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Post by Roger on Dec 3, 2020 22:31:12 GMT
I made a couple of Delrin sleeves to replace the Safety Valve springs so I could do the hydraulic test. 20201203_133224 by Roger Froud, on Flickr I actually took it up to 250PSI, but decided not to push my luck with the gauge glass. Out of interest, the Water Gauge seals perfectly on the glass, even though I can turn it with my fingers when there's no pressure. In my opinion, this is far more satisfactory than having a gland that can apply an uncontrolled amount of force on the glass. There's no need for any adjustment if you use 'O' rings correctly. 20201203_140022 by Roger Froud, on Flickr Here I've drained out half of the water so it's on the gauge, and I'm setting the safety valves to 100PSI having replaced the sleeves with the springs. I need to make a pipe to allow me to connect the hand pump to one of the clacks. 20201203_152401 by Roger Froud, on Flickr
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dscott
Elder Statesman
Posts: 2,440
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Post by dscott on Dec 4, 2020 1:20:11 GMT
It is so looking like something out of a Brewery! Says he who last visited an establishment back during July. While in Plymouth.
You must give it a go at making tea. A workshop must.
David and Lily.
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Post by Roger on Dec 4, 2020 11:08:45 GMT
The Test Boiler is going to have a simple temperature control arrangement with a potentiometer to effectively set the pressure. The TDA2086A Phase Angle Control chip is something I'd used in another life to control a refrigeration unit, so I happen to have a PCB with this already assembled. The Datasheet shows many applications, but this is the one relevant to what I'm doing. It uses a Triac on a big heatsink to ground the Neutral side of the Element which has the other side permanently connected to the incoming Live terminal. Feedback is by way of an NTC Thermistor which will be inserted into the place normally occupied by the Thermostat. It gets pretty hot, so I've sourced appropriate Glass type Thermistors which are good up to 200C. The wires for the Thermistor and Heater are all Silicone types and there's high temperature heat shrink and sleeving for the Thermistor. Figure 17 by Roger Froud, on Flickr Anyway, this is how it looks. It's only drawing about 8Amps and I've fitted the largest heatsink that will fit the PCB. I designed it as a general purpose PCB with all the feedback and filtering options described in the Datasheet in case I wanted to use it for other jobs. All of the relevant outputs were brought to the chunky connector. 20201204_104825 by Roger Froud, on Flickr The box is going to be 3D printed, so I've designed that as one piece which will be printed out in two halves. There are generous slots in the top and bottom, and it will be stood on spacers to make sure air can get in at the bottom. Control box by Roger Froud, on Flickr I crudely modelled the PCB and the big components so I could see where best to put the cable glands etc so it can be wired up without too much difficulty. Making the box translucent makes it much easier to see how much room there is. I've also embedded pockets for the M4 nuts that will hold the top on. I'll pause the print part way through and drop those in. Control box translucent by Roger Froud, on Flickr I don't have large enough Silicone wire for the elements, or a 13A plug and the long Cap Screws, so all of those have been ordered now. Hopefully those will be here later in the week and then I can try it all out. The only thing I need to think about is a cover for the exposed heater terminals. I'll probably 3D print one, I've got some Colorfabb HT which I made the blower from, so that will probably do. Just one question... what water treatment should I be using for a Steel boiler?
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Post by Doug on Dec 4, 2020 11:35:33 GMT
Hi Roger what material are you using for your valve handles (the look like wood ) is it some sort of tuffnall ?
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Post by Roger on Dec 4, 2020 12:27:34 GMT
Hi Roger what material are you using for your valve handles (the look like wood ) is it some sort of tuffnall ? Hi Doug, Yes, it's Tufnal rod, the smallest diameter I could find. I think it's 12mm, but I've just looked again, and now I can see it in 6mm, 8in too here.
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tony9f
Seasoned Member
Posts: 105
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Post by tony9f on Dec 4, 2020 13:19:32 GMT
Hi Roger,
I have been following your test boiler build and I'm very impressed with it. Temperature control is definatly the way to go, did you design the electronics yourself? As to water treatment, using soft water is the obvious thing but not de-min as this can act as a solvent on the metal. De-oxygenating the water is also a good move and just using pre boiled water will answer that. Proper deaereators generally keep feed water at 80 degrees which is too hot for your purposes. There are chemicals that absorb oxygen such as hydrazine (very nasty) or sodium bisulphite but I reckon a central heating inhibitor would do a similar job. The other thing (important with steel boilers) is controlling acidity, you want the water to be slightly alkaline. Milk of lime was what they used before purpose made additives were available. Finally, I believe the addition of tannin to the water was used to help to control dissolved solids by coalescing them into a sludge that can be blown out. In all honesty I don't think that tour boiler will be dealing with a large enough throughput to really warrant much of the above but protecting the shell from rust and the element from scale are priority. It's been a few years since I ran boiler plant so some of the above might be a bit rusty...hope it gives you some assistance.
