thermal regeneration
Recently Published Documents


TOTAL DOCUMENTS

266
(FIVE YEARS 62)

H-INDEX

31
(FIVE YEARS 6)

Membranes ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 48
Author(s):  
Pauline Zimmermann ◽  
Simon Birger Byremo Solberg ◽  
Önder Tekinalp ◽  
Jacob Joseph Lamb ◽  
Øivind Wilhelmsen ◽  
...  

The Reverse electrodialysis heat engine (REDHE) combines a reverse electrodialysis stack for power generation with a thermal regeneration unit to restore the concentration difference of the salt solutions. Current approaches for converting low-temperature waste heat to electricity with REDHE have not yielded conversion efficiencies and profits that would allow for the industrialization of the technology. This review explores the concept of Heat-to-Hydrogen with REDHEs and maps crucial developments toward industrialization. We discuss current advances in membrane development that are vital for the breakthrough of the RED Heat Engine. In addition, the choice of salt is a crucial factor that has not received enough attention in the field. Based on ion properties relevant for both the transport through IEMs and the feasibility for regeneration, we pinpoint the most promising salts for use in REDHE, which we find to be KNO3, LiNO3, LiBr and LiCl. To further validate these results and compare the system performance with different salts, there is a demand for a comprehensive thermodynamic model of the REDHE that considers all its units. Guided by such a model, experimental studies can be designed to utilize the most favorable process conditions (e.g., salt solutions).


Author(s):  
В.В. ВАЩЕНКО ◽  
Е.Ю. РУДЕНКО

Рассмотрены исследования в области использования отработанного кизельгура (диатомита) пивоваренного производства. Ресурсы кизельгура ограничены, его утилизация осуществляется захоронением на полигонах и требует больших затрат, поэтому поиск возможностей использования кизельгурового шлама экономически выгоден, а их внедрение на производстве будет способствовать улучшению экологии. Кизельгуровый шлам может подвергаться термической регенерации на специальных установках, после чего снова использоваться в процессе фильтрации пива. Использование регенерата отработанного кизельгура в качестве добавки в рацион кур-несушек и цыплят-бройлеров увеличивает их продуктивность и качество получаемых продуктов. Также возможно приготовление на основе отработанного кизельгура добавки к корму коров. Кизельгуровый шлам может применяться для очистки почвы от нефтепродуктов, а также воды от гербицида параквата и красителя метиленового синего. Как компонент строительных смесей отработанный кизельгур улучшает их свойства. Researches in the using of the fulfilled diatomaceous earth from the brewing industry are considered. Diatomaceous earth resources are limited, its disposal is burial in landfills and costly, so search the possibilities of the use of kieselguhr sludge cost-effective, and their implementation in manufacturing will contribute to improving the environment. Kieselguhr sludge can be subjected to thermal regeneration in special plants, and then used again in the filtering process of beer. The using of reclaim of the fulfilled diatomaceous earth as a supplement in the diet of laying hens and broiler chickens increases their productivity and the quality of the products. Also the preparation of additive based on spent diatomaceous earth to the feed of cows is possible. Kieselguhr sludge can be used for cleaning soil from petroleum products and water from the herbicide paraquat and dye methylene blue. As a component of construction waste mixtures of the fulfilled diatomaceous earth improves their properties.


2021 ◽  
Vol 2042 (1) ◽  
pp. 012094
Author(s):  
David Sauter ◽  
Manuel Hunziker ◽  
Joachim Poppei ◽  
Fabien Cochand ◽  
Markus Hubbuch ◽  
...  

Abstract To prevent undercooling of the ground in densely populated areas, regeneration of borehole heat exchangers (BHEs), for example by solar thermal heat, may become necessary. However, the usable roof area is often small compared to the building’s heat demand, especially in urban areas. It was investigated how much regeneration is possible in districts that are supplied entirely by heat pumps with BHEs. Example buildings were modelled based on the buildings of two districts in Zurich. Uncovered PVT collectors and glazed flat-plate collectors were used as regeneration sources. The possible regeneration was determined in a simulation process that included the effects of mutual influences between the BHEs of neighbouring buildings. As expected, glazed flat-plate collectors allow for more regeneration than uncovered PVT collectors. For full regeneration, the required usable roof area relative to the annual heat demand is about 1.8m2/MWh for PVT and 1.2m2/MWh for flat-plate collectors. Large buildings often do not provide sufficient roof area for full regeneration. A sustainable heat supply of the entire district with regenerated BHEs can be possible in suburban neighbourhoods, if the bigger buildings are distributed rather evenly. In urban neighbourhoods, areas may exist in which solar thermal regeneration alone is not sufficient.


