge pump; 11. Third pipeline;
12. Fifth pipeline; 13. First pipeline;
14. Second pipeline; 15. Fourth pipeline;
16. The third valve component.

Detailed ways

In order to have a clearer understanding of the technical features, purposes and effects of the present application, the specific implementation methods of the present application are now described with reference to the accompanying drawings.

As shown in Figures 1 to 4, the present application provides a negative pressure balance tank, which includes a tank body 1, a feed pipe 101 and a discharge pipe 102 are provided on the tank body 1, and a discharge pump 10 is provided on the discharge pipe 102 or on a pipeline connected to the discharge pipe 102; a negative pressure interface (not shown) connected to a negative pressure source (which may be a negative pressure tank) is provided on the tank body 1, and a first valve component 2 is provided at the negative pressure interface or on the pipeline connected to the negative pressure interface; when material (liquid material) is fed into the tank body 1 by the feed pipe 101, the first valve component 2 is turned on; when the material in the tank body 1 is fed out by the discharge pipe 102, the discharge pump 10 is started and the first valve component 2 is turned off.

In the present application, a feed pipe 101 and a discharge pipe 102 are arranged on the tank body 1 of the negative pressure balance tank, and a negative pressure interface connected to the negative pressure source is arranged on the tank body 1, and a first valve component 2 is arranged at the negative pressure interface or on the pipeline connected to the negative pressure interface; when material is fed into the tank body 1 through the feed pipe 101, the first valve component 2 is controlled to be in a conducting state to avoid a positive pressure environment in the tank body 1 due to the feeding of the material; when the material in the tank body 1 is discharged through the discharge pipe 102, the discharge pump 10 is controlled to start and the first valve component 2 is controlled to be in a closed state, so that the tank body 1 is in a closed state, and as the material is discharged, the interior of the tank body 1 is in a slightly negative pressure environment, and then the bubbles are broken due to the pressure difference between the inside of the bubbles and the internal environment of the tank body 1, thereby achieving the effect of eliminating the bubbles. The present application cyclically controls the on and off of the first valve component 2 and the start and stop of the discharge pump 10, so that a slightly negative pressure environment can always be maintained in the tank body 1, which can minimize the effect of reducing the foam generated by the material, and can eliminate the bubbles after the foam is generated, effectively solving the problem of easy accumulation of foam in the balance tank, and can achieve the effect of improving product quality, increasing production efficiency, and reducing production costs.

In an optional embodiment of the present application, as shown in Figures 1, 3 and 4, a feed port (not shown) is provided in the middle and lower portion of the tank body 1, one end of the feed pipe 101 is connected to the feed port, and the other end of the feed pipe 101 extends away from the tank body 1, and the axial direction of the feed pipe 101 is tangent to the outer wall of the tank body 1, and the axis of the feed pipe 101 gradually tilts upward from close to the tank body 1 to away from the tank body 1. After the material enters the interior of the tank body 1, the material can flow in a spiral downward direction along the inner wall of the tank body 1. Therefore, the material fed through the feed pipe 101 can enter the material (liquid) stored in the tank body 1 as soon as possible, reducing the contact between the material fed through the feed pipe 101 and the air in the tank body 1, thereby reducing the generation of foam.

In this embodiment, the angle between the axis of the feed pipe 101 and the horizontal plane is 5° to 45°. Optionally, the angle between the axis of the feed pipe 101 and the horizontal plane is 10°.

Further, the tank body 1 is a cylindrical structure with sealed top and bottom, the diameter of the tank body 1 is smaller than the height of the tank body 1 in the vertical direction, and the distance between the feed port and the bottom of the tank body 1 is 100cm to 350cm. Optionally, the distance between the feed port and the bottom of the tank body 1 is 150mm.

In the present application, the diameter of the feed pipe 101 can be adjusted according to factors such as the characteristics of the material, the degree of gas foam, the turbulence generated by the material entering the tank body 1, and/or the control of microorganisms in the tank body 1, and the specific diameter of the feed pipe 101 is not limited here. During the production process, the flow rate of the material in the feed pipe 101 is controlled in the range of 0.5m/s to 1.5m/s. Optionally, the flow rate of the material in the feed pipe 101 is 1m/s.

Of course, the diameter of the discharge pipe 102 can also be adjusted according to factors such as the characteristics of the material, the degree of gas foam, the turbulence generated by the material entering the tank body 1, and/or the control of microorganisms in the tank body 1. The specific diameter of the discharge pipe 102 is not limited here. During the production process, the flow rate of the material in the discharge pipe 102 is controlled in the range of 0.5m/s to 1.5m/s. Optionally, the flow rate of the material in the discharge pipe 102 is 1m/s.

