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Thread: boiler problems

  1. #1
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    boiler problems

    As I am sure you can tell from my previous post "auger problems" I am in the final phase of my brewery set up. It has been a long 4 months, but i am finally ready to brew some beer.

    I just finished the final peice of the puzzle, the gas main and meter and i am ready to boil some wort, or so i thought.

    The system is as follows...

    A 1.3 million btu, low pressure cast iron boiler by weil-mcclean, model LGB-11. It has a 5" header with 5X2" T fittings feeding the brewery. The steam main to the kettle in 2" with 5 elbows in line, it runs approximately 35 feet, and is insulated with 1/2 thick fiberglass insulation. Just before the kettle the main reduces to 1.5" and splits to feed both the side and bottom jackets. The feed manifolds off the steam main are made up of the following, all 1.5" - Y strainer, solenoid, gate valve, "T" with pressure gauge. The kettle inlets are both 1.5"

    The boiler runs with the high pressure cutoff set to 12 psi and the "cut in" restarting the boiler at 9 psi. The boiler manufacturer states that is has a maximum of 15 psi for steam and 50 psi for water.

    When the boiler is firing and running around 10 psi the gauges at the kettle read 6 psi for the side jacket, and 3 psi for the bottom jacket. The side jacket T's off the main first.

    I had the water filled up about 1/4 of the way in a 20bbl kettle, just enough to cover the themocouple,and about half of the side jacket.

    The water heats up to around 200F pretty quickly, then takes a while to get to 208F, and then it stops. It is rippling like it wants to boil but just can't make it happen.

    should I ....

    A. get a new set of controls and run the boiler at a higher pressure until the gauges at the kettle read close to 15psi. This would be against the manufacturers stated limit on the boiler, but not above the 50 psi if it were run as a water boiler.

    B. resize the steam main from the boiler to the kettle, to say 3". By far the most costly and involved option.

    C. Increase the size of the solenoid valves and the kettle mainfold to 2". reducing at the kettle. I believe the a 1.5" solenoid has a 1" port.

    D. Please give me a simple solution so I can make some damn beer.

    Any and all suggestions are appreciated. I am so close to brewing beer I can taste it.

    Thanks again,

    Scott
    Captain Lawrence Brewing Co.
    Pleasantville, NY

  2. #2
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    Your steam source and line sizes are way more than adequate for 20 BBL. Your instrument trains should have two more components: a vacuum relief valve, and an air eliminator. The vacuum relief allows air inside each jacket when the system cools down, the steam condenses, and a vacuum is created. The air eliminator ejects air from the jackets when steam is applied. It should be installed on a leg about 12 inches higher than the highest part of the jacket. This item is critical to full jacket use. You should also have a valve both before and after your instrument train. This would allow you to close the feed to your jackets and see the pressure rise quickly, indicating proper operation. These valves are also useful for instrument maintenance. Clean your strainers, check your solenoids for debris and porper operation. Have you checked your condensate lines and traps for proper operation? Try draining the condensate to the floor to see whether you have condensate backing into your jackets. Although your system should work fine, you may increase the pressure to cut out at 15psi and back in at 12psi. The difference between cut in and cut out is "deadband" and with a 1.3 MBTU/hr boiler, you should have a large enough steam drum to keep the unit from cycling on and off quickly. Two important things to remember: Be careful! Nothing hurts quite like a steam burn. And the other is that your system is relatively simple, and should work without problems. If this sort of thing is beyond your troubleshooting capabilities, call an expert! It's cheaper than your continued downtime and certainly a hospital stay. Besides, a good steam guy should have this up and running in an hour or two. And his assessment of the system will be money well spent. Good luck!

  3. #3
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    I have "y" strainers in line after the kettle jackets, before the steam traps, with drains and I checked the lines for condensate build up and all I got was steam.

    I will defintely put in some valves after the instrument train so that i can check for adaquate pressure before the jackets. Is 6 psi steam adaquate to boil 20 bbl of liquid?

    I appreciate the advice on the vacuum releif valve and the air ejector, however I have never heard of including these in-line before the jackets. Should I include them right before the jackets, after the jackets or some where closer to the kettle. Also is there a brand or manufacturer you can recomend. I am not sure exactly what you mean by vacuum releif and air eliminator.

    As for the air eliminator you recomend having it at least 12 inches above the higest part of the jacket - should I just "t" it off the instrument train after the valves and gauges?

    thanks again.

  4. #4
    Join Date
    Dec 2004
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    Scott,

    I've had this same issue at our B2 site and I did all the upgrades myself..........sorry if this seems long and I most certainly don't want to insult your intelligence. Skip to the end if the middle stuff is boring or you know this already.
    It's like my old Thermodynamics Prof Mr. Deller used to say, "He who understands the theory, but doesn't know the practical application is simply untrained. But he who knows the practical application, and doesn't know the theory, is dangerous!".

