A method and system for low-temperature liquid-phase hydrotreating of Fischer-Tropsch synthetic oil

Abstract

The invention relates to a method and system for low temperature liquid phase hydrofinishing of Fischer-Tropsch syncrude. The method comprises the following steps: (1) Fischer-Tropsch syncrude and hydrogen are uniformly mixed in a hydrogen oil mixer in order to prepare a gas-liquid two-phase mixture of hydrogen bubbles and dissolved hydrogen oil, and the gas-liquid two-phase mixture is preheated in order to obtain a preheated material; (2) under a condition of low temperature liquid phase hydrofinishing reaction, the preheated material is added from the top of a fixed bed reactor with a liquid level control valve through a catalyst bed layer which is arranged in the fixed bed reactor from top to bottom, at the same time supplemented hydrogen is added into a catalyst bed layer, and reaction products are obtained at bottom of the fixed bed reactor; (3) reaction products are added into a low pressure separator for carrying out separation, separated reaction oil part is used as cycle oil and added into the gas-liquid two-phase mixture obtained in the step (1); wherein the temperature for the low temperature liquid phase hydrofinishing reaction is 200-249 DEG C. The method can guarantee low temperature alkene reduction and deoxidation, and equipment is saved.

Description

technical field [0001] The invention relates to a method for low-temperature liquid-phase hydrotreating of Fischer-Tropsch synthetic oil and a system for applying the method. Background technique [0002] Fischer-Tropsch synthetic oil is a clean fuel, mainly composed of linear alkanes, olefins and oxygenated compounds. However, synthetic crude oil contains a large amount of olefins and oxygenated compounds. If deoxidation treatment is not carried out, the equipment will be corroded in subsequent processing. Therefore, the synthetic crude oil must be hydrosaturated and hydrodeoxygenated. [0003] The existing Fischer-Tropsch synthetic oil hydrofining process requires a hydrogen circulation system, a hydrogen circulation compressor and high-pressure gas-liquid separation equipment, and the hydrofining temperature is high, so the equipment investment and operating costs are high. [0004] CN1865405A discloses a process for the hydrofinishing of Fischer-Tropsch synthetic oil pr...

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Problems solved by technology

This method adopts an upflow fixed bed reactor, and the refining unit omits the circulating hydrogen compressor, but the reaction temperature is relatively high, and it is difficult to control the reaction temperature during actual operation, which cannot guarantee the smooth operation of the device and the quality of the product oil. More importantly, It is because the hydrogen dissolved in the liquid-phase Fischer-Tropsch synthetic oil is far from enough to consume hydrogen for the hydrofining reaction of Fischer-Tropsch synthetic oil, which will lead to insufficient hydrofining reaction of Fischer-Tropsch synthetic oil. For the solubility of hydrogen, the temperature of Fischer-Tropsch synthetic oil hydrofining reaction has to be increased accordingly, because the higher the temperature, the greater the solubility of Fischer-Tropsch synthetic oil to hydrogen

[0007] However, the prior art method has problems such as complex equipment, high reaction temperature, and unstable operation of the device. It is necessary to develop a more advanced method and system for Fischer-Tropsch synthetic oil liquid-phase hydrofining. Among them, it is necessary to greatly increase the supply cost Hydrogen in the liquid-phase hydrofinishing reaction of Fischer-Tropsch synthetic oil, and make the temperature of Fischer-Tropsch synthetic oil liquid-phase hydrofinishing reaction lower, and the reaction operation is more stable and flexible

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