What is Economizer in Boiler?

January 14, 2025

What is Economizer in Boiler?

Boiler economizer is a kind of heat exchange equipment specially designed to improve boiler energy utilization efficiency. It is usually installed in the flue at the tail of the boiler, and its main function is to recover the waste heat in the flue gas during the operation of the boiler, improve the overall energy efficiency of the boiler system, and thus achieve the purpose of energy saving and emission reduction.

The boiler economizer passes through the economizer to transfer the heat in the high-temperature flue gas to the boiler feed water through the internal heat exchange device to realize the preheating of the feed water. The preheated boiler feed water temperature is close to the required working temperature of the boiler, which greatly reduces the fuel consumption required by the boiler when heating the water to the required temperature, thus effectively improving the thermal efficiency, reducing the operating cost, and significantly reducing the energy waste and pollutant emission in flue gas emission. The application of economizer can not only save energy and reduce the production cost of enterprises, but also help to achieve the goals of energy saving, emission reduction and environmental protection, and it is an indispensable part of modern boiler system.

Working Principle of Boiler Economizer

The working principle of boiler economizer can be embodied in three aspects: heat recovery, temperature difference utilization and heat transfer mode. First, through heat recovery, when the high-temperature flue gas generated in the boiler combustion process passes through the economizer, the residual heat is absorbed by the heat exchanger and transferred to the boiler feed water, thus preheating the feed water. This heat recovery process significantly reduces the fuel consumption required for the boiler to further heat the water. Secondly, the economizer uses the temperature difference between flue gas and feed water to realize efficient heat exchange. Usually, the flue gas temperature is between 300-600°F, while the feed water temperature is between 100-230 F. This remarkable temperature difference provides favorable conditions for heat transfer and effectively improves the feed water temperature. Finally, the economizer completes the heat transfer through the shell-and-tube or plate heat exchanger, and the heat energy in the flue gas is transferred to the low-temperature feed water through these high-efficiency heat transfer devices, so as to realize the high-efficiency energy utilization and improve the thermal efficiency of the system.

Main Types of Boiler Economizer

Condensing economizer

By cooling the flue gas below its condensation temperature, the condensing economizer condenses the water vapor in the flue gas, thus releasing latent heat. This released latent heat is further utilized to heat boiler feed water or other process water, thus improving the overall heat recovery efficiency.

Pros

Condensing economizer becomes the most efficient economizer by using the latent heat of condensed water, which can significantly improve the thermal efficiency of the system, usually by 10%-15%. Higher efficiency directly reduces fuel consumption, thus reducing operating costs and carbon emissions, and at the same time effectively reducing thermal pollution in flue gas emissions, achieving the goal of energy conservation and environmental protection.

Cons

Condensing economizer will produce condensed water containing acidic components (such as sulfuric acid and nitric acid) in operation, which is highly corrosive to equipment, so it is necessary to use corrosion-resistant materials (such as stainless steel or special coating) to manufacture equipment. In addition, it is necessary to design a reliable condensate collection and discharge system to avoid affecting equipment and the environment. Due to the special requirements of these materials and designs, their manufacturing and installation costs are relatively high, resulting in relatively large initial investment.

Non-condensing economizer

Non-condensing economizer only reduces the temperature of flue gas to above its dew point temperature, thus avoiding the condensation of water vapor in flue gas. In this way, the equipment can not only recover some sensible heat, but also reduce the material loss and maintenance requirements caused by condensed water corrosion.

Pros

Non-condensing economizer has the characteristics of relatively simple design and structure, low manufacturing and maintenance costs, and at the same time, because there is no condensed water, the risk of corrosion of equipment is significantly reduced, thus reducing the maintenance frequency. Its applicability is wide, especially suitable for industrial boiler systems with low requirements for heat recovery efficiency.

Cons

The heat recovery efficiency of non-condensing economizer can only be improved by 2%-4%, which is significantly different from that of condensing economizer, so the improvement of thermal efficiency is limited and the fuel saving effect is not as obvious as that of condensing economizer.

