Development of a sorbent for carbon dioxide

The reversible absorption of CO2 by CaO at high temperature is a promising method for capturing and removing CO2 from a hot gas stream. The main challenge facing the use of this method is the deterioration of CO2 absorption capacity when the method is applied over a large number of CO2 absorption/desorption cycles. Although various techniques have been proposed for improving the cyclic stability and performance of calcium based sorbents, a cost effective method is still needed for industrial applications. Therefore, two promising methods for improving the cyclic stability were selected for further investigation. One method is to optimize the preparation conditions applied to various particle sizes of CaO precursors while the second method involves incorporating an inert material, MgO, in the sorbent. While applying the first method, it was discovered that the absorption capacity and stability of a sorbent derived from limestone is dependent on many factors including the initial calcination atmosphere, temperature and time as well as particle size. It was found that both the absorption capacity and stability were greater for a sorbent derived from 11 ym limestone particles than for one derived from a much coarser material. It was also found that by calcining the 11 ym limestone at 1000oC for 1 hr in 50 vol% CO2, the resulting sorbent had an initial absorption capacity of 7 mmol CO2/g sorbent which only declined to 6.3 mmol CO2/g sorbent over 80 cycles of CO2 absorption/regeneration. A sorbent prepared by calcining calcium acetate at 1000oC for 1 hr in an atmosphere containing from 50 to 100% CO2 exhibited the highest absorption capacity among the materials tested. It was also reasonably stable over 40 cycles tested. One of the most promising sorbents was prepared from plaster of Paris (calcium sulphate hemihydrate) by treating the material with a cyclic oxidation/reduction process at 1070oC. This sorbent exhibited an increasing trend in absorption capacity throughout a 200 cycle test of CO2 absorption and desorption. For the second method for improving the cyclic stability of the sorbent, small amounts of MgO were incorporated in a sorbent as an inert diluent and structural stabilizer. It appeared that addition of MgO improved the performance of the sorbent in some cases depending on both the source of MgO and calcination conditions. However, this method did not seem to offer an advantage over the use of dolomite (calcium magnesium carbonate) alone, especially when the particle size of the dolomite was reduced by grinding so that it was more nearly comparable to that of the 11 ym limestone. A sorbent prepared by calcining the ground dolomite at 1000oC for 1 hr in N2 had an absorption capacity in excess of 8 mmol CO2/g sorbent over 80 cycles of CO2 absorption/desorption

Lessons learned from Turkey's international mediation efforts in Syrian-Israeli and Palestinian-Israeli conflicts since 2002: impact of impartiality of the mediator on the mediation outcomes

The thesis aims to explore influence of impartiality of the Turkey's mediation efforts since 2002 in the conflicts of Israel-Syria and Israel-Palestine on the Turkey's mediation outcomes perceived by the disputants which are Israel, Palestine and Syria. This research examines the mediation process as a triangular process rather than dyadic by taking every disputants' perception towards the mediator into account. To this aim, comparative case study is used which is Turkey's mediation efforts in Syrian- Israeli and Israeli- Palestinian conflicts since 2002. The research consists of a textual analysis and in depth interviews. Most of the data used in this study derived from the official declarations of high level policy makers of Turkey, Israel, Palestine and Syria since 2002 as well as qualified newspaper accounts and academic writings. In order to complement those sources, interviews were conducted with the high level foreign policy makers of Turkey. Based on the research, the findings show that Turkey as a mediator could utilize its partiality by establishing a balanced relative bias towards disputants in order to achieve successful outcomes. Secondly, the distinction should be made between impartiality in attitude and impartiality in behavior. Accordingly, Turkey's impartiality in behavior, not necessarily impartiality in attitude; has a more positive influence on achieving successful outcomes

Techno-economic study of the calcium looping process for CO2 capture from cement and biomass power plants

The first detailed systematic investigation of a cement plant with various carbon capture technologies has been performed. The calcium looping (Ca-looping) process has emerged as a leading option for this purpose, since this process applied to a cement plant provides an opportunity to use the CaO purge for clinker production. The Ca-looping process is comprised of two interconnected reactors where the carbonator captures CO2 from flue gases and the calciner regenerates the CaCO3 into CaO by oxy-combustion. Fully integrated process flowsheets have been developed and simulated in UniSim Design Suite from Honeywell. The detailed carbonator model has been implemented using Matlab and incorporated into UniSim to provide a full flowsheet simulation for an exemplary dry-feed cement plant as a user-defined operation. The base cement plant simulation was also modified to integrate three different carbon capture processes: membrane; indirect calcination; and amine-scrubbing. Furthermore, an advanced configuration of Ca-looping process has been investigated where the energy intensive air separation unit was replaced with a chemical looping combustion (CLC) cycle. Each case has been optimised to minimise its energy consumption and compared in terms of levelised cost of cement and its resulting cost of CO2 avoided at the same CO2 avoidance rate. The proposed integration of the Ca-looping process is capable of achieving over 90% CO2 avoidance with additional fuel consumption of 2.5 to 3.0 GJth/ton CO2 avoided. By using an advanced configuration of the Ca-looping process with a CLC cycle, the additional fuel consumption can be reduced to 1.7 GJth/ton CO2 avoided, but the cost of the oxygen carrier is the major concern for this system. Among the other CO2 capture options, the membrane process is a promising alternative for the Ca-looping process since it has a potential of achieving the target CO2 avoidance rate and purity requiring lower energy consumption. The indirect calcination process provides moderate levels of CO2 avoidance (up to 56%) without a need of an external capture process whereas the integration of the amine process in a cement plant is challenging as a result of the requirement of steam for solvent regeneration. Furthermore, considering zero net CO2 emissions associated with biomass combustion systems, a novel concept has been analysed to capture of CO2 in-situ with the Ca-looping process while operating the combustor of a dedicated biomass power plant at sufficiently low temperature. This process is capable of achieving 84% overall CO2 capture rate with an energy penalty of 5.2% when a proper heat exchanger network is designed with the support of a pinch analysis. The techno-economic performance of the biomass power plant with in-situ Ca-looping CO2 capture process was compared with that of the alternative biomass-air-fired and biomass-oxy-fired power plants

