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- Fleig, Daniel, 1980, et al.
(författare)
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Evaluation of SO3 Measurement Techniques in Air and Oxy-Fuel Combustion
- 2012
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 26:9, s. 5537-5549
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Tidskriftsartikel (refereegranskat)abstract
- SO2 is enriched in wry-fuel combustion due to flue-gas recycle, and a significant higher SO3 concentration can be expected compared to air-firing. Since SO3 can cause high and low temperature corrosion, it is important to measure the SO3 concentration under oxy-fuel fired conditions. However, measurement of SO3 is not straightforward, since SO3 is a highly reactive gas. This paper presents an experimental study in the Chalmers oxy-fuel test unit, comparing different SO3 measurement techniques applied during oxy-fuel and air combustion. Propane (60 kW(th)) was used as fuel and SO2 was injected in the oxidizer to generate a controllable amount of SO3. The SO3 concentration was measured with four techniques: the controlled condensation method, the salt method, the isopropanol absorption bottle method, and with the Pentol SO3 monitor (previously: Severn Science analyzer). The controlled condensation method was used as the standard for comparison. Additionally, the acid dew-point temperature was measured with a dew-point meter. The controlled condensation and the salt method gave comparable results, and the repeatability with these methods was good. The SO3 concentrations measured with the Pentol SO3 monitor differed in average less than 20% from the SO3 concentrations obtained with the controlled condensation method. With the isopropanol absorption bottle method, a large amount of the SO2 was absorbed in the isopropanol solution, which gives a positive bias if the SO2 is oxidized to sulfate in the isopropanol solution. This was minimized by reducing the measurement time, bubbling argon through the absorption bottles after the measurement to force the SO2 out, and analyzing the solution immediately after the measurement. No principal differences between measuring the SO3 concentration during oxy-fuel combustion and air-firing were obtained. However, a correction factor for the mass flow meter of the Pentol SO3 monitor has to be used because of the high CO, concentration during oxy-fuel operation.
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| 2. |
- Vainio, Emil, et al.
(författare)
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Experimental evaluation and field application of a salt method for SO3 measurement in flue gases
- 2013
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 27:5, s. 2767-2775
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Tidskriftsartikel (refereegranskat)abstract
- In this study, an SO3 measurement technique was evaluated and developed. In the method, a salt is used to capture gaseous SO3/H2SO4. Various salts were tested to evaluate the suitability to measure SO3/H2SO4 without interference from SO2. Salts tested include NaCl, KCl, K2CO3, and CaCl2. The salts were tightly packed into a Teflon tube, and the gas was fed through the salt tube with subsequent reaction between SO3/H2SO4 and the salt with formation of sulfates of the respective salt. After the measurement, the salt was dissolved in water, and the solution was analyzed for sulfate ions. The SO3/H2SO4 concentration in the flue gas could then be determined because the gas volume flowing through the salt was measured together with the amount of sulfate bound in the salt. The method was tested in laboratory conditions, in a 100 kW(th) test unit during air-firing and oxy-fuel combustion, and in an industrial boiler. A first attempt to continuously measure SO3/H2SO4. indirectly with an FTIR, by measuring the release of HCl in the sulfation of KCl, was also made. The conversion of SO3 to H2SO4 in flue gas conditions is discussed. It was found that at the measurement conditions almost all SO3 is present as H2SO4. Therefore, the laboratory study was made with gaseous H2SO4 instead of SO3. The laboratory tests showed that all salts captured all H2SO4. The best selectivity toward H2SO4 was shown for NaCl and KCl; no significant amount of SO2 was captured in these salts. An in situ implementation of the salt method using KCl as salt was used during heavy oil combustion in a Kraft recovery boiler. The salt method showed to be an accurate, inexpensive, and easy way to measure SO3/H2SO4. in flue gases.
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