Steam Systems
Steam is one of the most important scopes of our work for food and beverage. It is also one of the most problematic systems we work on in breweries. Whether it is in a 5 bbl or 200 bbl brewery, we find it has often been designed and installed poorly. Many plant operators do not understand the dynamics in their system. We hear a lot of complaints about bad brewing equipment that can usually be traced back to under performing steam systems. Long boil times, noises, knocking, slow heatups, low boiler pressure, flooding feedwater tanks and blown jackets can all be a symptom of issues in your steam system. Here are some things we do to optimize a steam system.
Get Water Treatment
Water treatment is overlooked in many breweries and distilleries. It’s expensive, but cheaper than replacing your boiler and steam components. The investment you make will not only extend the life, but increase the performance of the system. The PH drops in a boiler, and once corrosion occurs, it not only destroys metal but causes boiler water to carry over into the system. Wet steam is cold steam. The higher the conductivity, ie. rust and solids, the worse the carryover. This is especially true in process boilers, where the demand is not constant and surge loads can carry a lot of water out. Keeping the PH high and oxygen out will keep more water in the boiler, giving you hotter steam, saving time and reducing energy costs. Pick a good treater. I call them Water Nerds, because you have to really love water chemistry to be good at it. Anyone can dump some chemical in a tank and hand you a bill for $600.
They are all in the business of selling chemicals, but qualified water treater with a good treatment plan will minimize chemical use, and they should take ownership of your boiler chemistry. I can’t say they all do, so make sure they understand the requirements of your operation and equipment and provide regular reports that are within the tolerances from the manufacturers. It will take several months of average production for them to figure it out. If they aren’t there regularly and giving you detailed reports, they probably just want to sell chemicals. They should also be at your open inspections, to observe their results. Corrosion doesn’t care about test results.
Keeping your feed water hot is important too. Steam injection from the boiler will preheat the water, usually 180-200F, which lets the boiler recover faster and strips oxygen from the water. There are several chemicals that work adversely in water below 180F as well.
All boilers are not the same, so there is no single model for treatment. Likewise, all consumers are different, so it takes regular monitoring and a good understanding by the treater to get your system dialed in.
Why do you need a condensate receiver?
There is a very good chance you don’t. What does every operator want more than anything? A point of failure of course. That’s all a condensate receiver is to us, and if there isn’t an absolute need, don’t get one.
A closed steam system does several things. It keeps the condensate in the system. It keeps oxygen out of the system. It uses the laws of thermodynamics, and the energy already present in the steam, to send condensate back to the feed water system. A steam system is always pressurized. By keeping the condensate system part of the steam system, the steam pumps the water back. By not allowing the water to sit in a receiver open to atmosphere, Oxygen has no way in. By placing the condensate receiver in the system, the two branches are separated, and now a mechanical pump has to be used to return the condensate to the feed water system. We use either electric pumps or pump traps in explosion proof areas, but either way, air is in contact with hot water and that leads to corrosion.
When we do use condensate receivers, it is because the elevation is too high for the steam pressure to push the condensate back. 1 psi of pressure pushes over 2 feet of head. That means with only 6 psi steam, the condensate can be raised 13’ and fall by gravity back to the boiler room on a low pressure steam system. Running high pressure steam, there is almost no situation where a condensate receiver is required. When we do use them, we have found Fabtek Aero to be superior. They are stainless steel. There is no place for corrosion. Also, on a production floor, they don’t rot from chemicals. When our elevation has to exceed 12’, we will install a receiver, but we try to plan the piping to not need one. One less point of failure, no wiring or air, less maintenance, no oxygen, no system loss. If your contractor tells you there has to be one, they might not understand how steam works.
Traps and Drip Legs
Put them everywhere. Put them on any vertical drop, put them between the boiler and trunks, put them in every cluster. You really can’t provide too many outlets for condensate to leave your steam piping. Wet steam is cold steam. When you hear knocking and the pipes shake, that’s because water expands about 1700 times at 40+MPH when steam hits it. It sounds scary because it is. We had a customer blowup an open steam kettle because of trapped condensate from a failed trap. It had been full of molten ketchup a few minutes before and if someone had been around, it would have been deadly.
A steam trap is a break between the steam and condensate. As it fills, it overcomes a float mechanism or a thermostatic device. When it opens, the steam on the top end pushes the condensate out. Then it closes and fills again. This automatic gate cycles constantly, keeping the system hot and dry when used in the right places. They should be at the end of every trunk, every branch, on every outlet, and we usually send one back from the boiler header to the feed water tank to keep the temperature high if steam sparge isn’t being used. Cold feed water takes more energy to boil and drops your boiler pressure.
Choose the Right Boiler
All boilers are not created equal. We prefer atmospheric water tube boilers for several reasons for process applications, when allowed. For starters, they get hot really fast and recover well. Secondly, the don’t have blowers and modulators, which are loud, use more electricity and are points of failure. Third, they are almost silent.
Fire tube boilers can produce a lot of steam, but they are slower to recover in our experience. Once at temperature, which can take a while from a startup (NOTE: DO NOT TURN YOUR BOILER OFF), they deliver steady heat, but start and stop a lot, unless they are sized perfectly. The refire time can exceed 100 seconds, so in a low pressure system, there can be a 6-8PSI drop before the boiler even fires back up. 6PSI in a kettle is a simmer, and you want a rolling boil. A still wants to maintain a steady rolling boil too, to ensure your alcohol runoff is steady.
Cast boilers make a good home heating boiler or a solid mooring, but that’s about it.
We recommend Rite boilers to all of our customers. We have been installing them for over 10 years and they perform exceptionally. For the end user, they are easy to operate, with a nice clean package and quiet. For us, they are easy to inspect, clean and service with minimal proprietary parts. The straight tube design lets you access the entire water side for cleaning. They have a massive amount of surface area, which means the recovery times exceed almost every other boiler we’ve worked with.
Hire a Steam Installer
People who install hot water systems are probably going to give you hot water from your steam boiler. I only say this because it’s been true more than not. I have had a lot of calls about functionality that come down to install. Steam is a different kind of animal from hydronic systems. If someone hasn’t done it, find someone who has and can tell you why and how it works. They should understand system layout, where to put automatic valves, how to pitch the piping so things stay dry, how to size the piping so the steam velocities are ideal and many other details I can’t get to, because this is not an instruction manual.
But choosing the right installer will save you way more than hiring an inexperienced one. Production plants are industrial environments and they aren’t served well by residential solutions. I am still amazed at the plumbers and HVAC companies at our job sites that are just blown away by what to do in a steam or glycol system. It’s funny sometimes, watching them try to figure things out, except it’s not because I know someone who just paid a lot of money is going to be stuck dealing with poor results for a long time. Through all your construction and service, selecting skilled contractors is critical to your success, and it can be a difficult choice.
We’ve got a lot to talk to talk about, but it’s a new site.
We’re working on it.