Building the GEK Gasifier in Seven Parts

This project is part of a series of instructables from ALL Power Labs showing how to create a Honda Accord that runs on wood gas.

This project is entered in the Craftsman contest, if you like this project I hope you will consider voting for it. Just click the "Honda Accord" link above to go to the main project, then click the "Vote Now" button. Thanks!! (note from after--- we won! thank you to all who voted for us. the shop is now much more full of tools thanks to sears)

This portion of the project shows fabrication instructions for the Open Source Gasifier Experimenter's Kit (GEK) from ALL Power Labs.

Note: The following fabrication instructions assume you already have cut out or otherwise acquired the necessary sheetmetal vessel tubes, flanges, plumbing parts and other accessories. If you have yet to do this, return to the main project Instructable and finish your prep work before continuing from here.

The GEK gasifier system consists of the following seven components. We will be building each of these components separately, the returning to the main project Instructable for final assembly and preparation to run.

Gas making:
1. Gas cowling and ash grate
2. Downdraft reactor
3. Fuel hopper

Particulate clean-up:
4. Cyclone
5. Packed bed filter

Gas combustion:
6. Centrifugal vac/blower
7. Swirl burner

CAD drawings for all the sheet metal parts and assembled vessels for how to build a GEK wood gasifer are in the main project Instructable, as well as on the download page of the main GEK site http://www.gekgasifier.com

Step 1: Fabrication Methods and Standards

Fabrication Method and Standards

All GEK vessels are fabricated using the same three basic part types: vessel tubes, flange rings, and end plates. Flange rings and end plates are welded on the ends of the cylindrical vessel tubes. Flange rings are usually at the top of a vessel tube, and fit around the outside of the tube. End Plates are usually at the bottom of a vessel tube, and fit inside the tube.

In all vessels, the circular plates/rings function as the jigs to pull the vessel tubes to perfectly round for welding. Tabs and slots on all vessels simularly index the pieces together and ensure an accurate finished product. This system of self-jigging is central to the ease of building the GEK.

While following the step-by-step instructions that follow, be sure to remember these other common standards across the kit.

- All flange rings and end plates should be oriented such that the slag side is down. (note: Oct GEK run needs the reactor bottom plate flipped so slag side up. we made a mistake on this one)

- All vessel tubes are rolled such that the slag side is facing inward

- All vessel tube seams should be in the rear center of the vessel

- All large vessel tubes will have approximately 3/8" overlap at the seam joint. This makes welding much easier than welding sheet edge to edge. The smaller vessels (cyclone and swirl burner) will have 1/4" overlap at the seam

- Tabs and slots will give you the correct positioning. But do be careful to center the first tab and slot so the others will come out correct. See notes in below text for details.

- When welding flange rings and end plates, start with short stitches around the circle. Do not do one long continuous weld or you will warp the flange.

Once you've built all the components listed below, you can proceed on to Assembly Instructions for how to put them all together into a functioning unit.

Step 2: Gas Cowling - Parts

Parts needed:

- Gas cowling vessel tube
- Bottom end plate
- Top flange ring
- Gas outlet square tube to cyclone inlet
- 1/2" close nipple
- Grate rotation bushing for bottom
- Cover plate for ash clean out port
- 5/16 x 5/8 bolts (4 count)
- 5/16 wing nuts (4 count)
- 1/2 pipe lenghts for leg attach points
- legs (4 count)

Step 3: Gas Cowling - 1

Weld (4) 5/16" bolts into ash port holes in bottom end plate.

Bolts should extend downwards towards slag side
Completely weld bolt head to bottom so that it is gas tight
Temp install ash port plate with wingnuts. You will need to add gasket material later. Clean up holes in ash port with 11/32" drill if necessary

Step 4: Gas Cowling - 2

Tack bottom end plate into vessel tube

Part Orientation: Slag side of end plate is down. Ash clean out port is to the left when looking from the front. Vessel tube seam is in back. 1/2" hole is in front.
Tab and Slot start position: The "center" of the slot at the vessel seam is 3/16" from the material edge. This results in a 1/4" space between the edge of the tab and slot on the material side of the slot.
Clamp bottom end plate into vessel cylinder or press together in sections and tack. Progress around the bottom seam in one direction, making sure the vessel tube is tight onto the end plate.

