Parametric Gasification of Oak 

and Pine Feedstocks Using the 

TCPDU and Slipstream Water-Gas 

Shift Catalysis 

Jason Hrdlicka, Calvin Feik, Danny Carpenter, and 

Marc Pomeroy 

Technical Report 

NREL/TP-510-44557 

December 2008 
Parametric Gasification of Oak 

and Pine Feedstocks Using the 

TCPDU and Slipstream Water-Gas 

Shift Catalysis 

Jason Hrdlicka, Calvin Feik, Danny Carpenter, and 

Marc Pomeroy 

Prepared under Task No. H2713B13 

Technical Report 

NREL/TP-510-44557 

December 2008 

National Renewable Energy Laboratory

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iii 

Executive Summary 

The goal of the Gasification of Biomass to Hydrogen project is to experimentally verify the 

technical and economic performance of an integrated biomass gasification-based hydrogen 

production process based on steam gasification. Through the auspices of the Department of 

Energy (DOE) Hydrogen Program, the National Renewable Energy Laboratory (NREL) has 

developed techno-economic models and analyses that have indicated that hydrogen production 

from biomass may be a viable approach. Costs developed in the techno-economic modeling 

effort have been used in H2A (DOE’s Hydrogen Analysis project) modeling and have resulted in 

estimated hydrogen costs of $1.77/kg (current) and $1.47/kg (advanced in 2015). 

To experimentally verify this work, NREL’s Thermochemical Process Development Unit 

(TCPDU) was used. The TCPDU is an integrated system of unit operations designed to 

investigate biomass thermochemical conversion to gaseous and liquid fuels and chemicals. The 

TCPDU has a biomass throughput range of 10–30 kg/hr. The TCPDU’s capabilities include 

gasification/pyrolysis, solid separation, full-stream methane and tar reforming, liquid scrubbing, 

and slipstream water-gas shift catalysis. Analytical instrumentation, including continuous nondispersive infrared analyzers, gas chromatographs, and molecular beam mass spectrometry, 

measures gas and tar compositions at various steps in the process. 

A comprehensive experimental design of tests was developed to explore variations in the 

biomass-derived product gas composition as a function of a range of process conditions. Oak and 

pine were used as feedstocks for this project. Product gas composition (H2, CO, CO2, CH4, C2H2, 

C2H4, C2H6, C3s, and C4s), tar composition, and tar concentration were measured, and carbon 

conversion and material balances were determined for a total of nine process conditions 

established by varying thermal cracker temperatures (750°C, 850°C, and 950°C) and steam-tobiomass ratio (0.74, 1.25, and 2.00 for oak; 0.81, 1.25, and 2.00 for pine). For the slipstream 

water-gas shift catalysis, a commercial sulfided cobalt/molybdenum catalyst was used. The Full 

Stream Reformer (FSR), with an NREL-developed, nickel-based catalyst (NREL56), was used 

during water-gas shift fixed-bed reactor testing to maximize H2 production. 

In general, results from this study show that a higher steam-to-biomass ratio and a higher thermal 

cracker temperature yielded a higher hydrogen concentration. The hydrogen concentration 

ranged from 26%–39% vol. (dry, N2-free) for oak and 35%–42% vol. for pine gasification. The 

carbon monoxide concentration ranged from 18%–31% vol. for oak and 15%–23% vol. for pine. 

The H2-CO ratio for oak varied between 0.9 and 2.1 with an average of 1.2. The H2-CO ratio for 

pine varied between 1.5 and 2.7 with an average of 2.0. Overall mass closures of 88%–100% 

were achieved during the parametric oak gasification studies and 86%–100% for pine 

gasification studies. Qualitative tar measurements were very similar between the two feedstocks. 

The shift catalyst was tested using bottled gases with an H2-CO ratio of 4.2, which is 

representative of the syngas produced in the TCPDU when the FSR is on-line. CO conversion of 

74% was obtained using a shift reaction temperature of 450°C (842°F), steam-to-H2 ratio of 5.0, 

and a gas hourly space velocity (GHSV) of 21,000. The H2-CO ratio increased from 4.2 at the 

inlet to 17 at the outlet. The TCPDU was then used to generate pine-derived syngas at a steamto-biomass ratio of 2.0 and a thermal cracker temperature of 850°C (1562°F). Using the same 

shift-reactor conditions as in the bottled-gas test, the CO conversion using pine-derived syngas 
 iv

was initially 68%. After six hours, the CO conversion decreased to 65%. The H2-CO ratio 

increased from 4.2 at the inlet to 14 at the outlet. The shift catalyst was not tested with oakderived syngas. 
Table of Contents 

Executive Summary ..................................................................................................................... iii

Table of Contents .......................................................................................................................... v

List of Figures ............................................................................................................................... vi

List of Tables ................................................................................................................................ vi

1 Introduction ....................................................................................................................... 1

2 Experimental Procedures ................................................................................................. 2

2.1 TCPDU Process Description........................................................................................... 2 

2.2 Full Stream Tar Reformer ............................................................................................... 4 

2.3 Fixed Bed Reactor Process Description .......................................................................... 5 

2.4 Analytical Gas Sampling ................................................................................................ 7 

2.5 Hot Gas Sampling—Tar Measurements ......................................................................... 9 

2.5.1 TMBMS Instrument .......................................................................................... 9 

2.5.2 Tar Calibration ................................................................................................ 10 

2.6 Water-Gas Shift Catalyst .............................................................................................. 12 

2.7 Experimental Test Matrix ............................................................................................. 12 

2.8 Solid Sample Analyses—Feed and Char Residues ....................................................... 14 

3 Experimental Results ...................................................................................................... 16

3.1 GC Gas Sampling Results ............................................................................................. 16 

3.2 Mass Spectral Results—Tar Concentrations ................................................................ 17 

3.2.1 Raw Syngas ..................................................................................................... 17 

3.2.2 Reformed and Scrubbed Syngas ..................................................................... 20 

3.3 Shift Catalyst Performance ........................................................................................... 22 

3.4 Material and Element Balances .................................................................................... 24 

4 Conclusions ...................................................................................................................... 25

References .................................................................................................................................... 26

Appendix A—Char Analysis ...................................................................................................... 27

Appendix B—Mass Balances ..................................................................................................... 31

Appendix C—Tar Concentrations ............................................................................................ 36

v 
List of Figures 

Figure 1: Process flow sheet for NREL’s Thermochemical Process Development Unit 

(TCPDU). The full stream tar reforming (FSR) reactor shown was on-line during the 

shift catalyst tests. MBMS sampling is performed before and after the FSR reactor as 

well as after the scrubber. ............................................................................................. 3 

Figure 2: Process flow sheet for the Full Stream Reformer (FSR) .............................................. 5 

Figure 3: Schematic of fixed bed reactor system (BTRS, Jr.) ...................................................... 7 

Figure 4: Schematic of TMBMS gas sampling system: (1) sampling manifold; (2) flow-control 

valve; (3) orifice-plate flow meter; (4) sampling orifice; (5) condenser; (6) chilled 

impingers with cotton wool; (7) coalescing filter; (8) pressure control valve; (9) 

sample pump; (10) dry test meter. Shaded areas maintained at 450°C. ..................... 10 

Figure 5: Response curves from liquid standard injections for the TMBMS for various tar 

species. Dashed lines represent linear least-squares fits to the data ........................... 12 

Figure 6: Time-averaged pine gasification mass spectra collected during steady-state conditions 

97075, 97085, and 97095 corresponding to thermal cracker temperatures of 750°C, 

850°C, and 950°C, respectively. Steam:biomass = 2:1, 8" fluidized bed = 700°C .... 19 

Figure 7: Time-averaged mass spectra showing components of raw, reformed, and scrubbed 

syngas during steady-state condition PI_HY_97850 .................................................. 21 

List of Tables 

Table 1: Nominal composition of liquid calibration standard for tar species ............................ 11 

Table 2: Summary of parametric oak gasification process conditions ....................................... 13 

Table 3: Summary of parametric pine gasification process conditions ...................................... 14 

Table 4: Proximate, ultimate, and elemental ash analysis for oak and pine feed samples ......... 15 

Table 5: Summary of dry, nitrogen-free gas composition for parametric oak tests ................... 16 

Table 6: Summary of dry, nitrogen-free gas composition for parametric pine tests .................. 17 

Table 7: Molecular weight and identification of common hydrocarbons detected in corn stover 

gasification product gases with the TMBMS ............................................................... 18 

Table 8: Comparison of tar concentrations in raw oak- and pine-derived syngas for quantified 

species representative of conditions established for 97085 .......................................... 20 

Table 9: Average concentrations (mg/Nm3

-dry basis) of pine-derived tars in raw, reformed, and 

scrubbed gas ................................................................................................................. 22 

Table 10: Bottled-gas test results using an H2-CO ratio of 1.0, no CO2 ...................................... 23 

Table 11: Bottled-gas test results using an H2-CO ratio of 4.2, 27 vol% CO2 ............................. 23 

Table 12: TCPDU-gas test results with an H2-CO ratio of 4.2 using pine feedstock ................... 24 

Table 13: Char analysis for oak samples ...................................................................................... 27 

Table 13: Char analysis for oak samples cont. ............................................................................. 28 

Table 14: Char analysis for pine samples ..................................................................................... 29 

Table 14: Char analysis for pine samples cont. ............................................................................ 30 

Table 15: Mass balances for oak gasification conditions ............................................................. 31 

Table 15: Mass balances for oak gasification conditions cont. .................................................... 32 

Table 15: Mass balances for oak gasification conditions cont. .................................................... 32 

Table 15: Mass balances for oak gasification conditions cont. .................................................... 33 

vi 
 vii

Table 15: Mass balances for oak gasification conditions cont. .................................................... 33 

Table 16: Mass balances for pine gasification conditions ............................................................ 34 

Table 16: Mass balances for pine gasification conditions cont. ................................................... 34 

Table 16: Mass balances for pine gasification conditions cont. ................................................... 35 

Table 16: Mass balances for pine gasification conditions cont. ................................................... 35 

Table 17: Absolute wet gas concentrations (mg/Nm3

) of selected tars measured during steadystate oak gasification. ................................................................................................... 36 

Table 18: Absolute wet gas concentrations (mg/Nm3

) of selected tars measured during steadystate pine gasification. .................................................................................................. 36 
1 

1 Introduction 

The goal of the Gasification of Biomass to Hydrogen project is to experimentally verify the 

technical and economic performance of an integrated biomass gasification-based hydrogen 

production process based on steam gasification. Through the auspices of the Department of 

Energy (DOE) Hydrogen Program, the National Renewable Energy Laboratory (NREL) has 

developed techno-economic models and analyses that have indicated that hydrogen production 

from biomass may be a viable alternative to fossil fuel based hydrogen production. Costs 

developed in the techno-economic modeling effort have been used in H2A (DOE’s Hydrogen 

Analysis project) modeling and have resulted in estimated hydrogen costs of $1.77/kg (current) 

and $1.47/kg (advanced in 2015). 

While these estimates are encouraging, they are based on non-integrated, pilot-scale data 

generated by Battelle Columbus Laboratories (BCL) in the 1980s. To give additional credibility 

to the estimates, integrated testing is required. This project has provided data needed to confirm 

gasification yields and gas compositions, has provided experimental hydrogen-yield data, and 

will provide updated techno-economic information for program evaluation efforts. 

Based on DOE-supported gasification research[1], NREL has developed gasifier yield 

correlations for indirectly heated steam gasification of biomass. These results have been used by 

NREL[2] and others[3] to indicate the feasibility of producing hydrogen and other fuels from 

biomass. These studies have also shown the benefits of catalytically converting high-molecular 

weight contaminants (tars) and light hydrocarbons (methane, ethane, etc.) in one unit operation. 

These early efforts were used by NREL to develop detailed ASPEN models and accompanying 

economic models[4] that were used to provide yield, capital cost, and operating cost data for use 

in H2A. 

The BCL Process Development Unit (PDU) was used to gather basic gasification-yield data 

under steam gasification conditions. The major components of the systems were the 

gasifier/heater, cyclones for solids separation, and a water scrubber for removal of tars. To 

further support the yields expected from a steam gasifier, a comparison of data from the BCL 

gasifier and the large FERCO gasifier in Vermont was made in 1995.[5] Gas yields and 

compositions were comparable. Tar sampling was not performed independently of the scrubber. 

In later efforts the NREL transportable molecular-beam mass spectrometer was used to 

independently measure tars, both at the Battelle PDU and at the NREL PDU. These 

measurements have been used to estimate tar yields in updated yield correlations. Very low 

contaminant levels are allowable in shift reactors and steam methane reformers.[6] Tars, 

ammonia, and halide levels must be less than 0.1 mg/Nm3

 for fuels synthesis.[7] 

Typical CO conversion in a natural gas-ammonia plant in a high-temperature, water-gas shift 

reactor is reported as 76%.[8] There have been some recent attempts to produce hydrogen from 

biomass-derived syngas using water-gas shift catalysts. Brown et al.[9] generated biomassderived syngas using a ballasted gasifier, steam reformer, and two-stage water-gas shift reactor 

system. They were able to achieve 83% CO conversion in the high-temperature shift reactor and 

98% conversion in the overall two-stage process. Haryanto et al.[10] looked at ultra hightemperature (>500°C) water-gas shift catalysts to increase overall process efficiency using 

bottled gas. They produced initial CO conversions of 40% for Ir on alumina, 50% for Pt-Ce on 

alumina and Rh-Pt-Ce on alumina, and 80% for Rh-Ce on alumina. 
2 Experimental Procedures 

2.1 TCPDU Process Description 

The Thermochemical Process Development Unit (TCPDU) is an integrated system of unit 

operations designed to investigate biomass thermochemical conversion to gaseous and liquid 

fuels and chemicals. The individual unit operations were designed to permit multiple equipment 

configurations. The ability to reconfigure the TCPDU permits operation over a wide range of 

conditions from pyrolysis to gasification and facilitates the evaluation of various processes and 

feedstocks for multiple users. The TCPDU also enables study of catalytic upgrading of pyrolysis 

vapors and raw syngas conditioning, depending on research needs. 

