# Comparison and Evolution of Particle Siz **e Distributions fr**  **om a High Efficiency Wo**  **od Boiler Using**  **Tw o**  **Ty pes of Fuel:**  **Wo od Chips and**  **Wo od Pellets** 

Suresh Raja
, James Laing, Thomas Holsen , Philip K. Hopke
**Center for**  **A ir**  **Resour ces Engineering and Science, Clarkson**  **University**

**, Potsdam, NY**

**13699**

# High Efficiency **Wo od Boiler** 

 Hamont CA

Tfire ( Hamont Consulting and Engineering, Austria)  150kW (514,000 Btu.h

- 1 

# ) Output High Ef

ficiency Wo od Boiler  High ef

ficiency due to lar ge heat exchanger surface area and good insulation  Automated fuel feed system  Duel air staging process  Oxygen sensor to control Lambda air to fuel ratio  Can burn wood as pellets, shavings or chips PKH1**Slide 2**

**PKH1** Undefined. Suggest deleting it here.

Philip Hopke, 10/20/2009

# Wo **od Pellets and Wo**  **od Chips**

**Wo od**  **Pellets:**

• made from compacted sawdust

• debarked clean wood used

• low moisture content due to pelletizing process **Wo od**  **Chips:**

• urban wood waste comprised prim arily of chipped wood pallets

• higher level of contamination, therefore, higher contaminants expected from

stack emissions

# Wo **od Pellets and Wo**  **od Chips**

**Wo od**  **Pellets Wo**  **od Chips** 

heat content (MJ/lbs) 8.49 6.72

mo isture (%) 4.80 26.6 ash ( d.w

. %) 0.60 1.79
carbon ( d.w

. %) 51.5 45.0 nitrogen ( d.w

. %) 0.13 0.37
sulfur ( d.w

. ppm ) 70.1 175  Wo od Pellets have higher heat content, therefore, higher com bustion ef ficiency  Higher fuel bound nitrogen and sulfur content of the wood chips expected to lead to higher NO
x 

## and SO 2 

## emissions  Higher ash content expected to lead to higher PM2.5 emissions

# Sour **ce Sampling System Schematics** 

Dilution Chamber

Dilution air Sam pling ports 142 m m quartz filter

Exhaust

PUF

HEPA filter PM 2.5 cyclone & nozzle Hot box Probe

Stack FMPS FDMS & TEOM CO

NO x SO 2 CO 2

in

- line filter

# Concentration of criteria pollutants (CO, NO **x** 

# , SO **2** 

# and **PM 2.5**  

# ) during steady state operation of boiler

**Time** 11:58 12:08 12:18 12:28**C O** **C o** **n c** **e n** **t r** **a t** **i o** **n (** **m g** **. m** **- 3** **)**

100 1000**C o** **n c** **e n** **t r** **a t** **i o** **n (** **m g** **. m** **- 3** **)**

0.1 1 10 100 1000

CO

NO x SO 2 PM 2.5



## Note: **Dashed line**  indicate data for Wo od Pellets **Solid line**  indicate data for Wo od Chips

# Concentration of criteria pollutants **(CO, NO x**  

# , SO **2** 

# and PM **2.5** 

# ) during shutdow **n of boiler** 

**Time** 16:54 17:04 17:14 17:24 17:34 17:44 17:54**C O** **C o** **n c** **e n** **t r** **a t** **i o** **n (** **m g** **. m** **- 3** **)**

10 100 1000 10000**C o** **n c** **e n** **t r** **a t** **i o** **n (** **m g** **. m** **- 3** **)**

0.001 0.01 0.1 1 10 100 1000

CO

NO x SO 2 PM 2.5



## Note: Ve rtical line indicates time of boiler shutdown process initiation. Wo od Chips used as fuel. PKH2**Slide 7**

**PKH2** yellow is vitually invisible from the audience. I changed the vertical line to magenta.

Philip Hopke, 10/20/2009

# Av **erage Ultra**

**- Fine PM Emission due to Combustion of**  **Wo od Chips and Pellets in a HE Boiler** 

**Time** 11:00 13:00 15:00 17:00 19:00**A v** **e r** **a g** **e P** **a r** **t i** **c l** **e S** **i z** **e (** **n m** **)**

0 20 40 60 80 100 120 140 Wood Chips (Steady State)

Wood Pellets (Steady State) Wood Chips (Shutdow

n)

# Av **erage particle siz e**  **distribution at full load during steady state operation and during boiler**  **shutdow n** 

Electrical Mobility

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

0 20x10 6 40x10 6 60x10 6 80x10 6 100x10 6dN/dlogDp[#/cm3]BoilerShutdown

0.0 5.0e+8 1.0e+9 1.5e+9 2.0e+9 2.5e+9 3.0e+9 3.5e+9 Pellets - Steady

State Chips - Ste ady

State Chips - Shutdow

n

# Criteria emissions fr **om various types of**

**wo od** 

**- fir**  **ed burners and boilers** 

Note:
*



## – measurements include particles with diameters less than 2.5μm, cyclone used for PM control

♦



## – multiclones used in series for PM control

●



## – no controls for PM **Emission Species**  **Residential:**

Emission factors (EP

A, 1980) **This study:**

Av erage

em ission factors **Commercial:**

Emission factors (EP A, 2008) **This study:**

Av erage emission factors

**Fire**

  ** Place** ( g /kg) **Wo od**  **Stove** ( g /kg) **Wo od**  **Chips** ( g /kg) **Wo od**  **Pellets** ( g /kg) **We t** 

**Wo od**  (μ g /BTU ) **Dry Wo**  **od** (μ g /BTU) **Wo od** 

**Chips** (μ g /BTU) **Wo od** 

**Pellets** (μ g /BTU)

PM 13 ● 9.1 ● 0.54* 0.47* 158.8 ♦ 136.1 ♦ 50.6* 26.5*

SO 2 0.2 0.2 0.02 0.005 11 .3 11 .3 1.8 0.28

NO x 2 0.49 1.84 0.34 99.8 222.3 137 19.4

CO 67 180 2.13 2.16 272.2 272.2 158 122

# Conclusions

 Particle size distributions similar for steady state combustion of pellets and chips  During shutdown, GMD decreased and particle number increased  Gaseous and particle emissions are lower than normal wood boilers due to quasi

- complete combustion.  During shutdown, CO increased, while NO
x 

# , SO 2 

# and PM2.5 decreased  Higher fuel nitrogen and sulfur content of the wood chips may have resulted in higher NO
x 

# and SO 2 

# emissions  Higher ash content of the wood chips may have resulted in higher PM2.5 emissions

# Acknowledgments

.  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