Step 5: Gas Cowling - 3

Tack top flange ring onto vessel tube.

No special orientation. Use any tab and slot position. Slag side should be down. Flange ring should be flush with top of vessel tube.
Clamp top flange ring into top of vessel tube and tack into place. ONLY tack/weld on the bottom side of the flange. If you have enough clamps, do the entire ring. If you do not have enough clamps, work in one direction, making sure the vessel is tight out to the flange.

Step 6: Gas Cowling - 4

Tack side seam

Tack down side seam of vessel. You may need to squeeze the vessel to get the seam parallel, making sure overlap stays consistent. You can use a tiedown strap, rope, or just push it down onto the table to get the seam together and parallel.

Step 7: Gas Cowling - 5

Assemble gas outlet and tack onto vessel tube

Weld flange into end of 2" square tube. Flange is symmetrical so no special orientation. But make sure the tube is flush with the flange plate
Weld half of a 1/2" coupling over the hole in the side of the square tube. This is to create a measurement bung. Make sure the weld is fully sealed.
Tack square tube assembly onto gas cowling. Make sure the flange is well aligned with the gas cowling. Misalignment will cause the cyclone to be cocked when fully assembled.
Clean up flange holes with a 11/32" drill

Step 8: Gas Cowling - 6

Fully weld all tacked joints

Stitch weld in short sections to prevent warpage. But make sure to fully seal all joints
Weld ONLY on the underside of the flange ring. No welding on the top joint side of the flange
Be careful to not warp the top flange when welding the gas outlet into place
Grind top surface of flange flat after welding
Clean up flange holes with a 11/32" drill

Step 9: Gas Cowling - 7

Weld on center rotation tube on outside bottom and add 1/2" close nipple

Put 1.5" x 6" pipe nipple in rotation bushing to help center the bushing in bottom of gas cowling. Remember that this is a rotation point, so alignment is important. Make sure rotation bushing stays firm on bottom while tacking and that the pipe nipple is not binding on the side of the hole.
Tack 1/2" close nipple into small hole in side of cowling protruding outward. Make sure it aims out at 90 degrees. Fully weld around it, and screw on a 1/2" cap to protect the threads

Step 10: Gas Cowling - 8

Weld on leg attach stubs

4 legs at 90 degrees separation around vessel. This is 45 degree off the front axis, like the legs of a chair.
Overlap leg stubs 2" up side of gas cowling. 3" of stub extends below cowling.
Use one leg as an extension jig to make sure leg is aligned while welding.
Drill a 11/32" hole in each 1" x 10" tubing leg, about 1" down from one end
Weld a 5/16" nut over each 11/32" hole
Insert legs onto stubs. Use 5/16" bolts to bind them in place.

Step 11: Rotary Ash Grate - Parts

Parts needed:

- Round perforated grate
- Grate stabilizer square tubes: 1/2" x 1/2" x 5" (5 count)
- 1.5" x 6" pipe nipple
- 2" x 2" pipe spacer
- 1.5" coupler
- 1.5" plug
- 1.5" cap
- Grate turning bar

Step 12: Rotary Ash Grate - 1

Make grate center attachment.

Weld 1.5" pipe coupling into center of grate over precut center hole. Careful centering is important so the edge of the grate doesn't scrape against the gas cowling wall while agitating char.
Weld spacer onto coupling. The spacer is a 2" x 2" pipe section. When grate is installed, this spacer rides on the bottom of the gas cowling, which locates the grate to the proper height (1.5") below the reactor.
Weld one end of one 1/2" x 1/2" x 5" square tube piece to the spacer, extending it out parallel to the grate to create an agitation arm. The tube should be about 2 3/4" above the grate along its length.

Step 13: Rotary Ash Grate 2

Weld support bars on bottom of grate

Support bars are the 1/2" x 1/2" x 5" square tubes.
Weld tubes from from center coupler out axially along the grate bottom. Make sure to clamp down the grate while welding to prevent warpage. A few stitch welds are fine. No need for a full length weld.