2021 ◽  
Vol 11 (21) ◽  
pp. 9851
Author(s):  
Frédérick de Meyer ◽  
Charles Bignaud ◽  
Bénédicte Poulain

Removing CO2 from natural gas or biogas in the presence of H2S is technically challenging and expensive as it often requires separation of both acid gases from the gas, typically using an aqueous amine solution, followed by separation of CO2 from H2S and conversion of H2S into solid S. In this work, the proof of concept of electrochemical, instead of thermal, regeneration of an aqueous amine solution is developed. This invention might be a very promising technology and has several advantages. It has H2S versus CO2 selectivity of 100%, can directly convert H2S into S and H2, and is economically competitive with CO2 desorption energy around 100 kJmol−1 and H2S conversion around 200 kJmol−1. If renewable energy is used for electrochemical regeneration, CO2 emissions due to the CO2 capture process can be significantly reduced.


Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 5958
Author(s):  
Xusheng Ren ◽  
Zhiliang Ou ◽  
Bang Wu

The activated coke is a promising support for catalysts, and it is important to study the performance of the activated coke catalyst on the removal of NOx. In the current research, a series of the activated coke-supported Mn–Cu catalysts are prepared by the incipient wetness impregnation method. The effects of the molar ration of Mn/Cu, the content of Mn–Cu, the calcination temperature, and reaction space velocity on NO conversion are investigated, and it was found that the 8 wt.% Mn0.7Cu0.3/AC had the best catalytic activity when the calcination temperature was 200 °C. The existence of SO2 caused the catalyst to deactivate, but the activity of the poisoning catalyst could be recovered by different regeneration methods. To uncover the underlying mechanism, BET, XPS, XRD, SEM and FTIR characterizations were performed. These results suggested that the specific surface area and total pore volume of the poisoning catalyst are recovered and the sulfite and sulfate on the surface of the poisoning catalysts are removed after water washing regeneration. More importantly, the water washing regeneration returns the value of Mn3+/Mn4+, Cu2+/Cu+, and Oα/Oβ, related to the activity, basically back to the level of the fresh catalyst. Thus, the effect of water washing regeneration is better than thermal regeneration. These results could provide some helpful information for the design and development of the SCR catalysts.


Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 5031
Author(s):  
Xia Song ◽  
Nana Nyarko Mensah ◽  
Yuting Wen ◽  
Jingling Zhu ◽  
Zhongxing Zhang ◽  
...  

Water pollution by various toxic substances remains a serious environmental problem, especially the occurrence of organic micropollutants including endocrine disruptors, pharmaceutical pollutants and naphthol pollutants. Adsorption process has been an effective method for pollutant removal in wastewater treatment. However, the thermal regeneration process for the most widely used activated carbon is costly and energy-consuming. Therefore, there has been an increasing need to develop alternative low-cost and effective adsorption materials for pollutant removal. Herein, β-cyclodextrin (β-CD), a cheap and versatile material, was modified with methacrylate groups by reacting with methacryloyl chloride, giving an average degree of substitution of 3 per β-CD molecule. β-CD-methacrylate, which could function as a crosslinker, was then copolymerized with acrylamide monomer via free-radical copolymerization to form β-CD-polyacrylamide (β-CD-PAAm) hydrogel. Interestingly, in the structure of the β-CD-PAAm hydrogel, β-CD is not only a functional unit binding pollutant molecules through inclusion complexation, but also a structural unit crosslinking PAAm leading to the formation of the hydrogel 3D networks. Morphological studies showed that β-CD-PAAm gel had larger pore size than the control PAAm gel, which was synthesized using conventional crosslinker instead of β-CD-methacrylate. This was consistent with the higher swelling ratio of β-CD-PAAm gel than that of PAAm gel (29.4 vs. 12.7). In the kinetic adsorption studies, phenolphthalein, a model dye, and bisphenol A, propranolol hydrochloride, and 2-naphthol were used as model pollutants from different classes. The adsorption data for β-CD-PAAm gel fitted well into the pseudo-second-order model. In addition, the thermodynamic studies revealed that β-CD-PAAm gel was able to effectively adsorb the different dye and pollutants at various concentrations, while the control PAAm gel had very low adsorption, confirming that the pollutant removal was due to the inclusion complexation between β-CD units and pollutant molecules. The adsorption isotherms of the different dye and pollutants by the β-CD-PAAm gel fitted well into the Langmuir model. Furthermore, the β-CD-PAAm gel could be easily recycled by soaking in methanol and reused without compromising its performance for five consecutive adsorption/desorption cycles. Therefore, the β-CD-PAAm gel, which combines the advantage of an easy-to-handle hydrogel platform and the effectiveness of adsorption by β-CD units, could be a promising pollutant removal system for wastewater treatment applications.