    Background:
    We have a 15hp Parker high pressure boiler we set at 80 psi and have an adjustable steam pressure reducing valve in the steam header just ahead of the kettle, mash tun, and hot liquor tank (our mash tun has steam jackets as well, but we haven't needed them). We hired a contractor to run the pipe and get things ready to fire up. The reducing valve put the steam pressure at 12 psi. During our water tests, we were taking a while to get to boil, but we felt we could live with the extra time. Man, were we wrong.

    First, a little explanation in what you are seeing.........

    1.) The pressure drops you are seeing at the jackets is due to the fact that the steam is breaking out to condensate as it passes over the much colder outer skin of the kettle. Water, requiring more energy to heat than air, is basically "drawing" the heat from the steam as it tries to reach an entropic state. The huge differential between steam at 12 psi (244F degrees) and the colder water (58F degrees) makes this heat transfer occur faster. At this point, you are getting a lot of condensate off the jackets with some steam.
    This reduction in pressure is what's placing the load on the boiler, and making it generate more steam. This is normal.
    Remember: Cold liquid in the kettle = lower jacket pressures.

    2.) As the water heats up, say.......to the 208F you are seeing.......the temperature differential is a lot less. Because of this, the heat transfer isn't as fast because the temperatures are so close (one could argue the steam and water phase energy differences from a water - steam state diagram are significant, but hey, this is applied science, right?). The pressure shown on your kettle gages should be increasing to close to nominal pressure. At this point, you're getting a lot less condensate and more steam off the jackets from the steam return lines (if you have steam traps and return lines, that is).
    Remember: Hot liquid in the kettle = higher jacket pressures.

    3.) Water heated in this manner doesn't increase in temperature uniformly over time. If you were to plot a "Temperature vs. Time" graph of the water as it's heating, you'ld see a linear progression at first and then a gradual curve as it plateaus out near boiling. It's easy to dump heat into water to get it hot.........it's harder (takes a lot more energy) to flash it to steam. What you are seeing is a rapid heating, but heat transfer plateaus (flattens) out as we approach boiling, where two separate energy states will co-exist (water-steam).
    Further, the boiling liquid will never get hotter than it's boiling point, so the only thing you get by dumping a LOT of energy in while heating to boil is a faster time to boil. All things being perfect, and you had nothing but time, and perfect insulation, 212F steam will eventually (I said eventually) heat the water to 212F. 250F steam only gets you there faster.
    Remember: All things being perfect, adding more steam heat over 212F reduces the time to boil.

    4.) Heating and boiling water is easy enough, but beer wort boils at a slightly higher temperature (because of the sugar) and is more insulative, so it will take a snick longer to heat as well. Fortunately, we load to the kettle with warm wort anyway in the 160F - 170F range, so your not bringing it up from a cold condition at least. When wort boils, the sugar wort solution holds the bubbles better than water (there's whole write-ups on surface tension and bubble nucleation), so a wort boil looks more foamy, and possibley more violent, than a water only boil.
    This is where we had our problems.........the water boil was fine (sort of.......we had similar results as you) but the wort boil was pretty limp........sort of a shimmer around the periphery except some rolling at one location. My friend from another Brewery (name withheld) mentioned that sometimes all he gets is a hard shimmer at the edges in his 20 Bbl which uses a low pressure boiler as well.
    Remember: If you are having problems getting a water boil, a wort boil will be even tougher.

    5.) Steam increases in temperature as it's pressure increases. When you increase the pressure and temperature above 212F and atmospheric pressure (0 psig), it's referred to as supersaturated steam. The idea is to get as much heat to the liquid as possible to ensure a proper boil AND reduce your time waiting for it to get there. Higher pressures/temperatures also produce a more uniform boil; meaning that more of the kettle skin inside is transferring heat uniformly above the boiling temperature.........there are no "cold spots" as it were, where skin temperature are not above boiling.
    Remember: Higher steam delivery pressure to the kettle = hotter steam = faster and more robust boil.

    Soooooo..............what are you seeing?
    My thought is that your delivery pressure is too low to overcome the heat losses of the steam jackets and piping. I'll support this here............

    1.) You're only getting a shimmer of a boil with water. This will not be good with wort.

    2.) Your boiler line pressure is between 9 and 12 psi. This equates to a range in temperature between 237F and 244F, but you're probably running in the middle at 10 psi / 239F.

    3.) Your boiler is probably generating.......what......somewhere around 950 - 1050 cu-ft of steam? I would think you have enough steam volume.

