Trihydro provides environmental, engineering, energy, transportation, and water resources services to public and private clients. From its initial start-up as a two-man firm in 1984, Trihydro has grown into a successful, dynamic firm of over 270 employees with 13 offices nationwide.

 

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March 2009

Are you a Major Refinery Source? Get ready to begin monitoring cooling tower water.

Amendments to Refinery MACT 1 are due to be published in the near future. The amendments focus on monitoring Heat Exchanger systems. Provided below is an outline of the requirements for monitoring these systems.

History
Under section 112(d)(6) of the Clean Air Act (CAA), the Environmental Protection Agency (EPA) is required to review identified maximum achievable control technology standards and to revise them “as necessary (taking into account developments in practices, processes, and control technologies)” at least every eight years. In response, EPA published a proposed rule containing amendments to the national emission standards for petroleum refineries in the Federal Register on September 4, 2007 for public comment. The proposed rule is entitled National Emission Standards for Hazardous Air Pollutants From Petroleum Refineries; Proposed Rule (72 FR 50716). The proposed rule outlines new compliance requirements for cooling towers under CAA sections 112(d)(2) and (f)(2). Due to public comment on the proposed rule, the EPA revised and supplemented the cooling tower requirements in National Emission Standards for Hazardous Air Pollutants From Petroleum Refineries; Proposed Rule (73 FR 66694) in the Federal Register on November 10, 2008. A summary of the cooling tower requirements outlined in the revised and supplemented proposed rule are described herein.*

General Requirements
The revised and supplemented proposed rule requires owners and operators of new and existing cooling towers (sources) to conduct monthly monitoring for leaks of total strippable volatile organic compounds (VOCs) from heat exchangers that are in “organic hazardous air pollutant (HAP) service (i.e., lines that contain or contact fluids with five weight percent or greater of total organic HAP listed in Table 1 of 40 CFR Part 63).” Heat exchangers in organic HAP service are exempt under the revised proposed rule if the pressure on the cooling water side of the exchanger is at least 35 kilopascals greater than that of the process fluid side or if an intervening cooling fluid containing less than five weight percent HAPs is used as an intermediary between the process fluid and cooling water.

The revised and supplemented proposed rule defines an existing source as a heat exchange system that was constructed or reconstructed on or prior to September 4, 2007. New sources are defined as being constructed or reconstructed after September 4, 2007. The revised proposed rule requires existing sources to be monitored monthly within 18 months following the promulgation of the rule, and monthly monitoring of new sources will be required upon start-up or on the date of promulgation of the amended proposed rule depending on which should occur later.

Leaks
Leaks are defined for existing and new sources as quantities of total strippable VOCs in the stripping gas. The quantity of total strippable VOCs in the stripping gas is obtained using the Modified El Paso Method (described in detail below). The total strippable VOC concentrations are quantified as methane. The leak definitions for existing and new sources are 6.2 and 3.1 parts per million by volume (ppmv), respectively. Once a leak is detected it must be repaired within 45 days of the sampling date unless such conditions exist that allow for a delay of repair.

The owner or operator must determine whether a delay of repair is necessary as soon as possible, but no later than 45 days after the leak is detected. During the delay of repair monthly monitoring must be continued. If a concentration of total strippable VOCs (as methane) exceeds 62 ppmv during the subsequent monitoring, the leak must be repaired within 30 days. For leaks with total strippable VOC (as methane) concentrations less than 62 ppmv, the following conditions allow for a delay of repair:

Within three years after the promulgation of the proposed rule, a delay of repair may be allowed if an identified leak has a total strippable VOC (as methane) concentration greater than 62 ppmv. However, after the three-year period, a leak greater than 62 ppmv must be repaired within 45 days of the date the leak is identified. The conditions under which a delay of repair is allowed in the first three years are as follows:
  • The repair requires the shutdown of the serviced unit (repair may be delayed until next planned shutdown if within 60 days of the determination that a delay is necessary).
  • Critical parts or personnel are not available (repair may be delayed up to 120 days after determination that a delay is necessary).
  • The repair is infeasible without shutting down the serviced unit and the shutdown will cause more emissions than the delay of repair.
Sampling
The revised proposed rule allows samples for the monitoring requirements to be collected at either the cooling water effluent of the heat exchanger or from the combined stream influent to the water cooling tower. If a leak is detected at the combined stream influent to the water cooling tower, the owner or operator may either elect to “fix the leak regardless of its location or begin monitoring at each heat exchanger in organic HAP service.”

