A key focus of microalgae-based fuels/chemicals research and development has been on the lipids that many strains generate, but recent studies show that solely recovering these lipids may not be cost competitive with fossil-derived processes. However, if the carbohydrates can also be recovered and ultimately converted into useful chemical intermediates, this may improve the economics for microalgae-based sustainable product technologies. In the present work, physical and chemical pre-treatments were performed on the Chlorella vulgaris microalgae strain to recover the carbohydrates from the biomass primarily in the form of glucose and galactose. The effects of temperature, acid concentration, microalgae solid-to-liquid loading, and hydrolysis time on carbohydrate hydrolysis and recovery was explored to identify optimum conditions. The highest recovery of total carbohydrates, 90 ± 1.1 wt% at 95% confidence which represents 40 wt% of the initial biomass, was obtained using temperature-assisted weak-acid extraction. Sequential extraction of carbohydrates and lipids was then explored. The highest recovery of total lipids was 71 ± 1.8 wt%, which represents 22 ± 0.9 wt% of the initial biomass. The sequential extraction of carbohydrates followed by lipids resulted in an overall recovery of 60 ± 1.6 wt% of the initial biomass, which is higher than current single product recovery strategies. These results suggest that adding carbohydrate recovery may be a viable strategy for overcoming a major economic hurdle to microalgae-derived chemical and fuel production by significantly increasing the yield of usable materials from microalgae biomass.

The emission of toxic metals from combustion of fossil fuels and wastes is an important global environmental issue. Toxic metals, such as arsenic, selenium, mercury, chromium, lead and cadmium are present in coals and in many municipal and industrial wastes. This paper is concerned with the partitioning of these metals during combustion, and with the mitigation of their effect on the environment using high temperature sorbents. The paper is divided into three parts. First, the partitioning of arsenic and selenium during coal combustion in a 17kW laboratory down-fired furnace is discussed and appropriate mechanisms identified. Second, the speciation of mercury and chromium during combustion is addressed, through special experiments on a 73kW refractory lined combustor. Third, experimental results on the sorption of individual and multiple metals on sorbents are presented. These sorbents were kaolinite and lime, and were injected directly into flue gas containing lead and cadmium metals, which had vaporized in the main flame. Results suggest that toxic metals from coal and waste combustion can be associated with lime or kaolinite sorbents, and that for some multiple metal mixtures, designer sorbents containing calcium, aluminum, and silicon might be useful to capture them and render them environmentally benign.

Offering a modern, process-oriented approach emphasizing process control scheme development instead of extended coverage of LaPlace space descriptions of process dynamics, Designing Controls for the Process Industries focuses on aspects that are most important for contemporary practical process engineering and reflects the industry's use of digital distributed control-based systems. The second edition now features 60 tutorial videos demonstrating solutions to most of the example problems. Instead of starting with the controller, the book starts with the process and moves on to how basic regulatory control schemes can be designed to achieve the process objectives while maintaining stable operations. In addition to continuous control concepts, process and control system dynamics are embedded into the text with each new concept presented. The book alsoincludes sections on batch and semi-batch processes and safety automation within each concept area. It discusses the four most common control techniques: control loop feedback, feedforward, ratio, and cascade, and discusses application of these techniques for process control schemes for the most common types of unit operations. It also discusses more advanced andless commonly used regulatory control options such as override, allocation, and split range controllers; includes an introduction to higher-level automation functions; and provides guidance for ways to increase the overall safety, stability, and efficiency for many process applications. It introduces the theory behind the most common types of controllers used in the process industries and provides various additional plant automation-related subjects. The new edition also includes new homework problems and examples, including multiple choice questions for flipped classes, information about statistical process control, and a new case study that documents the development of regulatory control schemes for an entire process area. Aimed at chemical engineering students in process control courses, as well as practicing process and control engineers, this textbook offers an alternative to traditional texts and offers a practical, hands-on approach to design of process controls. PowerPoint lecture slides, multiple-choice quiz questions for each chapter, and a solutions manual are available to qualifying instructors. Tutorial-style videos for most of the text examples are available for all readers to download.

