Boiler technology has come a long way in the past 100 years. The modern boiler room is a masterpiece of energy movement, a symphony of phase change, energy reclamation, and efficiency at every turn. That lets today’s boilers create more horsepower for less energy than ever before. So what exactly does a modern boiler room look like? You’ve come to the right place.
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The first thing you’ll notice in a modern boiler room is the same thing you’ll notice in every boiler room in the past century: the vessel. This is where the magic happens, so to speak. Because it’s in the vessel that the water inside changes from liquid to gas form, and goes off on its mission to complete whatever end process is needed. This is a good time to talk about the fire side and water side of the boiler, because the vessel happens to be where the two intersect. As you can probably surmise, the fire side relates to all the combustion processes involved in steam production, while the water side relates to all the water and steam movement.
THE FIRE SIDE
The fire side is where incoming fuel is turned into heat, which passes through the vessel walls and is absorbed by the water in the vessel. The fire side system includes all the sensors, gauges, valves, and regulators related to the control and monitoring of the heat that goes into the boiler. In a gas-fired boiler, the fire side starts with the gas train, which is where the incoming utility line connects. One feature of the gas train is the gas pressure regulator, which is there to ensure the fire side gets the right amount of fuel pressure to do its job properly, and efficiently.
On either side of the gas pressure regulator, you’ll find a gas pressure gauge. The gauge mounted inline before the gas pressure regulator tells you the line pressure coming in from the fuel supply, usually the utility line. The pressure gauge mounted on the other side of the gas pressure regulator tells you the pressure at which the fuel is actually being fed into the boiler system.
Once you’re through the gas train, you come to the burners, which mix the incoming fuel with oxygen, then ignite the mixture and shape the resulting flame to the ideal size for even heat transfer. The burners will also include an air delivery system to make sure the fuel has enough oxygen to properly atomize and mix with to burn efficiently. Air flow is regulated by a series of dampers that are adjusted during operation to make sure the combustion process has enough oxygen. These dampers are also used during shutdown and pre-purge procedures to let plenty of air flow in to vent unburned gas and combustion byproducts if the burners need to shut down.
As the fire side operates, it will produce exhaust gases, because that’s what combustion does. Those gases can’t just hang around, so they are routed out through the stack, which may include a scrubbing or filtration system to remove excess carbon before venting. Large industrial scrubbers actually use steam itself to clean the exhaust, which is yet another way steam helps make the earth a better place.
Since a boiler is all about collecting and moving heat, it wouldn’t make much sense to vent unused heat into the atmosphere. That would just be wasted money. That’s why modern stacks include heat recovery equipment that absorbs heat from the gases in the stack, redirecting that heat to be reused in the process of turning water into steam. Which brings us to…
THE WATER SIDE
The water side of the boiler is where you’ll find everything that is touched by water, steam, or both. All those burners we just talked about a second ago? They’re blasting heat into the vessel, which is the tank of tubes or drums that holds the water as it begins its phase change into steam. As the water in the vessel absorbs more and more heat, it eventually begins to change from liquid to gas form, collecting above the water in the vessel. Because it’s under pressure, that steam is able to absorb a lot of additional heat, which is one of the main reasons that steam remains the most efficient way to transfer large amounts of heat in industrial and commercial applications.
Once the steam has reached a high enough temperature and pressure, it’s ready to go to work. At this point, it travels through the steam manifold to be directed towards one of the work processes found along the steam circuit.
As the steam does its work, it releases its stored heat and pressure. Eventually, it loses enough energy that it reverts from a gas back to a liquid, forming condensate. This condensate collects into larger and larger droplets of water and is collected by traps, eventually flowing back through the condensate return lines to begin another trip through the system. But it doesn’t just go back into circulation. It has a few things to do first.
Every little bit of reclaimed heat is heat you don’t have to generate by burning fuel. That’s why modern boiler systems have some smart equipment dedicated to squeezing every last bit of heat out of water so it doesn’t go to waste. In the boiler system, that happens in the economizer.
