Using crystallizer and press to produce refined naphthalene from naphthalene cake is more complex, more equipment, more investment and poor working conditions, so the adoption of this process is gradually reduced.
According to the use of naphthalene, for example, in the production of phthalic anhydride, the industrial naphthalene containing more than 95% naphthalene can be used instead of refined naphthalene. In China, about 30% of naphthalene output must be produced with refined naphthalene or the required quantity of process equipment for phthalic anhydride production. Most of naphthalene can be used to produce naphthalene anhydride. Therefore, after dephenolization and depyridization of naphthalene oil fraction, the continuous distillation process (or batch distillation) is developed. At present, there are two main processes in China, i.e. single furnace single tower continuous production of industrial naphthalene and double furnace and double tower production of industrial naphthalene.