Riser design method, riser and device for upwelling generating device for kelp culture

Abstract

The invention belongs to the technical field of large-scale algae breeding engineering, and proposes a riser design method, a riser and a device for an upwelling generating device for kelp breeding, wherein the riser is designed as a truncated cone-shaped riser; the design steps of the diameters at both ends of the riser include: taking the average seawater depth of seawater in different kelp breeding areas, the average seawater flow rate in a preset period, and the nutrient salt content in the lower water body at a preset depth as influencing factors, and taking the preset kelp breeding nutrient salt demand as a target amount, to determine the diameter of the first end face of the truncated cone-shaped riser; determining the diameter of the second end face of the truncated cone-shaped riser according to the diameter of the first end and a preset ratio; designing the riser as a truncated cone-shaped riser, avoiding the use of a heating device and saving costs; and the design of the riser fully considers the influence of external factors in different breeding areas, so that the nutrient salt brought by the upwelling in the riser can be well applied to kelp production, thereby ensuring the growth and quality of the kelp.

Description

Technical Field

[0001] The invention belongs to the technical field of large algae cultivation engineering, and in particular relates to a riser design method, a riser and a device of an upwelling generating device for kelp cultivation. Background Art

[0002] Nutrients such as nitrogen and phosphorus in seawater are essential nutrients for kelp growth. Years of continuous cultivation have caused a certain degree of barrenness in the upper water bodies of kelp cultivation areas. The lack of nutrients has affected the healthy growth of kelp and even caused kelp to become sick. Therefore, in order to ensure the sustainable development of kelp cultivation, it is urgent to solve the problem of poor nutrients in the upper water bodies of kelp cultivation areas. Unlike the upper water bodies, the bottom water bodies are usually rich in nutrients. By injecting compressed air into the seabed and forming an ascending bubble curtain, an upwelling is generated, which brings the bottom seawater to the surface, thereby replenishing the surface nutrients, which can significantly increase the yield of a single kelp plant and effectively solve the problem of poor nutrients in the upper water bodies.

[0003] The inventors have discovered that when the riser (vertical cylinder) in the current upwelling generating device is working, it is necessary to use a heating device to heat the water in the riser and then use the chimney effect to achieve upwelling, which increases costs and heat energy consumption; and the design of the riser does not take into account the influence of external factors in different breeding areas, so that the nutrients brought by the upwelling in the riser are not well suitable for kelp production, affecting the growth and quality of the kelp. Summary of the invention

[0004] In order to solve the above-mentioned problems, the present invention proposes a riser design method, a riser and a device for an upwelling generating device for kelp cultivation. The riser is designed to be a truncated cone-shaped riser, which avoids the use of a heating device and saves costs. In addition, the design of the riser fully considers the influence of external factors in different breeding areas, so that the nutrients brought by the upwelling in the riser can be well applied to kelp production, thereby ensuring the growth and quality of the kelp.

[0005] In order to achieve the above-mentioned object, in a first aspect, the present invention provides a method for designing a riser of an upwelling generating device for kelp cultivation, which adopts the following technical scheme:

[0006] A method for designing a riser of an upwelling generating device for kelp cultivation, comprising a step of designing the overall structure of the riser and a step of designing the diameters of both ends of the riser;

[0007] The steps of designing the overall structure of the riser include: designing the riser as a truncated cone-shaped riser;

[0008] The steps for designing the diameters of both ends of the riser include: taking the average seawater depth of seawater in different kelp cultivation areas, the average seawater flow rate in a preset period, and the nutrient content in the lower water body at a preset depth as influencing factors, and taking the preset nutrient demand for kelp cultivation as the target amount, to determine the diameter of the first end face of the truncated cone riser; based on the diameter of the first end and a preset ratio, determine the diameter of the second end face of the truncated cone riser.

[0009] Furthermore, the diameter of the first end face is greater than the diameter of the second end face, and the diameter of the first end face is located in the lower layer of seawater.

[0010] Furthermore, the axial length of the riser is equal to the depth of the first end face in the seawater minus the length of the float rope; the depth of the first end face in the seawater is determined by the nutrient content in the lower water body.