Step 14: Rotary Ash Grate - 3

Install grate and confirm dimensions

Test 1.5" x 6" nipple to make sure it turns easily in bushing at bottom of gas cowling. Clean and/or sand if needed.
When fit is confirmed, screw 1.5" x 6" nipple into the bottom of the grate. Put 1.5" plug in center of top of grate. Lower grate down into the gas cowling.
Confirm that grate turns inside the gas cowling without binding on the walls
Confirm that top of grate is 17.5" below top of gas cowling flange ring. The reactor inserts 16" down into the gas cowling, leaving 1.5" to the grate.
Weld grate turn handle on 1.5" cap and install on end of grate post undernearth the gas cowling.

Step 15: Downdraft Reactor - Parts

Parts needed:

- Reactor outside vessel tube
- Insulation inside vessel tube
- Bottom end plate
- Middle flange ring
- Top flange ring
- 5/16" x 5/8" bolts (5 count)
- 5/16" nuts and washers (5 count)
- 1/2" 90deg plumbing elbows (5 count)
- 1/2 npt to 15/16 gas flare adapters (5 count)
- Reduction bell mounting ring
- Reduction bell
- 1/2" x 6" pipe nipples (5 count)
- 1" x 6.125" nozzle tubes (5 count)
- 3/8" street elbows
- Clay gasket material
- 1' of extra 1" pipe for nozzle adjustment spacers

Step 16: Downdraft Reactor - 1

Inner Vessel: Weld inner insulation vessel tube onto bottom flange plate.

Orientation: Slag side of flange plate is facing down.
Insert (5) 5/16" bolts into small holes, fastening them to the flange plate with nuts on the other side. This will hold them in place as you weld the bolt heads to the plate. Make welds gas tight.
Pull the two tabs on the vertical seam of the vessel into the center of the widest slot in the flange plate. One slot in the plate is larger- look closely. The two tabs should slightly overlap, probably not more than 1/4".
Fit all tabs on top edge of inner vessel into slots in flange plate.
Alignment: The inside edge of vessel tube needs to be EXACTLY aligned with inside of holes for air intakes. This is what determines plumb for the nozzles.
Weld up bottom flange completely
Weld up side seam.
Finish all welding on this inner insulation tube as you will not be able to get back to it once the outer tube is welded on.

Step 17: Downdraft Reactor - 2

Weld 1/2" 90 deg elbows into bottom flange end plate.

You might need to grind off casting debris on the elbows to get them to fit through the holes in the bottom end plate. If you need to, do NOT grind off the collar as this collar is used for offset spacing during the fabrication below.
Align elbows and weld them into bottom flange end plate

o On Bottom (bottom view): Elbows should radiate outward to the left. The air lines spiral outwards clockwise, passing as close as possible to the next air inlet tube as they radiate outward. Thus the elbow should be aligned so that the air line will pass just to the side of the next elbow. See pictures at http://allpowerlabs.org/gasification/gek/images/v1.0/reactor3-800.jpg for clarification. The collar on the elbow should sit on the bottom end plate. Do NOT grind off the collar, as this spacing is needed so there is room to screw in the SS tubes. Do NOT position the elbow further out or it will obstruct the grate when inserted into the gas cowling
o Inside Reactor. The elbows need to be aligned so the air inlet nipples rise straight upwards and parallel with the insulation vessel tube wall. You can use a right angle to draw straight vertical lines up the inside for alignment. Then use a 12" or so 1/2" pipe nipple with a coupler on the end to sign to this line. Push the elbow and the coupler up against the wall to ensure parallel orientation to the wall. A combination square will assist with vertical alignment. The line and the coupler/elbow collars are your jig alignment tools. Use a clamp to hold the jig in place.
o The elbows need to be welded in gas tight. It is easy to miss spots around the neck of the elbow.

