Author Topic: Developing a Small Steam Plant  (Read 14127 times)

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #60 on: November 26, 2019, 09:56:34 PM »
The pipe cleaners have not yet arrived, so rather than pace up and down fretting I transferred my attention to making a handle for the boiler feed pump:





The grip is aluminium, the shank a random piece of steel of unknown kind that I inherited with a lathe I bought a few years ago.

I'm pleased with the chunky undercut thread on the shank and the curved profile of the shank (which took quite a lot of work with files and abrasives in the lathe). The overall finish is reasonable and I can always go back to it again if I decide to. I am definitely not pleased that the slot at the bottom of the shank (to fit over the brass handle of the pump) is off-centre. I have no idea how this happened. I used an edge finder on the insides of the vice jaws and the 1/2 function of the DRO before cutting it with multiple passes of a small endmill.. Maybe I wasn't as accurate with the edge finder as I should have been - I don't know. I'll get away with it because it's only a pump handle and the slot will be covered by a collar. I most certainly will not get away with it when I get to building my second engine, so I need to address this.

I also reckon that some people may feel that the handle asssembly is a bit big and somewhat out of scale with the rest of the plant. On the other hand, it should be a nice chunky handle to pump water with.

Still on track, the inevitable imperfections notwithstanding...

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #61 on: November 27, 2019, 05:48:11 PM »
Well, since none of you  have talked me out of using that handle on the basis that it's visually too big for the plant, I've decided that I might as well talk myself out of it. It's too big for the plant. Or is it? Dammit, I don't know...depends on how you look at it... but certainly I have thought of other applications in which I could use it, so we'll see...

Meanwhile, here's my little oil refinery in development. Welcome to pipe cleaner heaven:







Looking at it might make you go crosseyed, but I think it more or less makes sense. The photos make some of the pipe cleaners look as though they are angled all over the place, but in fact they are pretty much arranged in right angle bends (I have a few elbows in my box that might be nice to use). The red pipe cleaners represent lagged pipes, the blue ones bare copper. The spiral bits are just where I have wound the pipe cleaners around existing pipes, and the bit of blue near the engine represents the displacement lubricator (winging its way as I type).

Apart from any other comments any of you may have, I only have two questions:

1. I have designated the pipe routing steam up the chimney from the separator as lagged. Should it be so?

2. How do I get water and steam to flow through the pipe cleaners? I have looked and they don't seem to be hollow in the middle. Can't for the life of me figure that one out...

Offline JC54

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Re: Developing a Small Steam Plant
« Reply #62 on: November 27, 2019, 07:52:54 PM »
Ask Santa to bring you some very thin long Drills?
When the Fun Stops,, Stop!

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #63 on: November 27, 2019, 08:52:53 PM »
Ah... so that's how it's done! Yep, makes sense...

Offline crueby

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Re: Developing a Small Steam Plant
« Reply #64 on: November 27, 2019, 10:29:28 PM »
Ask Santa to bring you some very thin long Drills?
Aircraft extension drills....   :Lol:

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #65 on: November 28, 2019, 12:33:14 AM »
Amazon is my friend...

Offline JC54

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Re: Developing a Small Steam Plant
« Reply #66 on: November 29, 2019, 10:57:04 PM »
My vote is keep pump handle as it is. I think it is in keeping with the engine,, something different. :ThumbsUp: :old: :DrinkPint:
When the Fun Stops,, Stop!

Offline MJM460

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Re: Developing a Small Steam Plant
« Reply #67 on: November 29, 2019, 11:55:44 PM »
Hi Gary, looks like it’s time to make up some tube connectors, and bend some copper tube, now you have the 3-D patterns.

You asked about insulating the outlet from the separator/feed water heater.

Insulation is normally applied for one of two reasons, or perhaps even both.  The obvious one is for heat conservation, and the other is for personal protection.  In this case, heat conservation is not really required, though if the outlet steam gets to the top of the stack before it condenses, it will more readily be dispersed into the atmosphere as extra humidity rather than raining inside your workshop.  So I would suggest in this case the main issue is personnel protection.

In the oil industry, and I assume power generation is similar, personnel protection is required if the surface is both accessible for accidental touching and above 65 deg C, above which burn injuries are considered likely.  Probably a bit of a safety margin in that, especially if you are an experienced welder with tough skin, but the line has to be drawn somewhere.

