[Digestion] flame lifting

Murali Krishna bmkrishna6 at gmail.com
Fri Apr 1 22:14:49 CDT 2011


Dear Deepak,

The tap which you are operating to reduce the gas flow can be considired as
a Gas control valve (may be  you have fixed a  brass gatewall type control
to the gas flow pipe).    Gas control valves are available in the market.
Anyhow, the tap you have on the line would serve the purpose.  As suggested
by Mr.Paul and other friends, reduction of supply pressure should solve the
problem.

Krishna.

On Fri, Apr 1, 2011 at 11:27 PM, Deepak D. G. <ghindwani at gmail.com> wrote:

> Dear David,
>
> Thanks for the advice. The issue is very difficult to get proper parts and
> consistent sizing in bali. Every time I buy gas jet the size always changes.
>
> I actually get my burners made locally since it is not available locally.
> I will try to reduce the gas flow by closing the gas tap bit and will
> update you the result.
>
> What do you mean by pressure control valve?? Please elaborate that
>
> Regards,
> Deepak
>
>
> David Fulford wrote:
>
>> Dear Deepak and listers,
>>
>> The issue of burner design and pressure control is one which needs some
>> careful planning. Biogas has a very low flame velocity, so if the flame
>> lifts from the burner, it means the flow rate of the biogas/air mixture is
>> too high, so the velocity from the flame port is faster than the flame can
>> burn.
>>
>> If you are using burners from a reliable source, then the gas pressure is
>> too high. If you are using a floating drum, the weight of the drum is too
>> much. However, studies by SNV of burners made in different projects suggests
>> that the quality of burners from different places in Asia is not consistent.
>> (I say this as someone who helped design the one now used by BSP Nepal,
>> which was criticised by the SNV study). The biogas wiki <
>> http://biogas.wikispaces.com/Biogas+burners> has a section on biogas
>> burners, with a link to that SNV report. Our Nepal design used too few flame
>> ports. A larger flame port area would have reduced the gas mixture velocity
>> through the holes. You may need to look for a better burner.
>>
>>
>> The simplest way to reduce gas pressure is to use a gas valve to control
>> the flow. Partly closing the valve will increase the pressure losses,
>> reducing the flow rate and the flow velocity. A longer lasting solution is
>> to use a pressure control valve.
>>
>> Regards,
>>
>> David F
>>
>>
>
>
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