Smoke Generators - Venturi Type

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Post by ssorllih » Mon Nov 12, 2012 18:56

Orf, what do you use for fuel wood?
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Post by crustyo44 » Mon Nov 12, 2012 19:52

Hi Orf,
Do you get enough smoke from this venturi set-up? My way of thinking is that if you have the venturi tube and air intake situated more near the bottom, the smoke/air mixture has a lot less resistance.
In your smoker, the air/smoke mixture has to travel all the way up the pipe, through the sawdust/pellets and/or chips to reach the venturi tube into your smoker.
Much more resistance in your set up.
That's my opinion for what's it worth.
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Post by orf » Mon Nov 12, 2012 19:55

I have a wood planer and used cherry wood "shavings" from it. I'm going to try sawdust and chips to see which one works better. If anyone has any advice I'd love to here it.I got the basic idea from the mother site eccept I used 1/2" black pipe, a piece of 4" stove pipe and a wine cork for the plug on the copper. orf...
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Post by orf » Mon Nov 12, 2012 21:41

jan, I thought the same thing.check out the link.orf...

Smoke Generators
Factory Made
Home Made

Venturi Smoke Generators

To smoke meat or sausages one needs to generate smoke. That task became easier to accomplish when venturi smoke generators started to appear around 2005. First in New Zealand, then in the USA, Poland and other countries.

Imagine somebody smoking a cigarette that sits next to the partially open window in a fast travelling car. The fast moving air outside creates a vacuum next to the window and pulls smoke out of the car. The same principle is used in venturi smoke generators where the pressurized air from an aquarium air pump is injected into a container which is filled with wood chips. The lowest layer of wood chips keeps on burning producing smoke. As it burns away it turns into ash that sinks to the bottom of the hopper. Then, the layer above starts to burn. The top layers cannot ignite as they are not exposed to the fresh air which is needed for combustion. The fresh air enters through the holes at the bottom of the smoke generator.


The smoke generated rises slowly, but most of it is sucked away by the air that comes out from the aquarium air pump nozzle. The air nozzle is aimed towards the opening that leads into the smoking chamber and this is the only direction for the air and smoke to travel.


There are units for sale in New Zealand (Venturi 500, 400), Poland (Roger) or in the USA (Smoke Daddy™), and although they may differ slightly in construction details, the engine that powers them is in all cases the same: an aquarium air pump. We have tried different types of venturi smoke generators and they all worked well.


Wood chips.

A big advantage of Venturi smoke generators is that they accept different sizes of wood chips so they are not locked in to any particular brand of a smoker.
.
Low Nozzle Smoke Generator

This is a typical venturi smoke generator. Connecting pipe is placed low and smoke box and smokehouse are at the same level. Such an arrangement works out well with small smokers.

Low nozzle cofiguration smoke generator.

The top of the container (cover) is loosely attached, but should make a reasonably tight connection to prevent the loss of smoke. There is no bottom, the container may be placed directly on the ground. A hole is made for the pipe that connects the smoke box with the smokehouse. The connecting pipe can be considered the smoke delivery channel. This pipe may be inserted loosely, threaded on both ends and secured with nuts, threaded into the smokehouse wall and the wall of the wood burning container, etc. This will depend on your technical abilities and the fanciness of the design.


The disadvantage of this design is that larger wood chips can get lodged in on top of the pipe and prevent more chips from dropping down. This will stop the fire. For that reason the length of the pipe in a smoke box should be kept to the minimum. Secondly, the pipe`s opening must be somehow protected, otherwise wood chips may enter inside and block the intake of smoke. Thirdly, this design does not contribute to the natural draft of the smokehouses because the smokehouse and the firebox are placed at the same level. This means that when the pump is off, the system will have little power to suck the smoke up.

Those minor flaws of the above design can easily be corrected by flipping the smoke box 180° on its horizontal axis and placing it either below the smokehouse or raising the smokehouse higher. Of course the fresh air supply holes must be present in the top and the bottom of the firebox and are simply covered with tape.


The high nozzle configuration induces stronger draft, providing that the smokebox is placed below the smokehouse. Even with a pump off, there should be enough natural draft to allow a thin smoke production. The bigger height between the fresh air inlet and the smoke exhaust, the stronger the draft.

High Nozzle Smoke Generator

High nozzle smoke generator.

Straight Injector High Nozzle Smoke Generator

This is a simple but effective smoke generator. Smoke Daddy™ smoke generators operate on this principle. The air flowing through the nozzle exits about 1/4" before the connecting pipe, which is of a larger diameter. In this little air gap a sufficient vacuum is created to suck in the smoke into the connecting pipe. The heart of the system consists of 3 parts: air pump, air nozzle (metal tube) and connecting pipe. Those parts can be connected together in many different ways. They can be threaded, nut secured or permanently welded.

Straight injector high nozzle smoke generator.

The venturi principle is explained in our section dealing with Gas Burners.



sorry about the long post I just meant to give the link,oopp's.anyway it's on the mother site under the smokehouse section/smoke generators.they have drawings and factorymade and homemade versions.orf...