Previous research has identified attractive chemical pathways to form levulinic–lactic acid mixtures from corn stover. Unfortunately, there is little market demand for levulinic acid, so conversion into more useful chemicals is needed. Presented herein are the results from a study to translate and optimize two lab-scale reactions that can be used to transform levulinic acid into a useful platform chemical, 2-methyltetrahydrofuran (2-MeTHF), to the continuous bench-scale. 2-MeTHF is an important monomer for the production of liquid polyols, which are used in polymer foam products. First, a hydrogenation reaction takes place, transforming levulinic acid into γ-valerolactone (GVL) by reaction with isopropanol using a Zr-β-zeolite catalyst. Next, the GVL is reacted with hydrogen to form 2-MeTHF utilizing a CuO/Al2O3 catalyst. Both reactions were optimized in bench-scale continuous flow reactors designed to produce 0.613 kg/h of 2-MeTHF from an initial feed of 1.02 kg/h of levulinic acid with a single pass conversion of 81 mol%.

Microalgae represent a promising source of triglycerides and free fatty acids, synthesized in the form of lipids, for use in renewable fuels and chemicals. One challenge is the ability to efficiently recover the lipids from within the microalgae cell. Although various techniques have been studied individually, a comprehensive study of extraction techniques using consistent experimental and analytical methodology is missing. This study aims to provide this unifying comparison using the common microalgae strain Chlorella vulgaris. The factors that were surveyed and then optimized to achieve maximum extraction efficiency included the solvent type; mechanical pre-treatment using a ball mill at a variety of grinding speeds; microalgae-to-solvent ratio; extraction facilitated by microwave; extraction facilitated by sonication; extraction facilitated using increased temperature; and extraction facilitated by in situ transesterification to convert the lipids into esters prior to extraction. The optimum conditions determined during these studies were utilizing methanol as the solvent, with ball mill pretreatment at a grinding speed of 500 rpm, and a 1:9 microalgae to solvent ratio. When used in combination with microwave-assisted extraction at a temperature of 140 °C, approximately 24 wt% of the initial lipids were recovered. Recoveries of over 70 wt% were obtained without a microwave at extraction temperatures of over 200 °C.

Steam is the typical working fluid used to drive turbo-generators in coal-fired power plants. It is effective as a working fluid, but some of its energy is lost when it is condensed. One method to recover more energy is to add a power recovery cycle (PRC) using a more volatile secondary working fluid (SWF). This paper details a techno-economic analysis of adding a PRC to a 500 MW lignite coal-fired power plant. After identifying the three most attractive SWFs, a baseline plant was developed to assess PRC addition utilizing either benzene, methanol, or hydrazine. The processes were designed for 3.2 million MTcoal/yr. An AACS Class 4 factored broad capital cost estimate and comparable estimates of the operating costs and revenues were developed to evaluate the feasibility of each alternative. Adding a benzene, methanol, or hydrazine PRC will produce an additional 59, 34, and 49 MW, respectively. The most significant challenge is the size and capital cost of the PRC equipment required. The benzene, methanol, and hydrazine processes had 2019 NPVs@12% of -$32, -$59, and +$35 million ± 40%, respectively. Thus, a PRC may be profitable at current or modest increases to U.S. Upper Midwest electricity prices of around $0.0667/kWh.

Composites of functionalized single walled carbon nanotubes (SWCNTs) and gold nanoparticles (Au NPs) of ≈15 nm diameter were drop-cast on a printed circuit board (PCB) substrate equipped with interdigitated electrodes to make a hybrid thin film. Addition of Au NPs decorated the surface of SWCNTs networked films and acted as catalysts which resulted into an enhanced sensitivity and low ppb concentration detection limit. The compositions of the film were characterized by scanning electron microscope (SEM). SWCNTs clusters were loaded with various amount of Au NPs ranging from 1–10% (by weight) and their effect on Nitric oxide (NO) sensitivity was studied and optimized. Further, the optimized composite films were tested in both air and nitrogen environments and as well as over a wide relative humidity range (0–97%). Sensors were also tested for the selectivity by exposing to various gases such as nitrous oxide, ammonia, carbon monoxide, sulfur dioxide and acetone. Sensitivity to NO was found much higher than the other tested gases. The advantage of this sensor is that it is sensitive to NO at low ppb level (10 ppb) with estimated response time within 10 s and recovery time around 1 min, and has excellent reproducibility from sensor to sensor and works within the wide range of relative humidity (0–97%).

