Dear Alex, I would like to share with you our solution for H2S removal. We have a biogas project in Uganda where we convert biogas into electricity with a 12kW gas generator. We remove the H2S with a small aquarium pump by pumping approximately 3% air into the gas mixture. In our case, we use the Schego Triumph Extra electronic 12V 180l/h. The Schego pumps also exist in 150l/h. So you can just calculate the 3% of your gas mixture to know how many hours your pump has to run. You could install a small solar system/ or just use a small 12V battery to run your air pump.
Good luck, Best regards, Sandra Bos www.fact-foundation.com > > ---------------------------------------------------------------------- > > Message: 1 > Date: Wed, 26 Sep 2012 12:34:44 -0700 > From: David <[email protected]> > To: [email protected] > Cc: [email protected], For Discussion of Anaerobic Digestion > <[email protected]> > Subject: Re: [Digestion] Removal of hydrogen sulphide from biogas > Message-ID: <[email protected]> > Content-Type: text/plain; charset="iso-8859-1"; Format="flowed" > > > > Alex, > > On 9/25/2012 1:53 PM, [email protected] wrote: > > David, > > > > Some really interesting points here. For example, any idea how much > > ferric oxide would make sense to add to a digester? How would that > > effect the effluent as a fertilizer? > > Well of course the question before your question has been mentioned > already, which is whether one needs to do anything at all. I don't > think it makes sense to do a preemptive strike on H_2 S, but rather > find out if it will be a problem, then if it is, to deal with it. And > of course whether it may be a problem depends on a number of factors. > And remembering that the original question was about small-scale, farm > or household digestion, of the millions of Chinese- and Indian-style > digesters extant, I don't know of any significant use of scrubbing H_2 > S that is used. Your thought appears to be the same since you say "In > the SNV program they essentially use no filtration, and they really do > not have issues." > > That said, using one of the methods mentioned by Henry of adding a > source of the ferric ion, based on the figures he presents-- and they > were minimal in his paper-- one would need 2 g Fe_2 O_3 /l of slurry. > That can end up being quite a lot of material. > > But it is important to note that Henry does not assert that this is a > well-tested dosage. In fact, according to his paper, he tried this > technique only twice-- not with a range of dosages, in a series of > digesters with varying amounts of sulfides, but only two times, once > each in two test digesters. He says that > > "It can be seen that the amount of sulfide in the sludge in a > digester is not a measure of the hydrogen sulfide in the > digester gases. The sulfide may be tied, as in this case, with > iron [DWH: i.e. often by adding it]. The iron content, of > course, is not an exact figure. Any small bit of rust would > have shown up too." > > > So even the 2g/l figure is "more or less", and really this comes down > to a sort of general guideline: if one has "too much" H2S in the > biogas, then try adding "some" rust (or perhaps a bit of > iron-containing soil, such as hematite) to the slurry. > > > > My sense is that the sulpher and iron would actually work well as > > micro nutrients, as both would be present in high concentrations. We > > could make a powdered mixture with cal (lyme?) To both raise pH and > > add the iron. Both materials are really cheap and effective in small > > volumes. > > S (more likely) and Fe (less likely) might be micro-nutrients, but > that would depend on the soil to which the effluent is being added. > And even cheap materials, given that one would have to mix and add > them, have a marginal cost in labor and complexity, so again either > additive should earn its place following some degree of proof that it > was actually needed, or sufficiently beneficial to warrant inclusion. > > > > Regarding the biological filtration, I think the thesis you posted > > talks about running the gas through a drier mix of cow manure. > > The cow manure filtration actually is mentioned in a different paper, > although at the moment I don't have the time to track it down. The > thesis I mentioned offers a lot of information that might be adapted > to lower-tech biofiltration of H_2 S. > > > > I have seen the industrial systems (RCM International a really > > impressive model), but I have not been able work through the pumping > > of substrate and air at a small scale. > > Any digester evolving biogas will provide enough pressure to cause the > biogas to flow. The problem, as you indicate, would be getting enough > but not too much air into the gas stream just before the point of > exposure to whatever media was supporting the sulfur-loving bacteria. > > > > Aside from engines, the question that SNV made me ask was: why > > filter for small systems? If the combustion is complete the sulphur > > becomes elemental, with a slight odor but not dangerous, or at least > > how I understand it. We have never registered