[Gasification] Characterization of waste water from biomass gasification equipment: A case-study from Cambodia

Tue Jan 5 17:44:18 CST 2016

On 05/01/2016 1:28 PM, Peter Davies wrote:
> Dear Tom,
>
> The end of 2015 has been very busy for us, and 
> the start of 2016 looks even busier. Essentially 
> we have successfully proven our gasifier systems 
> with high ash, pelleted ag-residues in a high 
> temperature, low tar gasifier scenario with 
> simple dry scrubbing. Even when slightly over 
> aspirated with some residual oxygen coming 
> through the tars were limited to low viscosity 
> condensates (and very little of these), though 
> the gas quality varied slightly with the 
> appearance of some C2-C8 hydrocarbons (nothing 
> higher though, within detectable limits of the 
> GC system used by the lab). We also now have one 
> of the leading European CHP providers sign off 
> on our gas quality for use in their IC engine 
> systems, so expect to be able to supply complete 
> turnkey plants shortly which have a global 
> support network.
>
> Yes it does require a pelleting step at this 
> stage, but we are working with a couple of 
> pellet equipment manufacturers for a lower cost, 
> gasifier optimised pellet which will be 
> substantially cheaper and lower maintenance than 
> conventional wood pellet plants used for the 
> combustion industry. Accompanying innovative 
> financing for village scale densification 
> systems is also now well advanced.
>
> So we don't agree that water scrubbing is either 
> necessary or where gasifiers will be in the 
> future. However if you only have old gasifier 
> tech to work with then you can try torrefied 
> sawdust filters to recirculate your scrubber 
> water through, our early testing found these 
> very effective till we fixed the hearth core in 
> the gasifier design so they were not needed.
>
> New Years Cheers,
> Peter
> ID Gasifiers Pty Ltd
> Australia.
>
>
> On 5/01/2016 2:31 AM, Tom Miles wrote:
>>
>> Since 2005 hundreds of small scale gasifiers 
>> have been installed in Myanmar, Cambodia and 
>> other South East Asian countries to offset high 
>> cost diesel to generate shaft and electric 
>> power in rice mills and palm factories. They 
>> are often in the 100+kW scale. Initially they 
>> were dual fueled with diesel but increasingly 
>> they are 100% producer gas. Ankur Scientific  
>> introduced a dry cleaning system in 2009 but in 
>> most cases the gasifiers use water scrubbers 
>> and the waste water and sludge is discharged 
>> into ponds without remediation. Simon Shackley 
>> and others have published a thorough 
>> characterization of waster waters from several 
>> gasifiers.
>>
>> Crop residues are best gasified at low 
>> temperatures. Low temperatures generate tars. 
>> Scrubbers are the lowest cost cleaning 
>> technique. Water strips toxic chemicals from 
>> the gas which become carried into the 
>> environment with water and sludge. Gasifier 
>> char is very useful. Sludge and black water are 
>> dangerous.
>>
>> The remediation of gasifier wastewater is a 
>> challenge for us. As we look forward to 
>> installing small scale gasifiers around the 
>> world we need to solve this problem . What are 
>> your solutions for filtering and remediating 
>> gasifier scrubber water? One solution might be 
>> running continuous blowdown though a vegetated 
>> biological filter where the biochar is used as 
>> part of the media. What have you tried?
>>
>> Tom
>>
>> T R Miles Technical Consultants Inc
>>
>> Portland, OR 97225
>>
>> tmiles at trmiles.com <mailto:tmiles at trmiles.com>
>>
>> www.trmiles.com <http://www.trmiles.com>
>>

Tom,  what about VCD using waste heat from the 
gasifier ? Possible ?   David Murphy
>>
>> Characterisation of waste water from biomass 
>> gasification equipment: A case-study from Cambodia
>>
>> Article in World Review of Science Technology 
>> and Sustainable Development 
>> 12(2):126-151 · December 2015
>>
>> DOI: 10.1504/WRSTSD.2015.073829
>>
>> Abstract
>>
>> The gasification of rice husks for small-scale 
>> power generation in rice mills and other small 
>> factories in Cambodia has spread rapidly in the 
>> past decade and has a favourable investment 
>> payback period where the facility is off-grid. 
>> The technology is widely regarded as a 
>> sustainable, low-carbon power option. However, 
>> installed gasification technologies produce a 
>> black waste water which is frequently disposed 
>> of into the local environment without any 
>> treatment. An analysis was undertaken to 
>> identify and measure the key potential 
>> contaminants and compare concentrations in the 
>> water and sediment with regulatory thresholds 
>> established in Cambodia and within other 
>> jurisdictions. It was found that concentrations 
>> of organic contaminants such as phenols and 
>> benzene-type molecules (BETX) (water and 
>> sediment) and polycyclic aromatic hydrocarbons 
>> (PAHs) (sediment), as well as macro water 
>> quality indicators, were far higher than 
>> regulatory thresholds prescribe, posing threats 
>> to sensitive aquatic ecosystems into which such 
>> waste is introduced.
>>
>>
>>
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>
> -- 
> Peter Davies
> Managing Director
> ID Gasifiers Pty Ltd
> Delegate River, Victoria
> Australia
> Ph: 0402 845 295
>
>
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