Author Topic: Developing a Small Steam Plant  (Read 3442 times)

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #30 on: October 08, 2019, 10:46:36 PM »
Thanks guys.

@ Pete - well, that makes sense! I was thinking that only some of the steam would condense, with some left over to send up the chimney to draw the flame (I have found that the blower - when used - sometimes helps focus a kerosene, alcohol or even gas flame into the bottom of the boiler). From what you are saying I guess that if anything does come out of the exit end of the separator it might be quite a gentle flow and that might actually be quite good to just gently pull up the flame. But we shall see. Your point has got me thinking that the thing for me to do is to first trial it without connecting the outlet to the chimney. If nothing is coming out there won't be much point in hooking it up, but if there is some outflow - event slight - I think it would be worth routing up tthe chimney.

@ ChucKey - agreed. Or like the cyclonic separator in a shop vac system. Already part of the plan!   :ThumbsUp:

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #31 on: October 08, 2019, 11:10:01 PM »

 That water will have oil in it but if you could work on an oil seperator you could then feed the hot water back to the water tank.

Just thinking.....

Pete

That's a thought, Pete, though I'm not sure I want to take this plant that far.

gary

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #32 on: October 09, 2019, 10:25:02 PM »
Wahey!

Silver solder day.   :Mad:



Below: the top half. The brass cap was silver soldered on to the copper tube. This picture shows the steam inlet pipe - which enters the vessel at a tangential angle -  just before I soft soldered it into the hole. This was the only soft soldering I did today.



The main body of the separator is pretty much done. All of the joints on the bottom half are silver soldered, but the middle joint is left as a push fit so that the vessel can be opened up for cleaning and so on. If there is any leakage from this I'll cross that bridge later, perhaps with some silicone. As noted above, this isn't a pressure vessel:



I'm waiting for an outlet valve with matching bush to arrive. When they do, the end cap of the 90 degree bottom tube will be drilled and the bush soft soldered into it. The next step after that will be the coil.

I'm not the neatest solderer in the world, hard or soft. I guess a lot of it is just practice. However, I'm not unhappy with the overall result, especially since most of it will be hidden inside the aluminium stand.

Offline crueby

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Re: Developing a Small Steam Plant
« Reply #33 on: October 09, 2019, 10:29:02 PM »
Your WorkMate looks like mine - pile of partly broken fire bricks, some scorches on the wood... Well lived in!
 :popcorn: :popcorn: :popcorn:

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #34 on: October 09, 2019, 10:34:38 PM »
I'm in good company then!

The first time I silver soldered it took me by surprise - I set my actual shop bench on fire. Plastic containers on the shelf above were melting with the heat from the torch and it was raining stainless steel cap-head screws...

 :Mad: :Mad: :Mad:

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #35 on: October 11, 2019, 12:05:14 AM »
The steam valve and bush arrived today so this evening I was able to drill the end of the drainage pipe, soft solder in the bush and trial fit the valve. Again not the neatest soldering in the world (everything runs - maybe I need thinner solder wire?) but it will be fairly well hidden when it's done and at least the valve hasn't ended up crooked. For the delicate soft soldering of the steam in pipe and the valve bush I bought a cheapo fine flame blowtorch at B&Q yesterday and I must say it's excellent for this kind of work:



Then the chickens came home to roost. I had begun to get the idea that I might have been premature in silver soldering the cap on to a fairly long tube section before fitting the coil, as it was going to be a faff trying to fit and tighten up the union nuts on the coil inside the cap when the coil was in the way. I got the first end done easily enough before I wound the coil:



Then with that end still attached I wound the coil round a bar of acetal held in the vice. The entire length of the coil used my remaining length of 3/16" pipe with nothing to spare:



But getting the coil into the tube was a mission to say the least, as I was working against two straight verticals and the 3/16" tube was work-hardening by the minute. I had thought of putting an elbow at the bottom which would probably have made life easier - but I didn't. This was probably not the best way to go about it but I think it all goes back to my earlier step with the cap. A simple flanged cap as MJM suggested would have been much easier to manage. The first union nut that I had tightened worked loose as I manhandled the coil, so now I have the awkward job of reaching in past the coil and tightening all three, including the one on the vertical steam out pipe in the centre of the cap. I have nothing that will reach in there so I'm going to have to make a long thin right angle spanner for each of the two sizes of nut.

