Post-combustion Gas Research Articles

Characterization of Waste Biomass Fuel Prepared from Coffee and Tea Production: Its Properties, Combustion, and Emissions

In order to reduce global warming, new energy fuels that use waste biomass to replace traditional coal are rapidly developing. The main purpose of this study is to investigate the feasibility behavior of different biomass materials such as spent coffee grounds (SCGs) and spent tea grounds (STGs) as fuel during combustion and their impact on the environment. This study involves using fuel shaping and co-firing methods to increase the fuel calorific value and reduce the emissions of pollutants, such as NOX and SO2, and greenhouse gas CO2. The produced gas content was analyzed using the HORIBA (PG-250) laboratory combustion apparatus. The results indicate that, among the measured formed particles, SCG:STG = 8:2, 6:4, and 4:6 had the lowest post-combustion pollutant gas emissions. Compared to using only waste coffee grounds as fuel, the NOx emissions were reduced from 166 ppm to 102 ppm, the CO emissions were reduced from 22 ppm to 12 ppm, and the CO2 emissions were reduced from 629 ppm to 323 ppm. In addition, the emission of SO2, the main component of acid rain, was reduced by 20 times compared to the combustion of traditional fuels. The SO2 emission of five different proportions of biomass fuels was 5 ppm, which is much lower than that of traditional coal fuels. Therefore, SCG and STG mixed fuels can replace coal as fuel while reducing harmful gasses.

Polymer-modified nanofillers for enhancing CO2 separation performance of MMMs: A comparative study on the role of bridging ligands

Advanced CO2 separation technology is one of the key technologies for reducing carbon emissions and can make significant contributions to reducing the negative impact of the greenhouse effect on human survival. Membrane separation technology is regarded as a new generation of carbon capture technology because of its great potential to reduce carbon capture energy consumption and improve net carbon capture efficiency. Mixed matrix membranes (MMMs) can break through the performance limit of traditional polymer membranes, but the influence of bridging agents for post-modifying nanofillers on membrane structure and properties needs further systematic investigation. In this work, four types of ligands were selected for synthesizing polymer-modified nanofillers and then incorporated into poly (vinylamine) (PVAm) to prepare MMMs. The comparative analysis results indicate that bridging ligands with superior flexibility are conducive to enhancing the gas permeability within the pores by diminishing the compactness of the polymer shell. The constructed phase interface transition area with uniformly enhanced mechanical strength demonstrates the improved interface compatibility between the matrix and nanofillers bridged via the flexible ligand. Techno-economic evaluation verifies the industrial application potential of the optimal MMMs targeting CO2 capture from post-combustion gas.

Hierarchically porous carbon foams coated with carbon nitride: Insights into adsorbents for pre-combustion and post-combustion CO2 separation

Adsorption is fundamental to many industrial processes, including separation of carbon dioxide from other gases in pre- or post-combustion gas mixtures. Adsorbents should have high capacity and selectivity, which are both intimately linked with surface area, pore size distribution, and surface energy. Porous carbons are cheap and scalable adsorbents, but greater understanding of how their textural properties and surface chemistry affects their performance is needed. Here, we investigate the effect of nitrogen doping on CO2 adsorption. Microporous carbon foams with large surface area (>2500 m2 g−1) and pore volume (1.6 cm3 g−1) are synthesized, then coated with varying amounts of carbon nitride (up to 17 at% nitrogen) to achieve high CO2 uptake (25.5 mmol g−1) and selectivity (CO2:N2 = 21), whilst also giving insights into the relationship between structure and function. At low pressure (relevant to post-combustion capture), moderate carbon nitride loading leads to enhanced uptake and selectivity by combining large ultramicropore volume with the introduction of Lewis base sites, leading to high isosteric heat of adsorption. Higher carbon nitride loading further increases selectivity but lowers uptake by blocking micropores. Conversely, at high pressure (relevant to pre-combustion capture) the uncoated carbon foam displays superior uptake, because mesoporosity is the dominant factor in this regime, rather than the presence of ultramicropores. Finally, the samples displayed excellent regeneration under repeated adsorption–desorption cycles, and breakthrough curves were measured. These results underscore the delicate balance required for optimal material design when applying porous carbon adsorbents to CO2 separation processes. Moving forward, improved adsorbents will contribute to the proliferation of carbon capture and storage (CCS) and carbon capture and utilisation (CCU) technologies, ultimately contributing reduced anthropogenic CO2 emissions.

