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Nickel-chromium alloy furnace tube for cracking furnace and preparation method thereof

A nickel-chromium alloy, cracking furnace technology, used in cracking, non-catalytic thermal cracking, petroleum industry and other directions, can solve problems such as the inability of the oxide film to work, slow down the phenomenon of catalytic coking, reduce free radical coking and polycondensation coking, improve The effect of thermal conductivity

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

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Effect test

preparation example Construction

[0019] The present invention also provides a method for preparing the above-mentioned nickel-chromium alloy furnace tube for a cracking furnace, the preparation method comprising: raising the temperature of the nickel-chromium alloy furnace tube to 600-1100°C, and keep it warm for 5-100 hours; then, cool the nickel-chromium alloy furnace tube to below 40°C at a cooling rate lower than 150°C / h; wherein, the nickel-chromium alloy furnace tube is equipped with an enhanced heat transfer member.

[0020] According to the method of the present invention, the above-mentioned temperature rise, heat preservation and temperature drop are carried out under the condition that an enhanced heat transfer member is arranged in the nickel-chromium alloy furnace tube. During the low oxygen partial pressure gas treatment process, the flow state of the low oxygen partial pressure gas is changed by performing the above-mentioned temperature rise, heat preservation and temperature drop treatment in...

Embodiment 1

[0036] 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: 32.55, Ni: 42.60, Fe: 21.12, Mn: 0.98, Si: 1.41, Nb: 0.64, C: 0.53, 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

[0039] 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 lower the furnace temperature to room temperature at a cooling rate of 100°C / h. 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 6.5 μm, and the coverage rate 91%.

[0040] 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 213.3~410.9℃, specific ...

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Abstract

The invention relates to the field of nickel-chromium alloy furnace tubes for cracking furnaces, and discloses a nickel-chromium alloy furnace tube for a cracking furnace and a preparation method thereof. The nickel-chromium alloy furnace tube comprises a furnace tube, an intensified heat transfer member arranged in the furnace tube and an oxidizing film formed on the inner surface of the furnace tube, wherein the oxidizing film contains an oxide of one or more elements such as Cr, Mn, Ni, Fe, Al and Si. According to the nickel-chromium alloy furnace tube for the cracking furnace provided by the invention, an inert protective film with relatively high heat stability is formed on the inner surface of the furnace tube, so that a catalytic coking phenomenon can be inhibited or alleviated; meanwhile, the intensified heat transfer member is arranged in the furnace tube, so that the flow condition of a fluid can be changed, the coefficient of heat conduction can be improved, and free radical coking and polycondensation coking can be reduced.

Description

technical field [0001] The invention relates to a nickel-chromium alloy furnace tube for a cracking furnace and a preparation method thereof. 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 ethyle...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C10G9/20
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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