TWO-STEP PYROLYSIS PROCESS APPLIED TO USED RAILROAD TIES AND UTILITY POLES

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: AFRI COMPETITIVE GRANT
• Reporting Frequency: Annual
• Accession No.: 1007281
• Grant No.: 2015-67021-24121
• Cumulative Award Amt.: $488,467.00
• Proposal No.: 2015-06050
• Project Start Date: Sep 1, 2015
• Project End Date: Feb 28, 2019
• Grant Year: 2015
• Program Code: [A1521]- Agricultural Engineering

Project Director
Labbe, N.

Recipient Organization
UNIVERSITY OF TENNESSEE
2621 MORGAN CIR
KNOXVILLE,TN 37996-4540

Performing Department
Center for Renewable Carbon

Non Technical Summary
Over 20 million new wooden railroad ties are installed every year in the U.S. This is of high value to the forest products sector as well as being over 20 % of the U.S. wood treatment industry and the jobs that both support. Moreover, wood is the best environmental option for railroad ties and utility poles. An important part of the sustainability of this industry is the ability to re-use or dispose of treated wood coming out of service. However, regulatory and environmental and financial landscape for such re-use and disposal are rapidly changing and significantly reducing the competitiveness of wood versus non-wood alternatives such as concrete and steel. Meanwhile, the developing bioeconomy sector struggles to obtain suitable high quality feedstock to cost effectively produce biofuels and bioproducts.The objective of this project is to propose an additional re-use option for used railroad ties and utility poles while securing an excellent feedstock for bio-oil production. Additionally, it will maintain or even increase the competitiveness and environmental profile of wood over non-wood alternatives. Initial results show that this may be possible by extracting the preservative for re-use in the treatment of new wood and adding value to preservative-free biomass for the production of higher quality bio-oil. The proposed process is to be achieved by careful temperature and time controlled of the desorption and pyrolysis steps. Two commonly used pyrolysis techniques, intermediate and fast pyrolysis, will be evaluated as part of the optimization and costing of a commercial scale facility.

Animal Health Component

50%

Research Effort Categories

Basic

25%

Applied

50%

Developmental

25%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
403	0650	2020	100%

Knowledge Area
403 - Waste Disposal, Recycling, and Reuse;

Subject Of Investigation
0650 - Wood and wood products;

Field Of Science
2020 - Engineering;

Keywords

desorption

preservatives

pyrolysis

used railroad ties

used utility poles

Goals / Objectives
The objective of this project is to propose an additional re-use option for used railroad ties and utility poles while securing an excellent feedstock for bio-oil production. Additionally, it will maintain or even increase the competitiveness and environmental profile of wood over non-wood alternatives. Initial results show that this may be possible by extracting the preservatives for re-use in the treatment of new wood and adding value to preservatives-free biomass for the production of higher quality bio-oil. The proposed process is to be achieved by careful temperature and time controlled of the desorption and pyrolysis steps. Two commonly used pyrolysis techniques, intermediate and fast pyrolysis, will be evaluated as part of the optimization and costing of a commercial scale facility.

Project Methods
1) Py-GC/MS and TGA/MS analyses will be employed to evaluate the impact of temperature and time on the desorption of preservative from used treated wood. Through this step, we will optimize these two parameters to recover as much preservative as possible in treated wood and generate decontaminated preservative-free wood. To further assert the effectiveness of the desorption step, the desorbed samples will be subsequently pyrolyzed in the Py-GC/MS.2) We will investigate and optimize the extraction of wood preservatives from used treated wood using two pyrolysis systems: a bench-scale high pressure fluidized bed fast pyrolysis and a semi-pilot auger intermediate pyrolysis system. These two systems, commonly used in biomass pyrolysis, will enable comprehensive evaluation of the impact of heat transfer rates, pressures and hydrodynamics on the quality of the products. Recovered preservatives, bio-oil, biochar, and combustible gas products will be analyzed online and off-line to aid in the optimization process and generate process specific data for further process performance analysis and economic assessment.3) Given that our long-term goal is to develop an economically and environmentally viable two-step pyrolysis process to upgrade and utilize used wood railroad ties and utility poles, our project includes a process performance and economic analysis. The goal of this objective is to develop a systematic process integration framework for the design and techno-economic performance analysis of the proposed two-step process. Our working hypothesis is that by coupling the two-step pyrolysis process to establish downstream technologies for the valorization of bio-oil, biochar, non-condensable gases and recovered preservatives, we diversify the product portfolio and hence increase the economic viability of the two-step process. Our approach is to carry out preliminary process evaluation on the potential of the two-step pyrolysis process and refine these analyses throughout the project as research begins to provide process specific data for the update of models.

