Regeneration Reactor Research Articles

Flexible strategies for carbon‐negative syngas and biochar poly‐generation via a novel chemical looping approach

AbstractThis work proposed a pyrolysis chemical looping reforming‐two stage regeneration (PCLR‐TR) process with carbon‐negative syngas and biochar poly‐generation，aimed at overcoming challenges in chemical looping gasification. The process effectively separates pyrolysis and reforming, circumventing slow solid–solid reactions and enabling the flexible adjustment of the H2/CO ratio. The two‐stage regeneration ensures improved synchronization of reaction rates across different reactors. The results indicate that manipulation of process parameters allows for flexible adjustment of the H2/CO ratio in syngas (ranging from 1.02 to 3.83). The introduction of CO2 feed in the first stage regeneration reactor reduces the oxygen carrier exothermic intensity in the second stage regeneration reactor by 58%. Optimization results suggest that the generated syngas is compatible with diverse downstream applications, exhibiting a maximum CO2 negative emission of 1.85 kg/kg syngas. The PCLR‐TR system offers a versatile and environmentally friendly solution for the energy and chemical industries.

Effective direct steam regeneration of bis-iminoguanidine solid sorbent used for carbon dioxide capture

A cost-effective, energy-efficient sorbent regeneration process for phase-changing guanidines used for CO2 capture was developed based on direct-steam stripping. This approach enhances the regeneration rate, simplifies the overall CO2 capture process, and reduces the energy cost compared to conventional conductive thermal regeneration. A direct-steam sorbent regeneration reactor was developed, demonstrating that aqueous bis(iminoguanidines) (BIG) sorbents, e.g., methylglyoxal-bis(iminoguanidine) (MGBIG) and glyoxal-bis(iminoguanidine) (GBIG), could be efficiently regenerated with up to ∼ 99 % CO2 recovery through direct-steam stripping. Using low-temperature steam at 100 °C, a 4.5 times faster regeneration rate for GBIG carbonate sorbent (e.g., 30 min for 10 g) was demonstrated compared to conductive-heating (e.g., 135 min for 10 g) at 130 °C. Additionally, fully regenerated MGBIG converts into an aqueous MGBIG solution when the steam condenses onto the sorbent surface. Condensed steam with the guanidine can be easily recycled as an aqueous solution into the gas–liquid contactor to achieve a continuous-flow CO2-capture process. Molecular dynamics simulation was employed to provide a better understanding of the process. Higher heat transfer rates from steam to guanidine carbonate, compared to air heating, were attributed to the vibration resonance of water molecules within MGBIG with that of vapor molecules and the effective transfer of kinetic energy from vapor to solid. Technoeconomic analysis demonstrated that direct-steam stripping significantly decreases the CO2 capture cost by 50 % compared to traditional conductive heating methods. Enhanced mass transfer facilitated by low-temperature steam and subsequent condensation effectively heats up the H2O-containing BIG-carbonate crystals, facilitating the desorption of CO2 from the solid crystals, thereby leading to fast, effective, and energy-efficient sorbent regeneration.

Modeling and Parameter Tuning for Continuous Catalytic Reforming of Naphtha in an Industrial Reactor System

A two-dimensional mathematical model was developed to simulate naphtha reforming in a series of three industrial continuous catalytic regeneration (CCR) reactors. Discretization of the resulting partial differential equations (PDEs) in the vertical direction and a coordinate transformation in the radial direction were performed to make the model solvable using Aspen Custom Modeler. A sensitivity-based parameter subset selection method was employed to identify the most influential parameters within the model. Tuning of 8 out of 180 parameters was used to ensure that model predictions match experimental data from one steady-state run. The updated parameter values improved the model fit to the data, reducing the weighted least-squares objective function for parameter estimation by 73%. The proposed model was used to predict reactor temperatures, catalyst coke weight fraction at the exit of the third reactor, and benzene flowrate from the outlet of the third reactor. The simulation results demonstrated a good agreement between the simulated values and the industrial measurements. Finally, the reactor model was utilized to explore the effects of changes in inlet temperatures and inlet level of catalyst deactivation, providing valuable insights for identifying desirable operational conditions that will improve the overall efficiency of the CCR process.

