Dry Sorbent Injection of Sodium Sorbents for SO₂, HCl and Mercury Mitigation

Solid waste incinerators emit air pollutants such as SO₂, HCl, and mercury. Dry sorbent injection of sodium sorbents has emerged as an important SO₂, HCl, and mercury mitigation technology due to its (a) low capital cost; (b) small installation foot print; (c) ease of operation; and (d) flexibility to fuel changes. In a dry sorbent injection system, trona or sodium bicarbonate is injected directly into hot flue gas. After injection, the sorbent is calcined into porous sodium carbonate that reacts with acid gases (SO₂, HCl and SO₃). This technology is able to achieve high removal rates for HCl (>99%) and SO₂ (>90%), and has been implemented at many waste incinerators in Europe and coal-fired power plants in the United States. With the promulgation of MACT rules, this technology will be a low-cost and easy-to-use option for waste-to-energy boiler owners.