    4.) You're running solenoid valves on a kettle? Why not globe valves? are you using it to heat strike water and want it to close? Steam does not like systems being "slammed" shut on them as a normal solenoid would do and can make a wild racket in the lines. We used a slow opening solenoid for our HLT so we can operate it hands off. It takes about a minute or two to fully open.

    5.) The pressure drops at the jackets you are seeing with cold liquid in the kettle are normal.


    Just my humble recommendation...........remember, this is just to get around changing out pipes. My thought is that it's a culmination of a few things.

    1.) Try to get very close to 15 psi in the steam main to the kettle. My favorite shopping place (McMaster-Carr) has pressure relief valves that can be calibrated in 1 psi increments. Unfortunately, because you are already close to the uppermost operating limt of the boiler, to get a true 15 psi in the line, you'll probably have to change the safety valve out to 17 psi or so, which isn't THE safest thing to do. 14 psi will do.
    Also, when you approach a relief valve's "burp pressure", it will begin to lift slightly and bypass steam until the line pressure drops below this burp pressure. Read the M-C on-line documentation for valve selection well before buying.
    Our boiler has a 100 psi safety relief valve, but to get a true 15 psi to the kettle I replaced the reduced line 15 psi relief valve with a 20 psi unit. A snick risky but we discussed it for a while first.

    2.) Your kettle, if built by a reputable manufacturer, was hydro'd to 21 psi. You have a little hidden room there to run it over 14.7 psi into 15 psi with a very good safety margin. Heck.......your gages probably aren't that accurate anyway.

    3.) In a perfect world, your water should theoretically be boiling away as the system sits now. However, there are a lot of heat transfer losses in a steam system if it's left un-insulated. If your lower steam panel/jacket is un-insulated, then insulating it will direct the heat more into the kettle. Specific Mechanical incprorated this upgrade in their steam kettles a while back, but ours is un-insulated. We just muscle through it. Write me direct if you want to persue this.....I did some research a while ago. Insulating the main from the boiler to the kettle will help as well.

    4.) Definitely check the porting on that solenoid if it's between the steam main and the kettle. Hopefully, it was a full port. If it isn't, replace it with a manual globe valve. A 1" port is too small.

    5.) You mentioned the 3" pipe...........is the "Steam Out" port on the kettle 3" Dia? Boiler manufacturers place the steam out port at the size they recommend the pipe to be to move the volume of steam. Our Parker outlet is only 1" Dia.........but then again it's max capability is 100 psi and we run at 80. If you reduced to 2" then with a 1" port, it could be a little constraining. It really depends on how far the boiler is form the kettle.

    Scott, sorry for the "Steam 101", but consider some of what I wrote here and look at your application. Since I can't see the installation, I am guessing at the obvious. Sending me some digital photos of the steam main from the boiler to kettle would help greatly. Gitchegumee's got some great advise as well.

    Drop me a line if you want to discuss this more or have some digital pics.

    Good luck, and keep the faith! You're almost there. Building a Brewery is one thing, but the big pain in the hopback is troubleshooting it once it's operational.........and you find out what does work and doesn't.

  5. #5
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    Brian, thanks for the in depth responce I have re-read it a few times already trying to make sure it all sinks in.

    I did a little more fiddling with the boiler today, as well as swapping out one of the solenoids for a straight run of pipe. the results are as follows...

    With both solenoids in line, and both lines plugged , the gauges were reading boiler pressure, which was around 12 psi.

    So i know that the boiler is delivering the pressure to the kettle, what I was then thinking was that the volume of steam was being restricted, as you both mentioned, by the solenoid valve.

    With the solenoid removed from the side jacket manifold, and the gate valve opened fully, the pressure was reading 6 - 9 psi, while the plugged bottom steam manifold was reading boiler pressure. The 6-9 psi is about 3 psi below boiler pressure at a given point in time. The boiler was shutting down at 12 psi and turning on at 9 psi.

    This was not very encouraging, and the boil still sucked.

    So I cranked down the presurtrol, which controls the upper limit, as far as it would go,this got he boiler to shut down at 15 psi. I then cranked the cut-in to restart the boiler at 12 psi.( it is designed to restart at 9 psi)

    This got the pressure at both the bottom and the side jackets up to between 9 and 12 psi depending on the boiler pressure.

    The boil is not what i would consider a rolling boil but it is at least bubbling as long as I keep the kettle door shut. The boiler is short cycling, turning on for about two minutes getting up to pressure then shutting down for a few minutes until the pressure drops. I am thinking about removing a few of the burners so that it will run more consistantly rather than super hot for a few minutes.

    I am also considering replacing the pressure relief valve with a 17 psi one. Unless someone wants to talk me out of it. I can't imagine that 2 psi can damage a cast iron boiler. This will allow me to get 15 psi to the kettle jackets with the low end being around 12.

