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Post by peterberg on Nov 7, 2018 1:41:42 GMT -8
Just wondering: is the first port plus the expansion room and secondary air inlet really necessary in this construction? Maybe the tangentially air inlets are enough to let the gases spin around in rapid motion, mixing should be excellent. This type of air inlets are employed in coal powder furnaces, as far as I am aware of.
Last year I've seen an example of that in Montana, the fire brigade that monitors the woods had a large demonstration model in order to show how a flame pattern develops in a firestorm. The thing wasn't fed with wood fuel by the way, just a small saucer filled with alcohol but the flames were enormous, raging up a vertical pipe with a loud rustling noise. The construction was just a static thing with no moving parts or ventilators, just the type of combustion enclosures I am fond of.
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furno
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Post by furno on Nov 7, 2018 5:01:53 GMT -8
I tried to use tangential entry for tertiary air. However, it is not yet clear that there is more benefit from the turbulence of the flow or the harm from its cooling. The problem is to twist the flow, you must introduce quite a lot of air. Excess air increases alpha and lowers the temperature of gases. Therefore, I probably refuse to use tertiary air. But devices for turbulence and swirling flow, without the supply of tertiary air, should be at the entrance of the flow into the riser.
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furno
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Post by furno on Oct 16, 2020 2:00:36 GMT -8
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Post by Jura on Oct 16, 2020 2:48:01 GMT -8
I built a similar heating stove a year ago. I already wrote about the beginning of the project in my thread. donkey32.proboards.com/post/30805/thread..... If there is interest in my project, then I can describe it in more detail in my thread. I have absolutely missed the thread with your set up. Have you got links to any description in RU LNG ? I can read it and understand so you'd not have to rewrite description of your project from the scratch. As to the photo: AFAIK - Adding air from beneath the firebox always caused huge increase in CO emission. |
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furno
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Post by furno on Oct 16, 2020 4:20:35 GMT -8
I have absolutely missed the thread with your set up. Have you got links to any description in RU LNG ? I can read it and understand so you'd not have to rewrite description of your project from the scratch. As to the photo: AFAIK - Adding air from beneath the firebox always caused huge increase in CO emission. It is not true. The CO level depends primarily on the alpha. Much also depends on the combustion mode. In itself, the presence or absence of a grill does not set the fuel combustion mode. The grill mode is very useful during the coal combustion phase. And the closed-bottom mode is preferable in the active combustion phase and makes the wood burning more uniform. [rus] Это не так. Уровень СО зависит от альфы в первую очередь. Так же много зависит от режима сгорания. Само по себе наличе или отсутсвие колосника не задает режима сгорания топлива. Колосниковый режим очень выгоден на фазе дожига углей. А подовый режим предпочтительнее в фазе активного горения и делает более равномерным сгорани дров. К сожаленинию я затрудняюсь найти точный перевод русским терминам "подовый и колосниковый режим". Поэтому использовал "grill" и "closed-bottom". |
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Post by Vortex on Oct 16, 2020 6:09:12 GMT -8
This is not true. The CO level depends on alpha in the first place. Much also depends on the combustion mode. By itself, the presence or absence of a grate does not set the fuel combustion mode. The grate mode is very beneficial in the phase of coal combustion. And the hearth mode is preferable in the active combustion phase and makes the combustion of firewood more uniform. Unfortunately, I find it difficult to find an exact translation of the Russian terms "hearth and grate regime". So I used "grill" and "closed-bottom". My testo results showed this to be true in the coaling phase, but if a hole burned through the coals so that air could easily pass, then the carbon monoxide would shoot up again. I think the Austrian method (of closing off all the air during the coaling phase to leave them as charcoals to be burnt in the combustion phase of the next fire) is a more elegant solution. I do not understand what: "The CO level depends on alpha in the first place." means, can you please explain. Maybe it is a bad translation. |
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furno
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Post by furno on Oct 16, 2020 9:30:09 GMT -8