Tony
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Post by ettingtonliam on Dec 4, 2020 14:20:31 GMT
Use rainwater (with the algae filtered out),blow down when hot, and store dry.
Come on Roger we are all agog to see you plug this in and raise steam!!
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Post by Roger on Dec 4, 2020 16:59:15 GMT
Hi Roger, I have been following your test boiler build and I'm very impressed with it. Temperature control is definatly the way to go, did you design the electronics yourself? As to water treatment, using soft water is the obvious thing but not de-min as this can act as a solvent on the metal. De-oxygenating the water is also a good move and just using pre boiled water will answer that. Proper deaereators generally keep feed water at 80 degrees which is too hot for your purposes. There are chemicals that absorb oxygen such as hydrazine (very nasty) or sodium bisulphite but I reckon a central heating inhibitor would do a similar job. The other thing (important with steel boilers) is controlling acidity, you want the water to be slightly alkaline. Milk of lime was what they used before purpose made additives were available. Finally, I believe the addition of tannin to the water was used to help to control dissolved solids by coalescing them into a sludge that can be blown out. In all honesty I don't think that tour boiler will be dealing with a large enough throughput to really warrant much of the above but protecting the shell from rust and the element from scale are priority. It's been a few years since I ran boiler plant so some of the above might be a bit rusty...hope it gives you some assistance. Tony Hi Tony, I designed the PCB, but the schematic is broadly taken from application notes in the chip Datasheet. The circuit was produced for the company I worked for about 20 years ago, but I still had one of the circuits to hand and thought it was suitable for this. Thanks for the information about the water, it's certainly not simple. I think I'll do what someone else has suggested and drain it out when it's not being used. If it's hot, I can blow air through it to dry it out. I might pour a little Fertan into it and run it around to cover everything.
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stevep
Elder Statesman
Posts: 1,072
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Post by stevep on Dec 4, 2020 17:31:27 GMT
Use rainwater (with the algae filtered out),blow down when hot, and store dry. Come on Roger we are all agog to see you plug this in and raise steam!! I thought that rainwater is always slightly acidic (carbonic acid), and as Tony has suggested that steel boiler water should be kept slightly alkaline, that may not be a good idea. But blowing it down and storing it dry is, I believe accepted wisdom.
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tony9f
Seasoned Member
Posts: 105
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Post by tony9f on Dec 4, 2020 17:42:48 GMT
Good idea using Fertan, at least you will phosphate the internals. Draining the boiler and drying is absolutely the right thing to do between uses. It is exactly what is done on full size plant when out of service for prolonged periods and usually left open to the air. Alternatively purge with inert gas.
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Post by Roger on Dec 4, 2020 17:55:34 GMT
Good idea using Fertan, at least you will phosphate the internals. Draining the boiler and drying is absolutely the right thing to do between uses. It is exactly what is done on full size plant when out of service for prolonged periods and usually left open to the air. Alternatively purge with inert gas. That's clinched it then, blowing down and drying plus Fertan it is. I've already painted the inside of the threads with Fertan before adding the fittings. I certainly could purge it with Argon once it's dry, but It's probably overkill. It's probably not going to get a lot of use after the initial Injector experiments, but you never know. It ought to be man enough to drive the locomotive for a test, so I might find myself doing that before a run to check all of the systems. Everything I make seems to end up being more useful than I had originally envisaged, so I'll keep an open mind.
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Post by andyhigham on Dec 4, 2020 19:19:05 GMT
I have received a newsletter today, it describes the boiler treatment for the new boiler on Sybil (ex Dinorwic Bagnall) "Earlier in the year the major components were grit-blasted inside and out and then painted to help protect the new boiler from corrosion. The insides, i.e. the parts of the boiler which will be in contact with water or steam, were painted with Apexior Number 1, a long-established anti-corrosive paint specially formulated for use inside boilers. It should also increase thermal efficiency, as it is claimed to increase heat transfer through the boiler plate and tubes. The outsides were painted in a suitable heat-resistant paint"
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Post by Roger on Dec 4, 2020 19:27:17 GMT
I have received a newsletter today, it describes the boiler treatment for the new boiler on Sybil (ex Dinorwic Bagnall) "Earlier in the year the major components were grit-blasted inside and out and then painted to help protect the new boiler from corrosion. The insides, i.e. the parts of the boiler which will be in contact with water or steam, were painted with Apexior Number 1, a long-established anti-corrosive paint specially formulated for use inside boilers. It should also increase thermal efficiency, as it is claimed to increase heat transfer through the boiler plate and tubes. The outsides were painted in a suitable heat-resistant paint" Thanks for that, I've not heard of Apexior Number 1 before. Of course, my boiler is different from conventional ones in that heat transfer on the metal components is something to avoid rather than enhance. In reality, it's not going to get enough use for corrosion to be a big issue unless I leave it all damp.
