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Hans T. Karlsson - One of the best experts on this subject based on the ideXlab platform.

  • LIMESTONE BASED Spray Dry SCRUBBING OF SO2
    Chemical Engineering Science, 2001
    Co-Authors: Ann-mari Strömberg, Hans T. Karlsson
    Abstract:

    Spray Dry scrubbing for emissions control has emerged during recent years. Worldwide, more than fifty Spray Dry Scrubbers are in operation or under construction for the control of SO2 on coal fired boilers. Virtually all of these units utilize a slurry of slaked lime as a reactive agent for SO2 capture. The cost of lime is several times the cost of limestone, so it would be a great advantage if limestone could be used in the process. Research on Spray Dry scrubbing has been underway for over six years at our department. The investigation on which the present paper is based was undertaken to study the prospects for Spray Dry scrubbing of SO2 by utilizing a slurry of finely ground limestone. The experiments were performed in a 0.5 MWth pilot plant, consisting of a Spray Dryer and a fabric filter system. The slurry was prepared from limestone ground to various particle sizes. Parameters investigated were the approach to the adiabatic saturation point, the stoichiometric ratio (CaCO3/SO2), and the addition of CaCl2, which would result from the chlorine in the coal. Furthermore, the impact of the pressure drop over the fabric filter on SO2 removal was studied. The experimental results showed that ground limestone can remove SO2 efficiently in a Spray Dry Scrubber system. A significant contribution to the removal occurs in the fabric filter. The removal increases as the surface area of the limestone increases due to grinding. However, a limiting value of the removal over the Spray Dryer is obtained at quite modest surface areas. This is caused by agglomeration of smaller particles at low pH values; as the droplets are contacted with the flue gas, the pH drops due to hydrogen ion production from hydrolysis of SO2. This was seen by measuring the paricle size distribution at different pH values. Hence, while the gas—solid reaction in the fabric filter depends on the surface area, the rate for the gas—liquid—solid reaction in the droplets depends on the particle or agglomerate size.

Ann-mari Strömberg - One of the best experts on this subject based on the ideXlab platform.

  • LIMESTONE BASED Spray Dry SCRUBBING OF SO2
    Chemical Engineering Science, 2001
    Co-Authors: Ann-mari Strömberg, Hans T. Karlsson
    Abstract:

    Spray Dry scrubbing for emissions control has emerged during recent years. Worldwide, more than fifty Spray Dry Scrubbers are in operation or under construction for the control of SO2 on coal fired boilers. Virtually all of these units utilize a slurry of slaked lime as a reactive agent for SO2 capture. The cost of lime is several times the cost of limestone, so it would be a great advantage if limestone could be used in the process. Research on Spray Dry scrubbing has been underway for over six years at our department. The investigation on which the present paper is based was undertaken to study the prospects for Spray Dry scrubbing of SO2 by utilizing a slurry of finely ground limestone. The experiments were performed in a 0.5 MWth pilot plant, consisting of a Spray Dryer and a fabric filter system. The slurry was prepared from limestone ground to various particle sizes. Parameters investigated were the approach to the adiabatic saturation point, the stoichiometric ratio (CaCO3/SO2), and the addition of CaCl2, which would result from the chlorine in the coal. Furthermore, the impact of the pressure drop over the fabric filter on SO2 removal was studied. The experimental results showed that ground limestone can remove SO2 efficiently in a Spray Dry Scrubber system. A significant contribution to the removal occurs in the fabric filter. The removal increases as the surface area of the limestone increases due to grinding. However, a limiting value of the removal over the Spray Dryer is obtained at quite modest surface areas. This is caused by agglomeration of smaller particles at low pH values; as the droplets are contacted with the flue gas, the pH drops due to hydrogen ion production from hydrolysis of SO2. This was seen by measuring the paricle size distribution at different pH values. Hence, while the gas—solid reaction in the fabric filter depends on the surface area, the rate for the gas—liquid—solid reaction in the droplets depends on the particle or agglomerate size.