[0011] Furthermore, a check valve is provided at one end of the riser close to the second end face.

[0012] Furthermore, the formula for determining the diameter of the first end face of the truncated cone riser is:

[0013] ΔP=D1(αT+βV+γP1)

[0014] Among them, ΔP is the nutrient demand for kelp farming; D1 is the diameter of the first end face; T is the average seawater depth; V is the average seawater flow rate; P1 is the nutrient content in the lower water body; α, β and γ are fitting parameters.

[0015] Furthermore, the nutrient salt demand for kelp farming is equal to the difference between the actual nutrient salt demand for kelp farming and the nutrient salt content in the upper water body.

[0016] Furthermore, the area ratio of the area of ​​the first end surface to the diameter of the second end surface is 0.5 to 0.8.

[0017] In order to achieve the above-mentioned object, in a second aspect, the present invention further provides a riser of an upwelling generating device for kelp cultivation, which adopts the following technical solution:

[0018] A riser of an upwelling generating device for kelp cultivation, wherein the riser is obtained by the riser design method of the upwelling generating device for kelp cultivation described in the first aspect.

[0019] In order to achieve the above-mentioned purpose, in a third aspect, the present invention also provides an upwelling generating device for kelp cultivation, which adopts the following technical scheme:

[0020] An upwelling generating device for kelp culture comprises a riser, a float connected to one end of the riser via a float rope, and a sinker connected to the other end of the riser via a sinker rope;

[0021] The riser is obtained by the riser design method of the upwelling generating device for kelp cultivation described in the first aspect.

[0022] Furthermore, it also includes a raft frame rope, on which a plurality of floats are arranged, and each float is connected to a riser via a float rope.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] In the present invention, the riser is designed as a truncated cone-shaped riser. When the riser moves downward with the waves, more water enters the end with a larger diameter, thereby forming a larger water flow at the end with a smaller diameter, which better forces the water body to reach the upper layer of seawater on the end with a smaller diameter, thereby replenishing the nutrients of the upper water layer, avoiding the use of a heating device, and saving costs. In addition, the average seawater depth of seawater in different kelp breeding areas, the average seawater flow rate in a preset period, and the nutrient content in the lower water body at a preset depth are used as influencing factors, and the preset nutrient demand for kelp breeding is used as the target amount to determine the first end face diameter of the truncated cone-shaped riser; the second end face diameter of the truncated cone-shaped riser is determined according to the diameter of the first end and the preset ratio; the influence of external factors in different breeding areas is fully considered, so that the nutrients brought by the upward flow in the riser can be well applied to kelp production, thereby ensuring the growth and quality of the kelp. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings in the specification that constitute a part of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments of this embodiment and their descriptions are used to explain this embodiment and do not constitute improper limitations on this embodiment.

[0026] Figure 1 This is a schematic diagram of the structure of Embodiment 2 of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of Embodiment 3 of the present invention;

[0028] Among them, 1. Float; 2. Float rope; 3. Check valve; 4. Standpipe; 5. Sinking rope; 6. Sinker; 7. Raft frame rope; 8. Kelp; 9. Connecting rope. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0030] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0031] Embodiment 1:

[0032] At present, when the riser in the upwelling generating device is working, it is necessary to use a heating device to heat the water in the riser and then use the chimney effect to achieve upwelling, which increases the cost and heat energy consumption; moreover, the design of the riser does not take into account the influence of external factors in different breeding areas, so that the nutrients brought by the upwelling in the riser are not well suitable for kelp production, affecting the growth and quality of kelp.

