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BEK Operation Manual

Page history last edited by Bestow 7 years, 8 months ago

 Return to BEK Main Page 

Operation Manual for the BEK 


Table of Contents

I) Introduction

II) Pre-Run Prep Instructions

A. Useful Tools

B. Fill the Hopper

C. Connect the Ejector Venturi

III) Description of Modes

A. Bypass Mode

B. Retort Mode

C. Sweep Gas Mode

IV) BEK Run Instructions

V) Shut Down 


I) Introduction

The Biochar Experimenters Kit (BEK) allows the control over the residence time and temperature over various reactor modes. 

II) Pre-Run Instructions

After you have followed the assembly instructions, you will always want to double check to make sure you have tightened all the bolts, all seals are airtight and in tact, and the igniters are working properly.

Saftey Note: Check the seals each time before running the BEK, because pyrolysis occurs in an oxygen free environment, no air should be able to leak into the system. The system is designed to only allow air into the combustor for a controlled flare of the combustible gases.

  

A. Tools Needed

  • propane torch
  • gloves (incase you want to service the reactor while it is running, leather gloves are prefered)
  • 1/2'' wrench and adjustable wrench
  • container for bio-oil

B. Fill the Hopper

  • Fill the hopper with raw biomass
  • Turn on the biomass auger to fill up the reactor. 

C. Connect the compressed air to the ejector venturi.

 

  • A compressor capable of 4-8 CFM at 120 psi is optimal for the ejector.

 

D. Connect the Propane to the Burner

  • A 5 gallon tank of propane will allow for several runs. Connect this using a regulator capable of between 5-10 psi.
  • Be sure to test your threaded connections for leaks using a bubble solution between the gas tank and the needle valve. The needle valve provided is a standard valve that tightens when turned to the right.  

 

E. Biochar Reservoir 

  • Optional:  Because hot charcoal will ignite when it comes into contact with air, you may want to replace the air in the biochar reservoir with an inert gas, smoke, or steam. If air is in the biochar reservoir, the first amount of hot charcoal introduced to the reservoir will smolder until the air is consumed. 
  • Saftey Note: Make sure the seal on the biochar reactor is in tact. Allowing air to contact the hot charcoal could ignite the char bed. At this point you may be only left over with ash in the char reservoir.

  

 

 


 

 

 

III) Description of Modes

 

A. Bypass Mode

 

For Bypass Mode, the top valve should be open to the chimney (closing off the Retort), and the Sweep gas valve should be closed. This mode will allow the hot gases from the burner to exit through the chimney without transferring heat to the biochar reactor.

 

 

 

   

 

 

 

B. Retort Mode

 

Retort Mode allows the hot gases from the burner to pass through the interstitial wall of the retort to heat up the biomass inside the biochar reactor with out introducing these gases into the reactor core. The pathway of the hot gases then exit through the top chimney port and escape through the chimney

 

 

 

   

 

  

 

C. Sweep Gas Mode

 

To allow the hot combustion products of the burner (carbon dioxide and water) to pass through the inside of the BEK reactor, open the Sweep Gas pathway using the bottom valve handle. The flow of gases through this pathway will exit through the top of the reactor and pass through the ejector to the burner.  Try varying the opening of the Sweep Gas valve, the manometer should respond in relation to the amount of flow allowed through this pathway. Be aware that allowing the pyrolysis gases through to the burner will change the combustion characteristics of the combustible gas mixture. You may need to vary the 1.5'' air pre mix ball valve to adjust the air to fuel mixture of the burner. Because of this system characteristic, always have a propane lighter on hand, incase you have to re-light the flare. 

 

 

 

               

 

 

 


 

IV) BEK Run Instructions

Saftey Note: When changing between the modes, keep the igniter torch ready to re-light the flare. Always switch between modes slowly to make for a smooth transition for changes in the gas stream to the burner could put out the flare. Keep the flare lit at all times, if the flare will not stay lit, keep the hand held torch on it until it lights.  Pyrolysis gas combustion characteristics and moisture content vary widely over various feedstocks and run conditions.  The igniters help greatly with this. Be sure to wear safty googles and gloves during the operation of the BEK.

 

Be sure to air out the BEK before starting it up a second time. As pyrolysis gases can tend to be left over from the last run you will want to make sure that the system does not have any flammable gases in it already before the second start up. Easily do this by opening up the valves and turning on the ejector venturi for about 30 seconds. 

