HEAVY METAL VAPORIZATION IN FLUIDIZED BED COMBUSTION OF SOLID WASTE AND COAL

Solid samples, either of realistic waste model or coal, and spiked with Cd, Pb or Zn, were burned in an electrically-heated fluid bed reactor coupled to a customized ICP spectrometer, for on-line analysis of vaporized metals. For waste samples, a single kinetic law (whatever the metal), predicting the vaporization characteristic time and the time course of the metal concentration in the solid, was obtained. Tests with burning coal samples, spiked with Cd (at 820°C) and Zn (temperature range 680°C to 820°C), proved that this law is still valid, with a slight tendency to underestimation for both Cd and Zn vaporization rates. The transient metal concentration in burning coal was also very well predicted

The presence of senescent peripheral T-cells is negatively correlated to COVID-19 vaccine-induced immunity in cancer patients under 70 years of age

PurposeCancer patients are at risk of severe COVID-19 infection, and vaccination is recommended. Nevertheless, we observe a failure of COVID-19 vaccines in this vulnerable population. We hypothesize that senescent peripheral T-cells alter COVID-19 vaccine-induced immunity.MethodsWe performed a monocentric prospective study and enrolled cancer patients and healthy donors before the COVID-19 vaccination. The primary objective was to assess the association of peripheral senescent T-cells (CD28-CD57+KLRG1+) with COVID-19 vaccine-induced immunity.ResultsEighty cancer patients have been included, with serological and specific T-cell responses evaluated before and at 3 months post-vaccination. Age ≥ 70 years was the principal clinical factor negatively influencing the serological (p=0.035) and specific SARS-CoV-2 T-cell responses (p=0.047). The presence of senescent T-cells was correlated to lower serological (p=0.049) and specific T-cell responses (p=0.009). Our results sustained the definition of a specific cut-off for senescence immune phenotype (SIP) (≥ 5% of CD4 and ≥ 39.5% of CD8 T-cells), which was correlated to a lower serological response induced by COVID-19 vaccination for CD4 and CD8 SIPhigh (p=0.039 and p=0.049 respectively). While CD4 SIP level had no impact on COVID-19 vaccine efficacy in elderly patients, our results unraveled a possible predictive role for CD4 SIPhigh T-cell levels in younger cancer patients.ConclusionsElderly cancer patients have a poor serological response to vaccination; specific strategies are needed in this population. Also, the presence of a CD4 SIPhigh affects the serological response in younger patients and seems to be a potential biomarker of no vaccinal response

Modeling kinetics of Cd, Pb, and Zn vaporization during municipal solid waste bed incineration

The fate of heavy metals contained in municipal solid waste is of major concern in the incineration process. This study is the first attempt to analyze the kinetic behavior of Cd, Pb, and Zn in a waste bed burning on the grate of an incinerator. The vaporization rates of the three heavy metals were derived from laboratory experiments. The kinetic law was then introduced into Garbed-ss, a mathematical model of the on-grate incineration of a refuse bed. Results show that the calculated vaporization of the three metals is fast, proceeds to nearly full completion, occurs at the pyrolysis front, and is indeed controlled by the thermal degradation of the waste. Alhough in agreement with thermodynamic calculations, the vaporization of lead and zinc seems to be overestimated. The model would be improved by accounting for the initial physical and chemical speciation of the heavy metals in the waste feed. © 2010 American Chemical Society

Numerical Study of a Structured Thermocline Storage Tank Using Vitrified Waste as Filler Material