ADVERTISEMENT RETURN TO ISSUEPREVCorrespondenceNEXTReply to "The Novelty of a Two-Step Aromatization Process"Swapnil FegadeSwapnil FegadeDepartment of Chemical Engineering, University of North Dakota, 241 Centennial Drive, Stop 7101, Grand Forks, North Dakota 58202-7101, United StatesMore by Swapnil Fegade, Brian TandeBrian TandeDepartment of Chemical Engineering, University of North Dakota, 241 Centennial Drive, Stop 7101, Grand Forks, North Dakota 58202-7101, United StatesMore by Brian Tande, Alena KubátováAlena KubátováDepartment of Chemistry, University of North Dakota, P.O. Box 9024, Grand Forks, North Dakota 58202, United StatesMore by Alena Kubátováhttp://orcid.org/0000-0002-2318-5883, Wayne Seames*Wayne SeamesDepartment of Chemical Engineering, University of North Dakota, 241 Centennial Drive, Stop 7101, Grand Forks, North Dakota 58202-7101, United States*More by Wayne Seameshttp://orcid.org/0000-0003-3133-1702, and Evguenii KozliakEvguenii KozliakDepartment of Chemistry, University of North Dakota, P.O. Box 9024, Grand Forks, North Dakota 58202, United StatesMore by Evguenii KozliakCite this: Ind. Eng. Chem. Res. 2021, 60, 10, 4191Publication Date (Web):March 2, 2021Publication History Published online2 March 2021Published inissue 17 March 2021https://pubs.acs.org/doi/10.1021/acs.iecr.1c00691https://doi.org/10.1021/acs.iecr.1c00691article-commentaryACS PublicationsCopyright © 2021 American Chemical Society. This publication is available under these Terms of Use. Request reuse permissions This publication is free to access through this site. Learn MoreArticle Views458Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail PDF (418 KB) Get e-AlertscloseSUBJECTS:Aromatic compounds,Physical and chemical processes Get e-Alerts

Recent measurements in scenarios representative of second generation atmospheric pressure oxy-coal combustion systems have shown a significant increase in ash deposition rates in comparison to combustion in air. However, the causative mechanisms behind this increase have not been well understood. To fill this void, well-characterized experiments including fuel and deposit particle size distributions (PSDs) were coupled with highly resolved numerical simulations to isolate the aerodynamic effects impacting the deposition process such that mechanisms could be hypothesized. Three combustion scenarios (AIR, OXY27, OXY70) spanning a factor of three variation in flue gas volumetric flow rates were simulated and the deposition characteristics (impaction rates, deposit PSD, temperature, residence times, capture rates) tracked/predicted using a customized deposition module. The measured deposit PSD was significantly different from the PSD of the parent fuel indicating significant physio-chemical transformations (coalescence and particle growth in particular) at play. The use of simplistic modeling approaches (swelling parameter variations) to model particle growth led to inaccurate deposit ash PSD and rate predictions. A more satisfactory agreement between the measurements and simulations was obtained when the functional form of the parent fuel PSD (spread parameter) was modified to conform closely to the deposit PSD while still ensuring the fidelity of temperature and velocity predictions. Based on the measured ash compositions, identical capture criteria were employed across all three scenarios. This study further supports the theory that the ash deposition rates in these systems are dominated by aerodynamic effects with the ash PSD playing a dominant role.