The other issue was that I could only push the coil so far into the cap before the straight sections prevented it from going any further. In the picture below, although you can't see it, the top of the coil (before it turns into a straight run) is only just over a third of the way up the top half of the vessel:



This bothered me at first as I feared a loss of efficiency, but the idea then dawned on me that probably all I need to do is to make the bottom end of the central steam out pipe longer so that it goes down quite far through the coil towards the bottom of the vessel (though clearly not so far down that the end will be immersed as soon as condensate starts to collect!). That way the steam will have no option but to descend into the depths of the coil before it can find its way out of the separator.

It also occurred to me that the bit of empty space above the coil where the steam comes in might not be such a bad thing either as it may give the steam a chance to build up a bit of a cyclone witthout interference when it first enters the vessel. This last point might be wishful thinking on my part - I'd be interested in any views on this. And on the rest of it of course...

So I need to make two tools to tighten the nuts, but other than that it seems to be goiing ok if my hypotheses above are correct. As a by-product, I have also realised that winding the simple coil for my flash steam plant (featured in another thread) should be a breeze...

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #36 on: October 14, 2019, 11:37:46 PM »
Not the most inspiring pictures tonight, unfortunately.

Because of my design issue of making the top section too long, it was a right game tightening up the union nuts on the coil on the underside of the cap. You can imagine. I tried making a right angle spanner-like tool out of a bit of steel, but that proved to be too flimsy and it bent even though I had hardened it. In the end I just took a perfectly nice 10 mm spanner, put the business end of it in the vice and  bashed it into a right angle with a hammer. For shame! Sheer vandalism, but it did the trick and I was able to get the internal coil connections to what I believe to be watertight.

With that done it was even trickier to tighten the connection on the central steam outlet pipe, so I re-thought it and drilled and tapped the central hole in the cap M12, then turned an elongated bush from brass with a slight taper on one end and an M12 thread on the other. This was drilled through for a sliding fit on the 1/4 " OD pipe and screwed into the hole in the cap. The threads fit nicely, but a hank of PTFE tape and a blob of Stag Wellseal will ensure that no stray steam escapes:



I then ran a length of the pipe through the bush with the bottom end at what I guess to be about the right depth in the vessel and plenty to play with sticking out the top. A union nut and nipple were added at the top and the assembly was silver soldered up. Here it is in situ:



This more or less completes the working assembly of the steam separator / feedwater preheater. I will use some of my self-amalgamating tape to make a seal between the top and bottom halves of the vessel, which will be ok because it won't be seen. I'll also insulate the main part of the body with ceramic fibre - ditto. The aluminium stand will cover a multitude, and that is what I'll tackle next.

Shiny toys!

Offline Ye-Ole Steam Dude

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Re: Developing a Small Steam Plant
« Reply #37 on: October 15, 2019, 12:05:21 AM »
Hello Gary,

Still following and watching  :popcorn:

Have a great day,
Thomas

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #38 on: October 15, 2019, 12:07:29 AM »
Many thanks Thomas.
You too   8)

Offline MJM460

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Re: Developing a Small Steam Plant
« Reply #39 on: October 15, 2019, 06:36:25 AM »
Hi Gary, good to see you managed to get the coil in.  Well done on that.  I was wondering how you would do it after soldering the top on to the cylinder first.

Remember that the water inside the coil is at full boiler pressure, so silver solder as many of the joints in that tube as you can.  All the joints which only see exhaust steam operate essentially at atmospheric pressure, so are the easier ones to seal.

MJM460

The more I learn, the more I find that I still have to learn!

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #40 on: October 15, 2019, 09:21:26 AM »
Hi MJM.

Getting the coil in was a mission, to say the least - both actually getting it in there, then tightening the nuts. Serves me right for not thinking it through properly. I don't think it's too bad a job in the end, though.

There are only two connections in the coil, and these are where it joins the cap. They are made with pipe nipples silver soldered on to the ends of the pipe and secured with union nuts. The unions are screwed into threaded holes in the cap. It's the tightening of the union nuts that makes the seal, and I *think* I managed to get them watertight (probably steamtight in fact though they don't need to be). I'll test these connections with an engine run under steam before final assembly though.

The joints at atmopsheric pressure shouldn't present too much of a problem, as you say.