Extensive instrumentation for Supervisory Control and Data Acquisition (SCADA) is used to 

continuously monitor process streams at key locations. This monitoring assures operators that 

mass closure is obtained before and during analytical measurements of performance tests. Stateof-the-art analytical equipment has also been integrated into the TCPDU to determine product 

composition at various points in the process. The SCADA and analytical equipment are linked to 

enable data integration into a single database-management system. 

The feeding system consists of a loss-in-weight feeder with a 450 L hopper (200 kg capacity) 

that meters pelletized biomass through two purged rotary valves, then into a crusher that grinds 

the material to less than 2-mm particle size, and finally through a third rotary valve. The rotary 

valves isolate the process from the feeding system before the feed drops into a 22-mm diameter 

screw, which augers the feed into the gasifier at a rate between 5 and 30 kg/hr (11 and 66 lb/hr). 

The first reactor in the process is an electrically heated fluidized bed reactor that is 20.3 cm (8 

in.) in diameter with a freeboard that is 40.6 cm (16 in.) in diameter. The bed zone is 76.6 cm (34 

in.) high. The freeboard zone is 170.2 cm (67 in.) high connected by a frustrum that is 29.2 cm 

(11.5 in.) high. The total reactor volume is 260 L (9.10 ft3) after accounting for the volume 

displaced by the olivine used in the bed. The bubbling bed is fluidized with either superheated 

steam for gasification experiments or preheated nitrogen for pyrolysis experiments. The 

minimum steam flow rate to maintain fluidization of olivine (ρ = 1.73 g/mL) is 10 kg/hr (22 

lb/hr) to maintain a superficial gas velocity of 25 cm/s (0.8 ft/s). Typical steam flow rates are 

varied between 10 and 30 kg/hr (22 and 66 lb/hr), depending on biomass feed rate and desired 

gas composition. For gasification, a steam-to-biomass ratio between 0.5 and 3 is desired. 

In the process configuration for gasification, as shown in Figure 1, gas, entrained char, and bed 

material flows from the reactor through a pipe that is 3.81 cm (1.5 in) in diameter and into a 

thermal cracker. The thermal cracker is 26 m (85 ft) long by 3.81 cm (1.5 in.) diameter tubular 

reactor with 11 independently controlled, electrically heated zones. The volume of the thermal 

cracker is approximately 28 L (1.0 ft3

). 

2 
Figure 1: Process flow sheet for NREL’s Thermochemical Process Development Unit (TCPDU). 

The full stream tar reforming (FSR) reactor shown was on-line during the shift catalyst tests. 

MBMS sampling is performed before and after the FSR reactor as well as after the scrubber. 

Downstream of the thermal cracker are two cyclone separators in series with barrels measuring 

10.2 cm (4 in) and 7.6 cm (3 in.) in diameter, respectively. The design collection efficiency of 

each cyclone is 95% with an overall design collection efficiency of 99.7%. Captured solids 

removed by the cyclones are collected in char pots below the cyclones. The char pots are 

emptied automatically, according to a programmable schedule, into an intermediate vessel where 

the char is cooled using nitrogen gas. The cooling vessel is operated like a lock hopper. After the 

char has cooled, it is transferred to a collection vessel that sits on an electronic scale to acquire 

mass data. Discrete char samples can be collected at this point for analysis, or bulk char can be 

accumulated and collected for further analysis or disposal. 

The gas leaving the cyclones moves quickly through the remaining 3.81 cm (1.5 in.) diameter 

pipe to the scrubber system. The volume of the piping between the cyclones and the scrubber is 

about 7.1 L (0.25 ft3

). Heated sample ports are available in this section of pipe for removing 

process gas or vapors and directing it to on-line analytical equipment for compositional analysis. 

The condensation operation consists of a conical vessel (25.4 cm to 5.08 cm taper) for mixing 

hot gases with cooling liquid followed by a vessel that is 25.4 cm (10 in.) in diameter with 

nozzles in the top to spray in cooling liquid. Dodecane cools the process gas. Dodecane easily 

separates from the condensed steam and assists with tar removal from the process gas stream. 

The dodecane flow rate is about 114 L/min (30 gal/min). This rate is sufficiently high to keep the 

dodecane from heating significantly as it contacts the hot gases and vapors entering the 

condensation vessels. The warm dodecane and condensed steam are pumped through a two 

 3
micron filter to remove residual particulate not collected by the cyclonic separators. The liquid 

then cools using a shell and tube heat exchanger and proceeds to a phase separator. The 

dodecane rises to the top of the phase separator and reenters to the scrubber. The condensed 

water and tar flow out the bottom of the phase separator to the settling tank. 

Condensed steam is pumped from the middle or water phase of the settling tank through a series 

of filters and into a stripping column where nitrogen removes light hydrocarbons. The stripped 

gases and nitrogen are directed to the thermal oxidizer (flare) for destruction. The water is then 

pumped back to a vessel where saturated steam at 850 kPag (125 psig) flowing through internal 

coils vaporizes the re-circulated water for process steam. Small amounts (ppm levels) of phenol, 

cresol, and naphthalene as detected by TMBMS sampling also return to the process. The 

concentrated “brine” in the reboiler is occasionally purged and disposed of as waste. 

Gas exiting the scrubber typically contains residual particulate not collected in the cyclones or 

scrubber and aerosols that form as the gas cools in the scrubber. Entrained particles or droplets 

exiting the second scrubber vessel are removed by filters with a nominal two-micron filtration 

size. These filters collect 1–3 kg/hr of material, most of which is entrained dodecane. The 

process gas cools further in another shell and tube heat exchanger. After a slipstream is removed 

for analytical sampling and for the shift catalyst reactor, the process gas is sent to the thermal 

oxidizer (flare) where it is combusted at 650°C (1202°F). 

2.2 Full Stream Tar Reformer 

The Full Stream Reformer (FSR) shown in Figure 1 and detailed in the Full Stream Reformer 

flow sheet in Figure 2 is an electrically heated fluidized bed reactor that is 35.6 cm (14 in.) in 

diameter with a freeboard that is 61 cm (24 in.) in diameter. The total FSR volume is 448 L (15.8 

ft3

) without any catalyst. The vessel consists of an inlet gas plenum, a fluidized bed section, and 

a freeboard. The plenum that is 33 cm (13 in.) high and 26.7 cm (10.5 in.) in diameter has a 

tangential gas inlet and is flanged to the bottom of the bed section. The gas distribution plate is 

welded to the top of the plenum and contains sixty-two 3.2 mm holes in concentric circles. The 

bed section is composed of an 18 cm (7 in.) high conical transition above the distributor and a 

pipe that is 92 cm (36.25 in.) high. The 100 cm (39 in.) high freeboard is connected to the bed 

section by a conical reducer that is 30.5 cm (12 in.) high. The FSR is mounted to a support stand 

at the bed to freeboard transition cone. The electrical bed heaters are supported by the plenum 

flange, and the freeboard heaters are supported by the vessel supports. 

The electric heaters are controlled using a cascaded proportional-integral-derivative (PID) 

control strategy. The highest temperature measured of the bottom three bed thermocouples and 

the heater surface temperature is used for the cascaded control. The vessel pressure is measured 

using a nitrogen-purged port on the freeboard to minimize catalyst plugging of the pressure lines. 

The catalyst is loaded into the vessel using a container connected to the catalyst fill port. Small 

samples may be taken from the bed during operation using a drain valve mounted in the center of 

the gas distributor. A cooling chamber on the bottom of the drain port allows hot samples to be 

collected safely for analysis. The same drain valve is used to drain the catalyst when the vessel is 

cool. 

 4
 5

Process gas from the gasification system mixes with superheated steam or nitrogen in an eductor. 

The combined gas heats further to at or near bed temperatures in the 6.7 m (22 ft) long, 

electrically heated preheater. The reformed gas exits the FSR via an internal cyclone that is 11.4 

cm (4.5 in.) in diameter. The cyclone collects entrained solids from the catalyst bed and returns 

them to the bed through a dip leg that is 4 cm (1.5 in.) in diameter. 

Catalyst regeneration requires the catalyst first to be oxidized to remove coke and other 

contaminates (e.g., sulfur). During catalyst oxidation, the FSR is isolated from the gasification 

process and fluidized by steam. Air may be introduced to the FSR just before the plenum for 

complete catalyst oxidation. Catalyst reduction occurs in the same manner except with the 

catalyst fluidized by nitrogen and hydrogen introduced to the plenum. The reforming catalyst is 

an NREL-developed, nickel-based catalyst. The current formulation is referred to as NREL56. 

Figure 2: Process flow sheet for the Full Stream Reformer (FSR) 

2.3 Fixed Bed Reactor Process Description 

Located in NREL’s Thermochemical Users Facility (TCUF), the BTRS, Jr. (Autoclave 

Engineers) and its associated equipment is a bench-scale fixed bed reactor system capable of 

handling reaction temperatures up to 650°C (1202°F) and pressures up to 200 barg (2900 psig). 

This system will be used to house the shift catalyst during this testing. Figure 3 shows a 
schematic of the reactor system. The high-pressure compressor is a lubrication-free, three-stage 

piston design. It has a maximum output capacity of 7.5 slm (16 scfh, 0.5 Nm3/h) at 152 barg 

(2200 psig). Reaching its maximum volumetric output requires a small, low-pressure gas booster 

pump to bring the inlet pressure up to 1.7 barg (25 psig). The low-pressure booster pump is a 

PTFE diaphragm design with a stainless-steel pump head, which is rated at an output of 15 slm 

(30 scfh, 0.9 Nm3/h) at 1.7 barg (25 psig) and a maximum output of 7 slm (15 scfh, 0.4 Nm3/h) at 

3.4 barg (50 psig). The gas is filtered for 0.1 μm aerosols and particulate before entering the high 

pressure compressor. 

Prior to entering the high-pressure compressor, the gas travels through a GC loop for analysis. 

All of the gas sent through this loop returns to the process to provide an accurate measurement of 

flow. The gas is then heated to 200°C (392°F) in an enclosed oven before entering the packed 

bed reactor where the gas is heated to the desired reaction temperature. Steam is added to the 

reactor by pumping water into the oven enclosure using an HPLC pump. The water evaporates in 

a heated coil before mixing with syngas. Depending on the hydrogen sulfide (H2S) concentration 

in the syngas, additional H2S may need to be added. Hydrogen sulfide is added directly at the 

inlet of the reactor using a mass-flow controller. 

The packed bed reactor is a stainless-steel (A-286) tube that is 431.8 mm (17.0 in.) in length and 

has an inner diameter of 13.1 mm (0.52 in.). The reactor was loaded with 10 mL (8.8 g) of 

catalyst at the outlet end. The catalyst occupied about 76 mm (3.0 in.) of the reactor, and the 

remaining length of the reactor was filled with glass wool for support and glass beads for heat 

transfer. 

After exiting the reactor, the gas passes through a condenser train consisting of two condensers 

using an ethylene glycol and water mixture (50:50) to cool the gas and steam to about 5°C 

(41°F). A knockout vessel follows the condensers to remove the condensed steam. The cooled, 

moisture-free gas travels through a GC loop for analysis. All of the gas that passes through this 

loop returns to the process to provide an accurate measurement of flow. A diaphragm valve 

measures the flow, and a dry test meter measures the gas-flow rate. The gas then travels to the 

thermal oxidizer (flare). 

 6
1.4 barg

Low pressure

compressor

High pressure

compressor

10 barg

Aerosol filters (0.1 um)

95% 99.99%

oven

enclosure

T=200 °C

Fixed bed

reactor

T=300-450 °C

P=10 barg

MFC

HPLC

pump

water

10%H2S/N2

Bottled or

TCPDU gas

GC and

MBMS

analysis

Flare

Condenser

train

Pressure/flow

control

Dry test meter

GC

loop

inlet

GC

loop

outlet

catalyst

bed

Figure 3: Schematic of fixed bed reactor system (BTRS, Jr.) 

2.4 Analytical Gas Sampling 

Extensive analytical instrumentation is available to determine gas composition at the exit of the 

TCPDU scrubbing system. Prior to analysis, however, the gas must be conditioned further before 

it is introduced to the instruments. A slipstream of the process gas is removed at the exit of the 

scrubbing system and compressed to 70 ± 10 kPa (10.2 ± 1.5 psig) in a Teflon diaphragm pump. 

The compressed gas then passes through a cold-finger condenser to remove excess moisture and 

any semi-volatile compounds (e.g., naphthalene, phenol) that might have bypassed the main 

process scrubber. The conditioned gas then passes to a pressure letdown valve, and the pressure 

reduces to 30 ± 2 kPa (4.3 ± 0.3 psig) before supplying the analytical instruments. To preserve 

the integrity of this sample slipstream in the analytical system, the gas comes in contact only 

with Sulfinert-passivated stainless steel (Restek, Bellefonte, CA) or Teflon surfaces. 

With steam and other condensable vapors removed from the product gas stream, compositions 

can be measured with three on-line, continuous, non-dispersive infrared (NDIR) chemical 

analyzers to monitor CO, CO2, and CH4: a thermal conductivity H2 analyzer; a paramagnetic O2

analyzer; and a four-channel, rapid-analysis gas chromatograph that cycles every three minutes 

to measure permanent gases and hydrocarbons (C2s through C4s and benzene). 

