BIO GAS PLANT

BIO GAS

The bio-gas is a renewable energy that can be used for heating, electricity, and many other operations that use a reciprocating internal combustion engine, such as GE Jenbacher or Caterpillar gas engines. To provide these internal combustion engines with bio-gas having ample gas pressure to optimize combustion, within the European Union ATEX centrifugal fan units built in accordance with the European Directive 2014/34/EU(previously 94/9/EG) are obligatory. These centrifugal fan units, for example, Comcimac, Meidinger AG or Witt & Sohn AG are suitable for use in Zone 1 & 2.

Other internal combustion engines such as gas turbines are suitable for the conversion of biogas into both electricity and heat. The diagest is the remaining inorganic matter that was not transformed into biogas. It can be used as an agricultural fertilizer.

Bio-gas is produced either;

• as landfill gas (LFG), which is produced by the breakdown of biodegradable waste inside a landfill due to chemical reactions and microbes, or
• as digested gas, produced inside an anaerobic digester.

Projects such NANOCLEAN are nowadays developing new ways to produce biogas more efficiently, using iron oxide nanoparticles in the processes of organic waste treatment. This process can triple the production of biogas.

Biogas plants
A biogas plant is the name often given to anaerobic digester that treats farm wastes or energy crops. It can be produced using anaerobic digesters (air-tight tanks with different configurations). These plants can be fed with energy crops such as maize silage or biodegradable waste including sewage sludge and food waste. During the process, the micro-organisms transform biomass waste into biogas (mainly methane and carbon dioxide) and digest.

Key processes
There are two key processes: mesophilic and thermophilic digestion which is dependent on temperature. In experimental work, a 1000-litre digester using psychrophiles harvested from "mud from a frozen lake in Alaska" has produced 200–300 litres of methane per day, about 20%–30% of the output from digesters in warmer climates.

Dangers
The air pollution produced by biogas is similar to that of natural gas, but with an additional risk from the toxicity of its hydrogen sulfide fraction and any unburned methane that escapes is a potent and long-lived greenhouse gas.

Bio-gas can be explosive when mixed in the ratio of one part bio-gas to 8-20 parts air. Special safety precautions have to be taken for entering an empty bio-gas digester for maintenance work. It is important that a biogas system never has negative pressure as this could cause an explosion. Negative gas pressure can occur if too much gas is removed or leaked; Because of this biogas should not be used at pressures below one column inch of water, measured by a pressure gauge.

Frequent smell checks must be performed on a biogas system. If biogas is smelled anywhere windows and doors should be opened immediately. If there is a fire the gas should be shut off at the gate valve of the biogas system.