Thermal Recycling Issues of Vinyl Chloride - March 2000

Thermal Recycling Issues of Vinyl Chloride - March 2000

Vinyl chloride (PVC) is a widely used plastic material, but several important issues exist in its thermal recycling (heat recovery recycling). These are detailed below.

1. low energy efficiency
PVC is less energy efficient in thermal recycling than other plastics. In thermal recycling, energy is recovered by burning waste plastic, but in the case of polyvinyl chloride, the energy obtained from this process is less efficient than the energy required for combustion. This is because the molecular structure of vinyl chloride prevents the combustion process from generating energy efficiently enough.

2. formation of toxic substances
The biggest problem with vinyl chloride is that it produces toxic hydrogen chloride (HCl) gas during combustion. Hydrogen chloride is toxic to the environment and human health, and when released into the atmosphere can cause acid rain as well as seriously affect the respiratory system. For this reason, dehydrogen chloride treatment is essential for thermal recycling of waste plastics containing vinyl chloride.

3. need for special equipment
In order to prevent the generation of hydrogen chloride from the combustion of vinyl chloride, it is necessary to perform hydrogen chloride dehydrogenation treatment prior to combustion. This treatment requires expensive equipment made of special corrosion-resistant materials, which significantly increases treatment costs. In addition, the dehydrochlorination process requires advanced technology, and maintenance of the equipment is complicated.

Recommendation of Alternative Recycling Methods
Because of these problems, material recycling (recycling for reuse as a material) is recommended for vinyl chloride rather than thermal recycling. In particular, it is suitable for use as durable products such as agricultural vinyl houses, electric wire covering materials, and water pipes, etc. In these applications, sorted collection is relatively easy and high purity recycling is possible.

5. restriction of use from the viewpoint of environmental consideration
From the standpoint of environmental considerations, it is desirable to limit the use of vinyl chloride to durable products and to minimize its use in situations where thermal recycling is required. This will minimize the environmental impact of the vinyl chloride recycling process.

For these reasons, thermal recycling of vinyl chloride poses significant challenges and requires careful attention in its use and disposal methods.