United States Environmental Protection Agency Environmental Sciences Research Laboratory Research Triangle Park NC 27711 Research and Development EPA-600/S3-83-102 Dec. 1983 &ER& Project Summary Formation of a Detached Plume from a Cement Plant James L Cheney, William D. Conner, Roy L Bennett, Donald L Duke, Carole L Walters, and Kenneth T. Knapp A coordinated study of process, source emissions, and plume sampling was conducted at a coal-fired cement pro- duction plant. Both source and plume sampling consisted of particle and gas measurement and characterization. Par- ticulate sampling of both the source and plume addressed particle size, amount, and composition. Particles were ana- lyzed by scanning electron microscopy, x-ray fluorescence spectroscopy, and chemical means. Gas sampling of both the source and plume involved conven- tional source sampling methods as well as procedures adapted to this specific measurement program. Plume opacity was measured by visual observation and a LIDAR system. Comparison of the results from the plume and source measurement indi- cated the formation of the plume was the result of the reaction of ammonia and hydrochloric acid. The formation of ammonium chloride occurred within the same set of reaction parameters as independent laboratory studies'had previously indicated. The results of electron microscopy analysis for one of the plume samples indicated an NH4CI particle size of < 0.4 fjm. When an estimation of the amount of these sized particles was compared to source particle sizing measurements, a 50 to 100% increase in such inhalable particulates was occurring within the plume, at less than 18 stack diameters from the exit. This Project Summary was developed by EPA's Environmental Sciences Re- search Laboratory, Research Triangle Park, NC, to announce key findings of the research project that is fully docu- mented in a separate report of the same title (see Project Report ordering infor- mation at back). Introduction This report discusses an in-depth study of a coal-fired cement production plant to determine the nature of the formation of a visible plume from the gases emitted from the stack. The plant has the capa- bility of operating on either a regular mode or a bypass mode. The visible plume formed each time the plant operated in the bypass mode. During the regular mode, the off gases from the coal-fired kiln passed through the raw product grinding mill and a recovery electrostatic precipitator (ESP) prior to their exit to the atmosphere. Duri ng the bypass mode, the kiln gases were rerouted around the mill and through a cooling tower, after which they were passed through the ESP and vented to the atmosphere. During both operating modes, source measurements indicated that the plant was well within compliance for both opacity and panicu- late grain loading. A 1-week (5-day) sampling program was conducted at the Lehigh plant at Leeds, Alabama, in May 1981. The sampl- ing addressed both source emissions of gases and particles and plume sampling. Source emissions were sampled by con- ventional extractive methods to determine the concentrations of S02, NH3, HCI, and NOx as well as particulate mass emission rates, particle size, and particle composi- tion. Gaseous HCI, NH3, S02, CO and C02 were also measured with an optical cross-stack procedure. The plume sampl- ing was performed with tethered balloons and various filters. The filters, which were connected to a pump box on the ground, were analyzed for such gases as ------- HCI, NH3, S02, and the particles were analyzed for SO4=, S03=, CI", NH3, by x- ray fluorescence spectroscopy, and scan- ning electron microscopy. Opacity meas- urements for the plume at and near the location of the balloon sampling location were performed with both a LIDAR system and by visual observation. Results Inclement weather and plant operating problems severely limited the time during which sampling of the bypass mode plume could be performed. However, adequate data were established to con- clude how the particles were formed in the plume. These data included: 1) In-stack measurements indicated that particulate NH4+ and CI* emis- sions of 0.68 (expressed as NH3) and 7.21 (expressed as HCI) Ib/hr were emitted and that ~ 85 percent of the NH3and ~ 50 percent of the HCI were emitted as gases. A second improved HCI reference method indicated — 80 percent of the HCI was emitted as gas phase. 2) The mass emission rate of particu- lates from the stack was 7.7 and 15.4 Ib/hr from two samples acquired. X- ray fluorescence analyses of the particles indicated their main com- ponents as Ca, Si, K, Fe, S, and Al. A Pilat impactor sample indicated that 56 percent of the total particulate catch was on the backup filter where the particles were less than 0.4 /urn in size. 3) Gas and particle composition of the plume were determined with a three- stage filter designed to collect parti- cles and gaseous HCI, NH3 and SC<2. The second filters following the front prefilter were chemically impreg- nated to absorb gaseous components passing through the particulate filter. Analyses of all three filters indicated a total catch of 1.86,1.13, and 12.5/u moles of HCI, NH3, and S02, respec- tively. The first of the three filters was assumed to collect particles only. The first filter collected 1.25, 0.75, and 0.08 fj moles of HCI, NH3, and S0<~, respectively. This indicated that ~ 40% of the HCI and NH3 had reacted to form particles but that very little (~ 7 percent) of the S02 had been converted_or was contained as particulate S04=. 4) Scanning electron microscopy of two plume samples acquired during the high opacity situation indicated a particle size range of 0.2 to 0.6 yum for both samples. In one of the samples a predominant number of particles contained CI* and were volatile in the electron beam. It was assumed that NH4CI was the basic particle component. The second sample contained a large number of particles with K and S. There were no significant particles containing CI" in this sample. These particles were assumed to contain I^SCu. 5) Opacity measurements by the LIDAR system and by visual observation agreed well and ranged from less than 5 percent near the stack exit to as high as 41 percent within 50 m of the exit. Conclusions The change from an invisible plume just above the stack to a highly opaque plume ~ 50 m from the stack indicates some kind of particle formation. The change in composition between in- stack and plume samples showed a conversion of gaseous NH3 and gaseous HCI to particulate matter containing NH4+ and CI". That this particulate matter was indeed NH4CI was supported by electron microscopy. There was also some evi- dence of S04= formation. The increase in particulate matter in the plume within 50 m downwind of the stack exit resulted in an estimated double amount of fine or inhalable particulate matter than that indicated by the source measurements. It was concluded from the data that the visible plume formed during bypass mode operation was the result of fine particle formation, predominantly NH4CI, but with some sulfite-sulfate salt formation, prob- ably a result of water droplet chemistry. The EPA authors, James L. Cheney (also the EPA Project Officer, see below), William D. Connor. Roy L. Bennett, Donald L. Duke, Carole L. Walters, and Kenneth T. Knapp are with Environmental Sciences Research Laboratory, Research Triangle Park, NC 27711. The complete report, entitled "Formation of a Detached Plume from a Cement Plant," (Order No. PB 84-120 187; Cost: $11.50. subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Environmental Sciences Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 *US GOVERNMENT PRINTING OfFICE 1983-759-015/7247 United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 Official Business Penalty for Private Use $300 ------- |