A method for reducing the viscosity of quenching oil in an ethylene plant

Abstract

The invention discloses a method for reducing ethylene unit quenching oil viscosity. The method comprises solvent-based extraction of quenching oil from an ethylene unit, and solvent recovery for viscosity-reduced quenching oil acquisition. A weight ratio of the solvent to the quenching oil in solvent-based extraction is 0.01-1.99 and preferably is 0.5-1.99. The method comprises the following steps of 1, solvent-based extraction: introducing quenching oil from an ethylene unit, carrying out solvent-based extraction in an extraction tower, separating extract oil from the tower top and separating raffinate asphalt from the top bottom, and 2, solvent recovery: carrying out heating and / or pressure reduction on the extract oil obtained by the step 1, feeding the extract oil into a solvent recovery tower and separating a solvent and viscosity-reduced quenching oil. The method greatly reduces ethylene unit quenching oil viscosity. The method utilizes a low solvent ratio in solvent extraction so that visbreaking effects are improved, a solvent circulation volume is greatly reduced and energy consumption is reduced.

Description

technical field [0001] The invention relates to the field of ethylene production, and more particularly relates to a method for reducing the viscosity of quenching oil in an ethylene unit. Background technique [0002] At present, major ethylene plants in the world use steam pyrolysis to produce basic organic chemical raw materials such as ethylene, propylene, butadiene, and aromatics. Raw materials such as light hydrocarbons, naphtha, and hydrogenated tail oil are mixed with a certain proportion of diluted steam in an industrial cracking furnace to undergo cracking reactions under high temperature conditions. Diene and other chemical raw materials. [0003] The quenching system is an important part of the ethylene plant. It is composed of quenching cooler, oil washing tower, water washing tower and other equipment. As the first process of ethylene cracking gas treatment, it often becomes the bottleneck restricting the output and long-term stable operation of the ethylene ...

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Problems solved by technology

[0008] The disadvantages of this method are: first, when the ethane furnace burns, it must be stripped with high-pressure steam, and the gas phase directly returns to the quenching oil tower, and the load of the quenching oil tower is high; second, the light components in the heavy fuel oil are sent outside after stripping The content is small, and the outgoing pipeline is prone to blockage

This method only optimizes the temperature distribution of the oil scrubber, does not change the composition of the quenching oil, has little effect on reducing the viscosity, and increases the load in the middle section of the oil scrubber, affecting production capacity

[0010] Although the above method can partially reduce the viscosity of the quenching oil, it cannot fundamentally solve the problem of high viscosity of the quenching oil

At present, many ethylene plants in China have unreasonable design of the quenching oil visbreaking system, high viscosity of the quenching oil, high temperature at the top of the quenching oil tower, low temperature at the bottom of the tower, unstable operation of the quenching oil visbreaking system, and low heat recovery efficiency. Frequent emulsification of quenching water

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