The analytical equipment includes: 

• California Analytical Instruments (CAI) Model 100P Paramagnetic Oxygen Analyzer 

with a range of 0–25 vol. %. 

 7
• Methane is measured with a CAI Model 100, NDIR Analyzer with a range of 0–50 vol. 

%. Carbon dioxide and carbon monoxide are measured with a CAI Model 200, NDIR 

Analyzer with a range of both analytes of 0–50 vol. %. 

• NOVA H2 thermal conductivity analyzer with a range of 0–50 vol. % and analog inputs 

for %CO, %CH4 and %CO2 to correct the hydrogen value. 

• A Varian Inc. CP4900 Quad Micro Gas Chromatograph (μGC) with thermal conductivity 

detectors (TCD). It is a four-channel, on-line, gas chromatograph with a cycle time of 

three minutes. A 10-m MoleSieve-5A column with an argon carrier is used to determine 

H2, O2, N2, CH4, and CO. Helium can also be determined when added as an internal 

standard. A 10-m PoraPlot Q column with a helium carrier is used to determine CO2 and 

C2H2. Ethane and ethene co-elute on this column and can be measured as a composite 

peak. A 10-m Alumina (sodium modified) column with a helium carrier is used to 

determine C2H4, C2H6, C3H6, and C3H8. This column can also determine higher paraffins 

and olefins, but for this use, the methodology has been optimized for the C2 and C3 

hydrocarbons. A 4-m methyl-silicone column with an argon carrier is used to determine 

C4 paraffins and olefins as well as benzene. 

• A second Varian μGC is used to duplicate some of these data points above but is also 

used for sulfur analysis. A 10-m Porabond Q column with a helium carrier is used to 

determine H2S and COS using a TCD as well as a tandem Differential Mobility Detector 

(DMD). 

Calibration gases to calibrate the on-line instrumentation and the two gas chromatographs are 

made by using two premixed, certified, commercial gas mixtures dynamically mixed on-line to 

generate the intermediate concentrations needed to calibrate across the experimental range. 

Divided between the premixed standards are all of the major gas components (H2, CO, CO2, 

CH4, C2s, C3s and C4s) expected in the product gas. In addition, there are mass-flow controllers 

to add nitrogen and helium to the mixed-gas standards for dilution and internal standard. The online gas analyzers are typically calibrated at their zero point using a mixture of nitrogen with 1% 

helium (the internal standard used in the process), and the span is adjusted with a gas mixture 

that closely approximates the gas composition under typical gasification conditions. The 

microchannel GC calibrates across a nine-point calibration curve that spans the range from 99% 

nitrogen to the highest concentrations found in the premixed commercial gas mixtures. The 

Sulfur μGC for sulfur measurements is calibrated using a standard mixture of H2S in nitrogen 

and COS in argon, which is then mixed with the other commercial gas calibration mixtures to 

calibrate the instrument at three levels. 

Each of the on-line instruments has an output of a 4–20 mA signal that is proportional to the 

analyte concentration. This signal is captured by an OPTO22 SCADA system and is recorded 

every minute to a log file on the system control computer. The GCs are both controlled by 

Varian Galaxie software running on a separate data-acquisition computer. The CP4900 

microGCs are cycled every three minutes, and the data are immediately transferred by a custom 

Excel macro to a spreadsheet. The spreadsheet displays a running graph of the concentration of 

all of the major gas components so operators can assess the stability of the process continuously. 

 8
2.5 Hot Gas Sampling—Tar Measurements 

2.5.1 TMBMS Instrument 

A transportable molecular-beam mass spectrometer (TMBMS) was used to provide continuous, 

on-line chemical analysis of hot product vapors from indirect gasification. The instrument, 

developed at NREL, is a useful tool for monitoring high-temperature thermochemical processes. 

The tool allows direct, real-time sampling of hot process vapors, providing a time-resolved 

account of the wet-gas composition. More information on the instrument can be found 

elsewhere.[11] A brief description follows. 

For these tests, a hot slipstream of the product gas from the TCPDU was conducted to the 

TMBMS through heat-traced and insulated 0.95 cm (0.375 in.) stainless-steel transfer lines 

maintained at 450°C (842°F). This temperature was hot enough to prevent condensation losses in 

the sampling system, yet sufficiently cool to minimize further thermal decomposition of the 

sampled tars. A heated sampling manifold filtered particulates and controlled the temperature, 

pressure, and flow of the sampled gases (see Figure 4). The gas-sampling system operated in 

“flow-by” mode, flowing approximately 3.5 standard liters per minute, of which the sampling 

orifice extracted roughly 10%. The unused gas passed through a condensation system to remove 

condensed steam and tars prior to the downstream metering system. 

A molecular beam forms as the gases are extracted through a 300 μm diameter orifice into the 

first stage of a three-stage, differentially pumped vacuum system. The nature of this free-jet 

expansion quenches chemical reactions and inhibits condensation by rapidly decreasing the 

internal energy of the sampled gases. The central core of this expansion becomes a molecular 

beam upon passing through a conical skimmer located at the entrance to the second stage of the 

vacuum system. The beam then enters the third stage where components are ionized and mass 

analyzed by a quadrupole mass spectrometer. Mass spectra are generated according to the 

measured signal intensity as a function of the molecular weight of the ions. 

The TMBMS is equipped with a heated sampling manifold and an OPTO22 (Temecula, CA) 

control system that allows it to interface with and monitor a variety of chemical process streams. 

Ten integrated temperature-control loops maintain sample line temperatures. The TCPDU 

process control system controls additional heaters for the sampling lines. Two mass-flow 

controllers introduce inert gases for sample dilution, liquid standard injections, and internal 

standards. Additional mass flow meters provide nitrogen purges to prevent line plugging and 

accumulation of process gases. Flow and pressure control valves operate in tandem to deliver a 

constant flow of gas at a constant pressure to the sampling orifice. OPTO stores values from 

these auxiliary channels electronically and uses them for data reduction. 

The mass spectrometer and spectral data collection were automated using a PC-based dataacquisition and control system manufactured by Extrel CMS (Pittsburgh, PA). Mass spectra were 

recorded for m/z=3 to m/z=400 along with auxiliary pressure data at a rate of 36 scans/min with 

one-minute averages stored. 

 9
1 

dP 

P 

9 

vent 

mass 

spectrometer 

8 

7 

5 6 

filters 

liquid standard 

dilution gas, cal. gases, 

scrubbed gas 

2 

3 

4 

TCPDU Process

10 

Figure 4: Schematic of TMBMS gas sampling system: (1) sampling manifold; (2) flow-control 

valve; (3) orifice-plate flow meter; (4) sampling orifice; (5) condenser; (6) chilled impingers with 

cotton wool; (7) coalescing filter; (8) pressure control valve; (9) sample pump; (10) dry test meter. 

Shaded areas maintained at 450°C. 

2.5.2 Tar Calibration 

The raw TMBMS mass spectra represent semi-quantitative, relative intensities for all species 

measured and detected. For the present parametric gasification studies, absolute tar 

concentrations in the product gas are desired for input into techno-economic models under 

development. Several factors, however, affect the instrument’s response non-uniformly to 

different chemical species. Absolute concentration data for selected tar species were achieved by 

carefully controlled injections of a liquid calibration standard containing benzene, toluene, 

phenol, cresol, naphthalene and phenanthrene dissolved in methanol. To avoid uncertainty due to 

sample matrix effects (e.g., bulk gas composition), the two-level standard is introduced as a 

standard addition while sampling raw process gas. Using high-pressure, liquid-chromatography 

(HPLC) pumps, the standard was injected into the sample line through a heated stainless-steel 

capillary downstream of the shut-off valves (see Figure 4). The liquid was vaporized upon entry 

into the sampling oven, giving rise to the changes in gas-phase concentration shown in Table 1. 

The weight loss of standard in the reservoir was recorded with a balance to determine the liquid 

feed rate. 

 10
Table 1: Nominal composition of liquid calibration standard for tar species 

Species Molecular 

Weight 

Standard Liquid 

Concentration 

(wt%) 

Std. Nominal 

Change in 

Concentration 

(mg/Nm3) 

Response 

Factor 

(counts per 

mg/L-actual) 

R2 from 

Calibration 

Curve 

Methanol 32 73.09 Low 

level 

High 

level 

Benzene 78 8.73 3810 7980 5.246 x 107 0.9995 

Toluene 92 7.92 3450 7240 4.910 x 107 0.9992 

Phenol 94 4.08 1780 3730 3.073 x 107 0.9971 

Cresol 108 1.79 780 1640 4.190 x 107 0.9984 

Naphthalene 128 3.36 1460 3070 9.934 x 107 0.9999 

Phenanthrene 178 1.03 448 940 1.015 x 108 0.9995 

Using the signal observed in the raw gas and during the standard injections, a three-point 

calibration curve was generated for each species in the standard. The response factors were 

derived from the slopes of the linear least-squares fits to the calibration data. Figure 5 shows the 

TMBMS response at specific molecular weights for each calibrated tar species from the liquid 

injection calibrations along with the linear least-squares fit (dashed lines). 

The mass spectrometer has proven to have a stable response to tar species across the spectrum, 

provided the sample matrix does not change significantly. Because large variations in gas 

composition are inherent in these parametric studies, and because conducting a liquid tar 

standard at each condition is prohibitively time consuming, additional steps were taken to ensure 

accurate calibrations. The liquid tar calibration was performed two to three times during each 

weeklong series of experiments. In addition, the instrument’s response to argon, added at a 

constant molar flow as a tracer gas in the TCPDU, was gauged at each discrete condition by 

carrying out a separate argon calibration. The tar response factors were then adjusted per 

condition for any changes observed in the argon response factors. 

 11
0.00E+00

2.00E+07

4.00E+07

6.00E+07

8.00E+07

1.00E+08

1.20E+08

1.40E+08

1.60E+08

1.80E+08

2.00E+08

0.0E+00 1.0E+03 2.0E+03 3.0E+03 4.0E+03 5.0E+03 6.0E+03 7.0E+03 8.0E+03 9.0E+03

Δ concentration (mg/Nm3

)

Response (counts)

benzene

toluene

phenol

cresol

naphthalene

phenanthrene

Figure 5: Response curves from liquid standard injections for the TMBMS for various tar species. 

Dashed lines represent linear least-squares fits to the data 

2.6 Water-Gas Shift Catalyst 

A commercial high-temperature, water-gas shift catalyst employed of cobalt and molybdenum 

active metals supported on high purity, activated alumina extrusions was used. The catalyst was 

received as 3 mm-diameter extrusions. The extrusions were hand crushed and sieved to a size of 

-14/+35 (0.5–1.4 mm). The bulk density of the sieved particles is 0.88 g/mL. This catalyst is a 

sulfided catalyst and requires an operating sulfur concentration of at least 30 ppmv. The catalyst 

was shipped in the oxidized form and was presulfided before exposure to syngas. The sulfidation 

procedure consisted of exposing the catalyst to 5 wt% H2S in nitrogen at an initial temperature of 

204°C (400°F) and gradually ramping up the temperature to a final value of 316°C (600°F). The 

sulfidation procedure was complete once the inlet and outlet sulfur concentrations were equal. 

2.7 Experimental Test Matrix 

A comprehensive experimental design was developed to explore variations in the biomassderived product gas composition as a function of a statistically robust range of process 

conditions. Product gas composition (H2, CO, CO2, CH4, C2H2, C2H4, C2H6, C3s, and C4s), tar 

composition and concentration, carbon conversion, and material balances were determined at a 

total of nine process conditions established by varying thermal cracker temperature (750°C, 

850°C, and 950°C) and steam-to-biomass ratio (0.74, 1.25, and 2.00 for oak; 0.81, 1.25, and 2.00 

for pine). The range of oak and pine gasification conditions attainable in NREL’s TCPDU are 

summarized in Table 2 and Table 3, respectively. 

 12
Material balances and on-line gas compositions determined by GC were determined in real time 

for all process conditions throughout the experimental campaign. On-line tar analysis by 

molecular beam mass spectrometry was also performed. Random grab samples of the pelletized 

oak and pine feed were taken, and selected char samples were isolated during each steady-state 

condition and were submitted for proximate, ultimate, and elemental ash analyses. 

Of the two process variables, thermal cracker temperature is easier to change and has less impact 

on overall process stability and steady-state operation. The thermal cracker temperature was 

never lower than the bed temperature. Varying the steam-to-biomass ratio can be achieved in 

several ways. The steam rate and the biomass-feed rate both can be varied independently 

between 10 and 30 kg/hr (22 and 66 lb/hr) within the limitations of maintaining fluidization in 

the reactor and heat conduction to the bed. 

From a steady-state process perspective, changing the steam-to-biomass ratio impacts the 

environment directly in the 8-in. fluidized bed reactor, specifically the dynamic accumulation 

and removal of unconverted carbon and ash, collectively referred to as char. During operation, 

large char particles accumulate in the reactor until a steady-state level is reached. The char 

particles leave the reactor once they become entrained in the exit gas. Entrainment occurs either 

when the particles become small enough to be carried by the gas or when larger particles enter 

into a region of higher velocity gas near the reactor outlet. For larger particles, this occurs more 

frequently as the char level in the bed increases in height. The rate at which the level increases is 

a function of the feed material density, size, shape, carbon conversion and feed-ash content. 

Consequently, a truly representative char sample associated with a given process condition is 

difficult to obtain when the bed conditions are changed during an experimental period. 