Step 18: Downdraft Reactor - 3

Outer Vessel: Weld mid flange ring (the one with air holes) onto outer reactor vessel tube

Orientation: Use any tab and slot position. Center your starting tab in the middle of the corresponding hole. Make sure tabs are pulled all the way into slots with C clamps. Use C clamps as you weld around circle. We've had the best results with extra deep throat C clamps, see photo.
Weld over the tab and slot joint on the INSIDE of the vessel to ensure gas tightness. You will NOT be able to access this weld point after step 4.
Weld in 1/2" NPT to 15/16" gas adapters for air inlet tubes up through the mid flange plate. The flared end of the adapter should point toward the ground. Make sure the adapters are centered in hole, and aligned accurately with side of vessel tube. Weld all the way around the top of 1/2" NPT adapters, making sure they are air tight.
Clean up flange holes with a 11/32" drill
Weld the remaning appropriate flange ring around the top of the vessel. Use the tabs and open slots for fitting, clamping and welding. No special orientation. Tack around first, pulling the ring tight to the edge of the vessel, then stitch weld all the way around to make it gas tight.

Step 19: Downdraft Reactor - 4

Outer Vessel: Weld top flange ring onto outer reactor vessel tube.

Orientation: Use any tab and slot position, but make sure flange is flush with top of vessel tube
Tab and Slot start position: The "center" of the slot at the vessel seam is 3/16" from the material edge. This results in a 1/4" space between the edge of the tab and slot on the material side of the slot.
Pull vessel tube and flange tight together with C clamps as you tack around the circle
Weld ONLY on the underside. No welding on the joint side of the flange
Grind top surface flat after welding
Clean up flange holes with a 11/32" drill

Step 20: Downdraft Reactor - 5

Join and weld outer reactor vessel assembly to inner insulation vessel assembly

Slip outer reactor vessel assembly inner insulation vessel.
A hole is cut in both vessels near the top edge- this will be the ignition access inlet. Align the two holes by eye as closely as possible, while also fitting the tabs and slots together on the bottom.
Pull outer vessel tube and inner vessel end plate with elbows tight together with C clamps as you tack and weld around the circle.
A 1" coupler then needs to be inserted for the ignition access inlet. Fit it in and most of the way through the outer vessel's access hole and aligning with the inner vessel's hole. It should cant upward at about 35 degrees. Weld all the way around it, allowing enough space to insert the 1" plug later.

Step 21: Downdraft Reactor - 6

Reduction Tube

Weld reduction tube onto reduction plate
Install reduction tube in bottom of reactor.

o Put two lines of clay rope on gasketing surface and make sure the seal is good.
o Tighten nuts with washers onto bolts in bottom to hold in reduction tube

Step 22: Downdraft Reactor - 7

Install Nozzles

Weld 3/8 street elbows onto ends of 1" air nozzle tubes. Make sure the elbows are angled at 90 degree from the nozzle tubes
Screw in 1/2" X 6" pipe nipples into bottom of the reactor. Tighten modestly with pliers
Put clay gasket material around bottom of nipples, and a thin coating around the threads at the top of the nipples
Push the nozzles down over the nipples, into the clay. Take care to not get clay sealant into the nozzle tube passage.
Depending on your nozzle preference, and desired final height, you may want to install some spacers on the 1/2" nipple before pushing on nozzle tubes. In general, you should start with the nozzles at a height above the reduction cone, equal to the diameter of the reduction cone entrance.
The nozzles should point inwards towards the center of the reactor, and be firmly positioned in the clay. They should be difficult to turn.

Step 23: Cyclone - Parts

Parts needed:

- Top Cylindrical vessel
- Bottom Taper
- 5" end plate for top of cyclone
- Square taper tube for tangential entry to cyclone
- Square flange for above tube
- 2" x 4" black pipe nipple
- 1" coupling
- 1" x close nipple
- Glass Mason jar

Step 24: Cylcone - 1

Assemble cyclone body

Clamp top end plate into top of cyclone cylinder. Slag side of plate should be down. Make sure to center tabs in slots around the perimeter.
Tack end plate and cylinder together. Tack down side seam, making sure overlap stays consistent.
Weld 2" x 4" pipe nipple into top of end plate to make cyclone outlet. The threads on the nipple should extend exactly 1" above the top of the end plate, and be exactly perpendicular to the top plate. Reconfirm this alignment from the outside as well as the inside of the cylinder.
Tack together the tapered cylinder. You may find hose clamps, tie downs, or other clamping devices to help hold the taper together and aligned before tacking.
Bring the top cylinder and bottom taper together to assess alignment. The weld is usually easier if the taper lip is slightly larger than the cylinder, allowing the cylinder to slip down inside it about 1/8". It is also fine if they meet edge to edge. The important thing is that the seam is smooth and even. Any method that achieves this is fine.
When happy with the alignment, tack into place, then stitch weld in stages to prevent warpage.

