My Steam Generator

grim

You would need a different style valve to accomplish that. A standard relief valve, once tripped, won't close until it gets several PSI below the specified point, which would create quite a bit of wavering at best, and at worst might not actually ever close again (if your element can generate enough steam to keep an undersized relief valve above the closing point).

Also, by releasing steam atmospheric, you've expended the energy to create it, only to waste the energy and the water.

Controlling the element really is the most elegant approach, you not only control to the setpoint, but inherent in this is another safety, once you over temp and exceed the implied pressure, the element will get no power. Having a system with only one safety, and an element that is always on, is a very scary proposition. What happens if the PRV fails?

Telluride

@bachman i would not use the dragon water lines for anything but the water feed line into the reservoir, the feed line and equilibrium line from the reservoir to the boiler should be copper or stainless.

cunnyfunt

I was assuming that you could safely maintain consistent pressure using a lower wattage element by doing it this way.

Element always on >Adjustable pressure relief valve/gauge > PID set to upper pressure limit > Higher rated blow off valve.

I am really excited about this project. Doing 200L+ mashes, ferment on the grain, is now very achievable.

I dont mess with my own safety. Telluride's system scares me way less than many of the flimsy aluminum pressure cookers/canners I have used over the years. I have blown my fair share of blow off valves using too much heat and some of these pressure cookers dont even come with a blow off.

grim

Depending in the size of your output plumbing, any restrictions in the flow path, and the depth of your tank, it's plausible that you never even get near your set point, especially if you have no valving on the output piping.

5500w into 200l is still roughly 3 hours from 20 to 100c.

cunnyfunt

Thanks again @grim. I'm still thinking on a wrong level. It's not about maintaining a set pressure. Check.

bachman

@telluride, thanks for the heads up. A little way up in one of your posts, I think you stated that your system has 1 gallon on water, that gallon is in the well and does not include the reservoir, is this correct? Another question, what is the water level above the element?

Telluride

@bachman There is a couple inches of water above the element, i would say there is 2 to 2.5 liters total of water in the entire system.

bachman

@telluride If I put a manifold on top of the well could I run the equalization line from the manifold to the reserved tank

cunnyfunt

Put an order into my StillDragon guy to make a Telluride generator. Im pretty excited. This system will add a whole new level to what I want to achieve. 200L + mashes, ferment on the grain. I love this community. I wont even sue if I burn myself:P

bachman

I think this set up is way nicer than the old keg steam generator, with the level switch it is safer. I thinker you will be able to conserve some water, instead of just putting 12 gallons in the keg and letting her go.

punkin

@cunnyfunt said: Put an order into my StillDragon guy to make a Telluride generator. Im pretty excited. This system will add a whole new level to what I want to achieve. 200L + mashes, ferment on the grain. I love this community. I wont even sue if I burn myself:P

Aaaahh i wondered what all that stuff was for. Looking forward to the pics and results. I put a golf towel in for you, i wasn't sure if i had given you one or not.

cunnyfunt

Ha thanks punkin. You are efficiently awesome..

TheMechWarrior

Here's a version I've just drawn up using SD stainless components for minimal welding work:

• 1 x SD RIMS tube
• 1 x SD 2" x 2" x 2" TC tee
• 1 x SD 2" x 4" TC pipe extension
• 1 x SD Element Guard Kit
• 1 x SD Element
• 6 x SD TC clamps

TheMechWarrior

The only "custom" work here is you'll need 4 x 2" end caps modified. I've just noticed SD already have a number of 2" caps with a choice of 3/4", 1/2" and 1" BSP, that would allow you to screw on a threaded male cross, tee or 1/4" reducer. I'll redraw this as described, now all stainless components are available from the Still Dragon store :D With the right fittings there's no need for any welding to build the "Steam Dragon".

Lloyd

And "Steam Dragon" it is. Naming bragging rights go to @TheMechWarrior.

Let me know if you need any parts modified.

TheMechWarrior

Thanks @Lloyd, I believe naming rights go to @Cambo on page 2 of this thread ;)

Lloyd

Oops, step aside @TheMechWarrior and let @Cambo step to center stage to accept the much coveted Bragging-Rights award.
Envelope please and drum roll...

Yes, bragging rights (according to our fine panel of honorable judges on page two) does in fact go to @Cambo. Well done!

grim

TMW - on the sensor tube, instead of a 2x2x2 tee and an extension, why not use two tees. The top tee will hold the float for the primary level control, and the bottom tee will hold a reverse float for the low water cutoff?

TheMechWarrior

@grim I like the idea of the second tier of safety with respect to changing out the 2" x 4" with the tee. There are other safety concerns I have that I wish to address tomorrow.

grim

Why the valve on the output? Why not control steam output via the element control?

FullySilenced

Low limit will not be safe at the bottom. As the element would be fully exposed by that time. Tees. Need to be stacked a special lelength tube may be required

TheMechWarrior

Thanks FS,

Version 3 of the drawing is now up yet still incomplete.
I'd like to see a check-valve on the water supply to protect it from the steam side.

I've opted to utilise all standard pre-existing Still Dragon modular components, anyone handy with some tools will be able to build it cheaper out of copper etc.

I've increased the steam generator diameter to 4" as I really didn't like the vapour velocities being generated. I'll follow this up with checks against a number different element wattages on the morrow.

I've now added a 305mm/12" heating element to the diagram so you can see where the top sits compared to the lowest level.

Missing control logic and no explanations given.

