Large-scale algal cultivation plays a vital role in the aquaculture industry in China. Saccharina japonica, the predominant species, accounted for 61.4% of the national total algal aquaculture output of 3.0294 million tons in 2024. The harvest window for S. japonica is notably brief, typically lasting only to 2‒3 months. Freshly harvested kelp has a very high moisture content (approximately 90% wet basis), necessitating immediate primary processing to prevent spoilage and facilitate storage and subsequent processing. The two primary traditional pretreatment methods are sun-drying and salting. Although salting is efficient and weather-independent, making it suitable for large-scale processing, sun-drying remains a crucial cost-effective method in regions with ample sunlight owing to its near-zero energy consumption. Sun-drying is mainly categorized into hang-drying and pavement drying. The practice of hang-drying is space efficient and yields cleaner products; however, it has several disadvantages, including longer drying cycles, severe product curling, and polysaccharide leaching. Pavement drying offers a higher drying efficiency, but traditional direct sand-beach spreading leads to significant sand contamination, relegating its use primarily to chemical feedstocks or abalone feed. Improved pavement-drying techniques, such as the use of pebble beds or polyethylene nets, have demonstrated the potential to produce high-quality dried kelp but remain labor intensive. The fundamental challenges in traditional sun-drying methods include high labor intensity and low operational efficiency, which severely constrain industrial-scale production. This issue is further exacerbated by the declining fishery labor force. Consequently, mechanization of the sun-drying process has become an urgent priority. Significant research efforts have been directed towards mechanizing hanging-drying, leading to the development of various systems, such as automatic lifting and hanging systems, multi-layer tray drying systems, and long-line continuous drying systems. These innovations have successfully mechanized the practice of hang-drying. In contrast, there are few studies of mechanized solutions geared towards pavement drying. Existing techniques involve fixed net frames that require laborers to traverse long distances for spreading and retrieval, thus failing to alleviate the core issue of labor intensity. Furthermore, a critical technological bottleneck for efficient and continuous mechanized pavement drying is the conveyor system. Although chain-and-net structures offer reliable performance, their prohibitively high manufacturing costs limit their large-scale application. In this study, we aimed to develop a novel continuous conveyor-type kelp pavement-drying equipment to overcome the limitations of existing methods. The primary objectives were to significantly reduce labor intensity, achieve automated operation for both spreading and retrieval, ensure high drying quality without sand contamination, and provide a cost-effective alternative to expensive chain-based conveyor systems, thereby facilitating widespread industrial adoption. A prototype "Continuous Conveyor Net for Pavement-Drying of Kelp" was designedand fabricated. The core design incorporates a steel wire rope net belt as the conveying medium and an automated cover net system. The key components include a synchronous anti-slip device with dual-groove pulleys and steel wire ropes, the rope-net structure, a tail drum assembly, dual-roller support frames, and a cover net mechanism. A structural analysis was conducted by focusing on the stress distribution within the steel wire ropes and the tensioning mechanics of the drum assembly. Extensive pilot-scale trials were performed to evaluate the system performance. A 50 m long prototype was tested under varying mass loads (20‒100 kg) to measure the resultant dragging tension on the steel wire ropes. The synchronization performance of the dual-groove pulley anti-slip device was quantified by measuring the relative displacement between two steel wire ropes during operation. The wind-resistance capability of the automatically deployed cover net was rigorously tested. Pilot-scale trials yielded critical operational data and validated the effectiveness of the design. The dragging tension on the steel wire ropes in the 50 m prototype correlated linearly with the applied load, ranging from 836.43‒1068.3 N for masses between 20‒100 kg. Regression analysis of these data produced a predictive trendline formula (y = 2.8984x + 778.46), which serves as a foundational basis for configuring the dragging force and motor power requirements for scaling the equipment to longer lengths, such as a projected 300 m system. The synchronous anti-slip device demonstrated exceptional performance, maintaining the relative displacement between the two steel wire ropes within a tight tolerance of ±4 mm throughout the operation, ensuring smooth, synchronized movement without slippage and guaranteeing operational reliability. The automated cover net system proved highly effective, withstanding wind speeds of up to 13.8 m/s, thereby effectively preventing wind from dislodging or disrupting the drying kelp and eliminating a major source of product loss and contamination.
Operationally, the equipment enables a stationary work mode. The laborers remain at a fixed location to place fresh kelp onto the net belt, which then automatically conveys the material distally until the entire length of the belt is evenly covered. The cover net is deployed automatically. After drying, the process is reversed, and the dried kelp is conveyed back to the starting point for easy collection. This eliminates the need for workers to walk long distances across large drying fields, fundamentally reducing the labor intensity. Compared to hang-drying, pavement-drying achieved with this equipment resulted in superior product flatness, faster drying rates, and crucially, complete absence of sand or other particulate contaminants due to the elevated net belt, leading to a significant enhancement in the final product quality. A key economic advantage was confirmed: the manufacturing cost of the critical components of the steel wire rope net belt structure is substantially lower than that of an equivalent chain-and-net structure. For a 300 m system, this cost reduction was quantified at approximately 111,000 Yuan, underscoring the excellent cost effectiveness and potential for large-scale implementation. In summary, we successfully developed and validated a continuous conveyor net pavement-drying system that effectively addresses the major challenges associated with traditional kelp pavement drying. The system offers significant advantages by integrating a steel wire rope net belt with a synchronous anti-slip device and an automated wind-resistant cover net. It achieves a substantial reduction in labor intensity through automated conveying, enhances the drying quality and efficiency, prevents sand contamination, and offers a cost-effective solution superior to chain-based alternatives. These findings provide a reliable technical and theoretical foundation for the design and power configuration of large-scale systems. This technology represents a promising and practical solution for the mechanized, high-quality pavement-drying of kelp, with strong potential for widespread application and a positive impact on the industry.
1 结构与方法
2 中试试验与分析
3 经济性分析
