Tyre pyrolysis process refers to turning waste tires into useful resources, including fuel oil, carbon black, etc. Compared to other disposal methods, pyrolysis technology has proven to be the most ideal approach for mitigating tire pollution.
Existing Shortcomings in Tire Handling
Apart from pyrolysis, major methods of waste tire disposal include accumulation and landfilling, retreading, rubber powder production, and heat energy utilization. However, each method has its notable drawbacks.
- This occupies land resources, and may contaminate groundwater.
- This easily breeds mosquitoes, spreading diseases such as dengue fever.
- This poses the risk of fire hazards, harming the environment.
- Refurbished tires may experience a decrease in performance, leading to potential safety risks.
- Tires can only be retreaded two or three times at most, thus a more radical solution is still needed.
- This requires high level of technical expertise, leading to high investment costs.
- Recycled rubber powder may not perform as well as new rubber, limiting market demand and, consequently, the volume of tire recycling.
- Burning waste tires directly generates persistent organic pollutants (dioxins, furans, etc.) and heavy metal pollutants (Zn, Cd, Ni, Pb, etc.). This poses a serious threat to the environment and human health.
Over a billion used tires are generated worldwide each year. The majority of these discarded tires cannot naturally decompose. Each of the aforementioned four methods has its own shortcomings. Fortunately, the increasingly mature high-temperature pyrolysis technology offers an ideal solution for the disposal of waste tires
What Is Tire Pyrolysis?
Tire pyrolysis refers to the process where tire waste undergoes thermochemical decomposition at high temperatures in an inert oxygen-free atmosphere to yield pyrolysis oil, carbon Black, steel wire, and syngas. It is a very complex process which cannot be completely described by one or several chemical reactions. This method represents a sustainable approach to waste tire management, addressing environmental concerns while creating economic opportunities.
Tire Pyrolysis Process: A Closer Look
Process waste tires through a shredder and dryer to meet size and moisture requirements for tire pyrolysis feeding.
Feed the small chunks of tires that meet the feeding standards into the pyrolysis reactor by auto-feeder or manual. Then seal the feeding inlet door tightly and make sure there is no gas leakage.
Initiate the combustion chamber to heat the reactor. As the temperature rises, the heat induces various decomposition and volatilization reactions such as cracking, dehydration, isomerization, aromatization, dehydrogenation, and condensation. At around 180°C-350℃, oil gas is generated, subsequently entering the pipeline manifold. Afterward, heavy oil is collected in the sludge tank, while light oil gas ascends and enters the condensation system.
After passing through the condenser, most of the gas liquefies into pyrolytic oil rich in aromatic compounds. Syngas that cannot be liquefied under normal pressure will be treated and return to the combustion chamber to provide heat to the reactor.
The hot exhaust gas discharged during the pyrolysis process enters the dedusting system after being cooled. After dust removal treatments such as water washing, spraying, ceramic ring adsorption, and activated carbon adsorption, the gas emissions meet the standards.
After finishing oil production, the temperature of the reactor will be cooled down, when the temperature falls down to 50-80℃, we can discharge the carbon black and steel wire automatically or manually.
Is the Process Safe?
Pyrolysis reactions occur in high-temperature, oxygen-free conditions, producing combustible gases. Unintentional oxygen exposure can lead to fire or explosion risks. Therefore, various safety measures are required in the modern tire pyrolysis process to ensure safety. Correspondingly, Beston has implemented stringent safety measures in the design of its tire pyrolysis plant:
- We use a nitrogen generator with a purity exceeding 95% to replace the air in the feeding system. This prevents excess air from entering during feeding. Consequently, it maintains an oxygen-deficient environment inside the reactor, ensuring a safer pyrolysis process.
- Our design incorporates multiple safety measures, including explosion-proof valves, safety instruments, and multi-point monitoring. These measures enable real-time monitoring of temperatures and pressures across various components, ensuring the safe operation of the equipment.
- The design strictly follows national standards, mechanical industry standards, etc. We hold CE/ISO/SGS certifications. The safety and reliability of the product are ensured.
- Our engineers will visit the installation site to carry out professional installation, debugging, and safety hazard assessments. This ensures that the initial installation can pass local safety assessment tests.
Is the Process Environmentally Friendly?
Compared to other tire disposal methods, tire pyrolysis stands out for its remarkable environmental advantages. Beston’s tire pyrolysis equipment achieves clean production through ingenious processes, minimizing its environmental footprint.