Design and study of a novel ammonia‐based CO2 capture process with bipolar membrane electrodialysis

AbstractAqueous ammonia is a promising absorbent in the field of post combustion CO2 capture. However, the high volatilization of NH3 results in a high energy requirement, as well as solid precipitation during the CO2 regeneration process. A novel process was designed to reduce energy consumption and solve the problem. The bipolar membrane electrodialysis (EDBM) unit and CO2 regeneration reactor were taken as the regeneration part. In the novel process, the bubble in the EDBM unit would be eliminated, and the regeneration of CO2 and aqueous ammonia would be operated separately, which significantly reduced energy consumption and avoided the risk of precipitation during regeneration. According to the simulation and calculation results, the CO2 regeneration energy consumption of the novel process using H2SO4 for CO2 regeneration is 39.0% lower than that of the conventional ammonia‐based process, which shows good energy saving potential. Moreover, the novel process will be more competitive as membrane technology develops.

Macroscopic analysis of chemical looping combustion with ilmenite versus conventional oxides as oxygen carriers

AbstractOver 40% of global energy-related CO2emissions are due to the combustion of fossil fuels for electric energy generation. Albeit CO2capture and storage have been identified as promissory actions to mitigate its emissions, the problem separating N2and CO2remains. A very effective solution for the former problem is to obtain the combustion CO2as a pure molecule, which is possible using the Chemical Looping Combustion (CLC) technology, which uses a solid oxygen carrier to transport the oxygen from an oxidating media (regeneration reactor) to a reducing media (combustion reactor). One of the key issues to apply CLC is to find or develop some material, suitable from the kinetic and thermodynamic points of view, for the reduction-oxidation cycles taking place inside combustion and regenerator reactors. The evaluation of “oxygen carrier” candidates for CLC is based on reactivity (rates and conversions), resistance to carbon accumulation, and “regenerability”, which means the ability of the material for cyclic reduction and oxidation. Another challenging issue to use CLC processes is the loss of oxygen carrier; this problem involves the use of supported metals on materials, such as zirconia, Al2O3, etc. Preparation of this kind of supported carriers requires time, money, and equipment. Meanwhile, the natural mineral ore named ilmenite, which consists of a mixture of iron and titanium oxides, and do not need to be supported, has been seen as promising to increase CLC efficiency as oxygen carrier. In this work, the performance of ilmenite is compared with some other oxygen carriers used in CLC.

Extracting high-purity hydrogen via sodium looping-based formic acid dehydrogenation

Formic acid (FA) has been considered as a prospective hydrogen carrier for its potentials to realize hydrogen storage, transportation, and in-situ supply under mild conditions. However, the application of FA dehydrogenation is limited by its unsatisfactory hydrogen concentration and carbon monoxide selectivity. Herein, a sodium looping-based (Na 2 CO 3 ↔NaHCO 3 ) formic acid dehydrogenation (SLFAD) system is proposed for high-purity hydrogen production with ultra-low CO generation via the Na 2 CO 3 ↔NaHCO 3 looping. The SLFAD system consists of three parts, which are FA dehydrogenation reactor (FADR), sorption-enhanced carbon oxide removal reactor (CORR), and sodium-based sorbent regeneration reactor (SSRR). Experimental results proved that no sodium formate and sodium oxalate was formed under NaHCO 3 reduction by H 2 . A comprehensive assessment of the system was carried out to preliminary verify the feasibility and optimize the operation parameters of the SLFAD system. Results indicated that a maximum hydrogen concentration of 97.905 vol%, a minimum CO concentration of 11.97 ppm, and a high hydrogen production rate of 0.99989 kmol H 2 h −1 can be obtained under the conditions of atmospheric pressure, FADR temperature at 80 °C, H 2 O/HCOOH = 1.2, CORR temperature at 80 °C, and Na 2 CO 3 /HCOOH = 1.0. • A sodium looping based formic acid dehydrogenation (SLFAD) concept was proposed. • A high hydrogen concentration of 97.90 vol% can be obtained at low temperatures. • Carbon monoxide concentration can be restricted to be 11.97 ppm via SLFAD process. • Sodium-based absorbent can be regenerated with the achievement of CO 2 capture.

