The Cynar Technology

Current situation of recycling of plastics Pyrolysis Structure of the System Operations

The system uses liquefaction, pyrolysis and distillation of plastics. The system can handle almost all the plastic that is currently being sent to landfills.

A major advantage of the process is its high efficiency. Each plant can produce up to 19k litres of fuel from 20 tonnes of waste plastic.

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Current situation of recycling of plastics

Various methodologies have been tried and tested to process waste plastics for many years, with recycling becoming the most common method reflecting the needs of the time. Plastics that cannot be processed are handled by waste management companies by normal landfilling or incineration.

The building or expanding of incinerators has become difficult due to opposition from governments and community groups with environmental concerns, most notably the levels of emissions.

Liquefaction of plastic is a superior method of reusing this resource. These distillate products are excellent fuels and make the Cynar Technology one of the best, economically feasible and environmentally sensitive recycling systems in the world today.

The synthetic fuels produced, given their low sulphur and high cetane qualities, will most likely be blended into a larger pool for use in trucks, buses, trains, boats, heavy equipment and generators.

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Pyrolysis

Pyrolysis is a process of thermal degradation in the absence of oxygen. Plastic waste is continuously treated in a cylindrical chamber and the pyrolytic gases condensed in a specially-designed condenser system to yield a hydrocarbon distillate comprising straight and branched chain aliphatics, cyclic aliphatics and aromatic hydrocarbons. The resulting mixture is
essentially equivalent to petroleum distillate. The plastic is pyrolised at 370ºC-420ºC and the pyrolysis gases are condensed in a 2-stage condenser to give a low sulphur content distillate.

The essential steps in the pyrolysis of plastics involves:

1. evenly heating the plastic to a narrow temperature range without excessive temperature variations
2. purging oxygen from pyrolysis chamber,
3. managing the carbonaceous char by-product before it acts as a thermal insulator and lowers the heat transfer to the plastic
4. careful condensation and fractionation of the pyrolysis vapours to produce distillate of good quality and consistency

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Structure of the System

The system consists of stock infeed system, pyrolysis chambers, contactors, distillation, centrifuge, oil recovery line, off-gas cleaning, and residual contamination removal.

Waste plastics are loaded via a hot-melt infeed system directly into main pyrolysis chamber.

Agitation commences to even the temperature and homogenise the feedstocks. Pyrolysis then commences and the plastic becomes a vapour. Non-plastic materials fall to the bottom of the chamber.

The vapour is converted into the various fractions in the distillation column, the distillates then pass into the recovery tanks.

From the recovery tanks, the product is sent to a centrifuge to remove contaminants such as water or carbon.

The cleaned distillates are then pumped to the storage tanks.

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Operations

The heart of the pyrolysis system is the prime chamber, which performs the essential functions of homogenisation, controlled decomposition and outgassing in a single process. The process requires minimal maintenance apart from carbon residue removal, and produces consistent quality distillate
from mixed and low-grade plastic waste.

The key to an efficient pyrolysis process is to ensure the plastic is heated uniformly and rapidly. If temperature gradients develop in the molten plastic mass then different degrees of cracking will occur and products with a wide distribution of chain lengths will be formed.

Another important aspect of pyrolysis is to use a negative pressure (or a partial vacuum) environment. This ensures that oxidation reactions are minimised and that gaseous pyrolysis vapours are quickly removed from the process chamber thereby reducing the incidence of secondary reactions and the formation of undesirable by-products.

The polymer is gently 'cracked' at relatively low temperatures to give predominantly straight chain aliphatic hydrocarbons with little formation of by-products. These hydrocarbons are then selectively condensed and cleaved further catalytically to produce the average carbon chain length required
for distillate fuel.

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