A final field evaluation test involving paired midget impinger train sampling concurrent with HCl monitoring at a MWC was used to determine the precision of the HC1 sampling and analysis protocol and the bias and precision of two HCl CEMS's

The U. S. EPA is currently regulating emissions of HCl from hazardous waste incinerators under 40 CFH 264.343 to 4 lbs/hr or an HCl removal efficiency of at least 993. The EPA is also currently considering regulating HCl emissions from MWC’s. Several state and local agencies have already set HCl emission limits for new MWC's and are requiring installation of HCl EMS’s at certain facilities. Laboratory and field studies were performed to develop and evaluate a sampling and analytical technique for measuring HCl from stationary sources. Studies were conducted in three phases: (1) literature search and development of a candidate sampling and analysis protocol. (2) laboratory evaluation and refinement of the protocol, and (3) field evaluation. Based on previous studies, a modified Method 6 sampling train with acidified water absorbing solution was selected for collection of HCl. An acidified water solution (0.1 N HzSO,) was selected to minimize the potential for Cl, to interfere with the HCl determination. Impingers containing an alkaline solution (0.1 N NaOH) and silica gel were added to the train to collect Cl, and moisture, respectively, and thus protect the pump and allow determination of percent moisture in the sample gas. Ion chromatography was selected as the most suitable technique for the analysis of HCl. In a laboratory evaluation, the candidate sampling train was challenged with various combinations of high concentration HCl and Cl, cylinder gases to assess the ability of the absorbing solutions to collect and speciate each gas with or without the presence of the other and to examine the effect of flow rate on the adsorption of Cl, in the acidic impinger solution. The first acidic impinger showed an HCl collection efficiency of better than 100 percent for all test conditions. Cl, separation in the train was 92 percent efficient at a sampling rate of 0.5 lpm and 97 percent efficient at a rate of 2 lpm. The presence of 197 ppm Cl, in a 221 ppm HCl gas stream sampled at 2 lpm resulted in an average positive bias in the HCl measurement of 3.4 percent. A preliminary field evaluation of the protocol was conducted to identify potential sampling problems and analytical interferents and to assess the use of stainless steel versus glass probe tips. The results of the test indicated that both glass and stainless steel probe tips were acceptable for HCl sampling and that a knockout impinger is necessary for use at high moisture (e.g., combustion) sources. An eight-run, six-variable (low reagent volume, increased impinger pH, longer sampling time, elevated impinger temperature, higher sampling rate. elevated Cl, levels, plus a control blank) ruggedness test was used to assess