| Ultra high-pressure processing (UHP) is a new method of food processing where food is subjected to elevated pressures (approximately 1,000 to 10,000 atmospheres), to achieve microbial inactivation or to alter the food attributes without changing the food quality and natural freshness. The sea food processed by UHP can retain its freshness, extend shelf life and improve effect of preservation, so it provides an innovative way for deep processing of sea food.Compared with industrialization of ultra-high pressure food processing in modern countries, the investigation about UHP in China is mainly about basic application such as food sterilization, denaturation of biomacromolecule, and so on. Therefore, the study on design and manufacture of UHP equipments is of real significance. Based on the features of ultra-high pressure vessel (UPV) for sea food processing, a new quick-opening closure device for UPV is presented in this paper. The main research results are as follows:(1) Engineering design method. A new device which integrated detachable tooth-locked quick closure structure and assembled seal components is given. And an engineering design method of the device used for UPV is also presented, which is applied to an UPV for sea food proceeding with a design pressure of 315MPa and a volume of 15L.(2) Numerical Simulation and fatigue design. A whole finite element model of the quick-opening closure structure is built. The stresses distribution of this structure and its contact pressure are obtained. The numerical values are assessed by stress categorization of design by analysis. Mean stress effects on fatigue life of pressure vessels is analyzed in detail and relevant fatigue design method is also given. The result shows that fatigue is one of the most important failure modes for UP Vs.(3) Optimum design. Based on orthogonal experiment, the significance of factors affecting fatigue life, including the root shape, the size of root radius and the geometric parameters of tooth and end flange, is obtained. It shows that the root radius is of importance to fatigue life of UPVs. And an optimized structure is achieved;the result indicates that the fatigue life can meet the design requirement after optimization.(4) Hydrostatic test. Hydrostatic test on a 15 L UPV for sea food processing is carried outThe experimental results show that, the device put forward in this paper is convenient for quick-opening with good seal performance, and seal components can be used repetitively under 397MPa. This device satisfies engineering application with good industrial utility prospect. |
