Optimum Regeneration Temperature Research Articles

Desorption research and energy consumption assessment of a porous liquids impregnated by monoethanolamine (MEA)

Porous liquids (PLs), as new carbon capture materials, have great application potential in gas separation, gas storage, catalysis, etc. Herein, it was reported a new Type 3 porous liquids (T3PLs) based on the rational coupling of MEA-modified porous silica nano-spheres (PSNs) as porous hosts with 2-[2-(dimethylamine) ethoxy]ethanol (DMEE) as the fluid medium. A method was specifically developed to evaluate the regeneration energy of T3PLs. It was found energy consumption followed the order: the sensible energy > solvent evaporation > reaction heat energy for 50 % MEA-PSNs (10 %)/DMEE. Further study revealed that the optimum regeneration temperature of the absorbent was 80 °C and the corresponding regeneration energy was 4.04 GJ/ton CO2, which was much smaller than the regeneration energy of commercial absorbent 5 M MEA (9.54 GJ/ton CO2). The regeneration performance revealed the average absorption rate and the average desorption rate decreasing by only 9.3 % and 11.8 % after nine cycles. All the results indicated the T3PLs in the present work were energy-saving and had potential applications in CO2 capture.

Insight into the enhancing activity and stability of Ce modified V2O5/AC during cyclic desulfurization-regeneration-denitrification

Cyclic desulfurization-regeneration-denitrification over carbon-based catalysts is a promising technology for SO2 and NOx simultaneous elimination in steel industry. Regeneration is imperative to the long-term operation of the process, while the research is limited. In this work, Ce modified V2O5/AC catalyst (CeVOx/AC) with higher desulfurization and denitrification activity was prepared and the effect of cyclic regeneration was investigated. Results illustrated that the desulfurization and denitrification activity of CeVOx/AC gradually improved with increasing the regeneration cycles at the optimum regeneration temperature of 470 °C in N2. The increasing Ce3+, V5+ and oxygen vacancies, enhanced surface acidity and improved redox ability contributed to the catalytic activity of regenerated catalysts. For desulfurization, more SO2 transformed into H2SO4 rather than to metal sulfates after cyclic regeneration. For denitrification, the improved redox ability accelerated the oxidation of NO to active NO2, bridged nitrites and nitrates, and the enhanced acidity facilitated the NH3 adsorption, further generating more -NH2 and promoting the SCR activity of regenerated samples. The CeVOx/AC with good activity and regenerative stability shows great application potential in steel industry for the simultaneous SO2 and NOx removal.

A Pilot‐Scale Demonstration of Mobile Direct Air Capture Using Metal‐Organic Frameworks

AbstractIt is increasingly apparent that negative emissions technologies, such as direct air capture (DAC), are required as part of the technology mix for limiting global atmospheric temperature increase. For all DAC technologies, the requisite energy for regeneration of the separation media strongly influences the overall cost of the process and therefore directly influences their likely implementation. Herein, the results of a pilot‐scale demonstration of a new metal organic framework (MOF) based technology, Airthena, incorporated within a mobile unit for distributed deployment, are reported. Careful preparation of a MOF nanocomposite results in a CO2‐selective sorbent with fine‐tuned kinetic and thermodynamic properties. An optimum regeneration temperature of 80 °C is achieved, along with strong repellence of water vapor during the adsorption process. Taken together, this demonstrator has delivered one of the lowest regeneration energy consumptions, 1.6 kWh kg‐CO2−1 with output purity of 70–80%. This equates to an operational cost of $35–$350 ton‐CO2−1 depending on the source of regeneration energy. Over the duration of the pilot‐scale testing, the demonstrator captures a total of 8 kg of CO2 over 2680 cycles.

