Linking the SO2 emission of cement plants to the sulfur characteristics of their limestones: A study of 80 NSP cement lines in China

In a properly operated new suspension preheater (NSP) cement line, the SO2 emission is mainly originated from sulfides in the raw meal, and limestone, occupying about 85% wt. of the raw meal, is the dominant sulfur source. However, the sulfur characteristics of limestones and then their influences on the SO2 emission have not been clarified yet. In the present study, 80 NSP cement lines with SO2 emission > 200 mg/Nm3 were recorded, the sulfur content and species as well as pyrite morphology of limestones were analyzed and then correlated to their resulting SO2 emission. The results show that the SO2 emission of stack gas increases linearly with the SO3 content of limestone used, and sulfates lead to a 50% reduction in SO2 emission relative to sulfides. Compared with average SO2 emission, euhedral pyrite leads to a slightly higher SO2 emission, whereas metasomatic pyrite results in a lower SO2 emission, which can be attributed to the effects of accompanying elements (Ti, F, K, and Al etc.) on the desulfurization reaction and clinkerization in the whole NSP cement line. The relationships proposed can be used to predict the SO2 emission based on the sulfur characteristics of limestone and to rationally utilize high-sulfur limestone in cement industry

Process compatible desulfurization of NSP cement production: A novel strategy for efficient capture of trace SO2 and the industrial trial

Cement industry contributes to more and more SO2 emission due to utilization of alternative raw materials and fuels, whereas the available calcium-based dry flue gas desulfurization (FGD) technologies present low efficiency due to slow reversible de-SO2 reactions and short gas-solid contact time in the preheater. In the present study, the SO2 capture potentials of CaCO3, CaO, and Ca(OH)2 in the preheater environment were maximized by introducing V2O5-based catalyst and selecting optimal reaction temperature, and the de-SO2 mechanism was extensively discussed. The results showed that the de-SO2 efficiency of calcium-based adsorbents increased by 10–57 times as SO2 was effectively oxidized to SO3 in the presence of V2O5-based catalyst, then maximum de-SO2 efficiency of 75.5% was achieved using Ca(OH)2 and V2O5-CeO2 at 600 °C. Furthermore, CaCO3 assisted by V2O5-CeO2 also had a de-SO2 efficiency of 65.6%. Subsequently, a novel process compatible FGD technology was designed to maximize the de-SO2 ability of raw meal in the preheater by adding V2O5-based catalyst and humidification, the SO2 concentration of flue gas reduced from 1000 mg/Nm3 to less than 100 mg/Nm3 in the industrial-scale trial, as more sulfur was solidified into clinker in the form of alkali sulfate without reducing its properties. This novel process compatible de-SO2 strategy is of real significance for reducing SO2 emission of cement industry at low economic cost

Solar-thermal conversion and steam generation: a review

Recently, steam generation systems based on solar-thermal conversion have received much interest, and this may be due to the widespread use of solar energy and water sources such as oceans and lakes. The photo-thermal desalination system becomes attractive as it can convert absorbed solar light energy into thermal energy and realise the desalination and water purification of saline water through the evaporation process. In this paper, the research status of solar-thermal conversion materials such as metal-based materials, semiconductor materials, carbon-base materials, organic polymer materials, composite photo-thermal materials and their solar-thermal conversion mechanism in recent years are reviewed. The physical process and evaluation principle of solar-thermal conversion are both carefully introduced. The methods of optimising thermal management and increasing the evaporation rate of a hybrid system are also introduced in detail. Four main applications of solar-thermal conversion technologies (seawater desalination, wastewater purification, sterilisation and power generation) are discussed. Finally, based on the above analysis, the prospects and challenges for future research in the field of desalination are discussed from an engineering and scientific viewpoint to promote the direction of research, in order to stimulate future development and accelerate commercial application

Aging-Induced Collateral Dysfunction: Impaired Responsiveness of Collaterals and Susceptibility to Apoptosis via Dysfunctional eNOS signaling

Despite positive animal studies, clinical angiogenesis trials have been disappointing, possibly due to risk factors present in humans but usually unexplored in animals. We recently demonstrated aging causes impaired collateral remodeling and collateral dropout; here, we investigate potential mechanisms responsible for these findings. Four-, 10-, and 18-month-C57BL/6J mice were subjected to femoral artery ligation; flow was measured using laser Doppler perfusion imaging. Endothelial nitric oxide synthase (eNOS) and phosphorylated eNOS were measured in calf muscle. Apoptosis was assessed in endothelial (EC) and smooth muscle (SMC) cells isolated from young and old mice. Angiogenesis was measured using a Matrigel plug assay. Lethally irradiated young and old mice received bone marrow cells (BMC) from either young or old donors and were subjected to femoral artery ligation (FAL). BMC mobilization and homing were assessed. Flow recovery was impaired and less eNOS and phosphorylated eNOS was present in older vs. young mice (pp=0.015, respectively). ECs and SMCs from older mice were more sensitive to an apoptotic stimulus, but were rescued by NO-enhancing drugs. In older mice, angiogenesis (Matrigel plug assay) was impaired, as was mobilization and homing of BM progenitor cells following FAL. Although both mobilization and homing improved when older mice received BMC transplantation from young donors, flow recovery failed to improve. Aging impairs BMC mobilization and homing, collateral responsiveness to angiogenic stimuli, and increases EC and SMC susceptibility to apoptosis via dysfunctional eNOS signaling. The latter could contribute to impaired remodeling and collateral dropout. These finding identify potential obstacles to therapeutic interventions in elderly patients

Take Shelter in the Sun

For humans, architecture is a shelter for dwelling. People seek protection and a sense of belonging in their surroundings. Architecture should reveal the time passage, changes in weather and the character of the place in order to make a place for people to dwell. Sunlight, as an abstraction of the sun, can be received by architecture and connect the place with the universe. This thesis explores how to apply sunlight research as a meaningful tool in architecture design. The research focused on two criteria: orientation and identity. Orientation and identity are the two elements that make a location into a place and make a space into a room.Master of ArchitectureThis project is a church located by the Blue Lagoon in Iceland. Light and color are used as means to reveal the movement of the sun and express local memory. The thesis focuses on how sunlight can be introduced into a room and the atmosphere that can be created. As a result, the church is able to tell about its surroundings and make people comfortable

Preparation and Characterization of Graphene Oxide

Graphene oxide (GO) films with two-dimensional structure were successfully prepared via the modified Hummer method. It is proven that redox method is a promising way to synthesize GO films on a large scale. Comprehensive characterizations of the properties of GO films were conducted. TEM and DFM analyses showed that GO sheets prepared in this study had single and double lamellar layer structure and a thickness of 2~3 nm. X-ray diffraction (XRD) was selected to measure the crystal structure of GO sheet. Fourier-transform infrared spectra analyzer (FT-IR) was used to certify the presence of oxygen-containing functional groups in GO films. The tests of UV-VIS spectrometer and TGA analyzer indicated that GO sheet possessed excellent optical response and outstanding thermal stability. Elemental analyzer (EA) and X-ray photoelectron spectroscope (XPS) analyzed the components synthetic material. Simultaneously, chemical structure of GO sheet was described in this study. Discussion and references for further research on graphene are provided