[0033] In view of the above problems, this embodiment provides a method for designing a riser of an upwelling generating device for kelp cultivation, including a step for designing the overall structure of the riser and a step for designing the diameters of both ends of the riser;

[0034] The design steps of the overall structure of the riser include: Figure 1 As shown, the riser is designed as a truncated cone-shaped riser; it can be understood that when in use, the end of the truncated cone-shaped riser with a larger diameter is located in the lower layer of seawater, and the end with a smaller diameter is located in the upper layer of seawater;

[0035] The steps for designing the diameters of both ends of the riser include: taking the average seawater depth in different kelp farming areas, the average seawater flow rate in a preset period, and the nutrient content in the lower water body at a preset depth as influencing factors, and taking the preset nutrient demand for kelp farming as the target amount, to determine the diameter of the first end face of the truncated cone riser; determining the diameter of the second end face of the truncated cone riser based on the diameter of the first end and a preset ratio; optionally, the diameter of the first end is greater than the diameter of the second end, and the diameter of the first end face is located in the lower layer of seawater.

[0036] Specifically, the riser is designed as a truncated cone-shaped riser, which avoids the use of a heating device and saves costs. In addition, it is understandable that in the process of kelp cultivation, the demand for nutrients is not the more the better, and the control of the nutrient content in seawater needs to be determined according to the production and quality requirements of kelp; the actual demand for nutrients in seawater for kelp cultivation can be determined by experiments, which will not be described in detail here; based on this, in this embodiment, the design of the riser fully considers the influence of external factors such as the average seawater depth of seawater in different kelp cultivation areas, the average seawater flow rate within a preset period, and the nutrient content in the lower water body at a preset depth, so that the nutrients brought by the upwelling in the riser can be well applied to kelp production, ensuring the growth and quality of kelp in different kelp cultivation areas.

[0037] In this embodiment, the axial length of the riser is equal to the depth of the first end face in the seawater minus the length of the float rope; the depth of the first end face in the seawater is determined by the nutrient content in the lower water body.

[0038] In this embodiment, the nutrient salt content of different depths in the lower layer of seawater in the aquaculture area is obtained by measurement; the first end face is set to a size with a higher nutrient salt content. Optionally, the axial length of the riser is 0.6 to 0.8 times the depth of seawater, and the nutrient salt concentration does not change much in a certain vertical range close to the seabed. The effect of obtaining nutrients is better when the first end face is 2 to 5 meters away from the seabed. In addition, considering that the length of kelp is generally 2 to 4 meters, the second end face can be 2-3 meters away from the sea surface. In summary, from the total water depth, the distance from the bottom end of the truncated cone riser to the seabed and the distance from the top end to the sea surface are removed, and it is concluded that the length of the riser is approximately 0.6 to 0.8 times the depth of seawater.

[0039] When no check valve is provided in the riser, under the action of waves, there will be an upward water column difference at the top every time the riser descends and rises, thereby forming an upward flow in the riser. In this embodiment, a check valve is provided at the upper end of the riser to only allow water to pass upward, so that the upward flow effect generated by the device will be further enhanced.

[0040] In some other embodiments, optionally, the check valve is disposed at the lower end of the riser, or check valves are disposed at both ends, and the riser can be made of polyethylene material.

[0041] In this embodiment, the length of the truncated cone riser is:

[0042] L=(D-2h)k1

[0043] Wherein, D is the sea water depth; h is the wave height; k1 is the safety factor, the value is less than 1, and the optional k1=0.8 is used to prevent the truncated cone riser from hitting the seabed.

[0044] In this embodiment, the diameter of the first end surface of the truncated cone riser can be determined empirically:

[0045] ΔP=D1(αT+βV+γP1)

[0046] Among them, ΔP is the nutrient salt demand for kelp farming, and optionally, the nutrient salt demand for kelp farming is equal to the difference between the actual nutrient salt demand for kelp farming and the nutrient salt content in the upper water body, ΔP=P-P2, P is the actual nutrient salt demand for kelp farming, and P2 is the nutrient salt content in the upper water body, which can be detected; D1 is the diameter of the first end face; T is the average seawater depth, and optionally, it is obtained by averaging the seawater depths obtained from multiple selected measuring points; V is the average seawater flow rate, and optionally, it is measured several times every month in the kelp farming area, and the average seawater flow rate is obtained by averaging over a period of one year; P1 is the nutrient salt content in the lower water body, which can be detected; α, β and γ are fitting parameters, and optionally, they are fitted through a large amount of historical data, such as on the basis of a given D1, using the least squares method and other methods.

