Time (mins) 0 60 120 180Concentration(mg/MJ)

0.1 1 10 100 1000 10000 CO NOx SO2

PM2.5 Particle s (x1 E10 #/MJ)

El ect ri cal Mobility

Diameter [nm] 1 10 100 1000dN/dlogDp[#/cm3]

0 1e+7 2e+7 3e+7 4e+7 5e+7 6e+7 7e+7 

# Gaseous, Particulate and **Semi**

**- volatile Emission Rates fr**  **om a High Efficiency**

**Wo od Pellet Boiler** 

**using Wo**  **od Pellets** J. Laing, S. Raja, T. M. Holsen, P. K. Hopke 

## Intr **oduction** There has been mounting concern over the health risks posed by pollutants emitted from biomass combustion, particularly fine PM. However , newer designs of fully automated, high ef ficiency wood boiler systems have been presented as a solution due to their low emissions. Continuous measurements of carbon monoxide, nitrogen oxides, sulfur dioxide, PM 2.5 , particle number concentration, and particle size distributions from a Hamont CA Tfire (Hamont Consulting and Engineering, Austria) gasification wood boiler (Figure 1) running at steady state were determined using wood pellets as fuel. Particle or ganic and elemental carbon fractions and particle and semi

- volatile or ganic compounds were also quantified. 

## Results

**Summary of Findings**  Selected two and a half hours of continuous gaseous and particle emission measurements are displayed in Figure 4. The temporal variations in emissions are seen collectively among all species, indicating that they are a function of in boiler variability . Emission factors for gaseous species, PM 2.5 , or ganic and elemental carbon, and particle number concentration are shown in Ta ble 2. All criteria emissions were relatively low , comparable to other studies. To tal carbon made up around 8.8 percent of PM 2.5 mass, the rest being inor ganic compounds derived from volatizing ash forming elements. The low or ganic fraction of PM 2.5 and the low CO emissions attest to nearly complete combustion in the boiler

. The ultrafine particle distribution during steady state operation was unimodal with a geometric mean diameter of 89 nm (Figure 5). Particle number concentration was 1.50 x 10 13 particles/MJ. Particle and semi

volatile or ganic compound emissions are presented in Ta ble 3. Alkanes were the most prevalent group of compounds, peaking at C 29 . Levoglucosan was the second most prominent resolved compound. P AHs were dominated by phenanthrene, acenaphthylene, pyrene, and fluoranthene, with minor amounts of indeno[1,2,3

- cd]pyrene, naphthalene, anthracene, and retene. Hexadecanoic acid, octadecanoic acid, and nonanoic acid were the predominant alkanoic acids. 

## Experimental Methods Emissions characterizations were performed on the gasification wood boiler running at steady state using wood pellets. The boiler has a thermal capacity of 150kW and was run at 76% capacity during testing. A dilution stack sampling system (Figures 2 & 3) conforming to EP A’ s conditional test method (CTM) 039 was used to provide sample flue gas to ambient gas monitors, a TEOM with FDMS, and an FMPS. A switch valve prior to the gas monitors provided background ambient concentrations ten minutes out of every hour . Quartz fiber filters and polyurethane foam (PUF) samples were collected and analyzed for particulate or ganic and elemental carbon content by the NIOSH protocol as well as gaseous and particulate or ganic compounds using GC/MS. Or ganic compounds included polycyclic aromatic carbon (P AHs) compounds, n

- alkanes, alkanoic acids, dicarboxylic acids, certain bio

- markers and levoglucosan. **Figur e 3.**  Dilution Sampling System. **Figur e 4.**  Gaseous and particle emission concentrations during steady state operation.

**Figur e 5.**  Particle size distribution during steady state operation for wood chips. **Ta ble**  **1**

**.** Characteristics of the Fuel

.



## Fuel **Analysis** The wood pellets used were manufactured by New England Wo od Pellet, LLC. Samples were collected for every testing period from the boiler feed bin. Gross heating value, ash content, moisture content, sulfur content, and nitrogen content were determined (T able 1). 

### Fuel Characteristics **Wo od Pellets**  heat content (MJ/lbs) 8.49 moisture (%) 4.80 ash (d.w . %) 0.60 carbon (d.w . %) 51.5 nitrogen (d.w . %) 0.13 sulfur (d.w

. ppm) 70.1 **Figur e 1.**  Hamont CA

Tfire Wo od Boiler

. **Ta ble 2.**  Gaseous and particle emissions factors. All emissions are in mg/MJ unless otherwise noted.

Dilution Chamber

Dilution air Sampling ports 142 mm

quartz filter

Exhaust PUF

HEP A filter PM 2.5 cyclone & nozzle Hot box

Probe

Stack FMPS FDMS & TEOM CO

NO x SO 2 CO 2

in

- line filter **Ta ble 3.**  Particle and semi

- volatile or ganic emissions

. **Organic Compounds μg/MJ**  Alkanes 377 PA Hs 32.0 Aromatic acids 28.9 Alkanoic acids 59.4 Dicarboxylic acids 37.3 Pentacyclic triterpane (hopanes) 39.2 Cholestane (sterols and cholestenes) 0.45 Methyloxylated phenols 15.7 Sterols 0.35 Levoglucosan 50.2 **Figur e 2.**  Schematic of Dilution Sampling System. **Emission Species**  **(mg/MJ) This Study**  **Other Studies**  **Hamont CA**  **Tfir e**  **Old**

**- type** 

**boilers*** **Modern wood**

**boilers*** CO 11 5 ± 1.21 7433 1324 NO x 18.4 ± 0.10 61.2 91.7 SO 2 0.26 ± 0.00 PM 2.5 25.1 ± 0.34 566 a 35.7 a OC 2.15 ± 0.64 EC 0.07 ± 0.03 total particle x10 12 (#/MJ) 15.0 ± 0.10 559 45.7 GMD (nm) 89.3 ± 0.06 *Johansson 2004 a To tal PM

– in

- stack filter

**Acknowledgements** This study was funded by the New Yo rk State Ener gy Research and Development Authority (NYSERDA) under contract 10672

. We want to thank David Dungate of ACT Bioener gy for his assistance in these studies

.