A Novel Application of Waste Tyres & plastics as Reburn Fuels for NOx Reduction in Large Scale Combustion Systems

在英国和欧洲，每年都有大量的废旧轮胎和废塑料需要处理。英国每年产生40万吨废旧轮胎，相当于3000万个轮胎。在欧盟，每年生产超过250万吨轮胎和1920万吨塑料。目前，绝大多数产生的轮胎和塑料废物都被填埋，这是对资源的主要浪费。最近的欧盟废物填埋指令（1999年）规定了到2006年禁止在填埋场使用整胎和碎胎的最后期限。此外，欧盟已将废轮胎认定为“优先废物流”。塑料也被视为优先废物流，欧共体包装和包装废物指令（1994年）和欧共体废弃电气和电子设备（WEEE）指令（2000年）为废塑料设定了雄心勃勃的回收和回收目标。此外，欧盟大型燃烧工厂指令（2001/80/EC）适用于广泛的工厂，包括发电站、水泥窑和钢基熔炉，并设定了严格的氮氧化物减排目标，例如，1987年以后建成的现有工厂，要求到2008年将氮氧化物水平降低到500毫克/立方米以下，到2016年将降低到200毫克/立方米以下（对于500MWt的工厂）。虽然使用现有的低氮氧化物燃烧器可以降低氮氧化物水平，但人们担心，改造系统以将氮氧化物降低到新的欧盟大型燃烧工厂指令所要求的低水平，可能无法以合理的成本实现。本提案旨在通过实际的大规模实验方法，研究使用轮胎和塑料两种废物流作为减少大型燃烧工厂NOx的潜在再生燃料。轮胎和塑料的高挥发性和反应性使其具有工艺优势，因为与煤炭相比，所需的燃烧时间更短，这将减轻在现有全规模工厂上改造再生能源技术的压力。实验将使用一个200千瓦时的中试反应堆进行。此外，由于废物燃烧与公众对环境问题的不良看法有关，因此工作的一部分将涉及全面的排放调查，包括酸性气体、微粒、重金属和二恶英。总之，所提出的工作将提供新的信息，并有助于制定将这项技术改造到现有工厂的战略。

Used tyres and waste plastics represent enormous tonnages of waste generated in the UK and Europe each year requiring disposal. Scrap tyre arisings in the UK are 400,000 tonnes per year amounting to 30 million tyres. In the EU, more than 2.5 million tonnes of tyres and 19.2 million tonnes of plastics are generated each year. Currently the vast majority of the tyre and plastics waste generated is landfilled representing a major waste of a resource. The recent EC Waste Landfill Directive (1999) sets a deadline for the banning of whole and shredded tyres from landfill sites by 2006. In addition, the European Union has recognised scrap tyres as a 'priority waste stream'. Plastics are also regarded as a priority waste stream and the EC Packaging and Packaging Waste Directive (1994) and the EC Waste Electrical and Electronic Equipment (WEEE) Directive (2000) set ambitious recycling and recovery targets for waste plastics.Further, the EC Large Combustion Plant Directive (2001/80/EC) applies to a wide range of plant including power stations, cement kilns and steel based furnaces and sets stringent emissions targets for NOx reduction, for example for existing plant built after 1987 plants are required to reduce NOx levels to below 500 mg/m3 by 2008 and below 200 mg/m3 after 2016 (for plants >500MWt). Whilst reduced NOx levels can be obtained by using existing low NOx burners, there is concern that retrofit systems to reduce NOx to the low levels required of the new EC Large Combustion Plant Directive may not be achievable at reasonable cost.This proposal seeks to investigate the use of two waste streams, tyres and plastics, as potential rebum fuels for the reduction of NOx from large combustion plant by way of a practical large scale experimental approach. The high volatility and reactivity of the tyres and plastics give a process advantage due to the shorter bum-out time required compared to coal which would ease the pressure of retrofitting rebum technology on existing full scale plant. Experiments will be undertaken using a 200kWth pilot-scale reactor. In addition, since wastes combustion Is associated with an adverse public perception of environmental concerns, a section of the work will involve a full emissions survey, including acid gases, particulate, heavy metals and dioxins. All together, the work proposed will provide new information and help to develop a strategy for the retro-fit of this technology to existing plant.