Разработка системы высококонцентрированной пылеподачи под давлением для высокореакционных топлив и энергосберегающих газовых горелок для котлоагрегатов

Проведено аналіз результатів робіт, які виконувались у різні роки щодо проблеми окислювання та самозаймання вугілля, з метою уточнення програми стендових досліджень щодо самозапалювання вугілля газової групи на спроектованому та змонтованому стенді кафедри, який призначений для досліджень граничних умов самозапалення псевдозрідженої вугільної суміші. В результаті аналізу умов окислювання вугілля встановлено, що ТЕС необхідно орієнтувати на одержання від постачальників маловідновлюваного вугілля, тому що теплові ефекти у разі реакції окислювання цього вугілля при температурі 100 0С (температура свіжого пилу в бункері) складає приблизно 2500 кДж/кг, що в 3 – 4 рази менше, ніж вугілля відновлюваного типу. Зроблено важливі висновки щодо можливості керування вмісту кисню в складі газоповітряного середовища в бункері та транспортних системах, які пов’язані з цим бункером. Для формування складу газів пневмозріджуючого та транспортуючого середовища рекомендується використання димових газів з вмістом О2 = 8 – 12 %. Запропонована система контролю псевдозрідженого середовища з використанням електрохімічних датчиків, які мають здатність формувати електричний сигнал пропорційно вмісту О2, СО в середовищі, що відповідає задачам забезпечення пожеже- вибухобезпеки вугільного пилу. Робота спрямована на створення нових видів техніки – розробку пальникових пристрїв для мікрофакельного спалювання природного газу в котлоагрегатах. Перевагою пальникових пристроїв з мікрофакельним горінням є низька чутливість до коливань тиску газу в мвгістралі, можливість сталої роботи при змінних тисках газу та повітря, більш високий , ніж у звичайних пальниках, коефіцієнт робочого регулювання – до 10 (норма – 5), можливість роботи при зміні коефіцієнту надлишку повітря від 1,02 до 10 – 20 (у звичайних пальниках – 1,02 – 1, 33), можливість формування необхідного профіля поля температур у топковому просторі. Виконано аналіз сучасних технологій та конструкцій пальникових пристроїв для спалювання газу в енергетичних котлах. Розроблені основні положення технології мікрофакельного спалювання газу за стабілізаторами та конструкції модельних пальникових пристроїв. Розроблена методика математичного моделювання робочого процесу пальникового пристрою при мікрофакельному спалюванні газу за стабілізаторами. Виконано роботи з розробки, монтажу та налагоджувальних випробувань експериментального стенду для реалізації мікрофакельного спалювання газу. Розроблена програма проведення випробувань мікрофакельних пальникових пристроїв.The analysis of results of works, which were carried out on the problem of oxidation and self-ignition of coal for improving accuracy of the program of investigation of coal self-ignition, was carried out. In the result of analysis of conditions of oxidation of coal was installed, that heat station must be oriented for supplying from suppliers low-restored coal, because heat effects from oxidation of this coal under the temperature 100 0C is about 2500 kJ/kg, that is about 3 – 4 times lower, then of restored coal. The important conclusion about possibility of regulation of maintenance of oxide in gas-air mixture in the bunker and transports systems made. For the aim of forming air-fluidising and transporting medium it is recommended to use flue gases with contents of oxygen about 8 – 12 %. It is proposed the system of controlling pseudo liquid mixture with using the electrochemical sensors, which are forming the electric signal in proportion with O2 and CO2. That is replied to the problem of provision of flame and explosion safety of coal dust. The investigation is aimed for the creation of new kinds of techniques – the development of fuel burners with microflame burning of natural gas in boilers. The advantage of these fuel burners are the low sensitivity to the pressure oscillation in the gas pipelines, the possibility of stable working under the variable gas and air pressure, the higher in comparison with usual burners the coefficient of work regulation – up to 10 (the normal level – 5), the possibility of working under changing of the coefficient of air excess from 1,02 to 10 – 20 (the normal level – 1,02 – 1,33), the possibility of forming of the necessary temperature profile in the furnace space. The analysis of up-to-date fuel-burning technology and of burners construction for gas burning in boilers is carrying out. The methods of mathematic simulation of the working process in fuel burners with micro-flame burning of gas after stabilizer is maid.Выполнен анализ результатов работ, которые выполнялись в разные годы по проблеме окисления и самовоспламенения угля, с целью уточнения программы стендовых исследований самовоспламенения углей газовой группы на спроектированном и смонтированном стенде кафедры, который предназначен для исследований условий самовоспламенения псевдоожиженной угольной смеси. В результате анализа условий окисления углей установлено, что ТЭС необходимо ориентировать на получение от поставщика маловосстанавливаемого угля, так как тепловые эффекты при реакции окисления этого угля при температуре 100 0С (температура свежей пыли в бункере) составляет около 2500 кДж/кг, что в 3 – 4 раза меньше, чем угля восстанавливаемого типа. Сделаны важные выводы относительно возможности регулирования содержания кислорода в составе газовоздушной смеси в бункере и транспортных системах, которые связаны с этим бункером. Для образования состава газов пневморазреживающей и транспортирующей среды рекомендуется использование дымовых газов с содержанием О2 = 8 – 12 %. Предложена система контроля псевдоразреженной среды с использованием электрохимических датчиков, которые имеют возможность формировать электрический сигнал, пропорциональный содержанию О2 и СО2 в среде, что отвечает задачам обеспечения пожаро- и взрывобезопасности угольной пыли. Работа направлена на создание новых видов техники – разработку горелочных устройств для микрофакельного сжигания природного газа в котлоагрегатах. Преимуществом горелочных устройств с микрофакельным сжиганием является низкая чувствительность к колебаниям давления газа в магистрали, более высокий, чем у обычных горелок, коэффициент рабочего регулирования – до 10 (норма – 5), возможность работать при изменении коэффициента избытка воздуха от 1,02 до 10 20 (у обычных горелок – 1,02 – 1,33), возможность формирования необходимого поля температур в топочном пространстве. Выполнен анализ современных технологий и конструкций горелочных устройств для сжигания газа в енергетических котлах. Разработаны основные положения технологии микрофакельного сжигания газа за стабилизаторами и конструкции модельных горелочных устройств. Разработана методика математического моделирования рабочего процесса горелочного устройства при микрофакельном сжагании газа за стабилизаторами. Выполнены работы по разработке, монтажу та наладочных испытаниях экспериментального стенда для реализации микрофакельного сжигания газа

