40 CFR § 63.7499 - What are the subcategories of boilers and process heaters?

---
identifier: "/us/cfr/t40/s63.7499"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 63.7499 - What are the subcategories of boilers and process heaters?"
title_number: 40
title_name: "Protection of Environment"
section_number: "63.7499"
section_name: "What are the subcategories of boilers and process heaters?"
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "C"
subchapter_name: "AIR PROGRAMS"
part_number: "63"
part_name: "NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 7401"
regulatory_source: "57 FR 61992, Dec. 29, 1992, unless otherwise noted."
cfr_part: "63"
---


# 63.7499 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]