The
emission characteristics of Cl were investigated on the basis
of the field experiments at three 410 t/h circulating fluidized bed
boilers co-firing petroleum coke and coal. All of the boilers were
equipped with advanced air pollutant control devices (APCDs) to meet
the ultralow emission requirement, such as selective non-catalytic
reduction, electrostatic precipitator (ESP) or fabric filters (FFs),
and wet flue gas desulfurization (WFGD). Gaseous Cl was sampled simultaneously
at both the inlet and outlet of the ESP or FFs and at the outlet of
the WFGDs based on U.S. Environmental Protection Agency Method 26A.
Feed fuel, limestone, bottom ash, ESP or FF ash, limestone slurry,
flush water, wastewater, and gypsum were also sampled to determine
Cl in each stream. Results showed that more than 86.1% of total chlorine
was emitted into the flue gas in the gaseous form (e.g., HCl and Cl2). HCl was the dominant species in the flue gas at the outlet
of boilers, accounting for 85.1–88.0%. The removal efficiencies
of total chloride are 15.6% by ESP and 19.0–19.7% by FFs, respectively.
The removal efficiencies of total chloride by WFGDs are in the range
of 91.2–96.1%. The majority of total chlorine went into wastewater
and gypsum, accounting for 76.16–80.19 and 11.35–12.76%,
respectively. About 1.4–4.3% of total Cl was finally emitted
into the atmosphere.