Pyrolysis is a breakthrough method for converting waste materials such as plastics, oil sludge and tyres into valuable energy. The process produces renewable resources such as pyrolysis oil, syngas, carbon black, etc.. The streamlined steps make this technology efficient in processing complex feedstocks and extracting a variety of valuable chemicals and fuels from them. Read on to learn more about the process of pyrolysis.
Understand Pyrolysis Process: Essential Material Decomposition
Pyrolysis process is essentially a thermal decomposition reaction in a high temperature and oxygen-free environment. The process is the core of the transformation of wastes such as plastics, oil sludge, and tyres into sustainable energy. These wastes contain high molecular weight hydrocarbon compounds, such as polymers, petroleum, and rubber. During the process of pyrolysis, long-chain or cross-linked high molecular compounds are decomposed into smaller hydrocarbon molecules, such as pyrolysis oil and syngas.
Pyrolysis Process Description: Step-By-Step Breakdown
In pyrolysis process, pyrolysis plant plays a vital role as a key production carrier. This equipment integrates a variety of components to form various process systems. They include feeding system, furnace, oil condensation system, gas treatment system, and solid residue discharge system. The following video is an example of tyre pyrolysis process for your reference. You can visit our YouTube channel for more videos of the pyrolysis process.
Raw Material Feeding
Raw materials enter the main furnace through different feeding methods. The feeding method is determined by the size and shape of the raw materials. Current mainstream options are: manual feeding, hydraulic feeding and screw feeding. They have different costs and feeding efficiency. Customers can choose according to their actual production needs.
01
Oil Gas Formation
After preheating, the raw materials enter the pyrolysis reactor. The initial heating heat source is provided by the burner. The fuel can be natural gas, diesel and heavy oil. When the reaction temperature is between 280℃ and 350℃, the raw materials undergo thermal decomposition and high-temperature oil gas are formed.
02
Pyrolysis Oil Condensation
- First, the high-temperature oil gas enter the manifold to separate impurities.
- Subsequently, the condensable components enter the condenser such as heavy hydrocarbons, aromatic hydrocarbons, phenols and other organic compounds,
- Next, these gaseous substances come into contact with the heat transfer medium in the condenser and begin to cool down.
- Finally, the liquid pyrolysis oil formed by condensation flows to the oil storage tank under the action of gravity.
03
Syngas Recovery
The water seal purifies non-condensable gases (such as hydrogen, carbon monoxide, methane, etc.) to form syngas. This gaseous fuel enters the combustion system through a pipeline. Thus, it replaces external fuel to provide energy for the entire pyrolysis reaction.
04
Solid Residue Discharging
The pyrolysis reaction separates the volatiles in the raw materials and leaves behind high-temperature solid residues. After the reaction is over, the water-cooled screw conveyor discharges these solids. Generally, the more water-cooled screw conveyors are configured, the better the cooling effect of the solid residues.
05
Comparative Analysis of Pyrolysis Process: Plastics/Oil Sludge/Tyre
Plastic, oil sludge and tyre pyrolysis processes are slightly different. Theses differences mainly include the corresponding configuration schemes and end product composition. The following is a comparative analysis of the pyrolysis processes for these raw materials:
Configuration Plan
- Plastic: Require catalytic tower improve pyrolysis efficiency, reduce wax formation, and optimize product composition.
- Oil sludge: Require conveying devices according to different liquid content, including belt conveyors, shaftless screw conveyors, and sludge pumps.
- Tyre: Require tyre shredder to reduce tire size to accommodate feed requirements. In addition, the process can extract the steel wire from the tyre and reuse it.
The following is a specific process flow of corresponding pyrolysis plant for your reference:
End Product Composition
Pyrolysis oil is the main product of pyrolysis. However, the oil yield of various raw material types is different. In addition, the composition of solid residues after pyrolysis is different. Due to the complex composition of various types of oil sludge, the composition ratio of its pyrolysis products (pyrolysis oil, syngas, solid residue) needs to be determined experimentally. The following is a comparison of end product composition of plastic and tyre.
Plastic
Plastic is a kind of high molecular polymer, the production of plastic requires various additives. Therefore, the solid residue from plastic to oil machine is a mixture of industrial residues and carbon black. In addition, the oil yield of different plastics varies significantly.
Tyre
Tyre is composed of natural rubber, synthetic rubber, carbon black, and metal wire. The tire pyrolysis process generates pyrolysis oil, carbon black, steel wire, and syngas. The proportion of pyrolysis products of various tires is roughly the same.
Key Strategies to Ensure Stable Pyrolysis Process
To maintain the long-term stability of the pyrolysis process, it is necessary to strictly control and adjust the working conditions. In addition, it is also necessary to apply some advanced technologies in the pyrolysis system. Here are some key strategies:
Precise Temperature Control
Precise temperature control ensures stable reaction conditions. This prevents unstable reaction temperature, which can lead to product instability. It is difficult for traditional burners to achieve this condition. Therefore, the equipment can use hot air heating method. The adjustable air volume ratio enables the pyrolysis process to achieve optimal operating conditions.
Flash Explosion Prevention
Flash explosion refers to a dangerous phenomenon caused by sudden release of excessive temperature or pressure during pyrolysis process. To avoid this happens, a nitrogen system can be installed. The system introduces nitrogen to replace excess air and pyrolysis gases before ignition and discharge. This prevents internal pressure overload and mixed gas explosion.
Wax Oil Blockage Prevention
During plastic pyrolysis process, the reaction may produce wax oil. Solidification of wax oil leads to blockage of pipelines or some facilities. Catalytic pyrolysis technology alleviates this problem. Introduction of catalyst solves the problem of decondensation and liquefaction of wax in pyrolysis oil gas. This curbs the generation of solid wax before pyrolysis oil is formed.
Coking Prevention
When processing high carbon content raw materials, local overheating will produce residues that are prone to coking. Coking will damage the inner wall of the reactor and reduce the reaction efficiency. In this case, friction blocks can be added to the main furnace. The friction blocks and the material rotate synchronously to increase thermal conductivity and avoid coking.
Pyrolysis Process Ignites Sustainable Future
The pyrolysis process is at the forefront of sustainable technology. It provides a viable solution for managing and reusing waste materials. This holistic approach not only maximizes energy recovery but also minimizes environmental impact. Thus, this paves the way for a cleaner and more sustainable future. If you are looking for solutions for pyrolysis recycling, please contact Beston Group.
