Cracking Reactor – The Core Reaction Unit of Pyrolysis Oil Refining Equipment

Cracking Reactor – The Core Reaction Unit of Pyrolysis Oil Refining Equipment

The cracking reactor is the core equipment of the pyrolysis oil refining process and also the heart unit for realizing the resource conversion of organic solid wastes. Its core function is to conduct thermal decomposition reactions on macromolecular organic solid wastes such as rubber and plastic in a sealed, high-temperature environment of 300~500℃ under oxygen-free or low-oxygen conditions, cracking them into combustible oil and gas, crude carbon black, steel wire (for rubber-based raw materials) and other products. It provides basic materials for subsequent processes such as oil and gas condensation and carbon black recovery, and is the key link connecting raw material pretreatment and product separation and purification in the entire production line.

I. Structural and Material Design

In response to the harsh working conditions during the pyrolysis process, the cracking reactor adopts a targeted structural and material design to ensure stable and safe operation:

Main Body Material：High-temperature resistant, creep-resistant and wear-resistant carbon steel or chrome-molybdenum alloy steel is selected as the main body material. For high-end equipment with higher process requirements, clad steel plates are adopted, which not only ensure the structural strength and pressure-bearing capacity of the reactor body, but also effectively improve its corrosion resistance to acidic and alkaline substances generated during pyrolysis.

Sealed Pressure-bearing Structure：The reactor body is manufactured by integral forging or roll welding technology with high processing precision, and is matched with high-temperature resistant metal gaskets and high-pressure flanges at the connection and sealing parts. This structural design ensures that the reactor body can maintain zero leakage under a slight positive pressure working condition of 0.1~0.3MPa, and stably maintain the oxygen-free reaction environment required for pyrolysis, avoiding the generation of toxic and harmful substances such as dioxins caused by oxygen participation.

Heating and Heat Exchange System：The outer wall of the reactor body is usually equipped with a jacketed or coil-type heating structure, which uses clean energy such as coal, natural gas or self-produced pyrolysis gas as the heat source to realize uniform heating of the internal raw materials; the continuous reactor body is also built with high-efficiency heat exchange components in some designs, which can recover the waste heat generated during the pyrolysis reaction, preheat the to-be-processed raw materials, and greatly improve the overall energy utilization efficiency of the production line and reduce energy consumption costs.

II. Process Compatibility and Application Scenarios

According to the actual production scale, raw material characteristics and project operation mode, cracking reactors are mainly divided into two types: batch type and continuous type, which can be flexibly matched with different pyrolysis oil refining project requirements:

Batch-type Cracking Reactor：The single reactor capacity is usually 5~20 tons, and the operation follows a cyclic batch process of "feeding → temperature rising and pyrolysis → residue discharging and product collection". It has the advantages of low initial equipment investment, simple operation and flexible process adjustment, and is especially suitable for small and medium-sized solid waste treatment projects with small processing capacity, complex raw material components and frequent raw material switching.

Continuous-type Cracking Reactor：Adopting the design of continuous sealed feeding and continuous slag discharge, the daily processing capacity of a single production line can reach tens to hundreds of tons. The whole process is controlled by an automatic system, with high production automation, stable reaction conditions and lower unit energy consumption of products. It is suitable for large-scale industrial solid waste disposal bases with large processing capacity and homogeneous raw material components (such as single rubber or plastic solid waste), and can realize continuous and efficient industrial production.

III. Core Status in the Production System

As the core reaction unit of the entire pyrolysis oil refining production line, the performance, quality and operation stability of the cracking reactor directly determine the overall operation efficiency, product quality and economic benefits of the production line, and it is also the key link with the highest investment cost and the strictest operation and maintenance requirements in the whole production system:

Direct Impact on Product Yield and Quality：The uniformity of the temperature field inside the reactor, the precise control of the pyrolysis reaction time and the reasonable design of the material flow path directly affect the pyrolysis conversion rate of raw materials (oil yield) and the quality of pyrolysis products. Excessive temperature fluctuation or insufficient reaction residence time will lead to incomplete pyrolysis of raw materials, resulting in low oil yield and high impurity content in fuel oil; on the contrary, overly long reaction time will cause secondary cracking of products and reduce the utilization value of oil and gas products.

Core of Project Investment and Operation Cost：As the single equipment with the highest manufacturing cost in the pyrolysis oil refining production line, its procurement cost accounts for 30%~40% of the total equipment investment of the whole production line. At the same time, under long-term high-temperature and high-pressure working conditions, the inner wall of the reactor body is prone to coking and wear, and the sealing parts and heating components are easy to age and damage. Regular professional operations such as reactor internal coking cleaning, non-destructive testing of the reactor body and replacement of vulnerable parts are required, which makes it the core link of the daily operation and maintenance cost of the production line.

Key Guarantee for Production Safety and Environmental Compliance：The excellent sealing performance and stable pressure control system of the cracking reactor are the key guarantees for the safe management of flammable and explosive pyrolysis gas in the production line, and can effectively prevent safety accidents such as gas leakage and explosion. In addition, maintaining a stable oxygen-free reaction environment inside the reactor is also the core to avoid the generation of toxic and harmful substances such as dioxins during the pyrolysis process, which is an important foundation for the production line to meet environmental protection emission standards and realize compliant operation.