Other Types of Boiler Economizer

Shell-and-tube economizer

Shell-and-tube economizer consists of a shell and a series of heat transfer tubes inside. Flue gas usually flows in the shell, while boiler feed water flows in the pipe, and heat is transferred from flue gas to feed water through the pipe wall.

pros: stable structure, suitable for high-pressure environment and high heat transfer efficiency.

Cons: it takes up a lot of space and is complicated to clean and maintain.

Plate economizer

The plate economizer is formed by arranging a plurality of metal plates, forming a plurality of flue gas and water flow channels, flue gas and feed water flow between the plates, and heat is transferred through the plates.

pros: small occupied space, suitable for scenes with limited installation space, and easy to disassemble and clean.

Cons: Limited high pressure resistance, usually suitable for medium and low pressure systems.

Installation and Economic Benefit

As an efficient energy-saving equipment, economizer can not only improve the overall efficiency of boiler system, but also significantly reduce fuel consumption, bringing considerable economic benefits to enterprises. Through reasonable installation design and operation optimization, the economizer can recover the investment cost in a short period of time and lay the foundation for the enterprise to realize the long-term energy-saving goal.

Installation Method

The installation of economizer can be flexibly applied to the design of new boiler system and the transformation of existing boiler system. When installing a new boiler, the economizer can be directly integrated into the system as a part of the overall design; For the existing boiler system, it can also be retrofitted to improve the system efficiency.

The installation steps usually include the following key links:

Use lifting equipment (such as crane) to lift the chimney to reserve space for the economizer.
Install the economizer to the predetermined position, and use the bracket or fixing device to ensure its stability.
Connect the economizer with flue gas channel and boiler water supply pipeline to ensure sealing and reliability.
Reinstall and connect the chimney to restore the normal exhaust passage of flue gas.
Debug the system to ensure that the operation of the economizer meets the design requirements and optimize the performance.

Economic Benefits

Energy recovery rate:Economizer can recover 30% to 50% of available energy loss in boiler exhaust gas, and reuse this heat for heating boiler feed water or other process requirements, greatly improving energy utilization efficiency and reducing boiler fuel consumption.
Cost saving:By improving boiler efficiency, economizer can bring significant energy cost savings. For example, for a 1200HP fire tube boiler, installing an economizer can save $6,000 to $10,000 in fuel costs every year. This saving benefit is especially obvious in the long-term operation, which is of great significance to the reduction of energy expenditure of enterprises.
Payback period of investment:Although the installation of economizer requires a certain initial investment, its efficient energy recovery ability makes the payback period of investment usually short. According to the operation scale of boiler system and fuel cost, the investment cost of economizer can usually be fully recovered by saving fuel cost within 12 to 24 months, and then the energy-saving income will continue to bring economic benefits to enterprises.

Advantages and Benefits of Economizer

Under the background of rising energy costs and increasingly stringent environmental protection requirements, the application of economizer shows its irreplaceable advantages in energy saving and emission reduction, improving efficiency and optimizing production.

Reduce fuel consumption:Economizer can recycle the heat in boiler exhaust gas and use it to heat boiler feed water or other process requirements, thus reducing fuel consumption by up to 20%. This remarkable energy-saving effect directly reduces the energy cost of enterprises and improves economic benefits.
Reduce emissions:By reducing the use of fuel, economizer can effectively reduce the emissions of greenhouse gases (such as carbon dioxide) and other waste gases, help enterprises achieve environmental protection goals, and meet increasingly stringent emission standards.
Improve boiler efficiency:The economizer improves the boiler efficiency by 10% through heat recovery, which significantly improves the overall performance of the system, thus making the boiler run more efficiently and reliably.
Extend system life:Because the economizer reduces the temperature of boiler exhaust gas and the heat load and wear of related components, it can prolong the service life of boiler equipment and reduce the frequency of shutdown and replacement caused by aging components.
Reduce maintenance costs:The economizer is simple in design and stable in operation, and almost does not need frequent maintenance, which can significantly save maintenance costs in long-term operation and reduce the extra expenses caused by downtime maintenance.