[0047] In this embodiment, optionally, the area ratio of the area of ​​the first end surface to the diameter of the second end surface is 0.5 to 0.8.

[0048] In other embodiments, the seawater depth is 15m; the diameters (inner diameters) of the top and bottom ends of the truncated cone riser are 150mm and 200mm respectively, and the area ratio of the top circle to the bottom circle of the truncated cone riser is 0.56; the truncated cone riser is 10m long, and a check valve is provided 30cm away from the bottom end of the truncated cone riser; the lengths of the float rope and the sinker rope are 2m and 20cm respectively; through the above arrangement, it is used in the aquaculture area to bring the nutrient-rich seawater at the bottom to the surface, replenishing the nutrients required for the normal growth of kelp.

[0049] Example 2

[0050] like Figure 1 As shown, this embodiment provides a riser 4 of an upwelling generating device for kelp cultivation, and the riser 4 is obtained by the riser design method of the upwelling generating device for kelp cultivation described in Example 1, which will not be described in detail here.

[0051] The working principle or process of this embodiment is as follows:

[0052] The artificial upwelling generating device and the riser are arranged in a kelp culture area or an artificial algae reef area, the buoy 1 provides buoyancy for the entire device, and under the combined action of the buoyancy of the buoy 1 and the gravity of the sinker 6, the riser 4 is suspended in the seawater;

[0053] When the riser 4 rises to the maximum height with the waves, it moves downward under the action of gravity as the wave surface drops; the depth of the riser 4 from the highest position to the lowest position is H, and during this descent, the total length of the water column gushing out of the top of the riser 4 is h1, where h1=1.25~2H;

[0054] When the standpipe 4 rises again with the waves, the rise height of the standpipe 4 from the lowest position to the highest position is still H. When the check valve 3 is not provided, the total length of the water column flowing into the pipe from the top of the standpipe 4 is H. When the check valve 3 is provided, only the upward water flow is allowed to pass through, and the top of the standpipe 4 will not flow into the seawater.

[0055] When the check valve 3 is not provided, under the action of waves, each time the riser 4 descends and rises, there will be an upward water column difference at the top, thereby forming an upflow in the riser 4; if the check valve 3 is provided at the upper end of the riser 4, the upflow effect generated by the riser 4 is further enhanced.

[0056] By utilizing the energy of waves to move the riser 4 up and down, an upwelling can be generated without the need for additional energy; an upwelling can be generated even without the check valve 3 being provided, and providing the check valve can further enhance the upwelling effect.

[0057] Embodiment 3:

[0058] like Figure 2 As shown, this embodiment provides an upwelling generating device for kelp cultivation, comprising a float 1, a float rope 2 connected to the float 1, a riser 4 connected to the float rope 2, a check valve arranged in the riser 4, a sinker rope 5 connected to the riser 4, and a sinker 6 connected to the sinker rope 5;

[0059] The riser 4 is obtained by the riser design method of the upwelling generating device for kelp cultivation described in Example 1.

[0060] The device in this embodiment also includes a raft frame rope 7, on which a plurality of buoys 1 are arranged, and each buoy 1 is connected to a riser 4 via a buoy rope 2; both ends of the raft frame rope 7 are connected to the seabed via a connecting rope 9 respectively.

[0061] The device in this embodiment has low operation and maintenance costs. The device in this embodiment is set in a kelp culture area or hung on a raft frame rope without special maintenance.

[0062] Embodiment 4:

[0063] This embodiment provides an upwelling generating device for kelp cultivation, which is different from the embodiment 1 in that the design of the riser is optimized, specifically:

[0064] The generatrix slope of the riser is a key parameter for the upwelling effect. The larger the slope, the better the upwelling effect, but the sedimentation force set at the bottom of the riser and the lifting force provided by the top are also required to be greater. The size of the generatrix slope of the truncated cone riser is determined by how much the bottom diameter (inner diameter) of the truncated cone riser exceeds the top diameter (inner diameter). When the top inner diameter of the truncated cone riser is determined, the design calculation steps for the bottom inner diameter of the truncated cone riser are:

[0065] S1. Select the specifications of the float according to the existing molded products, and assume that the maximum buoyancy provided by the float is Fmax.

