Electric Probat L12

[Justin Johnson]

I am considering purchasing an electric L12 built in the early 70's (i believe) to convert to nat gas. Anyone out there have any experience or knowledge about this machine?

[Christopher Schooley]

Justin, what's happening? It was great meeting you last week. Electric L12? Please, more details? What are the burners/elements? I've never heard of anything like this.

[Justin Johnson]

Great meeting you as well! I will be posting some pictures on Friday or Saturday of the EL12. It's a pretty cool machine! I look forward to your thoughts.

[Edwin Martinez]

Never heard of this either... but found the electric option here for both 5 and 12kg:
http://www.probat.com/en/gourmet-world/ ... sters.html

[Christopher Schooley]

It says on that link that there is gas/electric heating options, but doesn't explain that at all in the product write up. I'm going to ask Launtia about this. Pretty excited about that prospect, I've never considered electric heating for a roaster that size, but think that it could certainly be doable at the Probatino size. I feel like with an electric roaster that there are some interesting options for acquiring the energy needed that could be a decent gas alternative.
Justin, why are you converting it? You guys have a gas roaster already. I'd want to play around with it for a while. I know that a lot of roasters cringe when a machine isn't, or is minimally, gas fired but I am intrigued by the possibilities presented.

[geir oglend]

My past experience with electric coffee roasters are that they are very power hungry even at low volume. So to get 10-12 Kgs. of coffee roasted within 12-15 min will need upwards of 100 amps @ 220 volts or more. Now compare that in BTUs with gas and you might fine it cost prohibitive, IMO.
I also found that electric roasters are slow to react to temp adjustments and airflow can be a challenge at the best of times. Try comparing an electric vs. a gas stove...
geir oglend

[Christopher Schooley]

I find the electric vs. gas stove comparison to be totally inaccurate. Yes, adjustments to the energy input are slow to react and hard to measure accurately, but on an electric stove you are using solely conductive heat transfer (unless you are boiling something) and not using radiant and convective heat transfer in the same way you would in a roaster; which brings up the key element to being able to shape a roast in an electric roaster, you must have efficient airflow. Making airflow adjustments (if it is efficient) will help you shape the curve without ever making any adjustments (or minimal adj.) to the energy input (you must find a "sweet spot" with your energy setting where you can have enough energy to promote the roast but not too much as to cause scorching, tipping or, or facing (which usually have more to do with over stuffing the drum). You can also achieve a desired curve by changing the charge weight and charge temp, and then never make an adjustment at all to air or energy (I know this isn't as much fun for expert knob twiddlers). Admittedly, I have only roasted on sample sized electric roasters, but this is a similar methodology to how I roasted on IR 12 and IR 24 roasters or on other roaster models where I faced similar problems with slow reacting energy input adjustments (this is my personal experience with IR roasters, I know that there are different opinions/experiences), or roasters where you weren't able to adjust energy or airflow levels at all. I guess what I'm saying is that it's always important to remember that there are a number of variables that can be adjusted when roasting, not just energy input levels.

As far as being power hungry , I can totally see that, but that is why I would be interested in looking at alternative ways of generating electricity (at least part of it) with solar, wind, or even hydroelectric (I saw a pretty cool small scale hydro plant in Panama this summer). But you're right, Geir, that does pose a problem that would need solving... or maybe isn't solvable? I'm curious.

[geir oglend]

Yeah, that was a poor comparison Chris. However the energy comparison to natural gas vs. electric is the issue that first comes to mind.
On the lighter side of things, electrical inspectors might be less hassle, no open flame, no volatile gases/fumes absorbed by the coffee??
But what about all that electrical radiation standing close to the roaster for hours??
geir

[Christopher Schooley]

I would imagine that proper shielding would be in place in a piece of equipment like this. I would think that the EMF levels would be more dangerous in a cafe filled with laptops! wink. A lot of coffee roasters are already using high levels of electricity to power motors and what not, I don't think that it would be like sleeping in a power station. I doubt that this would be an issue, I could always be wrong. Maybe it would give you super powers!