In an optional embodiment of the present application, as shown in FIG1 , a bottom cover 105 is provided at the bottom of the tank body 1, and the bottom cover 105 is an inverted cone structure that gradually tapers from top to bottom. A discharge port (not shown) is provided at the central contraction position of the bottom cover 105, and one end of the discharge pipe 102 is connected to the discharge port. The structure of the bottom cover 105 can ensure that the material is discharged before the foam, and can prevent the generation of foam.

In this embodiment, the angle α between the bottom cover 105 and the horizontal plane is 15° to 60°. Optionally, the angle α between the bottom cover 105 and the horizontal plane is 45°. Since a certain liquid level needs to be maintained inside the negative pressure balance tank during operation, a low liquid level is prone to air intake and material interruption, and continuous production cannot be achieved; a high liquid level is prone to causing the material located in the tank body 1 and located at the upper part to stay in the tank body 1 for too long. If the angle α between the bottom cover 105 and the horizontal plane is small, a higher liquid level will be caused in the tank body 1; if the bottom cover 105 is a flat bottom structure arranged in the horizontal direction, the tank body 1 has a larger volume to buffer the materials with the same liquid level height. Therefore, it is necessary to take into account the liquid level height and the volume of the tank body 1 to ensure the balance between the two as much as possible. Therefore, the angle α between the bottom cover 105 and the horizontal plane is set to 45°, which can simultaneously meet the effects of liquid level control and material priority delivery. During the process of the foam entering the tank body 1, the material enters the tank body 1 along the tangent direction of the inner wall of the tank body 1 and then gradually rotates and moves downward toward the bottom of the bottom cover 105. Since the material entering the tank body 1 has an initial velocity (assumed to be v), according to the centripetal force formula _Fdirection = mv2/r, when the initial velocity of the material is the same, the radius of rotation of the material at the bottom cover 105 gradually decreases, and the centripetal force exerted on the material at the bottom cover 105 is greater than the centripetal force exerted on the straight cylindrical position on the inner wall of the tank body 1 (the centripetal force at the cone is greater than that at the cylinder). Since the gas moves from a higher pressure position to a lower pressure position, the foam moves from bottom to top along the inner wall of the bottom cover 105. During the upward movement of the foam, it will be broken due to the gradual decrease in the pressure in the tank body 1, thereby achieving the effect of preventing the generation of bubbles and foam.

In an optional embodiment of the present application, as shown in FIG1 , a guide plate 7 is provided inside the tank body 1 and above the discharge port. The guide plate 7 is provided with a plurality of guide holes. The material passes through the plurality of guide holes and is discharged from the discharge port. The setting of the guide plate 7 can prevent the material from directly entering the discharge port, avoid the generation of eddy currents at the discharge port, and ensure the smooth discharge of the material. The guide holes can be provided in the middle of the guide plate 7 or evenly distributed on the guide plate 7 to ensure that the material passes through the guide plate 7. After passing the guide plate 7, it can smoothly enter the discharge port.

Furthermore, the guide plate 7 may be, but is not limited to, an inverted "concave"-shaped structure, and the guide plate 7 may be made of, but is not limited to, a stainless steel plate with a thickness of 2 mm to 4 mm.

In an optional embodiment of the present application, as shown in FIG1 , a top cover 106 is provided on the top of the tank body 1, and the top cover 106 is a tapered structure that tapers from bottom to top, and the angle β between the top cover 106 and the horizontal plane is 10° to 30°. Optionally, the angle β between the top cover 106 and the horizontal plane is 15°.

In an optional embodiment of the present application, as shown in Figures 1, 3 and 4, a first pressure detection element 3 is provided on the top of the tank body 1, and the pressure inside the tank body 1 is detected in real time by the first pressure detection element 3 to ensure a micro-negative pressure environment inside the tank body 1.

Furthermore, as shown in Figures 1, 3 and 4, a second pressure detection element 4 is also provided at the bottom of the tank body 1, and the pressure inside the tank body 1 is detected in real time by the second pressure detection element 4. Taking into account the situation that a slightly negative pressure environment may cause a decrease in the accuracy of liquid level detection, the second pressure detection element 4 cooperates with the first pressure detection element 3 to improve the accuracy of detection.

Furthermore, the first pressure detection element 3 and the second pressure detection element 4 may be, but are not limited to, pressure sensors.

In an optional embodiment of the present application, as shown in Figures 1, 3 and 4, a first liquid level detection element 5 is provided on the top of the tank body 1, and a second liquid level detection element 6 is provided on the bottom of the tank body 1. The first liquid level detection element 5 detects a preset high liquid level in the tank body 1, and the second liquid level detection element 6 detects a preset low liquid level in the tank body 1. When the liquid level of the material in the tank body 1 reaches a high liquid level, it is necessary to temporarily stop feeding the material into the tank body 1 to prevent the material from overflowing; when the liquid level of the material in the tank body 1 reaches a low liquid level, it is necessary to control the discharge pump 10 to stop pumping the material to play a protective role.

