Tech Talk: East Texas Combustion Rule Brings Changes for Small Engines

Tech Talk: East Texas Combustion Rule Brings Changes for Small Engines

Tech Talk: By Doug Bartley, Certified Environmental Specialist (CES), B.enviroSAFE

East Texas gas producers, midstream operators and plant operators will soon undertake huge changes (March 1, 2010, deadline) to comply with the Texas Commission on Environmental Quality’s (TCEQ) “East Texas Combustion Rule,” as it applies to 33 counties extending east and southeast of the Dallas-Fort Worth Metroplex. The rule is spelled out in the TCEQ’s Title 30 TAC Chapter 117: ControI of Air Pollutions from Nitrogen Compounds, Subchapter E: Multi-Region Combustion Control, East Texas Combustion. The complete text of the rule is available online at www.tceq.state.tx.us.

In short, engines that were previously exempt from emission limitations (less than 500 Bhp, or brake horsepower) will now be called into regulation with stringent nitrogen oxide (NOx) emission limits, 0.5 grams per horsepower-hour (g/hp-hr) for 500+ Bhp engines and 1 g/hp-hr for 240 to 499 Bhp engines. This will apply to richburn engines only, at this time. However, don’t get comfortable because the new Environmental Protection Agency-proposed rule 40 CFR 60, Subpart “ZZZZ” is on its way and will include practically all engines, if approved as proposed.

Operators are scrambling to purchase catalytic convertors and air-to-fuel ratio controllers (AFRC) to retrofit these small engines to comply with the emission limits. Not only will this require an initial outlay of capital funds to purchase equipment, but it will also require ongoing maintenance costs associated with quarterly emission testing, record keeping, catalyst cleaning, etc. The 500+ Bhp engines, if permitted with a “permit by rule” permit, already must meet 2 g/hp-hr of NOx but will now have to reduce that to 0.5 g/hp-hr, which means operators will be buying additional catalyst(s) for their existing convertors or replacing the existing convertor housing with a larger one.

The initial compliance emission test must be conducted using EPA-approved test methods and EPA protocol calibration gases. The test report must include very specific information relative to the site and operating conditions, including raw data logs, schematics, description of sampling train, calibration worksheets, calculations, brief resume/qualifications of test personnel, etc. This test must be repeated every two years (biennially) or 15,000 engine run hours, whichever occurs first.

Proper operation of the engine must be documented by recorded measurements of NOx and carbon monoxide (CO) emissions at least quarterly and as soon as practical within two weeks after each occurrence of engine maintenance that may reasonably be expected to increase emissions such as oxygen sensor replacement, or catalyst cleaning or catalyst replacement. Stain tube indicators specifically designed to measure NOx concentrations may be acceptable for this documentation, provided a hot air probe or equivalent device is used to prevent error due to high stack temperature, and three sets of concentration measurements are made and averaged. Portable NOx analyzers are also acceptable for this documentation. Quarterly emission testing is not required for those engines whose monthly run time does not exceed 10 hours. This exemption does not diminish the requirement to test emissions after the installation of controls, major repair work, and any time the owner or operator believes emissions may have changed.

Engines that are exempt from emission reduction and testing, those less than 240 Bhp and emergency use engines, aren’t exempt from the record keeping requirements. In fact, written records must be maintained by the operator to document the purpose of the engine operation, and if operation was for an emergency situation, identify the type of emergency situation and the start and end times and date(s) of the emergency situation. For engines subject to testing, operators must keep records of emission testing results, maintenance on all emission control equipment such as cleaning or replacing catalyst, oxygen sensor replacement, air/fuel ratio controller set points, spark plug replacement and preventative maintenance performed.

A 15-day advance notice is required for all initial testing. This notice must be sent to the regional office of the TCEQ with jurisdiction over the facility and any local air pollution control agency.

All records must be maintained for at least five years and made available upon request to representatives of the TCEQ, the EPA, or any local air pollution control agency having jurisdiction.

This division (relating to East Texas Combustion) applies to stationary, gas-fired reciprocating internal combustion engines at any stationary source of nitrogen oxides in the following affected counties, according to the TCEQ: Anderson, Brazos, Burleson, Camp, Cass, Cherokee, Franklin, Freestone, Gregg, Grimes, Harrison, Henderson, Hill, Hopkins, Hunt, Lee, Leon, Limestone, Madison, Marion, Morris, Nacogdoches, Navarro, Panola, Rains, Robertson, Rusk, Shelby, Smith, Titus, Upshur, Van Zandt, and Wood Counties.

Doug Bartley is a certified environmental specialist and is president of B.enviroSAFE Environmental and Safety Consultants, which has provided emission testing since 1995 and keeps extensive records of all testing. He may be contacted at 817-439-4767 or doug@benvirosafe.com.