Recordkeeping and Reporting Requirements
Owners and operators are required under the revised and supplemented proposed rule to maintain records identifying all heat exchangers at the facility, the average annual HAP concentration of the process fluid, and the range of HAP concentrations of the process fluid. Also, owners and operators are required to identify all heat exchange systems that are in organic HAP (five weight percent or greater of organic HAPs) service. For each system, the following must be identified:
  • All heat exchangers within the system
  • Heat exchangers in organic HAP service
  • The cooling tower for each system
The dates of leak identification and repair must also be maintained. If a repair is delayed, records of the reason for the delay, the schedule for completion of repair, and the estimated emissions during the delay of repair must be maintained.

The results from each monthly monitoring event must be maintained and must include the following information:
  • Date and time of event
  • El Paso air stripper air and water flow rates (mL/min) and air temperature (oC)
  • Heat exchange exit line flow or cooling tower return line flow (gal/min)
  • FID response to certified gasses (zero, mid-level, and high-level)
  • Barometric pressure
  • Flame Ionization Detector (FID) reading (ppmv)
  • Certified gas methane concentration for zero, mid-level, and high-level air as defined by the Modified El Paso Method
Reporting requirements for monthly cooling tower monitoring consists of periodic reports that must include the following information:
  • Number of heat exchange systems in HAP service
  • Summary of monitoring data that indicated a leak including the number of leaks
  • Summary of reason for delay of repair of any leak and the date of repair
  • Number of heat exchange systems in organic HAP service found to be leaking
  • Dates of leak identification, leak source identification, and repair
  • Estimate of VOC (as methane) emissions for delay of repair
Modified El Paso Method
The revised proposed rule requires an owner or operator to use the Modified El Paso Method to collect and analyze samples to detect leaks. The Modified El Paso Method is described in Appendix P of the Texas Commission on Environmental Quality’s (TCEQ) Sampling Procedures Manual (January 2003). This method requires the use of a sampling train that consists of a small-scale VOC stripper with continuous inlet flow rates of cooling water and stripping air. The effluent air from the stripper contains the strippable VOCs and is routed to a water knock-out container followed by a Flame Ionization Detector (FID). The FID measures the total strippable VOC (as methane) concentration in the stripping gas. This method also specifies requirements for collecting samples, calibration of equipment, and decontamination procedures.

Trihydro Services
Trihydro is available to assist you with your required monthly cooling tower monitoring. Trihydro has designed and operated the El Paso sampling train since 2003. Trihydro personnel are available to perform the monthly sampling.

We have identified and speciated the HAP content of exchangers subject to the Hazardous Organic NESHAP (HON) listed in 40CFR Part 63. Trihydro is available to assist you with the identification and characterization of heat exchangers in organic HAP service. We have developed sampling plans and best practices for the identification and repair of leaking exchangers subject to the HON rule. Thus, we have the expertise to assist you with developing sampling plans to identify leaking exchangers for Residual Risk.

*Compliance dates are dependent on the publication of the Federal Registry


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March 2009

How will the stimulus package affect you?

President Barack Obama’s stimulus package, the American Recovery and Reinvestment Act, is designed to immediately save jobs or create new ones while laying the groundwork for long-term economic growth. The White House is estimating that, over the next 2 years, approximately 3.5 million jobs, many in infrastructure and renewable energy projects will be created or saved through the stimulus package. Click here to read more...