Inhibition of lignite ash slagging and fouling upon the use of a silica-based additive in an industrial pulverised coal-fired boiler. Part 1. Changes on the properties of ash deposits along the furnace

Inhibition of lignite ash slagging and fouling upon the use of a silica-based additive in an industrial pulverised coal-fired boiler: Part 3 – Partitioning of trace elements

“…As a consequence, the emission of trace elements from lignite is expected to vary considerably from bituminous coal. Moreover, as has been discussed in our previous papers [15,16], external silica-based additive in a mass fraction of approximately 4.0 wt% is effective in minimising ash slagging and fouling propensity in a lignite-fired boiler. This raises another query regarding the emission of trace elements upon the addition of external silica-based additives.…”

“…As a continuation of our previous works [15,16], this paper aims to clarify the partitioning and emission of twelve trace elements (As, Ba, Be, Co, Cr, Cu, Mn, Ni, Pb, Sr, V, and Zn) from an industrial pulverised lignite-fired boiler. To reiterate, the lignite is originated from Xinjiang (XJ), China, and its ash samples were collected from different locations in a 30 MW th subcritical pulverised-coal fired steam boiler after around two years of operation.…”

“…The schematic of the boiler and its operating conditions have been detailed previously [15,16,22]. In brief, coal particles, either on their own or mixed with silica-based additive, were fed tangentially into the boiler, and the hot flue gas generated passes through a variety of tubes from the flame (combustion) zone with an average temperature of 1300°C through to the furnace exist with a temperature of approximately 130°C.…”

Effects of wall temperature on slagging and ash deposition of Zhundong coal during circulating fluidized bed gasification

“…At melting temperature below 1000°C, sodium silicates would mix with iron, calcium, or magnesium oxides to form eutectics. These eutectics easily adhere to and slag in the coal burners of industrial pulverized coal-fired boilers [10]. Moreover, they cover the surfaces of bed materials or ash particles to form adhesive coating layers, leading to agglomeration or even defluidization [9,11,12].…”

“…In Zijing bituminous coal, a type of Zhundong coal containing 12.77 wt% Na 2 O in coal ash, volatilized Na content was maintained at 20-55 wt% during combustion at 400-1000°C, in which Na volatilization was kept at a high level within 600-900°C [8]. Volatilized Na will adhere, through sulfation [10] or condensation, to the heated surfaces and other ash particles to form a sticky inner layer on the bare heating surfaces or to form a sticky coating surface of bulk ash particles, which are considered as two necessary aspects of ash deposition [4]. Therefore, the existing research is focused on the Na release and transformation during the high-Na coal thermal conversion [8,[13][14][15].…”