Linear fresnel steam generation vibration suppression heat absorbing pipe

Abstract

The application relates to the technical field of solar light and heat steam generation, and discloses a linear Fresnel steam generation vibration-suppressing heat-absorbing pipe. The heat-absorbing pipe is provided with a biasing circumferential shunt partition plate with a through hole in a horizontal pipe body, so as to divide an inner cavity into an upper vapor phase channel and a lower liquid phase channel, and differential spiral inner ribs are arranged in the upper and lower channels respectively, and an axial micro groove group is arranged on the outer wall of the light-concentrating heated side. The micro groove promotes uniform generation of small bubbles, the through hole makes the bubbles disperse into the vapor phase channel, and the spiral inner ribs maintain the rotational flow of the upper and lower channels, so that the vibration of the two-phase flow is reduced and the pressure loss is kept low.

Description

Technical Field

[0001] This invention relates to the field of solar thermal steam generation equipment technology, and in particular to a linear Fresnel steam generation vibration-suppressing absorber tube, which is suitable for two-phase flow vibration suppression of horizontal absorber tubes in linear Fresnel concentrating solar collector systems using direct steam generation mode. Background Technology

[0002] Linear Fresnel concentrating solar thermal systems are an important technical route for medium-temperature industrial steam photothermal steam generation. In the direct steam generation mode, feedwater enters the mirror field absorber tube and undergoes preheating, boiling evaporation and superheating processes in sequence, eliminating intermediate heat exchange links, but the evaporation section will form a vapor-liquid two-phase flow.

[0003] The prior art, US9022020B2, "Linear Fresnel solar arrays and drives therefor," discloses linear Fresnel solar collector arrays and related receiving components, which can be considered the closest prior art to this invention. This type of system focuses on the overall arrangement of the mirror array, drives, and receivers, but does not propose an in-tube flow pattern reconstruction structure to address the liquid plug impact vibrations caused by the evolution from stratified flow to slug flow within the evaporation section of the horizontal absorber tube.

[0004] Inside horizontal or slightly inclined absorber tubes, gravity causes the liquid phase to tend to the bottom and the vapor phase to tend to the top. Unilateral concentrated heating further intensifies local boiling at the bottom of the tube, making it easy for bubbles to coalesce into large vapor bombs. When these large vapor bombs and liquid plugs alternately pass through bends, valves, or points of abrupt changes in cross-section, water hammer, vibration, and noise can easily occur. Long-term operation can lead to loosening of supports and hangers, weld fatigue, and absorber tube failure.

[0005] Existing solutions such as spiral ribs in steam generator tubes, boiling groove surfaces, or gas-liquid separation baffles can improve local heat transfer or separation effects, but these solutions do not form an integrated absorber tube structure centered around the goals of a linear Fresnel DSG horizontal long tube, single-sided heating on the concentrating side, and low pressure loss vibration suppression. Therefore, a absorber tube is needed that can suppress the generation of slug flow from the flow pattern source and adapt to the operating conditions of a linear Fresnel mirror field. Summary of the Invention

[0006] This invention addresses the technical problems existing in the prior art by proposing a linear Fresnel steam generation and vibration suppression absorber tube, which can suppress the slug flow and liquid plug impact vibration in the evaporation section of the linear Fresnel DSG horizontal absorber tube without significantly increasing pressure loss.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A linear Fresnel vapor-generating vibration-suppressing heat absorption tube includes a horizontally arranged tube body, a circumferential flow divider, spiral inner ribs, and a group of microgrooves on the concentrating side. The circumferential flow divider is arranged axially inside the tube body and divides the inner cavity of the tube body into a vapor phase channel located above and a liquid phase channel located below. The circumferential flow divider is provided with a through hole connecting the vapor phase channel and the liquid phase channel. The spiral inner ribs are respectively formed on the upper inner wall corresponding to the vapor phase channel and the lower inner wall corresponding to the liquid phase channel. The group of microgrooves on the concentrating side is formed on the concentrating heating side of the outer wall of the tube body. The spiral inner ribs on the lower inner wall are used to induce liquid phase rotation and allow the heated bubbles to enter the vapor phase channel through the through hole. The spiral inner ribs on the upper inner wall are used to induce vapor phase rotation to form a rotating vapor flow carrying micro-droplets.

[0008] Furthermore, the circumferential flow divider is located above the horizontal mid-surface of the pipe body, such that the cross-sectional area of ​​the vapor phase channel accounts for 25% to 35% of the total cross-sectional area of ​​the inner cavity of the pipe body, and the cross-sectional area of ​​the liquid phase channel accounts for 65% to 75% of the total cross-sectional area of ​​the inner cavity of the pipe body.

