Investigation And Design Of The Recovery Process And Equipments For Separation Of Waste Grease From Kitchen Garbage

With the continuous improvement of the people’s living standards and the rapid socio-economic development, the amount of kitchen waste is also increasing. According to statistics, only the wasted food on the table is valued more than two hundred billion yuan every year. Most of the wasted food is discarded without any efficient recovery and use, not only seriously affected the urban environment, but also caused a serious waste of resources and a number of food safety problems, with the food safety issues caused by waste greases and oils from restaurant to be the most serious. Therefore, the harmless recovery treatment of kitchen waste, especially the waste greases and oils from restaurant, is a matter of great urgency.In this paper, combined with Yinchuan geography and climate, eating habits as well as the level of local food kitchen waste treatment technologies, as for the technology of de-oiling dried fodder which has relatively high efficiency, shorter payback period, slight influenced by environmental climate, good economic returns, a innovative gravity-boiling-air flotation oil-water separation technology appropriate to this de-oiling dried fodder route was proposed. Also, a high-efficiency, energy-saving and low cost gravity-boiling-air flotation oil-water separator was designed on the premise of ensuring feasibility and economy, which laid the foundation for the comprehensive utilization of kitchen waste oil in the further, such as the preparation technology of biodiesel from kitchen waste oil.Oil-water separation is a key technology of the de-oiling dried fodder treatment, but also is the crucial pre-processing step for the comprehensive utilization of kitchen waste oil. In this study, based on conventional gravity separation techniques, the innovative gravity-boiling-air flotation water separation technology was designed through a large number of simulation experiments and calculation. Aimed on kitchen waste having high content of solid, boiling was introduced to improve the oil extraction from solid particle inside, meanwhile higher temperature can accelerate the upward movement of oil droplets and make these oil droplets coalesce to form large droplets, which can greatly increase separation efficiency. Air flotation was introduced to accelerate the upward movement of oil droplets, making the separation of emulsified oil be easy. More importantly, the air flotation method and boiling method was achieved on the same equipment through using high-pressure water vapor as the gas source of air flotation method without additional external heat source. The high-pressure water vapor was not only used to make the required micro-bubbles, but also used as the heat source for boiling method, which simplified the equipment and saved energy greatly. Finally, vertical separation tank was chosen as the basic equipment with high-pressure water vapor as the source of heat and air. Relevant technical parameters were determined through tests and theoretical calculations, which provided the basis for the equipment designs.