Dynamic simulation and multi-objective optimization of a solar-assisted desiccant cooling system integrated with ground source renewable energy

This study presents a dynamic simulation-optimization of a solar-assisted desiccant cooling system integrated with a ground source heat exchanger (SDCS-GSHE). Solar and ground source energies are used for regenerating the desiccant wheel (DW) and a pre-cooling process, respectively. The system is considered as an alternative for extremely hot and humid regions. Determinant design parameters of the SDCS-GSHE that are associated with the DW, GSHE, and solar loop components directly affect the system behavior and, consequently, the provided thermal comfort, as well as the solar fraction (SF). Therefore, a multi-objective genetic algorithm optimization is invoked to determine all viable optimum design parameters to set up the system. Also, an economic assessment of the system is performed to demonstrate its economic feasibility. With the results, the optimum regeneration temperature, number of ground boreholes, collector area can be determined based on the required level of thermal comfort and the SF. The results reveal that, in the absence of the GSHE, the system cannot provide thermal comfort in extremely humid regions even with high regeneration temperatures (around 120 °C). Instead, using the GSHE dramatically improves the established thermal comfort. For regeneration temperatures below 90 °C, it is determined that the total necessary energy can be supplied entirely by solar energy. For the best case, in which the system successfully provides thermal comfort, the cost payback period for the system is found to be 5.7 years.

Effects of regeneration conditions on sulfated CuSSZ-13 catalyst for NH3-SCR

To understand the role of regeneration conditions on sulfur-poisoned Cu/SSZ-13 catalysts for NH3-SCR, the physicochemical characterizations and NO2 conversions were investigated. The sulfur-poisoned Cu/SSZ-13 catalysts were treated at different conditions as a function of temperature and duration. TGA results revealed that regeneration at 500 °C only removed parts of sulfur spices and at 700 °C can completely remove all sulfur spices. The physical structural characterizations results illustrate that regeneration below 700 °C has no significant impact on CHA structure for Cu/SSZ-13 catalysts, while dealumination occurs on poisoned Cu/SSZ-13 when regeneration temperature is higher than 700 °C. EPR and H2-TPR results show that the sulfate decomposition and Cu migration reactions involved during regeneration and, as a result, the content of Cu2+ gradually increased as the extent of regeneration increased. The kinetics tests support that NOx conversion recovery is related to the content of Cu2+ increase during regeneration. Our study reveals that the optimum regeneration temperature is 700 °C, because severe dealumination at 750 °C inhibited Cu2+ amount increase.

Optimum regeneration temperature of a desiccant solution in a packaged liquid desiccant-assisted air conditioning unit

Recently, a package unit of liquid desiccant and an indirect and a direct evaporative cooling-assisted 100% outdoor air system (LD-IDECOAS) has been proposed. In this system, the amount of heating energy consumed to regenerate the desiccant solution is significant and should be reduced to achieve better energy conservation than that of a conventional air handling unit. The purpose of this research is to empirically investigate the optimum regeneration temperature of a lithium chloride (LiCl) desiccant solution, balancing the regeneration performance and solution heating energy consumption in the LD-IDECOAS package unit. The adiabatic cross-flow regenerator was tested in a test facility at desiccant solution temperatures of 50–90 °C. The measurement results were compared with the predicted data in the regenerator to assess the reliability of the experimental results. By balancing the regeneration performance with the solution heating energy consumption, the recommended temperature to regenerate the desiccant solution was 65 °C.

Cu-BTC synthesis, characterization and preparation for adsorption studies

In this study, several samples of Cu-BTC, a member of the MOF adsorbent family, were synthesized following synthesis routes that represent some modifications of published recipes. The effects of mixing, reaction temperature and duration, and concentrations of the precursors on the synthesized samples are discussed. The results showed that pre-mixing of the precursors’ solutions, higher dilution of the precursors, and modest reaction duration and temperature gave the most stable sample. The sample stability after several CO2 adsorption-desorption cycles was examined, and the characterization methods: XRD, TGA and SEM were used to describe selected synthesized sample and the commercial one (Basolite® C300). The thermal and mechanical processing effects as well as optimum regeneration temperature and duration were also experimentally determined (423.15 K, 8 h) for both in-house and Basolite® C300 samples.