You might be interested to know what happens if the pipe is hot enough to cause injury, but process reasons require cooling.  In such cases, a cage is made from expanded metal mesh and supported of the pipe by appropriate brackets in the accessible areas, for example where the pipe passes through a platform.

The exhaust steam in that pipe will be a mix of steam and air, so the final temperature after the feedwater has absorbed what the available heat transfer area will allow, is a bit hard to guess, but it will probably be a little above 65, but certainly less than 90.  Considering the nature of the plant as a whole it is probably not the biggest injury risk you need to be aware of, so I suggest that you can take your choice.

MJM460



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

Offline derekwarner

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Re: Developing a Small Steam Plant
« Reply #68 on: November 30, 2019, 04:22:22 AM »
Gary......

I found the DuBro 1/8" & 5/32" OD bending spring & wasted so many bends as being inaccurate in the set of and badly rippled inner surfaces, despite pre annealing the bend area

I finally purchased a pair of DuBro tube benders for the above sized tubes and find the K&S 1/8" & 5/32" OD brass tube can require 2 or 3 annealings until red hot, then air cooling after each annealing can achieve a smooth 90 degree bend with absolutely minimal surface rippling on the tube inner radius surface

If you read & view images of older  :old: full sized steam plants pipe work, you will note 90 degree bends, with pipe spools set in 3 principal  planes.....yes 'vertical', 'horizontal' and 'across

Parallelisim of pipe runs is also an aspect point as viewed that follows for the 3 planes mantioned

There is no use of 135 degree bends  :facepalm: or angular set of any pipework

So after realisation of the above my scale tubework [generally] follows these principals

Derek

« Last Edit: November 30, 2019, 11:25:38 AM by derekwarner »
Derek L Warner - Honorary Secretary [Retired]
Illawarra Live Steamers Co-op - Australia
www.ils.org.au

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #69 on: November 30, 2019, 04:24:12 PM »
Hi All.

Many thanks for your input.

@ JC54 - on the handle - you have emboldened me! It's quite a big handle but it's not like the plant is a 'model of' anything, so there's no predetermined look for it to spoil. And yes, I suppose it does sort of go with the engine, so I am now one step closer to keeping the handle as is.   :ThumbsUp:

@ MJM460 - educational, as always. I'm not too worried about the safety angle in this instance. As you suggest it's relatively minor (and I have been burned too many times to care...). What I'll do is run it with the pipe in question left bare, see what it does and then decide whether or not to lag it.

@ Derek - I agree with you about the 90 degree bends. It's certainly my intention to keep everything as square as possible. However, I have these:



I have quite a few of these elbows and straight connectors for both pipe sizes (3/16" and 1/4"). Using elbows instead of at least some of the bends would probably make life easier in that cutting straight pipe lengths and silver soldering nipples on to them will be easier  to keep accurate than full pipe runs with several bends in them.  However, will using elbows instead of bends impair efficiency by creating more drag on the steam passing through? Or would the difference be insignificant in a plant of this size?

And why do I find myself thinking that that last question has MJM's name on it...?   ;)

@ Derek - thanks for posting the photos. Great looking plant! What is that you used for the pipe insulation?

Offline derekwarner

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Re: Developing a Small Steam Plant
« Reply #70 on: November 30, 2019, 07:32:42 PM »
Gary.......the advantages of using those demountable elbows you show are many indeed, the single biggest disadvantage is in the hot steam tube to the engine & the mass of the fitting body, tails & nuts all consume more heat energy that a bent tube...same naturally applies to straight unions........a Golden rule is to keep the hot steam line a short as is reasonably practicable

In many installations, you may have a lubricator and then a regulator in the steam line between the boiler & the engine....so these must be considered & also lagged if possible

So the greater the material mass of the hot steam tube reduces the temperature of the steam & increases the formation of condensate/water

There is certainly a lessor issue with return lines, although it is best maintain the hottest exhaust steam temperatures the let the de-oiler perform its task

The tube insulation is pretty simple.......cotton twine [1.5 mm diameter] + a drop of Superglue......then wound progressively over the tubing....around the bends as needed & ended with another drop of Super glue........layer & paste a Home Brand Celulose type Polyfiller over the cotton twine to your required thickness....I chose say 2 mm deposit, then sand with 140 grit paper gently and progressively in sheet or tube format until you end up with a uniform thickness of ~~ 1.5mm depth......paint with oil based primer + oil based top coat

Derek
« Last Edit: November 30, 2019, 07:39:47 PM by derekwarner »
Derek L Warner - Honorary Secretary [Retired]
Illawarra Live Steamers Co-op - Australia
www.ils.org.au

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #71 on: December 01, 2019, 11:39:57 AM »
Ah yes, that makes sense, Derek.

