Types of Gasifier/reactors

Types of Gasifier/reactors

• 1.
  PRP Different Types of GASIFIERS/REACTORS
• 2.
   A REACTOR/ equipment in side which the gasification process takes place is known as Gasifier.  Gasifiers are used to convert the solid fuel materials into producer gas. WHAT IS A GASIFIER
• 3.
  Gasifiers are categorizedas follows:  Basing on direction of flow (DRAFT) of gas [where we get output]  Up draft (Counter current)  Down draft (concurrent)  Cross draft Based on type of bed  1. Fixed bed- updraft , downdraft and cross draft  2. Fluidized bed Types of Gasifier
• 4.
  Updraft Gasifier (Counter- current)  In the updraft gasifier, the feed (biomass) is introduced from the top and moves downwards while gasifying agents (air, steam, etc.) are introduced at the bottom of the grate.  The product gas moves upwards.  In this case, the combustion takes place at the bottom of the bed which is the hottest part of the gasifier and product gas exits from the top at lower temperature.(around 150 °C).  Because of the lower exit temperature, the product gas contains large amounts of tar.  The tar and volatiles produced during this process will be carried in the gas stream.  Ashes are removed from the bottom of the gasifier .
• 5.
   In thistype of gasifier the fuel is introduced at the top of the gasifier and air is introduced at or above the oxidation zone of the gasifier.  The producer gas is removed at the bottom of the apparatus , so that the fuel and gas move in the same direction.  Both the feed and product gas moves downward and the product exits from the bottom at a higher temperature, i.e., around 800 °C.  In this case, most of tars are consumed because the gas flows through a high temperature region.  Most suitable for engine applications. Downdraft Gasifier (Con-current)
• 6.
   Short designheight  Very fast response time to load  flexible gas production  Cross-draft gasifiers are most appropriate for thermal applications and one can design for higher moisture loadings in biomass. DISADVANTAGES  Minimum char converting capacity  High exist gas temperature  High gas velocity Cross-draft Gasifier
• 7.
   The feedis introduced at the bottom, which is fluidized using air, nitrogen and/or steam and the product gas then moves upward.  There are more particulates in the product gas from this gasifier .  Fluidization of the bed enhances the heat transfer to the biomass particle leading to increases in reaction rates and conversion efficiencies.  Fluidized beds also are able to tolerate a wide variation in fuel types and their characteristics. Fluidized Bed Gasifier