Progress 09/01/15 to 02/28/19

Outputs
Target Audience:Our targeted audiences for the engineering process analysis during the project include process engineers and process developers, in general. Specifically, we reached out to engineering professionals and researchers in the railroad tie industry, waste management companies, agricultural and natural resource engineering companies and industries looking for new waste streams to valorize. Furthermore, we have targeted the following academic audiences: graduate and undergraduate students and the scientific community interested in developing thermochemical processes for biomass conversion. We were engaged in the following efforts during the project: graduate and undergraduate education, outreach to industrial stakeholders and dissemination of our findings to the scientific community. Our graduate and undergraduate education efforts include providing training, mentoring and support for two graduate research assistants funded by this project. Furthermore, we have provided experiential learning opportunities for undergraduate students in the various laboratories involved on the project. We have hosted numerous stakeholders from academia and industry at our facilities in the past year to discuss our process of recovering creosote from ties and converting the resulting biomass into value added products. Additionally, we have engaged the scientific community by participating in professional meetings where our findings were presented. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?We have provided research training for several graduate and undergraduate students who participated directly and indirectly on this project. The training included one-on-one meeting on a weekly basis, regular presentations to internal and external audiences as well as research training in the lab, short series courses on specific topics and various professional development activities, e.g. resume clinic, mock interviews. Undergraduate and graduate students were provided the opportunity to advance their professional skills by learning from the project investigators and their lab members. Additionally, the graduate student on the project participated in several conferences. How have the results been disseminated to communities of interest?The findings of this project were disseminated through publications in scientific journals, presentations at professional meetings. Please see the following sections Refereed publications and theses and Other publications, conference papers and presentations. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? This project demonstrated the feasibility of a new technology pathway that efficiently desorbs creosote from used railroad ties and subsequently converts the resulting creosote-free ties into gasoline and diesel. At a capacity of 1769 dry tons of ties per day, a typical electricity self-sufficient integrated plant will generate 237 tons of recovered creosote, 69293 gallons of gasoline, and 74922 gallons of diesel, daily. In addition, the plant will produce an excess of 2831 kW of electricity which will be offloaded onto the grid. Our economic analysis considered three integrated plants strategically situated to minimize delivery cost of the ties and estimated that 2.33 millions tons of used ties will be available. This economic assessment is conceptual since our desorption process has yet to be deployed at a relevant scale and only a few large-scale pyrolysis plants have been commissioned. The analysis found that the equipment cost is $135 MM and the total capital investment is $299 MM, with the largest portion attributed to the fast pyrolysis and vapor-condensation area. The first step, the desorption step, accounts for only $89 MM. A sensitivity analysis was used to evaluate the impact of process and financial uncertainties of the minimum fuel selling price (MFSP). The analysis showed that MFSP can be significantly lower if one single plant (5307 dry tons/day) is used, however, the model does not take in consideration the added cost associated with the logistics of delivering such large amount of ties to one single plant.

Publications

• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Ross Houston, Nicole Labbe, Douglas Hayes, Charles Daw, Nourredine Abdoulmoumine. Intermediate Temperature Water-Gas Shift Kinetics for Hydrogen Production. Reaction Chemistry & Engineering.

Progress 09/01/17 to 08/31/18

Outputs
Target Audience:The target audiences reached by our effort during the reporting period include the railroad tie industry, waste management companies, industries looking for new waste streams to generate value added chemicals from biomass and wastes, bioenergy industries looking for unexpensive feedstocks, graduate and undergraduate students, and the scientific community interested in developing thermochemical processes for biomass conversion. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?We were engaged in the following efforts during the reporting period: graduate and undergraduate education, outreach to industrial stakeholders and dissemination of our findings to the scientific community. Our graduate and undergraduate education efforts include providing training, mentoring and support for two graduate research assistants funded by this project. Furthermore, we have provided experiential learning opportunities for undergraduate students in the various laboratories involved on the project. We have hosted numerous stakeholders from academia and industry at our facilities in the past year to discuss our process of recovering creosote from ties and converting the resulting biomass into value added products. Additionally, we have engaged the scientific community by participating in professional meetings where our findings were presented. The graduate students on the project participated and presented their work at several conferences. How have the results been disseminated to communities of interest?The findings of this project were disseminated through publications in scientific journals, presentations at professional meetings, reported in 1: The ACS Chemical & Engineering News (volume 95, issue 38, p. 8, September 2017) "Recycling railroad ties comes with benefits" by Stephen K. Ritter. https://cen.acs.org/articles/95/i38/Recycling-railroad-ties-comes-benefits.html 2: Fresh from the field, Weekly Highlights of the National Institute of Food and Agricultures's grantee community website, https://content.govdelivery.com/accounts/USDANIFA/bulletins/21b1f71 What do you plan to do during the next reporting period to accomplish the goals?In the next reporting period, we will conducting bench-scale fast pyrolysis experiments on untreated ties as well as treated ties to determine of the effect, if any, preservative removal on the quality of the resulting pyrolysis bio-oil. In the current reporting period, we encountered an issue with the bench-scale pyrolysis reactor, which was due to undesirable packing of partially reacted biomass at the outlet of the reactor. We are currently redesigning select components of the reactor to overcome the issue.