Determination of characteristic desorption temperature by thermal-pulse regeneration: A case study of water-activated alumina system

This study demonstrates that the characteristic temperature can be determined from analysis of the effluent temperature curves from a fixed bed with adsorbents. Since the continuous, accurate measurement of temperature is considerably easier to achieve than that of isotherm and concentration, it basically provides a novel alternative approach to determine the characteristic temperature of an adsorption system. The thermal-pulse regeneration method is commonly used for conserving thermal energy in industrial applications of air prepurification units based on the temperature swing process. The peak temperature of the residual thermal pulse (RTP), namely the cooling-peak, is usually considered an important reference for evaluating the degree of regeneration completion and the level of heat utilization efficiency. A small-scale experimental system was set up, and a set of experimental runs was performed to investigate the relationships between the RTP and the regeneration efficiency. Under the same initial test-bed conditions, regeneration experiments were carried out at various injected thermal pulse (ITP) magnitudes, and an interesting result was observed; that is, as the ITP magnitude becomes smaller, the occurrence times of the cooling peaks exhibit a C-shaped variation tendency with a minimum time point. Concentration analysis indicates that the minimum time point is given by the optimum run of regeneration, and therefore the cooling-peak that gives the minimum time point is the optimum regeneration temperature (the characteristic temperature) of the adsorbent-adsorbate system.

Effect of Temperature on Regeneration of Deactivated Catalytic Reforming Catalyst (Pt/Al2O3).

Catalytic reforming process will continue play an important role in meeting the world’s demands for high octane gasoline, petrochemicals and hydrogen hence the need to embark on continued improvement of the process. This work examined the effect of temperature on the regeneration of Pt/Al2O3 catalyst employed in semi regenerative fixed bed process. Samples of the catalyst were obtained from a running process (on line) at targeted periods of 10000 and 14000 hours of operation when the catalyst would have been deactivated to a degree. The catalyst samples which have undergone deactivation were regenerated at varying temperature conditions. The range of temperature studied is 400-800°C. The deactivated, regenerated and fresh catalyst samples were analyzed using FTIR, XRD and XRF to establish the extent of deactivation and regeneration. The progress of the regeneration was also monitored with gravimetric measurement of the weight losses. The work established an optimum regeneration temperature of 500°C. The optimum temperature can be employed as is a firm basis for regeneration process control and optimization.

Characteristics and Regeneration Properties of Manganese Oxide Sorbent under O<sub>2</sub> Atmosphere

The regeneration behavior of manganese oxide sorbent under O2atmosphere was investigated in a fixed bed micro-reactor under the influence of different temperatures and O2 concentrations. The change in phase of the sulfided and the regenerated sorbents was analyzed by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques. MnS, Mn3O4 and MnSO4 were found in regenerated sorbent at 400 °C, which indicated that the regeneration of the sulfided sorbent was not complete, however, MnS was converted to Mn3O4, Mn2O3 and few MnSO4 at 800 °C. The manganese sulfate formed during the regeneration but decomposed to Mn2O3 at 800 °C. MnS reacts with O2 to form Mn3O4 and MnSO4, and then MnSO4 was decomposed at 800 °C. The results show that the optimum regeneration temperature and O2 concentration obtained from this experiment are 800 °C and 2.2 vol %, respectively, and the regeneration conversion ratio was about 95%.

Thermally Stable Amine-Grafted Adsorbent Prepared by Impregnating 3-Aminopropyltriethoxysilane on Mesoporous Silica for CO2 Capture

In this paper, an amino-functionalized adsorbent for CO2 capture was synthesized by impregnating 3-aminopropyltriethoxysilane (APTES) on mesoporous silica. Amino functional groups were chemically bonded to silica support. Because of chemical bonds, the thermal stability of this adsorbent (205 °C) was greater than that of an adsorbent prepared by impregnating polyethylenimine on the same mesoporous silica (160 °C). The cyclic CO2 loading capacity was improved by increasing adsorption temperature, reaching a maximum of 89.3 mg CO2/g at 100 °C and then reduced at temperatures above 100 °C. Optimum regeneration temperature was determined at 120 °C. The adsorbent was stable for multiple adsorption–regeneration cycles operating at adsorption temperature of 100 °C in pure CO2 and regeneration temperature of 120 °C in atmosphere, respectively. The amino-functionalized mesoporous silica is a thermally stable adsorbent with relatively high CO2 loading capacity and high optimum adsorption and regeneration temperatur...

