結(jié)晶法

Crystallization method

間歇式分布結(jié)晶法（Prosbd 法）：20 世紀(jì) 60 年代由法國 Prosbd 公司開發(fā)，在捷克烏爾克斯焦油加工廠實施。主要設(shè)備是 8 個結(jié)晶箱，分 4 步進行。通過泵、加熱器和冷卻器實現(xiàn)結(jié)晶箱的升溫和降溫。該方法原料單一，無需輔助原料，工藝流程、設(shè)備和操作簡單，設(shè)備投資少，操作費用和能耗低，不產(chǎn)生 “三廢”，對環(huán)境無污染，原料可用工業(yè)萘或萘油餾分，產(chǎn)品質(zhì)量可通過結(jié)晶循環(huán)次數(shù)調(diào)節(jié)，生產(chǎn)工藝成熟，產(chǎn)品質(zhì)量穩(wěn)定，也可用于生產(chǎn)工業(yè)萘。

Intermittent distributed crystallization method (Prosbd method): developed by the French company Prosbd in the 1960s and implemented at the Urks tar processing plant in the Czech Republic. The main equipment consists of 8 crystallization boxes, which are divided into 4 steps. Heating and cooling of the crystallization box are achieved through pumps, heaters, and coolers. This method has a single raw material, no need for auxiliary raw materials, simple process flow, equipment and operation, low equipment investment, low operating costs and energy consumption, no production of "three wastes", no pollution to the environment. The raw materials can be industrial naphthalene or naphthalene oil fractions, and the product quality can be adjusted by the number of crystallization cycles. The production process is mature, the product quality is stable, and it can also be used for the production of industrial naphthalene.

連續(xù)式多級分步結(jié)晶法（Brodie 法）：又稱萘區(qū)域熔融精制，20 世紀(jì) 70 年代由澳大利亞聯(lián)合碳化物公司研制。主要由晶析精制、精萘蒸餾、制片包裝和溫水循環(huán) 4 個系統(tǒng)組成，是連續(xù)生產(chǎn)過程，產(chǎn)品質(zhì)量穩(wěn)定，但基建投資和操作費用高，操作條件要求嚴(yán)，在中國尚未普遍應(yīng)用，上海寶鋼化工曾采用此裝置運行。

Continuous multi-stage stepwise crystallization method (Brodie method): also known as naphthalene zone melting refining, developed by Union Carbide Australia in the 1970s. It mainly consists of four systems: crystallization refining, refined naphthalene distillation, film packaging, and warm water circulation. It is a continuous production process with stable product quality. However, the infrastructure investment and operating costs are high, and the operating conditions are strict. It has not been widely used in China, and Shanghai Baosteel Chemical has used this equipment for operation.

立管降膜結(jié)晶法（MWB 法）：20 世紀(jì) 80 年代末由瑞士 Sulzer 公司開發(fā)，采用獨特的降膜結(jié)晶技術(shù)，強化了萘熔體的傳熱與傳質(zhì)過程，提高了設(shè)備處理能力。我國鞍山化工總廠 1992 年引進該精萘加工裝置，1994 年投產(chǎn)，年產(chǎn) 2 萬噸。

Vertical tube falling film crystallization method (MWB method): developed by Sulzer company in Switzerland in the late 1980s, using a unique falling film crystallization technology to enhance the heat and mass transfer process of naphthalene melt and improve equipment processing capacity. The Anshan Chemical Plant in China introduced the refined naphthalene processing unit in 1992 and put it into operation in 1994, with an annual output of 20000 tons.

加氫精制法：萘的催化加氫多采用 AI - Co - Mo 催化劑，也有采用 AI - Ni - Mo 催化劑的，可使萘中的硫茚、苯甲腈、茚、酚等雜質(zhì)轉(zhuǎn)化成易于除去的物質(zhì)加以分離。萘加氫精制主要用于生產(chǎn)低硫萘，可避免流化床生產(chǎn)鄰苯二甲酸酐時催化劑中毒，也適用于生產(chǎn)二萘酚、甲萘胺、H 酸及苯胺染料中間體等化工產(chǎn)品。

Hydrorefining method: The catalytic hydrogenation of naphthalene often uses AI Co Mo catalyst, and some also use AI Ni Mo catalyst, which can convert impurities such as sulfur indene, benzonitrile, indene, phenol, etc. in naphthalene into easily removable substances for separation. Naphthalene hydrogenation refining is mainly used for the production of low sulfur naphthalene, which can avoid catalyst poisoning during fluidized bed production of phthalic anhydride. It is also suitable for the production of chemical products such as naphthol, naphthylamine, H-acid, and aniline dye intermediates.

升華法：利用萘在遠低于沸點時就具有升華的特性，使萘與雜質(zhì)分離，從而得到精萘。但一般單獨使用升華法較少，常與其他方法結(jié)合使用。

Sublimation method: Utilizing the sublimation property of naphthalene at temperatures far below its boiling point, naphthalene is separated from impurities to obtain refined naphthalene. However, sublimation method is rarely used alone and is often combined with other methods.

精萘生產(chǎn)工藝對比

Comparison of production processes for refined naphthalene

結(jié)晶法：操作相對簡單，投資和運行成本相對較低，產(chǎn)品質(zhì)量穩(wěn)定，但生產(chǎn)效率可能較低，生產(chǎn)規(guī)模受限。

Crystallization method: The operation is relatively simple, the investment and operating costs are relatively low, the product quality is stable, but the production efficiency may be low and the production scale is limited.

加氫精制法：能有效脫除雜質(zhì)，生產(chǎn)出高質(zhì)量的精萘，適用于對產(chǎn)品質(zhì)量要求高的領(lǐng)域，但需要較高的技術(shù)水平和設(shè)備投資，工藝操作條件較為嚴(yán)格。

Hydrorefining method: It can effectively remove impurities and produce high-quality refined naphthalene, suitable for fields with high product quality requirements, but requires high technical level and equipment investment, and strict process operating conditions.

升華法：可以在一定程度上提純精萘，但通常需要與其他方法配合使用才能達到較高的純度要求，單獨使用時應(yīng)用范圍較窄。

Sublimation method: It can purify refined naphthalene to a certain extent, but it usually needs to be used in combination with other methods to achieve higher purity requirements, and its application range is relatively narrow when used alone.

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