Sustainable Development Goals
Globally nearly two billion end-of-life tires (ELTs) are discarded annually which is drawing significant attention from society. This case study reviews a project the KleanTeam undertook in South Korea, a small country that produces in excess of 500,000 metric tonnes of scrap tires each year. The recycling rate of waste tires in South Korea is estimated at approximately 70% with a large percentage of these scrap tires being used for tire-derived fuel (“TDF”) as an alternative to coal for power production.
Tires are complex materials manufactured from vulcanized rubber and various other reinforcing materials. Current options for their disposal include reuse, retreading, regeneration, co-processing, pyrolysis, recycling, incineration, and landfilling; however, the ideal solution must be looked at on a case-by-case basis. A solution that works for one country may not work for another based on size, location, the volume of end-of-life tires, industrial activity, disposal, and the potential opportunity for resource recovery. Also, a key consideration is the products derived from scrap tires and the end-use opportunity that can be applied within the country. In each case, the best practice is always to undertake an economic and technical feasibility study, known as a Detailed Feasibility Study (“DFS”) combined with Life Cycle Assessment (“LCA”) to quantify the impact and support the decision-making process in order to determine what solution will deliver the highest returns both environmentally and financially.
The KleanTeam undertakes these scientific studies on specific projects and has carried out a vast number of these assignments on different continents, mainly Europe, Asia, and America. The main treatment options were reviewed as well as the most important limitations and aspects of the technologies studied and the best options available for reuse. Energy recovery has been one of the most widely used processes which has shown good performance, largely due to the emissions prevented through energy conversion.
To address the current shortfalls of scrap tire recycling in South Korea a concept was developed for the implementation of a cogeneration plant that would cleanly burn coal and TDF to supply electricity, steam, and purified water to businesses in the Yeosu Industrial Complex, in Busan, South Korea.
After 2 years of planning a Circulating Fluidized Bed Combustion technology was chosen as the Best Commercially Available Technology (“BCAT”) for co-processing coal and TDF to produce electrical power, steam, and heat in a cogeneration format. After technology vetting, Sumitomo Heavy Industries (“SHI”) was selected as the best technology provider who was a licensee of Foster Wheeler’s (“FW”) advanced CFB multifuel technology that can provide highly reliable power and combined heat & power generation burning a wide range of biomass and waste fuels while producing extremely low emissions.
SHI has made significant improvements to the FW technology over the past 30 years as the exclusive licensee for Japan since 1986 and a non-exclusive license for the rest of Asia. In June of 2009, and a total of 3-year construction, Kumho Petrochemical (“KP”) implemented and commissioned the first TDF co-firing Circulating Fluidized Bed Combustion (“CFBC”) boiler plant in South Korea.
The project consisted of 2 CFBC lines that consume 250 metric tonnes of coal per hour in each line for a total processing capacity of 500 metric tonnes per hour. In a 24-hour period that equals 12,000 metric tonnes of coal per day; now that’s a big plant that has a massive appetite. This plant was designed to be able to use up to a maximum 20-30% TDF (2,400 to 3,600 metric tonnes of 2” shredded tires per day / up to 1,188,000 tonnes of scrap tires per year) that could be substituted as feedstock instead of coal.
Upon completion of this project and after 2 years of fine-tuning the tire chip feed, so that steel wire volumes were controlled to prevent reactor fouling, KP committed to building another project consisting of 2 CFBC lines which consume 400 metric tonnes of coal per hour in each line for a total processing capacity of 800 metric tonnes per hour. In a 24-hour period that equals 20,200 metric tonnes of coal per day, which is a beast of a power plant.
It was an extremely audacious goal for KP to think it could secure anywhere near that kind of volume of scrap tires given South Korea itself only produces approximately 500KTPA of which 70% is already being recycled each year in the local economy. As a result, this meant that a vast majority of TDF was needed for the first project and the second would need to be imported as a result or the feedstock would need to be further diversified with biomass or Solid Recovered Fuel ("SRF”). The CFBC technology was the right selection for these projects because of its fuel-flexible capabilities in its clean-burning process and its ability to take full advantage of local and diversified fuel mixes. Notably, the fuel flexibility of CFBC boilers allows them to fire solid wastes as well as local agricultural and industrial waste, crop, and forestry residues beyond coal and scrap tires.
However, these two TDF projects are a great illustration of why bigger is not always better. And as a result of them, scrap tires became overvalued in South Korea from a recycling perspective and the sheer volume of waste tire imports became a significant challenge to the point where in reality only a small percentage of scrap tires are actually substituted and co-processed with coal.
The end result is the conservation of energy and finite resources through improved plant performance and better industrial efficiencies (approximate values):