[Justin Johnson]

The reason for conversion is directly related to the cost of electricity vs. natural gas. I was told by the owner of the EL12 that Probat actually offers a kit but I'm sure that the cost of it is sky high and I was thinking I would just do it myself. After seeing the machine yesterday I think that it's totally possible.
I am not looking to place the machine at WAC, rather at another roastery that is planning to open here in PDX. (yes, another!). They are currently renting time on a GG25 and converting this EL12 to gas would give them a similar roaster and cut down on their learning curve.
As far as using alternative energy sources go I think that the cost, installation and actual output of electricity will not balance out. I have been thinking about this as well and would love to play around with different technologies but alas, this roaster is destined for someone elses use
Here is a link to some pictures of this machine http://www.flickr.com/photos/53828629@N03/
I'm also wondering if anyone might know the worth of this machine, when I asked the current owner they had no idea.
Thanks for the responses!
Justin

[Andy Schecter]

My past experience with electric coffee roasters are that they are very power hungry even at low volume. So to get 10-12 Kgs. of coffee roasted within 12-15 min will need upwards of 100 amps @ 220 volts or more. Now compare that in BTUs with gas and you might fine it cost prohibitive, IMO

I think you are correct that electric roasting gets cost prohibitive once one gets beyond roasting very small quantities. Using your example, 100 amps at 220 volts is equivalent to about 75,000 btu/hr, which is not a very large burner. At the rates that are typical for commercial/industrial utilities in my area, it might cost about $2.30 US for an hour's worth of electric, but only $.75 for the equivalent amount of gas.

A more subtle point might be that roasting with electric is not exactly the same as roasting with gas. For instance, burning natural gas produces plenty of water vapor, so the environment inside a gas roaster is more humid than the environment in an electric roaster. To be honest, I'm not sure how significant this is, though.

You may remember that Todd Carmichael made a big stink (heh) about how gas roasting bathes the coffee in hydrogen sulphide (an inpurity produced when natural gas is burned). I think he is really off base on this one, however, since hydrogen sulphide is produced by coffee during the roasting process anyway (heat any sulphur-containing substance -- like coffee -- to a relatively high temperature and you will produce hydrogen sulphide).

As far as being power hungry , I can totally see that, but that is why I would be interested in looking at alternative ways of generating electricity (at least part of it) with solar, wind, or even hydroelectric (I saw a pretty cool small scale hydro plant in Panama this summer).

Energy consumption is an important issue that will probably become more and more important for coffee roasters. I'm skeptical that solar or wind will be much help, though. The amount of energy required would necessitate huge, very expensive solar arrays or windmills. Plus, it sucks only being able to roast on windy days or when the sun is shining.

Hydro sounds cool for those willing to locate their roastery near, say, Niagara Falls. Seriously, roasting takes a lot of energy. A cute little waterwheel isn't going to get the job done.

[Marty G Curtis]

I will answer the question weather or not you can convert the answer is yes and it will cost a fair amount to do it right. You have to understand anyone can but a gas burner in the roaster and roast coffee. But will it work and roast as good as a gas fired roaster that was design form the factory, well that the gamble you take when you do it your self. The reason it cost is you are paying for an expert the do it once and it work correctly right off the bat. Were as you do it your self you may or may not get it right the first time and may never get it right. I have been to plants that have been running equipment for 5 to 10 years and be set up incorrectly. Has it work yes and they have been profitably, but with changing a few things it even roast better and more easily repeatable. this is the difference setting it up correctly. By paying for a retro kit or a company that do this for a living you have a better chance of getting great results the first time out. Now the hard part is finding a company that can do it right the first time. So in the long run it may pay to just buy the kit and you have 100 years of research behind you to help. Or find someone that understands roasting and machinery design to make the change. I personally feel you will be very happy with the convert equipment. Also I believe if you get a company that know what they are doing when you get the roaster back, when we come up with a cheap electric source you may be able to change back.
By the way this is the third one I seen in thirty years, if I reminder correctly, Good Coffee in Seattle still has a LE-5 Probat roaster .

[Christopher Schooley]

Ah man, don't be so defeatist, Andy. You said it yourself:

Energy consumption is an important issue that will probably become more and more important for coffee roasters

I know very well that roasting takes a lot of energy, but I think that it's probably a good time to start coming up with some new ideas. Energy harvesting and storage is an area that we should be looking into, at least as a supplement and off-set. The Hydro plant that I saw in Panama was built to power a whole small scale resort with something like 20 cabins and a restaurant. It was pretty compact, but it was far from a cute little water wheel.

Looking at alternative generation would be pretty expensive and difficult, especially for a larger scale roaster, but if you are working on a 5-15 kilo machine I think that it could be achievable. Plus there are other off-sets that you could build into your facilities and/or operations which could go towards making up (maybe not entirely) the $1.55/hr (from your figures) difference in using electric instead of gas. I imagine that you would have to do a few things in concert with each other to make this viable, but again it could be achievable. We are going to have to eventually figure something out, right?

[Justin Johnson]

Marty,
Great advice, seriously. I think that the party that will eventually receive the roaster would rather it be done with a conversion kit as well. It seems as though having the right foundation will ultimately allow for additions and smaller modifications to this roaster.
Justin