Niu: Drying Fuel Alcohols and Natural Gas with Biosorbents Based on Agricultural By-products
Date: August 2018
Term: n/a
Status: Completed
Researcher(s): Catherine Hui Niu and Ajay Dalai, University of Saskatchewan, Saskatoon SK
SaskCanola Investment: n/a
Total Project Cost: n/a
Funding Partners: WGRF, Natural Science and Engineering Research Council of Canada, Canada Foundation for Innovation
Project Summary
Researchers at the University of Saskatchewan conducted a multi-year, multi-objective research project developing, analyzing, and testing the use of biomaterials (e.g. flax shives, canola meal, and oat hulls) as a biosorbent to dry natural gas and bio-alcohols. Overall, the project resulted in the development of various novel technologies to reduce the processing costs in renewable bioenergy, and the commercialization of by-products (canola meal, oat hulls, flax shives) as biosorbents. Because the current assessment is still limited to the data achieved in lab-scale, further research and more in-depth feasibility assessments beyond the pilot scale will be required for commercial industry applications.
Dehydration of gases is crucial in industry, however current dehydration methods have concerns of high energy consumption, and environmental pollution. Researchers at the University of Saskatchewan conducted a multi-year, multi-objective research project developing, analyzing, and testing the use of biomaterials (e.g., flax shives, canola meal, and oat hulls) as a biosorbent to dry natural gas and bio-alcohols. The overall objective of this research project was to develop and test high performance biosorbents from agricultural by-products for drying natural gas and fuel alcohols (bio-alcohols) in a pressure swing adsorption (PSA) process.
Objective 1: Evaluation of drying natural gas using flax shives
In the first study, researchers evaluated the use of flax shives as a biosorbent in natural gas dehydration in a PSA system. Flax shives, a byproduct from agricultural industry containing lignocellulose materials, was used to dehydrate methane, a main component of natural gas, in a PSA process. Flax shives were characterized, and the effect of PSA operating parameters were studied.
The results showed that a biosorbent developed from flax shives was able to effectively dehydrate methane with a higher selectivity for water adsorption than most commercial adsorbents and demonstrated stable performance after 70 hydration/dehydration cycles. Adsorption of methane, nitrogen and carbon dioxide was negligible. The biosorbent was also stable at temperatures up to 200 °C. The results show that the flax shive biosorbent is promising in the dehydration of methane (natural gas), and other non-polar gases in a PSA process. The results generated from drying natural gas using the flax shives based biosorbent were filed as part of US provisional patent application (Serial No. 62/575,137).
Objective 2: Evaluation of drying butanol using canola meal after protein extraction
The second study evaluated the use of canola meal after protein extraction as a biosorbent in dehydrating butanol. Using the previously developed PSA system, researchers studied the effects of various operating parameters (temperature, pressure, feed butanol composition, feed butanol flow rate, and canola meal particle size) on the effectiveness of canola meal as a biosorbent in the dehydration process. Overall, these results show that canola meal after protein extraction as a biosorbent has the capability to dry butanol from 55 to 99 v/v%. Reusability of the canola meal as a biosorbent was also tested, which was cycled through the dehydration process 16 times with no deterioration in biosorbent quality detected.
Objective 3: Evaluation of drying butanol using oat hulls
The third study evaluated the use of oat hulls as a biosorbent in drying butanol in a similar PSA system as a comparison using similar techniques. The results showed that using oat hulls was capable of achieving 99.0% butanol content as an output. Water adsorption of oat hulls was slightly lower than that of canola meal for drying lower grade butanol (55% v/v), but higher for drying higher grade butanol (95% v/v). This means that canola meal biosorbent may have better performance for dehydrating lower-concentration bio-butanols, while oat hulls may be better suited as a biosorbent to dehydrate higher-concentration bio-butanols.
Objective 4: Techno-economic analysis on three dehydration processes
In the final study, researchers conducted a comparative economic analysis of three dehydration processes (tetraethyl-glycol system, temperature swing adsorption, and pressure swing adsorption) to investigate if PSA using biosorbents would be a feasible industrial solution for drying natural gas at a pilot scale. A simulation model using available industrial data and data collected from previously performed analyses was used to simulate operating conditions on these three systems, including capital, operating, and recovery costs for each system.
The analysis for natural gas dehydration showed that the PSA technique had the lowest capital cost ($2.45 million USD), lowest annual operating cost ($956,000 USD/year), and lowest gas emissions (<0.1 kg/h), when compared to temperature swing adsorption and tetraethyl-glycol systems. Additionally, the PSA system has fewer pieces of equipment, higher potential for automation, as well as lower and safer operating temperatures. Although dehydrated butanol recovery between canola meal or oat hull pressure swing adsorption systems were comparable (both above 99.9%), canola meal biosorbent may have better performance for dehydrating lower-concentration bio-butanols, while oat hulls may be better suited as a biosorbent to dehydrate higher-concentration bio-butanols. The overall cost for the oat hull biosorbent system for drying lower grade butanol from a 55 % starting point was slightly higher as the water adsorption capacity of oat hulls is slightly lower than that of canola meal. Further research is required at the pilot scale to verify this economic analysis.
Overall, this project resulted in the development of novel technologies that will be able to address energy, agriculture and environmental needs, and contribute to the fundamental knowledge of biosorbents, agricultural by-products, energy, and material science and engineering. Because the current assessment is still limited to the data achieved in lab-scale, further research and more in-depth feasibility assessments beyond the pilot scale will be required for commercial industry applications.
Scientific publications
Huang, Q., C. H. Niu* and A. Dalai. 2018. Production of anhydrous biobutanol using a biosorbent developed from oat hulls. Submitted to Chemical Engineering Journal, under review.
Ghanbari, S., and C.H. Niu. 2018. Characterization of a High Performance Biosorbent for Natural Gas. Submitted to Energy and Fuels, under review.
Dhabhai, R., C.H. Niu* and A Dalai. 2018. Agricultural byproducts based biosorbents for purification of bio-alcohols: A review. Bioresources and Bioprocessing. 5:37. DOI: 10.1080/00986445.2017.1412307.
Jayaprakash, D., R. Dhabhai, C.H. Niu* and Ajay K. Dalai. 2017. Selective Water Removal by Sorption from Butanol–Water Vapor Mixtures: Analyses of Key Operating Parameters and Site Energy Distribution. Energy and Fuels, 31(5): 5193–5202. DOI: 10.1021/acs.energyfuels.7b00310.
Dhabhai, R., C.H. Niu* and A Dalai. 2018. Drying of non-polar gas in a pressure swing adsorption process using canola meal biosorbents. Asia-Pacific Journal of Chemical Engineering. DOI: 10.1002/apj.2232.
Dhabhai, R., C.H. Niu* and A Dalai. 2018. Selective Adsorption of Water from Aqueous Butanol Solution Using Canola Meal Based Biosorbents. Chemical Engineering Communication, 205(5): 637-646. DOI: 10.1080/00986445.2017.1412307.
Yan, B. and C.H. Niu*. 2017. Pretreating Biosorbents for Purification of Bioethanol from Aqueous Solution. International Journal of Green Energy, 14(3):245-252. DOI:10.1080/15435075.2016.1254087.