VOC in Cooling Tower Water

Leaks of volatile hydrocarbons from heat exchangers may emit large amounts of VOC which can cause emissions into the atmosphere or may create a hazard. Cooling Tower Monitoring gives an early warning of possible corrosion leaks. Savings in lost product can be substantial. On November 10, 2008 EPA proposed new cooling tower requirements for petroleum refineries (pdf).

EPA Requires TCEQ Approved Modified El Paso Method for Cooling Towers

In the early 70's, the El Paso Products Company devised a cost effective method to sample for VOC's in the cooling water. This method utilized a dynamic or flow-through system for air stripping a sample of the water and analyzing the resultant off-gases for VOC's using a common flame ionization detector (FID) analyzer, and has been required in permits in Texas for many years.

The El Paso Products method, however, has been overshadowed nationally by the use of purge and trap analysis of water samples utilizing gas chromatography and/or mass spectrometry techniques. While direct water analysis has been shown to be effective for cooling tower measurements of heavier molecular weight organic compounds with relatively high boiling points, Texas Commission on Environmental Quality (TCEQ) has determined that this approach may be ineffective for capture and measurement of volatile organic compounds with lower boiling points, such as ethylene, propylene, 1,3-butadiene, and butenes. VOC's with a low molecular weight and boiling point are generally lost in the sample collection step of purge/trap type analysis. Consequently, TCEQ requires that the air stripping method presented in Appendix P of the TCEQ Sampling Procedures manual be used for cooling tower and other applicable water matrix emission measurements of VOC's with boiling points below 140 F.

This test method had been review and accepted by the Texas Environmental Department currently known as Texas Commission on Environmental Quality (TCEQ). This method was accepted for analyzing samples for any VOC's that may come in contact with the cooling water. As of January of 2003, the TCEQ has adopted a new modified El Paso method. This method has taken an EPA methodical approach to testing. In this modified method certain criteria have to be met before this method can be utilized and a QA/QC procedure has been added which was not provided in the previous El Paso method.

ETEC Industries has the experience and the equipment to perform the necessary QA/QC on the cooling tower water apparatus and the knowledge to perform cooling tower water testing with the procedure incorporated in the TCEQ sampling procedures manual. ETEC offers this testing service through two options; continuous monitoring and monthly monitoring, each of the monitoring program options will be customized to fit each industrial client's compliance needs. The compliance monitoring program will provide a turnkey solution from testing to reporting of calculated mass emissions from each cooling tower. ETEC will also provide technical support in the event a leak is detected and if data dictates that samples be speciated periodically, ETEC Industries will provide a 3rd party laboratory or provide samples to the facilities in-house laboratory.