Method for reducing ethylene cracking furnace tube coking and improving ethylene selectivity

An ethylene cracking furnace and furnace tube technology, which is applied in the directions of hydrocarbon cracking, gaseous chemical plating, coating, etc., can solve problems such as complex coating process, and achieve the effects of firm bonding, simple operation and low cost.

Active Publication Date: 2010-06-09
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0013] Aiming at the defects of the existing coating technology, such as complex coating process and disassembly to be coated, the present invention invents a method of pre-coating the inner surface of the furnace tube in an online manner to obtain a ceramic coating

Method used

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  • Method for reducing ethylene cracking furnace tube coking and improving ethylene selectivity
  • Method for reducing ethylene cracking furnace tube coking and improving ethylene selectivity

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] The pre-coating of the furnace tube is carried out on the 200g / h laboratory ethylene cracking evaluation device, that is, vapor deposition. The pretreatment solution is injected from the connecting part of the preheater and the cracking furnace. The material of the furnace tube is 304 stainless steel, and the center of the furnace tube is inserted There are thermocouple protection tubes of the same material with the following dimensions:

[0031] Furnace tube size: 14×2×900mm; thermocouple protection tube: 6×1×850mm

[0032] (1) Vapor deposition

[0033]The conditions are as follows:

[0034] Preheater temperature: 600°C; cracking furnace temperature: 800°C; water vapor (carrier gas) flow rate: 50g / h; pretreatment solution injection rate: 8g / h (preheat and stir with a magnetic heating stirrer when injecting); Pretreatment solution: 2% ethanol solution of hexamethyldisiloxane;

[0035] (2) Heat treatment:

[0036] After vapor deposition, the temperature of the cr...

Embodiment 2

[0041] Replace the new furnace tube of the same material, change the pretreatment solution in the example 1 into the ethanol solution of 2 mass % hexamethyldisiloxane+2 mass % chromium acetylacetonate, other treatment conditions and processes are the same as in Example 1, The surface analysis results are shown in Table 2.

[0042] Table 2 furnace tube inner surface element data (wt%)

[0043] element

Embodiment 3

[0045] The furnace tube is processed according to the method described in Example 1, and then the cracking test is carried out on the device. In the cracking process, the cracked gas is analyzed by gas chromatography, and the nitrogen 2 and O 2 The mixed gas is burned, and the CO and CO in the burnt gas are measured online with an infrared analyzer 2 Concentration, the volume of charred gas is recorded online with a wet flowmeter, and the amount of carbon in the charred gas is calculated, that is, the coking amount of the furnace tube during the cracking operation cycle. The physical properties of the raw material oil used in the examples are shown in Table 4. The cracked gas was analyzed by gas chromatography, and it was found that the volume percentage of olefins was higher than that of the blank test. The comprehensive comparison of the specific results is shown in Table 5.

[0046] The cracking conditions are as follows:

[0047] Raw materials: 200 grams of industrial n...

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Abstract

The invention discloses a method for reducing ethylene cracking furnace tube coking and improving ethylene selectivity, belonging to the cracking technology. The method comprises the following steps: injecting on line the pretreating solution containing ceramics elements, such as Si, Al, Ca, B and the like as well as catalytic activity elements, such as Ag, Cr, Cu, Ti, Mn and the like into a cracking furnace tube during steam hot preparation at the temperature of 500-1000 DEG C; carrying out vapour phase deposition on the elements onto the inner wall of the furnace tube; at the temperature of 700-1100 DEG C, in the carrier gas atmosphere taking inert gas as the main component, carrying out constant-temperature heat treatment on the furnace tube; and finally, forming a ceramics coating on the inner surface of the furnace tube. The coating reduces more than 80% of deposition on the inner wall of the furnace tube by coke and improves ethylene selectivity.

Description

technical field [0001] The invention relates to a method for reducing the coking of the furnace tube of an ethylene cracking furnace, more specifically, the invention relates to a method for forming a ceramic coating on the inner surface of the furnace tube to reduce the coking. Background technique [0002] Trienes (ethylene, propylene, butadiene) and triphenyls (benzene, toluene, xylene) produced by ethylene plants are the basic raw materials for the petrochemical industry. The output, production scale and technology of ethylene indicate the development level of a country's petrochemical industry. The current method of producing ethylene is mainly tube furnace cracking technology, which has been widely used in the world. In the ethylene production process of hydrocarbon steam cracking in tube furnaces, the coking of the furnace tubes and waste heat boilers (TLE) in the radiant section of the cracking furnace restricts the operating cycle of the cracking furnace and direct...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C16/30C23C16/44C07C11/04C07C4/02
CPCY02P20/52
Inventor 王申祥王红霞王国清
Owner CHINA PETROLEUM & CHEM CORP
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