WO2021004190A1

WO2021004190A1 - Low-pressure irrigation venturi fertilizer applicator with dual fertilizer suction ports

Info

Publication number: WO2021004190A1
Application number: PCT/CN2020/093271
Authority: WO
Inventors: 魏正英; 张磊; 贾维兵; 张千; 冯培存; 张育斌
Original assignee: 西安交通大学
Priority date: 2019-07-10
Filing date: 2020-05-29
Publication date: 2021-01-14
Also published as: CN110419310A; CN110419310B

Abstract

A low-pressure irrigation venturi fertilizer applicator with dual fertilizer suction ports, comprising a water inlet section (1), an axially symmetric converging section (2), a throat section (3), an axially symmetric diverging section (4) and a water outlet section (5). The water inlet section (1), the axially symmetric converging section (2), the throat section (3), the axially symmetric diverging section (4) and the water outlet section (5) are provided along the water flow direction sequentially, and the throat section (3) is provided with two fertilizer suction pipes (6) symmetrically. The fertilizer applicator changes the operating water flow state of the classical venturi fertilizer suction device, so that the negative pressure area in the throat portion is distributed more uniformly, and the fertilizer liquid flow direction and the water flow direction can be mixed more quickly and uniformly, facilitating the stabilization of fertilizer suction and improving the proportion of the fertilizer suction, and greatly satisfying the requirements for water-fertilizer integration in a low-pressure irrigation system.

Description

Venturi fertilizer applicator with low pressure irrigation and double suction fertilizer mouth

Technical field

The invention belongs to the technical field of agricultural water and fertilizer integration, and relates to a small fertilizer suction device matched with a low-pressure irrigation system, in particular to a low-pressure irrigation double suction fertilizer port Venturi fertilizer applicator.

Background technique

Low-pressure irrigation technology uses energy-optimized methods to reduce the need for high-pressure energy levels in the front end of the irrigation system under normal pressure irrigation systems. The integration of water and fertilizer is to mix fertilizer with water in the middle of irrigation, achieve one-time simultaneous irrigation of water and fertilizer, save water and fertilizer resources, irrigate uniformly, improve water and fertilizer utilization efficiency, and reduce labor costs. The low-pressure water-fertilizer integrated irrigation combined with the two methods can give full play to the advantages of both, reduce energy consumption while realizing simultaneous irrigation of water and fertilizer, and further improve crop growth.

Fertilizer with water in the irrigation system is to install fertilizer equipment on the water pipeline, including differential pressure fertilizer applicator, proportional fertilizer applicator, fertilizer pump and Venturi fertilizer applicator. Differential pressure type fertilizer applicator needs to adjust the opening degree of the front and rear supporting valves to form a pressure difference to form a fertilizer absorption effect, but the accuracy of the pressure difference is difficult to control, and the uniformity of fertilization is poor. The proportional fertilizer applicator uses the power of the main water circuit to drive the internal piston to achieve the function of absorbing fertilizer, and the proportional knob can be adjusted to control the amount of fertilizer. However, the cost of this device is high and it is difficult to popularize in my country. The performance of the fertilizer applicator is stable, but it needs an independent power source (pump). The overall device has a complex structure and a large volume, making it difficult to apply in small user farmland areas. The Venturi fertilizer applicator has a simple structure and uses the hydraulic force and its own structure to produce a pressure difference. The negative pressure area of the throat provides conditions for the external atmospheric pressure to transport the fertilizer liquid into the Venturi fertilizer applicator through the fertilizer suction port, and the device cost is low.

The fertilizer absorption performance of the Venturi applicator has a lot to do with its own structure. If the design is unreasonable, the fertilizer suction pipe will flow backwards. The current Venturi fertilizer applicator generally has too much initial pressure for fertilizer absorption, which is only suitable for atmospheric irrigation systems, and the single fertilizer suction port at the throat will affect the uniform distribution of the overall watershed. The minimum negative pressure at the throat section will It tends to be around the side wall of the fertilizer suction port, and the inertial force of the water flow in the main pipe is small and concentrated, which makes it difficult to absorb fertilizer stably. Therefore, the improvement of the existing Venturi fertilizer suction device structure is the direction of the applicant's attention.

Summary of the invention

The invention provides a low-pressure double-suction fertilizer port Venturi fertilizer applicator, which improves the use performance of the supporting Venturi fertilizer applicator, reduces the critical fertilizer absorption pressure, increases the fertilizer absorption, and reduces the throat The concentrated area of the minimum negative pressure zone can improve the uniform distribution range and improve the fertilizer absorption performance and stability.

