Stand-alone hydrogen generator based on the chemical decomposition of water by aluminum

Milinchuk, V.K.; Klinshpont, E.R.; Belozerov, Vladimir Ivanovich

doi:10.26583/npe.2015.2.05

Cited by 2 publications

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“…According to the coolant quality standards, the total concentration of alkali metal ions in the hot state of a VVER unit is ~ 3.0 mg/dm 3 and is achieved by introducing alkali metal hydroxides into the primary circuit coolant in the amount depending on the concentration of boric acid and enabling the hydrogen potential to be kept at a level of pH = 5.8-10.3 (Yefimov et al 1983, Shkolnikov et al 2008, Klinshpont et al 2012, 2015. No influence of alkali metals on the hydrogen formation in the process of the water coolant interaction with the reactor structural materials has been investigated as part of this problem.…”

Section: Introductionmentioning

confidence: 99%

Generation of hydrogen by hydroheterogeneous compositions based on aluminum and alkali metals

Askhadullin

Milinchuk²

2021

NUCET

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The process of hydrogen formation and the associated risk of combustion and explosion is a complex problem concerned with the hydrogen and radiation safety of nuclear reactors. Lithium, potassium and sodium hydroxides are used in VVER reactors as corrective additives for keeping the hydrogen potential of the water coolant with boric acid at a controlled level of 5.8 to 10.3. In the process of investigating the interaction of aqueous solutions of the above hydroxides with aluminum, the most chemically active of these is lithium hydroxide; this reaction proceeds with hydrogen formed at a high rate at room temperature (in an exothermic mode). The processes of hydrogen generation in hydroheterogeneous compositions with potassium and sodium hydroxides proceed at an acceptable rate with heating to ~ 60 °C. The kinetics of hydrogen generation depends in a complex way on the content of boric acid, namely, the hydrogen yield is at a level of ~ 1000 ml at a low concentration of 0.01 to 0.05 g/l, and there is no hydrogen formation at a concentration of 0.6 g/l. According to the coolant quality standards, in the hot state of a VVER-1000 unit or in the reactor state at the minimum controlled power level, the total concentration of alkali metals is about 1 mg/dm3, i.e. two to three orders of magnitude as less as in the investigated compositions. The discovery of the influence of alkali metal hydroxides on the formation of hydrogen with the participation of structural materials based on the example of aluminum makes it possible to suggest that the hydroxides of these metals contained in the coolant in a small amount can also take part in the hydroheterogeneous process of formation of minor hydrogen amounts. The potential for hydrogen formation in such a way needs to be taken into account during long-term operation of nuclear reactors, and during accidents and incidents at NPPs

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Section: Introductionmentioning

confidence: 99%

Generation of hydrogen by hydroheterogeneous compositions based on aluminum and alkali metals

Askhadullin

Milinchuk²

2021

NUCET

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Кинетика Окисления Порошка Алюминия В Воде В Реакторе Идеального Смешения При Порционной Подаче Реагента

Morozova¹,

Кудряшова²,

Павленко³

2021

Южно-Сибирский Научный Вестник

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В работе рассматривается реакция окисления мелкодисперсного порошка алюминия водой в реакторе идеального смешения. На основе полученных ранее данных о макрокинетике реакции взаимодействия дисперсного алюминия с водой теоретически рассматриваются режимы порционной подачи порошка в реактор. Решение проблемы поиска кинетических параметров реакции дисперсного алюминия с водой актуально в связи с разработкой источников водорода для питания топливных элементов. Задача оптимизации режимов генерации водорода в реакции алюминий-вода встает в связи с тем, что динамика реакции взаимодействия алюминия высокой дисперсности с водой носит экстремальный характер с резким нарастанием давления водорода и резким спадом. С другой стороны, в технологиях, использующих водород как топливо, необходимо равномерное поступление газа к топливному элементу. Рассматривается реактор идеального смешения, содержащий нагретую воду (80°С), в который через некоторые промежутки времени (10–270 с) подается порошок алюминия. Определяется степень превращения алюминия, и скорость образования водорода в зависимости от времени. В расчетах принимаются кинетические параметры порошка марки Alex; считается, что масса воды существенно превышает стехиометрическую. Проводится сравнение динамики протекания реакции для случаев единовременной загрузки порошка в реактор и порционной подачи с разными промежутками времени. Показано, что при порционной подаче водород генерируется, практически, в стационарном режиме, и теплового взрыва в результате экзотермической реакции не происходит. Найденные закономерности протекания реакции в дальнейшем могут быть использованы для расчета технических параметров систем генерации водорода. The paper considers the reaction of oxidation of finely dispersed aluminum powder with water in an ideal stirred reactor. Based on the previously obtained data on the macrokinetics of the reaction of the interaction of dispersed aluminum with water, the modes of portion feeding of the powder into the reactor are theoretically considered. Solving the problem of searching for the kinetic parameters of the reaction of dispersed aluminum with water is important in connection with the development of hydrogen sources for fuel cells. The problem of optimizing the modes of hydrogen generation in the aluminum-water reaction arises in connection with the fact that the dynamics of the interaction of highly dispersed aluminum with water are extreme with a sharp increase in hydrogen pressure and a sharp decline. On the other hand, technologies that use hydrogen as a fuel require a uniform supply of gas to the fuel cell. An ideal stirred reactor containing heated water (80 ° C) is considered, into which aluminum powder is fed at some time intervals (10–270 s). The degree of conversion of aluminum and the rate of formation of hydrogen as a function of time is determined. The calculations are based on the kinetic parameters of the Alex brand powder; it is believed that the mass of water significantly exceeds stoichiometric. The dynamics of the reaction are compared for the cases of a one-time loading of the powder into the reactor and portion feeding with different time intervals. It is shown that, with portion feeding, hydrogen is generated practically in a stationary mode, and no thermal explosion occurs as a result of an exothermic reaction. The found regularities of the course of the reaction can be used in the future to calculate the technical parameters of hydrogen generation systems.

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Stand-alone hydrogen generator based on the chemical decomposition of water by aluminum

Cited by 2 publications

References 0 publications

Generation of hydrogen by hydroheterogeneous compositions based on aluminum and alkali metals

Generation of hydrogen by hydroheterogeneous compositions based on aluminum and alkali metals

Кинетика Окисления Порошка Алюминия В Воде В Реакторе Идеального Смешения При Порционной Подаче Реагента

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