Table 2: Summary of parametric oak gasification process conditions 

Date/Time 

Started 

Date/Time 

Completed ID 

Biomass 

(kg/hr) 

Steam 

(kg/hr) S:B 

Bed 

Temp 

(°C) 

TC 

Temp 

(°C) 

11/20/2007 12:45 11/20/2007 14:41 OK_HY_97095 10.1 20.2 2.00 700 950 

11/28/2007 13:22 11/28/2007 16:22 OK_HY_97085 10.1 20.2 2.00 700 850 

11/28/2007 17:35 11/28/2007 20:35 OK_HY_97075 10.1 20.2 2.00 700 750 

11/29/2007 13:40 11/29/2007 16:47 OK_HY_77075 18.6 13.8 0.74 700 750 

11/29/2007 18:32 11/29/2007 21:32 OK_HY_77085 18.6 13.8 0.74 700 850 

11/30/2007 11:41 11/30/2007 15:00 OK_HY_77095 18.6 13.8 0.74 700 950 

12/4/2007 13:20 12/4/2007 14:44 OK_HY_97095b 10.1 20.2 2.00 700 950 

12/12/2007 11:56 12/12/2007 14:57 OK_HY_87095 13.85 17.3 1.25 700 950 

12/12/2007 16:15 12/12/2007 19:20 OK_HY_87085 13.85 17.3 1.25 700 850 

12/13/2007 13:30 12/13/2007 16:32 OK_HY_87075 13.85 17.3 1.25 700 750 

12/14/2007 11:45 12/14/2007 14:50 OK_HY_77085b 18.6 13.8 0.74 700 850 

12/17/2007 11:55 12/17/2007 15:20 OK_HY_97085b 10.1 20.2 2.00 700 850 

12/18/2007 13:24 12/18/2007 16:25 OK_HY_87085b 13.85 17.3 1.25 700 850 

 13
Table 3: Summary of parametric pine gasification process conditions 

Date/Time 

Started 

Date/Time 

Completed ID 

Biomass 

(kg/hr) 

Steam 

(kg/hr) S:B 

Bed 

Temp 

(°C) 

TC 

Temp 

(°C) 

8/26/2008 13:47 8/26/2008 16:50 PI_HY_97095 10.1 20.2 2.00 700 950 

8/27/2008 12:39 8/27/2008 16:11 PI_HY_97085 10.1 20.2 2.00 700 850 

8/28/2008 14:27 8/28/2008 17:27 PI_HY_97075 10.1 20.2 2.00 700 750 

9/2/2008 13:45 9/2/2008 16:48 PI_HY_77075 17.5 14.2 0.81 700 750 

9/3/2008 12:28 9/3/2008 15:45 PI_HY_77085 17.5 14.2 0.81 700 850 

9/4/2008 12:24 9/4/2008 15:40 PI_HY_77095 17.5 14.2 0.81 700 950 

9/5/2008 13:45 9/5/2008 16:50 PI_HY_87095 13.85 17.3 1.25 700 950 

9/8/2008 13:00 9/8/2008 16:00 PI_HY_87085 13.85 17.3 1.25 700 850 

9/9/2008 14:00 9/9/2008 17:23 PI_HY_87075 13.85 17.3 1.25 700 750 

9/11/2008 14:00 9/11/2008 17:03 PI_HY_97085b 10.1 20.2 2.00 700 850 

Because of the wide range of char particle sizes and the variety of mechanisms determining the 

size and shape of the particles, those particles captured in the char cyclones likely have a wide, 

unknown time history in the reactor. Changes in operating conditions also affect the particle 

history and the steady-state char level. Higher throughputs of gases and biomass (especially 

gases) will lower the steady-state level of char. When changing from a relatively low velocity to 

a higher velocity, the apparent char yield appears to increase due to the increased entrainment of 

char. Decreasing the gas rate has the opposite effect. The only method to determine the char 

yield directly from measurements of char versus time is waiting for the reactor to reach steadystate char level at each set of operating conditions. Depending on conditions, this can take up to 

several hours after each change. 

2.8 Solid Sample Analyses—Feed and Char Residues 

The proximate, ultimate, and elemental ash analyses for the oak and pine-grab samples are 

presented in Table 4. The proximate and ultimate analyses of the two wood feedstocks are very 

similar. The ash chemistry of oak and pine is also very similar with the exception of calcium and 

magnesium content. Oak ash has more calcium, and pine ash has more magnesium. Appendix A 

contains the proximate, ultimate, and elemental ash analyses for each of the char samples 

collected. 

To minimize the time averaging of the char sampling method, relatively small char samples were 

collected during each steady-state operating period. Typically, char removed from the process is 

collected in a plastic bag that lines a 113-L (30 gal) char drum. These bags can hold up to 17 kg 

of char that accumulates over time as about 500 g of char is blown down every 10 to 15 minutes. 

Steady-state conditions were usually designated once the gas compositions were stable and after 

a char blow-down event. During the steady-state sampling period, the char sample removed from 

the char pots was diverted to a one-gallon container and collected. This collection provided a 

representative sample of the char that escaped the gasifier during a relatively short time period. It 

should also be noted that because of char accumulation in the fluidized bed reactor, char captured 

by the cyclones at any given time could have evolved from biomass fed hours earlier. 

 14
 15

Table 4: Proximate, ultimate, and elemental ash analysis for oak and pine feed samples 

Oak Pine

Proximate Analysis (wt% as received) 

Moisture 5.81 7.55 

Ash 0.53 0.30 

Volatile Matter 79.05 79.86 

Fixed C 14.61 12.29 

HHV (Btu/lb) 7993 8263 

Ultimate Analysis (wt% as received) 

C 48.55 49.67 

H 5.11 6.11 

N 0.05 0.06 

O (by difference) 39.92 36.29 

S 0.03 0.02 

Cl 0.01 0.01 

Moisture 5.81 7.55 

Ash 0.53 0.30 

Elemental Ash Analysis (wt% of ash as oxide) 

SiO2 3.82 5.39 

Al2O3 0.91 1.54 

TiO2 0.04 0.06 

Fe2O3 0.71 2.02 

CaO 42.40 29.00 

MgO 2.02 10.50 

Na2O 0.43 0.39 

K2O 18.90 18.90 

P2O5 2.62 5.24 

SO3 2.63 3.26 

Cl 0.03 0.17 

CO2 24.47 21.27 
3 Experimental Results 

The parametric oak gasification experiments were conducted during November and December 

2007, and the parametric pine gasification experiments were conducted during August and 

September 2008. Prior to each set of experiments, the fluidized bed reactor was loaded with a 

fresh charge of olivine, and initial system check-out and preparation was performed. 

3.1 GC Gas Sampling Results 

Complete raw gas compositions are measured every four minutes, and data export continuously 

to a spreadsheet for data manipulation. Helium was added to the front end of the TCPDU as an 

internal standard to correct changes in gas-flow rate through the process. Nitrogen is added at 

several points in the process as a purge gas. For reporting purposes, all gas compositions 

measured with the GC are reported on a dry basis. The average gas compositions measured 

during each process condition during oak and pine gasification are presented in Table 5 and 

Table 6, respectively. Random conditions were performed twice to obtain replicates. These 

conditions have a “b” in the run ID. 

Table 5: Summary of dry, nitrogen-free gas composition for parametric oak tests 

Run ID 77075 77085 77085b 77095 87075 87085 87085b 87095 97075 97085 97085b 97095 97095b

S:B ratio 0.74 0.74 0.74 0.74 1.25 1.25 1.25 1.25 2.00 2.00 2.00 2.00 2.00 

TC Temp (°C) 750 850 850 950 750 850 850 950 750 850 850 950 950 

Gas (%vol.) 

H2 29.14 30.45 26.70 32.35 29.74 29.38 30.17 32.01 29.26 29.35 34.01 33.74 39.15 

CO 27.73 26.05 30.76 24.83 26.85 26.98 28.34 25.59 27.08 27.41 22.76 24.45 18.37 

CO2 21.30 21.55 19.52 21.57 21.50 20.33 20.55 20.31 20.51 19.81 22.30 19.93 23.45 

CH4 13.03 13.74 15.05 14.01 13.04 13.67 14.06 13.60 12.42 13.27 12.17 12.59 11.06 

He (tracer) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

C2H6 1.24 1.17 1.29 1.12 1.68 1.58 0.57 1.48 2.22 2.13 1.95 1.86 1.69 

C2H4 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

C2H2 3.03 3.61 4.05 2.29 3.03 3.63 3.75 2.12 3.11 3.69 3.09 2.12 1.66 

C3H8 1.47 0.59 0.56 0.09 1.31 0.50 0.50 0.06 1.17 0.46 0.40 0.01 0.03 

C3H6 0.14 0.33 0.41 1.12 0.15 0.41 0.42 1.22 0.19 0.48 0.39 1.25 0.99 

1-C4H8 0.54 0.08 0.10 0.01 0.45 0.08 0.08 0.00 0.47 0.10 0.07 0.00 0.00 

2-cis-C4H8 0.25 0.07 0.06 0.03 0.21 0.06 0.06 0.04 0.19 0.04 0.04 0.00 0.00 

2-trans-C4H8 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

COS (ppmv) 0 0 0 0 0 0 0 0 0 0 0 0 0 

H2S (ppmv) 0 48 54 51 0 52 51 51 0 59 48 58 40 

Closure (%) 97.9 97.7 98.5 97.5 98.0 96.6 98.5 96.4 96.9 96.8 97.2 96.0 96.4 

H2:CO ratio 1.1 1.2 0.9 1.3 1.1 1.1 1.1 1.3 1.1 1.1 1.5 1.4 2.1 

In general, higher steam-to-biomass ratio and higher thermal cracker temperature yields a higher 

hydrogen concentration. The hydrogen concentration ranged from 26%–39% for oak and 35%–

42% for pine gasification. The carbon monoxide concentration ranged from 18%–31% for oak 

and 15%–23% for pine. The H2-CO ratio for oak varied between 0.9 and 2.1 with an average of 

1.2. The H2-CO ratio for pine varied between 1.5 and 2.7 with an average of 2.0. The carbon 

dioxide concentration ranged from 19%–23% for oak and 21%–25% for pine. The water-gas 

shift catalyst requires sulfur to maintain activity so the H2S concentration in the syngas is also 

16 
important. For oak, the H2S concentration was 40–60 ppmv. For pine, the H2S concentration was 

20–30 ppmv. These concentrations were observed when the thermal cracker temperature was 

either 850°C (1562°F) or 950°C (1742°F). At a thermal cracker temperature of 750°C (1382°F), 

the H2S concentration was 0 ppmv because the sulfur remains bound with tar and char at lower 

temperatures. 

Table 6: Summary of dry, nitrogen-free gas composition for parametric pine tests 

Run ID 77075 77085 77095 87075 87085 87095 97075 97085 97085b 97095 

S:B ratio 0.81 0.81 0.81 1.25 1.25 1.25 2.00 2.00 2.00 2.00 

TC Temp (°C) 750 850 950 750 850 950 750 850 850 950 

Gas (%vol.) 

H2 35.59 35.49 37.87 39.08 39.94 40.53 35.29 35.18 42.11 37.53 

CO 18.93 17.95 20.45 17.68 16.40 17.69 23.44 20.58 15.34 19.94 

CO2 24.26 23.90 23.35 24.13 24.74 23.57 22.10 21.49 24.98 20.80 

CH4 12.09 12.80 15.04 10.12 10.87 11.39 13.29 12.30 9.80 12.29 

He (tracer) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

C2H6 0.88 0.82 0.74 0.97 0.88 0.82 1.63 1.55 1.17 1.40 

C2H4 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

C2H2 2.92 3.72 0.07 2.41 3.02 0.05 3.06 0.49 2.71 2.05 

C3H8 1.51 0.63 0.00 1.13 0.53 0.00 1.18 0.02 0.44 0.05 

C3H6 0.12 0.34 1.03 0.12 0.13 0.00 0.18 0.45 0.28 1.34 

1-C4H8 0.56 0.10 0.00 0.40 0.07 0.56 0.46 0.10 0.06 0.00 

2-cis-C4H8 0.24 0.06 0.03 0.17 0.00 0.00 0.06 0.00 0.00 0.00 

2-trans-C4H8 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

COS (ppmv) 0 0 0 0 0 0 0 0 0 0 

H2S (ppmv) 0 31 30 0 23 25 0 26 20 20 

Closure (%) 97.1 95.8 98.6 96.2 96.6 94.6 101.5 92.2 96.9 95.4 

H2:CO ratio 1.9 2.0 1.9 2.2 2.4 2.3 1.5 1.7 2.7 1.9 

3.2 Mass Spectral Results—Tar Concentrations 

3.2.1 Raw Syngas 

The raw gas from indirect oak and pine gasification contained the familiar slate of tar 

compounds typically observed. Figure 6 shows a series of time-averaged mass spectra taken 

during the 97075, 97085, and 97095 steady-state conditions for pine gasification, showing the 

effect of thermal cracker temperature on the product slate. Predominant peaks in all three plots 

include methane (m/z=16), benzene (m/z=78) and naphthalene (m/z=128). Other peaks observed 

in the spectra, typical of those encountered in previous biomass gasification studies, are 

identified in the inset of the figure, and Table 7 gives a list of tar compounds with their 

molecular formulas. As expected for these conditions, the spectrum is comprised largely of 

tertiary tar compounds, characterized by the polycyclic, aromatic hydrocarbon series of peaks, 

along with some alkylated, aromatic derivatives (e.g., toluene, indene, methylnaphthalenes) and 

secondary tars (e.g., phenolics). Notable omissions from the spectrum include water (m/z=18), 

carbon monoxide/N2 (m/z=28), and carbon dioxide (m/z=44), which were not scanned to avoid 

saturating the detector. 

