1. Produced from petroleum hydrocarbons: catalytic heavy reforming oil, catalytic cracking light cycle oil, by-product tar from cracking to ethylene, etc;
2. By separating coal tar, naphthalene accounts for about 8% -12% in high-temperature coal tar. Distill the coal tar, cut the kerosene, remove phenols, remove quinolines, and distill to obtain finished naphthalene. Each ton of naphthalene consumes 10 tons of coal tar;
3. Refined naphthalene is obtained by refining crude naphthalene with clay;
The production process of the falling film step-by-step crystallization method consists of a product production process system, an energy system, a nitrogen sealing system, and a computer control system. The production process system takes a large cycle as the production cycle, with each large cycle containing 4 small cycles and each small cycle containing 4-6 segments. Each segment consists of three steps: crystallization, partial melting, and complete melting;
Example of falling film crystallization operation process: Liquid industrial naphthalene sent from the industrial naphthalene unit is sent to the distillation tank. When the fourth stage crystallization operation is carried out, the raw material liquid in the tank is pumped into the dynamic crystallizer collection tank. Uncrystallized naphthalene oil and sweating liquid are placed in the lower purity distillation tank, and the full melt can be used as the raw material for the fifth stage. After six stages of crystallization refining according to the predetermined procedure, the product refined naphthalene can be obtained. To improve the extraction rate of naphthalene The fraction rich in sulfur indene can be sent to a static crystallizer for processing, and the product obtained from the static crystallizer can be returned to the corresponding distillation tank of the dynamic crystallization system. The residual liquid can be sold as a water reducing agent. Due to the use of both dynamic and static crystallizers in this device, it can ensure a high naphthalene recovery rate while reducing energy consumption
5. Static stepwise crystallization method: The raw material industrial naphthalene is loaded into a crystallization box for rapid cooling, and after cooling to 82 ℃, it becomes uniformly cooled. It is cooled at a cooling rate of 2 ℃/h to 60 ℃, and the first crystallization naphthalene oil rich in sulfur indene is discharged as an intermediate fraction for post-treatment. Then, the material inside the crystallization box is heated at a rate of 4 ℃/h, and samples are taken every 0.5 hours to determine its crystallization point. According to the different crystallization points, they are discharged into the corresponding distillation tanks. This process is carried out 3-4 times in steps to obtain high-purity refined naphthalene.
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