Optimization of Design and Operational Parameters of Adsorbers for Purification of Neon-Helium Mixture

The analysis of options for arranging an adsorber composed of several sections is given. The formulas for calculating the geometric parameters of individual adsorber elements were obtained for a specified diameter of the cooling nitrogen bath. The expenditure of refrigerant and energy required to regenerate the sorbent were defined for several constructional variants. The operating costs for a single adsorber cycle were calculated. The optimum regeneration temperature was determined at which the cost of purifying the mixture is minimal.

재생 면적비가 가정용 소형 제습로터의 성능에 미치는 영향에 관한 실험적 연구

During hot and humid weather, air-conditioners consume a large amount of electricity due to the large amount of latent heat. Simultaneous usage of a dehumidifier may reduce latent heat and reduce electricity consumption. In this study, dehumidification performance was measured for a small-sized dehumidification rotor made of inorganic fiber impregnated with metallic silicate within a constant temperature and humidity chamber. Regeneration to dehumidification depends on ratio, rotor speed, room temperature, regeneration temperature, room relative humidity and frontal velocity to the rotor. Results demonstrate an optimum area ratio (1/2), rotor speed (1.0 rpm), and regeneration temperature () to achieve a dehumidification rate of 0.0581 kg/s. As the area ratio increases, the optimum rotation speed and the optimum regeneration temperature also increase. Above the optimum rotor speed, incomplete regeneration reduces dehumidification. Above the optimum regeneration temperature, increased temperature variation between regeneration and dehumidification reduces dehumidification. Dehumidification rate also increases with an increase of relative humidity, dehumidification temperature and flow velocity into the rotor.

Adsorptive removal of carbon dioxide using polyethyleneimine loaded glass fiber in a fixed bed

Low-cost glass fiber (GF) was modified by loading polyethyleneimine (PEI) using a physical impregnation method and applied as an adsorbent for CO2 capture. The structure and morphology of the PEI-loaded GF were characterized by thermogravimetic analyzer (TGA), fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The PEI-loaded GF possessed a core–shell structure. The CO2 dynamic adsorption–desorption performances were investigated in a PEI-loaded GF fixed bed. The effects of PEI loading ratio, adsorption temperature, relative humidity (RH), flow rate and bed depth (H/D) ratio were examined, and the maximal dynamic CO2 adsorption capacity was 60.04 mg g−1 with a PEI/GF ratio of 0.70 g g−1. In addition, the PEI-loaded GF was regenerated with only a slight decrease in the adsorption capacity after multiple regenerations using an optimum regeneration temperature of 100 °C. The results suggest that the PEI-loaded GF can be used as an economical adsorbent system for CO2 capture.

가정용 소형 제습로터의 성능에 대한 실험적 연구

In Korea, summer is hot and humid, and air-conditioners consume too much electricity due to large amount of latent heat. Simultaneous usage of dehumidifier may reduce the latent heat and save the electricity. In this study, dehumidification performance was measured in a constant temperature and humidity chamber for a small-sized dehumdification rotor made of inorganic fiber impregnated with metallic silicate. Variables were rotor speed, room temperature, regeneration temperature, room relative humidity and frontal velocity to the rotor. Results showed that there existed optimum rotor speed (1.0 rpm), and optimum regeneration temperature (100 o C). Above the optimum rotor speed, incomplete regeneration is responsible for reduced dehumidification. Above the optimum regeneration temperature, increased temperature difference between regeneration and dehumidification process is responsible for reduced dehumidification. The amount of dehumidification also increases with the increase of relative humidity, dehumidification temperature and flow velocity into the rotor.