In order to achieve the above objectives, the present invention adopts the following technical solutions: a low-pressure irrigation double suction fertilizer port Venturi fertilizer applicator, including a water inlet section, an axisymmetric contraction section, a throat section, an axisymmetric expansion section and a water outlet section; The water inlet section, the axisymmetric contraction section, the throat section, the axisymmetric expansion section and the water outlet section are arranged in order in the direction of the water flow; the throat section is provided with a fertilizer suction pipe symmetrically, and the axis of the fertilizer suction pipe has an angle with the axis of the venturi main pipe α, the fertilizer suction pipe is connected with the throat section.

The inlet end of the fertilizer suction pipe is provided with a one-way valve.

The fertilizer suction pipe is connected to the fertilizer liquid irrigation.

A filter is provided at the inlet end of the fertilizer suction pipe.

The angle α between the axis of the fertilizer suction pipe and the water inlet section is 50°-80°.

The contraction angle β of the axisymmetric contraction section is 18°～26°, and the expansion angle γ of the axisymmetric expansion section is 5°～9°.

The length ratio of the axisymmetric contraction section and the axisymmetric expansion section is 0.178～0.486.

The included angle α is 50°, the contraction angle β of the axisymmetric contraction section is 24°, and the expansion angle γ of the axisymmetric expansion section is 6°.

The inner diameter of the water inlet section and the water outlet section are the same.

The axisymmetric contraction section, the throat section, the axisymmetric expansion section and the outer wall of the fertilizer suction pipe are provided with reinforcing ribs, and the reinforcing ribs connect the axisymmetric contraction section, the throat section, the axisymmetric expansion section and the fertilizer suction pipe into a whole.

Compared with the prior art, the present invention has at least the following beneficial effects: According to the hydraulics-Bernoulli principle, two fertilizer suction pipes are arranged at the throat of the venturi and are 50°-80° to the main axis of the venturi. °The included angle changes the water flow state of the classic Venturi fertilizer suction device, so that the negative pressure area in the throat is more evenly distributed, and the fertilizer liquid flow direction and the water flow direction can be quickly mixed and consistent, which is beneficial to stabilize the fertilizer absorption and increase the fertilizer absorption ratio , The proportion of fertilizer absorption can reach 30%; the suction pipe in the throat uniformly distributes the negative pressure area formed by the sudden shrinkage of the throat section on the entire circular section where the fertilizer suction pipe and the throat section are connected, making the negative pressure area more stable and concentrated , Further reduce the working pressure of the front end of the venturi; the invention reduces the overall size, rationally optimizes the structural parameters of each part, reduces the critical fertilizer absorption pressure, the starting pressure can be as low as 0.008MPa, and meets the low pressure irrigation pressure conditions; the invention has a simple and compact structure, Change the fertilizer structure layout of the existing classic Venturi fertilizer suction device without adding external accessories and no additional power source.

Furthermore, a one-way valve at the end of the fertilizer suction pipe can prevent water from flowing into the fertilizer liquid through the fertilizer suction pipe when the pressure does not reach the working pressure during the start-stop phase, causing pollution and affecting the fine water and fertilizer ratio.

Description of the drawings

Figure 1 is a schematic diagram of the overall structure of the present invention;

Figure 2 is an internal sectional view of the present invention;

Figure 3 is a graph showing the relationship between inlet pressure and fertilizer absorption of the fertilizer applicator of the present invention;

Figure 4 is a graph showing the relationship between inlet pressure and fertilizer absorption concentration of the fertilizer applicator of the present invention;

Figure 5 is a pressure vector diagram of an embodiment of the fertilizer applicator according to the present invention;

Fig. 6 is a velocity vector diagram and flow trace diagram of an embodiment of the fertilizer applicator according to the present invention.

The marks in the figure indicate: 1. Water inlet section, 2. Axisymmetric contraction section, 3. Throat section, 4. Axisymmetric expansion section, 5. Water outlet section, 6. Fertilizer suction pipe, 7, Stiffener, 8. One-way valve.

Detailed ways

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

According to the working principle of the venturi tube and the related knowledge of fluidics, for the fluid in the same pipeline, its flow rate is inversely proportional to the equivalent area of the flow section, that is, when the equivalent area of the pipeline section changes, the fluid flow rate will also be corresponding Variety. Therefore, the cross-sectional area of the throat section in the venturi structure shrinks sharply relative to the cross-sectional area of the inlet end, and the fluid flow rate of the throat section reaches the maximum value. At the same time, there is a vacuum around the throat section wall, which is negative pressure relative to the throat section and increases at the throat. The pipeline connected with atmospheric pressure can transport the liquid into the inside of the venturi through the pressure difference, which is the principle of the venturi fertilizer suction device. The setting of a single fertilizer suction port disrupts the uniform distribution of negative pressure in the throat, and the flow direction of the fertilizer liquid is perpendicular to the direction of the main water flow, resulting in uneven mixing, unstable fertilizer absorption, and large critical pressure for fertilizer absorption. There is a large backflow at the axisymmetric enlarged section, which affects the application of the Venturi fertilizer applicator in the low-pressure irrigation system as a whole.

