Ethylene MACT

MACT requirements for ethylene plants were promulgated July 12, 2002. For existing sources, compliance is required within 3 years after the date of publication in the Federal Register. The standards are part of the generic MACT and are found in 40 CFR 63 Subparts XX and YY, with requirements for some sources as referenced to Subparts SS, UU, and WW. Control requirements are summarized in the table below with more specifics following the table.

Summary of Ethylene MACT Requirements
Emission Cource	40 CFR 63 Subparts	Comment
Heat exchange systems	XX	Similar to HON, but may require testing with lower detection limit or monitoring of subset of exchangers to ensure detection of leaks >= 6.7 lb/hr.
Waste operations	XX	Requires compliance with NESHAP FF even for facilities with TAB < 10 Mg/yr. Also requires control for continuous butadiene streams with < 10 ppm benzene. For facilities with TAB >= 10 Mg/yr, allows use of FF compliance options.
Storage vessels	YY and WW	Requires use of IFR, EFR, or vent to control for tanks >= 25,096 gal and HAP vapor pressure >= 0.49 psia. Vent to control if HAP vapor pressure >= 11.1 psia.
Process vents	YY and SS	Reduce organic HAP emissions by 98 wt. % or to 20 ppmv for vents with flow rate >= 0.388 scfm and HAP concentration >= 50 ppm at existing sources and flow rate >= 0.28 scfm and HAP concentration >= 30 ppmv at new sources.
Transfer racks	YY	Reduce organic HAP emissions by 98 wt. % or to 20 ppmv, or route displaced vapors to process or fuel gas system or vapor balance. Load only to vessels that meet vapor-tightness requirements. Applies to racks with 30-day average throughput > 20,000 gallons per day and HAP VP >= 0.49 psia.
Equipment leaks	YY and UU	Monitor equipment (valves, pumps, connectors, agitators, pressure relief devices) that contain or contact >= 5 wt % HAP. Similar to HON fugitive requirements.

Ethylene MACT Heat Exchange Systems Requirements:

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Monitor cooling water for presence of substances that indicate a leak. If a leak is detected, repair within 45 days.

Monitor individual exchangers, entire heat exchange system, or any combination of exchangers as long as cooling water flow rate and method sensitivity would detect leak of 6.7 lb/hr. (Example: If test method has a sensitivity of 1 ppm for total HAP, the cooling water flow rate must be < 13,482 gpm.)

Frequency:

For existing sources, monitor monthly for 6 months, initially and after a leak repair. If no leaks are detected, monitor quarterly until a leak is detected.

Monitor for HAP (total or speciated), TOC, VOC, or surrogate parameters

• Systems with pressure on cooling water side at least 5 psia greater than pressure on process side
• Systems that cool process fluids containing < 5 wt% HAP
• Systems with intervening cooling fluid with < 5 wt% HAP
• Once-through system with NPDES permit meeting specified conditions

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Comply with the requirements of 40 CFR 61 Subpart FF with differences as noted below:

• Control requirements apply to all ethylene production sources that are located at a major source of HAPs, regardless of whether the total annual benzene (TAB) is less than 10 Mg/yr.
• Continuous butadiene waste streams must be controlled even though benzene concentration is less than 10 ppm.
• Sources with TAB < 10 Mg/yr cannot use the FF compliance options known as the 2 Mg option, the 1 Mg process wastewater option, or the 6 Mg option as specified in 61.342(c)(3)(ii), (d), and (e).
• Waste transferred offsite must comply with 63.1096 instead of 61.342(f). Offsite transferee must certify that waste streams are handled in accordance with requirements.

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Vessel Size Range (gallons)	HAP VP (psia)	Control Requirements
1056 - 25,096	0.49 - 11.1	Submerged fill pipe  or comply w/requirements for >= 25,096 gallons
>= 25,096	0.49 - 11.1	IFR (w/liquid mounted seal, mechanical shoe seal, or primary and secondary seals) or EFR (w/liquid mounted seal or mechanical shoe seal plus secondary seals) or Closed vent system to control device
	>= 11.1	Closed vent system to control device

Ethylene MACT Process Vent Requirements:

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Process vent definition:
gas stream with the following characteristics:

• Flow rate > 0.176 scfm
• HAP concentration > 20 ppmv
• Continuously discharged to atmosphere or to point of entry into control device
• Excludes streams routed to fuel gas system
• Excludes episodic or nonroutine releases

• Existing sources: Flow rate >= 0.388 scfm and HAP concentration >= 50 ppm_v
• New sources: Flow rate >= 0.28 scfm and HAP concentration >= 30 ppm_v

Reduce organic HAP emissions by 98 wt. % or to 20 ppm_v by venting through closed vent system to any combination of control devices and meet standards in Subpart SS for closed vent system (CVS) and control devices used

Closed vent systems: 63.983

• Flow indicator or car seal for bypass lines
• Monitor initially and annually (physical inspection for hard piping; Method 21 for ductwork)

• Meet 63.11(b)
• Conduct initial flare compliance assessment of visible emissions, net heating values, and exit velocity
• Monitor presence of flame

• Monitor temperature for incinerator
• Monitor temperature for boiler or process heater < 150 Btu/hr with vent stream not introduced with primary fuel
• Conduct performance test for incinerator or for boiler or process heater < 150 Btu/hr with vent stream not introduced with primary fuel

• Conduct performance test
• Continuously monitor outlet organic concentration or
    Absorber liquid temperature and specific gravity
    Condenser outlet temperature
    Carbon adsorber bed temperature and regeneration flow
  

• Conduct performance test
• Propose and follow appropriate monitoring requirements

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Applicability:

Throughput > 20,000 gallons per day averaged over consecutive 30-day period HAP VP >= 0.49 psia

Reduce organic HAP emissions by 98 wt. % or to 20 ppm_v by venting through closed vent system to any combination of control devices as specified in 63.1105
or
Route displaced vapors to process, fuel gas system, or vapor balance

Load only into vessels that meet vapor-tightness requirements

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Applicability:

Equipment that contains or contacts >= 5 weight % organic HAP

Control requirements:

Comply with Subpart UU
• Valves: monitor monthly, quarterly, or less depending on % leaking. Leak definition 500 ppm
• Pumps: monitor monthly, visual inspection weekly. Leak definition 5,000 ppm for polymerizing monomers; 1,000 ppm for others. Quality Improvement Program if > 10% or 3 pumps leak
• Connectors: monitor annually, biennially, or less frequently depending on % leaking. Leak definition 500 ppm
• Agitators: monitor monthly, visual weekly. Leak definition 10,000 ppm
• Pressure relief devices: monitor within 5 days after release. Leak definition 500 ppm
• Compressors: equip with seal system and barrier fluid or route to control
• Sampling connection system: use closed-purge, closed-loop, or closed vent system

(Prepared July, 2002)