Determination of Concentration for Some Priority Substances in Paddy Fields of Ergene River, Meriç River, and Yenikarpuzlu Dam, Turkey

This study was intended in paddy (rice husk and rice), sediment, and irrigation water samples taken from the paddy fields of Ergene River, Meriç River, and Yenikarpuzlu Dam reservoir which are frequently grown in the river basin in Thrace region and endosulfan (EN) and PAHs were investigated. For analysis, EN and PAHs were studied by GC-MS. The data obtained as a result of the analyses were compared with the results of the standard reference items, and the accuracy of the results was determined. The standard addition method was used to prove the accuracy of EN and PAHs. The recovery parameters on the extraction efficiency of EN and PAHs were optimized, and the recoveries ranged from 82 to 105%. The methods showed good linearity for EN and PAHs, and the LOD and LOQ for methods were found 0.03–63.1 and 0.1–210 μg kg−1, respectively

The effect of supply chain agility on firm performance during COVID-19 pandemic: the mediating and moderating role of demand stability

The aim of this paper is to analyse the effects of supply chain agility on firm performance and the role of demand stability in this relationship. Within the scope of the research, by establishing a SEM (structural equation modelling), effects of supply chain agility and demand stability on firm performance were investigated. In addition, the effect of supply chain agility on demand stability is also observed. Analyzes have shown that during COVID-19 pandemic period, supply chain agility positively affects demand stability and firm performance. In addition, demand stability has positively affected firm performances. The mediating role of demand stability was analysed with the Process Macro method and its moderating effect was analysed with multiple regression. Analysis results showed that demand stability has a mediating role in the effect of supply chain agility on firm performance, but it doesn't have a moderating role

A Hybrid Carbon Capture System of Indirect Calcination and Amine Absorption for a Cement Plant

AbstractHere we present the process integration of the indirect calcination process existing in the literature [1] into a cement plant. The indirect calcination process is composed of a circulating fluidized bed combustor and a fluidized bed calciner where hot solid particles are circulated between those reactors for heat transfer. It allows separation of CO2 from limestone calcination in a concentrated form. The process integration proposed in this study minimizes the total thermal energy requirement by using excess energy from high temperature flue gases for cement raw meal preheating as in the conventional cement manufacturing process. It also suggests a new hybrid carbon capture system where an additional CO2 capture unit is combined with the indirect calcination process, since the standalone indirect calcination application can only provide a moderate level of CO2 avoidance. The amine process is added to increase CO2 avoidance rate further. Full process flowsheets have been developed and analyzed using the commercial software UniSim Design R400 from Honeywell. The hybrid system can achieve more than 90% carbon capture rate thanks to the supplementary amine process while the indirect calcination can capture only 56% without the amine process. With the support of a simple and transparent economic analysis, the capture cost involved in the hybrid system was estimated to be higher than that of the indirect calcination only but significantly lower than that of the standalone amine process on a basis of unit CO2 avoided

Genetic polymorphism in the serotonin transporter gene-linked polymorphic region and response to serotonin reuptake inhibitors in patients with premature ejaculation

OBJECTIVES: Serotonin plays a central role in ejaculation and selective serotonin reuptake inhibitors have been successfully used to treat premature ejaculation. Here, we evaluated the relationship between a polymorphism in the serotonin transporter gene-linked polymorphic region (5-HTTLPR) and the response of patients with premature ejaculation to SSRI medication. METHODS: Sixty-nine premature ejaculation patients were treated with 20 mg/d paroxetine for three months. The Intravaginal Ejaculatory Latency Time and International Index of Erectile Function scores were compared with baseline values. The patients were scored as having responded to therapy when a 2-fold or greater increase was observed in Intravaginal Ejaculatory Latency Time compared with baseline values after three months. Three genotypes of 5-HTTLPR were studied: LL, LS and SS. The appropriateness of the allele frequencies in 5-HTTLPR were analyzed according to Hardy-Weinberg equilibrium using the χ2-test. RESULTS: The short (S) allele of 5-HTTLPR was significantly more frequent in responders than in nonresponders (

Process simulation of Ca-looping processes: review and guidelines☆

Abstract Ca-looping is one of the most promising processes for CO 2 capture in short to medium term plants, which can be applied for both post-combustion and pre-combustion layouts. The recent successful operations of MW-scale pilot plants are leading to an increased interest in this technology. In addition, the particularly advantageous applicability in cement plants, the main industrial contributors to CO 2 emissions worldwide, can further lead to a forthcoming development of the technology. Quite a large amount of scientific papers on reactors and process modeling has been published in the recent years and more studies are expected to be published in the future. According to the experience of the authors in this field and on the basis of a literature review, suggestions and modeling needs for next works are provided in this paper