There are several ways to improve the energy efficiency of a steam boiler. Among these are: lowering the stack temperature, installing an Economizer and a variable frequency drive, tuning the burner, and cleaning the fireside.
Performing these steps regularly can help you increase the efficiency of your boiler. Below are a few suggestions for you. The best boiler maintenance is also crucial for boiler efficiency.
LOWER THE STACK TEMPERATURE
The higher the stack temperature of a high-efficiency steam boiler, the lower its efficiency. Higher temperatures cause heat to escape into the atmosphere, reducing overall boiler fuel-to-steam efficiency. Lower temperature, on the other hand, increases efficiency.
The stack temperature is a good indicator of boiler efficiency because it’s the temperature of combustion gases that exit the boiler. A lower temperature indicates a better heat exchanger design and better fuel-to-steam efficiency.
High-efficiency steam boilers have the capability to reduce energy costs while increasing occupant comfort and reliability. Older hot water boilers are notorious for losing a significant amount of energy out of the flue. Often, their flue-gas temperatures remain high, reducing efficiency.
However, newer condensing steam boilers achieve lower stack exhaust temperatures. By lowering the return water temperature, these boilers can achieve maximum efficiency. Emerson Swan has a well-known correlation between the return water temperature and boiler efficiency.
The higher the hydrogen content of gaseous fuels, the greater the amount of water vapor produced during combustion. Water vapor uses energy to change phases during combustion, reducing efficiency.
Higher hydrogen content fuels (such as fuel oil) have higher efficiency than natural gas. Make sure to choose a fuel that is representative of the job site. LOWER THE STACK TEMPERATURE of a high-efficiency steam boiler
INSTALL AN ECONOMIZER & VARIABLE FREQUENCY DRIVE
The use of an economizer is an effective way to improve the energy efficiency of your boiler. Economizers capture both sensible and latent energy from flue gas. They can be either counterflow or parallel flow. In a counterflow design, the feed water flows opposite the flue gas. The manufacturer will provide the design for the economizer based on the input and output temperatures of the end user.
An economizer is a device that redirects hot flue gas from the boiler into the feed water, increasing thermal efficiency. This device can result in a reduction of approximately 1% of fuel costs for every ten degrees increase in feed water temperature.
An economizer can generate a significant return on investment in just a few months. To maximize energy efficiency, economizers should be installed in high-efficiency steam boilers.
A high-efficiency steam boiler can improve a facility’s bottom line by increasing its combustion efficiency. The higher the efficiency of a boiler, the greater the heat released from it. The more surfaces the boiler has, the faster it can release that energy.
In addition, more efficient fuels can lead to a reduction in the boiler’s utility costs. The installation of an economizer and variable frequency drive will help improve boiler efficiency.
TUNE THE BURNER REGULARLY
To get the most out of your steam boiler, tuning it regularly is a key part of maintaining the system. It is necessary to balance the burner to ensure optimum output and minimize combustion air emissions. If you don’t tune the burner properly, you may experience low heat output, excessive fumes, or excessive fuel expenditure.
Generally, tuning takes place in the spring and fall, when the system is not used as frequently. This prevents the boiler from ignoring actual operating CO and O2 levels.
For calculating the boiler’s efficiency, you must subtract the total energy input from the total energy output, and multiply the result by 100. This is called GCV, or Gross Calorific Value.
If your boiler is not achieving these standards, you must use a flue gas analyzer to determine the exact ratio of air and fuel. Tuning your boiler regularly will increase its efficiency and reduce your energy bills.
CLEAN THE FIRESIDE
In order to maximize your steam boiler’s efficiency, you must clean the fireside regularly. This is an essential step because soot buildup can significantly decrease heat transfer. It also increases the amount of fuel used because hot gases pass through the tubes without transferring heat to the water.
Furthermore, it can also result in an increase in the stack temperature. Cleaning the fireside regularly will ensure optimum boiler performance and lower your operating costs.
The best way to clean the fireside of a high-efficiency steam boiler is to change the type of fuel used. This is important because practically every fuel leaves deposits on the fireside of the tubes.
Fouling reduces the amount of heat transfer and increases the flue gas temperature, which in turn increases your energy costs. By changing the type of fuel and adjusting the amount of air you burn, you can significantly increase the efficiency of your steam boiler.
