Actuated steam valve recommendation

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RPierce
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Actuated steam valve recommendation

Post by RPierce »

I'm trying to add instrumentation and industrial automation to a mash tun that will be used for 500 gallon batches. It is heated via a steam jacket. There are two steam inlets to the jacket, each via 3/4" pipe. I believe the steam from the boiler is set for 12 PSI max. Steam flow is currently controlled by a pair of manually operated gate valves. I would like to replace them with actuated steam valves such that I can control the steam flow via PID so that the mash tun can maintain a constant temperature according to their mash schedule.

As my previous experience is in automating home brewing, I don't have any experience with steam! I'm trying to find some kind of valve that is designed for steam and can be proportionally controlled. The interface can't be proprietary, lock me into using proprietary software, etc. 0-10V or 4-20 mA analog, for example, would be fine, as would be any digital protocol where I could get electrical and protocol level specs.

Thanks!
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Re: Actuated steam valve recommendation

Post by HDNB »

if you find something please post it, i'd like to learn about finer control on a steam jacket still.

I'm not sure why you would control on a mash tun with that size feed and pressure though. can you elaborate on how the tun works with the manual valves?

i mean: I'm curious. 500 gallons of mash would take an enormous amount of heat and feeding 12psi on a couple 3/4" lines is going to take hours and hours to get corn anywhere near gelling temps. I would think you'd be going balls out, full throttle the whole time...and then 10 or 15 hours later when you finally get to like 90*C, you would go into full cooling mode to get back to mashing temps, and then fuller cooling mode to get to pitching temperatures.

how many square feet of steam jacket are you using? are you agitating or circulating the wort? so many questions are rattling around me brain...time to temperature?

if you up the feed to a 1" you could manifold the inputs in parallel and then only use one valve...'cause i'm betting when you find them they are going to be wildly expensive.for that matter, my steam guy sez that one in/out works fine anyway... the steam gets to the cooler temperatures anyway.
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RPierce
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Re: Actuated steam valve recommendation

Post by RPierce »

At this point, I'm only focusing on steam for the mash tun, not the stills.

The steam headers themselves are substantially larger than 3/4". They get reduced down to 3/4" before entering the equipment. The 500 gallon stripping still and the smaller pot still each have a single 3/4" gate valve at their inputs. The mash tun has two gate valves for its steam jacket inputs. I'm not entirely sure why; e.g. if it heats a separate bottom and top jacket, or if both are parallel inputs to the same jacket. I only see one condensate line coming out.

I think the mash tun can hold substantially more than 500 gallons, but we're only doing 500 gallon batches as that's all the stripping still can hold. The mash tun originally came from a brewery, but at some point the false bottom was removed when it found a new home at a different distillery before coming to us. It does have an agitator; we're not recirculating any wort.

This is a brand new DSP; none of the equipment has been used at this location before. So I don't know how long it will take to heat. I'm hoping that this isn't a 10 to 15 hour process!

From a control systems standpoint, I'm assuming we're going balls out full throttle at first, however I'd like to be able to ramp the steam down as we approach the target temperature. From there, I'd like to use PID to control the steam flow to maintain the target temperature for the duration of the mash cycle.

Being a beer person, I just assumed that the mash would either be single temp, or discrete increasing steps. There's definitely no cooling set up for this, so I probably should ask if they're going to need to go to a higher temperature and let it fall.

That's a good point about valve cost. I don't know if these are both parallel inputs to the same steam jacket, or if there are two different jackets. I can look into using a larger header and valve and having it feed both inputs. Alternately, if they're both the same, then it might be possible to use a cheaper solenoid valve for one input and an actuated proportional valve for the other. I'd open the solenoid only when doing a major temperature increase and close it once we were approaching the target temperature. This assumes I'd need no more than half of the steam to maintain a steady temperature, which would be provided by the actuated valve.
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Re: Actuated steam valve recommendation

Post by RedwoodHillBilly »

A thought. Depending on the thermal mass of the mash tun compared to the steam power input, you may be able to use a long period PWM (i.e. 100 sec. period, 1 sec. duty cycle resolution) using a solenoid valve. This would still give you proportional control for the PID loop but without of the cost of a true proportional valve.
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acfixer69
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Re: Actuated steam valve recommendation

Post by acfixer69 »

