Resurrection of a CFEI 100 KVA Induction Furnace

[awemawson]

Good to know that you are following along, frankly this is drawing on all my resources of enthusiasm and perseverance 

A fair amount of Googling and Youtube watching tells me that this style of pump does indeed use reed valves, and pistons driven on an eccentric so I'm pretty sure that direction of rotation of the motor IS irrelevant.

It also told me that there is a 'telltale'  to show the oil level which I eventually got to after much huffing and puffing (round the back down low very dark!). Now I can see 'something' in the tell tale window but am I seeing current oil level or an artefact from the level  as was some time ago - what makes me suspicious is that it doesn't seem to be horizontal 

Laying concrete today so not more will be done I expect.

[Sea.dog]

It's identical in construction to the Ingersoll-Rand that I'm rebuilding, in that case. I suppose it's a pretty common design. I've never played with a compressor before so it was all new to me when I took the crankcase cover off.

[russ57]

Absolutely following.

I've learned that 100kw induction furnaces are far more complex than I had ever envisaged...

You can't possibly give up until you have the next project on the go.



-Russ

[awemawson]

Years back when I had my Moog Hydropoint and needed large volumes of compressed air I had a Prestcold 3 cylinder inline cold room compressor - the  integral 3 phase motor was too large for my converter to drive until I removed the cylinder head and took out the flat leaf valves for one cylinder - then it was fine ! That though was shaped more like a car engine with a crank shaft with three throws.

[Pete.]

Good to know that you are following along, frankly this is drawing on all my resources of enthusiasm and perseverance 

A fair amount of Googling and Youtube watching tells me that this style of pump does indeed use reed valves, and pistons driven on an eccentric so I'm pretty sure that direction of rotation of the motor IS irrelevant.

It also told me that there is a 'telltale'  to show the oil level which I eventually got to after much huffing and puffing (round the back down low very dark!). Now I can see 'something' in the tell tale window but am I seeing current oil level or an artefact from the level  as was some time ago - what makes me suspicious is that it doesn't seem to be horizontal 

Laying concrete today so not more will be done I expect.

I must say it looks like a tide mark to me Andrew.

[awemawson]

I fear that you are right Pete, but those that I've seen on Youtube being butchered open have oil in that is basically clear with a light grey tinge to it so I can't be certain.

[John Rudd]

If the price of a drop in replacement is prohibitive, could you graft in a stand alone chiller unit?

[mc]

I must say it looks like a tide mark to me Andrew.

I'd agree.
I'd say the light silver mark around the lower edge of the glass is the machined lip the glass sits against, and you'd normally expect to see oil between the glass and metal.

[awemawson]

If the price of a drop in replacement is prohibitive, could you graft in a stand alone chiller unit?

John, the Flowcool IC120 chiller in which this compressor is housed IS a separate stand alone unit from the actual Furnace Driver itself - it's a darn great big box!

It draws 11 kW according to the specification, and provides 39 kW of cooling to the water so is quite a beast.Chillers like this are used in several industries - (injection moulding is one) and I suspect that sourcing a complete working second hand chiller of similar specification would be a better option than replacing the compressor if there is doubt about the integrity of the immersed plumbing.

The late and much lamented Mark McGrath spotted this one for me in an auction in South Wales back in 2006 - an auction that I won of course as I now have the beast. So if any of you know where I can lay my hands on another powerful chiller of similar specification don't be shy, shout out !

[awemawson]

So logically if I am to take this project any further I need to gain some confidence in the big blue box -the actual Furnace Driver that takes 415 volt at an unhealthy number of amps, and oscillates away driving coils round the crucible at several thousand amps 

To get it to 'ping' and establish the resonant frequency, which can be done without too much power I need to locate the four 'driver hoses' that connect the blue box to the crucible unit. They are not just hoses, they have very heavy bare fine strand copper wire threaded up them, and the chilled water is pumped down the hose to stop them melting. At least if I can get the 'ping' working it'll show if the electronics is at least still alive.