any dangerous sulphur > > compositions in a kitchen. Thoughts? > > Actually when H_2 S is burned, it produces SO_2 , which is quite > irritating (that concentrations of three to five PPM are readily > detectable). Further, in the presence of water (and when the exhaust > gases cool, water will be present), SO_2 combines to produce sulfurous > acid (H_2 SO_3 ), which can corrode appliances, flues, and the like. I > use sulfur to control gophers on my farm, for example, by putting some > elemental sulfur in a run that I've dug up, then burning it into the > burrow with a propane torch. Believe me, it's sufficiently deadly. > > I think, in sum, that the reason so little scrubbing is done is > because few substrates contain sufficient sulfur to be of much > concern, and those which do contain sulfur in some form (pig manure, > for example) are generally digested at a pH sufficient to reduce the > production of H_2 S (and/or there is sufficient ferric ion present-- > widely available in soil and water-- to suppress the production of H_2 > S) that it simply is not a problem in most situations. > > > > d. > -- > David William House > "The Complete Biogas Handbook" |www.completebiogas.com| > /Vahid Biogas/, an alternative energy consultancy |www.vahidbiogas.com > > | > | > "Make no search for water. But find thirst, > And water from the very ground will burst." > (Rumi, a Persian mystic poet, quoted in /Delight of Hearts/, p. 77) > > http://bahai.us/ > | > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://lists.bioenergylists.org/pipermail/digestion_lists.bioenergylists.org/attachments/20120926/1499eeb1/attachment-0001.html> > > ------------------------------ > > Message: 2 > Date: Thu, 27 Sep 2012 06:04:58 +0530 > From: Anand Karve <[email protected]> > To: For Discussion of Anaerobic Digestion > <[email protected]> > Subject: Re: [Digestion] Removal of hydrogen Sulphide from biogas > Message-ID: > <CACPy7ScV4KvtE5qWcm+Zy=-n2fveq35uaq3onehjgdrslxh...@mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Dear Mr. Taiwo, > passing biogas through a cylinder filled with iron filings or steel wool > would remove the hydrogen sulphide. The iron filings would turn black by > being converted into iron sulphide. Such blackened iron filings have to be > periodically changed. > Yours > A.D.Karve > > On Tue, Sep 25, 2012 at 11:26 AM, Isiaka Taiwo > <[email protected]>wrote: > > > Dear sir, > > > > I am an Electrical Engineer from Nigeria. > > > > I am working on biogas application on farm and low / middle class homes. > > > > My objective is to use biogas for cooking, running of small power > > generators and lighting of gas lamps. > > > > I have accomplished the production of biogas from my biogas digester, and > > I have burnt the gas and it gave blue flame. > > > > I have also converted a petrol generator to gas generator with a converter > > I bought in country. > > > > I am delaying the test of the generator with biogas because of the > > corrosive effect of the gas which I learnt can damage the generator. Also , > > I want to protect lives of the stakeholders as the hydrogen sulphide is > > also poisonous. > > > > I am looking for simplest and easiest do it yourself (DIY) way(s) to > > eliminate hydrogen sulphide from biogas and I think you can be of > > assistance. > > > > I don't mind suggestion of suppliers of any ready made solution. > > > > Please , I am waiting for any assistance or useful information that will > > help in realisation of my set objectives. > > > > Thanks for the anticipated assistance and supports. > > > > > > Isiaka Taiwo > > Sent from my BlackBerry wireless device from MTN > > > > _______________________________________________ > > Digestion mailing list > > > > to Send a Message to the list, use the email address > > [email protected] > > > > to UNSUBSCRIBE or Change your List Settings use the web page > > > > http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org > > > > for more information about digestion, see > > Beginner's Guide to Biogas > > http://www.adelaide.edu.au/biogas/ > > and the Biogas Wiki http://biogas.wikispaces.com/ > > > > > > > -- > *** > Dr. A.D. Karve > Trustee & Founder President, Appropriate Rural Technology Institute (ARTI) > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://lists.bioenergylists.org/pipermail/digestion_lists.bioenergylists.org/attachments/20120927/e7034131/attachment-0001.html> > > ------------------------------ > > _______________________________________________ > Digestion mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org > > for more information about digestion, see > Beginner's Guide to Biogas > http://www.adelaide.edu.au/biogas/ > and the Biogas Wiki http://biogas.wikispaces.com/ > > > > End of Digestion Digest, Vol 25, Issue 8 > ****************************************
_______________________________________________ Digestion mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org for more information about digestion, see Beginner's Guide to Biogas http://www.adelaide.edu.au/biogas/ and the Biogas Wiki http://biogas.wikispaces.com/