[0009] Furthermore, the circumferential diversion baffle is a stainless steel sheet with a thickness of 0.8 mm to 1.2 mm, the through hole is a circular hole or a slit hole, the opening ratio of the through hole is 15% to 25%, and the diameter of the circular hole is 3 mm to 5 mm.

[0010] Furthermore, the circumferential diversion baffle is continuously arranged along the axial direction of the pipe body, or it is composed of multiple segmented baffles with a length of 500mm to 1000mm spaced apart along the axial direction of the pipe body, with a spacing of 50mm between adjacent segmented baffles.

[0011] Furthermore, the spiral inner ribs on the upper inner wall are arranged within the 180-degree arc-shaped inner wall range at the top of the tube, with a rib height of 0.8mm to 1.2mm, a spiral angle of 30 degrees to 40 degrees, a pitch of 120mm to 180mm, and two ribs.

[0012] Furthermore, the spiral inner ribs on the lower inner wall are arranged within the 180-degree arc-shaped inner wall range at the bottom of the tube, with a rib height of 1.2mm to 1.8mm, a spiral angle of 25 degrees to 35 degrees, a pitch of 100mm to 150mm, and 3 to 4 ribs.

[0013] Furthermore, the cluster of microgrooves on the focusing side is located within an arcuate range of approximately 150 degrees at the bottom of the outer wall of the tube, and is composed of rectangular or V-shaped microgrooves extending along the axial direction of the tube. The width of the microgrooves is 0.3 mm to 0.5 mm, the depth is 0.5 mm to 1.0 mm, and the spacing between the microgrooves is 1.0 mm to 1.5 mm.

[0014] Furthermore, the outer diameter of the tube is 38mm to 50mm, the wall thickness is 3mm to 4mm, and the material is 316L stainless steel or Incoloy 800H heat-resistant alloy.

[0015] Furthermore, the inner wall of the pipe is provided with a support boss for positioning the circumferential diversion baffle. The circumferential diversion baffle is fixed to the support boss by welding and the phase of the circumferential diversion baffle and the spiral inner rib are aligned when adjacent pipe sections are connected.

[0016] Furthermore, the circumferential flow divider and at least part of the spiral inner ribs are formed on a core tube that can be inserted from the end of the tube body to adapt to the modification of existing linear Fresnel mirror field heat absorber tubes. Beneficial effects

[0017] This invention uses a circumferential flow divider to confine the naturally stratified vapor and liquid phases in the horizontal pipe to the upper and lower channels respectively, and allows the bubbles generated in the lower layer to disperse into the upper layer through through holes, which can weaken the conditions for bubbles to agglomerate into large vapor bombs.

[0018] This invention utilizes the higher and denser spiral inner ribs of the lower channel to induce the liquid phase to form a rotating liquid film flow, and utilizes the spiral inner ribs of the upper channel to induce the vapor phase to rotate and inhibit droplet coalescence, so that the flow pattern in the evaporation section tends to be a stable pseudo-annular flow.

[0019] The present invention arranges microgrooves on the concentrating heating side, which is beneficial to increase the nucleation density of nucleation boiling on the heating side, so that bubbles detach from the heating surface at a smaller scale and more uniformly, thereby reducing the formation of large vapor bombs from the source.

[0020] This invention does not rely on strong throttling components such as orifice plates and venturis, but mainly achieves vibration suppression through flow pattern reconstruction, and the pressure loss increase is controllable. Under the statistical caliber of the specific embodiment, the pressure loss of a single 24m evaporation section increases from 28kPa to 32kPa, while the root mean square value of vibration acceleration is significantly reduced.

[0021] The partition, spiral ribs, and microgroove group of the present invention can all be integrated into the heat absorber tube body or the insertable core tube, with no moving parts, making it suitable for long-term service of mirror field heat absorbers. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall axial cross-sectional structure of the heat absorption tube of the present invention. Detailed Implementation

[0023] The following combination Figure 1 The embodiments of the present invention will be described below. It should be understood that the embodiments are used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0024] like Figure 1As shown, the heat absorber tube in this embodiment includes a tube body 1, upper inner wall spiral ribs 2, lower inner wall spiral ribs 3, circumferential flow divider 4, a cluster of microgrooves on the concentrating side 8, a vapor phase channel 6, and a liquid phase channel 7. The tube body 1 is a horizontally arranged circular tube with an outer diameter of 42 mm, a wall thickness of 3.5 mm, and is made of 316L stainless steel. The circumferential flow divider 4 is axially arranged inside the tube body 1 and divides the inner cavity of the tube body into an upper vapor phase channel 6 and a lower liquid phase channel 7.

