Millennium Synfuels Project: Retort Process Characterization Project Overview for UHOP Review March 12, 2008
Background Energy security issue has led to interest in coal-to-liquids technologies One approach use retorting technology commonly associated with oil shale processing Hybrid Energy System (HES) technology developed by: Millennium Synfuels, LLC joint venture of Ambre Energy Pty, Ltd (Australia) and Oil Tech (Utah) University of Utah is providing technical assistance in commercial development of the process
The HES Process - Characteristics A continuous flow retort for pyrolyzing (heating without oxygen) carbonaceous material Electrically-heated lowtemperature gravity-fed retort (right). The process operates at relatively low temperatures producing: a gas stream suitable for gas turbine use high value liquids for chemical and refinery feedstocks a clean burning, high energy char Gravity-Fed Retort
Objectives University of Utah is assisting commercial developer with Identification of kinetic rates and product distributions for operating conditions unique to the HES process Accomplished via 4 Tasks Detailed literature review Process modeling Bench-scale experiments TGA Laboratory-scale retort Detailed measurements and characterization during pilot plant operation Millennium Synfuels Pilot Facility located near Bonanza, UT Due to time constraints will focus on these tasks
Coal Analyses ANALYSIS Sub-bituminous A Lignite B Total Moisture (ad%) Ash (ad%) Volatile Matter (ad%) Fixed Carbon (ad%) Total Sulfur (ad%) Carbon (daf%) Hydrogen (daf%) Nitrogen (daf%) Total Sulfur (daf%) Oxygen by difference (daf%) 4.9 27.5 37.9 29.7 0.46 73.1 6.13 1.03 0.78 19.0 29.4 9.0 39.0 37.6 0.78 57.7 7.08 0.99 2.61 31.62 For both bench- and pilot-scale experiments
Task 3 Bench-Scale Laboratory Experiments Subtask 3.1 Thermogravimetric Analyses (TGA) Used as a rapid screening tool to evaluate effect of key operating parameters (heating rate, final T, hold time) Also used to fit rate parameters for process model ~20 mg samples in inert, or very low O 2 environments
Typical TGA Results Lignite B 600 C at 10 C/min, hold 55 min Mass vs. time for original sample Mass vs. temperature for original sample 100 1000 100 Weight, percent of initial 80 60 40 20 800 600 400 200 Temperature, C Weight, percent of initial 80 60 40 20 0 0 0 50 100 150 200 Time, minutes 0 0 100 200 300 400 500 600 700 Temperature, C Mass and temp. vs. time for dry sample Mass vs. temperature for dry sample 100 1000 100 Weight, percent of initial 80 60 40 20 800 600 400 200 Temperature, C Weight, percent of initial 80 60 40 20 0 0 0 20 40 60 80 100 120 Time, minutes 0 0 100 200 300 400 500 600 700 Temperature, C Results were found to be reproducible Volatiles continue to be released once final T is reached (not consistent with the literature)
TGA Results Lignite B Average Volatiles: 450 C: 26%, 600 C: 36% 750 C: 42% Increased volatiles with temperature; consistent with the literature Considerable difference between 600 and 750 No influence on volatiles due to heat rate (=> use 5 C/min) Given the relatively low heat rates, consistent with literature
TGA Results Sub-bituminous A Average Volatiles: 450 C: 22% 600 C: 27% 750 C: 29% Negligible influence of heating rate Much lower volatiles than lignite coal Little difference between 600 and 750
Example: Fitting Model Parameters Lignite B coal weight loss, daf b 1 0.8 0.6 0.4 0.2 0 0 20 40 60 time, min Fit of our TGA data to determine Arrhenius parameters for coal devolatilization in the process model: A 1 =3.7e5 and A 2 =1.46e13; E 1 /R=13,417 and E 2 /R=28,205; α 1 =0.2565
Conclusions of TGA Tests TGA experiments were very reproducible Lignite coal had much higher volatiles than subbituminous Lignite much more sensitive to temperature than subbituminous Heating rate had negligible effect on yields over the range studied Particle size influence: Pulverized and small chunks (1-2 mm) showed no significant difference When run with one large 400 mg chunk, mass and heat transfer effects resulted in very slow drying, when resulted in larger apparent volatiles yield