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Post by andyhigham on Dec 4, 2020 20:02:28 GMT
BTW Sybil is essentially a full size "Sweet Pea"
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Post by coniston on Dec 4, 2020 22:13:29 GMT
Hi Roger what material are you using for your valve handles (the look like wood ) is it some sort of tuffnall ? Hi Doug, Yes, it's Tufnal rod, the smallest diameter I could find. I think it's 12mm, but I've just looked again, and now I can see it in 6mm, 8in too here. Glad Doug asked the question, I've been keeping my eye open but didn't think of ebay, thanks for that Roger, just bought some. Chris D
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Post by Roger on Dec 4, 2020 22:16:51 GMT
My thoughts are turning to making the injector cones now that I've got the material, the design and the Reamers made. However, getting the exact diameters of the tapers is challenging. My solution is to use stops, which are what most people use. However, I don't like the idea of setting the positions using the parts I'm machining, I'd rather set them precisely on the bench. To that end, here's an 8mm Piece of Silver Steel that's been faced off and reamed 1.6mm The idea is to use that diameter as the reference. I want it to be tough enough to be able to resist being damaged by the Reamer when it's offered up to the edge, but not hardened so it damages the Reamer. 20201204_203546 by Roger Froud, on Flickr I'm made two 8mm Silver Steel stops with M2.5 grub screws. The stops and the gauge have been made long enough to ensure they sit nicely in the Vee block, and are clocked true to the middle. So I plan to use a Slip Gauge between the two pieces then slide the reamer into the gauge piece and lock the grub screw. That will give be a known reference length from the 1.6mm diameter and the stop. I can use another longer Slip gauge between the end of the Cone and the stop so I have a known reference point to start from. Yes, I know I could ream a 1.6mm hole in the end of the cone I'm making and then go in from the point it first touches, but I think this is a bit rough and ready. Having a known reference means I'm not stuck if the reaming is interrupted, I'll always be able to find my way back. 20201204_214445 by Roger Froud, on Flickr This may all seem a bit over the top, but the intention is to make these as close to the drawing as possible. I know the angle is very close to the drawing, and I also want to make sure that the throat diameters are very close too. There's little point in going to the trouble of designing something precisely, then making it roughly and then not knowing if it doesn't work because the design is wrong or whether it's just not to the drawing!
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Post by coniston on Dec 4, 2020 22:23:15 GMT
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Post by Roger on Dec 4, 2020 22:23:58 GMT
Hi Doug, Yes, it's Tufnal rod, the smallest diameter I could find. I think it's 12mm, but I've just looked again, and now I can see it in 6mm, 8in too here. Glad Doug asked the question, I've been keeping my eye open but didn't think of ebay, thanks for that Roger, just bought some. Chris D Hi Chris, Glad that was useful. My first thought when buying almost everything is eBay, whether that's Tissues, Metal, Cars, Wire, Tools, Golf Clubs, ICs etc. I've just checked and I've purchased 1441 items from eBay to date! It's my one stop shop, and I rarely buy from anywhere else.
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Post by steamer5 on Dec 4, 2020 23:40:40 GMT
Hi Roger, re the boiler treatment...I just had a quick look at the link Chris posted.....Looks like TS is the one for you as it would seem to be spec'd for steel. I love the way of figuring out if you a short, just right or over dosed....short the sightglass will be lager coloured, just right bitter ale, too much Guinness!! Its going to be real tough having to open bottles of beer to use as a colour reference, I mean what to do with an open bottle...guess you'll figure that out! They also recommend blowing the boiler down & storing dry if out of service for awhile On the water front...do you have a dehumidifier or as we have just got a condensing clothes drier, both are a great source of soft water
I hope you don't have Elves in your shop those reamers would make great javelins!
Cheers Kerrin
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Gary L
Elder Statesman
Posts: 1,208
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Post by Gary L on Dec 5, 2020 0:13:56 GMT
Hi Malcolm, To be honest I have no idea what the gauge will cope with. If it's a problem, I'll make a longer pipe and put a shallow 'U' bend in it. I don't think this one is long enough. The temperature will only be 166C at the maximum pressure, so I suspect it will be fine. Time will tell! Hi Malcolm beat me to it. There are two issues, one is that in this day and age a pressure gauge not designed for steam could have plastic parts in it which might not like the temperature. The other, which would apply to most gauges, is that thermal expansion of the bourdon tube will give you an inaccurate reading. I would use a siphon tube personally. Regards Paul But isn’t the steam at the same temperature as the water anyway, more or less? Until in the absence of a syphon, it arrives at somewhere cooler (like the inside of the Bourdon tube) where it condenses anyway?? Just asking... Gary
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