1 and 2, this embodiment provides a low-pressure double-suction fertilizer port Venturi fertilizer applicator, including a water inlet section 1, an axisymmetric contraction section 2, a throat section 3, an axisymmetric expansion section 4 and a water outlet section 5; , The water inlet section 1, the axisymmetric contraction section 2, the throat section 3, the axisymmetric expansion section 4 and the water outlet section 5 are arranged in sequence along the water flow direction; the inner diameters of the water inlet section 1 and the water outlet section 5 of the venturi The same; the throat section 3 is provided with two fertilizer suction pipes 6 symmetrically, the axis of the fertilizer suction pipe 6 and the axis of the venturi main pipe have an angle α, and α is 50°-80°; the fertilizer pipe 6 is connected with the throat pipe section 3; The inlet end of the fertilizer pipe 6 is provided with a one-way valve 8; the contraction angle of the axisymmetric contraction section 2 is β, and β is 18°～26°; the expansion angle of the axisymmetric expansion section 4 is γ, and γ is 5°～9 °.

The fertilizer suction pipe 6 is connected to the fertilizer liquid irrigation; the inlet end of the fertilizer suction pipe 6 is provided with a filter, and the filter is arranged between the water inlet of the one-way valve 8 and the outlet of the fertilizer liquid irrigation.

The length ratio of the axisymmetric contraction section 2 and the axisymmetric expansion section 4 is 0.178～0.486.

Following the above technical scheme, the present invention implements a low-pressure double-suction fertilizer port Venturi fertilizer applicator, which includes a water inlet section 1 and a water outlet section 5, an axisymmetric contraction section 2, a throat section 3, and an axisymmetric expansion section 4; 1 The inner diameter of the water outlet section 5 is the same. There are two fertilizer suction pipes 6 symmetrically arranged in the throat section 3. The fertilizer suction pipe 6 and the main axis of the venturi tube have an angle α of 50°, and are connected at the end of the fertilizer pipe 6 One-way valve 8; the fertilizer pipe 6 is biased toward the water inlet section 1 and the angle α with the axis of the classic venturi pipe is 50°. The outer diameter of the water inlet section 1 and the water outlet section 5 is 18 mm, the inner diameter is 16 mm, and the length is 16 mm. The contraction angle β of the axisymmetric contraction section 2 is 24°, and the expansion angle γ of the axisymmetric expansion section 4 is 6°; the outer diameter of the throat section 3 is 5.2mm, the inner diameter is 3.2mm and the length is 6.4mm; the fertilizer pipe 6 The outer diameter is 5.2mm, the inner diameter is 3.2mm, and the length is 34～38mm; the axisymmetric contraction section 2, the throat section 3, the axisymmetric expansion section 4 and the fertilizer pipe 6 are provided with a 2mm thick rib 7 on the outer wall to strengthen The rib 7 connects the axisymmetric contraction section 2, the throat section 3, the axisymmetric expansion section 4 and the fertilizer pipe 6 into a whole; it is used to increase the structural strength of the fertilizer pipe, as shown in Figure 2.

Referring to Figures 3 and 4, the experimental test performance of the present embodiment obtained the fertilizer absorption flow rate and fertilizer absorption concentration under different pressures of the Venturi fertilizer applicator, and fitted the pressure-fertilization flow rate relationship curve of the fertilizer applicator of the present invention. , Pressure-fertilization concentration relationship curve.

The pressure vector diagram of the middle section is shown in Fig. 5, and the velocity vector diagram and flow trace are shown in Fig. 6. In this embodiment, the hydraulic performance simulation is performed in the CFD analysis software FLUENT to observe the pressure vector and velocity vector diagram of the middle section. And the flow trajectory diagram, the use of structural size and angle to reduce the return area, uniform negative pressure distribution, reduce energy consumption, improve the stability and uniformity of fertilizer absorption.

The specific use of the low pressure double suction fertilizer port Venturi fertilizer applicator is as follows:

According to the water flow direction of the irrigation system, the low-pressure multi-suction fertilizer Venturi fertilizer applicator is connected in parallel to the first main water pipeline of the irrigation system according to the direction of the inlet section 1 and the front outlet section 5 and the rear.

