Method for preventing coking of visbreaking and heating furnace used for inferior heavy oil

Abstract

The invention relates to a method for preventing coking of a visbreaking and heating furnace used for inferior heavy oil. The inferior heavy oil is a residual oil fraction of crude oil obtained at a temperature of 420 DEG C; a horizontal tube box-type furnace is used as the visbreaking and heating furnace, and temperature of a furnace outlet is controlled to be 425 to 435 DEG C; steam is injected into a furnace tube of a transfer line between a convection chamber and a radiation chamber and into a furnace tube in the middle of the radiation chamber, and steam accounting for 0.5 to 4% of the weight of raw materials is injected; 70% of the steam is injected into the furnace tube of the transfer line between the convection chamber and the radiation chamber, and 30% of the steam is injected into the furnace tube in the middle of the radiation chamber; and a line rate of the visbreaking and heating furnace is 1.2 to 2.0 m / s. According to the method, through optimization of an arrangement pattern of furnace tubes of the visbreaking and heating furnace, furnace outlet temperature and the flowing line rate of a medium in the furnace tubes and increase of steam injection points, coking in the visbreaking and heating furnace is effectively avoided, and safe and long-period production of the furnace is realized.

Description

technical field [0001] The invention relates to a method for preventing coking of a visbreaking heating furnace for processing low-quality heavy oil by adjusting the outlet temperature of the visbreaking heating furnace, the steam injection amount of the heating furnace and the steam injection position of the heating furnace. Background technique [0002] Visbreaking is a mild thermal cracking process, the purpose is to convert residual oil into fuel oil with a viscosity that meets the specification, and produce a part of light products; visbreaking can also be used to obtain a part of middle distillate. Its conventional process flow is: normal pressure or vacuum residue is heated to 400-500°C through a heating furnace, and then passes through an upflow reaction tower and fractionation tower, where light components and cracked residue are separated. [0003] At present, among the approximately 10 trillion barrels of remaining oil resources in the world, more than 70% are hea...

AI Technical Summary

Problems solved by technology

After coking occurs in the furnace tube, due to the reduction of the flow area, the flow resistance of the medium increases, and the heat transfer efficiency decreases, resulting in an increase in energy consumption of the device

At the same time, due to coking, the heat transfer performance in the furnace tube becomes poor, and the thermal resistance increases. When the medium absorbs the same heat, the tube wall temperature of the coking furnace is higher than that of the uncoked furnace tube wall, and the strength of the furnace tube decreases. Oxidation loss increases, the life of the furnace tube is shortened, and serious accidents such as furnace tube wall penetration occur

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