Flares for Cost Effective VOC Control for Oil and Gas Production

Date PublishedJune 19, 2013
CompanyZeeco Inc.
Article AuthorScott D. Reed
Article TypeJanuary 2013 Issue
Tags, , , ,
PULSE Interactive

Flares for Cost Effective VOC Control for Oil and Gas Production

On April 17, 2012, the United States Environmental Protection Agency (EPA), as part of the Clean Air Act (CAA) requirement, released the first federal air standards for oil and gas production, transmission, and storage facilities. The National Emissions Standards for Hazardous Air Pollutants (NESHAP) 40 CFR 63 subpart HH/HHH has been revised, affecting existing and new/modified facilities. In addition, the newly developed New Source Performance Standards (NSPS) 40 CFR 60 Subpart OOOO (Quad O), applies to new and modified affected facilities; significant staff increases are anticipated as a result of these broad reaching emission reduction rulings.

The goal of these new regulations is a 95% Volatile Organic Compound (VOC) reduction. VOCs in the presence of sunlight lead to the development of grade-level ozone (smog). According the U.S. EPA, approximately 40% of all US VOC emissions are from the oil and gas production and processing segments. While utilization of a flare as the control device produces CO2 as a product of combustion, carbon dioxide has a much lower (20X factor) environmental impact than current methane venting.

Zeeco Inc.With new, updated regulations in place for US oil and gas production and processing facilities, there is potential for the regulations to spill over into neighboring sites. Some operating companies already have new standards in place based on the EPA guidelines even though the site they are operating on may not be under the EPA mandate. As of October 15, 2012, NSPS Quad O requires gases that would otherwise be vented during periods of flowback be routed to a Completion Control Device (CCD) instead. The

CCD must achieve a minimum of 95% VOC reduction. A properly designed Engineered Flare will achieve greater than 98% VOC reduction.

Storage tanks are subject to both the revised NESHAP and the new NSPS standards and affected sites must achieve a 95% VOC reduction. Affected sources include sites with VOC emission rates of 6 TPY or greater. A properly designed Engineered Flare System will achieve greater than a 98% VOC reduction, meeting compliance targets. There are three typical options for storage tank VOC control: 1) Enclosed Combustion Device, 2) Vapor recovery Unit, and 3) Engineered Flare System. The open flare system is the lowest cost option, and when properly designed and operated per 40 CFR 60.18 with no visible emissions (per American Petroleum Institute (API) Method 22), there is no performance test required, saving additional cost for compliance. A properly designed Engineered Flare can also be designed to combine the low pressure tank vents and the high pressure separator vents into one system (Dual Flare) to save capital cost.

In urban locations, enclosed flares (sometimes incorrectly called “incinerators” or “combustors”) are sometimes preferred as a “good neighbour” investment. Enclosed flares can be designed for multiple streams within the same unit to save on overall capital costs.

In addition to the NESHAP and NSPS for the oil and gas production sites, new flare assist media regulations are forthcoming, targeting steam and air assist flares. Other affected equipment includes glycol dehydration vents, wet seal compressor vents, and compressor station storage tanks. The new EPA regulations will target Combustion Zone Net Heating Value (CZNHV), to reduce “over steaming” or “over airing” flares. The amount of steam/air (via low pressure air blower) will have to be controlled in relationship to the amount of hydrocarbon being sent to the flare.

When evaluating an Engineered Flare, seek a robust design that includes temperature-resistant construction for heat-affected components to ensure long-term life expectancy of the flare tip and pilot. Utilization of investment castings for the critical components in the heat-affected zones minimizes the potential for field failure. Requiring a continuous, monitored pilot that meets the API 537 performance design criteria (150 mph wind and 10” rain/hr) means less operations and maintenance nuisance issues in the field and ensures environmental performance for VOC reduction.