Manufacturing method of a PVC-lined fiberglass reinforced plastic composite tank

Abstract

The technical problem to be solved by the present invention is to provide a manufacturing method for an inner-lined PVC fiberglass composite tank, in which an inner lining layer, a secondary inner lining layer, an intermediate layer and a strengthening layer are successively manufactured from the inside to the outside. The inner lining layer uses CPVC plates, the secondary inner lining layer uses PVC plates, and the two layers are bonded by a serrated clamp method, giving full play to the characteristics of the inner lining layer, effectively solving the problem that the inner lining layer is prone to cracking due to temperature influence, and being applicable to highly corrosive acids and strongly active oxidizing chemical media.

Description

Technical Field

[0001] The present invention relates to the field of processing and manufacturing of PVC-lined fiberglass reinforced plastic composite tanks, and particularly relates to a manufacturing method of a PVC-lined fiberglass reinforced plastic composite tank. Background Art

[0002] At present, the commonly used storage tanks for containing highly corrosive chemical media are divided into three types: steel storage tanks, plastic anti-corrosion storage tanks, and fiberglass reinforced plastic storage tanks. Steel storage tanks can be calculated or selected according to relevant standards. However, compared with storage tanks for ordinary media, steel storage tanks for highly corrosive chemical media need to adopt a larger corrosion allowance, are heavy in mass, have higher on-site transportation and installation costs, and have a short service life. Plastic anti-corrosion storage tanks have strong corrosion resistance, are convenient to operate, and are light in weight. However, plastic storage tanks are not strong enough and cannot withstand strongly oxidizing media, are extremely easy to break, and are dangerous. Ordinary fiberglass reinforced plastic storage tanks (material: FRP) are mainly used to store various low-concentration chemical media, ultra-pure water storage tanks, and extra-large drinking water tanks, etc., but are not suitable for sulfuric acid with a concentration above 70%, other highly corrosive acids, strongly active alkalis, oxidizing salts, and soluble organic solvents.

[0003] The current research discloses the development of a PP / GFRP external pressure storage tank. The inner lining layer uses a 5-mm-thick PP plate. The HBS-01 adhesive is selected for the PP layer and the GFRP layer. The fiberglass surface mat, fiberglass chopped strand mat, and 3201 vinyl resin are selected as the 1.5-mm secondary inner layer materials. The structural layer is wound with isophthalic heat-resistant resin and roving fiberglass. In this method, the relationship between the HBS-01 adhesive and the surface treatment temperature of PP is very large, and integral heating treatment cannot be adopted, resulting in more frequent equipment heating and more difficult overall bonding process of the equipment, leading to easy cracking of the inner lining layer and short service life. Moreover, in this method, the inner lining material used is a PP plate. The PP material storage tank can hold sulfuric acid with a concentration within 65% at the service temperature range (-20°C - +120°C), but is also not suitable for concentrated sulfuric acid and other chemical media such as oxidizing salts. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a manufacturing method of a PVC-lined fiberglass reinforced plastic composite tank. The inner lining layer, secondary inner lining layer, intermediate layer, and strengthening layer are sequentially manufactured from the inside to the outside. The inner lining layer uses a CPVC plate, the secondary inner lining layer uses a PVC plate, and the two layers are fitted by a serrated clamp method, giving full play to the characteristics of the inner lining layer, effectively solving the problem that the inner lining layer is easily cracked due to temperature influence, and being able to be applicable to highly corrosive acids and strongly active oxidizing chemical media.

