Inhibitor and device for slowing down coking of ethylene cracking furnace pipe, and application method

Abstract

The invention relates to an inhibitor and device for slowing down coking of an ethylene cracking furnace pipe, and an application method. The inhibitor is a composition of alkali metal salt and boron compounds. An injectant nozzle comprises a guide pipe, wherein the guide pipe is covered with a heat insulating pipe; a nozzle is arranged at the front end of the heat insulating pipe; a guiding screw piece is arranged inside a spray cavity of the nozzle; a spraying piece is arranged at the front end of the nozzle; the injectant nozzle is mounted at the crossover section of the cracking furnace pipe. The application method comprises the following steps: the inhibitor is injected into high-temperature raw material gas in the crossover section of the cracking furnace pipe through an atomizing nozzle; aqueous solution spray of the inhibitor is injected into a cracking raw material in the cracking process; the inhibitor is used for catalyzing coke on the inner wall of a gasifying furnace pipe and gas-phase matrix coking in the presence of water vapor to slow down apparent furnace pipe coking. The inhibitor is good in coking inhibiting effect and less in added dose, and avoids sedimentation or fatigue damage of the inhibitor; the inhibitor is applied to a vapor cracking ethylene preparing device, can remarkably reduce furnace pipe coking, reduces the temperature of the pipe wall, guarantees the yield of triene, and greatly prolongs the operation cycle of the cracking furnace.

Description

technical field [0001] The invention relates to a method for reducing the coking of furnace tubes by hydrocarbon steam cracking to produce ethylene, in particular to an inhibitor, a device and a use method for slowing down the coking of ethylene cracking furnace tubes. Background technique [0002] The ethylene unit is the leading unit of a large petrochemical enterprise, and most of the production energy consumption is consumed by the cracking furnace. The operation status of the cracking furnace plays a decisive role in the benefit of the ethylene unit. [0003] Most of the world's ethylene production adopts the tube furnace cracking process. The hydrocarbon raw materials and steam are thermally cracked in the high-temperature heat-resistant furnace tube. Along with the coking reaction, a layer of coke will inevitably be formed on the inner wall of the furnace tube. With the gradual thickening of the coke layer, many adverse effects have been brought to the production: on ...

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Problems solved by technology

In fact, most of the coking occurs in the second half of the furnace tube in the radiant section, while the amount of coking in the convection section is very small. The direct addition method will cause the inhibitor to deposit in the steam pipeline and part of the convection section, and cannot fully reach the furnace in the radiant section. Tube

[0011] The method of using the inhibitor is very important to the effect of inhibiting coking and the smooth operation of the cracking furnace; if the injected inhibitor solution does not vaporize quickly, and the liquid is sprayed on the high-temperature furnace tube, the creep stress of the furnace tube due to continuous cold shrinkage and thermal expansion It will cause fatigue damage; if the amount of inorganic salt preparations injected is too large, it may cause the deposition of inhibitors in the furnace tube or the loss of large pieces of coke to block the furnace tube

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