Large-scale applications and challenges of adsorption-based carbon capture technologies

This paper introduces adsorption processes with scaled sizes for post-combustion carbon capture, pre-combustion carbon capture, and direct air capture (DAC). Technical characteristics, separation performances, and operating energy consumptions of adsorption-based pilot plants for carbon capture are analyzed. Opportunities and challenges of adsorption-based carbon capture processes in future development are illustrated. Adsorption-based post-combustion carbon capture is a relatively mature technology, which can be applied to retrofitted power plants. However, in order to commercialize this technology, quantities of research and development resources are still needed. Researches on adsorption-based post-combustion carbon capture should focus on the following three aspects: (1) Low-temperature adsorbents with excellent CO2 working capacities, kinetics, and stabilities, (2) low energy consumption cycles using steam purge, and (3) contactors with low gas-solid mass transfer resistances. The warm gas clean-up technology based on pressure swing adsorption (PSA) is a research hotspot for pre-combustion carbon capture. At present, many warm gas clean-up pilot plants are being built worldwide, and in the meantime, some bottlenecks appear. First, the CO2 working capacities of elevated temperature adsorbents are still lower than those of low temperature adsorbents. The recently reported molten salt-promoted magnesium oxide achieves a very high working capacity through the bulk phase chemical absorption, but a carbon capture prototype needs to be established to verify its cyclic stability. Achieving both high purity and high recovery of warm gas clean-up consumes a large amount of high temperature steam. Although multi-train PSA configuration can reduce the energy consumption, it also increases the operating complexity and equipment investment. In addition to CO2, the removal of other impurities such as H2S, COS, HCl, and heavy metals in syngas/reforming gas should be considered. The sorption enhanced reforming with oxy-fuel regeneration process based on high temperature adsorbents can achieve CO2 enrichment in the regeneration reactor. However, pilot plants for this technology are currently lacking, and so detailed techno-economic analysis is still needed to assess its capture cost. Although DAC is a relatively new concept and is still in the early stage for large-scale commercial application, the synergy between DAC and conventional carbon capture technologies can mitigate climate change effects in the long run. The development of DAC technologies needs to pay special attention to the pressure drop problems. Novel gas-solid contactors using structural adsorbents can effectively reduce the power consumption of the fan. Steam purge under subatomospheric pressures reduces the regeneration temperature of DAC, and thus makes the utilization of renewable energy and industrial waste heat for regeneration becoming possible. When steam purge is used, the cyclic stability of the adsorbents should be concerned. For instance, polyamine impregnated adsorbents are prone to amine leakage in the presence of steam. Therefore, the development of hydrothermally stable DAC adsorbents is significantly important.

Simultaneous magnesia regeneration and sulfur dioxide generation in magnesium-based flue gas desulfurization process