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Post by ssorllih » Tue Nov 13, 2012 00:24

A slope of 1 inch per foot is enough for a smoke pipe. Comfortable working heights for a cabinet would place the lowest shelf at about 24 inches and the highest hanging level a little over six feet.
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Post by orf » Wed Nov 14, 2012 13:29

jan I got your e-mail but no pic's.orf...
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Post by crustyo44 » Wed Nov 14, 2012 19:59

Image

Hi Orf,
Here is the photo as promised.
Regards,
Jan.
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Post by orf » Wed Nov 14, 2012 20:30

do you have any problems with chips getting in the pipe or is there a screen on it.orf...
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Post by crustyo44 » Wed Nov 14, 2012 21:32

Hi Orf,
My friend who has the same unit uses a mixture of chips, small and large, shavings and also sawdust and a mixture of all of them.
Sofar no trouble with the inlet pipe blocking up.
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Post by orf » Thu Nov 15, 2012 01:31

I had an old fish pump that we had from when the kids were small that I tried to use. It didn't work so good so I went and bought a new pump at the walmart's. It works great I think I could use chips,dust or any combination of them. I have 50# to do this weekend for the holiday I'll let you know how it works out.
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Post by kiwihunter » Fri Nov 23, 2012 07:22

I just use oven cleaner to clean the venturi system just leave for 30 minutes and wash gets rid of most of the residue built up
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Post by jbk101 » Sun Feb 03, 2013 15:27

Hello All,
It's been awhile since I posted anything. Been trying to stay busy and slowly knocking tasks of my Honey Do List while still trying to find a new employment opportunity and the search not going so well :sad:

One of the projects that I have been working on was modifying my Venturi type cold smoker that I made. (Since I completed it I had to make a sausage to test it out :mrgreen: So I made the Pork and Turkey Kielbasa and it turned out real nice :smile: )

Image

The modification were as follows: redesigned the Internal Screen, added a Fire Starter Port, added a second adjustable air pump at the bottom of the unit with 2 air lines, original pump was moved to a new air intake just below the cabinet intake, painted the unit with 4 coats of High Temperature Black Paint and finally made a storage / carry case for the air pumps and any tools I might need.

Image

I used apple wood chips for the initial burn and in less than 5 minutes the smoke was just bellowing out the back of the Cabinet vents.

Image

I decided to open the Cabinet Door and this was the View

Image

Here is the unit mounted to my cabinet - I do need to fix a small leak at the top air line but it did not cause much of a difference in the amount of smoke generated. I just don't like it leaking - LOL.

Image

My initial burn time that I got was about 1-1/2 hours and I think with some pellet type material I could achieve a lot longer burn time, I used some fairly large apple wood chips that I had on hand. I also need to play with the air flow adjustment to fine tune the unit for the amount of smoke and possibly increase the burn time in the process.

Here is a close up shot of the fire starter port that I added
Image

Overall I think my modification were a success but being the perfectionist that I am I will continue to tweak it some more. :grin:
Thanks,
John
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Post by jbk101 » Sun Feb 03, 2013 15:55

I forgot to mention that I used RedZed's :) recipe that he posted here for the Sausage.

My version of Grandpa's Pork and Turkey sausage.

5 lbs of lean turkey leg meat
5 lbs pork butt and loin meat
1 lb back fat

Cure 1 2tsp.
Salt 40g.
yellow mustard seeds 1tbs
coriander 1tsp
Caraway 1.5 tsp
marjoram 1tsp
Garlic 2 cloves homegrown
dextrose 7g.
water 180ml

I deboned the turkey legs and selected the pork, cut into 2 inch chunks
and cured for 3 days. (the plan was for 2 days but something came up)

Ground the lean turkey and lean pork through the 10mm plate. Fat pork and back fat through the 10mm and then through the 4.5mm.

Mixed the rest of the spices with the water, mixed well and stuffed into 32mm hog casings. Dried at room temp with the help of a fan for a couple of hours and then in the preheated smoker for about an hour at 120-140F. Smoked with cherry for 2 hours, bringing up temp slowly until IT of 155.
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Post by el Ducko » Sun Feb 03, 2013 17:26

Looking at the leak, it appears that you're running a positive pressure at the top of the chip bed, which I wouldn't have expected a venturi-type smoke generator to do. That says to me that you are blowing air into the base, below the chip bed and combustion zone, and also blowing air into the top, above the chip bed but not into the outlet tube. Thus, it's not a true venturi up there, although it would come close if you shoved the air tube up close to the exit tube.

But ya know what? Nobody cares. You have a smoke generator that works, and it looks like it works pretty well. That's what counts. The air across the top of the bed propels the smoke into the smoker, and that little bit of back pressure probably keeps the combustion rate lower than it would be if you pulled a vacuum on the top. (That's good.)

I really like this design! ...believe I'll go try to build one myself, if you don't mind. I think you said in an earlier post that it's 4" pipe, right? The screw-on top and bottom ought to make it real easy to clean. I assume you have some sort of mesh just above the lighter hole.

Good job!

And as they say in the business world,
(1) Imitation is the sincerest form of flattery, and
(2) Plagiarism is limited solely by faulty technique.
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Experience - the ability to instantly recognize a mistake when you make it again.
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Post by ssorllih » Sun Feb 03, 2013 17:27

If you can cut some limb wood of such size to fit the burner you could mix those in with the chip and get a higher fuel density.
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