In its simplest form, a boiler has a way to make fire, a pressure vessel full of water, and a steam header to direct the steam where it needs to go to get work done. But there is a whole range of equipment out there, much of which is also necessary, designed to help a boiler do its job and operate more efficiently. Known as “auxiliary equipment”, these add-ons can do wonders for your boiler’s performance and longevity, and your fuel costs.
ECONOMIZERS
As the name suggests, economizers help your boiler do more with less by reusing heat that might otherwise be lost. Made by companies like Heat Sponge, economizers capture exhaust heat from the stack and use it to heat feedwater so your boiler doesn’t have to work as hard or use as much fuel to bring the feedwater up to the temperature at which it becomes steam.
In an economizer:
- Hot flue gases leave the boiler’s furnace after combustion
- Those hot flue gases are routed over economizer tubes
- Cold feedwater is fed through the economizer tubes, warming it up before it enters the boiler’s pressure vessel
- Every degree you can heat your feedwater is one less degree that the boiler’s furnace is going to have to heat it
HEAT EXCHANGERS
Heat exchangers, also known as heat recovery units, are similar to economizers in that they capture excess heat and repurpose it to reduce the amount of heat your boiler’s furnace has to create when converting water to steam. They’re typically manufactured by companies like The Penn Separator Corporation.
Heat exchangers can be located in several different locations around your boiler based on where they are capturing and repurposing heat:
- Blowdown heat exchangers and flash tanks capture heat from hot surface blowdown water and transfer that energy to makeup water
- Condensate heat exchangers capture heat from condensate and use it to heat feedwater
DEAERATORS
While water is made up of oxygen and hydrogen, your boiler system can still end up with excess free oxygen in its water.
That free oxygen is one of your boiler’s biggest enemies for several reasons:
- Excess oxygen causes corrosion inside your pressure vessel and pipes
- Excess oxygen can absorb heat without producing any additional steam, wasting fuel and lowering your boiler’s operating efficiency
Getting that excess oxygen out of the water is therefore pretty important. That’s where the deaerator comes in. Made by companies like BFS and Industrial Steam, deaerators remove excess oxygen from your boiler’s water so it can’t harm your equipment or your efficiency.
Deaerators work using one of two methods:
- Spraying water into a fine mist and rapidly heating it so the oxygen can escape
- Routing water in extremely thin sheets over a series of metal plates so that the oxygen can escape as it absorbs steam, thereby heating it.
FEEDWATER SYSTEMS
A feedwater system is a collection of equipment that works together to make sure your boiler never runs out of water, while protecting the boiler from the shock of cold feed water. Made by BFS and Industrial Steam, feedwater systems preserve efficiency and performance by keeping your boiler supplied with properly treated, preheated, deaerated water. Reclaimed condensate alone isn’t enough to keep your boiler’s steam circuit fully supplied with water that it can convert to steam. So while the condensate return system is part of the feedwater system, the feedwater system must also include a way to introduce makeup water that replaces steam lost to end work processes.
A typical feedwater system will typically include
- A condensate return
- A makeup water supply
- A deaerator or vented feed tank
- Water treatment equipment to remove dissolved calcium and magnesium ions and add oxygen scavenging chemicals to reduce oxygen levels
- Pumps, because water must be forced into the boiler under pressure to overcome steam pressure in the pressure vessel.
CONDENSATE RETURNS
Some boiler systems have to run on 100% externally supplied makeup water to replace the water lost to steam.
Examples include:
- Humidification systems
- Steam injection systems in food processing and manufacturing
- Any application in which the steam may become contaminated with oils, chemicals, or process fluids during use
Many boiler systems, however, are able to recapture condensing steam after it leaves the work process and cools back into liquid water, so that water can then be reused to keep the pressure vessel properly supplied. In those cases, having a condensate return can lower the amount of extra added water the boiler needs to keep producing steam. To preserve boiler pressure, condensate is resupplied to the boiler using pumps made by companies like Armstrong International.
STEAM SEPARATORS
Steam is versatile enough to power countless different work processes. However, many of those work processes require what’s known as “dry steam”, or steam without any excess water droplets in it. One extremely common example is found in power generation. Steam turbines require dry steam to move the turbine blades. However, any excess water droplets can end up damaging the turbine blades and reducing the lifespan of the steam turbine. For processes that require dry steam, therefore, there has to be a way to remove any excess microscopic water from the steam supply.
That’s where the steam separator comes in. Made by companies like Armstrong International, steam separators separate out the water from the steam, so only dry steam reaches the end process.
There are several different methods of steam separation:
- Centrifugal steam separators spin the steam, forcing the water droplets to be expelled outwards and away from the steam
- Baffles can be used to strip away the water droplets as steam passes through them
- Gravity operated steam separators use gravity to let the heavier water droplets fall away from the lighter steam
STEAM TRAPS
Steam traps serve the crucial function of removing condensate and excess air from steam systems without losing steam pressure. By doing this, they help prolong the life of the boiler itself, and the integrity of end work processes that might be damaged by the intrusion of condensate.
Drip legs, engineered low points in the steam system, collect condensate for removal. Steam traps made by companies like Armstrong International basically act as gates that only allow condensate and non-condensable gases to escape the drip leg or heat exchanger. As long as hot, dry steam is present at a steam trap, it will remain closed. However, should any condensate or air enter, the steam trap will open, allowing the air or condensate to escape. Then, when the piping to the trap is full of pure steam again, it will close, retaining that steam for use.
- Float steam traps operate by detecting the difference in density between steam, condensate, and air
- Inverted bucket steam traps operate by using a bucket floating in condensate to close the trap when steam enters. When condensate is present, the bucket will sink, opening the trap
- Thermostatic steam traps operate by detecting the difference in temperature between steam, condensate, and air
FUEL DELIVERY SYSTEMS
In order to keep your boiler running at its best, it needs a steady, even supply of fuel. If you’re running natural gas or propane, the fuel delivery system will likely include a pressure regulator made by a company like Maxitrol. That regulator makes sure that the pressure of the incoming fuel doesn’t go too high or too low, which might cause the burner to perform poorly. Safety shutoff valves, such as those manufactured by Siemens and Honeywell, start and stop the flow of gas as needed. If your boiler runs on fuel oil, the fuel delivery system will include a pump, a pressure regulator and an atomizer to supply the oil under constant pressure, and mix it with air to aid in efficient combustion.
If you are considering adding peripheral equipment to your boiler to improve efficiency and performance, a professional from WARE is ready to help you select the right equipment. Our highly trained technicians will then install it properly, so you can get the most out of every fuel dollar and every pound of steam. No matter what you need, from parts and supplies to training to maintenance and repair, WARE is standing by to help.