Dear Prasad The average fuel particle size is important for "good gas." If the gasifier design worked well with wood chips of a given size, then changing to wood pellets of a different size would be expected to result in a change in gasifier performance, similar to changing to wood chips of a similarly different size.
Wood pellets can have a different problem associated with them. In addition to the apparent difference in average particle size between wood chip and pellet fuel, there can be a hidden difference in real average fuel particle size, in that wood chips can fall apart through moisture absorption from gas circulating within the fuel bed. These smaller particles can tend to block off portions of the previously active gasifier bed, leading to channelling and non-uniform flow through the bed. This "non-uniform flow" can be "too much air in one section of the bed" (leading to very high temperatures and clinkering of ash), and other areas of the bed where there is "too little air" ( leading to tarry gas passing through the reaction zone). Best wishes, Kevin Chisholm ----- Original Message ----- From: Thomas Koch To: Discussion of biomass pyrolysis and gasification ; [email protected] Sent: Tuesday, July 24, 2012 3:57 AM Subject: Re: [Gasification] Need help from gasifier experts_Clinker formation Dear Prasad Thank you for a very clear pinpointing of the fundamental problem of “inventory bed” gasification technology. If you have tars you have problems that are almost impossible to handle with in the economy a gasifier can expext to operate with in. If you reduce the temperature you get more tars and a high char loss. If you raise the temperature the tar problem reduces you reduce the char loss and increase the loss as latent heat in the gas - and you get klinker. Staged gasification – Viking – Double feuer – NOTAR – TKE – Wamsler and a number other designs have managed to reduce the tar content in the gas considerably – for some close to zero – but they are all facing high temperature engineering challenges and none have proven real reliably operation for many thousand hours. The challenges of all these constructions are the complex design and therefor the cost – both for building and operation. Best regards Thomas Fra: [email protected] [mailto:[email protected]] På vegne af Prasad Mande Sendt: 24. juli 2012 08:42 Til: Discussion of biomass pyrolysis and gasification; [email protected] Emne: Re: [Gasification] Need help from gasifier experts_Clinker formation Dear gasifier experts, I was working on the biomass pellet trial on one of the wood chip gasifier (Gasifier design is IISc India design- Open top downndraft). I found that gasifier was able to make good quality gas when switched from wood chips to these biomass pellets. However, two major problems I came across are TAR and Clinkers. Clinkers are primarily due to the temperature in the reactor bed which is exceeding probably ash fusion temperatures for the biomass pellets I used. I want to know from you the ways to control this reactor bed temperature inside gasifier, such that I can avoid clinker formation and also reduce the temperature Waiting for the guidance from experts. From: [email protected] [mailto:[email protected]] On Behalf Of A.Saravanakumar Sent: Tuesday, July 24, 2012 11:00 AM To: [email protected]; [email protected] Subject: Re: [Gasification] Flaming pyrolysis modelling for truncated updraft gasifier Dear Booster, Warm Greetings, You are my GAS GURU and inspiration to us. I pray for your early recovery from the fall. I kindly request you to see through the paper and make necessary corrections in this paper in the aspect of Elsevier publications. Please check the manuscript for grammatical errors and instances of badly worded/constructed sentences and refine the language carefully. I kindly request you to correct the paper, which I have sent for your kind perusal. Thanking you Yours faithfully A. Saravanakumar On Sat, 21 Jul 2012 01:51:39 +0530 Tombreed wrote: > Dear Sara The paper was not attached... Tom Reed Thomas B Reed body { background: #FFF; } Follow Rediff Deal ho jaye! to get exciting offers in your city everyday. ------------------------------------------------------------------------------ _______________________________________________ Gasification 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/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/
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