Soft sensing method for true temperature of pyrolysis mixed products at outlet of ethylene cracking furnace

Abstract

The invention relates to a soft sensing method for true temperature of pyrolysis mixed products at the outlet of an ethylene cracking furnace, comprising the following steps: firstly obtaining the furnace tube parameters of the cracking furnace; then obtaining the information of cracking raw material; then calculating the composition of pyrolysis products at the outlet of the cracking furnace; according to a cracking process model, including mass balance equation, momentum balance equation and energy balance equation, calculating the composition profiles of the pyrolysis products at the outlet of a radiant section; then calculating coking thickness in a cracking furnace tube; calculating coking thickness in a adiabatic segment furnace tube according to the contents of small molecule unsaturated hydrocarbon and aromatic hydrocarbon in the pyrolysis products and running time; and finally calculating the difference value of the temperature of a measurement and control point and the true temperature of pyrolysis mixed products so as to calculate the true temperature of pyrolysis mixed products at the outlet of the ethylene cracking furnace. Through the method, the true temperature of gas mixture of pyrolysis products at a particular moment of time can be dynamically calculated, and accurate model of the ethylene cracking furnace can be established, so that the method provides the basis for the simulation, optimization and control of cracking process.

Description

field of invention [0001] The invention relates to a temperature measurement method, in particular to a soft measurement method for the real temperature of cracking mixed products at the outlet of an ethylene cracking furnace. Background technique [0002] Ethylene is the most important monomer in the petrochemical industry and the basis for the production of organic raw materials. The scale of ethylene plant has been enlarged, the technical level and industrial concentration have been continuously improved. [0003] The thermal cracking ethylene unit is one of the units with the highest production capacity and the largest energy consumption in the petrochemical industry. The complex hydrocarbon cracking reactions of high temperature, strong heat absorption and short residence time in the cracking furnace basically determine the product yield and main energy consumption indicators of the entire ethylene plant. Therefore, the operating level and technical level of the crack...

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Problems solved by technology

At present, there are two methods for determining this temperature: one is to use the COT temperature at the sampling point of the DCS system to replace this temperature, and the COT sampling point is located outside the cracking furnace tube, without considering the temperature difference inside and outside the cracking furnace tube; Another situation is to use the method of COT plus a fixed temperature deviation to estimate, but as the cracking process proceeds, the temperature difference changes gradually, and the temperature difference estimation is not necessarily accurate

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