Research On The Dynamic Matching Optimization And Assessment Methods For Suction-lifting System Of Cutter Dredger

As one sort of the most widely-used ships in modern dredging engineering, cutter suction dredger can integrate soil excavation, the mixing of sand and water, slurry transportation the three working processes as a whole with a high efficiency and a good adaptability, working in such areas as the construction and maintenance of port navigation channel, land reclamation for coastal industry parks, flood control and desilting projects, environmental protection and improvement and the sea resources development. Suction-lifting system, the core parts of cutter suction dredger, is of wide area high energy consumption system, which is furnished with the transportation pipeline up to dozens of kilometers and several large-power centrifugal pumps and can consumes 80%-90% power of the all, therefore being much improvement for energy saving. Deep research on optimized matching between dredge equipments and dynamic working conditions can not only decrease dredging cost, energy consumption and working risk but improve efficiency, project management and the lifetime of dredge equipments.It is of paramount importance to work out one systematic matching and assessment method, which is based on hydraulic dredging mechanism and can optimize working conditions and power utility. The first optimization model between cutter and sand properties is presented in the dissertation with a good consideration of the influence of sand motion characteristics on its cutting. And then based upon output characteristics of the power, torque and speed of suction-lifting system when diesel and slurry pump unit is viewed as a whole, the matching between slurry pump and transportation can be well optimized. Resistance model of slurry transportation pipeline, as another vital content, is to analyze the impact factors and energy nodes of slurry transportation power consumption system, aiming to make sure a smooth, safe and economic operation with the lowest ratio of energy consumption.In this dissertation the research on dynamic matching optimization, which is a typical multi-level decision-making dynamic optimization problem involving complex impact factors and evaluation criteria, is divided into soil cutting, mud mixing and slurry delivery the three programs. With the dynamic programming method of multi-level fuzzy decision-making, a series of indexes such as smash degree of sediment particles, sand leakage ratio in the suction pipeline, energy efficiency of diesel engine, slurry pump cavitation limit value, transportation pipeline blockage risk indicator and power utility ratio, is constructed to form the evaluation mechanism of suction-lifting system. The system with a insight into dredging mechanism, which provides solid evidence for safe, accurate and environment-friendly dredging, can help engineers to make a scientific and quantitative evaluation on specific projects.The content of each chapter can be generalized as follows.The research background, purpose and significance is described in the first chapter, in which an overview of operating procedures, configuration and application areas, research results and focuses of cutter suction dredger at home and abroad is introduced and the content and research work of the dissertation is briefed.The second chapter gives a detailed description of the properties of sand and the law of solid-liquid two-phase flow, presents and analyzes the settling velocity of sand, which effects matching characteristics of the whole suction-lifting system as the key parameter. This chapter has laid a detailed theoretical basis for the following in-depth study of the research.As one body part, chapter 3 establishes several most critical matching optimization models of the suction-lifting system based on the dynamic characteristics of dredging equipments, including the matching model between sand cutting and cutter working parameters, the model between cutter and its electric drive system, the one between diesel engine and slurry pump unit and the transportation pipeline, which constitute the analysis model of suction-lifting system matching characteristics.Chapter 4, the other body part, suggests the multi-level dynamic programming method for fuzzy decision on matching optimization of suction-lifting system considering complex and volatile dredging conditions. In terms of the three aspects as slurry formation process, power supply of diesel engine and energy loss characteristics of transportation pipeline, matching indexes evaluation system of suction-lifting system is established in this chapter. In practical dredging projects, it is beneficial for engineers to figure out a construction plan based upon the above indexes, which can optimize slurry formation process and energy utility of the transportation pipeline.The last chapter, chapter 5, summarizes the research, the relative results and the prospects of researches in days to come.