What are the subcategories of boilers and process heaters?

The subcategories of boilers and process heaters, as defined in § 63.7575 are: (a) Pulverized coal/solid fossil fuel units. (b) Stokers designed to burn coal/solid fossil fuel. (c) Fluidized bed units designed to burn coal/solid fossil fuel. (d) Stokers/sloped grate/other units designed to burn kiln dried biomass/bio-based solid. (e) Fluidized bed units designed to burn biomass/bio-based solid. (f) Suspension burners designed to burn biomass/bio-based solid. (g) Fuel cells designed to burn biomass/bio-based solid. (h) Hybrid suspension/grate burners designed to burn wet biomass/bio-based solid. (i) Stokers/sloped grate/other units designed to burn wet biomass/bio-based solid. (j) Dutch ovens/pile burners designed to burn biomass/bio-based solid. (k) Units designed to burn liquid fuel that are non-continental units. (l) Units designed to burn gas 1 fuels. (m) Units designed to burn gas 2 (other) gases. (n) Metal process furnaces. (o) Limited-use boilers and process heaters. (p) Units designed to burn solid fuel. (q) Units designed to burn liquid fuel. (r) Units designed to burn coal/solid fossil fuel. (s) Fluidized bed units with an integrated fluidized bed heat exchanger designed to burn coal/solid fossil fuel. (t) Units designed to burn heavy liquid fuel. (u) Units designed to burn light liquid fuel. [76 FR 15664, Mar. 21, 2011, as amended at 78 FR 7163, Jan. 31, 2013]