Coal gas naphthalene-purifying waste diesel reclaiming technique

Abstract

A regenerating technologic method to waste diesel oil made by refined naphthalene removal from coal gas pertains to a regenerating technologic method to waste diesel oil made by refined naphthalene removal from coal gas in the coal gas purifying industry. The method is chiefly used for settling questions such as high diesel consumption, high production cost, the hoarding of a waste diesel and sale handicap existing in the current regenerating technologic method of coal gas doffing precisely naphthalene. The method combines the traditional rectification technique and freezing crystal technology: first naphthalene in the waste diesel is primarily concentrated by intermission rectification; then naphthalene in the fractioning rich in naphthalene can be separated by the freezing crystal technology; at last kettle fluid with less naphthalene, the lean naphthalene fraction and lean naphthalene oil are mixed so as to regenerate diesel. The technology flow is simple; the equipment investment and production cost are low; the content of naphthalene drops down from 3-4 percent to 0.5 percent; the yield of a regenerating diesel exists above 80 percent, so as to realize the recycling utilization. The method is applied to the regeneration of the waste diesel oil made by refined naphthalene removal from coal gas in the coal gas purifying industry.

Description

technical field [0001] The invention relates to the regeneration of naphthalene-removed waste diesel oil in the coal gas purification industry. Background technique [0002] The background technology involved in the present invention includes traditional rectification technology and freezing crystallization technology, and these two technologies are widely used in the chemical industry. [0003] Distillation is a chemical unit operation that realizes liquid-liquid separation. It uses the difference in relative volatility of each component in the mixture to separate the components to be separated. Waste diesel oil is a mixture system with complex composition, which contains many components with similar or identical boiling points to naphthalene. It is difficult to separate naphthalene from waste diesel oil by conventional rectification technology. The main reasons are: (1) Simple distillation only includes a gas-liquid equilibrium, so the separation ability is limited. Unde...

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Problems solved by technology

The existence of these companions directly leads to the low enrichment of naphthalene, and the serious loss of diesel oil in the separation process

(3) While naphthalene is removed from waste diesel oil by simple distillation, the accompanying substances close to the boiling point of naphthalene are also removed, which not only reduces the yield of diesel oil, but also reduces the quality of diesel oil, making it more viscous and fluid Poor performance and stability, directly affecting the naphthalene washing process

In addition, the gum content of diesel oil recovered by simple distillation increases, and the ability to wash naphthalene decreases, resulting in increased fuel consumption and increased operating costs

(4) Some products with relatively low naphthalene content (less than 0.5%) can be obtained by simple distillation, but the amount is very small and the yield is very low. Most of the naphthalene still remains in the waste diesel oil, and the expected separation cannot be achieved. Purpose

(5) Due to the presence of companions in diesel oil that are very close to the boiling point of naphthalene, the purity of naphthalene in the naphthalene fraction obtained by simple distillation separation cannot be too high, which will inevitably affect the sales and use of naphthalene products

This technology is suitable for treating waste diesel oil with a high naphthalene content (>30%), but not suitable for treating low-concentration naphthalene-containing waste diesel oil (<4%), and it is even less likely to reduce the naphthalene content in diesel to below 0.5% , this is mainly due to the low content of naphthalene in waste diesel oil, which is far from saturated. If you want to crystallize naphthalene from it, you need to further reduce the temperature to reduce its solubility

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