Install a small filter at the front end of the one-way valve 8 of the low-pressure double-suction fertilizer port Venturi fertilizer applicator through a hose to prevent impurity particles in the fertilizer liquid from entering the back-end system;

Fertilizer liquid irrigation is set under the fertilizer suction pipe 6. The bottom of the fertilizer liquid irrigation is controlled within 1m from the main axis of the low-pressure double suction fertilizer port Venturi fertilizer applicator. The fertilizer liquid irrigation is filled with sufficient liquid fertilizer; when the water supply of the irrigation system is turned on, The pressure of the water flow enters the system pipeline quickly, and the pressure of the water flow is designed according to the system requirements. The energy level of the pressure supply device is designed. From the inlet section 1 of the low-pressure double suction fertilizer port Venturi fertilizer applicator, it enters the venturi tube and enters the throat through the axisymmetric constriction section 2. Pipe section 3, then through the axisymmetric expansion section 4, and finally enter the irrigation pipe network through the outlet section 5;

The inner diameters of inlet section 1 and outlet section 5 are set to 16mm, which reduces the amount of overflow and initially reduces the working pressure; at the same time, two fertilizer suctions with an angle of 50° with the main axis of the venturi are arranged symmetrically at the throat Tube 6, the fertilizer suction tube 6 uniformly distributes the negative pressure zone formed by the sudden shrinkage of the throat section on the entire circular section where the fertilizer suction tube 6 and the throat section 3 are connected, making the negative pressure zone more stable and concentrated, and further reducing the venturi. Work pressure at the front end of the tube.

The angle α of the fertilizer suction pipe 6 reduces the energy loss when the fertilizer solution is mixed with water, the flow direction can be quickly kept consistent, the uniformity of water and fertilizer mixing is improved, and the backflow of the water and fertilizer mixture in the axisymmetric expansion section 4 is eliminated, which ensures The energy of the irrigation system is stable. The overall work pressure is reduced to meet the needs of low-pressure irrigation systems, and the stability of fertilizer absorption and the uniformity of fertilizers are improved;

The one-way valve on the 6 end of the fertilizer suction pipe only allows the fertilizer liquid to be transported in one direction to prevent the liquid in the venturi tube from flowing back into the fertilizer liquid during the short working period of start and stop, causing pollution of the fertilizer liquid.

In a word, the present invention effectively reduces the critical pressure of fertilizer absorption operation and improves the fertilizer absorption performance by changing the number and arrangement structure of fertilizer suction pipes.

Claims

A low-pressure irrigation double suction fertilizer port Venturi fertilizer applicator, which is characterized in that it comprises a water inlet section (1), an axisymmetric contraction section (2), a throat section (3), an axisymmetric expansion section (4) and a water outlet section (5); Among them, the water inlet section (1), the axisymmetric contraction section (2), the throat section (3), the axisymmetric expansion section (4) and the water outlet section (5) are arranged in sequence along the water flow direction; (3) (2) fertilizer suction pipes (6) are symmetrically arranged, the axis of the fertilizer suction pipe (6) and the axis of the venturi main pipe have an angle α, and the fertilizer suction pipe (6) is connected with the throat section (3).
The low-pressure irrigation double suction fertilizer port Venturi fertilizer applicator according to claim 1, characterized in that the inlet end of the fertilizer suction pipe (6) is provided with a one-way valve (8).
The low-pressure irrigation double-suction fertilizer port Venturi fertilizer applicator according to claim 1, characterized in that the fertilizer suction pipe (6) is connected to the fertilizer liquid irrigation.
The low-pressure irrigation double suction fertilizer port Venturi fertilizer applicator according to claim 1, wherein a filter is provided at the inlet end of the fertilizer suction pipe (6).
The low-pressure irrigation double suction fertilizer port Venturi fertilizer applicator according to claim 1, characterized in that the included angle α of the axis of the fertilizer suction pipe (6) to the water inlet section (1) is 50°-80°.
The low-pressure irrigation double-suction venturi fertiliser applicator according to claim 5, characterized in that the contraction angle β of the axisymmetric contraction section (2) is 18°～26°, and the expansion angle of the axisymmetric expansion section (4) γ is 5°-9°.
The low-pressure irrigation double-suction venturi fertiliser applicator according to claim 6, characterized in that the length ratio of the axisymmetric contraction section (2) and the axisymmetric expansion section (4) is 0.178-0.486.
The low-pressure irrigation double suction fertilizer port Venturi fertilizer applicator according to claim 7, characterized in that the included angle α is 50°, the contraction angle β of the axisymmetric contraction section (2) is 24°, and the axisymmetric expansion section (4) The expansion angle γ of) is 6°.
The low-pressure irrigation double suction fertilizer port Venturi fertilizer applicator according to claim 1, wherein the inner diameter of the water inlet section (1) and the water outlet section (5) are the same.
The low-pressure irrigation double suction fertilizer port Venturi fertilizer applicator according to any one of claims 1-9, characterized in that the axisymmetric contraction section (2), the throat section (3), the axisymmetric expansion section (4) and The outer wall of the fertilizer suction pipe (6) is provided with reinforcing ribs (7), and the reinforcing ribs (7) connect the axisymmetric contraction section (2), the throat section (3), the axisymmetric expansion section (4) and the fertilizer suction pipe (6) As a whole.