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

Mon Jan 4 22:08:02 CST 2016

 Tom and listers,	
	GC's are limited in their ability to detect broad ranging components. A GC set up for fixed gases usually can't detect compounds like ethanol, methanol, acetic acid which are all present in gasifier produced gases unless specifically removed and acetic or other organic acids will contribute to engine oil acidification and corrosion over time. 
	There are system that can provide instantaneous broad ranged gas analysis going from hydrogen to whatever you want in MW. 
	The other question is to gas heating value for combustible components to adjust the engine air/fuel ratio as it may change, such as change in moisture content in feedstock, ambient humidity, composition of feedstock or to increase the range of acceptable feedstock for improved economic performance. There is such a device which is surprisingly inexpensive and effective with any combustible component being analyzed instantaneously, which a GC cannot do.  

Sincerely,
Leland T. "Tom" Taylor
Thermogenics Inc. 

-----Original Message-----
From: Peter Davies <idgasifier at gmail.com>
To: gasification <gasification at lists.bioenergylists.org>
Sent: Mon, Jan 4, 2016 7:30 pm
Subject: Re: [Gasification] Characterization of waste water from biomass gasification equipment: A case-study from Cambodia

                     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
         www.trmiles.com

         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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