Evaluation of Air Pollution Abatement Systems for Multiple-Hearth Sewage Sludge Incinerators

摘要

Capital and annual costs were calculated for the application of six different air pollution control system options to municipal sewage sludge incinerators that were using multiple-hearth furnaces. The systems involved three principal types of air pollution equipment--wet scrubbers, fabric filters, and electrostatic precipitators--applied to three different plant sizes (plants incinerating 36, 72, and 300 tons of dry sludge per day in one, two, and eight multiple-hearth furnaces, respectively). The six options were: (1) venturi/tray scrubber with a 40-inch pressure drop, (2) fabric filter system operating at 500 deg and equipped with an upstream temperature control, (3) fabric filter system operating at 500 deg and equipped with a heat exchanger and a scrubber for SO2 reduction, (4) electrostatic precipitator (ESP) with upstream limited temperature and humidity control, (5) same as Option 4 but with an additional downstream wet scrubber for SO2 reduction, and (6) ESP with upstream temperature control and an SO2 scrubber. Technical feasibility studies indicated that all three types of controls could achieve a total particulate removal efficiency of 99 percent. The venturi/tray scrubber option entailed the lowest capital cost, but annual operating costs were highest because of the high pressure drops and increased energy use.