A method was proposed for simultaneously regenerating magnesia from the Mg-based flue gas desulfurization byproducts in the power plant and generating the high concentration of sulfur dioxide. Elemental sulfur particles were evaporated to sulfur vapor and the latter one was used as the reductive agent to regenerate magnesia from the magnesium gypsum. The experiments were carried out in a successive fixed-bed system to study the concentration of sulfur dioxide in the exhaust gas and the activity of the regenerated magnesia under different reaction conditions. Sulfur vapor effectively reduced the magnesia regeneration temperature from above 950 °C to merely 650 °C. The concentration of sulfur dioxide in the exhaust gas could achieve 20% by volume when the sulfur vapor partial pressure was 1674 Pa, the regeneration temperature was 750 °C, the gas hourly space velocity was 1200 h−1 and the loading of the reaction materials in the regeneration reactor was 16 g, respectively. The activity of the regenerated magnesia after the decomposition of the magnesium gypsum at 750 °C was satisfactory. Both the magnesium gypsum and the regenerated magnesia were characterized using X-ray fluorescence spectroscopy, thermogravimetric analyzer, X-ray diffraction spectroscopy, BET surface area analyzer, scanning electron microscopy, high resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The kinetics of the magnesia regeneration from the magnesium gypsum in the presence of the sulfur vapor was analyzed and the nucleation model was determined to be the most appropriate kinetic model. The activation energy and the pre-exponential factor were determined to be 76.51 kJ/mol and 228.66 min−1, respectively. All the results demonstrate that there is considerable potential for the application of this proposed method in flue gas desulfurization process.

Synergistic decarbonization and desulfurization of blast furnace gas via a novel magnesium-molybdenum looping process

In this work, a novel system for synergistic decarbonization and desulfurization of blast furnace gas (BFG) was proposed via a magnesium-molybdenum looping process (MMLP): MgO ↔ MgCO3 and MoO3 ↔ MoS2. The system is comprised of a desulfurization/decarbonization reactor (DDR) and a carbon–sulfur carrier regeneration reactor (CRR). The simulation was conducted for feasibility verification and parameter optimization with applied ASPEN Plus software. Four carbon–sulfur carriers, MgO-MoO3, MgO-Fe2O3, MgO-MnO2, and MgO-SnO2, were preliminary investigated for screening. Results indicate that MgO-MoO3 performs superior capability of synergistic decarbonization and desulfurization. Both water–gas shift and COS/CS2 hydrolysis can be promoted in the presence of MgO via the CO2 absorption and the sorption-enhanced organic sulfur hydrolysis. The effects of MgO/C and 2MoO3/S mole ratios, temperature, pressure, O2 flow rate, and H2O flow rate were intensively discussed. Excessive temperature (>240 °C) in DDR leads to a decrease in carbon removal efficiency. A suitable amount of H2O is beneficial for CO2 capture, organic sulfur hydrolysis, and water gas shift reaction while excessive H2O decreases the organic sulfur hydrolysis efficiency and increases the system energy consumption. Carbon removal efficiency (CRE) of 99.70%, sulfur removal efficiency (SRE) of 100.00%, and H2 yield at 0.276 kmol/h (BFG flow rate = 1 kmol/h) can be obtained under the typical conditions of MgO/C = 2MoO3/S = 1.1, temperature = 240 °C, pressure = 1 atm and H2O/(CO + COS + CS2) = 1.2, providing theoretical guidance for the synergistic removal of sulfides and COx of BFG.

Chemical looping deoxygenated gasification: An implication for efficient biomass utilization with high-quality syngas modulation and CO2 reduction

Chemical looping gasification is a promising technology for biomass utilization. However, the biomass-derived products contain tar and CO2, which seriously affects the syngas quality and hinders its development. A new approach, chemical looping deoxygenated gasification (CLDG), was proposed for high-quality, H2/CO-tunable syngas generation with CO2 utilization via redox looping of CaO + Fe ↔ Ca2Fe2O5. The CLDG process involves a deoxygenation reactor (DR) and a regeneration reactor (RR). Fe0 continuously reduces the oxygen-containing species to drive high-quality syngas production in the DR, and the oxidized oxygen carrier (Fe3+) can be reduced under CO in the RR. A thermodynamic simulation was conducted to verify the feasibility of CLDG using Aspen Plus. The effects of DR and RR temperatures, of the molar ratios of Fe/Obio, CO2/C, H2O/C, and (C + CO)/Fe on the syngas quality, H2/CO molar ratio, and the efficiency of gasification, chemical looping deoxygenation, and CO2 reduction were investigated intensively and optimized to guide the CLDG process. The results indicate that CLDG can significantly improve the quality of syngas with various H2-to-CO syngas modulations and CO2 reduction, obtaining a lower heating value (LHV) of 9.07 MJ/m3, a gasification efficiency of 96.31%, a CO2 reduction efficiency of 44.51%, an H utilization efficiency of 79.52%, and a chemical looping deoxygenation efficiency of 17.55%.