 17
Table 7: Molecular weight and identification of common hydrocarbons detected in corn stover 

gasification product gases with the TMBMS 

Molecular Weight Formula Chemical Name(s)

15,16 CH4 methane 

26 C2H2 acetylene 

78 C6H6 benzene 

91,92 C7H8 toluene 

94 C6H6O phenol 

104 C8H8 styrene 

106 C8H10 (m-, o-, p-) xylene 

108 C7H8O (m-, o-, p-) cresol 

116 C9H8 indene 

118 C9H10 indan 

128 C10H8 naphthalene 

142 C11H10 (1-, 2-) methylnaphthalene 

152 C12H8 acenapthylene 

154 C12H10 acenaphthene 

166 C13H10 fluorene 

178 C14H10 anthracene, phenanthrene 

192 C15H12 (methyl-) anthracenes/phenanthrenes 

202 C16H10 pyrene/fluoranthene 

216 C17H12 methylpyrenes/benzofluorenes 

228 C18H12 chrysene, benz[a]anthracene, ... 

242 C19H14 methylchrysenes, methylbenz[a]anthracenes 

252 C20H12 perylene, benzo[a]pyrene, 

266 C21H14 dibenz[a,kl]anthracene, 

278 C22H14 dibenz[a,h]anthracene, 

302 C24H14 dibenzochrysenes, etc. 

352 C28H16 dibenzoperylenes, etc. 

At these process conditions, the raw gas spectra from the two feedstocks were qualitatively very 

similar. As seen in Figure 6, an increase in the severity of thermal cracking resulted in a decrease 

of secondary tar species as the methyl and hydroxyl groups characteristic of secondary tar 

species were cleaved from the aromatic structures. Table 8 shows the tar concentrations in the 

raw oak- and pine-derived product gas, as measured by the TMBMS for the six quantified 

species. Also included are estimations of “other tars” and “heavy tars.” These quantities were 

derived by applying the response factors for naphthalene and phenanthrene to the mass spectral 

summations m/z 80–176 (“other tars”) and m/z 180–400 (“heavy tars”), respectively. These 

values are typical of those measured during previous studies under the same conditions. 

Table 8 indicates that oak gasification yielded somewhat more tar than the pine gasification. This 

difference is consistent with the GC results that show a noticeable increase of methane and other 

hydrocarbons during oak gasification. Tar concentration data from all parametric conditions are 

tabulated in Appendix C. 

 18
Signal Intensity (% of m/z 16)

20

40

60

80

100 16-methane 26-acetylene

78-benzene

128

91,92

178

100 150 200 250 300 350

0

5

10

15

20

25 91,92 - toluene

94 - phenol

104 - styrene

108 - cresols

116 - indene

128 - naphthalene

142 - methylnaphthalenes

152 - acenaphthalene

166 - flourene

178 - anthracene/phenanth.

192 - methylanth./phenanth...

202 - pyrene/flouranthene

216 - benzo(a)flourene, etc.

228 - chrysene, etc.

242 - methylchrysenes, etc.

252 - perylene, etc

266 - dibenz[a,kl]anthracene...

278 - dibenz[a,h]anthracene...

302 - dibenzochrysenes, etc.

352 - dibenzoperylenes, etc.

94

108

116

128

142

152 166

178

192

202

228 242

252

266

278

216

91/

92

302 352

94

40-argon

(tracer)

Signal Intensity (% of m/z 16)

20

40

60

80

100 16-methane 26-acetylene

78-benzene

128

91,92 178

100 150 200 250 300 350

0

5

10

15

20

25

30

94

104

116

128

142

152

166

178

192

202

228242 252

266

278

216

91/

92

302 352

94

40-argon

(tracer)

m/z

0 50 100 150 200 250 300 350 400

Signal Intensity (% of m/z 16)

20

40

60

80

100 16-methane 26-acetylene

78-benzene

128

91,92

178

100 150 200 250 300 350

0

10

20

30

40

50

104

116

128

152

166

178

202

228 252

278 91/

92 302 352

40-argon

(tracer)

750oC

850o

C

950o

C

Figure 6: Time-averaged pine gasification mass spectra collected during steady-state conditions 

97075, 97085, and 97095 corresponding to thermal cracker temperatures of 750°C, 850°C, and 

950°C, respectively. Steam:biomass = 2:1, 8" fluidized bed = 700°C 

 19
Table 8: Comparison of tar concentrations in raw oak- and pine-derived syngas for quantified 

species representative of conditions established for 97085 

Species m/z Tar Concentrations (mg/Nm3 - wet basis) 

oak pine 

Benzene 78 4860 4690 

Toluene 92 1510 1540 

Phenol 94 690 1090 

Cresol 108 100 100 

Naphthalene 128 1250 1310 

Phenanthrene 178 390 570 

“other tar”(a) 80-176 2900 3190 

“heavy tar”(b) 180-400 2930 3590 

Total (>m/z 78) 9770 11380 

(a)Summation of mass spectral peak intensities (m/z 80–176)—response for naphthalene used, (b)Summation of mass 

spectral peak intensities (m/z 180–400)—response for phenanthrene used 

3.2.2 Reformed and Scrubbed Syngas 

For the shift experiments, the raw syngas was first catalytically reformed to convert the tar 

contaminants into additional H2 and CO. The reformed gas was then quenched with cold 

dodecane in the scrubbing system as an additional cleaning step before being fed into the shift 

reactor. Post-reformer syngas monitoring with the TMBMS was conducted during this portion of 

the test, including monitoring of the dry, quenched gas. Figure 7 shows a mass spectral 

comparison of the raw, reformed, and scrubbed syngas sampled during condition 97085. The 

TMBMS samples the gas “as is,” including any steam. Compared to the first two plots, the mass 

spectral components in the “post-quench” plot of Figure 7 therefore appear enhanced (by roughly 

a factor of two) due to the removal of steam from the sampled gas. As seen in Figure 7, some 

components remained in the dry gas after scrubbing—notably, toluene (m/z 91,92), styrene (m/z 

104), indene (m/z 116), and naphthalene (m/z 128). All of these species, except naphthalene, 

appear to have increased, an indication that there may be some holdup of these components in 

the scrubbing system. Also of note is the appearance of a trace dodecane peak at m/z 170, 

indicating that some of the quench liquid carried over as vapor from the scrubbing system. 

Table 9 summarizes the quantified species observed in the raw, reformed, and scrubbed gas 

during a shift experiment. 

 20
20

40

60

80

100 16-methane 26-acetylene

78-benzene

128

91,92

178

0

5

10

15

20

25 91,92 - toluene

94 - phenol

104 - styrene

108 - cresols

116 - indene

128 - naphthalene

142 - methylnaphthalenes

152 - acenaphthalene

166 - flourene

178 - anthracene/phenanth.

192 - methylanth./phenanth...

202 - pyrene/flouranthene

216 - benzo(a)flourene, etc.

228 - chrysene, etc.

242 - methylchrysenes, etc.

252 - perylene, etc

266 - dibenz[a,kl]anthracene...

278 - dibenz[a,h]anthracene...

302 - dibenzochrysenes, etc.

352 - dibenzoperylenes, etc.

Signal Intensity (% of m/z 16)

100 150 200 250 300 350

94

116

128

142

152

166

178

192

202

228

242

252

266

278

216

91/

92

302 352

94

Signal Intensity (% of m/z 16)

20

40

60

80

100 16-methane

78-benzene

128

178

0

5

10

15

20

25

100 150 200 250 300 350

128

152 166

178

202 252

91/

92

m/z

0 50 100 150 200 250 300 350 400

Signal Intensity (% of m/z 16)

20

40

60

80

100 16-methane

78-benzene

91,92

178

0

5

10

15

20

25

100 150 200 250 300 350

104 116

91/

92

reformer

inlet

reformer

outlet

post-quench

170-dodecane

Figure 7: Time-averaged mass spectra showing components of raw, reformed, and scrubbed 

syngas during steady-state condition PI_HY_97850 

 21
Table 9: Average concentrations (mg/Nm3

-dry basis) of pine-derived tars in raw, reformed, and 

scrubbed gas 

Species m/z Tar Concentrations (mg/Nm3 – dry basis) 

Raw gas Reformed gas Scrubbed gas 

Benzene 78 11170 7880 11720 

Toluene 92 3650 230 1770 

Phenol 94 2200 60 30 

Cresol 108 180 – – 

Naphthalene 128 2980 1090 110 

Phenanthrene 178 1240 230 – 

“other tar”(a) 80-176 6300 240 530 

“heavy tar”(b) 180-400 6270 120 – 

Total (>m/z 78) 22830 1960 2430 

(a)Summation of mass spectral peak intensities (m/z 80–176)—response for naphthalene used, (b)Summation of mass 

spectral peak intensities (m/z 180–400)—response for phenanthrene used 

3.3 Shift Catalyst Performance 

Bottled gas was first used to test the performance of the high-temperature, water-gas shift 

catalyst. Table 10 shows the results of the bottled-gas test using an H2-CO ratio of 1.0. The inlet 

gas composition was about 48% CO and 48% H2 on a nitrogen-free basis. There was no CO2 or 

CH4 added in this test to try to maximize CO conversion. The highest CO conversion, 91%, was 

achieved using a reaction temperature of 450°C (842°F) and a gas hourly space velocity (GHSV) 

of 21,000. A higher steam flow rate also increases the CO conversion. When the H2O-H2 ratio 

was increased from 4.4 to 5.6, the CO conversion increased from 31% to 37%. The most 

important parameters are temperature and space velocity. 

Table 11 shows the results of the bottled-gas test using an H2-CO ratio of 4.2, which is more 

representative of the syngas produced in the TCPDU when the steam reformer is on-line. Carbon 

dioxide was also added at a concentration of 27%. Methane is also a major syngas component 

but was unavailable for this test. Similar to the previous test, the highest CO conversion, 74%, 

was obtained using a temperature of 450°C (842°F) and a GHSV of 21,000. 

 22
Table 10: Bottled-gas test results using an H2-CO ratio of 1.0, no CO2

Temp (C) GHSV 

H2S 

(ppmv) H2O:H2 H2O:CO

CO 

(vol. 

%) 

H2

(vol. 

%) 

CO2

(vol. 

%) 

CH4

(vol. 

%) CO conv H2/CO

reactor inlet composition 48.3 47.8 0.0 0 - 1.0 

300 39200 100 4.4 4.4 42.6 49.8 4.5 0 11.7% 1.2 

350 39200 100 4.4 4.4 33.3 52.6 10.3 0 31.1% 1.6 

350 45200 100 5.6 5.6 30.2 53.8 12.0 0 37.4% 1.8 

400 45200 100 5.6 5.6 20.4 57.1 18.5 0 57.7% 2.8 

450 45200 100 5.6 5.6 16.1 59.2 21.9 0 66.7% 3.7 

450 45200 300 5.6 5.6 18.5 58.7 20.3 0 61.6% 3.2 

450 21500 300 7.5 7.5 4.0 63.6 29.6 0 91.7% 15.9 

Table 11: Bottled-gas test results using an H2-CO ratio of 4.2, 27 vol% CO2

Temp (C) GHSV 

H2S 

(ppmv) H2O:H2 H2O:CO

CO 

(vol. 

%) 

H2

(vol. 

%) 

CO2

(vol. 

%) 

CH4

(vol. 

%) CO conv H2/CO

reactor inlet composition 13.4 55.8 27.3 0 - 4.2 

300 20800 200 5.1 21.5 10.5 57.5 28.7 0 21.6% 5.5 

350 20800 200 5.1 21.5 7.9 58.0 30.5 0 41.1% 7.3 

400 20800 200 5.1 21.5 5.4 59.0 32.2 0 59.4% 10.9 

450 20800 200 5.1 21.5 3.5 59.8 33.3 0 74.0% 17.1 

450 41600 200 5.1 21.5 6.6 58.7 31.3 0 50.9% 8.9 

The bottled-gas test showed that high-temperature, high steam-to-syngas ratio, and low space 

velocity increased the CO conversion. Table 12 shows the results from the shift catalyst tests 

using biomass-derived syngas generated by the TCPDU. For this test, the TCPDU was operated 

using a high steam-to-biomass ratio (2.0) and middle thermal cracker temperature (850°C). In 

addition, the FSR was brought on-line to reform methane and tars to increase the H2 yield. 

Similar to the bottled-gas tests, maximum CO conversion was obtained at 450°C (842°F) and a 

GHSV of 20,000. The reaction temperature was increased from 300°C (572°F) to 450°C (842°F) 

and held for six hours. Initially, the CO conversion was 68% and decreased to 65% after six 

hours. The initial CO conversion during the actual syngas test (68%) is close to the CO 

conversion obtained during the bottled syngas test (74%). After the six-hour test, the steam flow 

reduced, and CO conversion remained relatively high at 61%. 

 23
Table 12: TCPDU-gas test results with an H2-CO ratio of 4.2 using pine feedstock 

Temp (C) GHSV 

H2S 

(ppmv) H2O:H2 H2O:CO

CO 

(vol. 

%) 

H2

(vol. 

%) 

CO2

(vol. 

%) 

CH4

(vol. 