Step 25: Cyclone - 2

Attach inlet to cylcone body

Align tangential inlet tube into topside of cyclone. The lip of the inlet tube should insert just inside forward edge of the square entry hole, and all the rest of the edges should conform with the sides of the cylinder. Bend and coax as needed. The goal is to have a smooth transition surface all around the joint for smooth gas flow. The top of the square inlet tube should also be parallel with the top of cyclone, and without twist, so that it will align properly with the gas cowling.
When happy with the alignment, tack into place, then stitch weld in stages to prevent warpage.
Align and weld square flange onto inlet tube. Use this weld step as an opportunity to make sure the cylcone is aligned parallel with the gas cowling. Alignment is usually helped by bolting the cyclone flange to the gas cowling flange, then holding the cyclone in place while tacking. Once tacked alignment is confirmed, weld into place.

Step 26: Cylcone - 3

Attach condensate trap on bottom of cyclone

Weld half of a 1" coupler into the bottom of the cyclone's taper. Use a 1" nipple screwed into the coupler while welding to make sure the coupler is aligned in the bottom of the taper. It is visible in the tip of the cyclone taper in the left photo below.
Weld a 1" close nipple into the steel ring lid for the Mason jar

Step 27: Packed Bed Filter - Parts

Parts needed:

- Packed Bed Filter vessel tube
- Bottom end plate
- Top flange ring
- 2" coupling, cut in half
- 1/2" coupling, cut in half
- 5/16 x 5/8 bolts (4 count)
- filter support screens (2 count)
- fine steel wool for filter media

Step 28: Packed Bed Filter - 1

Weld Bottom Plate and Top Flange onto Vessel Cylinder

Clamp bottom end plate into packed bed filter cylinder. Slag side of plate should be down. Make sure to center tabs in slots around the perimeter.
Tack end plate and cylinder together only around the bottom seam
Clamp top flange ring into top of filter cylinder. Slag side of flange should be down. Make sure to center tabs in slots around the perimeter.
Tack around bottom of flange ring. Do NOT weld on top of flange
Tack down side seam of vessel. You may need to squeeze the vessel to get the seam parallel, making sure overlap stays consistent.
Grind top surface flat after welding
Clean up flange holes with a 11/32" drill

Step 29: Packed Bed Filter - 2

Weld accessories onto vessel cylinder

Weld half of a 2" coupling over the hole on the outside of the bottom end plate. Thread opening side should point downward, so as to turn onto the cyclone exit. Make sure half coupler is "square" so the filter and cyclone will align straight
Weld the halved 1/2" couplers over the small holes on the side. These are bungs for instrument access.

Step 30: Packed Bed Filter - 3

Assemble filter inside

Weld four of the 5/16" bolts on the bottom of a circle screen so as to hold it off the bottom of the filter. Position bolts about halfway from the center hole to the wall.
Weld one 5/16" bolt in the center of the second screen circle for the top of the filter. The bolt gives a grab point to remove it from the vessel
Pull apart 4 rolls of steel wool into flat strips in preparation for packing the filter
Pack the filter. Put the screen with four stand off bolts into the bottom. Pack the steel wool in folded layers. Make sure to prevent channels along the sides. The goal is a consistent and complete distribution of steel wool fully filling the vessel. Pack up to about 1" from the top, then put second screen on top to hold it in.