Not so much about friction/baffling effects; more about heat loss. Right enough, now that you point it out it's a bit self-defeating to lag pipes then stick a big heat sink in the middle of them. so... I will use the elbows where it doesn't matter (e.g. the cold water feed) and bend the others.

Thanks also for the recipe for lagging the pipes. Not sure I will do it the way you describe, but will certainly consider it.

Cheers,

gary     :ThumbsUp:

Offline MJM460

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Re: Developing a Small Steam Plant
« Reply #72 on: December 01, 2019, 11:37:04 PM »
Hi Gary, a bit slow on taking my cue, it’s been a busy morning.

On the pressure drop, yes, a change of direction involves more pressure loss than the same length of straight pipe, though as you suggest it’s not a lot in the great scheme of things.  The component of velocity in the direction of the straight pipe is reduced to zero, involving the loss of one velocity head of energy, and it is a loss, not converted to extra pressure.  Then the flow has to be accelerated in the other direction, which takes another velocity head.  Obviously the two occur in a gradual transition rather than in sequence, but the total effect is similar.  The important thing to appreciate is that velocity is a vector and has direction.  Maintaining the same speed of flow around a bend does not avoid the issue.

If you have a sharp bend, such as the intersection of two drilled passages in a solid fitting, there is even more energy lost in turbulence created.  There is less turbulence in a smooth sweeping bend so less energy loss.  The standard data for a forged pipe bend of the standard radius is about 13 times the equivalent length of straight pipe.  So for 1/4 in. tube, about 3 inches of extra length.  You can see why I say overall it is not much.  But bending the tube avoids the cost of the fitting as well as in principle being the right direction on energy losses if you are after the last bit of performance.  You do what fits when you have plenty of pressure which you are dissipating in a control valve to run an engine slowly, as pressure loss is not a problem.

On the heat loss issue, Derek is quite right that it takes heat to get the extra metal in those fittings up to steam temperature.  That certainly results in extra condensate when you are starting from cold.  However, providing you insulate them well, the extra heat loss once warmed up is only due to the extra surface area, and easily managed by a bit of extra thickness of insulation, so again, not much of a problem in the grand scheme of things, especially with that good condensate separator you have made.

It might not be immediately obvious just why refinery piping is always run parallel in the three orthogonal directions.  Cutting across at an angle would obviously involve a shorter length, hence lower cost.  Basically the parallel runs allow the most usable space for future additions, while the remaining open space is more friendly for cranes and other maintenance equipment, so not only to look tidy.  A singly line across a pipe trac at an angle can block hundreds of meters of otherwise useable space where the pipe supports are already in place.  In your plant you may prefer graceful curves in keeping with your engine design.  It’s up to you.

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 #73 on: December 03, 2019, 10:56:26 AM »
Thanks MJM.

Putting this all together, I reckon I'll try to avoid using couplings where it's reasonable to do so, but not be too phobic of them for the tricky bits and where it doesn't matter.

As for the aesthetics - good point. Graceful curves are nice, but then so is a bit of juxtaposition of organic and geometric. I'll play it by ear...

Fascinating to learn about allowing space for service vehicles etc among refinery pipework. Obvious if you are in the know, I suppose, but what lay person would have thought of it?

All the Best,

gary

 :ThumbsUp:

Offline gary.a.ayres

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Re: Developing a Small Steam Plant
« Reply #74 on: December 05, 2019, 10:30:56 PM »
The displacement lubricator arrived today. PM Research LUB-2, 2" long, 3/16" x 40 thread. All the way from the USA. Here it is, along with the tee by which it will be connected into the system, lying on the baseboard which is now looking pretty good after five coats of water-based gloss woodstain/varnish in a 'dark mahogany' hue:



I guess I could have had a go at making a lubricator myself but it strikes me as being something of a mission and I'd rather devote the required amount of time, energy and angst to something more substantial.

As for hooking it up, here's exactly how I plan to do it (3:35 to 5:07):

<a href="https://www.youtube.com/watch?v=y9o6dXWGE10" target="_blank">http://www.youtube.com/watch?v=y9o6dXWGE10</a>

Now that I have this part and the baseboard is varnished, I can finalize my layout and start screwing things down and piping them together.

 :cartwheel:

 

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