Large-scale preparation of composite membranes for CO2 separation via interfacial polymerization: Monomer selection and processing parameter optimization

The increasingly serious situation of CO2 emissions compels researchers to pay extensive attention to industrial processes for carbon capture. Membrane-based separation technology is widely regarded as a promising reserve method for carbon capture, featuring a wide adjustment range, flexible operation and modular design. In this work, a large-scale interfacial polymerization membrane production process for carbon capture was developed together with the construction of novel interfacial polymerization equipment with an adjustable organic phase bath and surface cross-linking unit. A monomer suitable for efficiently preparing high-performance CO2 separation membranes was selected through a combination of experiments and simulations. The effect of production conditions on the structure and performance of large-scale membranes was investigated. The performance resilience at high pressure and short-term stability in the presence of impurities of the optimized membranes were examined. Techno-economic evaluation targeting carbon capture from post-combustion gas verifies the significant industrial application potential of the membranes.

Binary carbon dioxide and nitrogen adsorption on pomelo peel-derived porous sorbent

The rising concern regarding CO2 emission from fossil fueled-power plants, along with the heightened interest in repurposing biowaste has necessitated the utilization of biowaste as an adsorbent for CO2 capture. In this study, the pomelo peel-derived activated carbon (POM-AC) was investigated as a potential adsorbent for post-combustion CO2 capture application, which involves capturing CO2 from the CO2 and N2 gas mixture. The POM-AC was characterized, revealing a microporous-mesoporous structure that contains various surface functional groups including hydroxyl, carbonyl, carboxyl, and alkene groups. The strong affinity of POM-AC towards CO2 over N2 was demonstrated from the increment in the CO2 and N2 gas mixture uptake with the increase in CO2 gas compositions. The total adsorption capacity of POM-AC at ambient conditions for 100% CO2, 15% CO2, 10% CO2, and 5% CO2 is 127.8 mg/g, 55.7 mg/g, 49.1 mg/g, and 38.3 mg/g, respectively. Notably, POM-AC outperformed the commercial activated carbon (Chemiz-AC) at simulated post-combustion conditions due to POM-AC having smaller pores than Chemiz-AC. The Ideal Adsorbed Solution Theory (IAST) prediction of binary CO2 and N2 adsorption equilibria showed higher CO2 adsorption capacity than N2 at post-combustion gas compositions (5–15% CO2), which further suggests its stronger preferential of CO2 over N2. Furthermore, a relatively high CO2/N2 selectivity of 23.9 was predicted for 15% CO2 gas composition. The adsorption isotherm and kinetic analysis revealed that the surface of POM-AC is heterogenous, and the rate-controlling step of CO2 and N2 adsorption is physisorption. Coupled with the utilization of a zero-cost biowaste as an activated carbon precursor, these findings showed that POM-AC could be a promising adsorbent for post-combustion CO2 capture application.

Synthesis and optimization of high-performance amine-based polymer for CO2 separation

• Optimal conditions were ascertained to obtain PVAm with high molecular weight and low crystallinity. • The effect of molecular weight and crystallinity on CO 2 separation performance of PVAm was systematically discussed. • The pilot scale synthesis of PVAm was successfully attempted for continuous preparation of composite membranes with high CO 2 separation performance. Membrane technology features inspiring excellence from numerous separation technologies for CO 2 capture from post-combustion gas. Polyvinylamine (PVAm)-based facilitated transport membranes show significantly high separation performance, which has been proven promising for industrial scale-up. However, commercialized PVAm with low molecular weight and excessive crystallinity is not available to prepare high-performance membranes. Herein, the synthesis process of PVAm was optimized by regulating polymerization and acidic hydrolytic conditions. The membranes based on PVAm with a molecular weight of 154 kDa and crystallinity of 11.37% display high CO 2 permeance of 726 GPU and CO 2 /N 2 selectivity of 55 at a feed gas pressure of 0.50 MPa. Furthermore, we established a PVAm synthesis reactor with an annual PVAm solution (1%(mass)) capacity of over 7000 kg and realized the scaled-up manufacture of both PVAm and composite membranes.

