Importance of Biomass Pyrolysis
Pyrolysis is the process of thermal degradation of a substance in the absence of oxygen or an oxidizing agent. The process can also be conducted in the presence of a negligible amount of oxygen. The idea behind conducting the process in an oxygen free reactor is to minimize the gasification reaction occurring in it. The reaction is carried out at a relatively low temperature of 500 to 800 degree Celsius. The main byproducts of the reaction are pyrolysis oil, charcoal and gas in different proportions. This process is usually carried out for recycling tyre and plastic. The proportions of the byproducts depend on the parameters of the reaction and the biomass characteristics. Pyrolysis is gaining importance nowadays as a means to utilize the energy present in the biomass. There are many techniques to obtain this energy, ranging from the traditional methods of burning to gasification and pyrolysis. However while considering the factor of profit in investment, it would be ideal to choose the method that yields the maximum benefit with limited efforts. The process of pyrolysis does not have any harmful emissions or byproducts. Biomass pyrolysis is a profitable method to extract the energy within biomass while successfully eliminating the solid wastes that would otherwise be difficult to dispose. The solid wastes included in the biomass are very costly to decompose by other methods. By employing pyrolysis, these wastes can be converted into liquid products in a very environment friendly method. These liquefied products have a variety of uses. They can be used in storage combustion, retrofitting, transport and flexibility in marketing as well as with production. There are a variety of pyrolysis processes conducted for biomass. Some of them are fast pyrolysis, flash pyrolysis and conventional pyrolysis. The usual biomass pyrolysis involves a number of activities such as planting the biomass, pretreatment, product utilization, pyrolysis product, upgrading and having them evaluated on the basis of economy and cost. Earlier, pyrolysis was done for the production of charcoal. This was carried out as slow reactions at low temperatures to maximize the yield of the reaction. Nowadays they are of great help in recycling nondegradable rubber and plastic wastes. The products of the pyrolysis process are determined to a great extent by the temperature and pressure inside the reactors. On increasing the temperature of the reaction, the proportion of the gaseous products increase. The industries concentrate more on liquid byproducts of pyrolysis. This is because the liquid products are potent oil substitutes that would be useful in the case of oil shortage. Another factor that adds to their importance is that the liquid products are high in energy density. The liquid byproducts are similar to the biomass in elemental composition though they possess a slightly higher heating value. They are basically composed of oxygenated hydrocarbons in a complex mixture. The complexity of the product is due to the lignin degradation and the spectrum of phenol based compounds contained in it. The solid byproduct is often char. These are used for limited metallurgical applications in developed countries. The gaseous byproduct from pyrolysis is used mainly as fuel gas. The fuel gas that is produced during recycling or biomass pyrolysis of plastic can be used for power generation as well. It would be an ideal twofold beneficial technique for power generation, in that without harming the environment, wastes are also disposed of in an eco-friendly manner. Pyrolysis holds promise for future technology and the creation of new energy sources. Though this technology has not been researched in detail, it offers the scope for being one of the top processes for generating energy in an eco-friendly way.