2021 ◽  
Vol 43 (7) ◽  
pp. 537-546
Author(s):  
Heejong Son ◽  
Sangki Choi ◽  
Byungryul An ◽  
Hyejin Lee ◽  
Hoon-Sik Yoom

Objectives : The purpose of this study was to evaluate the effect of increasing the number of regeneration of granular activated carbon (GAC) on the adsorption capacity of natural organic matter (NOM), and to suggest the technical process options associated the limit number of regeneration and the efficient use of regenerated GAC.Methods : The physicochemical properties of virgin and thermally regenerated GAC were analyzed. To evaluate the NOM adsorption capacity of virgin- and regenerated-GAC, five laboratory-scale columns packed with virgin- and regenerated-GAC were used for treating effluent from pilot-scale drinking water treatment facility. The NOM concentration in the influent and the effluent treated by each column was analyzed by LC-OCD (liquid chromatography-organic carbon detector) to evaluate the adsorption capacity of each NOM fractions (humic substances (HS), building blocks (BB), low molecular weight organics (LMWs)).Results and Discussion : Due to the change in the pore structure of GAC by thermal regeneration, the volume of micropores (< 2 nm) decreased, while the volume of mesopores (> 2 nm) increased. The volume ratio of micropore in virgin-GAC was about 60%, but it gradually decreased as the number of regenerations increased, resulting that the volume ratio of micropore in the 5th-regenerated (5th-Re) GAC decreased to 23%. On the other hand, the volume ratio of mesopore increased in proportion to the number of regenerations from 40% of the virgin GAC to 77% of the 5th-Re-GAC. The DOC adsorption capacities of the regenerated GACs were higher than that of virgin GAC, and the DOC adsorption capacity increased as the number of regenerations increased. As a result of comparing the adsorption capacity of virgin- and regenerated-GAC by NOM fractions, the adsorption capacity of high molecular weight NOM, such as HS, increased by 1.5 to 1.7 times as the number of regenerations increased. In contrast, the adsorption capacity of low molecular weight NOM, such as BB and LMWs, decreased by 78% and 48% as the number of regeneration increased. The limit number of regeneration was evaluated based on that the adsorption capacity (qe) of each NOM fractions keep over than 70% relative to its virgin GAC. As a result, the adsorption capacity for low molecular weight NOM was greatly reduced in GAC regenerated over than 3rd time, so that the 2nd-Re-GAC was valid to keep 70% removal of whole NOM fractions. Low adsorption of low molecular weight NOM (BB and LMWs) by 3rd-Re-GAC could be complemented by using together with virgin-GAC, and low adsorption of high molecular NOMs (HS) could be compensated as well.Conclusions : Due to the change in the pore structure of GAC by thermal regeneration, the DOC adsorption capacity was higher in regenerated GAC than its virgin-GAC, and the adsorption capacity of DOC and high molecular weight NOM (HS) was enhanced as the number of regenerations increased. On the other hand, the pore volume of micropore was reduced by regenerations, and in more than 3rd times regenerations, the adsorption capacity of low molecular weight NOMs (BB and LMWs) was reduced by less than 70% compared to its virgin GAC, so that 2nd-Re-GAC was suggested for suitable GAC. When using a mixture of virgin- and 3rd-Re-GAC, low adsorption of low molecular weight NOM (BB and LMWs) by 3rd-Re-GAC could be complemented by using together with virgin-GAC, and low adsorption of high molecular NOMs (HS) could be compensated as well.


Sign in / Sign up

Export Citation Format

Share Document