An economizer passes hot deaerated feedwater, which includes returned condensate, through a series of pipes that preheat the feedwater that’s waiting to be added to the vessel. Since it absorbs reclaimed heat even before entering the vessel, that means the water won’t require as much added energy to convert to steam. Which means the burners won’t have to burn quite as much fuel to keep the steam flowing. In fact, modern economizers can get the water up to 300 degrees Fahrenheit or higher before it goes into the vessel, saving a lot of heat energy and money over time.
Another process the feedwater must go through before reentering the vessel has to do with dissolved oxygen. Once the water stopped being steam and became condensate, it began to absorb oxygen if it was exposed to the air around it. After all, oxygen is water-soluble, so once it finds some water, it’s going to dissolve on in. The thing is, though, excess oxygen isn’t exactly friendly to the pipes, gauges, valves, and other metal surfaces inside your boiler system. By itself, it can cause oxidation of the metal surfaces, also known as rust. Excess oxygen also likes to accelerate the corrosive reactions that happen on the molecular level inside your boiler’s vessel. That oxygen has to go, which is where the deaerator comes in.
There are several types of deaerators out there, but they each do the same thing: heat up and atomize the water to draw out the extra oxygen and vent it away before it can get into the feedwater supply. Once it’s been deaerated, the water is ready to be pumped back into the boiler vessel as makeup water to maintain the vessel’s water level. If you have driven by a plant and witnessed a small pipe with steam coming out of it, that may be the vent from the deaerator doing its job of removing excess oxygen from the feedwater supply to the boiler.
Smaller boiler systems that don’t require a lot of makeup water may have a condensate return system instead of a deaerator. In a condensate return system, steam is pumped under pressure through the condensate, using the heat from the steam to draw the oxygen out and vent it away.
Another important component you’ll find in a modern boiler system is the water treatment system. Truth be told, the quality of the water in your boiler can be one of the most influential factors in the longevity and overall efficiency of your boiler. No matter where you live or work, the water coming in from the utility will have some impurities in it, most often dissolved mineral solids like calcium and magnesium, along with some iron. If those solids are allowed to get inside your boiler’s vessel, they’ll cause chemical reactions that will result in corrosion, rust, and scale.
Corrosion and rust literally eat metal away, weakening the overall integrity of the vessel and other boiler components. Scale, on the other hand, is buildup that develops over time that begins to act as an insulator, robbing the boiler of efficient heat transfer and, consequently, hampering efficiency. If left unchecked this buildup will eventually cause overheating and metal failure.
A proper water treatment system will include a water softener, which uses sodium ions to strip away the magnesium and calcium before they can enter the feedwater. Modern water treatment also involves several other chemicals that further reduce the level of harmful solids dissolved in the water, all of which create water that is less reactive with the boiler system itself, and more suited to conversion into pure, powerful steam.
THE BIG BRAIN
A modern boiler system will also have a pretty impressive amount of technology attached to it. Today’s control systems use data links, sensors, and remote-operated servo motors rather than physical linkages to adjust the flow of water, air, and fuel in the boiler system. They take multiple readings every second, constantly processing the information to calculate tiny adjustments that can be made to optimize boiler performance and efficiency. By making these tiny adjustments over time, the boiler control system can keep the boiler operating at peak efficiency, saving energy dollars over time.
These advanced systems give the boiler operator more information about what’s going on in the system and where, which helps identify and diagnose any system issues as they happen. That keeps small problems from developing into bigger problems, extending the usable life of the boiler. These advanced systems also give boiler operators more control over all the operating parameters of the boiler, allowing them to make manual adjustments and tweaks whenever needed. Best of all, it’s all done through a sleek touchscreen interface that’s a lot like an iPad, making the boiler room feel less like a dark corner of the basement, and more like a computerized command center.
If you have an older boiler system in need of an upgrade, or if you’re in the market for a new or rental boilers, we have your back. We also have the expertise to back them up, whether you need service or maintenance. Check out our online Boiler Warehouse store for any parts you may need. If you’d like to learn more about how all of the components of a boiler work together, consider taking some boiler education classes at WARE Boiler University. We have a range of online classes and in-person classes available that will take you inside every aspect of boiler room operation, boiler room components, and boiler technology. Remember, we’re always here to help. Just let us know.