[0005] The present invention is achieved by the following technical solutions:

[0006] A manufacturing method of a PVC-lined fiberglass reinforced plastic composite tank includes the following steps:

[0007] S1. Fabricate the inner lining layer: First, fabricate the tank bottom and tank top. According to the design requirements of the drawing, use water jet cutting to cut the CPVC board into multiple CPVC board cutting pieces, and use hot air welding to assemble the CPVC board cutting pieces to form a circular plate-shaped tank bottom and a conical tank top;

[0008] Then fabricate the cylinder section. After mating the cylinder coiling die with the CPVC board cutting pieces, send them into the heating furnace at the same time for one-time heating and forming;

[0009] Finally, use hot air welding to assemble each cylinder section;

[0010] S2. Fabricate the secondary inner lining layer: Apply PVC glue on the CPVC board of the inner lining layer, and then bond another layer of PVC board; The processing method of the PVC board is the same as that of the CPVC board in step S1. Open multiple U-shaped grooves on the CPVC board, and make multiple racks on the PVC board to make the inner lining layer and the secondary inner lining layer fit in a serrated clamp manner. Finally, use hot air welding for welding reinforcement to reduce cracks in the inner lining layer caused by temperature influence;

[0011] S3. Fabricate the intermediate layer: First, apply interfacial resin on the outer surface of the PVC board, then lay a layer of alkali-free chopped strand mat. The laying should be flat without wrinkles, and then apply another layer of interfacial resin. The interfacial resin is isophthalic acid / neopentyl glycol type unsaturated polyester resin, and use a pressure roller to flatten the surface;

[0012] S4. Fabricate the strengthening layer: After the interfacial resin in S3 is cured, start fabricating the strengthening layer. Assemble the cylinder section, tank bottom and tank top into an integral tank, and then alternately bond alkali-free chopped strand mat and apply bisphenol A epoxy vinyl ester resin layer on the surface of the intermediate layer. During this period, fully roll and press to drive out the broken bubbles, and the appearance is flat. After the bisphenol A epoxy vinyl ester resin layer is cured, roughen the resin surface and continue to apply resin until the thickness of the strengthening layer reaches the technical requirements;

[0013] Finally, use a spraying machine and a winding machine to synchronously spray and wind direct winding yarn on the outer surface of the tank body, so that the spraying yarn is tightened by the direct winding yarn before curing.

[0014] Further, in step S1, when the cylinder coiling die and the CPVC board cutting pieces are mated and sent into the heating furnace at the same time, use an electric heating furnace to fully heat the CPVC board cutting pieces, control the heating temperature at 120 - 140 degrees Celsius, and the holding time is at least 20 minutes.

[0015] Further, in step S2, open U-shaped grooves with a width of 10 mm and a depth of 3 mm every 1 m on the CPVC board, and the racks made on the PVC board have a width of 9 mm and a height of 3 mm.

[0016] Further, in step S3, when using a pressure roller to flatten the surface, the diameter of the bubbles is made less than 5 mm, and the number is reduced to an average of 1 per square meter.

[0017] Further, in step S4, on the surface of the intermediate layer, alkali-free chopped strand mat is alternately bonded and a bisphenol A epoxy vinyl ester resin layer is coated. After every 3 - 5 layers are coated, the curing time of the bisphenol A epoxy vinyl ester resin layer is 20 min - 30 min.

[0018] Further, in step S4, before the spraying machine sprays the injection yarn, resin, curing agent and accelerator should be mixed into the injection yarn.

[0019] The beneficial effects achieved by the present invention compared with the prior art are as follows:

[0020] 1. Using the manufacturing method of the inner-lined PVC fiberglass composite tank of the present invention, the inner lining layer, sub-inner lining layer, intermediate layer and strengthening layer are made from the inside to the outside in sequence. The inner lining layer uses CPVC board, the sub-inner lining layer uses PVC board, and the two layers are fitted by means of a serrated clamp, giving full play to the characteristics of the inner lining layer, effectively solving the problem that the inner lining layer is prone to cracking due to temperature influence, and being applicable to highly corrosive acids and strongly active oxidizing chemical media.

[0021] 2. When the cylinder coiling die and the CPVC board blanking part are fed into the heating furnace simultaneously, the CPVC board blanking part is fully heated by the electric heating furnace, with uniform heating and one-time forming, effectively avoiding the forming arc deviation and saving the correction process.