Impacts
What was accomplished under these goals? During this period, we finalized the technoeconomic analysis of our proposed process which is to 1) desorb and recover creosote from used ties and 2) convert the desorbed ties into bio-oil upgraded to gasoline and diesel. Our model system was evaluated with three plants geographically spread across the United States to minimize the cost of transportation. Under our baseline case scenario, our process was found to generate 237 tons/day of recovered creosote and 69,293 and 74,922 gal/day of gasoline and diesel, respectively. Moreover, we determined that the plant will be self-sufficient in electricity supply and will generate an additional 2831 kW offloaded onto the grid. The estimated total capital investment for an nth plant was estimated at $380 million. Furthermore, the minimum fuel selling price (MFSP) was determined to be $2.52 per gasoline gallon equivalent (GGE) at a 10 % required internal rate of return in 2016 U.S. dollars, with a simple payback period of 9 years after tax and a market price of recovered creosote of $2.80/gal. The sensitivity analysis reveals that plant size, internal rate of return, and feedstock cost have the most impact on the MFSP.

Publications

• Type: Journal Articles Status: Published Year Published: 2018 Citation: Kim P., H. L. Haber, J. Lloyd, J.W. Kim, N. Adoulmoumine, N. Labb�. Optimization of thermal desorption conditions for recovering wood preservative from used railroad ties through response surface methodology. Journal of Cleaner Production, 2018, 201, 802-811. DOI: 10.1016/j.jclepro.2018.08.097
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Houston R., H. L. Haber, P. Kim, J.W. Kim, J. Lloyd, N. Labb�, N. Abdoulmounine. Rail road tie preservative recovery and conversion to hydrocarbon fuels: A Conceptual process design and economics. Biofuels Bioproducts & Biorefining. 2018, 12, 834-845, DOI: 10.1002/bbb.1894
• Type: Theses/Dissertations Status: Published Year Published: 2018 Citation: Holly Haber, Sustainable method for recovery of copper naphthenate from used railroad ties. Master of Science Degree, The University of Tennessee, May 2018
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: " Ross Houston, Oluwafemi Oyedeji, and Nourredine Abdoulmoumine. Development of a comprehensive computational fluid dynamics and discrete element model of biomass fast pyrolysis in a bubbling fluidized bed reactor. 2017 ASABE Annual International Meeting, July 16-19, 2017 Spokane, WA.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: " Ross Houston, Nicole Labb�, and Nourredine Abdoulmoumine. The Kinetics of the Water-Gas Shift Reaction for the Production of Hydrogen over a Cu-based Catalyst for Biomass Hydrous Pyrolysis. 2017 AIChE Annual Meeting, October 29-November 3, 2017 Minneapolis, MN.
• Type: Theses/Dissertations Status: Published Year Published: 2018 Citation: Houston Ross, Computational Fluid Dynamic Modeling of Catalytic Hydrous Pyrolysis of Biomass to Produce Refinery-Ready Bio-Crude Oil, Master of Science Degree, The University of Tennessee, June 2018
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: " Holly Haber, Pyoungchung Kim, Stephen Chmely, Jeff Lloyd, Yagya Regmi, Nourredine Abdoulmoumine, Nicole Labb�. Two-step process for recovery of copper naphthenate from end-of-life railroad ties. 225th American Chemical Society National Meeting, March 18-22, 2018 New Orleans, LA.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: " Ross Houston and Nourredine Abdoulmoumine. Computational Modeling of Biomass Hydrous Pyrolysis with In-situ Hydrogen Generation to Produce Refinery-Ready Bio-crude Oil. Symposium on Thermal and Catalytic Sciences for Biofuels and Biobased Products, October 8th-10th, 2018 Auburn, AL.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: " Ross Houston and Nourredine Abdoulmoumine. Computational Fluid Dynamic Modeling of Catalytic Hydrous Pyrolysis in a Fluidized Bed Reactor to Produce Refinery-Ready Bio-crude Oil. 2018 ASABE Annual International Meeting, July 29-August 1, 2018 Detroit, MI.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: " Ross Houston, Oluwafemi Oyedeji, and Nourredine Abdoulmoumine. Development of a Comprehensive Computational Fluid Dynamic and Discrete Element Model of Biomass Fast Pyrolysis in a Bubbling Fluidized Bed Reactor. 2017 NETL Workshop on Multiphase Flow Science, August 8-10, 2017 Morgantown, WV.