%) CO conv H2/CO

reactor inlet composition 12.2 50.9 26.0 7.3 - 4.2 

300 20000 200 4.8 20.4 10.2 52.4 27.5 7.3 16.6% 5.1 

350 20000 200 4.8 20.4 8.7 53.1 28.4 7.3 28.2% 6.1 

400 20000 200 4.8 20.4 6.6 53.8 30.0 7.0 46.1% 8.2 

450 20000 200 4.8 20.4 3.9 54.8 31.7 7.0 

68.2% at 0 

hr 14.1 

450 20000 200 4.8 20.4 4.1 54.7 31.7 7.0 

66.2% at 3 

hr 13.3 

450 20000 200 4.8 20.4 4.2 54.6 31.6 7.0 

65.1% at 6 

hr 13.0 

450 14700 200 2.9 12.2 4.7 54.2 31.4 7.0 61.1% 11.5 

3.4 Material and Element Balances 

Overall mass closures of 94% ± 4% (mean ± standard deviation) were achieved during the 

parametric oak gasification studies and 93% ± 4% for pine gasification. Overall closure was 

obtained by accurately measuring all solid-, vapor-, and gas-phase inputs and combining the 

analytical measurements of gas composition, char yields, and liquid accumulation rates to 

determine the outputs. Appendix B contains the overall and elemental balance for each 

condition. Carbon balances were 89% ± 8% for oak and 96% ± 9% for pine gasification. The 

hydrogen balances were 103% ± 3% for oak and 102% ± 3% for pine gasification. The oxygen 

balances were 102% ± 3% for oak and 105% ± 4% for pine gasification. 

The char accumulation in the fluidized bed and actual char yields are difficult to measure directly 

because steam-to-biomass ratio changes on a regular basis. The weight of the solids collected in 

the cyclones is measured in semi-continuous batches and includes oak or pine char and any bed 

material (olivine) carried over out of the reactor. A true char yield can be established if a steadystate accumulation of char in the reactor has been reached and the bed conditions are stable so 

the bed material carryover is constant. The level of char in the reactor reaches steady-state only 

for a given condition after at least several hours. Process upsets and changes in biomass feed rate 

or steam rate can all impact the char accumulation rate or the level of char in the reactor. 

 24
4 Conclusions 

Parametric gasification tests were performed in NREL’s TCPDU using oak and pine feedstocks. 

The parameters of interest were steam-to-biomass ratio and thermal cracker temperature. 

Generally, a higher steam-to-biomass ratio and a higher thermal cracker temperature increased 

H2 production. Oak gasification yielded slightly more tar than pine gasification, which is 

consistent with GC results that show an increase of methane and other hydrocarbons during oak 

gasification. A slipstream fixed bed reactor was used to house a water-gas shift catalyst to 

increase H2 production further. Bottled syngas tests yielded CO conversion of 74% at a reaction 

temperature of 450°C, an H2O-H2 ratio of five, and GHSV of 20,000. Pine-derived syngas using 

a high steam-to-biomass ratio (2.0), middle thermal cracker temperature (850°C), and full-stream 

reforming yielded an initial CO conversion of 68% using the same shift-reactor conditions for 

the bottled syngas test above. CO conversion decreased to 65% after six hours of testing the shift 

catalyst on pine-derived syngas. The shift catalyst was not tested with oak-derived syngas. 

25 
References 

1. Feldman, H.F.; Paisley, M.A.; Applebaum, H.R.; and Taylor, D.R. "Conversion of Forest 

Residues to a Methane-Rich Gas in a High-Throughput Gasifier." PNL-6570/DE88-013138. 

Battelle Columbus Laboratory for Pacific Northwest Laboratory, 1988. 

2. Wyman, C.E., Bain, R.L.; Hinman, N.D.; and Stevens, D.J. "Ethanol and Methanol from 

Cellulosic Materials," Chapter 21. T.B. Johansson, ed. Renewable Energy: Sources for Fuels 

and Electricity. Washington, D.C.: Island Press, 1993. 

3. Hamelinck, C.N.; Faaji, A.P.C. Future Prospects for Production of Methanol and Hydrogen 

from Biomass. NWS-E-2001-49. Utrecht, the Netherlands: Utrecht University, 2001. 

4. Spath, P.; Aden, A.; Eggeman, T.; Ringer, M.; Wallace, B.; Jechura, J. Biomass to Hydrogen 

Production Detailed Design and Economics Utilizing the Batelle Columbus Laboratory 

Indirectly-Heated Gasifier. NREL/TP-510-37408. Golden, CO: National Renewable Energy 

Laboratory, 2005. 

5. Sapp, J. Vermont Gasifier Project: Final Report Phase 1. DOE/GO/10032-T1. National 

Energy Production Corporation, 1995. 

6. Spath, P.; Dayton, D.C. Preliminary Screening: Technical and Economic Assessment of 

Synthesis Gas to Fuels and Chemicals with Emphasis of the Potential for Biomass-Derived 

Syngas. NREL/TP-510-34929. Golden, CO: National Renewable Energy Laboratory, 2003. 

7. NOVEM. Unit Operations—Biomass Gasification. 2DEN-02.20. Utrecht, the Netherlands: 

Netherlands Agency for Energy and the Environment, 2002. 

8. Twigg, M.V. The Catalyst Handbook. 2nd ed. London: Manson Publishing, 1996. 

9. Brown, R.C.; Smeenk, J.; Sadaka, S.; Norton, G.; Zhang, R.; Suby, A.; Cummer, K.; Ritzert, 

J.; Xu, M.; Lysenko, S.; Nunez, J.; Brown, N. Biomass-Derived Hydrogen from a Thermally 

Ballasted Gasifier. DE-FC36-01GO11091. Ames, IA: Iowa State University, 2006. 

10. Haryanto, A.; Fernando, S.D.; Adhikari, S. "Catalytic Biomass Gasification to Produce 

Sustainable Hydrogen" American Society of Agricultural and Biological Engineers Annual 

International Meeting. Portland, OR, 2006. 

11. Carpenter, D.L.; Deutch, S.P.; French, R.J. "Quantitative Measurement of Biomass Gasifier 

Tars Using a Molecular-Beam Mass Spectrometer: Comparison with Traditional Impinger 

Sampling." Energy & Fuels; Vol. 21, 2007; pp. 3036–3043. 

26 
Appendix A—Char Analysis 

Table 13: Char analysis for oak samples 

Sample ID OK_77075 OK_77085 OK_77085b OK_77095 OK_87075 OK_87085

Sample Date Taken 11/29/07 11/29/07 12/14/07 11/30/07 12/13/07 12/12/07

Sample Date 

Received 12/3/07 12/3/07 12/20/07 12/3/07 12/20/07 12/20/07

Sample Date Report 12/21/07 12/21/07 1/11/08 12/21/07 1/11/08 1/11/08

Loss on drying, % 0.64 0.33 0.38 0.17 0.7 0.51

Carbon, % 83.94 69.41 84.86 77.76 83.54 83.47

Hydrogen, % 1.43 0.99 1.29 1.04 1.24 1.2

Nitrogen, % 0.33 0.29 0.09 0.35 0.08 0.07

Oxygen, % (by diff) 0 0 4.33 0 4.41 0.86

Sulfur, % 0 0 0.01 0.01 0.02 0.01

Chlorine, % 0.009 0.005 0 0.005 0 0

Ash, % 14.83 30 9.04 22.44 10.1 10.88

Volatile matter, % 5.93 4.2 8.56 5.08 5.66 4.88

Fixed carbon, % 78.6 65.47 82.02 72.31 83.63 83.73

HHV, Btu/lb 12773 10394 13137 11646 12876 12790

Ash Al, % 0.96 0.87 0.49 1.01 0.45 0.51

Ash Ca, % 16.4 5.49 27.5 7.98 22.3 21

Ash Fe, % 6.36 7.92 4.36 7.34 5.36 5.35

Ash Mg, % 32.5 44.9 21.8 40.8 30.6 29.2

Ash P, % 1.04 0.39 1.64 0.57 1.3 1.29

Ash K, % 6.38 2.39 11.3 3.76 9.16 8.78

Ash Si, % 30.38 38.39 22.26 35.8 27.52 27.38

Ash Na, % 0.28 0.11 0.48 0.12 0.42 0.24

Ash S, % 0.38 0.18 0.52 0.07 0.57 0.43

Ash Ti, % 0.04 0.04 0.04 0.04 0.00 0.04

Ash Cl, % 0.03 0.01 0.00 0.04 0.00 0.00

Ash CO2, % 4.17 1.15 6.45 3.03 5.31 5.67

Ash fusion temps,°F (those reported as 2700 are actually >2700) 

Initial- O* 2555 2700 2512 2700 2609 2567

Softening- O* 2579 2700 2236 2700 2610 2609

Hemispherical- O* 2583 2700 2557 2700 2611 2618

Fluid- O* 2600 2700 2700 2700 2612 2686

Initial- R** 2674 2700 2595 2700 2600 2627

Softening- R** 2700 2700 2616 2700 2618 2689

Hemispherical- R** 2700 2700 2636 2700 2656 2700

Fluid- R** 2700 2700 2680 2700 2700 2700

*in an oxidizing atmosphere 

**in a reducing atmosphere 

27 
Table 13: Char analysis for oak samples cont. 

Sample ID OK_87085b OK_87095 OK_97075 OK_97085 OK_97085b OK_97095

Sample Date Taken 12/18/07 12/12/07 11/28/07 11/28/07 12/17/07 11/20/07

Sample Date 

Received 12/20/07 12/20/07 12/3/07 12/3/07 12/20/07 12/3/07

Sample Date Report 1/11/08 1/11/08 12/21/07 12/21/07 1/11/08 12/21/07

Loss on drying, % 0.47 0.65 0.67 0.31 0.97 0.48

Carbon, % 86.66 86.35 70.82 71.36 88.64 54.48

Hydrogen, % 1.26 1.04 1.12 1.11 1.17 0.68

Nitrogen, % 0.08 0.19 0.3 0.3 0.21 0.25

Oxygen, % (by diff) 4.38 2.32 0 0 0.87 0

Sulfur, % 0.02 0.01 0.05 0.03 0.02 0.03

Chlorine, % 0 0 0.005 0.005 0 0.005

Ash, % 7.13 9.44 28.41 30.28 8.12 45.04

Volatile matter, % 8.46 7.26 4.24 4.32 7.95 3.1

Fixed carbon, % 83.94 82.65 66.68 65.09 82.96 51.38

HHV, Btu/lb 13534 13089 10634 10353 13212 8205

Ash Al, % 0.22 0.57 0.92 0.97 0.49 1.26

Ash Ca, % 30.2 26.6 6.05 6.65 24.2 3.44

Ash Fe, % 3.65 4.47 7.66 7.59 4.34 7.89

Ash Mg, % 18.3 22.2 43.5 42.7 23 45

Ash P, % 1.88 1.58 0.42 0.41 1.5 0.26

Ash K, % 13.4 11.3 2.45 2.61 10.7 1.47

Ash Si, % 19.17 23.04 38.3 38.1 23.42 40.01

Ash Na, % 0.42 2.26 0.15 0.11 0.26 0.09

Ash S, % 0.53 0.38 0.25 0.13 0.31 0.15

Ash Ti, % 0.04 0.04 0.00 0.00 0.04 0.00

Ash Cl, % 0.05 0.01 0.00 0.02 0.02 0.02

Ash CO2, % 13.87 10.29 1.13 1.76 15.04 1.84

Ash fusion temps,°F (those reported as 2700 are actually >2700) 

Initial- O* 2700 2500 2700 2700 2500 2700

Softening- O* 2700 2511 2700 2700 2517 2700

Hemispherical- O* 2700 2519 2700 2700 2536 2700

Fluid- O* 2700 2525 2700 2700 2547 2700

Initial- R** 2700 2608 2700 2700 2629 2700

Softening- R** 2700 2618 2700 2700 2634 2700

Hemispherical- R** 2700 2621 2700 2700 2640 2700

Fluid- R** 2700 2624 2700 2700 2644 2700

*in an oxidizing atmosphere 

**in a reducing atmosphere 

28 
Table 14: Char analysis for pine samples 

Sample ID PI_77075 PI_77085 PI_77095 PI_87075 PI_87085 

Sample Date Taken 9/2/08 9/3/08 9/4/08 9/9/08 9/8/08 

Sample Date 

Received 9/10/08 9/10/08 9/10/08 9/19/08 9/19/08 

Sample Date Report 9/17/08 9/17/08 9/17/08 10/1/08 10/1/08 

Loss on drying, % 0.99 1.08 1.16 0.6 0.51 

Carbon, % 81.63 67.54 74.08 82.53 81.53 

Hydrogen, % 1.07 0.53 0.62 1.15 1.1 

Nitrogen, % 0.14 0.1 0.14 0.1 0.1 

Oxygen, % (by diff) 0.35 0.88 0.15 0.06 0.01 

Sulfur, % 0.01 0.01 0.01 0.01 0.01 

Chlorine, % 0.01 0.01 0.01 0.02 0.03 

Ash, % 15.82 29.87 23.85 15.56 16.88 

Volatile matter, % 5 3.7 3.01 3.27 4.35 

Fixed carbon, % 78.19 65.35 71.98 80.57 78.26 

HHV, Btu/lb 12484 10244 11055 12767 12305 

Ash Al, % 2.05 1.09 0.96 0.85 0.94 

Ash Ca, % 6.63 3.4 5.14 7.03 4.69 

Ash Fe, % 7.17 7.96 7.49 6.81 7.31 

Ash Mg, % 40.4 47.7 45.5 38.8 41.6 

Ash P, % 1.01 0.43 0.8 1.27 0.85 

Ash K, % 3.83 1.6 3 4.39 3.08 

Ash Si, % 37 41.31 38.12 33.52 36.62 

Ash Na, % 0.15 0.07 0.15 0.14 0.04 

Ash S, % 0.12 0.08 0.14 0.3 0.14 

Ash Ti, % 0.18 0.04 0.05 0.01 0.04 

Ash Cl, % 0.04 0.01 0.05 0.01 0.01 

Ash CO2, % 1.97 0.72 1.88 5.33 3.99 

Ash fusion temps,°F (those reported as 2700 are actually >2700) 