A readily available source for renewable fuels and chemicals is corn stover, which consists of the leftover stalks, leaves, husks, and cobs from the corn plant and makes up nearly half of the yield of a corn crop. Common practice is to pretreat it with sulfuric acid to break down the hemicellulose, releasing xylose, followed by enzymatic hydrolysis to convert the cellulose into glucose. Using a Sn-Beta catalyst, it is possible to convert these monomeric sugars into lactic, levulinic, formic, and acetic acids. This paper presents the results of a techno-economic analysis (TEA) of the commercial feasibility of producing these acids from corn stover. Two preliminary process designs were evaluated which represent two separate reaction yields: a balanced yield of both lactic and levulinic acids and the yields from a co-catalysis with CaSO4 to produce primarily lactic acid. Both process designs are scaled to process 230,000 MT/year of corn stover. An AACS Class 4 factored broad capital cost estimate and comparable estimates of operating costs and revenues were used to generate cash flow sheets to evaluate the economic feasibility of both options. The balanced product process has an estimated NPV@20% = $3.3 million ± 40%, while the CaSO4-facilited process has an NPV@20% = $110 million ± 40% (January 2019 basis). A major hurdle for both processes is the demand for levulinic acid. The balanced product process will produce 135% of the expected global demand and the CaSO4-facilitated alternative will meet 31% of the demand. For the demand to meet production, advances in levulinic acid applications are needed. However, the attractive economics suggest that these technologies warrant further development towards commercialization.

The production of microalgae as a fatty acid oil resource for use in biofuels production is a widespread research topic at the lab scale. Microalgae contain a higher lipid content on a dry-weight basis compared to oilseeds such as soybeans. Additionally, the growth and cultivation cycle of microalgae is 15 days, in comparison to soybeans, for which the cycle occurs once or twice annually. However, to date, it has been uneconomical to produce microalgae oils in a world-scale facility due to limitations in cultivating microalgae at commercial scales. Recent developments suggest that the use of heterotrophic microalgae may be economically feasible for large-scale oil production. To assess this feasibility, a comparative scoping study was performed analysing the feasibility of an industrial-scale process plant for the growth and extraction of oil from microalgae. Processes were developed at the preliminary design level using heterotrophic subspecies and autotrophic subspecies of Chlorella vulgaris. AACE Class 4 cost estimates and economic analyses were performed. This study concludes that processes based on heterotrophic microalgae are more likely to reach economic feasibility than processes using autotrophic microalgae. However, a few barriers still remain to achieving free-market economic viability.

The effect of the combustion temperature on the mobility of three semi-volatile trace elements (TEs), arsenic, selenium, and antimony, from the fly ash generated from the combustion of a pulverized sub-bituminous coal was assessed using a modified toxicity characteristic leaching procedure protocol. Multiple sets of size-segregated fly ash samples were collected from the combustion of a Powder River Basin sub-bituminous coal in a laboratory-scale self-sustaining combustor at peak combustion temperatures of 1623, 1673, and 1723 K. TEs were extracted from representative ash samples from each particle size mode (submicron, fine fragment, and bulk) in acidic (pH 2.88), neutral (pH 7), and basic (pH 11) solvents. TE concentrations in each solvent were compared to the concentrations from complete digestion to determine fly ash TE mobility under various conditions. It was observed that an increase in the peak combustion temperature increased the distribution of minor elements and TEs in the smaller size modes but had no significant effect on TE mobility for a given size mode under a particular leaching fluid. For all three TEs, solubility decreased with increasing pH for most size modes. In a majority of cases, the fraction present in the smaller sized submicron and fine fragment particles was found to be more leachable compared to the larger bulk particles.