Effect of the Dried and Hydrothermal Sludge Combustion on Calcium Carbonate Decomposition in a Simulated Regeneration Reactor of Calcium Looping

Abstract: The O2/CO2 coal combustion provides enough heat for the decomposition of calcium carbonate in the regenerator reactor of Calcium-looping (Ca-L) process. In this study, the dried sewage sl...

Thermal design of dual circulating fluidized bed reactors for a large-scale CO2 capture system

A dual circulating fluidized bed reactor has been studied for carbon dioxide (CO2) capture. It is important to maintain the reaction temperature of the adsorbent in the carbonation–regeneration cycle. The dual circulating fluidized bed reactor will be used ultimately in the large reactors of industrial-sized power plants to control CO2 emissions. However, to date, studies have considered only small-scale reactor models, due to the limitations associated with two-phase flow dynamics and changes in the heat transfer characteristics with reactor size. In this study, we investigated the thermal design of a feasible pilot-scale reactor through thermal-fluid analysis of the reactor and heat transfer in two-phase flow. Based on our thermal-fluid experimental results for a laboratory-scale dual circulating fluidized bed reactor with an amine-functionalized silica sorbent 0.37EB-PEI, a thermal design process was carried out to increase the reactor scale. In consideration of the heat of reaction and the sensible heat for a continuous process, the increase in total heat duty at the reactor scale has been determined. In the overall heat transfer process of the reactor, consisting of three heat transfer mechanisms, the bed-to-wall heat transfer by gas-solid fluidization was identified as the dominant mechanism. The scale-up of the fluidized bed resulted in a change in gas-solid behaviors and a lower heat transfer coefficient. Ultimately, through the thermal design process, the heat exchange area required for a large-scale carbonation reactor and regeneration reactor were derived; specifically, for the pilot-scale reactor to accommodate > 2000 m3/h flue gas, the required reactor height was estimated to be about two times compared to not taking the scale-up effect into account. We proposed a multi-tube reactor with the high heat transfer coefficient and the large heat transfer area for an efficient large-scale CO2 capture system.

CO2 Sorption Characteristics of Various Sorbents in the Bubbling Fluidized-Bed

This study reports the performance of base-impregnated silica and activated carbons supplied by the University of Nottingham (UNOTT) have been tested in the bubbling fluidized-bed reactor and the two interconnected bubbling fluidized-beds in a continuous system. UNOTT has published several papers with polyethyleneimine (PEI)-silica sorbents using a bubbling fluidized-bed reactor, reporting that the average working capacity was around 8.0wt.% and the regeneration heat was around 3.3 GJ/tCO2 based on the cycle tests. In order to verify the performance of this silica adsorbent and to draw comparison with activated carbons that potentially offer have lower regeneration energies, KIER has carried out cycle experiments using a bubbling fluidized bed reactor and also used a continuous CO2 capture system which consists of a bubbling fluidized-bed-type absorption and regeneration reactors. Further, the sorption characteristics, including equilibrium capacity, kinetics, surface area, pore size distribution, were determined using a volumetric (BET) and a gravimetric (MSB, magnetic suspension balance methods. The sorption mechanism of CO2 on the sorbent surface was investigated by in situ FT-IR. The optical, physical and chemical characteristics were examined by SEM- EDAX, TGA before and after the sorption - desorption cyclic tests. Particle size distribution of the sorbent was also analyzed by laser diffraction particle size analyzer.