Initial- O* 2700 2700 2700 2505 2700 

Softening- O* 2700 2700 2700 2519 2700 

Hemispherical- O* 2700 2700 2700 2531 2700 

Fluid- O* 2700 2700 2700 2549 2700 

Initial- R** 2700 2700 2700 2700 2700 

Softening- R** 2700 2700 2700 2700 2700 

Hemispherical- R** 2700 2700 2700 2700 2700 

Fluid- R** 2700 2700 2700 2700 2700 

*in an oxidizing atmosphere 

**in a reducing atmosphere 

29 
Table 14: Char analysis for pine samples cont. 

Sample ID PI_87095 PI_97075 PI_97085 PI_97085b PI_97095

Sample Date Taken 9/5/08 8/28/08 8/27/08 9/11/08 8/25/08

Sample Date 

Received 9/19/08 9/10/08 9/10/08 9/19/08 9/10/08

Sample Date Report 10/1/08 9/17/08 9/17/08 10/1/08 9/17/08

Loss on drying, % 0.42 0.99 0.92 1 0.94

Carbon, % 76.44 75.17 71.16 88.67 71.37

Hydrogen, % 1.01 0.92 0.78 1.29 0.68

Nitrogen, % 0.06 0.13 0.17 0.01 0.18

Oxygen, % (by diff) 0.01 0.01 0.01 0.38 0.74

Sulfur, % 0.01 0.01 0.01 0.01 0.01

Chlorine, % 0.03 0.01 0.02 0.03 0.01

Ash, % 22.06 22.84 27.26 8.65 26.09

Volatile matter, % 3.67 4.4 5.32 4.09 4.56

Fixed carbon, % 73.85 71.77 66.5 86.26 68.41

HHV, Btu/lb 11443 11364 10789 13470 10798

Ash Al, % 1.02 2.82 9.92 1.08 15.52

Ash Ca, % 4.09 3.08 5.21 12.7 4.18

Ash Fe, % 7.47 7.4 5.38 5.6 4.39

Ash Mg, % 42.8 43.4 30.4 31.6 24.5

Ash P, % 0.74 0.4 0.56 2.28 0.67

Ash K, % 2.7 1.48 1.83 8.49 1.01

Ash Si, % 37.19 38.95 29.4 26.67 27.32

Ash Na, % 0.03 0.07 0.14 0.18 0.06

Ash S, % 0.13 0.07 0.11 0.64 0.11

Ash Ti, % 0.04 0.18 0.68 0.01 0.45

Ash Cl, % 0.01 0.06 0.07 0.01 0.08

Ash CO2, % 3.56 1.36 3.15 8.43 0.49

Ash fusion temps,°F (those reported as 2700 are actually >2700) 

Initial- O* 2700 2700 2700 2611 2700

Softening- O* 2700 2700 2700 2689 2700

Hemispherical- O* 2700 2700 2700 2700 2700

Fluid- O* 2700 2700 2700 2700 2700

Initial- R** 2700 2700 2673 2645 2660

Softening- R** 2700 2700 2678 2649 2694

Hemispherical- R** 2700 2700 2680 2651 2700

Fluid- R** 2700 2700 2682 2657 2700

*in an oxidizing atmosphere 

**in a reducing atmosphere 

30 
Appendix B—Mass Balances 

Table 15: Mass balances for oak gasification conditions 

 OK_HY_77075 OK_HY_77085 OK_HY_77085b 

 

Mass 

In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass 

In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Mass Out/ 

Mass In, 

% 

Mass 

In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Closure 32.5 29.1 89.7% 32.5 30.8 94.8% 32.5 28.5 87.7%

Ash 0.10 0.09 90.5% 0.10 0.57 577.1% 0.10 0.05 53.4%

C 9.05 6.85 75.7% 9.05 7.87 87.0% 9.04 7.05 78.0%

H 2.50 2.58 103.5% 2.50 2.65 106.1% 2.50 2.54 101.7%

O 19.69 20.5 104.1% 19.69 20.6 104.7% 19.69 19.8 100.7%

N 0.009 0.002 21.3% 0.009 0.006 59.1% 0.009 0.001 5.6%

S 0.006 0.000 1.2% 0.006 0.003 45.8% 0.006 0.002 40.9%

Hx 0.001 0.000 5.8% 0.001 0.000 10.2% 0.001 0.000 0.0%

Ash_Al 0.001 0.001 95.5% 0.001 0.005 551.7% 0.001 0.000 28.7%

Ash_Ca 0.042 0.015 35.0% 0.042 0.031 74.7% 0.042 0.014 34.6%

Ash_Fe 0.001 0.006 810.6% 0.001 0.045 6437.3% 0.001 0.002 327.6%

Ash_Mg 0.002 0.029 1455.9% 0.002 0.256 12827.2% 0.002 0.011 575.8%

Ash_P 0.003 0.001 35.9% 0.003 0.002 85.9% 0.003 0.001 33.4%

Ash_K 0.019 0.006 30.5% 0.019 0.014 73.0% 0.019 0.006 31.9%

Ash_Si 0.004 0.027 719.6% 0.004 0.219 5799.5% 0.004 0.012 310.9%

Ash_Na 0.000 0.000 58.9% 0.000 0.001 147.6% 0.000 0.000 59.6%

Ash_S 0.003 0.000 13.1% 0.003 0.001 39.5% 0.003 0.000 10.5%

Ash_Hx 0.000 0.000 90.5% 0.000 0.000 192.4% 0.000 0.000 0.0%

Ash_CO2 0.024 0.004 15.4% 0.024 0.007 27.1% 0.024 0.003 14.1%

31 
Table 15: Mass balances for oak gasification conditions cont. 

 OK_HY_77095 OK_HY_87075 OK_HY_87085 

 

Mass 

In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Mass 

In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Mass In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Closure 32.4 29.2 90.0% 31.2 28.2 90.3% 31.3 29.7 94.9%

Ash 0.10 0.52 529.1% 0.07 0.10 141.2% 0.07 0.11 147.3%

C 9.02 8.56 94.9% 6.74 5.60 83.0% 6.76 5.81 86.0%

H 2.49 2.49 99.7% 2.65 2.61 98.5% 2.65 2.77 104.8%

O 19.67 18.8 95.7% 20.91 20.6 98.4% 20.92 21.6 103.4%

N 0.009 0.008 87.5% 0.007 0.001 11.9% 0.007 0.001 10.0%

S 0.006 0.004 67.5% 0.004 0.000 7.4% 0.004 0.005 109.6%

Hx 0.001 0.000 12.5% 0.001 0.000 0.0% 0.001 0.000 0.0%

Ash_Al 0.001 0.005 587.2% 0.001 0.000 69.8% 0.001 0.001 82.5%

Ash_Ca 0.042 0.042 99.6% 0.031 0.023 74.3% 0.031 0.023 72.9%

Ash_Fe 0.001 0.038 5469.8% 0.001 0.006 1065.8% 0.001 0.006 1109.8%

Ash_Mg 0.002 0.212 10686.6% 0.001 0.032 2138.6% 0.001 0.032 2129.1%

Ash_P 0.003 0.003 115.1% 0.002 0.001 70.0% 0.002 0.001 72.5%

Ash_K 0.019 0.020 105.3% 0.014 0.010 68.4% 0.014 0.010 68.4%

Ash_Si 0.004 0.186 4958.5% 0.003 0.029 1017.1% 0.003 0.030 1055.7%

Ash_Na 0.000 0.001 147.7% 0.000 0.000 137.9% 0.000 0.000 82.2%

Ash_S 0.003 0.000 14.1% 0.002 0.001 30.6% 0.002 0.000 24.1%

Ash_Hx 0.000 0.000 705.5% 0.000 0.000 0.0% 0.000 0.000 0.0%

Ash_CO2 0.024 0.016 65.5% 0.018 0.006 30.6% 0.018 0.006 34.1%

Table 15: Mass balances for oak gasification conditions cont. 

 OK_HY_87085b OK_HY_87095 OK_HY_97075 

 

Mass 

In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Mass In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Mass 

In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Closure 31.2 30.5 97.8% 31.1 30.0 96.3% 30.4 29.4 96.8%

Ash 0.07 0.07 94.1% 0.07 0.08 109.2% 0.05 0.29 538.5%

C 6.73 6.26 93.0% 6.70 5.85 87.4% 4.93 4.29 87.1%

H 2.64 2.85 107.9% 2.64 2.84 107.5% 2.78 2.86 102.9%

O 20.90 22.3 106.6% 20.87 21.9 104.7% 22.00 22.5 102.3%

N 0.007 0.001 11.2% 0.007 0.002 23.3% 0.005 0.003 60.3%

S 0.004 0.005 116.1% 0.004 0.005 118.0% 0.003 0.001 17.4%

Hx 0.001 0.000 0.0% 0.001 0.000 0.0% 0.001 0.000 10.0%

Ash_Al 0.001 0.000 22.8% 0.001 0.000 68.4% 0.000 0.003 544.4%

Ash_Ca 0.031 0.021 67.0% 0.031 0.021 68.5% 0.023 0.018 76.8%

Ash_Fe 0.001 0.003 483.9% 0.001 0.004 687.3% 0.000 0.022 5809.9%

Ash_Mg 0.001 0.013 852.7% 0.001 0.018 1199.8% 0.001 0.126 11596.8%

Ash_P 0.002 0.001 67.5% 0.002 0.001 65.8% 0.001 0.001 86.3%

Ash_K 0.014 0.009 66.7% 0.014 0.009 65.3% 0.010 0.007 69.8%

Ash_Si 0.003 0.013 472.3% 0.003 0.018 658.4% 0.002 0.111 5399.3%

Ash_Na 0.000 0.000 91.9% 0.000 0.002 573.8% 0.000 0.000 187.9%

Ash_S 0.002 0.000 19.0% 0.002 0.000 15.8% 0.001 0.001 51.2%

Ash_Hx 0.000 0.000 156.9% 0.000 0.000 36.4% 0.000 0.000 0.0%

Ash_CO2 0.018 0.010 53.3% 0.018 0.008 45.9% 0.013 0.003 24.9%

32 
Table 15: Mass balances for oak gasification conditions cont. 

 OK_HY_97085 OK_HY_97085b OK_HY_97095 

 

Mass In, 

kg/hr 

Mass Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Mass In, 

kg/hr 

Mass Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Mass 

In, 

kg/hr 

Mass Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Closure 30.3 29.1 95.9% 30.3 30.1 99.6% 30.3 30.3 100.0%

Ash 0.05 0.27 505.1% 0.05 0.12 234.1% 0.05 0.62 1167.5%

C 4.90 4.23 86.3% 4.86 5.00 102.8% 4.87 4.66 95.7%

H 2.78 2.83 102.0% 2.77 2.89 104.1% 2.77 2.95 106.2%

O 21.97 22.2 101.0% 21.94 22.6 102.9% 21.95 22.7 103.5%

N 0.005 0.003 53.0% 0.005 0.003 64.2% 0.005 0.003 68.7%

S 0.003 0.003 112.2% 0.003 0.004 125.7% 0.003 0.001 40.3%

Hx 0.001 0.000 8.8% 0.001 0.000 0.0% 0.001 0.000 13.7%

Ash_Al 0.000 0.003 538.4% 0.000 0.001 126.0% 0.000 0.008 1616.5%

Ash_Ca 0.023 0.018 79.2% 0.023 0.030 133.6% 0.023 0.021 94.7%

Ash_Fe 0.000 0.020 5399.7% 0.000 0.005 1430.9% 0.000 0.049 12973.7%

Ash_Mg 0.001 0.115 10677.2% 0.001 0.029 2665.3% 0.001 0.279 26007.9%

Ash_P 0.001 0.001 79.0% 0.001 0.002 134.0% 0.001 0.002 115.9%

Ash_K 0.010 0.007 69.8% 0.010 0.013 132.5% 0.010 0.009 90.8%

Ash_Si 0.002 0.103 5037.8% 0.002 0.029 1435.1% 0.002 0.248 12227.8%

Ash_Na 0.000 0.000 129.2% 0.000 0.000 141.5% 0.000 0.001 244.4%

Ash_S 0.001 0.000 25.0% 0.001 0.000 27.6% 0.001 0.001 66.6%

Ash_Hx 0.000 0.000 336.7% 0.000 0.000 156.1% 0.000 0.000 778.3%

Ash_CO2 0.013 0.005 36.3% 0.013 0.019 143.9% 0.013 0.011 87.8%

Table 15: Mass balances for oak gasification conditions cont. 

