Why Do Offshore And Onshore Wind Power Use Pultrusion Technology? What Are The Advantages of Pultruded Boards?

 

Application of Pultruded Board in Blade Industry:

The main beam of the blade (also called beam cap or beam) is the main load-bearing member or main structural member in the wind turbine blade, similar to the keel of a ship. If the main beam breaks, the entire blade will also break.

 

Initially, the main beam used the vacuum infusion method, that is, laying glass fiber layer by layer on it, and then infusing resin; later, prepreg appeared. Whether it is glass fiber or carbon fiber, the prepreg is laid layer by layer, and the product is formed after vacuum membrane pressure maintenance.

 

The current process is to first pultrude into a certain length of pultruded board, with a common cross-sectional size of 120 mm × 5 mm. During the production process, the pultruded boards are pieced together, and a cloth layer of certain specifications is laid in the middle. Then they are bundled together and put into the blade, and infused together with the blade. After infusion, demolding becomes the structural part inside the blade.

 

Reasons for Offshore And Onshore Wind Power to Use Pultrusion Technology:

 

 

1) The Pultrusion Process Ensures A High Fault Tolerance Rate For The Product.

In the past, whether the infusion process or prepreg was used for production, if there were defects somewhere during the production process, the impact on the main beam would be fatal. For example, if the main beam is 80 meters long and 60 centimeters wide, as long as there are defects somewhere, this main beam will have safety hazards.

 

However, if a problem or defect occurs on a pultruded board during the production process, the pultruded board can be scrapped and replaced with a new one. This means that even if there is a problem with the main beam of the blade during the assembly process, it only needs to replace the problematic pultruded board, and it will not affect other pultruded boards. The cost of scrapping a pultruded board is much lower than that of scrapping the entire main beam.

 

2) The Pultrusion Process Makes The Main Beam Structure Stronger.

Because the fiber content of the pultrusion process, the amount of yarn and resin used can be controlled and adjusted, and the yarn content can reach 70% (volume content), but the yarn content of vacuum infusion can only reach 60% at most. The higher the fiber content, the better the mechanical properties or load-bearing state of the main beam.

 

At present, the length of pultruded plates used in onshore wind power is mostly between 80 meters and 97 meters, such as Shanghai Electric has 85 meters, 89 meters, and 90 meters; Dongfang Electric has 90 meters and 91 meters; Goldwind and Zhongke Yuneng mainly promote blades with a blade shape of 93 meters; Yunda has 92 meters and 97 meters.

 

Among the blades of 80 meters to more than 90 meters, except for the need to use vacuum infusion or prepreg for production due to contract signing, or due to some economic reasons, basically 98% of the blades are produced by pultrusion. Including the 99-meter blades of offshore wind power and the 123-meter blades of Goldwind, they also use pultrusion. Blades are available in carbon plates and glass fiber plates, and there is also a certain gap depending on the blade shape.

 

Downstream Carbon Plate Industry’s Planning for Pultruded Materials:

Sinoma Science and Technology, Goldwind Science and Technology, and Zhongfu Lianzhong all control some pultruded plate manufacturers or produce pultruded plates independently. For example, Zhongfu Lianzhong’s subsidiary Fengdian Technology has begun to produce pultruded plates and wind turbine blades; Mianyang and Huamei have carried out strategic cooperation; Sany Heavy Industry and Fengdu New Materials have carried out strategic cooperation, etc., all of which indirectly illustrate the importance of pultruded plates to wind turbine blades.

 

Technical Situation Of Pultruded Beams:

According to the resin classification, most manufacturers now use epoxy resin technology. At the same time, everyone is actively developing polyurethane pultrusion technology. Compared with epoxy resin, polyurethane resin has a lower price and is more suitable for the continuous decline in installed prices in the future wind power industry. However, in a short period of time, polyurethane resin has higher requirements for materials and moisture content in the air. In the next 3 to 4 years, epoxy resin will still be the mainstream.

 

Material Manufacturers: Domestic Pultrusion Manufacturers of Glass Fiber are Mainly Taishan Fiberglass, Chongqing International, China Jushi, and foreign OC companies.

 

1) In terms of carbon fiber, foreign companies mainly include Zoltek and Toray, and domestic companies mainly include Jilin Guoxing, Jilin Baojing, Zhejiang Jinggong, Jiangsu Hengshen, Weihai Guangwei and other companies. Among them, Guoxing, Hengshen and Guangwei can produce yarn, pultruded plates and some carbon fiber products. Guangwei’s fishing rod products are very popular. Jilin Guoxing has invested a lot of energy and funds in carbon fiber and carbon fiber carbonization in recent years.

 

2) In terms of epoxy resin, it is mainly Taiwan Shangwei, Shanghai Daosheng Tianhe, Shanghai Huibai, and Sichuan Dongshu. At present, it is mainly the pultrusion process of epoxy system. There are few polyurethane manufacturers, mainly Shanghai Covestro. The year before last, Covestro, Shanghai Goldwind and Zhongfu Lianzhong jointly developed a pure polyurethane wind turbine blade with a length of more than 60 meters, which accumulated technology for the future development of polyurethane wind turbine blades.