Furthermore, the first liquid level detection element 5 and the second liquid level detection element 6 can be, but are not limited to, liquid level sensors. Of course, a continuous float level gauge or other liquid level measurement elements can also be used.

In an optional embodiment of the present application, as shown in FIGS. 1 to 4 , a manhole 104 is provided on the top of the tank body 1, a manhole cover is provided at the manhole 104, and an electronic lock 1041 is provided on the manhole cover. When the manhole cover is closed, the tank body 1 is fully sealed, and a slightly negative pressure environment is formed inside the tank body 1. When someone opens the manhole cover manually, the system connected to the electronic lock 1041 will automatically send out an alarm signal and stop the production operation.

In an optional embodiment of the present application, as shown in FIG. 1 , FIG. 3 , and FIG. 4 , a support leg 8 is provided at the bottom of the tank body 1 .

In an optional embodiment of the present application, as shown in Figures 1, 3, and 4, at least one spray device 103 is provided inside the tank body 1, and a second valve component 9 is provided on the spray device 103 or on a pipeline connected to the spray device 103. A cleaning liquid is provided to the spray device 103 through the second valve component 9, so that the interior of the tank body 1 can be cleaned.

In a specific embodiment of the present application, as shown in FIG3 , the feed pipe 101 is connected to the feed device through the third pipeline 11, the negative pressure interface is connected to the negative pressure source through the fifth pipeline 12, the discharge pipe 102 is connected to the first pipeline 13, the spray device 103 is connected to the second pipeline 14, the first pipeline 13 is connected to the second pipeline 14, and the second valve member 9 is located on the discharge pipe 102 or the first pipeline 13 or the second pipeline 14 or the spray device 103. When cleaning the inside of the tank body 1, the discharge pump 10 can be started, and the second valve member 9 can be controlled to be turned on, and the liquid can be sequentially sent to the spray device 103 through the first pipeline 13 and the second pipeline 14, so as to clean the inside of the tank body 1.

In another specific embodiment of the present application, as shown in FIG4 , the feed pipe 101 is connected to the feed device through the third pipeline 11, the negative pressure interface is connected to the negative pressure source through the fifth pipeline 12, the discharge pipe 102 is connected to the first pipeline 13, the spray device 103 is connected to one end of the fourth pipeline 15, and the other end of the fourth pipeline 15 is connected to the third pipeline 11, and a third valve member 16 is provided on the feed pipe 101 or the third pipeline 11, and the second valve member 9 is located on the fourth pipeline 15 or on the spray device 103. When cleaning the interior of the tank body 1, the second valve member 9 can be controlled to be always in the conducting state, and the third valve member 16 can be controlled to be in the off or pulse conducting state, and the liquid can be sent to the spray device 103 through the fourth pipeline 15, so as to clean the interior of the tank body 1. Of course, the second valve member 9 and the third valve member 16 can also be controlled to be conducted in a pulse manner to complete the cleaning operation of the tank body 1.

In the present application, the tank body 1 can be a heat-insulating tank body or a stirring tank body with an agitator arranged inside it. It can be replaced with a tank body with corresponding functions according to different production needs.

In the present application, the tank body 1 and the components that come into contact with the material during the production process are made of food-grade materials. The food-grade materials may be, but are not limited to, 304 and above stainless steel materials, and the sealing materials used in the tank body 1 and other sealing positions may be, but are not limited to, EPDM (ethylene propylene diene monomer rubber), silicone or Teflon, thereby greatly improving the hygiene and safety of the food.