Progress 09/01/16 to 08/31/17

Outputs
Target Audience:The target audience reached by our effort during the reporting period was the railroad ties industry, waste management companies, co-generation facility,industries looking for new waste streams to generate value added chemicals from biomass and wastes, and the scientific community interested in developing thermochemical processes for biomass conversion. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The postdoc and two graduate studentswho are working on this projectare being trained to generate and assemble data that are needed for evaluating the technical and economic viability of the two-step process. Both graduate students have also been trained at performing the thermal desorption at bench and pilot scale. Regular meetings with our industrial partner (Nisus) have also been great opportunities for the graduate students to understand the challenges that the ties industry is facing. How have the results been disseminated to communities of interest?Our findings were presented at various conferences: P. Kim, N. Labbe, N. Abdoulmoumine, J. Lloyd, J. Kim, et al (2016), Oral presentation, "Recycling of used railroad tie via an auger pyrolysis system", 2016 America Institute of Chemical engineering Conference, November 13 - 18, 2016, San Francisco, CA, USA. What do you plan to do during the next reporting period to accomplish the goals?During the next reporting period, large amount of desorbed materials will be generated using thepilot scale pyrolysis reactor. The best cleating agents will be used to extract the inorganics then the materials will be pyrolyze in a fluidized bed reactor. The non-condensable gas, bio-oil, and biochar will be characterized. The desorbed-chelating extracted biomass will be compared to the desorbed material, and to the untreated ties.

Impacts
What was accomplished under these goals? A two-step thermochemical process combining a thermal desorption at 250 - 300 ºC and a pyrolysis at 500 ºC of used creosote-treated wooden railroad ties was carried out usinga semi-pilot scale augerreactor systemto recover preservative and produce a high quality bio-oil and biochar. Under optimal temperature, high preservative removal efficiency (70 - 74 %) was achieved with a high proportion of polycyclic aromatic hydrocarbons (PAHs, 80 - 82 %) and a large portion of the original wood mass (67 - 70 %) was retained.Pyrolysis of these thermally treated ties generated a bio-oil with lower water content and total acid numbers, and higher amount of lignin-derived compounds than that of untreated ties. The generated biochar contained higher carbon content and lower amount of PAHs than the biochar from untreated ties. The removal of copper naphthenate (CN) from the used ties was investigated to improve the commercial viability of this biomass as a fuel source and avoid alternative disposal methods, like landfilling. Bench-scale thermal desorption of organic preservative components from CN-impregnated ties was followed by extraction of the copper fraction with various chelating agents: ethylenediaminetetraacetic acid (EDTA), 1-hydroxy ethylidene-1,1-diphosphonic acid (HEDP), and 2,6-pyridine dicarboxylic acid (PDA). Naphthenic acid (NA) was recovered at desorption temperatures between 225 and 300 °C and could potentially be recycled to treat new ties. Chelation with PDA, a biodegradable chelating agent, after desorption had the highest extraction efficiency of copper and other naturally present inorganics; extracting 100 % of the copper from both the raw and 225 °C-treated samples. Optimized desorbed material showed a 64 % decrease in ash content when extracted with PDA. We concluded that the optimum desorption conditions were between 250 and 275 °C for 45 min followed by extraction with PDA when considering both NA removal and inorganic extraction efficiency.