    Also, if anyone has experience using a vacuum relief valve and an air eliminator in their steam set up please let me know. I found some information regarding their use, but they were set up coming directly off the jacket, not on the steam line. I am thinking this could be the final peice of the puzzle?

    I am almost to a boil any additional advice would be appreciated.

    Scott

  6. #6
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    Without an air eliminator, air will stick in your system and cause less steam to see the jackets. I forget the numbers here, but on a 1 bar boiler I seem to remember a 40% drop in heat transfer without an air eliminator. And what happens to steam when it condenses? It loses volume. Hence the vacuum breakers on each jacket to allow air in when the steam cools. Both of these components should be in your steam supply line. Do NOT change any safety relief to above 15 psi. NO, NO, NO. This puts your boiler, and your jacketed tanks, into the class of a high pressure steam boiler. Most states require a licensed high pressure steam boiler operator to be on site at all times that a high pressure steam boiler is used. Something you don't want. Besides, most jacketed tank manufacturers are NOT ASME certified to even make jackets that run above 1 bar = 15 psi steam. And you don't need the extra pressure. You should have a great rolling boil with what you have. And any small restriction (read here solenoid valve) is only a minor choke consideration. Gases like steam tend to pick up velocity to make up volume for smaller passages and recover from restrictions well. And keep a solenoid valve as your main steam shutoff to each jacket from a control panel. They can be chosen to be perfectly suited for this application. Do not remove burners from your boiler. This is not your problem. Who put your steam system in? In my humble opinion, you should have a steam professional come in to see why you aren't getting the great boil you should. And again, the advice and assessment are worth the price. You're almost there. Keep the faith! Good luck & cheers!

  7. #7
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    Dec 2004
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    I'm with Gitchegumee with regards to changing out that valve. After seeing the photos you sent, the valve you'ld have to change is on the boiler itself, and even 17 psi has a pretty explosive force if there's a failure. To clarify, the relief valve I changed was after the pressure reducing valve in our steam supply to the kettle. The boiler is totally protected within its operating parameters.

    Gitch,
    The recommendation of an air elimator is very interesting. I discussed our installation with 2 boiler contractors prior to having one of them perform the overall installation of plumbing, valves, and traps. Further, here in the Northwest I haven't seen any on other Brewery installations, which is also interesting. It might be a regional industry paradigm that could also be an error on our side.

    I have heard a brewer or two complain about the quality of their boil on steam systems. This might be a good avenue of research up here.

    With regards to the pressure and 12 vs. 15 psi. My chips are still on the side that 12 is too low. When I discussed this exact topic with the folks at Specific Mechanical a little while ago, they recommended 13 as their lowest, and that anything lower won't get you there. HOWEVER, their preferred installation drawings don't show these air eliminators, and maybe there's a reckoning as to why the "more is better" approach is recommended.
    Amazingly, the vacuum breakers aren't installed up here either.

    Good discussion..........with many ideas to try. Scott, I hope your installers are on their game and can recommend some solutions. It is frustrating to tweek so many things to get better results and still see little return, but you'll get there, my friend.

  8. #8
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    Gitch,

    I have done a little research online looking for examples of the air eliminator and the vacuum breaker. I found one schematic that shows a kettle with the air eliminator and the vacuum breaker installed in the upper most point of the kettle jacket, as far away from the steam inlet as possible.

    I am just a little confused with the operation of these two components, it seems to me that they are working against each other. The vacuum breaker is letting air in and the air eliminator is letting air out.

    Can you clarify their mode of operation a little more. Will they still do the job if they are installed on the steam main as opposed to the jacket?

    Scott

  9. #9
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    Get your pressure controler running right up to the ragged edge...you want that boiler cycling at 14 and 15 psi. at 15 psi steam is only 250 degrees...the closer you get to a boil the less efficient the heat transfer.

    Honeywell makes a boiler pressure control for about $40 that will run up to 15, and has and adjustment for hysteresis (the difference between the cut in and the cut out) that can be dialed down to 1 psi of difference.

    I'm not sure if you've done this, but get full port solenoid valves, or get rid of them alltogether. the restriction will slow you down.



    also, who made your kettle...is it new? if not, have you cleaned the jackets?


    cheers

  10. #10
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    Today was a good day...I boiled a full kettle of water! I cranked up the pressure on the boiler to go right up to the max, and the pressure releif valve is relaesing a small amount of steam. The cut is cranking the boiler back up at 12 psi. I am going to swap it out for one that is designed to cut back in at a higher pressure. The one i am using now is supposed to have a max cut in of 9 psi, but i really cranked it down.

    Thanks everyone for your help on the matter. I avoided turning my boiler into a time bomb and swapping out pipes.

    thanks again,

    Scott

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