[Stoves] Rice husk stove and rice husk gasifier

[Ken Boak]

Chris,

I have been looking at fuel densification by way of charcoalised briquettes.

Several organisations are creating charcoal briquettes using rice husk.

Googling "rice husk charcoal " will find numerous links and videos - so
plenty of material already out there.

Charcoalisation stabilises the fuel stock, makes it less likely to absorb
moisture and gives a much higher energy density, consistent and almost
smokeless fuel product.

Charcoal sells for about $500 to $600 a tonne - so a useful revenue stream.

However - you do need to utilise the pyrolysis gases in an efficient manner
if the charcoaling process is to be viable and locally environmentally
acceptable.

With standardised fuel, it makes the whole mechanical handling and shipping
tasks a lot easier and makes a very valuable by product from the waste.

With charcoal you then have the opportunity to run IC engines by way of a
charcoal gasifier - which produces a relatively tar free gas - and less
likely of engine damage.

Rice husks contain a lot of silicates - and these will create ash and
vitrefy in the hot zones of a gasifier - so care has to be taken over this
too.


Ken


London




On 14 October 2016 at 13:05, Christopher Bradnum <
Christopher.Bradnum at nottingham.ac.uk> wrote:

> Dear List Member
>
> I am looking for some help on a project one of my students is starting.
>
> I have a Taiwanese student who would like to develop a passive (not
> electric fan) rice husk stove for her home as her major project for the
> BEng in Mechanical Engineering at the University of Nottingham. Depending
> on the success of the project, her family may consider starting a business
> manufacturing such stoves within their community. Her family own a rice
> farm and they have a lot of material that they can convert into energy.
> They already have a stove (sorry I don't have the photographs of this)
> which they use for some of their cooking needs. It has a deep central 'pot
> like' component (+/- 750mm tall X 300mm diameter) with a grid at its base
> which holds the burning rice husk. This 'pot' is located inside a larger
> vessel. At the base a fan directs air in below the central rice burning
> 'pot'. A separate pot holder unit is placed on top of the whole
> configuration. This has, what looks like, an inverted colander at its
> centre through which the flame reaches the cooking pot. The stove complete
> is around 1,000mm tall. The rice husk is top lit inside the central pot and
> I assume the air pushed in from underneath helps to fuel the fire. The
> stove produces a reddish / purple flame and I am told a pot filled with
> fuel lasts for 5 hours. Although I can't quite work out what needs to be
> cooked for that long.
> The student returns home in December and will complete some rudimentary
> tests to get a baseline for the efficiency and emissions given off by the
> stove. I will also get her to complete the heterogeneous cooking test
> developed by SeTAR under Prof Harold Annegarn and Crispin
> Pemberton-Piggots' supervision at the University of Johannesburg.
> Leading up to that testing I want her to get on with a bit of research, so
> I thought to turn to this very excellent group and ask for some help
> (standing on the shoulders of giants...).
> Has anyone on the list worked with rice husk as a fuel source and does
> anyone have any research work we can look at as a starting point?
> Particularly using rice husks as a fuel for cooking.
>
> It seems to me, through superficial online perusing, that a rice husk
> gasifier might be a better utilisation of the raw material. If it is a good
> system to convert rice husk into energy I would like to make and test one
> of these too. Does anyone have research around rice husk gasifiers that I
> could start investigating? Is this a good or not so good use of the fuel?
>
> Kind regards
>
> Chris
>
>
>
>
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