Stopping the air supply to the firebox will extinguish the coals. But you are not using some of the fuel. Mechanical underburning increases sharply. This reduces overall efficiency. Therefore, this is a bad decision. When I spoke about the dependence of CO on alpha, I meant the combustion of coal on the grate. There is no free oxygen above the coal bed and alpha is less than 1. But CO is maximum. ibb.co/mFjkKDc[rus] Прекращая подачу воздуха в топку вы затушите угли. Но вы не используете часть топлива. Резко растет механический недожег. Это снижает общую эффективность. Поэтому это плохое решение. Когда я говорил о зависимости СО от альфа, то имел ввиду горение угля на решетке. Над слоем угля нет свободного кислорода и альфа меньше 1. Но СО максимален. |
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Post by Jura on Oct 16, 2020 13:05:25 GMT -8
I do not understand what: "The CO level depends on alpha in the first place." means, can you please explain. Maybe it is a bad translation. I believe by alfa " furno " meant "lambda". am I right? During my tests amount of air provided in the coaling phase had no significant influence on emissions. Only when it was provided from the beneath the CO sky rocketed. Well..I'd tend to shut off the air in the coaling phase and burn thus created char coal bed with next batch. ibb.co/mFjkKDc I'd need a legend for the sketch from this image. It seems to me I get the idea from the graph but.. need to now what are the corresponding layers presented related to. Theanks for the link. I recalled I started to read it year in2019.. But it was some 20 pages.. now it's 167. my lord.. EDIT: update: I found the source and the description of the image provided by Vladimir studopedia.org/2-125652.htmlIt deals with burning coal.. the kinetics are absolutely different than in the case of burning wood only. |
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Post by Vortex on Oct 17, 2020 1:49:13 GMT -8
The grill mode is very useful during the coal[ing] combustion phase. And the closed-bottom mode is preferable in the active combustion phase and makes the wood burning more uniform. My testo results showed this to be true in the coaling phase, but if a hole burned through the coals so that air could easily pass, then the carbon monoxide would shoot up again. I think the Austrian method (of closing off all the air during the coaling phase to leave them as charcoals to be burnt in the combustion phase of the next fire) is a more elegant solution. During my tests amount of air provided in the coaling phase had no significant influence on emissions. Only when it was provided from the beneath the CO sky rocketed. I believe the above statements are all true and not contradictory, because if there is enough gas present in the afterburner of the Vortex core to ignite, then the carbon monoxide is burned in the vortex. By providing air up through the grate it boosts the gas production which enables efficient combustion of the carbon monoxide in the afterburner, giving lower carbon monoxide readings at the testo. |
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furno
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Post by furno on Oct 17, 2020 13:47:24 GMT -8
Indeed, the combustion mechanism in the gasification zone is somewhat different from that in a layer of coal. The fuel layer, consisting of firewood, does not have a clear boundary due to the size of the pieces of wood and the unevenness of their heating. Regions are formed along the surface of the layer, channels of wood pieces into which both external air and pyrolysis gas enter simultaneously. Conditions are created for combustion in both flame and smoldering modes. Such combustion in the bed was considered and named by different researchers. Micro-furnaces at Khoshev, coal canals at Kontorovich, a system of gas burners at Knorre. Most of the thermal energy obtained from combustion in this layer is spent on maintaining and self-reproducing the combustion process. That is, for heating pieces of wood for its thermal destruction. But eventually a layer of ordinary coal forms. Combustion in a coal bed is well studied. I showed the drawing and graphs when burning in a layer of coal. [rus] Действительно механизм горения в зоне газификации несколько отличается от горения в слое угля . Слой топлива, состоящий из дров , не имеет четкой границы из за крупности кусков древесины и неравномерности их нагрева. По поверхности слоя образуются области, каналы из кусочков древесины в которые одновременно поступает и внешний воздух и пиролизный газ. Создаются условия для горения как в пламенном , так и в тлеющем режиме. Такое горение в слое рассматривали и по разному называли различные исследователи.. Микротопки у Хошева, угольные каналы у Конторовича, система газовых горелок у Кнорре. Большая часть тепловой энергии получаемой от горения в этом слое расходуется на поддержание и самовоспроизведение процесса горения. Т.е на нагрев кусков древесины для ее термодеструкции. Но в конечном итоге образуется слой обычного угля. Горение в слое угля хорошо изучено. Я показывал рисунок и графики при горении в слое угля. |
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furno
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Post by furno on Oct 20, 2020 13:02:35 GMT -8