This is what is typically used in equipment of commercial size
http://www.spiraxsarco.com/global/us/Pr ... valves.pdf" onclick="window.open(this.href);return false;" rel="nofollow

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HDNB
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Re: Actuated steam valve recommendation

Post by HDNB »

please allow a couple comments that may help simplify your set up and costs:

-you want to fill your tun to over the steam jacket, or the grain will ccok onto the side of the tun and it's a bitch to clean. also making more wort than the still holds is a good thing...make 4 charges if you can!
-you need to go from cold to hot, target temp as fast as you can, so also having the steam jacket submerged will increase the thermal transfer area and increase the efficiency.
-the agitator is a must, the heat does not move through mash fast enough to strip the heat from the jackets with any efficiency. what i mean is the wort will boil for 1/4" from the jacket and float to the top, and the bottom and centre of the mash will stay cold if it is not continuously stirred.
-once you have reached the "target temp" (gelatinization) you will have no problem holding heat in a 500ghallon, the mass is so large that you will be lucky if it cools naturally 1*C an hour...your problem will be one of cooling, not holding heat. (once gelatinized, it does not need more time/heat)
-you also want to cool as fast as possible, or you will experience battles with PH crash and with infection.
-if you only have one condensate out, the inputs are parallel. The steam will heat from one input almost exactly as fast as from two...my steam guy showed me the math on this, but it was over my head.

there is a calculator on the parent site for heat up times that is surprisingly accurate (Rad's Calcs) but it does not take into account thermal transfer area of steam jacket and agitation/non-agitation.

assuming you are using low pressure steam (sub 15PSI), and it cycles between say 10 and 14psi, and you want to heat 500 gallons though 64 square feet of steam jacket from 20*C to 90*C with an agitator running the whole time, plan on 5 hours. take away the agitator plan on 24. (or if you lower pressure, or have a smaller jacket)

i can tell you are a beer guy...here's what a mash cycle looks like for distilling:

once you reach gelling, you will be able to hold the heat for 90 minutes easy with no heat so HTL enzymes can do their thing. just shut off the steam. (and you want to shut down steam or the enzymes will become denatured as they get stirred past the jacket)
once gelled, and liquified, you need to drop to mash temp 65* asap. natural cooling on this mass would be 24+ hours and your PH will go low and bacteria will be having a heyday, so forced cooling is a must.
cooling to your next target at 65* you need to add GL enzyme or malt....which will do their job substantially in 90 minutes as well, but you may choose an overnight (12 hour) rest to get total conversion before pitching.
if you choose overnight, you will still need to force cool to pitching temps...500 gallons at 65*C will still be over 50* 12 hours later....so you may as well just force cool it on the first day, pitch the yeast, call it a day and go home. planned to perfection you can do this all in an 8 hour day if you have enough steam jacket, pressure and agitation.

hope that saves you some time, experiments and money. and if that isn't all reality ^^^, come back here and expose me as a fraud.

now as a mod...i wrote all this so i ain't gonna delete it...because we are discussing a mash tun, not a still. Obviously with gear this size you are going pro, so please post your license number in the sig line, so we can discuss the larger still at some point. and fire up some pictures for us!!!
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DeepSouth
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Re: Actuated steam valve recommendation

Post by DeepSouth »

I personally think you'd be throwing a bunch of money down the drain for no reason trying to automate a mash tun. Just turn the valve wide open until you reach your target temperature, then turn the valve off. As was said earlier, you'll have no trouble whatsoever of the tank holding it's temperature, there won't be any throttling required. In addition, how do you plan to cool the mash tun, and what size is your steam boiler?

-Source, someone who runs a 300 gallon steam heated mash tun daily and performed all of his steam system installation :D
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HDNB
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Re: Actuated steam valve recommendation

Post by HDNB »

Deepsouth, can you post a pic of your agitator? how long does it take your 300gallons to hit gel temps?
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Re: Actuated steam valve recommendation

Post by DeepSouth »

Image
I can usually heat from ambient 70 F to 200 F for cooking corn in about 1-1.5 hours. My boiler is 700,000 BTU/hr, and my pot is 300 gallons. Even if I'm running the still at the same time, it still takes about the same time to heat up.
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Re: Actuated steam valve recommendation

Post by HDNB »

ahh.. i was confused, i thought you used the open top tun with the single jacket for a mash cooker. (from your other photos in your other build out thread)
I can see the closed top and full jacket being much faster than the single sided jacket.

