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Steam Pressure for Brewhouse Kettle - HELP!

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  • Steam Pressure for Brewhouse Kettle - HELP!

    Hey everyone, would really appreciate some help here.

    We have a Premier Stainless 2-vessel brewhouse. Kettle is rated at 1 bar working pressure. We have a coil-type boiler that generates steam at about 10 bar, and we then send the steam through a pressure reducing station to bring it down to 1 bar for our kettle jackets. We haven't been able to achieve a proper vigorous/rolling boil. Been doing water brews this past week and at best we've seen some bubbling, but nothing that I would refer to as an acceptable boil.

    The kettle RTD shows a maximum temperature of 99 degrees C, we can't seem to cross this no matter how long we run the boiler for.

    Our steam guys insist that we will never be able to get to a boil with 1 bar of steam pressure, but to me that makes no sense since I've seen low pressure (15 psi) Sussman boilers achieve a really vigorous boil with similar kettles (ours is a 20 hl kettle with 2 jackets). Not to mention, there are hundreds and hundreds of similar installations where breweries boil wort with steam at 1 bar.

    Our boiler is not undersized...it's sized at 850 kg/hour, whereas we only really need 350 kg/hour.

    Any idea why our steam guys insist that we increase our steam pressure? The jackets are rated at 1 bar so I don't want to start sending steam at 3 bar into the jackets.

    Does this have anything to do with bar(g) versus bar(a)?

    FYI, the traps are working fine. And the HLT heats well...but then again, we're not trying to boil the water in the HLT.

    Appreciate your help. Thanks!

  • #2
    Flow Rates

    You can do all kinds of heating and boiling at 10 PSIG if you have the horsepower and flow rates to back it up.
    You are correct to raise questions.
    When you say " Steam guys " did they Engineer and install the piping and associated system?
    Given all of your system parameters a Steam Engineer from Spirax Sarco could likely help you determine where the problem lies.
    If you have a 100 PSI boiler it sound like you are starving you load.
    Do you have a guage on the outlet of the regulator that is telling you the actual pressure in PSIG you are putting to your load?
    Is the line sized correct and is the regulator sized for the flow rate you need in BTU/hr?
    Warren Turner
    Industrial Engineering Technician
    HVACR-Electrical Systems Specialist
    Moab Brewery
    The Thought Police are Attempting to Suppress Free Speech and Sugar coat everything. This is both Cowardice and Treason given to their own kind.

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    • #3
      1 bar should be lots if your jacket area is sufficient. according to my steam table, at 15.3psig the steam temp is 250F.

      do you have an air vent? it is a little bimetalic valve that closes when the temperature goes up. it lets the air bleed out of the dimple jacket. If there is a large air pocket in the jacket, it effectively reduces the heating area. check out the spirax saarco website which has comprehensive manuals for this stuff.

      from a spirax saarco document:

      Effect of Air on Steam Temperature

      When air and other gases enter the steam system, they consume part of the volume that steam would otherwise occupy. The temperature of the air/steam mixture falls below that of pure steam. Figure 6-1 explains the effect of air in steam lines. Table 6-1 and Chart 6-1 show the various temperature reductions caused by air at various percentages and pressures.


      Effect of Air on Heat Transfer
      The normal flow of steam toward the heat exchanger surface carries air and other gases with it. Since they do not condense and drain by gravity, these non-condens- able gases set up a barrier between the steam and the heat exchanger surface. The excellent insulating properties of air reduce heat transfer. In fact, under certain conditions as little as ^ of 1% by volume of air in steam can reduce heat transfer efficiency by 50% (Fig. 7-1).
      When non-condensable gases (primarily air) continue to accumulate and are not removed, they may gradually fill the heat exchanger with gases and stop the flow of steam altogether. The unit is then
      “air bound.”

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