WO2010038221A2

WO2010038221A2 - Biomass or dendro gasifier

Info

Publication number: WO2010038221A2
Application number: PCT/IB2009/054431
Authority: WO
Inventors: Lalith Lalith Mohan Seneviratne
Original assignee: Lalith Mohan Seneviratne Lalit
Priority date: 2008-09-30
Filing date: 2009-10-09
Publication date: 2010-04-08
Also published as: WO2010038221A3; WO2010038221A8

Abstract

This invention relates to the development of a small Biomass or Dendro Gasifier of thermal capacity 15 KW. What differentiates this design from other commercially available small Biomass or Dendro Gasifiers of similar capacity is the fact that it produces wood gas or producer gas of low tar content without the need of water for scrubbing and cleaning the gas. Use of water for scrubbing makes the operation cumbersome and further the contaminated water containing phenols have to be properly disposed of. This design therefore offers a robust and standalone unit capable of easy deployment. Through the innovative design of the Hopper the moisture and the tar formed through pyrolysis are separated and removed before they can seep to the Firebox where the combustion of the wood and the reduction to wood gas or producer gas takes place. The design of the Firebox with custom castable fire concrete material raises the combustion area temperature and accelerates the cracking of the remaining tar, further improving the quality of the wood gas or producer gas.

Description

1. Description

The description here relates to the invention a Biomass or Dendro Gasifier of thermal capacity 15 KW. It was developed over the period from 2006 to 2007. An early prototype was tested in November 2006 and an improved version by using better material was tested in December 2007.

A schematic or a block diagram of the gasifier is given in Fig. 1

Fig. 1

The critical components in the system are the Hooper and the Firebox where the wood gas or producer gas is produced. A schematic description of the process within these two components is depicted in Figs. 2a and 2b.

M(W

Stages of gasification

fig2a

Fig 2b

The Hopper acts as the wood storage silo performing the function of drying and pyrolysing the wood chips. Drying separates the moisture (H₂O) from the wood. Pyrolysis produces charcoal, tar and hydro carbons.

The firebox is where the combustion takes place with the injection of air. This produces Carbon Dioxide (CO₂) and further water vapour (H₂O) through the cracking of some tar. Subsequently, the reduction of the gas takes place through reacting with charcoal and ash to create producer gas consisting primarily of Carbon Monoxide (CO) and Hydrogen (H₂)

The Cyclones clean the producer gas of fine carbon black dust or soot. The Cooler (a Heat Exchanger) cools the producer gas and reduces its moisture content through condensation. The Filters that are composed of natural coconut coir fibre clean the producer gas of remaining particles. The resultant cool, dry and clean producer gas can thus be fed into an internal combustion engine or used as a fuel in burners or furnaces.

Claims

ClaimsThe claims relate to the design aspects of the Hopper and the Firebox that leads to low tar producer gas or wood gas that does not require scrubbing with water for the filtering of tar.

1.1. Hopper Design

The following design features of the Hopper allow moisture and heated liquefied tar created through the drying and pyrolysis of the wood, to be drained out of the hopper and be collected at the container at the side of the hopper bottom. This prevents excess moisture and liquefied tar seeping into the firebox where it can interfere with the efficiency of the reduction process thereby leading to high tar content producer gas. Please refer to Drawing no. 111407/07 enclosed.

1.1.1. Perforated cone at the lower inside of the Hopper that allows condensed moisture and tar to seep to the outside surface of the cone, drip down, and be conducted along the slanted plate fixed to the outside lower part of the cone.

1.1.2. The gully or drain at the bottom end of the hopper that collects the condensed moisture and tar conducted in the manner described in 4.1.1 above and feeds it to the container at the side of the Hopper bottom.

1.2. Firebox Design

The design of the inside of the Firebox as described below with the use of special material leads to the efficient cracking of tar, reducing the tar content in the producer gas in addition to the reduction achieved as described under 4.1 above.

1.2.1. The inside of the firebox is made of custom made castable fire concrete material. This cast-able fire concrete is high temperature resistant (up to 1500 degrees C) and has a 10 year life-time. The cast-able fire concrete gives very good thermal insulation and thereby raises the temperature of the combustion area. The higher temperature makes a good part of the remaining tars to crack, to form combustible gases. Please refer to Drawing nos. 111407/01 , 111407/02 and 111407/03 enclosed.