[0025] The circumferential flow divider 4 is located above the horizontal mid-surface of the tube body 1, such that the vapor phase channel 6 accounts for approximately 30% of the area and the liquid phase channel 7 accounts for approximately 70%. The circumferential flow divider 4 can be made of 0.8mm thick 316L stainless steel sheet, with circular holes of approximately 3.5mm in diameter arranged in an equilateral triangular array on the divider, resulting in an opening ratio of approximately 20%. In other embodiments, the through holes can also be slit holes, and the divider thickness, hole diameter, and opening ratio can be adjusted within the range defined in the claims.

[0026] like Figure 1 As shown, the upper inner wall spiral rib 2 is set within the 180-degree arc-shaped inner wall area at the top of the tube. The rib height can be 1.0 mm, the spiral angle can be 35 degrees, the pitch can be 150 mm, and the number of ribs can be 2. The lower inner wall spiral rib 3 is set within the 180-degree arc-shaped inner wall area at the bottom of the tube. The rib height can be 1.5 mm, the spiral angle can be 30 degrees, the pitch can be 120 mm to 150 mm, and the number of ribs can be 3 or 4. The lower inner wall spiral rib 3 is higher and denser than the upper inner wall spiral rib 2 to accommodate the characteristics of higher liquid phase density and the need for stronger rotational induction.

[0027] like Figure 1 The microgrooves 8 on the focusing side are arranged within an arc-shaped area of ​​approximately 150 degrees on the bottom of the outer wall of the tube body 1, extending axially along the tube body. The microgrooves can be rectangular or V-shaped, with a width of 0.4 mm, a depth of 0.8 mm, and a spacing of 1.2 mm. The microgrooves can be formed using a fiber laser or wire EDM, and then electrochemically polished to remove slag and burrs.

[0028] During manufacturing, a spiral inner rib can first be formed on the inner wall of the seamless steel pipe using a customized drawing die. Then, the circumferential diversion baffle 4 is punched and fixed to the support boss on the inner wall of the pipe body 1. The circumferential diversion baffle 4 can be fixed by laser spot welding, and the welding position should ensure that the plane of the baffle and the phase of the spiral inner rib are stable. When adjacent pipe sections are butt-welded together, the phases of the circumferential diversion baffle 4 and the spiral inner rib of each pipe section should be aligned. After connection, the pipe body should be flushed to remove processing debris.

[0029] During operation, the feedwater enters the preheating section in a single-phase liquid state, and the circumferential flow divider 4 and the spiral inner ribs only form controllable additional resistance. When the working fluid enters the evaporation section, a large number of microbubbles are generated on the heating surface where the microchannel group 8 on the concentrating side is located; the spiral inner ribs 3 on the lower inner wall induce the liquid phase to form a rotating liquid film flow in the liquid phase channel 7, and the microbubbles are carried to the vicinity of the circumferential flow divider 4 and dispersed into the vapor phase channel 6 through the through holes; the spiral inner ribs 2 on the upper inner wall induce the vapor flow in the vapor phase channel 6 to rotate and move forward, so that the microdroplets tend to the wall surface and are not easy to agglomerate into liquid plugs.

[0030] In one embodiment, the heat collection area of ​​a linear Fresnel DSG steam generation system in a textile factory is 12,000 square meters, the steam output is 4 tons / hour, the output is 1.6 MPa saturated steam, and the length of a single absorber tube is 24 m. After adopting the absorber tube of this embodiment, under the same statistical caliber, the pressure drop of a single 24 m evaporation section increased from 28 kPa to 32 kPa, the root mean square value of the vibration acceleration of the evaporation section decreased from 8.5 m / s² to 1.6 m / s², and the fluctuation of the outlet steam dryness decreased from ±12% to ±4%. The above data are the test results of a specific engineering embodiment and do not constitute a limitation on all operating conditions.

[0031] For the modification of existing mirror fields, the circumferential flow divider 4 and at least part of the spiral inner ribs can be made into a core tube structure that can be inserted from the end of the tube body 1. After the inserted core tube is in place, its through holes, upper swirl structure, and lower swirl structure remain consistent with... Figure 1 The working path shown is consistent, thus achieving two-phase flow vibration suppression modification without removing the original heat absorption tube.

