Preparation method of PTFE-based membrane for preventing and removing ices covering wind turbine blades and use thereof

Abstract

A preparation method of a polytetrafluoroethylene (PTFE)-based membrane for preventing and removing ices covering wind turbine blades is provided and the method comprises: preparing a membrane into a PTFE rod material with polymerized monomers by using monomer polymerization methods such as blending, pre-compressing and pushing; making the membrane into a PTFE-based homogeneous membrane with micropores and nano and micron scale concave-convex geometrical ultra-structure morphologies under the condition that the membrane is cracked to generate a laminar exfoliated fabric-like structure in the hot calendaring process of the PTFE rod material by using a hot calendaring and fusion polymerization method; and applying the PTFE-based homogeneous membrane to blades of a large wind turbine in operation.

Claims

1. A method of making a polytetrafluoroethylene (PTFE)-based membrane for preventing and removing ice covering wind turbine blades, comprising the following steps: infiltrating PTFE resin powder with vinyl silicone oil, wherein a mass ratio of the vinyl silicone oil to the PTFE resin is (2-3):100, blending the PTFE resin powder and the vinyl silicone oil at room temperature to prepare a blended resin powder, pre-compressing the blended resin powder in a pre-compressing material barrel at a temperature of 60-90 C. under a pressure of 5-8 MPa and fusion polymerizing the PTFE resin and vinyl silicone oil monomers to prepare a monomer polymerized blank rod material, hot pushing the monomer polymerized blank rod material in a hot pushing material barrel at a temperature of 60-90 C. under a pressure of 5-8 MPa to prepare a membrane rod material, subjecting the prepared membrane rod material to micro-scale polymerization hot calendering in a hot calendering machine, wherein a gap distance between upper and lower oil-heated pressure calendering rollers of the hot calendering machine is set as a thickness of a membrane to be prepared, and temperatures of the calendering rollers are 60-90 C., and extruding the membrane rod material through the gap between the calendering rollers at a rate of 20-30 m/min under a rotation of the calendering rollers while uniformly extending the membrane rod material toward two sides of the hot calendering machine under an action of temperature and hot calendering stretching, wherein the membrane is split to generate a structure resembling a fabric after laminar exfoliation of the membrane to prepare a homogeneous PTFE-based membrane with a set thickness, wherein a contact angle between water beads and a surface of the membrane is 115.89-125.46, a surface morphology of the membrane is exhibited as a micro concave-convex structure with an average size of 10-20 micrometers, a height of 8-10 micrometers and a spacing of 20-30 micrometers, which is uniformly distributed in longitudinal and latitudinal directions.

2. A method of applying a PTFE-based membrane for preventing and removing ice covering wind turbine blades made according to the process of claim 1, comprising: polishing a surface of a wind turbine blade with a hand-held polishing machine to remove a part of aged coating pasted on a base layer surface of the blade and to provide the base layer of the blade with a flatness and finish degree, so as to meet pasting requirement conditions of the PTFE-based membrane; cutting a plurality of membranes horizontally along an angle of attack, a deflection and a curvature of an airfoil starting from a front edge of a tip of the blade according to a width of each membrane, wherein each membrane is cut separately to conform to the airfoil, the angle of attack, the deflection and a size of the blade; pasting each membrane from an SS surface of a rear edge of the blade to a PS surface of a front edge of the blade, wherein a membrane on the PS surface of the front edge is overlapped on a membrane on the SS surface of the rear edge, and membrane overlaps are horizontally staggered; horizontally winding a plurality of wound membranes on the blade, wherein winding each respective wound membrane is performed while removing a release paper on a surface of the respective wound membrane, directing the respective wound membrane between clamp rollers of a membrane pasting tool, and pulling the pasting tool to apply a tension force to the respective wound membrane; wherein horizontally winding further comprises: using a vertical and a horizontal edge of a last wound membrane pasted on the tip of the blade as a winding and pasting reference line, slowly spreading a respective wound membrane for winding and pasting by aligning the respective wound membrane with the reference line, removing air between the respective wound membrane and the base layer uniformly using a membrane pasting scraper according to a width of the whole respective wound membrane from a starting portion to a rear of a pasted surface of the respective wound membrane in a non-spread direction, forcefully and firmly pasting the respective wound membrane on the surface of the blade while the air between the respective wound membrane and the base layer is removed, and horizontally overlapping the respective wound membrane on a pasted membrane on the tip-of the blade, wherein all horizontal overlaps of the wound membranes are arranged on the SS surface of the rear edge of the blade; cutting and digging out a pasted membrane at a lightning arrester of the blade to expose the lightning arrester, and compacting and flattening the pasted membrane; carefully checking each membrane overlap, and if a respective membrane overlap is not tight, compacting and flattening the respective membrane overlap so as to avoid wrinkling, bulging, blistering, and unevenness; and if a membrane portion is scratched during construction, cutting a whole width membrane, and horizontally winding and pasting the whole width membrane on a surface of the whole scratched portion to repair the scratched portion.