Effect of Steam Injection during Carbonation on the Multicyclic Performance of Limestone (CaCO3) under Different Calcium Looping Conditions: A Comparative Study

This study explores the effect of steam addition during carbonation on the multicyclic performance of limestone under calcium looping conditions compatible with (i) CO2 capture from postcombustion gases (CCS) and with (ii) thermochemical energy storage (TCES). Steam injection has been proposed to improve the CO2 uptake capacity of CaO-based sorbents when the calcination and carbonation loops are carried out in CCS conditions: at moderate carbonation temperatures (∼650 °C) under low CO2 concentration (typically ∼15% at atmospheric pressure). However, the recent proposal of calcium-looping as a TCES system for integration into concentrated solar power (CSP) plants has aroused interest in higher carbonation temperatures (∼800–850 °C) in pure CO2. Here, we show that steam benefits the multicyclic behavior in the milder conditions required for CCS. However, at the more aggressive conditions required in TCES, steam essentially has a neutral net effect as the CO2 uptake promoted by the reduced CO2 partial pressure but also is offset by the substantial steam-promoted mineralization in the high temperature range. Finally, we also demonstrate that the carbonation rate depends exclusively on the partial pressure of CO2, regardless of the diluting gas employed.

Synergistic and competitive effect of H2O on CO2 adsorption capture: Mechanism explanations based on molecular dynamic simulation

The presence of water vapor in post-combustion gas streams is a challenging technical issue that limits the utilization of CO2 adsorbents. Understanding the physical and chemical interaction mechanisms between adsorbents and adsorbates is the key to effectively deal with the competitive adsorption of CO2 and H2O. In this paper, a thermodynamic molecular pump (TMP) is proposed to resolve the contradictions between the promotion and impedance of CO2 adsorption by H2O. Specifically, the TMP model was proposed for quantitative analyses on a molecular scale for the first time. The equilibrium adsorption isotherms and adsorption enthalpies for CO2 and H2O at 298–388 K were obtained by grand canonical Monte Carlo (GCMC) simulations, while the adsorption entropies were obtained by density functional theory (DFT). Furthermore, the Gibbs free adsorption energy was then obtained by considering the effects of temperature and adsorption sites. The TMP-based analysis showed that the Gibbs free adsorption energy of H2O was a significant factor that influenced the CO2 adsorption result due to its contribution to the total driving energy. For CuBTC (BTC: benzene-1,3,5-tricarboxylate), the CO2 adsorption entropy provided a greater driving force to adsorb CO2 preferentially at 348–388 K. For zeolite AFI, the adsorption enthalpy was always the largest driving force. The results show that the adsorption temperature had a strong influence on zeolites. At 320–360 K, the zeolites showed better CO2/H2O adsorption selectivity than metal–organic frameworks (MOFs) due to their sensitivity to the thermal driving forces, as predicted by the TMP model. This is especially significant for the potential application of zeolites in temperature swing cycles driven by low- and medium-grade energy. The TMP model can provide guidance for screening CO2 adsorbents in the presence of H2O.

Assembly of Defect-Free Microgel Nanomembranes for CO2 Separation.