Rich Spray-Flame Propagating through a 2D-Lattice of Alkane Droplets in Air

International audienceIn a recent numerical paper (Nicoli et al. Combust. Sci. Technol. vol. 186, pp. 103-119; 2014) [1], a model of isobaric flame propagation in lean sprays has been proposed. The initial state of the monodisperse mists was schematized by a system of individual alkane droplets initially located at the nodes of a face-centered 2D-lattice, surrounded by a saturated mixture of alkane and air. In the present study, the previous model is complemented with an original chemical scheme that allows us to study the combustion of rich alkane/air mixtures

Speciation of Arsenic in Exfoliated Urinary Bladder Epithelial Cells from Individuals Exposed to Arsenic in Drinking Water

BackgroundThe concentration of arsenic in urine has been used as a marker of exposure to inorganic As (iAs). Relative proportions of urinary metabolites of iAs have been identified as potential biomarkers of susceptibility to iAs toxicity. However, the adverse effects of iAs exposure are ultimately determined by the concentrations of iAs metabolites in target tissues.ObjectiveIn this study we examined the feasibility of analyzing As species in cells that originate in the urinary bladder, a target organ for As-induced cancer in humans.MethodsExfoliated bladder epithelial cells (BECs) were collected from urine of 21 residents of Zimapan, Mexico, who were exposed to iAs in drinking water. We determined concentrations of iAs, methyl-As (MAs), and dimethyl-As (DMAs) in urine using conventional hydride generation-cryotrapping-atomic absorption spectrometry (HG-CT-AAS). We used an optimized HG-CT-AAS technique with detection limits of 12–17 pg As for analysis of As species in BECs.ResultsAll urine samples and 20 of 21 BEC samples contained detectable concentrations of iAs, MAs, and DMAs. Sums of concentrations of these As species in BECs ranged from 0.18 to 11.4 ng As/mg protein and in urine from 4.8 to 1,947 ng As/mL. We found no correlations between the concentrations or ratios of As species in BECs and in urine.ConclusionThese results suggest that urinary levels of iAs metabolites do not necessarily reflect levels of these metabolites in the bladder epithelium. Thus, analysis of As species in BECs may provide a more effective tool for risk assessment of bladder cancer and other urothelial diseases associated with exposures to iAs

Development of low temperature dielectric coatings for electrical conductors fifteenth quarterly report

