Industrial tests of co-combustion of alternative fuel with hard coal in a stoker boiler

This paper presents the results of industrial research on co-combustion of solid recovered fuel (SRF) with hard coal in a stoker boiler type WR-25. The share of SRF in the fuel mixture was 10%. During the co-combustion of SRF, no technological disturbances of the boiler were noted. The obtained SO₂ and NO_X emissions were comparable with coal combustion, but dust emissions increased. During the co-combustion of the coal mixture with 10% of alternative fuel, acceptable standards for co-incineration of waste were exceeded for NOx, dust, CO, HCl, HF, heavy metals, dioxins, and furans. The by-products of waste co-combustion with coal were non-hazardous waste. The obtained results constitute a very important contribution to the process of boiler retrofitting toward a waste co-incineration unit, and to meeting the legislative and environmental requirements. <i>Implications</i>: Due to some challenges related to waste storage and transportation, combustion in incineration plants and Waste-to-Energy plants is not possible. The adaptation (formal and technical) of medium scale boilers as co-incineration plants reveals high potential. Nevertheless, the lack of experience and investigations of waste co-combustion in real industrial scale grate boilers is observed. Thus, the implication of this article results consists of the investigations using industrial scale mechanical grate boiler (different from incineration type). Moreover, the investigations were carried out in a low-capacity boiler (~50% of nominal capacity). This novel experience is very important because reduced heat dissipation into the grid caused by high ambient temperatures occurs very frequently. These tests are valuable from the point of view of retrofitting the unit to obtain technological and emission parameters that would allow obtaining the status of a waste co-incinerating unit. The results of these investigations are addressed to power plant management board and engineering staff.

本论文报告了在WR-25型炉排锅炉中开展的固体回收燃料（solid recovered fuel, SRF）与硬煤混烧的工业研究成果。燃料混合物中SRF的占比为10%。在SRF混烧过程中，未观测到锅炉出现任何技术扰动。测得的二氧化硫（SO₂）与氮氧化物（NOₓ）排放水平与纯硬煤燃烧时相当，但粉尘排放量有所上升。当采用含10%替代燃料的煤基混合物进行混烧时，氮氧化物、粉尘、一氧化碳（CO）、氯化氢（HCl）、氟化氢（HF）、重金属、二噁英及呋喃类污染物的排放超出了废弃物混烧的可接受标准。煤与废弃物混烧产生的副产物属于非危险废物。本次研究所得成果，可为锅炉改造为废弃物混烧机组的工作，以及满足相关法规与环保要求提供重要支撑。

**应用启示**：由于废弃物存储与运输环节存在诸多挑战，现有焚烧厂及垃圾焚烧发电厂难以开展此类混烧作业。将中型锅炉进行合规性与技术层面的改造，使其成为混烧机组，展现出极高的应用潜力。但目前，针对真实工业规模炉排锅炉开展的废弃物混烧试验与经验积累仍较为匮乏。因此，本研究成果的核心应用启示在于，采用工业级机械炉排锅炉（区别于专用焚烧炉）开展混烧试验。此外，本次试验在额定负荷约50%的低容量锅炉中开展。此次试验积累的全新经验具有重要价值，因环境高温导致的电网散热受限情况时有发生。从机组改造角度而言，本次试验可为获取符合废弃物混烧机组资质所需的技术与排放参数提供宝贵参考。本次研究成果可供电厂管理层与工程技术人员参考。