3. The method according to claim 2, wherein an overlapping width between respective wound membranes is 10-40 mm in the horizontally overlapping step.

4. The method according to claim 2, wherein the horizontally staggered membrane overlaps are overlapped by 150-200 mm, the horizontal wound membrane overlaps are overlapped in a longitudinal direction by 10-40 mm, and a second membrane is longitudinally overlapped and pressed on an 8-10 mm edge of a first membrane by taking a 8-10 mm overlapped edge of the first membrane as a reference line.

5. The method according to claim 4, wherein each membrane is applied without forceful and horizontal stretching to avoid shrinking of a respective membrane after being stretched, and each membrane is pasted in a smooth state.

6. The method according to claim 4, wherein when a pasted membrane is wrinkled and hollowed or the pasted membrane is irregular or deformed due to non-alignment with the reference line, a whole non-spread part of the pasted membrane is slowly lifted, and then the membrane part is re-pasted to prevent a pasting quality of the membrane part from being influenced.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a nano and micro concave-convex geometric ultra-structure morphology of a surface of a membrane under a scanning electron microscope (SEM).

(2) FIG. 2 shows a membrane surface-water contact angle under a KRUSS DSA-100 contact angle tester.

(3) FIG. 3a-FIG. 3f show an engineering application method on a wind turbine generator blade.

DETAILED DESCRIPTION

Example 1

(4) A preparation method of a PTFE-based membrane provided in this example comprises the following steps:

(5) (1) preparing a membrane rod material by blending, pre-compressing and pushing

(6) a PTFE resin was infiltrated with vinyl silicone oil, a mass ratio of vinyl silicone oil to PTFE resin was 2.5:100, the vinyl silicone oil generated an affinity group with the PTFE diffusion resin, promoted the PTFE diffusion resin to generate an adhesion affinity force with polyester adhering glue, blending was conducted at room temperature, a blended resin powder was prepared by fusion polymerization of PTFE resin+vinyl silicone oil monomers; the blended resin powder was pre-compressed in a pre-compressing material barrel at the temperature of 60 C. under the pressure of 5 MPa to prepare a monomer polymerized blank rod material based on PTFE monomer fusion polymerization; the blank rod material based on PTFE monomer fusion polymerization was subjected to hot pushing in a hot pushing material barrel at the temperature of 60 C. under the pressure of 8 MPa to prepare a 17 mm membrane rod material based on PTFE monomer fusion polymerization.

(7) (2) preparing a membrane by hot calendaring

(8) the prepared membrane rod material based on PTFE monomer fusion polymerization was subjected to micro-scale polymerization hot calendaring in a hot calendaring machine, a gap distance between two upper and lower oil pressure calendaring rollers of the hot calendaring machine was set as a thickness (such as 80 um, 100 um or 120 um) required for the membrane based on PTFE monomer polymerization, the temperatures of the calendaring rollers were 60 C., the 17 mm membrane rod material based on PTFE monomer fusion polymerization was extruded from the gap between the calendaring rollers at the rate of 25 m/min under the clockwise rotation of the calendaring rollers while uniformly extending toward two sides under the action of temperature and hot calendaring stretching, and the membrane is split to generate a fabric-like structure after laminar exfoliation to prepare a homogeneous PTFE-based membrane with a set thickness.