Three-dimensional CFD simulation of an MgO-based sorbent regeneration reactor in a carbon capture process

Carbon dioxide is the primary greenhouse gas emitted through human activities; therefore, efficient reduction of CO2 is regarded as one of the key environmental challenges of the current century. Different processes have been introduced in the literature for CO2 capture; among these, solid sorbent processes have shown potential advantages such as easy regeneration and high capacity. In order to achieve steady CO2 capture using solid sorbents, a circulating fluidized bed (CFB) is used that consists mainly of a carbonator reactor (where the CO2 is adsorbed by solid sorbents) and a regenerator (where carbonated sorbents release CO2 and a concentrated CO2-steam mixture is produced). Different solid sorbents have been developed to be utilized in carbon capture units such as MgO-based sorbents and CaO-based sorbents. In this study, an MgO-based solid sorbent was used due to its capability to capture CO2 at high temperature (300–550°C), which is in the vicinity of the operating conditions of advanced power plants (e.g., integrated gasification combined cycles [IGCC]). The use of MgO-based sorbents results in a lower energy penalty in the carbonation/regeneration cycle of MgO-based sorbents. In this study, three-dimensional computational fluid dynamics (CFD) simulations of the regeneration unit of the carbon capture process using MgO-based solid sorbents were investigated and the performance of the fluidized bed regenerator unit (operating at different conditions) was studied.

Intelligent nanospheres with potential-triggered undamaged regeneration ability and superparamagnetism for selective separation of cesium ion

Intelligently magnetic nanospheres with potential-triggered undamaged regeneration ability and superparamagnetism for selective Cs+ separation and recovery are synthesized. Each nanosphere is composed of Prussian blue (PB) with strong Cs+ affinity modified magnetic Fe3O4 (Fe3O4@PB). The magnetic Fe3O4@PB nanospheres show rapid Cesium ion (Cs+) insertion/release kinetics, which is attributed to the good affinity of PB toward Cs+ and the large specific surface area. The Cs+ adsorbed nanospheres can be easily regenerated by simply switching potential of magnetic electrode in an electromagnetic coupling regeneration reactor. Excitingly, the Cs+ adsorption capacity is nearly invariable after 20 adsorption–regeneration cycles and a high regeneration efficiency over 99% is maintained in each cycle. The smart regeneration mechanism is clarified by electrochemical experiment and advanced quantum chemistry calculation. This intelligently magnetic nanospheres with potential-triggered undamaged regeneration ability should be a promising alternative materials for selective separation and recovery of metal ions from wastewater.

Regeneration of activated carbon saturated with chloramphenicol by microwave and ultraviolet irradiation

To reduce the secondary pollution of volatile organic compounds generated from adsorbent regeneration, a regeneration method for granular activated carbon (GAC) saturated with chloramphenicol is studied. The saturated GAC is regenerated by microwave and ultraviolet irradiation which radiated from electrodeless lamps activated by microwave. The existence of ultraviolet rays can affect the degradation of chloramphenicol, and it is analyzed by adsorption capacity recovery percentage, mineralisation percentage and the amount of inorganic chloride. The saturated GAC is regenerated in microwave reactor at 2450MHz for 10min. The mineralisation percentage increases to 37% from 5% when adds the electrodeless lamp into the regeneration reactor. Besides, 83% of the total chloride in chloramphenicol can transform into inorganic chloride. Add ultraviolet radiation in microwave regeneration reactor can enhance the oxidizability of microwave regeneration method. Furthermore, the adsorption ability of GAC can maintain at a high level after five absorption/regeneration cycles. These results show a great potential use of microwave and ultraviolet irradiation to regenerate activated carbon saturated with chlorinated organic compound. This regeneration method can reduce the risk of secondary pollution of chlorinated organic compound during adsorbent regeneration.

High-Performance Chemically Regenerative Redox Fuel Cells Using a NO3- /NO Regeneration Reaction.

