2001 Progress Report: Characterization and Minimization of Fine Particulate Emissions from Waste Incinerators by Real-Time Monitoring of Size-Resolved Mass and Chemical CompositionEPA Grant Number: R828192
Title: Characterization and Minimization of Fine Particulate Emissions from Waste Incinerators by Real-Time Monitoring of Size-Resolved Mass and Chemical Composition
Investigators: Smith, Kenneth A. , Boudries, Hacene , Worsnop, Douglas R. , Zhang, X.
Current Investigators: Smith, Kenneth A. , Boudries, Hacene , Worsnop, Douglas R.
Institution: Massachusetts Institute of Technology , Aerodyne Research Inc.
Current Institution: Massachusetts Institute of Technology , Aerodyne Research Inc.
EPA Project Officer: Shapiro, Paul
Project Period: June 1, 2000 through May 1, 2003
Project Period Covered by this Report: June 1, 2000 through May 1, 2001
Project Amount: $335,000
RFA: Combustion Emissions (1999) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Air
The goal of this research is to perform a real-time analysis and quantification of particulate pollutants in the exhaust of waste incinerators. All the pollutants that we propose to measure are either known to be toxic or carcinogenic. Our approach to this task involves using two instruments: a laser-based aerosol mass spectrometer (AMS) for selective and sensitive detection of toxic organics (specifically, polycyclic aromatic hydrocarbons, or PAHs), and an Aerosol Mass Spectrometer (AMS, Aerodyne Research Inc.) for volatile and semivolatile compounds. This program is a collaborative effort between the research groups led by Professors Kenneth A. Smith at the Massachusetts Institute of Technology, Department of Chemical Engineering, and Dr. Douglas R. Worsnop at Aerodyne Research Inc. (ARI). The experimental results were obtained from a pilot-scale waste incinerator at the New Jersey Institute of Technology (NJIT), with the laser-based AMS specially developed for the project and an AMS instrument commercialized by ARI.
During the first year of the project, we have successfully accomplished all of the tasks scheduled in the proposal. These can be summarized as follows:
1. Development of a computer-based optic-electronic system to synchronize laser triggering with a chopper. In the design, the optical signal generated when the chopper opens to the particle beam is used to trigger a counter-board installed in the computer (Model CIO-DAS08-AOH, Computer Boards, Inc., Middleboro, MA); after waiting for a programmed delay time in terms of counter pulses, the board sends a signal to trigger the laser.
2. Introduction of a programmable counter (Model PCI-6601, National Instruments, Austin, TX) to generate certain frequency to control the chopper wheel at three positions: beam-open, chopping, and beam-blocking.
3. Upgrade of the software for the data acquisition system to control all instrument operations, including: laser triggering timing; chopper positions; spectra acquisition; and analysis, display, and storage of mass spectra according to operation conditions.
4. Consolidation of all instrument operation systems onto two modules: (1) the Instrument including the pumps and TOF; and (2) all control units of the instrument. The instrument is now easily portable and can operate on a mobile platform (e.g., on a truck). The two modules can be assembled within 2 to 3 hours.
5. Quantitative calibration of the REMPI AMS instrument using pure pyrene particles and comparing the calibration results with an Aerosol Mass Spectrometer (AMS, Aerodyne Research Inc.).
6. Application in a field experiment.
Both REMPI-AMS-MS, an AMS-Quadrupole (Jayne, et al., 2000), a Condensation Particle Counter, CPC (TSI, model CPC 3010), an Atomizer (Poly-disperse Aerosols, DMA, TSI Model 3071), and an atomizer (TSI Model 3076) were deployed at the NJIT from October 29, 2001, to November 2, 2001, to characterize in real-time aerosols emissions from the incinerator. During this experiment, we used well-defined fuel that had been prepared according to U.S. Environmental Protection Agency recommendations for previous experiments at NJIT. Aerosol size distribution and mass loading concentrations were measured for typical fuel used in a pilot-Incinerator at NJIT.
A resonance enhanced multiphoton ionization-time of flight aerosol mass spectrometer (REMPI-TOFAMS) has been modified for monitoring particulate emissions from the incinerator for selective and sensitive detection of some toxic organics (specifically, polycyclic aromatic hydrocarbons, or PAHs). The REMPI-TOFAMS and an ARI commercialized aerosol mass spectrometer (AMS) have been used to monitor particulate emissions from a pilot-scale solid waste incinerator. The REMPI-TOFAMS data indicates that particulate PAH emissions were relatively high at high tempearture (~850°C) when sampled before the baghouse. When particulates were sampled after the baghouse (low temperature), results similar to those seen with high temperature emissions before the baghouse were observed and the PAH concentrations were between 0.15 to 150 µg/m3, depending on the species. However, low concentrations of PAH have been observed at intermediate temperatures (~600°C). The data may suggest that 600°C is an appropriate temperature for low PAH emission, whereas MSW incinerators may operate at higher temperatures (900-1,200°C) with high particulate PAH emissions. Quantification of particulate PAH emission at high temperatures (900-1,200°C) is necessary to be representative of real emission from MSW incinerators.
Detailed analysis of mass spectrum obtained by the AMS instrument during the entire period shows the presence of five different groups of compounds: chlorides, ammonium, water, PAH, and organics. Nitrates and sulphates were not observed during this experiment. The total mass loading of aerosols were found to be negatively correlated with oven temperature. A substantial decrease in aerosols mass loading was observed when the PCC temperature surpassed 400°C.
The preliminary results from the NJIT pilot-scale incinerator allow us to determine the limit of the REMPI-TOF instrument and help us to determine what needs to be done to successfully accomplish the tasks scheduled for years 2 and 3. Below are the major modifications and improvements that need to be done during the next few months:
1. Systematic experiments are required to draw firm conclusions on the particulate
PAH emissions as functions of combustion temperature, fuel types, and air/fuel
2. Dynamic behavior of the instrument is not sufficiently fast to provide quantitative measurements for particle size distribution. Major upgrading on the vacuum system is required to conduct quantitative measurements on particle size distribution.
3. Upgrade the instrument so that it can acquire signals at two scales, higher scale for high concentration species like pyrene, low scale for low concentration species.
4. The sensitivity of the current instrument for PAHs is on the scale of 50 ng/m3. To measure PAH components for ambient particles that are on the order of 1 ng/m3 level, one needs also to improve ionization and detection efficiency of the instrument. With the 1 ng/m3 sensitivity, it is expected that the instrument would be able to detect chlorinated PAH emissions from an incinerator.