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The Maximum Achievable Control Technology (MACT) standards for the oil and natural gas industry are expected to be proposed in early 1997, with promulgation later in the year. These standards will include "control device monitoring" requirements to show that controlled sources are in "continuous compliance" with the MACT standard. Since condensers are the most widely used control option for glycol dehydrators, the monitoring requirements for condensers are of particular interest; this requirement may include recording the condenser outlet temperature. Performance testing on all condenser units may be required to establish the appropriate site-specific temperature that indicates whether a unit is achieving the desired level of control. Computer modeling is a less expensive and more flexible alternative for establishing this temperature and defining a site-specific condenser curve, but this approach has not previously been validated through field measurements. Gas Research Institute (GRI) has initiated a field condenser test program to collect the data necessary to validate the use of computer programs, such as GRI-GLYCalcTM and commonly available process simulation packages, in predicting glycol dehydrator vent condenser efficiency. A series of nine test, at seven sites have been conducted to collect these data. This paper will present the results of the field testing (performed on several different condenser types, including air-, glycol-, and water-cooled systems), and make comparisons to the modeling results. The paper will also include general information on the key process parameters affecting condenser performance. Introduction Regulatory Overview. Title III of the Clean Air Act Amendments (CAAA) of 1990 requires the United States Environmental Protection Agency (EPA) to adopt Maximum Achievable Control Technology (MACT) standards to limit hazardous air pollutant (HAP) emissions from 250 source categories. These MACT standards must include control limits as well as control device monitoring approaches to ensure that the emission source is in continuous compliance with the standard. One of the 250 source categories to be regulated is the oil and natural gas industry. This standard is currently scheduled for proposal in early 1997, with promulgation later in the year. In its initial preparation of information on the oil and natural gas MACT standard, EPA identified glycol dehydrators as a significant HAP emission source and has suggested that 95% HAP reductions will be required through the use of combustion, condensation, or other processes. [Previous studies have shown that about 80% of the installed control devices are condensers because of the advantages of recovering valuable hydrocarbon products (1).] In previous MACT standards, EPA has required relatively straightforward control device monitoring requirements, such as recording of key control device operating parameters. Depending on the type of control system, this has included parameters such as scrubber pH, liquid influent flows, gas effluent flows, or firebox temperature. For glycol dehydrators, the requirements will likely consist of periodic recording of key operating parameters such as firebox temperature for combustion devices or outlet temperature for condensers. P. 7^

Increasing regulatory pressure has made emissions of benzene, toluene, ethylbenzene, and xylenes (collectively known as BTEX) and total volatile organic compounds (VOC) from glycol dehydration units a major concern for the natural gas industry since there are over 40,000 of these units in operation. The Clean Air Act Amendments (CAAA) of 1990 have been the impetus for air toxics regulations, and the Maximum Achievable Control Technology (MACT) standards for the oil and gas industry will be proposed in June, 1995, and will include glycol dehydrators. In addition, several states are regulating or considering regulation of these units. The most common control systems that have been applied to glycol dehydrators are combustion or condensation systems. Combustion systems suffer from high operating costs since they do not recover the hydrocarbon for sale and require supplemental fuel. Many of the condensation systems may not achieve sufficiently low condenser temperatures to meet regulatory control limits. The R-BTEXTM process addresses this shortcoming by recovering the steam from the glycol dehydrator and converting it to cooling water; this allows R-BTEX to achieve the lowest condenser temperature possible without refrigeration. The Gas Research Institute (GM) is conducting a field test program to demonstrate the process under a variety of conditions. Under this program, testing has been completed at one site in south Texas and at another site in western Colorado. Startup of a third unit at a Gulf Coast site in Texas should occur in late 1994. This paper presents the testing results for the first two sites and includes a side-by-side comparison of the R-BTEX process with other available control technologies. P. 511