Kinetic enhancement of adsorbent for CO2 capture from atmosphere by porous material

Strategies for stabilizing atmospheric greenhouse gas concentrations will need to consider future CO2 emissions from an enormous resource of worldwide fossil fuel supplies and a diverse range of mitigation technologies. In 2013, global CO2 emissions due to fossil fuel use (and cement production) were 36 gigatonnes (Gt CO2), and are projected to increase by an additional 2.5% in 2014. Even if all emissions from large fixed sources could be captured, the roughly 30-50% of global emissions due to transportation and mobile sources would still be released into the atmosphere. To ensure the concentration of atmospheric CO2 in the scope of security, CO2 air capture, which offers the potential to be a truly carbon negative technology, is urgent. The design and preparation of porous materials with controlled structures and functionalities is crucial to low concentration CO2 capture. In this work, two preparation approaches of CO2 adsorbents are explored. One is heterogeneous membrane preparation using porous supporting materials through phase inversion method, which is relatively simple, rapid, and inexpensive, and the other is to directly prepare the porous adsorbents through grafting method using a novel material—cellulose. For phase inversion method, anion exchange resin, which can absorb low concentration CO2 after ion exchange treatment, is mixed with Polyethersulfone (PES), N-Methyl pyrrolidone (NMP) and Macrogol 400(PEG-400) to form casting solution, and finally, the heterogeneous membrane is prepared for CO2 adsorption. For grafting method, the cellulos anion exchange fiber used for CO2 adsorption, is prepared by alkali pretreatment of sodium hydroxide and the grafting of epichlorohydrin and ethylenediamine onto fiber, and finally ion exchange treatment is made to introduce basic groups, such as carbonate ions and hydroxide ion. The surface properties of the prepared adsorption materials are characterized by SEM and BET, as can be seen in Figure 1, and the results reveal that the materials are porous and have large specific surface area, which is beneficial to the kinetics of CO2 adsorption. The absorption performances of the two kinds of adsorbents are tested on a self-made rotating bed reactor, and the absorption capacity and kinetics are compared. To optimize the kinetics performance of CO2 adsorption, the modified shrinking core model (SCM) is used to analyze the resistance during the reaction process according to the test results. The resistance during the mass transfer process includes physical diffusion resistance and chemical reaction resistance. For the heterogeneous membrane, the results reveal that the resistance of physical diffusion and chemical reaction is comparable when the saturation of CO2 adsorption is low (less than 0.3), and the physical diffusion resistance increases greatly and controls the kinetics performance when the saturation of CO2 is high, as can be seen in Figure 2. The influence of temperature and humidity on CO2 adsorption kinetics is also studied and the diffusion coefficient and reaction rate constant are obtained, and the activation energy of reaction can be determined

Sustainable Food and Fuel on Yongxing Island by Conversing the Carbon Captured from Ambient Air

AbstractSynthetic hydrocarbon fuel, derived from renewable energy and captured carbon dioxide from ambient air, can thoroughly close its carbon cycle and is a promising option for CCU and an important approach to sustainable energy. We investigate the Yongxing island in south China sea, which offers steady wind resources to provide continuous energy supply for plant factory and fuel synthesis. The energy consumption of MSAC and TSAC is compared and conversion of the captured CO2 to food and fuel are calculated. Powered by wind energy, 200 ton vegetables and 5.2*103 ton diesel will be produced per year, so self-sufficiency of vegetable and fuel demand can be achieved on Yongxing island. Our methodology could provide a new utilization mode for islands like Yongxing island

Time-Free Solution to SAT Problem by Tissue P Systems

Tissue P systems are a class of computing models inspired by intercellular communication, where the rules are used in the nondeterministic maximally parallel manner. As we know, the execution time of each rule is the same in the system. However, the execution time of biochemical reactions is hard to control from a biochemical point of view. In this work, we construct a uniform and efficient solution to the SAT problem with tissue P systems in a time-free way for the first time. With the P systems constructed from the sizes of instances, the execution time of the rules has no influence on the computation results. As a result, we prove that such system is shown to be highly effective for NP-complete problem even in a time-free manner with communication rules of length at most 3