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Post by Jura on Oct 20, 2020 15:46:04 GMT -8
I will tell you a little about my heating furnace. Thank you for your input, Vladimir I believe your stove deserves its own topic here on Donkeys. It would be nice to get know more solutions applied and be able to ask you questions. It's hard to do so in here as we'd flood the Vortex thread. (I got through 47 pages of the topic on stroiteli forum but it's been flooded a bit, I saw a bit of the stove innards on the photos.) UPDATE: I'm sorry I was sure it was vortex thread. I'm dead tired today. so did not notice we write in your thread |
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furno
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Post by furno on Oct 22, 2020 2:49:03 GMT -8
Basic principles of building a firebox. - separation of combustion phases and heat extraction. Heat extraction is prohibited in the firebox. - achievement of the maximum flow rates of the gases of the flame and their turbulence. - achievement of high heat density in the area of the flame torch and port. - air inlet at maximum speeds. Slotted nozzles and thin gaps. - combination of hearth and grate modes. - implementation of the half-gas mode in the phase of active release of wood gas. Structurally, it consists of a power frame made of red brick on the edge. The firebox is lined with 40mm chamotte bream standing dry in a load-bearing frame. Depending on the needs, the firebox can operate in grate and hearth modes. In the rear and side bricks of the niche, channels with narrow slotted nozzles are provided for supplying primary air. Air under the grate and into the side slots is supplied through different channels, which allows you to combine types of air supply. The overlap of the firebox lining is made of fireclay bricks, which lie freely on the walls of the lining. The ceiling has a rectangular port (hailo). There is a prechamber above the firebox overlap. The gas flow behind the port strikes the upper overlap of the forchamber, which leads to an additional flow turbulator and activation of combustion. The chamber is made of a ceramic fiber slab. The exit from the chamber goes into a rectangular riser, also lined with ceramic fiber plates. The dimensions of the lining slabs, floor slabs and the displacement chamber are selected so that the entire firebox can be moved through the front opening, which is made removable and closed by a frame with a furnace and blower doors. The grate lies in a niche made of chamotte bricks beveled at an angle of 60 degrees. Such a slope allows the coals to roll freely onto the grate when it burns out and excludes poking and opening the furnace door. The niche bricks are dry and can be easily replaced. Combustion air is supplied from under the floor and through the blower door. [rus] Основные принципы построения топки. - разделения фаз горения и отбора тепла. В топке отбор запрещен. - достижение максимальных скоростей потока газов факела и их турбулизация. - достижение высокой теплонапряженности в зоне пламенного факела и порта. - ввод воздуха на максимальных скоростях. Щелевые сопла и тонкие прозоры. - комбинирование подового и колосникового режимов. - реализация режима полугаза в фазе активного выхода летучих. Конструктивно состоит из силовго каркаса , выполненной из красного кирпича на ребро. Топливник футерован шамотной лещакой 40mm стоящей насухо в силовом каркасе. В зависимости от потребностей топливник может работать и в колосниковом и подовом режиме. В задней и боковых кирпичах ниши предусмотены каналы с узкими щелевыми соплами для подачи ПВВ . Воздух под колосник и в боковые щели подается по разным каналам , что позволяет комбинировать типы подачи воздуха. Перекрытие футеровки топливника сделано из шамотных кирпичей , которые свободно лежит на стенках футеровки. В перекрытии находится прямоугольное плохообтекаемое хайло (порт). Над перекрытием топливника находится форкамера . Поток газов за портом ударяется в верхнее перекрытие форкамеры , что приводит к дополнительной турбулизатор потока и активации сгорания. Камера выполнена из плиты керамоволокна. Выход из камеры идет в прямоугольный райзер, также футерованный плитами из керамоволокна. Размеры плит футеровки , перекрытия и камеры смещения подобраны так, что вся топка может быть перебрана через фронтальный проем, который сделан съемным и закрывается рамой с топочной и поддувальной дверками. Колосник лежит в нише из скошенных под углом 60 градусов шамотных кирпичей. Такой уклон позволяет углям свободно скатываться на колосник при догорании и исключает шуровку и открытие топочной дверцы. Кирпичи ниши стоят насухо и могут быть легко заменены Предусмотрена подача воздуха на горение из под пола и через поддувальную дверку.       |
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furno
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Post by furno on Jan 16, 2021 2:18:42 GMT -8
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Post by josephcrawley on Jan 17, 2021 15:10:02 GMT -8
Is the sketchup file earlier in this thread still your current design for this heater core?
Thanks
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