India Solar, Wind, Biomass, Biofuels – EAI

Pyrolysis

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Pyrolysis as a method for power production is not well established currently in India or elsewhere in the world.

The two main methods of pyrolysis are “fast” pyrolysis and “slow” pyrolysis. Fast pyrolysis yields 60% bio-oil, 20% biochar, and 20% syngas, and can be done in seconds, whereas slow pyrolysis can be optimized to produce substantially more char (~50%) along with organic gases, but takes on the order of hours to complete. In either case, the gas or oil can be used as a fuel for firing the boiler for steam production and subsequent power production.

Typically pyrolysis plants work well beyond 2 MW scale, while gasification plants work well until 2 MW scale, at the current technological progress. Thus, it can be said that pyrolysis takes off where gasification ends.

Slow Pyrolysis

In the case of slow pyrolysis when you get an organic gas and charcoal. The gas can be cooled and fed to a gas engine for power production. Cooling this gas however results in a significant amount of hydrocarbons being removed. Thus most of the energy is wasted away. A more efficient idea that is being explored is to use this heterogeneous gas straight for combustion of boilers and running a steam cycle. Charcoal is a valuable product, which fetches anywhere between Rs 10-Rs 25 per Kg. It has a much better calorific value than coal and people in many places use charcoal because coal might not be available in those places.

Fast Pyrolysis

Fast pyrolysis is a process in which organic materials are rapidly heated to 450 - 600°C in absence of air. Under these conditions, organic vapours, permanent gases and charcoal are produced. The vapours are condensed to pyrolysis oil. Typically, 50 - 75 wt % of the feedstock is converted into pyrolysis oil. The pyrolysis oil can be used as a replacement for furnace oil.

 

Biomass-based Power Production Methods

 

 

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