The development of robust and thin CO2 separation membranes that allow fast and selective permeation of CO2 will be crucial for rebalancing the global carbon cycle. Hydrogels are attractive membrane materials because of their tunable chemical properties and exceptionally high diffusion coefficients for solutes. However, their fragility prevents the fabrication of thin defect-free membranes suitable for gas separation. Here, we report the assembly of defect-free hydrogel nanomembranes for CO2 separation. Such membranes can be prepared by coating an aqueous suspension of colloidal hydrogel microparticles (microgels) onto a flat, rough, or micropatterned porous support as long as the pores are hydrophilic and the pore size is smaller than the diameter of the microgels. The deformability of the microgel particles enables the autonomous assembly of defect-free 30-50 nm-thick membrane layers from deformed ∼15 nm-thick discoidal particles. Microscopic analysis established that the penetration of water into the pores driven by capillary force assists the assembly of a defect-free dense hydrogel layer on the pores. Although the dried films did not show significant CO2 permeance even in the presence of amine groups, the permeance dramatically increased when the membranes are adequately hydrated to form a hydrogel. This result indicated the importance of free water in the membranes to achieve fast diffusion of bicarbonate ions. The hydrogel nanomembranes consisting of amine-containing microgel particles show selective CO2 permeation (850 GPU, αCO2/N2 = 25) against post-combustion gases. Acid-containing microgel membranes doped with amines show highly selective CO2 permeation against post-combustion gases (1010 GPU, αCO2/N2 = 216) and direct air capture (1270 GPU, αCO2/N2 = 2380). The membrane formation mechanism reported in this paper will provide insights into the self-assembly of soft matters. Furthermore, the versatile strategy of fabricating hydrogel nanomembranes by the autonomous assembly of deformable microgels will enable the large-scale manufacturing of high-performance separation membranes, allowing low-cost carbon capture from post-combustion gases and atmospheric air.

Enhancement of CO2 capture through hydrate formation: the effect of tetrahydrofuran (THF) and tertiary amine solutions

Global climate change and global warming due to elevated CO2 atmospheric concentrations have become a major global concern. For this reason, the separation and capture of CO2 from industrial effluence is an important research focus. The CO2-based hydrate formation process has received close attention in the field of carbon capture due to its efficiency in selectively separating CO2 from pre- and post-combustion gas mixtures. In this work, a set of experiments was conducted in the presence of the two tertiary amines, triisopropanolamine (TIPA) or triethanolamine (TEA) combined with THF to evaluate their effectiveness in CO2 selectivity during hydrate formation and in decreasing the operational pressure required for the process. These experiments were aimed at observing whether the presence of amines supports/depresses the hydrate formation. In addition, they were also aimed at comparing the carbon-selective separation efficiency of the systems with and without amines through hydrate formation. It was observed that TEA discouraged hydrate formation. However, the addition of TIPA in the presence of THF at an operational pressure of 3.5 MPa improved initial gas loading as well as CO2 selective separation from the gas mixture. This contributed to an increase of 65% in the capture of CO2 from the gas mixture. When the same experiment was carried out at a lower pressure of 1.5 MPa, CO2 selectivity was also observed to have increased. However, the induction time was observed to be considerably longer compared to the previous case.

Electric Field Controlled Separation and Capture of CO2 over S-Doped Graphene: A First-Principles Calculation

The selective adsorption and capture of CO2 from post-combustion gases carries huge significance for the reduction of greenhouse effect. In this research, the computations of density functional are performed to investigate the CO2 selective adsorption of S-doped graphene in thrall to applied electric field (E-F). Introducing the applied E-F, the adsorption between S-doped graphene and CO2 is strong chemisorption, and CO2 can be effectively captured. Removing the applied E-F, the adsorption restores to physisorption and CO2 is easily desorbed. Therefore, the CO2 seize and clearing can be realized merely by controlling the E-F. Besides, the adsorption energy of N2 (H2O) on S-decorated graphene is positive when introduce the applied E-F. The results demonstrated that S-doped graphene can selectively adsorb CO2 from the post-combustion gases by controlling the E-F.