In this study, we proposed high-performance chemically regenerative redox fuel cells (CRRFCs) using NO3- /NO with a nitrogen-doped carbon-felt electrode and a chemical regeneration reaction of NO to NO3- via O2 . The electrochemical cell using the nitrate reduction to NO at the cathode on the carbon felt and oxidation of H2 as a fuel at the anode showed a maximal power density of 730 mW cm-2 at 80 °C and twofold higher power density of 512 mW cm-2 at 0.8 V, than the target power density of 250 mW cm-2 at 0.8 V in the H2 /O2 proton exchange membrane fuel cells (PEMFCs). During the operation of the CRRFCs with the chemical regeneration reactor for 30 days, the CRRFCs maintained 60 % of the initial performance with a regeneration efficiency of about 92.9 % and immediately returned to the initial value when supplied with fresh HNO3 .

High‐Performance Chemically Regenerative Redox Fuel Cells Using a NO3−/NO Regeneration Reaction

AbstractIn this study, we proposed high‐performance chemically regenerative redox fuel cells (CRRFCs) using NO3−/NO with a nitrogen‐doped carbon‐felt electrode and a chemical regeneration reaction of NO to NO3− via O2. The electrochemical cell using the nitrate reduction to NO at the cathode on the carbon felt and oxidation of H2 as a fuel at the anode showed a maximal power density of 730 mW cm−2 at 80 °C and twofold higher power density of 512 mW cm−2 at 0.8 V, than the target power density of 250 mW cm−2 at 0.8 V in the H2/O2 proton exchange membrane fuel cells (PEMFCs). During the operation of the CRRFCs with the chemical regeneration reactor for 30 days, the CRRFCs maintained 60 % of the initial performance with a regeneration efficiency of about 92.9 % and immediately returned to the initial value when supplied with fresh HNO3.

CFD simulation of CO2 sorption on K2CO3 solid sorbent in novel high flux circulating-turbulent fluidized bed riser: Parametric statistical experimental design study

In this study a high flux circulating-turbulent fluidized bed (CTFB) riser was confirmed to be advantageous for carbon dioxide (CO2) sorption on a potassium carbonate solid sorbent. The effect of various parameters on the CO2 removal level was evaluated using a statistical experimental design. The most appropriate fluidization regime was found to occur between the turbulent and fast fluidization regimes, which was shown to capture CO2 more efficiently than conventional fluidization regimes. The highest CO2 sorption level was 93.4% under optimized CTFB operating conditions. The important parameters for CO2 capture were the inlet gas velocity and the interactions between the CO2 concentration and the inlet gas velocity and water vapor concentration. The CTFB regime had a high and uniform solid particle distribution in both the axial and radial system directions and could transport the solid sorbent to the regeneration reactor. In addition, the process system continuity had a stronger effect on the CO2 removal level in the system than the process system mixing.

Modeling of a liquid desiccant dehumidification system for close type greenhouse cultivation

Solar energy, heat exchange with the ambient & plants and vapor balance are the key variables for modeling the greenhouse. However, due to solar energy, crops continuously produce water vapors through evapotranspiration, which continuously need to be dehumidified to maintain the relative humidity in the required range. Therefore, modeling and simulation of dehumidification system seems to be indispensable, as it will help to investigate the workability and operating performance of the greenhouse. Hence, this work models and simulates the various components of liquid desiccant based dehumidification system for greenhouse cultivation. Each component of an entire stand-alone dehumidification system, namely reference greenhouse, dehumidification & regeneration reactors and solar collector are thoroughly modeled in MATLAB Simulink environment. The overall system can be effectively utilized to analyze the working performance for greenhouse cultivation. The obtained results indicate that proposed modeling is effective in showing the moisture removal, which crops generate inside the greenhouse. Besides, the developed system is very unique, as most of the previous desiccant system are designed for domestic and commercial buildings. It is envisaged that this work is very useful for the researchers and energy professionals to develop efficient integrated systems for stand-alone buildings.