A flue gas economizer or heat recovery unit is a type of heat exchanger whose main function is to harness the thermal energy that would otherwise be lost when released to the atmosphere.
Economizers are typically used in conjunction with water-tube and fire-tube boilers. These devices are designed to raise the temperature of water or other thermal fluids – such as thermal oils or molten salts – without a phase change.
An economizer is placed after the flue gas exiting the boiler, taking advantage of its waste heat to transfer it to the feed water or oil. In this way, the economizer reduces the amount of energy required to heat the thermal water or oil to boiling point, improving the thermal efficiency of the boiler and reducing fuel consumption.
Operation of an oil-water economizer
It consists of:
Depending on the type of process, duty, space and customer requirements, a type of economizer is designed.
Aitesa designs the following types of economizers:
These economizers are designed to capture heat from the flue gases and transfer it to the water. The water, in turn, absorbs this thermal energy inside the economizer and delivers it to the place where it is required.
In the specific case of a boiler, the heat generated by combustion can be used to raise the feedwater temperature to near saturation levels just before it enters the boiler.
This case is similar to the previous case, except that the thermal fluid is a thermal oil, which collects the heat in the economizer and transfers it to the place intended for it.
This device works as an economizer that raises the temperature of water or a thermal fluid entering at a low temperature (below 65 °C). This condition causes the condensation of the water vapor present in the flue gas, causing the condensed water to adhere to the walls of the tubes. To prevent damage caused by corrosion due to this phenomenon, this type of equipment is manufactured in stainless steel.
Not sure which one you need? Our team of experts can analyze your process and recommend the best solution.
At AITESA we are experts in economizer design.
The use of economizers allows the recovery of heat from the exhaust gases, which would otherwise be lost, to preheat the feedwater or thermal fluids. This reduces the amount of fuel required to reach the desired operating temperatures, improving the thermal efficiency of the system.
By improving energy efficiency, economizers contribute to a significant decrease in operating costs. The reduction in fuel consumption not only implies a direct saving in energy costs, but by applying preventive maintenance methods, the wear and tear of the main equipment can also be minimized, prolonging its useful life and reducing maintenance costs.
Energy efficiency achieved through economizers also has a positive impact on the environment. By reducing the consumption of fossil fuels, emissions of greenhouse gases and other pollutants are reduced. This contributes to a company’s lower carbon footprint and improves its environmental profile, which is increasingly valued in the marketplace and can facilitate compliance with environmental regulations.
We adapt the economizers to different environments and needs. Their modular design allows them to be installed horizontally or vertically, depending on the available space. In addition, they can be configured according to the specific requirements of each process, such as pressure, temperature or required flow rate. They are also compatible with existing equipment, which facilitates their integration without the need for major changes to the existing system.
The use of economizers contributes to the reduction of CO₂ emissions, enabling industries to align with international environmental regulations such as ISO 14001 and the objectives of the European Green Pact. This improvement in environmental performance does not compromise operational efficiency, as systems continue to operate efficiently while decreasing their impact on the environment. Furthermore, this reduction in emissions facilitates compliance with stringent regulations, which improves the acceptance of companies in demanding sectors such as energy, petrochemicals and other regulated industrial processes.
Transport of an economizer and an industrial reboiler
At AITESA we are experts in the design of economizers.
Preparation for transport of an economizer
Economizers also offer important advantages in complex applications such as catalytic cracking, distillation and hydrogen production, where waste heat utilization is critical. They can be designed with materials resistant to highly corrosive gases, making them ideal for demanding environments such as those in the petrochemical industry. In addition, by recovering heat that would otherwise be lost, they help to significantly reduce energy consumption in refining processes and fuel production, improving overall plant efficiency.
In industries such as cement and glass, economizers allow the recovery of waste heat generated in clinker kilns and glass furnaces, using it to preheat air or process fluids. This recovery significantly improves the efficiency of the fuel used, as less energy is required to reach the necessary temperatures. As a result, a significant reduction in emissions is also achieved in highly energy-intensive processes, contributing to both resource savings and compliance with environmental regulations.
Do you need a customized solution for your industry? Contact us and we will design the ideal equipment for your process.
Economizer assembly for a calcination boiler
In AITESA we study your case to offer you the best economizer.
Economizer in manufacturing process
We not only design economizers, we create energy solutions that optimize your production, reduce costs and ensure regulatory compliance.
The composition of the gas to be heated, inlet temperatures, heat exchanged, flow rates, operating pressure, type of installation, space limitations, and possible restrictions on materials due to corrosion or regulations must be indicated.
The number of steps refers to the number of times the fluid changes direction within the economizer.
It depends on the type of gases and process conditions. In corrosive environments or with acid condensation, stainless steels or special alloys are used to extend the life of the equipment.
Periodic inspections, tube cleaning (mechanical or chemical), gasket checks and leak tests. Models with removable heads allow easier and more efficient cleaning.
By reducing fossil fuel consumption and CO₂ emissions, it enables companies to align with international environmental regulations such as ISO 14001 or the objectives of the European Green Pact.
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Aitesa has more than 40 years of experience designing and supplying heat recovery boilers.