No wastewater is generated throughout the entire production process. Water is primarily used in three stages. Every part of the water will be recycled, with no wastewater discharge.
- Circulating cooling water functions solely for cooling throughout the process. It carries away heat from cooling pipes without coming into contact with oil gas, thus avoiding wastewater generation.
- In the non-condensing gas treatment process, the water used in the water seal generates a small amount of wastewater with weak acidity. After neutralization with a weak alkaline solution and filtration, this wastewater achieve harmlessness, suitable for subsequent use in the misting desulfurization tower.
- In the flue gas dedusting process, the misting desulfurization tower generates wastewater. Upon adding Ca(OH)₂ to water, Ca(OH)₂ reacts with sulfides (SO₂, H₂S) in the flue gas, ultimately forming a mixture of CaSO3 and CaS. This mixture will serve as a purifying agent for the water. As the pyrolysis process continues, the water can be recycled after replenishing with water and Ca(OH)₂.
- Following dedusting in the spray tower, more than 95% of sulfur-containing particulate matter in the exhaust gas from the combustor is efficiently eliminated.
This ensures that the emissions meet standards and resolves the issue of emitting black smoke. - In tire pyrolysis process, some syngas that cannot be liquefied at normal temperature and pressure are produced. The syngas passes through the water seal, flame arrester, and then enters the combustor. In the oxygen-enriched state facilitated by the draft fan, syngas will be fully burned.
- The solid residues produced from waste tire pyrolysis are mainly coarse carbon black and steel wires. They can be sold directly or reprocessed.
- The mixture of CaSO3 and CaS generated during the treatment of weak acidic wastewater, after collection, filtration and drying, can be used as road base material.
Factors Influencing Tire Pyrolysis Process
The tire pyrolysis process is a complex technology influenced by various factors. These factors directly impact its efficiency, product quality, and environmental friendliness. Here are the key factors affecting the tire pyrolysis process:
The chemical composition, additives, moisture content, and size of the tires can result in different types and properties of pyrolysis products.
Residence time primarily affects the completeness of the pyrolysis reaction and product composition. Longer reaction times help in more thorough decomposition of raw materials, but excessive residence time may lead to further cracking of gases and oils, affecting product quality.
Temperature is a critical parameter in tire pyrolysis, directly influencing the efficiency and product distribution. Higher temperatures facilitate the breakdown of high-molecular-weight polymer chains, promoting pyrolysis reactions and the production of pyrolysis oil. However, excessively high temperatures may lead to increased gas production and energy consumption.
The heating rate significantly affects the generation of pyrolysis products. By combining temperature and heating rate, the proportions of different components in the pyrolysis products can be controlled. Lower temperatures and slower heating allow for sufficient time for organic molecules to decompose and recombine, increasing the solid content in the products. Higher temperatures and faster heating result in widespread breakdown of organic molecules, increasing the gas component in the pyrolysis products.
The design of the reactor directly determines heat and mass transfer efficiency, influencing the overall energy efficiency and stability of the pyrolysis process. Pyrolysis units are typically classified into horizontal rotary kilns and vertical kilns. Horizontal rotary kilns ensure uniform heating and thorough pyrolysis, making them the most common equipment for waste tire oil refining.
Catalysts play a crucial role in enhancing the conversion rate of waste tires and improving product quality during pyrolysis oil refining. Introducing suitable catalysts can lower reaction temperatures, reduce energy consumption, and increase product selectivity and yield. However, the necessity of using catalysts depends on the specific goals and practical conditions of tire pyrolysis.
Tire pyrolysis at Beston Group
Beston Group offers both batch and continuous pyrolysis plant to cater to diverse production needs. The batch system allows for the processing of a specific quantity at a time, requiring a shutdown for unloading and loading after each batch. It is suitable for small-scale production with relatively lower investment costs. On the other hand, the continuous system enables uninterrupted operations, eliminating the need for shutdowns during unloading and loading. It is ideal for handling large volumes of waste tires.
Our tire pyrolysis solutions have been exported to more than 100 countries. Success stories from customers worldwide highlight the effectiveness of our technology in efficiently converting discarded tires into valuable resources.
Beston Group takes pride in providing comprehensive services to investors embarking on tire pyrolysis projects. Our one-stop service includes project planning, equipment installation, training, and continuous support. Customer satisfaction is our top priority, ensuring that every stage of the tire pyrolysis project is seamless and successful.
