Design And Safety Research Of The Styrene Intermediate Tank Farm

In chemical plant, intermediate tank farm plays an essential role in the coordination of the preceding and the following units. Tank farm, when compared with unit area usually possesses the characteristics of having large storage capacity and being compact in arrangement which in the event of accident, will lead to severe casualty and property loss. The safety design of the tank farm is of great significance in chemical engineering design.This paper analyzes the safety design based on the characteristics of intermediate tank farm, and a case study is carried out on the intermediate tank farm in Styrene Plant. This paper deconstructs the design of intermediate tank farm into different levels, and makes detailed introduction of them. The implementation measure of safety design is employed in order to ensure the safety of tank farm.A 320 kt/a Styrene Plant is used as an example, wherein a systematic safty design is implemented to the intermediate tank farm. First of all, the design principles of intermediate tank farm are summerized and established. And the storage tank is employed according to the styrene production process and the safe storage requirements; Different types of tanks are designed according to the differences between the nature of the storage material, and so are the process and protective facilities, guaranteeing the safety of the tank and the surrounding facilities. In this paper, the development of the "design temperature and the material selection of large storage tank without HTM input" is characterized by being safe and economical. Proper design temperature is determined by calculating and analyzing the outdoor monthly mean minimum temperature, annual mean minimum temperature and extreme minimum temperature. Accordingly, the suitable material of intermediate tank is selected that greatly saves the equipment cost. Besides, the terminal layout design that satisfies the national standard, and another three-level preventions and control measures and necessary seepage prevention facilities are also designed, so as to prevent the hazards brought about by tank leakage. This paper also establishes the models of the heat exchanger and the process for intermediate tank farm, with the process simulation and the calculation of heat exchanger, the mechanism of the in-tank overtemperature polymerization and implosion is analyzed, and the control measures are proposed, which reduces the risks of tank over-temperature polymerization and flash polymerization. Furthermore, a three-level overpressure protection measures for tank is set up, and the calculation model was established in order to prevent overpressure in case of accident. In addition, we also specially calculate and set up the related safety instrument facilities, fully guaranteeing the safe operation of intermediate tank farm.The result of our study has an important role in the designing of intermediate tank farm, especially intermediate tank farm in Styrene Plant as well as to ensure the normal operation and the safety in production of the main plant of the styrene.