A continuous rectification system and process of bio-aviation kerosene based on shallow liquid layer evaporator

Abstract

The invention relates to a system and a technology for continuously rectifying biological aviation kerosene based on a shallow-liquid-layer evaporator. The system comprises a lightness-removing column and a finished-product column, the bottoms of the lightness-removing column and the finished-product tower are both provided with a shallow-liquid-layer evaporator, a gas-phase inlet of the lightness-removing column and a liquid-phase inlet of the lightness-removing column are communicated with a flash-evaporation tank, the top of the lightness-removing column is connected with a condenser II, and the bottom of the lightness-removing column is communicated with a liquid-phase inlet of the finished-product tower via a discharging pump II. The beneficial effects comprise that by employing two-tower rectification for relatively separating light compositions and heavy compositions, the high-quality target product biological aviation kerosene is obtained, the liquid-layer thickness of a heating pallet is reduced, the temperature of a heating medium is reduced, the heating vaporization amount is improved, high-temperature decomposition, polymerization and coking caused by over-long staying time are furthest eliminated, the rectification yield and the oil quality of the biological aviation kerosene are improved, and energy consumption is reduced.

Description

Technical field [0001] The invention relates to the technical field of separation and purification of biological aviation kerosene, in particular to a continuous distillation system and process for biological aviation kerosene based on a shallow liquid layer evaporator. Background technique [0002] Bio-aviation kerosene is made from waste animal and vegetable oils and fats, and undergoes chemical treatments such as hydrodeoxygenation, cracking, isomerization, etc., and then rectification to separate hydrocarbon components of C9~C16, with a distillation range of 120~240℃, average The molecular weight is 200-250, which can be used directly or mixed with traditional jet fuel to provide jet aircraft. Compared with traditional jet fuel, it can reduce carbon dioxide emissions. Due to the advantages of easy-to-obtain, renewable and low-pollution biofuel raw materials, the development of bio-jet kerosene has received widespread attention from many countries in the world. Traditional ke...

AI Technical Summary

Problems solved by technology

Traditional kerosene is generally obtained through single-tower side discharge, but to obtain high-quality aviation kerosene, the rectification tower is often high, the equipment investment is high, and the light component and heavy component are difficult to separate, and the yield of the target product is low , difficult to control

Aviation kerosene rectification belongs to high-temperature distillation, and the reboiler is generally kettle type or falling film type. The kettle type reboiler has a large liquid holding capacity, a long residence time, and a thick liquid layer on the surface of the heating tube, which increases the vapor content of the components. The pressure will increase the boiling temperature of the oil, which will easily lead to high temperature polymerization, decomposition and coking of the oil, reduce the rectification yield of bio-aviation kerosene, and consume a lot of energy

Although the falling film reboiler can better solve the influence of the liquid layer thickness on the vaporization process, due to the uneven distribution of the feed, the oil tends to dry up on the surface of the heat exchange tube, and the coking of the oil at high temperature will cause the heating tube to be blocked. The thermal resistance of the dirt increases, resulting in a significant decrease in the heat transfer area and total heat transfer coefficient, resulting in a decrease in evaporation, requiring frequent cleaning and repairs, which is not conducive to the stable operation of the equipment, and often uses a large flow pump for cycle operation, and the operating cost is relatively high

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