The Technology

The Clean Combustion System^TM (CCS) concept is that of a entrained-flow coal gasifier followed by stages of combustion air. The CCS Burner is uniquely designed to provide the necessary time, temperature and stoichiometry required for all the chemicals in coal to complete their combustion reactions (to reach equilibrium conditions).

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The coal, with limestone added as source of calcium for sulfur capture, is pulverized and introduced to the burner along with a limited amount of hot combustion air. The initial high temperature combustion gasifies and/or releases all the constituents of coal into the gas; i.e. carbon, sulfur, nitrogen and ash compounds. At these high temperatures and with limited available oxygen, the carbon aggressively commands oxygen to form carbon monoxide (CO) from all sources, including such compounds as water (H₂O). Nitrogen compounds that may form, such as NO_x, HCN's and NH₄, are simply forced to the molecular form (N₂) by the aggressive action of carbon for oxygen. In the presence of calcium, the sulfur reacts to form calcium sulfide (CaS, a solid 'non-gaseous' particle). The hydrogen can't compete with the other elements and remains H₂.

The high combustion temperatures melt together the coal ash (largely silica and alumna) and calcium sulfide solids to form an inert slag that drains from the bottom of the boiler. The very hot gases, high in CO and H₂, and nearly free of NO_x and sulfur, then exit into the boiler furnace. As the gases cool and generate steam, additional "over-fire" air is added in stages to the furnace to complete the combustion of CO to CO₂ and H₂ to water. These steps prevent formation of any new (thermal) NO_x and completes the combustion with excess air. The clean hot gases then enter the boiler superheat section as was before the retrofit.

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