New hyper‐cross‐linked porous organic polymers (POPs) with a high content of pyridine segments (7.86 mmol pyridine g−1), and a micro/mesoporous texture are reported. The networks are achieved by the chain‐growth homopolymerization of 2,6‐ and 3,5‐diethynylpyridines. The pyridine segments form links interconnecting the polyacetylene main chains in these networks. The content of pyridine segments in the networks can be tuned by copolymerizing diethynylpyridines with 1,3‐diethynylbenzene. The pyridine rings in the networks serve as base and hydrophilic centers for the sorption of CO2 and water. The homopolymer pyridine networks are highly efficient in the low‐pressure adsorption/desorption of CO2. This sorption mode is promising for the postcombustion removal of CO2 from the fuel gas. The poly(3,5‐diethynylpyridine) network exhibits high efficiency in capturing and releasing water vapor (determined capacity 376 mg g−1 at 298 K and relative humidity (RH) = 90% is one of the highest values reported for POPs) and is a promising material for the cyclic water harvesting from air. The reported networks are characterized by 13C cross‐polarization magic angle spinning NMR, thermogravimetric analysis, and N2 adsorption/desorption and their efficiency in CO2 and H2O capturing is discussed in relation to the content and type of incorporated pyridine segments.
Abstract. SiO 2 deposits which cause technical problems on combustion equipment are built by combustion of biogas containing siloxanes. Therefore, in these cases, the siloxanes must be removed from the biogas. For siloxane removal from biogas, its adsorption on activated carbon is often used. After saturation, the saturated adsorbent must be replaced. The adsorbent cost constitutes the main part of the operational costs of the purification equipment. Therefore it is necessary to find an adsorbent having high adsorption capacity for siloxane at a possible low price.Using laboratory apparatus and biogas produced from waste-water treatment sludge at the wastewater treatment plant Prague Bubeneč various activated carbons were tested for siloxane removal and their adsorption capacities for siloxanes were estimated, and the adsorbent cost relative to 1 kg of siloxanes removed from biogas were calculated. The lowest price for the removal of 1 kg of siloxanes was determined by Chezacarb, Sil Extra 40 AP and 4-60 adsorbents. Another important information obtained from the test is that the weakly adsorbed siloxane (OMCTS) is displaced by the larger molecule of DMCPCS during adsorption.
Power cycles using carbon dioxide in a supercritical state (sc-CO2) can be used in both the nuclear and non-nuclear power industry. These systems are characterized by their advantages over steam power cycles, e. g., the sc-CO2 turbine is more compact than the steam turbine with a similar performance. The parameters and lifespan of the system are influenced by the purity of the CO2 in the circuit, especially the admixtures, such as O2, H2O, etc., cause the enhanced structural materials to degrade. Therefore, gas purification and purity control systems for the sc-CO2 power cycles should be proposed and developed. The inspiration for the proposal of these systems could stem from the gas, especially the CO2-cooled nuclear reactors operation. The first information concerning the CO2 and sc-CO2 power cycle chemistry was gathered in the first period of the project and it is summarized in the paper.
In the Czech Republic, increasing trend exists in utilization of biomass as a fuel in heating and power plants. This is preferred solution by EU Climate plans, and it is connected with some economic benefits (e.g. green bonuses, guaranteed purchase price), on the other hand the combustion of fossil fuels is penalized (EU ETS – Emission Trading System). There are many types of biomass with different parameters but one of the most discussed are wooden resides because of its quantity. There are big differences between quality parameters, especially in moisture content, which is decreasing the LHV. There are some technologies which can decrease moisture. Dryer technologies could be simple so-lution, but final decreasing of moisture is quite low. More effective is application of flue gas condensation. This technology is well known for gas-fired boilers but nowa-days is still more often build by new solid fuels-fired plants. This deals with design of condensation technology for existing heating plant in Mladá Boleslav. The fuel mixture is based on wood residues (70 %) and pelletized plant biomass (30 %). The calculation was done for three boilers for soild fuels – two same CFBs (steam production 100 t·h-1) and one BFB (steam production 80 t·h-1). Moisture content was calculated for two cases of wooden residues with moisture content 35 and 50 %. System of condensation include three step water scrubber, heat ex-changer, heat pump and humidifier of combustion air. The final designed output of unit for BFB is 12.7 MW (19 MW for each CFBs), but from these the output of heat pump is 5 MW (7.5 MW). The source of heat for heating pumps is steam, which can be used in current heater, so the final net output from condensation is 7.7 MW (11.5 MW). These parameters are only for 50 % of moisture content in wooden residues. The application of these system is not cost-effective for moisture content of fuel around 35 %. It is possible to build this technology for 50 % of fuel moisture content, but technology will not raise the temperature parameters of hot water. There are two differences between Mladá Boleslav heating plant and Finnish Vuosaari power plant in Helsinky, where the similar unit is already built. First of them is moisture content of fuel more than 50 %. Second one is temperature of hot water system 60 °C, however in Mladá Boleslav is at least 80 °C, sometimes it could be more than 110 °C. The decreasing of this temperature is problem because the most of heating systems were designed by current standards with temperature 80 °C. The only possible solution is to build two steps scrubber and the waste heat utilize as preheater of hot water.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.