Dielectric coatings for electrical conductors at cryogenic temperature

CHARACTERIZATION OF METHANE-AIR DIFFUSION FLAMES FOR FLAME SYNTHESIS APPLICATION THROUGH OPTICAL DIAGNOSTICS

Flame synthesis is a growing field of research aiming at forming new materials and coatings through injection of seed materials into a flame. Accurate prediction of the thermal structure of these flames requires detailed information on the radiative properties and a thorough understanding of the governing combustion processes. The objective of this work is to establish a basic optical diagnostic characterization of different methane-air diffusion flames of different complexity. The basic principles are developed and demonstrated at a rotational symmetric co-flow burner and finally applied to a burner consisting of six clustered microflames which is designed for future flame synthesis work. This work focuses on the demonstration of the optical techniques for characterizing the optical emissions from diffusion flames and of the proposed method for the determination of radiating species properties from these optical measurements. In the co-flow diffusion flame setup, the fuel of methane diluted with nitrogen is provided through an inner tube while the air is applied through an outer duct surrounding the fuel nozzle. Filtered imaging and spectrally resolved measurements of the chemiluminescence of CH* and C2* and of water emission were conducted. A procedure for using the HITRAN database to support the spectroscopic analysis of the water emission was developed. In the six clustered microflames burner setup, the burner consisted of six micro-nozzles arranged in a circle surrounding a central nozzle through which air and TaN seed particles with sizes between 0.3 and 3 μm were injected. Spectrally resolved measurements of the chemiluminescence of CH* and C2* were conducted for temperature measurements. Imaging results obtained from a spectral integration of the molecular emission were compared to results from Japanese collaborators who applied a tomographic analysis method to filtered emission measurements of CH* emission which can yield spatially resolved three dimensional mapping of the flame front. The analysis of the spatial distribution of the integrated band emission of CH* and C2* showed that the emission of both species is generated at the same locations in the flame which are the thin flame sheets shown in the tomography results of CH*. The ratio of the C2* and the CH* emission from the emission spectroscopy measurements was used to determine a local equivalence ratio through empirically derived correlations for premixed flames reported in literature. Rotational and vibrational temperature distributions of CH* and C2* radicals throughout the entire flame were determined from the spectrally resolved emission from CH* and C2*. The temperatures of TaN seed particles were characterized using VIS-NIR emission spectra while varying fuel-air flow rates. The temperature profiles of the particles at various heights above the base of the central nozzle, obtained by their VIS-NIR continuum emission, showed a well-defined constant temperature region that extended well beyond the actual flame front and changed as fuel and oxidizer flow rates were varied. The results demonstrate the ability to control the duration to which seed particles are subjected to high temperature reactions by adjusting fuel and oxidizer flow rates in the clustered microflames burner

DEVELOPMENT OF COMPLEX TECHNICAL SOLUTIONS OF GAS TURBINES OPERATION’S ENVIRONMENTAL SAFETY IMPROVEMENT IN KAZAKHSTAN

Article describes results of analysis of the gas turbine usage in energy sector, on gas transmission stations and oil refinery plants. It is showed that today in Kazakhstan are operated more than 45 gas turbines on power stations and more than 250 gas turbines on gas transmission stations. Herewith on some operation modes arises problems on meeting the air emissions’ level requirements. Because of this gas turbines air emissions reduction and gas turbines’ combustion chambers improvement aimed to decrease the toxic level are contemporary issues in Kazakhstan. As a solution usage of microflame front devices is proposed.В работе представлены результаты анализа применения ГТУ в энергетике, на газоперекачивающих станциях, на нефтеперерабатывающих заводах. Показано, что в Казахстане в настоящее время эксплуатируется более 45 ГТУ на электростанциях и более 250 ГТУ на газоперекачивающих станциях. При этом на ряде режимов возникают проблемы с выполнением жестких требований по выбросам вредных веществ. Поэтому снижение вредных выбросов ГТУ и модернизация камер сгорания ГТУ с целью снижения их токсичности является весьма актуальной задачей для Казахстана. В качестве решения предлагается применение микрофакельных фронтовых устройст

Oxidation state specific analysis of arsenic species in tissues of wild-type and arsenic (+ 3 oxidation state) methyltransferase-knockout mice

Arsenic methyltransferase (As3mt) catalyzes the conversion of inorganic arsenic (iAs) to its methylated metabolites, including toxic methylarsonite (MAsIII) and dimethylarsinite (DMAsIII). Knockout (KO) of As3mt was shown to reduce the capacity to methylate iAs in mice. However, no data are available on the oxidation states of As species in tissues of these mice. Here, we compare the oxidation states of As species in tissues of male C57BL/6 As3mt-KO and wild-type (WT) mice exposed to arsenite (iAsIII) in drinking water. WT mice were exposed to 50 mg/L As and As3mt-KO mice that cannot tolerate 50 mg/L As were exposed to 0, 15, 20, 25 or 30 mg/L As. iAsIII accounted for 53% to 74% of total As in liver, pancreas, adipose, lung, heart, and kidney of As3mt-KO mice; tri- and pentavalent methylated arsenicals did not exceed 10% of total As. Tissues of WT mice retained iAs and methylated arsenicals: iAsIII, MAsIII and DMAsIII represented 55%–68% of the total As in the liver, pancreas, and brain. High levels of methylated species, particularly MAsIII, were found in the intestine of WT, but not As3mt-KO mice, suggesting that intestinal bacteria are not a major source of methylated As. Blood of WT mice contained significantly higher levels of As than blood of As3mt-KO mice. This study is the first to determine oxidation states of As species in tissues of As3mt-KO mice. Results will help to design studies using WT and As3mt-KO mice to examine the role of iAs methylation in adverse effects of iAs exposure

