While not specifically addressed under Quad-O, glycol dehydrator emission standards have been tightened under amendments to CFR National Emission Standards for Hazardous Air Pollutants (NESHAP) from oil and natural gas production facilities (Subpart HH) and from natural gas transmission and storage facilities (Subpart HHH).
Small glycol dehydrators are defined as processing less than 85,000 m3 per day on average annually and must meet a specific limit of BTEX (benzene, toluene, ethylbenzene and xylene) emissions based on the unit's throughput and gas composition.
Triethylene glycol weighs ~9.36 pounds per gallon and is usually acidic when it leaves the glycol dehydrator
. All glycols (EG, DEG, TEG, TTEG), in the presence of H2S, COS, CS2, RHS, CO2, O2, and water, in the gas stream, naturally become acidic.
Glycol dehydrators have been the most prevalent equipment to remove water from natural gas streams.
[USPRwire, Fri Jul 26 2019] Glycol dehydrators have been the most prevalent equipment to remove water from natural gas streams.
Summary: Glycol dehydrators
have been the most prevalent equipment to remove water from natural gas streams.
This subcategory consists of glycol dehydrators
with an actual annual average natural gas flow rate of less than 283,000 standard cubic meters per day (scmd) or actual average benzene emissions less than 0.9 Mg/yr.
Recommendation: To ensure that Interior has a complete picture of venting and flaring on federal leases and takes steps to reduce this lost gas where economic to do so, and to help reduce venting and flaring of gas by addressing limitations in their regulations, the Secretary of the Interior should direct BLM and BOEMRE to revise its guidance to operators to make it clear that technologies should be used where they can economically capture sources of vented and flared gas, including gas from liquid unloading, well completions, pneumatic valves, and glycol dehydrators
. BOEMRE should consider extending its requirement that gas be captured where economical to "lease-use" sources of gas.
The proposed changes would remove the 1 ton per year benzene compliance alternative for large glycol dehydrators
and establish emission limits for small glycol dehydrators
at major sources.