Publications

• Type: Journal Articles Status: Published Year Published: 2017 Citation: Kim P., A. Taylor, J. Lloyd, J. Kim, N. Abdoulmoumine, and N. Labb�*. A two-step thermochemical process for adding value to used railroad wood ties and reducing environmental impacts. ACS Sustainable Chemistry & Engineering. 2017, DOI: 10.1021/acssuschemeng.7b02666
• Type: Journal Articles Status: Under Review Year Published: 2017 Citation: An environmentally friendly process for recovery of wood preservative from used copper naphthenate treated railroad ties
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Haber H., P. Kim, S. C. Chmely, J. Lloyd, Y. N. Regmi, N. Abdoulmoumine, N. Labb�*. Environmentally friendly process for recovery of wood preservative from used copper naphthenate-treated railraod ties. ACS Sustainable Chemistry and Engineering, 2017, DOI: 10.1021/acssuschemeng.7b02760
• Type: Journal Articles Status: Submitted Year Published: 2017 Citation: Ross Houston, Holly Haber, Pyoungchung Kim, Jae-Woo Kim, Jeff Lloyd, Nicole Labb�, and Nourredine Abdoulmoumine. Rail road tie preservative recovery and conversion to hydrocarbon fuels: A Conceptual process design and economics

Progress 09/01/15 to 08/31/16

Outputs
Target Audience:The target audience reached by our effort during the reporting period was the railroad ties industry, waste management companies,industries looking for new waste streams to generate value added chemicals from biomass, and the scientific community interested in developing thermochemical processes for biomass conversion. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The post doc working on this project is being trained to generate data that are useful for evaluating the technical and economic viability of the two-step process. How have the results been disseminated to communities of interest?Our findings were presented at various conferences and symposiums: 1. N. Labbe, P Kim, N. Abdoulmoumine, J. Lloyd. Maximinzing the value and environemental benefits of used ties. 97th Annual RTA Conference (Tucson Arizona, November 2-5, 2015). 2. P. Kim, J. Lloyd, N. Labbe. Two-step pyrolysis applied to used railroad ties, ACS international conference (March 13-17, 2016, San Diego, CA) 3. P. Kim, J.Lloyd, N. Abdoulmoumine, N. Labbe. Reclaiming creosote by thermal desorption in used wood ties, International crosstie & fastening system symposium (June 14-16, 2016, University of Illinois at Urbana-Champaign, USA) What do you plan to do during the next reporting period to accomplish the goals?During the next reporting period, we will perform creosote desorption under optimum conditions using a semipilot-scale auger reactor. After the desorption at low temperature (250 - 300 oC), the thermally treated wood will be pyrolyzed at 500 oC for 72 s to produce bio-oil and biochar. The creosote fraction, bio-oil and biochar will be analyzed. Creosote content in the bio-oil will be monitored to estimate the creosote removal yield. The desorbed creosote fraction will be analyzed by gas chromatography mass spectrometry and compared to commercial creosote. We will also investigate theeffect of Cu contained in Cu-Naphthenate-treated wood ties (Cu-N wood tie) during pyrolysis processes. Cu-N wood ties will be treated with different solvents to remove Cu from the samples and the resulting materials will be tested using a fluidized bed pyrolysis reactor to produce high quality bio-oils.

Impacts
What was accomplished under these goals? 1. The thermal desorption of creosote remaining in used ties was investigated by thermogravimetry analysis (TGA)and pyrolysis gas chromatography mass spectrometry (Py-GC/MS). These two techniques permitted the identification of optimum temperature and residence time to desorb most of the creosote while minimizing the degradation of the solid matrix (wood). The data generated by these experiments are being used to perform the desorption of creosote at the lab scale and also to initiate the process analysis of the proposed system. 2. According tothe operation conditionsextracted from Py-GC/MS and TGA experiments, we have set up the lab-scaled batch reactor with liquid nitrogen-cooledcondensers to collect creosote from used railroad tie materials. Thermal desorption conditions ranging from250 to 350 oC for 30 min residence time were applied to recover creosote and upgrade the wood to provide an improved quality biomass for subsequent thermochemical processes. Our study concluded that thermal treatment ranging between 275 and 300 oC would be preferred to recover creosote (65 - 79%) and generate a biomass feedstock containing 19-23 MJ/kg, and energy yield of 75 - 87%.

Publications

• Type: Journal Articles Status: Published Year Published: 2016 Citation: Thermal desorption of creosote remaining in used railroad ties: investigation by TGA and PyGC/MS. P Kim, J. Lloyd, J.W Kim,N. Labbe. Energy, 96, 2016, 294-302.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Recovery of creosote from used railroad ties by thermal desorption. P. Kim, J. Lloyd, J.W. Kim, N. Abdoulmoumine, Energy, 111, 2016, 226-236