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Processing method of nichrome furnace tube for pyrolysis furnace

A technology of nickel-chromium alloy and treatment method, which is applied in the direction of cracking, hydrocarbon cracking to hydrocarbon, non-catalytic thermal cracking, etc., can solve the problem that the oxide film cannot play its role, and achieve the slowdown of catalytic coking, the reduction of free radical coking, and the reduction of polycondensation coking effect

Active Publication Date: 2017-04-05
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, the oxide film in the liquid cracking furnace tube is only effective in the early stage of the furnace tube service, because the oxide film at this time has not been covered by condensation and coking, and when the cracking furnace runs to the middle and late stages, the oxide film cannot play its role

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] The furnace tube in the radiant section of the industrial cracking furnace, which is made of 35Cr45Ni and has samples of the same material in the furnace tube, was treated with a low oxygen partial pressure gas atmosphere. The element composition of the furnace tube alloy is: Cr: 32.60, Ni: 42.44, Fe: 21.13, Mn: 1.01, Si: 1.38, Nb: 0.73, C: 0.54, others: 0.17 (wt%). In the furnace tube of the radiant section of the cracking furnace, in the form of mutual intervals, twisted sheets integrally made with the furnace tube are arranged along the axial direction. The axial length of the twisted sheet twisted by 180° is a pitch, and the distance between two adjacent twisted sheets is The distance is 15 pitches. The hypoxic partial pressure gas used was H 2 The gas mixture with water vapor, wherein the volume percentage of water vapor in the low oxygen partial pressure gas is 5.0%, the heating rate of the heat treatment furnace during the treatment of the low oxygen partial pre...

Embodiment 2

[0030] The same type of cracking furnace containing twisted sheets in the same radiant section furnace tube as in Example 1. The hypoxic partial pressure gas used was H 2 The gas mixture with water vapor, wherein the volume percentage of water vapor in the low oxygen partial pressure gas is 3.2%. for 30 hours, and then the furnace temperature was naturally lowered to room temperature. The composition of the surface of the sample was analyzed by scanning electron microscope and energy dispersive spectrometer. The analysis showed that an oxide film containing oxides of Cr, Mn, Ni, Fe and Si elements was formed on the surface of the sample. The thickness of the oxide film was 6.4 μm, and the coverage 85%.

[0031] Hydrocarbon steam cracking reaction is carried out in industrial cracking furnace after low oxygen partial pressure gas atmosphere treatment, cracking raw material is diesel oil, its physical properties are: distillation range 211.5~408.7℃, specific gravity D 20 0.87...

Embodiment 3

[0033] The same type of cracking furnace containing twisted sheets in the same radiant section furnace tube as in Example 1. The hypoxic partial pressure gas used was H 2 A gas mixture with water vapor, wherein water vapor accounts for 2.2% by volume of the low oxygen partial pressure gas, the heating rate of the heat treatment furnace during the treatment of the low oxygen partial pressure gas is 80°C / hour, the treatment temperature is 850°C, and the treatment time for 45 hours, and then the furnace temperature was naturally lowered to room temperature. The composition of the surface of the sample was analyzed by scanning electron microscope and energy dispersive spectrometer. The analysis showed that an oxide film containing oxides of Cr, Mn, Ni, Fe and Si elements was formed on the surface of the sample. The thickness of the oxide film was 6.2 μm, and the coverage was 87%.

[0034] The hydrocarbon steam cracking reaction is carried out in the industrial cracking furnace a...

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Abstract

The invention relates to the field of nichrome furnace tubes for pyrolysis furnaces and discloses a processing method of a nichrome furnace tube for a pyrolysis furnace. The method comprises the following steps of: in the atmosphere of low-oxygen partial-pressure gas, heating the nichrome furnace tube to 600-1100 DEG C at a heating speed lower than 150 DEG C / h, and performing heat preservation for 5-100 hours, wherein the nichrome furnace tube is internally provided with an enhanced heat transfer component. By use of the nichrome furnace tube, which is processed by the method, for the pyrolysis furnace, the operation cycle of the pyrolysis furnace can be obviously prolonged.

Description

technical field [0001] The invention relates to a treatment method for a nickel-chromium alloy furnace tube used in a cracking furnace. Background technique [0002] Ethylene is one of the most important basic raw materials in the petrochemical industry. The current method of producing ethylene is mainly tube furnace cracking technology, which has been widely used in the world. However, an unavoidable problem in the production process of ethylene is the coking and carburization of crackers during service. Coking during the cracking process will reduce the inner diameter of the furnace tube, increase the pressure drop in the tube, and shorten the operating cycle of the cracking furnace; when the temperature of the tube wall reaches the allowable limit or the pressure drop reaches a certain level, the furnace needs to be shut down for coke cleaning. The coking on the inner wall of the furnace tube hinders the normal progress of the cracking reaction, affects the ethylene yie...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C10G9/16C10G9/20C07C11/04C07C4/04
Inventor 王国清王红霞王申祥郏景省张利军刘俊杰
Owner CHINA PETROLEUM & CHEM CORP
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