Task 3 Bench-Scale Laboratory Experiments Subtask 3.2 Lab-scale retort reactor Design and construction of ~ 1kg batch reactor Experimental matrix Two coals (lignite B, sub-bituminous A) Vary heat rate, final temperature, soak time at final T Subtask 3.3 Analytical Methodologies Develop or adapt methods for extraction, isolation and characterization of condensable hydrocarbons Develop portable versions of the liquid capture and gas conditioning systems Provide detailed characterization of the liquid and gaseous products for lab- and pilot-scale retorts
Laboratory-Scale Reactor 10 cm ID 12 cm length 1.75 liter volume Seven heaters 1.3 cm diameter 20 cm length
Lab-Scale Reactor Procedure Pre-dry coal 3 days at 137 C Lignite mass loss 14%; Subbituminous 9% Load coal into reactor and seal 800-1000 grams Filled to top of heaters Sit overnight for gaskets to dry Heat reactor Set controller to 150 C for initial heating Once temps showed 100 C, ramp at 5 C/min to final temperature. Hold at this temp. Four conditions Two final temps: 450 and 600 C Two holding times: 15 and 60 minutes
Lab-Scale Test Sampling System Column Target compounds Temp. (C) Pressure (psi) Length (m) Mol Sieve 5A PLOT H 2, O 2, N 2, CH 4, CO 125 40 20 PoraPLOT U PLOT CO 2, C 2 H 4, C 2 H 6, H 2 S 50 25 10 Alumina KCl PLOT C 3 H 8, C 3 H 6, C 2 H 2, C 4 H 10 80 25 10 CP-Sil 5 CB C 4 H 10, C 5 H 12, C 6 H 14 50 18 6
Distribution of Phases 110 100 90 80 70 60 50 % gas % organic % aqueous % char + ash 40 30 20 10 0 Lignite 600C 60 min Lignite 600C 15 min Lignite 450C 60 min Lignite 450C 15 min Subbit, 600C, 60 min Subbit, 600C,15 min Subbit, 450C, 60 min Subbit, 450C, 15 min
Gas Composition versus T mol % 100 90 80 70 60 50 40 30 20 N-Hexane N-Pentane Iso-Butane Unknown454 n-butane Iso-Butane Acetylene Propylene Propane Hydrogen Sulfide Ethane Ethylene Carbon Dioxide Carbon Monoxide Methane Hydrogen 10 0 300 C 450 C 600 C 300 C 450 C 600 C LIGNITE SUBBITUMINOUS
Oil Product Fractions Lab Scale Experiments 100 90 80 Lignite 450C 60min Lignite 600C 60min Sub-bit. 450C 60min Sub-bit. 600C 60min 70 Weight Percent 60 50 40 30 20 10 0 Volatiles (<1050 F) wt% volatiles IBP - 400 F wt% Naptha 400-650 F wt% Distillate 650-1050 F wt% Gas Oil > 1050 F wt% Residuum
Conclusions of Lab-Scale Gas production Retort Tests Lignite produces more gas than subbituminous Production of gas+oils+water (not from drying phase) corresponds very well to "volatiles" from TGA experiments, both on dry basis More H 2, CH 4 and less CO 2 at higher final temperature Oil production Overall composition and corresponding boiling point distribution and fractionation similar among all samples Primarily distillate and gas oil
Task 4 Pilot-Scale Testing Technical resource to Millennium Synfuels technical team Assisted with planning of pilot scale tests Provided technical support on site during pilot plant runs at Bonanza, UT facility Provided analytical measurements during testing Status: Summer testing campaign (July/Aug 2007) completed 5 UofU technical staff involved in retort operation/measurements Analysis complete for all liquid and gaseous process and product samples Additional analyses being performed on liquid and solid samples by commercial laboratories Millennium Synfuels Pilot Facility located near Bonanza, UT
Concluding Comments Relatively short-term, industry-driven program University was able to respond using combination of professional staff, faculty and students Results from all scales provided sufficient confidence in process to allow Millennium Synfuels to proceed to next phase of development
Acknowledgements Task 1 Literature Review Hongzhi Zhang, Adel Sarofim Task 2 Process Modeling Geoff Silcox Task 3.1 - TGA Sam Dickman, Kevin Whitty Task 3.2 Lab-Scale Retort Derrick Call, Phil Jankovich, Dana Overacker, David Wagner, Kaushik Gandhi, Kevin Whitty, JoAnn Lighty Task 3.3 Analytical Methodologies David Wagner, David Ray Wagner, Kaushik Gandhi, Kevin Whitty Task 4.1 Pilot-Scale Testing Ryan Okerlund, David Wagner, David Ray Wagner, Phil Jankovich, Eric Eddings Task 4.1 Pilot-Scale Lab Analyses Kaushik Gandhi, Derrick Call Task 5 Reporting Kerry Kelly & all of the above