Making BioChar at Burt's Greenhouses

Alex English burtsgh.com Northeast Biochar Symposium 2009

`

Why?Partly because of anecdotal experiences like;

Biochar Demonstration Plot: Peashttp://www.burtsgh.com/index.php/download_file/-/450/

The Presentation Path● Over view of our heating system ● Chain Grate Stoker● Two stage combustion● Technologies and modifications● How that helps us make char● New experiments ● Summary

~1.5 acre inside and 1 acre outside to keep warm

So we are heating with wood

Fuel specs...................................and reality

● Max particle size● Amount of fines● Moisture content

Augers and ConveyorsDeliver Fuel to the Stoker/Boiler

The chain grate stoker

● Boiler on top

● Stoker below

The chain grate stoker

Combustion airunder and over

First StageGasificationThe grate can be stationary except ash will eventually plug up the grate. With wet fuel you need to keep burning the hot char under the pile to dry the fuel. With dry fuel you can speed up chain grate and the zones stretch out in sequence horizontally.

Very Roughly SpeakingWith dry fuel and fast moving grate

First stage (gasification) is based on control of air under the fuel and the grate speed (Lambda <1)Second Stage (combustion) refers to the complete

oxidation of the gases from the first stage gasification.

Two stage combustionThomas Nussbaumer Lucerne University

http://www.nyserda.org/Programs/Environment/EMEP/conference_2007/Nussbaumer_Thomas.pdf

Two stage combustionThomas Nussbaumer Lucerne University

Two stage combustionThomas Nussbaumer Lucerne University

Measuring Results

A stack gas analyzer to measure CO and O2 is an essential development tool.

Stack Oxygen Sensor Panel Responsive control of over-fuel air supply

for optimum second stage combustion,independent of first stage conditions.

Hackers Guide toLow cost Oxygen Sensor

for Combustion Control

Innovate Motorsports LM1 ($300) or LM2 $490 Bosch LSU-4 wide band Oxygen sensor included ($80 replacement)http://www.airfuelmeter.com/english/lsu4_en_sensor.htm

● 'Hack' into Red and Yellow leads on sensor● Connect to Omega Signal Conditioner ($150)

(OM7-30-03) Output: 0-5 Volt● Connect to PLC Analogue Input● PLC Output to Control Air Supply

Stoker Modifications Equipment

● In feed airlock● Under fuel air valves● Secondary or over

fuel combustion air● Stack O2 sensor● Air cooled Ash and

Char auger ● Air locked Char/Ash

bin

Programing● Smooth modulation

logic for PLC● O2 sensor control of

secondary air through PLC

Data Logging 7.5 Hours one February Night

Two Stage Combustionwith Char

Two Stage Combustionwith Char

● Requires dry fuel (<20% moisture)● Needs much less under fuel air● High grate speed ● Oxygen sensor still provides correct amount of

over fuel air for 'complete' combustion of gases● Reduces maximum heat output ● Is easier at a fixed rate with hot water heat

storage or a second modulation boiler

Hot Water Heat StorageA costly solution?

Advantages● 24 hour maximum● Low demand seasons● Steady state

combustion/pyrolysis● Crop Insurance

During Breakdowns● Replaces expansion

tanks

Disadvantages● Capital Cost● Water treatment ● Heat Loss

Experimental Options for Stoker Flaring of Batch Pyrolyser Gases

Added gases contribute fuel to the second stage flame

Testing the ConceptThe gases from a 400 gal top lit, updraft (T-LUD)

batch pyrolyser are piped to the stoker.

Air locked (liquid trough seal) Char/Ash Bin(with anonymous peer reviewer)

BioChar to Go

A Summary of our Path toMaking Biochar

● Focus on Two Stage Combustion● Control the Air.... Everywhere● Test Combustion with Stack Gas Analyzer● Automate using a Wide band Oxygen sensor

Thank you Alex English english@kingston.net