OP, sorry for asking questions of deep south on your thread. His build is a great resource for you and can be found at:

http://homedistiller.org/forum/viewtopi ... 75&t=58505

i'll stop now.

as for your heat up times, if deep's 300 gallons takes 1.5 hours using 64sq ft of jacket at 12 psi...and i know a guy that uses 16 sq ft on a 300 gallon insulated tank...it takes about 2.5 hour to heat up at 12 psi...you can use some guess work to figger your heat up on 500 gallons if you measure your jacket.
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Re: Actuated steam valve recommendation

Post by DeepSouth »

It's not really the steam jacket pressure that's the driver here. The important thing is the size of your boiler. If you had a 100,000 Btu/hr steam boiler vs a 300,000 btu/hr steam boiler and they both operated between 10 and 12 psi and the inlet pipe and steam jackets were identical, your bigger boiler would heat your tank three times as fast. A good rule of thumb for steam heated stills is that you need 100,000 BTU/hr of steam boiler capacity for every 100 gallons of mash you are heating to get things up to temp on the order of 1 hour.

So a 500 gallon still with only a 250,000 Btu/hr boiler will at best take you 2 hours to heat up.

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RPierce
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Re: Actuated steam valve recommendation

Post by RPierce »

You've got me pegged accurately as a hobbyist beer brewer.... To be clear, I'm not the distiller for this operation, just an electronics and control systems person. I'm realizing my mistake now. Volume to surface area. Volume is proportional to the cube of the size, while surface area is proportional to the square of the size. My poor little 5 or 10 gallon beer mashes have a far greater surface area to volume ratio than a 500 gallon whiskey mash, so while I'm worried about adding heat into my beer mash to counteract heat loss and maintain a steady mash temperature, their whiskey mash isn't going to have that problem at all.

While I did consider controlling the duty cycle of the steam, I'd be concerned about cycling it that much. Also, I'm thinking everyone here is correct; heat isn't my problem, and a simple solenoid steam valve that will shut off automatically when the target temperature is reached, or maybe a little before if there is overshoot, is all I'll need. Now, when I get to still control systems, I'll want to revisit the idea of an actuated pressure reducing valve.

About the mash tun: I was entirely mistaken. There is only one steam jacket inlet. What we were told was a second steam inlet was really the condensate, and what we were told was the condensate was actually a piece of pipe welded to the bottom that wasn't connected to anything but appears to be structural for supporting an agitator. This was originally used for beer and had a false bottom. Another distiller acquired it and cut out the false bottom. Working capacity is 800 gallons, and when filled up to the upper manway, it holds 1000 gallons.

I took my control box for my beer setup to the distillery yesterday, put a digital probe in one of the lower ports, and let another probe hang from a cable in the top. We filled it up with 500 gallons of water to test it. I can see exactly what people are saying about the importance of the agitator. With the agitator running, we were seeing the two thermometers agree within 0.1 F. Without the agitator, the values diverged, and when turning on the agitator after some time of leaving it off, I could see the very hot water that was around the jacket circulating before everything equalized.

They have a boiler rated at 15 PSI and were running the system at 12 PSI. I believe the boiler is around 750,000 BTU/h. They have the mash tun, a 500 gallon still, and a 150 gallon still. With just the mash tun running, we heated 500 gallons of water (with no grain) at about 48-49 F per hour.

From an automation perspective, I'm considering just controlling a solenoid steam valve, a solenoid for fill water, and the agitator. Inputs would be the temp probe I installed near the base of the mash tun and a meter for the volume of fill water. That way, the distiller can do other things while a program runs that will automatically fill with X gallons of water, turn on the agitator, heat to Y temp, and then shut off the steam.

How do most craft distilleries handle both heating and cooling in the same vessel? I'm now agreeing that cooling is going to be a far bigger problem. I think they're planning on not taking the corn to 90C to gel it, and just doing a single temp mash. Even then, it's going to have to sit overnight before pitching yeast. I'm also thinking that maybe we could mash with 800 gallons, and when finished, dilute with cold water to 1000 gallons before transferring into totes to ferment. That will at least avoid the problem of the mash level being below the steam jacket, and it buys us some cooling.
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Re: Actuated steam valve recommendation

Post by DeepSouth »

I heat and cool using the same external jacket. Out of my steam inlet and condensate returns I have tees and valves. I shut off the condensate return loop, then run cold water in from the bottom of the jacket and out the top.
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Re: Actuated steam valve recommendation

Post by Hank Reardon »

I realize that the thought process was corrected by DS for the controls fellow looking to automate the mashtun. Being said, HD asked about controlling steam on a jacketed still also.