Factors Affecting the Efficiency of Boiler Economizer

Flue gas temperature:The higher the initial temperature of flue gas, the more available heat it contains. Therefore, higher temperature flue gas provides more potential heat recovery capacity for economizer.

Boiler feed water temperature:The lower the temperature of boiler feed water, the stronger its ability to absorb heat, which directly improves the recovery efficiency of economizer. Therefore, selecting the appropriate feed water temperature can optimize the heat recovery effect.

Economizer type:Condensing economizer is more efficient, which can make extra use of the latent heat of water vapor in flue gas, but it needs to design corrosion-resistant materials and treat condensed water. The non-condensing economizer has a simple structure, but the heat recovery efficiency is relatively low.

Economizer size:The size of economizer has a direct impact on heat recovery efficiency. If the size is too small, the heat in the flue gas may not be fully recovered, while if the size is too large, it will increase the cost and occupy space, so it is necessary to choose the appropriate size according to the needs of the boiler system.

Installation quality:Reasonable installation and debugging are very important to the performance of economizer. Incorrect installation may lead to flue gas leakage or decrease of heat recovery efficiency, so ensuring high-quality installation and debugging is the basis to ensure the best performance of economizer.

Design Characteristics of EPCB Economizer

EPCB economizer pays attention to the combination of functionality and practicality in design, which embodies the following remarkable characteristics: firstly, anti-corrosion design is adopted, especially in condensing economizer, anti-corrosion materials are selected to effectively prevent the corrosion damage of acid condensate to equipment, thus prolonging the service life. Secondly, the compact design is a great advantage of EPCB economizer. Its optimized structure occupies a small area, which is convenient for installation and maintenance in a limited space, while reducing the clutter above the boiler system and improving the overall aesthetics and practicality. In addition, EPCB economizer pays attention to maintainability and is equipped with detachable heat exchange elements, which makes cleaning and maintenance more convenient and greatly reduces maintenance difficulty and downtime. Finally, the economizer is equipped with flue gas and water inlet/outlet temperature indicators, which can monitor the operating temperature in real time, help users to grasp the performance status in time and quickly troubleshoot, and ensure the stable and efficient operation of the equipment. These design features make EPCB economizer a model of energy-efficient and user-friendly products.

Conclusion

As an efficient heat recovery equipment, boiler economizer greatly improves the overall energy efficiency of boiler system by making full use of the waste heat in flue gas, which not only effectively reduces fuel consumption, but also significantly reduces operating costs. In industrial production, condensing economizer or non-condensing economizer can be selected according to specific application requirements, both of which have unique advantages and applicable scenarios. For example, condensing economizer is suitable for low-temperature flue gas environment and has higher heat recovery efficiency, while non-condensing economizer is more suitable for conventional high-temperature flue gas conditions. Choosing the size and model of economizer reasonably and ensuring high-quality installation and debugging are the key factors to realize efficient operation and prolong service life of equipment.

In design and technology, modern boiler economizer integrates many innovations, such as corrosion-resistant materials, anti-scaling structure, compact design and intelligent monitoring system, which makes it more suitable for changing industrial needs. By significantly improving boiler efficiency, economizer not only brings economic benefits to enterprises, but also plays an important role in energy saving, emission reduction and environmental protection. As an indispensable and important equipment in modern industrial boiler system, boiler economizer embodies the perfect combination of technological progress and sustainable development, and helps enterprises to reach a new height on the road of energy saving and environmental protection. If you are interested in boiler system, please contact EPCB. Choosing EPCB boiler means choosing high quality, high efficiency and reliable service support, which will make your boiler system further on the road of energy saving and environmental protection.