Process Vent

{
  "id": "MLC-T-ENV-022308",
  "term": "Process Vent",
  "field": "Environment",
  "definition": "1. Any open-ended pipe or stack that is vented to the atmosphere either directly, through a vacuum-producing system, or through a tank associated with hazardous waste distillation, fractionation, thin-film evaporation solvent extraction, or air or steam stripping operations.\n\n2. Point of discharge to the atmosphere (or point of entry into a control device, if any) of a gas stream from the acrylic and modacrylic fibers production process.\n\n3. Vent stream that is the result of the manifolding of each and all batch process vent, continuous process vent, or miscellaneous vent resulting from the affected facility into a closed vent system and into a common header that is routed to a control device. The process vent standards apply at the outlet of the control device. A process vent is either a PVC-only process vent or a PVC-combined process vent.\n\n4. Process vent or vent stream as they are defined in the referencing subpart.\n\n5. Open-ended pipe, stack, or duct through which a gas stream containing HAP is continuously or intermittently discharged to the atmosphere from any of the processes listed in § 63.680(c)(2)(i) through (c)(2)(vi) of this section. For the purpose of this subpart, a process vent is none of the following: a pressure-relief vent or other vent that is used as a safety device (as defined in this section); an open-ended line or other vent that is subject to the equipment leak control requirements under § 63.691 of this subpart; or a stack or other vent that is used to exhaust combustion products from a boiler, furnace, process heater, incinerator, or other combustion device.\n\n6. Gaseous emission stream from a unit operation that is discharged to the atmosphere either directly or after passing through one or more control, recovery, or recapture devices. Unit operations that may have process vents are condensers, distillation units, reactors, or other unit operations within the TPPU. Process vents exclude pressure releases, gaseous streams routed to a fuel gas system(s), and leaks from equipment regulated under § 63.1331. A gaseous emission stream is no longer considered to be a process vent after the stream has been controlled and monitored in accordance with the applicable provisions of this subpart.\n\n7. Vent from a process vessel or vents from multiple process vessels within a process that are manifolded together into a common header, through which a fluorinated GHG-containing gas stream is, or has the potential to be, released to the atmosphere (or the point of entry into a control device, if any). Examples of process vents include, but are not limited to, vents on condensers used for product recovery, bottoms receivers, surge control vessels, reactors, filters, centrifuges, and process tanks. Process vents do not include vents on storage tanks, wastewater emission sources, or pieces of equipment.\n\n8. Gas stream that: Is discharged through a conveyance to the atmosphere either directly or after passing through a control device; originates from a unit operation, including but not limited to reactors (including reformers, crackers, and furnaces, and separation equipment for products and recovered byproducts); and contains or has the potential to contain GHG that is generated in the process. Process vent does not include safety device discharges, equipment leaks, gas streams routed to a fuel gas system or to a flare, discharges from storage tanks.\n\n9. Gas stream that is continuously or periodically discharged during normal operation of a catalytic cracking unit, catalytic reforming unit, or sulfur recovery unit, including gas streams that are discharged directly to the atmosphere, gas streams that are routed to a control device prior to discharge to the atmosphere, or gas streams that are diverted through a product recovery device line prior to control or discharge to the atmosphere.\n\n10. Gaseous emission stream from a unit operation that is discharged to the atmosphere either directly or after passing through one or more control, recovery, or recapture devices. Unit operations that may have process vents are condensers, distillation units, reactors, or other unit operations within the EPPU. Process vents exclude pressure releases, gaseous streams routed to a fuel gas system(s), and leaks from equipment regulated under § 63.502. A gaseous emission stream is no longer considered to be a process vent after the stream has been controlled and monitored in accordance with the applicable provisions of this subpart.\n\n11. Point of emission from a unit operation. Typical process vents include condenser vents, vacuum pumps, steam ejectors, and atmospheric vents from reactors and other process vessels.\n\n12. Furnace vents, dryer vents, agglomeration furnace vents, vents from battery breakers, vents from buildings containing lead bearing material, and any ventilation system controlling lead emissions.\n\n13. Any open-ended pipe, stack, duct, or other opening intended to allow the passage of gases, vapors, or fumes to the atmosphere and this passage is caused by mechanical means (such as compressors, vacuum-producing systems or fans) or by process-related means (such as volatilization produced by heating). For the purposes of this subpart, a process vent is neither a pressure relief device (as defined in this section) nor a stack, duct or other opening used to exhaust combustion products from a boiler, furnace, heater, incinerator, or other combustion device.\n\n14. Point of discharge to the atmosphere (or the point of entry into a control device, if any) of a gas stream from a unit operation within a source category subject to this subpart. Process vent excludes the following gas stream discharges: (1) Relief valve discharges; (2) Leaks from equipment subject to this subpart; (3) Gas streams exiting a control device complying with this subpart; (4) Gas streams transferred to other processes (on-site or off-site) for reaction or other use in another process (i.e., for chemical value as a product, isolated intermediate, byproduct, or co-product for heat value); (5) Gas streams transferred for fuel value (i.e., net positive heating value), use, reuse, or sale for fuel value, use, or reuse. On or after November 19, 2021 this exclusion no longer applies to the Carbon Black Production source category; (6) Gas streams from storage vessels or transfer racks subject to this subpart; (7) Gas streams from waste management units subject to this subpart; (8) Gas streams from wastewater streams subject to this subpart; (9) Gas streams exiting process analyzers; and (10) Gas stream discharges that contain less than or equal to 0.005 weight-percent total organic HAP.\n\n15. Point of discharge to the atmosphere (or the point of entry into a control device, if any) of a gas stream if the gas stream has the characteristics specified in § 63.107(b) through (h), or meets the criteria specified in § 63.107(i). For purposes of §§ 63.113 through 63.118, all references to the characteristics of a process vent (e.g., flow rate, total HAP concentration, or TRE index value) shall mean the characteristics of the gas stream. [40 CFR 63.101 (CFR 2024)]",
  "subject": "Land, waste and cleanup",
  "references": [
    "RCRA Orientation Manual 2008 Glossary",
    "40 CFR 63.11398 (CFR 2013)",
    "40 CFR 63.12005 (CFR 2013)",
    "40 CFR 65.2 (CFR 2013)",
    "40 CFR 63.681 (CFR 2013)",
    "40 CFR 63.1312 (CFR 2013)",
    "40 CFR 98.128 (CFR 2013)",
    "40 CFR 98.6 (CFR 2013)",
    "40 CFR 63.1579 (CFR 2013)",
    "40 CFR 63.482 (CFR 2018)",
    "40 CFR 63.522 (CFR 2018)",
    "40 CFR 63.542 (CFR 2018)",
    "85 FR 41680; 40 CFR 63.7957 (CFR 2021)",
    "40 CFR 63.1101",
    "40 CFR 63.101 (CFR 2024)"
  ],
  "url": "https://mlchart.com/terminology/environment/process-vent/"
}