(739f) Single Step NO, SO2 and CO2 Removal From Gas Mixtures Using Calcium Sorbent and Char - Optimization of Process Parameters

Prior research has shown the effectiveness of carbon, derived from inexpensive sources like coal char, in controlling post-combustion NO_x emissions. The reduction of NO using char is a widely researched phenomenon. Some of the existing combustion modification methods such as re-burning employ this principle to reduce NO emissions. Pure carbon materials require very high temperatures for the C-NO reaction. However, the presence of mineral matter in char and the presence of O₂ in flue gas significantly reduce the required temperature of NO capture. Studies conducted at OSU have revealed that up to 98% reduction in NO levels using bituminous and lignite chars is achievable at moderate to high temperatures (500-800 °C) using simulated flue gas, at lab and pilot scale.

Naturally derived inexpensive calcium sorbent in the form of CaO or Ca(OH)₂ has been used extensively for the capture of CO2 and SO2. >90% CO₂ and complete SO₂ removal was achieved in studies conducted at OSU at the sub-pilot scale continuous reactor for the successful demonstration of the carbonation calcinations reaction (CCR) process.

In this study, these two reactive systems are combined to achieve single step CO₂, SO₂, and NO removal from gas mixtures at high temeperature (>500 °C). The effect of variables such as char particle size, use of activated carbon, extent of moisture in reactant gas, SO₂ concentration was quantified using a fluidized bed reactor. The fluidization behaviour of various mixtures of CaO sorbent and char was studied. The char selectivity for NO reduction was optimized. The results of these tests will be presented in the form of net NO, SO₂ and CO₂ capture. The merits and potential challenges of this novel process will also be discussed.