 
 

1. Ignitors  

  • Plug in the ignitors for automatic ignition of the flare to ensure a clean burn of the pyrloysis gases.
  • Double check that they are working. They will glow orange when turned on.  

 

  

 

 

   

 

 

 

2. Light the Burner   

  • Orient the valves into Bypass Mode.  
  • Open the red gate valve that is inline to the condensing circuit (or the short circuit depending on the set up you have chosen)
  • Turn the ejector on by opening up the compressed air valve slightly. Place the propane torch into the lighting port, while turning on the propane slowly. Slowly adjust the 1.5'' air premix ball valve and the ejector to allow air into the burner.
  • The flare will catch in the burner when the correct air to fuel ratio is allowed by the propane valve, compressed air valve, and the 1.5'' air premix valve. 
  • Leave the flare on for a 3-5 minutes in By-Pass Mode to allow the burner to get hot. 

       

 
     
 
    

3. Heat Char with Retort Mode   

  • To heat up the biochar reactor indirectly, slowly open the Retort pathway.
  • As the char bed starts to create pyrolysis gas, it will pass through the circuit and enter the burner. Make sure the valve is open between the ejector and the reactor to allow for this. 
  • Monitor the temperature. Around 100C, water will boil off introducing water into the flare. If the flare seems shaky, increase the air and propane just slightly.
  • As the reactor reaches pyrolysis temperatures, you will notice the flare in the burner will start to gradually change.  This is due to the combustion properties of the pyrolysis gas which will change across various feedstocks and reacton conditions. You may need to adjust the propane for the flare. Sometimes the pyrolysis gas will keep the flare lit on its own and no propane may be needed. This usually happens at higher reactor temperatures above 400C. 

 

4. Heat Char with Sweep Gas Mode

  • The sweep gas mode will circulate the hot flue gases from the burner into the char bed. This mode will heat up the char quicker than the retort mode because the hot flue gases are in physical contact with the char bed. 
  • Make sure the valve right before the cyclone is open. This valve is located on the condensing (or short) circuit. 
  • You will want to slowly open the sweep gas valve keeping your hand held igniter on the burner. As the valve is opened, the flue gas displaces the pyrolysis gases and it opens the pathway for the pyrolysis gas to pass through the condensing (or by-pass) circuit. The gases are then introduced to the flare. Because the pyrolysis gases have completely different combustion characteristics, you may find that the flare might flicker. If the sweep gas valve is open too fast, this could put the flare out. Have the hand held torch ready to re-light the flare. 
  • Most likely you will need more oxygen to combust the pyrolysis gas, open the air valve to allow more air into the burner.  
  • Monitor the temperatures.
  • To turn the sweep gas mode off, you will want to slowly close the valve while monitoring the flare, you may find that you need to close the air valve a little to return to a stable flame.

 

5. Create Bio-Oil

  • If you have the BEK set up to create bio-oil, you will want to drain out the bio-oil at the end of the run. While you can open the valve during the run to allow bio oil to flow out, air will be sucked into this valve (because the system is under a vacuum) and can change the air/fuel mixture in the burner. Make sure you do this slowly so as not to disturb the flare. 

  • Make sure that you do drain the bio oil out of the cyclone at the end of the run before the system cools off. If the system is allowed to cool, the bio oil can be come viscous and clog the cyclone. If this does happen you can fire it with a torch and the oil will again begin to drain. 

 

6. Shutdown

  • To shutdown the BEK, you will want to return to the bypass mode. Make sure you have closed (slowly) the bio oil valve, the sweep gas valve, and the retort valve. 

  • Turn off the feedstock auger motor and leave the biochar auger on until all of the char is moved out of the reactor.

  • Slowly turn the propane down, but keep the mixture of air proportional so as to sustain the flare in the burner.

  • If there is no pyrolysis gases you may shut off the propane and air entirely. However, if there is pyrolysis gas and smoke, start the flare again to burn these off while the system cools down. 

  • After shutting all of the valves, and the biochar has been removed from the reactor you can open the char bucket and spray the char with water. Hot char will start to burn if it is in contact with air. You can also let the char cool over night before collection. 

 

 

 

 

 

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