Experimental investigation of improved graphene oxide as an efficient catalyst for the sustainable chemical fixation of CO2 with epoxides

Herein, we improved the synthesis procedure of graphene oxide with the optimized catalytic properties as a promising catalyst for the cycloaddition of CO2 to epoxides at mild conditions. Different operating conditions such as reaction temperature, pressure, TBAB/epoxy molar ratio, various nucleophiles (co-catalyst), reaction time and catalyst weight percentage were studied in this reaction. In addition, different epoxides were converted at 80 °C, under optimized conditions including a catalyst loading of 3.2 wt.%, reaction pressure of 1 bar, TBAB/epoxy molar ratio of 1/40 for 12 h with isolated yields of carbonate up to 98 %. In addition, the kinetic of the reaction was investigated at different reaction temperatures by calculating the reaction rate constant and activation energy (based on Arrhenius equation). Furthermore, the best catalyst is investigated at atmospheric bubbling conditions and model gas of post-combustion gas stream at 80 °C. The obtained results revealed that, the proposed graphene oxide has a high tendency for the conversion of carbon dioxide without post-processing of CO2 containing effluent gas streams.

Thermoresponsive CO2 absorbent for various CO2 concentrations: tuning the pKa of ammonium ions for effective carbon capture

Amine absorbents that efficiently absorb and desorb CO2 in response to small temperature changes are desired for CO2 separation from concentrated and dilute gases. Thermoresponsive hydrogel films consisting of amine-containing microgel particles (GPs), which capture CO2 at a low temperature (30 °C) and desorb it upon mild heating (75 °C), are attractive for capturing CO2 from postcombustion gases containing 10% CO2 (10 kPa). However, little information has been reported about thermoresponsive GPs for CO2 separation from gas mixtures with low concentrations of CO2. Herein, we describe the effect of the pKa of ammonium ions in GPs on the amount of CO2 desorption upon heating at 75 °C, which was investigated at various CO2 concentrations. The efficiency of CO2 desorption (mol-desorbed CO2/mol-amine) depends on the pKa and pKa shift (ΔpKa) of the ammonium ions in the range of 30‒75 °C. Computational predictions also indicated that the pKa values and ΔpKa are both important for reversible CO2 absorption. A guideline for designing thermoresponsive amine absorbents for various applications including direct air capture and carbon recycling in closed spaces, such as space stations and submarines, is provided. Amine-containing microgel particles (GPs), which capture CO2 at a low temperature and desorb it upon a mild heating, are attractive materials for capturing CO2. In this paper, the effect of pKa of ammonium ions in the GPs on the amount of CO2 desorption upon heating was investigated at various CO2 concentrations by experiments and thermodynamic predictions. A guideline for designing thermoresponsive amine absorbents for various applications including direct air capture and carbon recycling in closed spaces, such as space stations and submarines, is provided.

Molecular-Level Overhaul of γ-Aminopropyl Aminosilicone/Triethylene Glycol Post-Combustion CO2 -Capture Solvents.

Capturing carbon dioxide from post-combustion gas streams is an energy-intensive process that is required prior to either converting or sequestering CO2 . Although a few commercial 1st and 2nd generation aqueous amine technologies have been proposed, the cost of capturing CO2 with these technologies remains high. One approach to decrease costs of capture has been the development of water-lean solvents that aim to increase efficiency by reducing the water content in solution. Water-lean solvents, such as γ-aminopropyl aminosilicone/triethylene glycol (GAP/TEG), are promising technologies, with the potential to halve the parasitic load to a coal-fired power plant, albeit only if high solution viscosities and hydrolysis of the siloxane moieties can be mitigated. This study concerns an integrated multidisciplinary approach to overhaul the GAP/TEG solvent system at the molecular level to mitigate hydrolysis while also reducing viscosity. Cosolvents and diluents are found to have negligible effects on viscosity and are not needed. This finding allows for the design of single-component siloxane-free diamine derivatives with site-specific incorporation of selective chemical moieties for direct placement and orientation of hydrogen bonding to reduce viscosity. Ultimately, these new formulations are less susceptible to hydrolysis and exhibit up to a 98 % reduction in viscosity compared to the initial GAP/TEG formulation.