 :ThumbsUp:

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #41 on: October 17, 2019, 11:12:18 PM »
Just back from working away from home, but managed to squeeze in a little bit of shop time this evening.

Milled a notch into the thick-walled aluminium tube that will act as a stand and jacket for the separator to provide access for the steam inlet pipe and to centre the separator in the stand:



Like the steam inlet pipe, the sides of the notch are tangential to the bore of the stand.

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #42 on: October 20, 2019, 09:57:19 PM »
The housing (a better term for it than 'stand') for the separator is quite tall, and when combined with the height of the chuck on the rotary table it is beyond the capacity of every machine in my shop apart from the big floorstanding drill press:



The plan is to make a bolt circle in order to attach the cap to the housing. I'm going to use M2 cap head screws for this, with a tapping drill size of 1.6mm. The chuck on the drill press won't hold anything that small, but it will hold a very small Jacobs chuck that I have, which will in turn hold the drill bit. This arrangement produces a certain amount of runout, but I think the centre drill which you can see here will counteract that. The dividing plate attachment on the rotary table enables the correct spacing of the six holes. Note the mill table which I have fitted to the drill press - it's a very handy addition. Recommended!

I got as far as centre drilling  the holes (as in the photo below) before I had to leave to go away until midweek. Once they are drilled and tapped I'll use transfer screws to mark out the positions on the cap.


Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #43 on: October 23, 2019, 11:00:48 PM »
So.

Holes drilled and tapped:



So far so good. But next comes a comedy of errors. Because I had already silver soldered the top half of the separator to the cap, and not having any long series drills, I decided it would be necessary to drill the clearance holes for the fixing screws in the cap from above to avoid a foul-up between the drill chuck and the top half of the separator. I put four transfer screws into the holes in the housing, turned the cap assembly upside down and set it all up to transfer the holes by giving a wooden block placed on the other end of the housing a sharp tap with a wooden mallet:



However, it didn't occur to me that the position of the steam inlet pipe would be a problem. It should have, but it didn't. The four holes transferred nicely (I only have four M3 transfer screws), but due to the fact that I had positioned the holes in the housing somewhat randomly relative to the notch for the pipe, the position of the notch caused the pipe to lever the cap round and throw the holes in the cap out of alignment with those in the housing when the cap was turned the right way up:



Rookie error!   :facepalm:

I initially thought of widening the notch, but then decided to try to bend the tube to a more forgiving angle. The tube did not bend. The soft solder sheared, and the tube came out:



 :facepalm: :facepalm:

I'll have to solder it back in again at a better angle, after which I'll transfer and drill the two remaining clearance holes.

Not a major disaster, but the result of not thinking through the sequencing issues properly, and it's striking how a mistake early on can make its presence felt through subsequent steps.

Still, at least I now shouldn't have to widen that notch in the housing, and the drilling, tapping and transferring of the holes seems to have gone well...

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #44 on: November 03, 2019, 10:04:24 PM »
Managed to make some reasonable progress before I went on holiday and today having just got back.

The cap is now in situ, fixed with stainless M3 pan head screws:





Work then began on the aperture at the bottom through which the drain valve will protrude.

Centering the housing on the drill press:



Cutting the aperture with a hole saw. This went quite well, and overall the aperture looks fairly neat. Inside the housing there is a gouge at each side as the hole saw cut vertically through the sides of the tube. I'm going to leave this be as any attempts to tidy it up will probably just make it worse. In any case the gouging is pretty much internal and doesn't really harm the overall look. It's visible on the finished assembly but you have to peer a bit to see it. No big deal.



I had a nice thick brass ring left over from a failed attempt at making a meths burner housing. This just needed a little drilling to convert it to a base for the separator housing. I centred it by eye under the housing and marked it out...



... then drilled three clearance holes to allow it to be fixed to the bottom of the housing courtesy of three corresponding holes drilled and tapped M3. These three holes are a bit out of alignment with the existing outer holes but that won't matter as only the outer holes will be seen. They will be used to fix the asssembly to the base board of the plant.



I used both transfer punches and transfer screws to mark out the various fixing holes in the cap and the base. They are extremely handy for accurately transferring hole positions.

Finally, the basic assembly in a more or less complete state:



There are still a few bits and pieces to attend to and the whole thing will benefit from a bit of a shine up. Getting there though...