연소 전 CO2포집 흡수제들의 마모특성

Attrition characteristics of <TEX>$CO_2$</TEX> absorbents for pre-combustion <TEX>$CO_2$</TEX> capture were investigated to check attrition loss of those absorbents and to determine solid circulation direction and the better <TEX>$CO_2$</TEX> absorbent. The cumulative attrition losses of two absorbents increased with increasing time. However, attrition loss under a humidified condition was lower than that under a non-humidified condition case. Between two absorbents, attrition loss of PKM1-SU absorbent was higher than that of P4-600 absorbent. The average particle sizes of the attrited particles were less than <TEX>$2.5{\mu}m$</TEX> for two absorbents under a non-humidified condition case, and therefore, we could conclude that the main mechanism of attrition for two absorbents is not fragmentation but abrasion. Based on the results from the test for the effect of humidity on the attrition loss, we selected solid circulation direction from SEWGS reactor to regeneration reactor because the SEWGS reactor contains more water vapor than regeneration reactor. Attrition loss and make-up rate of two absorbents were compared based on the results from <TEX>$CO_2$</TEX> sorption capacity tests and attrition tests. Required make-up rate of P4-600 absorbent was lower than that of PKM1-SU absorbent. However, more detail investigation on the optimum regeneration temperature, manufacturing cost, solid circulation rate, regeneration rate, and long-term sorption capacity should be considered to select the best <TEX>$CO_2$</TEX> absorbent.

The effects of operational conditions of the desiccant wheel on the performance of desiccant cooling cycles

A desiccant cooling model is developed and applied to the ventilation, recirculation, makeup, and mix modes of the operating system. The mathematical model is based on the transient coupled heat and mass transfer and is used to predict the performance of the system under various design and operational conditions. The numerical results are validated using experimental measurements. The effects of the regeneration temperature and rotational speed of the desiccant wheel on the COP and output cycle temperature are investigated. The results show the availability of an optimum regeneration temperature and rotational speed in which the output cycle temperature has a minimum value. The optimum regeneration temperature and rotational speed are detected and shown on the Psychrometric charts. Calculating these values has a significant effect on the energy use of these cycles.

Regeneration of a vanadium pentoxide supported activated coke catalyst-sorbent used in simultaneous sulfur dioxide and nitric oxide removal from flue gas: Effect of ammonia

A vanadium pentoxide supported activated coke (V 2O 5/AC) catalyst-sorbent has been reported to be very active for simultaneous removal of SO 2 and NO under dry conditions at temperatures of 200 °C and below. Regeneration of the SO 2-captured catalyst-sorbent is a key step in operation of such a process, which influences the catalyst-sorbent's SO 2 and NO removal activities, lifetime, as well as recovery of sulfur. Due to limited information in this regard, this paper studies thermal regeneration of a V 2O 5/AC catalyst-sorbent with emphases on the effect of atmosphere. The optimum regeneration temperature is found to be 380 °C in an Ar stream and 300 °C in a 5% NH 3/Ar stream. Compared to the fresh V 2O 5/AC, the V 2O 5/ACs regenerated in Ar show lower SO 2 adsorption capacities and higher NO removal activities, while the regenerated V 2O 5/ACs by 5% NH 3/Ar show higher and stable SO 2 adsorption capacities and higher NO removal activities. Two types of reactions occur during the regeneration: reduction of the adsorbed sulfur species by carbon to SO 2 and CO 2, and oxidation of carbon by oxygen in the V 2O 5/AC to CO 2. The carbon consumption of the latter is much more than that of the former in an Ar atmosphere, but fully suppressed by the presence of 5% NH 3. Detailed analysis and characterization of the V 2O 5/AC subjected to the regenerations are presented.

Production of activated carbon from acorns and olive seeds

This study has been designed to produce activated carbon from acorns and olive seeds. The starting materials are low in cost and they are the cause of solid waste pollution problems in Jordan. A chemical procedure is used to produce the required activated carbon. The results indicate that activated carbon produced from acorns compares favorably with that from olive seeds which rank second, along side commercial type activated carbon which comes last with respect to adsorption capacity. However, the optimum activation temperature is 800°C and the optimum regeneration temperature is also 800°C.