精萘的制作流程通常包括原料預處理、蒸餾、酸洗、堿洗、精餾等步驟，以下是具體介紹：

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:

原料預處理：精萘的原料通常是煤焦油或石油萘。首先要對原料進行預處理，以去除其中的雜質，如水分、固體顆粒等。對于煤焦油，一般先進行靜置分層，使水分和雜質沉淀到底部，然后通過過濾或離心分離等方法進一步去除固體雜質。石油萘則可能需要通過萃取、吸附等方法去除其中的芳烴雜質。

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.

蒸餾：將預處理后的原料送入蒸餾塔中進行蒸餾。在蒸餾過程中，利用萘與其他組分沸點的差異，將萘從原料中分離出來。通常采用減壓蒸餾的方式，以降低蒸餾溫度，減少萘的分解和聚合。蒸餾塔的操作條件根據原料的組成和產品要求進行調整，一般塔頂溫度控制在 180 - 210℃左右，塔底溫度控制在 220 - 250℃左右。通過蒸餾，可以得到粗萘，其純度一般在 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：將粗萘用濃硫酸進行酸洗，以去除其中的不飽和烴、酚類等雜質。酸洗過程中，濃硫酸與雜質發生化學反應，生成可溶于酸的物質，從而與萘分離。酸洗溫度一般控制在 30 - 60℃左右，酸洗時間為 1 - 3 小時。酸洗后，將酸液和萘層分離，萘層再用清水洗滌至中性。

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.

堿洗：經過酸洗后的萘再用氫氧化鈉溶液進行堿洗，以去除殘留的酸性物質和酚類雜質。堿洗溫度一般控制在 40 - 80℃左右，堿洗時間為 1 - 2 小時。堿洗后，同樣將堿液和萘層分離，萘層用清水洗滌至中性。

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.

精餾：將經過酸洗和堿洗后的萘送入精餾塔中進行精餾，以進一步提高萘的純度。精餾塔通常采用高效填料塔或板式塔，操作壓力一般為常壓或減壓。通過精確控制精餾塔的溫度、回流比等操作參數，使萘與其他微量雜質分離，最終得到純度在 99% 以上的精萘。塔頂得到的是輕組分雜質，塔底得到的就是精萘產品。

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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