Now all the furnace ancillaries were carefully set on a pallet and plastic wrapped about 13 years ago and the pallet placed between my CH oil tank and my Red Diesel Bowser, and I've been dreading pulling bits off it 

Sure enough massive deterioration - pallet totally rotted away, plastic wrap eaten by vermin and quite a bit of rust in places - but today I pulled it all out and placed it on my loading dock for examination.

Some things are definitely beyond hope -

a/ A big low speed chest drill I used for mixing sand - too rusty to both with

b/ The water pipes from the Chiller to the Furnace driver - at least one eaten by vermin

c/ A asbestos cement mounting panel that adapted the driver hoses through 90 degrees - totally crumbled away

None of these are show stoppers - I have a second four way 90 degree hose panel that seems to be OK, the drill is no big issue and the water hose is just standard large bore reinforced hose and can be replaced

[awemawson]

However I find that I have:

A/ Two sets of four hoses - a long set and a short set. At a first glance they look as though they may have survived

B/ A spare coil unit for the crucible unit - looks OK now I've removed the mouse nest !

C/ The big Grundfos pump that I used to circulate water round a 'Cold Bank' (a standard copper hot cylinder) - this may be OK - I had been careful to fill it with water to keep the seal moist and cover it with the small plastic header tank to keep the rain off the motor)

D/ Two tubs of high temperature cement - may or may not be OK

E/  Miscellaneous water fittings

F/  Furnace driver four way pipe  90 degree adaptor

The ends of the chilled water hoses can be re-used so they are not a total write off.

So next I need to do a proper assessment of the driver hoses for  electrical conductivity and water tightness.

[awemawson]

Inspecting the short driver hoses they are quite badly crazed but although I'll not use them ultimately with water under pressure, they will be OK for the 'pinging test' I think

The long set of hoses actually seem to have fared better - I've not completely unwound them but the bit's I've bent so far don't show the same crazing. This long set of hoses I made myself from brand new welding cable and 150 PSI 'Brewers Hose' so is probably a bit newer.

I'd forgotten that I also had a rigid set of extensions I'd made - heavy wall 3/4" copper pipe double insulated by two layers of flexible conduit which was a right pain all those years ago getting it on!

[awemawson]

I had words with a local refrigeration company today -  (I've used them before re-gassing an air drier compressor  so had one of the directors mobile number on my list ! )

Basically his conclusion is much the same as mine - the compressor is toast, the rest of the plumbing is questionable, and even given an (expensive) replacement compressor it will use gas that is no longer allowed 

. . .so it looks like a replacement total water chiller is the only logical way to go if the ping test works.

Meanwhile I re-palatalised all the ancillaries making sure the pipes needed for the ping test are on top and tucked them away in the tractor shed. Now if I'd had the tractor shed before they wouldn't have deteriorated - but I didn't 

[mattinker]

Sorry to hear that mate.

Cheers, Matthew

[chipenter]

Will it work with total loss cooling using water form your stream , I know it's 70 yards away but 150 yards of hose have to be less than a new chiller ? 

[awemawson]

Total loss probably would be OK, (especially as after that burst water main a few years back I have a private fire hydrant !) but my concern as I mentioned earlier is furring up of the internals.

One solution would be a heat exchanger immersed in a tank of water such as an IBC, where the tank is constantly being refreshed on a total loss system so the the water circulating in the furnace itself is always the same water

[russ57]

Seems like that could be enough for a proof of concept to prove that the rest of the system is functional.

Even direct flow for an hour or two would be ok?

-Russ

[WeldingRod]

When I played with a big induction heater, having low conductivity liquid is the heater internals was important.  Gallons of DI water...  there were hose spirals that isolated the hot, high voltage bits from the grounded pump and cooler.  My levitation coils were on a separate cooling loop, and much less critical.

Sent from my SM-G892A using Tapatalk

[awemawson]

Yes this one has an odd four terminal feed arrangement to balance the coils to ground. I remember that when I installed new crucibles in each of the furnace bodies I had to make internal water connections to flexible tubing, but I couldn't use normal jubilee clips as the strong AC field induced currents in them that heated them up enough to melt the pipe ! I had to source special plastic clips to avoid the issue.

