Biofuel Combustion Characteristics and Flame Sensor Response

Neehad T IslamResearch Engineer

National Oilheat Research Alliance

Co-author(s):Dr. Tom Butcher

John LeveyRyan Kerr

Overview

•Advanced flame sensor response testing at NORA

•Test implemented to analyze cutoff in pumps that operated on biodiesel

•Dissection of pumps to observe wear and tear

•Rigorous combustion testing on biodiesel including emissions analysis

Advanced Flame Sensor Testing: Methodology

• CAD cell connected to voltage source

• DAQ system collects voltage data every 100ms to show flame behavior

• Pumps from field tested: 12 that ran B20 at least ~10 years, 7 on No. 2 for same time

• Run in cold-start and steady state to analyze transient start and cutoff responses

Simple Circuit for CAD Cell Testing

Notable Observation

180

220

260

300

340

380

420

0 0.4 0.8 1.2 1.6 2

CA

D C

ell R

esis

tan

ce (Ω

)

Time (s)

Solenoid No Solenoid

Repeatability of the Trend

180

220

260

300

340

380

420

0 0.4 0.8 1.2 1.6 2

CA

D C

ell

Re

sist

ance

(Ω

)

Time (s)

230

250

270

290

310

330

350

370

390

410

0 0.4 0.8 1.2 1.6 2

CA

D C

ell

Re

sist

ance

(Ω

)

Time (s)No. 2 B20

*Both pumps do not have solenoid valves

Cutoff Comparison

Examination of Parts

• Each pump was dissected after testing• Pictures of parts taken for comparison• Piston heads below are examples

Never exposed to bio

Ran B20 ~ 10 years

Piston Head – Nominal B0

Piston Head – Nominal B20

Pump Gear– Nominal B0

Pump Gear– Nominal B20

Pump Face– Nominal B0

Pump Face – Nominal B20

Pump Strainer – Nominal B0

Pump Strainer – Nominal B20

Biodiesel Combustion Testing

•Combustion testing on biodiesel with varying viscosities

•Baseline No. 2 oil test for comparison

•Varying excess air – CO2 sweep from ~9-10% to ~15%

•Emissions characteristics for CO2, CO and NOx and SMOKE

•CAD Cell Resistance measured over 10 seconds and averaged

•Graphs made with CO2 as independent variable

CO2 and Excess Air Relationship

6

7

8

9

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16

0 20 40 60 80 100

Flu

e ga

s C

O2

(%

)

Excess Air (%)

B0 B20 B50 B100

B20 Comparison: Carbon Monoxide

0

150

300

450

600

750

900

9.5 10.5 11.5 12.5 13.5 14.5 15.5

CO

(p

pm

)

CO2 (%)

No. 2 High Visc B20 Low Visc B20

B20 Comparison: CAD Cell Resistance

250

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450

550

650

750

850

9.5 10.5 11.5 12.5 13.5 14.5 15.5

CA

D C

ell

Re

sist

ance

(Ω

)

CO2 (%)

No. 2 High Visc B20 Low Visc B20

B20 Comparison: Nitrogen Oxides

50

60

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100

110

9.5 10.5 11.5 12.5 13.5 14.5 15.5

NO

x (p

pm

)

CO2 (%)

No. 2 High Visc B20 Low Visc B20

B20 Comparison: SMOKE

0

1

2

3

4

5

6

7

8

9

13.5 13.8 14.1 14.4 14.7 15 15.3

SMO

KE

CO2 (%)

No. 2 High Visc B20 Low Visc B20

What’s the Big Deal?

•Advanced flame sensor testing analyzing pump cutoff shows that operation of pumps with B20 does not hinder performance

•Wear and tear of pumps operating on B20 are essentially the same as those on No. 2 oil

• Combustion performance of B20 means seamless transition from No. 2 oil