Ionic liquid containing amine-based silica aerogels for CO2 capture by fixed bed adsorption

The main goal of this study is to develop an adsorption based process using amine-based silica aerogels to capture CO2 from post-combustion gases. For this purpose, silica based aerogels were synthesized by following single-step sol-gel method using tetraethyl orthosilicate (TEOS) as silica precursor and (3-Aminopropyl)triethoxysilane (APTES) as amine source in different compositions. To enhance CO2 capture performances of the prepared aerogels, amine-containing ionic liquid (1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) was also used as sol agent due to high CO2 selectivity and lower viscosity. Chemical structural properties, thermal behaviors, surface area and morphologies of prepared aerogels were analyzed. CO2 capture performances of prepared aerogels were investigated in a fixed bed column of CO2 capture experimental set-up for adsorption. Results have shown that CO2 adsorption capacities of ionic liquid containing amine-based aerogels increased with the addition of amine source and ionic liquid. Among the prepared aerogels, the sample of TA0.24IL0.28 exhibited superior adsorption behavior with the maximum capacity of 243.32 mg CO2/g (5.53 mmol/g).

Эффективность сжигания древесного топлива в водогрейных котлах КВУ-2000

Renewable energy use is one of priority areas of power production development. One of the sources is wood biomass. Utilization of wood biomass in the regions with developed timber industry is a prospective decision in ensuring power independence. Wood biomass usage allows to recover by-products of logging and woodworking industries, generate cheaper electric power and reduce an impact on the environment. The North-West of Russia has huge wood reserves. As a result, the issues of efficient utilization of wood biomass are relevant for the region. An effective way of the complex solution of energetical and ecological problems with provision of heating loads is application of modern devices operating on wood fuel such as modern water boilers. This study aims to analyze heat engineering and environmental performance of the boiler KVU-2000 during the combustion of by-products of timber industry. The components of the boiler’s heat balance and gaseous effluents have been determined. Emissions of particulate matter and the content of soot particles have been studied. The study results have shown that the boiler KVU-2000 provides high economic and environmental performance when operating on polydisperse wood fuel. However, a manual regulation of secondary air flow and absence of the flue gas oxygen control systems do not allow to keep optimum combustion air-blown mode. Absence of resistance control devices for ash collectors and thermal insulation of elements in post-combustion gas path lead to irrational heat losses, which conflicts with normative regulations. A limited operational period between cleaning of heating surfaces of a fire-tube boiler demands strict requirements to capacity redundancy. Elimination of identified flaws will ensure substantial increase of energetic and economic performance of the boilers; allow to minimize the emissions of harmful substances of biofuel burning, and recommend these boilers for application in heat supply systems in the Arctic region. For citation: Lyubov V.K., Popov A.N. Combustion Efficiency of Wood Fuel in the Water Boilers KVU-2000. Lesnoy Zhurnal [Russian Forestry Journal], 2020, no. 1, pp. 167–179.DOI: 10.37482/0536-1036-2020-1-167-179 Acknowledgments: The authors are grateful to D.G. Chukhchin for carrying out the research using the scanning electron microscopy method.

Evaluation of the thermal regeneration of an amine-grafted mesoporous silica used for CO2/N2 separation

In view of the promising applicability of adsorption to the capture of CO2 from post-combustion gases, the use of mesoporous silica functionalized with 3-aminopropyltriethoxysilane (APTES) was studied as adsorbent in a fixed bed for CO2–N2 separation under thermal swings. Characterization of the adsorbent performed before and after functionalization indicated that amine grafting was successful. Additionally, CO2 adsorption on a magnetic suspension balance showed a significant increase in uptake of the APTES-functionalized sample over the support, mainly at low relative pressures. Relatively high values of adsorption enthalpy suggest the occurrence of chemical adsorption attributed to CO2 bonding with the amines. Breakthrough curves were measured for pure CO2, N2 and the CO2/N2 (15/75% v/v) mixture, which showed good agreement with respect to the uptake of the individual gases, as determined from gravimetric tests. Full CO2 desorption from the bed required a temperature rise, which suggests that these materials may be suitable for TSA cyclic processes. A temperature of 90 °C was enough for a complete regeneration of the adsorbent during the desorption phase under dynamic conditions. The material showed very stable behavior after 20 successive cycles.