Today's objective was to clear enough 'stuff' from the foundry to allow me to choose one of the two furnace bodies, and get it close enough to the furnace driver for the hose / cable assemblies to reach.

Much 'stuff' was re-distributed causing havoc elsewhere but I did actually manage to achieve the objective AND leave enough space arround it and the driver unit to investigate further.

My two 'bodies' are:

 a/ A tilting one that pours into a ladle or direct to a mould

 b/ An inverting one where the mould clamps on top, and when the charge is molten can be inverted into the mould

I chose the inverting one simply as it was sitting on a base with castors and could be moved for inspection more easily - the other one is parked in the stable and no doubt will raise a few comments.

On a roll I decided to investigate the inverting body a bit. It has a clamping pneumatic cylinder that retains the mould on top, and another one that presses on a rack and rotates the entire body upside down - this later motion needs a bit of clearance around it and would easily remove  stray fingers.

Amazingly the pneumatics still seem to basically work albeit with a bit of hissing and wheezing!

 

[Sea.dog]

My word, that is a tidy shed 

[awemawson]

As you know Graham, it was packed to the rafters, and totally impossible to work in.

. . . Something had to be done !

[awemawson]

Today's objectives :  Wire up the 415 volt three phase input and  connect the furnace body ready for pinging

All very well, but the postman delivered the replacement bearings for my buffing spindle, the motor of which is in pieces on the workshop floor - so re-assemble with new bearings - it's only a 5 minute job.

Blooming thing took literally the whole morning. First assembly, greased the bearings, pressed them home, replaced the motor end bells, spindle locked solid  Slacken an end cap spindle frees up - have I put the crinkle shaft expansion washer in the wrong place  Pull it apart, no washer in correct place, make sure bearings fully home - reassemble - still stiff - argh, beginning to loose the will to live . Dismantle for third time, examine everything, find a burr on one bearing retainer ring pressing inwards onto shaft - bung it back together, put it back on it's pillar - all OK except I've just lost an entire morning 

So I didn't get started on the furnace until this afternoon. First thing, pull it away from the wall on the pallet truck and unbolt all the doors - front one has keys, the other three although hinged are bolted shut, and the last panel is just bolted and not really removable as loads is mounted on it.

To get it out of my previous foundry, the main isolator switch operating handle, and the 125 A input socket had to be removed to get it through the door - but where are they? OK found tucked away inside behind panels, and at least I had had the foresight to label the phases 

Bit of a pain re-assembling them - one of the Nutsert bushes holding the input socket failed and is pretty well impossible to get at, so it's fixed with three out of four bolts, but OK for now.

[awemawson]

So now on to the driver connections to the furnace body. There are four rubber hoses each with a heavy braided copper cable cooled by a water jacket - or they would be if I had a cooler !

Searching around I found that I had made sketches back in 2005 when I got this beast to better understand how it interconnects.  Basically there are two coils (actually one centre tapped) with a blockage for water where they join. The coils are wired in parallel and give about 13 micro-henries of inductance.

There are two water circulating paths.

OK how do I connect it - I opened up the back of the furnace body that I moved yesterday and then remembered - as I had two bodies I had a system of quick disconnect couplers, with copper braid jumpering them so that the QD surfaces didn't carry the current. But my short hoses don't have the QDs fitted.

Options -

A/ lug the long pipes over - I think they have the QDs
B/ remove the QDs from the furnace (actually not easy due to the construction around them
C/ use the replacement coil set that I have suitably suspended to avoid human contact (nasty high voltages)

I'm tending to option C/ at the moment but will think it over, meanwhile I've realised that I don't have a spare cable mounted 125 A socket to power the beast up, so I need to rob one from somewhere else.

Time for a cup of tea !

[Sea.dog]

I take it that you don't have a Rivnut set? It would be a 5 minute job to drill the old nut out and replace.

[awemawson]

I do, and it isn't, as it rotates in the hole !

(The nutsert has pushed through the panel, but the bolt is firmly stuck in it so bolt would need sawing off in situ )

These 5 minute jobs - had one of those this morning . . . . 

It can bally well make do with three screws until the fate of the big blue box is decided !