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Chemical Wall-Treatment Method That Reduces the Formation of Coke

a wall treatment and chemical technology, applied in the direction of solid-state diffusion coating, metallic material coating process, coating, etc., can solve the problems of coking phenomena, deterioration of the conductivity of the walls, and loss of head

Inactive Publication Date: 2019-12-26
TOTAL RAFFINAGE CHIM +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent text describes a process for treating a wall made of a special metal alloy to prevent coke formation during operation. The process involves surface treatment using carbides, which are removed using electrolysis to reduce coke formation. After treatment, the surface can be further oxidized to further reduce coke formation. The treatment process results in a homogeneous oxidized layer that increases the lifetime of the part. In addition, the treatment process results in a compressed layer that increases residual compressive strength, reducing fatigue and corrosion failures. The surface treatment also helps to fill cavities in the metal alloy and covers carbides that may be present, reducing coke formation.

Problems solved by technology

The walls of the reactors of some units of the petrochemical or chemical industry are sometimes subjected to very severe operating conditions which can result in phenomena of coking.
This deposition of coke can result in a fouling of the tubes, causing a head loss, a deterioration in the conductivity of the walls and a decrease in the yields.
It is then necessary to shut down the unit in order to remove the coke formed, an operation which is harmful to the productivity of the unit.

Method used

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  • Chemical Wall-Treatment Method That Reduces the Formation of Coke
  • Chemical Wall-Treatment Method That Reduces the Formation of Coke
  • Chemical Wall-Treatment Method That Reduces the Formation of Coke

Examples

Experimental program
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Effect test

example 1

emical Treatment of the Surface

[0099]In this example, the sample is subjected to an electrolytic dissolution chemical treatment.

[0100]The sample to be tested is placed at the anode of an electrolysis cell, such as described in FIG. 1, the cathode being a metal plate made of stainless steel or of graphite, with dimensions similar to or greater than those of the sample. The anode and cathode are separated by a distance of approximately 1 cm, the plates being substantially parallel inside the electrolysis cell.

[0101]An electrolytic solution is prepared by dissolving, with mechanical stirring, 135 g of NaOH (in the form of pellets) in 1 l of distilled water and then the electrolysis cell is filled with the solution obtained. The chloride content of the solution is less than 10 ppm by weight.

[0102]A potential difference is applied between the anode (sample) and the cathode.

[0103]Two series of five and four tests were carried out on HP 25-35 alloys, which were all polished before being pl...

example 2

l Surface Treatment / Shot Peening

[0111]A polished HP 25-35 alloy sample is subjected to shot peening in a sleeve sandblasting chamber. The parameters used are as follows:[0112]Particles: glass beads Ø 100-200 μm[0113]Projection distance: approximately 15 cm[0114]Duration of the projection: 15 seconds for a sample of a few cm2 [0115]Carrier gas: compressed air under a controlled pressure of 2.5 to 3.5 bars, nozzle diameter 6 to 8 mm, 40 litres of particles in a closed circuit.

[0116]A sample M1 is obtained.

example 3

l Surface Treatment / Sandblasting (Alumina Blasting)

[0117]A polished HP 25-35 alloy sample is subjected to alumina blasting in a sleeve sandblasting chamber. The parameters used are as follows:[0118]Particles: brown corundum (Al2O3) Ø 250-400 μm[0119]Projection distance: approximately 15 cm[0120]Duration of the projection: 15 seconds for a sample of a few cm2 [0121]Carrier gas: compressed air under a controlled pressure of 2.5 to 3.5 bars, nozzle diameter 6 to 8 mm, 40 litres of abrasive particles in a closed circuit.

[0122]A sample M3 is obtained.

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Abstract

The invention relates to a process for the treatment of a wall made of Fe—Ni—Cr metal alloy of an industrial reactor which reduces the formation of coke on the said wall when it is subjected to operational conditions favourable to coking, the metal alloy comprising, within its structure, carbides, some of which show on the surface. The process comprises a chemical surface treatment stage, during which at least a part of the carbides initially present in the alloy is dissolved by electrolytic decomposition, under conditions suitable for dissolving at least a part of these carbides, in particular chromium carbides.

Description

TECHNICAL FIELD[0001]The invention relates to a process for the surface treatment of a metal wall which has the effect of reducing the formation of coke at the surface of this wall. More specifically, the invention relates to a process for the surface removal of carbides from a wall made of metal alloy, in particular by chemical treatment. The invention also relates to the use of a metal wall treated by the treatment process in a process for the treatment of hydrocarbons.STATE OF THE ART[0002]The walls of the reactors of some units of the petrochemical or chemical industry are sometimes subjected to very severe operating conditions which can result in phenomena of coking. For example, the manufacture of alkenes, monomers valued in the polymer industry, is obtained by cracking oil-derived hydrocarbons at temperatures of the order of 800 to 900° C. In this type of process, a mixture of hydrocarbons and steam is circulated at high speed in reactors, generally formed of metal tubes, oft...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C25F3/06C23C8/02B24C1/04
CPCC25F3/06C23C8/02B24C1/04
Inventor AUGUSTIN, CHRISTELCAZOTTES, SOPHIEVACHÉ, NICOLASSTEYER, PHILIPPEDURET THUAL, CLAUDEDUPOIRON, FRANÇOIS
Owner TOTAL RAFFINAGE CHIM
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