AbstractThermocline storage may be, today, the cheapest way to store solar thermal energy at high temperatures. Several estimations lead to a potential cost reduction of 35% compared to a two tank configuration while retaining a good efficiency. Thermocline tanks, in packed bed configurations, are mostly designed using filler materials to reduce the required amount of the expensive molten salt. The main problem of this technology is the thermal ratcheting which can lead to dramatic structural failure of the tank. One solution could be to use a structured bed configuration. With this goal, and as a part of the OPTS Project (OPtimization of a Thermal energy Storage system with integrated Steam Generator), after preliminary investigations driven by the necessity to have a low manufacturing cost, a brick design, made of industrial wastes, is proposed allowing both good thermal and mechanical properties. The implementation of the tank with the filler material of this geometry does not require a specific know- how other than building a classic wall. In order to study the behavior of the thermocline in this structured configuration, a numerical model is developed. A parametrical study was performed and the results are presented and discussed in this paper. The influences of the geometrical ratio of our ‘pattern’, of the physicals properties of the storage material and of the flow rate of the solar salt inside the tank are characterized. The aim is to study the theoretical feasibility of a direct high temperature structured thermocline tank for concentrated solar power, using cheap filler materials

Impact of thermal energy storage integration on the performance of a hybrid solar gas-turbine power plant

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Simulation of a Hybrid Solar Gas-turbine Cycle with Storage Integration

AbstractThe interest for hybrid solar gas-turbine systems (HSGT) in solar tower plant technologies is growing This is due to the high conversion efficiency and to the low water consumption that are achieved when a combined cycle is implemented. This paper presents a simulation tool which is dedicated to the performance analysis of the top cycle featuring a thermal energy storage unit (TES). The influence of the TES operating conditions on the power plant production is highlighted. A major advantage of the storage is to stabilize the air temperature at the combustion chamber inlet in order to keep the operating conditions of the combustion chamber close to the design point. This work establishes that a higher and more stable electrical generation is achieved through this concept. According to the storage capacity, the TES unit increases the daily average solar share of the power plant. This study is conducted within the framework of the French PEGASE project (Production of Electricity from Gas and Solar Energy) which aims at setting up and testing at THEMIS site (France) a demonstration plant based on HSGT technology

Experimentation of a High Temperature Thermal Energy Storage Prototype Using Phase Change Materials for the Thermal Protection of a Pressurized Air Solar Receiver

International audienceThe work addresses the issue of fast variations of temperature of a central solar receiver under cloud covering. A specific attention is paid to the situation of Hybrid Solar Gas Turbine (HSGT) systems using pressurized air as Heat Transfer Fluid (HTF), as it is considered in the Pegase project (France). A Thermal Energy Storage (TES) unit integrated in the receiver is proposed for smoothing the variation of temperature. The technology is based on the utilization of both Phase Change Material (PCM) and metallic fins in order to enhance charge and discharge capability of the storage unit. A test-bench is designed with copper fins and is experienced with paraffin wax and with Li 2 CO 3 successively as PCMs. In the same time, the test unit is modeled and the charging and discharging modes are simulated. The results show that the full charging is achieved in about 4 hours starting from 700 °C when the receiver is maintained at 900°C, whereas the discharge from 900°C to 700°C is achieved in 2.5 hours

Development of a Thermal Energy Storage Pressed Plate Ceramic Based on Municipal Waste Incinerator Bottom Ash and Waste Clay

International audiencePressed plates ceramics made of gross-milled bottom ashes and waste clay, were made using technologies available in the building bricks and tiles industry, to ease production upscaling at low-cost. These sintered ceramics are intended for use as a high-temperature thermal energy storage material. They represent an alternative to the waste-based petrurgic ceramics previously developed for this application. Post-treated incinerator bottom ashes from a commercial incinerator were collected, characterized and processed to form ceramic materials, using clay as a binder. Ashes were milled, dried, and mixed with various amounts of an illitic clay (produced as washing mud by a quartz quarry in proportions from 20 to 70% dry weight) prior to uniaxial pressing (12 × 5 × 1 cm slabs) and firing at various temperatures, ranging from 1050 to 1125 °C. The sintered samples have been characterized in terms of volumic mass, mechanical strength, thermal capacity and thermal conductivity. Their mineral structure has also been studied. The resulting sintered ceramics exhibit relatively high mechanical resistance and low thermal conductivity, along with moderate volumic mass. These properties allow envisioning the use as filler material for thermocline thermal storage systems (structured beds), and could be interesting for further work regarding applications in the construction field (bricks, tiles, pavements…)