[0066] S2. Select the diameter of the top surface of the truncated cone-shaped vertical tube according to the existing molded products, or according to the scheme in Example 1, obtain the inner diameter of the top surface of the truncated cone-shaped vertical tube as D1 and the wall thickness as S.

[0067] S3. Assume that the inner diameter of the bottom of the truncated cone-shaped vertical pipe is D2, and calculate the volume V of the truncated cone-shaped vertical pipe and the gravity Wp in water as follows:

[0068] Wp=(ρp -ρ w )V g

[0069] Among them, Wp is less than 0; ρ p is the density of the truncated cone riser material; ρ w is the density of seawater; g is the acceleration due to gravity.

[0070] S4. Determine the weight W of the sinker in water s for:

[0071] W s =-k2*Wp

[0072] Among them, k2 is the counterweight coefficient, and its value is greater than 1; k2 is usually taken as 1.5 to ensure that the truncated cone riser is in a vertical state in the sea and to provide a larger settling force for the downward movement of the truncated cone riser.

[0073] S5. According to the wave period T and wave height h with higher frequency in the sea area, use formula F max =W s +Wp+Fd+Fm, calculate the limit value D of D2 2max , Fd is the water resistance encountered by the truncated cone riser when it is pulled upward, and is the additional mass force experienced by the truncated cone riser; when setting a check valve, the gravity of the seawater in the riser must be added.

[0074] S6. According to the existing molded products, determine the value of the inner diameter D2 of the bottom surface of the truncated cone standpipe so that D2≤D 2max In practical applications, if there is no truncated cone-shaped riser product with a generatrix slope of (D2-D1) / 2L, it can also be implemented by connecting in two sections, that is, using a round tube in the upper part and a commercially available truncated cone-shaped riser in the lower part, or vice versa;

[0075] In this embodiment, optionally, the length of the float rope is 0 to 3 m, and can be directly connected to the float when the water depth is shallow; the length of the sinker rope is 0 to 0.5 m, and can be directly connected to the bottom of the riser when the water depth is shallow.

[0076] At this time, the total length of the water column gushing out from the top of the truncated cone riser is h1:

[0077] h1=(D2 2 / D1 2 )H

[0078] When the device rises again with the waves, assuming that the height of the truncated cone riser from the lowest position to the highest position is still H, then the total length of the water column flowing into the tube from the top of the truncated cone riser is H, H

[0079] ​In one embodiment, no check valve is set in the truncated cone riser, the sea area has a high frequency of wave period T = 6s, wave height h = 1m, seawater depth is 20m, safety factor k1 = 0.8, then the length of the truncated cone riser is L = 14.4m. According to the existing molded products, a buoy with a diameter of 320mm commonly used in raft farming is selected, and its maximum buoyancy is F max =166.6N. According to the existing molded products, the selected truncated cone-shaped vertical tube top surface inner diameter D1 = 172.8mm, wall thickness S = 13.6mm, and outer diameter is 200mm. The initial setting D2 = 300mm, then the outer diameter of the bottom surface of the truncated cone-shaped vertical tube is 327.2mm, and the calculated volume of the truncated cone-shaped vertical tube is V = 0.15m 3 The material density of the truncated cone riser is ρ p =960kg / m 3 , seawater density is taken as ρ w =1025kg / m 3 , the weight W of the truncated cone in seawater is calculated p =-97.98N, that is, the gravity of the truncated cone standpipe itself is less than the buoyancy it receives. The weight coefficient is k2 = 1.5, and the weight of the sinker in the water is calculated to be W s =146.97N.

