Ideas requd - heating the area below a water coil?

[julianf]

I realise ive been foolish -

For ages ive been thinking about putting a coil in my processor, to heat from water, without realising that the top of it would be large enough to 'wind in' a standard coil!

However....

My processor tank looks like this (jules' photo, but mine is the same) -



ahh, ive just found another snap online of mine -



These are not the coils ill be using, but some like these -



The ones in the photo are ear-marked for my thermal store - for the bio tank, ill just use smooth ones out of standard hot water tanks.



Anyhow, the problem -

I can 'wind in' one of these coils through the top port on the reactor, having pre-drilled the ports on the side of the reactor to line up with the coil.

...but, because its a conical tank, there will be 50 ltrs or so below the level of the coil.



How do you think i should deal with this?

Possible options that spring to mind -

• Periodically pump with processor pump whilst heating (but my pump really doesnt like cold oil)
• Use air pump to gently mix, like nigeb's bubble washing tank
• Use another pump to mix
• Wrap the lower port of the reactor with 10mm pipe, externally

At the moment, im keen on the air pump idea, but id welcome any other suggestions?

[nigelb]

What I'd do Julian is use your processor pump. If you allow the oil to heat up close to reaction temperature and then turn on your pump there should only be a brief run of "cold" oil before it all starts to blend together. I think you may be looking at a problem that doesn't exist. Obviously circulating the oil from cold could put some strain on your pump......but heating and then pumping shouldn't pose to many issues.

Using an airpump could cause you more problems depending on humidity. See soap-rich-bio-poor about his issues...although I think he was using a compressor.

Option three is probably an unnecessary expence...unless you're looking to upgrade anyway.

Option 4 sounds messy and could introduce a fair amount of ineficiency

Nige

[Julian]

See soap-rich-bio-poor about his issues...although I think he was using a compressor.

Nige

OK, completely unjustified now.  I've managed to get 80 ltrs of, what I hope is, bio from the last soap batch it's just under going the acid wash as I type.

Other than that I agree with Nige.  If I heat my processor without running the pump, then start it when the tank's up to temperature, it only takes a couple of seconds before the pipe work starts to warm up.

I don't know what you use your Mono pump for but I have mine plumbed in parallel with the processor pump, but valved so it can pump independently of the processor via a couple of hoses so it can be used to do pretty much any pumping duty around the shed.

With a similar arrangement, the problem wouldn't exist.

[greasemonkey]

I don't think you will have a problem. If the top three quarters of the tank is hot, then the bit below the heater coils will follow. Imagine it this way, if you actually wanted to keep the bottom of the tank cold, and heat the top, how would you do it? It would be nigh on impossible.

[julianf]

I should also mention that i get in a fair bit of tallow (melts at over 50c, and will shatter when cold - ie not even gloopy!) and id like to reduce the stress of processing this too.

Its obviously got to be hot to even get it into the processor, but i dread to think what would currently happen if i got a long power cut before it was methylated!

I have also just thought -

I have to machine the plate for the lower port anyhow.  Im thinking that, if i can squeeze another couple of holes into it, i can have a loop of 10mm copper actually running up from the lowest point in addition to the larger coil higher up.

I think that would do it - use the large coil for the bulk of the heating, and use the smaller, internal, 10mm 'loop' just to stop things going solid at the lowest point.


Im also planning on having valves so as i can either drain down all the pipework (& hopefully the pump) or fill them with oil at points where im waiting for the water or glyc to settle out.

Processing beef tallow is a right pain, but its one of my free collections, so im happy to put in a bit of effort once in a while.

[Tony]

Sounds like you need an extra little pump that can take hot liquid from the top and push it into the very bottom?

[Head Womble]

Sounds like you need an extra little pump that can take hot liquid from the top and push it into the very bottom?

Or just some extra pipework and valves so the same pump can be used by reversing the flow.

Can you not solder a small bore coil to outside of the base, keeping it tightly coiled and well insulated,
with a bit of work you should be able to run it along the pipework/pump like trace heating.

[julesandtash]

I have proper trace heating cable for mine now thanks to William Crosby. All of my pipework, valves and processor bottom is getting wrapped with it.
It's only 10watts per metre so not going to warm up anything from cold but under the insulation it is enough to keep temperatures up whilst settling.

I was thinking about the same thing as Julian although, rather than cut holes in the side, I was going to have the pipes to the coil dropping vertically down the middle of the processor from the big screw on cover on the top. I plan to make my own coil from 10mm microbore so will make the last few turns at the bottom progressively smaller diameter so it fits all the way to the bottom of the processor.

Julian, would you be able to machine a plate for me to fit into the 4" RJT nut on the bottom of the tank (ie the outlet from the cone where the original 4" to 2" reducer and  tap fits). I want to take that valve off and get my pipework closer in to the tank.
Ideally I would like a plate that fits into the RJT nut with a hole cut in that is the same diameter as the outside of a 2" BSP socket so I can weld one in.

[julianf]

Julian, would you be able to machine a plate for me to fit into the 4" RJT nut on the bottom of the tank (ie the outlet from the cone where the original 4" to 2" reducer and  tap fits). I want to take that valve off and get my pipework closer in to the tank.
Ideally I would like a plate that fits into the RJT nut with a hole cut in that is the same diameter as the outside of a 2" BSP socket so I can weld one in.

Non ferrous i can do any time.  If you want steel (like on my reactor, or that tank you saw in essex) then you would need to wait till i next go back that way, as thats where my lathe still resides : (

[julesandtash]

Definitely steel please - waiting is no problem.

[julianf]

Jules,

You will, i assume, want the center hole offset?  If its all centered up, there would be a lip on the inside, meaning that the reactor could never be fully drained.

[K.H]

Totally off topic i know but while i remember do you do Military vehicle shows/get togethers with that truck of yours?

[julianf]

Who, me?

Nope - the truck is currently on a SORN, in storage, miles away from where we are living.

At christmass, i did a couple of laps of a field with it (i was amazed it started fine, but the batteries are all on float from the solar etc, so there's no real reason why it shouldnt)

Im not actually a member of the owners club at the moment either, and got the hump a bit, as the 101 forum, which ive been chatting on for about 10 yrs plus suddenly became 'members only' due to some obsessive beaurocrats.

Wouldnt have bothered me as much, had i not have been in the middle of doing some engraving for the club (which i wasnt a member of!) spares department at the time...


</rant>


Anyhow, why do you ask?

Id like to get the truck back on the road again sometime.  There's little chance of us being able to afford 'proper' holidays for some time to come, so having a camper may afford us some respite.  But then there's a load of things i want / need to do to it that will also take time / money...

[K.H]

Who else?
Its just that a guy named John Coghlan organises military get togethers (they pull up in a line for the weekend, kick tyres, get pissed and have a BBQ), they have one every year and they have asked to use my old mans field this time

[julianf]

I dont recognise the name, but then i probably wouldnt anyhow.

I also fear that, if i ever go to somtime like that, people are going to get upset with me, as my truck is all chopped about.  There's certainly some about who scorn 'destroying' these historic vehicals, and would rather they stayed in original condition, if only to be bought out 2x a year (if that)

I can see the value in preserving history and all that, but, at the same time, i can also see the value in keeping somthing on the road and not just part of an exhibit somwhere.

Ive owned the truck for over 1/3 of my life, and ive encountered more mixed opinion over it than anything else ive ever done / owned!