In the present study, the use of Sn-Beta zeolite to facilitate the conversion of lignocellulosic biomass-derived glucose and xylose into lactic and levulinic acid was explored. The reactions were carried out in a batch reactor using water as the solvent. Water is the preferred solvent over methanol as it reduces downstream product acid recovery and purification complexity. Optimization experiments were performed for reaction temperature and residence time. Under optimized reaction conditions, the Sn-Beta facilitated reaction of a pure sugar solution resulted in lactic acid yields of 13 and 19 wt% of inlet carbon of glucose and xylose, respectively, plus levulinic acid yields of 18 and 0.8 wt%, respectively. When actual biomass-derived sugar solutions were tested, the yields of lactic acid were significantly higher than those from the optimized model solution experiments with lactic acid yields of 34 wt%. These biomass-derived sugar solutions contained residual levels of CaSO4 from the neutralization step of the hydrolysis process. Further experiments were performed to examine the potential effects from CaSO4 contributing to this increase. It was found that the sulfate ions increased the Brønsted basicity and the calcium increased the Lewis acidity of the reaction solution, and that the combination of both effects increased the conversion of the original sugars into lactic acid. These effects were verified by testing other organic bases to isolate the Brønsted acid neutralization effect and the Lewis acid enhancement effect. The addition of CaSO4 resulted in attractive lactic acid yields, 68 wt% and 50 wt% of inlet carbon from pure glucose and xylose solutions, respectively. Increasing the actual corn stover and forage sorghum derived sugars concentration (in water) allowed lactic acids yields of greater than 60 wt% to be achieved. When the optimized Sn-Beta reaction system was applied to corn stover and forage sorghum mixtures, it was found that the ratio of lactic-to-levulinic acid generated was inversely dependent upon the glucose-to-xylose ratio in the recovered sugar mixture.

Coal fueled the Industrial Revolution and the global expansion of electrification in the 20th century. In the 21st century, coal use has declined in North America and Europe, but continues to increase in Asia. Coal contains many of the elements of the Periodic Table, in percent-levels or in trace amounts (ppm, ppb). The impact of many of these elements on the environment via air and water discharges from coal-fired plants has been studied with decades of research on their chemical transformations within combustion systems and on their fates upon reintroduction into the environment. The transformations of the trace elements present in coal burned during combustion can be categorized as thermal volatilizations from the coal in the furnace; thermal decomposition of trace element compounds inside the coal; encapsulation inside ash structures through high-temperature vitrification; oxidation of the trace elements with the myriad species contained in flue gas through gas phase (homogeneous) reactions or catalytic (gas-solid) reactions; adsorption and/or reactions with active sites on entrained fly ash particulates contained in the flue gas; and absorption into solutions. These transformations can, in many cases, impact the fraction of these trace elements that are removed by various pollution control devices compared to the fraction released into the environment. The sampling and measurement of trace elements, in the inlet coal, outlet flue gas, aqueous scrubber solutions, and ash matrices, represents a significant challenge. This review focuses on the behavior of trace elements in industrial coal combustion systems with an emphasis on what has been learned over the past century uniquely related to the use of coal in boilers for electricity and heat production. Key accomplishments in measurement, modeling and control of trace element emissions in coal-fired systems are highlighted.

Molecular beam (MB) time-of-flight mass spectrometry has been used to investigate thermal decomposition of triolein, to reveal the mechanisms of low temperature soot/coke formation characteristic for triglycerides (TGs). Mass detected pyrolysis products were observed at incremented temperatures using both VUV single photon ionization (general product detection) and REMPI based selective detection of aromatic products. To augment the simple mass characterizations, we have employed stoichiometric considerations; we have supplemented the analysis further by using the detailed information available from product analysis of batch reactor TG cracking. Both the VUV photoionization and batch reactor studies indicated that formation of C7-sized stable products is a marker of significant triolein decomposition that is coupled with PAH formation. A significant fraction of the C7 species observed likely formed as a result of a C-C bond scission at the allylic position to the ω-9 double bond of oleic acid. REMPI detection indicated a high specificity for PAH formation at three distinct molecular weight values, 276, 352 and 444 amu (the latter being a fullerene precursor). The stoichiometric analysis has shown that these PAHs likely arise from condensation reactions of either C7- or C8-sized fragments (three, four and five, respectively). The C8-sized intermediate would become essential whenever the PAH product of C7 fragment condensation contained an odd number of carbon atoms, resulting in a less stable aromatic structure with an incomplete double bond conjugation. MB experiments involving either addition or in situ generation of hydrogen resulted in an enhancement of lower molecular weight PAH formation, i.e., a decrease in the effective number of condensing fragments. In contrast, an increase in temperature yielded the opposite effect.