(9) the density of the PTFE-based membrane was 2.1 kg/m3, as shown in FIG. 2, a contact angle between water beads and the surface of the membrane is 115.89-125.46, as shown in FIG. 1, the surface morphology of the membrane was exhibited as a micro concave-convex structure with an average size of 15 um, a height of 9 um and a spacing of 15 um under the stereo imaging of a scanning electron microscope, which can be uniformly distributed in a longitude and latitude direction.

(10) Various properties of 5 PTFE membrane samples prepared by the above method were tested. Results are as follows: {circle around (1)} the average thickness of the membrane is 100 um; {circle around (2)} the average weight of the membrane is 210 g/m2; {circle around (3)} the adhesive peel strength is 50 N, and 180 adhesive peel strength is 1000 N/m; {circle around (4)} through a 14400 h xenon lamp aging test, a freeze-thaw cycle performance test (temperature: 60 C.-150 C., humidity: 5-98%), an ozone aging test, an ultraviolet aging test, an artificial atmosphere corrosion and sea salt solution immersion test, the average tensile strength before and after aging is 25 MPa, the average elongation is more than 90%, and no aging phenomenon occurs; {circle around (5)} by using the GB/T 9266-2009 Determination of the Washability of Building Exterior Wall Coatings, after 37 times/min cyclic reciprocating friction for 40,000 times, there is no roughness on the surface of the membrane, no damage to exposed substrate was observed, and wear resistance is strong; {circle around (6)} a dynamic wind pressure test platform is used to simulate the wind speed of 36.9 m/s (12-level typhoon) to test rain wash resistance, and there is no roughness on the surface of the membrane through 1000 h strong wind speed blowing water test, and the membrane has a good rain erosion property; {circle around (7)} as shown in FIG. 1, the surface morphology of the membrane is tested by scanning electron microscope (SEM), and the surface morphology of the membrane is exhibited as a micro concave-convex structure with an average size of 20-40 um, a height of 10-20 um and a spacing of 30-50 um, which can be uniformly distributed in a longitude and latitude direction; {circle around (8)} as shown in FIG. 2, the contact angle between the membrane surface and the water drops measured by a water contact angle tester is between 115.89 and 125.46; {circle around (9)} the average surface roughness of the membrane measured by a surface roughness meter is 0.18 um.

Example 2

(11) This example provides use of a blade of a wind turbine in operation in example 1. According to the features of the chord length, deflection and curvature of the airfoil of the wind turbine blade and convenience of engineering construction, the tip of the blade is perpendicular to the ground and parallel to the tower body of the wind turbine, the blade penetrates through a high-altitude hanging basket, the adhesion of the membrane adopts a cutting, splicing and pasting method and a winding and pasting method which are performed simultaneously by four people, one of the four people is in charge of spreading the membrane and aligning a pasting reference line, one of the four people is in charge of finishing the smoothness of the membrane when being pasted, one of the four people is in charge of eliminating air between the membrane and a blade base layer and bonding with a pasting scraper, and one of the four people is in charge of cooperation between logistics services and construction. The process and method of the adhesion of the membrane are similarly suitable for blades of a wind turbine which is not in operation, specifically comprising:

(12) (1) polishing the surface of the blade

(13) the flatness and finish degree of the blade surface were treated with a hand-held polishing machine, and meanwhile a part of aged coating pasted on a base layer surface was removed, so as to meet the pasting requirement conditions of the PTFE-based nano functional composite membrane; and

(14) (2) pasting the membrane

(15) 1) cutting, splicing and pasting the tip of the blade

(16) as shown in FIG. 3a, the membrane was cut horizontally along the angle of attack, deflection and curvature of the airfoil starting from the front edge of the tip of the blade according to the width of the membrane, each membrane was cut separately into a membrane conforming to the airfoil, angle of attack, deflection and size, and then the cut membrane was pasted.

