Classification of Biogas Plants

Classifcation o biogas plants Biogas plants are mainly classifed as:  continuous and batch type (as per process)  The dome and drum types Dierent variations in the drum type

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Continuous type biogas plant •

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In this plant the supply o gas is continuous and the digester is ed ith biomass regularly! Continuous digester plant process is o to types (a) single stage process (b) double stage process

stage process  The entire process o conversion o comple" organic compounds into biogas is completed in a single chamber  This chamber is regularly ed ith ra materials hile the spent residue #eeps moving out !  in this e get serious problems ith agricultural residues hen ermentated in a single stage continuously ! •

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Double stage process  In

this stage acidogenic stage and methogenic stage are physically separated into to chambers!  The frst stage o acid production is carried out in a separate chamber and only the diluted acids are ed into the second chamber here bio methanation ta#es place $nd the biogas can be collected rom the second chamber!

Batch type biogas plant •

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Batch type plants are appropriate here daily supplies o ra aste materials are di%cult to be obtained!  The eeding is beteen intervals &the plant is emptied once in the process o digestion is complete! $ batch loaded digester is flled to a capacity sealed and given su%cient retentation time in the digester!

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'as production is uneven because bacterial digestion starts sloly& pea#s and then tappers o ith groing consumption o volatile solids  This di%culty can overcome by using minimum to digesters so that at least one is alays in operation !

ains eatures o batch type plant •

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'as production in batch type is intermittent depending upon the clearing o the digester! It needs several digesters or chambers or continuous gas production &these are ed alternately! Batch plants are good or long fbrous materials!  This plant needs additional ermented slurry to start the digestion process!

Dome and drum type plants •

$s there are many types o biogas plants mainly to types o plants are usually used they are ! (*) +loating gas holder digester (,) f"ed dome digester

+loating gas holder digester

+i"ed dome digester

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 The -oating gas holder hich is used in India is #non as ./IC plant !  The f"ed dome digester is called Chinese plant!  They can be constructed above or underneath the ground &in -oating gas holder the gas holder is separated rom the digester ! In f"ed dome digester & the gas holder and the digester are combined!

Dierent variations in drum type •

 There are to main variations in -oating drum design!! (*) -oating drum ith ater seal! (,) -oating drum ithout ater seal!

+loating drum type biogas plants

+i"ed dome plant

$dvantages o -oating drum plant •

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 it has less scum troubles because solids are constantly submerged  no separate pressure e0uali1ing device needed hen resh aste is added to the tan# In it& the danger o mi"ing o"ygen ith the gas to orm an e"plosive mi"ture is minimi1ed 2o problem o gas lea#age Constant gas

$dvantages o f"ed dome type pla nt •

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It has lo coast compared to -oating drum because it uses cement but not steel In this type heat insulation is better as construction is beneath the ground! 2o maintenance!