A periodic inspection of the fireside of a high-efficiency steam boiler can help you determine whether or not it needs cleaning. Visual inspections can be part of an annual maintenance program or ongoing.
In addition to visual examinations, you should look for changes in flue-gas temperature and boiler tubing replacements. These factors can indicate a scaling issue. If you notice a trend in the temperature of your flue gas, then you need to clean the fireside.
PREHEAT COMBUSTION AIR
The temperature of combustion air in a high-efficiency steam boiler is critical to its efficiency. Heating the combustion air before it enters the boiler reduces fuel consumption by as much as 1%.
However, preheating the air increases its temperature by more than 20 degrees. Therefore, preheating is not a substitute for higher boiler temperatures. This article will discuss two ways to increase boiler efficiency.
A high-efficiency steam boiler can reduce fuel consumption by up to 20%, which is considered a significant improvement. But the amount of air that enters the boiler can have a negative impact on its efficiency. Low air can cause soot, smoke, carbon monoxide, and other harmful gases to be produced.
Conversely, too much air reduces boiler efficiency. Therefore, if you choose a high-efficiency steam boiler, it’s important to consider the amount of air that is entering and exiting the boiler.
A preheater is an air preheater that helps increase the boiler’s thermal efficiency. It also reduces the amount of useful heat that escapes the boiler’s flue gas, a feature that can simplify a high-efficiency steam boiler’s design.
An air preheater is installed between the economizer and the chimney to maximize efficiency and reduce fuel consumption
RETURN CONDENSATE TO THE BOILER
A high-efficiency steam boiler returns condensate back to the process, which reduces flash losses and increases overall energy savings. Condensate return piping should be insulated to minimize heat loss into the environment.
Installing meters in the boiler is not a direct way to improve the efficiency of a steam boiler, but it can give you insight into your current operating conditions and the cost of steam production.
While the return of condensate to a boiler may not seem like much, it can save a lot of money. It can cut the cost of make-up water, chemical treatment, and energy. By reusing this water, a high-efficiency steam boiler can dramatically reduce its operating costs.
Additionally, the process can improve working conditions, reduce energy consumption, and reduce its carbon footprint. As condensate contains a significant amount of sensible heat, it can save anywhere from 10% to 30% of the initial boiler cost.
Many systems do not return all of the condensates, so it’s essential to keep this water as clean as possible. The more condensate you return to the boiler, the more energy it’s going to save you, and you’ll get the same amount of steam for less fuel.
You might have to use more energy to keep the feedwater warm, but it’s worth it if you can reduce the amount of water that gets returned to the boiler.
RECOVER HEAT FROM BOILER BLOWDOWN
To increase the efficiency of your steam boiler, consider recovering the heat from the blowdown. Blowdown is a by-product of the steam production process and can contain about 5% of the total heat produced in the boiler.
Because it is the same temperature and pressure as the steam generated by the boiler, this water can be recovered through a heat exchanger, flash tank, or both. The figures below show how much heat can be recovered from blowdown based on different condensate return rates.
When a boiler blowdown occurs, high-temperature water from the surface blow-off system carries valuable heat energy. That energy would otherwise be lost to the drain. But a heat recovery system, like the Hurst system, can reclaim the heat by recovering it and transferring it to the boiler’s make-up water.
This can add up to significant fuel savings, which can total thousands of dollars per year.
SURVEY & REDUCE STEAM TRAPS
Leaky steam traps can result in a significant loss of energy. According to the U.S. Department of Energy, as much as 20 percent of steam is lost through steam traps.
In addition to reducing energy output, steam trap leaks can also create potential safety hazards and lower operational reliability. In this article, we will discuss the importance of steam trap design and sizing steam trap types, and testing methods.
To improve the efficiency of your boiler, you should consider implementing a high-pressure condensate return system. This system will return condensate at a higher pressure than usual, allowing you to keep the water at a higher temperature.
A Mechanical Construction Services representative can help you determine whether a high-pressure condensate return system is appropriate for your process.
you can determine the most effective ways to survey & reduce steam traps in your high-efficiency steam boiler. By reviewing steam trap performance and calculating steam losses, you will be able to determine whether to replace a faulty steam trap.
We look at the inlet pressures and heat of vaporization for steam traps used in dry cleaning establishments. Then, we divide this data by the number of steam traps per year and the associated efficiency of 80%.
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