Selenite downregulates STAT3 expression and provokes lymphocytosis in the liver of chronically exposed Syrian golden hamsters

Arsenic is considered a worldwide pollutant that can be present in drinking water. Arsenic exposure is associated with various diseases, including cancer. Antioxidants as selenite and α-tocopherol-succinate have been shown to modulate arsenic toxic effects. Since changes in STAT3 and PSMD10 gene expression have been associated with carcinogenesis, the aim of this study was to evaluate the effect of arsenic exposure and co-treatments with selenite or α-tocopherol-succinate on the expression of these genes, in the livers of chronically exposed Syrian golden hamsters. Animals were divided into six groups: (i) control, (ii) chronically treated with 100 ppm arsenic, (iii) treated with 6 ppm α-tocopherol-succinate (α-TOS), (iv) treated with 8.5 ppm selenite, (v) treated with arsenic + α-TOS, and (vi) treated with arsenic + selenite. Urine samples and livers were collected after 20 weeks of continuous exposure. The urine samples were analyzed for arsenic species by atomic absorption spectrophotometry, and real-time RT-qPCR analysis was performed for gene expression evaluation. A reduction in STAT3 expression was observed in the selenite-treated group. No differences in PSMD10 expression were found among groups. Histopathological analysis revealed hepatic lymphocytosis in selenite-treated animals. As a conclusion, long-term exposure to arsenic does not significantly alter the expression of STAT3 and PSMD10 oncogenes in the livers of hamsters; however, selenite down-regulates STAT3 expression and provokes lymphocytosis

Preconcentration of Hydride Forming Elements in Quartz Atomizers for Atomic Absorption Spectrometry

UNIVERZITA KARLOVA V PRAZE PŘÍRODOVĚDECKÁ FAKULTA Katedra analytické chemie PREKONCENTRACE HYDRIDOTVORNÝCH PRVKŮ V KŘEMENNÝCH ATOMIZÁTORECH PRO ATOMOVOU ABSORPČNÍ SPEKTROMETRII Autoreferát disertační práce Praha 2008 RNDr. Jan Kratzer 2 OBSAH OBSAH ............................................................................................................. 2 ODBORNÝ ŽIVOTOPIS ................................................................................ 4 SEZNAM PUBLIKACÍ ................................................................................... 6 ABSTRAKT ..................................................................................................... 9 1 ULTRASTOPOVÁ ANALÝZA HYDRIDOTVORNÝCH PRVKŮ .... 11 2 CÍLE DISERTAČNÍ PRÁCE................................................................. 13 3 EXPERIMENTÁLNÍ ČÁST................................................................... 15 3.1 Aparatura............................................................................................ 15 3.2 Procedura............................................................................................ 16 3.3 Detekce atomovou absorpční spektrometrií ........................................ 18 3.4 Radiometrická měření......................................................................... 19 4...CHARLES UNIVERSITY IN PRAGUE FACULTY OF SCIENCE Department of Analytical Chemistry PRECONCENTRATION OF HYDRIDE FORMING ELEMENTS IN QUARTZ ATOMIZERS FOR ATOMIC ABSORPTION SPECTROMETRY Synopsis of the PhD Thesis Prague 2008 RNDr. Jan Kratzer 2 CONTENTS CONTENTS................................................................................................................... 2 CURRICULUM VITAE............................................................................................... 4 LIST OF PUBLICATIONS ......................................................................................... 6 ABSTRACT................................................................................................................... 9 1 ULTRATRACE ANALYSIS OF HYDRIDE FORMING ELEMENTS ....... 11 2 OBJECTIVES OF THE THESIS ...................................................................... 13 3 EXPERIMENTAL .............................................................................................. 15 3.1 Apparatus ....................................................................................................... 15 3.2 Procedure........................................................................................................ 16 3.3 Detection by atomic absorption spectrometry...Department of Analytical ChemistryKatedra analytické chemieFaculty of SciencePřírodovědecká fakult