[0022] 3. An interface resin is used between the sub-inner lining layer and the strengthening layer to ensure close fitting between the sub-inner lining layer and the strengthening layer without delamination. A layer of alkali-free chopped strand mat is laid outside the interface resin, and the interface resin and the alkali-free chopped strand mat are alternately constructed, giving full play to the wetting ability of the interface resin for glass fiber.

[0023] 4. The spraying machine and the winding machine are used to synchronously spray injection yarn and directly wind continuous filament yarn on the outer surface of the tank body, so that the injection yarn is tightened by the directly wound continuous filament yarn before curing, and winding is carried out immediately after spraying, changing the traditional method of winding after the overall spraying is completed, effectively reducing the generation of gaps and improving the manufacturing quality of the storage tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the bottom assembly of the tank described in this embodiment;

[0025] Figure 2 It is a schematic diagram of the tank top of the present embodiment;

[0026] Figure 3 It is a schematic diagram of the cooperation between the cylinder section and the cylinder coiling die of the present embodiment;

[0027] Figure 4 It is a schematic diagram of the cylinder body assembled with cylinder segments described in this embodiment. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0029] In the description of the invention, it should be understood that the terms "front", "rear", "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on directions or positional relationships shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the invention. The invention is further described below in conjunction with the drawings and embodiments.

[0030] In order to overcome the problems existing in the background technology, this embodiment discloses a method for manufacturing a PVC-lined glass fiber reinforced plastic composite tank. The PVC-lined glass fiber reinforced plastic composite tank manufactured by the manufacturing method comprises an inner lining layer, a secondary inner lining layer, an intermediate layer and a reinforcing layer from the inside to the outside, which effectively solves the problem that the inner lining layer is easily cracked due to the influence of temperature, and can be applied to highly corrosive acids and highly active oxidizing chemical media. It includes the following steps:

[0031] S1. Making the inner lining: First, make the tank bottom and tank top. According to the design requirements of the drawings, use water jet cutting to cut the CPVC board to form multiple CPVC board blanks. Use hot air welding to assemble the CPVC board blanks to form a circular tank bottom and a conical tank top. Figure 1 As shown in the figure, the tank bottom is assembled from multiple blanks and fixed together by welding. Figure 2 As shown, the tank top is made by using a tool to pull up its middle position after layout, and directly forming the tank top cone instead of the original melon-shaped assembly welding method, so that the tank top is formed in one step, effectively reducing the number of welds and further reducing the risk of leakage.

[0032] Then make the tube section, such as Figure 3 As shown, the cylinder coil mold and the CPVC board blank are matched and sent into the heating furnace at the same time. The CPVC board blank is fully heated by the electric heating furnace. The heating temperature is controlled at 120-140 degrees Celsius and the insulation time is at least 20 minutes to make it evenly heated and formed in one time.

[0033] Finally, each cylinder section is assembled by hot air welding. For hot air welding, the welding rod grade is 5603, and the leg height of the fillet weld is 0.7 times the thickness of the thinner welded part. After the first pass of hot air welding is completed, the weld should be inspected by electric spark testing with a test voltage of 10 KV; after the second pass of welding is completed, the weld is again inspected by electric spark testing with a test voltage of 20 KV. As Figure 4 shown, the cylinder of the tank is formed;

[0034] S2. Fabricate the secondary lining layer: Apply PVC glue on the CPVC board of the lining layer, and then bond another layer of PVC board; The processing method of the PVC board is the same as that of the CPVC board in step S1. U-shaped grooves with a width of 10 mm and a depth of 3 mm are opened every 1 m on the CPVC board, and racks with a width of 9 mm and a height of 3 mm are made on the PVC board, so that the lining layer and the secondary lining layer are fitted in a serrated clamp type. Finally, hot air welding is used for welding reinforcement to reduce cracks generated in the lining layer due to temperature influence;

