精萘的制作流程通常包括原料预处理、蒸馏、酸洗、碱洗、精馏等步骤，以下是具体介绍：

The production process of refined naphthalene usually includes steps such as raw material pretreatment, distillation, acid washing, alkali washing, and distillation. The following is a specific introduction:

原料预处理：精萘的原料通常是煤焦油或石油萘。首先要对原料进行预处理，以去除其中的杂质，如水分、固体颗粒等。对于煤焦油，一般先进行静置分层，使水分和杂质沉淀到底部，然后通过过滤或离心分离等方法进一步去除固体杂质。石油萘则可能需要通过萃取、吸附等方法去除其中的芳烃杂质。

Raw material pretreatment: The raw materials for refined naphthalene are usually coal tar or petroleum naphthalene. Firstly, the raw materials need to be pre treated to remove impurities such as moisture and solid particles. For coal tar, it is generally first subjected to static stratification to allow water and impurities to settle to the bottom, and then further remove solid impurities through methods such as filtration or centrifugal separation. Petroleum naphthalene may require the removal of aromatic impurities through extraction, adsorption, and other methods.

蒸馏：将预处理后的原料送入蒸馏塔中进行蒸馏。在蒸馏过程中，利用萘与其他组分沸点的差异，将萘从原料中分离出来。通常采用减压蒸馏的方式，以降低蒸馏温度，减少萘的分解和聚合。蒸馏塔的操作条件根据原料的组成和产品要求进行调整，一般塔顶温度控制在 180 - 210℃左右，塔底温度控制在 220 - 250℃左右。通过蒸馏，可以得到粗萘，其纯度一般在 90% - 95% 左右。

Distillation: Send the pre treated raw materials into a distillation tower for distillation. During the distillation process, naphthalene is separated from the raw material by utilizing the difference in boiling point between naphthalene and other components. Usually, vacuum distillation is used to lower the distillation temperature and reduce the decomposition and polymerization of naphthalene. The operating conditions of the distillation tower are adjusted according to the composition of the raw materials and product requirements. Generally, the top temperature of the tower is controlled at around 180-210 ℃, and the bottom temperature is controlled at around 220-250 ℃. By distillation, crude naphthalene can be obtained, with a purity generally around 90% -95%.

酸洗：将粗萘用浓硫酸进行酸洗，以去除其中的不饱和烃、酚类等杂质。酸洗过程中，浓硫酸与杂质发生化学反应，生成可溶于酸的物质，从而与萘分离。酸洗温度一般控制在 30 - 60℃左右，酸洗时间为 1 - 3 小时。酸洗后，将酸液和萘层分离，萘层再用清水洗涤至中性。

Acid washing: Wash crude naphthalene with concentrated sulfuric acid to remove impurities such as unsaturated hydrocarbons and phenols. During the pickling process, concentrated sulfuric acid reacts chemically with impurities to produce substances soluble in acid, which are then separated from naphthalene. The pickling temperature is generally controlled at around 30-60 ℃, and the pickling time is 1-3 hours. After acid washing, separate the acid solution from the naphthalene layer, and wash the naphthalene layer with clean water until neutral.

碱洗：经过酸洗后的萘再用氢氧化钠溶液进行碱洗，以去除残留的酸性物质和酚类杂质。碱洗温度一般控制在 40 - 80℃左右，碱洗时间为 1 - 2 小时。碱洗后，同样将碱液和萘层分离，萘层用清水洗涤至中性。

Alkali washing: After acid washing, naphthalene is washed with sodium hydroxide solution to remove residual acidic substances and phenolic impurities. The alkaline washing temperature is generally controlled at around 40-80 ℃, and the alkaline washing time is 1-2 hours. After alkaline washing, separate the alkaline solution from the naphthalene layer, and wash the naphthalene layer with clean water until neutral.

精馏：将经过酸洗和碱洗后的萘送入精馏塔中进行精馏，以进一步提高萘的纯度。精馏塔通常采用高效填料塔或板式塔，操作压力一般为常压或减压。通过精确控制精馏塔的温度、回流比等操作参数，使萘与其他微量杂质分离，最终得到纯度在 99% 以上的精萘。塔顶得到的是轻组分杂质，塔底得到的就是精萘产品。

Distillation: Send the naphthalene that has been acid washed and alkali washed into a distillation tower for further distillation to improve the purity of naphthalene. Distillation towers usually use high-efficiency packed towers or plate towers, and the operating pressure is generally atmospheric or reduced pressure. By precisely controlling the operating parameters such as temperature and reflux ratio of the distillation tower, naphthalene is separated from other trace impurities, resulting in refined naphthalene with a purity of over 99%. At the top of the tower, light component impurities are obtained, while at the bottom, refined naphthalene products are obtained.

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