Claims

1. A linear Fresnel vapor-suppressing and vibration-damping endothermic tube, comprising a horizontally arranged tube body, a circumferential flow divider, spiral inner ribs, and a group of microgrooves on a concentrating side. The circumferential flow divider is arranged axially inside the tube body and divides the inner cavity of the tube body into an upper vapor phase channel and a lower liquid phase channel. The circumferential flow divider has through holes connecting the vapor phase channel and the liquid phase channel. The spiral inner ribs are respectively formed on the upper inner wall corresponding to the vapor phase channel and the lower inner wall corresponding to the liquid phase channel. The group of microgrooves on the concentrating side is formed on the concentrating heating side of the outer wall of the tube body. The spiral inner ribs on the lower inner wall are used to induce liquid phase rotation and allow the heated bubbles to enter the vapor phase channel through the through holes. The spiral inner ribs on the upper inner wall are used to induce vapor phase rotation to form a rotating vapor flow carrying microdroplets.

2. The linear Fresnel steam-generating and vibration-suppressing heat absorber tube according to claim 1, wherein, The circumferential flow divider is located above the horizontal mid-surface of the pipe body, such that the cross-sectional area of ​​the vapor phase channel accounts for 25% to 35% of the total cross-sectional area of ​​the inner cavity of the pipe body, and the cross-sectional area of ​​the liquid phase channel accounts for 65% to 75% of the total cross-sectional area of ​​the inner cavity of the pipe body.

3. The linear Fresnel steam-generating and vibration-damping heat absorber tube according to claim 1, wherein, The circumferential diversion baffle is a stainless steel sheet with a thickness of 0.8 mm to 1.2 mm. The through hole is a circular hole or a slit hole. The opening ratio of the through hole is 15% to 25%, and the diameter of the circular hole is 3 mm to 5 mm.

4. The linear Fresnel steam-generating and vibration-suppressing heat absorber tube according to claim 1, wherein, The circumferential diversion baffle is continuously arranged along the axial direction of the pipe body, or it is composed of multiple segmented baffles with a length of 500mm to 1000mm spaced apart along the axial direction of the pipe body, with a spacing of 50mm between adjacent segmented baffles.

5. The linear Fresnel steam-generating and vibration-suppressing heat absorber tube according to claim 1, wherein, The spiral inner ribs on the upper inner wall are arranged within the 180-degree arc-shaped inner wall range at the top of the tube. The rib height is 0.8mm to 1.2mm, the spiral angle is 30 degrees to 40 degrees, the pitch is 120mm to 180mm, and there are 2 ribs.

6. The linear Fresnel steam-generating and vibration-suppressing heat absorber tube according to claim 1, wherein, The spiral inner ribs on the lower inner wall are arranged within the 180-degree arc-shaped inner wall range at the bottom of the tube. The rib height is 1.2mm to 1.8mm, the spiral angle is 25 degrees to 35 degrees, the pitch is 100mm to 150mm, and the number of ribs is 3 to 4.

7. The linear Fresnel steam-generating and vibration-damping heat absorber according to claim 1, wherein, The microgroove group on the focusing side is located within an arc-shaped area of ​​approximately 150 degrees at the bottom of the outer wall of the tube body, and is composed of rectangular or V-shaped microgrooves extending along the axial direction of the tube body. The width of the microgrooves is 0.3 mm to 0.5 mm, the depth is 0.5 mm to 1.0 mm, and the spacing between the microgrooves is 1.0 mm to 1.5 mm.

8. The linear Fresnel steam-generating and vibration-damping heat absorber according to claim 1, wherein, The outer diameter of the tube is 38mm to 50mm, the wall thickness is 3mm to 4mm, and the material is 316L stainless steel or Incoloy 800H heat-resistant alloy.

9. The linear Fresnel steam-generating and vibration-damping heat absorber according to claim 1, wherein, The inner wall of the pipe is provided with a support boss for positioning the circumferential diversion baffle. The circumferential diversion baffle is fixed to the support boss by welding and the phase of the circumferential diversion baffle and the spiral inner rib are aligned when adjacent pipe sections are connected.

10. The linear Fresnel steam-generating and vibration-damping heat absorber according to claim 1, wherein, The circumferential flow divider and at least part of the spiral inner ribs are formed on a core tube that can be inserted from the end of the tube body to adapt to the modification of existing linear Fresnel mirror field heat absorber tubes.

Images