Step 31: Vac/blower - Parts

Parts needed:

Fan rotor:
-circular fan plate with 5 blade slots
-5 fan blades
-shaft collar

Housing:
-top fan housing plate
-bottom fan housing plate
-fan housing side strip
-threaded inlet nipple
-5/16" x 5/8" bolts (8count)
-5/16" threaded rod

Step 32: Vac/blower - 1

Weld the fan rotor

Drill out the shaft hole in the center of the plate with a 5/16" bit. Insert a 5/16" bolt through the shaft collar and then through the plate, adding a nut to tighten on the other side of the plate. Be certain to place the collar such that the head of the set screw is oriented midway between the blade slots. This will guarantee access to the screw once the blades are welded on. Weld the shaft collar to the plate, all the way around except where it will interfere with the set screw. Remove the bolt and nut.
Fit a blade into the slot, using the tab on the blade. Fit the blade such that the outer edge is flush with the edge of the plate. Make 3 small welds along the blade tab on the bottom of the plate to secure it. Ensure that the blades stand exactly 90 degrees to the plate. Repeat until done. 3 small welds for each blade on the bottom of the plate is sufficient. Make sure your welds are evenly spaced, this will ensure the fan stays balanced in operation. Grind the weld bumps down evenly.

Step 33: Vac/Blower - 2

Weld together the housing

Insert 4 bolts into holes in the fan housing bottom plate. Start with the orientation shown in the photo. It is very easy to mistake the orientations of these parts and cause yourself aggravation so refer very carefully to the photos. Using nuts to hold the bolts in place, make small welds to the bolt heads to secure them.
Start fitting the fan housing side strip to the bottom plate as shown. Tabs in the strip fit into slots in the plate. Fit the strip tightly to the plate, and tack weld as you go along counterclockwise. It will be helpful as you go to flip the housing over and weld the slot/tab joints on the back.
Insert 4 bolts into the fan housing top plate, and secure with nuts and welds as decribed above. Again, pay very close attention to the orientation in the photo. Flip the plate over and fit to the rest of the housing, inserting the side strip tabs into slots in the top plate. Fit up tightly and tack as you go, then weld the tab/slot joints. Fit the 2" close nipple over the outlet hole and tack in place. Stitch weld the entire housing together to make it airtight. Weld all the way around the nipple.
In the 2 vacant bolt holes insert the included length of 5/16" allthread. Weld it in place with thread protruding up and down from either hole approximate to the protruding lengths of the other bolts previously welded.

Step 34: Swirl Burner - Parts

Parts needed:

-burner tube
-bottom plate
-gas inlet tube

Step 35: Swirl Burner - 2

Weld together burner

Pull tube together, using a ratchet strap if necessary
Fit bottom plate into place, using tabs to fit into slots on edge of tube. Tack weld as you go around the edge of the tube, keeping the parts fit up tightly
Keep side seam tight and 90 degrees to the bottom end, tack down the seam
Flip over and fit gas inlet tube carefully over hole in burner. Tack into place, keeping the inlet level with bottom of burner for a 90 degree orientation
Weld all the way around bottom plate, up the side seam and all the way around gas inlet

Step 36: Fuel Hopper - Parts

Parts needed:

-30 gallon open drum with lid and ring band clamp
-5/16" nuts (10 count)
-5/16" x 5/8" bolts and 5/16" nuts or wingnuts for jigging

Step 37: Fuel Hopper - 1

Weld nuts under lip of barrel

Start with a 5/16" x 5/8" bolt, and screw a nut on all the way up to the bolt head. Reach under the cut out lip of the barreltop and insert the shaft up through the bolt hole. Hold it in place with a wingnut on the top side.
Crawl into the bottom of the barrel deep enough to afford yourself enough reach with the welding gun, and carefully weld the NUTS, but NOT THE BOLTHEADS, to the underside of the barreltop. A quick weld on either side of the nut is plenty, no need for more.
Crawl out and remove the bolts and wingnuts

Step 38: Fuel Hopper - 2

Drill holes in side

The Hopper needs 4 holes in sides where the lid springs will attach. Measure down 8" from the barreltop, and drill a 5/16" hole. Drill 3 more holes at equal distance from one another around the barrel, all 8" down from the top. From above, if you connected the drill holes visually it should form a perfect "+" or "x".

Step 39: Here's What You Should Have

Congratulations, you've finished all the fabrication steps. Now continue to the GEK Final Assembly Instructable to put all the pieces together and light it on fire.

Introduction: Building the GEK Gasifier in Seven Parts