Coal Substitute Fuel Gets a Boost from Report
- Jun 23, 2020 3:50 pm GMT
London-based Helvellyn Group is a manufacturer of a low environmental impact direct coal replacement fuel for industrial and power generation applications called SERF.
Their fuel is specifically designed to mimic the characteristics of coal, allowing for use of the same fuel delivery, preparation and combustion infrastructure, without modification and resulting in the same combustion characteristics, but with a substantial CO2 emissions reduction.
Although coal substitutes have been used in the past, and currently some power plants are using wood pellets in place of coal, the dirtiest fossil fuel has been essential to not just power generation but industrial processes such as steel making, which makes decarbonizing a headache.
The issue at stake is can coal-fired assets continue to the end of their life-cycle, or will utilities have to decommission them prematurely, because of new environment legislation? That would result in economic losses, so any method of life extension would be welcomed by power suppliers.
SERF is used in place of bituminous coal, with up to 100% substitution. Normal transport and handling processes can be used, and the fuel is water-resistant so it can be stored in external stockpiles.
An analysis by highly-respected consultants Uniper Technologies said Helvellyn Group’s SERF, “is technically suitable for use in large scale thermal power plants in a blend, and potentially up to full substitution, with little or no capital outlay and delivering a net reduction in operating costs.”
Frank Harris, Helvellyn’s CEO, explains how SERF is produced, “Our process is able to take a wide range of carbonaceous feedstocks, including low grade coal, sludges, wastes, and biomass, and produce fuels to a precise specification consistently,” He continues, “We knew that the fuel would work in large-scale powergen, and now we have independent analysis from one of the most experienced companies in the sector, to back that up, emphatically.”
The fuel is normally supplied in 50mm lumps, as shown above, but it can also be purchased as pellets, logs or ground into a fine gravel-like substance.
The company notes that exact fuel specification and presentation can be fine-tuned to meet the specific needs of a given plant. Normally SERF is presented as 50 mm hard, hydrophobic lumps with the following properties: energy >25 kJ/kg (10,750 Btu/lb, 5.97 kcal/kg); ash content <6%; moisture <2%; chlorine <0.07%; carbon >60%; sulfur <0.2%; and nitrogen <0.4%.
The Uniper analysis acknowledges that coal-fired power plants vary considerably in their tendency to suffer from slagging and fouling, and the report highlights that the different ash composition of SERF means that these risks need to be assessed on a case-by-case basis. SERF contains higher levels of calcium and sodium, which increases risks of some types of boiler ash deposition, but it also contains low levels of iron, which is beneficial.
Risks are also dependent on factors including boiler design, operating regime, complementary coal quality, and co-firing levels. Helvellyn has said that plant operators have a range of mitigation measures available should issues arise. The company said the risk of boiler corrosion is low, primarily due to the low chlorine level in SERF, and erosion risks are expected to be reduced as a result of lower ash content and lower flue gas flow rates.
Harris said that using SERF will lead to a reduction in SO2, NOx, and particulate matter, noting that the higher the substitution rate, the lower the levels of each emission. SERF is expected to produce higher boiler efficiencies, together with lower ash remnants.
Whether this technology will succeed in replacing the oldest of the fossil fuels remains to be seen, but it looks promising.
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