Dry SO sub 2 -Particulate Removal for Coal-Fired Boilers. Volume 1. Demonstration of SO sub 2 Removal on a 22-MW Coal-Fired Utility Boiler by Dry Injection of Nahcolite. Final Report

摘要

A full scale demonstration of the dry removal of SO sub 2 with nahcolite (naturally occurring sodium bicarbonate) was conducted at Public Service Company of Colorado's Cameo Unit No. 1. This is a 22 MW coal-fired boiler retrofitted with a fabric filter. In the dry SO sub 2 removal process nahcolite is pulverized and injected into the flue gas stream ahead of the fabric filter and downstream of the air preheater. The nahcolite collects on the bags and the SO sub 2 is removed as the flue gas passes through the filter cake. The objectives of the program were (1) to demonstrate the operability of the injection technique and the level of SO sub 2 removal attainable on a full scale utility system under typical operating conditions, and (2) to assess the impact of nahcolite injection on the operation of the fabric filter. The test program demonstrated SO sub 2 removals in the range of 75 to 83 percent with the injection of a stoichiometric amount of nahcolite into the flue gas. The rate of reaction between nahcolite and SO sub 2 was decreased when baghouse temperature was reduced from 300 exp 0 F to 275 exp 0 F. This effect lessened the average SO sub 2 removal to nearly 40 percent when injecting near stoichiometric amounts. In addition to SO sub 2 removal, the dry injection of nahcolite also resulted in a simultaneous removal of nitric oxide on the order of 8 percent to 14 percent. Nahcolite injection had no substantial impact on the fabric filter operation. The rate of change in flange-to-flange pressure drop during filtration increased by about 0.1 inch H sub 2 O/h (20 percent) due to nahcolite injection. A second phase of testing is currently planned at the Cameo facility to address the effectiveness of other sodium-based materials as dry SO sub 2 scrubbing agents including trona and soda ash. 28 figures, 16 tables. (ERA citation 08:031095)