[0080] According to the wave parameters, the average velocity of the wave water particles is 0.52m / s. According to the volume of the truncated cone riser, its additional mass is calculated to be about 157.66kg. When the truncated cone riser moves upward, the speed is lower than 0.52m / s. According to 0.52m / s, the water resistance F of the truncated cone riser is d = 10.22N, the actual water resistance of the truncated cone riser is less than this value. The acceleration of the truncated cone riser upward is 0.17m / s 2 Approximately, the additional mass force F m =26.80N. When D2 is set to 300mm, the downward force on the truncated cone riser is 86.01N, which is less than the maximum buoyancy provided by the float. Adjust the value of D2, W p , W s 、F d 、F m All of them change, using formula F max =W s +W p +F d +F m , calculate D 2max =591mm, that is, the inner diameter of the bottom surface of the truncated cone riser cannot exceed 591mm.

[0081] Assuming that there is a truncated cone riser in the molded product with the outer diameter and inner diameter of the top surface being 200mm and 172.8mm respectively, and the outer diameter and inner diameter of the bottom surface being 400mm and 372.8mm respectively, then a truncated cone riser of this specification shall be selected.

[0082] Because the water depth in this embodiment is relatively deep, the float rope is taken as 3m and the sinker rope is taken as 0.5m.

[0083] The above description is only a preferred embodiment of the present embodiment and is not intended to limit the present embodiment. For those skilled in the art, the present embodiment may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present embodiment shall be included in the protection scope of the present embodiment.

Claims

1. A method for designing a riser pipe of an upwelling generating device for kelp cultivation, characterized in that: It includes the design steps of the overall structure of the riser and the design steps of the diameters at both ends of the riser; The steps of designing the overall structure of the riser include: designing the riser as a truncated cone-shaped riser; The steps of designing the diameters of both ends of the riser include: taking the average seawater depth of seawater in different kelp culture areas, the average seawater flow rate in a preset period, and the nutrient salt content in the lower water body at a preset depth as influencing factors, and taking the preset nutrient salt demand for kelp culture as the target amount, determining the diameter of the first end face of the truncated cone-shaped riser; determining the diameter of the second end face of the truncated cone-shaped riser according to the diameter of the first end face and a preset ratio; The formula for determining the diameter of the first end face of the truncated cone riser is: ΔP=D1(αT+βV+γP1) Among them, ΔP is the nutrient demand for kelp farming; D1 is the diameter of the first end face; T is the average seawater depth; V is the average seawater flow rate; P1 is the nutrient content in the lower water body; α, β and γ are fitting parameters.

2. The method for designing a riser of an upwelling generating device for kelp cultivation as claimed in claim 1, characterized in that: The diameter of the first end face is greater than the diameter of the second end face, and the diameter of the first end face is located in the lower layer of seawater.

3. The method for designing a riser of an upflow generating device for kelp cultivation as claimed in claim 2, characterized in that: The axial length of the riser is equal to the depth of the first end face in the seawater minus the length of the float rope; the depth of the first end face in the seawater is determined by the nutrient content in the lower water body.

4. The method for designing a riser of an upflow generating device for kelp cultivation as claimed in claim 1, characterized in that: In the standpipe, a check valve is arranged at one end close to the second end surface.

5. The method for designing a riser of an upflow generating device for kelp cultivation as claimed in claim 1, characterized in that: The nutrient salt requirement for kelp farming is equal to the difference between the actual nutrient salt requirement for kelp farming and the nutrient salt content in the upper water body.

6. The method for designing a riser of an upwelling generating device for kelp cultivation as claimed in claim 1, characterized in that: The area ratio of the area of ​​the first end surface to the diameter of the second end surface is 0.5 to 0.

8.

7. A riser pipe of an upwelling generating device for kelp cultivation, characterized in that: The riser is obtained by the riser design method of the upflow generating device for kelp cultivation according to any one of claims 1 to 6.

8. An upwelling generating device for kelp cultivation, characterized in that: It includes a riser, a float ball connected to one end of the riser through a float rope, and a sinker connected to the other end of the riser through a sinker rope; The riser is obtained by the riser design method of the upflow generating device for kelp cultivation according to any one of claims 1 to 6.

9. The upwelling generating device for kelp cultivation according to claim 8, characterized in that: It also includes a raft frame rope, on which a plurality of float balls are arranged, and each float ball is connected with a riser through a float rope.

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