Numerical Study of the Movement of Fine Particle in Sound Wave Field

AbstractInhalable particulate matter, especially PM2.5 is one of the main pollutants in China and it's harmful to both human health and atmosphere. Since the removal efficiency of traditional dust removal devices such as ESP for PM2.5 is very low, pretreatment becomes necessary before the dust gets into the dust remover. Acoustic agglomeration is one of the pretreatment technologies which uses sound wave with high intensity to make fine particles get agglomerate and grow up, and improves the efficiency of traditional dust removal devices for PM2.5. In sound wave field, fine particles are carried by the medium which in this paper is air, and vibrate with different amplitude because of different particle sizes, thus relative movement appears and then particles have more chances to collide and get agglomerate. In this paper, the movement of particles with different sizes in travelling wave sound field and standing wave sound field were calculated, including the velocity, displacement, amplitude and so on. The situation that Re<1 was considered and Viscous force in Stokes region was chose as the main forces here. Studying the movement of fine particle in sound field with different conditions has great meaning in learning the mechanisms of acoustic agglomeration

Hydrodynamics and heat transfer of suspended surface in a supercritical cfb furnace

With the scaling-up of CFB boilers, more heating surfaces like suspended surfaces and/or mid-partition walls, are arranged in the furnace to ensure adequate heat absorption. The length of suspended surface reaches almost half height of the furnace in the Baima 600MW supercritical CFB boiler. Since the gas-solids hydrodynamics and heat transfer on those surfaces are different from that on waterwall, further researches are needed to investigate the characteristics of hydrodynamics and heat transfer on the suspended surfaces. Beside the experimental measurements on the suspended surfaces in a scale down test rig, the hydrodynamic characteristics on the suspended surfaces were computed by a CFD simulation combined with EMMS model in a supercritical CFB of annular furnace. The results present an uneven axial solid concentration profile on the suspended surface, and descending particles are found on some locations especially where those surfaces far away from the furnace exits. Based on the gas-solids hydrodynamic results, the modified cluster renewal model was applied in the heat transfer coefficient calculation of the suspended surfaces. The result shows the heat transfer coefficient varies with the height and it has difference between two sides of a surface. In addition, the average heat transfer coefficients of suspended surface at different locations are compared. References Basu P, Nag P K. Heat transfer to walls of a circulating fluidized-bed furnace[J]. Chemical Engineering Science, 1996, 51(1): 1-26. Cen K F, Ni M J, Luo Z Y, et al. Theoretical design and operation of circulating fluidized bed boiler[J]. China Electric Power Press, Beijing, 1998: 647-663. Cheng L M, Wang Q H, Shi Z L, et al. Heat transfer in a large circulating fluidized bed boiler[J]. Journal of Power Engineering, 2006, 26(3): 305-310. Huang C, Cheng L M, Zhou X L, et al. Suspended surface heat transfer in a large circulating fluidized bed boiler furnace[J]. Journal of Zhejiang University. Engineering Science, 2012, 46(11): 2128-2132. Sundaresan R, Kolar A K. Axial heat transfer correlations in a circulating fluidized bed riser[J]. Applied Thermal Engineering, 2012. * “Strategic Priority Research Program” of the Chinese Academy of Sciences, Grant No. XDA0703010

Gas-Solids Hydrodynamics in a CFB with 6 Cyclones and a Pang Leg

Solids volume fraction and particle velocity profiles were measured with a fiber optical probe in a cold circulating fluidized bed test rig with 6 parallel cyclones and a pant leg. Results in the pant leg zone, main bed zone and exit zone of the furnace are reported. The work also includes the influences of superficial gas velocity, secondary air rate and static bed height on the gas-solids hydrodynamics