@grim, I haven't tackled the control logic yet; we have 2 major control loops to manage. Firstly steam supply and secondly stripping column vapour outlet temp/pot ale output temp. I suspect this will be a cascade control system between the 2 systems.
Someone else I'm hoping will chip in here, instrumentation & control is outside my area of expertise.

DocPorter

I would think you would want a little more height above the liquid level to boil the water.

Also a pressure transmitter controlling the element would be nice (instead of the temperature transmitter). Or at least a high pressure switch to shut everything down on high pressure. Steam boilers typically operate on pressure rather than temperature, because pressure is what's most dangerous. Although both is better. The relief valve should be the last line of defense. I would pipe the discharge to the floor.

I would also put a globe or gate valve on the steam out line (with a PI downstream). These would keep a mild amount of pressure (~10 psi) on the steam generator, or else you'd get surges every time the element clicks on/off.

Definitely a good idea to have a check valve on the water inlet.

Also could change the bottom elbow to a tee to allow for condensate return (in a closed loop system)

Also, not to be nit picky but:

"LSL" should be an "LT" with an output of "LAL" & "LAH"

"TT" should not have a box. It should go to a "TIC" in a box. Which then goes to the element (if controlling on/off by temp)

The "PRV" should be "PSV". PRV = Pressure Regulating Valve, PSV = Pressure Safety Valve

Manofconstantsorrow

@DocPorter said:

The "PRV" should be "PSV". PRV = Pressure Regulating Valve, PSV = Pressure Safety Valve

PRV is the correct term of use here as it stands for Pressure Relief Valve IMHO.

grim

Within the boiler the temperature and pressure are directly related, if you know one, you know the other. Measuring pressure will be significantly more expensive and require more specialized equipment. Accurate low pressure transducers are very expensive in comparison to accurate thermometers.

0psig - 212f

2psig - 218.5f

4psig - 224.4f

6psig - 229.8f

8psig - 234.6f

10psig - 239f

I would strongly strongly strongly argue that you need no restriction valve on the output, and putting one there is asking for trouble. Using a standard SSR controller, you can dial the steam generation volume through the power input, the element should never turn off. Controlling steam output through the ssr controller is vastly superior to a valve.

TheMechWarrior

Great input team! Sounds like DocPorter may have seen a P&ID or two; that's going to be helpful, cheers. The PT (together with a PAH interlock) was on the plans for this mornings update, along with a couple of other safety improvements inlcuding the isolations and drains. Also included with todays update will be a series of pressure calcs.

grim

Check valve was a great suggestion, I missed that on the first pass.

I don't understand why you need two feeder solenoids.

Also, I suspect you will need to custom sized TC spools, based on the drawing above. No way you get perfect line-up horizontally and vertically. I actually think the copper line approach is more elegant of a design, lower cost, and fewer failure points.

DocPorter

This is going to be great! I think it's the perfect blend of simplicity and safety!

I look at and create P&IDs every day at work, so I'm full of useless symbology and terminology...

Grim - You are correct. Using an SSR to vary the wattage is superior to the on/off method I had in my head. Also using a TT will be just as good as using a PT (and much cheaper as you mentioned). However, I disagree and believe a valve on the discharge would be useful. This allows you to put back-pressure on the generator.

Let's say you have a set point of 230°F (6 PSIG). If you're system only has a maximum pressure drop of 2 PSI (maybe direct injecting into 4.5ft of water open to the atm) then the element will be on 100% of the time. As the level switch turns on/off to add cold water to the reservoir the temperature (and thus the pressure) will surge up/down.

Now let's say you have the same system at the same set point of 230°F (6 PSIG). But this time you have a gate valve which you can close a little to put some back pressure on the generator. Now you can put 6 PSI back-pressure on the system and the element can swing up/down to compensate for the cold water addition.

In summary I think adding a gate/globe valve on the steam outlet would be a good way to smooth out the steam delivery.

grim

I suspect the level control cylinder will act as a tempering tank for the make up water.

The primary level control should only be based on a single float valve, this will cause the solenoid to likely add water in short small bursts. I suspect only a few mL will be necessary to trip the reed switch each time. I don't envision a situation where a large slug of water would be added.

I now understand the second solenoid valve, it will cut the water supply in a high water situation if triggered by the upper float. Problem with this design is if the primary float/solenoid fails, the high level cutoff becomes the primary, and the system doesn't shut down.

TheMechWarrior

The "off-the-shelf" build model will be gone in today's update folks. While it sounded like a good idea initially; custom solutions are required for this build. You'll also see a great reduction in the number of joins and a shift away from TC fittings to flange. Safety is my number one focus, cost is second, modular construction is no longer a consideration. While cost is not my highest concern it's most certainly up there, you'll notice I've not used a level transmitter, tempting as it might be in preference for 3 x $5 level switches. Reliability will determine the ultimate destiny of these switches, the same can be said of the solenoid valves. The reason for the 2 will covered in today's update.

@DocPorter I think you're leaning towards a Pressure Control Valve or Pressure Regulating Valve for constant pressure supply? PS, the water top up for this system will be preheated.

Today's update will include a brief summary of the failure modes I've considered and the control measures in place to manage them. Together with your input we can make this something safe and to be very proud of.

Why steam Strip? I know there are some out there that still don't understand the benefit of a steam stripper, basically it all comes down to the heat recovery that's possible. Allowing you to preheat the feed coming in using the spent vapour temp and spent pot-ale temp, thus reducing the total energy required to boil your beer/wine. In a standard batch still we put all the energy in required to boil the full volume from the lowest temp to boiling and never recover any of the spent heat.