 OK_HY_97095b 

 

Mass 

In, 

kg/hr 

Mass Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Closure 30.3 28.5 94.0%

Ash 0.05 0.22 406.3%

C 4.89 5.05 103.4%

H 2.77 2.73 98.5%

O 21.96 21.1 96.2%

N 0.005 0.001 24.3%

S 0.003 0.005 180.3%

Hx 0.001 0.000 0.0%

Ash_Al 0.000 0.002 361.6%

Ash_Ca 0.023 0.041 179.2%

Ash_Fe 0.000 0.013 3364.5%

Ash_Mg 0.001 0.069 6415.7%

Ash_P 0.001 0.002 165.9%

Ash_K 0.010 0.018 177.1%

Ash_Si 0.002 0.065 3180.9%

Ash_Na 0.000 0.001 359.0%

Ash_S 0.001 0.001 54.1%

Ash_Hx 0.000 0.000 270.8%

Ash_CO2 0.013 0.010 74.7%

 33
Table 16: Mass balances for pine gasification conditions 

PI_HY_77075 PI_HY_77085 PI_HY_77095 

 

Mass 

In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Mass 

In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Mass 

In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Closure 32.1 30.3 94.6% 32.0 29.3 91.5% 32.0 27.4 85.6%

Ash 0.05 0.33 633.8% 0.05 0.66 1250.7% 0.05 0.18 345.4%

C 8.72 8.06 92.5% 8.70 7.95 91.4% 8.69 6.92 79.7%

H 2.66 2.77 103.9% 2.66 2.74 102.9% 2.66 2.57 96.7%

O 18.98 20.8 109.7% 18.97 20.4 107.3% 18.96 19.1 100.6%

N 0.011 0.003 28.0% 0.011 0.002 20.9% 0.010 0.001 10.1%

S 0.004 0.000 6.0% 0.004 0.001 25.5% 0.003 0.001 20.9%

Hx 0.000 0.000 120.2% 0.000 0.000 125.6% 0.000 0.000 43.4%

Ash_Al 0.001 0.007 843.7% 0.001 0.007 885.3% 0.001 0.002 215.3%

Ash_Ca 0.015 0.022 144.9% 0.015 0.022 146.6% 0.015 0.009 61.2%

Ash_Fe 0.001 0.024 2249.8% 0.001 0.052 4928.7% 0.001 0.014 1280.6%

Ash_Mg 0.006 0.135 2438.7% 0.006 0.313 5682.0% 0.006 0.082 1496.6%

Ash_P 0.003 0.003 122.2% 0.003 0.003 102.6% 0.003 0.001 52.7%

Ash_K 0.010 0.013 128.4% 0.010 0.011 105.9% 0.010 0.005 54.8%

Ash_Si 0.003 0.124 4350.9% 0.003 0.271 9586.0% 0.003 0.069 2442.5%

Ash_Na 0.000 0.001 243.8% 0.000 0.000 224.5% 0.000 0.000 132.8%

Ash_S 0.002 0.000 23.3% 0.002 0.001 30.7% 0.002 0.000 14.8%

Ash_Hx 0.000 0.000 149.1% 0.000 0.000 73.6% 0.000 0.000 101.6%

Ash_CO2 0.011 0.007 58.7% 0.011 0.005 42.3% 0.011 0.003 30.5%

Table 16: Mass balances for pine gasification conditions cont. 

PI_HY_87075 PI_HY_87085 PI_HY_87095 

 

Mass 

In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass 

In, 

kg/hr 

Mass Out/ 

Mass In, % 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Mass 

In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Closure 31.5 28.1 89.2% 31.5 30.5 96.9% 31.5 29.9 95.0%

Ash 0.04 0.21 507.1% 0.04 0.18 434.2% 0.04 0.26 620.6%

C 6.91 6.88 99.5% 6.89 6.80 98.7% 6.89 5.92 86.0%

H 2.79 2.72 97.7% 2.78 2.84 101.9% 2.78 2.81 101.1%

O 20.41 20.8 101.8% 20.40 21.6 105.8% 20.39 21.7 106.3%

N 0.008 0.001 16.3% 0.008 0.001 12.9% 0.008 0.001 8.4%

S 0.003 0.000 4.9% 0.003 0.001 22.5% 0.003 0.001 21.9%

Hx 0.000 0.000 195.5% 0.000 0.000 231.5% 0.000 0.000 253.2%

Ash_Al 0.001 0.002 279.9% 0.001 0.002 265.0% 0.001 0.003 411.1%

Ash_Ca 0.012 0.015 122.9% 0.012 0.008 70.2% 0.012 0.011 87.5%

Ash_Fe 0.001 0.014 1709.6% 0.001 0.013 1571.1% 0.001 0.019 2295.2%

Ash_Mg 0.004 0.082 1873.9% 0.004 0.075 1720.1% 0.004 0.110 2529.9%

Ash_P 0.002 0.003 122.9% 0.002 0.002 70.4% 0.002 0.002 87.6%

Ash_K 0.008 0.009 117.8% 0.008 0.006 70.8% 0.008 0.007 88.7%

Ash_Si 0.002 0.071 3153.7% 0.002 0.066 2949.7% 0.002 0.096 4282.4%

Ash_Na 0.000 0.000 182.0% 0.000 0.000 44.5% 0.000 0.000 47.7%

Ash_S 0.001 0.001 46.7% 0.001 0.000 18.6% 0.001 0.000 24.7%

Ash_Hx 0.000 0.000 29.8% 0.000 0.000 25.5% 0.000 0.000 36.5%

Ash_CO2 0.009 0.011 127.1% 0.009 0.007 81.4% 0.009 0.009 103.9%

 34
 35

Table 16: Mass balances for pine gasification conditions cont. 

 PI_HY_97075 PI_HY_97085 PI_HY_97085b 

 

Mass 

In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Mass 

In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Mass 

In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Closure 30.6 30.5 99.8% 30.6 29.4 96.3% 30.6 29.0 94.6%

Ash 0.03 0.21 695.8% 0.03 0.63 2083.2% 0.03 0.06 188.0%

C 5.00 5.31 106.1% 4.98 5.56 111.6% 5.03 5.08 101.0%

H 2.88 3.00 104.2% 2.87 3.12 108.7% 2.88 2.84 98.8%

O 21.60 22.9 105.8% 21.59 24.3 112.7% 21.61 21.8 101.0%

N 0.006 0.001 19.8% 0.006 0.004 65.0% 0.006 0.000 1.1%

S 0.002 0.000 4.6% 0.002 0.001 31.0% 0.002 0.000 21.4%

Hx 0.000 0.000 91.4% 0.000 0.000 458.5% 0.000 0.000 195.6%

Ash_Al 0.000 0.006 1274.2% 0.000 0.062 13419.2% 0.000 0.001 131.8%

Ash_Ca 0.009 0.006 73.9% 0.009 0.033 374.3% 0.009 0.007 82.3%

Ash_Fe 0.001 0.016 2549.1% 0.001 0.034 5548.4% 0.001 0.003 521.1%

Ash_Mg 0.003 0.091 2876.1% 0.003 0.191 6031.4% 0.003 0.018 565.7%

Ash_P 0.002 0.001 53.1% 0.002 0.004 222.6% 0.002 0.001 81.8%

Ash_K 0.006 0.003 54.5% 0.006 0.011 201.7% 0.006 0.005 84.4%

Ash_Si 0.002 0.082 5028.4% 0.002 0.184 11363.0% 0.002 0.015 930.1%

Ash_Na 0.000 0.000 124.9% 0.000 0.001 747.8% 0.000 0.000 86.8%

Ash_S 0.001 0.000 14.9% 0.001 0.001 70.3% 0.001 0.000 36.9%

Ash_Hx 0.000 0.000 245.6% 0.000 0.000 857.8% 0.000 0.000 11.1%

Ash_CO2 0.006 0.003 44.5% 0.006 0.020 308.5% 0.006 0.005 74.5%

Table 16: Mass balances for pine gasification conditions cont. 

 PI_HY_97095 

 

Mass 

In, 

kg/hr 

Mass 

Out, 

kg/hr 

Mass Out/ 

Mass In, % 

Closure 30.5 26.9 88.2%

Ash 0.03 0.07 228.7%

C 4.98 4.79 96.2%

H 2.87 2.98 103.5%

O 21.58 22.3 103.5%

N 0.006 0.001 9.2%

S 0.002 0.000 1.4%

Hx 0.000 0.000 86.8%

Ash_Al 0.000 0.011 2359.5%

Ash_Ca 0.009 0.004 43.2%

Ash_Fe 0.001 0.003 474.3%

Ash_Mg 0.003 0.017 533.6%

Ash_P 0.002 0.000 27.5%

Ash_K 0.006 0.001 20.4%

Ash_Si 0.002 0.017 1056.0%

Ash_Na 0.000 0.000 129.0%

Ash_S 0.001 0.000 8.4%

Ash_Hx 0.000 0.000 80.7%

Ash_CO2 0.006 0.001 16.7%
Appendix C—Tar Concentrations 

Table 17: Absolute wet gas concentrations (mg/Nm3) of selected tars measured during steadystate oak gasification. 

Run ID 77075 77085 77085b 77095 87075 87085 87085b 87095 97075 97085 97085b 97095 97095b 

S:B ratio 0.74 0.74 0.74 0.74 1.25 1.25 1.25 1.25 2.00 2.00 2.00 2.00 2.00 

TC Temp (°C) 750 850 850 950 750 850 850 950 750 850 850 950 950 

Tars (mg/Nm3) 

Benzene 4870 7638 9790 12400 4290 7310 6728 10520 2980 4990 4724 7790 6874 

Toluene 2520 2290 2950 440 2200 2240 2060 400 1460 1550 1470 390 330 

Phenol 1770 810 880 30 1610 820 730 20 1580 730 650 50 40 

Cresol 1320 120 110 20 1100 110 100 10 910 110 80 30 20 

naphthalene 1000 2090 3040 4010 940 2050 1940 3570 610 1300 1200 2380 1830 

phenanthrene 260 650 1040 1290 250 640 580 1190 170 420 360 790 540 

“other tars”(a) 6060 4360 5910 3200 5350 4110 4060 2810 3960 3170 2640 2160 1690 

“heavy tars”(b) 7210 6030 3790 8720 5440 4720 2340 6040 3930 3070 2790 5670 4280 

Total (>m/z 78) 20130 16350 17710 17710 16900 14700 11800 14040 12630 10350 9190 11470 8720 

(a)Summation of mass spectral peak intensities (m/z 80–176)—response for naphthalene used, (b)Summation of mass 

spectral peak intensities (m/z 180-400)—response for phenanthrene used 

Table 18: Absolute wet gas concentrations (mg/Nm3) of selected tars measured during steadystate pine gasification. 

Run ID 77075 77085 77095 87075 87085 87095 97075 97085 97085b 97095

S:B ratio 0.81 0.81 0.81 1.25 1.25 1.25 2.00 2.00 2.00 2.00

TC Temp (°C) 750 850 950 750 850 950 750 850 850 950

Tars (mg/Nm3) 

benzene 4310 8130 12530 3830 8650 9260 2580 4970 4405 7490

toluene 2470 2720 490 2040 2850 420 1380 1640 1430 280

phenol 3270 1570 80 2530 1700 60 1710 1180 1000 20

cresol 1580 150 20 1100 150 20 790 110 90 –

naphthalene 1000 2450 4210 890 2460 3020 620 1470 1150 2520

phenanthrene 400 1090 1860 350 1040 1290 260 670 480 1150

“other tars”(a) 6870 5770 3860 5440 5720 2830 3710 3560 2820 2840

“heavy tars”(b) 7690 7560 9990 5480 6210 5810 4000 4300 2880 5830

Total (>m/z 78) 23280 21310 20507 17830 20110 13450 12470 12910 9850 12630

(a)Summation of mass spectral peak intensities (m/z 80–176)—response for naphthalene used, (b)Summation of mass 

spectral peak intensities (m/z 180-400)—response for phenanthrene used 

36 
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Technical Report 

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4. TITLE AND SUBTITLE

Parametric Gasification of Oak and Pine Feedstocks Using the 

TCPDU and Slipstream Water-Gas Shift Catalysis 

5a. CONTRACT NUMBER

DE-AC36-08-GO28308 

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

J. Hrdlicka, C. Feik, D. Carpenter, and M. Pomeroy 

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NREL/TP-510-44557 

5e. TASK NUMBER

H2713B13 

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National Renewable Energy Laboratory 

1617 Cole Blvd. 

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REPORT NUMBER

NREL/TP-510-44557 

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S)

NREL 

11. SPONSORING/MONITORING

AGENCY REPORT NUMBER

12. DISTRIBUTION AVAILABILITY STATEMENT

National Technical Information Service 

U.S. Department of Commerce 

5285 Port Royal Road 

Springfield, VA 22161 

13. SUPPLEMENTARY NOTES

14. ABSTRACT (Maximum 200 Words)

With oak and pine feedstocks, the Gasification of Biomass to Hydrogen project maximizes hydrogen production using 

the Full Stream Reformer during water-gas shift fixed-bed reactor testing. Results indicate that higher steam-tobiomass ratio and higher thermal cracker temperature yield higher hydrogen concentration. NREL’s techno-economic 

models and analyses indicate hydrogen production from biomass may be viable at an estimated cost of $1.77/kg 

(current) and $1.47/kg (advanced in 2015). To verify these estimates, NREL used the Thermochemical Process 

Development Unit (TCPDU), an integrated system of unit operations that investigates biomass thermochemical 

conversion to gaseous and liquid fuels and chemicals. 

15. SUBJECT TERMS

oak feedstock; pine feedstock; parametric gasification; Thermochemical Process Development Unit; TCPDU; 

slipstream; water-gas shift catalysis; Gasification of Biomass to Hydrogen; Full Stream Reformer; FSR; steam-tobiomass ratio; thermal cracker temperature; hydrogen concentration; biomass; thermochemical conversion; liquid 

fuels 

16. SECURITY CLASSIFICATION OF: 17. LIMITATION 

OF ABSTRACT

UL 

18. NUMBER 

OF PAGES 

19a. NAME OF RESPONSIBLE PERSON 

a. REPORT 

Unclassified 

b. ABSTRACT 

Unclassified

c. THIS PAGE 

Unclassified 19b. TELEPHONE NUMBER (Include area code)

Standard Form 298 (Rev. 8/98) 

Prescribed by ANSI Std. Z39.18