[0035] S3. Fabricate the intermediate layer: First, apply interfacial resin on the outer surface of the PVC board, then lay a layer of alkali-free chopped strand mat, and the laying should be flat without wrinkles. Then apply another layer of interfacial resin. The interfacial resin is isophthalic acid / neopentyl glycol type unsaturated polyester resin, and a roller is used to flatten the surface so that the bubble diameter is less than 5 mm and the number is reduced to an average of 1 per square meter, greatly reducing the number of bubbles and ensuring close fitting between the FRP and the PVC without delamination;

[0036] S4. Fabricate the strengthening layer: After the interfacial resin in S3 is cured, start fabricating the strengthening layer. Assemble the cylinder section, tank bottom and tank top into an integral tank, and then alternately bond alkali-free chopped strand mat and apply bisphenol A epoxy vinyl ester resin layer on the surface of the intermediate layer to fully utilize the wetting ability of the interfacial resin for glass fiber. During this period, the crushed bubbles are driven out by sufficient rolling, and the appearance is flat. After every 3 - 5 layers are applied, the curing time of the bisphenol A epoxy vinyl ester resin layer is 20 min - 30 min. After the bisphenol A epoxy vinyl ester resin layer is cured, the surface of the resin is roughened, and the resin is continuously applied until the thickness of the strengthening layer reaches the technical requirements;

[0037] Finally, prepare a winding machine, pour the prepared resin into the sizing tank. The winding machine is used to wind the direct winding yarn, and prepare a spraying machine. The spraying machine is used to spray the spray yarn. The internal spray coating of the spraying machine is the spray yarn mixed with resin, curing agent and accelerator. Use the spraying machine and the winding machine to synchronously spray the spray yarn and wind the direct winding yarn on the outer surface of the tank body, so that the spray yarn is tightened by the direct winding yarn before curing. By changing the traditional method of winding after the overall spraying is completed, the generation of gaps is effectively reduced, and the manufacturing quality of the storage tank is improved.

[0038] Comparative Example 1:

[0039] Preparation method of PP / GFRP external pressure storage tank: The PP inner lining layer uses a PP plate with a thickness of 5 mm. HBS-01 adhesive is used between the PP layer and the GFRP layer. Glass fiber surface mat, glass fiber chopped strand mat and 3201 vinyl resin are selected as the 1.5 mm sub-inner layer materials, and the structural layer is wound with isophthalic heat-resistant resin and roving fiberglass. The inner lining material used in this method is a PP plate. The PP material storage tank can hold sulfuric acid with a concentration within 65%, but it is also not suitable for concentrated sulfuric acid, other highly corrosive acids, strongly active alkalis, oxidizing salts and other chemical media.

[0040] Comparative example 2:

[0041] Preparation method of steel-lined plastic storage tank: The inner lining layer uses 16-20 mm PE plastic, and a turtleback mesh lining is carried out between the inner lining layer and the strengthening layer. The strengthening layer uses carbon steel material. The inner lining material used in this method is PE plastic, which can hold concentrated sulfuric acid with a concentration within 98%, other highly corrosive acids, strongly active alkalis, oxidizing salts and other chemical media. However, the equipment is heavy and not conducive to transportation and installation, and compared with fiberglass, the equipment has lower strength and poor heat insulation.

[0042] Comparative example 3:

[0043] The preparation method of a glass fiber reinforced composite polyvinyl chloride pipe is divided into five layers: polyvinyl chloride pipe, outer film of polyvinyl chloride pipe, preservative layer, adhesive layer and glass fiber, and is used for the transportation of corrosive media under higher pressure.

[0044] The inner lining layer and the strengthening layer of the tanks produced by the methods provided in the examples and comparative examples 1, 2, and 3 were statistically compared. The specific results are shown in the following table.

[0045]

[0046] It can be seen from the above table that the inner lining PVC fiberglass composite pipe prepared by using the production method of the inner lining PVC fiberglass composite tank described in the present invention is mainly used for chemical media such as concentrated sulfuric acid, other highly corrosive acids, strongly active alkalis, oxidizing salts, etc. The concentration of concentrated sulfuric acid that can be held can reach 98%, which solves the problems of poor corrosion resistance and short service life of ordinary equipment.

