Steam Design and Control Questions

TheMechWarrior

I feel like steam is my Achilles heel.
Give me an electrically heated water circuit and I'm happy; take away electricity and give me steam and I start to crumble in fear.

Calling on the SD resident steam gurus that I can think of off the top of my head @grim ; @CothermanDistilling ; @Harry ; @Telluride ; @jacksonbrown and anyone else I might have missed.

I'm planning on purchasing a 200 kg/h (~430,000 BTU or ~125 kW) gas heated steam boiler.

It needs to:

1. Heat a volume to strike temp for my 1500L mash/lauter tun. Strike volume is 760L @ 66°C (151°F), sparge volume 1 of 580L @ 68°C (154°F), sparge volume 2 of 580L @ 70°C (158°F). Control system here needs to accurately control the dose volume and heat and control to a desired setpoint.
2. Heat a small CIP set.
3. Provide for hot water on demand to sinks and taps (very small demand as at present it's a very small foot print).
4. Provide for heat for a still (baine, thermosyphon reboiler etc).

I'm just not sure how best to achieve this!

Ie for the first 3 options via a single insulated 1000L hot water tank with a fill volume controlled by a flow totaliser, and an immersion coil for the steam. Dial up the required temperature and away it goes.

I have no idea what the design circuits look like. My lack of experience in this area has me second guessing design control ideas.

I'm opening up the floor to discussion.

Cheers,
Mech.

jacksonbrown

Not sure how I ended up on that list :)

What's existing?

What flow rate for strike and sparge water?
Is it being recirculated through the mash? (do you need to maintain wort temp?)
Got a P&ID for your CIP set?

The hot water points might be better served separately by gas or electricity 'on demand' boxes rather than running steam or hot water ring mains everywhere (for quite a few reasons).

grim

We are using a stainless u-tube heat exchanger for steam to water heating. It works almost too well. Pretty big, 5" x 48", and fed directly off the steam header by a dedicated 2" main. It is in our utility room, bolted to the wall up near the ceiling. It provides hot water for our entire operation. We have no other hot water heater, no separate on-demand water heater, etc etc. Boiler is a bit more than 15hp, so similarly sized.

There are a number of circuits that are on thermostatic mixers, 3 sinks and a wash down hose station. These fixtures produce unlimited 125f water, I can run everything full open and the temp off the heat exchanger doesn't budge.

Initially we thought it wouldn't keep up at higher flow rates, but based on the performance, I'm pretty sure I could heat unlimited 160f water at around 10gpm.

Because of this, we're going to run a non-thermostat line for filling the mash tun. Then we'll see if we can push the heat exchanger higher, to reduce the amount of steam injection time necessary to bring the mash tun to a boil (minimize blowdown). Our process is very different from yours, as we are gelatinizing corn, and are full grain-in. So we have the luxury of filling to our desired volume and heating, and working temps downward.

HLT is probably the easiest approach, alternatively you could use a heat exchanger but the sizing is going to be critical. Tube in shell or even a plate and frame. The downside here is that your flow rate will be limited by your heat exchanger size and boiler output. Unlike an HLT, where you can pre-heat larger volumes by trading off time.

Temp control of your HLT is simple, even as simple as a PID controller and a solenoid on the input of the steam coil, or even simpler yet with nothing but a thermometer and a globe valve. Flow meters and totalizers will work as well, just make sure they are going to be sized for your anticipated flow rate, and they can handle the temperature. No matter what you are talking about 20-30 minutes to fill and heat those volumes, so well within the realm of realistic manual control.