The thermochemical process of changing the composition of the organic material by heat without the involvement of oxygen, known as pyrolysis, Pyrolysis has become a popular approach in recent years for recycling plastic waste. It converts plastic materials into valuable and reusable products. These products mainly include gas, petrochemicals, and solid carbon such as pyrolysis oil, carbon black and syngas. Pyrolysis in this context works by breaking the waste of molecular structure through heating in a low oxygen environment at high temperatures in the range of 300°C - 800°C.
Under low oxygen condition and high temperature, the municipal solid waste can be converted into pyrolysis oil, syngas and carbon black by means of pyrolysis in the equipment. The process of the technology involves three stages. The first stage is initial heating and moisture removal, the second stage is primary decomposition, in which solid waste is decomposed into a large number of volatile matter, and the third stage is secondary cracking process, in which the more complex molecules are decomposed into simpler molecules.
Temperature and pressure control remain a major factor influencing product quality and yield. Suitable thermal management provides control over the rate of decomposition reaction and prevents unwanted secondary reactions, which can reduce the product purity and yield of the catalyst and/or process equipment.
Mingjie pyrolysis plants have batch type, semi-continuous type and fully automatic type which are determined by the capacity and working manner.
Batch pyrolysis equipment: Low investment cost and slag discharge efficiency is high. The working capacity of batch pyrolysis machine is 2-15T/D, it is more for small-scale or medium-scale production. The characteristic of batch plastic pyrolysis machine is batch processing of materials. After certain amount of materials are put into pyrolyze in the pyrolysis reactor, the reactor need to be reload after the pyrolysis finishes.
Continuous systems usually have higher efficiency and greater capacity. Full continuous feeding and discharging within 24 hours. Large processing capacity, 35-40T tires and 30T plastics can be processed every day. Longer production cycle with steady working conditions.
Waste tyre pyrolysis plant is made up of several units, which work in sequence. The reactor is the main body for the pyrolysis process. In the reactor, there are heating sources and temperature control system. The water-cooled automatic slag discharge system is fly ash free, high efficiency and can achieve high temperature slag discharge in a short time.
Batch pyrolysis plant is specially designed for recycling organic whole tires or plastics, by using pyrolysis technology to convert solid waste into pyrolysis oil, carbon black and syngas.
The working process for tyre recycling pyrolysis plant is as follows. Feedstock preparation Before loading the feedstock in, you need to make sure that the tyres can be processed whole in batch system or shredded for continuous system.
The feedstock of continuous pyrolysis plant should be less than 5-8mm and need to crush into the rubber powder without steel wire.
Waste tyre pyrolysis process produces many different products with various uses and values. The major liquid product obtained from waste tyre pyrolysis process is called pyrolysis oil, accounting for about 40-45% of the mass of the feedstocks. The calorific value of the pyrolysis oil is generally similar to that of conventional fuel oils, and thus it can be utilized for heating, power supply, and as the feedstocks for further refinery.
The resulting carbon black is a solid product, which accounts for about 30-35% of the output of the tyre recycling process and is primarily used in the rubber industry for tyre sidewalls and rubber mixes, as well as for the production of ink and as a filler material in a range of applications. The steel wire from tyres, which makes up about 10-15% of a tyre, retains a high scrap metal value and can be reused directly in the steel production process.
Syngas production is an opportunity to realize additional energy recovery of biomass, using it to generate process heat or to drive gas engines or turbines and generate electricity.
Waste plastic pyrolysis plants are design for different types of waste plastic. And it deals with the different characteristics of different types of plastic by special design from feeding plastic to discharging plastic all in a sealed and clean operation environment.
The strong processing capacity of the mJ-15 pyrolysis equipment allows for the daily processing of 15-16T tires and 12T plastics. The advanced technology of the system realizes the automatic feeding of the pre-treated plastic, so as to maintain the best condition of the reactor.
Plastic pyrolysis will get a large amount of pyrolysis oil with different properties according to the different compositions of the feedstocks. Polyethylene and polypropylene will get the oil with diesel properties. While polystyrene will get the oil with different hydrocarbon composition. And the amount of dioxins, NOx and SO2 produced from the pyrolysis process is much less than those produced from direct incineration.
With sufficient energy content, gas products from plastic pyrolysis can be used as either fuel for heating purposes or as power generators. The carbon black produced from plastic pyrolysis, unlike tyre pyrolysis, contains high amount of carbon which can be further utilised in various downstream applications.
Tyres and plastics exhibit fundamental differences in chemical composition affecting their pyrolytic behavior. Tyres contain natural rubber, synthetic rubber, carbon black, steel reinforcement, and various chemical additives, while plastics consist primarily of polymer chains with different thermal decomposition pathways.
The different chemical structures lead to different catalytic behaviors, such as reaction rates, optimal temperature and catalyst yield. In general, Tyre recycling needs higher temperature because of the carbon black and cross-linked rubber structures, whereas plastics pyrolysis can occur at lower temperature which depends on the polymer structure.
Co-processing tyres and plastics is a complex issue, that requires investigation into many number of variables. There is a wide range of feedstocks, of unknown behaviour and also process variables in the two plants, which need to be controlled in order to keep both tires and plastic under optimal and safe condition.
Design of the reactor must account for the different thermal expansion coefficients and heating requirements. The need to remove the steel wires from tyres introduces a separation step that may interfere with the processing of the plastic. The separation of the products and the purification of the individual components is also more complex when processing mixed feedstocks that yield different products upon pyrolysis.
Pyrolysis equipment has been already widely adopted in MSW treatment, which means it can solve the MSW, while also provide resources to make energy and product through pyrolysis. The combined processing method will lead to a drastic reduction in landfill waste and also effectively divert tire and plastic waste from landfill disposal.
The gas products generated through the pyrolysis process generally have higher energy content than syngas produced through gasification, enabling greater energy recovery from biomass. This increase in energy recovery from biomass ultimately results in less fossil fuel consumption and lower associated greenhouse gas emissions.
An integrated facility using combined tyre and plastic recycling capacity would be more capital and resource efficient. Resource such as heating and cooling sources as well as material storage areas can be utilised in common across multiple products, thereby reducing marginal processing costs. In addition, utilising multiple end products in the recycling market can provide a more stable margin over time by spreading risk as opposed to being a monopoly supplier of a single commodity.
Recent developments in the process technology focus on increasing thermal efficiency and flexibility for process control. New heat transfer surfaces enable more efficient energy utilisation under optimal reaction conditions. Optimized catalysts and structures contribute to product quality and maximum yield.
Special flue gas treatment system. Special emission purification system. We develop innovative concepts that meet the increasing demands of environmental protection while at the same time increasing efficiency.
The core competences and assets developed over many decades can be meaningfully expanded with the integration of emerging technologies including robotic processing, AI, and a wide range of convertible feedstocks. Smart control based on machine learning ensures that the entire production process is continuously monitored and individually optimised in real time, which leads to much better product properties and significantly higher plant efficiency. Further potential for high added value can be achieved in future material recycling in such a way that more material can be extracted from what was previously considered waste, thus opening up more opportunities for use.
Mingjie Group is always focused on the research of the advanced environmental protection technology and the promotion of the sustainable development. We strives to eliminate pollution through new technology. The development of the future will be circular economy combined with pyrolysis technology, transforming solid waste into resources, achieving the recycling development of materials in closed-loop system and helping to control the waste and to improve the resource utilization.