Analysis of makeup air in a natural smoke vent system in a tall space using numerical simulation and Schlieren technique

Purpose The purpose of this paper is to analyze the phenomenon of makeup effect using numerical simulation and model experiments on seven different natural smoke extraction patterns of tall space. Airflow distribution and heat accumulation phenomenon in different cases are compared. The natural smoke exhaust system for tall spaces has many advantages, including low cost, no power and low maintenance cost. It is more advantageous than the mechanical type of exhaust. However, the internal air distribution is complicated since the large span spatial character. Effective and correct verification method is very important for the analysis of flow fields in tall spaces. Design/methodology/approach This study used fire dynamics simulator (FDS) software to simulate the fire scene. The model experiments are conducted to determine if the numerical simulation results are reasonable. A single-mirror Schlieren system, including an 838 (H) × 736 mm (W) square concave mirror, as well as the focal length of 3,100 mm was adopted to record the dynamic flow of hot gas. Six smokeless candles were burned in a 1/12.5 model in experiments to record the distribution of inflow, accumulation and outflow of airflow in the space. In addition, the thermocouple lines were mounted in the model for temperature measurement. Findings The results of numerical simulation and model experiments have proved that makeup air has a significant effect on the effectiveness of a natural smoke vent system. Larger areas of smoke vents will produce more heat accumulation phenomenon. In this study, the air inlet and vent installed on the same side have a better heat removal effect. Moreover, Schlieren photography technique is proved to be an accurate measurement method to record the dynamic flow of hot air immediately, directly and accurately. The dynamic flow behavior of hot gas in the model has been visualized in this paper. Originality/value At present, there is no examination method other than checking the smoke vent area to validate the effectiveness of a natural smoke vent system in Taiwan, as well as no requirements regarding the makeup inlet. The effect of makeup air in generating the effective push-pull phenomenon of airflow has been analyzed. In addition, the post-combustion hot gas distributions were visualized by using Schlieren photography technology in the model space, compared with the FDS simulation result and thermocouple recorded temperature. A verification method in the model experiments is established to determine if the numerical simulation results are reasonable.

Investigation on kinetics of carbon dioxide absorption in aqueous solutions of monoethanolamine + 1, 3-diaminopropane

ABSTRACTEnvironmental concerns from global warming and climate change demand carbon dioxide separation from post-combustion gases. Important parameters are involved in choosing the suitable solvent for carbon dioxide separation, including the reaction rate of carbon dioxide and the solvent. In this paper, the kinetics of carbon dioxide (CO2) absorption in aqueous solutions of Monoethanolamine (MEA) + 1,3-Diaminopropane (DAP), a diamine containing two primary amino group, was developed. The measurements were performed in a stirred cell with a horizontal gas-liquid interface in the temperature range of 313.15–333.15 K and aqueous solutions of 10 wt% MEA + 5 wt% DAP and 12.5 wt% MEA + 2.5 wt% DAP. Experiments were conducted in an isothermal batch reactor with a horizontal gas-liquid interface under pseudo-first-order conditions, enabling the determination of the overall kinetic rate constant from the pressure drop method. Second-order reaction rate constants of CO2 absorption in amine solutions were estimated using the calculated initial absorption rate. It was found that the rate constants in MEA+ DAP solutions were greater than in MEA solutions which means that DAP increases the reaction rate.

Phosphorus Dendrimer Derived Solid Sorbents for CO2 Capture from Post-Combustion Gas Streams

Solid amine sorbents were prepared via cross-linking of polyamine compounds and polyaldehyde phosphorus dendrimers through a reductive amination approach. The CO2 adsorption capacities from inert gas streams and simulated flue gas were determined using a thermogravimetric analyzer (TGA) and a packed-bed reactor, (PBR) respectively. The sorbents adsorbed CO2 from inert CO2 gas streams up to 7.3 wt % at 65 °C and 10.7 wt % at 25 °C, while adsorbing CO2 from simulated flue gas up to 7.4 wt % at 65 °C. The amines are covalently bound in the sorbent, providing a robust material that is stable at elevated temperatures and does not leach upon exposure to moisture. The sorbents underwent extensive cycle testing, with no degradation observed up to 45 cycles on the TGA and up to 25 cycles on the PBR, while displaying rapid kinetics for both adsorption and desorption of CO2.