BIO GAS

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BIO GAS : 

BIO GAS A gas produced by the biological breakdown of organic matter in the absence of oxygen with the help of bacteria.

Chemical composition of biogas : 

Chemical composition of biogas Component Methane Carbon dioxide gas Hydrogen Nitrogen Carbon monoxide Oxygen Hydrogen sulphide Percentage 40-70 30-60 1.0 .5 .1 .1 .1

Materials for bio gas production : 

Materials for bio gas production Animal wastes Agricultural wastes Industrial wasts Night soil

Production of biogas : 

Production of biogas Biogas is generated , when organic matter undergoes fermentation through anaerobic digestion. This process can be divided into two phase. Acid forming(liquification). Converts fats, carbo-hydrates ,protiens into volatile acid and also produces carbon dioxide. pH range 5.1-6.8 Bacteria- Saprophytic bacteria

2. Methanogenesis(gasification) : 

2. Methanogenesis(gasification) Convert acid into methane and carbon dioxide which are the main constituents of biogas. Bacteria-Methanogens becteria pH range 7.2-7.4 If there is fall on temprature more than 10 °C from the optimum value , the bacteria stop working and methane gas production stops.

Different way to produce methane : 

Different way to produce methane Methanogens use a number of different ways to produce methane Using ethanoate (acetate) that may be derived from the decomposition of cellulose: CH3COO+ + H-  CH4 + CO2 +36 kJ mol-1 Or using hydrogen and carbon dioxide produced by the decomposers: 4 H2 + CO2  CH4 + 2 H2O +130.4 kJ mol-1

Conditions for biogas production : 

Conditions for biogas production Temprrature range Anaerobic system pH Time frame 30-35 Methanogenic bacteria 6.7-7.5 30 days until production

Factors affecting generation of biogas : 

Factors affecting generation of biogas Temperature of substrate(35-38°C) Loading rate Solid concentration(7-9%) pH value Retention period Nutrients concentration(C, S, H₂, O₂,P, N₂) Toxic substance

Types of biogas plant : 

Types of biogas plant 1.Batch type biogas plant Use where daily supplies of raw waste materials are difficult to be obtained. Gas production in batch type is uneven. It have several digesters in series. Several digesters occupy more space. Require large volume of digester, therefor Initial cost become high

2.Continuous type biogas plant : 

2.Continuous type biogas plant The supply of gas is continuous and digester is fed with biomass regularly. Type 1.Single stage These plants are generally preferred for small and medium biogas plant. 2.Double stage These plant are preferred for large biogas plant.

3.Movable drum type or floating dome type : 

3.Movable drum type or floating dome type

4.Fixed dome type : 

4.Fixed dome type

Biogas plant developed in india : 

Biogas plant developed in india 1.Deenbandhu biogas plant(Action for food Production 1984)

2.Gayatri model : 

2.Gayatri model This model is developed by the Government Implements Factory , Bhubaneshwar.

3.Manipal model : 

3.Manipal model Developed by Manipal Institute of Technology,Manipal. This has features of both indian and chines models. It has rectangular digestor and RCC roof

4.Spherical biogas plant : 

4.Spherical biogas plant This is a fixed dome type biogas plant. Developed by The Energy Resource Institute,New Delhi.

Selection of site for biogas plant : 

Selection of site for biogas plant The distance b\w plant and site should be minimum. The plant should be constructed in open space. Plant should be constructed away from the walls. Sufficient quantity of water must be available. Sufficient space must be available for operation and maintenance.

Use of biogas : 

Use of biogas Cooking . Lighting. Heating. Internal combustion engine.

Biogas is difficult to store , compress or liquify : 

Biogas is difficult to store , compress or liquify A temperature of -162°C is needed to liquify methane at atmospheric pressure. The critical pressure of methane is 4710 kPa at -82°C .( critical temp of a gas is that temp above which it is not possible to liguifyit by any pressure.Critical pressure is the pressure needed to liquify gas at critical temp.