Claims

1. A manufacturing method of a PVC-lined fiberglass reinforced plastic composite tank, characterized in that, It includes the following steps: S1. Fabricate the inner lining layer: First, fabricate the tank bottom and tank top. According to the design requirements of the drawing, use water jet cutting to cut the CPVC board into multiple CPVC board cutting pieces, and use hot air welding to assemble the CPVC board cutting pieces to form a circular plate-shaped tank bottom and a conical tank top; Then fabricate the cylinder sections. After matching the cylinder coiling die with the CPVC board cutting pieces, send them into the heating furnace at the same time for one-time heating and forming; Finally, assemble each cylinder section by hot air welding; S2. Fabricate the secondary inner lining layer: Apply PVC glue on the CPVC board of the inner lining layer, and then bond another layer of PVC board; The processing method of the PVC board is the same as that of the CPVC board in step S1. Open multiple U-shaped grooves on the CPVC board, and make multiple racks on the PVC board, so that the inner lining layer and the secondary inner lining layer are fitted in a serrated clamp type, and finally use hot air welding for welding reinforcement to reduce cracks generated in the inner lining layer due to temperature influence; S3. Fabricate the intermediate layer: First, apply interfacial resin on the outer surface of the PVC board, then lay a layer of alkali-free chopped strand mat. The laying should be flat without wrinkles, and then apply another layer of interfacial resin. The interfacial resin is isophthalic acid / neopentyl glycol type unsaturated polyester resin, and use a pressure roller to flatten the surface; S4. Fabricate the strengthening layer: After the interfacial resin in S3 is cured, start fabricating the strengthening layer. Assemble the cylinder sections, tank bottom and tank top into an integral tank, and then alternately bond alkali-free chopped strand mat and apply bisphenol A epoxy vinyl ester resin layer on the surface of the intermediate layer. During this period, fully roll to drive out the broken bubbles and make the appearance flat. After the bisphenol A epoxy vinyl ester resin layer is cured, roughen the resin surface and continue to apply resin until the thickness of the strengthening layer reaches the technical requirements; Finally, use a spraying machine and a winding machine to synchronously spray spray yarn and wind direct winding yarn on the outer surface of the tank body, so that the spray yarn is tightened by the direct winding yarn before curing.

2. The manufacturing method of the inner-lined PVC fiberglass reinforced plastic composite tank according to claim 1, characterized in that, In step S1, when the cylinder coiling die and the CPVC board cutting pieces are matched and sent into the heating furnace at the same time, use an electric heating furnace to fully heat the CPVC board cutting pieces, control the heating temperature at 120 - 140 degrees Celsius, and the heat preservation time is at least 20 min.

3. The manufacturing method of the inner-lined PVC fiberglass reinforced plastic composite tank according to claim 1, characterized in that, In step S2, open U-shaped grooves with a width of 10 mm and a depth of 3 mm every 1 m on the CPVC board, and the racks made on the PVC board have a width of 9 mm and a height of 3 mm.

4. The manufacturing method of the inner-lined PVC fiberglass reinforced plastic composite tank according to claim 1, characterized in that, In step S3, when using a pressure roller to flatten the surface, make the bubble diameter less than 5 mm, and the number is reduced to an average of 1 per square meter.

5. The manufacturing method of the inner-lined PVC fiberglass composite tank according to claim 1, characterized in that, In step S4, alternately bond alkali-free chopped strand mat and apply bisphenol A epoxy vinyl ester resin layer on the surface of the intermediate layer. After applying 3 - 5 layers each time, the curing time of the bisphenol A epoxy vinyl ester resin layer is 20 min - 30 min.

6. The manufacturing method of the inner-lined PVC fiberglass reinforced plastic composite tank according to any one of claims 1-5, characterized in that, In step S4, before the spraying machine sprays the spray yarn, resin, curing agent and accelerator should be mixed into the spray yarn.

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