text: Abstract Ash conditioning studies have been conducted at Ontario Hydro's 640 MJ/h combustion research facility to reduce high ash resistivities and improve ESP collection efficiencies when burning a low sulphur western Canadian (Luscar) coal, a western Canadian-US coal blend with limestone injection and a low sulphur eastern US coal. The Luscar coal produced a stable flame and carbon burnout was 99.9% Ash resistivities measured in situ ranged between 2.7 x 10^10 to 1.4 x 10^11 ohm.cm. The pilot precipitator performed only with 79% efficiency . S03 conditioning of the Luscar coal ash with 50 ppm S03 decreased the resistivity by 0.7 to 1 order of magnitude and improved the collection efficiency of the ESP. Conditioning the waste from the western Canadian US coal blend during limestone injection was carried out using both S03 and water. Injection of about 60 ppm S03 vapour into the flue gas to condition the limestone injection waste reduced the resistivity by up to 3 orders of magnitude. Humidification of the waste lowered ash resistivity from 2.8 x 10^11 to 1.8 x 10^8 ohm.cm. In both cases ash collection efficiency of the precipitator increased. Injecting a proprietary chemical to condition the ash from a 1.1% S eastern US coal had no effect on the ash resistivity but improved the cohesiveness of the ash causing a slight improvement in ESP performance.
  Type Text
  Format application/pdf
  Language eng
  Rights This material may be protected by copyright. Permission required for use in any form. For further information please contact the American Flame Research Committee.
  Conversion Specifications Original scanned with Canon EOS-1Ds Mark II, 16.7 megapixel digital camera and saved as 400 ppi uncompressed TIFF, 16 bit depth.
  Scanning Technician Cliodhna Davis
  Metadata Cataloger Kendra Yates
  ARK ark:/87278/s6833vmk
  Setname uu_afrc
  Date Created 2012-04-20
  Date Modified 2012-09-05
  ID 4927
  Reference URL https://collections.lib.utah.edu/ark:/87278/s6833vmk
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  Title Page 4
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  S03 CONDITIONING SYSTEM This system, shown in Figure 2, was designed and constructed for studying the effect of S03 conditioning on the resistivity and precipitability of high resistivity ashes such as: ashes from low sulphur coals and sorbent injection wastes. The conditioning system is constructed of 316 stainless steel. The S03 is generated by passing S02 and air slowly over a vanadium pentoxide catalyst bed at approximately 4250C. The oxidation is 99.5% efficient and proceeds according to the following reaction: S02 + 1/2 02 ---> S03· WATER CONDITIONING SYSTEM This system, located upstream of the resistivity probe housing and the ESP consists of a water injection system and the humidification chamber shown in Figure 3a. Its function is to humidify the flue gas for increasing S02 capture, reducing ash resistivity and improving particulate collection at the ESP. The humidification chamber, 19 cm 10 and 5.8 m long, is equipped with four water inj ection ports to provide 1 to 3 s residence time in the humidifier. The water is injected through a Turbotak Caldyn 2 mm nozzle. Water droplet size distribution is shown in Figure 3b. The chamber is also equipped with three ports, 61 cm apart, for inserting thermocouples to measure dry-bulb-wet-bulb temperatures and gas drying times. The water injection system consists of a solenoid valve, electrically controlled by a cyclic timer. The water flow rate is measured by a rotameter upstream of the spray nozzle. CHEMICAL INJECTION FEED SYSTEM The feed system consisted of alL beaker containing an aqueous solution of the proprietary. Three stainless steel control valves on the outlet of an AMF Cuno chemical metering pump provided adequate control to inject the chemical into the flue gas stream via a Turbotak 2 mm twin fluid atomizer. A pressure stabilizer on the outlet side of the pump maintained a head pressure thereby allowing precise injection of the chemical solution. The chemical feed set up is shown in Figure 4. PROCEDURES After steady-state was achieved with the baseline coal under investigation, injection of the appropriate conditioning agent was initiated. In the case of the low sulphur western Canadian Luscar coal, S03 conditioning was carried out, for the sorbent inject waste produced while burning a western CanadianfUS coal blend, both S03 and water conditioning were utilized and for the low sulphur eastern US coal, a proprietary chemical was used to condition the ash. Data collected during each test include system temperatures and pressures, flue gas constituents concentrations (C02 , CO, O2 , S02 and NOx ) in-situ ash resistivities and inlet and outlet dust loadings to the ESP. Ash samples collected isokinetically were analyzed for chemical composition and particle size distribution.