(17) when in adhesion, the membrane was pasted from the SS surface (leeward side) of the rear edge to the PS surface (windward side) of the front edge, the membrane on the PS surface of the front edge was overlapped on the membrane on the SS surface of the rear edge, the two membranes were horizontally overlapped and staggered by 15 cm and were not arranged at the same position; the horizontal overlapping thickness of the membrane was 150-200 mm, the edge of the adhered first membrane was taken as a reference line, the second membrane was overlapped and pressed on the 10 mm-40 mm edge of the first membrane, the two membranes were longitudinally overlapped by 10 mm-40 mm, and so on, inverted flashing of the membrane on the blades was not formed.

(18) 2) winding and pasting

(19) as shown in FIGS. 3b and 3c, at a 5 cm position from the tip of the blade to the middle of the blade, when the airfoil, chord length, deflection, curvature, and angle size of the blade were suitable for winding and pasting, and pasting was performed by using a manner that the membrane was horizontally wound on the blade.

(20) as shown in FIGS. 3e and 3f, when the membrane was wound and pasted, the membrane was spread by 200 mm, the release paper on the surface was torn off, and the membrane penetrated through the clamp rollers of a membrane pasting tool, a tension force was applied to the membrane by pulling via hands, and the release paper was torn off while the membrane was wound and pasted.

(21) the vertical and horizontal edge of the last membrane pasted on the tip of the blade was used as a winding and pasting reference line, and the membrane was slowly spread for winding and pasting by aligning the reference line, and air between the membrane and the base layer was uniformly removed using a membrane pasting scraper according to the width of the whole membrane from the starting portion to the rear of the pasted surface, namely, a membrane non-spread direction, while the membrane was forcefully and firmly pasted on the surface of the blade, and the air between the membrane and the base layer must be thoroughly removed; overlapping of the membrane on the upper layer pressed the overlapping surface of the overlapping part of the membrane on the lower layer, the overlapping thicknesses of the upper and lower two layers of membranes were 10 mm, namely, the wound and pasted membrane must be overlapped on the pasted membrane of the tip of the blade, and all the horizontal overlaps of the membrane, namely, the linkers between the membranes were all arranged on the SS surface of the rear edge of the blade.

(22) 3) treating the membrane at the lightning arrester of the blade

(23) as shown in FIG. 3d, the membrane was directly covered and pasted from the surface of the lightning arrester, before the pasting of the whole membrane was ended, the membrane covering the lightning arrester was cut and dug out one by one to expose the lightning arrester, and the membrane at the seam was compacted and flattened.

(24) 4) overlapping of the membrane and treatment of the linker

(25) whether the pasting at the overlapping position was tight was carefully checked, and if the overlapping was not tight, compaction and flattening was timely performed, so as to avoid wrinkling, bulging, blistering, and unevenness.

(26) 5) repairing the damaged membrane

(27) if the membrane was scratched during the construction, a membrane with the entire width was cut, and horizontally wound and pasted on the surface of the whole scratched part for repairing.

(28) In the above pasting process, the membrane was strictly forbidden to be horizontally stretched to avoid that the membrane was wrinkled after being stretched, the membrane must be pasted in a natural and smooth state. When wrinkling and hollowing occurred or the membrane was not smooth or deformed without aligning the reference line, the whole membrane that was not spread should be slowly lifted to a position where wrinkling and hollowing occurred, and then was pasted again, so as not to affect the pasting quality of the membrane.

(29) In the disclosure, the membrane is prepared into a concave-convex geometric ultra-structure surface morphology with nano and micro dimensions on the basis of sufficiently utilizing the low surface tension and high lubricating property of the PTFE-based material by using monomer fusion polymerization and micro polymerization technology methods, so that the membrane has more ultra-low surface solid tension, better hydrophobicity, higher non-adhesion property and high anti-fouling property on the basis of having a high lubricating surface.

(30) In addition to the above examples, other embodiments can also belong to the disclosure. Technical solutions formed by equivalent replacements or equivalent transformations are all included within the protective scope of the disclosure.