Galen H. Richards

The chemical composition of environmental tobacco smoke III. Identification of conservative tracers of environmental tobacco smoke

Several components of environmental tobacco smoke (ETS) have been determined in experiments conducted in a 30 m3 Teflon chamber. The effect of residence time in the chamber on the particle size distribution, mass of particles, gas-particle equilibria, and chemical composition of both the gas and particle phases of environmental tobacco smoke has been studied. Many organic compounds present in tobacco smoke condensate are not found in the particle phase in environmental tobacco smoke but are present in the gas phase. Concentrations of several nitrogen containing organic compounds, identified in the chamber experiments, have been determined in several indoor environments where environmental tobacco smoke was present. These compounds were not found in indoor environments where environmental tobacco smoke was not present. The studies in the indoor environments indicate that gas phase nicotine and myosmine are removed from indoor environments at a much faster rate than gas phase 3-ethenylpyridine or 2-ethenylpyridine or particle-phase nicotine or cotinine. Gas-phase 3-ethenylpyridine and particle-phase nicotine are proposed as tracers of environmental tobacco smoke.

The character of ash deposits and the thermal performance of furnaces

The character of fireside ash deposits depend on the processes by which deposits are formed and subsequent reactions within the deposit and with furnace gases. The properties influencing furnace heat transfer, absorptivity for radiative transfer and thermal conductivity for conductive transfer are shown from many measurements to depend on this character. Illustrative trends in these properties as deposits mature and grow are presented together with their effect on furnace exit temperature and efficiency. The reflective character of initial deposits from particular coals is then considered with predictions and measurements of the spectral character of such deposits, during the first three hours of growth, using on-line FTIR spectroscopy.

Radiative heat transfer in pulverized-coal-fired boilers: Development of the absorptive/reflective character of initial ash deposits

Emission Fourier transform, infrare (FTIR) spectroscopy data provide in situ, time-resolved, spectralemissivity measurements for ash deposits generated from two U.S. Powder River Basin coals. The first 3h of deposit growth on a tube in cross flow in a pilot-scale furnace detail the development of surface emissivity with time. Measured emissivities vary significantly with wavelength, indicating the influence of the physical properties and chemical composition of the deposit. At long wavelength (>7 μm), emission features exhibit characteristics of silica, sulfates, and silicates. The spectral emissivity measured in this region approaches a steady value due to an increase in deposit thickness and the size of particles in the deposit. In contrast, deposits are not opaque at shorter wavelengths where the measured emissivity is influenced by the properties of the underlying metal surface. Theoretical predictions of the emsivity of a particulate layer were performed, and results are compared to the measured values. The theory adequately predicts the general features of spectral variation of the emissivity. The predicted trends in emissivity with particle size and deposit composition are also consistent with exerimental observations. Total (Planck-weighted) emissivities are calculated from the measured spectral values for the deposits at the tube temperatures. They increase with time from the clean tube value (0.2–0.3) to values typicals of deposits formed from western U.S. coal (0.45–0.55). Calculated total absorptivities are found to be lower than the correspoding emissivities.

Pyrite and illite associations in two eastern US bituminous coals

The ash transformation and deposition behavior of pyrite and illite, which are commonly identified with slagging, are influenced by the manner in which the minerals occur in the fuel. An enhanced computer controlled scanning electron microscopy technique was used to analyze the mineral content of individual coal particles in samples of two pulverized fuels. The particle-by-particle analysis determined whether individual mineral grains were included or excluded. It also provided information on which mineral species were likely to be found in the same coal particle with pyrite or illite. Illite typically appeared as included particles and was associated with a variety of other silicate species. In contrast, pyrite tended not to associate with other minerals and showed a significantly higher fraction of excluded particles. Such detailed observations of coal mineral distributions and associations provide additional insight into the mechanisms which govern fly ash formation.

Monitoring of Environmental Tobacco Smoke Nicotine with a Sorbent Bed-Capillary Gas Chromatograph System

Abstract A sorbent bed-capillary gas chromatographic analytical method well suited to monitor environmental tobacco smoke nicotine in an environmental chamber or in indoor environments has been developed. The sampled air passes directly through a glass tube filled with Tenax after which the tube becomes an insert for a packed column injector port where the sample is heat-desorbed to a cold trap and transferred to a capillary GC column. Nicotine is quantitated by the use of an external standard. The results show that this method can meet the need of monitoring nicotine in an environmental tobacco smoke chamber and can be easily applied to do routine environment monitoring. The method was used to monitor the concentration of gas phase nicotine in environmental tobacco smoke in a 30m3 Teflon chamber. The concentration of nicotine was found to be constant with time with ordinary fluorescent room lighting. However, when a UV-light bank was turned on to simulate photochemical conditions, the concentration of ni...

Investigation of Mechanisms for the Formation of Ash Deposits for Two Powder River Basin Coals

Two subbituminous coals from the Powder River Basin were fired in a pilot-scale combustor to study ash deposit formation under low-temperature fouling conditions. The two coals were chosen as they are similar in composition, but behaved differently when fired in a utility boiler. This study focuses on the mechanisms governing the formation of the initial deposit layer and is limited to deposition times of approximately 3 hours.