I haven't seen these valves on a still, but have seen them in food processing in 3 different applications, all concerned with overhearing a product.
http://www.processandsteam.com/abpdfs/C ... lValve.pdf" onclick="window.open(this.href);return false;" rel="nofollow

Page 3 has the example of the v-port control valve seat, and you can see how they work. They do offer much more than a standard gate valve, and give precise control within a range.

The first time I saw one was in a processing facility that made masa. The manufacturer of that particular valve was Durco, and the actuator was. Flowserve.
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Re: Actuated steam valve recommendation

Post by RPierce »

I'd wondered if it were possible to circulate cold water through a steam jacket to chill the mash. On one hand, there's probably going to be more than an hour between applying steam and applying cold water, so there would be time for the jacket to get down to the temperature of the mash. But on the other hand, isn't it bad to cold shock metal like that? I'd imagine that metal is going to change dimensions rapidly once a change of temperature is applied, which would stress any welds, cause possible stress cracks, etc. Are there such things as mash tuns specifically designed to handle heating and cooling via the same steam jacket?
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Re: Actuated steam valve recommendation

Post by HDNB »

with experience running the unit a few times i believe you will come to see you are overthinking it.

the steam jacket will cool to the mash temp in minutes, adding cold water too it will definitely move the metal a bit, but i don't think it will cause any major issues as long as you don't have steam in the jacket when you add water...that would cause a vacuum and risk serious damage...make sure you have some quality vacuum breakers on the jackets between the input valve and the condensate trap.

as the temperature gradient narrows (mash approaches steam temp) your temp. gains per hour will slow, but thats ok since the corn needs time to cook anyway.

the idea of 800 gallon cook and then adding 200 gallons after gelling to get back to malt temperatures is valid. exactly what i do, and others too...judging by some recent recipes. You will be surprised that adding 200 gallons won't cool as much as you think though. I can add only about 10% volume VS. your 25% volume add... but i can tell you that adding 10% does almost nothing to lower the temperature by any noticeable amount.

and like deepsouth says, heat up time is affected by boiler BTU size, until you reach the heat transfer limits of the steam jackets and temperature differentials of the mash/steam...my boiler is small in comparison, but limits at 14.5psi when the heat transfer slows due to jacket size and temperature differential. What i'm saying is once the system is at 14.5psi there is no more heat input whether you have a 200k BTU boiler or a 2mm BTU, it is all governed by how fast you can absorb the heat to create vapour, how big the column is to move that vapour through and how well you can cool the vapour back to liquid.

on my system, the small boiler creates far more heat than the column can pass or the condensers can cool...so i end up running with the manual steam valve almost closed once i have reached operating temperature and the boiler is limited out...but I can turn on my mash tun and start running in parallel with the still since i have so much heat, even off the little guy boiler. In fact, i could probably run a couple tuns and the still simultaneously if i had interest/need to.

the 750k BTU gear you have will handle your workload no problem, with room for expansion.
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Re: Actuated steam valve recommendation

Post by WhiskyRichard »

Because you won't have very much cooling, as others have pointed out, it might be easier, and it will certainly be cheaper to use a solenoid or other on/off control, instead of a proportionally controlled valve. Writing a program to control a solenoid will be simpler than for a proportional valve. You can leave the gate valves in series with that, turning them wide open for quick initial heating, and then turned down quite a bit for temperature maintenance. You can tune those valves as a sort of PID tuning of that system, so that you don't overshoot your temperatures, or cycle your solenoid too much. An agitator will be necessary to maintain even temperatures, and to make sure there's not a lot of lag in your temp reading---again, so that you don't have too much 'overshoot' on your temp control loop.

Actually, a better setup might be a bypass line around the current gate valves with the solenoid and a smaller gate valve for tuning control. That way you don't have to buy a solenoid big enough to pass all the steam you'll need for heating, just for the small amount you'd need for temperature maintenance.
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