The working process of the negative pressure balance tank of the present application is: when feeding materials into the tank body 1, the first valve component 2 is controlled to be turned on first. Since the tank body 1 is an empty tank in the initial state, the material gradually replenishes the liquid level in the tank body 1 to a medium-high liquid level height (filling approximately 50% to 90% of the space in the tank body 1) after entering the tank body 1. During this process, the air in the tank body 1 is gradually compressed. If the second valve component 9 is not controlled to be turned on, the continuous feeding of materials will cause the interior of the tank body 1 to gradually become a positive pressure, resulting in the loss of the function of the negative pressure balance tank during the production process. After the liquid level inside the tank body 1 reaches the middle-high liquid level, the first valve member 2 is controlled to close, at which time the other valve members (such as the second valve member 9 and the third valve member 16) are all in the off state, and the discharge pump 10 is turned on to deliver the material in the tank body 1 to the system. During the material output process, it is ensured that the liquid level in the tank body 1 is always at the middle-low liquid level (filling about 20% to 50% of the space in the tank body 1). Since the entire system is in a closed state, during the process of the material in the tank body 1 changing from the middle-high liquid level to the middle-low liquid level, the pressure in the tank body 1 gradually forms a micro-negative pressure (the micro-negative pressure is only compared with the ambient pressure outside the tank body 1, and the specific pressure parameters of the micro-negative pressure are not limited). The tank body 1 is filled with a slightly negative pressure environment, so that when bubbles are contained in the foam, the slightly negative pressure environment in the tank body 1 will cause the bubbles to burst, thereby achieving the effect of eliminating the bubbles. However, as the bubbles in the liquid gradually rise to the top of the tank body 1, the pressure in the tank body 1 will gradually approach 0 from negative pressure. At this time, the above operation process needs to be repeated, that is, the first valve member 2 is controlled to be turned on again, and the material is then fed into the tank body 1 to a medium-high liquid level. Then, the first valve member 2 is controlled to be closed and the discharge pump 10 is turned on until the liquid level in the tank body 1 is at a medium-low liquid level again, thereby re-establishing a slightly negative pressure environment in the tank body 1.

The characteristics and advantages of the negative pressure balance tank of this application are:

The negative pressure balance tank can always maintain a micro-negative pressure environment in the tank body 1, so as to minimize the foaming of the material inside the tank body 1, and can eliminate the bubbles after the foam is generated, effectively solving the problem of easy accumulation of foam in the balance tank, and can achieve the effect of improving product quality, increasing production efficiency and reducing production costs.

The above description is only an illustrative embodiment of the present application and is not intended to limit the scope of the present application. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present application shall fall within the scope of protection of the present application.

Claims (13)

A negative pressure balance tank, comprising a tank body, a feed pipe and a discharge pipe being arranged on the tank body, and a discharge pump being arranged on the discharge pipe or on a pipeline connected to the discharge pipe; The tank body is provided with a negative pressure interface connected to a negative pressure source, and a first valve member is provided at the negative pressure interface or on a pipeline connected to the negative pressure interface; When the material is fed into the tank through the feed pipe, the first valve member is turned on; When the material in the tank is delivered through the discharge pipe, the discharge pump is started and the first valve member is closed. The negative pressure balance tank as described in claim 1, wherein a feed port is provided in the middle and lower part of the tank body, one end of the feed pipe is connected to the feed port, the axial direction of the feed pipe is tangent to the outer wall of the tank body, and the axis of the feed pipe gradually tilts upward from close to the tank body to away from the tank body. The negative pressure balance tank according to claim 2, wherein the angle between the axis of the feed pipe and the horizontal plane is 5° to 45°. The negative pressure balance tank as described in claim 1, wherein a bottom cover is provided at the bottom of the tank body, the bottom cover is an inverted cone structure that gradually tapers from top to bottom, a discharge port is provided at the central contraction position of the bottom cover, and one end of the discharge pipe is connected to the discharge port. The negative pressure balance tank as described in claim 4, wherein a guide plate is provided inside the tank body and above the discharge port, and a plurality of guide holes are opened on the guide plate, and the material passes through the plurality of guide holes and is sent out from the discharge port. The negative pressure balance tank according to claim 4, wherein the angle between the bottom cover and the horizontal plane is 15° to 60°. The negative pressure balance tank according to claim 1, wherein a top cover is provided on the top of the tank body, the top cover is a conical structure that tapers from bottom to top, and the angle between the top cover and the horizontal plane is 10° to 30°. The negative pressure balance tank according to claim 1, wherein a first pressure detection element is provided on the top of the tank body, and/or a second pressure detection element is provided on the bottom of the tank body. The negative pressure balance tank according to claim 1, wherein a first liquid level detection element and a second pressure detection element are respectively provided at the top and the bottom of the tank body. The negative pressure balance tank according to claim 1, wherein the tank body is provided with a manhole, a manhole cover is provided at the manhole, and an electronic lock is provided on the manhole cover. The negative pressure balance tank according to claim 1, wherein at least one spray device is provided inside the tank body, and a second valve member is provided on the spray device or on a pipeline connected to the spray device. The negative pressure balance tank as described in claim 11, wherein the discharge pipe and the spray device are respectively connected to the first pipeline and the second pipeline, the first pipeline is connected to the second pipeline, and the second valve member is located on the discharge pipe or on the first pipeline or on the second pipeline or on the spray device. The negative pressure balance tank as described in claim 11, wherein the feed pipe and the spray device are respectively connected to the third pipeline and the fourth pipeline, the third pipeline is connected to the fourth pipeline, a third valve member is provided on the feed pipe or on the third pipeline, and the second valve member is located on the fourth pipeline or on the spray device.