What are the reasons for coking during cracking of oily sludge?

 There are many reasons for coking during the cracking of oily sludge, mainly including the following aspects:

1. Incomplete pyrolysis:

During the pyrolysis process, when the outer surface temperature has reached the set temperature but the center temperature has not reached it, the reaction will be incomplete and part of the pyrolysis oil will not be completely recovered. The unrecovered pyrolysis oil will participate in the coking reaction, generating coke that sticks to the wall of the fixed bed.

 2. Catalytic effect of impurities:

During the production and transportation of sludge, impurities such as metal particles and dust will be mixed in. These metal particles will act as catalysts during the pyrolysis of sludge, causing the pyrolysis oil to generate metal carbides in a high temperature environment, thereby participating in the coking reaction.

 3. Influence of raw material components:

The polycyclic aromatic hydrocarbons and other heavy components in the sludge raw materials will undergo condensation reactions with high molecular weight olefins under high temperature to produce coke. In addition, heavy aromatic hydrocarbons in the raw materials or aromatic intermediates produced by polymerization are also common coking precursors.

 4. Small molecule cyclization reaction:

 Oil sludge after pyrolysis reaction will produce small molecules. These substances will undergo cyclization reaction to generate macromolecules under appropriate conditions, and react with the coking matrix or metal particles on the surface of the fixed bed to further generate coking.

 5. Generation of free radicals:

 If free radicals are generated during the pyrolysis process of oily sludge, it will also promote the occurrence of coking reaction. The high activity of free radicals makes them easy to combine with other molecules to form coke.

 6. Equipment and design factors:

 The design and operating conditions of the pyrolysis reactor may also affect the formation of coking. For example, the material, temperature distribution, and fluid dynamics of the reactor wall may affect the rate and degree of coking.

 7. Improper operating conditions:

 If the operating conditions such as temperature, pressure, and residence time during the pyrolysis process are not properly controlled, it may also lead to the aggravation of coking. For example, too high a temperature or too long a time may lead to a decrease in product quality and an increase in coking.

In summary, there are many reasons for coking in oily sludge pyrolysis, which need to be comprehensively considered and controlled from multiple aspects such as raw material characteristics, operating conditions, equipment design, etc. In order to prevent the occurrence of coking, a variety of measures can be taken, such as optimizing pyrolysis process parameters, improving raw material pretreatment effects, and strengthening equipment maintenance and care. If you have any equipment needs, please feel free to contact Zhengzhou Dingli New Energy Equipment Co., Ltd. The manufacturer will arrange professional engineers and sales managers to give you a detailed reply!